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We provide a complete classification up to conjugacy of the binary shifts of commutant index 2 on the hyperfinite II(1) factor. There is a natural correspondence between the conjugacy classes of these shifts and polynomials over GF(2) satisfying a certain duality condition.
We provide a complete classification up to conjugacy of the binary shifts of finite commutant index on the hyperfinite II(1), factor. There is a natural correspondence between the conjugacy classes of these shifts and polynomials over GF(2) satisfying a certain duality condition.
Male passengers regularly commuting by train on the Stockholm-Nynäshamn line were investigated on two morning trips to Stockholm. These trips were made under different levels of crowding, before (Trip 1) and after (Trip 2) a period of gas rationing during the oil crisis in 1974. However, seats were available for almost everyone during both trips. One group of subjects boarded the train at its first stop (Nynäshamn), the other midway on its route (Västerhaninge). Physiological reactions were assessed from the rate of catecholamine excretion in urine and subjective experiences were measured by self-ratings. The results showed that feelings of discomfort grew more intense as the train approached Stockholm and the number of passengers increased. Perceived crowdedness increased as the square of the number of passengers. During both trips the subjects from Nynäshamn (longer trip) had a lower rate of adrenaline and noradrenaline excretion on the train than those from Västerhaninge. Furthermore, it was found that the rate of adrenaline excretion was higher for both groups during Trip 2, when the train was more crowded. The results support previous findings indicating that the stress involved in travelling by train varies more with the social and ecological conditions of the trip than with its length or duration.
The sexual behaviors and safer sex practices of college students at a midwestern commuter university are described. Responses from a student sample of 1,919 indicated that slightly more than 10% used condoms consistently. The most frequently cited reasons for not using condoms were monogamy (83%) and preferring other forms of birth control (31%). The leading reason for consistent condom use was fear of HIV infection (72%). Approximately 75% indicated they talked with their sexual partners about HIV prevention; women reported communicating significantly more often than men did (p < 0.0001). Seventy percent of the sample reported they had only one sexual partner during the past year. Students who had multiple partners during the past year were more likely to practice such unsafe sexual practices as not using condoms and not communicating about HIV prevention. Unsafe sexual practices occur on nontraditional university campuses just as frequently as they do on more traditional campuses, thus supporting the need for HIV prevention programs on every college and university campus.
The intermethod variability of control materials and patient blood samples for the measurement of hemoglobin A2 (HbA2) were compared. A set of 54 blood samples and 10 control materials were analyzed in duplicate by HPLC and microcolumn methods. For each set of methods the distances of the materials from the regression line of patient blood results (expressed as normalized residuals) were calculated. Four out of ten controls had normalized residuals exceeding three standard deviations from the regression line. Moreover, total Hb and Hb derivatives analysis proved that only a minority of the controls could be considered similar to patients' blood samples. Intermethod calibration performed "a posteriori" by the two best performing control materials improved intermethod variability among all the five tested methods. We conclude that the use of high resolution HPLC methods together with appropriate commutable control materials allows for better harmonization of results in the field of diagnosis of hemoglobin disorders in research and clinical practice.
Significant among-manufacturer differences in values for serum proteins persist 7 years after the introduction of the international reference material (Certified Reference Material 470; Reference Preparation for Proteins in Human Serum). In some cases, such as transthyretin and C4, the biases actually continue to increase. Further efforts at standardization are needed in order to improve commutability of results among laboratories and are essential if universal reference intervals are to be developed.
Certified Reference Material 470 (CRM 470) demonstrates commutability with both the manufacturer's calibrator and with dilutions of serum pools in the Dade Behring N High Sensitivity assay for C-reactive protein (CRP). Both regression and back calibration show similar nonlinearity for all materials, largely due to the method of calibration curve fitting used in this assay. Significant differences in values among the currently available commercial assays can be largely overcome by using appropriate calibration curve fitting and the recommended value transfer protocol, which includes a minimum of two assay runs on each of at least 3 separate days, with weight correction of all reconstitutions and dilutions. An initial weight-corrected dilution should be made each day because of the relatively high level of CRP in CRM 470. In our opinion, the degree of nonlinearity, imprecision, and differences in values in currently available assays renders the use of fixed clinical decision cut-points questionable for high-sensitivity CRP. An alternative approach is suggested.
Further studies have been carried out on the potential value of oxygen enrichment of room air for commuters to high altitude. Novel ways of providing oxygen-enriched spaces for working and sleeping are being tested at the California Institute of Technology where a radiotelescope is being designed for an altitude of 5,000 m in north Chile. The modules are containers such as those used on container ships, and they are fitted out in California and then sealed and transported to the telescope site in Chile. The result is a turnkey facility which shows promise for field studies. The oxygen is provided by oxygen concentrators, and different modules are used for sleeping, living, and laboratory quarters. Two extensive experiments on oxygen enrichment were carried out at the University of California White Mountain Research Station, altitude 3,800 m, in the summer of 1998. The first study was devoted to the mechanism for the increase in arterial oxygen saturation on the day after sleeping in an oxygen-enriched atmosphere compared with sleeping in ambient air (5). Possible mechanisms include less fluid accumulation in the lung associated with acute mountain sickness, or a change in the control of ventilation. A double blind study was therefore carried out of the effects of sleeping in oxygen enrichment on both the ventilatory response to hypoxia and to carbon dioxide. In a related study, subjects who had been at an altitude of 3,800 m for two days, and were therefore partially acclimatized, were studied at a simulated altitude of 5,000 both breathing ambient air and 27% oxygen. The studies were done at 3800 m altitude by enriching the atmosphere of the test room with appropriate amounts of nitrogen or oxygen. An extensive series of neuropsychological tests were carried out with the objective of determining which features of CNS function were improved by oxygen enrichment at an altitude of 5,000 m.
