6,339 research outputs found
On Whitney type inequalities for local anisotropic polynomial approximation
We prove a multivariate Whitney type theorem for the local anisotropic
polynomial approximation in with . Here is a
-parallelepiped in \RR^d with sides parallel to the coordinate axes. We
consider the error of best approximation of a function by algebraic
polynomials of fixed degree at most in variable ,
and relate it to a so-called total mixed modulus of smoothness appropriate to
characterizing the convergence rate of the approximation error. This theorem is
derived from a Johnen type theorem on equivalence between a certain
K-functional and the total mixed modulus of smoothness which is proved in the
present paper.Comment: 12 pages; the proofs of Theorems 1.2 and 2.2 and Lemma 3.1 are
revised; typos are corrected; Acknowledgments are added; the results are
unchange
Heavy flavor in heavy-ion collisions at RHIC and RHIC II
In the initial years of operation, experiments at the Relativistic Heavy Ion
Collider (RHIC) have identified a new form of matter formed in nuclei-nuclei
collisions at energy densities more than 100 times that of a cold atomic
nucleus. Measurements and comparison with relativistic hydrodynamic models
indicate that the matter thermalizes in an unexpectedly short time, has an
energy density at least 15 times larger than needed for color deconfinement,
has a temperature about twice the critical temperature predicted by lattice
QCD, and appears to exhibit collective motion with ideal hydrodynamic
properties - a "perfect liquid" that appears to flow with a near-zero viscosity
to entropy ratio - lower than any previously observed fluid and perhaps close
to a universal lower bound. However, a fundamental understanding of the medium
seen in heavy-ion collisions at RHIC does not yet exist. The most important
scientific challenge for the field in the next decade is the quantitative
exploration of the new state of nuclear matter. That will require new data that
will, in turn, require enhanced capabilities of the RHIC detectors and
accelerator. In this report we discuss the scientific opportunities for an
upgraded RHIC facility - RHIC II - in conjunction with improved capabilities of
the two large RHIC detectors, PHENIX and STAR. We focus solely on heavy flavor
probes. Their production rates are calculable using the well-established
techniques of perturbative QCD and their sizable interactions with the hot QCD
medium provide unique and sensitive measurements of its crucial properties
making them one of the key diagnostic tools available to us.Comment: 96 pages, 53 figures. Accepted for publication in Physics Reports.
Fixed typo in Fig. 15 captio
Enhanced carrier scattering rates in dilute magnetic semiconductors with correlated impurities
In III-V dilute magnetic semiconductors (DMSs) such as GaMnAs,
the impurity positions tend to be correlated, which can drastically affect the
electronic transport properties of these materials. Within the memory function
formalism we have derived a general expression for the current relaxation
kernel in spin and charge disordered media and have calculated spin and charge
scattering rates in the weak-disorder limit. Using a simple model for magnetic
impurity clustering, we find a significant enhancement of the charge
scattering. The enhancement is sensitive to cluster parameters and may be
controllable through post-growth annealing.Comment: 4 pages, 3 figure
Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Central South Dakota: Aurora, Brule, Charles Mix, Gregory and Jerauld Counties
The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: ( 1) To provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) To develop a research background for evaluating Government farm programs under varying assumptions
Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Cetnral South Dakota: Brown and Spink Counties
The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes· to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: (1) to provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) to develop a research background for evaluating government farm programs under varying assumptions
Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income in Central South Dakota: Buffalo, Hand and Hyde Counties
The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were (1) To provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) To develop a research background for evaluating Government farm programs under varying assumptions
Effect of Alternative Wheat and Feed Grain Prices on Optimum Farm Plans and Income: Beadle, Clark, Codington, Day, Marshall and Roberts Counties
The purpose of this report is to present some results of a cooperative research project between the South Dakota Agricultural Experiment Station and the Farm Production Economics Division, Economic Research Service, U. S. Department of Agriculture. This research contributes to a larger project-GP-5, Economic Problems in the Production and Marketing of Great Plains Wheat. The general objectives of the research undertaken in South Dakota were: (1) to provide economic data needed by farmers to make profitable adjustments in their farming systems and production practices and (2) to develop a research background for evaluating government farm programs under varying assumptions
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