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231.
Lelia K Lawson Elizabeth M Crown Mark Y Ackerman J Douglas Dale 《International journal of occupational safety and ergonomics》2004,10(3):227-238
Wildland firefighters work in unfavourable environments involving both heat and moisture. Moisture in clothing systems worn by wildland firefighters may increase or decrease heat transfer, depending on its source and location in the clothing system, location on the body, timing of application and degree of sorption. In this experiment, 4 outerwear/underwear combinations were exposed to 1 of 5 different conditions varying on amount and location of moisture. The fabric systems were then exposed to either a high-heat-flux flame exposure (83 kW/m(2)) or a low-heat-flux radiant exposure (10 kW/m(2)). Under high-heat-flux flame exposures, external moisture tended to decrease heat transfer through the fabric systems, while internal moisture tended to increase heat transfer. Under low-heat-flux radiant exposures, internal moisture decreased heat transfer through the fabric systems. The nature and extent of such differences was fabric dependent. Implications for test protocol development are discussed. 相似文献
232.
Peter D. Lattin Parker J. Wigington Thomas J. Moser Barbara E. Peniston Dale R. Lindeman Doug R. Getter 《Journal of the American Water Resources Association》2004,40(1):215-227
ABSTRACT: This paper compares approaches to quantifying land cover/land use (LCLU) in riparian corridors of 23 watersheds in Oregon's Willamette Valley using color infrared aerial photography (AP) and Thematic Mapper (TM) imagery. For each imagery source, LCLU adjacent to stream networks were quantified across a range of lateral and longitudinal scales. Single‐date AP data had higher LCLU class accuracies than the multi‐date TM data, except for row crops. Correlations among LCLU classes for the two imagery sources increased with increased spatial extent. In general, LCLU proportions for AP and TM differed, but lateral/longitudinal patterns were similar. An aggregated vegetation class comprised of forest, shrub/scrub, and grass/forb was strongly associated with a fish index of biotic integrity (IBI) for both AP and TM data, although AP correlations were higher. Highest fish IBI correlations for both data sources were with the aggregated vegetation class close to the stream and for the longest longitudinal scales. The row crop class was strongly associated with stream nitrate for both data sources, although correlations for the TM data were higher. Stream nitrate correlations were strongest for the widest lateral and longest longitudinal scales. Overall, both single‐date AP and multi‐date TM imagery appear to have potential for use in estimating indicators of stream ecological condition. 相似文献
233.
Dale M. Robertson 《Journal of the American Water Resources Association》2003,39(5):1281-1308
ABSTRACT: Various temporal sampling strategies are used to monitor water quality in small streams. To determine how various strategies influence the estimated water quality, frequently collected water quality data from eight small streams (14 to 110 km2) in Wisconsin were systematically subsampled to simulate typically used strategies. These subsets of data were then used to estimate mean, median, and maximum concentrations, and with continuous daily flows used to estimate annual loads (using the regression method) and volumetrically weighted mean concentrations. For each strategy, accuracy and precision in each summary statistic were evaluated by comparison with concentrations and loads of total phosphorus and suspended sediment estimated from all available data. The most effective sampling strategy depends on the statistic of interest and study duration. For mean and median concentrations, the most frequent fixed period sampling economically feasible is best. For maximum concentrations, any strategy with samples at or prior to peak flow is best. The best sampling strategy to estimate loads depends on the study duration. For one‐year studies, fixed period monthly sampling supplemented with storm chasing was best, even though loads were overestimated by 25 to 50 percent. For two to three‐year load studies and estimating volumetrically weighted mean concentrations, fixed period semimonthly sampling was best. 相似文献
234.
ABSTRACT. Beginning of month water temperature profiles are estimated for each lake. These water temperature profiles along with surface water temperatures are used to determine the effects of thermal expansion and contraction of water on the net basin supply values obtained from water balance studies using end of month lake levels. It is demonstrated that net basin supply values (equivalent to precipitation on the lake minus the evaporation from the lake plus the runoff into the lake) obtained from water balance studies without accounting for the thermal expansion and contraction of water may be in error by as much as 100 percent during some months for each lake. 相似文献
235.
Kevin?J.?McGrawEmail author James?Dale Emiko?A.?Mackillop 《Behavioral ecology and sociobiology》2003,53(2):116-122
Evolutionary biologists have shown much recent interest in the costliness and signal content of colorful plumage displays in birds. Although many studies suggest that both carotenoid- and structurally-based plumage colors are condition-dependent indicators of health and nutritional state at the time ornamental feathers are grown, there is little experimental evidence supporting the idea that melanin pigmentation is a reliable signal of condition during molt. Instead, melanin-based ornamental coloration often reveals the competitive ability and dominance of individuals throughout the year. However, this work does not indicate which proximate environmental factors shape the expression of melanin pigmentation at the time of feather growth. Because of the link between melanin coloration and the social environment, it is possible that the development of brightly colored plumage may be associated with aggressive social interactions during feather molt. Here, we show that melanin-based ornamental coloration in male house sparrows (Passer domesticus) is correlated with the degree to which individuals interact aggressively with conspecifics during molt. Males that were dominant (beta, but not alpha) within captive social groups during molt grew larger badges than subordinates. Groups of males that had higher rates of aggression during molt grew larger badges than less aggressive triads. To our knowledge, this is the first demonstration that melanin pigmentation and plumage-based status badges are related to the competitive history of individuals during feather development. By coupling badge size directly with aggressive experiences during molt, birds can use their status signal to honestly indicate their likelihood of winning agonistic encounters throughout the year. 相似文献
236.
