Evaluating the ENVI-met microscale model for suitability in analysis of targeted urban heat mitigation strategies

Microscale atmospheric models are increasingly being used to project the thermal benefits of urban heat mitigation strategies (e.g., tree planting programs or use of high-albedo materials). However, prior to investment in specific mitigation efforts by local governments, it is desirable to test and validate the computational models used to evaluate strategies. While some prior studies have conducted limited evaluations of the ENVI-met microscale climate model for specific case studies, there has been relatively little systematic testing of the model's sensitivity to variations in model input and control parameters. This study builds on the limited foundation of past validation efforts by addressing two questions: (1) is ENVI-met grid independent; and (2) can the model adequately represent the air temperature perturbations associated with heat mitigation strategies? To test grid independence, a “flat” domain is tested with six vertical grid resolutions ranging from 0.75 to 2.0 m. To examine the second question, a control and two mitigation strategy simulations of idealized city blocks are tested. Results show a failure of grid independence in the “flat” domain simulations. Given that the mitigation strategies result in temperature changes that are an order of magnitude larger than the errors introduced by grid dependence for the flat domain, a lack of grid independence itself does not necessarily invalidate the use of ENVI-met for heat mitigation research. However, due to limitations in grid structure of the ENVI-met model, it was not possible to test grid dependence for more complicated simulations involving domains with buildings. Furthermore, it remains unclear whether existing efforts at model validation provide any assurance that the model adequately captures vertical mixing and exchange of heat from the ground to rooftop level. Thus, there remain concerns regarding the usefulness of the model for evaluating heat mitigation strategies, particularly when applied at roof level (e.g. high albedo or vegetated roofs)

A study of caesarean section at full cervical dilatation

Background: Caesarean sections performed in the second stage of labour are difficult and have many implications on both mother and baby. This study was conducted to analyse fetal and maternal outcome in case of caesarean section at full cervical dilatation.Methods: This prospective study was conducted at one of tertiary care teaching institute for period of 1st August 2019 to 31st January 2020. It includes all women delivered by caesarean section at full cervical dilatation at study institute during study period. Cases were looked for parity, maternal age, gestational age, baby birth weight, indication of cesarean section and associated factors.Results: Out of total 3657 deliveries 1690 were delivered by caesarean section, out of which 65 (3.8%) caesarean sections were conducted at full cervical dilation. The most common indication of caesarean section was deep transverse arrest in 66.15% of cases. The maximum number of cases (69.23%) were seen between the age group of 20 to 25 years. Majority of second stage cesarean section (70.77%) were performed in primi gravida. 80% of caesarean sections at full cervical dilatation were performed after 37 weeks of gestation. 15.38% of patients had anemia, 20% had hypertension, 4.61% had history of previous caesarean section. Baby weight at time of birth was 2.5 to 3.5 kg in 67.70% of cases. 15.38% of patients required blood transfusion.Conclusions: A skilled obstetrician is required to take timely and proper decision in such cases and also to conduct cesarean section at second stage of labour

Heat mitigation strategies in winter and summer: Field measurements in temperate climates

Natural elements such as vegetation and water bodies may help reduce heat in urban spaces in summer or in hot climates. This effect, however, has rarely been studied during cold seasons. This paper briefly studies the effect of vegetation and water in summer and more comprehensively in winter. Both studies are done in courtyards on two university campuses in temperate climates. A scale model experiment with similar materials supports the previous studies. The summer study is done in Portland (OR), USA, and the winter study (along with the scale model) in Delft, the Netherlands. The summer study shows that a green courtyard at most has a 4.7 °C lower air temperature in the afternoon in comparison with a bare one. The winter study indicates that the air temperature above a green roof is higher than above a white gravel roof. It also shows that, although a ‘black’ courtyard has higher air temperatures for a few hours on sunny winter days, a courtyard with a water pond and with high amounts of thermal mass on the ground has a warmer and more constant air temperature in general. Both the summer and winter studies show that parks in cities have a lower and more constant air temperature compared to suburbs, both in summer and winter. The scale model also demonstrates that although grass has a lower albedo than the used gravel, it can provide a cooler environment in comparison with gravels and black roof

Thermal assessment of heat mitigation strategies : the case of Portland State University, Oregon, USA

Courtyard vegetation, high albedo surfaces, and courtyard ponds were investigated as potential heat mitigation strategies using field measurements and simulations in a university campus environment. The investigation was performed during a summer period in the temperate climate of Portland, Oregon, USA. In a comparison of seven locations on the campus, the maximum park cooling island effect recorded was 5.8 °C between the heavily treed campus park and a nearby parking lot with asphalt pavement. Simulations of courtyards with vegetation and a water pond showed 1.6 °C and 1.1 °C air temperature reduction, respectively. Changing the albedo of the pavement in a bare courtyard from 0.37 (black) to 0.91 (white) led to 2.9 °C increase of mean radiant temperature and 1.3 °C decrease of air temperature

