New exact solutions for power-law inflation Friedmann models

We consider the spatially flat Friedmann model. For a(t) = t^p, especially, if p is larger or equal to 1, this is called power-law inflation. For the Lagrangian L = R^m with p = - (m - 1)(2m - 1)/(m - 2), power-law inflation is an exact solution, as it is for Einstein gravity with a minimally coupled scalar field Phi in an exponential potential V(Phi) = exp(mu Phi) and also for the higher-dimensional Einstein equation with a special Kaluza-Klein ansatz. The synchronized coordinates are not adapted to allow a closed-form solution, so we use another gauge. Finally, special solutions for the closed and open Friedmann model are found.Comment: 9 pages, LaTeX, reprinted from Astron. Nachr. 311 (1990) 16

Do Community-Based Corrections Have an Effect on Recidivism Rates? A Review of Community Supervision, Supportive Reintegration, Electronic Monitoring Programs and Their Impacts on Reducing Reoffending

This paper will examine the impact and effect community-based corrections have on the reduction of recidivism for adult offenders. More specifically, I will focus on three commonly used types of such corrections in the United States: community supervision, supportive reintegration, and electronic monitoring. I propose that these community-based correctional programs will reduce reoffending rates. I will first provide a theoretical perspective to provide a foundational support, followed by a background of community-based corrections and their usage in contemporary American courts. I will then review the research regarding community supervision, supportive reintegration, and electronic monitoring, and discuss how these programs affect recidivism, how they may be improved, and implications for future research. Offender-community integration is more relevant than ever as prison populations continue to increase and more inmates are being released back into society (U.S. Department of Justice 2009). Community-based corrections, if utilized appropriately and efficiently, have the potential to decrease overcrowded prisons, be more cost-effective than incarceration, and reduce reoffending rates (Bouffard and Muftic 2006)

On the infinite particle limit in Lagrangian dynamics and convergence of optimal transportation meshfree methods

We consider Lagrangian systems in the limit of infinitely many particles. It is shown that the corresponding discrete action functionals Gamma-converge to a continuum action functional acting on probability measures of particle trajectories. Also the convergence of stationary points of the action is established. Minimizers of the limiting functional and, more generally, limiting distributions of stationary points are investigated and shown to be concentrated on orbits of the Euler-Lagrange flow. We also consider time discretized systems. These results in particular provide a convergence analysis for optimal transportation meshfree methods for the approximation of particle flows by finite discrete Lagrangian dynamics

Of maps and scripts:The status of formal constructs in cooperative work

Abstract. The received understanding of the status of formal organizational constructs in cooperative work is problematic. The paper shows that the empirical evidence is not as strong as we may have believed and that there is evidence from other studies that contradicts what we may have taken for granted for years. This indicates that the role of formal con-structs is more differentiated than generally taken for granted. They not only serve as ‘maps ’ but also as ‘scripts’. of a different nature than presumed by the protagonists of office automation [e.g., 42; 45; 49]. The general conclusion of these studies were that such constructs, instead of determin-ing action causally, serve as ‘maps ’ which responsible and competent actors may consult to accomplish their work [8, p. 114; 43, p. 188 f.]. Thus, Lucy Suchman’s radical critique of cognitive science [43] and the ‘situated action ’ perspectiv

The Parabolic Anderson Model with Acceleration and Deceleration

We describe the large-time moment asymptotics for the parabolic Anderson model where the speed of the diffusion is coupled with time, inducing an acceleration or deceleration. We find a lower critical scale, below which the mass flow gets stuck. On this scale, a new interesting variational problem arises in the description of the asymptotics. Furthermore, we find an upper critical scale above which the potential enters the asymptotics only via some average, but not via its extreme values. We make out altogether five phases, three of which can be described by results that are qualitatively similar to those from the constant-speed parabolic Anderson model in earlier work by various authors. Our proofs consist of adaptations and refinements of their methods, as well as a variational convergence method borrowed from finite elements theory.Comment: 19 page

Derivation of a Sample of Gamma-Ray Bursts from BATSE DISCLA Data

We have searched for gamma-ray bursts (GRBs) in the BATSE DISCLA data over a time period of 5.9 years. We employ a trigger requiring an excess of at least 5 sigma over background for at least two modules in the 50-300 keV range. After excluding certain geographic locations of the satellite, we are left with 4485 triggers. Based on sky positions, we exclude triggers close to the sun, to Cyg X-1, to Nova Persei 1992 and the repeater SGR 1806-20, while these sources were active. We accept 1013 triggers that correspond to GRBs in the BATSE catalog, and after visual inspection of the time profiles classify 378 triggers as cosmic GRBs. We denote the 1391 GRBs so selected as the "BD2 sample". The BD2 sample effectively represents 2.003 years of full sky coverage for a rate of 694 GRBs per year. Euclidean V/Vmax values have been derived through simulations in which each GRB is removed in distance until the detection algorithm does not produce a trigger. The BD2 sample produces a mean value = 0.334 +- 0.008.Comment: 5 pages, 3 figures, Latex with aipproc.sty, Proc. of the 5th Huntsville Gamma Ray Burst Symposium, Oct. 1999, ed. R.M. Kippen, AI

Ring extensions invariant under group action

Let $G$ be a subgroup of the automorphism group of a commutative ring with identity $T$. Let $R$ be a subring of $T$ such that $R$ is invariant under the action by $G$. We show $R^G\subset T^G$ is a minimal ring extension whenever $R\subset T$ is a minimal extension under various assumptions. Of the two types of minimal ring extensions, integral and integrally closed, both of these properties are passed from $R\subset T$ to $R^G\subset T^G$. An integrally closed minimal ring extension is a flat epimorphic extension as well as a normal pair. We show each of these properties also pass from $R\subset T$ to $R^G\subseteq T^G$ under certain group action.Comment: Revisions: minor edits and results 4.9-4.11 removed due to error in 4.9; 15 pages; comments welcom