Space telescope phase B definition study. Volume 2A: Science instruments, f24 field camera

The analysis and design of the F/24 field camera for the space telescope are discussed. The camera was designed for application to the radial bay of the optical telescope assembly and has an on axis field of view of 3 arc-minutes by 3 arc-minutes

Local Density of States and Angle-Resolved Photoemission Spectral Function of an Inhomogeneous D-wave Superconductor

Nanoscale inhomogeneity seems to be a central feature of the d-wave superconductivity in the cuprates. Such a feature can strongly affect the local density of states (LDOS) and the spectral weight functions. Within the Bogoliubov-de Gennes formalism we examine various inhomogeneous configurations of the superconducting order parameter to see which ones better agree with the experimental data. Nanoscale large amplitude oscillations in the order parameter seem to fit the LDOS data for the underdoped cuprates. The one-particle spectral function for a general inhomogeneous configuration exhibits a coherent peak in the nodal direction. In contrast, the spectral function in the antinodal region is easily rendered incoherent by the inhomogeneity. This throws new light on the dichotomy between the nodal and antinodal quasiparticles in the underdoped cuprates.Comment: 5 pages, 9 pictures. Phys. Rev. B (in press

The Preemption of Collective State Antitrust Enforcement In Telecommunications

The dichotomy between the levels of government provided murky guidance to telecommunications firms on what behavior is anticompetitive and what decisions firms will have to spend years defending. Despite T-Mobile and Sprint agreeing to sell off several subsidiaries, helping to create a new competitor, and surviving a gamut of regulatory reviews, these companies still could not merge. At this point, preventing the deal would cause irreversible harm to the merging parties. The conflicts that arose in the T-Mobile-Sprint merger could have been solved through the preemption of collective state antitrust enforcement in the telecommunications market, which would balance the twin goals of promoting the consumer and aggregate social welfares. The telecommunications market is subject to substantial federal scrutiny and regulation, which limits competitive choices to an abnormal degree and causes the market to suffer extraordinary damage when collective states interject themselves as enforcers. Limiting state antitrust activities is not a novel concept, with a variety of studies arguing that the inefficiencies and competing interests associated with state action substantially hamper state antitrust enforcement of national markets. This Comment does not presume to redefine the antitrust system in its entirety, but narrowly applies the possibility of preempting state action to the telecommunications market

Fermion Soliton Stars with Asymmetric Vacua

Fermion soliton stars are a motivated model of exotic compact objects in which a nonlinear self-interacting real scalar field couples to a fermion via a Yukawa term, giving rise to an effective fermion mass that depends on the fluid properties. Here we continue our investigation of this model within General Relativity by considering a scalar potential with generic asymmetric vacua. This case provides fermion soliton stars with a parametrically different scaling of the maximum mass relative to the model parameters, showing that the special case of symmetric vacua, in which we recover our previous results, requires fine tuning. In the more generic case studied here the mass and radius of a fermion soliton star are comparable to those of a neutron star for natural model parameters at the GeV scale. Finally, the asymmetric scalar potential inside the star can provide either a positive or a negative effective cosmological constant in the interior, being thus reminiscent of gravastars or anti-de Sitter bubbles, respectively. In the latter case we find the existence of multiple, disconnected, branches of solutions.Comment: 9 pages, 7 figures. v2: matches version accepted in PR

Transporting Bits or Transporting Energy: Does it matter? A comparison of the sustainability of local and remote computing

This document presents the results of a study of the sustainability of data management and data movement between data centres, the ultimate goal being to minimize the CO2 footprint