Propagation of ultrawideband short pulses of terahertz radiation through submillimeter-diameter circular waveguides.

We report experimental investigations in which quasi-optical methods were used to efficiently couple freely propagating, optoelectronically generated, subpicosecond pulses of terahertz (THz) radiation into submillimeter circular metal tubes (waveguides) and, consequently, to measure the transmitted pulses from these waveguides. We observe very dispersive low-loss propagation over the frequency band from 0.65 to 3.5 THz, with frequency-dependent group velocities nu(g) ranging from c/4 to c and phase velocities nu(p) from 4c to c , where nu(g)nu(p)=c(2) . The linearly polarized incoming THz pulses couple significantly only into the TE(11) , TM(11) , and TE(12) modes of the utilized 24- and 4-mm-long stainless-steel tubes, with inside diameters of 240 and 280microm , respectively.

Cultural effects: affects following ruminations on success and failure in sports.

Affect following ruminations of success and failure in sport was examined for cultural effects. 66 African-American and 84 Native West African athletes completed questionnaires following ruminations about their most successful athletic experience, and again following ruminations about their worst failure. Analysis suggested that affect following ruminations of successful experiences was more positive than those following failure. Cultural differences were noted in the affective responses following ruminations of success. African athletes tended to be more positive in general and self-related affect following ruminations of success and slightly more negative following ruminations of failure than American athletes.

Changes in scores on the profile of mood states following a single bout of physical activity: heart rate and changes in affect.

28 college age students participating in a weight lifting class exhibited significant decreases in negative affect and increases in positive affect. Changes in affect were correlated with average exercise heart rates. Higher heart rates were correlated with reductions in negative affect and increases in positive affect. Correlations of .37 and .40 suggest that, in accordance with earlier studies, exercise intensity may be indirectly related to exercise.

Athletic injury and self diminution.

A review of the literature examining the effects of athletic injury on persons have suggested a deleterious effect. Specifically, results indicated that following traumatic injury, athletes suffer a diminution of affect and feelings of self-worth. Because studies published in this area have been post-injury in design, the present study was fashioned to examine changes from baseline values in the self-concept of university varsity football players following a disabling injury. There were 29 athletes in the subject pool. Sixteen subjects were severely injured during the season. Measures were taken on the first day of fall practice and at the end of the season. Injured athletes were assessed each week while they were unable to participate in practice. Analysis revealed a significant decrease in generalized self-concept following athletic injury (p < 0.001) which persisted through the course of treatment. Suggestions for continued research and treatment are proffered.

Resistance exercise decreases beta-endorphin immunoreactivity.

Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To examine further the effects of resistance exercise on beta-EP immunoreactivity, 10 male and 10 female college-age students participated in a series of controlled isotonic resistance exercises. The session consisted of three sets of eight repetitions at 80% of one repetition maximum (1-RM) for each of the following exercises: (1) bench press; (2) lateral pull-downs; (3) seated arm curls; and (4) military press. Blood plasma was sampled both before and after the lifting routine and beta-endorphin levels were determined by radioimmunoassay. A Students t test for paired samples indicated that mean(s.e.) plasma beta-endorphin levels after exercise (10.5(1.3) pg beta-EP ml-1) were significantly decreased as compared with pre-exercise (control) levels (16.5(1.2), P < 0.05). While the mechanism(s) contributing to the decrease in immunoreactivity is unclear, it may be the result of the synergistic effect of beta-EP clearance during rest intervals and changes in psychological states between sampling.

Exercise dependence in relation to competitive orientation of runners.

An increasing number of runners seem to be vulnerable to the exercise dependence (ED) syndrome, a clinical disorder in which the athlete is unwilling to alter or discontinue training regimens despite medical contraindications to continued training compliance. As habituation to a stimulus has been regarded to be a diagnostic criterion of an addicted state, we hypothesized that performance in running events of increasing distances would be accompanied by an increased tendency towards ED. To examine this relationship, an exercise addiction scale was completed by recreational (non-competitive) runners (N = 33), five kilometer (5K) runners (N = 24), marathoners (N = 32), and ultramarathon (50 miles) runners (N = 61). ANOVA procedures indicated that both marathoners and ultramarathoners showed significantly higher ED scores [3.78 +/- 1.6 (SD) and 4.59 +/- 1.8, respectively] as compared to 5K (2.9 +/- 1.0) and recreational runners (2.16 +/- 1.3) (p < 0.05). In addition, ultramarathoners presented significantly higher ED scores than those of marathoners (p < 0.05). The data indicate that a tendency towards ED may motivate participation in competition of increasing distance and support a habituation effect consistent with acquired dependence behavior.

The effects of an acute bout of sleep on running economy and VO2 max.

