Reduce Heat Stress Research Articles

Simulating the cooling effects of water spray systems in urban landscapes: A computational fluid dynamics study in Rotterdam, The Netherlands

Heat waves and the related heat stress can increase human morbidity and mortality, decrease human productivity and increase building energy consumption for cooling. There is a need for sustainable systems to reduce heat stress in urban areas. Evaporative cooling by water spray systems is increasingly used for this purpose. However, the evaluation of the cooling potential of such systems is difficult. To our knowledge, a systematic investigation of the cooling potential of such a system in an actual urban area has not yet been performed. This paper presents high-resolution Computational Fluid Dynamics (CFD) simulations based on the 3D unsteady Reynolds-Averaged Navier-Stokes equations to assess the cooling potential by a water spray system with 15 hollow-cone nozzles. The system is numerically implemented for a courtyard in the Bergpolder Zuid region of Rotterdam, the Netherlands and operated during the heat wave period of July 2006. The simulations are validated based on wind-tunnel measurements of an evaporative cooling process and satellite imagery data during the heat wave period. The Universal Thermal Climate Index (UTCI) is used to assess the heat stress reduction due to evaporative cooling. The results show that for given values of injected water flow rate (ṁw=9.0l/min) and height of the spray system (H=3m), a maximum temperature reduction and UTCI reduction of about 7 and 5°C are achieved at pedestrian height. In addition, a thermal comfort improvement from strong heat stress (without spray system) to moderate heat stress up to a distance of 5m from the spray line is obtained.

Erratum to: Down-regulation of miR-181a can reduce heat stress damage in PBMCs of Holstein cows.

Erratum to: Down-regulation of miR-181a can reduce heat stress damage in PBMCs of Holstein cows.

Prokaryotic expression of chicken interferon-γ fusion protein and its effect on expression of poultry heat shock protein 70 under heat stress.

Interferons have attracted considerable attention due to their vital roles in the host immune response and low induction of antibiotic resistance. In this study, total RNA was extracted from spleen cells of chicken embryos inoculated with Newcastle disease vaccine, and the full-length chicken interferon-γ (ChIFN-γ) gene was amplified by RT-PCR. The full complementary DNA sequence of the ChIFN-γ gene was 495bp long and was cloned into the prokaryotic expression vector pProEX™HTb . The plasmid was transformed into Escherichia coli DH5α and the expression of ChIFN-γ was induced by isopropyl β-D-1-thiogalactopyranoside. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis and Western blot results showed the expressed fusion protein had a molecular weight of approximately 18kDa and was recognized by an anti-His mAb. Moreover, ChIFN-γ was found to demonstrate anti-viral activity in vitro. To test the in vivo function of ChIFN-γ in broilers under heat stress, a total of 100 broilers were randomly assigned to either a control group or a treated group, in which they were hypodermically injected with recombinant ChIFN-γ. Results demonstrated ChIFN-γ affects the messenger RNA expression levels of heat shock protein 70 (HSP70) in the heart and lung tissues, and decreases the concentration of HSP70 in serum. Therefore, we conclude recombinant ChIFN-γ can reduce heat stress to some extent in vivo.

0080 Reducing heat stress in calf hutches using reflective covers: Optical properties and implications

0080 Reducing heat stress in calf hutches using reflective covers: Optical properties and implications

Enfriamiento al inicio de verano para mitigar el estrés por calor en vacas Holstein del noroeste de México

El objetivo de este estudio fue determinar la respuesta fisiológica, endócrina y productiva en vacas lactantes sometidas a varias series de enfriamiento artificial al inicio de verano (junio a julio de 2011). Se asignaron 14 vacas Holstein multíparas a uno de dos tratamientos: enfriamiento (E) antes de la ordeña (0700 y 1700 h) y enfriamiento adicional (EA) cada 2 h de 0700 a 1700 h en el corral de espera a la ordeña. Se midió la producción de leche (PL), niveles de prolactina (PRL) e IGF1, mientras que la temperatura rectal y frecuencia respiratoria fueron registradas y consideradas como indicadores fisiológicos de estrés por calor. La temperatura ambiental y humedad relativa también fueron registradas y utilizadas para calcular el índice de temperatura-humedad (ITH). Los indicadores de estrés calórico mostraron una interacción significativa (P<0.001) entre tratamiento y tiempo/semana, los cuales fueron menores con EA (-3.8 respiraciones por minuto y -0.2 °C) sólo durante las semanas 6 y 7. Los niveles séricos de PRL fueron mayores bajo enfriamiento adicional (EA: 35.1 vs E: 29.4 ng/ml; P=0.004), mientras que los de IGF1 solo variaron a través de las semanas de muestreo (P=0.014). La PL se incrementó (P<0.05) en EA durante las semanas 6 (+3.1kg/día) y 7 (+3.1 kg/día). Se concluye que la mayor frecuencia de baños mitigó la condición de estrés calórico al inicio de verano, permitiéndole a la vaca expresar un mejor desempeño productivo al final del estudio, ya que dicho efecto dependió de la variable tiempo/semana.

Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling.

Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory.

Influence of shading and sprinkling water on milk production and physiological responses of dairy cows

Countless studies attest to the negative effects of high temperatures on milk production. So, many environmental modifications can be introduced in order to decrease the temperature of the animals and, consequently, reduce heat stress, helping so, in the comfort of dairy cows confined. The aim of this review was to approach the effects of shading and sprinkling water on milk production and physiological responses in dairy cows. Several methods have been employed, such as natural or artificial shading, ventilation, cooling air from the application of water droplets, water spray on the animal accompanied by ventilation and air conditioning. In intensive production systems, coupled with the shading, the use of evaporative cooling systems in proportion to the animals an environment with warmer temperatures, avoiding situations of heat stress and increasing milk production. In pastures, the providing shade, either natural or artificial, it is necessary for dairy cows in order to reduce the excess heat received by direct solar radiation, especially during the hottest hours of the day and in regions near the line of Ecuador.

Urban heat islands in China enhanced by haze pollution.

The urban heat island (UHI), the phenomenon of higher temperatures in urban land than the surrounding rural land, is commonly attributed to changes in biophysical properties of the land surface associated with urbanization. Here we provide evidence for a long-held hypothesis that the biogeochemical effect of urban aerosol or haze pollution is also a contributor to the UHI. Our results are based on satellite observations and urban climate model calculations. We find that a significant factor controlling the nighttime surface UHI across China is the urban–rural difference in the haze pollution level. The average haze contribution to the nighttime surface UHI is 0.7±0.3 K (mean±1 s.e.) for semi-arid cities, which is stronger than that in the humid climate due to a stronger longwave radiative forcing of coarser aerosols. Mitigation of haze pollution therefore provides a co-benefit of reducing heat stress on urban residents.

Comparative efficacy of passive and mechanical fan-pad cooling system for microclimate modification and welfare in broiler production

Efficacy of passive cooling vis-à-vis mechanical fan-pad cooling system was assessed for microclimate modification to alleviate heat stress and improving growth performance and welfare of broilers. Cooling treatments comprised of Tc (control without any cooling system), TJSC passive cooling (jute sheet roof shading and curtains with gravity flow sprinklers), TGSC passive cooling (green sheet roof shadings and curtains with gravity flow sprinklers) and TFP (fan pad mechanical cooling systems). The results of shed microclimate indicated that maximum ambient temperature, temperature humidity index (THI) and duration and level of heat stress in control were significantly higher than passive (TJSC and TGSC) and mechanical (TFP) cooling group. Growth performance and feed efficiency, in both passive (TJSC and TGSC) and mechanical cooling (TFP) were significantly better than control. However, growth performance and feed efficiency of chicks was significantly higher in TFP than chicks in passive (TJSC and TGSC) cooling groups. In passive cooling systems (TJSC and TGSC), the plasma catalase, glutathione peroxidase (GPx) and BUN were significantly lower than control (Tc) but significantly higher than mechanical cooling (TFP) system. The stress related behavioural activities, panting, preening, scratching and wing flapping were significantly higher in control as than in cooling system. It was concluded that passive cooling system can be an environment friendly and energy independent alternate to intensive mechanical cooling system to reduce heat stress and improve growth and welfare in broiler production.

Dynamic stability of cemented carbide circular saw blades for woodcutting

With increasing requests and applications for carbide circular saw blades in the wood industry for furniture manufacturing, dynamic stability becomes a critical problem that has a strong effect on cutting quality, noise, vibration, material waste and the lifetime of a saw blade. The dynamic stability of a circular saw blade is associated with its natural frequency and stress distribution, and roll tensioning is considered to be the most effective method to improve this dynamic stability. In this study, several roll tensioning methods have been investigated, and the results indicate that continuous roll tensioning along a fixed tracking groove on the surfaces of circular saw blade produces better dynamic stability compared with alternative roll tensioning along different tracking grooves. The effects of various roll-tensioning parameters, such as rolling force, rolling radius and rolling number, on the natural frequency and stress distribution of circular saw blades have also been investigated, thus, optimum parameters can be achieved. Results show that the influence of the rolling force is the strongest, while the effect of the rolling number is negligible. Radial slots can effectively increase the natural frequencies of a circular saw blade and reduce heat stress, particularly tangential heat stress, which is induced by cutting processes. The slot number and length also have strong effects on the natural frequencies. Additionally, the effects of geometric parameters, such as the thickness of the saw blade and the clamp diameter, on the natural frequencies are also examined using finite element analysis. The simulated results are validated by experimental tests, which exhibit good agreement with the experimental results.

