Dorsal shaving affects concentrations of faecal cortisol metabolites in lactating golden hamsters

Breeding of golden hamsters is classically performed at thermal conditions ranging from 20 to 24 °C. However, growing evidence suggests that lactating females suffer from heat stress. We hypothesised that shaving females dorsally to maximise heat dissipation may reduce stress during reproduction. We thus compared faecal cortisol metabolites (FCM) from shaved golden hamster mothers with those from unshaved controls. We observed significantly lower FCM levels in the shaved mothers (F_1,22?=?8.69, p?=?0.0075) pointing to lower stress due to ameliorated heat dissipation over the body surface. In addition, we observed 0.4 °C lower mean subcutaneous body temperatures in the shaved females, although this effect did not reach significance (F_1,22?=?1.86, p?=?0.18). Our results suggest that golden hamsters having body masses being more than four times that of laboratory mice provide a very interesting model to study aspects of lactation and heat production at the same time.     

Hot bats: extreme thermal tolerance in a desert heat wave

Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures (T _a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T _as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed (Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats (Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T _a was ～45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T _a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures (T _skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T _skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T _skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T _skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death.     

Projected change in climate thresholds in the Northeastern U.S.: implications for crops, pests, livestock, and farmers

Most prior climate change assessments for U.S. agriculture have focused on major world food crops such as wheat and maize. While useful from a national and global perspective, these results are not particularly relevant to the Northeastern U.S. agriculture economy, which is dominated by dairy milk production, and high-value horticultural crops such as apples (Malus domestica), grapes (Vitis vinifera), sweet corn (Zea mays var. rugosa), cabbage (Brassica oleracea var. capitata), and maple syrup (sugar maple, Acer saccharum). We used statistically downscaled climate projections generated by the HadCM3 atmosphere–ocean general circulation model, run with Intergovernmental Panel on Climate Change future emissions scenarios A1fi (higher) and B1 (lower), to evaluate several climate thresholds of direct relevance to agriculture in the region. A longer (frost-free) growing season could create new opportunities for farmers with enough capital to take risks on new crops (assuming a market for new crops can be developed). However, our results indicate that many crops will have yield losses associated with increased frequency of high temperature stress, inadequate winter chill period for optimum fruiting in spring, increased pressure from marginally over-wintering and/or invasive weeds, insects, or disease, or other factors. Weeds are likely to benefit more than cash crops from increasing atmospheric carbon dioxide. Projections of thermal heat index values for dairy cows indicate a substantial potential negative impact on milk production. At the higher compared to lower emissions scenario, negative climate change effects will occur sooner, and impact a larger geographic area within the region. Farmer adaptations to climate change will not be cost- or risk-free, and the impact on individual farm families and rural communities will depend on commodity produced, available capital, and timely, accurate climate projections.     

The characterization and comparison of ozone exposure indices used in assessing the response of loblolly pine to ozone

Using the 1988 and 1989 experimental results obtained for two loblolly pine half-sibling families (GAKR 15–23 and GAKR 15–91) at the Auburn University intensive field research site, we: (1) explored the performance of a set of exposure indices; (2) characterized the ambient air and charcoal-filtered air treatments at Auburn and compared the values of the O₃ exposure indices with those values calculated for ambient O₃ monitors for a select set of sites; (3) identified and characterized O₃ treatments in the Auburn open-top exposure chambers where an adverse effect was noted; and (4) identified where such experimental exposure regimes occurred under ambient conditions. We found that the SUMO exposure index did not perform adequately. We were unable to distinguish among the performances of the SUM06, W126, and SUM08 exposure indices. The results of the analyses of six estimated logistic parameters for a model of diameter² × height (d²h) vs time indicated O₃ effects for both families. At pH 4.3 (near ambient conditions), a response to O₃ was detected in the NF × 2.5 treatments for both families for t₂, the approximate time of maximum growth during the second year. Using ln (final d²h), family 23 did not show O₃ effects. A comparison of the exposures experienced in the NF × 2.5 treatments with those occurring under ambient conditions at other locations showed that in 1983 and 1986, the San Bernardino County (CA) site experienced O₃ exposures similar to those values experienced at the NF × 2.5 treatments in 1989.     

