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.

A Network Flow Computation for Project Cost Curves

Abstract: A network flow method is outlined for solving the linear programming problem of computing the least cost curve for a project composed of many individual jobs, where it is assumed that certain jobs must be finished before others can be started. Each job has an associated crash completion time and normal completion time, and the cost of doing the job varies linearly between these extreme times. Given that the entire project must be completed in a prescribed time interval, it is desired to find job times that minimize the total project cost. The~method solves this problem for all feasible time intervals.

Living Well at the End of Life: Adapting Health Care to Serious Chronic Illness in Old Age

Abstract: : Most older Americans now face chronic illness and disability in the final years of life. These final years can prove painful and difficult for sick and disabled elderly people, who may have difficulty finding care to meet their needs. This period is often stressful and expensive for families. As currently configured, health care and community services simply are not organized to meet the needs of the large and growing number of people facing a long period of progressive illness and disability before death. This white paper synthesizes a growing body of research on the issue of chronic illness in the last phase of life. It describes the demographic and cost components of the problem, examines gaps in the current health care system, explores some reform measures that are addressing urgent needs, and outlines a vision for adapting the health care system to confront the new reality. This work has relied heavily upon grant support from The Archstone Foundation, the Milbank Memorial Fund, and The Washington Home and Community Hospices.

Geochemistry and sedimentology of a facies transition from limestone to iron-formation deposition in the early Proterozoic Transvaal Supergroup, South Africa

Abstract: This study deals with the geochemistry and sedimentology of a facies transition from interbedded carbonate-shale to banded iron-formation in the Campbellrand carbonate sequence to the overlying Kuruman Iron Formation of the Transvaal Supergroup in South Africa which is approximately 2.3 Ga old. Four major lithologies are (1) limestone and dolomite, (2) shale and interbedded shale carbonate, (3) siderite-rich banded iron-formation, and (4) iron oxide-rich banded iron-formation. These rocks are unaltered and essentially unmetamorphosed with a maximum metamorphic-diagenetic overprint ranging in temperature from 110 degrees to 170 degrees C and with pressures of not more than 2 kbars.The oldest rocks are limestones and lesser dolomite with abundant cryptalgalaminae and intraclastic textures. Interbedded with the limestones and dolomites are carbonaceous shales, some of which are unusually ferruginous or pyrite rich. These carbonates and shales are overlain by meso- and microbanded siderite-chert iron-formation which grades upward into magnetite-, chert-, and carbonate-rich iron-formation.The averages for major and trace elements and rare earth element (REE) contents of the limestones, dolomites, and shales are distinct from those of the two types of iron-formation. The two most chemically diverse rock types are the shales (enriched in alkalis and most trace elements) and the two iron-formation types (siderite and magnetite rich) which are almost totally depleted in all elements except Si, Fe, Mg, and Ca (and CO 2 ). The high Al 2 O 3 contents of the shales (avg 9.55 wt %) correlate well with their high organic carbon contents (avg 3.91 wt %); the limestones and dolomites have average Al 2 O 3 and organic carbon contents of about 3.0 and 0.7 wt percent, respectively; the two iron-formation types have Al 2 O 3 average values of 0.099 wt percent (siderite rich) and 0.066 wt percent (magnetite rich) and corresponding averages for organic carbon of 0.080 wt percent (siderite rich) and 0.012 wt percent (magnetite rich). The REE are generally concentrated in the shales by a factor of about 10 over the iron-formations. The limestones and dolomites have intermediate values, and the iron-formations are most depleted. The iron-formation REE patterns (in a ratio with North American shale composite (NASC)) have pronounced positive Eu anomalies and slight negative Ce anomalies. Both of these anomalies are absent in the shales, but the limestones and dolomites show slight positive Eu anomalies.The siderite-rich iron-formations consist of chert-siderite-ankerite (or ferroan dolomite) with traces of pyrite and stilpnomelane. The siderite in these commonly microbanded assemblages is very fine grained along well-defined bedding planes. It is concluded, from petrographic study, that siderite is a primary precipitate. The ankerites and ferroan dolomites in these siderite-rich occurrences are commonly euhedral (rhombohedral), much coarser grained, and appear to be of later (diagenetic) origin. The magnetite-rich iron-formations consist of chert-magnetite-ankerite (or ferroan dolomite) + or - siderite + or - hematite + or - stilpnomelane + or - minnesotaite. In these oxide-rich iron-formations the ankerites (and ferroan dolomites) are similarly much coarser grained than the finely banded siderite. On the basis of the geochemical data and a reconstruction of the depositional basin for the carbonate-shale to iron-formation transition, we conclude that the limestone-dolomite-shale lithologies originated in a water column quite distinct from that in which the iron-formations were precipitated. We propose a model with a stratified water column in which the surface waters (during a regressive stage in the depositional basin) were the site of much organic carbon productivity and the locus of cryptalgal limestones and intraclastic limestone deposition; with at somewhat greater depth (below the chemocline) deposition of pyritic carbonaceous shale. Our model depicts the deeper waters (during a transgressive stage of the basin with the Kaapvaal craton more deeply submerged) as the site for iron-formation deposition; these deeper waters were depleted in organic carbon and enriched in dissolved ferrous iron relative to the shallower water mass, with continued availability of oxygen along the chemocline separating the two water masses. The ultimate source of the iron (and probably the SiO 2 ) in the iron-formations appears to be a very dilute hydrothermal input in the deep ocean waters, as concluded from mixing calculations of REE values for modern Atlantic Ocean water and hydrothermal solutions from the East Pacific Rise.

Spinal Manipulative Therapy for Low Back Pain: A Meta-Analysis of Effectiveness Relative to Other Therapies

Abstract: Background Low back pain is a costly illness for which spinal manipulative therapy is commonly recommended. Previous systematic reviews and practice guidelines have reached discordant results on the effectiveness of this therapy for low back pain. Purpose To resolve the discrepancies related to use of spinal manipulative therapy and to update previous estimates of effectiveness by comparing spinal manipulative therapy with other therapies and then incorporating data from recent high-quality randomized, controlled trials (RCTs) into the analysis. Data sources MEDLINE, EMBASE, CINAHL, the Cochrane Controlled Trials Register, and previous systematic reviews. Study selection Randomized, controlled trials of patients with low back pain that evaluated spinal manipulative therapy with at least 1 day of follow-up and at least one clinically relevant outcome measure. Data extraction Two authors, who served as the reviewers for all stages of the meta-analysis, independently extracted data from unmasked articles. Comparison treatments were classified into the following seven categories: sham, conventional general practitioner care, analgesics, physical therapy, exercises, back school, or a collection of therapies judged to be ineffective or even harmful (traction, corset, bed rest, home care, topical gel, no treatment, diathermy, and minimal massage). Data synthesis Thirty-nine RCTs were identified. Meta-regression models were developed for acute or chronic pain and short-term and long-term pain and function. For patients with acute low back pain, spinal manipulative therapy was superior only to sham therapy (10-mm difference [95% CI, 2 to 17 mm] on a 100-mm visual analogue scale) or therapies judged to be ineffective or even harmful. Spinal manipulative therapy had no statistically or clinically significant advantage over general practitioner care, analgesics, physical therapy, exercises, or back school. Results for patients with chronic low back pain were similar. Radiation of pain, study quality, profession of manipulator, and use of manipulation alone or in combination with other therapies did not affect these results. Conclusions There is no evidence that spinal manipulative therapy is superior to other standard treatments for patients with acute or chronic low back pain.