English

English

Shade Effect on Growth and Productivity of Tomato and Chili Pepper

Southern U.S. states such as Texas experience high temperatures and intense solar radiation during the summer production season. Use of shadecloth is common in Spain and other Mediterranean countries and is becoming popular with homeowners or small-acreage farmers in Texas. Little information is available on the applicability of using shadecloth on tomato (Solanum lycopersicum) and chili pepper (Capsicum annuum) in the warm climate of Texas. The effects of two shade nets differing in shading intensity on growth, chlorophyll fluorescence, and photosynthesis of ‘Celebrity’ tomato and ‘Sweet Banana’ chili pepper was investigated from May to Aug. 2014. Plants were grown in 50% shade, 70% shade, or full sun. Compared with the unshaded control, tomato grown in 50% shade had similar yield and shoot fresh and dry weight and less photochemical stress. The 50% shade reduced number and weight of unmarketable tomato fruit. Similar results were obtained with chili pepper except for lower numbers of marketable fruit. The 70% shade significantly reduced yield parameters of both tomato and chili pepper. Both 50% and 70% shadecloth reduced leaf temperatures of tomato and chili pepper with variable results in June and July. Growth index [(height + width 1 + width 2) ÷ 3] of tomato and chili pepper was the highest with 50% shade, the lowest with full sun, and intermediate with 70% shade. The maximum net photosynthetic rates (Pn) of tomato determined from a Pn to light response curve supported the results on growth and yield. However, the maximum Pn of chili pepper was higher in full sun treatment compared with 50% or 70% shade. The latter two were almost identical. This one growing season study indicated that shading at 50% benefits tomato and chili pepper production in west Texas by reducing heat stress; however, a shading percentage below 50% may be better.

Development of Dryland Oilseed Production Systems in Northwestern Region of the USA

This report addresses the development of dryland oilseed crops to provide feedstock for production of biofuels in semi-arid portions of the northwestern USA. Bioenergy feedstocks derived from Brassica oilseed crops have been considered for production of hydrotreated renewable jet fuel, but crop growth and yields in the northwestern region are limited by a lack of plant available water. Based on a review of the scientific literature, several areas were identified where research could be directed to provide improvements. The current agronomic limitations for oilseed production are mainly due to seedling establishment under extreme heat, dry seedbeds at optimum planting times, survival under extreme cold, and interspecific competition with weeds. To improve emergence and stand establishment, future work should focus on developing soil management and seeding techniques that optimize plant available water, reduce heat stress, and provide a competitive advantage against weeds that are customized for specific crops, soil types, and soil and environmental conditions. Spring and winter cultivars are needed that offer increased seedling vigor, drought resistance, and cold tolerance.

Down-regulation of miR-181a can reduce heat stress damage in PBMCs of Holstein cows.

Heat stress can weaken the immune system and even increase livestock's susceptibility to disease. MicroRNA (miR) is short non-coding RNA that functions in post-transcriptional regulation of gene expression and some phenotypes. Our recent study found that miR-181a is highly expressed in the serum of heat-stressed Holstein cows, but the potential function of miR-181a is still not clarified. In this study, peripheral blood mononuclear cells (PBMCs), isolated from Holstein cows' peripheral blood, were used to investigate the effects of miR-181a inhibitor on heat stress damage. Our results showed that significant apoptosis and oxidative damage were induced by heat stress in PBMCs. However, with apoptosis, the levels of reactive oxygen species (ROS) and content of malondialdehyde (MDA) were reduced, while the content of glutathione (GSH) and the activity of superoxide dismutase (SOD) were increased even under heat stress conditions after transfecting miR-181a inhibitors to PBMCs. Meanwhile, mRNA expression of bax and caspase-3 was significantly decreased, but mRNA expression of bcl-2 was increased in transfected PBMCs. In conclusion, our results demonstrated that down-regulation of miR-181a can reduce heat stress damage in PBMCs of Holstein cows.

