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 effects of participation in service-learning on adolescents with disabilities

This article examines the effects of active participation in service-learning on adolescents with disabilities. Through a survey of special education teachers, effects on students\u27 socialization, behavior, attitudes, attendance, academic skills, functional skills, and relationships with non-disabled peers are explored. Promising results are found for adolescents with mild disabilities in attendance and academic skills, and for adolescents with moderate to profound disabilities in socialization and relationships with non-disabled peers. Implications for school inclusion of students with disabilities are addressed and recommendations for areas of future study are made

GEMPAK5 user's guide, version 5.0

GEMPAK is a general meteorological software package used to analyze and display conventional meteorological data as well as satellite derived parameters. The User's Guide describes the GEMPAK5 programs and input parameters and details the algorithms used for the meteorological computations

Brane World in a Topological Black Hole Bulk

We consider a static brane in the background of a topological black hole, in arbitrary dimensions. For hyperbolic horizons, we find a solution only when the black hole mass assumes its minimum negative value. In this case, the tension of the brane vanishes, and the brane position coincides with the location of the horizon. For an elliptic horizon, we show that the massless mode of Randall-Sundrum is recovered in the limit of large black hole mass.Comment: Latex, 8 pages, v2: Additional references, to appear in MPL

Black Hole Thermodynamics and Riemann Surfaces

We use the analytic continuation procedure proposed in our earlier works to study the thermodynamics of black holes in 2+1 dimensions. A general black hole in 2+1 dimensions has g handles hidden behind h horizons. The result of the analytic continuation is a hyperbolic 3-manifold having the topology of a handlebody. The boundary of this handlebody is a compact Riemann surface of genus G=2g+h-1. Conformal moduli of this surface encode in a simple way the physical characteristics of the black hole. The moduli space of black holes of a given type (g,h) is then the Schottky space at genus G. The (logarithm of the) thermodynamic partition function of the hole is the Kaehler potential for the Weil-Peterson metric on the Schottky space. Bekenstein bound on the black hole entropy leads us to conjecture a new strong bound on this Kaehler potential.Comment: 17+1 pages, 9 figure

Simulating Human-AI Collaboration with ACT-R and Project Malmo

We use the ACT-R cognitive architecture (Anderson, 2007) to explore human-AI collaboration. Computational models of human and AI behavior, and their interaction, allow for more effective development of collaborative artificial intelligent agents. With these computational models and simulations, one may be better equipped to predict the situations in which certain classes of intelligent agents may be more suited to collaborate with people. One can more tractably understand and predict how different AI agents affect task behavior in these situations. To simulate human-AI collaboration, we are developing ACT-R models that work with more traditional AI agents to solve a task in Project Malmo (Johnson et al., 2016). We use existing AI agents that were originally developed as the AI portion of the Human-AI collaboration. In addition, creating a model in ACT-R to simulate human behavior gives us the opportunity to play out these interactions much faster than would be possible in real time

General K=-1 Friedman-Lema\^itre models and the averaging problem in cosmology

We introduce the notion of general K=-1 Friedman-Lema\^itre (compact) cosmologies and the notion of averaged evolution by means of an averaging map. We then analyze the Friedman-Lema\^itre equations and the role of gravitational energy on the universe evolution. We distinguish two asymptotic behaviors: radiative and mass gap. We discuss the averaging problem in cosmology for them through precise definitions. We then describe in quantitative detail the radiative case, stressing on precise estimations on the evolution of the gravitational energy and its effect in the universe's deceleration. Also in the radiative case we present a smoothing property which tells that the long time H^{3} x H^{2} stability of the flat K=-1 FL models implies H^{i+1} x H^{i} stability independently of how big the initial state was in H^{i+1} x H^{i}, i.e. there is long time smoothing of the space-time. Finally we discuss the existence of initial "big-bang" states of large gravitational energy, showing that there is no mathematical restriction to assume it to be low at the beginning of time.Comment: Revised version. 32 pages, 1 figur

Fate of Kaluza-Klein Bubble

We numerically study classical time evolutions of Kaluza-Klein bubble space-time which has negative energy after a decay of vacuum. As the zero energy Witten's bubble space-time, where the bubble expands infinitely, the subsequent evolutions of Brill and Horowitz's momentarily static initial data show that the bubble will expand in terms of the area. At first glance, this result may support Corley and Jacobson's conjecture that the bubble will expand forever as well as the Witten's bubble. The irregular signatures, however, can be seen in the behavior of the lapse function in the maximal slicing gauge and the divergence of the Kretchman invariant. Since there is no appearance of the apparent horizon, we suspect an appearance of a naked singularity as the final fate of this space-time.Comment: 13 pages including 10 figures, RevTeX, epsf.sty. CGPG-99/12-8, RESCEU-6/00 and DAMTP-2000-30. To appear in Phys. Rev.