Peripheral sweat gland function,but not whole-body sweat rate,increases in women following humid heat acclimation

The purpose of this study was to compare both the whole-body and pharmacological-induced sweat rates of men and women following humid heat acclimation.     

Characteristics of wettedness under constant average skin temperature

1. 1. Experiments were carried out concerning the characteristics of wettedness revealed under constant average skin temperature using sitting-resting nude subjects. From the basic measurements of both environmental parameters and human physiological responses, the conclusions detailed below were proposed regarding the changes of wettedness under constant average skin temperature.

2. 2. There is positive correlation between the wettedness and environmental humidity, and negative correlation between the wettedness and air temperature.

3. 3. There is positive correlation between the evaporative heat loss from the skin surface and air temperature, and negative correlation between the evaporative heat loss and environmental humidity.

4. 4. There is negative correlation between the wettedness and evaporative heat loss.

5. 5. Wettedness is not constant but takes varying values, that is, corresponding to each average skin temperature both the maximum and the minimum wettedness values occur.

6. 6. Deriving from the items mentioned above, the theoretical locus of equal average skin temperature is not a straight line, but is a curved line plotted on the psychrometric chart.

Welfare implication of measuring heart rate and heart rate variability in dairy cattle: literature review and conclusions for future research

Heart rate (HR) measurements have been used to determine stress in livestock species since the beginning of the 1970s. However, according to the latest studies in veterinary and behaviour–physiological sciences, heart rate variability (HRV) proved to be more precise for studying the activity of the autonomic nervous system. In dairy cattle, HR and HRV indices have been used to detect stress caused by routine management practices, pain or milking. This review provides the significance of HR and HRV measurements in dairy cattle by summarising current knowledge and research results in this area. First, the biological background and the interrelation of the autonomic regulation of cardiovascular function, stress, HR and HRV are discussed. Equipment and methodological approaches developed to measure interbeat intervals and estimate HRV in dairy cattle are described. The methods of HRV analysis in time, frequency and non-linear domains are also explained in detail emphasising their physiological background. Finally, the most important scientific results and potential possibilities for future research are presented.     

The influence of ethnic differences upon human responses due to thermal environment

1. 1. The influence of ethnic differences is discussed with reference to the following issues.

2. 2. It has been found that total numbers of active sweat glands increase in tropical populations compared with people from northern latitudes.

3. 3. It has also been observed that the active sweat glands of Eskimos are fewer than those of Caucasians.

4. 4. The rate of the evaporated sweat loss was calculated by measuring body weight loss and it was found that the evaporated sweat loss of Caucasians is larger than that of Japanese in the same climate.

5. 5. Meteorological factors might have been responsible for the smaller loss in Japanese compared with that of Japanese-Americans.

6. 6. Under the same experimental conditions, it was observed that there were little or no differences between the Caucasians and Negros.

Application of a weighing system for measuring total evaporative water loses in large ruminants

A weighing system originally designed for monitoring changes in the mass of humans due to fluid loss in hospital beds has been adapted to measure the total evaporative water loss of large domestic animals in studies of temperature regulation. Mass loss was monitored on a charge recording and regressed against time. The adaptation resulted in an overall reduction of 73% in the standard error of the regression coefficient of rate of total evaporative water loss. Accuracy was 48% better in the climate chamber than outdoors.     

Validity of a wearable sweat rate monitor and routine sweat analysis techniques using heat acclimation

