Description of Atmospheric Conditions at the Pierre Auger Observatory Using Meteorological Measurements and Models

Atmospheric conditions at the site of a cosmic ray observatory must be known well for reconstructing observed extensive air showers, especially when measured using the fluorescence technique. For the Pierre Auger Observatory, a sophisticated network of atmospheric monitoring devices has been conceived. Part of this monitoring was a weather balloon program to measure atmospheric state variables above the Observatory. To use the data in reconstructions of air showers, monthly models have been constructed. Scheduled balloon launches were abandoned and replaced with launches triggered by high-energetic air showers as part of a rapid monitoring system. Currently, the balloon launch program is halted and atmospheric data from numerical weather prediction models are used. A description of the balloon measurements, the monthly models as well as the data from the numerical weather prediction are presented

Tubule density at different sample sites around the stratum medium of horse hoof horn

Microscopic analysis shows that equine hoof wall is composed of distinct phases of tubular and intertubular horn. The tubule density (TD) of hoof horn is found by ascertaining the number of tubules per unit area and is believed to relate to mechanical properties, resistance to wear, “quality”, hardness and moisture content. The straight grid previously used to ascertain the TD of hoof horn may omit certain tubules on both the inner and outer hoof wall as the wall itself is curved. This present study examined whether there was a significant difference in results for TD between using the conventional straight grid method and a novel method using a curved grid. TD was also compared across three sample sites. An analysis of TD from four equal sections (zones) across the hoof wall was also carried out

Nonlinear, relativistic Langmuir waves in astrophysical magnetospheres

Large amplitude, electrostatic plasma waves are relevant to physical processes occurring in the astrophysical magnetospheres wherein charged particles are accelerated to relativistic energies by strong waves emitted by pulsars, quasars, or radio galaxies. The nonlinear, relativistic theory of traveling Langmuir waves in a cold plasma is reviewed. The cases of streaming electron plasma, electronic plasma, and two-streams are discussed

On-off intermittency and amplitude-phase synchronization in Keplerian shear flows

We study the development of coherent structures in local simulations of the magnetorotational instability in accretion discs in regimes of on-off intermittency. In a previous paper [Chian et al., Phys. Rev. Lett. 104, 254102 (2010)], we have shown that the laminar and bursty states due to the on-off spatiotemporal intermittency in a one-dimensional model of nonlinear waves correspond, respectively, to nonattracting coherent structures with higher and lower degrees of amplitude-phase synchronization. In this paper we extend these results to a three-dimensional model of magnetized Keplerian shear flows. Keeping the kinetic Reynolds number and the magnetic Prandtl number fixed, we investigate two different intermittent regimes by varying the plasma beta parameter. The first regime is characterized by turbulent patterns interrupted by the recurrent emergence of a large-scale coherent structure known as two-channel flow, where the state of the system can be described by a single Fourier mode. The second regime is dominated by the turbulence with sporadic emergence of coherent structures with shapes that are reminiscent of a perturbed channel flow. By computing the Fourier power and phase spectral entropies in three-dimensions, we show that the large-scale coherent structures are characterized by a high degree of amplitude-phase synchronization.Comment: 17 pages, 10 figure

Length of Service and the Operation of Internal Labor Markets

This paper presents a summary of the evidence which has recently been collected concerning the role of length of service in the operation of internal labor markets. It argues that these data are inconsistent with the human capital model of the experience-earnings and experience-layoff relationships. The paper concludes by asserting that if we are ever to fully understand the role of service, newdata are needed.

The non-linearity between <ln A> and <Xmax> induced by the acceptance of fluorescence telescopes

The measurement of the average depth of the shower maximum is the most commonly used observable for the possible inference of the primary cosmic-ray mass composition. Currently, different experimental Collaborations process and present their data not in the same way, leading to problems in the comparability and interpretation of the results. Whereas is expected to be proportional to in ideal conditions, we demonstrate that the finite field-of-view of fluorescence telescopes plus the attenuation in the atmosphere can introduce a non-linearity into this relation, which is specific for each particular detector setup

Years of Service and Probability of Promotion

This study provides evidence which we believe challenges some conventional assumptions about the promotion process. Based on survey information collected from a large random sample of U.S. private sector firms, we reach two main conclusions. First,seniority independent of productivity appears to play a significant role even in nonunion promotion decisions. Second, the differences between union and nonunion promotion processes, at least with regard to the weight assigned to seniority per se, appear to be important but less dramatic than is popularly supposed.

Searching for an anomalous tˉqγ\bar t q \gamma coupling via single top quark production at a γγ\gamma\gamma collider

We investigate the potential of a high-energy $\gamma\gamma$ collider to detect an anomalous $\bar t q \gamma$ coupling from observation of the reaction $\gamma \gamma \to t\bar q$, $\bar t q$, where $q=c$ or $u$. We find that with $b$-tagging and suitable kinematic cuts this process should be observable if the anomalous coupling $\kappa/\Lambda$ is no less than about 0.05/TeV, where $\Lambda$ is the scale of new physics associated with the anomalous interaction. This improves upon the bound possible from observation of top decays at the Tevatron.Comment: 13 pages, RevTeX, 1 PS figur

Length of Service, Terminations and the Nature of the Employment Relationship

This paper presents new survey evidence that relative protection against job loss grows with length of service, independent of their net value to the firm. This protection makes good sense given that at most companies employees appear to earn less than their value marginal product in the early part of their tenure and more than their value marginal product in the latter part; without job protection policies for senior employees, the firm would have an incentive to terminate them when their "spot" earnings went above their "spot" value marginal product. In particular, we find that a very large percentage (over 95 percent) of hourly union members outside of agriculture and construction are covered by protective policies for senior workers and, that a somewhat smaller, but still substantial, percentage (about 85 percent) of comparable nonunion hourlies also have some protection against jobloss in their senior years. The potential reasons for these findings are briefly discussed.