1,375 research outputs found
Social Integration of Older Immigrants in 21st Century America
There are various reasons for the burgeoning interest in detailed research into the determinants of social well-being among older immigrants in this country. As a result of shifting federal government policies, the total volume of immigrants has increased significantly, the countries from which they migrate have changed, and more immigrant families have brought their parents into the United States than ever before. Consequently, the older adult population is becoming more diverse due in part to the aging-in-place of younger immigrants and an increasing number of immigrants who are older upon arrival in the United States. These trends create challenges for social service providers, who are encountering language and cultural differences among their clients for which they are unprepared. This report provides an overview of research about older adult immigrants in the United States that my colleagues and I have conducted over the past few years. Various demographic and cultural aspects of today's immigrants that differ from the past are described. The importance of social integration to older immigrants' well-being is considered. Then some intriguing research about the "new immigrants" is summarized and additional areas for future research are suggested.
RAXJET: A computer program for predicting transonic, axisymmetric flow over nozzle afterbodies with supersonic jet exhausts
A viscous-inviscid interaction method to calculate the subsonic and transonic flow over nozzle afterbodies with supersonic jet exhausts was developed. The method iteratively combines a relaxation solution of the full potential equation for the inviscid external flow, a shock capturing-shock fitting inviscid jet solution, an integral boundary layer solution, a control volume method for treating separated flows, and an overlaid mixing layer solution. A computer program called RAXJET which incorporates the method, illustrates the predictive capabilities of the method by comparison with experimental data is described, a user's guide to the computer program is provided. The method accurately predicts afterbody pressures, drag, and flow field properties for attached and separated flows for which no shock induced separation occurs
Interference effects on the hypersonic, rarefied flow about a flat plate
The Direct Simulation Monte Carlo method is used to study the hypersonic, rarified flow interference effects on a flat plate caused by nearby surfaces. Calculations focus on shock-boundary-layer and shock-lip interactions in hypersonic inlets. Results are presented for geometries consisting of a flat plate with different leading-edge shapes over a flat lower wall and a blunt-edge flat plate over a 5-degree wedge. The problems simulated correspond to a typical entry flight condition of 7.5 km/s at altitudes of 75 to 90 km. The results show increases in predicted local heating rates for shock-boundary-layer and shock-lip interactions that are quantitatively similar to those observed experimentally at much higher densities
On the relationship between period and cohort mortality
In this paper I explore the formal relationship between period and cohort mortality, focusing on a comparison of measures of mean lifespan. I consider not only the usual measures (life expectancy at birth for time periods and birth cohorts) but also some alternative measures that have been proposed recently. I examine (and reject) the claim made by Bongaarts and Feeney that the level of period is distorted, or biased, due to changes in the timing of mortality. I show that their proposed alternative measure, called “tempo-adjusted†life expectancy, is exactly equivalent in its generalized form to a measure proposed by both Brouard and Guillot, the cross-sectional average length of life (or CAL), which substitutes cohort survival probabilities for their period counterparts in the calculation of mean lifespan. I conclude that this measure does not in any sense correct for a distortion in period life expectancy at birth, but rather offers an alternative measure of mean lifespan that is approximately equal to two analytically interesting quantities: 1) the mean age at death in a given year for a hypothetical population subject to observed historical mortality conditions but with a constant annual number of births; and 2) the mean age at death, , for a cohort born years ago. However, I also observe that the trend in period does indeed offer a biased depiction of the pace of change in mean lifespan from cohort to cohort. Holding other factors constant, an historical increase in life expectancy at birth is somewhat faster when viewed from the perspective of cohorts (i.e., year of birth) than from the perspective of periods (i.e., year of death).life expectancy, life span, mortality, tempo-adjusted life expectancy
The Cancer Transition in Japan since 1951
The overall trend of cancer mortality in Japan has been decreasing since the 1960s (age-standardized death rates for ages 30-69), though trends differ enormously among various forms of the disease. Cancer mortality was heavily influenced by Japanese postwar economic recovery, which led to improved living conditions and better control of infectious agents known to cause some common forms of cancer (stomach, cervical). However, Japanese wealth and development have also been associated with risky personal behaviors (smoking, drinking) and other conditions, leading to increases in cancers with no known or else very weak links to infection. This shift away from infectious and toward non-infectious causes of prevalent forms of cancers is called the "cancer transition," by analogy to Omran's "epidemiologic transition." We suggest that the cancer transition described here in the case of Japan must be a part of efforts to revise and update the epidemiologic transition, which should incorporate new knowledge about the role of infection in chronic disease morbidity and mortality.cancer, cancer transition, epidemiologic transition, health, health and development, infectious diseases, Japan, mortality, non-infectious disease
Identifiable Age, Period, and Cohort Effects: An Exploratory Approach Applied to Italian Female Mortality
A group of eleven Ph.D. candidates from seven countries--Robin Cowan, Andrew Foster, Nedka Gateva, William Hodges, Arno Kitts, Eva Lelievre, Fernando Rajulton, Lucky Tedrow, Marc Tremblay, John Wilmoth, and Zeng Yi--worked together at IIASA from June 17 through September 6, 1985, in a seminar on population heterogeneity. The seminar was led by the two of us with the help of Nathan Keyfitz, leader of the Population Program, and Bradley Gambill, Dianne Goodwin, and Alan Bernstein, researchers in the Population Program, as well as the occasional participation of guest scholars at IIASA, including Michael Stoto, Sergei Scherbov, Joel Cohen, Frans Willekens, Vladimir Crechuha, and Geert Ridder. Susanne Stock, our secretary, and Margaret Traber managed the seminar superbly.
