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11.
Volianitis S Dawson EA Dalsgaard M Yoshiga C Clemmesen J Secher NH Olsen N Nielsen HB 《Journal of sports sciences》2012,30(2):149-153
Reduced hepatic lactate elimination initiates blood lactate accumulation during incremental exercise. In this study, we wished to determine whether renal lactate elimination contributes to the initiation of blood lactate accumulation. The renal arterial-to-venous (a-v) lactate difference was determined in nine men during sodium lactate infusion to enhance the evaluation (0.5 mol x L(-1) at 16 ± 1 mL x min(-1); mean ± s) both at rest and during cycling exercise (heart rate 139 ± 5 beats x min(-1)). The renal release of erythropoietin was used to detect kidney tissue ischaemia. At rest, the a-v O(2) (CaO(2)-CvO(2)) and lactate concentration differences were 0.8 ± 0.2 and 0.02 ± 0.02 mmol x L(-1), respectively. During exercise, arterial lactate and CaO(2)-CvO(2) increased to 7.1 ± 1.1 and 2.6 ± 0.8 mmol x L(-1), respectively (P < 0.05), indicating a -70% reduction of renal blood flow with no significant change in the renal venous erythropoietin concentration (0.8 ± 1.4 U x L(-1)). The a-v lactate concentration difference increased to 0.5 ± 0.8 mmol x L(-1), indicating similar lactate elimination as at rest. In conclusion, a -70% reduction in renal blood flow does not provoke critical renal ischaemia, and renal lactate elimination is maintained. Thus, kidney lactate elimination is unlikely to contribute to the initial blood lactate accumulation during progressive exercise. 相似文献
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Niels Opstrup 《Journal of Higher Education Policy & Management》2017,39(5):524-539
Pay-for-performance schemes have become a widespread management strategy in the public sector. However, not much is known about the rationales that trigger the adoption of performance-related pay provisions. This article examines managerial and organisational features of university departments in Denmark that use publication incentive payments. Most often it is used when heads of department outside the humanities think it is a good idea to reward scholars financially for publications. In-depth analysis of the cases reveals, however, that department heads cannot simply be divided between ‘believers’ and ‘non-believers’. Almost half expressed confidence in that publication incentive payments motivate researchers to perform better, not because of the monetary reward, but because of the positive feedback signalled by the pay supplement. 相似文献
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Niels Hermens Sabina Super Kirsten T. Verkooijen Maria A. Koelen 《Research quarterly for exercise and sport》2017,88(4):408-424
Purpose: Despite the strong belief in sports programs as a setting in which socially vulnerable youth can develop life skills, no overview exists of life skill development in sports programs serving this youth group. Therefore, the present systematic review provides an overview of the evidence on life skill development in sports programs serving socially vulnerable youth and, insofar as it was investigated in the included studies, of the conditions conducive to life skill development in these sports programs. Method: Potentially relevant studies published during 1990 to 2014 were identified by a search in 7 electronic databases. The search combined terms relating to (a) sport, (b) youth AND socially vulnerable, and (c) life skills. Eighteen of the 2,076 unique studies met the inclusion criteria. Results: Each included study reported that at least 1 life skill improved in youth who participated in the studied sports program. Improvements in cognitive and social life skills were more frequently reported than were improvements in emotional life skills. Only a few of the included studies investigated the conditions in the studied sports programs that made these programs conducive to life skill development. Conclusions: Sports programs have the potential to make a difference in the life skill development of socially vulnerable youth. This conclusion needs to be treated with some caution, because the studies experienced many challenges in reducing the risk for bias. Several alternative research strategies are suggested for future studies in this field. 相似文献
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Niels Smits Gideon J. Mellenbergh Harrie C. M. Vorst 《Journal of Educational Measurement》2002,39(3):187-206
In this article, grade point average (GPA) is considered a missing data technique for unavailable grades in school grade records. In Study 1, theoretical and empirical differences between GPA and seven alternative missing grade techniques were considered. These seven techniques are subject mean substitution, corrected subject mean, subject correlation substitution, regression imputation, expectation maximization algorithm imputation and two multiple imputation methods-stochastic regression imputation and data augmentation., The missing grade techniques differ greatly. Data augmentation and stochastic regression imputation appear to be superior as missing grade techniques. In Study 2, the completed grade records (observed and imputed values) were used in two prediction analyses of academic achievement. One analysis was based on unweighed grades, the other on weighed grades. In both analyses, alternative missing grade methods produced better and more consistent predictions. It is concluded that some alternative missing grade methods are superior to GPA. 相似文献
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In the few available studies on the use of books in examinations, open-book tests have been found to reduce pre-test memorization and anxiety during examinations without affecting academic performance. However, these studies were made with students in non-book systems, whereas systems which allowed books in all exams might be thought likely to create a non-fact-learning attitude in students. The present study was undertaken in a book-allowing system with 120 students during a regular course in physiology at a medical school. Each group sat two parallel 60-item multiple choice tests and used books in one test but not in the other. The tests took place about four weeks prior to the final examination, which is of the same type as the experimental tests. Recall items could yield less than 15% of maximum points, so that interpretation and problem-solving items predominated. Total test points with and without books did not differ significantly. An analysis of variance showed that the effect of books on recall items was only slight and that the two tests varied in difficulty, in spite of efforts to secure equality. 相似文献
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The sciences are often perceived by students as irrelevant as they do not see the content of science as related to their daily lives. Web 2.0-mediated activities are characterized by user-driven content production, collaboration, and multi-way communication. It has been proposed that employing Web 2.0 in educational activities will promote richer opportunities for making learning personally meaningful, collaborative, and socially relevant. Since Facebook is already in use among youths, it potentially provides a communicative link between educational content and students’ lives. The present study was conducted as a case study to provide an inductive, explorative investigation of whether and how the integration of Facebook into upper secondary biology can affect interest in biology and participation in learning communication. The results indicate that the coupling of formal and informal communication practices on Facebook serves to maintain interest and open up new learning possibilities while at the same time creating barriers to communication. These barriers are due to distractions, ethical issues, and a certain depreciation of the activities ensuing from the everydayness of Facebook as a communication platform. In conclusion, use of Facebook as an educational platform is not clearly good or bad. 相似文献
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Niels Holmqvist Niels H. Secher Kåre Sander‐Jensen Ulrich Knigge J⊘rgen Warberg Thue W. Schwartz 《Journal of sports sciences》2013,31(2):123-128
Exhaustive exercise is associated with a persistent sensation of weakness and sometimes nausea suggesting abdominal vagal activity. We measured plasma indices of sympathoadrenal (adrenaline, noradrenaline, dopamine) and vagal (pancreatic polypeptide) activity before, during and after submaximal and maximal exercise in healthy young subjects. Plasma adrenaline, noradrenaline and dopamine increased to 8.5 (range 7.4–40.5), 48.0 (32.3–100.5) and 1.8 (1.2–6.6) nmol l–1 respectively (n = 5), during maximal exercise and decreased towards control values within 15 min of rest. Pancreatic polypeptide (n = 10) increased only during maximal exercise and reached its highest value, 48 (21–145) pmol l–1, after exertion. The results conform to an increase in sympathetic activity during exercise and a persistent vagal activity after intense exercise which could contribute to the sensation of weakness. 相似文献
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Methods for detecting copying of multiple-choice test responses developed over a 60-year period are reviewed and compared with respect to their effectiveness and the practicality of their application for groups of varying size. Although effective detection methods are routinely used in large admissions and licensing testing programs, they are seldom applied in the areas of standardized testing or classroom testing in schools or colleges. Circumstances associated with this discrepancy are discussed. 相似文献