Stavrakakis et al. investigated the capability of three Reynolds Averaged Navier-Stokes models to simulate natural ventilation in buildings. Papakonstantinou et al. presented a mathematical model for turbulent flow and accordingly developed a 3- D numerical code to compute velocity and temperature fields in buildings. A novel gas-liquid mass transfer CFD model was developed by Li et al. to simulate the absorption of CO2 in a microporous microchannel reactor. Yuan et al. visualized the air paths and thermal leakages near a complex geometry using a transient thermal model with buoyancy-driven convection, conduction and thermal radiation heat transfer and flow field near a vehicle structure . In the context of agriculture, researchers have extensively employed CFD analysis for study of ventilation, air flow, and microclimate in indoor systems. Zhang et al. developed a CFD simulation to assess single-phase turbulent air stream in an indoor plant factory system and achieved the highest level of flow uniformity with two perforated tubes. Karadimou and Markatos developed a transient two-phase model to study particle distribution in the indoor environment using Large Eddy Simulation method. Baek et al. used CFD analysis to study various combinations of air conditioners and fans to improve growth rate in a plant factory . More recently, Niam et al. performed numerical investigation and determined the optimum position of air conditioners in a small vertical plant factory is over the top. In addition, a variety of mathematical techniques are proposed to provide sub-model for investigating photosynthesis. According to Boulard et al., tall canopies can induce a stronger cooling of the interior air by using a CFD model to study the water vapor, temperature, and CO2 distribution in a Venlo-type semi-closed glass greenhouse. Despite the fact that photosynthesis plays an integral role in distribution of species and uniformity along cultivation trays, rolling grow trays this issue has not been well addressed. Although numerous research works have been done to investigate the turbulent flow in enclosures and buildings, this study is the first to numerically investigate the transport phenomena considering the product generation and reactant consumption through photosynthesis and plants transpiration with CFD simulations for IVFS-based studies.

Furthermore, a newly proposed objective uniformity parameter is defined to quantify velocity uniformity for individual cultivation trays. Moreover, numerical simulations are performed to simulate and optimize fluid flow and heat transfer in an IVFS for eight distinct placements of flow inlets and outlets in this study. Accordingly, the effects of each case on uniformity, relative humidity, temperature, and carbon dioxide concentration are discussed in detail. Finally, an overall efficiency parameter is defined to provide a holistic comparison of all parameters and their uniformity of each case.In this study, three-dimensional modeling of conjugated fluid flow and heat transfer is performed to simulate the turbulent flow inside a culture room having four towers for hydroponic lettuce growth. Assuming that the four towers are symmetric, a quarter of the room with four cultivation trays is selected as the computational domain, as illustrated in Fig. 1a. Symmetry boundaries are set at the middle of the length and width of the room. The effect of LED lights on heat transfer is considered through constant heat flux boundary conditions at the bottom surface of each tray as shown in Fig. 1b. Lastly, the species transfer due to photosynthesis are occurring only in the exchange zone, which is illustrated in Fig. 1c. To study the impact of air inlet/exit locations on characteristics of air flow, four square areas, denoted as A, B, C, and D in Fig. 1a, are considered to be inlet, exit, or wall. To perform a systematic study, Table 1 presents the location of inlet and exit for all eight cases studied. With the aim of comparing all of the proposed designs, case AB is selected to be the baseline. A fluid stream with horizontal speed ranging from 0.3 to 0.5 m s−1 can escalate the species exchange between the flow and plant leaves resulting in enhancement of photosynthesis. In indoor farming systems, the flow velocity can be controlled well using ventilation fans for more efficient plant growth.

However, heterogeneous distribution of feeding air over plant trays can cause undesirable non-uniformity in crop production, which should be avoided. Therefore, it is important to study the effect of inlet-outlet location and flow rate on the flow patterns throughout the culture room. Herein, the most favorable condition is defined as the condition at which the flow velocity above all trays is equal to the optimum speed Uo, which is set to be 0.4 m s−1. The objective uniformity, OU, defined in Eq. is used to assess the overall flow conditions. The OU for all eight cases as a function of mass flow rate are summarized in Fig. 5. Since the inlet/exit area and air density remain the same, the mass flow rate is directly proportional to flow velocity. In addition, the target flow velocity over the plants is set to be 0.4 m s−1. Therefore, a general trend of OU first increases and then decreases when increasing the overall mass flow rate. Depending on the design, the peak of OU occurs at different mass flow rate for each case. Another general trend can be observed that the peak of OU occurs at a lower mass flow rate if the inlet is located at the top due to buoyancy force. This can be clearly demonstrated by cases AB and BA or AD and DA . Therefore, there exists a different optimal inlet/exit design for each mass flow rate condition. As can be seen from Fig. 5, the maximum OU at flow rates of 0.2, 0.3, 0.4 and 0.5 kg s−1 is observed for configurations AD, BC, BA, and DA, respectively. Therefore, this simulation model can identify optimal flow configuration at a specific mass flow rate condition. Since OU quantifies the deviation of average velocity of each tray from the designed velocity, a higher OU value indicates that the crops will have better and more uniform photosynthesis. It can be observed from Fig. 5 that the maximum OU obtained for all conditions is case BC at a flow rate of 0.3 kg s−1. To develop a better understanding, the two-dimensional velocity and vorticity distributions in the x-y plane along the middle of the z-direction for all eight cases at a mass flow rate of 0.3 kg s−1 are plotted in Figs. 6 and 7.

As can be observed from Figs. 6 to 7, the OU is highest for case BC due to its uniform velocity and vorticity distributions between trays. This can be attributed to the position of inlet/exit location with respect to the tray orientation. For case BC, the inlet flow is parallel to the longitudinal direction of the tray and the exit is along the transverse direction . This design allows the flow to travel through the long side of the tray uninterrupted and then form a helical flow orientation near the end of the tray. This spiral formation of flow induces a more uniform and regular flow in the room. This also explains why case AD has very high OU. Similar spiral formation can also be observed when the inlet flow is parallel to the transverse direction of the tray and the exit is along the longitudinal direction , like case DA. However, since the inlet flow is along the short side of the tray, the benefit is not as great and requires much higher inlet mass flow rate. On the other hand, for cases where the inlet and exit are located on the same wall, such as AB or CD, the air flow only has strong mixing effect along the inlet/exit direction which, in turn, reduces the overall flow uniformity. Besides the velocity distribution, horticulture trays the effect of temperature is also a critical parameter for determining convective flow. Fig. 8 shows the two-dimensional temperature distributions in the x-y plane along the middle of the z-direction for all eight cases at a mass flow rate of 0.3 kg s−1. In our analysis, the temperature of the inlet flow is lower than that of the exit flow due to the heat generated from the LED light. For case BC, the inlet is located near the bottom and the exit is near the top. Due to the density difference, the exit warm stream tends to flow up. This allows the flow to reach the topmost tray more easily and, therefore, achieves more uniform temperature distribution among all trays. Combining the inlet flow along the long side of the tray, the helical flow effect, and the buoyancy, case BC is able to reach the maximum OU of 91.7%. Fig. 9 summarized the velocity and temperature contours for case BC at an inlet mass flow rate of 0.3 kg s−1. The velocity pro- files in Fig. 9a clearly show the spiral effect above each cultivation tray and the local velocity is close to the optimal speed of 0.4 m s−1. In addition, the temperature shows an increasing trend from bottom to top as the flow helically passing through the crops and moving towards the outlet.The distributions of temperature and gas species, such as water vapor and CO2, play an integral role in photosynthesis which, in turn, influences the quality of plant and its growth. Therefore, maintaining these critical parameters in a reasonable range to ensure reliable and efficient production is essential to environmental control of an IVFS. Evaluating the distribution of these parameters can also provide the effectiveness of inlet/exit location. It should be noted that the parameter OU provides an overall assessment of the air flow velocity over planting trays. An optimal design is to achieve desired local temperature and species distribution while maintaining high OU values in an IVFS. In the following discussion, the four cases with highest values of OU at their corresponding mass flow rates are studied and compared to the baseline case AB.Since CO2 is a reactant of photosynthesis, increasing CO2 concentration usually leads to enhancement of crop production. Reports show that increasing the CO2 concentration from the atmospheric average of 400 ppm to 1500 ppm can increase the yield by as much as 30%. In this IVFS analysis, the CO2 level of the inlet mass flow rate is increased by a CO2 generator to be 1000 ppm . Since the consumption rate of CO2 through the exchange zones is fixed, higher overall average CO2 concentration through the system is desirable. Fig. 10 shows the comparison of the average CO2 concentration between the highest OU cases and the baseline case AB at different inlet mass flow rate. A few general trends of CO2 concentration can be observed from Fig. 10. First, the CO2 concentration increases with inlet flow rate due to increasing supply of CO2 molecules. In addition, tray 1 has the highest CO2 concentration because most of the cold fresh inlet air dwells near the bottom of the IVFS due to the buoyancy effect. In contrast, tray 3 has the lowest CO2 concentration because the fresh inlet air has the highest flow resistance to reach tray 3due to the combination of sharp turns and buoyancy effect. This is particularly true at low inlet flow rates and when the inlet is located on the top, which lead to low flow circulation as cold inlet air flows downward directly. As a result, BC, BA, and DA at 0.3, 0.4, and 0.5 kg s−1, respectively, have relatively high CO2 concentrations. Even though the baseline case AB at 0.5 kg s−1 has the highest CO2 concentration, its OU is too low to be considered a good design. Temperature is also a critical parameter to control and monitor because it directly affects both relative humidity and plant growth. The temperature distribution in the system depends on the inlet/exit location, inlet mass flow rate, and amount of heat. Since the inlet temperature and heat flux conditions are fixed, the exit temperature increases with decreasing inlet mass flow rate. Fig. 11 shows a comparison of the average temperatures of the higher OU cases and the baseline case AB at different inlet mass Fig. 12. Comparison of the average RH over each tray between the best OU cases and the baseline case at each inlet mass flow rate condition. flow rates.

Sparse metal bars allowed for paw access to the smooth acrylic floor, whereas dense-wire mesh did not. For high-fat diet CPP, animals were given one pellet of standard chow and an isocaloric amount of high-fat food . As high-fat pellets have a different color and consistency, they were also given to home cages the day before pre-conditioning to prevent neophobia. Statistical analyses. Results are expressed as means ± SEM. Significance was determined using two-tailed Student’s t-test, One-way or Two-way analysis of variance with Tukey’s post-hoc test and differences were considered significant if P<0.05. Analyses were conducted using GraphPad Prism .The use of marijuana is reinforced through activation of the mesolimbic reward circuit . In a related but distinct modulatory process, the neurotransmitter system mediating the effects of marijuana in the brain – the endocannabinoid system – also facilitates the reward of other stimuli, such as food or drugs of abuse . The endocannabinoid system has three main components: two lipid-derived local messengers – 2- arachidonoyl-sn-glycerol and anandamide , enzymes and transporters that mediate their formation and elimination, and receptors that are activated by endocannabinoids and regulate neuronal activity . Genetic and pharmacological studies have unveiled key roles of the CB1 receptor in the modulation of reward signaling. Less is known about the functions served by individual endocannabinoid messengers. In particular, an emerging question is whether endocannabinoids might also regulate the reward of social interactions. We recently demonstrated that anandamide regulates social reward via cooperative signaling with oxytocin, 4×4 grow table a neuropeptide that is crucial for social bonding . The role of 2-AG remains unknown, however. One way to assess the specific contribution of individual endocannabinoids is to manipulate the enzymes responsible for their formation and deactivation.

For example, pharmacological inhibition or genetic deletion of the enzyme that hydrolyzes anandamide, fatty acid amide hydrolase , markedly increases anandamide activity at CB1 cannabinoid receptors . Analogous strategies exist for 2-AG. Indeed, MGL-/- mice, in which the 2-AG-hydrolyzing enzyme monoacylglycerol lipase is deleted, andthus 2-AG levels are elevated, as well as DGL-α-/- mice, in which the 2-AG-synthesizing enzyme diacylglycerol lipase is deleted, and thus 2-AG levels are very low . However, the effects of these radical modifications are often difficult to interpret because of the emergence of profound compensatory changes in the brain, such as desensitization of CB1 receptors and elevation in anandamide and arachidonic acid levels . We have recently generated a novel transgenic mouse model – MGL-Tg mice – which selectively overexpress MGL in forebrain neurons under the control of the CaMKIIα promoter . These mutant mice display a forebrain-selective accrual in MGL hydrolyzing activity and a 50-75% decrement in 2-AG content. This reduction in 2-AG is not accompanied by overt changes in levels of other endocannabinoid-related lipids , cannabinoid receptors, or other endocannabinoid-related proteins . To investigate the role of 2-AG in reward-related behaviors, we tested MGL-Tg mice in conditioned place preference paradigms for high-fat food, social, or cocaine stimuli. Based on a rich theoretical framework, CPP assesses the rewarding value of test stimuli by pairing them with neutral environments . Because less is known about endocannabinoid signaling and social behavior, we also investigated the effects of social interaction on 2-AG signaling in reward-related regions of the brain. We hypothesized that MGL-Tg mice are deficient in reward signaling and that rewarding social stimuli drive 2-AG signaling in normal mice.Socially conditioned place preference . Procedures were previously described . Briefly, mice were placed in a two-chambered acrylic box .