Heat in courtyards : a validated and calibrated parametric study of heat mitigation strategies for urban courtyards in the Netherlands

Outdoor thermal comfort in urban spaces is an important contributor to pedestrians’ health. A parametric study into different geometries and orientations of urban courtyard blocks in the Netherlands was therefore conducted for the hottest day in the Dutch reference year (19th June 2000 with the maximum 33 °C air temperature). The study also considered the most severe climate scenario for the Netherlands for the year 2050. Three urban heat mitigation strategies that moderate the microclimate of the courtyards were investigated: changing the albedo of the facades of the urban blocks, including water ponds and including urban vegetation. The results showed that a north–south canyon orientation provides the shortest and the east–west direction the longest duration of direct sun at the centre of the courtyards. Moreover, increasing the albedo of the facades actually increased the mean radiant temperature in a closed urban layout such as a courtyard. In contrast, using a water pool and urban vegetation cooled the microclimates; providing further evidence of their promise as strategies for cooling cities. The results are validated through a field measurement and calibration

The impact of heat mitigation strategies on the energy balance of a neighborhood in Los Angeles

Heat mitigation strategies can reduce excess heat in urban environments. These strategies, including solar reflective cool roofs and pavements, green vegetative roofs, and street vegetation, alter the surface energy balance to reduce absorption of sunlight at the surface and subsequent transfer to the urban atmosphere. The impacts of heat mitigation strategies on meteorology have been investigated in past work at the mesoscale and global scale. For the first time, we focus on the effect of heat mitigation strategies on the surface energy balance at the neighborhood scale. The neighborhood under investigation is El Monte, located in the eastern Los Angeles basin in Southern California. Using a computational fluid dynamics model to simulate micrometeorology at high spatial resolution, we compare the surface energy balance of the neighborhood assuming current land cover to that with neighborhood‐wide deployment of green roof, cool roof, additional trees, and cool pavement as the four heat mitigation strategies. Of the four strategies, adoption of cool pavements led to the largest reductions in net radiation (downward positive) due to the direct impact of increasing pavement albedo on ground level solar absorption. Comparing the effect of each heat mitigation strategy shows that adoption of additional trees and cool pavements led to the largest spatial‐maximum air temperature reductions at 14:00h (1.0 and 2.0 °C, respectively). We also investigate how varying the spatial coverage area of heat mitigation strategies affects the neighborhood‐scale impacts on meteorology. Air temperature reductions appear linearly related to the spatial extent of heat mitigation strategy adoption at the spatial scales and baseline meteorology investigated here

A prospective study of obstetric and gynaecological emergencies in a tertiary care hospital

Background: The management of obstetrics and gynaecological emergency is directed at the preservation of life, health, sexual function and the perpetuation of fertility. The main aim of the study was to access the burden of surgical emergency and to study the course of management at a tertiary care hospital.Methods: This prospective study was carried out in the department of obstetrics and gynaecology, S. S. G. Hospital, Baroda for a period from January to December 2018.Results: A total of 73 patients presented to our emergency room who required urgent surgical intervention. All patients were resuscitated and surgery was done at earliest possible time. The age of patient ranged from 18 to 45 years.  About 75.8% of female presented with the complaint of acute abdomen, followed by 32.9% with bleeding per vaginum. 16.4% had vomiting, 6.8% with fever and 4.1% with mass per abdomen. In majority of cases a diagnosis of ruptured ectopic pregnancy (34 patients) was made, followed by PPH in 14 patients and 12 cases of rupture uterus. Four cases of torsion of ovarian mass and 3 cases of septic peritonitis were operated. The most common surgery performed was salpingectomy followed by subtotal obstetric hysterectomy. A mortality rate of 8.2% was noted.Conclusions: This study emphasized the great role of timely surgical intervention as lifesaving procedures. Skilled clinicians and immediate intervention in a tertiary care is the main-stay of the emergency case management and are indispensable for decreasing mortality and morbidity

Micrometeorological simulations to predict the impacts of heat mitigation strategies on pedestrian thermal comfort in a Los Angeles neighborhood

