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31.
Development of anti-G suits and their limitations   总被引:1,自引:0,他引:1  
Initial anti-G suits were based on the belief that decreased venous return was the critical effect of increased weight of blood during acceleration. Cumbersome water filled, pneumatic gradient or pulsatile pressure suits resulted. Subsequent centrifuge studies implicated arterial pressure, rather than venous return, as the major determinant of G tolerance in the sitting position. Consequently, methods of increasing arterial pressure were developed. Findings that the hypertensive, associated anti-blackout and discomfort effects of suit inflation all increase with bladder system pressure up to arterial occlusive levels resulted in the simplified G-suit used in W.W.II to the present. Recent +Gz loss of consciousness crashes indicate current straining maneuvers plus this suit are inadequate. Furthermore, because of very high pressures to maintain cerebral circulation in the sitting position, very high G suit protection is hazardous. If piloting is essential for full use of super performance fighters, the prone position with counter-weighted head support plus omni-directional surveilance is the surest strategem to obtain this advantage.  相似文献   
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This paper models the proximate determinants of school attendance and scores on cognitive and educational achievement tests and on school examinations of over 600 schoolchildren from the Control group of a randomized trial in Tanzania, where children in the Intervention group heavily infected with hookworm and schistosomiasis received treatment. The modeling approach used a random effects framework and incorporated the inter-relationships between school attendance and performance on various tests, controlling for children's health status, socioeconomic variables, grade level, and the educational infrastructure. The empirical results showed the importance of variables such as children's height and hemoglobin concentration for the scores, especially on educational achievement tests that are easy to implement in developing countries. Also, teacher experience and work assignments were significant predictors of the scores on educational achievement tests, and there was some evidence of multiplicative effects of children's heights and work assignments on the test scores. Lastly, some comparisons were made for changes in test scores of treated children in the Intervention group with the untreated children in the Control group.  相似文献   
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The authors report a new case of abdominal pregnancy with living baby. The analysis of this observation permits to present then the clinical and paraclinical characteristics of this exceptional localization of pregnancy and emphasize the surgical principles involved with its treatment, around the time of the term delivery.  相似文献   
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Irritability is often a problem for patients with Post-Traumatic Stress Disorder (PTSD). We describe two cases that illustrate the use of lithium in the treatment of veterans with PTSD who complained of serious problems with irritability or angry outbursts. These cases are discussed in the context of evidence that lithium may be useful in other patients with disorders of impulse control. The evidence linking disorders of anger and impulse control to a dysregulation in neurotransmitter regulation, particularly in serotonergic pathways, supports a psychopharmacologic approach to treatment. These findings should lead to further study of the role of lithium in the treatment of this symptom complex in patients with PTSD.  相似文献   
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