A 30-min preconditioning session was used to establish baseline neutral preference to two types of autoclaved, novel bedding . These differed in texture and shade . Individual mice with strong baseline preference for either type of bedding were excluded – typically, those that spent more than 1.5x time on one bedding over the other. The next day, animals were randomly assigned to a social cage with cage-mates to be conditioned to one type of novel bedding for 24 h , then moved to an isolated cage with the other type of bedding for 24 h. On the next day, animals were tested alone for 30 min in the two-chambered box to determine post-conditioning preference for either type of bedding. Bedding volumes were 300 mL in each side of the two-chambered box and 550 mL in the home-cage. Familiar animals from the same cage were tested concurrently in four adjacent, opaque CPP boxes. Between trials, boxes were thoroughly cleaned with SCOE 10X odor eliminator . Scoring was automated using a validated image analysis script in ImageJ .Cocaine and high-fat diet CPP. Procedures were previously described . Briefly, these paradigms were similar to social CPP, including unbiased and counterbalanced design, cleaning and habituation, exclusion criteria, and scoring, except for the following main differences, which followed reported methods . Mice were conditioned and tested in a two-chambered acrylic box . Pre- and post conditioning tests allowed free access to both chambers and each had durations of 15 min and 20 min . For conditioning, animals underwent 30-min sessions alternating each day between saline/cocaine or standard chow pellet/high-fat pellet . The two chambers offered conditioning environments that differed in floor texture and wall pattern – sparse metal bars on the floor and solid black walls vs. dense-wire-mesh floors and striped walls. Sparse metal bars allowed for paw access to the smooth acrylic floor, whereas dense-wire mesh did not. For high-fat diet CPP, animals were given one pellet of standard chow and an isocaloric amount of high-fat food . As high-fat pellets have a different color and consistency, they were also given to home cages the day before pre-conditioning to prevent neophobia.Intake of high-fat pellets was recorded in free feeding mice using an automated monitoring system , as described previously . Food intake was measured for two days, and the average of intake was normalized to the body weight at the start of feeding.The test was conducted according to established methods .

To mimic the conditions of the social CPP task, mice were first isolated for 30 min and tested in dim-light conditions . Pairs of mice were tested in an open field arena for 5 min. Scoring for social interaction time included behaviors such as sniffing, following, grooming, mounting and crawling over or under. Passive interaction, in which mice were in close proximity but without these interactions, was not included in the scoring.The procedure was previously described , which was based on an established protocol . Briefly, test mice were first habituated to an empty three-chambered acrylic box , including to the center chamber for 10 min, cannabis drying system and then to all chambers for 10 additional min. Mice were then tested for 10 min. Subjects were offered a choice between a novel object and a novel mouse in opposing side chambers. The novel object was an empty inverted pencil cup and the novel social stimulus mouse was a sex, age and weight-matched 129/SvImJ mouse. These mice were used because they are relatively inert. They were trained to prevent erratic or aggressive behaviors, such as biting the cup. Weighted cups were placed on top of the pencil cups to prevent climbing. Low lighting was used. The apparatus was thoroughly cleaned with SCOE 10X odor eliminator between trials to preclude olfactory confounders. Chamber time scoring was automated using image analysis.Sniffing time was scored by trained assistants who were unaware of treatment conditions. Outliers in inactivity or side preference were excluded.The procedure was previously described . Briefly, whole brains were collected and flash-frozen in isopentane at -50 to -60 °C. Frozen brains were transferred to -20°C in a cryostat and kept for 1 h to attain local temperature. The brain was then cut to the desired coronal depth and micropunches from bilateral regions of interest were collected using a 1×1.5-mm puncher . The micropunches weighed approximately 1.75 mg. A reference micropunch was taken to normalize each punch to the brain’s weight. Bilateral punches were combined for lipid analyses.Procedures were previously described . Briefly, tissue samples were homogenized in methanol containing internal standards for H2 -anandamide , H2 -oleoylethanolamide and 2 H8-2-arachidonoyl-sn-glycerol . Lipids were separated by a modified Folch-Pi method using chloroform/methanol/water and open-bed silica column chromatography. For LC/MS analyses, we used an 1100 liquid chromatography system coupled to a 1946D-mass spectrometer detector equipped with an electrospray ionization interface . The column was a ZORBAX Eclipse XDB-C18 . We used a gradient elution method as follows: solvent A consisted of water with 0.1% formic acid, and Solvent B consisted of acetonitrile with 0.1% formic acid. The separation method used a flow rate of 0.3 mL/min. The gradient was 65% B for15 min, then increased to 100% B in 1 min and kept at 100% B for 14 min. The column temperature was 15°C. Under these conditions, Na+ adducts of anandamide/H2 -anandamide had retention times of 6.9/6.8 min and m/z of 348/352, OEA/H2 -OEA had Rt 12.7/12.6 min and m/z 326/330, and 2-AG/2 H8-2-AG had Rt 12.4/12.0 min and m/z 401/409. An isotopedilution method was used for quantification.MGL-Tg mice eat less chow than do their wild-type littermates . The food intake phenotype, however, does not dissociate the effects of 2-AG signaling on metabolic and reinforcement processes.

Furthermore, altered feeding can be interpreted as either decreased or increased reward to the food stimulus. To isolate the effects of reduced 2-AG signaling on reward, we tested MGL-Tg mice and their wild-type littermates in a CPP task for high-fat food. In a standard CPP box, mice were conditioned for 30-min sessions to either standard chow or isocaloric high-fat food for 6 sessions each, alternating over 12 days total . In WT mice, we found that this conditioning protocol was sufficient to elicit a preference for the high-fat-paired chamber during post-conditioning testing. Animals spent 137 seconds more in the high-fat chamber compared to the standard-chow chamber . In contrast, MGL-Tg mice did not develop a preference for either chamber . This result suggests that 2-AG signaling is involved in conditioned reward processes of high-fat food. We then asked whether this role for 2-AG signaling could translate to the reward produced by social interaction . We conditioned mice for 24 h with cage-mates in their home-cage to one type of bedding, then we conditioned them for 24 h isolated to another bedding . In the post conditioning test in a standard CPP box, we found that this conditioning was sufficient to elicit a preference in WT mice for the social bedding . In contrast, MGL-Tg mice did not develop a preference for either bedding . Together with the high-fat-food CPP results, these results suggest that 2-AG signaling may underlie aspects of reward processes common to both natural stimuli.The lack of CPP can be attributed to impairments in the generation and processing of the reward, the consolidation of the memory for the reward, or a combination of these processes. To evaluate whether high-fat food stimuli are generated and processed properly, we measured initial intake of high-fat pellets over 2 days. MGL-Tg mice show a 16% reduction in normalized intake compared to WT littermates over this period . The combined phenotype of MGL-Tg mice showing a lack of CPP and decreased intake suggests that 2-AG plays a role in the generation and processing of high-fat food reward. Strict interpretation of these results, however, may be complicated by the role of 2-AG in energy metabolism . For the same reason, we also examined the direct social activity and the social approach interest of MGL-Tg mice using the social interaction test and the three chambered social approach test , respectively. These tests differ in two key ways: the social interaction test evaluates interactions that are reciprocal and direct, whereas the social approach test measures approach activity to a stimulus mouse that is sequestered in an inverted wire cup; the social interaction test uses familiar cage-mates, whereas the social approach test uses a novel mouse as a stimulus. In the social interaction test, we observed that MGL-Tg mice trend toward less interaction time, but this result was not significant . In the social approach test, we found that both MGL-Tg and WT mice preferred the social chamber over the object chamber and sniffed the stimulus mouse more than the object . MGL-Tg mice were similar to WT mice in the amount of time spent in the social chamber and sniffing the stimulus mouse .

In addition, there are stark differences for acute LD50 doses among genera, where minute amounts of brodifacoum bait caused death in domestic canids but domestic felids required doses 5 to 40 times higher . The same variability seen in both mustelids and other carnivores suggests that predicting clinical thresholds for fishers would be pre-mature. Furthermore, AR exposed fishers had an average of 1.6 AR types within their systems, and possible interaction effects from a combination of 2 or more AR compounds within a fisher and other species are entirely unknown.Spatial analyses did not reveal any obvious point sources of AR exposure. Instead, these analyses suggested that exposure is widespread across the landscape. Previous studies expected that exposure to AR compounds would be clustered near areas of human activity or in habitations and that exposure would not be common outside of these areas. Incongruously, data from this study refuted this hypothesis thus making the finding even more significant. Furthermore, these exposures occurred within a species that is not closely affiliated with urban, peri-urban or agricultural settings in which second-generation ARs typically are. Before the June 2011 Environmental Protection Agency regulations, second generation class ARs could be purchased at local retailers, vertical farming system with recommendations for placement in weather- and tamperresistant bait containers no more than 50 feet from any building. However, since June 2011, second generation ARs have not been available to consumers at retail, but only at agricultural stores with additional form and weight restrictions.

These newly passed regulations are aimed at further restriction of irresponsible and illegal use of ARs. However, we would have expected that with either pre- or post-June 2011 regulations, second generation AR exposed fishers would have overlapped with urban, peri-urban, or agricultural environments. This pattern is acknowledged in several studies, such as Riley et al. where bobcat and mountain lion total quantification levels of AR exposure were associated with human-developed areas. Numerous studies have documented that secondary poisoning cases are closely associated with recent agricultural or urban pest eradication efforts. The majority of habitat that fishers in California and fishers throughout the DPS currently and historically occupied is not within or near agricultural or urban settings. Several fishers that were exposed had been monitored their entire lives and inhabited public or community lands where human structures are rare or non-existent . Therefore, exposure from first or second generation AR use at or within 50 feet of residential or agricultural structures and settings were considered unlikely due to fisher habitat requirements and general lack of association with humans. This suggests that wide-spread non-regulated use of second generation second generation ARs is occurring within the range of fishers in California, especially on public lands. A likely source of AR exposure to fishers is the emerging spread of illegal marijuana cultivation within California public and private lands. In 2008 in California alone, over 3.6 million outdoor marijuana plants were removed from federal and state public lands, including state and national parks, with thousands of pounds of both pesticides and insecticides found at grow sites. In 2011, a three week eradication operation of marijuana cultivation removed over 630,000 plants and 23,316 kg of trash including 68 kg of pesticides within the Mendocino National Forest in the northern California fisher populations range. Anticoagulant rodenticides and pesticides are typically dispersed around young marijuana plants to deter herbivory, but significant amounts of AR compounds are also placed along plastic irrigation lines used to draw water from in order to deter rodent chewing .

A recent example in which over 2,000 marijuana plants were removed less than 12 km from one of the project areas revealed that plants on the peripheraledges as well as nearby irrigation had large amounts of second generation AR placed . Finally, just within a single eradication effort, multiple kilometers of irrigation line within National Parks and Forests in California were removed. Placement of ARs at the grow sites and along irrigation lines which jut out great distances from the grow site itself may explain why there are no defined clusters of AR exposure. It is noteworthy that the AR fisher mortalities we documented occurred in different areas of their California range but within a relatively short seasonal period between mid-April to mid-May. We cannot specify the exact explanation or source contributing to all AR mortalities that occurred within this short temporal period. This period is when females are providing for offspring as well as males searching for mates; however, preliminary spatial data for fishers in California document that females have more confined home-ranges during this period, while males have slightly larger home-ranges . Additionally, several books available to the general public identify the optimal time for planting marijuana outdoors is during mid to late spring, and seedlings are especially vulnerable to rodent pests . Of additional concern is that April to May is the denning period for female fishers and a time when fisher kits are entirely dependent on their mothers. The documentation of a lactating female mortality attributed to AR toxicosis during this period suggests that most likely kits would be abandoned and die from female mortalities during this time. In conclusion, this study has demonstrated that fishers in the western DPS, which are of conservation concern and a candidate for protection under the Endangered Species Act, are not only being exposed to ARs, but ARs are a direct cause of mortality and indirect mortality in both of California’s isolated populations. Consequently, these toxicants may not only pose a mortality risk to fishers but could also pose significant indirect risks by depleting rodent prey populations upon which fishers depend.

