Effects of external loading on power output in a squat jump on a force platform: a comparison between strength and power athletes and sedentary individuals

The aim of this study was to determine the effects of external loading on power output during a squat jump on a force platform in athletes specializing in strength and power events (6 elite weight-lifters and 16 volleyball players) and in 20 sedentary individuals. Instantaneous power was computed from time-force curves during vertical jumps with and without an external load (0, 5 or 10 kg worn in a special vest). The jumps were performed from a squat position, without lower limb counter-movement or an arm swing. Peak instantaneous power corresponded to the highest value of instantaneous power during jumping. Average power throughout the push phase of the jump was also calculated. A two-way analysis of variance showed significant interactions between the load and group effects for peak instantaneous power (P< 0.01) and average power (P< 0.001). Peak instantaneous power decreased significantly in sedentary individuals when moderate external loads were added. The peak instantaneous power at 0 kg was greater than that at 5 and 10 kg in the sedentary individuals. In contrast, peak instantaneous power was independent of load in the strength and power athletes. Mean power at 0 kg was significantly lower than at 5 kg in the athletes; at 0 kg it was significantly higher than at 10 kg in the sedentary males and at 5 and 10 kg in the sedentary females. In all groups, the force corresponding to peak instantaneous power increased and the velocity corresponding to peak instantaneous power decreased with external loading. The present results suggest that the effects of external loading on peak instantaneous power are not significant in strength and power athletes provided that the loads do not prevent peak velocity from being higher than the velocity that is optimal for maximal power output.     

Influence of recovery intensity on time spent at maximal oxygen uptake during an intermittent session in young,endurance-trained athletes

Abstract

In this study, we examined the effects of three recovery intensities on time spent at a high percentage of maximal oxygen uptake (t90[Vdot]O_2max) during a short intermittent session. Eight endurance-trained male adolescents (16 ± 1 years) performed four field tests until exhaustion: a graded test to determine maximal oxygen uptake ([Vdot]O_2max; 57.4 ± 6.1 ml · min^?1 · kg^?1) and maximal aerobic velocity (17.9 ± 0.4 km · h^?1), and three intermittent exercises consisting of repeat 30-s runs at 105% of maximal aerobic velocity alternating with 30 s active recovery at 50% (IE₅₀), 67% (IE₆₇), and 84% (IE₈₄) of maximal aerobic velocity. In absolute values, mean t90[Vdot]O_2max was not significantly different between IE₅₀ and IE₆₇, but both values were significantly longer compared with IE₈₄. When expressed in relative values (as a percentage of time to exhaustion), mean t90[Vdot]O_2max was significantly higher during IE₆₇ than during IE₅₀. Our results show that both 50% and 67% of maximal aerobic velocity of active recovery induced extensive solicitation of the cardiorespiratory system. Our results suggest that the choice of recovery intensity depends on the exercise objective.     

Indexing Grey Resources: Considering Usual Behavior of Library Users and the Use of Dublin Core Metadata via a Database of Specialized Vocabulary

Grey resources spread over a large set of matters. In each field of interest, people have their own concepts, each group will use their own vocabulary. Most authors of grey resources were not able to determine the Decimal or Dewey classification themselves, nor are they able to fix themselves the appropriate terms to embed in the DC elements. It is then worth providing the web user with an interface that makes him feel at home, by adapting automatically the terms designing the fields of the search form to those which are in use in his domain of activity. The whole classification proposed cover about 110 different topics, each one having a set of terms chosen to entitle the fields of the interface of thematic search as well the submission forms. Moreover, seven entry points are proposed in the first step of the connection, driving the user towards the appropriate context in accordance with the purpose of the document to find: teaching and research; literature; technological documentation and data sheets; vulgarization and everyday life; citizen and social activities; arts, sports and spare time; bank of images. Indeed, the system must allow the flexibility that allow the replacement of any term by another if necessary. So the entire set of terms is put in a database. This system is also able to adapt the language chosen by the user. The submission forms filled by authors are parsed according to the topic selected and the Dublin Core metadata file––as an XML file––is generated and stored in the indexing server. It is delivered on simple metadata request, and is reachable by a hyperlink included in any page of search results. The experimental system has been built and evaluated over a period of five years, and was implemented in the site of the University of Poitiers since June 2005. The software is to be released under free software license (CECILL).     

SARA: A Text-Based and Reader-Based Theory of Signaling

We propose a two-component theory of text signaling devices. The first component is a text-based analysis that characterizes any signaling device along four dimensions: (a) the type of information it makes available, (b) its scope, (c) how it is realized in the text, and (d) its location with respect to the content it cues. The second component is a reader-based analysis in which signaling effects on text-processing are hypothesized to depend jointly on (a) the relevance of the signaled information to the readers' goals and background knowledge and (b) the accessibility of the signaled information to cognitive processes. The two components of the model are closely related: The text-based component specifies the information made available to the reader, and the accessibility of that information is influenced by the realization properties, scope, and location of the signaling device relative to the cued content.     

Bibliotheca Alexandrina—Reviving a legacy of the past for a brighter common future

After briefly recalling the creation, organization, role and destruction of the Ancient Library of Alexandria, this article describes the scope and objectives of the new Bibliotheca Alexandrina and its functions and organization in six departments. It explains the symbolic and aesthetic values of the winning design for the new library, the budget required for its creation, and the international support so far obtained. It summarizes the steps undertaken by Egypt, UNESCO and UNDP and briefly explains the future strategy for proceeding with the implementation of the project. It concludes by high-lighting the meaning of the new Bibliotheca Alexandrina for Egypt, UNESCO and the International Community.