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1.
The environmental profile of central Arizona is quantitatively described using meteorological data between 1971 and 1986. Utilizing ambient temperature criteria of hours per day less than 21° C, between 21 and 27° C, and more than 27° C, the environmental profile of central Arizona consists of varying levels of thermoneutral and heat stress periods. Milk production data from two commercial dairy farms from March 1990 to February 1991 were used to evaluate the seasonal effects identified in the environmental profile. Overall, milk production is lower during heat stress compared to thermoneutral periods. During heat stress, the cool period of hours per day with temperature less than 21° C provides a margin of safety to reduce the effects of heat stress on decreased milk production. Using minimum, mean and maximum ambient temperatures, the upper critical temperatures for milk production are 21, 27 and 32° C, respectively. Using the temperature-humidity index as the thermal environment indicator, the critical values for minimum, mean and maximum THI are 64, 72 and 76, respectively.  相似文献   

2.
The influence of a 24 h fast on endurance performance and the metabolic response to maximal cycle exercise was investigated in 6 healthy men (mean +/- SD: age = 27 +/- 7 years; weight = 73 +/- 10 kg; VO2max = 46 +/- 10 ml.kg-1.min-1). Subjects performed in randomised order two exercise bouts to exhaustion separated by one week. Test rides were performed in fasted (F) and post-absorptive (normal-diet, ND) conditions on an electrically braked cycle ergometer at a workload equivalent to 100% of VO2max. Acid-base status and selected metabolites were measured on arterialised venous blood at rest prior to exercise and at intervals for 15 mins following exercise. Exercise time to exhaustion was shorter after F compared with ND (p less than 0.01). Pre-exercise blood bicarbonate (HCO3-) concentration, PCO2 and base excess (BE) were lower after F compared with ND (p less than 0.05). Prior to exercise, circulating concentrations of free fatty acids (FFA), beta-hydroxybutyrate (B-HB) and glycerol were higher after F compared with ND (p less than 0.01) but blood glucose and lactate concentration were not different. On the F treatment, after exercise, blood pH, HCO3-, and BE were all significantly higher (p less than 0.01) than on ND; blood lactate concentration was significantly lower for the whole of the post-exercise period after F compared with ND (p less than 0.01). Circulating levels of FFA and B-HB after exercise on the F treatment fell but levels of these substrates were not altered by exercise after ND.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
The purpose of this study was to determine the effects of acute exercise on IL-17 concentrations in hot and neutral environments in trained males. Ten trained, non-heat acclimated males performed two 1 h run on treadmill at 60% VO2max in neutral (22±1 °C, 50±5RH) and hot (35±1 °C, 50±5) temperature conditions. Samples of the venous blood were taken (Pre, post, 2 h post) for determination of serum IL-17, cortisol concentrations and numbers of leukocytes and neutrophils. In addition, body temperature, RPE and PVC during exercise were measured. The collected data were analyzed using the Repeated-Measures analyses of variance and Bonferroni post hoc and Paird T tests (p<0.05). The concentration of cortisol and total number of leukocytes increased significantly after exercise, in both conditions (p<0.0001) and were significantly higher in hot than neutral (p=0.016, p=0.002). During the rest period (2 h post) the number of neutrophils increased significantly in hot environment (p=0.018). The concentrations of IL-17 increased significantly only after exercise in hot (p<0.0001) and were significantly higher during hot than neutral (p=0.002). The results suggest that exercise in hot environment cause increase in body temperature, perceived exertion and cardiac-vascular changes which are sufficient to elicit immune, hormonal and inflammatory responses. The present results confirm the additive effect of heat stress on the IL-17 response during exercise.  相似文献   