The urban heat island impacts the thermal comfort of pedestrians in cities. In this paper, the effects of four heat mitigation strategies on micrometeorology and the thermal comfort of pedestrians were simulated for a neighborhood in eastern Los Angeles County. The strategies investigated include solar reflective 'cool roofs', vegetative 'green roofs', solar reflective 'cool pavements', and increased street-level trees. A series of micrometeorological simulations for an extreme heat day were carried out assuming widespread adoption of each mitigation strategy. Comparing each simulation to the control simulation assuming current land cover for the neighborhood showed that additional street-trees and cool pavements reduced 1.5 m air temperature, while cool and green roofs mostly provided cooling at heights above pedestrian level. However, cool pavements increased reflected sunlight from the ground to pedestrians at a set of unshaded receptor locations. This reflected radiation intensified the mean radiant temperature and consequently increased physiological equivalent temperature (PET) by 2.2°C during the day, reducing the thermal comfort of pedestrians. At another set of receptor locations that were on average 5 m from roadways and underneath preexisting tree cover, cool pavements caused significant reductions in surface air temperatures and small changes in mean radiant temperature during the day, leading to decreases in PET of 1.1°C, and consequent improvements in thermal comfort. For improving thermal comfort of pedestrians during the afternoon in unshaded locations, adding street trees was found to be the most effective strategy. However, afternoon thermal comfort improvements in already shaded locations adjacent to streets were most significant for cool pavements. Green and cool roofs showed the lowest impact on the thermal comfort of pedestrians since they modify the energy balance at roof level, above the height of pedestrians

Effects of urbanization on regional meteorology and air quality in Southern California

Urbanization has a profound influence on regional meteorology and air quality in megapolitan Southern California. The influence of urbanization on meteorology is driven by changes in land surface physical properties and land surface processes. These changes in meteorology in turn influence air quality by changing temperature-dependent chemical reactions and emissions, gas–particle phase partitioning, and ventilation of pollutants. In this study we characterize the influence of land surface changes via historical urbanization from before human settlement to the present day on meteorology and air quality in Southern California using the Weather Research and Forecasting Model coupled to chemistry and the single-layer urban canopy model (WRF–UCM–Chem). We assume identical anthropogenic emissions for the simulations carried out and thus focus on the effect of changes in land surface physical properties and land surface processes on air quality. Historical urbanization has led to daytime air temperature decreases of up to 1.4&thinsp;K and evening temperature increases of up to 1.7&thinsp;K. Ventilation of air in the LA basin has decreased up to 36.6&thinsp;% during daytime and increased up to 27.0&thinsp;% during nighttime. These changes in meteorology are mainly attributable to higher evaporative fluxes and thermal inertia of soil from irrigation and increased surface roughness and thermal inertia from buildings. Changes in ventilation drive changes in hourly NOx concentrations with increases of up to 2.7&thinsp;ppb during daytime and decreases of up to 4.7&thinsp;ppb at night. Hourly O3 concentrations decrease by up to 0.94&thinsp;ppb in the morning and increase by up to 5.6&thinsp;ppb at other times of day. Changes in O3 concentrations are driven by the competing effects of changes in ventilation and precursor NOx concentrations. PM2.5 concentrations show slight increases during the day and decreases of up to 2.5&thinsp;µg&thinsp;m−3 at night. Process drivers for changes in PM2.5 include modifications to atmospheric ventilation and temperature, which impact gas–particle phase partitioning for semi-volatile compounds and chemical reactions. Understanding process drivers related to how land surface changes effect regional meteorology and air quality is crucial for decision-making on urban planning in megapolitan Southern California to achieve regional climate adaptation and air quality improvements.</p

Porous Silicon Nanoparticles Embedded in Poly(lactic‐ co ‐glycolic acid) Nanofiber Scaffolds Deliver Neurotrophic Payloads to Enhance Neuronal Growth

Scaffolds made from biocompatible polymers provide physical cues to direct the extension of neurites and to encourage repair of damaged nerves. The inclusion of neurotrophic payloads in these scaffolds can substantially enhance regrowth and repair processes. However, many promising neurotrophic candidates are excluded from this approach due to incompatibilities with the polymer or with the polymer processing conditions. This work provides one solution to this problem by incorporating porous silicon nanoparticles (pSiNPs) that are pre-loaded with the therapeutic into a polymer scaffold during fabrication. The nanoparticle-drug-polymer hybrids are prepared in the form of oriented poly(lactic-co-glycolic acid) nanofiber scaffolds. We test three different therapeutic payloads: bpV(HOpic), a small molecule inhibitor of phosphatase and tensin homolog (PTEN); an RNA aptamer specific to tropomyosin-related kinase receptor type B (TrkB); and the protein nerve growth factor (NGF). Each therapeutic is loaded using a loading chemistry that is optimized to slow the rate of release of these water-soluble payloads. The drug-loaded pSiNP-nanofiber hybrids release approximately half of their TrkB aptamer, bpV(HOpic), or NGF payload in 2, 10, and >40 days, respectively. The nanofiber hybrids increase neurite extension relative to drug-free control nanofibers in a dorsal root ganglion explant assay