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Biomedical subjects

J C Spence

Publications and source records attributed to J C Spence.

At least 19 recordsLinked to original sources
PubMed2005

Social ecological correlates of physical activity in normal weight, overweight, and obese individuals.

OBJECTIVE: Research is limited concerning the moderating influence of weight status (ie normal, over, and obese) on the social ecological correlates of physical activity (PA) in adults. Therefore, the present study attempted to shed light on this issue. DESIGN: In 2001, a national cross-sectional mail out panel survey was conducted over a 3-month period in the United States. SUBJECTS: There were 1867 normal weight (ie body mass index (BMI)=20-24.99 kg/m2), 2145 overweight (ie BMI=25-29.99 kg/m2), and 1902 obese (ie BMI>30 kg/m2) adults. MEASURES: Various demographic measurements were taken in addition to social support (SS), self-efficacy (SE), access to facilities, and PA. RESULTS: Normal weight individuals engaged in significantly more PA than overweight individuals, who in turn engaged in significantly more PA than obese individuals F(2,5991)=55.51, P<0.01. Further regression analyses showed that higher SE, SS, the access to facilities in a neighborhood, and various interactions among these constructs were significantly and positively associated with PA. Interestingly, the strength of these relationships varied depending on weight status. CONCLUSION: Weight status needs to be taken into consideration when examining social ecological correlates of PA.

Adult↗
PubMed2002

The epidemiology of medically attended sport and recreational injuries in Queensland.

The Queensland Sport and Recreation Injury Survey (QSRIS) is a retrospective study describing the annual incidence of injuries in the state of Queensland, Australia, resulting from sport and recreational activity involvement. Data were collected by means of a computer-assisted-telephone-interview (CATI) survey of a representative sample of Queenslanders in the spring of 2000. The sample produced a total of 1337 respondents aged 18 to 94 years. The survey asked information regarding medically attended, non-fatal injuries resulting from sport and recreational activities in the past 12 months. Of the 1337 individuals surveyed, 191 of the respondents reported one or more injuries that required medical attention resulting in a total of 222 Injuries. This represents an overall rate of 1,666 medically attended injuries per 10,000 people. Among those reporting a sport or recreational injury, the most common types of injuries were a strained/pulled muscle (30.9%), sprained/torn ligament (24.1%), and fracture (12.6%). The most common bodily locations of injuries were the shoulders (13.0%) and knees (12.5%). Results detail the nature and type of injury, medical professional attending to the injury and the nature of the sport or recreational activity that led to the reported injury, highlighting the number of injuries associated with general fitness activities achieved through high participation rates and low injury rates. This remains an area of much needed attention given the promotional push towards raising the levels of physical activity at a population level.

Adolescent↗
PubMed2001

Atomic string holography.

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.

Journal Article↗
PubMed2001

Image reconstruction from electron and X-ray diffraction patterns using iterative algorithms: experiment and simulation.

The hybrid input-output iterative algorithm, which solves the phase problem for scattering from non-periodic objects, is reviewed for application to X-ray and electron diffraction data. Desirable convex constraints, including the sign of the scattering potential for electrons, and compact support, are discussed. The cases of complex and real exit-face wavefunctions, strong and weak phase objects, various supports, and the use of coherent focussed radiation are reviewed. Reconstruction of general complex objects requires accurate knowledge of the support, which should consist of two holes or a triangle in an opaque mask. The support boundaries should be as sharp as possible. Strong phase objects without absorption can be recovered if the support consists of one hole, is accurately known and has sufficiently sharp boundaries. Real and weak phase objects with absorption can be recovered without accurate knowledge of the support area if the support boundaries are sufficiently sharp and the support consists of one or more holes. A sign constraint on the scattering potential is used to recover weak phase objects. The experimental realization of theoretically desirable support conditions is discussed. A two-stage method of finding the support for complex objects is proposed. Experimental results from applying the Gerchberg-Saxton-Fienup HiO-algorithm to coherent electron diffraction patterns are presented, using specially made e-beam lithographed support structures. Images with a resolution of about 5 nm are thus recovered from the intensities alone in coherent electron diffraction patterns from non-periodic objects. Limitations of the present experiments are identified and suggestions made for development of both X-ray and electron work.

Journal Article↗
PubMed2001

Feeling state responses to acute exercise of high and low intensity.

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.

Adult↗
PubMed2000

Personal risk factors associated with injury among female recreational ice hockey players.

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.

Adolescent↗
PubMed2000

Understanding physical activity intention in Canadian school children and youth: an application of the theory of planned behavior.

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.

Adolescent↗
PubMed2000

Epidemiology of women's recreational ice hockey injuries.

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.

Adolescent↗
PubMed1996

Drug and alcohol use by Canadian university athletes: a national survey.

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.

Adult↗
PubMed1989

FORTRAN source listing for simulating three-dimensional convergent beam patterns with absorption by the Bloch wave method.

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."

Electron Probe Microanalysis↗
PubMed1988

Structural characterization of Ba2YCu3O7 by high resolution transmission electron microscopy.

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.

Barium↗
PubMed1980

Do vascular clones determine developmental patterns?

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.

Cardiovascular System↗
PubMed1979

Vitiligo patterns simulating autoimmune and rheumatic diseases.

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.

Adolescent↗