Search PubMed⌕ Search

Biomedical subjects

P M Peterson

Publications and source records attributed to P M Peterson.

14 recordsLinked to original sources
PubMed1996

Comparison of additive and multiplicative models of regional variation in the decline of stroke mortality in the United States.

BACKGROUND AND PURPOSE: Although previous studies have shown that geographic variation in the decline of stroke mortality rates may be an important contributor to the changing geographic distribution of stroke mortality in the United States, some concern has been raised that this phenomenon may be model dependent. This study examines the geographic variation in the decline of stroke mortality rates in the United States with the use of both additive and multiplicative models. METHODS: National Center for Health Statistics and Bureau of the Census data were used to assess regional-level temporal trends of underlying-cause stroke mortality rates in the United States for 1979 through 1989. Both additive and multiplicative models were fit to the data. RESULTS: Underlying-cause stroke mortality rates have declined fairly steadily in all regions of the United States and for all race-sex groups, although there was significant regional variation in the rate of decline during the period 1979 through 1989. The South, which initially had the highest rates, had the most rapid decline for all race-sex groups when either additive or multiplicative models were used. CONCLUSIONS: From 1979 through 1989 there was significant geographic variation in the rate of decline of stroke mortality rates, with the most rapid rates of decline in the South. As a result, there has been a decrease in interregional variation in stroke mortality rates.

Age Factors↗
PubMed1995

Geographic variation in reporting of stroke deaths to underlying or contributing causes in the United States.

BACKGROUND AND PURPOSE: This study examines the geographic variation in the reporting of deaths with stroke as the underlying or contributing cause in the United States. METHODS: Data from the National Center for Health Statistics and Bureau of the Census were used to map the geographic distribution of race- and race/sex-specific, underlying-, contributing-, and multiple-cause age-adjusted stroke mortality rates in the United States by state for 1979 through 1981. RESULTS: Underlying-, contributing-, and multiple-cause age-adjusted stroke mortality rates were significantly clustered for both whites and blacks. However, the spatial distributions of underlying- and contributing-cause rates differed; there was no association between underlying- and contributing-cause rates for either racial group or for the various race/sex groups. There was no association between nonstroke mortality and stroke mortality rates. There was also very little spatial variation and no spatial clustering of the median number of contributing causes reported. CONCLUSIONS: The overall large-scale spatial distribution of resident underlying-cause stroke mortality rates cannot be explained by geographic variation in the selection of the underlying cause of death from among all causes reported on the death certificate, by different area-dependent tendencies for mortality generally, or by different tendencies to consider stroke as the cause of death when death occurs. Geographic variation in contributing-cause rates is not explained by variation in tendency to report contributing causes of death.

Age Factors↗
PubMed1995

Effects of interstate migration on the geographic distribution of stroke mortality in the United States.

BACKGROUND AND PURPOSE: This study examines the effects of lifetime net interstate migration on the geographic distribution of stroke mortality in the United States. METHODS: National Center for Health Statistics and Bureau of the Census data were used to map the geographic distribution of age-adjusted, race-, and race/sex-specific stroke mortality rates by interstate migration status for natives, outmigrants, nonmigrants, inmigrants, and residents in the United States for 1979 to 1981. RESULTS: High age-adjusted stroke mortality rates were significantly clustered in the southeastern United States for both whites and blacks; in addition, for whites, low-rate states were concentrated in some Mountain and northeastern states. Migrant status did not change this large-scale pattern, but individual states showed significant migration effects, which varied in magnitude and direction. Among whites, states that benefited from migration, with markedly lower stroke mortality rates among residents than natives, included Arizona, Colorado, District of Columbia, and Florida, whereas states that suffered from migration included California, Idaho, Montana, North Dakota, Nevada, and Oklahoma. Among blacks, only Colorado showed an apparent large benefit from migration, whereas 21 states suffered from migration. CONCLUSIONS: Although the overall large-scale spatial distribution of resident stroke mortality rates cannot be explained by migration effects, some individual states had rates that were strongly influenced by migration. Patterns of mortality among migrant groups in Sun Belt retirement destination states probably result from differential selection effects for retirement migration in older adults. Patterns of mortality for black migrants to the North are probably influenced by "carryover" effects from their origin states.

Adult↗
PubMed1995

Geographic variation in the decline of stroke mortality in the United States.