Thermal performance of buildings integrated with phase change materials to reduce heat stress risks during extreme heatwave events

Building refurbishment, through incorporating phase change materials (PCMs) into building fabrics, has been considered to be an effective way to reduce the energy consumption and related carbon emission of buildings. At the same time, it can also help to reduce the extreme heatwave risks in non-air-conditioned buildings. This study investigates the potential applications of PCMs to be integrated into buildings to reduce heat stress risks during extreme heatwave periods through numerical simulations. This study uses 2009 weather data of Melbourne, a city that regularly experiences heatwaves in summer. A detached single-storey house, without an active air-conditioning system, is refurbished with the installation of macro-encapsulated Bio-PCM™ mats as inner linings of walls and ceilings. Dynamic thermal simulations have been undertaken to reveal the performance of, and factors that influence, the adoption of PCM to reduce heat stress during heatwave periods. Discomfort index has been used as an indicator for measuring the indoor heat stress risks. The results showed that PCM refurbishment can effectively reduce the indoor heat stress risks, indicating a significant advantage in improving the occupant health and comfort. The selection of suitable phase transition temperature, and amount of PCM, is critical for this application to be effective. Appropriate selection of PCM with better ventilation design could reduce the severe discomfort period by 65% during extreme heatwave conditions. While the thermal energy storage of PCM reduces the indoor heat stress, night ventilation enhances the cool storage of PCM.

Intervention to reduce heat stress and improve efficiency among sugarcane workers in El Salvador: Phase 1

BackgroundChronic heat stress and dehydration from strenuous work in hot environments is considered an essential component of the epidemic of chronic kidney disease in Central America.Objective(1) To assess feasibility of...

Heat stress amelioration measures in lactating Nili-Ravi buffaloes: Effect on body weight changes, dry matter intake, milk production and economics

The aim of the present study was to find out the effect of heat stress amelioration on body weight changes, dry matter intake, milk yield and economics in lactating Nili-Ravi buffaloes during hot-dry (HD; April to Mid June) and hot-humid (HH; Mid June to August) seasons under tropical climate. Forty two Nili-Ravi lactating buffaloes were uniformly divided into two groups of twenty one in each considering their lactation number, stage of lactation, body weight, dam’s milk yield and milk yield in current lactation. The control (T0) group buffaloes were kept in separate shed without any nutrient supplementation and modification in microclimate and management. The treatment (T1) group was supplemented with niacin, yeast, edible oil in feed and provided curtains and mist fans in the shed, and altered feeding time, frequency and type of ration. The overall mean body weights in control and treatment group buffaloes were noted to be 517.4 kg and 523.4 kg, respectively. Under HD and HH seasons, mean body weights at different fortnights in treatment group buffaloes were 515.6 kg and 531.1 kg, respectively. In control group, the respective values were 512 kg and 522.7 kg. Although the body weights were higher in treatment than control group, there were no statistically significant differences between two experimental groups. The overall mean daily total dry matter intake (TDMI), dry matter intake through concentrate (CDMI), dry matter intake through dry fodder (DFDMI) and dry matter intake through green fodder (GFDMI) were noted to be 13.04, 4.21, 1.02, 7.92, 14.13, 4.24, 1.17 and 8.65 kg in control and treatment group buffaloes, respectively. Under both seasons, treatment group buffaloes consumed more dry matter than control group throughout the experimental period. The values were also differed significantly (ranged from P<0.05 to P<0.0001) between two groups. The overall mean values of fortnightly total milk production were 103.2 kg in control group and 121.5 kg in treatment group. Throughout the period, treatment group buffaloes produced more milk than control. Milk production was also significantly (P<0.0001) differed between control and treatment groups under two seasons. The daily average additional input cost per buffalo was maximum 22/- and additional income per buffalo was minimum 35/-. Therefore, the net profit was around 13/- per buffalo per day. The input: output ratio was calculated to be 1:1.59. It can be concluded that the use of such types of housing, nutritional and management interventions in the form of one package not only helps to maintain body weight but also increases dry matter intake and favours economic milk production in lactating buffaloes through reducing heat stress during hot-dry and hot-humid seasons in tropical climate.