4.
油球藻(Graesiella sp.WBG-1)是一株适合于开放池规模化培养的产油微藻,在室外规模培养过程中常因一种病原真菌(Amoeboaphelidium sp.)的污染严重影响其生长和油脂积累,甚至导致培养失败。本文利用MTT染色法借助光学显微镜对被病原真菌感染的油球藻细胞计数并统计感染率,设置不同温度、光照强度、p H以及通气量等培养条件,研究环境因子对病原真菌感染能力的影响。结果表明:MTT染色法简单易行,可用于油球藻规模培养中病原真菌的检测;温度、光照强度、通气量和p H值均能够显著影响病原真菌的感染能力,高温、高光照强度、弱酸性环境和藻液静止等培养条件不利于病原真菌对油球藻的感染;在温度30℃、光强140μmol·m~(-2)·s~(-1)、通气量1.0 L·min~(-1)和p H 9.0±0.5的培养条件下成功建立了病原真菌感染油球藻的连续传代培养。本研究在实验室内模拟油球藻规模培养中被病原真菌感染的全过程,为深入研究该病原真菌对微藻细胞的感染行为及其感染机制提供了平台。  相似文献   

5.
快速城市化区域城市热岛及其环境效应研究   总被引:2,自引:0,他引:2  
江学顶  夏北成  郭泺 《生态科学》2006,25(2):171-175
以广州为中心的珠江三角洲区域城市化十分迅速,城市热岛对城市生态环境影响极大。城市热岛及其环境效应的研究有利于城市合理规划和可持续发展。利用中尺度模式MM5模拟广州地区的城市热岛效应,模式采用四重嵌套网格,最高水平分辨率为1km。研究通过数值模拟结果与自动气象站观测的气温和ETM+热红外波段反演的地温的对比,表明该方案能准确模拟地表的温度状况和城市热岛的环境效应。研究还表明城市干岛与热岛相伴而生,02时和11时广州热岛强度较小,相对湿度较高,20时热岛强度达到最大,城区相对湿度则最低;因城市热岛的存在,改变了原盛行风向,减弱了风速,且湿地、绿地、河流廊道等景观分割了城市热岛和干岛,增加了其破碎度,调节了城市气候。  相似文献   

6.
doi: 10.1111/j.1741‐2358.2012.00638.x Effects of the head lift exercise on the swallow function: a systematic review Objective: Ageing is associated with modifications in upper oesophageal sphincter function that may be deleterious to deglutition. The head lift exercise (Shaker exercise) is a head‐raising work out aiming to improve the opening of this segment, and ultimately to reduce aspiration. We aimed to review critically the evidence on the effects of this structured intervention programme and to identify gaps to be filled by future research. Material and Methods: We identified published reports addressing the effect of this exercise in increasing the anteroposterior diameter and cross‐sectional area of the deglutitive upper oesophageal sphincter opening or dysphagic symptoms. Results: Nine methodologically heterogeneous studies were included in the review, and the reported effects of the head lift exercise were an increase in the anterior excursion of the larynx and in the anteroposterior diameter of the upper oesophageal sphincter opening, and the elimination of dysphagic symptoms. Conclusion: Further studies including control groups and accounting for potential confounders are needed for a sound assessment of the effectiveness of this technique. The data on the functional results are, however, promising for dysphagia interventions.  相似文献   

7.
The aim of the present study was to evaluate the effect of a 12 week program of physical exercise (PE) on butyrylcholinesterase (BChE) in obese adolescents. This study compared obese adolescents (N = 54) before and after PE, regarding the relative intensity (RI) and activity of different molecular forms (G1, G2, G4 and G1-ALB) of BChE found in plasma. Waist circumference (WC) and lipid profile were also assessed before and after PE. It was shown that before PE, mean plasma BChE activity was significantly higher in obese than in non-obese adolescents and that it was significantly reduced after PE, becoming similar to that found in non-obese adolescents. Lipid profile and WC also changed in response to PE. These results are consistent with studies that found a correlation between BChE and lipid metabolism and suggest that PE may have led to a physiological regularization of plasma BChE activity. Although mean BChE activity of each isoform was significantly reduced by PE, their RI did not change. This is in accordance with a previous suggestion that this proportion is maintained under factors such as obesity, and may therefore be important for BChE functions.  相似文献   