BACKGROUND AND PURPOSE: This study examines the geographic variation in the decline of stroke mortality rates in the United States. METHODS: National Center for Health Statistics and Bureau of the Census data were used to assess regional and state level temporal trends of stroke mortality in the United States for 1970 to 1989. RESULTS: Underlying- and multiple-cause stroke mortality rates have declined fairly steadily in all regions of the United States and for all race/sex groups, although the rates of decline were greater during 1970 to 1978 than during 1979 to 1989. The declines in underlying-cause rates could not be attributed to a shift toward reporting stroke as a contributing rather than underlying cause of death, since both underlying- and multiple-cause rates declined similarly. There was significant regional variation in the rate of decline, particularly during 1979 to 1989. The South initially had the highest rates, but it experienced the most rapid decline, so that by 1989 the South no longer had the highest rates. States with the most rapid rates of decline were significantly clustered in the South and particularly the Southeast. Most of the decline in overall stroke mortality was due to declines in ischemic stroke mortality. CONCLUSIONS: During 1970 to 1989 there was significant geographic variation in the rate of decline of stroke mortality rates, with the most rapid rates of decline concentrated in the high-rate areas of the South and particularly the Southeast. As a result, there has been a decrease in interregional and interstate variation in stroke mortality rates, which is apparently not due to an artifact of changing reporting patterns.

Age Factors↗
PubMed1990

Robustness of an adaptive beamforming method for hearing aids.

We describe the results of computer simulations of a multimicrophone adaptive-beamforming system as a noise reduction device for hearing aids. Of particular concern was the system's sensitivity to violations of the underlying assumption that the target signal is identical at the microphones. Two- and four-microphone versions of the system were tested in simulated anechoic and modestly-reverberant environments with one and two jammers, and with deviations from the assumed straight-ahead target direction. Also examined were the effects of input target-to-jammer ratio and adaptive-filter length. Generally, although the noise-reduction performance of the system is degraded by target misalignment and modest reverberation, the system still provides positive advantage at input target-to-jammer ratios up to about 0 dB. This is in contrast to the degrading target-cancellation effect that the system can have when the equal-target assumption is violated and the input target-to-jammer ratio is greater than zero.

Computer Simulation↗
PubMed1987

Multimicrophone adaptive beamforming for interference reduction in hearing aids.

To reduce interference in monaural hearing aids from sound sources that are spatially separated from a target source, we are investigating methods for combining information from multiple microphones. In this paper, we describe an adaptive beamforming method that functions to preserve target signals arriving from straight-ahead of a microphone array while minimizing output power from off-axis interference sources. In a preliminary evaluation of a two-microphone system, sentence intelligibility tests were administered to normal-hearing subjects using processed and unprocessed materials from simulated environments in which the target was on-axis, the interference (speech babble) was 45 degrees off-axis, and the reverberation mimicked that of a living room, a conference room, and anechoic space. Compared to listening through a single microphone, the two-microphone beamformer reduced the target-to-interference ratio required to achieve 50 percent keyword intelligibility by 30, 14, and 0 dB in the anechoic, living-room, and conference-room conditions, respectively. The corresponding improvements over binaural listening (one microphone to each ear) were 24, 9, and 0 dB. Further tests in the living-room environment using the same beam-forming system but with filter impulse responses shortened by a factor of four (which would decrease the adaptation time by a factor of four) decreased the improvement by 5 dB. These results are sufficiently encouraging to warrant further tests involving more realistic reverberant conditions, multiple sources of interference, and time-varying acoustic environments.

Acoustics↗
PubMed1986

Simulating the response of multiple microphones to a single acoustic source in a reverberant room.

A method is presented for simulating the impulse response between an acoustic source and multiple microphones in a reverberant room. The method is similar to the image method described by Allen and Berkley [J. Acoust. Soc. Am. 65, 943-950 (1979)] but includes modifications to simulate received echo arrival time accurately. The essential modification is to represent each received echo as a low-pass-filtered impulse at the correct arrival time. Using this "low-pass impulse" method, reverberant rooms can be simulated with sufficient accuracy to investigate multiple-microphone systems that are sensitive to interchannel phase.

Acoustics↗
PubMedDate not supplied

Spina bifida: the transition into adulthood begins in infancy.

Many concerns surround the preparation of a person with spina bifida for a successful transition into adult life and responsibilities. A model of intervention must be based on developmental concerns and timely issues from infancy through all stages of development to young-adult life. This article discusses, within a developmental framework, issues of transition in relation to physical, social, emotional, and educational/vocational needs; it also presents a conceptual framework for the transition into adulthood. Guidelines were developed by incorporating expected outcomes of people with spina bifida and using a philosophical framework that encompasses the achievement of a balance among dependence, independence, and interdependence. This model is based on developmental issues from infancy through all stages of development to young-adult life. Using this framework for care, the rehabilitation nurse can feel confident that the needs of clients with spina bifida and similar chronic conditions are being met.

Activities of Daily Living↗