Charge and the topology of spacetime

A new class of electrically charged wormholes is described in which the outer 2-sphere is not spanned by a compact, co-orientable hypersurface, These wormholes can therefore display net electric charge from the source-free Maxwell equations. This extends the work of Sorkin on non-space-orientable manifolds, to spacetimes which do not admit a time orientation. The work is motivated by the suggestion that quantum theory can be explained by modelling elementary particles as regions of spacetime with non-trivial causal structure. The simplest example of an electrically charged spacetime carries a spherical symmetry

Symplectomorphism group relations and degenerations of Landau-Ginzburg models

In this paper, we describe explicit relations in the symplectomorphism groups of toric hypersurfaces. To define the elements involved, we construct a proper stack of toric hypersurfaces with compactifying boundary representing toric hypersurface degenerations. Our relations arise through the study of the one dimensional strata of this stack. The results are then examined from the perspective of homological mirror symmetry where we view sequences of relations as maximal degenerations of Landau-Ginzburg models. We then study the B-model mirror to these degenerations, which gives a new mirror symmetry approach to the minimal model program.Comment: 100 pages, 24 figure

The splashback radius as a physical halo boundary and the growth of halo mass

The boundaries of cold dark matter halos are commonly defined to enclose a density contrast $\Delta$ relative to a reference (mean or critical) density. We argue that a more physical boundary of halos is the radius at which accreted matter reaches its first orbital apocenter after turnaround. This splashback radius, $R_{sp}$, manifests itself as a sharp density drop in the halo outskirts, at a location that depends upon the mass accretion rate. We present calibrations of $R_{sp}$ and the enclosed mass, $M_{sp}$, as a function of the accretion rate and alternatively peak height. We find that $R_{sp}$ varies between $\approx0.8-1R_{200m}$ for rapidly accreting halos and $\approx1.5R_{200m}$ for slowly accreting halos. The extent of a halo and its associated environmental effects can thus extend well beyond the conventionally defined "virial" radius. We show that $M_{sp}$ and $R_{sp}$ evolve relatively strongly compared to other commonly used definitions. In particular, $M_{sp}$ evolves significantly even for the smallest dwarf-sized halos at $z=0$. We also contrast $M_{sp}$ with the mass enclosed within four scale radii of the halo density profile, $M_{<4rs}$, which characterizes the inner halo. During the early stages of halo assembly, $M_{sp}$ and $M_{<4rs}$ evolve similarly, but in the late stages $M_{<4rs}$ stops increasing while $M_{sp}$ continues to grow significantly. This illustrates that halos at low $z$ can have "quiet" interiors while continuing to accrete mass in their outskirts. We discuss potential observational estimates of the splashback radius and show that it may already have been detected in galaxy clusters.Comment: 15 pages, 12 figures, comments most welcom

The Use of Telemetry Monitoring Among General Medicine Patients

Objective: To determine why and when general medicine non-ICU patients are upgraded from a non-telemetry level of care to telemetry monitoring at Thomas Jefferson University Hospital (TJUH). Comparison of the reasons for initiation of continuous ECG monitoring with the AHA and ACC guidelines would provide a greater understanding of the applicability of these recommendations to non-ICU general medicine patients. This information can provide guidance to identify areas of intervention to decrease inappropriate and/or overutilization of telemetry. The ultimate goal is to identify general medicine patients who are likely to benefit from continuous ECG monitoring, without negatively affecting clinical outcomes for those who do not receive cardiac monitoring.https://jdc.jefferson.edu/patientsafetyposters/1025/thumbnail.jp

Supersymmetric rotating black hole spacetime tested by geodesics

We present the complete analytical solution of the geodesics equations in the supersymmetric BMPV spacetime \cite{Breckenridge:1996is}. We study systematically the properties of massive and massless test particle motion. We analyze the trajectories with analytical methods based on the theory of elliptic functions. Since the nature of the effective potential depends strongly on the rotation parameter $\omega$, one has to distinguish between the underrotating case, the critical case and the overrotating case, as discussed by Gibbons and Herdeiro in their pioneering study \cite{Gibbons:1999uv}. We discuss various properties which distinguish this spacetime from the classical relativistic spacetimes like Schwarzschild, Reissner-Nordstr\"om, Kerr or Myers-Perry. The overrotating BMPV spacetime allows, for instance, for planetary bound orbits for massive and massless particles. We also address causality violation as analyzed in \cite{Gibbons:1999uv}.Comment: 37 pages, 27 figure