3,340 research outputs found
Bullsnake Predation on Waterfowl Nests on Valentine National Wildlife Refuge, Nebraska
Bullsnake (Pituophis melanoleucus) predation on upland nesting ducks was monitored on Valentine National Wildlife Refuge (NWR) from 1982-86. The fate of 1,999 duck nests of 9 species was observed under different treatments of land use and control of potential nest predators. Maximum potential levels of bullsnake depredation are masked by nest destruction by mammalian species; bullsnake nest depredation rates were \u3e65% where mammalian predators were controlled, \u3e40% without predator control and \u3c4.0% where both mammalian and reptilian predators were controlled and/or excluded. Duck nest densities were dramatically increased where predator control was accomplished in undisturbed nesting cover
TB8: Enzyme Levels in Birds
This technical bulletin describes a research project relating to enzymes and chickens during health and disease. This project was started in 1957, and with the aid of a National Institutes of Health grant #C-4957 in 1959 the work was accelerated. This bulletin covers some of the work that has not been published and at also summarizes some of the literature relating to enzyme activity levels in birds.https://digitalcommons.library.umaine.edu/aes_techbulletin/1190/thumbnail.jp
Estimating the Effects Weather, Dry Matter Intake, and Body Weight on Daily Water Intake in Weaned Calves
Water is an essential nutrient and is required for growth, metabolism, lactation, and reproduction. However, water requirements for beef cattle have not been studied extensively since the 1950’s. The genetic potential for beef cattle has changed considerably since then. With the change in genetics, beef producers have observed increases in average daily gain and final body weight. The need for updated water requirements for beef cattle has also been exacerbated by global climate variability, drought conditions, and the need for efficient use of water resources. Given the increased productivity of cattle today relative to those of decades ago, increased water requirements are almost certain. Further research must be conducted to determine how those requirements have changed
Maximum elastic deformations of relativistic stars
We present a method for calculating the maximum elastic quadrupolar
deformations of relativistic stars, generalizing the previous Newtonian,
Cowling approximation integral given by [G. Ushomirsky et al., Mon. Not. R.
Astron. Soc. 319, 902 (2000)]. (We also present a method for Newtonian gravity
with no Cowling approximation.) We apply these methods to the m = 2 quadrupoles
most relevant for gravitational radiation in three cases: crustal deformations,
deformations of crystalline cores of hadron-quark hybrid stars, and
deformations of entirely crystalline color superconducting quark stars. In all
cases, we find suppressions of the quadrupole due to relativity compared to the
Newtonian Cowling approximation, particularly for compact stars. For the crust
these suppressions are up to a factor ~6, for hybrid stars they are up to ~4,
and for solid quark stars they are at most ~2, with slight enhancements instead
for low mass stars. We also explore ranges of masses and equations of state
more than in previous work, and find that for some parameters the maximum
quadrupoles can still be very large. Even with the relativistic suppressions,
we find that 1.4 solar mass stars can sustain crustal quadrupoles of a few
times 10^39 g cm^2 for the SLy equation of state or close to 10^40 g cm^2 for
equations of state that produce less compact stars. Solid quark stars of 1.4
solar masses can sustain quadrupoles of around 10^44 g cm^2. Hybrid stars
typically do not have solid cores at 1.4 solar masses, but the most massive
ones (~2 solar masses) can sustain quadrupoles of a few times 10^41 g cm^2 for
typical microphysical parameters and a few times 10^42 g cm^2 for extreme ones.
All of these quadrupoles assume a breaking strain of 0.1 and can be divided by
10^45 g cm^2 to yield the fiducial "ellipticities" quoted elsewhere.Comment: 21 pages, 11 figures, version accepted by PRD, including the
corrected maximum hybrid star quadrupoles (from the erratum to the shear
modulus calculation) and the corrected binding energy computatio
Theory of imaging a photonic crystal with transmission near-field optical microscopy
While near-field scanning optical microscopy (NSOM) can provide optical
images with resolution much better than the diffraction limit, analysis and
interpretation of these images is often difficult. We present a theory of
imaging with transmission NSOM that includes the effects of tip field,
tip/sample coupling, light propagation through the sample and light collection.
We apply this theory to analyze experimental NSOM images of a nanochannel glass
(NCG) array obtained in transmission mode. The NCG is a triangular array of
dielectric rods in a dielectric glass matrix with a two-dimensional photonic
band structure. We determine the modes for the NCG photonic crystal and
simulate the observed data. The calculations show large contrast at low
numerical aperture (NA) of the collection optics and detailed structure at high
NA consistent with the observed images. We present calculations as a function
of NA to identify how the NCG photonic modes contribute to and determine the
spatial structure in these images. Calculations are presented as a function of
tip/sample position, sample index contrast and geometry, and aperture size to
identify the factors that determine image formation with transmission NSOM in
this experiment.Comment: 28 pages of ReVTex, 14 ps figures, submitted to Phys. Rev.