8.
环境条件对植物稳定碳同位素组成的影响   总被引:15,自引:0,他引:15  
植物稳定碳同位素技术是近年兴起的一项快速、可靠的技术。利用稳定碳同位素技术可以揭示碳同化的过程的许多方面的信息。1 3C和1 2 C同位素效应 ,使它们在进行碳循环时发生稳定碳同位素的分馏。植物光合作用过程中CO2 经气孔扩散分差和RUBPCase及PEPCase羧化分馏是造成植物稳定碳同位素比率 (R =1 3C/ 1 2 C)不同于源CO2 中碳同位素比率的主要原因。遗传因素和环境因子同时决定植物碳同位素组成。植物稳定碳同位素技术同时还是古气候重建和预测未来环境变化的理论基础。本文综述了光照、温度、水分、二氧化碳、矿质营养、盐分和大气污染物等环境因素对植物稳定碳同位素组成影响方面的研究进展。  相似文献   

9.
Objective: The objective was to test effects of aerobic exercise training on metabolic syndrome (MetSyn) improvement in response to weight reduction. Research Methods and Procedures: A total of 459 overweight and obese women (age, 49 ± 9 years; BMI, 28 ± 3 kg/m2) were recruited for a baseline examination to test the relationship between cardiorespiratory fitness and metabolic syndrome prevalence; among these, 67 subjects with MetSyn were treated with 14‐week weight‐loss programs, which included low‐calorie diet and aerobic exercise. The MetSyn was defined according to the Examination Committee of Criteria for “Metabolic Syndrome” in Japan. Maximal oxygen uptake (V?o 2max) during a maximal cycling test was measured as an index of cardiorespiratory fitness at baseline and after the intervention. Results: In the baseline examination, age‐ and BMI‐adjusted odds ratios for MetSyn prevalence in the low, middle, and upper thirds of V?o 2max were 1.0 (referent), 0.50 (95% confidence interval, 0.26 to 0.95), and 0.39 (95% confidence interval, 0.14 to 0.96), respectively (linear trend, p = 0.02). The adjusted odds ratios for MetSyn improvement in the two interventions with diet alone and diet plus exercise were 1.0 and 3.68 (95% confidence interval, 1.02 to 17.6; p = 0.04), respectively. Discussion: These results suggest that adding aerobic exercise training to a dietary weight‐reduction program further improves MetSyn (adjusted odds ratio, 3.68) in obese women, compared with diet alone. Further studies on an association between V?o 2max change and MetSyn improvement are needed.  相似文献   

10.
The Chinese black honeybees is an ecotype of the European honeybee that is formed by the natural hybridization of Apis mellifera mellifera and A. m. carnica. It is distributed in nature reserves in North China and has been an important breeding resource for disease resistance and other desirable traits. Compared to the areas outside of reserves, the nature reserves offer significant biodiversity benefits not only to the Chinese black honey bees but also to the other valuable plants and animals. In recent years there has been growing evidence that environmental factors including food choices play an important role in shaping the composition and activity of gut microbiota, which in turn can impact host health. In the previous studies on Chinse black honeybees, little attention has been paid to the diverse population of microbes in the gut that play a vital role in host health. In order to achieve a better understanding on the role of environmental factors in diversity and composition of gut microbiota of honey bees, in the present study, we analyzed the gut bacterial communities of Chinese black honeybees using terminal restriction fragment length polymorphism (T-RFLP). The results showed that the samples from the national nature reserves that are protected and managed so as to preserve and enrich their natural condition and resources for Chinese black honeybees had higher variety and richness of gut bacteria than that collected from unreserved regions that also harbor populations of Chinese black honeybees. The four terminal restriction fragments (T-RFs), 201, 223, 247 and 320 bp, were identified to be the dominant bacteria of Chinese black honeybees. Of which 247 and 320 bp had greater differences between bee groups sampled in different regions and therefore could be used as genetic markers to separate samples collected from the national nature reserves to samples collected from unreserved regions. The results clearly indicate that national nature reserve protects biological diversity and ecological and evolutionary processes which have had a significant influence on the diversity of gut bacteria of Chinese black honeybees. The ubiquity of gut symbiotic bacteria identified in Chinese black honeybee suggests that environmental factors could play an important role in diversity and composition of gut bacteria and warrant further investigation into the functional significance of these gut bacteria for the honeybee health.  相似文献   

