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Counselors with higher levels of perceived occupational stress report significantly greater personal strain and less coping resources than do counselors perceiving lower levels of occupational stress.  相似文献   
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It has previously been shown that the metabolic acidaemia induced by a continuous warm-up at the 'lactate threshold' is associated with a reduced accumulated oxygen deficit and decreased supramaximal performance. The aim of this study was to determine if an intermittent, high-intensity warm-up could increase oxygen uptake (V02) without reducing the accumulated oxygen deficit, and thus improve supramaximal performance. Seven male 500 m kayak paddlers, who had represented their state, volunteered for this study. Each performed a graded exercise test to determine V02max and threshold parameters. On subsequent days and in a random, counterbalanced order, the participants then performed a continuous or intermittent, high-intensity warm-up followed by a 2 min, all-out kayak ergometer test. The continuous warm-up consisted of 15 min of exercise at approximately 65% V02max. The intermittent, high-intensity warm-up was similar, except that the last 5 min was replaced with five 10 s sprints at 200% V02max, separated by 50 s of recovery at ~55% V02max. Significantly greater (P<0.05) peak power (intermittent vs continuous: 629 ± 199 vs 601 ± 204W) and average power (intermittent vs continuous: 328±39.0 vs 321 ±42.4 W) were recorded after the intermittent warm-up. There was no significant difference between conditions for peak V02, total V02 or the accumulated oxygen deficit. The results of this study indicate that 2 min all-out kayak ergometer performance is significantly better after an intermittent rather than a continuous warm-up.  相似文献   
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We are heading into an era of uncontrolled and uncontrollable information flow. In the past, the tools of information flow required large investments, and the persons controlling them were easily identifiable. Now, effective long-range communication with large numbers of people can be done using tools that are easily affordable to the average citizen. Moreover, it can be done in ways that make monitoring and control virtually impossible. This is not a worrisome future change that can be averted by prompt action; it is a fait accompli and there is no reversing it. However, this is not necessarily clear to those interested in monitoring and control. Unfortunately, the bulk of electronic communication is still relatively exposed to monitoring and control, and is likely to remain so for a while. The danger is that the authorities, trying to retain a grip on a situation that is irretrievably slipping away, will react to the extremes of the problem in ways that leave ordinary users' privacy unprotected. The best approach is to adapt traditional solutions rather than inventing new ones. The safeguards built into the traditional solutions may not be precisely appropriate, but they are far better than nothing.  相似文献   
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This paper, the first of two dealing with ultrasonic delay lines, is concerned mainly with the theoretical considerations involved in the general process of ultrasonic propagation. The transducer action is given considerable attention and an equivalent circuit employing a transmission line as an element is demonstrated. The diffraction spreading of the beam and absorptive losses in the transmitting medium are also discussed.  相似文献   
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