Medical care utilization in a regional prepaid medical system

Aggregate dollar medical care utilization is estimated by applying a fee structure to 1967–70 medical care utilization of 3,418 members of the Kaiser Foundation Health Plan of Portland, Oregon. The data indicated a very stable pattern of medical care utilization by the cohort during the period. The average yearly increase in medical care dollar utilization per person (prices constant) was only 1.5 percent. There was some tendency for resource utilizaton to become more concentrated among the highest users. Inpatient services accounted for about 40 percent of the dollar utilization with no tendency to decline or rise over the fouryear period. While age and death were the only factors significantly associated with the likelihood of being a high user in a given year ($2,500 threshold), family size, education, and sex joined these factors in being associated with medical care dollar utilization by an individual. Family size was negatively related while education and being female were related directly to dollar utilization. A limited comparison is made with experience in the U.S.This research was supported by Grant No. 5 RO1 HS-01653, awarded by the National Center of Health Services Research, HRA. Technical support was given by the Health Services Research Center, Kaiser Foundation Hospitals, Portland, Oregon.     

The spectrum of power from wind turbines

The power spectral density of the output of wind turbines provides information on the character of fluctuations in turbine output. Here both 1-second and 1-hour samples are used to estimate the power spectrum of several wind farms. The measured output power is found to follow a Kolmogorov spectrum over more than four orders of magnitude, from 30 s to 2.6 days. This result is in sharp contrast to the only previous study covering long time periods, published 50 years ago. The spectrum defines the character of fill-in power that must be provided to compensate for wind's fluctuations when wind is deployed at large scale. Installing enough linear ramp rate generation (such as a gas generator) to fill in fast fluctuations with amplitudes of 1% of the maximum fluctuation would oversize the fill-in generation capacity by a factor of two for slower fluctuations, greatly increasing capital costs. A wind system that incorporates batteries, fuel cells, supercapacitors, or other fast-ramp-rate energy storage systems would match fluctuations much better, and can provide an economic route for deployment of energy storage systems when renewable portfolio standards require large amounts of intermittent renewable generating sources.     

Phase-shifting birefringent scatterplate interferometer

We realized what we believe is a new phase-shifting scatterplate interferometer by exploiting the polarization characteristics of a birefringent scatterplate. The common-path design of the interferometer reduces its sensitivity to environmental effects, and phase shifting allows quick and accurate quantitative measurements of the test surface. A major feature of the birefringent scatterplate approach for phase shifting is that no high-quality optical components are required in the test setup. The theory of the interferometer is presented, the procedure for the fabrication of the birefringent scatterplate is described, and experimental results are shown.     

Update strategies for kriging models used in variable fidelity optimization

Many optimization methods for simulation-based design rely on the sequential use of metamodels to reduce the associated computational burden. In particular, kriging models are frequently used in variable fidelity optimization. Nevertheless, such methods may become computationally inefficient when solving problems with large numbers of design variables and/or sampled data points due to the expensive process of optimizing the kriging model parameters in each iteration. One solution to this problem would be to replace the kriging models with traditional Taylor series response surface models. Kriging models, however, were shown to provide good approximations of computer simulations that incorporate larger amounts of data, resulting in better global accuracy. In this paper, a metamodel update management scheme (MUMS) is proposed to reduce the cost of using kriging models sequentially by updating the kriging model parameters only when they produce a poor approximation. The scheme uses the trust region ratio (TR-MUMS), which is a ratio that compares the approximation to the true model. Two demonstration problems are used to evaluate the proposed method: an internal combustion engine sizing problem and a control-augmented structural design problem. The results indicate that the TR-MUMS approach is very effective; on the demonstration problems, it reduced the number of likelihood evaluations by three orders of magnitude compared to using a global optimizer to find the kriging parameters in every iteration. It was also found that in trust region-based method, the kriging model parameters need not be updated using a global optimizer—local methods perform just as well in terms of providing a good approximation without affecting the overall convergence rate, which, in turn, results in a faster execution time.     

Expert systems: A short introduction

Expert systems are rapidly growing in diversity of application and usage worldwide. Even though expert system development has been slow in applying expert systems to the specific field of structures, expert system technology has been pervasive in other areas of engineering and manufacturing. This paper provides a short introduction on expert systems, looking at their development, application and future trends.     

Influence of some hypnotist and subject variables on hypnotic susceptibility.

Randomly assigned 48 21-56 yr. Old females to 1 of 4 groups given different information with regard to a hypnotist's warmth and experience. The 6 male graduate student hypnotists had previously been judged on their objective warmth and competent appearance. Following structuring, all ss underwent individual hypnotic induction. As predicted, ss run by the objectively warmer, more competent appearing es obtained significantly higher susceptibility scores. Structured warmth produced significant differences only in ss run by the objectively less warm es. Both structured warmth and experience affected ss' subjective impressions of whether they thought they had been hypnotized. The complex relationship between antecedent variables and the various objective and subjective dependent indicators of hypnotic phenomena are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Marital status and schizophrenia: A study of incidence and outcome.

Investigated the relationships between marital status and the incidence and prognosis of schizophrenia, based on a considerably more representative sample (N = 213) than previously available. Results provide strong evidence that the rate differentials and differences in outcome so often observed for marital status categories do not derive from inadequate or inappropriate sampling or statistical manipulation. In additional analyses, controlling for differential social class and severity of pathology, however, the relationships with prognosis could no longer be observed. These latter findings suggest that a process of selection by marriage is the more tenable interpretation of the relationships under consideration. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Numerical treatment of mixed boundary value problems in two-dimensional elastostatics

Finite difference treatment of two-dimensional problems in elastostatics is usually based on the differential equations for the displacement vector or the Airy stress function, depending on whether boundary conditions are on displacement or stress. In either case, determination of stresses requires numerical differentiation and therefore use of a rather fine grid. Moreover, neither method is suited to the treatment of mixed boundary conditions. The alternative method developed in this paper uses the first derivatives of the displacement components at the grid points as basic variables and hence does not require numerical differentiation in the evaluation of stresses. Appropriate finite difference equations are established, and their use is discussed in connection with a specific example with known explicit solution.     

Comparison of PCR prescreening to two cultivation procedures with PCR confirmation for detection of Mycobacterium avium subsp. paratuberculosis in U.S. Department of Agriculture fecal check test samples

Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent in Johne's disease in cattle and causes diarrhea, decreased milk production, emaciation, and frequently death. The ability to detect MAP rapidly and accurately is an integral part of herd management. However, detection of this bacterium is complicated due to its slow division time and its ability to enter dormancy. Culture methods are considered the "gold standard," but they have their limitations. Many enzyme-linked immunosorbent assay methods and conventional PCR methods have been used as diagnostic tools. The present study compares the results of a PCR prescreen to two culture methods of detection paired with confirmatory PCR to determine the most accurate, rapid, and sensitive method using U.S. Department of Agriculture (USDA) fecal check samples. This study involving two laboratories (Marshfield Clinic Laboratories, using solid culture medium [Herrold's egg yolk agar], and TREK Diagnostic Systems Research and Development, using liquid culture medium [ESP Culture System II]) showed that the PCR prescreening method used in this study lacked specificity and sensitivity as a stand-alone test in fecal samples. However, the combination of liquid enrichment culture using the ESP II system, and PCR confirmation with the hspX primer set, was not only 100% sensitive and specific but also correlated with viable MAP and USDA culture results.