On the trend of the transmittance of direct solar irradiance in Athens during the summer

In recent years, high concentrations of air pollutants in Athens have been measured. Since 1962 measurements of the broadband direct solar irradiance, which is directly affected by the aerosol loading in the atmosphere, have been avialable from the National Observatory of Athens (NOA). Using these data, the year to year trend of the mean value of the midday transmittance with clear sky in summer is evaluated for the period 1962–1985. A pronounced decrease of the transmittance occurred between the years 1962 and 1975. This probably reflects the rapid urbanization of the Athens area.     

Cutting tool temperatures in interrupted cutting—The effect of feed-direction modulation

Transient tool temperatures in interrupted machining processes were investigated. The initial focus was feed-direction modulated turning. Here, the instantaneous uncut chip thickness (IUCT) was modeled including the regenerative effect introduced by the modulation. Treating the tool as a one-eighth semi-infinite body, for a rectangular heat patch governed by the IUCT at the corner, the tool heat conduction problem was solved. The Green’s function solution procedure included heat convection from exterior surfaces. The results indicated that modulation lowered the cutting temperature, more significantly at a higher modulation frequency. However, heat conduction into the tool dominated over convection to the ambient. The IUCT was found to lag the peak temperature, indicating that modulation can possibly alter the thermal softening of the cutting tool in continuous cutting without a concomitant decrease in material removal rate. The same tool temperature model applied to face-milling indicated that the peak temperature occurred only at cut exit. Carefully planned interrupted hard-facing experiments were performed varying the frequency and duration of interruption. Tool-life data confirmed the beneficial effects of lower cutting temperatures due to slight interruption.     

Sodar in air pollution meteorology

Information concerning atmospheric stability and turbulence is basic in studies related to air pollution meteorology. In this context a monostatic sodar has been operating at the National Physical Laboratory, New Delhi, for many years to probe the thermal structure of the lower atmosphere in real time and space.Various observed thermal structures viz. nocturnal inversion, thermal plumes, formation and break-up of inversion, orographical mixing, multilayered structures and waves etc., are the result of the different atmospheric stabilities and turbulence conditions. These structures have been studied in the light of surface measurements of wind speed and direction for organized indexing of the structural details to infer meteorological conditions concerning Pasquill stability classifications.The height of the ground-based thermal structure has been correlated with the Richardson number, Ri, for quantitative estimation of the turbulence parameter. Estimated values of Ri have been further used to determine the cross wind dispersion coefficient, σ_y. The results obtained are realistic and can be used as input parameters for air pollution modelling.     

Analysis of temperature effects on seasonal and interannual variation in CH4 emission from rice-planted pots

Rice (Oryza sativa L.) paddies are one of the major sources of atmospheric methane (CH₄), a greenhouse gas. To elucidate the quantitative relationship between CH₄ emission from rice paddies and temperature, 6 years data of CH₄ emission from pot experiments were analyzed in terms of the sum of effective temperature (∑(T−15); T is the daily mean air temperature (°C)). The base temperature of 15 °C was adopted as the 0 °C physiological temperature for methanogens. Significant positive correlations between total CH₄ emission throughout the rice growth period and ∑(T−15) were observed for pots with rice straw (RS) application at a rate of 6 g kg⁻¹ soil, which corresponds to 6 t ha⁻¹ (r=0.830⁷¹), and those without RS application (r=0.818⁷¹). It was confirmed that temperature is a major factor affecting the interannual variation in CH₄ emission. For the 1993 and 1995 data sets that include seven and four levels of RS application, the relationship between seasonal CH₄ emission and RS application rate could be expressed using linear functions (r=0.988⁷¹, 0.996⁷¹), the slopes of which were similar to each other. Based on these findings, we confirmed that the dependence of seasonal CH₄ emission on both temperature and RS application rate can be described by a single linear equation.     