11.
Objective: The aim of this study was to investigate the effects of an acute exercise bout in the morning in the post‐absorptive or postprandial state on the glycemic and insulinemic response to three standardized meals throughout the day. It is hypothesized that post‐absorptive exercise enhances fat oxidation rate during exercise and thereafter attenuates the glucose and insulin response to subsequent meals. Research Methods and Procedures: Seven sedentary males with metabolic syndrome (age, 45 ± 11 years; BMI, 34 ± 3 kg/m2) were studied in a crossover design comparing three conditions: no exercise, postprandial and post‐absorptive exercise (at ~60% of the individual V?O2max for 45 minutes). Substrate use was evaluated by indirect calorimetry during exercise. Venous blood samples were taken at regular (30‐ to 60‐minute) intervals throughout the day, and glucose, insulin, and triglyceride concentrations were determined. Results: During exercise, a higher fat oxidation rate was observed in the post‐absorptive than the postprandial state. The glycemic response to a standardized high‐carbohydrate breakfast was lower when exercising after breakfast than when exercising before breakfast. There was no effect of either exercise mode on glucose and insulin response to lunch and supper. Discussion: Post‐absorptive exercise has the advantage of promoting fat use, whereas postprandial exercise can attenuate the glycemic response to breakfast. Neither exercise mode acutely induces improved glucoregulation later during the day. The impact of meal timing on the effects of regular exercise training on glycemic control in this population remains to be studied.  相似文献   

12.
Gonzales, BR, Hagin, V, Guillot, R, Placet, V, and Groslambert, A. Effects of polyester jerseys on psycho-physiological responses during exercise in a hot and moist environment. J Strength Cond Res 25(12): 3432-3438, 2011-With the general acceptance that extreme environments have a detrimental effect on thermoregulation and human performance, the aim of this study was to investigate the influence of 3 polyester jerseys with knits of different sizes on physiological and perceptual responses in trained cyclists during exercise performed in a hot and moist environment. Ten trained male cyclists (mean ± SD, age: 29.1 ± 8 years, height: 177.12 ± 5 cm, body mass: 70.10 ± 6 kg), performed 3 tests of 15 minutes at 150 W on a calibrated home trainer by randomly wearing jerseys with small knits (SK), medium knits, and large knits (LK). While exercising, the jersey and torso skin temperatures, perceived exertion and hotness, and heart rate (HR) were continuously recorded. The major results of this study showed that perceived hotness with LK was significantly lower (p < 0.05) than with SK at minutes 10 (effect size [ES] = 1.18) and 12 (ES = 1.04) of exercise. The torso skin temperature with LK was significantly lower (p < 0.05) than with SK at minute 10 (ES = 0.84) and at minute 14 (ES = 0.81) of exercise, and the LK jersey temperature was significantly lower (p < 0.05) than with SK jerseys at minutes 12 (ES = 0.83) and 14 (ES = 0.90) of exercise. However, no significant difference was found in perceived exertion or HR. These results suggest that the use of polyester jerseys with larger knits could limit the drift of skin temperature and therefore increase the thermal comfort of cyclists during exercise performed in a hot and moist environment. Therefore, coaches are encouraged to take particular care that their athletes wear exercise-appropriate clothing in hot temperatures.  相似文献   

13.

[Purpose]

The purposes of this study is first to examine a positive effect of long term combined exercise including aerobic and resistance exercise on increasing level of serum BDNF, and investigate how aerobic exercise is related to improving BDNF circulation and resistance exercise improves fat oxidation in mid-aged women.

[Methods]

Initially, 30 mid-aged women, according to their exercise preference, was randomly assigned as a non-exercise group (n=7, control group; CG) and exercise group (n=23). Then, 23 exercise participants were divided by aerobic exercise group (n=15, AEG) and combination of aerobic and resistance exercise group (n=8, CEG). Prior to the experiment, all participants’maximal oxygen uptake (VO2max), body composition, and blood factors were measured. Changes (Δ delta value) in body composition, fitness level, and serum BDNF level of the different groups were tested through one way ANOVA.

[Results]

For AEG and CG after 24 weeks, VO2max and high-density lipoprotein cholesterol (HDL-C) were significantly increased. During this period, CEG had significant increase in muscular strength and decrease in triglyceride (TG) total cholesterol (TC)/HDL-C (p=0.013). Continuously, serum BDNF concentration of both AEG and CEG was significantly increased (F=6.328, p=0.001) compared to CG. There, however, was no significant between-group difference.

