Biomedical subjects
Publications and source records attributed to J C Spence.
A method is given to invert the multiple scattering of electrons in a crystalline slab to obtain the projected potential. For a fixed orientation of the incident beam of electrons, scattering data are required for two thicknesses of the crystal.
A new diffraction-channeling effect has been discovered, in which Kikuchi or channeling line patterns formed by high energy electrons, neutrons, and positrons are shown to break up into a series of annular disks if the crystal thickness traversed by the beam is small. The disks may be interpreted as Gabor in-line holograms of strings of atoms projected along the beam path. For electrons or positrons the patterns may be detected with little background by detecting characteristic x-ray emission from a thin film as a function of the diffraction conditions of a collimated, ionizing, high energy beam. Uses of the effect for structure determination and atomic-resolution lensless imaging are suggested.
The purpose of the present study was to examine the effects of exercise intensity on feeling states following two acute bouts of exercise (i.e., 50% and 80% of age-predicted maximal heart rate reserve: HRR) in highly fit and unfit females. It was hypothesized that highly fit females would have increased positive well-being and/or reduced psychological distress post-exercise (high intensity) compared to unfit females while both groups would experience similar feeling states following moderate intensity exercise. Twelve highly fit and 12 unfit females completed 3 conditions: attention control and fitness test, and two acute bouts of exercise (30 minutes on a bicycle ergometer) at 50% and 80% age-predicted HRR. Pre- and post-exercise feeling states were measured via the Subjective Experiences Exercise Scale (McAuley & Courneya, 1994). Analyses indicated a time x condition x fitness interaction F(2,21)=6.07, p<.01 (eta2 =.37) for psychological distress. Follow-up univariate analyses revealed no change in the 50% or control conditions, however, psychological distress significantly increased for the unfit participants F(1,11)=4.68,p<.05 (eta2 =.29) while there was no change for the highly fit participants F(1,11)=2.14,p>.05 (eta2 =.16) in the 80% intensity condition. No fitness differences emerged with respect to positive well-being or fatigue. Therefore, the present study's results substantiate the need to consider fitness level in dose-response studies, particularly ones which examine negative feeling states.
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INTRODUCTION: Women's ice hockey is a rapidly growing sport, however little is known about the injuries sustained by this group of athletes. PURPOSE: The objective of this research was to identify risk factors associated with injury among female recreational ice hockey players. METHODS: This prospective study followed players from two women's ice hockey leagues in Edmonton, Canada during the 1997-98 hockey season. The occurrence of injuries was monitored during the season through standardized telephone follow-up. Risk factors were determined using multiple logistic regression. RESULTS: The initial study sample consisted of 314 players, however as the season progressed 19 (6%) were lost to follow-up. The results of the study are based on 295 (94%) participants. A total of 125 injuries were reported; the injury rate was 7.5 injuries/1,000 player-exposures. Risk factors found to be significantly related to the occurrence of injury were: injury in the past year (OR= 1.57), more than 5 years of hockey experience (OR=1.49), and high exposure level (OR=1.41). CONCLUSION: This research is the first to quantify personal risk factors associated with injury among female recreational ice hockey players. A sports injury in the previous 12 months appears to be highly associated with injury and further research is required to more fully understand this relationship. The importance of controlling for level of exposure when investigating risk factors for sports injury was demonstrated.
The purpose of this study was to investigate the efficacy of the theory of planned behavior in predicting physical activity intention in a nationwide sample of Canadian children and youth. The study sample consisted of participants from Grades 3, 5, 8, and 11 from schools across Canada. School participation was determined by means of a randomly stratified sample design. Results show that the direct measures of the theory of planned behavior explained 47% of the variability in the measure of physical activity intention. In addition, notable differences in the relative contributions of the predictor variables of attitude, subjective norm, and perceived behavioral control were found across grade and grade-by-gender subgroups. The present study provides evidence that in a population of children and youth the determinants display a pattern of change developmentally.
INTRODUCTION: Participation in ice hockey by women is increasing in many parts of North America; however, research into injuries and the patterns of injury among female players associated with this activity is limited. PURPOSE: The purpose of this research was to examine the incidence and nature of injuries suffered by female recreational ice hockey players. METHODS: This prospective study followed 314 female players from 33 teams in Edmonton, Canada, during the 1997-1998 hockey season. Injury and game attendance data were collected using monthly telephone interviews throughout the season. Diagnostic information for individuals who received medical treatment was solicited from the attending health professional. RESULTS: A total of 102 players reported a total of 125 injuries for a rate 7.5 injuries/1000 player exposures. The anatomic region most often injured was the lower extremity (31.2%), and the most common diagnosis was sprain/strain (52.0%). The predominant injury mechanism was player contact, either as a result of collision with another player or a body check (40.0%). Of all injuries, 65.6% occurred during league games, 27.2% during play-off, tournament, or exhibition games, and 7.2% during practices. Although less than 1% of injuries resulted in hospitalization, 17.6% of injuries resulted in an absence from hockey of 8 or more days. CONCLUSION: The diagnostic and anatomic distribution of injury in the women's hockey league was similar to that in leagues where full facial protection is mandatory. The observed injury rate was lower than the rates reported for male recreational and collegiate ice hockey players. Female recreational ice hockey players are at risk for injuries and further research is required to identify areas for injury prevention.
