5,625 research outputs found
Seasonal Emergence Patterns of Black Flies (Diptera: Simuliidae) in Northwestern Pennsylvania
A two-year emergence trap study of black flies at four sites in northwestern Pennsylvania yielded 1%3 individuals of nine species. The collections included Prosimulium mixtum, P. jU5cum, Stegapterna mutata, Simulium aureum, S. excisum (recorded for the first time from Pennsylvania), S. gauldingi, S. sp. nr. innacens, S. vittatum, and S. tuberasum. Species richness for all sites peaked during May. Emergence collections below a sewage plant effluent outfall represented fewer individuals and species than collections above the effluent outfall. Chromosomal analysis of supplementary larval collections revealed the IIIL-l and IS-7 sibling species of S. vittatum and the FG sibling of S. tuberasum
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Testing Reliable Distributed Applications Through Simulated Events
There are many distributed applications that incorporate application-specific reliability algorithms which operate on top of general purpose networking, operating system and programming language facilities. We present a framework for application-level reliability testing suitable for a wide range of distributed applications, and describe how we've applied it to one particular application, Mercury, a distributed, multi-user programming environment
Wildlife in Airport Environments: Chapter 8 Identification and Management of Wildlife Food Resources at Airports
Wildlife use airport habitats for a variety of reasons, including breeding, raising young, resting, taking refuge from predators, and locating sources of water. But the chief motivation for most individuals to encroach on airports is food. Depending on the specific habitat types present and habitat management strategies employed, airports can harbor large numbers of small mammals, insects, earthworms, and palatable vegetation that attract many species hazardous to aircraft. Often the best way to reduce populations of hazardous wildlife at airports is to determine which sources of food are being used, and then remove or modify those foods to make them less attractive (Washburn et al. 2011). Fortunately, the science of wildlife ecology and management has a long and productive history of research on wildlife food habits and foraging strategies, and the applied nature of most food habit studies conducted in airport environments facilitates straightforward specialization of investigational techniques. In this chapter we (1) discuss in more detail food resources as a primary motivation for wildlife use of airport properties, (2) consider some established principles of wildlife food habits and foraging strategies that affect airport wildlife management, (3) review techniques used to investigate wildlife food habits and identify those most useful for airports, (4) discuss methods for eliminating or modifying some preferred foods at airports, and (5) briefly consider future research needs
Plasma Electron Beam Welder for Space Vehicles Final Report
Feasibility of developing plasma electron beam welding system for earth orbiting vehicl
Impact of the human footprint on anthropogenic mortality of North American reptiles
Human activities frequently result in reptile mortality, but how direct anthropogenic mortality compares to natural morality has not been thoroughly investigated. There has also been a limited examination of how anthropogenic reptile mortality changes as a function of the human footprint. We conducted a synthesis of causespecific North American reptile mortality studies based on telemetry, documenting 550 mortalities of known cause among 2461 monitored individuals in 57 studies. Overall 78% of mortality was the result of direct natural causes, whereas 22% was directly caused by humans. The single largest source of mortality was predation, accounting for 62% of mortality overall. Anthropogenic mortality did not increase with the human footprint or with species body mass, though predation mortality increased with decreasing human footprint. The relatively low amount of anthropogenic mortality compared to other taxa suggests that reptiles may be more impacted by indirect than direct anthropogenic mortality. As a result, mitigating these indirect impacts, which include habitat loss and introduction of invasive species, is essential for conservation of North American reptiles
Causeāspecific mortality of the worldās terrestrial vertebrates
Aim: Vertebrates are declining worldwide, yet a comprehensive examination of the sources of mortality is lacking. We conducted a global synthesis of terrestrial vertebrate causeāspecific mortality to compare the sources of mortality across taxa and determine predictors of susceptibility to these sources of mortality.
Location: Worldwide.
Time period: 1970ā2018.
Major taxa studied: Mammals, birds, reptiles and amphibians.
Methods: We searched for studies that used telemetry to determine the cause of death of terrestrial vertebrates. We determined whether each mortality was caused by anthropogenic or natural sources and further classified mortalities within these two categories (e.g. harvest, vehicle collision and predation). For each study, we determined the diet and average adult body mass of the species and whether the study site permitted hunting. Mortalities were separated into juvenile or adult age classes.
We used linear mixed effects models to predict the percentage of mortality from each source and the overall magnitude of mortality based on these variables.
