Lattice Universes in 2+1-dimensional gravity

Lattice universes are spatially closed space-times of spherical topology in the large, containing masses or black holes arranged in the symmetry of a regular polygon or polytope. Exact solutions for such spacetimes are found in 2+1 dimensions for Einstein gravity with a non-positive cosmological constant. By means of a mapping that preserves the essential nature of geodesics we establish analogies between the flat and the negative curvature cases. This map also allows treatment of point particles and black holes on a similar footing.Comment: 14 pages 7 figures, to appear in Festschrift for Vince Moncrief (CQG

Collapse of Kaluza-Klein Bubbles

Kaluza-Klein theory admits ``bubble" configurations, in which the circumference of the fifth dimension shrinks to zero on some compact surface. A three parameter family of such bubble initial data at a moment of time-symmetry (some including a magnetic field) has been found by Brill and Horowitz, generalizing the (zero-energy) ``Witten bubble" solution. Some of these data have negative total energy. We show here that all the negative energy bubble solutions start out expanding away from the moment of time symmetry, while the positive energy bubbles can start out either expanding or contracting. Thus it is unlikely that the negative energy bubbles would collapse and produce a naked singularity.Comment: 6 pages, plain LaTeX, UMDGR-94-08

Characterization of the Torsional Piezoelectric-like Response of Tantalum Trisulfide Associated with Charge-Density-Wave Depinning

We have studied the frequency and voltage dependence of voltage-induced torsional strains in orthorhombic TaS3 [V. Ya. Pokrovskii, et al, Phys. Rev. Lett. 98, 206404 (2007)] by measuring the modulation of the resonant frequency of an RF cavity containing the sample. The strain has an onset voltage below the charge-density-wave (CDW) threshold voltages associated with changes in shear compliance and resistance, suggesting that the strain is associated with polarization of the CDW rather than CDW current. Measurements with square-wave voltages show that the strain is very sluggish, not even reaching its dc value at a frequency of 0.1 Hz, but the dynamics appear to be very sample dependent. By applying oscillating torque while biasing the sample with a dc current, we have also looked for strain induced voltage in the sample; none is observed at the low biases where the voltage-induced strains first occur, but an induced voltage is observed at higher biases, probably associated with strain-dependent CDW conductance.Comment: 11 pages, including 3 figures, to be published in Phys. Rev. B (Rapid Comm.

The isolation of gravitational instantons: Flat tori V flat R^4

The role of topology in the perturbative solution of the Euclidean Einstein equations about flat instantons is examined.Comment: 15 pages, ICN-UNAM 94-1

Aspects of analyticity

CONTENTS: 1 Introduction 2 Analytic Manifolds and Analytic Continuation of Metrics 3 Walker's Spacetimes and their Maximal Extension 4 Global Structure of de Sitter and Reissner-Nordstr\"om-de Sitter Cosmos 4.1 Special Cases 4.2 Collapsing Dust 5 Euclidean Metrics 6 Physical Interpretation of Euclidean Solutions, and a remark about the Gravitational Action 6.1 Thermal Interpretation 6.2 Tunneling Interpretation 7 The Multi-Black-Hole Solutions 7.1 Merging Black Holes 7.2 Continuing Beyond the Horizons 8 Naked Singularities? Reference

School Refusal:Characteristics, Assessment, and Effective Treatment: A Child and Parent Perspective

The present study, using shelf data, described a quantitative research project which attempted to propound and answer questions about the nature of school refusal in a Pennsylvania school district. The study analyzed shelf data that surveyed 40 students and parents in grades 2 through 11th who missed more than ten percent of 2007-2008 school year. Using shelf data collected by the GNA school district which consisted of parent and student surveys, this study investigated the different reasons why students refuse to attend school. Furthermore, this study also examined common characteristics found among school-refusing students in the Greater Nanticoke Area School District. Results of this study did not support previous findings of a positive correlation between parents’ permissive parenting styles and higher rates of school refusal. Although results revealed a relatively equal representation of school refusal across grades, slightly higher rates of school refusal behavior was noted among 6th grade students. No differences in gender were reported. Limitations of the study and suggestions for future research were also discussed