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To gauge the extent of drug and alcohol use in Canadian university athletes, we estimated the proportion of Canadian university athletes using social and/or ergogenic drugs through survey methods. A secondary purpose was to examine athletes' perceptions of the value of drug testing and drug education programs. Using a stratified random sampling procedure, 754 student athletes were surveyed in eight different sports from eight universities across Canada. Results showed that 17.7 percent of athletes have used major pain medications over the past twelve months, 3 percent reported use of weight loss products, 0.9 percent reported anabolic steroid use, 16.6 percent reported use of smokeless tobacco products, 94.1 percent reported use of alcohol, 65.2 percent reported use of caffeine products, 0.7 percent reported use of amphetamines, 1.0 percent reported use of barbiturates, 19.8 percent reported use of marijuana or hashish, 5.9 percent reported use of psychedelics and 0.8 percent reported use of cocaine/crack.
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The FORTRAN source code is given for a computer program that calculates the two-dimensional intensity distribution in convergent-beam transmission electron microdiffraction (CBED) patterns from perfect crystals. The program uses the eigenvalue or Bloch-wave method. It allows three-dimensional dynamical diffraction, and so includes all higher-order Laue zone effects without approximation. No symmetry reduction is included. The program accepts noncentrosymmetric or centrosymmetric crystal structures and allows absorption corrections to be included. It uses the "EISPACK" subroutines for the diagonalisation of a general complex matrix. Up to 100 CBED disks may be included. The code is also available via "Bitnet."
We show that high-resolution transmission electron microscopy can be used directly to reveal the structure of the metal framework and its defects in Ba2YCu3O7. The use of dynamical effects under carefully selected and controlled conditions allows the detection of long-range order in the disposition of the oxygen vacancies, but inevitable misalignments make the quantification of the order parameter difficult. Specimen preparation methods are compared, and a wide-angle convergent-beam pattern is demonstrated.
It is postulated that endothelial (and possibly other) cells are arranged in monoclonal zones, each of which occupies an accurately predetermined site in the cardiovascular system. The clones impose detailed developmental patterns on the vascular tree itself and provide positional information relevant to the morphogenesis of surrounding tissues--for example, clones in the dermis regulate the behaviour of epidermal melanocytes.
Several variants of generalised vitiligo can be recognised by their cutaneous distribution. In some, certain anatomical regions--e.g., hands--are predominantly affected while the cutaneous depigmentation in other variants shows a similar anatomical distribution to that of the internal structures affected in some of the autoimmune and rheumatic diseases. Five patients have been seen, and three described by others, with vitiligo affecting skin of eyelids and lower front of neck, reminiscent of the anatomical distribution of lesions in thyrotoxicosis with exophthalmos: two of these patients have thyrotoxicosis. Another variant of vitiligo mimicks the anatomical distribution of lesions in ankylosing spondylitis, Reiter's syndrome, and ulcerative colitis and there are cases simulating lupus erythematosus, rheumatoid arthritis, and psoriasis. It is suggested that the parts of the body affected in each vitiligo variant and its corresponding internal disease constitute a set os mosiac patches with distinctive shared characters. These may have morphogenetic functions during embryonic development and be potentially autoantigenic later in life.
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The 1996 Alberta Sport and Recreation Injury Survey is a retrospective study describing the annual incidence of injuries in the province of Alberta resulting from sport and recreational involvement. Data was collected by means of a telephone survey using random digit dialing techniques to obtain a representative sample of Albertans in the winter of 1995-96. The sample produced a total of 3,790 respondents from 1,478 households evenly split between genders, with an age range of 6 to 93 years. The survey asked information regarding medically attended, non-fatal injuries resulting from sport and recreational activities. Findings reveal an annual incidence of sport or recreational injuries of 11%. Among those reporting a sport or recreational injury, the most common types of injuries were a sprained/torn ligament (31%), strained/pulled muscle (19%), and fracture (13%). The most common bodily locations of injuries were the knees (21%) and the ankle (14%).
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