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Is Vertical Farming Eco Friendly

We also predicted that recent cocaine use would amplify the effects of historical use in HIV as assessed by traditional and ISDA memory metrics. Relative to other memory metrics, we posited that encoding would adversely be impacted given that both cocaine and HIV have been documented to impact frontostriatal networks . Data from 113 community-dwelling HIV infected participants were used for the current analysis. This sample was extracted from a prior study , which was funded by the National Institute on Drug Abuse . The initial study was adequately powered to detect the effects of . No control group was available in the sample . Participants were recruited from community health agencies in the Los Angeles area through fliers posted in infectious disease clinics at two University-affiliated medical centers. Exclusion criteria included meeting diagnostic criteria for lifetime or current history of psychotic spectrum or manic disorders and any neurological disorder other than HIV-infection . For our analyses, the participants were stratified by 1) recent cocaine use and 2) if participants ever met diagnostic criteria for cocaine dependence or abuse in their lifetime. The stratification for the recent cocaine abuse, participants 1) reported using cocaine within 4 weeks of testing and/or had positive urinalysis results for cocaine use on the day of testing or 2) denied cocaine use 4 weeks prior to testing and had negative cocaine urinalysis results . A period of four weeks was selected for self-report to ensure that there was sufficient time for such substances to adequately clear their system. Urine toxicology conducted on the day of testing, which screened for cocaine, amphetamine, cannabis,indoor growing racks and opiate metabolites. The stratification for presence or absence of lifetime cocaine dependence or abuse was determined by the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorder 4th Edition, Clinical Version . HIV status was confirmed with ELISA and Western blot. Seventy percent of the HIV/ Coc+ , 63 percent of the HIV/Coc− , 65 percent of HIV/CocDx+ , and 72 percent of HIV/CocDx− participants met the Centers for Disease Control and Prevention diagnostic criteria for Acquired Immunodeficiency Syndrome .

There were no group differences in the proportion of participants meeting criteria for AIDS . All of the participants were on self-administered HAART at the time of testing. The CVLT-II is a verbal list-learning test comprised of 16 items that can be grouped into four semantic categories. The list is presented orally to participants over five learning trials, followed by a short-delay free and cued recall, long-delay free and cued recall, and recognition trials. The CVLT-II yields numerous indices. For the current study, we were interested primarily in the sum of items recalled across all five learning trials , short-delay free recall, and long-delay free recall. Item level data from the CVLT-II were evaluated via the Item Specific Deficit Approach , a quantitative process method for deriving indices of encoding, consolidation, and retrieval deficits. These indices have demonstrated increased sensitivity to cognitive impairment compared to traditional indices calculated from list-learning data . Furthermore, these indices seem to be less contaminated by other cognitive factors . The ISDA encoding deficit index is derived by summing the items that were not recalled at least three times during the five initial CVLT-II learning trials . The consolidation deficit index is calculated by summing the items that were recalled at least once during the list learning, but not recalled during either the short or long delay free or cued recall trials. The retrieval index is calculated via the sum of items that were recalled during list learning but recalled inconsistently across the short and long-delay free and cued recall trials . The consolidation index and retrieval index totals are divided by the number of items recalled at least once during the list learning trials to control for learning differences between groups.While the HIV/Coc+ and HIV/Coc− groups were well matched in terms of premorbid intelligence, age, education, sex, and history of depression , the HIV/Coc− group was comprised of a larger proportion of Caucasian participants than the HIV/Coc+ group. That said, ethnic/racial membership was not significantly associated with any of the dependent variables in the current study . Additionally, the HIV/Coc− had greater duration of lifetime cocaine and stimulant use, than the HIV/Coc+ group, while the HIV/Coc+ had a greater number of participants with positive cannabis toxicology. Total duration of cocaine and stimulant use was not associated with any of the dependent variables in the study . Similarly, positive cannabis toxicology was exclusive to HIV/Coc+ in our sample and was not associated with any of the dependent variables in the study .

