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51.
Abstract Hydration status is not easily measured, but acute changes in hydration status are often estimated from body mass change. Changes in body mass are also often used as a proxy measure for sweat losses. There are, however, several sources of error that may give rise to misleading results, and our aim in this paper is to quantify these potential errors. Respiratory water losses can be substantial during hard work in dry environments. Mass loss also results from substrate oxidation, but this generates water of oxidation which is added to the body water pool, thus dissociating changes in body mass and hydration status: fat oxidation actually results in a net gain in body mass as the mass of carbon dioxide generated is less than the mass of oxygen consumed. Water stored with muscle glycogen is presumed to be made available as endogenous carbohydrate stores are oxidized. Fluid ingestion and sweat loss complicate the picture by altering body water distribution. Loss of hypotonic sweat results in increased osmolality of body fluids. Urine and faecal losses can be measured easily, but changes in the water content of the bladder and the gastrointestinal tract cannot. Body mass change is not always a reliable measure of changes in hydration status and substantial loss of mass may occur without an effective net negative fluid balance. 相似文献
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The comparative kilogram-price of an equivalent product group in international trade is a rough indication of underlying technological capability. Although there are many theoretical and practical difficulties involved in applying this approach to East-West trade, these difficulties can be minimised by a careful selection of product groups. In this connection, advanced chemical products are particularly suitable because the chemical industry is one in which both kilogram-prices and technological sophistication tend to increase hand-in-hand at successive stages of manufacture. The results of this enquiry are quite striking. From the standpoint of bilateral trade, the kilogram-prices of Soviet and East European exports to the EEC countries are consistently lower than those of corresponding imports from the EEC. Throughout the period 1960–1972 these differentials appears to be closing either very slowly or not at all, while the Soviet and East European share of the EEC marked has remained more or less constant or has declined since the mid-1960's. From the alternative perspective of the “neutral” Yugoslavian market, the kilogram-prices of EEC exports are again consistently higher than those obtained by the Comecon coun tries. Moreover, there has been a considerable eroson in the market share of the Comecon countries since the mid-1960's. These general findings are broadly in line with other kinds of estimates and suggest that in these relatively advanced and dynamic sectors of industry, Soviet and East European technology is at present substantially inferior to that of the Common Market countries. 相似文献
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We develop and propose a new counting method at the aggregate level for contributions to scientific publications called modified fractional counting (MFC). We show that, compared to traditional complete-normalized fractional counting, it eliminates the extreme differences in contributions over time that otherwise occur between scientists that mainly publish alone or in small groups and those that publish with large groups of co-authors. As an extra benefit we find that scientists in different areas of research turn out to have comparable average contributions to scientific articles. We test the method on scientists at Norway’s largest universities and find that, at an aggregate level, it indeed supports comparability across different co-authorship practices as well as between areas of research. MFC is thereby useful whenever the research output from institutions with different research profiles are compared, as e.g., in the Leiden Ranking. Finally, as MFC is actually a family of indicators, depending on a sensitivity parameter, it can be adapted to the circumstances. 相似文献
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Abstract Four sprint starting positions—the bunch, medium, elongated, and hyperextended—were compared on mean elapsed times at distances of 10 and 30 yd. Averages of three starts for each of 30 inexperienced college undergraduate males on each type of start were derived from electronically-controlled measures, the times for both distances being recorded from the same start. Statistical analyses indicated significantly lower elapsed times with the hyperextended starting position. 相似文献
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Esther T. Canrinus Michelle Helms‐Lorenz Douwe Beijaard Jaap Buitink Adriaan Hofman 《Educational studies》2011,37(5):593-608
This study shows that professional identity should not be viewed as a composed variable with a uniform structure. Based on the literature and previous research, we view teachers’ job satisfaction, self‐efficacy, occupational commitment and change in the level of motivation as indicators of teachers’ professional identity. Using two‐step cluster analysis, three distinct professional identity profiles have empirically been identified, based on data of 1214 teachers working in secondary education in the Netherlands. These profiles differed significantly regarding the indicators of teachers’ professional identity. Teachers belonging to the found profiles did not significantly differ in their amount of experience. 相似文献
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The purpose of the study was to examine the relationship of classroom environment to attitudes toward science and achievement in science among tenth grade biology students. An attitude instrument was administered at three times during the school year to measure student attitudes toward science and the classroom environment. The classroom environment measures examined six areas: emotional climate of the science classroom, science curriculum, physical environment of the science classroom, science teacher, other students in the science classroom, and friends attitudes toward science. Student achievement in science was measured by teacher reported semester grades. The results of the study indicated: (1) student attitudes toward the classroom environment predicted between 56 to 61% of the variance in attitudes toward science, (2) student attitudes toward the classroom environment predicted between 5 to 14% of the variance in achievement in science, (3) student attitudes toward science and attitudes toward the classroom environment predicted between 8 and 18% of the variance in achievement in science. 相似文献