Dissociation and pain perception : an experimental investigation

textDissociative symptoms and abnormalities in pain perception have been associated with a range of disorders. We tested whether experimentally induced increases in state dissociation would cause an analgesic response, and whether this effect would be moderated by participants' history of trauma and dissociative experiences. Participants (n=120) were classified based on their histories of traumatic and dissociative experiences: No trauma or dissociation (NN), trauma without dissociation (TN), or trauma with dissociation (TD). All participants were randomized to a dissociation induction condition via audiophotic stimulation or a credible control condition and were compared on prepost changes in subjective pain and pain tolerance in response to a standard cold-pressor test. Unexpectedly, dissociation induction did not lead to greater pain tolerance or reduced self-reported pain. However, increases in state dissociation significantly predicted increased immersion time and decreased subjective pain.Psycholog

Dilating and contracting arbitrarily

Standard accuracy-based approaches to imprecise credences have the consequence that it is rational to move between precise and imprecise credences arbitrarily, without gaining any new evidence. Building on the Educated Guessing Framework of Horowitz (2019), we develop an alternative accuracy-based approach to imprecise credences that does not have this shortcoming. We argue that it is always irrational to move from a precise state to an imprecise state arbitrarily, however it can be rational to move from an imprecise state to a precise state arbitrarily

Scattering of Several Multiply Charged Extremal D=5 Black Holes

The moduli space metric for an arbitrary number of extremal D=5 black holes with arbitrary relatively supersymmetric charges is found.Comment: 12 pages, ReVTeX. Minor typos corrected, including an unimportant sign for which the corresponding comment was removed. One reference adde

Enabling III-V-based optoelectronics with low-cost dynamic hydride vapor phase epitaxy

Silicon is the dominant semiconductor in many semiconductor device applications for a variety of reasons, including both performance and cost. III-V materials have improved performance compared to silicon, but currently they are relegated to applications in high-value or niche markets due to the absence of a low-cost, high-quality production technique. Here we present an advance in III-V materials synthesis using hydride vapor phase epitaxy that has the potential to lower III-V semiconductor deposition costs by orders of magnitude while maintaining the requisite optoelectronic material quality that enables III-V-based technologies to outperform Si. We demonstrate the impacts of this advance by addressing the use of III-Vs in terrestrial photovoltaics, a highly cost-constrained market. The emergence of a low-cost III-V deposition technique will enable III-V electronic and opto-electronic devices, with all the benefits that they bring, to permeate throughout modern society.Comment: pre-prin

Efficiency of a Brownian information machine

A Brownian information machine extracts work from a heat bath through a feedback process that exploits the information acquired in a measurement. For the paradigmatic case of a particle trapped in a harmonic potential, we determine how power and efficiency for two variants of such a machine operating cyclically depend on the cycle time and the precision of the positional measurements. Controlling only the center of the trap leads to a machine that has zero efficiency at maximum power whereas additional optimal control of the stiffness of the trap leads to an efficiency bounded between 1/2, which holds for maximum power, and 1 reached even for finite cycle time in the limit of perfect measurements.Comment: 9 pages, 2 figure

Relativistic mean-field study of neutron-rich nuclei

A relativistic mean-field model is used to study the ground-state properties of neutron-rich nuclei. Nonlinear isoscalar-isovector terms, unconstrained by present day phenomenology, are added to the model Lagrangian in order to modify the poorly known density dependence of the symmetry energy. These new terms soften the symmetry energy and reshape the theoretical neutron drip line without compromising the agreement with existing ground-state information. A strong correlation between the neutron radius of 208Pb and the binding energy of valence orbitals is found: the smaller the neutron radius of 208Pb, the weaker the binding energy of the last occupied neutron orbital. Thus, models with the softest symmetry energy are the first ones to drip neutrons. Further, in anticipation of the upcoming one-percent measurement of the neutron radius of 208Pb at the Thomas Jefferson Laboratory, a close relationship between the neutron radius of 208Pb and neutron radii of elements of relevance to atomic parity-violating experiments is established.Comment: 14 pages, 5 figure

