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At least 919 records · Page 51Linked to original sources
PubMedDate not supplied

[Pulse rate counter with digital read-out].

An all-purpose pulse rate counter with digital read-out, devised at the All-Union Research Institute of Radioelectronic Medical Equipment, is described. The counter is intended both for a separate use and also as a part of a complex set of the patients monitoring apparatus, the ones for functional diagnosis, mass examinations of the population and for research work. In combination with a commutator the device permits creation of multichannel systems of control.

Humans↗
PubMedDate not supplied

Development of a prototype magnetically suspended rotor ventricular assist device.

A continuous flow centrifugal blood pump with magnetically suspended impeller has been designed, constructed, and tested. The system can be functionally divided into three subsystem designs: 1) centrifugal pump and flow paths, 2) magnetic bearings, and 3) brushless DC motor. The centrifugal pump is a Francis vane type design with a designed operating point of 6 L/min flow and 100 mmHg pressure rise at 2,300 RPM. Peak hydraulic efficiency is over 50%. The magnetic bearing system is an all active design with five axes of control. Rotor position sensors were developed as part of the system to provide feedback to a proportional-integral-derivative controller. The motor is a sensorless brushless DC motor. Back electromotive force voltage generated by the motor is used to provide commutation for the motor. No slots are employed in the motor design in order to reduce the radial force that the bearings must generate. Tests pumping blood in vitro were very encouraging; an index of hemolysis of 0.0086 +/- 0.0012 was measured. Further design refinement is needed to reduce power dissipation and size of the device. The concept of using magnetic bearings in a blood pump shows promise in a long-term implantable blood pump.

Blood Volume↗
PubMed1996

Nuclear accumulation and homeostasis of the unusual polymer beta-poly (L-malate) in plasmodia of Physarum polycephalum.

The plasmodium of Physarum polycephalum specifically contains an unusual polyester, beta-poly(L-malate), which is not found in any of the mononucleate forms of its life cycle. Plasmodia growing on D-glucose have been analyzed for beta-poly(L-malate) in nuclei, cytosol and culture medium after cell fractionation, purification by chromatography on DEAE-cellulose and digestion of proteins/nucleic acids. Nuclei contained 400 micrograms polymer per 1 g of plasmodia, corresponding to a nuclear concentration of 230 mM L-malyl residues, not depending on growth rates, lengths of growth periods, and the growth form as micro- or macroplasmodia. The synthetic rate increased during the phase of rapid enlargement of the nuclei after mitosis. Beta-Poly(L-malate) was polydisperse in molecular mass, these tending to be higher in nuclear than in cytosolic extracts and being lowest in the culture medium. Beta-Poly(L-malate) was not degraded when contained in plasmodia, in contrast to degradation and the occurrence of low molecular mass polymer in the culture medium. During pulse-chase feeding with D-[14C]glucose (0.8 micrometerCi/mol), beta-[14C]poly(L-malate) appearance followed kinetics indicating a release of polymer from nuclei into the culture medium when it was in excess of a threshold. Injection experiments with purified beta-[14C]poly(L-malate) revealed a re-entry from the cytoplasm into the nuclei and thus the possibility of commutation between the cytoplasm and the nuclei. The observed homeostasis in nuclei supports the assumption that beta-poly(L-malate) plays an essential role in growing plasmodia.

Animals↗
PubMed1997

Violence and injury mortality in the Cape Town metropole.

OBJECTIVE: To describe accurately the violence and injury mortality in a South African city and demonstrate the utility of secondary data sources to identify injury control priorities. DESIGN: Cross-sectional analysis of medicolegal laboratory (state mortuary), forensic and police data. SETTING: Metropolitan Cape Town, 1994. RESULTS: Non-natural causes (deaths due to homicide, suicide, accidents and undetermined causes) accounted for almost 4000 deaths, which comprised approximately 30% of all-cause mortality during 1994. The five main violence and injury mortality categories were: homicide (1789 cases; 46% of all non-natural mortality), transport accidents (1130 cases; 29% of all non-natural mortality), fire (295 deaths; 8% of all non-natural mortality), suicide (291 deaths; 7% of all non-natural mortality) and drowning (96 cases; 2% of all non-natural mortality). CONCLUSIONS: Priority issues in injury control include the increasing homicidal and suicidal use of firearms, road and rail commuter injury and the spatial distribution of injury. Surveillance, based on non-natural mortality, should be included in local, regional and national health information systems.