An application of NOAA AVHRR thermal data to the study of urban heat islands

Brightness temperatures were derived from the Advanced Very High Resolution Radiometer (AVHRR) at channel 4 (10.5–11.5 μm) on the NOAA-9 and NOAA-10 satellites to examine the applicability of the AVHRR thermal data to the study of urban heat islands. Air and ground surface temperatures measured at meteorological stations in large cities (population over 300,000) in South Korea were compared with in situ brightness temperature data.The correlation coefficient between air temperatures and brightness temperatures is 0.85 and the relationship may be expressed by the regression: AT=0.59 BT + 2.54. This equation explains 73% of variances at the 0.02% significance level. The best-fit line, however, underestimates air temperatures in such heat-processing industrial cities as Ulsan and Pohang, where smoke puffs up from the high stacks of industrial plants, and overestimates them in the Seoul metropolitan area. The regression equation of ground surface temperatures on brightness temperatures explains 72% of variances. Assuming that optimal meteorological conditions can be selected, the regression equation can be used as a tool to assess air temperature fields in cities.Urban land-use, such as built-up, residential and industrial areas, was clearly identified from the AVHRR thermal data, while small-scale land-use, like parks, were not distinguishable. Brightness temperatures for the intensity of heat islands were related to the population size of cities. The areal magnitude of heat islands in the Seoul metropolitan area expanded considerably, reflecting the conurbation trend for the period 1986–1989. Urban temperatures in the area increased during the period, while temperature gradients declined.     

Transpiration rates of urban trees, Aesculus chinensis

Transpiration patterns of Aesculus chinensis in relation to explanatory variables in the microclimatic, air quality, and biological phenomena categories were measured in Beijing, China using the thermal dissipation method. The highest transpiration rate measured as the sap flux density of the trees took place from 10:00 am to 13:00 pm in the summer and the lowest was found during nighttime in the winter. To sort out co-linearity, principal component analysis and variation and hierarchical partitioning methods were employed in data analyses. The evaporative demand index (EDI) consisting of air temperature, soil temperature, total radiation, vapor pressure deficit, and atmospheric ozone (O₃), explained 68% and 80% of the hourly and daily variations of the tree transpiration, respectively. The independent and joint effects of EDI variables together with a three-variable joint effect exerted the greatest influences on the variance of transpiration rates. The independent effects of leaf area index and atmospheric O₃ and their combined effect exhibited minor yet significant influences on tree transpiration rates.     

An experimental study of nightime air-pollutant transport over complex terrain in Athens

The Thriassion plain is a heavily industrialized area to the west of the Athens basin, separated from it by Mount Aegaleo, a 468-m high ridge about 15 km long. Three field experiments were performed to determine the possibility of air pollutant transport into the Athens basin. Sulphur hexafluoride (SF₆) was released from one of the stacks of the Hellenic Oil Refineries, situated in the eastern part of the Thriassion plain, together with several releases of tetroons. These experiments revealed two mechanisms of air mass transport from the Thriassion plain, a daytime mechanism, when the air mass is transported along the Mount Aegaleo ridge and through the passage between Mount Aegaleo and Mount Parnitha to the north, and a nighttime mechanism, when transport occurs over Mount Aegaleo. SF₆ was released only during the night and although in all three occassions it reached the western suburbs of Athens, it did so by different simultaneous mechanisms. Furthermore its advection-diffusion once in the basin showed large variability, whose cause was the details of the flow field as it developed under the influence of the thermal stratification. The experiments demonstrate the complexity of the diffusion of air pollutants in complex terrain and the influence of both the details of the flow field and the stratification in determining the local ground-level concentrations. They also point out the need for simultaneous modelling of both factors, for the correct computation of pollution levels.     

