Squeezing the quantum noise of a gravitational-wave detector below the standard quantum limit.

The Heisenberg uncertainty principle dictates that the position and momentum of an object cannot be simultaneously measured with arbitrary precision, giving rise to an apparent limitation known as the standard quantum limit (SQL). Gravitational-wave detectors use photons to continuously measure the positions of freely falling mirrors and so are affected by the SQL. We investigated the performance of the Laser Interferometer Gravitational-Wave Observatory (LIGO) after the experimental realization of frequency-dependent squeezing designed to surpass the SQL. For the LIGO Livingston detector, we found that the upgrade reduces quantum noise below the SQL by a maximum of three decibels between 35 and 75 hertz while achieving a broadband sensitivity improvement, increasing the overall detector sensitivity during astrophysical observations.

A postmortem study of the mediodorsal nucleus of the thalamus in schizophrenia.

Four studies have reported that the mediodorsal nucleus of the thalamus (MD) is smaller and contains fewer neurons in schizophrenia. The MD is a key node in a circuit proposed to be dysfunctional in the disorder. However, one study did not find a MD volume loss in schizophrenia, and all the studies to date are relatively small. Given the importance of establishing unequivocally the presence of MD pathology, we have carried out a study of the volume and number of neurons in the left and right MD in 21 patients with schizophrenia and 27 healthy comparison subjects. We also measured the size of MD neurons, and estimated total thalamic volume. We found no difference in the volume of the MD, the number of MD neurons, or the size of MD neurons in either hemisphere in schizophrenia. Neither was total thalamic volume altered. There are no obvious methodological or clinical factors to explain our failure to replicate the finding of MD involvement in schizophrenia. Hence our negative observations, in the largest sample yet investigated, cast doubt on the robustness and/or the generalisability of MD neuropathology in schizophrenia.

Comparing the characteristics of schools that produce high percentages and low percentages of primary care physicians.

To examine whether the medical school environment is important in influencing students to choose careers in primary care, the authors in 1991 compared certain characteristics of the environments of schools that produced high percentages of primary care physicians with those of schools that produced low percentages over a five-year period. The authors used the American Medical Association Physician Masterfile to identify the percentage of graduates of each of 121 medical schools for the period 1981-1985 who entered primary care specialties. They then compared the 25 schools that produced low percentages (22-29%) with the 25 schools that produced high percentages (39-56%). The results demonstrate important differences between the two groups of schools in their commitments to primary care education, their research programs, and their clinical environments supporting required clerkships. The authors conclude that a school's educational environment is an important factor in influencing some students to pursue careers in primary care medicine.

The long-term effect of an innovative family physician curricular pathway on the specialty and location of graduates of the University of Washington.

PURPOSE: To report the specialty and rural/urban distribution a mean of 19 years after graduation for a cohort of students from a family physician curricular pathway. METHOD: Specialty and location information for medical students who had entered the University of Washington between 1968 and 1973 was obtained from the 1994 Physician Masterfile of the American Medical Association. RESULTS: Of the 239 family physician pathway graduates, 173 (72%) had intended family practice at graduation, and 136 (57%) were family physicians two decades later. The proportions of all graduates in family practice and of graduates serving rural Washington as family physicians had increased over that of a cohort of students who had entered the University of Washington prior to the introduction of the pathway curriculum. These proportions surpassed the goals set at the time the new curriculum was introduced. CONCLUSION: With early identification and support of students interested in family practice, an increased number entered the specialty and were still family physicians in mid-career.

Locus of control orientation among obese adults in outpatient treatment for obesity.

We studied locus of control (LOC) in samples of obese and nonobese subjects. We administered Rotter's (1966) I-E Scale to 106 obese adults in outpatient treatment for obesity and to 99 nonobese controls. The obese subjects were significantly more internally oriented than the control group. These findings challenge currently held assumptions on the directionality of LOC in obese groups. The results contradict the consensus among researchers that obese individuals have an external LOC orientation. The finding that internal LOC is associated with the obese condition may be a useful predictor variable influencing obesity treatment, approaches, and outcome.

Radiation losses from single-mode optical Y junctions formed by silver-ion exchange in glass.

Single-mode optical Y junctions have been fabricated using silver-ion exchange in glass. Radiation losses are given for several different input conditions to the branch arms when the Y junction is used as an optical power combiner. A minimum radiation loss of 3 dB has been measured when only one branch arm is excited.

The development and use of a comprehensive test for evaluating decentralized medical education--the WAMI experience.