Adolescent↗
PubMed1997

Correlates of college student marijuana use: results of a US National Survey.

This study examines which personal student background and college characteristics are associated with marijuana use. A self-administered survey was mailed to a national representative sample of 17592 students at 140 American colleges. One of four (24.8%) students reported using marijuana within the past year. Rates of use among the colleges ranged from zero per cent at the lowest use schools to 54% at the highest use schools. Multiple regression models, constructed to determine the college and student characteristics predicting marijuana use, suggest that use was higher among students at non-commuter colleges and at colleges with pubs on campus. Student characteristics associated with marijuana use included being single, white, spending more time at parties and socializing with friends, and less time studying. Marijuana use was higher among students who participate in other high risk behaviors such as binge drinking, cigarette smoking and having multiple sexual partners, and among students who perceived parties as important, and religion and community service as not important. The study points to the social nature of drug use in college, and demonstrates that this behavior is of continuing concern for public health.

Adolescent↗
PubMedDate not supplied

Determinants of tick-avoidance behaviors in an endemic area for Lyme disease.

BACKGROUND: Tick bite control is an important initiative to prevent Lyme disease and other tickborne infections. While several studies have demonstrated that knowledge and awareness of Lyme disease in endemic areas are good, none has evaluated the relative importance of knowledge with other attitudinal and health belief variables to determine motivators of preventive behavior. METHODS: We conducted a cross-sectional analysis of 304 commuter ferry passengers departing Martha's Vineyard Island, Massachusetts, in August 1992, to ascertain the prevalence of tick-avoidance behaviors among individuals from an endemic area of Lyme disease and to identify the knowledge, behavioral, and demographic variables that best determine precautionary behavior. RESULTS: Overall, survey respondents (n = 304) had very good knowledge of Lyme disease (73% items correct on a knowledge test), but only 59% of respondents reported limiting time in tick areas, 58% usually wore protective clothing, 40% wore tick repellent, and 66% usually performed tick checks. By stepwise linear regression analysis, determinants of tick-avoidance behaviors included perceiving the behavior's benefits as outweighing its inconvenience (P < .0001), having confidence in recognizing Lyme disease symptoms (P < .0004), believing that Lyme disease is a serious illness (P < .0009), and believing that the avoidance behavior is effective in reducing the risk of Lyme disease (P < .01). Younger respondents (P < .05) performed fewer avoidance behaviors. Visitors (P < .0001) performed fewer tick checks than residents. Having confidence that one could find a tick on oneself with a tick check also predicted performance (P < .008). Increased general knowledge about Lyme disease did not predict any protective behaviors. CONCLUSIONS: Precautionary behaviors were underperformed in an at-risk population despite good knowledge of Lyme disease symptoms and transmission. Instead, performance was related to confidence in finding a tick on oneself and a perception that a precaution's benefit outweighed its inconvenience and would adequately reduce risk for Lyme disease. These data have implications for Lyme disease prevention programs, which typically focus on enhancing general knowledge as a means toward disease reduction.

Adult↗
PubMed1998

Multicenter harmonization of common enzyme results by fresh patient-pool sera.