The lack of spatial clustering of exposed individuals suggests that AR contamination is widespread within this species’ range and illegal or irresponsible use of ARs continues despite recent regulatory changes regarding their use. Because we do not know the long term ecological ramifications of these toxicants left on site long after marijuana grows are dismantled, heightened efforts should be focused on the removal of these toxicants at these and adjacent areas at the time of dismantling. Further regulation restricting the use of ARs to only pest management professionals as well as continued public outreach through state wide Integrated Pest Management programs may be warranted. In addition, promotion of compounds that do not possess the propensity for secondary poisoning should be considered in non-professional use settings. Furthermore, ARs in these habitats may pose equally grave risks to other rare and isolated California carnivores such as the Sierra Nevada red fox , American marten , wolverine , gray wolf or raptors such as northern spotted owls , California spotted owls and great gray owls . Future research should be directed to investigating potential risks to prey populations as well as other sympatric species that may allow a better understanding of the potential AR sources contributing to these exposure and mortality rates from anticoagulant rodenticides.Edge detection is the first step of human visual perception and is fundamentally important in the human visual system . Edge detection significantly reduces the amount of data to be processed, vertical farming racks since it extracts meaningful information and preserves important geometric features. To detect the edges of an object, the object information is processed by either digital computation or analog computation. In practice, as an optical analog computation element, spatial differentiator enables massively parallel processing of edge detection from an entire image, which offers advantages over digital computation: It can deal with realtime and continuous image processing with high speed and is power-saving in specialized computational tasks . During the past few years, optical meta materials and meta surfaces have been suggested to perform analog spatial differentiation for edge detection which show superior integration capability compared with the traditional bulky system comprising lenses and spatial filters . A suitably designed meta material structure was theoretically proposed to perform desired mathematical operations including edge detection as light propagates through it . Deliberately designed layered structure was also suggested for spatial differentiation when an incident beam is reflected from it . Plasmonic dark-field microscopy utilizes near-field surface plasmon waves to excite the object, and can be also treated as an efficient approach for edge detection . However, to the best of our knowledge, free space broadband edge detection has not been reported yet because either the system can only be applied for surface imaging or the fabrication involved is too complicated . Here, we propose a mechanism to implement an optical spatial differentiator consisting of a designed Pancharatnam–Berry -phase meta surface inserted between two orthogonally aligned linear polarizers . Unlike other spatial differentiator approaches, our method does not depend on complex layered structures or critical plasmonic coupling condition, but instead is based on spin-to-orbit interactions. Experiment confirms that broadband optical analog computing enables the edge detection of an object and achieves tunable resolution at the resultant edges. Furthermore, meta surface orientation-dependent edge detection is also demonstrated experimentally.As shown in Fig. 2A, the sample is made of form-birefringent nanostructured glass slabs. The diameter of the glass substrate is 2.5 cm, the thickness is 3 mm, and the pattern area of the sample is 8 mm by 8 mm. The meta surface pattern is fabricated by a femtosecond pulse laser inside of glass, 50 μm beneath the surface. Under intense laser irradiation, a plasma of high free electron density is generated by a multi-photon ionization process. The interference between the plasma and the incident light beam leads to the stripe-like nanostructure as reported . By carefully controlling the polarization of incident beam, the desired orientation of the nanostructure, which is perpendicular to this polarization, can be obtained. More fabrication details could be found in our previous work . We utilized the polariscopy method to demonstrate the local optical slow-axis orientation of this birefringent structure .

As shown in Fig. 2B, crossed linear polarizer imaging under 80× magnification emphasizes the transverse gradient pattern of the optical axis, which corresponds to the dotted square area in Fig. 2A. We can clearly see the local orientation of the microscopic structures, i.e., the slow-axis distribution φðx,yÞ of laser-induced form birefringence. The red bars indicate the orientation of the slow axis over one period of this sample. The nanostructures are on the order of 30∼100 nm, as indicated from the scanning electron microscope image in Fig. 2B, Inset. The structure dimension is much smaller than the working wavelength, therefore we can treat it as a birefringence medium with spatially variant optical slow axis. When the light beam passes through the designed inhomogeneous birefringent medium with locally varying optical axis orientations and homogeneous retardation, it will acquire a spatially varying PB phase .The first lens yields the Fourier transform of the object at its back focal plane, which is exactly the position of the meta surface. In turn, the second lens performs another Fourier transform, delivering a duplicate of the object. When the light passes through the 4f system, we obtain two vertically shifted LCP and RCP images with overlapping area being linear-polarized as shown in Fig. 3 A–C. The amount of shift of the two images is difficult to see due to the small phase gradient of the meta surface. To block the overlapping area while preserving circularly polarized edge, we put an analyzer after the meta surface so that only the edges can go through, as displayed in Fig. 3 D–F. The wavelengths are chosen as 430, 500, and 670 nm, which not only confirms the proposed concept of edge detection, but also demonstrates its broadband capability. The broadband property of our meta surface originates from the geometric phase of the nanostructure orientation, which is intrinsically independent of wavelength . Additionally, the transfer function of the whole edgedetection system is experimentally measured and provided in SI Appendix, Fig. S3, which shows a typical response for the edgedetection function . Additionally, we demonstrate the tunable resolution of the edge images corresponding to different PB phase gradient period Λ. For this experiment, we choose the UCSD Triton insignia as our object . Fig. 4 A–D shows the photos of four meta surfaces with Λ equal to 500, 750, 1,000, and 8,000 μm. Fig. 4 E–H corresponds to the polariscope optical image of the meta surfaces of the first row, which shows different numbers of period within the same field of view .

We provided 36 statements that corresponded to four themes: community ; the environment ; changes over time in property values, community safety, community demographics and so on and grower demographics . Respondents were asked to agree or disagree with the statements using a 5-point Likert scale and were able to provide comments after each subsection. The third section of the survey solicited background information about each respondent. Respondents were asked whether they earned income from timber, ranching or dairying, how long their families had owned the land they worked and whether they were absentees. In addition, we asked landowners if they had been approached about selling their land for cannabis cultivation and if they had next-generation succession plans for the family ranch or timber business. We also asked if landowners knew of nearby cannabis growing.As indicated previously, all respondents included in our survey owned at least 500 acres of land. Twenty two percent owned between 500 and 1,000 acres, 51% owned between 1,000 and 5,000 acres and 28% owned more than 5,000 acres. Of the 69 landowners whose responses were included in our results, 63 respondents managed timberland and 56 respondents managed ranchland, meaning that most respondents managed both land types; only one respondent was involved in dairy farming. Forty-six percent of respondents lived on their properties full time, while 20% lived on their properties part time. Thirty-three percent of respondents were absentee landowners. In general, bud drying rack the land represented in the survey had been in respondents’ families for a long time — more than 50 years in 81% of the cases, 25 to 50 years in another 10% of the cases, less than 25 years in 6% and less than 5 years in only 3% of the cases.

Fifty percent of respondents reported that their primary income was from traditional forms of agriculture or timber production; no respondents reported cannabis as their primary income source.Seventy-one percent of landowners reported that they did not grow cannabis on their property while 18% reported that they did. These percentages, however, are derived only from the 34 of 69 respondents who agreed or disagreed with the statement that they had used their property to grow cannabis. The remaining respondents — half the total — chose not to indicate whether they had grown cannabis, potentially indicating landowners’ reluctance to associate themselves with the cannabis industry. About 40% of respondents had indirectly profited from cannabis through off-farm work such as heavy equipment work, trucking and so on . Fifty-seven percent of all respondents agreed or strongly agreed with the statement that “the cannabis industry has negatively affected my livestock operations,” while 27% disagreed with this statement. Over 60% of respondents agreed that cannabis had increased the cost of labor. Comments that respondents offered on the cost of labor included “Property values are inflated by the cannabis industry, hence costing us more for leases and ownership.”Seventy-five percent of respondents agreed or strongly agreed with the statement that “shared roads have been degraded by cannabis growers” and 65% agreed that noise pollution has increased due to cannabis growing. Fifty-five percent of respondents agreed that growers increase light pollution and 71% reported having experienced illegal garbage dumping by cannabis growers on or near their property. Forty percent of landowners disagreed or strongly disagreed with the statement that “I know growers who have values that align with my own” . At the same time, 34% of respondents agreed or strongly agreed with that statement . One respondent added that “[M]onetary impact is obvious.

Cultural and moral impacts are terrible.”Fifty-six percent of respondents agreed or strongly agreed that water sources have been impacted by cannabis growers, while 25% disagreed with this statement. Fifty-six percent also agreed that water had been stolen from their property. Seventy-two percent of respondents had experienced trespassing, while 20% had not. Forty percent of respondents reported that their fencing or infrastructure had been destroyed by cannabis growers, though a similar percentage had not. Fifty percent of landowners reported that neighboring growers had failed to assist with fence maintenance, and 75% of landowners reported having discovered trespass grows on their property . One respondent added that “[Growers’] dogs killed our cattle. My brother confronted a grower in fatigues carrying an assault rifle on our property. [Our] fences have been wrecked, roads damaged, and stream water theft.” Another respondent wrote that “Yes, this is true in the past, but with the pot market collapsing I don’t think this will be a problem in the future”.Roughly 55% of landowners reported having been threatened by cannabis growers’ dogs while 24% did not. Forty-six percent of landowners reported that their safety had been threatened by growers. Equal proportions of landowners reported, and did not report, having felt unsafe due to interactions with growers on public lands. Finally, 50% of landowners agreed that growers had committed crimes against them or their Property.Perceptions of cannabis growers were relatively unified among survey respondents. A majority of respondents did not perceive growers as having values similar to their own . The majority of landowners felt that growers had changed how it feels to live in their community , and 77% of landowners expressed concern about the changes that growers are bringing to their community. More than 80% of respondents were concerned about growers taking over working lands in their communities, and the same percentage were concerned that growers reduce the influence in the community of timber managers and ranchers.

One respondent wrote that “The bottom line is that our family would accept the negative economic impact of eliminating ‘pot’ in return for the elimination of all the negative impacts of the grower culture.” More than 90% of respondents agreed that growers from urban locations do not understand rural land management. Most landowners disagreed that growers are reinvigorating their rural communities or that growers are the only thing keeping their communities going . Eighty three percent of respondents disagreed with the statement that growers do a good job of policing themselves. Most landowners have not changed their views on cannabis with medical or recreational legalization .The clear majority of respondents did not think cannabis growers manage timberlands sustainably and a similar percentage felt the same about ranchlands. Eighty-five percent of respondents regarded cannabis growing as negatively affecting wildlife and 87% regarded it as negatively affecting stream flow . Eighty-four percent thought cannabis growing leads to soil erosion and 70% thought it increases fire hazard. Seventy-eight percent believed that cannabis production in ranchlands and timberlands leads to habitat fragmentation and the same percentage suggested that the economic value of cannabis incentivizes the subdivision of large parcels.Fifty percent of landowners felt that their property value had increased due to cannabis production while 40% were neutral on that question. Eighty-three percent of respondents thought that Humboldt County was a safer place before cannabis and 76% of respondents perceived new cannabis growers as less responsible than cannabis growers who have been in the county for years. About half of respondents believed that increased cannabis legalization will be good for Humboldt County. Fifty-seven percent of respondents were not yet willing to accept that cannabis is a leading industry and that people should support it. Fifty-four percent of respondents believed that Humboldt County would be better off in the future without cannabis.Most landowners included in the survey reported having observed changes in grower demographics in the last decade. Most felt that the number of small cannabis growers is decreasing. Sixty-one percent felt that the number connected to organized crime is increasing and perceived that there is an increasing number of green rush growers in their communities. Most respondents were concerned about organized crime, vertical grow rack system while only 48% were concerned with green rush growers and 18% with small growers.Overall, resident and absentee owners expressed similar views on most issues. Of the survey’s 59 statements on experiences and perceptions, statistically significant differences between the two groups appeared for only eight statements. Absentee owners were more likely to report that their surface water resources had been impacted by growers; that their fences or infrastructure had been destroyed by growers; that their safety had been threatened by growers and that they had been threatened by growers on public land. They were less likely to agree that growers manage timberland sustainably and that cannabis production decreases their property values.