太原市2014年春节期间常规大气污染物浓度变化及聚类分析

为了探寻太原市春节期间不同监测站点各常规大气污染物的质量浓度变化规律及相互之间的关系,记录和收集了太原市上兰、南寨、涧河、尖草坪、桃园、坞城、小店、金胜、晋源9个监测点2014年农历小年至元宵节(2014-01-23—2014-02-14)期间的大气PM2.5、PM10、CO、NO2、O3、SO2小时浓度值以及相应的气温、气压、湿度、风级、能见度等气象数据,采用相关分析、小波分析、单因子污染指数评价和系统聚类等方法进行研究,发现:1该时段内就太原市总体而言,PM2.5超标倍数最大,其次是PM10、SO2、CO、NO2,O3污染最小.2农历小年、除夕、正月初八、元宵节大气PM2.5和PM10的浓度迅速增加,与自然气象因子基本无关,说明烟花爆竹的集中燃放对大气颗粒物尤其是细颗粒物产生较大影响.3SO2、NO2、CO与PM2.5和PM10浓度变化的波动趋势相似、主周期相同,反映了部分PM2.5和PM10与SO2、NO2、CO有共同的来源;O3的波动趋势及主周期与上述污染物完全不同,显示出它来源的特殊性.4按PM2.5聚类,南寨、涧河、尖草坪、桃园4个点聚为一类,小店和坞城2个点聚为一类,金胜和晋源聚为一类,位于太原市最北端作为清洁对照的上兰监测点自成一类,与它们的地理位置有较好的相符性,同时,聚类分析结果与各监测点的单因子污染指数评价结果相一致.本文提示小波分析与聚类分析相结合可以较好地反映城市大气污染物浓度变化的时间与空间分布规律.     

中国陆地生态系统土壤异养呼吸变异的影响因素

土壤异养呼吸是生态系统碳平衡估算中的关键因子之一.通过文献调研,收集了中国陆地生态系统中土壤异养呼吸的观测数据,同时收集整理了试验地点气候资料(年总降水量和年平均气温)和环境因子(如树木生长年龄)指标.结果表明,异养呼吸与土壤呼吸的关系可用幂函数方程描述,异养呼吸随土壤呼吸的增大而增大,该幂函数方程可解释异养呼吸73%(R2=0.730,P<0.001)的变异.异养呼吸与年总降水量以及年平均气温的关系均可用一元线性方程描述.异养呼吸占土壤呼吸的比例与年总降水量、年平均气温的关系均可用对数回归方程描述,异养呼吸占土壤呼吸的比例随年总降水量的增大和年平均气温的升高而减小.异养呼吸占土壤呼吸的比例随树龄的增大而增大,两者之间的关系可用幂函数方程描述.进一步的结果表明,经验模型模拟得到的异养呼吸模拟值与实际样地观测结果之间呈显著的线性回归关系,采用的经验统计模型可较好地模拟异养呼吸的变异.     

湛江电厂温排水对滨海水体生态环境的影响

2011年1月对湛江电厂温水排放口附近水域的生态环境进行了采样调查,分析了温排水对受纳水体的水温、溶解氧、营养盐、叶绿素a以及浮游植物的细胞密度、群落组成多样性和均匀度的影响。结果表明:电厂温排水主要影响表层水且范围较小;溶解氧虽随水温的变化稍有变化,但含量均在5.00 mg/L以上,符合渔业水域水质标准;温排水促进了受纳水体的富营养化,自然水温处至排水口中心,营养盐(无机氮、活性磷酸盐)、叶绿素a和浮游植物的细胞密度、种类数呈递增趋势;从浮游植物群落的多样性指数和均匀度分析,温排水提高了群落的多样性和抗干扰能力;在对浮游植物与主要环境因子间的偏相关性分析发现,浮游植物细胞密度和水温呈极显著正相关,相关系数为0.941 8(p<0.01),与活性硅酸盐呈显著负相关,相关系数为-0.892 4(p<0.05),与其他因子相关性不明显。     

