Scattering of gravitational radiation: second order moments of the wave amplitude

Gravitational radiation that propagates through an inhomogeneous mass distribution is subject to random gravitational lensing, or scattering, causing variations in the wave amplitude and temporal smearing of the signal. A statistical theory is constructed to treat these effects. The statistical properties of the wave amplitude variations are a direct probe of the power spectrum of the mass distribution through which the waves propagate. Scattering temporally smears any intensity variations intrinsic to a source emitting gravitational radiation, rendering variability on time scales shorter than the temporal smearing time scale unobservable, and potentially making the radiation much harder to detect. Gravitational radiation must propagate out through the mass distribution of its host galaxy before it can be detected at the Earth. Plausible models for the distribution of matter in an $L_*$ host galaxy suggest that the temporal smearing time scale is at least several milliseconds due to the gas content alone, and may be as large as a second if dark matter also scatters the radiation. The smearing time due to scattering by any galaxy interposed along the line of sight is a factor $\sim 10^5$ times larger. Gravitational scattering is an excellent probe of matter on parsec and sub-parsec scales, and has the potential to elucidate the nature of dark matter.Comment: A&A accepted, 19 pages, 4 fig

The Politics of Procedure: An Empirical Analysis of Motion Practice in Civil Rights Litigation Under the New Plausibility Standard

This Article attempts to assess, empirically, whether the Court’s introduction of the so-called “plausibility standard” in the context of civil pleadings has had a disparate impact on civil rights claims, particularly in employment and housing discrimination cases. In a previous study conducted by one of the co-authors of this Article, it was revealed that in a sample of employment and housing discrimination cases, courts were more likely to dismiss these cases based on the lack of specificity of the pleadings after the Court’s decision in Iqbal. Furthermore, that study also found, after Iqbal, a significant rise in both the number of reported decisions in such cases on motions challenging the specificity of the pleadings, as well as a significant rise in the number of decisions dismissing such actions. To describe these findings and explore their implications, this Article proceeds as follows. Part II provides a brief overview of the evolution of pleading standards, from the introduction of the federal rules to the issuance of Twombly and Iqbal. Part III will provide an overview of past studies on the impact of these decisions on litigation in the federal courts, explore some of the implications of the plausibility standard and the due process questions it raises. Part IV describes the methodology and findings of this study and explores some of the implications of these findings

Can Maxwell's equations be obtained from the continuity equation?

We formulate an existence theorem that states that given localized scalar and vector time-dependent sources satisfying the continuity equation, there exist two retarded fields that satisfy a set of four field equations. If the theorem is applied to the usual electromagnetic charge and current densities, the retarded fields are identified with the electric and magnetic fields and the associated field equations with Maxwell's equations. This application of the theorem suggests that charge conservation can be considered to be the fundamental assumption underlying Maxwell's equations.Comment: 14 pages. See the comment: "O. D. Jefimenko, Causal equations for electric and magnetic fields and Maxwell's equations: comment on a paper by Heras [Am. J. Phys. 76, 101 (2008)].

RELATION OF RHEUMATIC-LIKE CARDIAC LESIONS OF THE MOUSE TO LOCALIZATION OF GROUP A STREPTOCOCCAL CELL WALLS

Mice injected intraperitoneally with isolated cell wall fragments of Group A streptococci develop a carditis similar to that previously observed in mice injected with crude extracts of this organism. Neither the soluble cytoplasmic components of Group A streptococcal cells nor the nonfragmented cell walls produced carditis in this experimental model. Fluorescein and 125I-labeled antibodies specific for Group A streptococcal cell wall antigens were used to demonstrate that, for 5 wk after injection, cell wall material is localized around the sites of active lesions in the heart. In addition, the cell wall antigen accumulates in the liver, spleen, mediastinal lymph nodes, and the adjacent loose connective tissue, where it persists for at least 10 wk

Viticulture, Wine Production, And Agriculture In Armenia: Economic Sectors In Transition

This paper focuses on perhaps the oldest branches of economic activity of Armenia viticulture and wine production. Accounts of vines and wines in Armenia are part of a larger story of the country’s agriculture industry. This paper pulls together the historic landscape and present state of affairs of the industries, revealing the significant roles agriculture, viticulture and winemaking have played in shaping Armenia and that they continue to play in sustaining the country’s standard of living. From ancient roots, through a transitional era of privatization and into modern times, the story of agriculture as a whole, grape-growing specifically, and wine production in Ar- menia is one of survival much like that which characterizes the lives of the Armenian people themselves across scores of centuries

The general relativistic infinite plane

Uniform fields are one of the simplest and most pedagogically useful examples in introductory courses on electrostatics or Newtonian gravity. In general relativity there have been several proposals as to what constitutes a uniform field. In this article we examine two metrics that can be considered the general relativistic version of the infinite plane with finite mass per unit area. The first metric is the 4D version of the 5D "brane" world models which are the starting point for many current research papers. The second case is the cosmological domain wall metric. We examine to what extent these different metrics match or deviate from our Newtonian intuition about the gravitational field of an infinite plane. These solutions provide the beginning student in general relativity both computational practice and conceptual insight into Einstein's field equations. In addition they do this by introducing the student to material that is at the forefront of current research.Comment: Accepted for publication in the American Journal of Physic

Cross-Cultural Consumer Attitudes: A Case Of The Second-Hand Clothing Market In Armenia

Under the auspices of the Center for Business Research and Development (CBRD) at the American University of Armenia, and with contributions from assistants: Lusine Poghosyan; Armen Ginosyan; Christina Dombayan; and David Janibekyan, the authors of this article consider the issue of consumer attitudes in Armenia with respect to second-hand clothing. Results of an informal public poll in Yerevan, the country’s capital, and a rendering of an historical perspective on Armenia’s economy provide a backdrop for discourse on what appears to be a slight shift of consumer attitude away from a relatively negative bias against the purchase of second-hand clothing when compared to that evidenced broadly in the United States

Prediction and measurement of radiation damage to CMOS devices on board spacecraft

The CMOS Radiation Effects Measurement (CREM) experiment is presently being flown on the Explorer-55. The purpose of the experiment is to evaluate device performance in the actual space radiation environment and to correlate the respective measurements to on-the-ground laboratory irradiation results. The experiment contains an assembly of C-MOS and P-MOS devices shielded in front by flat slabs of aluminum and by a practically infinite shield in the back. Predictions of radiation damage to C-MOS devices are based on standard environment models and computational techniques. A comparison of the shifts in CMOS threshold potentials, that is, those measured in space to those obtained from the on-the-ground simulation experiment with Co-60, indicates that the measured space damage is smaller than predicted by about a factor of 2-3 for thin shields, but agrees well with predictions for thicker shields

Two Examples of Circular Motion for Introductory Courses in Relativity

The circular twin paradox and Thomas Precession are presented in a way that makes both accessible to students in introductory relativity courses. Both are discussed by examining what happens during travel around a polygon and then in the limit as the polygon tends to a circle. Since relativistic predictions based on these examples can be verified in experiments with macroscopic objects such as atomic clocks and the gyroscopes on Gravity Probe B, they are particularly convincing to introductory students.Comment: Accepted by the American Journal of Physics This version includes revision