With this study, we aimed to better understand the experiences and perceptions of traditional agricultural producers — the families who, in most cases for several generations, have made a living off their land, all the while watching changes occur in the social, economic and environmental dynamics that surround cannabis. This survey’s documentation of social tensions may not come as a surprise to those who have lived in Humboldt County . Even after many decades of cannabis cultivation, traditional agricultural producers have not warmed to the people or practices involved in the cannabis industry. Indeed, changes in the social fabric of the cannabis industry have only perpetuated and intensified existing tensions. As this survey shows, concerns about “small growers” are minimal now — those growers have become part of the community, and one-third of respondents agreed that they know growers whose values align with their own. What was novel 40 years ago is now a cultural norm. Today’s concerns center instead on the challenges of current cannabis culture: environmental degradation and the threat of major social and economic change. Respondents mostly agreed that growers today are less reasonable than those who have been in the county for many years. As one respondent wrote, “Growers are a cancer on Humboldt County.” This distrust highlights the challenges that, in rural areas, can often hinder community-building and mutual assistance mechanisms, which are often needed in isolated communities . The economic influence of cannabis can be seen throughout the county. As the survey shows, approximately 40% of respondents have been impacted indirectly by the cannabis industry, and some respondents have directly profited through cannabis production themselves. Interestingly, just over half the respondents chose not to say whether they grow cannabis, hinting at the possibility that, even for traditional agricultural producers, cannabis has presented an opportunity to supplement income and cover the costs of landownership. However, the broader economic growth attributed to the cannabis industry is not always viewed favorably, and a majority of respondents agreed that Humboldt County would be better off in the future without cannabis. Some respondents claimed that the industry has increased the cost of labor and that, in many cases, it can be difficult to find laborers at all because the work force has been absorbed by higher-paying cannabis operations. Likewise, many respondents agreed that land values have increased because of cannabis. But for landowners whose property has been passed down through generations, and who have little intention of selling, increased land values translate into increased taxes and difficulty in expanding operations, both of which can be limiting for families who are often land-rich but cash-poor. One respondent wrote, “Yes, the price of land has gone up… but this is a negative. It increases the inheritance tax burden, and it has become so expensive that my own adult children cannot afford to live here.” In Humboldt County’s unique economic climate, it’s difficult for most landowners to decide whether the opportunities the cannabis industry provides are worth the toll that they believe the industry takes on their culture and community — it’s not a simple story. As one respondent noted, “If I had taken this survey 40 years ago, my response would have been very different. With Humboldt County’s poor economy, everyone is relying on the cannabis industry in one way or another.” Our survey provides an important baseline from which such changing attitudes can be measured. Our results should be seen in the context of larger trends involving population and agricultural land in Humboldt County. At the time we were preparing our survey, property records indicated that slightly more than 200 landowners in the county owned at least 500 acres; these individuals made up our survey population. Past research, however, has documented that cannabis was likely grown on over 5,000 distinct parcels in Humboldt County in 2016 .

We believe that this occurred in the early 2000s although it could have started after 1989 when we last visited the structures. We lack information on the most obvious and interesting observations: the mode of reproduction, the settlement biology, and the growth of this interesting sponge. The obvious questions relate to the explanation of the event. We have no knowledge of the actual propagules or the settlement, only recruitment to a size that can be seen and identified. There are no published descriptions of dispersal propagules of A. joubini, their settlement preferences, or their growth rates. We have seen very small buds that we assume are asexually produced by another hexactinellid, R. antarctica, and we have collected them in the water column in strong currents. Thus, we know that asexually produced buds can move through the water column where they could in principle be entrained and lifted by strong tidal currents; however, we have not seen R. antarctica or any other hexactinellid beside A. joubini on any of our settling surfaces. To our knowledge, there is no evidence of any Antarctic hexactinellid sponge demonstrating sexual reproduction, although it has been seen elsewhere. In our cases A. joubini propagules must have been abundant, at least around the gangplank on Ross Island and at Explorers Cove where there was massive recruitment high in the water column. Given the heavy recruitment observed on artificial surfaces well above the seafloor, we suggest that swimming larvae are released episodically. Why is the A. joubini recruitment predominantly on artificial surfaces? We have no data to address this interesting question, equipment for growing weed but we hypothesize that there are more predators on natural substrata and that these predators serve as a strong filter on the survivorship of the propagules as discussed by Thorson.

Oliver and Slattery offer strong evidence of the efficiency of a microcanopy of carnivorous invertebrates near the gangplank, and Suhr et al. demonstrated that three of the most common foraminifera, especially Astrammina rara, consume metazoa including planktonic invertebrates in Explorers Cove. Out of this, it is reasonable to speculate that benthic predation filters settling larvae as discussed by Thorson. Another obvious question relates to the fact that we saw no measurable growth of many naturally occurring A. joubini between 1967 and 1989, yet beginning sometime between then and 2004 they exhibited tremendous growth. With the exception of two small sponges, none of the structures had any A. joubini in 1989. However, in 2004 these structures were photographed with very large sponges that presumably had settled after 1998, but certainly no earlier than 1990 , and by 2010 sponges had obtained diameters ranging from 7 to 72 cm . Further, the estimated mass of a sponge observed on an artificial substrate at Cape Armitage in 2010 increased about 30% when it was re-photographed in 2012. Clearly, rapid growth rates are possible by A. joubini. What environmental factors were responsible for this sudden growth? The most likely correlate with the growth if not the settlement was a probable shift in plankton composition. Typically the transport of abundant primary production from the north results in a seasonal plankton bloom composed of relatively large phytoplankton . However, in the 2000s a series of large icebergs were grounded, blocking this transport and preventing the annual ice from breaking up and going out until 2011. The icebergs and thick sea-ice probably interfered with the advection and growth of the large phytoplankters that usually dominate in the water column. Thrush and Cummings and Conlan et al. summarized many populations that were negatively impacted by the lack of advected primary production over this decade.

The dynamics of A. joubini were also correlated with this phenomenon, and we suggest that changes in the plankton may have resulted in a shift from large phytoplankters to tiny dinoflagellates and bacteria. Margalef postulated such a relationship in water columns to result from reduced resources. Sea ice thickness and transparency affects benthic productivity and ecosystem function. Montes-Hugo et al. , described such regional changes in the Western Antarctic Peninsula suggesting a strong relationship between ice cover and the size of the phytoplankton. Orejas et al. and Thurber 2007 discuss the strong relationship between microplankton and Antarctic sponges. Reiswig and Yahel et al. , working on other hexactinellid sponges, demonstrated that they retain only very small particles of bacteria and protists. As hexactinellids in general seem restricted to feeding on tiny particles, the shift in plankters may have offered a strong pulse of appropriate food for A. joubini, triggering rapid growth that was previously not observed in this species. Moreover, our observations of relatively fast growth following a shift in the food is supported by Kahn et al. who report relatively fast temporal changes in the density of two deepwater hexactinellid sponge species in 4,000 m depth off Monterey, California, USA. These density shifts occur with a lag of 1–2 years following shifts in the food supply of the micro-particles they consume. Although A. joubini growing on the gangplank had a broader weight distribution than the same species growing on the floaters in Explorers Cove , we are hesitant to attribute these differences to the site location. It is very likely that the individual sponges that fell off the racks and floaters in Explorers Cove were larger than the sponges that remained on these substrata. Therefore, the measurements from these two substrata at Explorers Cove could be skewed to smaller-sized individuals. We also have preliminary but convincing evidence of A. joubini mortality.

Although we were not able to relocate all transects in 2010 and therefore may have missed some surviving sponges, at least 67 large A. joubini died in the 40 years of this program with no known survivors. We have no reason to question earlier observations that some mortality results from predation by A. conspicuous and the amphipod S. antarctica. Additionally, Cerrano et al., report patches of diatoms inside A. joubini, but speculate that the diatoms had invaded and are detrimental to the sponges. We agree and have seen the amphipod, S. antarctica, eating patches of the sponge that subsequently are colonized by diatoms. In 2012 we photographed considerable evidence of incipient amphipod infestation on A. joubini at the gangplank; however, the actual mortality sources within this study are not known and some may reflect ice formation on the sponge that kills the tissue in a patchy manner, later becoming infected with S. antarctica. We emphasize that many of these large A. joubini surely do live longer, and we are only considering sponges in our localized study sites, but this is still a very high mortality rate for a species of sponge thought to be long-lived. Summarizing the A. joubini observations of massive recruitment and growth and rapid mortality, we suggest that this sponge has much more dynamic life history than previously suspected. What of the other Hexactinellida in our study sites? We know that R. antarctica grows relatively fast as this was studied in the 1970s. We observed surprisingly fast growth and asexual reproduction of mature individuals and we also observed some 40 very small R. antarctica buds to increase their volume as much as two orders of magnitude . This species is by far the dominant sponge in the 25–50 m depth range at McMurdo Station, but it is so inconspicuous that it is extremely difficult to evaluate the population patterns. Obviously it has the potential to multiply relatively quickly, yet we have no evidence of sufficient mortality to balance the reproduction and growth rates observed. The other common Antarctic hexactinellid is R. nuda/racovitzae. This knobby, volcano-shaped sponge is smaller than A. joubini and remains an enigma with regard to its population dynamics and growth rate. Prior to the removal of the cages in 1977, seven R. racovitzae survived inside cages , while 2 died inside their cages. Those survivors did not show significant growth during that time period. The mortalities may have resulted from sea star predation or infestation of S. antarctica. Our extensive surveys in 2010 may have come across a few young R. nuda/racovitzae although they were not collected and we are not sure of their identification. It is interesting to note that Fallon et al., report a relatively-small, 15 cm diameter specimen from the Ross Sea was approximately 440 years old. Many of the R. racovitzae in our area were at least a meter tall, so this species might obtain great age. Rossella fibulata is a rare sponge in the McMurdo Sound area; however, two individuals settled on a rack at Explorers Cove and on a cage at Cape Armitage. It appears to grow rapidly but otherwise little is known of its biology. In any case, the four hexactinellid species in this shallow habitat certainly have different life history patterns, with the fast turn-over of A. joubini being the most surprising. Our observations complement those of Teixido´ et al. who report high frequencies of asexual reproductive strategies in three deep-water Hexactinellida in which 35% of the observed R. nuda were actively budding. In addition, grow tables 4×8 many R. racovitzae exhibited reproduction by fragmentation while R. vanhoeffeni reproduced with bipartition. Thus, it appears that each of the Antarctic Hexactinellida species exhibits different life history biology.

In summary, these observations allow us to test and reject the prevailing notion of slow rate processes for both recruitment and growth of A. joubini. The population dynamics imply that A. joubini are fast to respond to an environmental shift, but the population increase may be relatively short and we need to re-evaluate ideas of slow processes and stability over century time scales. These surprising results are set in a time of climate- and fishing-related environmental changes. Certainly these results demonstrate the great importance of comprehensive, long-term data sets designed to better understand such processes. Voucher specimens collected in the 1960s were sent to the Smithsonian Oceanographic Sorting Center and the specimens seem to be lost; however, a collection of specimens is available at the Scripps Invertebrate Collections.Adolescence is a critical period of development marked by the formation of self-concept and identity, independence from parental guidance, and growth in cognitive and socioemotional skills such as empathy, resilience, and creativity. However, some adolescents also begin to engage in risky behaviors, such as use of tobacco, cannabis, alcohol and other substances. These behaviors are significant, as they can negatively influence this important developmental period and contribute to a vicious cycle whereby risky behaviors interfere with school engagement and academic performance and vice versa. This negative feedback loop is suggested by Richard Jessor’s Theory of Problem Behavior, which proposes that school climate, including the social environment of peers, contributes to adverse adolescent behaviors and outcomes including school disengagement, risky behaviors, and academic failure. These adolescent behaviors in turn influence the school climate, as when groups of students normalize delinquent behaviors, undermining academic engagement more broadly. This vicious cycle in adolescence can have significant downstream effects in adulthood, potentially affecting educational and socioeconomic opportunities as well as overall health outcomes. While Jessor’s theory suggests reciprocal effects between a negative school climate and adolescent risky behaviors, it may also suggest that a positive school climate could create a virtuous cycle of improved academic success, greater school engagement, academically and prosocially supportive peers, and better academic and behavioral outcomes among teens. This is supported by prior literature which has shown that positive school climate is linked to better academic performance, student well being, and school engagement, and lower rates of problem behaviors such as disruptive, antisocial, violent, bullying, or delinquent behavior. Although there is no standardized measure of school climate, there are several domains which have been used to characterize school climate and show predictive potential, among them: the institutional environment, student-teacher relationships , and disciplinary styles. However, prior studies have primarily only examined a limited set of school climate variables and adolescent risky behaviors and most have been limited to cross-sectional designs. As a result, it is still unknown which aspects of school climate might be targeted to improve specific academic or health outcomes. The present study sought to identify and compare associations between school climate measures across multiple domains and multiple downstream health and academic outcomes longitudinally.

