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81.
Robert?W.?ElnerEmail author Peter?G.?Beninger Daniel?L.?Jackson Tracy?M.?Potter 《Marine Biology》2005,146(6):1223-1234
82.
We used multiple and logistic regression analysis to study the breeding-area requirements of 10 species of grassland and early-successional birds at 90 grassland-barren sites in Maine. The incidence of six of the species was clearly sensitive to the area of grassland. Upland Sandpipers, the species with the largest area requirements, were infrequent at sites of less than 50 ha and reached 50% incidence at those of about 200 ha. Grasshopper Sparrows reached 50% incidence at about 100 ha, Vesper Sparrows at about 20 ha, and Savannah Sparrows at about 10 ha. Incidence for three edge species, Brown Thrasher, Common Yellowthroat, and Song Sparrow, was negatively correlated with open area, and incidence for Field Sparrows was not strongly influenced by grassland size. These results indicate that grasslands need to be approximately 200 ha in area if they are to be likely to support a diverse grass land bird fauna. However, large grasslands or grassland-barrens are rare; random samples indicated that in Maine only 1% of hayfields and only 8% of grassland-barrens were more than 64 ha in area. Conservation efforts seeking to protect habitat for rare grassland birds need to consider sites of at least 100 ha—and preferably 200 ha—in size, and these are notably rare in Maine and probably throughout New England and eastern North America. Airports provide some of the last extensive patches of grassland habitat in the northeast. To maintain viable populations of area-sensitive grassland birds, management of these sites for nesting birds will become increasingly important. 相似文献
83.
Many organizations are blurring the boundaries between work and nonwork through practices such as flextime, telecommuting, and on‐site day‐cares. Such integration of work and nonwork is purported to help employees find the seemingly elusive “work‐life balance.” Scholarly investigations of this issue have increased in number, but a standard measure of work–nonwork boundary strength has yet to emerge. The purpose of this research is to explore the boundary strength construct through the process of measure validation. In Study 1, data were collected from students (N = 162) to pilot test the measure. Study 2 was a longitudinal field study in which data were collected from employees of Canadian organizations (Survey 1: N = 793; Matched data for Surveys 1 & 2: N = 205). Confirmatory factor analyses supported the hypothesized two‐factor structure of the work–nonwork boundary strength measure, confirming the importance of differentiating boundary strength at home (BSH) and boundary strength at work (BSW). Longitudinal analyses confirmed the structural invariance of the measure and revealed that boundary strengths are relatively stable over a period of 1 year. Role identification was related to boundary strength at home only. Weak boundaries, both at home and at work, were associated with high inter‐role conflict. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
84.
Melvin W. First Frederick J. Viles Jr. 《Journal of the Air & Waste Management Association (1995)》2013,63(3):122-127
Multistage gas absorption of 1–50% nitric oxide, nitrogen dioxide, and nitrogen tetraoxide from air with water or caustic solutions can produce colorless stack discharges. The rate at which NO is oxidized to No2 in the gas phase and the solubility rate of No2 in water or solution are highly concentration dependent so that reductions of stack gas concentrations of nitrogen oxides below approximately 200 ppm appear to be impractical. High efficiency absorption combined with elevated discharge of the cleaned, colorless gases is an acceptable method of air pollution control for many troublesome operations. Experiences in the fields of rocketry and nuclear energy are cited. Engineering modifications of metal pickling operations have been found especially helpful in producing effective control at an acceptable cost. 相似文献
85.
Lindsey Swierk Matthew Ridgway Tracy Langkilde 《Behavioral ecology and sociobiology》2012,66(7):1033-1043
Female choice can powerfully influence the evolution of male phenotypes. In territorial species, it is challenging to determine the targets of female choice because male traits (e.g., behavior and morphology) are often correlated with territory. We sought to elucidate if and how females specifically evaluate male traits in a territorial species. In this study, we presented female fence lizards, Sceloporus undulatus, with two potential mates to examine mate choice in the absence of territory cues. Females associated more with males possessing better body condition, longer heads, and wider throat badges, and that performed more shudder behavior, which females responded to by approaching shuddering males and performing push-ups. A post hoc decision tree analysis suggests that the strongest predictor of female association was an overall quality index that incorporates all of these traits, rather than individual traits. Male snout–vent length, head width, abdominal badge width, and push-up behavior did not affect female association. Further research on why these traits, which are known to correlate with fitness, do not appear to be used by females when selecting mates would improve our understanding of the evolution of male traits. Our study reveals that females of this territorial species possess the ability to use multiple male traits interactively to make fitness-relevant mate choice decisions in the absence of direct territory cues. 相似文献
86.
Sara T. Savage Joy Lawrence Tracy Katz Rebecca C. Stearns Brent A. Coull 《Journal of the Air & Waste Management Association (1995)》2013,63(9):1088-1097
Abstract Inhalation exposure to urban air particles is known to increase morbidity in humans and animals. Our group utilizes the Harvard/U.S. Environmental Protection Agency Ambient Particle Concentrator (HAPC) to generate concentrated aerosols of outdoor air particles for experimental exposures. We have reported increased pathologic responses to inhalation of concentrated urban air particles and identified silicon (as silicate) as an element associated with many of these responses. Using silicate-rich Mt. St. Helen’s volcanic ash (MSHA), we exposed three groups of Sprague-Dawley rats by inhalation for 6 hr to filtered air, MSHA, or MSHA passed though the HAPC. Twenty-four hours following exposure, bronchoalveolar lavage was performed to assess total cell count, differential cell count, protein, lactate dehydrogenase, and n-β[notdef]glucosaminidase levels. Peripheral blood was examined for packed cell volume, total protein, total white cells, and differential cell count. Morphologic studies localized particles in the lung and assessed pulmonary vasculature. No significant differences were observed among any of the groups in any parameter measured including morpho-metric analysis of pulmonary vasoconstriction. Scanning electron microscopy and X-ray analysis identified particles as silicates typical of MSHA throughout the lung. These findings suggest that particles passing through the HAPC have no change in their toxic potential in an exposure setting where particle deposition in the lung has occurred. 相似文献
87.
David Leith Melvin W. First Henry Feldman 《Journal of the Air & Waste Management Association (1995)》2013,63(7):636-642
Pulse-jet filter cleaning is ineffective to the extent that collected dust redeposits rather than falls to the hopper. Dust tracer techniques were used to measure the amount of redeposition in a pilot scale pulse-jet filter. A mathematical model based on experimental results was developed to describe dust transfer from bag to bag, redeposition on the pulsed bag itself, and migration to the dust hopper. Dust redeposition upon the pulsed bag increased markedly with increasing filtration velocity, whereas migration and redeposition on bags adjacent to the pulsed bag decreased. For high velocity pulse-jet filters to operate at lowest possible pressure drop, filter cake redeposition must be minimized. 相似文献
88.
Successful control of some contaminant sources is extremely difficult to achieve technically and there remains a need for more information specific to control procedures. The cost of air cleaning equipment installations can be exceedingly high depending upon the performance standards to be satisfied and the physical and chemical characteristics of the contaminants. Control of emissions from the foundry cupola, the steel mill, metal refining operations, coal burning utilities, and incinerators still presents imposing cost and operational and performance problems—despite the technological progress made in recent years. The interrelationship of the source, the degree of control necessary, the equipment available to do the job, and the costs are discussed. 相似文献
89.
Melvin W. First 《Journal of the Air & Waste Management Association (1995)》2013,63(12):1192-1194
New kinds of fabric filtration devices are reviewed in this paper. The industry is on the threshold of a period of innovation and development in this field which should see the advancement of new concepts of the way filters function. 相似文献
90.