A region consisting of 19 clinical laboratories harmonized their calibration of seven common enzymes by using fresh patient-pool sera. One of the laboratories was chosen to act as Regional Reference Laboratory (RRL). This laboratory used internationally accepted (mostly IFCC) methods at 37 degrees C, with an intralaboratory CV < or = 2.5%. First, the reference ranges of the RRL were verified by analysis of a reference population and calculation of the results by a parametric method. Next, all laboratories, including the RRL, received six patient-pool sera and analyzed them at the same time on the same date. Enzyme calibration factors at each laboratory were converted on the basis of the slope, and occasionally the intercept, of regression analysis with the RRL and the individual laboratory. Before harmonization, the interlaboratory CVs varied from 16.9% to 61.6%. After harmonization, CVs decreased to between 5.0% and 9.5%. These results proved to be reproducible over a period of more than a year. Using internationally accepted inaccuracy and imprecision criteria, the achieved interlaboratory CVs permit the use of one set of reference ranges by all participating laboratories. Certified Reference Materials were analyzed, resulting in interlaboratory CVs as low as those achieved with patient-pool sera. These materials can act as commutable reference preparations, except for creatine kinase.

Alanine Transaminase↗
PubMed1998

Haematology outreach clinics in the Free State and northern Cape.

OBJECTIVE: Evaluation of haematology outreach clinics in the Northern Cape and Free State. DESIGN: Retrospective analysis of records from March 1994 to February 1996. SETTING: Central South Africa is sparsely populated. Consultants from Bloemfontein held outpatient clinics in hospitals (with laboratories) in Bethlehem, Kimberley and Kroonstad. SUBJECTS: 117 patients with suspected haematological disease. MAIN OUTCOME MEASURES: Input measures (population, number of clinics and costs), process measures (patient numbers, patients per clinic, new consultations per clinic, patients' domicile, how they were referred, types of diagnoses and number of patients with non-haematological disorders) and output measures (attrition, changes in attendance and savings). MAIN RESULTS: The 84 clinics that were held, with 636 consultations, did not cost the State anything. Only 6% of the 117 patients had no haematological problem. Sixty-eight per cent had chronic haematological neoplasms. In Kimberley most of the patients came from Kimberley Hospital, while most of the patients at the other clinics were referred via Bloemfontein. There was only a 10% attrition rate and only one-third of patients were referred to Bloemfontein. We saved paying patients an estimated R21,260 in transport costs, while saving the State R172,992 by seeing patients at secondary, instead of tertiary, hospitals. CONCLUSIONS: It is cheaper to send a doctor to an outreach clinic than to refer patients to a central facility, provided there is enough work for a doctor at the clinic. It costs the State much less for patients to be seen at a secondary than a tertiary hospital. Positive spin-offs include academic stimulation of doctors and laboratories in the periphery, with more appropriate referrals to teaching hospitals. Weaknesses include poor availability of expensive drugs at the clinics and lack of standardised records. By commuting to outreach clinics, specialists can greatly reduce health expenditure and spread it from tertiary to lower levels. At the same time more patients have access to their services.

Costs and Cost Analysis↗
PubMed1997

Applicants to B.Sc.N., R.N., and R.P.N. nursing programs: differences and predictors.

We surveyed 205 applicants to three types of nursing programs (B.Sc.N., diploma-R.N., and diploma-R.N.A.) offered in Toronto, Ontario. Applicants were predominately white, unmarried women living within commuting distance of the institutions to which they applied. Applicants to practical nursing programs tended to be older than applicants to B.Sc.N. and diploma-R.N. programs, be married, have at least one dependant, come from blue-collar families, be out of school longer, and submit fewer applications. Applicants with dependants were 11 times more likely to choose R.P.N. over R.N. programs. Recency of graduation and high school average were predictive of choosing B.Sc.N. over R.N. programs. While this 1992 cohort had some appreciation for the challenges facing the nursing profession, most applicants still expected to secure full-time employment in acute care post-graduation. The data provide an important benchmark for comparing current and future cohorts of applicants with respect to socio-demographic characteristics and expectations of nursing as a career choice.

Adolescent↗
PubMed1995

[Peptic ulcer among workers in the engineering and chemical industries].

