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Formation of Amorphous Metal By Hypervelocity Impact
The Center for Electromechanics at The University of Texas at Austin has investigated the use of an electromagnetic railgun accelerator for the deposition of non-crystalline metals. The two main objectives of the study were to produce non-crystalline metal deposits in single thin layers (˷ 25lJm thick) and to determine the feasibility of building thicker layers by making multiple deposits. Deposits have been analyzed using a variety of techniques, including electrical resistivity and resistivity ratio, x-ray diffraction, and transmission electron microscopy. Differential scanning calorimetry was carried out at Battelle Columbus Laboratories. The measurements show that CEM-UT -has produced non-crystalline Fe78B13Si9 deposits. Single and multiple-layer non-crystalline deposits with thicknesses of up to 36 ”m have been produced, and the upper thickness limit of the technique has not yet been determined.Center for Electromechanic
The Composing Process: A Springboard for Literacy Development
The composing process involves the methods used by writers to discover ideas, formulate goals, make plans, ex press ideas, and assess, revise, and edit their writing. Several years ago, few studies examining the children\u27s composing process could be found in the literature. Yet recently, there has been an increased interest in all facets of composing. This interest has resulted from a concern for improving reading and writing skills, and has been the impetus for increased research activity. As a result of this research activity, models describing the composing process have been developed, and new issues are continuing to gain attention. One such issue relates to the techniques that children use when composing
Becoming Literate: The Acquisition of Story Discourse
Educators and researchers are focusing their attention on children\u27s knowledge of reading and writing acquired prior to formal instruction. Many research projects have described the parallel between children\u27s acquisition of spoken and written language. As a result of extensive research during the last twenty years, educators\u27 understanding of how children learn to read and write has changed drastically
Lie symmetries of Einstein's vacuum equations in N dimensions
We investigate Lie symmetries of Einstein's vacuum equations in N dimensions,
with a cosmological term. For this purpose, we first write down the second
prolongation of the symmetry generating vector fields, and compute its action
on Einstein's equations. Instead of setting to zero the coefficients of all
independent partial derivatives (which involves a very complicated substitution
of Einstein's equations), we set to zero the coefficients of derivatives that
do not appear in Einstein's equations. This considerably constrains the
coefficients of symmetry generating vector fields. Using the Lie algebra
property of generators of symmetries and the fact that general coordinate
transformations are symmetries of Einstein's equations, we are then able to
obtain all the Lie symmetries. The method we have used can likely be applied to
other types of equations
Mass singularity and confining property in
We discuss the properties of the position space fermion propagator in three
dimensional QED which has been found previouly based on Ward-Takahashi-identity
for soft-photon emission vertex and spectral representation.There is a new type
of mass singularity which governs the long distance behaviour.It leads the
propagator vanish at large distance.This term corresponds to dynamical mass in
position space.Our model shows confining property and dynamical mass generation
for arbitrary coupling constant.Since we used dispersion retation in deriving
spectral function there is a physical mass which sets a mass scale.For finite
cut off we obtain the full propagator in the dispersion integral as a
superposition of different massses.Low energy behaviour of the proagator is
modified to decrease by position dependent mass.In the limit of zero infrared
cut-off the propagator vanishes with a new kind of infrared behaviour.Comment: 22pages,4figures,revtex4,Notational sloppiness are crrected.Submitted
to JHE
Quark Coulomb Interactions and the Mass Difference of Mirror Nuclei
We study the Okamoto-Nolen-Schiffer (ONS) anomaly in the binding energy of
mirror nuclei at high density by adding a single neutron or proton to a quark
gluon plasma. In this high-density limit we find an anomaly equal to two-thirds
of the Coulomb exchange energy of a proton. This effect is dominated by quark
electromagnetic interactions---rather than by the up-down quark mass
difference. At normal density we calculate the Coulomb energy of neutron matter
using a string-flip quark model. We find a nonzero Coulomb energy because of
the neutron's charged constituents. This effect could make a significant
contribution to the ONS anomaly.Comment: 4 pages, 2 figs. sub. to Phys. Rev. Let
Success in Reading: Four Characteristics of Strategic Readers
Reading is a complex process which involves the coordination of a multitude of skills. Strategic readers can be distinguished from the less-skilled readers by their methods of interacting with text. The mental processes of good readers must be understood in order to make assumptions concerning the nature of reading
Improving interval estimation of binomial proportions
In this paper, we propose one new confidence interval for the binomial proportion; our interval is based on the Edgeworth expansion of a logit transformation of the sample proportion. We provide theoretical justification for the proposed interval and also compare the finite-sample performance of the proposed interval with the three best existing intervalsâthe Wilson interval, the AgrestiâCoull interval and the Jeffreys intervalâin terms of their coverage probabilities and expected lengths. We illustrate the proposed method in two real clinical studies
A Smirnov-Bickel-Rosenblatt theorem for compactly-supported wavelets
In nonparametric statistical problems, we wish to find an estimator of an
unknown function f. We can split its error into bias and variance terms;
Smirnov, Bickel and Rosenblatt have shown that, for a histogram or kernel
estimate, the supremum norm of the variance term is asymptotically distributed
as a Gumbel random variable. In the following, we prove a version of this
result for estimators using compactly-supported wavelets, a popular tool in
nonparametric statistics. Our result relies on an assumption on the nature of
the wavelet, which must be verified by provably-good numerical approximations.
We verify our assumption for Daubechies wavelets and symlets, with N = 6, ...,
20 vanishing moments; larger values of N, and other wavelet bases, are easily
checked, and we conjecture that our assumption holds also in those cases
Scaling Of Chiral Lagrangians And Landau Fermi Liquid Theory For Dense Hadronic Matter
We discuss the Fermi-liquid properties of hadronic matter derived from a
chiral Lagrangian field theory in which Brown-Rho (BR) scaling is incorporated.
We identify the BR scaling as a contribution to Landau's Fermi liquid
fixed-point quasiparticle parameter from "heavy" isoscalar meson degrees of
freedom that are integrated out from a low-energy effective Lagrangian. We show
that for the vector (convection) current, the result obtained in the chiral
Lagrangian approach agrees precisely with that obtained in the
semi-phenomenological Landau-Migdal approach. This precise agreement allows one
to determine the Landau parameter that enters in the effective nucleon mass in
terms of the constant that characterizes BR scaling. When applied to the weak
axial current, however, these two approaches differ in a subtle way. While the
difference is small numerically, the chiral Lagrangian approach implements
current algebra and low-energy theorems associated with the axial response that
the Landau method misses and hence is expected to be more predictive.Comment: 39 pages, latex with 4 eps figure, modified addresses and reference
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