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 µm 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 QED3QED_3

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 intervals—the Wilson interval, the Agresti–Coull interval and the Jeffreys interval—in 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