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排序方式: 共有177条查询结果,搜索用时 15 毫秒
1.
H. G. Thomas M. Scantlebury D. Swanepoel P. W. Bateman N. C. Bennett 《Die Naturwissenschaften》2013,100(11):1023-1030
Sociality in mole rats has been suggested to have evolved as a response to the widely dispersed food resources and the limited burrowing opportunities that result from sporadic rainfall events. In the most arid regions, individual foraging efficiency is reduced, and energetic constraints increase. In this study, we investigate seasonal differences in burrow architecture of the social Cryptomys hottentotus hottentotus in a mesic region. We describe burrow geometry in response to seasonal weather conditions for two seasons (wet and dry). Interactions occurred between seasons and colony size for the size of the burrow systems, but not the shape of the burrow systems. The fractal dimension values of the burrow systems did not differ between seasons. Thus, the burrow complexity was dependent upon the number of mole rats present in the social group. 相似文献
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This scoping review provides a summary of research findings on social support dynamics in the wake of disasters that occurred on the continent of Australia and Oceania between 1983 and 2013. Forty-one studies, quantitative and qualitative, were summarised, investigating different facets of post-disaster supportive interactions. All inquiries assessed disasters resulting from natural hazards, with the majority of them conducted following events in Australia and New Zealand. The review revealed similar patterns of post-disaster social support dynamics that routinely unfold after disastrous incidents all over the world. Consistent with the disaster mental health literature, the documentation of social support mobilisation and social support deterioration processes was common. Salutary direct effects of supportive behaviours on post-disaster psychological distress were also highly evident. Most studies, however, posed research questions or hypotheses that lacked empirical or theoretical grounding. In conclusion, the review offers several recommendations on how to advance research on post-disaster social support. 相似文献
3.
Jesse H. Bennett A. Clyde Hill David M. Gates 《Journal of the Air & Waste Management Association (1995)》2013,63(11):957-962
A model simulating pollutant exchange with isolated leaves that integrates factors which have been found to be important in regulating pollutant uptake by leaves is presented. The model is patterned after an electrical analogue simulator and was designed to emphasize the effects of pollutant and leaf properties on the process. The article discusses the relative significance of factors affecting gas transfer, sorption of pollutants by leaf surfaces, and pollutant solubility and fate on the uptake process. Data is presented showing uptake of ozone by exposed mesophyll and several epidermal surfaces chosen for their different surface characteristics. The model was used to derive a mathematical expression for the exchange process which was rearranged to define internal (average) pollutant solute concentration in terms of external concentration, leaf and boundary layer diffusion resistance, surface sorption and pollutant solubility. The importance of estimating internal solute concentration is discussed. 相似文献
4.
Jesse H. Bennett A. Clyde Hill 《Journal of the Air & Waste Management Association (1995)》2013,63(3):203-206
Concentration profiles for hydrogen fluoride(HF), sulfur dioxide(SO2), ozone (O3), nitrogen dioxide(NO2), and nitric oxide(NO) generated in a standardized alfalfa canopy are presented. Wind, light, temperature, and carbon dioxide(CO2) profiles, canopy pollutant uptake rates, and canopy structural data are also given. Canopy pollutant concentration profile characteristics were studied to evaluate the relative potentials for major air pollutants to penetrate into canopies. The study was conducted in an environmental growth chamber equipped to control automatically environmental conditions and monitor continuously gas exchange rates. HF, SO2, and NO2 profiles suggested that these gases were removed efficiently by the upper portion of the canopy as well as by the immediate subsurface vegetation. The steady state HF profile showed the greatest displacement within the canopy. The NO profile was displaced the least. The uptake rate of NO by plants was apparently too slow in comparison with gas transport and mixing within the canopy to affect the internal profile substantially. O3 appeared to be readily deposited on the surface tissues, but the deeper tissues in the canopy had less effect on the concentration profile. Data are also presented to show the relationship between NO2 concentration within the canopy and changes in the air concentration above the vegetation. The results indicated that gas transport between the atmosphere and canopy interior was rapid. The data presented should be of current interest to agriculturists, researchers, administrators, and environmental planners concerned with effects of air pollutants on plants and on the fate of pollutants in the microenvironment. 相似文献
5.
Kenneth J. Tobin Marvin E. Bennett 《Journal of the American Water Resources Association》2017,53(3):593-604
Historically, many watershed studies have been based on using the streamflow flux, typically from a single gauge at the basin's outlet, to support calibration. In this setting, there is great potential for equifinality of parameters during the optimization process, especially for parameters that are not directly related to streamflow. Therefore, some of the optimal parameter values achieved during the autocalibration process may be physically unrealistic. In recent decades a vast array of data from land surface models and remote sensing platforms can help to constrain hydrologic fluxes such as evapotranspiration (ET). While the spatial resolution of these ancillary datasets varies, the continuous spatial coverage of these gridded datasets provides flux measurements across the entire basin, in stark contrast to point‐based streamflow data. This study uses Global Land Evaporation: the Amsterdam Model data to constrain Soil and Water Assessment Tool parameter values associated with ET to a more physically realistic range. The study area is the Little Washita River Experimental Watershed, in southern Oklahoma. Traditional objective metrics such as the Nash‐Sutcliffe coefficients record no performance improvement after application of this method. However, there is a dramatic increase in the number of days with receding flow where simulations match observed streamflow. 相似文献
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Summary Extensive field and laboratory studies show that Damaraland mole-rats, like naked mole-rats, have an extreme form of vertebrate sociality. Colonies usually contain 2 reproductives and up to 39 non-breeding siblings, 90% of whom live a socially-induced lifetime of sterility; they remain in the natal colony, forage for food, defend the colony and care for successive litters. Although there is heightened dispersal following good rainfall, the majority of adult non-reproductives remain in their natal colony and failure to disperse is not directly attributable to habitat saturation or unfavourable soil conditions. A major dispersal event follows the death of a reproductive. Differences in colony cohesion, ethology and the hormonal profiles of non-reproductive animals suggests that eusociality evolved along different pathways in these two phylogenetically divergent genera of the Bathyergidae. 相似文献
8.
P R Fresquez J R Biggs K D Bennett D H Kraig M A Mullen J K Ferenbaugh 《Journal of environmental science and health. Part. B》1999,34(5):901-915
This paper summarizes radionuclide concentrations (3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p < 0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% of LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y-1 (2.2 microSv y-1), deer bone = 3.8 mrem y-1 (38 microSv y-1), elk muscle = 0.12 mrem y-1 (1.2 microSv y-1), and elk bone = 1.7 mrem y-1 (17 microSv y-1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y-1 (1000 microSv y-1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E-06, which is far below the Environmental Protection Agency upper level guideline of 1E-04. 相似文献
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