In other words, the eliquid will be entirely VG well before the e-liquid reservoir is depleted. The predicted percent of e-liquid remaining at full VG enrichment in the model is fairly insensitive to starting volume in the e-liquid but is sensitive to starting PG:VG ratio and temperature, as expected. Thus, a user may be inhaling high relative concentrations of acrolein and other predominant VG products in the aerosol for a significant amount of time during the e-liquid cartridge or reservoir lifespan.The vaping process for e-cigarettes is complex and dynamic, possibly more so than currently appreciated. Coil temperature, puff duration, and PG:VG ratio all significantly affect both theaerosol production and the composition. Most of the mass that was lost from the e-liquid could be accounted for as PG and VG. Furthermore, volatile/semivolatile compounds dominated the total aerosol. Caution should be exercised when collecting particles with dense filter material or with overloaded filters for studying the particle phase, as the semivolatiles can be trapped and interpreted as particulates. In general, the chemical mechanisms for forming carbonyls appear to be well understood, and consistent with the numerous insights gained from interpreting the carbonyl mass yield as normalized by aerosol mass. Some exceptions include acetone, for which there may be a radical pathway from VG not currently accounted for, and acetaldehyde, for which there may be a thermal pathway from PG. Importantly, drying room the user’s exposure to toxic carbonyls such as acrolein may change during the vaping process, and the user may be exposed to high relative content of VG and its degradation products as the e-liquid is depleted.

These findings support the need for further research into aerosol composition and toxicology as a function of the e-cigarette puffing life cycle, in addition to e-liquid composition, puffing regimen, and vaping device operational conditions.The unexpected outbreak of e-cigarette or vaping-associated lung injury was reported nationwide starting in September 2019, causing more than 2800 hospitalizations and 60 deaths. The specific biological mechanisms of EVALI, as well as the chemical causes, are still under investigation. Emerging evidence shows that EVALI is associated with vaping tetrahydrocannabinol containing e-liquid cartridges that were obtained on the black market. Although adverse health effects of vaping THC cartridges have been found to include abdominal pain, nausea, chest pain, shortness of breath, and acute respiratory distress, they have not to date been fatal. The sudden deaths and hospitalizations from EVALI are, instead, strongly linked to a compound called vitamin E acetate , the chemically-stable esterified form of vitamin E . VEA is thought to be used as a cutting agent in THC cartridges because it has a similar viscosity to THC oil, so that the adulteration will not be visually evident. FDA labs confirmed that VEA was present in 81% of THC-containing vaping cartridges confiscated from 93 EVALI patients. VEA was also found in the bronchoalveolar fluid samples from 48 of 51 patients, but not found in samples from the healthy comparison control group. The VEA fraction in vaping cartridges confiscated from EVALI patients range from 23% – 88%. The interaction between aerosolized VEA with lung surfactant, the toxicity of VEA thermal degradation products, or other components in the vaping aerosol of extracted THC oil have been hypothesized to explain the association of VEA to EVALI. It should be noted that there is currently not sufficient evidence to rule out the contribution of other diluents, flavoring additives, pesticide residues, or other ingredients found in THC cartridges.

It’s also not known if VEA has a synergistic effect with THC oil components that may lead to EVALI. A limited number of recent research publications has focused on either the physical and chemical properties, or the biological effects of the vaping aerosol from VEA. DiPasquale et al.observed VEA was capable of reducing the elastic properties of pulmonary surfactant and thus cause lung dysfunction by alveolar collapse or atelectasis. Lanzarotta et al. found evidence for hydrogen bonding between VEA and THC in both vaping aerosol and unvaped e-liquid, suggesting they may synergistically cause EVALI. Wu et al. showed that the toxic gas ketene, as well as carcinogenic alkenes and benzene are generated from the thermal degradation of VEA. RiordanShort et al. found that pure VEA starts to decompose at an incubation temperature of 240 °C and identified over 40 kinds of thermal degradation product at an incubation temperature of 300 °C, 30 of which are carbonyls and acids. However, the experiments of Riordan-Short was done under heated headspace sampling as a surrogate vaping environment, instead of a real vaping environment in an e-cigarette tank with metal coil, where temperature gradients exist due to localized coil heating. Furthermore, different coil material and surface area will have different effects on thermal degradation chemistry. Jiang et al. reported a total of 35 toxic byproducts during the vaping of commonly used diluents including VEA; over 25 of them are carbonyl compounds. Compared to VEA, there is less research available on the vaping chemistry of THC oil extracts and other cannabinoids due to DEA regulations, even though the metabolism of THC has been well studied.Meehan-Atrash et al. hypothesized that THC emits similar thermal degradation products to terpenes given their terpenoid backbone; however, terpenes are also found in cannabis plants and can be used as additives in e-liquids, such that the degradation products may be difficult to distinguish from THC. It was also found that vaping and dabbing cannabis oil including terpenes may cause exposure to concerning degradants such as methacrolein, benzene, and methyl vinyl ketone.

Adding terpenes to THC oil led to higher levels of gas-phase products compared to vaping THC alone. Since vaping is a complex and dynamic process, a systematic understanding of the chemistry occurring during the vaping process is needed to assess potential factors that may contribute to EVALI, as well as other potential adverse health effects. In this work, a temperature controlled vaping device with accurate coil temperature measurement was used to vape e-liquids of VEA, extracted THC oil, and their mixture under typical vaping conditions consistent with the CORESTA standard. Gravimetric analysis was used to evaluate the aerosolization efficiency, while the high performance liquid chromatograph coupled with high resolution mass spectrometry was used to characterize thermal degradation products including carbonyl compounds, acids, and cannabinoids using the methods developed by Li et al. A comprehensive thermal degradation mechanism for THC and VEA are proposed, which could be useful for regulation and further research.A temperature-controlled third generation Evolv DNA 75 modular e-cigarette device with a refillable e-liquid tank and single mesh stainless steel coils was used for aerosol generation . The mod enabled variable output voltages with coil resistance of ~0.12 ohm. Evolv Escribe software was used to customize the power output in order to achieve the desired coil temperature. The coil temperatures were measured by a flexible Kapton-insulated K type thermocouple in contact with the center of the coil surface and output to a digital readout. The temperature set by the device is not truly representative of the measured coil temperature, as often, vertical farming units the device flow rate, e-liquid viscosity, and coil resistance changes will alter the relationship between applied power and output coil temperature that drives chemistry. The puff duration is 3 s with a flow rate of 1.20 ± 0.05 L/min, quantified by a primary flow calibrator , corresponding to puff volume of 60 ± 2.5 mL. The puff volume and puff duration selected in this work is consistent with e-cigarette test protocols applied to propylene glycol /vegetable glycerin based e-cigarettes.The e-liquids used for vaping in this work are: pure VEA that was used as purchased, extracted THC oil that is commercially obtained from Bio-pharmaceutical Research Company , and the mixture of the two ingredients . All THC experiments are performed at the BRC facility under an active DEA Schedule 1 license. Thecomposition analysis by gas chromatography of unvaped extracted THC oil showed that the most abundant cannabinoids are: Δ 9 -tetrahydrocannabinol , Δ9 – tetrahydrocannabinol acid and cannabigerol acid , while other cannabinoids were identified below 3% of the total peak area . Δ 8 -THC, which can be observed at 0.3 minutes after the Δ 9 isomer, was not detected in the mixture. A total of over 50% of mass in unvaped extracted THC oil remain uncharacterized, but presumably contains terpenoids and potentially other alkanes and alkenes. Three temperatures were chosen for the particle generation, with a temperature measurement deviation of 10 °F. The quantification of carbonyls is only reported at 455 °F. During the sample collection, a total of 10 puffs of aerosol with a frequency of 2 puffs/min were collected for each sample. Carbonyls, acids and cannabinoids in vaping aerosols , which represent a large portion of expected products, were collected onto 2,4- dinitrophenylhydrazine cartridges for HPLC-HRMS analysis. The consecutive sampling with three DNPH cartridges shows a collection efficiency >98.4% for carbonyl-DNPH adducts in the first cartridge. Excess DNPH is conserved in the cartridge after the collection to maximize collection efficiency.

DNPH cartridges were extracted with 2 mL of acetonitrile into autosampler vials and analyzed by HPLC-HRMS. Consecutive extractions of DNPH cartridges for samples confirmed that >97% of both DNPH and its hydrazones were extracted after the first 2 mL volume of acetonitrile. The collection efficiency for cannabinoids is unknown, since only a limited amount of THC oil was available for experiment and not for quality controlcharacterizations. The high resolution mass data of cannabinoids is only used for identification in this work. Details on the collection method are described elsewhere. Moreover, glass fiber filters were used to collect the particles, as has been done in other e-cigarette studies. The particle mass collected on filters was determined gravimetrically on a microbalance by weighing the filter mass immediately before and after puffing at different experimental conditions. The standard deviation of the gravimetric analysis after triplicate measurements was determined to be ∼20%, mainly due to variations in puffing. The sample collection and analysis were performed in triplicate.Carbonyl compounds and acids from the thermal degradation of VEA and THC were derivatized by 2,4-DNPH to form carbonyl-DNPH compounds during the collection process. The detailed mechanism and method of identification for each carbonyl were described in previous work.40 Beside DNPH adducts, HRMS has been proven to be an effective tool for the detection of cannabinoids and their oxidative products, as the phenolic hydroxyl group in cannabinoids can be ionized in both electrospray ionization positive and negative modes, while the high mass precision enables the analysis of elemental composition. Negative mode was applied for the detection in this work as both carbonyl-DNPH adducts and cannabinoids can form negative ions by deprotonation. An external mass calibration was performed using the carbonyl-DNPH standard solution immediately prior to the MS analysis, such that the mass accuracy was adjusted to be approximately 1 ppm for standard compounds, the mass calibration was then applied to a molecular formula assignment for unknown compounds. All molecular assignments were analyzed by the MIDAS v.3.21 molecular formula calculator . Carbonyl-DNPH adducts and cannabinoids in extracts solution were separated and analyzed using an Agilent 1100 HPLC with an Poroshell EC-C18 column coupled to a linear-trap-quadrupole Orbitrap mass spectrometer with an ESI source at a mass resolving power of ∼60 000 m/Δm at m/z 400. The mobile phase of LC−MS grade water with 0.1% formic acid and acetonitrile were applied in the chromatography method. The analytes were eluted over the course of 45 min at 0.27 mL/min with the following gradient program: 40% B , 50% B , 60% B , 80% B , and 40% B . After separation by chromatography, single ion chromatography of each compound were extracted for the quantification of specific carbonyl compounds based on their calibrated m/z. Formaldehyde, acetaldehyde, acetone, butyraldehyde, valeraldehyde, hexanal were quantified using the analytical carbonyl-DNPH standards. The SIC peak separation between isomers of butyraldehyde/isobutyraldehyde, valeraldehyde/isovaleraldehyde hexanal/4-methylpentanal cannot be achieved, so the concentration of all isomers were calculated as a total amount. The concentrations of glyoxal, methylglyoxal, diacetyl were calculated by an estimated ESI sensitivity as described by Li et al.40The thermal degradation of both VEA and THC was observed at the measured coil temperature of 455 ± 10 °F , which is close to temperature that VEA started to degrade in the work of Riordan-Short et al..

Underscoring the limits to garden accessibility in Milwaukee, distance to the nearest garden appears to be increasing over time. While gardens appear to be distributed in a way that makes them more accessible for marginalized groups than for more privileged ones, the gardens are becoming less accessible in general.In Seattle, Philadelphia, and Milwaukee, the primary organizations involved in building, maintaining, and defending the city’s gardens worked to gain legitimacy for themselves and, in the process, served to legitimize urban agriculture as a land use—selecting from among its many potential benefits to construct a narrative that served their organizational interests and priorities. The organizations discussed in this dissertation identified different target audiences for their legitimizing efforts, faced different challenges in gaining or maintaining legitimacy, and ultimately advanced the legitimacy of urban agriculture along different lines. As this dissertation demonstrates, variations in how urban agriculture has been legitimized have impacted the socio-natural spaces constructed in each city and the strength of arguments for long-term site preservation in the face of potential redevelopment. As it worked to gain legitimacy, Milwaukee Urban Gardens found more success as a garden support organization than it did as a land trust; as it has undertaken more programming and site maintenance over the years, Milwaukee Urban Gardens has joined with other organizations in the city to frame urban agriculture as a legitimate land use for its job training, employment and commercial potential. Urban farms are the focal point in Milwaukee, and greening is the focal point in Philadelphia, where the Pennsylvania Horticultural Society gradually evolved its Philadelphia Green program toward blight removal and neighborhood revitalization.

