Why Do People Lack Health Insurance?

Currently, 46 million people or nearly one in five nonelderly adults and children lack health insurance in the United States, an increase of 6 million since 2000. The recent rise in uninsurance has been attributed to a number of factors, including rising health care costs, the economic downturn, an erosion of employer-based insurance, and public program cutbacks. Developing effective strategies for reducing uninsurance requires understanding why people lack insurance coverage. This brief looks at the reasons people report being uninsured overall and by key population subgroups (defined by age, race/ethnicity, health status, and family and employment characteristics). We also examine how those reasons have changed over time

Crash Analysis and Energy Absorption Characteristics of S-shaped Longitudinal Members

This paper presents finite element simulations of the crash behavior and the energy absorption characteristics of thin S-shaped longitudinal members with variable cross-sections made of different materials to investigate the design of optimized energy-absorbing members. Numerical studies are carried out by simulation via the explicit finite element code LS-DYNA [1] to determine the desired variables for the design of energy-absorbing members. The specific energy absorption (SEA), the weight of the members and the peak force responses during the frontal impact are the main measurements of the S-shaped members' performance. Several types of inner stiffening members are also investigated to determine the influence of the additional stiffness on the crash behavior

Endogenizing Growth via a Lag for Apprenticing

We take up a growth model with both skilled and unskilled labor, and a steady migration of some unskilled workers, who undertake apprenticing, to the skilled group of workers. Apprenticing involves a period of observing and thus labor output foregone. The time-out for observing represents a cost to the economy and this results in the rate of balanced growth being endogenous. We examine the balanced growth path and report on the stability of our dynamic system.skilled and unskilled labor, apprenticing, balanced growth, endogenous growth

Ultrasensitive detections in atomic and molecular physics: demonstration in molecular overtone spectroscopy

We consider several highly sensitive techniques commonly used in detection of atomic and molecular absorptions. Their basic operating principles and corresponding performances are summarized and compared. We then present our latest results on the ultrasensitive detection of molecular overtone transitions to illustrate the principle and application of the cavity-enhanced frequency-modulation (FM) spectroscopy. An external cavity is used to enhance the molecular response to the light field, and an FM technique is applied for shot-noise-limited signal recovery. A perfect match between the FM sideband frequency and the cavity free spectral range makes the detection process insensitive to the laser-frequency noise relative to the cavity, and, at the same time, overcomes the cavity bandwidth limit. Working with a 1.064-µm Nd:YAG laser, we obtained sub-Doppler overtone resonances of C2HD, C2H2, and CO2 molecules. A detection sensitivity of 5 x 10^-13 of integrated absorption (1 x 10^-14/cm) over 1-s averaging time has been achieved

Taber Vibration Isolator for Vacuum and Cryogenic Applications

We present a procedure for the design and construction of a passive, multipole, mechanical high-stop vibration isolator. The isolator, consisting of a stack of metal disks connected by thin wires, attenuates frequencies in the kilohertz range, and is suited to both vacuum and cryogenic environments. We derive an approximate analytical model and compare its predictions for the frequencies of the normal modes to those of a finite element analysis. The analytical model is exact for the modes involving only motion along and rotation about the longitudinal axis, and it gives a good approximate description of the transverse modes. These results show that the high-frequency behavior of a multi-stage isolator is well characterized by the natural frequencies of a single stage. From the single-stage frequency formulae, we derive relationships among the various geometrical parameters of the isolator to guarantee equal attenuation in all degrees of freedom. We then derive expressions for the attenuation attainable with a given isolator length, and find that the most important limiting factor is the elastic limit of the spring wire material. For our application, which requires attenuations of 250 dB at 1 kHz, our model specifies a six-stage design using brass disks of approximately 2 cm in both radius and thickness, connected by 3 cm steel wires of diameters ranging from 25 to 75 microns. We describe the construction of this isolator in detail, and compare measurements of the natural frequencies of a single stage with calculations from the analytical model and the finite element package. For translations along and rotations about the longitudinal axes, all three results are in agreement to within 10% accuracy.Comment: 11 pages, 13 figures, REVTe