Each of the eleven students in the seminar succeeded in writing a report on the research they had done. With only one exception, the students evaluated the seminar as "very productive"; the exception thought it was "productive". The two of us agree: the quality of the research produced exceeded our expectations and made the summer a thoroughly enjoyable experience. We were particularly pleased by the interest and sparkle displayed in our daily, hour-long colloquium, and by the spirit of cooperation all the participants, both students and more senior researchers, displayed in generously sharing ideas and otherwise helping each other.
One of the best of the research reports produced and probably the most original is the report by John Wilmoth that appears in this working paper. Building on some of the work on the mathematics of population surfaces, on the use of shaded contour maps for displaying population surfaces, and on Italian mortality that had been started at IIASA by the two of us and W. Brian Arthur, Bradley A. Gambill, and Graziella Caselli, Wilmoth developed an approach for analyzing age, period, and cohort effects that shows considerable promise for further development and application. This report thus exemplifies the productive role IIASA can play in bringing together diligent, creative scholars from different countries and disciplines
Computation of high Reynolds number internal/external flows
A general, user oriented computer program, called VNAF2, developed to calculate high Reynolds number internal/external flows is described. The program solves the two dimensional, time dependent Navier-Stokes equations. Turbulence is modeled with either a mixing length, a one transport equation, or a two transport equation model. Interior grid points are computed using the explicit MacCormack scheme with special procedures to speed up the calculation in the fine grid. All boundary conditions are calculated using a reference plane characteristic scheme with the viscous terms treated as source terms. Several internal, external, and internal/external flow calculations are presented
Introduction to the Special Collection “Human Mortality over Age, Time, Sex, and Place: The 1st HMD Symposiumâ€
This introduction to the special collection “Human Mortality over Age, Time, Sex, and Place: The 1st HMD Symposium†describes the Human Mortality Database project and briefly summarizes the Special Collection articles.
Physical Fitness and Weight Loss After Surgery for Obstructive Sleep Apnea: A Case Study
Objective: While there has been a great deal of research on obstructive sleep apnea and its association with obesity, there is little documentation in the primary literature concerning weight loss and improved physical fitness after medical treatment of obstructive sleep apnea. This study will document the effects of a reduced calorie diet combined with aerobic conditioning and strength training on a subject who has been treated surgically for obstructive sleep apnea. Methods: The subject participated in a 12-week structured fitness and nutritional program for weight reduction. Pre-program baseline measurements including weight, body mass index (BMI), body fat composition, and waist measurement were established. A pre-program baseline of physical fitness capability was established including a timed 1.5 mile run along with maximum repetitions of specific callisthenic and strength exercises performed with a 2 minute time limit. All physical fitness training activity was recorded, including elapsed times, repetitions, weight levels, and exercise intensity attained. Daily dietary intake, including grams of carbohydrate, protein, and fat, as well as total calories consumed were recorded in a program log. At program completion monitored parameters were analyzed for percent change from baseline. Results: The dietary calculations revealed an average intake of 1237 total calories per day. This was broken down into 61% carbohydrates, 26% protein, and 13% fat. The subject had a total weight loss of 41 pounds during the 12 week program, corresponding to a 16.5% decrease from a baseline of 248 pounds. BMI was reduced from 37.7 to 31.5, a 16.4% decrease. Body fat percentage was reduced from 36.6% to 28%, a decrease from baseline of 23.5%. Patients waist size decreased from 42 inches to 36 inches, a decrease of 14.3% from baseline. The subject decreased his time in the 1.5 mile run from 15:36 to 12:23, a decrease of 20.4% from baseline. The subject improved his 2 minute pushup maximum from 26 to 53, a 104% increase. The number of sit-ups in 2 minutes was increased from 41 to 76, an increase of 85% from baseline. Conclusion: The subject of the case-study was able to achieve gains in physical fitness as well as weight loss by following a highly structured nutritional plan combined with aerobic conditioning and strength training.\u2
Stroke Prevention in Non-Valvular Atrial Fibrillation
Atrial Fibrillation (AF) is the most commonly-treated cardiac arrhythmia in the world. In AF, unsynchronized action potentials in the pulmonary veins and left atrium lead to uneven contractions of the atrial muscle cells, resulting in an irregularly irregular heart rhythm and inadequate blood flow out of the heart. The major complication that stems from untreated AF is a thromboembolic stroke event. While Warfarin has been the long-standing treatment option in preventing stroke, there are several other available options that patients may consider, including Direct Oral Anticoagulants (DOACs), such as Apixaban (aka Eliquis) and Rivaroxiban (aka Xarelto). An additional and more recent option is occlusion of the left atrial appendage (LAAO), a pocket structure and the most common site for thrombus formation. The only FDA approved device in the US currently for LAAO is the WATCHMAN device. This review defines atrial fibrillation, explains different risk assessment tools in stroke prevention, and outlines the available prophylaxis options while weighing risks and benefits
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