An Inventory of Disability Information for the Population Living in Institutions

The population living in institutions is excluded from most major national surveys. We evaluate the implications of this exclusion for disability statistics and research by compiling and examining existing disability information for the population living in institutions, with an emphasis on working-age people. The population living in institutions is a very small share of the entire population, but increased considerably from 1990 to 2000, especially for those ages 18-64. Working-age people accounted for a much larger proportion of the population living in institutions in 2000 (56 percent) than in 1990 (45 percent). As of 2000, 86 percent of the institutionalized working-age population resided in correctional institutions, and the remaining 14 percent were approximately evenly split between nursing homes and other institutions, many of which specialize in care for people with disabilities. When disability is defined as having at least one of the four disabilities in the 2000 Census—self-care, mental, physical, or sensory disabilities—the vast majority of the population with disabilities lives in household units; 8.7 percent live in group quarters (GQs), 6.4 percent live in institutional GQs, and 2.3 percent in non-institutional GQs. For working-age people with disabilities, the share of males living in institutional GQs is much larger than the share of females (7.7 percent versus 1.7 percent), in part reflecting the fact that more than nine out of ten inmates in correctional institutions are male. Working-age people with disabilities residing in institutional GQs are also disproportionately African American (38.6 percent of those ages 18-49 and 22.4 percent of those ages 50-64). Increased incarceration rates and the relatively high prevalence of disability in the incarcerated population suggest that growth in incarceration could have a substantial impact on disability prevalence in the household population, and on the characteristics of the household population with disabilities, most notably for young male African Americans. The nursing home residence rate declined for all age groups, but for those under 65 the decline is very small relative to the size of all persons in that age group, and thus seems unlikely to have much impact on disability statistics for the household population. We found no surveys covering the population living in institutions other than correctional institutions and nursing homes. The lack of information on this population may present a substantial problem for disability statistics and research

Income Security for Workers: A Stressed Support System in Need of Innovation

The current mix of public and private programs to support workers after they experience disability onset provides benefits to millions of workers and former workers. Yet, despite the large and growing costs of these programs, the inflation-adjusted household incomes of workers with disabilities have been falling for over two decades, both absolutely and, especially, relative to the incomes of those without disabilities. The aging of the baby boom generation is likely to make matters worse, and the government’s fiscal circumstance will make it increasingly difficult to sustain existing public programs. Current public policy initiatives might eventually improve the disability support system, but they are not likely to ward off the adverse consequences of the pending crisis. Policy changes that leverage existing private sector practices and capabilities might achieve greater success, but have received little attention and are far from proven

Wave fields from an off-center explosion in an embedded solid sphere

This study investigates the effects of explosions in asymmetric source regions on the excitation of seismic body waves. We give an analytic formulation for determining the wave fields from an off-center explosion in an embedded solid sphere in an elastic whole-space. As expected, this geometry generates shear as well as compressional body waves. The calculated wave fields show that the degree of shear-wave generation is determined by the asymmetry of the source region. The results are compared with the known analytic solutions of an explosion in an elastic whole-space and at the center of an elastic sphere embedded in the whole-space. The radiation patterns at different periods for different parameters of the media suggest that the asymmetry of the source region has significant effects on shorter period but has only minor effects on long periods. The long-period P-to-S wave maximum amplitude results are in agreement with that for explosions in axisymmetric cavities

Refractive Geometry for Underwater Domes

Underwater cameras are typically placed behind glass windows to protect them from the water. Spherical glass, a dome port, is well suited for high water pressures at great depth, allows for a large field of view, and avoids refraction if a pinhole camera is positioned exactly at the sphere’s center. Adjusting a real lens perfectly to the dome center is a challenging task, both in terms of how to actually guide the centering process (e.g. visual servoing) and how to measure the alignment quality, but also, how to mechanically perform the alignment. Consequently, such systems are prone to being decentered by some offset, leading to challenging refraction patterns at the sphere that invalidate the pinhole camera model. We show that the overall camera system becomes an axial camera, even for thick domes as used for deep sea exploration and provide a non-iterative way to compute the center of refraction without requiring knowledge of exact air, glass or water properties. We also analyze the refractive geometry at the sphere, looking at effects such as forward- vs. backward decentering, iso-refraction curves and obtain a 6th-degree polynomial equation for forward projection of 3D points in thin domes. We then propose a pure underwater calibration procedure to estimate the decentering from multiple images. This estimate can either be used during adjustment to guide the mechanical position of the lens, or can be considered in photogrammetric underwater applications

Refractive Geometry for Underwater Domes

Underwater cameras are typically placed behind glass windows to protect them from the water. Spherical glass, a dome port, is well suited for high water pressures at great depth, allows for a large field of view, and avoids refraction if a pinhole camera is positioned exactly at the sphere’s center. Adjusting a real lens perfectly to the dome center is a challenging task, both in terms of how to actually guide the centering process (e.g. visual servoing) and how to measure the alignment quality, but also, how to mechanically perform the alignment. Consequently, such systems are prone to being decentered by some offset, leading to challenging refraction patterns at the sphere that invalidate the pinhole camera model. We show that the overall camera system becomes an axial camera, even for thick domes as used for deep sea exploration and provide a non-iterative way to compute the center of refraction without requiring knowledge of exact air, glass or water properties. We also analyze the refractive geometry at the sphere, looking at effects such as forward- vs. backward decentering, iso-refraction curves and obtain a 6th-degree polynomial equation for forward projection of 3D points in thin domes. We then propose a pure underwater calibration procedure to estimate the decentering from multiple images. This estimate can either be used during adjustment to guide the mechanical position of the lens, or can be considered in photogrammetric underwater applications