Black Hole Hair Removal: Non-linear Analysis

BMPV black holes in flat transverse space and in Taub-NUT space have identical near horizon geometries but different microscopic degeneracies. It has been proposed that this difference can be accounted for by different contribution to the degeneracies of these black holes from hair modes, -- degrees of freedom living outside the horizon. In this paper we explicitly construct the hair modes of these two black holes as finite bosonic and fermionic deformations of the black hole solution satisfying the full non-linear equations of motion of supergravity and preserving the supersymmetry of the original solutions. Special care is taken to ensure that these solutions do not have any curvature singularity at the future horizon when viewed as the full ten dimensional geometry. We show that after removing the contribution due to the hair degrees of freedom from the microscopic partition function, the partition functions of the two black holes agree.Comment: 40 pages, LaTe

A class of finite two - dimensional sigma models and string vacua

We consider a two - dimensional Minkowski signature sigma model with a $2+N$ - dimensional target space metric having a null Killing vector. It is shown that the model is finite to all orders of the loop expansion if the dependence of the ``transverse" part of the metric \ggij (u,x) on the light cone coordinate $u$ is subject to the standard renormalization group equation of the $N$ - dimensional sigma model, {d\ggij\over du} = \gb_{ij} =R_{ij} + ... . In particular, we discuss the `one - coupling' case when \ggij(u,x) is a metric of an $N$ - dimensional symmetric space \gij(x) multiplied by a function $f(u)$. The theory is finite if $f(u)$ is equal to the ``running" coupling of the symmetric space sigma model (with $u$ playing the role of the RG ``time"). For example, the geometry of space - time with \gij being the metric of the $N$ - sphere is determined by the form of the \gb - function of the $O(N+1)$ model. The ``asymptotic freedom" limit of large $u$ corresponds to the weak coupling limit of small $2+N$ - dimensional curvature. We prove that there exists a dilaton field which together with the $2+N$ - dimensional metric solves the sigma model Weyl invariance conditions. The resulting backgrounds thus represent new tree level string vacua. We also remark on possible connections with some $2d$ quantum gravity models.Comment: 15 pages [Complete revision. The main statement of the previous version is generalised to the case of an arbitrary ``transverse" metric satisfying sigma model renormalization group equation.

String vacuum backgrounds with covariantly constant null Killing vector and 2d quantum gravity

We consider a $2d$ sigma model with a $2+N$ - dimensional Minkowski signature target space metric having a covariantly constant null Killing vector. We study solutions of the conformal invariance conditions in $2+N$ dimensions and find that generic solutions can be represented in terms of the RG flow in $N$ - dimensional ``transverse space'' theory. The resulting conformal invariant sigma model is interpreted as a quantum action of the $2d$ scalar (``dilaton") quantum gravity model coupled to a (non-conformal) `transverse' sigma model. The conformal factor of the $2d$ metric is identified with a light cone coordinate of the $2+N$ - dimensional sigma model. We also discuss the case when the transverse theory is conformal (with or without the antisymmetric tensor background) and reproduce in a systematic way the solutions with flat transverse space known before.Comment: 26 p., revised (a discussion of tachyon coupling is added at the end of section 4), DAMTP-92-4

M.C.R.G. Study of Fixed-connectivity Surfaces

We apply Monte Carlo Renormalization group to the crumpling transition in random surface models of fixed connectivity. This transition is notoriously difficult to treat numerically. We employ here a Fourier accelerated Langevin algorithm in conjunction with a novel blocking procedure in momentum space which has proven extremely successful in $\lambda\phi^4$. We perform two successive renormalizations in lattices with up to $64^2$ sites. We obtain a result for the critical exponent $\nu$ in general agreement with previous estimates and similar error bars, but with much less computational effort. We also measure with great accuracy $\eta$. As a by-product we are able to determine the fractal dimension $d_H$ of random surfaces at the crumpling transition.Comment: 35 pages,Latex file, 6 Postscript figures uuencoded,uses psfig.sty 2 misspelled references corrected and one added. Paper unchange