While HIV/CocDx+ and HIV/CocDx− were well matched in terms of premorbid intelligence, age, education, sex, ethnicity, and history of depression , the HIV/CocDx− group had greater incidence of lifetime alcohol abuse and/or dependence and cannabis abuse and/or dependence than the HIV/CocDx+ group. That said, lifetime alcohol abuse and/or dependence and cannabis abuse and/or dependence were not significantly associated with any of the dependent variables in the current study . In order to determine the impact of cocaine use on CVLT-II performances, we performed 2 group X 2 cocaine use history ANOVAs for the CVLT-II total learning sum, CVLT-II short-delay free recall, CVLT-II long-delay free recall, and ISDA indices . A significance level of α <0.05 was used as the threshold for significance. To correct for family-wise error, we calculated q-values with a predetermined false discovery rate cut-off of .05 for each p value across all memory metrics .We hypothesized that 1) recent cocaine use will exacerbate encoding deficits and verbal memory difficulties in HIV infected individuals and 2) meeting lifetime diagnostic criteria for cocaine dependence and/or abuse would adversely impact memory performances, 3) recent cocaine use would amplify the effects of historical use in HIV, and 4) encoding would be adversely impacted over consolidation and retrieval. Our data partially supported these hypotheses. Specifically, using traditional verbal memory metrics that do not control for , recent cocaine use impacted total learning, short and long delay, and recognition discriminability, and interactive effects between recent use and historical use emerged only for the recognition discriminability metric. Specifically, the interactive effects revealed recognition discriminability performance differences in recent cocaine users with and without a lifetime history of cocaine abuse or dependence; the interaction further suggested that with abstinence, recognition discriminability performances of those with and without cocaine abuse and dependence are similar. Overall, the traditional memory metrics revealed general and non-specific findings that recent cocaine abuse and not historical use impacts all memory domains. However, given that traditional metrics do not account for inattention and dysexecutive symptoms , an alternative approach was employed as both cocaine and HIV influence frontostriatal networks subservient to these functions . Indeed, using the ISDA, our findings revealed that only encoding was compromised in the HIV/Coc+ group when compared to the HIV/Coc− group.

Additionally, using the ISDA, we found that historical cocaine use and/or dependence did not have an impact on encoding, consolidation, or retrieval. In contrasting traditional memory metrics and the ISDA, the ISDA memory metrics isolated statistically inferior performances to encoding, while the traditional metrics provided non-specific findings,micro green growing racks despite being statistically collinear to traditional memory metrics . Similar collinearity among memory metrics has been reported by other researchers . These findings speak to the incremental utility of the ISDA in an HIV setting and suggests that reduced memory performances in the context of HIV and cocaine use are likely secondary to disrupted learning, which is concordant with prior research suggesting frontostriatal involvement and reduced executive ability that likely impacts strategic encoding strategies . Of note, our findings are also in line with prior research supporting the notion that the deleterious effects of cocaine use on cognition in HIV are, at least to some extent, state-like in nature and transitory . Moreover, a recent longitudinal study found that in some cases, 1-year abstinence led to cognitive performances similar to that of healthy control participants . Our findings further add to the literature against the lasting impact of cocaine use ; however, given the cross-sectional nature of the study and a lack of healthy comparison subjects, we cannot affirm that reduced encoding will be fully ameliorated, although this study converges with other research that suggests performance comparable to HIV/Coc− groups. At first blush, our findings appear to differ from another study reporting no differences in verbal memory between HIV participants with and without cocaine use . However, in the Durvasula et al. study, HIV/Coc+ participants were younger and there is evidence to suggest that older individuals with HIV, even a remote history of stimulant use seems to have an effect as persons age . Additionally, the authors note that their findings may have been confounded by alcohol use and largely recreational drug users . The results of the current study underscore the importance of interventions that aid in the cessation of cocaine use among individuals with HIV. The immediate concern is that cocaine use could lead to worse cognitive status that could reduce HAART adherence. Indeed, declines in cognitive functioning , including memory , are associated with decreased medical compliance; this phenomenon also appears to be the case for cocaine use . This is a particularly vexing problem since cocaine-related verbal memory deficits may not only lead to worse functional outcomes, but active cocaine use may accelerate HIV replication , further highlighting the importance of targeted substance use/abuse interventions for persons with HIV. Our results have implications for clinical practice. Of notable importance, is the HIV/Coc+ memory profile of acquisition adjusted versus non-adjusted measurement of memory. Our findings highlight the importance of clinically correcting for inattention and a decline in executive ability , especially in the context of HIV and cocaine given the neurocircuitry involved . Relying solely on traditional metrics can be misleading, as seen in this study. Specifically, memory performances should adjust for acquisition, if memory is being evaluated . Additionally, HIV-related memory deficits are associated with decreases in medical compliance and daily functioning , so additional memory deficits caused by cocaine use could potentially exacerbate functional impairment in areas such as medication management, driving, employment, money management, cooking, and shopping . Additionally, our data suggest recommendations that specifically target the HIV-associated memory deficits, such as methods that improve the acquisition of new information rather than retrieval practice . Finally, our findings also offer hope and incentive to patients, suggesting that abstinence from cocaine may confer cognitive benefit. While our study suggests that recent, not past, cocaine use exacerbates verbal memory difficulties in HIV/AIDS via greater encoding deficits, our study also suffered from some limitations. The study did not include a healthy control group or a HIV-negative group with a history of cocaine use. Such comparisons would have allowed for a more detailed analysis and stronger conclusions about the independent, additive, and interactive effects of HIV serostatus and cocaine use. As such, this study can only speak to the effects of recent COC use in the setting of HIV and without a normative sample, differences observed between groups may not represent clinically relevant discrepancies . Nevertheless, discrepancies between healthy comparisons and participants with HIV are well documented . Our study evaluated the impact of cocaine use in HIV only on verbal memory and is a notable limitation, as other research has demonstrated discrepancies in attention, working memory, psychomotor speed, and executive functions . The present study utilized a cross-sectional design. A longitudinal and within-subjects design, in which participants’ performances are assessed while accounting for natural variation in the level of cocaine use over time, would have allowed us to better ascertain the impact of cocaine use on verbal memory in persons with HIV. Additionally, Finally, our methodology for determining history of cocaine use entailed self-report and urinalysis screen; while urinalysis is very accurate in this regard, it is only effective for a limited temporal window and, thus, we had to rely on self-reports regarding cocaine use that occurred several weeks prior to urine collection. That said, future research should also consider whether there are thresholds in terms of duration and severity of cocaine use that are related to long term declines in verbal memory in individuals with HIV. The incidence of HIV infection remains high among minority men who have sex with men.

