Is edge information for stereoacuity spatially channeled?

Models of stereopsis generally assume that binocular correspondence is achieved through alignment of luminance edges in the two eyes. Yet the stimulus properties which constitute edge information for stereopsis have not been defined. Three experiments explored the nature of these stimulus properties. The first two experiments tested whether local luminance gradient and the relative phase of spatial components supply information about the position of edges which influences stereosensitivity. In Expt 1, stereothresholds were reduced with increased spatial frequency or contrast of sinusoidal luminance gratings, but no simple relationship between target luminance gradient and stereosensitivity was found. In Expt 2, stereothresholds were equivalent for targets having identical spatial frequency components, but differing in maximum luminance gradient and the relative spatial phase of their components. In addition, stereothresholds were lower for the target having the higher contrast in pairs of unequal-contrast targets having equal maximum luminance gradients. These results suggest that the properties of luminance gradient and relative spatial phase do not influence stereosensitivity independently of spatial frequency and contrast. Experiment 3 directly tested whether stereosensitivity depends on edge information whose disparity is detected independently at different spatial scales. Stereothresholds for IF + 5F compound targets were found to be equivalent to thresholds obtained separately with the more sensitive of the two components. Taken together with a compressive nonlinearity in the relationship between contrast and stereothreshold obtained by others (Halpern and Blake, 1989; Legge and Gu, 1989) and replicated in Expt 1, the results of Expt 3 indicate that, whatever the exact nature of the luminance discontinuity information utilized in disparity detection, it is processed independently at different spatial scales.     

Use of electronic data processing at a urologic polyclinic--a program packet for recording and evaluating data of specialized consultations

A software package was developed for computerized recording and processing of clinical data in a urological out-patient clinic. In a pilot study this program proved to be useful for the rapid evaluation of all important clinical and laboratory results of patients with renal cell carcinoma, and its use also accelerated the preparation of medical reports. The experience gained in this initial project shows that the application of this newly developed concept of data processing can easily be extended to routine out-patient followup in other special areas within the field of oncology.     

Investigations concerning the potential for using 1H NMR relaxometry or high-resolution spectroscopy of plasma as a screening test for malignant lung disease

In 158 plasma samples, obtained from patients with lung carcinoma, lung metastases, and infectious or inflammatory lung diseases and from healthy controls, the NMR relaxation times T1 and T2 of water protons were measured at a resonance frequency of 20 MHz by pulsed NMR techniques and adjusted to a standardized total plasma protein concentration. For one-third of these samples water-suppressed 500-MHz 1H NMR spectroscopy at 37 degrees C was used (a) to determine the widths of the composite lipid methyl and methylene signals, and (b) to quantitate individual lipid methylene signal components that could be detected in resolution-enhanced spectra. In addition, hematological parameters and the plasma levels of several acute phase proteins and apolipoprotein-A were monitored. No diagnostically significant differences between lung carcinoma patients and patients with nonmalignant lung disease could be found for any of the plasma NMR parameters, nor could T1 or lipid linewidth data distinguish between any patient group and healthy controls. However, the mean T2 was significantly shortened by about 15% for any kind of lung disease compared to healthy controls. Similar but less significant results were found for apolipoprotein-A levels. A linear discriminant function, calculated from the apolipoprotein-A and T2 data, did not improve the differentiation between malignant and nonmalignant lung disease but did improve the discrimination between tumor patients and healthy controls up to a sensitivity and specificity of 80 and 96.5%, respectively. T2 correlates inversely with plasma fibrinogen levels and the blood sedimentation rate and, therefore, appears to monitor a general inflammatory status of a tumor patient rather than the presence or absence of cancer. For all groups except healthy pregnant women, the lipid methylene composite signal linewidth correlates inversely with the fraction of mobile triglyceride present (mainly as VLDL), as estimated from resolution-enhanced spectra.     

Aspects of speech motor control: programing of repetitive versus non-repetitive speech

The aim of the present study was to investigate whether time to program repetitive speech movements (RS) would be distinct from time to program non-repetitive speech movements (NRS) when the length of sequences is kept constant. Using an oral reading task, latencies for the initiation of RS and NRS were measured under two conditions which allowed delineation of the time necessary for perceptual processing separated from actual motor programing. The results show that latencies for NRS were significantly longer than for RS, indicating that the nature of an utterance, not simply its length, is a determinant of program complexity.     

Increased F-wave duration in patients with spasticity.

F-wave responses of the posterior tibial nerve have been studied in 22 patients with spasticity and in 18 normal control subjects with surface EMG. Mean amplitude and mean duration of the F-waves were significantly (p less than 0.001) longer in patients with spasticity than in healthy controls. These findings could be the result of an enhanced spinal excitability in spasticity. Based on the present results F-wave recording may be used as a simple and practical technique for detection and documentation of spasticity.     

An external stimulus that mimics Mls locus responses

The response to a novel set of T cell mitogens has been analysed and compared to the response to Mls locus differences. These polyclonal T cell activators, staphylococcal enterotoxins A and B, stimulate T cells in a way that requires an antigen-presenting cell bearing class II MHC products and involves the CD4:T cell receptor complex. However, the specificity of MHC recognition by the T cell receptor is lost in this response. Thus, these mitogens produce a response with characteristics similar to that induced by Mls locus differences. These mitogens can be used to analyse the immunobiology of this response, and may help in understanding and identifying the Mls locus product as well.     

Primary Care Physician Compensation Method in Medical Groups: Does It Influence the Use and Cost of Health Services for Enrollees in Managed Care Organizations?

Context.— Growth of at-risk managed care contracts between health plans and medical groups has been well documented, but less is known about the nature of financial incentives within those medical groups or their effects on health care utilization. Objective.— To test whether utilization and cost of health services per enrollee were influenced independently by the compensation method of the enrollee's primary care physician. Design.— Survey of medical groups contracting with selected managed care health plans, linked to 1994 plan enrollment and utilization data for adult enrollees. Setting.— Medical groups, major managed care health plans, and their patients/enrollees in the state of Washington. Study Participants.— Sixty medical groups in Washington, 865 primary care physicians (internal medicine, pediatrics, family practice, or general practice) from those groups and affiliated with 1 or more of 4 managed care health plans, and 200931 adult plan enrollees. Intervention.— The effect of method of primary care physician's compensation on the utilization and cost of health services was analyzed by weighted least squares and random effects regression. Main Outcome Measures.— Total visits, hospital days, and per member per year estimated costs. Results.— Compensation method was not significantly (P>.30) related to utilization and cost in any multivariate analyses. Patient age (P<.001), female gender (P<.001), and plan benefit level (P<.001) were significantly positively related to visits, hospital days, and per member per year costs. The primary care physician's age was significantly negatively related (P<.001) to all 3 dependent measures. Conclusions.— Compensation method was not significantly related to use and cost of health services per person. Enrollee, physician, and health plan benefit factors were the prime determinants of utilization and cost of health services.