Inflaton two-point correlation in the presence of a cosmic string

Precise measurements of the microwave background anisotropy have confirmed the inflationary picture of approximately scale invariant, Gaussian primordial adiabatic density perturbations. However, there are some anomalies that suggest a small violation of rotational and/or translational invariance in the mechanism that generates the primordial density fluctuations. Motivated by this we study the two-point correlation of a massless scalar (the inflaton) when the stress tensor contains the energy density from an infinitely long straight cosmic string in addition to a cosmological constant

Rent Appropriation in Strategic Alliances: A Study of Technical Alliances in Pharmaceutical Industry

Many existing alliance studies have investigated how embedded relations create superior value for organizations. The role of network structure in rent appropriation or pie splitting, however, has been underexplored. We propose that favorable locations in interorganizational networks provide firms with superior opportunities for appropriating more economic benefits from alliances than their partners do. Specifically, we argue that partners’ asymmetric network positions will lead to unequal brokerage positions that promote disparate levels of information gathering, monitoring, and bargaining power, which lead to differing capacities to appropriate value. This in turn results in variations in market performance. We also propose this brokerage position exacerbates existing inequalities such as commercial capital; thus, available firm resources will moderate such network effects. Evidence is presented in the form of market response to technology alliance announcements from a set of pharmaceutical firms. In general, we find that firms within central network positions and those spanning structural holes have higher returns than their partners. In addition, we show that this relationship is contingent upon available firm resources

Silent reading of direct versus indirect speech activates voice-selective areas in the auditory cortex

In human communication, direct speech (e.g., Mary said: “I'm hungry”) is perceived to be more vivid than indirect speech (e.g., Mary said [that] she was hungry). However, for silent reading, the representational consequences of this distinction are still unclear. Although many of us share the intuition of an “inner voice,” particularly during silent reading of direct speech statements in text, there has been little direct empirical confirmation of this experience so far. Combining fMRI with eye tracking in human volunteers, we show that silent reading of direct versus indirect speech engenders differential brain activation in voice-selective areas of the auditory cortex. This suggests that readers are indeed more likely to engage in perceptual simulations (or spontaneous imagery) of the reported speaker's voice when reading direct speech as opposed to meaning-equivalent indirect speech statements as part of a more vivid representation of the former. Our results may be interpreted in line with embodied cognition and form a starting point for more sophisticated interdisciplinary research on the nature of auditory mental simulation during reading

A molecular-dynamics algorithm for mixed hard-core/continuous potentials

We present a new molecular-dynamics algorithm for integrating the equations of motion for a system of particles interacting with mixed continuous/impulsive forces. This method, which we call Impulsive Verlet, is constructed using operator splitting techniques similar to those that have been used successfully to generate a variety molecular-dynamics integrators. In numerical experiments, the Impulsive Verlet method is shown to be superior to previous methods with respect to stability and energy conservation in long simulations.Comment: 18 pages, 6 postscript figures, uses rotate.st

Nonlinear Aggregation-Diffusion Equations: Radial Symmetry and Long Time Asymptotics

We analyze under which conditions equilibration between two competing effects, repulsion modeled by nonlinear diffusion and attraction modeled by nonlocal interaction, occurs. This balance leads to continuous compactly supported radially decreasing equilibrium configurations for all masses. All stationary states with suitable regularity are shown to be radially symmetric by means of continuous Steiner symmetrization techniques. Calculus of variations tools allow us to show the existence of global minimizers among these equilibria. Finally, in the particular case of Newtonian interaction in two dimensions they lead to uniqueness of equilibria for any given mass up to translation and to the convergence of solutions of the associated nonlinear aggregation-diffusion equations towards this unique equilibrium profile up to translations as $t\to\infty$

The XYZs of Charmonium at BES

This contribution reviews some recent developments in charmonium spectroscopy, and discusses related theoretical predictions. The spectrum of states, strong decays of states above open charm threshold, electromagnetic transitions, and issues related to the recent discoveries of the "XYZ" states are discussed. Contributions that BES can make to our understanding of charmonium and related states are stressed in particular.Comment: 5 pages, 1 eps figure. Invited contribution to the International Workshop on Tau-Charm Physics Charm2006 (5-7 June 2006, Beijing, China