Grade Retention and School Performance: An Extended Investigation

This study extends Reynolds’ (1992) investigation of the social- psychological influences on grade retention and school adjustment in early childhood by tracing the predictors and consequences of grade retention for school achievement, perceived competence, and delinquency in early adolescence (age 14). The study sample included 1,164 (93 percent of the sample from the original study) low-income, mostly black children in the Chicago Longitudinal Study. Twenty-eight percent of the study sample were retained-in-grade by age 14 (first grade to eighth grade). The strongest predictors of retention were early school performance (test scores and grades), sex (boys were more likely to be retained), parent participation in school, and school mobility. Overall, grade retention was significantly associated with lower reading and math achievement at age 14 above and beyond a comprehensive set of explanatory variables. Results based on same-age comparison groups yielded larger effects of retention on school achievement than those based on same-grade comparisons, but both approaches indicated that grade retention was associated with significantly lower reading achievement. In the full model, grade retention was unrelated to perceived school competence at age 12 and to delinquency infractions at age 14. With the exception of reading achievement, retention during the primary grades and retention during grades 4 to 7 yielded a similar pattern of effects. Findings were largely consistent with the earlier study and suggest that intervention approaches other than grade retention are needed to better promote school achievement and adjustment.

Finite Temperature and Dynamical Properties of the Random Transverse-Field Ising Spin Chain

We study numerically the paramagnetic phase of the spin-1/2 random transverse-field Ising chain, using a mapping to non-interacting fermions. We extend our earlier work, Phys. Rev. 53, 8486 (1996), to finite temperatures and to dynamical properties. Our results are consistent with the idea that there are ``Griffiths-McCoy'' singularities in the paramagnetic phase described by a continuously varying exponent $z(\delta)$, where $\delta$ measures the deviation from criticality. There are some discrepancies between the values of $z(\delta)$ obtained from different quantities, but this may be due to corrections to scaling. The average on-site time dependent correlation function decays with a power law in the paramagnetic phase, namely $\tau^{-1/z(\delta)}$, where $\tau$ is imaginary time. However, the typical value decays with a stretched exponential behavior, $\exp(-c\tau^{1/\mu})$, where $\mu$ may be related to $z(\delta)$. We also obtain results for the full probability distribution of time dependent correlation functions at different points in the paramagnetic phase.Comment: 10 pages, 14 postscript files included. The discussion of the typical time dependent correlation function has been greatly expanded. Other papers of APY are available on-line at http://schubert.ucsc.edu/pete

Spin Chains as Perfect Quantum State Mirrors

Quantum information transfer is an important part of quantum information processing. Several proposals for quantum information transfer along linear arrays of nearest-neighbor coupled qubits or spins were made recently. Perfect transfer was shown to exist in two models with specifically designed strongly inhomogeneous couplings. We show that perfect transfer occurs in an entire class of chains, including systems whose nearest-neighbor couplings vary only weakly along the chain. The key to these observations is the Jordan-Wigner mapping of spins to noninteracting lattice fermions which display perfectly periodic dynamics if the single-particle energy spectrum is appropriate. After a half-period of that dynamics any state is transformed into its mirror image with respect to the center of the chain. The absence of fermion interactions preserves these features at arbitrary temperature and allows for the transfer of nontrivially entangled states of several spins or qubits.Comment: Abstract extended, introduction shortened, some clarifications in the text, one new reference. Accepted by Phys. Rev. A (Rapid Communications

Exact solution of a 2d random Ising model

The model considered is a d=2 layered random Ising system on a square lattice with nearest neighbours interaction. It is assumed that all the vertical couplings are equal and take the positive value J while the horizontal couplings are quenched random variables which are equal in the same row but can take the two possible values J and J-K in different rows. The exact solution is obtained in the limit case of infinite K for any distribution of the horizontal couplings. The model which corresponds to this limit can be seen as an ordinary Ising system where the spins of some rows, chosen at random, are frozen in an antiferromagnetic order. No phase transition is found if the horizontal couplings are independent random variables while for correlated disorder one finds a low temperature phase with some glassy properties.Comment: 10 pages, Plain TeX, 3 ps figures, submitted to Europhys. Let