The development of a comprehensive examination at the end of the first year of medical school is discussed. The implications of the results for the evaluation of the WAMI Program in decentralized medical education are presented.

The National Health Service Corps: rural physician service and retention.

BACKGROUND: The National Health Service Corps (NHSC) scholarship program is the most ambitious program in the United States designed to supply physicians to medically underserved areas. In addition to providing medical service to underserved populations, the NHSC promotes long-term retention of physicians in the areas to which they were initially assigned. This study uses existing secondary data to explore some of the issues involved in retention in rural areas. METHODS: The December 1991 American Medical Association (AMA) Masterfile was used to determine the practice location and specialty of the 2903 NHSC scholarship recipients who graduated from US medical schools from 1975 through 1983 and were initially assigned to nonmetropolitan counties. We used the AMA Masterfile to determine what percentage of the original cohort was still practicing in their initial county of assignment and the relation of original practice specialty and assignment period to long-term retention. RESULTS: Twenty percent of the physicians assigned to rural areas were still located in the county of their initial assignment, and an additional 20 percent were in some other rural location in 1991. Retention was highest for family physicians and lowest for scholarship recipients who had not completed residency training when they were first assigned. Retention rates were also higher for those with longer periods of obligated service. Substantial medical care service was provided to rural underserved communities through obligated and postobligation service. Nearly 20 percent of all students graduating from medical schools between 1975 and 1983 who are currently practicing in rural counties with small urbanized populations were initially NHSC assignees. CONCLUSIONS: Although most NHSC physicians did not remain in their initial rural practice locations, a substantial minority are still rural practitioners; those remaining account for a considerable proportion of all physicians in the most rural US counties. This study suggests that rural retention can be enhanced by selecting more assignees who were committed to and then completed family medicine residencies before assignment.

Predicting performance during clinical years from the new Medical College Admission Test.

The results of a predictive validity study of the new Medical College Admission Test (MCAT) using criteria from the clinical years of undergraduate medical education are presented and discussed. The criteria included course grades and faculty ratings of clerks in internal medicine, surgery, obstetrics and gynecology, pediatrics, and psychiatry; scores on a comprehensive test of clinical knowledge (including patient management type examinations); and scores on Part II of the examinations of the National Board of Medical Examiners (NBME). While the validity coefficients of the MCAT with the Part II examinations ranged from .03 to .47, they were higher than those of undergraduate grade-point averages with the same criteria. The implications of the small-to-medium size validity coefficients for admissions are discussed.

Evaluating student performance in a decentralized basic science program.

The results of the evaluation of the basic science curriculum in a regionalized medical education program in the states of Washington, Alaska, Montana, and Idaho (WAMI) are presented and discussed. The hypothesis that students taking the first quarter of basic science at universities remote from the Unversity of Washington School of Medicine (UWSM) will be no different in academic performance from those who remain at the UWSM is tested. The variables considered were student performance on (a) common tests in Anatomy/Histology, Biochemistry, Mechanisms of Physiology, and Epidemiology; (b) subsequent course work at the UWSM; and (c) the mini-tests and Part I of the examinations of the National Board of Medical Examiners. The developement of the common tests is described. Analysis of variance indicates that the null hypothesis cannot be rejected at the .05 level.

Career preferences of first- and second-year medical students: the WAMI experience.

Students admitted directly to the Seattle campus of the University of Washington School of Medicine are predominately from metropolitan areas. Students completing their first year at affiliated programs at Washington State University, University of Alaska, Montana State University, and the University of Idaho are predominately from nonmetropolitan areas. The authors compared these two groups of students with respect to preferred specialties and practice location; in addition, these preferences were examined on the basis of the size of students' home communities. Factor analysis of the preferences indicated by three entering classes at the end of their second year identified interpretable clusters of specialties and location types. Few differences were found in preferences for specialties, either between the groups or based on size of home community. Differences in attitudes toward location of practice indicated that students favor commmunities similar to those in which they were raised. The preferences indicated by second-year students were found to be significantly related to those expressed by the same students as they entered medical school, suggesting stability of student attitudes toward career choices. These results indicate that increased admissions from nonmetropolitan areas may affect the distribution of physicians by region but not by specialty.

Predicting first-quarter test scores from the new Medical College Admission Test.