[Conclusion]

Although there was no difference in serum BDNF level between AEG and CEG, we confirmed that CEG may have a possibility of positive changes in increase of serum BDNF level in mid-aged women.  相似文献   

14.
Immune cells are bioenergetically expensive during activation, which requires tightly regulated control of metabolic pathways. Both low and high glycemic conditions can modulate immune function. States of undernourishment depress the immune system, and in the same way, excessive intake of nutrients, such as an obesity state, compromise its functioning. Multicellular organisms depend on two mechanisms to survive: the regulation and ability to store energy to prevent starvation and the ability to fight against infection. Synergic interactions between metabolism and immunity affect many systems underpinning human health. In a chronic way, the breakdown of glycemic homeostasis in the body can influence cells of the immune system and consequently contribute to the onset of diseases such as type II diabetes, obesity, Alzheimer's, and fat and lean mass loss. On the contrary, exercise, recognized as a primary strategy to control hyperglycemic disorders, also induces a coordinated immune-neuro-endocrine response that acutely modulates cardiovascular, respiratory, and muscle functions and the immune response to exercise is widely dependent on the intensity and volume that may affect an immunodepressive state. These altered immune responses induced by exercise are modulated through the “stress hormones” adrenaline and cortisol, which are a threat to leukocyte metabolism. In this context, carbohydrates appear to have a positive acute response as a strategy to prevent depression of the immune system by maintaining plasma glucose concentrations to meet the energy demand from all systems involved during strenuous exercises. Therefore, herein, we discuss the mechanisms through which exercise may promotes changes on glycemic homeostasis in the metabolism and how it affects immune cell functions under higher or lower glucose conditions.  相似文献   

15.
2008年11月“第十一次全国环境微生物学学术研讨会”在江苏无锡顺利召开, 这次大会充分反映了我国环境微生物学界取得的最新进展。为了展现我国环境微生物学工作者取得的新成果,《微生物学通报》在08年“环境微生物专刊”的基础上, 针对“第十一次全国环境微生物学学术研讨会”组织出版了新一期专刊, 期望该专刊的出版能进一步推动我国环境微生物学相关领域的交流和发展。  相似文献   

16.
In order to determine whether exercise-induced profuse sweating could reduce urinary uric acid excretion, we simulated badminton players training and measured their uric acid in urine, sweat and blood during the training period. Thirteen male volunteers who were well-trained badminton players were recruited in this study. On the first 2 days and the last 2 days of the study period none of the subjects engaged in any intense exercise- or activity-inducing profuse sweat, but they accepted routine training 2 h per day during the middle 3 days. The results show that mean serum urate levels of thirteen volunteers rose significantly on day 4, when the concentrations increased by 18.2% over day 2 (P < 0.05). The mean ten-hour urinary uric acid excretion of seven volunteers on the 3 training days was significantly less at 178.5 micromol/day and 118.3 micromol/day than those on the preceding and subsequent days of the training days, respectively (P < 0.05). Furthermore, for six volunteers, the mean ratio of clearance of uric acid to creatinine was 6.6% on day 2, which significantly decreased to 5.4% on day 4 (P < 0.05). It is concluded profuse sweating exercise results in a decrease of urinary uric acid excretion amounts and leads to increased serum uric acid after the exercise. We suggest that persons who take vigorous exercise or are exposed to hot environments need drinking enough fluids to prevent dehydration and maintain adequate urinary output. People with profuse sweat after rigorous exercise are recommended taking sports drinks containing abundant sodium in order to decrease serum uric acid.  相似文献   

