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Balldin UI O'Connor RR Werchan PM Isdahl WM Demitry PF Stork RL Morgan TR 《Aviation, space, and environmental medicine》2002,73(5):456-459
BACKGROUND: Aircrew have reported increased heat stress when wearing the USAF Combined Advanced Technology Enhanced Design G-Ensemble or COMBAT EDGE (CE). The perceived thermal burden has been attributed to the fact that CE includes an inflatable counter-pressure vest to ease the work of positive pressure breathing during G (PBG). This study compared the heat load of CE with that of the standard USAF anti-G system (STD) without the vest, and measured heat stress effects on G-tolerance in both suits. METHODS: This study had 12 subjects (6 of them aircrew) who participated. Simulated preflight thermal stress (20 min walking at 35 degrees C with 85% relative humidity and radiant heat) was followed by return to a cooler environment (21 degrees C). G-tolerance and subjective stress levels were determined on the human centrifuge before and after the heat stress. Body weight, rectal and skin temperatures, and blood parameters were also assessed. RESULTS: Baseline relaxed tolerance for +Gz gradual onset runs (GORs) were (mean +/- SD) 7.6 +/- 1.3 G for CE and 7.1 +/- 0.8 G for STD (p < 0.05). Maximal rectal temperature following heat stress peaked at 38.1 +/- 0.4 degrees C for both CE and STD, and mean nude weight loss was 1.10 +/- 0.24 kg for both. Relaxed GOR tolerances after heat stress were 7.1 +/- 1.3 for CE and 6.3 +/- 0.9 for STD (p < 0.01). The heat stress significantly reduced G tolerance for both CE and STD (p < 0.01). CONCLUSIONS: Simulated preflight activity in hot conditions revealed no significant difference between CE and STD with regard to maximal core and skin temperature elevations or dehydration levels. CE supported a significantly higher baseline relaxed G-tolerance than STD, an advantage that persisted after heat stress and dehydration. 相似文献
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Brief exposure to -Gz reduces cerebral perfusion pressure during subsequent +Gz stress in rats 总被引:4,自引:0,他引:4
Sheriff DD Isdahl WM Nelson CD Werchan PM 《Aviation, space, and environmental medicine》2001,72(1):8-12
INTRODUCTION: In humans, +Gz exposure immediately preceded by exposure to zero or -Gz can result in unexpected incapacitation ("push-pull" effect). Our goals were to establish whether this phenomenon exists in rats and to evaluate the importance of varying the duration of -Gz exposure on magnitude of the push-pull effect on cerebral perfusion pressure. METHODS: Eight conscious male rats were studied in the transition from +5 Gz to +10 Gz imposed by centrifugation. This was done with (push-pull) or without (control) 2 s exposure to -5 Gz applied using a counterbalanced design. Seven isoflurane anesthetized rats were studied in the transition from 0Gz (+1Gy) to + 1Gz imposed by tilting. This was done with (push-pull) or without (control) 0.5, 1, 3, or 9 s exposure to -1Gz imposed immediately prior to the transition applied using a counterbalanced designed. RESULTS: Exposure to 2 s of -5 Gz significantly (p < 0.01) reduced carotid artery pressure in the 4th through 8th s of exposure to +10 Gz by an average of 15 mmHg compared with control. In the tilt experiments, a push-pull effect was found with mild Gz exposure (+/-1Gz) with as little as 0.5 s -Gz exposure. Varying the head-down dwell time did not alter the magnitude of the exaggerated hypotension induced by "push-pull" (p = 0.90). CONCLUSIONS: We conclude that rats express a "push-pull" effect similar to that observed in humans but that altering the duration of exposure to -Gz does not influence the magnitude of the "push-pull" effect. 相似文献
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A dissolution model was developed especially for the study of Intraoralia containing Gelatin and used to determine the dissolution behaviour of disc-shaped pieces of Gelatin of different composition (addition of a plasticizer and Formaldehyde) by means of the electrical conductance. 相似文献
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Oliver Pfaar Kostas Karatzas Katharina Bastl Uwe Berger Jeroen Buters Ulf Darsow Pascal Demoly Stephen R. Durham Carmen Galán Regula Gehrig Roy Gerth van Wijk Lars Jacobsen Nikos Katsifarakis Ludger Klimek Annika Saarto Mikhail Sofiev Michel Thibaudon Barbora Werchan Karl-Christian Bergmann 《Allergy》2020,75(5):1099-1106
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Hendrix Cassandra L. Werchan Denise Lenniger Carly Ablow Jennifer C. Amstadter Ananda B. Austin Autumn Babineau Vanessa Bogat G. Anne Cioffredi Leigh-Anne Conradt Elisabeth Crowell Sheila E. Dumitriu Dani Elliott Amy J. Fifer William Firestein Morgan Gao Wei Gotlib Ian Graham Alice Gregory Kimberly D. Gustafsson Hanna Havens Kathryn L. Hockett Christine Howell Brittany R. Humphreys Kathryn L. Jallo Nancy King Lucy S. Kinser Patricia A. Levendosky Alytia A. Lonstein Joseph S. Lucchini Maristella Marcus Rachel Monk Catherine Moyer Sara Muzik Maria Nuttall Amy K. Potter Alexandra S. Rogers Cynthia Salisbury Amy Shuffrey Lauren C. Smith Beth A. Smyser Christopher D. Smith Lynne Sullivan Elinor Zhou Judy Brito Natalie H. Thomason Moriah E. 《Archives of women's mental health》2022,25(5):943-956
Archives of Women's Mental Health - Our primary objective was to document COVID-19 induced changes to perinatal care across the USA and examine the implication of these changes for maternal... 相似文献
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The therapy of denture sore mouth which is induced by Candida albicans must take its bearings about the general and local disposition factors. The crucial points of stomatological treatment are pointed to. The problems related to local antimycotic therapy in the oral cavity are discussed. A new antimycotic dosage form, the nystatin-gelatin foil, for local application in denture wearers in presented. Its dosage and its use are described. 相似文献
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J W Burns P M Werchan J W Fanton A B Dollins 《Aviation, space, and environmental medicine》1991,62(7):615-617
Seven male baboons (average weight, 20.6 kg) were trained in a simple shock-avoidance performance task on the USAFSAM centrifuge. A red light was presented to the baboon at approximate 2-s intervals. The animal was allowed 1 s to turn off the light or receive a 1-s shock. The shock could be abbreviated by a late trigger pull. Thus, the animal could avoid, escape, or accept the full shock. EEG was monitored from three transcranial stainless steel electrodes. Loss of consciousness (LOC) was induced by a rapid onset (4 or 6/s) exposure to 8 +Gz and sustained until LOC was identified by a near isoelectric EEG signal. Performance recovery time was measured from the return of EEG activity to the time when the animal resumed the performance task. These data were compared with previously obtained human data and found to be very similar. Also, it was found that time of performance recovery became significantly shorter after multiple LOC exposures and the performance recovery time significantly increased with increased time of unconsciousness. This study demonstrates the utility of the baboon as an animal model for G-induced LOC (G-LOC) research. 相似文献