Introductionthe aim of this study was to assess the validity of a novel wearable sweat rate monitor against an array of sweat analysis techniques which determine sudomotor function when exercising moderately under heat stress. Construct validity was determined utilising a 5-day short-term heat acclimation (STHA) intervention.MethodsNineteen healthy individuals (age: 41 ± 23 years, body mass: 74.0 ± 12.2 kg, height: 174.9 ± 6.9 cm) [male; n = 15, female; n = 4] completed nine trials over a three-week period, in a controlled chamber set to 35 °C, 50% relative humidity for all sessions. The pre and post-trials were separated by five consecutive controlled hyperthermia HA sessions. Sweat analysis was compared from pre and post-trial, whereby whole body sweat rate (WBSR) was assessed via pre and post nude body mass. Local sweat rate (LSR) was determined via technical absorbent patches (TA) (weighed pre and post) and a novel wearable KuduSmart® (SMART) monitor which was placed on the left arm during the 30-min of exercise. Tegaderm patches, used to measure sweat sodium chloride conductivity (SC), and TA patches were placed on the back, chest and forearm for the 30-min cycling.ResultsSudomotor function significantly adapted via STHA (p < 0.05); demonstrated by a WBSR increase of 24%, LSR increase via the TA method (back: 26%, chest: 45% and arm: 48%) and LSR increase by the SMART monitor (35%). Finally, SC decreased (back: -21%, chest: -25% and arm: -24%, p < 0.05).ConclusionAll sweat techniques were sensitive to sudomotor function adaptation following STHA, reinforcing their validity. The real time data given by the wearable KuduSmart® monitor provides coaches and athletes instant comparable sudomotor function feedback to traditional routinely used sweat analysis techniques.     

冬小麦农田暂时水分胁迫状况下水、热通量日变化

以冬小麦农田尺度为研究对象,采用涡度相关技术测定农田能茸平衡各分量,研究暂时水分胁迫状况下农田蒸散通量和蒸发比值（evaporative fraction）日变化特征。结果表明,冬小麦在农田郁闭（LAI≥3）且土壤含水量为田间持水量的55％-65％时,晴天日农田潜热通量日变化在正午前后存在明显的“蒸散高地（evapotranspiration plateau）”现象,持续时间达2．5—4h,表现为蒸散通量增量日变化突然极显著降低,即蒸散通量呈相对稳定、甚至下降的变化趋势;反映在蒸发比值日变化过程方面,夜间和日出日落前后时刻蒸发比值变化较大,7：00-18：00时段内蒸发比值曲线近似呈倒“s”型,9：00～16：00时段内蒸发比值比较稳定,正午前后蒸散高地出现时,蒸发比值有所下降大约在0．5—0．65范围内,12：00—13：30时段内蒸发比值平均值接近9：00—16：00时段内蒸发比值平均值。     

Regional differences in sweat rate response of steers to short-term heat stress

Six Angus steers (319 ± 8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed into two environmental chambers initially maintained at 16.5–18.8°C air temperature (T _a). Cold chamber T _a was lowered to 8.4°C, while T _a within the hot chamber was increased to 32.7°C over a 24-h time period. Measurements included respiration rate, and air and body (rectal and skin) temperatures. Skin temperature was measured at shoulder and rump locations, with determination of sweat rate using a calibrated moisture sensor. Rectal temperature did not change in cold or hot chambers. However, respiration rate nearly doubled in the heat (P < 0.05), increasing when T _a was above 24°C. Skin temperatures at the two locations were highly correlated (P < 0.05) with each other and with T _a. In contrast, sweat rate showed differences at rump and shoulder sites. Sweat rate of the rump exhibited only a small increase with T _a. However, sweat rate at the shoulder increased more than four-fold with increasing T _a. Increased sweat rate in this region is supported by an earlier report of a higher density of sweat glands in the shoulder compared to rump regions. Sweat rate was correlated with several thermal measurements to determine the best predictor. Fourth-order polynomial expressions of short-term rectal and skin temperature responses to hot and cold exposures produced r values of 0.60, 0.84, and 0.98, respectively. These results suggest that thermal inputs other than just rectal or skin temperature drive the sweat response in cattle.     

Influence of day of postpartum breeding on pregnancy rate, pregnancy loss rate, and foaling rate in Thoroughbred mares