17.
Off-road vehicle driving is considered as main contributor to land degradation in arid regions. This study examined the impact of off-road vehicles (ORV) on soil and vegetation in a natural recreational desert meadow of Raudhat Khuraim, Saudi Arabia. Vegetation canopy cover and plant height away from road tracks were assessed. Also, species density and canopy cover, bare ground cover and soil attributes were assessed in four microhabitats; tracks, inter-tracks, verges, and away from vehicle tracks (undisturbed natural areas). Results show that the cover of forbs and grasses was negatively associated with distance from road verges. It was observed that the height of woody species responded negatively to distance away from tracks. Cover of native species decreased under verge, inter-track and track microhabitats giving more opportunity for weeds to flourish. Bare ground was highest (60.7%) in tracks. ORV impact on soil bulk density was clear with an increase of 38% under tracks compared to soils of undisturbed natural vegetation and a similar decrease in porosity was observed. On the other hand, soil electrical conductivity was significantly higher (5.45 mS cm?1) under disturbance compared to 1.32 mS cm?1 in undisturbed natural vegetation. Organic matter and nitrogen were not affected significantly by ORV disturbance. The results emphasize that managing off-road vehicle driving is essential for conserving native vegetation.  相似文献   

18.
我国是世界上环境污染最为严重的国家之一,环境治理工作日趋重要.随着分子生物学技术的发展,在环境微生物学领域的科研工作者的不懈努力下,我国在环境微生物学方面取得了许多重要成果,使微生物在环境保护中发挥着越来越重要的作用.为了展现国内环境微生物科研工作者取得的最新进展,<微生物学通报>针对"第十次全国环境微生物学术研讨会"组织出版了这期"环境微生物专刊",期望该专刊的出版有助于我国环境微生物学相关领域的交流和发展.  相似文献   

19.
Previous research suggests high impact forces generated during landings contribute to noncontact anterior cruciate ligament (ACL) injuries. In women, neuromuscular differences appear to modify the ability to dissipate landing forces when compared to men. This study examined peak vertical impact forces (F(p)) and rate of force development (RFD) following a 9-week, low-intensity (simple jump-landing-jump tasks) and volume (number of foot contacts per workout) plyometric-based knee ligament injury prevention (KLIP) program. Female subjects were randomly assigned into control (n = 14) and treatment (n = 14) groups. Treatment subjects attended KLIP sessions twice a week for 9 weeks, and control subjects received no intervention. Ground reaction forces (F(p) and RFD) generated during a step-land protocol were assessed at study onset and termination. Significant reductions in F(p) (p = 0.0004) and RFD (p = 0.0205) were observed in the treatment group. Our results indicate that 9 weeks of KLIP training altered landing strategies in women to lower F(p) and RFD. These changes are considered conducive to a reduced risk of knee injury while landing.  相似文献   

20.
Aim This paper describes the distribution pattern (occurrence) of badgers (Meles meles L. 1758) in a Mediterranean mountain area of central Spain, in relation to landscape characteristics and climatic data. We test the fit of the badger occurrence pattern to the niche hypothesis predictions. Location We sampled twenty-four survey plots randomly distributed in the mountains of central Spain (Sierra de Guadarrama, Madrid): ten in the north and fourteen in the south slopes. All habitat types and climatic conditions typical of central Spain can be found. Methods The ocurrence of badgers in the plots were recorded through an exhaustive search of setts and latrines in four different (and evenly spaced) points in each plot. The index of occurrence was made by dividing the number of positive points (badger presence) by the total number of points sampled (four in all plots). Landscape patterns (% type of habitat in each plot) were obtained from detailed maps and climate data from meteorological stations placed in the plot. We analyse the contribution of landscape variables and climate data to explain the differences in badger occurrence through Pearson correlations and fixed one-way ANCOVA with climatic data as fixed factor, vegetation cover as covariates and badger occurrence as response variable. Additionally, we use an one-way ANOVA to check the differences in occurrence between north and south plots with the location of each plot as fixed factor. Results The results indicate that the badger is more abundant in rainy areas of the mountains, and in open landscapes vegetated by ash-tree forests than in closed landscapes vegetated by holm oak forests. In addition, the species is more abundant in the northern plots than in the southern ones. Northern plots were homogeneous areas characterized by their open landscape and wet climate, while southern plots were characterized by their dry climate and closed landscapes. In addition, climate (measured as summer rain) is more determinant than habitat type (holm oak cover) to explain the pattern of badger occurrence. Main conclusions Overall, we consider that the typical Mediterranean landscapes are poor habitats for badgers due to changes in the environmental conditions associated with concomitant changes in food resources. These data support the niche hypothesis to explain the changes in abundance or occurrence close to the edge of the distribution of species, and in particular, in Palearctic species in the Mediterranean area.  相似文献   

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