Estimating the Effects of Weather, Dry Matter Intake, and Body Weight on Daily Water Intake in Weaned Calves
Objective The purpose of this study was to study the effect of weather, dry matter intake, and body weight on the water requirements of weaned calves and estimating the requirements in a model.Study Description Weaned steers (n=48) were selected to study the effects of the weather, body weight, and dry matter intake on water intake in the winter (n=24) and summer (n=24) months. Calves were provided with ad libitum access to feed and water at the SDSU Cow-Calf Education and Research Facility (CCERF) and measured utilizing an automated feed and water system (Insentec, The Hague, Netherlands). Temperature, humidity, precipitation, wind speed, solar radiation, and air pressure were recorded at a Mesonet automated weather station in Brookings, SD (located 2.4 miles from the SDSU CCERF). Effects of climate data, body weight, and daily dry matter intake on daily water intake will be analyzed utilizing a mixed-effects model
Formation of plasma around a small meteoroid: 1. Kinetic theory
This article is a companion to Dimant and Oppenheim [2017] https://doi.org/10.1002/2017JA023963.This paper calculates the spatial distribution of the plasma responsible for radar head echoes by applying the kinetic theory developed in the companion paper. This results in a set of analytic expressions for the plasma density as a function of distance from the meteoroid. It shows that at distances less than a collisional mean free path from the meteoroid surface, the plasma density drops in proportion to 1/R where R is the distance from the meteoroid center; and, at distances much longer than the mean‐free‐path behind the meteoroid, the density diminishes at a rate proportional to 1/R2. The results of this paper should be used for modeling and analysis of radar head echoes.This work was supported by NSF grant AGS-1244842. (AGS-1244842 - NSF
Charge Exchange and Chemical Reactions with Trapped Th
We have measured the reaction rates of trapped, buffer gas cooled Th
and various gases and have analyzed the reaction products using trapped ion
mass spectrometry techniques. Ion trap lifetimes are usually limited by
reactions with background molecules, and the high electron affinity of multiply
charged ions such as Th make them more prone to loss. Our results show
that reactions of Th with carbon dioxide, methane, and oxygen all occur
near the classical Langevin rate, while reaction rates with argon, hydrogen,
and nitrogen are orders of magnitude lower. Reactions of Th with oxygen
and methane proceed primarily via charge exchange, while simultaneous charge
exchange and chemical reaction occurs between Th and carbon dioxide.
Loss rates of Th in helium are consistent with reaction with impurities
in the gas. Reaction rates of Th with nitrogen and argon depend on the
internal electronic configuration of the Th.Comment: 9 pages, 10 figures, 4 tables. Submitted to PR
Spatially Resolved Temperature and Water Vapor Concentration Distributions in Supersonic Combustion Facilities by TDLAT
Detailed knowledge of the internal structure of high-enthalpy flows can provide valuable insight to the performance of scramjet combustors. Tunable Diode Laser Absorption Spectroscopy (TDLAS) is often employed to measure temperature and species concentration. However, TDLAS is a path-integrated line-of-sight (LOS) measurement, and thus does not produce spatially resolved distributions. Tunable Diode Laser Absorption Tomography (TDLAT) is a non-intrusive measurement technique for determining two-dimensional spatially resolved distributions of temperature and species concentration in high enthalpy flows. TDLAT combines TDLAS with tomographic image reconstruction. More than 2500 separate line-of-sight TDLAS measurements are analyzed in order to produce highly resolved temperature and species concentration distributions. Measurements have been collected at the University of Virginia's Supersonic Combustion Facility (UVaSCF) as well as at the NASA Langley Direct-Connect Supersonic Combustion Test Facility (DCSCTF). Due to the UVaSCF s unique electrical heating and ability for vitiate addition, measurements collected at the UVaSCF are presented as a calibration of the technique. Measurements collected at the DCSCTF required significant modifications to system hardware and software designs due to its larger measurement area and shorter test duration. Tomographic temperature and water vapor concentration distributions are presented from experimentation on the UVaSCF operating at a high temperature non-reacting case for water vitiation level of 12%. Initial LOS measurements from the NASA Langley DCSCTF operating at an equivalence ratio of 0.5 are also presented. Results show the capability of TDLAT to adapt to several experimental setups and test parameters
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