Cool Bands: Wing bands decrease rate of heating, but not equilibrium temperature in Anartia fatima

Butterflies regulate their internal thoracic temperature in order to optimize performance activities (e.g. flight, foraging). Previous research has shown that butterfly wings, particularly the innermost portions, play a role in thermoregulation. We investigated to see whether a lightly colored wing band would alter the thermal properties of the banded peacock butterfly (Anartia fatima) with two within subject experiments in a laboratory setting: (1) band color manipulation in which euthanized individuals were heated to thermal equilibrium with the band unaltered and then again with the wing darkened; (2) wing ablation in which individuals already run through experiment 1 were heated to equilibrium two more times; once with the outer portion of the wing including the band removed and then with the entire wing removed. Individuals were spread so that the dorsal surface of the wing was exposed to illumination from a lamp suspended above. Twelve Anartia fatima males were collected in Panama and were run through experiment one. Four individuals were run through experiment two. We found no effect of darkening the band on the internal thoracic equilibrium temperature, but the darkened band did increase the rate of heating. The wing ablation experiment revealed that wing removal lowered the internal thoracic equilibrium temperature but did not affect the heating rate. Therefore we show that butterfly bands may be important in butterfly thermoregulation and we discuss the importance of the wing band on thermoregulatory abilities in Anartia fatima with respect to the butterfly's natural history. We conclude that the wing band may allow butterflies to reduce heat stress induced by their warm environments.

Effect of in vitro zinc supplementation on HSPs expression and Interleukin 10 production in heat treated peripheral blood mononuclear cells of transition Sahiwal and Karan Fries cows

The changing climatic scenario with apprehended rise in global temperature is likely to affect the livestock adversely vis-à-vis production and reproduction. This has prompted more focus in addressing the unfavorable effects of thermal stress in livestock system. Presuming that the trace element zinc is indispensible for cellular antioxidant system and immune function, the present study was designed to investigate the effect of zinc treatment on heat stress alleviation and immune modulation in peripheral blood mononuclear cells (PBMC) of indigenous and crossbred transition cows. Twelve cows, six each of Sahiwal and Karan Fries (KF) in their second parity with confirmed pregnancy were selected for the experiment. The blood samples were collected at −21, 0 and +21 days in relation to expected date of calving. The experiment was carried out in vitro after isolating PBMC from whole blood. The 48h cultured PBMC were subjected to assorted levels of exposures viz. 37°C, 42°C to impose heat stress and 42°C+zinc to alleviate heat stress and modulate immunity. The PBMC viability was 86%, 69% and 78%, respectively. The mRNA expression of heat shock proteins (HSP 40, 70 and 90α) and Interleukin-10 (IL-10) production varied between the two breeds vis-à-vis days and levels of exposure. The mRNA expression of HSP40 and HSP70 was significantly (P<0.05) higher in Karan Fries than the Sahiwal cows. Both the breeds showed maximum expression of HSP on the day of parturition, more so in KF than Sahiwal. There was a significant (P<0.05) difference in the HSP mRNA expression at different levels of exposure. Zinc treatment to heat stressed PBMC caused a significant (P<0.05) down regulation of HSP. For immune status, anti-inflammatory cytokine, IL-10 in the culture supernatant was accessed. The IL-10 was significantly (P<0.05) higher in Karan Fries (168.18±14.09pg/ml) than the Sahiwal cows (147.24±11.82pg/ml). The IL-10 concentration was highest on the day of calving. Zinc treatment reduced the IL-10 concentration. From the study, it could be concluded that the zinc supplementation in heat stressed PBMC can ameliorate thermal stress and modulate immune response which can act as a model for reducing heat stress during the periparturient period in tropical livestock.

Heat and Humidity in the City: Neighborhood Heat Index Variability in a Mid-Sized City in the Southeastern United States.

Daily weather conditions for an entire city are usually represented by a single weather station, often located at a nearby airport. This resolution of atmospheric data fails to recognize the microscale climatic variability associated with land use decisions across and within urban neighborhoods. This study uses heat index, a measure of the combined effects of temperature and humidity, to assess the variability of heat exposure from ten weather stations across four urban neighborhoods and two control locations (downtown and in a nearby nature center) in Knoxville, Tennessee, USA. Results suggest that trees may negate a portion of excess urban heat, but are also associated with greater humidity. As a result, the heat index of locations with more trees is significantly higher than downtown and areas with fewer trees. Trees may also reduce heat stress by shading individuals from incoming radiation, though this is not considered in this study. Greater amounts of impervious surfaces correspond with reduced evapotranspiration and greater runoff, in terms of overall mass balance, leading to a higher temperature, but lower relative humidity. Heat index and relative humidity were found to significantly vary between locations with different tree cover and neighborhood characteristics for the full study time period as well as for the top 10% of heat index days. This work demonstrates the need for high-resolution climate data and the use of additional measures beyond temperature to understand urban neighborhood exposure to extreme heat, and expresses the importance of considering vulnerability differences among residents when analyzing neighborhood-scale impacts.