In recent years, this framing for the value of urban agriculture has been contested by Soil Generation, a Black- and Brown-led coalition advocating for more permanent gardens, affordable housing, and community control over land use more generally, vertical farming supplies advancing a new frame that ties urban agriculture’s legitimacy to the stewardship of longtime residents and the unjust history of dispossession they have experienced. In Seattle, the P-Patch program worked to legitimize its activities for the benefits of food production and community-building that community gardens can provide, and advocates with the P-Patch nonprofit refined this narrative over time by articulating how urban agriculture serves as a neighborhood amenity that could ease some of the strain of urban growth while attracting desirable new residents. In all three cities, economic arguments have been central to strengthening the legitimacy of urban agriculture in the eyes of city officials in order to secure more resources and favorable policy for the gardening organizations and their spaces. However, these economically focused arguments also cohere with processes perpetuating inequality in urban environments. In the case of Milwaukee’s employment emphasis and PHS’s revitalization framing, economically focused arguments have served to reinforce the conception of urban agriculture as a temporary use of urban space that can and should be replaced with more profitable development whenever the opportunity arises. In Seattle, framing that augments urban agriculture’s legitimacy as a source of livability amidst intensifying urban development overlooks the fact that rapidly appreciating neighborhoods become unlivable for residents at the bottom of the income distribution, who end up with greater food insecurity and likelihood of displacement regardless of garden permanence. Just as the different ways of framing urban agriculture’s benefit have been unequally strong as a claim for garden permanence, the different organizational configurations and environments in each city have been unequally conducive to social movement mobilization that could challenge elite interests and push city officials beyond their original willingness for garden preservation.

In terms of the organizational environment, evidence from Milwaukee and Seattle indicates that civic conventions conducive to bottom-up governance work to support the process of legitimizing urban agriculture, but it appears to have been the discursive opportunity structure of mistrusting elites, absent in Milwaukee but present in both Philadelphia and Seattle, that has facilitated mobilization in defense of threatened urban agricultural spaces. Different organizational configurations across the three case-cities are instructive for understanding the dynamics of organizational hybridization, especially from community-based to social movement activities. Across the three cases, I found only one example of a community-based organization effectively taking up the work of a social movement organization —the P-Patch nonprofit. Developed as a parallel organization to support the city’s P-Patch program by providing a forum for volunteer site leaders to share strategies for garden management, the P-Patch nonprofit gained legitimacy as a representative of gardener interests while maintaining an organizational structure independent from the city program that allowed for outsider social movement mobilization when needed. Both of these features facilitated the P-Patch nonprofit’s success in SMO activities, but these activities were organized on a temporary basis, and their framing reflected the relatively privileged perspectives of the nonprofit’s volunteer leaders. In contrast, Soil Generation has arisen in Philadelphia as a counterpoint to PHS, a CBO that did not prioritize gaining legitimacy from gardeners and has been perceived as coopted because of its close relationship with city leaders. Soil Generation has functioned as a SMO since its inception and has kept up its social movement activities for the long term. With leadership explicitly oriented to the needs of poor people of color, Soil Generation is advancing a frame that re-legitimizes urban agriculture as worthy of permanence, while also insisting on policy that will address the broader needs of the city’s low-income gardeners—especially their need for affordable housing. While not generalizable to all organizations in all cities, comparing the example of Soil Generation to the other organizations in this study suggests that organizations formed with a social movement orientation may simply be better positioned to advocate for policies that run counter to elite interests than organizations formed as community-based organizations to provide services.

In Milwaukee, none of the organizations involved in building, maintaining, or advocating for urban gardens can really be considered a social movement organization. The main community-based organization that manages gardens in the city, Milwaukee Urban Gardens and now Groundwork Milwaukee, has occasionally called for gardeners to write letters on behalf of a favorable policy, but the group has never organized to pressure city officials for garden preservation or other policies that go beyond what the city is interested in doing for its own interests. Similar to PHS in Philadelphia, Groundwork Milwaukee now draws a decent share of its funding from green space maintenance contracts with the city, establishing organizational commitments that would conflict with outsider strategies for social movement mobilization. Across the three case-cities, evidence suggests that the switch from CBO to SMO is challenging because CBOs often must seek resources and legitimacy from city officials, large funders, and other elites; over time, their work as service providers appears to build up connections and commitments to other organizations that can leave them coopted or less focused on the needs of more marginalized members, clients, and constituencies. Of course, this finding only reflects analysis of a small sample of organizations, and additional research with larger samples would be needed to confirm if this pattern is widespread, but it conforms with earlier findings about the process of organizational cooptation over time . While Groundwork Milwaukee provides one example of a CBO unlikely to take up confrontational politics, the Milwaukee Food Council is an organization more like Soil Generation that was formed to advance policy goals, cannabis indoor greenhouse and due to its relative independence from the local government this organization might be better positioned for outsider strategies of social movement mobilization. However, the Milwaukee Food Council mostly counts leaders from other organizations as its members and does not have much of a direct relationship with gardeners or the general public. In other words, unlike Soil Generation, the Milwaukee Food Council has not gained legitimacy as a representative of the city’s gardeners and marginalized residents. Even if the Milwaukee Food Council had legitimacy as a representative of gardeners and a large, active base of supporters to mobilize in the push for more permanent urban agricultural spaces, because of the benefits for which urban agriculture has been legitimized in Milwaukee, the city’s civic conventions, and the political-economic reality in which currently cultivated lots are seen as a potential development lifeline for reviving the city’s economy, this organization would still face a steep challenge in convincing city officials or the general public that permanent gardens are the best policy. Across all three cities, the legitimation activities of garden organizations and the policies they have achieved to increase longevity for the city’s gardens are reflected in the physical manifestations and geographical distribution of gardens. While there are certainly similarities between the community gardens in all three cities, the forms and ideas about urban agriculture that people are likely to encounter as they move through urban space are different. Among the three cities, the prevalent urban agricultural forms in Milwaukee can be understood as the most impermanent. In Milwaukee, one is more likely to observe large, mowed lots with only a few trees or garden beds that represent the legacy of MUG’s early attempts to function as a land trust, which backfired when these sites did not have enough support or interest from nearby residents to be maintained in full form. This particular form is certainly not widespread in Milwaukee, but it is virtually absent in the other case-cities and it serves to reinforce ideas about community gardens as temporary land uses. Another distinct feature of Milwaukee’s urban agriculture landscape is the prevalence of youth job training programs and food businesses that package and distribute items grown on urban farms. Someone moving through the city is as likely to encounter a site where young people work together to tend crops as they are to encounter a community garden with individual plots claimed and cared for by different people. Both of these urban agricultural forms can provide important nutritional and social benefits for people in need, but the employment and commerce-oriented nature of Milwaukee’s urban agriculture leaves open more possibility for relocating urban agriculture to make way for other kinds of development. In Philadelphia, there are numerous traditional community gardens—certainly more than in Seattle or Milwaukee—but their presence is dwarfed by the 13,000 vacant lots that are maintained with PHS’s signature clean-and-green treatment. As in Milwaukee, this form of urban agriculture signals impermanence, but unlike the spaces tended by Milwaukee’s youth these sites are not growing food—only trees and a few ornamental plants that can be easily kept up by the circulating maintenance crews. Someone moving through the city is more likely to encounter a clean-and-green lot than a community garden or farm, but many such spaces do exist. Some of these spaces announcing themselves with signs, murals, and tributes to groups who have ensured their existence, while others keep a low profile to avoid what gardeners perceive as the likelihood the city will sell the lot if they learn it has a garden. Regardless of their outward appearance, and despite not being the focus of the legitimizing narrative that PHS amplified for many years, hundreds of gardens in Philadelphia have provided food, a sense of community, and other benefits to residents in many neighborhoods. In Seattle, the most common form of urban agriculture is the P-Patch community garden, most of which have individually tended plots and common areas with space for the public to sit and enjoy urban nature. Someone moving through the city is likely to encounter a P-Patch with signage announcing the program and perhaps an upcoming community event to be held in the space. These elements reflect the strategic efforts that P-Patch advocates have made over the years to bolster the program’s legitimacy in the eyes of city officials and the non-gardening public, given that they have secured virtual permanence for the gardens as a land use, but must still work to maintain the spaces’ public legitimacy and funding. As we consider what form of urban agriculture someone might encounter as they move through each city, we should also consider who is likely to be having the encounter in the first place. Over time, as one part of the wider urban processes of economic competition and land use contestation, organization-led efforts to legitimize and secure urban agricultural spaces have not only influenced the form that these spaces take, but also where the gardens have survived and who is most likely to be occupying nearby urban space to begin with.

As the US economy is shifting away from manufacturing, Florida argued, continued growth derives from an ascendant group of workers he called the “creative class”—people who work in science, technology, engineering, design, and other knowledge-based sectors . Because their work is intellectual rather than physical, these individuals are not as tied to particular locations, and they can choose to live in whichever cities they find attractive; in other words, particular types of use value can serve as a basis for increasing exchange value. The types of use value most important to the creative class include diversity, individual expression, and loose community with many weak social ties . Indeed, Florida highlighted Seattle as a creative city with all the ingredients to attract the creative class, and the P-Patches are exemplary of the urban character that Seattle was offering: they are filled with art and with all different kinds of people getting to know one another in loose communities . Without having the vocabulary of creative cities, P-Patch advocates in the 1990s framed the value of their gardens for city leaders in terms that align well with attracting the creative class. While the theory of creative cities appears to offer a resolution to the tension between use and exchange value in urban growth dynamics, in reality the tension is simply displaced. Urban growth entrepreneurs were quick to take up Florida’s ideas in their development strategies, and critics were equally quick to decry the downsides . Florida himself acknowledged that creative cities tend to have higher levels of inequality as the economy is increasingly bifurcated into a creative class and a service class . People in creative cities who do not belong to the creative class cannot fully enjoy the benefits of its use-value-rich amenities. The increasing exchange value in hip neighborhoods—or, in cities such as Seattle, hydroponic racks all neighborhoods—contributes to higher rents and displacement of lower income and marginalized people .

Furthermore, while creative cities make a show of celebrating racial and ethnic diversity, the reality is often a superficial multiculturalism lacking substantial engagement with institutional racism and the inequalities it produces . In creative cities, the downsides of increasing exchange value are borne even more heavily by marginalized people. This diminished use value is just easier for a creative city’s more affluent residents to ignore than the traditional downsides of growth such as noise, traffic and air pollution—pervasive downsides that P-Patches help ameliorate for Seattleites. For the last 30 years, the political economy of Seattle has enabled continued investment that has helped solidify the status of the city’s community gardens, but nothing about this political economy ensures that the gardens are providing the potential benefits most needed by the city’s marginalized residents—or even that they remain accessible to these communities at all. The city’s gardens do produce a lot of food, with some of it directly feeding low-income gardeners in the P-Patch program and other gardens such as the Danny Woo International District Community Garden, which serves primarily Asian-American residents of nearby affordable housing. As described in chapter 3, the City ensured that as its P-Patch program expanded, new gardens accessible to low-income residents were prioritized, and P-Patch gardeners also grow tons of fresh produce for the city’s food banks. Food bank donation is a longstanding tradition in the P-Patches, but it is not a requirement for participants and is contingent upon the available time and generosity of current gardeners. In good years, the total amount of produce donated by P-Patch gardeners exceeds 40,000 pounds; however, as Seattle has become increasingly unaffordable, the number of people relying on food banks has also increased. Even before the pandemic, food banks were distributing more than 22,885,000 pounds of food a year .

From 2007 to 2011, average monthly visits to food banks in Seattle doubled from 61,401 to 122,197 . The rate of food insecurity in Seattle grew from 7% in 2007 to 13% in 2019 . The fresh, organic produce that flows from P-Patches to low-income gardeners and other food-insecure Seattleites is not insignificant, but the rate of growth in food bank donations is not keeping up with the rate of growth in rents and attendant growth in food insecurity. Food provision is one of the key benefits that urban gardens can offer low-income residents, but others matter as well. Low-income neighborhoods tend to suffer from more blight, higher crime rates, and lower neighborhood social cohesion, and gardens have been extolled for their potential to improve low-income neighborhoods along these dimensions. However, if the neighborhoods become unaffordable for low-income people, then those residents have to move, and the neighborhoods’ improvements are moot for them. In Seattle, over the last two decades since garden advocates won preservation victories and significant resources to expand the P-Patch program, real estate values have also increased dramatically citywide . Staggering increases in median home values—up 93% from 2012 to 2018—have priced many people out of formerly affordable neighborhoods or out of the city entirely . As one outcome of this extreme housing market, the Laotian gardeners who helped build Bradner Gardens Park in the 1990s can no longer afford to live in the surrounding neighborhood. Overall, the program has evolved toward benefitting low-income residents because of its public mission and some of its partnerships, and P-Patch gardeners have long celebrated their racial and ethnic diversity although it does not seem that a lot of effort was put into cultivating leadership from minority communities. The social movement mobilized to prevent program cuts in the early 1990s and preserve threatened P-Patches thereafter was led by gardeners who were active in the P-Patch nonprofit.