A Unifying Theory for the Religion Clauses of the First Amendment

According to Justice Powell, the first amendment religion clauses are the source of some of the most perplexing questions that the Supreme Court confronts. In a long and rapidly expanding line of religion clause cases the Court has struggled, with a conspicuous lack of success, to articulate principles of broad applicability. The Court\u27s efforts to date have resulted in a jumble of tests, standards, and theoretical approaches from which predicting the outcome in future cases is very difficult. The conceptual problems that have frustrated the Court\u27s attempts at doctrinal development center in two broad areas: first,the meaning and effect of the establishment clause and second, the relationship between the establishment clause and the free exercise clause. In a third area, the meaning and effect of the free exercise clause, the Court has had somewhat less trouble articulating a doctrinal approach, but even here the Court has not applied the doctrine consistently and has not reached entirely predictable results. Perhaps the most telling measure of the Court\u27s doctrinal frustration in the religion clause area is the extent to which it recently has attempted to elevate its conspicuous lack of doctrinal consistency into an accepted methodology for decision making. Chief Justice Burger summarized current thinking on the relationship between the two religion clauses by noting that there is internal tension in the First Amendment between the Establishment Clause and the Free Exercise Clause. Finding a clearer acknowledgement of the Court\u27s failure to articulate a unifying theory underlying the two clauses would be difficult. Concerning the meaning and effect of the establishment clause, Chief Justice Burger has observed with apparent approval (or at least resignation) that the Court has been unwilling to tie establishment clause analysis to a single test. With the same apparent approval, Justice White has noted that our decisions have tended to avoid categorical imperatives and absolutist approaches .... This course sacrifices clarity and predictability for flexibility .. .., Describing the same phenomenon in another case, Justice O\u27Connor concluded that [e]very government practice must be judged in its unique circumstances to determine whether it constitutes an endorsement or disapproval of religion. In effect, the Court seems to have accepted the inevitability of an ad hoc approach with a final result in any case possible only after Supreme Court review... The thesis of this Article is that such a single overriding objective can be identified and articulated. This objective reflects the basic purpose of those who authored and adopted the religion clauses and, to a remarkable degree, harmonizes the Court\u27s apparently disparate results in religion clause cases. The Court\u27s conscious acceptance of the unifying theory proposed in this Article would provide a satisfying explanation for a large number of results arrived at by intuition in the past and would provide a theoretical basis from which to predict results in future cases

Lunar particle shadows and boundary layer experiment: Plasma and energetic particles on the Apollo 15 and 16 subsatellites

The lunar particle shadows and boundary layer experiments aboard the Apollo 15 and 16 subsatellites and scientific reduction and analysis of the data to date are discussed with emphasis on four major topics: solar particles; interplanetry particle phenomena; lunar interactions; and topology and dynamics of the magnetosphere at lunar orbit. The studies of solar and interplanetary particles concentrated on the low energy region which was essentially unexplored, and the studies of lunar interaction pointed up the transition from single particle to plasma characteristics. The analysis concentrated on the electron angular distributions as highly sensitive indicators of localized magnetization of the lunar surface. Magnetosphere experiments provided the first electric field measurements in the distant magnetotail, as well as comprehensive low energy particle measurements at lunar distance

Painlev\'e Transcendent Describes Quantum Correlation Function of the XXZ Antiferromagnet away from the free-fermion point

We consider quantum correlation functions of the antiferromagnetic spin-$\frac{1}{2}$ Heisenberg XXZ spin chain in a magnetic field. We show that for a magnetic field close to the critical field $h_c$ (for the critical magnetic field the ground state is ferromagnetic) certain correlation functions can be expressed in terms of the solution of the Painlev\'e V transcendent. This establishes a relation between solutions of Painlev\'e differential equations and quantum correlation functions in models of {\sl interacting} fermions. Painlev\'e transcendents were known to describe correlation functions in models with free fermionic spectra.Comment: 10 pages, LaTeX2