Brown University

About: Brown University is a education organization based out in Providence, Rhode Island, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 35778 authors who have published 90896 publications receiving 4471489 citations. The organization is also known as: brown.edu & Brown.

Energy release rate along a three-dimensional crack front in a thermally stressed body

Abstract: Based on a line-integral expression for the energy release rate in terms of crack tip fields, which is valid for general material response, a (area/volume) domain integral expression for the energetic force in a thermally stressed body is derived. The general three-dimensional finite domain integral expression and the two-dimensional and axisymmetric specializations for the energy release rate are given. The domain expression is naturally compatible with the finite element formulation of the field equations. As such it is ideally suited for efficient and accurate calculation of the pointwise values of the energy release rate along a three-dimensional crack front. The finite element implementation of the domain integral corresponds to the virtual crack extension technique. Procedures for calculating the energy release rate using the numerically determined field solutions are discussed. For illustrative purposes several numerical examples are presented.

Screening for psychologic distress in ambulatory cancer patients

Abstract: BACKGROUND Based on evidence that psychologic distress often goes unrecognized although it is common among cancer patients, clinical practice guidelines recommend routine screening for distress. For this study, the authors sought to determine whether the single-item Distress Thermometer (DT) compared favorably with longer measures currently used to screen for distress. METHODS Patients (n = 380) who were recruited from 5 sites completed the DT and identified the presence or absence of 34 problems using a standardized list. Participants also completed the 14-item Hospital Anxiety and Depression Scale (HADS) and an 18-item version of the Brief Symptom Inventory (BSI-18), both of which have established cutoff scores for identifying clinically significant distress. RESULTS Receiver operating characteristic (ROC) curve analyses of DT scores yielded area under the curve estimates relative to the HADS cutoff score (0.80) and the BSI-18 cutoff scores (0.78) indicative of good overall accuracy. ROC analyses also showed that a DT cutoff score of 4 had optimal sensitivity and specificity relative to both the HADS and BSI-18 cutoff scores. Additional analyses indicated that, compared with patients who had DT scores < 4, patients who had DT scores ≥ 4 were more likely to be women, have a poorer performance status, and report practical, family, emotional, and physical problems (P ≤ 0.05). CONCLUSIONS Findings confirm that the single-item DT compares favorably with longer measures used to screen for distress. A DT cutoff score of 4 yielded optimal sensitivity and specificity in a general cancer population relative to established cutoff scores on longer measures. The use of this cutoff score identified patients with a range of problems that were likely to reflect psychologic distress. Cancer 2005. © 2005 American Cancer Society.

Reliability Estimates for The Minimum Data Set for Nursing Home Resident Assessment and Care Screening (MDS)

Abstract: The MDS is a core set of items, definitions, and response categories used to assess all of the nation's 1.5 million nursing home residents who reside in facilities participating in the Medicare or Medicaid programs. Further, the Health Care Financing Administration (HCFA) has proposed a rule that would require facilities to computerize MDS data and submit it to state and federal agencies, paving the way for a national database. This article describes the process of testing the reliability of the MDS items in 13 nursing homes in five states. The results demonstrate that MDS data gathered in a research effort attain reliabilities that make such data useful. MDS items met a standard for excellent reliability (i.e., intraclass correlation of .7 or higher) in key areas of functional status, such as cognition, ADLs, continence, and diagnoses. Sixty-three percent of the items achieved reliability coefficients of .6 or higher. Eighty-nine percent of the items in the MDS achieved .4 or higher.

Trans-Planckian problem of inflationary cosmology

Abstract: In most current models of inflation based on a weakly self-coupled scalar matter field minimally coupled to gravity, the period of inflation lasts so long that, at the beginning of the inflationary period, the physical wavelengths of comoving scales which correspond to the present large-scale structure of the Universe were smaller than the Planck length. Thus, the usual computations of the spectrum of fluctuations in these models involve extrapolating low-energy physics (both in the matter and gravitational sector) into regions where this physics is not applicable. In this article we study the dependence of the usual predictions of inflation for the spectrum of cosmological fluctuations on the hidden assumptions about super-Planck scale physics. We introduce a class of modified dispersion relations to mimic possible effects of super-Planck scale physics, and find that, given an initial state determined by minimizing the energy density, for dispersions relations introduced by Unruh the spectrum is unchanged, whereas for a class of dispersion relations similar to those used by Corley and Jacobson (which involve a more radical departure from the usual linear relation) important deviations from the usual predictions of inflation can be obtained. Some implications of this result for the unification of fundamental physicsmore » and early Universe cosmology are discussed.« less