The predictive validity of the new Medical College Admission Test as it relates to end-of-quarter examinations in anatomy, histology, physiology, biochemistry, and "ages of man" is presented. It is recognized that the maximum predictive power is attenuated by the reliability of the criterion variables. To determine the value of attempting to increase the reliability in the criteria, the authors corrected the validity coefficients for attenutation. Regression analyses were also undertaken to examine the extent to which the new MCAT subtests can predict scores on end-of-quarter examinations. Results indicate that the Science Knowledge assessment areas of chemistry and physics and the Science Problems subtest were the most useful in predicting student performance, followed by the Skills Analysis: Quantitative and Skills Analysis: Reading subtests and the biology area of the Science Knowledge subtest.

Geographic and specialty distributions of WAMI Program participants and nonparticipants.

In an effort to make the geographic distribution of physicians closer to the distribution of the population as a whole, in 1971 the states of Washington, Alaska, Montana, and Idaho established the WAMI Program. In a departure from the Flexnerian model of medical education, the WAMI Program was organized to distribute the components of medical education throughout the region, both at the medical center at the University of Washington School of Medicine and at remote sites. In the present article, the authors describe the results of the first seven years of the program (1975-1981) in terms of the geographic and specialty distribution of the school's graduates before and after the establishment of the program. At the time of the study, 23 percent of the graduates with WAMI Program experience practiced in nonmetropolitan areas as defined by the U.S. Bureau of the Census. Only 13 percent of all U.S. physicians practiced in such areas in 1981, while 24 percent of the U.S. population lived there. In addition, 61 percent of the graduates with program experience were in primary care practice in contrast to 35 percent of all U.S. physicians. If all U.S. physicians behaved as these graduates do, the distribution of U.S. physicians would be reversed, with the proportion of physicians practicing primary care in nonmetropolitan areas being larger than the proportion of the population living in those areas.

The effect of federal grants on medical schools' production of primary care physicians.

OBJECTIVES: Title VII of the Health Professions Educational Assistance Act of 1976 was created to encourage the production of primary care physicians. This study explored recent trends in the proportion of US medical school graduates entering primary care in relationship to Title VII funding. METHODS: The American Medical Association Physician Masterfile was used to determine the specialty choice of all students graduating from American medical schools between 1960 and 1985. RESULTS: The proportion of graduates entering primary care rose from 19.7% in 1967 to 31.1% in 1976 and remained stable for the subsequent decade. The increase occurred before implementation of Title VII. Rural, state-owned medical schools with departments of family medicine tend to produce a greater proportion of primary care physicians than urban private schools without family medicine departments. CONCLUSIONS: The values of American medical schools and the reward structure of American medical practice favor the production of specialists over primary care physicians. Although Title VII helped to encourage and sustain the development of primary care educational programs at both the medical student and graduate levels, an increase in the proportion of primary care physicians will require fundamental changes.

Which medical schools produce rural physicians?

OBJECTIVE: To examine the hypothesis that medical schools vary systematically and predictably in the proportion of their graduates who enter rural practice. DESIGN: The December 1991 version of the American Medical Association Physician Masterfile was used to examine the rural and urban practice locations of physicians who graduated from American medical schools between 1976 and 1985. Selected characteristics of the medical schools--including location, ownership, and funding--were linked to the Physician Masterfile. MAIN OUTCOME MEASURES: The percentage of the graduates from each medical school who were practicing in rural areas in December 1991, disaggregated by physician specialty. RESULTS: Of the practicing graduates from our study, 12.6% were located in rural counties; family physicians were much more likely than members of other specialties to select rural practice, particularly in the smallest and most isolated rural counties. Women were much less likely than men to enter rural practice. Medical schools varied greatly in the percentage of their graduates who entered rural practice, ranging from 41.2% to 2.3% of the graduating classes studied. Twelve medical schools accounted for over one quarter of the physicians entering rural practice in this time period. Four variables were strongly associated with a tendency to produce rural graduates: location in a rural state, public ownership, production of family physicians, and smaller amounts of funding from the National Institutes of Health. DISCUSSION: The organization, location, and mission of medical schools is closely related to the propensity of their graduates to select rural practice. Increasing policy coordination among medical schools and state and federal governmental entities would most effectively address residual problems of rural physician shortages.

Picosecond pump-probe interferometric measurement of optical nonlinearities in channel waveguides.

An interferometric technique for measuring with picosecond resolution the time evolution of the real and imaginary components of optical nonlinearities in channel waveguides is described. Characteristics of the technique are illustrated with measurements of band-filling optical nonlinearities in CdS(x)Se(1-x)-doped glass channel waveguides.