Records (years 2005-2007) were analyzed from a Thoroughbred stud farm in central Kentucky. Data from all breeding cycles of foaling mares were tabulated (3184 cycles of 2003 foaling mares bred between 7 and 163 days postpartum). A multiple logistic regression model employing Bayesian statistics was used to adjust for factors that significantly affected outcome; odds ratios (ORs) for pregnancy rate, pregnancy loss rate, and foaling rate were determined to examine the influence of day of postpartum breeding on these parameters. Mares bred before Day 22 (Day 0 = day of foaling) postpartum had a decreased OR for becoming pregnant (P < 0.05); the median OR for becoming pregnant (1.00) was not reached until Day 46 postpartum. Mares bred before Day 13 postpartum had an increased OR for pregnancy loss (P < 0.05). The median OR for pregnancy loss did not decline below 1.00 until Day 78 postpartum. Mares bred before Day 20 postpartum had a decreased OR for producing a foal (P < 0.05). The median OR for producing a foal (1.00) was not reached until Day 75 postpartum. We concluded that fertility (in terms of a higher OR for becoming pregnant and a lower OR for pregnancy loss, resulting in a higher OR for producing a foal) continued to improve in Thoroughbred mares for approximately 2.5 mo postpartum. These findings are of importance to management strategies directed at early postpartum breeding, and explain some of the reported drift in subsequent foaling dates of Thoroughbred mares, despite management practices that employ early postpartum breeding.     

Estimates of tuberculosis progression rate of children in China

In this paper, a discrete mathematical model is formulated to describe tuberculosis (TB) progression from latent infection to active disease. The data of national TB epidemiology surveys in China are taken to estimate the TB progression rate for children aged 0–14 years. The progression rate obtained in this paper gives a detailed and better estimate of TB progression rate among children.     

龙须菜对重金属铜胁迫的生理响应

研究了大型海藻龙须菜(Gracilaria lemaneiformis)对不同浓度重金属铜(0、25、50、100、250和500 μg·L^-1)胁迫的生理响应.结果表明:当Cu²⁺浓度≥50 μg·L^-1时,龙须菜藻体的相对生长速率显著下降,最大光化学量子产量、最大相对电子传递速率和相对电子传递效率呈相同的变化趋势.随着Cu²⁺浓度的升高,龙须菜藻体最大净光合速率和光饱和点显著降低,而光补偿点显著升高,叶绿素a、类胡萝卜素和藻胆蛋白含量则呈先升高后下降的趋势;当Cu²⁺浓度达到500 μg·L^-1时,叶绿素a、类胡萝卜素和藻胆蛋白含量显著下降.说明龙须菜在低浓度Cu²⁺胁迫下具有一定的抵抗能力,而当Cu²⁺浓度≥50 μg·L^-1时,会对藻体生理活动造成显著的抑制作用.     

Weighing the cost: the impact of serial heatwaves on body mass in a small Australian passerine

Rising temperatures pose a grave risk to arid zone birds because they are already living close to their physiological limits and must balance water conservation against the need for evaporative cooling. We assess how extreme temperatures affect a wild population of small passerines by monitoring daily mass change in individual jacky winters Microeca fascinans (a small Australasian robin) across a series of severe heatwaves that afflicted southern Australia in the summer of 2018–2019. Daily maximum temperature and duration of heat exposure were negatively related to the birds’ ability to maintain body mass. At maximum temperatures ≥ 42°C, birds lost 2.0% of their body mass daily and at ≥ 45°C, 2.6%. Apparent mortality increased almost three‐fold, and all breeding birds abandoned their nests. Nevertheless, net daily mass loss was less than might be expected from laboratory‐based findings, presumably because wild jacky winters undertook behavioural thermoregulation. The birds also regained some mass between heatwave events and suffered no long‐term reduction in body condition.     

Physiological acclimation of a desert antelope, Arabian oryx (Oryx leucoryx), to long-term food and water restriction

Desert mammals often experience scarcity of drinking water and food for prolonged periods. In this study, the first long-term acclimation experiment in a non-domesticated desert-adapted ungulate, we investigated the mechanisms used by the Arabian oryx Oryx leucoryx, to adjust its physiology to progressive food and water restriction over 5 months, an experimental regimen and time course chosen to mimic what it typically experiences between spring and late summer in the desert. At the end of the acclimation period, oryx consumed less than one and half of food and water of animals in the control group and lost 8.2±2.6% of their initial body mass. Experimental animals reduced their mass-specific resting metabolic rate (RMR) and total evaporative water loss (TEWL) by 16.2 and 25.7%, respectively, and maintained a digestive efficiency of about 70%. We found no support for the idea that reduced RMR in oryx correlated with a decreased thyroid hormone concentration in plasma. At the end of the 5 months acclimation, oryx continued to mobilize fatty acids to fuel metabolism, and did not use protein breakdown as a major source of gluconeogenesis. Oryx in the experimental group reduced their water intake by 70% and maintained constant plasma osmolality. They adjusted their water budget by reducing mass-specific TEWL, increasing urine osmolality and reducing urine volume by 40%, and excreting feces with <50% water content. Oryx have an unusually low TEWL compared with other arid-zone ungulates; both hydrated and water-deprived individuals have TEWL values, 51.7 and 39.3%, respectively, of allometric predictions for arid-zone ungulates. Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorized users.     

