13,615 research outputs found
Two dimensional fermions in three dimensional YM
Dirac fermions in the fundamental representation of SU(N) live on the surface
of a cylinder embedded in and interact with a three dimensional SU(N)
Yang Mills vector potential preserving a global chiral symmetry at finite .
As the circumference of the cylinder is varied from small to large, the chiral
symmetry gets spontaneously broken in the infinite limit at a typical bulk
scale. Replacing three dimensional YM by four dimensional YM introduces
non-trivial renormalization effects.Comment: 21 pages, 7 figures, 5 table
The Star Formation Rate - Dense Gas Relation in the Nuclei of Nearby Galaxies
We investigate the relationship between the star formation rate (SFR) and
dense molecular gas mass in the nuclei of galaxies. To do this, we utilize the
observed 850 micron luminosity as a proxy for the infrared luminosity and SFR,
and correlate this with the observed CO (J=3-2) luminosity. We find tentative
evidence that the LIR-CO (J=3-2) index is similar to the Kennicutt-Schmidt (KS)
index (N ~ 1.5) in the central ~1.7 kpc of galaxies, and flattens to a roughly
linear index when including emission from the entire galaxy. This result may
imply that the volumetric Schmidt relation is the underlying driver behind the
observed SFR-dense gas correlations, and provides tentative confirmation for
recent numerical models. While the data exclude the possibility of a constant
LIR-CO (J=3-2) index for both galaxy nuclei and global measurements at the ~80%
confidence level, the considerable error bars cannot preclude alternative
interpretations.Comment: Accepted at ApJ Letter
Investigation of temperature and concentration oscillations in the directional solidification of Pb-Sn-Te
Directional solidification of the pseudobinary compound semiconductor material Pb sub 1-x Sn sub x Te by the Bridgman crystal growth process will be studied. Natural convection in the molten sample will be visualized with a novel electrochemical cell technique that employs the solid electrolyte material yttria-stabilized zirconia. Mass transfer by both diffusion and convection will be measured by detecting the motion of oxygen tracer in the liquid. Additional applications for electrochemical cells in semiconductor crystal growth are suggested. Unsteady convection in the melt will also be detected by the appearance of temperature oscillations. The purpose of this study is to experimentally characterize the overstable conditions for a Pb sub 1-x Sn sub x Te melt in the vertical Bridgman crystal growth technique and use a linear analysis to predict the onset of convection for this system
Chiral Symmetry Restoration in the Schwinger Model with Domain Wall Fermions
Domain Wall Fermions utilize an extra space time dimension to provide a
method for restoring the regularization induced chiral symmetry breaking in
lattice vector gauge theories even at finite lattice spacing. The breaking is
restored at an exponential rate as the size of the extra dimension increases.
Before this method can be used in dynamical simulations of lattice QCD, the
dependence of the restoration rate to the other parameters of the theory and,
in particular, the lattice spacing must be investigated. In this paper such an
investigation is carried out in the context of the two flavor lattice Schwinger
model.Comment: LaTeX, 37 pages including 18 figures. Added comments regarding power
law fitting in sect 7. Also, few changes were made to elucidate the content
in sect. 5.1 and 5.3. To appear in Phys. Rev.
Keeping the dream alive: Managing the Space Station Program, 1982 to 1986
The management is described and analyzed of the formative years of the NASA Space Station Program (1982 to 1986), beginning with the successful initiative for program approval by Administrator James M. Beggs through to the decision to bring program management to Reston, Virginia. Emphasis is on internal management issues related to the implementation of the various phases of the program. Themes examined are the problem of bringing programmatic and institutional interests together and focusing them to forward the program; centralized versus decentralized control of the program; how the history of NASA and of the individual installations affected the decisions made; and the pressure from those outside NASA. The four sections are: (1) the decision to build the space station, (2) the design of the management experiment, (3) the experiment comes to life, and (4) the decision reversal
IMPACT OF SHELTERBELTS ON GROUNDNUT PRODUCTION IN THERILANDS: A DECOMPOSITION ANALYSIS.
In areas characterized by wind erosion and shifting sand dunes, shelterbelts can increase crop yields. Groundnut yields in southern India increased with the introduction and maturation of shelterbelts. Decomposition analysis attributed most of the yield increases to the shelterbelts themselves, with a small portion attributed to input use changes. While shelterbelt cost data are scarce, the estimated value of inputs saved due to shelterbelts suggested a net benefit stream that is initially negative but increasing into the indefinite future. Public investments in shelterbelts may be the most effective means of preventing land degradation.Crop Production/Industries,
PRICE SENSITIVITIES FOR U.S. FROZEN DAIRY PRODUCTS
Price elasticities and flexibilities for a system of frozen dessert products are estimated from scanner data. Simultaneity tests reject exogeneity of conditional expenditures, but not prices or quantities, at the weekly level. Inverting the elasticity matrix to obtain flexibilities, while theoretically appropriate, appears to be empirically unacceptable.Demand and Price Analysis,
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