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991.
Jiansheng Yan Keith R. Smith 《Journal of the American Water Resources Association》1994,30(5):879-890
ABSTRACT: The unique characteristics of the hydrogeologic system of south Florida (flat topography, sandy soils, high water table, and highly developed canal system) cause significant interactions between ground water and surface water systems. Interaction processes involve infiltration, evapotranspiration (ET), runoff, and exchange of flow (seepage) between streams and aquifers. These interaction processes cannot be accurately simulated by either a surface water model or a ground water model alone because surface water models generally oversimplify ground water movement and ground water models generally oversimplify surface water movement. Estimates of the many components of flow between surface water and ground water (such as recharge and ET) made by the two types of models are often inconsistent. The inconsistencies are the result of differences in the calibration components and the model structures, and can affect the confidence level of the model application. In order to improve model results, a framework for developing a model which integrates a surface water model and a ground water model is presented. Dade County, Florida, is used as an example in developing the concepts of the integrated model. The conceptual model is based on the need to evaluate water supply management options involving the conjunctive use of surface water and groundwater, as well as the evaluation of the impacts of proposed wellfields. The mathematical structure of the integrated model is based on the South Florida Water Management Model (SFWMM) (MacVicar et al., 1984) and A Modular Three-Dimensional Finite-Difference Groundwater Flow Model (MODFLOW) (McDonald and Harbaugh, 1988). 相似文献
992.
Helen Lawton Smith 《Journal of Environmental Planning and Management》1988,31(2):123-126
The growth of advanced technology industry in Oxfordshire has mainly been generated from within the county. The increasing number of firms has attracted the interest of numerous property developers wishing to build science parks and business parks in and around Oxford. This is where growth has been highest, but where there are policies of restraint and to protect the green belt. 相似文献
993.
994.
Hans Pohl Benjamin Wipfler David Grimaldi Felix Beckmann Rolf G. Beutel 《Die Naturwissenschaften》2010,97(9):855-859
Fossilization in amber is unique in preserving specimens with microscopic fidelity; however, arthropod inclusions are rarely
examined beyond the exoskeleton as this requires destructive sampling when traditional techniques are used. We report the
first complete, digital 3D, non-destructive reconstruction of the anatomy of an insect fossil, a specimen of †Mengea tertiaria embedded in a 42-Ma Baltic amber. This was made possible using Synchrotron μ-CT. The species belongs to the stem group of
the phylogenetically enigmatic and extremely specialized Strepsiptera. Most internal structures of the fossil are preserved,
but small parts of the lumen had decayed due to incomplete infiltration of the resin. Data on internal organs provided additional
information for resolving phylogenetic relationships. A sister group relationship between †Mengea and all extant lineages of the group was confirmed with characters previously not accessible. The newly gained information
also yielded some insights in the biology of †Mengea and the early evolutionary history of Strepsiptera. The technique has a tremendous potential for a more accurate interpretation
of diverse fossil arthropods preserved in ambers from 130 Ma to the present. 相似文献
995.
Coprolites (fossilized feces) preserve a wide range of biogenic components, from bacteria and spores to a variety of vertebrate tissues. Two coprolites from the Calvert Cliffs outcrop belt (Miocene-aged Chesapeake Group), MD, USA, preserve shark tooth impressions in the form of partial dental arcades. The specimens are the first known coprolites to preserve vertebrate tooth marks. They provide another example of trace fossils providing evidence of prehistoric animal behaviors that cannot be directly approached through the study of body fossils. Shark behaviors that could account for these impressions include: (1) aborted coprophagy, (2) benthic or nektonic exploration, or (3) predation. 相似文献
996.
The underlying principles of water’s equation of state (ES) and its associated pressure–volume–temperature (PVT) relationship, are employed for the purpose of producing “ultra-high” pressure within the closed volume of a thick-walled metal tube, resulting in a new and innovative hydroforming process. The process, called “Closed-Volume Thermally Activated” (CVTA) Tube Hydroforming, involves conducting a high level of heat through the walls of a thick-walled, metallic, water-containing closed tube. Experimental validation of the concept is presented, and potential applications are discussed. This work represents a break-through in manufacturing technology, which, when further developed, is expected to enable manufacturers to expand significantly their manufacturing capability. 相似文献
997.
