33 research outputs found
The geometry of phase mixing
Partially phase-mixed structures in galaxies occupy a complex surface of
dimension D in six-dimensional phase space. The appearance of such structures
to observers is determined by their projection into a subspace whose
dimensionality K is determined by the number of observables (e.g. sky position,
distance, radial velocity, etc.). We discuss the expected dimensionality of
phase-space structures and suggest that the most prominent features in surveys
with K=D or K>D will be stable singularities (catastrophes). The simplest of
these are the shells seen in the outer parts of elliptical galaxies.Comment: 14 pages, Latex, 4 figures. Submitted to MNRA
Relativistic Effects of Light in Moving Media with Extremely Low Group Velocity
A moving dielectric medium acts as an effective gravitational field on light.
One can use media with extremely low group velocities [Lene Vestergaard Hau et
al., Nature 397, 594 (1999)] to create dielectric analogs of astronomical
effects on Earth. In particular, a vortex flow imprints a long-ranging
topological effect on incident light and can behave like an optical black hole.Comment: Physical Review Letters (accepted
Optics of Nonuniformly Moving Media
A moving dielectric appears to light as an effective gravitational field. At
low flow velocities the dielectric acts on light in the same way as a magnetic
field acts on a charged matter wave. We develop in detail the geometrical
optics of moving dispersionless media. We derive a Hamiltonian and a Lagrangian
to describe ray propagation. We elucidate how the gravitational and the
magnetic model of light propagation are related to each other. Finally, we
study light propagation around a vortex flow. The vortex shows an optical
Aharonov--Bohm effect at large distances from the core, and, at shorter ranges,
the vortex may resemble an optical black hole.Comment: Physical Review A (submitted
Implementing The Prison Rape Elimination Act: A Toolkit for Jails
Minor edits. “The goal of this Toolkit is to provide jails of all sizes, political divisions, and geographic locations with a step-by-step guide for preventing, detecting, and eliminating sexual abuse of inmates in their custody – and for responding effectively to abuse when it occurs. Prison rape includes all forms of inmate sexual abuse within a correctional facility, including state and federal prisons, county and municipal jails, police lock-ups, holding facilities, inmate transportation vehicles, juvenile detention facilities, and community corrections facilities. Protecting arrestees, detainees, and inmates from sexual violence is part of a jail’s core mission. This toolkit will help assess your jail’s operations with an eye to improvements.” The Toolkit is divided into folders holding materials related to: introductory information about PREA [Prison Rape Elimination Act] and it Standards; a Self-Assessment Checklist with supporting forms “to provide a step-by-step process for jails to review and assess policies, procedures, and practices in light of the PREA Standards and accepted best practices”; and additional resources to assist you in PREA-readiness
Risk state changes analysis of railway dangerous goods transportation system: Based on the cusp catastrophe model
Plasmodium CDP-DAG synthase: An atypical gene with an essential N-terminal extension
International audienc