Incidence of peptic ulcer among workers employed in the engineering and chemical industries is presented in view of selected environmental factors. The study covered 157 workers with peptic ulcer who reported themselves to outpatient clinics at the Nitrogenous Fertilizers Plant in Pulawy and the Automobile Works in Lublin (5000 and 3252 employees, respectively). The study was conducted over a period of one year. It included: medical examinations, supplementary tests and a questionnaire survey. The questionnaire asked, among others, about working conditions, type of occupation performed and lifestyle. Peptic ulcer was diagnosed in 2.03% of workers engaged in the engineering industry and 1.82% of those working at the chemical plant. The incidence of peptic ulcer was higher among manual workers (2.18%) than in office workers (1.16%). The patients had been exposed to the following environmental factors: excessive noise--21%, vibration--17.2%, commuting--11.5%, extra work--14.5%, conflicts at work--13.5%, conflicts at home--15.3%, irregular meals--21.6%, alcohol intake--22.4%, cigarette smoking--62.4%. The study indicates that peptic ulcer is more often diagnosed in manual than in office workers and its incidence can be associated with working conditions and lifestyle. However, no significant variation in annual morbidity caused by peptic ulcer was observed among workers of the plants under study.

Chemical Industry↗
PubMed1985

Demographic-economic analysis in a multi-zonal region: a case study of Nordrhein-Westfalen.

"This paper develops a series of spatially-disaggregated demographic-economic models, based on an extended Leontief type input-output model. Travel between residence and place of work and residence and place of shopping is included in the models, and a detailed decomposition of a range of multipliers identified. A model explicitly involving travel to work is developed empirically for the state of Nordrhein-Westfalen in West Germany, and sets of multipliers presented which relate changes in demographic and economic variables in particular zones of the state with changes in economic output and employment-related variables in other zones."

Behavior↗
PubMed1986

The distribution of population and employment in a polycentric city: the case of Los Angeles.

"The distribution of population and employment in metropolitan Los Angeles in 1970 and 1980 is examined in this paper. Population continued to disperse in the 1970s, whereas the geographical distribution of employment combined job clustering around a few major employment centers with a high degree of general job dispersion. In Los Angeles polycentrism has been associated with shorter work trips, particularly intracounty trips in the more peripheral counties." Population data are for 2,403 comparable census tracts for 1970 and 1980; data concerning geographical employment distribution are from the 1980 census.

Americas↗
PubMed1998

South-East Asia.

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Acquired Immunodeficiency Syndrome↗
PubMed1997

Sexual networks in Uganda: mixing patterns between a trading town, its rural hinterland and a nearby fishing village.

The study was based in south-west Uganda where significant differences in HIV prevalence have been found between urban and rural areas. Longitudinal data collected in a diary format was used to determine the extent to which high-risk men and women living in a truck stop/trading town had sexual contact with people from surrounding rural areas and a nearby fishing village. Study participants were 143 men, 75 of whom were resident in the town, 40 in a fishing village and 28 in rural areas, and 81 women, of whom 47 were resident in the town, 25 in the fishing village and 9 in a rural area. During 1687 man weeks the 143 men made 3149 trips and had 5189 sexual contacts. Ninety-two per cent of these sexual contacts occurred in the man's current place of residence and 21% were with a new partner. The 81 women participated for 1280 women weeks during which they recorded 6378 sexual contacts. Women who lived in the fishing village and the rural area had around 90% of their contacts with local men while those who lived in the town fell into 3 categories: women who charged a relatively high price for commercial sex had only 11% of contacts with men living in the town, while those who charged a tenth of the price had 71% of contacts with town men. The small number of women who fell into an intermediate category, in terms of price, had sexual contact with a wide variety of men. These findings show that there is little scope for HIV infection to spread between different residential or occupational groups. This may help to explain how large differences in HIV seropositivity between neighbouring localities can be maintained for long periods, despite considerable social and economic mixing between groups and high levels of sexual partner change within groups.

Adolescent↗