Beverly A. Dale Tracy B. Perry Karen A. Holbrook Emily F. Hamilton Vyta Senikas 《黑龙江环境通报》1986,6(1):37-44
This paper describes a method for biochemical analysis of proteins from fetal skin biopsy samples. The method has wide potential application for diagnosis of disorders with a known protein abnormality detectable by protein staining or a specific antibody. Analysis requires a single 1 mm biopsy, is rapid (2 days) and extremely sensitive. In the present study, fetal skin biopsies from normal fetuses and a fetus at risk for lamellar ichthyosis were obtained. The epidermis or hairs with attached follicular cells were dissected from the remaining skin. Proteins were extracted and separated by SDS-polyacrylamide gel electrophoresis. Proteins from duplicate gels were transferred to nitrocellulose and immunostained for the acidic and basic keratins and for the keratin filament associated protein, filaggrin, using monoclonal antibodies. All samples contained keratins typical of fetal epidermis at 20 weeks gestation. Presence of filaggrin is variable at this age and depends on the presence of keratinized cells of hair canals. No keratin abnormalities in the fetus at risk for lamellar ichthyosis were detected, however, in one presumably normal biopsy, an abnormally low proportion of the 67 kd keratin and the presence of follicular keratins were evident. These results demonstrate that biochemical analysis of fetal biopsies is possible, thus increasing the diagnostic potential of the fetal biopsy procedure for disorders in which a known protein or antigen is altered in utero. 相似文献
237.
Wind Characteristics of Mesquite Streets in the Northern Chihuahuan Desert, New Mexico, USA 总被引:2,自引:0,他引:2
Past research has shown that the most important areas for active sand movement in the northern part of the Chihuahuan Desert
are mesquite-dominated desert ecosystems possessing sandy soil texture. The most active sand movement in the mesquite-dominated
ecosystems has been shown to take place on elongated bare soil patches referred to as “streets”. Aerodynamic properties of
mesquite streets eroded by wind should be included in explaining how mesquite streets are more emissive sand sources than
surrounding desert land. To understand the effects of wind properties, we measured them at two flat mesquite sites having
highly similar soil textures but very different configurations of mesquite. The differences in wind properties at the two
sites were caused by differences of size, orientation, and porosity of the mesquite, along with the presence of mesquite coppice
dunes (sand dunes stabilized by mesquites growing in the dune and on its surface) found only at one of the two sites. Wind
direction, u* (friction velocity), z0 (aerodynamic roughness height) and D (zero plane displacement height) were estimated for 15-m tower and 3-m mast data. These aerodynamic data allowed us to distinguish
five categories with differing potentials for sediment transport. Sediment transport for the five categories varied from unrestricted,
free transport to virtually no transport caused by vegetation protection from wind forces. In addition, “steering” of winds
below the level of the tops of mesquite bushes and coppice dunes allowed longer parallel wind durations and increased wind
erosion for streets that aligned roughly SW–NE.
U.S. Government right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged. 相似文献
238.
Sperm traits often show extreme variation both between and within species. Between-species variation may often be interpreted
in the context of a sperm competition theory, but within-species variation has remained unexplained. Previous studies on intraspecific
variation in sperm traits have focused on a limited set of variables and may have failed to explain observed variation because
of potential trade-offs between different sperm traits. We report on variation in number, size, motility and longevity of
sperm in the frog Crinia georgiana, a species where sperm competition is common. We found intrapopulation variation in sperm size and motility and interpopulation
variation in relative sperm number and size. When we combined relative sperm number and size into one variable, and motility
and longevity into another, we found significant interpopulation variation in these variables as well. We also detected considerable
intra- and significant interpopulation variation in cumulative sperm quality, a combination of all four sperm traits. Furthermore,
a significant effect of the interaction between population origin and male size on sperm characteristics indicated interpopulation
variation in the strength of selection acting on sperm traits of males adopting different mating strategies. We discuss heterogeneity
in the reproductive environment, a complex genetic background in the determination of sperm characteristics and varying levels
of developmental noise as potential contributors to the observed variation in sperm traits. 相似文献
239.
Numerous challenges face those involved with developing a coordinated and consistent approach to cleaning up the US Department
of Energy’s (DOE) Hanford Site in southeastern Washington. These challenges are much greater than those encountered when the
site was selected and the world’s first nuclear complex was developed almost 50 years ago. This article reviews Hanford’s
history, operations, waste storage/disposal activities, environmental monitoring, and today’s approach to characterize and
clean up Hanford under a Federal Facility Agreement and Consent Order, signed by DOE, the Environmental Protection Agency,
and the Washington Sate Department of Ecology. Although cleanup of defense-related waste at Hanford holds many positive benefits,
negative features include high costs to the US taxpayer, numerous uncertainties concerning the technologies to be employed
and the risks involved, and the high probability that special interest groups and activists at large will never be completely
satisfied. Issues concerning future use of the site, whether to protect and preserve its natural features or open it to public
exploitation, remain to be resolved. 相似文献
240.