Vasculature of the hive: heat dissipation in the honey bee (Apis mellifera) hive

Eusocial insects are distinguished by their elaborate cooperative behavior and are sometimes defined as superorganisms. As a nest-bound superorganism, individuals work together to maintain favorable nest conditions. Residing in temperate environments, honey bees (Apis mellifera) work especially hard to maintain brood comb temperature between 32 and 36 °C. Heat shielding is a social homeostatic mechanism employed to combat local heat stress. Workers press the ventral side of their bodies against heated surfaces, absorb heat, and thus protect developing brood. While the absorption of heat has been characterized, the dissipation of absorbed heat has not. Our study characterized both how effectively worker bees absorb heat during heat shielding, and where worker bees dissipate absorbed heat. Hives were experimentally heated for 15 min during which internal temperatures and heat shielder counts were taken. Once the heat source was removed, hives were photographed with a thermal imaging camera for 15 min. Thermal images allowed for spatial tracking of heat flow as cooling occurred. Data indicate that honey bee workers collectively minimize heat gain during heating and accelerate heat loss during cooling. Thermal images show that heated areas temporarily increase in size in all directions and then rapidly decrease to safe levels (<37 °C). As such, heat shielding is reminiscent of bioheat removal via the cardiovascular system of mammals.     

Effects of atmospheric CO2 enrichment on plant growth: the interactive role of air temperature

Comprehensive reviews of the plant science literature indicate that a 300 part per million (ppm) increase in atmospheric carbon dioxide (CO₂) concentration generally increases plant growth by approximately 30%. Working with two species of floating aquatic plants and three terrestrial species, we demonstrate that this stimulatory effect of atmospheric CO₂ enrichment is strongly temperature dependent. Indeed, our results suggest that for a 3°C increase in mean surface air temperature (as is generally predicted to result from the ‘greenhouse effect’ of such an increase in the CO₂ content of the air), the growth enhancement factor for such a CO₂ increase rises from 1.30 to 1.56. If the non-CO₂ trace gas greenhouse effect is equally as strong, as recent model studies suggest, the growth enhancement factor rises still higher to a value of 1.85. On the other hand, our results also indicate that atmospheric CO₂ enrichment tends to reduce plant growth at relatively cold air temperatures, i.e. below a daily mean air temperature of approximately 18.5°C. As a result, predicting the ultimate biospheric consequences of a doubling of the Earth's atmospheric CO₂ concentration may prove to be much more complex than originally anticipated.     

20世纪90年代以来上海地区热量资源变化研究

全球气候变暖引起上海地区热量资源的变化。为了摸清20世纪90年代以来上海地区热量资源变化规律,论文根据1991至2003年上海地区11个站年气温、地温资料,在与前30年(1961至1990年)平均比较的基础上,统计分析1991年以来气温、地温、积温、界限温度及无霜期等体现热量资源特征气候值的变化情况,结果表明:1991至2003年,上海地区气温年平均升高0.9℃,5cm深度地温年平均升高0.5℃,≥3℃有效积温年平均升高219℃.d,≥10℃有效积温年平均升高77℃.d,稳定通过0℃、10℃持续期平均延长12.5d和5.7d及无霜期平均延长9.4d,热量资源增加。     