Raia-Silvia Massad Benjamin Loubet Andre Tuzet Herv Autret Pierre Cellier 《Agriculture, ecosystems & environment》2009,133(3-4):170
The plant can be a source or a sink of ammonia (NH3) depending on its nitrogen (N) supply, metabolism and on the background atmospheric concentrations. Thus plants play a major role in regulating atmospheric NH3 concentrations. For a better understanding of the factors influencing the NH3 stomatal compensation point, it is important to analyse the dynamics of leaf NH3 fluxes. The relationship between the leaf NH3 fluxes and the leaf apoplast ammonium and nitrate concentrations, N nutrition and the light and dark periods was studied here.We designed an experiment to quantitatively assess leaf-atmosphere NH3 exchange and the stomatal compensation point and to identify the main factors affecting the variation of NH3 fluxes in oilseed rape. We tested day and night dynamics as well as the effect of five different N treatments. Two experimental methods were used: a dynamic open flux chamber and extraction of the apoplastic solution.Chamber measurements showed that there was a good correlation between plant NH3 fluxes and water fluxes. Compensation points were calculated by two different methods and ranged between 0.8 and 12.2 μg m−3 NH3 (at 20 °C) for the different N treatments. Apoplastic solution measurements showed that there was no significant differences in the apoplastic NH4+ concentrations ([NH4+]apo) extracted in dark and light periods for the same N treatment. Statistical analysis also showed that [NH4+]apo was correlated with [NH4+] in the nutrient solution and weakly correlated with [NO3−]. Apoplast NH4+ concentrations ranged between 0.1 and 2.1 mM, bulk tissue NH4+ concentrations between 3.9 and 6.6 mM and xylem concentrations between 2.4 and 6.1 mM depending on the N supply.Calculated NH3 emission potential from the extraction measurements were over-estimated when compared with the value calculated from chamber measurements. Errors related to chamber measurements included separation of the cuticular and stomatal fluxes and the calculation of total resistance to NH3 exchange. Errors related to the extraction measurements included assessing the amount of cytoplasmic contamination. We do not have another method to assess the NH3 stomatal compensation point and the choice between these two measurement techniques should depend on the scales to which the measurements apply and the processes to be studied. 相似文献
998.
In many social taxa, reproductively dominant individuals sometimes use aggression to secure and maintain reproductive status.
In the social insects, queen aggression towards subordinate individuals or workers has been documented and is predicted to
occur only in species with a small colony size and a low level of queen–worker dimorphism. We report queen aggression towards
reproductive workers in the ant species Aphaenogaster cockerelli, a species with a relatively large colony size and a high level of reproductive dimorphism. Through analysis of cuticular
hydrocarbon profiles, we show that queens are aggressive only to reproductively active workers. Non-reproductive workers treated
with a hydrocarbon typical for reproductives are attacked by workers but not by queens, which suggests different ways of recognition.
We provide possible explanations of why queen aggression is observed in this species. 相似文献
999.
Schwebel DC Ball KK Severson J Barton BK Rizzo M Viamonte SM 《Journal of Safety Research》2007,38(5):501-509
INTRODUCTION: Motor-vehicle crashes kill roughly 4,500 American adults over the age of 75 annually. Among younger adults, one behavioral factor consistently linked to risky driving is personality, but this predictor has been overshadowed by research on cognitive, perceptual, and motor processes among older drivers. METHOD: In this study, a sample of 101 licensed drivers, all age 75 and over, were recruited to complete self-report measures on personality, temperament, and driving history. Participants also completed a virtual environment (VE) course designed to assess risk-taking driving behavior. State records of motor-vehicle crashes were collected. RESULTS: Results suggest both a sensation-seeking personality and an undercontrolled temperament are related to risky driving among older adults. Sensation-seeking was particularly related to history of violations and tickets, while temperamental control was more broadly related to a number of risky driving measures. Methodological and crash prevention issues are discussed. 相似文献
1000.
High bat (Chiroptera) diversity in the Early Eocene of India 总被引:1,自引:0,他引:1
Smith T Rana RS Missiaen P Rose KD Sahni A Singh H Singh L 《Die Naturwissenschaften》2007,94(12):1003-1009
The geographic origin of bats is still unknown, and fossils of earliest bats are rare and poorly diversified, with, maybe,
the exception of Europe. The earliest bats are recorded from the Early Eocene of North America, Europe, North Africa and Australia
where they seem to appear suddenly and simultaneously. Until now, the oldest record in Asia was from the Middle Eocene. In
this paper, we report the discovery of the oldest bat fauna of Asia dating from the Early Eocene of the Cambay Formation at
Vastan Lignite Mine in Western India. The fossil taxa are described on the basis of well-preserved fragments of dentaries
and lower teeth. The fauna is highly diversified and is represented by seven species belonging to seven genera and at least
four families. Two genera and five species are new. Three species exhibit very primitive dental characters, whereas four others
indicate more advanced states. Unexpectedly, this fauna presents strong affinities with the European faunas from the French
Paris Basin and the German Messel locality. This could result from the limited fossil record of bats in Asia, but could also
suggest new palaeobiogeographic scenarios involving the relative position of India during the Early Eocene. 相似文献