Results: We documented 42,755 mortalities of known cause from 120,657 individuals representing 305 vertebrate species in 1,114 studies. Overall, 28% of mortalities were directly caused by humans and 72% from natural sources. Predation (55%) and legal harvest (17%) were the leading sources of mortality.
Main conclusions: Humans were directly responsible for more than oneāquarter of global terrestrial vertebrate mortality. Larger birds and mammals were harvested more often and suffered increased anthropogenic mortality. Anthropogenic mortality of mammals and birds outside areas that prohibited hunting was higher than within areas where hunting was prohibited. Mammals experienced shifts from predominately natural to anthropogenic mortality as they matured. Humans are a major contributor to terrestrial vertebrate mortality, potentially impacting evolutionary processes and ecosystem functioning
Partitioning of evapotranspiration and its relation to carbon dioxide exchange in a Chihuahuan Desert shrubland
Key to evaluating the consequences of woody plant encroachment on water and carbon cycling in semiarid ecosystems is a mechanistic understanding of how biological and non-biological processes influence water loss to the atmosphere. To better understand how precipitation is partitioned into the components of evapotranspiration (bare-soil evaporation and plant transpiration) and their relationship to plant uptake of carbon dioxide (CO2) as well as ecosystem respiratory efflux, we measured whole plant transpiration, evapotranspiration, and CO2 fluxes over the course of a growing season at a semiarid Chihuahuan Desert shrubland site in south-eastern Arizona. Whole plant transpiration was measured using the heat balance sap-flow method, while evapotranspiration and net ecosystem exchange (NEE) of CO2 were quantified using the Bowen ratio technique
Synthesis of Chiral Bisoxazoline Ligands: (3aR,3a'R,8aS,8a'S)-2,2'-(cyclopropane-1,1-diyl)bis(3a,8a-dihydro-8H-indeno[1,2-d]oxazole)
A. Bis((3aR,8aS)-3a,8a-dihydro-8H-indeno[1,2-d]oxazol-2-yl)methane (3) . An oven-dried 2-L three-necked, round-bottomed flask equipped with a 6.5 cm Ć 2.0 cm Teflon-coated elliptical stir bar is fitted with a thermometer, a reflux condenser and a rubber septum. The system is connected to a continuous nitrogen flow and then charged with (1R,2S)-(+)-cis-1-amino-2-indanol (1, 22.2 g, 149 mmol, 2.1 equiv), diethyl malonimidate dihydrochloride (2, 16.4 g, 71 mmol, 1 equiv), and 1 L of dichloromethane (Note 2). The system is heated to 45 Ā°C (internal temperature 43 Ā°C) under an atmosphere of nitrogen in an oil bath for 18 h, stirring at 600 rpm. Reaction progress is monitored by Ā¹H NMR (Note 3) (Figure 1)
Visualizing genetic constraints
Principal Components Analysis (PCA) is a common way to study the sources of
variation in a high-dimensional data set. Typically, the leading principal
components are used to understand the variation in the data or to reduce the
dimension of the data for subsequent analysis. The remaining principal
components are ignored since they explain little of the variation in the data.
However, evolutionary biologists gain important insights from these low
variation directions. Specifically, they are interested in directions of low
genetic variability that are biologically interpretable. These directions are
called genetic constraints and indicate directions in which a trait cannot
evolve through selection. Here, we propose studying the subspace spanned by low
variance principal components by determining vectors in this subspace that are
simplest. Our method and accompanying graphical displays enhance the
biologist's ability to visualize the subspace and identify interpretable
directions of low genetic variability that align with simple directions.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS603 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Impact locations and damage to civil and military rotary-wing aircraft from wildlife strikes
Rotary-wing aircraft (e.g., helicopters and tilt-wing aircraft) are an important component of all U.S. military services and the U.S. civil aviation industry. Our analyses of wildlife strikes to military rotary-wing aircraft, both within the United States and during overseas deployments, as well as civil helicopters, have shown there are important patterns within wildlife strike data for flight operations conducted on airfields and during off-airfield missions. Birds accounted for 93% of the wildlife strikes where the animal was identified, and mammals (primarily bats) accounted for 7%. Wildlife impacted all parts of civil helicopters and military rotary-wing aircraft during strike events; however, specific areas were impacted by wildlife with a higher frequency compared to others. We recommend airframe manufacturers and maintenance personnel consider reinforcing and redesigning rotary-wing aircraft windscreens and main rotor systems to better withstand the impact of wildlife
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