28,566 research outputs found

    How Pay and Benefits Change as Job Level Rises: Data from the National Compensation Survey

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    [Excerpt] The Bureau of Labor Statistics (BLS) National Compensation Survey (NCS) is the key source of data on the pay and benefits of workers in the United States. The NCS uses data on employer costs for a variety of compensation components to produce the Employer Cost Index (ECI) and Employer Cost of Employee Compensation (ECEC) on a quarterly basis. The ECI provides an index of changes in the employer’s cost of wages and compensation from the prior quarter and prior year. The ECEC provides estimates of wages and salaries as well as average cost of benefits per hour worked, shown in dollars and cents. On an annual basis, the NCS produces information on the availability of a suite of benefits, including health, retirement, insurance, and leave as part of the Employee Benefits Survey (EBS). This Beyond the Numbers article examines pay and benefits by job level to provide additional context to the nature of compensation among private sector workers in the United States

    The Mass Function of Cosmic Structures with Non-Spherical Collapse

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    Non-spherical dynamical approximations and models for the gravitational collapse are used to extend the well-known Press \& Schechter (PS) approach, in order to determine analytical expressions for the mass function of cosmic structures. The problem is rigorously set up by considering the intrinsic Lagrangian nature of the mass function. The Lagrangian equations of motion of a cold and irrotational fluid in single-stream regime show that the shear, which is non-locally determined by all the matter field, is the quantity which characterizes non-spherical perturbations. The Zel'dovich approximation, being a self-consistent first-order Lagrangian and local one, is used as a suitable guide to develop realistic estimates of the collapse time of a mass clump, starting from the local initial values of density and shear. Both Zel'dovich-based \an\ and models and the homogeneous ellipsoidal model predict that more large-mass objects are expected to form than the usual PS relation. In particular, the homogeneous ellipsoid model is consistent at large masses with a Press \& Schechter mass function with a lower value of the \dc\ parameter, in the range 1.4Ă·\div1.6. This gives a dynamical explanation of why lower \dc\ values have been found to fit the results of several N-body simulations. When more small-scale structure is present, highly non-linear dynamical effects can effectively slow down the collapse rate of a perturbation, increasing the effective value of \dc. This may have interesting consequences on the abundance of large-mass high-redshift objects.Comment: 16 pages+5 figures, uuencoded postscript file, submitted to Ap

    Morphological transformation of NGC 205?

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    NGC 205 is a dwarf elliptical galaxy which shows many features that are more typical of disk galaxies, and our recent study of the central stellar population has added another peculiarity. In the central regions, star formation has been on-going continuously for a few hundred Myr, until ca. 20 Myr ago, perhaps fed by gas funneled to the center in the course of morphological transformation. In this contribution we use a deep, wide-field image obtained at a scale of 2"/px to show that subtle structures can be detected in and near the body of the dwarf galaxy. The southern tidal tail can be mapped out to unprecedented distances from the center, and we suggest that the northern tail is partially hidden behind a very extended dust lane, or ring, belonging to M31. A spiral pattern emerges across the body of the galaxy, but it might be explained by another M31 dust filament.Comment: 2 pages, 1 figure, poster contributed to IAU Symposium 262, Stellar Populations -- Planning for the Next Decade, G. Bruzual & S. Charlot, ed

    Disability Insurance Plans: Trends in Employee Access and Employer Costs

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    [Excerpt] Short- and long-term disability insurance programs replace some of the wages lost by people who cannot work because of a disabling injury or illness that is not work-related. Short-term disability insurance typically covers periods lasting less than 6 months, and long-term disability insurance lasts for the length of the disability or until retirement. Those workers who are unable to work due to injury or illness and who do not have disability insurance coverage through their employers may seek benefits from Social Security Disability Insurance (SSDI). The number of SSDI claimants has grown over the past decade as younger workers and those in relatively low- skill, low-pay jobs have applied for benefits. This has prompted interest in the amount of coverage for workers in employer-provided disability insurance programs. This issue of Beyond the Numbers examines trends in employer- provided disability insurance coverage over time, explains the basic terms of coverage for typical plans, and estimates the costs to private employers

    A Lagrangian Dynamical Theory for the Mass Function of Cosmic Structures: I Dynamics

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    A new theory for determining the mass function of cosmic structures is presented. It relies on a realistic treatment of collapse dynamics. Gravitational collapse is analyzed in the Lagrangian perturbative framework. Lagrangian perturbations provide an approximation of truncated type, i.e. small-scale structure is filtered out. The collapse time is suitably defined as the instant at which orbit crossing takes place. The convergence of the Lagrangian series in predicting the collapse time of a homogeneous ellipsoid is demonstrated; it is also shown that third-order calculations are necessary in predicting collapse. Then, the Lagrangian prediction, with a correction for quasi-spherical perturbations, can be used to determine the collapse time of a homogeneous ellipsoid in a fast and precise way. Furthermore, ellipsoidal collapse can be considered as a particular truncation of the Lagrangian series. Gaussian fields with scale-free power spectra are then considered. The Lagrangian series for the collapse time is found to converge when the collapse time is not large. In this case, ellipsoidal collapse gives a fast and accurate approximation of the collapse time; spherical collapse is found to poorly reproduce the collapse time, even in a statistical sense. Analytical fits of the distribution functions of the inverse collapse times, as predicted by the ellipsoid model and by third-order Lagrangian theory, are given. These will be necessary for a determination of the mass function, which will be given in paper II.Comment: 18 pages, Latex, uses mn.sty and psfig, 7 postscript figures (fig. 2 and 3 not complete). Revised version, stylistic changes. MNRAS, in pres
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