An experiment was conducted to determine the effect of different stocking densities on serum corticosterone (CORT), ovotransferrin (OVT), α1-acid glycoprotein (AGP) and ceruloplasmin (CP) concentrations, brain heat shock protein (HSP) 70 expression and performance in broiler chickens exposed to unheated and heated conditions. Day-old chicks were stocked at 0.100 m(2)/bird (low density (LD)) or 0.063 m(2)/bird (high density (HD)), in battery cages and housed in environmentally controlled rooms. From 21 to 35 days of age, birds from each stocking density group were exposed to either 24 or 32 °C. Growth performance was recorded during the heat treatment period, and blood and brain samples were collected to determine CORT, OVT, AGP, CP and HSP 70 levels on day 35. Heat treatment but not stocking density was detrimental to growth performance. There were significant temperature × density interactions for CORT, CP and OVT on day 35. Although HD elevated CORT, CP and OVT when compared to LD, the effects of the former were more obvious under heated condition. Both temperature and density had significant effect on AGP and HSP 70. In conclusion, irrespective of temperature, high stocking density was physiologically stressful to broiler chickens, as indicated by CORT, AGP, CP, OVT and HSP 70, but not detrimental to growth performance and survivability. As it was shown in the present study, AGP, CP and OVT could be useful biomarkers to determine the effect of overcrowding and high temperature on the welfare of broiler chickens.
Asymmetrical street aspect ratios, i.e. different height-to-width (H1/W-H2/W) ratios, have not received much attention in the study of urban climates. Putrajaya Boulevard (northeast to southwest orientation) in Malaysia was selected to study the influence of six asymmetrical aspect ratio scenarios on the street microclimate using the Envi-met three-dimensional microclimate model (V3.1 Beta). Putrajaya Boulevard suffers from high surface and air temperature during the day due to the orientation, the low aspect ratio and the wide sky view factor. These issues are a common dilemma in many boulevards. Further, low and high symmetrical streets are incompatible with tropical regions as they offer conflicting properties during the day and at night. These scenarios are examined, therefore, to find asymmetrical streets which are able to reduce the impact of the day microclimate on boulevards, and as an alternative strategy fulfilling tropical day and night climatic conditions. Asymmetrical streets are better than low symmetrical streets in enhancing wind flow and blocking solar radiation, when tall buildings confront winds direction or solar altitudes. Therefore, mitigating heat islands or improving microclimates in asymmetrical streets based on tall buildings position which captures wind or caste shades. In northeast to southwest direction, aspect ratios of 0.8-2 reduce the morning microclimate and night heat islands yet the negative effects during the day are greater than the positive effects in the night. An aspect ratio of 2-0.8 reduces the temperature of surfaces by 10 to 14 °C and the air by 4.7 °C, recommended for enhancing boulevard microclimates and mitigating tropical heat islands.
Asthma is a chronic condition of great public health concern globally. The associated morbidity, mortality and healthcare utilisation place an enormous burden on healthcare infrastructure and services. This study demonstrates a multistage quantile regression approach to predicting excess demand for health care services in the form of asthma daily admissions in London, using retrospective data from the Hospital Episode Statistics, weather and air quality. Trivariate quantile regression models (QRM) of asthma daily admissions were fitted to a 14-day range of lags of environmental factors, accounting for seasonality in a hold-in sample of the data. Representative lags were pooled to form multivariate predictive models, selected through a systematic backward stepwise reduction approach. Models were cross-validated using a hold-out sample of the data, and their respective root mean square error measures, sensitivity, specificity and predictive values compared. Two of the predictive models were able to detect extreme number of daily asthma admissions at sensitivity levels of 76 % and 62 %, as well as specificities of 66 % and 76 %. Their positive predictive values were slightly higher for the hold-out sample (29 % and 28 %) than for the hold-in model development sample (16 % and 18 %). QRMs can be used in multistage to select suitable variables to forecast extreme asthma events. The associations between asthma and environmental factors, including temperature, ozone and carbon monoxide can be exploited in predicting future events using QRMs.
This paper addresses a concurrent multidisciplinary problem: animal safety against lightning hazards. In regions where lightning is prevalent, either seasonally or throughout the year, a considerable number of wild, captive and tame animals are injured due to lightning generated effects. The paper discusses all possible injury mechanisms, focusing mainly on animals with commercial value. A large number of cases from several countries have been analyzed. Economically and practically viable engineering solutions are proposed to address the issues related to the lightning threats discussed.
The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese) natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages: 22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m(-2) h(-1)) and Japanese (83.2 ± 6.4 g m(-2) h(-1)) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese (0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function.
Larvae of Aedes albopictus Skuse typically inhabit natural and artificial containers. Since these larval habitats are replenished by rainfall, Ae. albopictus may experience increased loss of immature stages in areas with high levels of rainfall. In this study, we investigated the effects of rainfall and container water level on population density, and oviposition activity of Ae. albopictus. In field and laboratory experiments, we found that rainfall resulted in the flushing of breeding habitats. Excess rain negatively impacted larval and pupal retention, especially in small habitats. When filled with water to overflowing, container habitats were significantly repellent to ovipositing females. Taken together, these data suggest that rainfall triggers population loss of Ae. albopictus and related species through a direct detrimental effect (flushing out) and an indirect effect (ovipositional repellency).
This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).
