University of Utah

About: University of Utah is a education organization based out in Salt Lake City, Utah, United States. It is known for research contribution in the topics: Population & Medicine. The organization has 52894 authors who have published 124076 publications receiving 5265834 citations. The organization is also known as: The U & The University of Utah.

UNC-13 is required for synaptic vesicle fusion in C. elegans

Abstract: We analyzed the synaptic physiology of unc-13 mutants in the nematode C. elegans. Mutants of unc-13 had normal nervous system architecture, and the densities of synapses and postsynaptic receptors were normal at the neuromuscular junction. However, the number of synaptic vesicles at neuromuscular junctions was two- to threefold greater in unc-13 mutants than in wild-type animals. Most importantly, evoked release at both GABAergic and cholinergic synapses was almost absent in unc-13 null alleles, as determined by whole-cell, voltage-clamp techniques. Although mutant synapses had morphologically docked vesicles, these vesicles were not competent for release as assayed by spontaneous release in calcium-free solution or by the application of hyperosmotic saline. These experiments support models in which UNC-13 mediates either fusion of vesicles during exocytosis or priming of vesicles for fusion.

Trace Anomalies and the Hawking Effect

Abstract: The general spherically symmetric, static solution of ${\ensuremath{ abla}}_{\ensuremath{ u}}{T}_{\ensuremath{\mu}}^{\ensuremath{ u}} = 0$ in the exterior Schwarzschild metric is expressed in terms of two integration constants and two arbitrary functions, one of which is the trace of ${T}_{\ensuremath{\mu}\ensuremath{ u}}$. One constant is the magnitude of ${T}_{\mathrm{tr}}$ at infinity, and the other is determined if the physically normalized components of ${T}_{\ensuremath{\mu}\ensuremath{ u}}$ are finite on the future horizon. The trace of the stress tensor of a conformally invariant quantum field theory may be nonzero (anomalous), but must be proportional (here) to the Weyl scalar, $48{M}^{2}{r}^{\ensuremath{-}6}$; we fix the coefficient for the scalar field by indirect arguments to be ${(2880{\ensuremath{\pi}}^{2})}^{\ensuremath{-}1}$. In the two-dimensional analog, the magnitude of the Hawking blackbody effect at infinity is directly proportional to the magnitude of the anomalous trace (a multiple of the curvature scalar); a knowledge of either number completely determines the stress tensor outside a body in the final state of collapse. In four dimensions, one obtains instead a relation constraining the remaining undetermined function, which we choose as ${T}_{\ensuremath{\theta}}^{\ensuremath{\theta}}\ensuremath{-}\frac{{T}_{\ensuremath{\alpha}}^{\ensuremath{\alpha}}}{4}$. This, plus additional physical and mathematical considerations, leads us to a fairly definite, physically convincing qualitative picture of $〈{T}_{\ensuremath{\mu}\ensuremath{ u}}〉$. Groundwork is laid for explicit calculations of $〈{T}_{\ensuremath{\mu}\ensuremath{ u}}〉$.