776 research outputs found
Water Quality Project Evaluation A Handbook for Objectives-Based Evaluation of Water Quality Projects
PDF pages: 5
An Arctic ecosystem : the coastal tundra at Barrow, Alaska
From the Foreward: This book is one of a series of volumes reporting results of research by
U. S. scientists participating in the International Biological Program
(IBP). As one of the 58 nations taking part in the IBP during the period
July 1967 to June 1974 , the United States organized a number of large,
multidisciplinary studies pertinent to the central IBP theme of "the biological
basis of productivity and human welfare."Direct financial support of the Biome-wide
program was derived from three major sources: the National Science
Foundation, the State of Alaska and the petroleum industry through the
University of Alaska. The NSF funding was under the joint sponsorship
of the U. S. Arctic Research Program (Division of Polar Programs) and
the U. S. International Biological Program (Ecosystem Analysis). The
Army Research Office and the Department of Energy (previously AEC
and ERDA) both contributed funded projects to the Program. Industry
support was provided through unrestricted grants from: Atlantic Richfield
Company, Alyeska Pipeline Service Company, BP Alaska, Inc.
Cities Service Company, Exxon Company, USA (Humble Oil and Refining
Company), Gulf Oil Corporation , Marathon Oil Company, Mobil
Oil Company, Prudhoe Bay Environmental Subcommittee of the Alaska
Oil and Gas Association, Shell Oil Company, Standard Oil Company of
California, Standard Oil (Indiana) Foundation Inc., and Sun Oil Company
Infrared Observations During the Secondary Eclipse of HD 209458b: I. 3.6-Micron Occultation Spectroscopy Using the VLT
We search for an infrared signature of the transiting extrasolar planet HD
209458b during secondary eclipse. Our method, which we call `occultation
spectroscopy,' searches for the disappearance and reappearance of weak spectral
features due to the exoplanet as it passes behind the star and later reappears.
We argue that at the longest infrared wavelengths, this technique becomes
preferable to conventional `transit spectroscopy'. We observed the system in
the wing of the strong nu-3 band of methane near 3.6 microns during two
secondary eclipses, using the VLT/ISAAC spectrometer at a spectral resolution
of 3300. Our analysis, which utilizes a model template spectrum, achieves
sufficient precision to expect detection of the spectral structure predicted by
an irradiated, low-opacity (cloudless), low-albedo, thermochemical equilibrium
model for the exoplanet atmosphere. However, our observations show no evidence
for the presence of this spectrum from the exoplanet, with the statistical
significance of the non-detection depending on the timing of the secondary
eclipse, which depends on the assumed value for the orbital eccentricity. Our
results reject certain specific models of the atmosphere of HD 209458b as
inconsistent with our observations at the 3-sigma level, given assumptions
about the stellar and planetary parameters.Comment: 26 pages, 8 figures Accepted to Astrophysical Journa
SCAMP: Rapid Focused Sonic Boom Waypoint Flight Planning Methods, Execution, and Results
Successful execution of the flight phase of the Superboom Caustic Analysis and Measurement Project (SCAMP) required accurate placement of focused sonic booms on an array of prepositioned ground sensors. While the array was spread over a 10,000-ft-long area, this is a relatively small region when considering the speed of a supersonic aircraft and sonic boom ray path variability due to shifting atmospheric conditions and aircraft trajectories. Another requirement of the project was to determine the proper position for a microphone-equipped motorized glider to intercept the sonic boom caustic, adding critical timing to the constraints. Variability in several inputs to these calculations caused some shifts of the focus away from the optimal location. Reports of the sonic booms heard by persons positioned amongst the array were used to shift the focus closer to the optimal location for subsequent passes. This paper describes the methods and computations used to place the focused sonic boom on the SCAMP array and gives recommendations for their accurate placement by future quiet supersonic aircraft. For the SCAMP flights, 67% of the foci were placed on the ground array with measured positions within a few thousand feet of computed positions. Among those foci with large caustic elevation angles, 96% of foci were placed on the array, and measured positions were within a few hundred feet of computed positions. The motorized glider captured sonic booms on 59% of the passes when the instrumentation was operating properly
Comparison of Observed and Simulated Grow-Finish Swine Performance Under Summer Conditions
As a part of a National Pork Producers Council educational program, our research and extension team at the University of Kentucky was linked with an independent commercial swine producer to test the NCPIG model against observed commercial on-farm data. This experience provided improved information for model development as well as increased producer insight into the data input needs and potential benefits of modeling. Detailed production information comparisons between the NCPIG model and producer data are presented for summer time conditions to assess the validity of the NCPIG model for simulation of grow-finish swine performance. Results demonstrated that the NCPIG model accurately simulated performance
Pyruvate Oxidase of \u3ci\u3eStreptococcus pneumoniae\u3c/i\u3e Contributes to Penumolysin Release
Background
Streptococcus pneumoniae is one of the leading causes of community acquired pneumonia and acute otitis media. Certain aspects of S. pneumoniae’s virulence are dependent upon expression and release of the protein toxin pneumolysin (PLY) and upon the activity of the peroxide-producing enzyme, pyruvate oxidase (SpxB). We investigated the possible synergy of these two proteins and identified that release of PLY is enhanced by expression of SpxB prior to stationary phase growth. Results
Mutants lacking the \u3c\u3espxB gene were defective in PLY release and complementation of spxB restored PLY release. This was demonstrated by cytotoxic effects of sterile filtered supernatants upon epithelial cells and red blood cells. Additionally, peroxide production appeared to contribute to the mechanism of PLY release since a significant correlation was found between peroxide production and PLY release among a panel of clinical isolates. Exogenous addition of H2O2 failed to induce PLY release and catalase supplementation prevented PLY release in some strains, indicating peroxide may exert its effect intracellularly or in a strain-dependent manner. SpxB expression did not trigger bacterial cell death or LytA-dependent autolysis, but did predispose cells to deoxycholate lysis. Conclusions
Here we demonstrate a novel link between spxB expression and PLY release. These findings link liberation of PLY toxin to oxygen availability and pneumococcal metabolism
What Have We Learned from RHIC?
In this talk, I present what I believe we have learned from the recent RHIC
heavy ion experiments. The goal of these experiments is to make and study
matter at very high energy densities, greater than an order of magnitude larger
than that of nuclear matter. Have we made such matter? What have we learned
about the properties of this matter? What do we hope and expect to learn in the
future?Comment: 34 figure
Semiclassical Casimir Energies at Finite Temperature
We study the dependence on the temperature T of Casimir effects for a range
of systems, and in particular for a pair of ideal parallel conducting plates,
separated by a vacuum. We study the Helmholtz free energy, combining
Matsubara's formalism, in which the temperature appears as a periodic Euclidean
fourth dimension of circumference 1/T, with the semiclassical periodic orbital
approximation of Gutzwiller. By inspecting the known results for the Casimir
energy at T=0 for a rectangular parallelepiped, one is led to guess at the
expression for the free energy of two ideal parallel conductors without
performing any calculation. The result is a new form for the free energy in
terms of the lengths of periodic classical paths on a two-dimensional cylinder
section. This expression for the free energy is equivalent to others that have
been obtained in the literature. Slightly extending the domain of applicability
of Gutzwiller's semiclassical periodic orbit approach, we evaluate the free
energy at T>0 in terms of periodic classical paths in a four-dimensional cavity
that is the tensor product of the original cavity and a circle. The validity of
this approach is at present restricted to particular systems. We also discuss
the origin of the classical form of the free energy at high temperatures.Comment: 17 pages, no figures, Late
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