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  • 1
    Electronic Resource
    Electronic Resource
    High power radiation from ionization fronts in a static electric field in a waveguide (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 1115-1123 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The radiation produced when a relativistically moving plasma/gas boundary (i.e., an ionization front) passes between alternatively biased capacitor electrodes is studied. Results of an experiment based on a design which incorporates the capacitor electrodes into an X band waveguide are presented. The waveguided design effectively couples nearly three orders of magnitude more power into the output than the previously unguided designs. Linear theory is extended to include the depletion of the laser energy as it propagates through the ionizable gas (i.e., laser depletion), and the effect of finite output pulse duration. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1377608
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  • 2
    Electronic Resource
    Electronic Resource
    A treadmill test of sprint running (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of medicine & science in sports 6 (1996), S. 0 
    Details
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: Anaerobic power is characterized by a high degree of specificity regarding both the recruited muscles as well as the recruitment pattern. The popular Wingate Anaerobic Test (WAnT) is a cycling test that does not satisfy the need for a running-specific anaerobic test. We describe such a test, using a novel type of a commercially available treadmill (BRL 1800, Gymrol, France). The ergometer is equipped with a torque motor to neutralize the frictional resistance of the treadmill belt, and a hip-belt harness connected to a horizontal rod. Force applied to the harness is monitored by a strain gauge mounted on the rod, while vertical movement is monitored by a potentiometer at the posterior fixed end of the rod. These, in conjunction with the treadmill belt speed, enable the computation of horizontal and vertical power as well as the combined total output. Power is calculated both as ‘peak’ power (highest 2.5 s segment) and ‘mean’ power (20 s duration). Preliminary results of young athletes were generally consistent with the expected age-related changes in anaerobic power. Values obtained on the anaerobic treadmill were always higher than the corresponding WAnT values previously obtained in comparable age groups. The higher values were probably due to the larger muscle mass involved and the shorter peak and mean power durations (2.5 and 20 s versus 5 and 30 s in the WAnT, respectively). This test should enable not only running-specific anaerobic power monitoring but also the characterization of the relationship between the horizontal and vertical components of that power.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0838.1996.tb00468.x
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  • 3
    Electronic Resource
    Electronic Resource
    Cervical spine injury in the very elderly (2000)
    Springer
    Emergency radiology 7 (2000), S. 287-291 
    Details
    ISSN: 1438-1435
    Keywords: Key words Cervical spine – Radiography – Injury – Elderly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: Elderly patients are known to be at increased risk of cervical spine injuries. This propensity for injury becomes more important as the population of mobile elderly individuals increases. The present study seeks to examine the incidence and spectrum of spine injury among patients aged 80 years or greater, and to examine the efficacy of a decision rule for obtaining cervical spine radiography in this extreme age group. The decision rule would determine whether imaging could be avoided in patients who have none of the following: (1) posterior midline cervical spine tenderness; (2) focal neurological deficit; (3) abnormal level of alertness; (4) evidence of intoxication; or (5) clinically apparent distracting painful injury. Methods: All blunt trauma victims presenting to participating emergency departments underwent clinical evaluation prior to radiographic imaging. The elements of the decision rule were assessed and documented in each patient prior to radiographic imaging. The presence or absence of cervical spine injury was subsequently based on the final interpretation of all radiographic studies supplemented by a review of neurosurgical and risk management logs from each participating hospital. Data on all patients aged 80 years or greater were sequestered from the main database for separate analysis. Results: The study enrolled 34,069 individuals, including 818 patients (2.4 %) with cervical spine injuries. This population contained 1,070 patients (3.1 % of all cases) aged 80 or greater, 50 of whom (4.7 %) sustained cervical spine injuries. Injuries to the craniocervical junction (particularly C2 and the odontoid) accounted for 47.3 % of the injuries in the elderly, but only 28.6 % of injuries in younger patients. Older fracture victims were also likely to have more injuries (2.54 injuries/patient) than their younger counter parts (1.78 injuries/patient). The decision rule correctly identified all very elderly cervical spine injury victims [sensitivity 100.0 %; confidence interval (CI) 92.9–100.0 %], and designated 132 patients as “low-risk,” yielding a negative predictive value of 100.0 % (CI 97.3–100.0 %). Conclusions: The very elderly are at increased risked of cervical spine injury, particularly injury to the craniocervical junction. They also tend to have more extensive injuries than younger patients. Despite the increased risk of injury, the decision rule performed well in the very elderly, and allowed correct identification of all cervical spine injury victims.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00011843
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of environmental temperature on testosterone and cortisol responses to high Intensity, intermittent exercise in humans (1996)
    Springer
    European journal of applied physiology 75 (1996), S. 83-87 
    Details
    ISSN: 1439-6327
    Keywords: Key words Anaerobic exercise  ;  Exercise recovery  ;  Hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to examine the testosterone, cortisol, and the molar ratio of testosterone to cortisol (T:C) blood concentration responses to intermittent, high intensity exercise in the heat. Eight active men [mean age 25 (SD 3) years, mass 71.1 (SD 5.5) kg, height 175.9 (SD 4.4) cm] performed two series of five 15-s Wingate anaerobic power tests in both hot (H, 35°C) and thermoneutral (TN, 22°C) environments. Each period of exercise was separated by 30-s of active recovery. Each series was separated by 60 min of passive recovery. Blood samples were obtained before (PRE), immediately post (IP), and 5(5R), 10(10R), 15(15R), 30(30R), 45(45R), and 60(60R) min following exercise. Peak power was significantly higher, during the first series of exercise, in the H compared to TN. No significant differences were seen in any of the variables between the first and second series of exercise in either environmental condition. Furthermore, no significant differences between these conditions were observed in heart rate, blood lactic acid concentration, or rectal temperature. A significant decrease in cortisol concentration was observed between PRE and IP, during both conditions. However, no significant interactions between TN or H were seen. No change from PRE was observed in testosterone or T:C during either TN or H. It would appear that testosterone and cortisol respond similarly to repeated periods of short duration high intensity exercise, in either thermoneutral or moderately hot environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050130
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of hydration state on plasma testosterone, cortisol and catecholamine concentrations before and during mild exercise at elevated temperature (1994)
    Springer
    European journal of applied physiology 69 (1994), S. 294-300 
    Details
    ISSN: 1439-6327
    Keywords: Dehydration ; Fluid intake ; Testosterone ; Cortisol ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This investigation examined the influence of pre-exercise hydration status, and water intake during low intensity exercise (5.6 km · h−1 at 5% gradient) in the heat (33° C), on plasma testosterone (TEST), cortisol (CORT), adrenaline (A), and noradrenaline (NA) concentrations at baseline (BL), pre-exercise (PRE), and immediately (IP), 24 h (24 P), and 48 h postexercise (48 P). Ten active men participated in four experimental treatments. These treatments differed in preexercise hydration status [euhydrated or hypohydrated (HY, −3.8 (SD 0.7)% body mass)] and water intake during exercise (water ad libitum or no water intake during exercise, NW). There were no significant changes in TEST, CORT, or A concentrations with time (BL, PRE, IP, 24 P, and 48 P), or among treatments. However, significant increases from BL and PRE plasma NA concentrations were observed at IP during all four treatment conditions. In addition, HY + NW resulted in significantly higher plasma NA concentrations at IP compared to all other treatments. These results suggest that moderate levels of hypohydration during prolonged, low intensity exercise in the heat do not influence plasma TEST, CORT, or A concentrations. However, plasma NA appears to respond in a sensitive manner to these hydration and exercise stresses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00392033
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