中亚水热资源匹配特征及敏感性分析

从水热积指数出发,基于1931—2019年Climatic Research Unit（CRU）再分析资料,运用多时序分析方法,从多时间尺度分析中亚水热资源匹配空间特征和时序变化,并进行敏感归因探究。结果表明：（1）空间上中亚水热匹配条件存在相对优劣,优势区多分布于高纬及高山高原地带,水热资源匹配较差区域分布于南部沙漠。优势区多和同期降水高值区、潜在蒸散低值区和气温低值区重合,年际水热积指数变化不明显或呈弱下降趋势;较差区域多为同期潜在蒸散和气温高值区,降水低值区,水热积指数降低且年际变幅较大。（2）中亚水热资源匹配年内存在季节差异,春秋较好、冬季次之、夏季较差;在年际尺度上,1931—1974年,水热匹配条件呈现上升趋势;1974—2000年左右,水热匹配条件波动上升;2000—2019年,水热匹配条件下降,且在1971—1980年、1981—1990年、1990—2000年发生匹配条件突变。春夏秋季水热匹配变化趋势同年际趋势大致相同,冬季波动幅度较小。（3）在春、夏及年尺度上,主导敏感性因子为平均气温因子,在秋冬两季为降水因子;在高纬、高原高山区,水热积指数变化敏感性气候因子多为降水因子;中亚南部水热积指数变化对降水敏感性减弱,平均气温敏感性增加,且北部平均气温敏感性系数绝对值略低于南部;高山高原区域对极端温度变化较为敏感。     

Three-year lifecycle,large body,and very high threshold temperature in the cricket <Emphasis Type="Italic">Gryllus argenteus</Emphasis> for special adaptation to desiccation cycle in Malawi

In temperate climates, the initiation and termination of diapause synchronize the stress-tolerant stage with the stressful season and reproduction with the non-stressful season in many insects. Synchronization is often regulated by photoperiodism.Voltinism and the ultimate size of adults are also important determinants for their lifecycle, and different diapause stages and voltinism patterns are known in crickets.Here, we investigated the life history of the African cricket Gryllus argenteus from Malawi, which is a typical arid tropical highland. The climate is characterized by alternating arid and wet seasons, each of which lasts for half a year, and where the available heat mass is much less than lowlands at the same latitude. We first measured the nymphal duration at each rearing temperature and calculated the lower developmental threshold (t ₀) to be 20.19 °C based on Ikemoto and Takai (2000) and 19.38 °C based on a conventional line-fitting method. These values are very high relative to many other insects. The local temperature in winter does not fall below 15 °C, but this is much higher than the lethal limit. This suggested that critical stress in this locality was not coldness but low precipitation in winter. We estimated, based both on local temperature change and the Ikemoto and Takai’s t ₀, that G. argenteus required 3 years to complete its lifecycle unlike wet lowland species, where univoltinism or multi-voltinism are commonplace. Photoperiodism was observed in this species, but due to a lag between annual cycles in photoperiod, temperature, and humidity, photoperiodism alone cannot atune their lifecycle with local conditions.Synchronization in this species was achieved by three different adaptations: photoperiodism, high t ₀, and large body size, which give it a long lifecycle. Although the species cannot achieve a univoltine lifecycle because of its high t₀ value, it can escape from dry season by entering diapause at moderate temperatures, probably thereby achieving adaptive synchrony of lifecycle with both favorable and unfavorable seasons. A comparison between a conventional photothermogram and a newly formulated photohydrogram or photohygrogram demonstrates that even though sufficient heat is available, scarcity of water and thus scarcity of foliage should force the cricket to maintain diapause at intermediate temperature. The results suggested that high t ₀, large body size, and multi-ennial lifecycle mutually affect each other and formulate a unique adaptation under such an extreme environment.     

北方农牧交错带农业气候资源空间特征分析

运用GIS与RS技术,选择日平均温度、生育期日平均温度、生育期积温、生育期降水、全年降水和生育期日照时数等指数,依据主要作物适宜条件构建模糊隶属函数,利用主成分分析法定量评判研究区农业气候资源适宜度。在此基础上,进一步指出农业气候资源各单项指数及综合指数的空间分异规律。结果表明:①相对热量和光照而言,水分是研究区农牧林业生产的主要限制因子,水分指数的分布大体呈现东北-西南走向;②研究区总气候资源指数和资源效能指数的计算表明,农业气候资源潜力小,光、热、水的配合效果差;两指数由东南向西北的分布次序均为由好到差;③研究区气候资源利用效率计算表明:大多数作物对农业气候资源利用的实际效率低。该指数由东南向西北的分布次序为较高、一般、较低和低4种类型。