4,582 research outputs found
Early Time Evolution of High Energy Heavy Ion Collisions
We solve the Yang-Mills equations in the framework of the
McLerran-Venugopalan model for small times tau after a collision of two nuclei.
An analytic expansion around tau=0 leads to explicit results for the field
strength and the energy momentum tensor of the gluon field at early times. We
then discuss constraints for the energy density, pressure and flow of the
plasma phase that emerges after thermalization of the gluon field.Comment: 4 pages, 1 figure; contribution to Quark Matter 2006; submitted to J.
Phys.
GrowingâŠBut Constrained: An Exploration of Teachers\u27 and Researchers\u27 Interactions with Culture and Diversity through Personal Narratives
Educators from all realms of education who engage in in-depth conversations and reflections about personal experiences and perspectives related to diversity are significantly important to the cultural understandings in Education. This paper is a narrative analysis of how teachers who were enrolled in a Master\u27s Program from two university campuses of the same predominantly White university participated in an in-depth look at their diverse cultural experiences through reflection and dialogue. Two researchers, one African American female utilizing the Critical Race Theory perspective the other Caucasian female using Socio-constructivism, interacted with one another and the teachers\u27 narratives through several personal experiences interchanges. The resulting teacher/research dialogue on culture and diversity revealed how when the constraints of different theoretical frameworks and past encounters with culture and diversity are exposed a space for dialogue on culture and diversity, characterized by growth, opens up
Discussion of spectrophotometric determination of marine-plant pigments, with revised equations for ascertaining chlorophylls and carotenoids
A number of discrepancies in the spectrophotometric determination of plant pigments with the Richards with Thompson method have been reported. A revised set of equations for the determination of plant chlorophylls and a new equation for the approximate estimation of plant carotenoids are presented
Extranuclear X-ray Emission in the Edge-on Seyfert Galaxy NGC 2992
We found several extranuclear (r >~ 3") X-ray nebulae within 40" (6.3 kpc at
32.5 Mpc) of the nucleus of the Seyfert galaxy NGC 2992. The net X-ray
luminosity from the extranuclear sources is ~2-3 E39 erg/s (0.3-8.0 keV). The
X-ray core itself (r <~ 1") is positioned at 9:45:41.95 -14:19:34.8 (J2000) and
has a remarkably simple power-law spectrum with photon index Gamma=1.86 and
Nh=7E21 /cm2. The near-nuclear (3" <~ r <~ 18") Chandra spectrum is best
modelled by three components: (1) a direct AGN component with Gamma fixed at
1.86, (2) cold Compton reflection of the AGN component, and (3) a 0.5 keV
low-abundance (Z < 0.03 Zsolar) "thermal plasma," with ~10% of the flux of
either of the first two components. The X-ray luminosity of the 3rd component
(the "soft excess") is ~1.4E40 erg/s, or ~5X that of all of the detected
extranuclear X-ray sources. We suggest that most (~75-80%) of the soft excess
emission originates from 1" < r < 3", which is not imaged in our observation
due to severe CCD pile-up. We also require the cold reflector to be positioned
at least 1" (158 pc) from the nucleus, since there is no reflection component
in the X-ray core spectrum. Much of the extranuclear X-ray emission is
coincident with radio structures (nuclear radio bubbles and large-scale radio
features), and its soft X-ray luminosity is generally consistent with
luminosities expected from a starburst-driven wind (with the starburst scaled
from L_FIR). However, the AGN in NGC 2992 seems equally likely to power the
galactic wind in that object. Furthermore, AGN photoionization and
photoexcitation processes could dominate the soft excess, especially the
\~75-80% which is not imaged by our observations.Comment: 34 pages AASTEX, 9 (low-res) PS figures, ApJ, in press. For
full-resolution postscript file, visit
http://www.pha.jhu.edu/~colbert/n2992_chandra.ps.g
Effect of dynamic stall on the aerodynamics of vertical-axis wind turbines
Accurate simulations of the aerodynamic performance of vertical-axis wind turbines pose a significant challenge for computational fluid dynamics methods. The aerodynamic interaction between the blades of the rotor and the wake that is produced by the blades requires a high-fidelity representation of the convection of vorticity within the wake. In addition, the cyclic motion of the blades induces large variations in the angle of attack on the blades that can manifest as dynamic stall. The present paper describes the application of a numerical model that is based on the vorticity transport formulation of the NavierâStokes equations, to the prediction of the aerodynamics of a verticalaxis wind turbine that consists of three curved rotor blades that are twisted helically around the rotational axis of the rotor. The predicted variation of the power coefficient with tip speed ratio compares very favorably with experimental measurements. It is demonstrated that helical blade twist reduces the oscillation of the power coefficient that is an inherent feature of turbines with non-twisted blade configurations
Cancer Information Seeking Preferences among health professionals serving American Indians in Minnesota, North Dakota, and Wisconsin
This article identifies cancer information resources used by health professionals in tribal health departments or Indian Health Service clinics serving American Indian communities in Wisconsin, Minnesota and North Dakota
Ferromagnetic redshift of the optical gap in GdN
We report measurements of the optical gap in a GdN film at temperatures from
300 to 6K, covering both the paramagnetic and ferromagnetic phases. The gap is
1.31eV in the paramagnetic phase and red-shifts to 0.9eV in the spin-split
bands below the Curie temperature. The paramagnetic gap is larger than was
suggested by very early experiments, and has permitted us to refine a
(LSDA+U)-computed band structure. The band structure was computed in the full
translation symmetry of the ferromagnetic ground state, assigning the
paramagnetic-state gap as the average of the majority- and minority-spin gaps
in the ferromagnetic state. That procedure has been further tested by a band
structure in a 32-atom supercell with randomly-oriented spins. After fitting
only the paramagnetic gap the refined band structure then reproduces our
measured gaps in both phases by direct transitions at the X point.Comment: 5 pages, 4 figure
Analysis of EUV/FUV dayglow and auroral measurements
This report documents investigations carried out over the twelve month period which commenced in November 1992. The contract identifies the following three tasks: analysis of the O II 83.4 nm dayglow and comparison with incoherent scatter radar data, analysis of the EUV spectrum of an electron aurora, and analysis of the EUV spectrum of a proton-hydrogen-electron aurora. The analysis approach, data reduction methods, and results, including plots of O I 98.9 nm versus time and average spectra, are presented for the last two tasks. The appendices contain preprints of two papers written under the first task. The first paper examines the effect of new O(3P) photoionization cross sections, N2 photoabsorption cross sections, and O(+) oscillator strengths and transition probabilities on the O II 83.4 nm dayglow. The second addresses the problem of remotely sensing the dayside F2 region using limb O II 83.4 nm data
Forage-Animal Production Research Unit (FAPRU): Establishment of a New USDA-ARS Research Location
Forages are vital to the success of grazing livestock production systems. Forages provide a low cost source of nutrients for animal production (Barnes & Nelson 2003; Ball et al., 1996). Limited fundamental (i.e., genomic, proteomic, metabolomic) research on the effects of environment and management on plant quality and production and the effects of plant metabolites (i.e., nutrients, anti-quality factors, nutraceuticals) on animal performance has hindered our ability to improve the productivity of forage-based enterprises. There is insufficient information for reliable prediction of animal performance in response to plant metabolites. To address these issues, USDA-ARS established FAPRU (Forage-Animal Production Research Unit) in 2003 at U Kentucky, Lexington. Its mission is to improve the productivity, profitability, competitiveness and sustainability of forage-based enterprises through improved understanding of the fundamental biological processes that occur at the animal-plant interface
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