Physical Sciences and Mathematics Commons^™

Two-Temperature Discrete Model For Nonlocal Heat Conduction, Sergey Sobolev

Sergey Sobolev

The two-temperature discrete model for heat conduction in heterogeneous media is proposed. It is shown that the discrete model contains as limiting cases both hyperbolic and parabolic heat conduction equations for propagative and diffusive regimes, respectively. To obtain these limiting cases two different laws of continuum limit have been introduced. The evolution of the two-temperature system comprises three stages with distinct time scales : fast relaxation of each subsystem to local equilibrium, energy exchange between the subsystems and classical hydrodynamics.

Who Enrolled In A State Program For The Uninsured: Was There Adverse Selection?, Paula Diehr

Paula Diehr

Managed care plans may hesitate to participate in programs for uninsured persons because they fear adverse selection, whereby only the sickest people or highest users would choose to join the program. We studied this issue in Washington State's Basic Health Plan, a demonstration program that provides subsidized health insurance for families earning less than 200% of the poverty level. We interviewed people in three counties who enrolled in the program, and compared them to people in the same counties who were eligible but did not enroll. There were substantial differences between enrollees and eligibles in education, age, income, employment, race, …

The Hazardous Waste Land, Jerry L. Anderson

Jerry L. Anderson

This article was one of the first comprehensive critiques of the Superfund remediation and liability system. The article addresses systemic problems with the CERCLA mechanism that result in inequity and slow the pace of cleanups.

Do Communities Differ In Health Behaviors?, Paula Diehr

Paula Diehr

Communities differ in the prevalence of various health behaviors, but it is not known to what extent these differences are due to "different types" of people living in them. We used data from the evaluation of the Henry J Kaiser Family Foundation Community Health Promotion Grant Program to study individual-level and community-level variation in health behaviors for 15 communities. Our results show (1) there was significant variation among these communities in prevalences of smoking, consumption of alcohol and dietary fat, and use of seatbelts; (2) these differences persisted after control for demographic, health status, and other health behavioral characteristics of …

Small Area Variation Analysis. Methods For Comparing Several Diagnosis-Related Groups., Paula Diehr

Paula Diehr

In small-area variation analysis, the variation of health care utilization rates, e.g., admission rates, among small areas is calculated. Frequently, the variation of one diagnosis, diagnosis-related group (DRG), or procedure is compared with the variation of another. Unfortunately, the methods generally used to make these comparisons are not consistent. They differ on whether they 1) adjust for the prevalence of the DRGs, 2) distinguish between variation among areas and variation within areas, 3) weight all areas equally, and 4) adjust for multiple admissions per person. None has an associated confidence interval. These discrepancies occur in part because there is no …

Generalized Linear Models: Software Implementation And The Structure Of A General Power-Link Based Glm Algorithm, Joseph Hilbe

Joseph M Hilbe

Generalized linear modeling (GLM) is currently undergoing a renaissance. The number of software packages offering GLM capability grows each year and as a partial consequence one finds an increased number of research endeavors being modeled using GLM methodology. On the other hand, there have likewise been an increasing number of requests to vendors by users of statistical packages to include GLM facilities amid other offerings. The overall effect has been a near 300 percent increase in GLM programs over the past four years.

I shall discuss the nature of generalized linear models followed by an examination of how they have …

Tensor Operators Iii, Some Fundamental Tensor Operator Identities, Daniel Flath, J. Towber

Daniel Flath

No abstract provided.

Special Review: Evaluation Of The Exploratory Factor Analysis Programs Provided In Spssx And Spss/Pc+, Gregory J. Boyle

Gregory J. Boyle

Given the frequent use of SPSSX and SPSS/PC+ exploratory factor analysis in analyzing multivariate psychometric data, it is germane to examine the limitations of the Factor program as it currently exists. Over recent years, the routines in these packages generally have been developed and expanded considerably. In particular, the exploratory factor analysis procedures have been greatly extended and enhanced with inclusion of additional estimation methods such as minimum likelihood, unweighted least squares, generalized least squares, and so on. Like­ wise, availability of a Scree plot of the latent roots against factor number has facilitated determination of the appropriate factor-extraction number. …

The Paradox Of Ideology, Justin Schwartz

Justin Schwartz

A standard problem with the objectivity of social scientific theory in particular is that it is either self-referential, in which case it seems to undermine itself as ideology, or self-excepting, which seem pragmatically self-refuting. Using the example of Marx and his theory of ideology, I show how self-referential theories that include themselves in their scope of explanation can be objective. Ideology may be roughly defined as belief distorted by class interest. I show how Marx thought that natural science was informed by class interest but not therefore necessarily ideology. Capitalists have an interest in understanding the natural world (to a …

Field Experiments In A Fractured Clay Till: 2. Solute And Colloid Transport, Larry Mckay, Robert W. Gillham, John A. Cherry

Larry McKay

A field tracer experiment was conducted in a lateral flow field in the weathered and highly fractured upper 6 m of a 40-m-thick clay-rich till plain in southwestern Ontario. In the upper 3 m where fractures are closely spaced (<0.13 m) the advancing front (C/C0 = 0.01) of the nonreactive solute tracers, bromide and 18O, migrated at rates of 0.01 to 0.07 m/d, over distances of 4 and 6 m and under a lateral hydraulic gradient of 0.24. In this same zone, two strains of colloid-sized bacteriophage tracers migrated at rates of 2 to >5 m/d. Simulations with a discrete fracture/porous matrix flow and transport model, which used the cubic law for flow in fractures, showed that diffusion of the solutes, but not the much larger colloids, into the matrix pore water between fractures is sufficient to cause the observed difference in solute and colloid transport rates. Transport-derived and hydraulic conductivity-derived fracture aperture values …

Field Experiments In A Fractured Clay Till: 1. Hydraulic Conductivity And Fracture Aperture, Larry Mckay, John A. Cherry, Robert W. Gillham

Larry McKay

Field values of horizontal hydraulic conductivity measured in the upper 1.5–5.5 m of a weathered and fractured clay-rich till were strongly influenced by smearing around piezometer intakes, which occurs during augering, and by the physical scale of the measuring device. Values measured in conventional augered piezometers were typically 1–2 orders of magnitude lower than those measured in piezometers designed to reduce smearing. Measurements of hydraulic conductivity in small-scale seepage collectors or piezometers, which typically intersect fewer than 10 fractures, vary over a much greater range, 10−10 to 10−6 m/s, than large-scale values based on infiltration into 5.5-m-deep trenches which intersect …