A statistical model of laboratory death rate measurements for airborne bacteria

Summary From 270 published laboratory airborne death rate measurements, two regression models relating the death rate constant for 15 bacterial species to aerosol age in the dark, Gram reaction, temperature, and an evaporation factor which is a function of RH and temperature were obtained. The independent variables accounted for 94% of the variation in the data for each of the two models. In both models the regression shows an increased survival rate with aerosol age accounting for approximately 90% of the total variation in the data. The remainder of the total variation was explained by temperature and RH (in interaction with the Gram reaction) in one model and by the evaporation function (in interaction with the Gram reaction) in the order model. Death rate data for gaseous atmospheric contamination, and light experiments were too few for building a regression model. In addition, these points were not well fit by the model indicating further research is needed to prepare realistic prediction models for airborne bacterial survival.     

Critical thermal maxima and acclimation rate of the tropical guppy Poecilla reticulata

Tropical guppies, Poecilia reticulata, collected from the canal of La Laguna Los Patos were acclimated over a four-week period at local water temperatures of 24–33 °C to determine their critical thermal maxima (CTM) and death points (DP), as criteria of thermal tolerance. In addition, individual thermal tolerance times at a lethal temperature of 38.5 °C were measured over 12 days for upward acclimation from 24 to 30 °C and over 16 days for downward acclimation from 30 to 24 °C to determine acclimation rate just before and after changing the acclimation temperatures. The CTM ranged from 38.95 to 40.61 °C and the average DP varied from 41.22 to 42.86 °C. Positive relationships were apparent between thermal tolerance and acclimation temperatures, and thus heat tolerance criteria (CTM and DP) were significantly different among acclimation temperatures. Individual heat tolerance times increased most rapidly during the first 6 hours of upward acclimation after transfer from 24 to 30 °C, continued to increase another 5 days and fluctuated after initial acclimation was completed. The heat tolerance times of fish transferred from 30 to 24 °C declined steadily over times, reaching a minimum at 14–16 days after transfer.     

Effects of metabolic rate on thermal responses at different air velocities in −10°C

The effects of exercise intensity on thermoregulatory responses in cold (−10°C) in a 0.2 (still air, NoWi), 1.0 (Wi1), and 5.0 (Wi5) m s⁻¹ wind were studied. Eight young and healthy men, preconditioned in thermoneutral (+20°C) environment for 60 min, walked for 60 min on the treadmill at 2.8 km/h with different combinations of wind and exercise intensity. Exercise level was adjusted by changing the inclination of the treadmill between 0° (lower exercise intensity, metabolic rate 124 W m⁻², LE) and 6° (higher exercise intensity, metabolic rate 195 W m⁻², HE). Due to exercise increased heat production and circulatory adjustments, the rectal temperature (T_re), mean skin temperature (T_sk) and mean body temperature (T_b) were significantly higher at the end of HE in comparison to LE in NoWi and Wi1, and T_re and T_b also in Wi5. T_sk and T_b were significantly decreased by 5.0 m s⁻¹ wind in comparison to NoWi and Wi1. The higher exercise intensity was intense enough to diminish peripheral vasoconstriction and consequently the finger skin temperature was significantly higher at the end of HE in comparison to LE in NoWi and Wi1. Mean heat flux from the skin was unaffected by the exercise intensity. At LE oxygen consumption (V ₂) was significantly higher in Wi5 than NoWi and Wi1. Heart rate was unaffected by the wind speed. The results suggest that, with studied exercise intensities, produced without changes in walking speed, the metabolic rate is not so important that it should be taken into consideration in the calculation of wind chill index.     