Synchronized human sleep has been shown to decrease activation of the sympathetic nervous system, resulting in reduced levels of oxygen consumption. This is in direct conflict with sympathetic arousal, which coincides with the initiation of exercise. Although a considerable body of research has investigated the effects of sleep deprivation on exercise performance, the effects of an acute bout of sleep on exercise response have not been previously reported. This question appears relevant considering the occurrence of acute sleep bouts among athletes competing in prolonged multi-event competition (e.g. swimming, track and field). To investigate the effects of an acute bout of sleep on submaximal (running economy) and maximal oxygen consumption, seven male volunteers participated in a continuous, progressive treadmill test to volitional exhaustion immediately following a 1-h bout of sleep (SB) or no sleep (Control). The subjects served as their own controls and the order of trials was randomized. A MANOVA with repeated measures indicated no difference between groups for running economy or VO2 (P < 0.05). However, a significant interaction effect was observed in which SB resulted in greater running economy (lower VO2) through the first two stages of the protocol, while the control treatment yielded a greater economy throughout the remaining stages. While the implications of the findings are uncertain, they may indicate differences in psychological arousal or anxiety as a result of treatments or the possibility of a delayed sympathetic arousal in the early stages of exercise following sleep.

Beta-endorphins and mood states during resistance exercise.

Research examining the relationship between beta-endorphin immunoreactivity and affect has resulted in equivocal findings. To examine this relationship further, 10 male and 10 female college-age students participated in a controlled free-weight exercise session. Blood plasma samples were procured both prior to and following the exercise bout and beta-endorphin levels were determined by immunoassay. Analysis indicated that plasma beta-endorphin levels following exercise were significantly decreased from pre-exercise levels. Pearson correlations showed no significant relationship between pre- or postexercise plasma beta-endorphins and either total mood disturbance or Profile of Mood States subscores. The data support previous failure of resistance exercise to produce an increase in beta-endorphin immunoreactivity as well as the lack of a significant relationship between affect and the beta-endorphin response to exercise.

Scores on exercise dependence among dancers.

A number of researchers have suggested that the syndrome of exercise dependence (addiction) is paralleled by a tendency towards eating disorders such as anorexia nervosa and bulimia. As considerable research has reported a high incidence of eating disorders among dancers and as rigorous physical demands are inherent in dance, we hypothesized that dancers would present a higher profile of exercise dependence on the Negative Addiction Scale than other athletes. To test this hypothesis, 47 female ballet and modern dancers completed a survey on exercise dependence adapted from Hailey and Bailey (1982) to assess quantitatively exercise dependence. Scores were compared with those obtained from 39 female endurance (running) athletes and 16 female nonendurance (field hockey) athletes. Significantly higher scores on dependence for dancers than for endurance or nonendurance athletes were noted. The data indicate that dancers may be at greater risk for psychophysiological problems associated with exercise dependence than other athletes and so should be monitored for symptoms.

Hyperbaric oxygen: value in management of nonhealing saphenectomy wounds.

The greater saphenous vein is commonly used as a conduit for arterial bypass in both cardiac and peripheral vascular operations. Although saphenectomy wound complications occur infrequently, such problems may be quite serious. We report a case in which hyperbaric oxygen therapy was extremely valuable in the management of a very difficult saphenectomy wound.

Donor cardiectomy for other transplantation centers.

Inadequate supply of donor hearts is the greatest limitation to wider utilization of heart transplantation. We performed donor cardiectomy for other transplantation centers in three cases. The donor heart functioned well in all cases, and the recipients were all discharged. Donor cardiectomy for other transplantation centers allows utilization of hearts that might otherwise be lost for transplantation.

Metabolic demands and perceived exertion during cardiopulmonary resuscitation.

Emergency situations often require continuous execution of one-person cardiopulmonary resuscitation (CPR) for periods of time in excess of 30 minutes. The limited research which has examined the demands of the procedure has focused on central physiological measures, despite (1) the use of a subjective end-point for termination of CPR (i.e., exhaustion) as stated in professional guidelines, and (2) significant peripheral involvement in the form of muscular exertion, a phenomenon more closely linked to Ratings of Perceived Exertion (RPE) than to central factors. To examine subjective responses to performing CPR, 8 healthy, sedentary subjects [M age = 20.8 (yr) +/- .4; weight (kg) 82.6 +/- 7.1; height (cm) 183.7 +/- 2.8] reported differentiated Ratings of Perceived Exertion (RPE) following 10 minutes of one-person CPR testing. While metabolic data observed during CPR support previous research suggesting that the energy demands of performing CPR are relatively low, both peripheral and over-all RPE were significantly higher than central (respiratory-metabolic) RPE. Over-all RPE was also significantly greater than peripheral RPE. The data suggest research investigating CPR demands based on central measures may underestimate actual as well as perceived demands of performing the procedure. In addition, the considerable interindividual variability in the relative energy cost (% VO2 max) of performing one-person CPR suggests that the fitness level of the individual may be a limiting factor in the ability to perform CPR for extended periods of time.

Trust and adolescent sports: starters vs nonstarters.

Confirming earlier research, starters in basketball were found to be less trusting than nonstarters among junior high school boys (n = 12) and girls (n = 18). Researchers should explore the etiology of these differences.

Mood alterations with a single bout of physical activity.

Although numerous studies have examined the relationship among affect, personality, and physical activity, results are equivocal. Critics have cited inadequate experimental designs and analyses as the bases for ambiguity. This study addressed two identified weaknesses, length of exercise regimen and improper selection of subjects. Subjects were 72 college-age students who participated in one of three 75-min. activity classes (running, karate, weight lifting) and a lecture class (control subjects). The Profile of Mood States Test was administered prior to and immediately after exercise bouts. Analyses of variance and multiple t tests indicated that participating in a single bout of exercise significantly reduced reported total mood disturbance, tension, depression, anger, and confusion.