Symmetry boundaries are set at the middle of the length and width of the room

Furthermore, employment of light emitting diodes as light sources can initiate and sustain photosynthesis reactions and the optical wavelength, light intensity, and radiation intervals can further enhance growth quality. Recently, many studies have been carried out to investigate how environmental parameters, such as closed-loop control, ultrasound, and electro-degradation, affect hydroponic cultivation of leafy vegetables in these systems. One of the most influential factors affecting growth in IVFS is to maintain a uniform air flow at an optimal air current speed over plants canopy surfaces. Poor flow uniformity or variation in air velocity over culture beds destabilizes crop production rates. It has been found that inducing a horizontal air speed of 0.3–0.5 m s−1 boosts photosynthesis through more efficiently exchanging species between the stomatal cavities in plants and the flow of air. Lee et al. studied the effects of air temperature and flow rate on the occurrence of lettuce leaf tip burn in a closed plant factory system. Furthermore, it was observed that the relative humidity of the air flow can significantly influence calcium transportation in lisian thus cultivars . According to Vanhassel et al., higher levels of relative humidity can significantly decrease the occurrence of tip burn. Therefore, it is vital to maintain relative humidity in the desired range to ensure even distribution of calcium in lettuce leaves. Over the past few years, researchers have been trying to develop techniques for improving uniformity over cultivation zones. Regardless of the recent progress, the control and automation systems of IVFS bring additional costs,seedling grow rack which makes systematic experimental investigation and optimization a challenge. Computational fluid dynamics has been utilized as a reliable tool to numerically simulate complex physical phenomena. Markatos et al. developed a CFD procedure to study velocity and temperature distribution in enclosures using buoyancy-induced physics. 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 micro-porous micro-channel 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, 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.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.In our model, a tetrahedral grid type is used to discretize the entire computational domain. To ensure that the numerical results are independent of grid dimensions, five grid numbers ranging from 196,951 to 1,164,624 are used to study the baseline Case AB at a mass flow rate of 1 kg s−1. Fig. 2 summarizes the average temperature and pressure difference for the five grid numbers. Balancing between the accuracy of the simulation results and computational cost, the grid number of 697,537 is employed throughout the rest of the study.

The simulation domain consists of rectangular prisms as cultivation tray, the exchange zone in which the photosynthesis processes occur, and the rest of the open volume. To validate our numerical code, we performed simulation of conjugated heat transfer and turbulent flow passing over one rectangular prism in a duct. The exact dimensions and input conditions of this test case can be found in the study of Nakagawa et al.. The induced flow involves periodic vortex shedding that can be problematic for numerical analysis. The results of the numerical simulations are compared with the experimental measurements done by Lyn et al., Franke and Rodi , and Durao et al. [46]. Fig. 3 shows the average axial velocity distribution and our simulation results agree well with the experimental data both before and after the rectangular prisms. To further validate the reliability of heat transfer calculation, the simulated local Nusselt number along the upper wall of the square prism are compared with the experimental data measured by Nakagawa et al. in Fig. 4. When x/H is between 1and 2, the wake flow is extremely unsteady and adverse flow can be observed in Fig. 3. Therefore, it is extremely difficult to accurately predict the convective heat transfer in this region. Nevertheless,indoor growing racks the simulation results show good agreement with the experimental data, especially in the wake region . Further, the calculation of species transport in this work is simulated using species exchange sub-model, which has been validated extensively in the literature.In this study, three dimensional simulations of conjugated turbulent flow and heat transfer are carried out to study the concept of the IVFS. The exchange zone above each tray is designed to represent the volume where the photosynthesis reaction takes place including carbon dioxide consumption along with water transpiration and oxygen production. In addition, the room is assumed to be insulated by wooden walls with known thickness and thermal properties for modeling heat exchange with the outdoor ambient air. In this study, we analyze the effect of eight distinctive inlet outlet placements on flow uniformity over the lettuce canopy, temperature and relative humidity distribution in the room, and the power required for air circulation.One of the most critical factors affecting crop growth rate is the air flow velocity over plants. 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.