Unlike the Pennsylvania Horticultural Society, this organization was seen as a legitimate representative of gardeners’ interests, but the movement the organization built was not framed around or led by gardeners of color, immigrants, or low-income people. This movement has been extremely effective at preserving community gardens and ensuring that public resources continue to support these spaces; today, P-Patch advocates quickly organize to protect any sites that become threatened . The P-Patch nonprofit has many of the features known to contribute to social movement success: skilled and experienced leadership, an engaged constituency, legitimacy in the eyes of decision-makers and the public, and sophisticated framing that resonates with their target audiences. However, this movement has been organized narrowly around preserving the P-Patches—resisting one of the symptoms of unrestrained urban growth, rather than challenging the logic of growth overall or any of its other ill effects. As Seattle real estate values continue to balloon, microgreen grow rack displacement continues apace, and the framing for preserving P-Patches does not address the detrimental impacts of growth on poor gardeners, residents of color, or others vulnerable to the ongoing displacement.Evidence from the three case-cities indicates that a local government’s ability to support urban agriculture is tied to its economic and fiscal situation. Of course, the status of the locality within the ongoing global competition to attract growth matters for the amount of resources available to invest in urban gardens. Since cities are continuously engaged in this competition, their status is always subject to change, and potential change in the city’s economic fortunes remains a top concern of elected officials and growth elites regardless of the city’s current success or failure in attracting urban growth. The history of all three cities shows that framing urban agriculture as a valuable tool to improve or insure a city’s economic standing has been an effective strategy for winning favorable policy and public investment. The appeal to growth interests has taken on different forms in the different economic and political contexts of each city, and in all three cases these economic rationales have consequences for the city’s gardens and/or for its marginalized residents. In Seattle, as the city was beginning to experience urban growth due to its strong technology sector, P-Patch advocates refined their efforts to legitimize community gardens by framing them as a neighborhood amenity that ameliorates some ill effects of urban growth, building a case to value gardened land alongside housing and commercial development and furthering the commodification of nature as a selling point for the city’s livability. This refined framing presents urban agriculture as a palliative for the alienation from nature and fellow humans that often occurs with urbanization . However, it does not address other social impacts of rising property values—particularly the affordability crisis that displaces the city’s low-income residents.

In Philadelphia, where economic downturn and disinvestment left 40,000 lots across the city vacant, PHS and other growth coalition members successfully argued that this land was a liability for the city, and that repurposing it for greening would help revitalize blighted neighborhoods and attract new capital investment. They were right; Philadelphia has turned its fortunes around and is now experiencing renewed urban growth, including rapidly increasing land values and gentrification in some of the city’s neighborhoods. With the floodgates opening to capital flows, gardens are getting swept away. Now, Soil Generation and its allies are trying to push back on the commodification of nature as a symbol of investment readiness that can flip vacant land from liability to asset, shifting the focus to the community members who have stewarded these spaces and arguing that they deserve to retain them—an outcome that would necessitate both the gardens and the gardeners being able to stay in place. In order for this to occur, the city’s Land Bank must implement its directives in a way that prioritizes community land uses in gentrifying neighborhoods, an uphill battle given the immense amounts of capital held by growth entrepreneurs vying for ownership of these spaces. Soil Generation’s ongoing organizing and framing around community control works to put power behind this struggle, and they have accomplished some early victories in framing the Land Bank’s mandate and revising the disposition process; however, it remains to be seen what the movement will ultimately achieve in terms of garden preservation and affordable housing. In Milwaukee, the city is still struggling to win greater capital investment and urban growth, and land is seen as a lifeline for this effort. Urban nature in the form of gardens and farms has been commodified as a tool for training and employing residents, a potential pathway to economic development that can ameliorate some of the worst impacts of capital flight that the city has experienced. Despite its poor fiscal situation, the cash-strapped city government still shows willingness to devote some resources and recruit public and private partners to invest in urban agricultural spaces. However, like PHS’s framing in Philadelphia, Milwaukee’s commodification of urban nature as training ground and space of economic production leaves open the ongoing possibility of replacing gardens and farms with any more profitable use that might come along.The preceding chapters have revealed how the main community garden programs and proponents in each city highlighted some of urban agriculture’s potential benefits over others, influencing the priorities for how community gardens were developed and managed over time. In addition to assessing what benefits community gardens are providing to surrounding neighborhoods, we can better understand their impact on a city by investigating where community gardens are located, and thus to which neighborhoods their benefits are accruing. As noted throughout this study, many of the benefits for which community gardens are celebrated are particularly important for low-income communities and marginalized racial and ethnic groups. The free or low-cost fresh produce these spaces can yield will matter most for food-insecure households, often associated with high-poverty neighborhoods and those with a higher proportion of Black and/or Latino residents . Urban blight, crime, and inadequate greenspace are also more common in neighborhoods with these characteristics, so the value of community gardens as safe, attractive, and healthy greenspace is also especially salient in such areas . Community gardens can support important cultural practices as well, since ways of growing food and medicine are meaningful traditions for virtually every culture. In this regard, the ability for immigrants to access community gardens is another key consideration for understanding whether urban agriculture’s touted benefits are available to those who need them most.As with any alternative food initiative, there is no guarantee that the benefits of urban agriculture will accrue to those who are most in need.

As chapter 5 will detail, longitudinal spatial analysis demonstrates that between 1980 and 2019, P-Patch gardens have become more accessible overall; moreover high-poverty neighborhoods in Seattle were originally further from the PPatch gardens than their lower-poverty counterparts, but that relationship has flipped over time such that proximity is greater for low-income communities today. Finally, in response to the “persistent skepticism” about gardens as a private use of public land, as Frank Kirk’s quote above describes, the P-Patch program leaders systematically incorporated public spaces into design and redesign plans for the gardens. In my analysis of PPatch Post newsletters, the code design for community was only applied twice for issues in the 1980s, but this code came up more and more often in the 1990s and especially from 1998 onward. New gardens were built with public features like benches or picnic tables, and such elements were added to the older gardens as they were renovated—especially when those gardens won Neighborhood Matching Funds to improve their spaces. Because of the civic infrastructure in Seattle, including numerous channels of communication between garden advocates, city officials, and other residents as well as the availability of public resources for garden development, P-Patch gardeners were able to maintain legitimacy for their organization and for the use of public land for urban agriculture by aligning their activities with widely shared values and public priorities. The priorities of city officials and P-Patch gardeners were not always perfectly aligned, however. As mentioned earlier, two P-Patches on public land were threatened by development in the mid-1990s. Gardeners first pressed their interests through the city’s bottom-up governance infrastructure, but it soon became clear they would not prevail through insider strategies .

While Seattle’s political opportunity structure is usually amenable to resident interests, indoor plant table competing resident demands—and the growth machine’s drive for increasing exchange value—exerted strong countervailing influence in these cases. When insider strategies proved futile, the garden advocates pursued outsider strategies to organize public opposition to the development plans. In this period of mobilization, Seattle’s civic conventions promoting distrust of elite control and expecting neighborhood involvement in decision-making helped form a discursive opportunity structure for framing the threat of garden loss in a way that would resonate well beyond the gardens. When the gardeners at the Mount Baker P-Patch learned that their city-owned lot was slated to be auctioned off for housing development, they joined with the local neighborhood association to come up with an alternative plan. With a grant from the Neighborhood Matching Fund, they conducted design charettes with P-Patchers, representatives of greening organizations, and other residents. The final product, a plan for Bradner Gardens Park, interwove P-Patches with numerous other uses such as a basketball court, family picnic area, public art, and native planting demonstration gardens. Advocates for Bradner Gardens Park presented the plan to city officials, and also visited the meetings of neighborhood associations from across the city to gain their endorsements. They built up legitimacy for the Park proposal through the civic infrastructure of Neighborhood Matching Funds and neighborhood association endorsements, and they framed their proposal as the epitome of neighborhood planning, civic participation and collaboration among diverse groups in a community. City leaders remained steadfast in their desire to see housing on the site, however, so the garden advocates devised an initiative to prevent the auction. With the help of a former were reneging on their previous deal.The argument that the city could not be trusted helped to whip up opposition to the proposed move, and it also resonated with one council member who reportedly didn’t care about PPatches but was moved by the argument about fairness.

Ultimately, council members did approve a plan to move the garden, but only on the condition that gardeners were given a better replacement site and logistical and material support for the move. These concessions made a big difference for the future direction of the Interbay P-Patch, which is a thriving community garden and destination for neighborhood residents today. In both of these cases, Seattle’s garden advocates were able to strike a nerve for the general public by framing the city’s plans as a betrayal of the self-government expectations they held, and by arguing that these moves needed to be resisted in order to hold the government accountable to its citizens. Ultimately, in both cases, council members originally opposed to the gardeners’ requests ended up voting in their favor. The garden advocates’ leveraging of Seattle’s civic conventions is evident in analysis of documents and interviews from the three cities, which shows that the code for fairness or justice was more than twice as common in Seattle as in Philadelphia and more than three times as common as in Milwaukee. The bulk of these codes applied to documents in the period of October 1995 to September 1996, when the Bradner and Interbay resistance efforts were broadening from insider strategies into outsider strategies involving criticism of the city and mobilization of both gardeners and the public. These examples demonstrate how social movement mobilization was effective in Seattle and accomplished long-term preservation for many of the city’s gardens. However, the movement mobilized in the mid-1990s was framed around a symptom—development threats to specific gardens—and not around the underlying economic dynamics driving garden displacement. While all of the gardens on public land are effectively permanent thanks to movement organizers’ victory in passing Initiative 42, gentrification has continued apace in Seattle; among the many low-income residents who have been displaced due to rising housing costs are gardeners who can no longer afford to live near the sites they helped to build, including Bradner Gardens Park.

In this way, the local garden preservation movement in Seattle draws a clear contrast with that in Philadelphia, where garden loss is framed in connection to the broader context of structural racism, neighborhood disinvestment, and growth machine logic that threatens vulnerable people as well as vulnerable spaces.This chapter has demonstrated multiple ways that civic conventions structure opportunities for garden organizations to legitimize their activities and to build broader support for urban agriculture as a land use. Civic institutions that support public input into policy making have served as political opportunity structures to legitimize urban agriculture as a land use desired by residents. Civic ideas can serve as a discursive opportunity structure that garden advocates can leverage to frame the need for social movement mobilization in support of threatened gardens, whether or not these spaces have gained legitimacy through formal policy channels. When a city’s civic conventions include infrastructure for bottom-up governance, this infrastructure provides a political opportunity structure for supporting resident demands such as space for community gardens and urban agriculture. A participatory governing process can rationalize garden development in accordance with broader public interests and concerns while building legitimacy for community gardens as a land use. Garden organizations in Seattle and Milwaukee have bolstered the legitimacy of their gardens by taking advantage of civic conventions conducive to bottom-up governance, including the civic infrastructure of grant programs for resident-initiated projects and accepted channels for communicating resident desires. In these cities, conventions for bottom-up governance provided a political opportunity structure to legitimate urban agriculture as an activity in line with broader public priorities. The same political opportunity structure did not exist in Philadelphia, where PHS established legitimacy for its Philadelphia Green program as a provider of city beautification services and a catalyst for neighborhood reinvestment, with less emphasis on the importance of fulfilling resident desires for growing space. Instead, gardens in Philadelphia struggled to gain legitimacy in the eyes of city officials even as many such spaces were used and valued by neighborhood residents. The city’s redevelopment efforts led to the loss of numerous gardens in the early 2000s, plant growing stand when city officials treated these spaces as “vacant” rather than land already under legitimate use. With PHS having legitimized its garden support activities as temporary measures to promote redevelopment, the organization was not positioned to challenge the loss of gardens through that very redevelopment. Indeed, due to PHS’s dependence on city contracts for greening services and its association with the city’s social elite, the organization stood to lose legitimacy in any open confrontation with public officials. When PHS did not mobilize its gardeners to challenge the city’s land use policies, another organization did. Situating the pattern of garden removal in the historical context of dispossession and racial injustice, Soil Generation has mobilized the city’s growers to push for greater community control over land use decisions. Their framing legitimizes urban agriculture as stewardship of land long abandoned by property owners and the city, while delegitimizing the city’s development plans by drawing on widely shared cynicism about the government’s effectiveness and trustworthiness. This cynicism has provided a discursive opportunity structure in which calls for ongoing mobilization to ensure government accountability have resonated widely. In coalition with other groups organizing for economic and racial justice, Soil Generation has gained legitimacy as a genuine representative of the interests of gardeners and communities of color in the city, and the organization has sustained outsider strategies to pressure the city government to transfer land ownership to community gardeners. Discursive opportunity structures in Seattle have similarly supported social movement mobilization when gardeners sought to preserve gardens and public officials resisted.

