RAND Corporation

About: RAND Corporation is a nonprofit organization based out in Santa Monica, California, United States. It is known for research contribution in the topics: Population & Health care. The organization has 9602 authors who have published 18570 publications receiving 744658 citations.

Physical Education in Elementary School and Body Mass Index: Evidence from the Early Childhood Longitudinal Study

Abstract: Objectives. We examined the effect of physical education instruction time on body mass index (BMI) change in elementary school.Methods. We examined data from a national sample of 9751 kindergartners in the United States who were reported on for 2 years. We used a difference-in-differences approach to examine the effect of an increase in physical education instruction time between kindergarten and first grade on the difference in BMI change in the 2 grades, using the same child as the control.Results. One additional hour of physical education in first grade compared with the time allowed for physical education in kindergarten reduces BMI among girls who were overweight or at risk for overweight in kindergarten (coefficient = −0.31, P < .001) but has no significant effect among overweight or at-risk-for-overweight boys (coefficient = −0.07, P = .25) or among boys (coefficient = 0.04, P = .31) or girls (coefficient = 0.01, P = .80) with a normal BMI.Conclusions. Expanding physical education programs in schoo...

Management of heart failure. III. The role of revascularization in the treatment of patients with moderate or severe left ventricular systolic dysfunction.

Abstract: Objective. —This article reviews the benefits and risks of coronary artery bypass grafting and angioplasty for patients with moderate or severe left ventricular systolic dysfunction and summarizes the recommendations of the expert panel for the Agency for Health Care Policy and Research Heart Failure Guideline. Data Sources. —Data were obtained from studies published in English and referenced in MEDLINE or EMBASE between 1966 and 1993. We used the search terms heart failure, congestive; congestive heart failure; heart failure; cardiac failure ; and dilated cardiomyopathy in conjunction with the terms coronary artery bypass grafting and angioplasty . Study Selection. —All cohort studies and case series that provided separate outcomes data on a subgroup of patients with a left ventricular ejection fraction less than 0.40 were reviewed. Data Extraction and Synthesis. —Studies were reviewed for inclusion and exclusion criteria, survival, and functional status measures using a standardized form. Cohort studies were assessed on eight aspects of study quality using a defined list of study flaws. Conclusion. —Coronary artery bypass grafting improves 3-year survival by approximately 30% to 50% and physical functioning by approximately one New York Heart Association class in patients with moderate to severe left ventricular dysfunction and limiting angina. However, the operative mortality ranges from 5% to 30% depending on patients' ejection fractions and comorbidity. It is not clear whether patients whose predominant symptom is heart failure rather than angina benefit from bypass surgery or how much ischemia is required to justify surgical intervention. Clinical outcomes after angioplasty have not been adequately studied to determine the relative risks and benefits compared with bypass grafting. ( JAMA . 1994;272:1528-1534)

Climate change and growth scenarios for California wildfire

Abstract: Large wildfire occurrence and burned area are modeled using hydroclimate and landsurface characteristics under a range of future climate and development scenarios. The range of uncertainty for future wildfire regimes is analyzed over two emissions pathways (the Special Report on Emissions Scenarios [SRES] A2 and B1 scenarios); three global climate models (Centre National de Recherches Meteorologiques CM3, Geophysical Fluid Dynamics Laboratory CM2.1 and National Center for Atmospheric Research PCM1); three scenarios for future population growth and development footprint; and two thresholds for defining the wildland-urban interface relative to housing density. Results were assessed for three 30-year time periods centered on 2020, 2050, and 2085, relative to a 30-year reference period centered on 1975. Increases in wildfire burned area are anticipated for most scenarios, although the range of outcomes is large and increases with time. The increase in wildfire burned area associated with the higher emissions pathway (SRES A2) is substantial, with increases statewide ranging from 36% to 74% by 2085, and increases exceeding 100% in much of the forested areas of Northern California in every SRES A2 scenario by 2085.

Toward Trustworthy AI Development: Mechanisms for Supporting Verifiable Claims

Abstract: With the recent wave of progress in artificial intelligence (AI) has come a growing awareness of the large-scale impacts of AI systems, and recognition that existing regulations and norms in industry and academia are insufficient to ensure responsible AI development. In order for AI developers to earn trust from system users, customers, civil society, governments, and other stakeholders that they are building AI responsibly, they will need to make verifiable claims to which they can be held accountable. Those outside of a given organization also need effective means of scrutinizing such claims. This report suggests various steps that different stakeholders can take to improve the verifiability of claims made about AI systems and their associated development processes, with a focus on providing evidence about the safety, security, fairness, and privacy protection of AI systems. We analyze ten mechanisms for this purpose--spanning institutions, software, and hardware--and make recommendations aimed at implementing, exploring, or improving those mechanisms.