BACKGROUND: Between 1990 and 1998, aviation accidents in Alaska caused 100 occupational pilot deaths (equivalent to 430/100,000 pilots/ year, approximately 86 times the overall U.S. worker fatality rate). Although Alaskan geography and climate increase aviation risks, many accidents were attributed to pilot error. While most accidents occurred during takeoff/landing, most fatalities resulted from Controlled Flight Into Terrain (CFIT). The purpose of this study was to examine risk factors for CFIT. METHODS: Using National Transportation Safety Board airplane accident data we identified CFIT from flight phase and event description fields, and calculated odds ratios for CFIT/non-CFIT accidents for visual conditions, aircraft features, and pilot experience. RESULTS: Between 1991 and 1998, 351 single aircraft commuter and air taxi accidents occurred in Alaska; 59 (17%) were CFIT. Of 140 total fatalities, 82 (59%) occurred in 30 CFIT accidents. There was a twelve-fold risk for death in CFIT vs. non-CFIT accidents (OR = 12.42, 95% CI = 8.19-18.88). Accidents while flying Visual Flight Rules (VFR) into poor visibility were more likely CFIT than non-CFIT (Odds ratio = 46.06, Confidence Interval = 19.32-112.46), and caused 37% of all deaths. Additionally, flights in Instrument Meteorological Conditions (IMC) were 47 times more likely to be CFIT than non-CFIT. No risk for CFIT was shown for flight hours, number of engines, passenger presence, or pilot age. All CFIT were attributed to pilot error, often for continuing VFR into poor visibility. CONCLUSION: CFIT caused most aviation deaths. Further research into human factors contributing to CFIT is needed. Implementation of global-positioning, ground-proximity/avoidance technology, might reduce CFIT incidence.
Until recently, the investigation of crash injuries and their causes in railroad crashes has been relatively nonexistent. Now, however, with the trend toward a more balanced transportation system, the number of railroad passengers is increasing and there is a concurrent demand for new, rebuilt, or refurbished passenger cars. Most railroad passenger cars in service today appear to have been designed primarily for longevity and easy servicing with secondary emphasis on passenger comfort and little emphasis on passenger safety. It is unlikely that these priorities will be reversed unless crash injury investigations can demonstrate a specific need for improvements in crashworthiness. In line with this objective, techniques developed in aircraft crash investigations were used to collect and evaluate crash injury and escape data from the collision of two commuter trains.
The authors identified variables that enhance the predictability of academic performance and retention in an urban, commuter college. They used a longitudinal design with 2 waves of data collection: prior to 1st-semester attendance and again 6 semesters later. The results support the following conclusions: (a) After controlling for precollege indices of academic ability, specific variables within demographic, personal behavior, expectations, and attitudinal domains improved the predictability of grade point average by 15.5% for Whites and 20.3% for Blacks; overall, these analyses accounted for 61% of the variance in grade point average for Whites and 47% for Blacks; (b) for retention, the comparable increment in predictability was 2.5% for Whites and less than 1% for Blacks; overall, the percentage of retention variance accounted for was 42% for Whites and 29% for Blacks; and (c) a paradoxical finding was the combination of a positive correlation between high school average and students' expected grades on tests and a negative correlation between expected and actual grades. The paradox is resolved by citing data that demonstrate (a) a disparity between high school grades and independently measured academic accomplishment; (b) the consequent false attributions students draw about their academic abilities; and (c) the impact of these false attributions on the priority students place on their academic responsibilities.
Physical activity has considerable health-enhancing potential. It will be realized, however, only if large number of people participate in adequate activity. This summary report describes the main results of four studies aimed to find out whether physically active commuting to work (PACW) meets the requirements of health and fitness enhancing activity. Three successive mail inquiries (N = 2014) indicated that PACW provided habitual exercise to one-third of employed urban population, and that more than one-fifth expressed willingness and being able to increase PACW. A randomized controlled trial on 68 inactive middle-aged men and women revealed that PACW (1 h daily for 10 wk) increased VO2max by 4.5% (P = 0.02), maximal treadmill time by 10.3% (P = 0.0007), and HDL cholesterol by 5% (P = 0.06). A demonstration project in a large industrial plant showed that PACW can be successfully promoted by low cost measures. In conclusion, these studies suggest that PACW may offer substantial potential as health and fitness enhancing measure provided that it can be practiced safely.
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