Widely shared ideas about the value of civic participation underlay the development of the P-Patch nonprofit, its successful cultivation of volunteer labor over decades, and its mobilization to stave off garden loss and achieve permanence for the P-Patches. As in Philadelphia, civic ideas about distrust of elites contributed powerfully to the local discursive opportunity structure; by framing Initiative 42 as a necessary bulwark against city officials selling off parks, P-Patch advocates won broad public support for their proposal and secured stronger protections for the city’s gardens than public officials were initially wiling to enact. In contrast, Milwaukee’s civic conventions hold more of an assumption of good governance on the part of city officials, and the local discursive opportunity structure has been far less favorable to social movement mobilization. Garden advocates have achieved longer term land access and more permissive zoning policy through insider political strategies, but many gardens in Milwaukee remain classified as a temporary use. Without an organized effort to engage gardeners in civic action, and without a widely held belief in the need to mobilize to hold the government accountable, the city’s garden advocates seem to lack the tools to pressure city officials into making more gardens permanent. In terms of urban political economy, insider strategies that frame urban agriculture’s value to align with the city government’s priorities will likely reflect growth machine logic. Land use policies that elected officials will happily pass, such as small matching grants to support green space improvements and ordinances allowing beekeeping, tend to increase use value for residents in ways that do not undermine the potential for increasing exchange value as well. To achieve permanent tenure for community gardens and urban farms means removing the land from the city’s development portfolio—something that runs counter to the standard motivations of most city officials. The cases of Philadelphia and Seattle demonstrate how garden advocacy organizations have mobilized social movement activity by drawing on discursive opportunity structures to successfully frame the need for garden permanence as part of a wider struggle to preserve resident interests in the face of potential political corruption. Alongside these more confrontational efforts, organizations in both Philadelphia and Seattle also used insider strategies for some of their efforts to legitimize gardens. As Chapter 4 will explain, growth machine logic endures as a powerful force in shaping the framing, policy, and practice of urban agriculture in all three cities.A city’s civic conventions form an important piece of the organizational environment in which community gardening programs develop and define themselves. Yet what is possible for urban agriculture in any given city is also contingent upon its political-economic context. As urban political ecologists would describe it, ideas about appropriate uses for urban space combine with material flows and conditions, as well as ideas governing the legitimacy of governments themselves, in order to determine the actual production of urban socio-nature . In this regard, the distribution and character of urban agriculture in any city is influenced by local economic pressures, the sources and extent of public resources, and political factors at larger scales such as the laws and activities of state and federal governments.

This is not to say that active racial bias was applied in hiring and appointing leaders, rather that low or no pay likely served as a barrier for gardeners of color in light of persistent racial wealth gaps . The demographics of P-Patch leadership are likely to have impacted the perspective from which both organizations operated, especially the framing of the benefits of community gardens. P-Patch volunteers assiduously grew and measured their food bank donations, which have no doubt been helpful for food insecure Seattleites; however, produce distributed through food banks treats the symptom of hunger, rather than its root cause of economic inequality . Likewise, community building is an important and hard to measure process for maintaining healthy social dynamics in cities . However, when community-building is framed as a relief-valve for the pressures of increasing urbanization, as was often the case in the P-Patch’s framing, it reflects an ideological orientation that seeks to accommodate rather than challenge ideas of inexorable urban growth. Moreover, as Chapter 4 will explain, the sense of community engendered in the P-Patches is part of what has made Seattle such an attractive city for the “creative class” whose purchasing power and population growth have contributed to gentrification in most Seattle neighborhoods. Among the three case-cities, Seattle’s urban agriculture movement, in particular the organized efforts to preserve P-Patches in the 1990s, grow table has been the most effective so far at accomplishing policy change that secures community gardens as a permanent land use.

The organizational structure, pairing a city-run garden program with a nonprofit fundraising and advocacy organization, appears to have worked very well to develop and manage gardens in a stable way while facilitating gardener mobilization when needed and encouraging leadership from gardeners themselves. However, gardeners from more marginalized communities have almost never taken on these leadership roles, and the mobilization to protect gardens has not addressed the question of securing low-income gardeners themselves in the neighborhoods they have helped to shape.Urban agriculture has gained legitimacy as a land use in each of the three case-cities, and the benefits with which it is most associated reflect the strategies that the main gardening organizations in each city have pursued to gain and maintain their own legitimacy. In Milwaukee, MUG attempted to gain legitimacy as a land trust, but when they were unsuccessful in convincing a sufficient donor audience that garden preservation was a meaningful cause, MUG ultimately joined Growing Power, Walnut Way and the Victory Gardens Initiative in focusing on youth engagement and employment. Together, these organizations built legitimacy for urban agriculture as a tool for job training and economic development. Philadelphia Green gained legitimacy as a program of the well-established Pennsylvania Horticultural Society, and in working to maintain its legitimacy for the organization’s donor base, program leaders demonstrated how greening can work as a tool for blight removal and neighborhood revitalization. However, PHS and Philadelphia Green did not invest as much effort in building the program’s legitimacy with urban gardeners themselves, and another group has claimed that role. When community organizers were mobilizing to change city policy and defend threatened gardens, they ultimately removed PHS from their coalition and formed Soil Generation, an organization staking its legitimacy on its representation of Black and Brown growers in the city.

Rejecting the notion that urban agriculture is a legitimate land use mainly for its revitalization potential, Soil Generation is framing the need for preservation as an issue of community control over land use decisions. The City of Seattle’s original funding for the P-Patch Program was legitimized as support for recreation, but the program and its advocates have maintained legitimacy over time by documenting and emphasizing other benefits more in keeping with the departments in which the program has been housed—that is, providing food for people in need and a network of community-building spaces that bring diverse people together . While urban agriculture has been legitimized as a land use in all three case-cities, the different framings do not all translate equally well into making claims about the need to preserve community gardens in the face of more profitable potential land uses. For example, the economic development potential of urban agriculture confers legitimacy on such spaces, but does not preclude replacement with another form of development that would likely yield more jobs. Legitimacy is built up over time; once urban agriculture has come to be associated with particular benefits in a given locale, shifting the narrative proves more difficult. Furthermore, shifting an organization’s emphasis becomes more difficult once that organization has gained legitimacy and built up ties and commitments with other organizations in its environment. The challenge of gaining legitimacy to begin with was more difficult for MUG than for Philadelphia Green or the P-Patch program and its supporting nonprofit, because MUG lacked any affiliation with an existing, already-legitimized organization. When seeking policy change to increase land tenure for gardens, MUG, Philadelphia Green and the P-Patch Program all erred on the side of insider advocacy, having built close relationships with city agencies . When insider strategies were not enough, the P-Patch nonprofit had relatively more flexibility than these groups to parlay its organizational legitimacy into social movement organizing.

Since the PPatch nonprofit had gained legitimacy as a forum for supporting gardeners, rather than as a garden site administrator, its primary legitimizing audience was the gardeners themselves, and the organization depended relatively less on approval from city officials. Framing appeals for collective action as looking out for the interests of its primary, already-engaged audience, the PPatch nonprofit was able to take up the function of a social movement organization with relative ease . Finally, let us consider how the various organizations’ efforts to legitimize their operations have impacted the physical institutionalization of urban agriculture within each city’s landscape. For example, most Milwaukee residents and visitors are just as likely to encounter young people selling cottage goods made from produce they grew as they would be to encounter the space in which the products were grown. Given the relative scope of Philadelphia Green’s different projects, residents and visitors in Philadelphia are far more likely to see lots with the “clean-and-green” treatment than they are to see community gardens. Meanwhile in Seattle, the P-Patch gardens have been gradually developed into public gathering spaces rather than just growing spaces, and residents and visitors are increasingly likely to encounter them as inviting, park-like places. Thus, the organizations have legitimized urban agriculture around some benefits rather than others, not only discursively through media coverage, publicity, vertical rack and political engagement, but also materially through the manifestations of their work that reinforce particular ideas about urban nature.Organizational sociologists and social movement scholars have long emphasized the influence of external factors on organizational practices and outcomes . Yet an aspect of the organizational environment that has not received much attention in the literature is the locality’s civic conventions . Civic conventions are shared beliefs about expected and acceptable forms of interaction between the government and the polity, an institutionalized understanding of “how we do things around here” . This chapter will demonstrate how civic conventions are especially influential for hybrid organizations as they attempt to expand into a new organizational function which positions them differently with respect to civic action. Deploying the concept of civic conventions, I contribute to the literature on hybrid organizational forms by exploring the dynamics at work when service providers take on social movement work, rather than the reverse scenario described by Minkoff . Unlike hybrid organizations that begin as movement organizations and later take up service provision as a form of civic action, urban agriculture groups initially work to organize communities in the civic action of transforming land and must then take up social movement work later, when the transformed land becomes threatened. In doing so, garden organizations must navigate idiosyncratic local expectations regarding civic and political engagement. Organizations that build their legitimacy around social movement activities may be able to push the boundaries of local civic conventions, but organizations that are legitimized for community service provision face an extra challenge in gaining legitimacy for new activities, and thus pressure to conform to extant civic conventions is stronger. Building connections between organizational theory and the literature on social movements, I argue that the local civic conventions can be understood as a combination of political and discursive opportunity structures, working together to shape the terrain on which hybrid organizations cultivate civic participation of various forms among some or all of their members.

When they first form, urban garden organizations must work to establish legitimacy for themselves as community-based service providers. In order for a garden organization to be viewed as legitimate, the gardeners must be seen as contributing to the public good rather than as benefitting unfairly from public resources such as land and water. Even when urban garden organizations become familiar and widely accepted in a city, the use of urban land for agriculture is almost always viewed as a temporary practice . Once gardens are established, they often become quite meaningful to the gardeners and those living nearby; this emotional connection makes the loss or removal of the garden a difficult prospect. Facing an impending removal or changing economic conditions that increase gardens’ vulnerability to development, garden organizations must work to build a new kind of legitimacy for urban agriculture as a permanent fixture of the urban landscape. This effort requires new framing processes and political strategies, often including social movement mobilization. The strategies that can be pursued at this point will depend somewhat on the local civic conventions, as well as the existing frames that have been used to legitimize garden organizations.In this chapter, I highlight the role of civic conventions throughout the life of urban garden organizations and the movements they spur to preserve urban agriculture as a land use. When urban garden programs are building their initial legitimacy, when gardens are about to be replaced with a different land use, or when garden advocates propose a change in local policy that would increase the long-term security of growing spaces, they can build strategies that draw on local civic conventions to amass broader support from the general public . I discuss two main ways that civic conventions can promote garden legitimation at these different points in time. First, civic conventions conducive to bottom-up governance can help build the legitimacy of urban agriculture as garden organizations are getting started and seeking out basic resources and support—in other words, as the garden programs are seeking to gain legitimacy as community-based organizations. Like other resident activities and use-value rich land uses, urban agriculture tends to have its strongest base of support at the grassroots level. If the municipal government is generally receptive to resident preferences and interests, this convention creates a relatively easy way for resident demands for urban agriculture to be incorporated rationally into local policy. In Seattle and, to a lesser extent, in Milwaukee, civic conventions which held that city officials should be receptive to bottom-up governance created many opportunities for residents to express their desire to use vacant land for growing food directly to key decision-makers, and the cities’ main garden organizations and policies gained legitimacy through this process. Conversely, in the case of Philadelphia, civic conventions carry far less expectation for bottom-up governance. In this city, cynicism about government runs high in part because of a complex, opaque bureaucracy that seems to discourage formal resident input. In this case, when cultivated lots were being sold without gardeners’ prior knowledge or input, lack of access to decision-making and perceived injustice became rallying cries for broader mobilization around community control of land and urban planning. Comparing the social movement dynamics in Milwaukee, Philadelphia, and Seattle, in this chapter I show how civic conventions present a landscape of discursive and political opportunity structures that hinder or make possible certain strategies for achieving an organization’s desired policy outcomes. Civic conventions that exist as widely shared ideas about what is unacceptable for, expected in, or salient to the local policy making process can be considered an aspect of the local discursive opportunity structure. That is, these conventions are cultural understandings of what is reasonable and legitimate in the context of local policy making .