High ambient temperature is a major problem in commercial broiler production in the humid tropics because high producing broiler birds consume more feed, have higher metabolic activity, and thus higher body heat production. To evaluate the effects of two previously isolated potential probiotic strains (Lactobacillus pentosus ITA23 and Lactobacillus acidophilus ITA44) on broilers growing under heat stress condition, a total of 192 chicks were randomly allocated into four treatment groups of 48 chickens each as follows: CL, birds fed with basal diet raised in 24 °C; PL, birds fed with basal diet plus 0.1 % probiotic mixture raised in 24 °C; CH, birds fed with basal diet raised in 35 °C; and PH, birds fed with basal diet plus 0.1 % probiotic mixture raised in 35 °C. The effects of probiotic mixture on the performance, expression of nutrient absorption genes of the small intestine, volatile fatty acids (VFA) and microbial population of cecal contents, antioxidant capacity of liver, and fatty acid composition of breast muscle were investigated. Results showed that probiotic positively affected the final body weight under both temperature conditions (PL and PH groups) compared to their respective control groups (CL and CH). Probiotic supplementation numerically improved the average daily gain (ADG) under lower temperature, but significantly improved ADG under the higher temperature (P
Natives of the tropics are able to tolerate high ambient temperatures. This results from their long-term residence in hot and often humid tropical climates. This study was designed to compare the peripheral mechanisms of thermal sweating in tropical natives with that of their temperate counterparts. Fifty-five healthy male subjects including 20 native Koreans who live in the temperate Korean climate (Temperate-N) and 35 native tropical Malaysian men that have lived all of their lives in Malaysia (Tropical-N) were enrolled in this study after providing written informed consent to participate. Quantitative sudomotor axon reflex testing after iontophoresis (2 mA for 5 min) with 10% acetylcholine (ACh) was used to determine directly activated (DIR) and axon reflex-mediated (AXR) sweating during ACh iontophoresis. The sweat rate, activated sweat gland density, sweat gland output per single gland activated, and oral and skin temperature changes were measured. The sweat onset time of AXR (nicotinic-receptor-mediated) was 56 s shorter in the Temperate-N than in the Tropical-N subjects (P < 0.0001). The nicotinic-receptor-mediated sweating activity AXR (1), and the muscarinic-receptor-mediated sweating activity DIR, in terms of sweat volume, were 103% and 59% higher in the Temperate-N compared to the Tropical-N subjects (P < 0.0001). The Temperate-N group also had a 17.8% (P < 0.0001) higher active sweat gland density, 35.4% higher sweat output per gland, 0.24 degrees C higher resting oral temperature, and 0.62 degrees C higher resting forearm skin temperature compared to the Tropical-N subjects (P < 0.01). ACh iontophoresis did not influence oral temperature, but increased skin temperature near where the ACh was administered, in both groups. These results suggest that suppressed thermal sweating in the Tropical-N subjects was, at least in part, due to suppressed sweat gland sensitivity to ACh through both recruitment of active sweat glands and the sweat gland output per each gland. This physiological trait guarantees a more economical use of body fluids, thus ensuring more efficient protection against heat stress.
The diversity and abundance of macroinvertebrate shredders were investigated in 52 forested streams (local scale) from nine catchments (regional scale) covering a large area of peninsular Malaysia. A total of 10,642 individuals of aquatic macroinvertebrates were collected, of which 18.22% were shredders. Biodiversity of shredders was described by alpha (αaverage), beta (β) and gamma diversity (γ) measures. We found high diversity and abundance of shredders in all catchments, represented by 1,939 individuals (range 6-115 and average per site of 37.29±3.48 SE) from 31 taxa with 2-13 taxa per site (αaverage=6.98±0.33 SE) and 10-15 taxa per catchment (γ=13.33±0.55 SE). At the local scale, water temperature, stream width, depth and altitude were correlated significantly with diversity (Adj-R2=0.205). Meanwhile, dissolved oxygen, stream velocity, water temperature, stream width and altitude were correlated to shredder abundance (Adj-R2=0.242). At regional scale, however, water temperature was correlated negatively with β and γ diversity (r2=0.161 and 0.237, respectively) as well as abundance of shredders (r2=0.235). Canopy cover was correlated positively with β diversity (r2=0.378) and abundance (r2=0.266), meanwhile altitude was correlated positively with β (quadratic: r2=0.175), γ diversity (quadratic: r2=0.848) as well as abundance (quadratic: r2=0.299). The present study is considered as the first report describing the biodiversity and abundance of shredders in forested headwater streams across a large spatial scale in peninsular Malaysia. We concluded that water temperature has a negative effect while altitude showed a positive relationship with diversity and abundance of shredders. However, it was difficult to detect an influence of canopy cover on shredder diversity.
Understanding the impacts of climate change on crop yield is important for improving crop growth and yield formation in northwestern China. In this study, we evaluated the relationship between meteorological dryness/wetness conditions and spring wheat yield in the Ili river basin (IRB). The climate and yield data from 1961 to 2013 were collected to analyze characteristics and correlations between these two variables using the standardized precipitation evapotranspiration index (SPEI), yield detrending method, modified Mann-Kendall test and Spearman correlation analysis. Main results were as follows: (1) correlations between monthly SPEI values (MSV) and climatic yield of spring wheat indicated that the dryness/wetness condition in May was a key factor affecting yield in the whole region; (2) although the MSV in May and yield fluctuated from negative to positive values in time, the severely and extremely dryness events were in good agreement with the higher yield losses; (3) each increase of 0.5 MSV in May promoted over 3% increase of yield in most part of IRB; however, the larger variability of MSV in May resulted in larger yield fluctuations; and (4) the Tibetan Plateau index in April showed significant correlations with the MSV in May and yield, which provided a precursory signal for decision-makers to better understand potential yield fluctuations.