Identification of an ovulation rate QTL in cattle on BTA14 using selective DNA pooling and interval mapping

Increased twinning incidence in beef cattle has the potential to improve production efficiency. However, phenotypic selection for twinning rate is difficult because of the trait's low heritability and the long time interval necessary to collect phenotypic records. Therefore, this trait and the correlated trait of ovulation rate are ideal candidates for marker-assisted selection. The objective of this study was to complete a genome-wide search for ovulation rate quantitative trait loci (QTL) in two related sire families. The families (paternal halfsib sires 839802 and 839803) were from a population of cattle selected for ovulation rate at the USDA Meat Animal Research Center, Clay Center, Nebraska. Putative ovulation rate QTL have previously been identified in the 839802 family on chromosomes 7 and 19; however, marker coverage in the original scan was not complete. This study fills the gaps in marker coverage of the earlier study by adding approximately 60 informative microsatellites to each sire family. Each family was genotyped using selective DNA pooling. Sons and daughters were included in either the high or low pool based on their estimated breeding value deviations from the mid-parent average (EBVMD) for ovulation rate. Approximately 40% (839802) and 26% (839803) of available progeny comprised the high and low pools combined. Pooled typing revealed possible associations (nominal P < 0.05) between ovulation rate and marker genotype for 11 and 15 microsatellites in the 839802 and 839803 families, respectively. Subsequent interval mapping strengthened support for the presence of an ovulation rate QTL on BTA14 (chromosome-wise P < 0.02).     

晋西黄土区苹果树边材液流速率对环境驱动的响应

为明确环境因子对树木蒸腾过程的驱动机制,以晋西黄土残塬沟壑区的苹果树(红富士)为对象,利用热扩散式液流技术监测生长季苹果树树干液流的动态变化,并同步监测了气象和土壤水分等环境要素的季节动态.结果表明: 在众多环境因子中,太阳净辐射(R_n)、大气水分亏缺(VPD)与液流速率(J_s)间的相关性最强.在小时或日尺度,环境因子主成分分析中前3个主成分的累积方差贡献率均在86%以上.其中,第一主成分主要包含VPD、R_n等因子,方差贡献率达52%(小时尺度)和63%(日尺度)以上,可归为蒸发需求因子(EDI),是影响该地区果树树干液流的关键综合环境要素集;第二主成分主要包括土壤含水率(SWC)等因子,归为土壤水热供给因子;第三主成分主要包括风速等因子,归为大气水热散失动力因子.在小时或日尺度上,J_s对两种环境因子综合变量(EDI或潜在蒸发散ET₀)的响应都呈显著的指数增长关系,在小时尺度上,基于EDI模拟苹果J_s的指数模型精度更高(R²=0.72),在日尺度上,基于ET₀模拟苹果J_s的指数模型模拟精度更高(R²=0.88).研究结果对于明确苹果树水分传输对环境驱动的响应规律,根据气象要素估算苹果树蒸腾耗水量,并指导果园水分管理均具有重要意义.     

盐渍区农田氮肥施用量对土壤硝态氮动态变化的影响

土壤硝态氮动态变化和残留与农田硝态氮淋溶以及地下水硝态氮污染密切相关。为了促进海河低平原盐渍区农田氮肥合理利用以及农业可持续发展,试验在盐化潮土条件下,通过设计不同施氮量（0,70,140,210kg N hm^-2）处理,重点研究了该区农田氮肥施用量对土壤硝态氮动态、残留以及土壤氮损失的影响。结果表明：（1）0～100cm土壤剖面硝态氮总量随施氮量显著增加,施用氮肥没有改变剖面硝态氮总量随玉米生育进程波状变化趋势,但明显增强了其变化幅度;（2）施氮改变了硝态氮土壤剖面空间分布状态,表现出施氮后上部土层（0～40cm）硝态氮比例显著增加而后迅速降低的趋势;（3）硝态氮残留与氮素损失随施氮量增加而增加,且N210和N140处理下氮素损失量显著高于N70和N0。