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Yoann M. Garnier Christos Paizis Romuald Lepers 《European Journal of Sport Science》2019,19(2):166-176
The present study assessed neuromuscular and corticospinal changes during and after a fatiguing submaximal exercise of the knee extensors in different modes of muscle contraction. Twelve subjects performed two knee extensors exercises in a concentric or eccentric mode, at the same torque and with a similar total impulse. Exercises consisted of 10 sets of 10 repetitions at an intensity of 80% of the maximal voluntary isometric contraction torque (MVIC). MVIC, maximal voluntary activation level (VAL) and responses of electrically evoked contractions of the knee extensors were assessed before and after exercise. Motor evoked potential amplitude (MEP) and cortical silent period (CSP) of the vastus medialis (VM) and rectus femoris (RF) muscles were assessed before, during and after exercise. Similar reductions of the MVIC (?13%), VAL (?12%) and a decrease in the peak twitch (?12%) were observed after both exercises. For both VM and RF muscles, MEP amplitude remained unchanged during either concentric or eccentric exercises. No change of the MEP amplitude input–output curves was observed post-exercise. For the RF muscle, CSP increased during the concentric exercise and remained lengthened after this exercise. For the VM muscle, CSP was reduced after the eccentric exercise only. For a similar amount of total impulse, concentric and eccentric knee extensor contractions led to similar exercise-induced neuromuscular response changes. For the two muscles investigated, no modulation of corticospinal excitability was observed during or after either concentric or eccentric exercises. However, intracortical inhibition showed significant modulations during and after exercise. 相似文献
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This research, carried out in Greece on pupils aged 12–16, focuses on the transformation of their representations concerning
light emission and image formation by extended light sources. The instructive process was carried out in two stages, each
one having a different, distinct target set. During the first stage, the appropriate conflict conditions were created by contrasting
the subjects’ predictions with the results of experimental situations inspired by the History of Science, with a view to destabilizing
the pupils’ alternative representations. During the second stage, the experimental teaching intervention was carried out;
it was based on the geometrical optics model and its parameters were derived from Kepler’s relevant historic experiment. For
the duration of this process and within the framework of didactical interactions, an effort was made to reorganize initial
limited representations and restructure them at the level of the accepted scientific model. The effectiveness of the intervention
was evaluated two weeks later, using experimental tasks which had the same cognitive yet different empirical content with
respect to the tasks conducted during the intervention. The results of the study showed that the majority of the subjects
accepted the model of geometrical optics, that is, the pupils were able to correctly predict and adequately justify the experimental
results based on the principle of punctiform light emission. Educational and research implications are discussed.
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| Christos DedesEmail: |
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Christos Giatsidis Giannis Nikolentzos Chenhui Zhang Jie Tang Michalis Vazirgiannis 《Journal of Informetrics》2019,13(2):757-768
Traditionally, citation count has served as the main evaluation measure for a paper's importance and influence. In turn, many evaluations of authors, institutions and journals are based on aggregations upon papers (e.g. h-index). In this work, we explore measures defined on the citation graph that offer a more intuitive insight into the impact of a paper than the superficial count of citations. Our main argument is focused on the identification of influence as an expression of the citation density in the subgraph of citations built for each paper. We propose two measures that capitalize on the notion of density providing researchers alternative evaluations of their work. While the general idea of impact for a paper can be viewed as how many researchers have shown interest to a piece of work, the proposed measures are based on the hypothesis that a piece of work may have influenced some papers even if they do not contain references to that piece of work. The proposed measures are also extended to researchers and journals. 相似文献
5.
Christos Doumas 《Endeavour》1983,7(3):144-149
The abrupt decline of the Minoan civilisation in Crete between 1500 and 1450 BC has been linked with the consequences of an exceptionally violent eruption of the volcano Santorini. This article reviews this, and other theories, in the light of archaeological evidence acquired in the course of excavations at Thera during the past fifteen years. 相似文献
6.
Ardith Baker Teresa Bittner Christos Makrigeorgis Gloria Johnson Joseph Haefner 《Teaching Statistics》2010,32(3):81-87
Recent evidence indicates that decision makers are more sensitive to potential losses than gains. Loss aversion psychology has led behavioural economists to look beyond expected utility by developing prospect theory. We demonstrate this theory using the Deal or No Deal game show. 相似文献
7.
Costas Chryssanthopoulos Christos Ziaras Tanja Oosthuyse Ioannis Lambropoulos Paradisis Giorgios P Elias Zacharogiannis 《Journal of sports sciences》2018,36(7):824-833
This study examined the effect of carbohydrate mouth rinsing on endurance running performance in women. Fifteen female recreational endurance runners, who used no oral contraceptives, ran two races of 1-h duration on an indoor track (216-m length) at 18:00 h after an 8-h fast with a 7-days interval between races, corresponding to the 3rd-10th day of each premenopausal runner’s menstrual cycle, or any day for the postmenopausal runners. In a double-blind random order, participants rinsed their mouth with 25 ml of either a 6.4% carbohydrate (RCHO) or a placebo solution (RP). No fluid was ingested during exercise. Serum 17β-Εstradiol (P = 0.59) and Progesterone (P = 0.35) did not differ between treatments. There was no difference in 1-hour running performance (RCHO: 10,621.88 ± 205.98 m vs. RP: 10,454.00 ± 206.64 m; t = 1.784, P = 0.096). Furthermore, the mean percentage effect (±99%CI) of RCHO relative to RP, 1.67% (?1.1% to 4.4%), and Cohen’s effect size (d = 0.21) support a trivial outcome of RCHO for total distance covered. In conclusion, carbohydrate mouth rinsing did not improve 60-min track running performance in female recreational runners competing in a low ovarian hormone condition, after an 8-h fast and when no fluid was ingested during exercise. 相似文献
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Christos V. Massalas George I. Tzivanidis John T. Katsikadelis 《Journal of The Franklin Institute》1978,306(6):449-455
In this paper, a solution is presented to the buckling problem of a continuous beam resting on a tensionless foundation model that was proposed by Winkler and by Reissner. 相似文献
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Athanassios Protopapas Aikaterini Fakou Styliani Drakopoulou Christos Skaloumbakas Angeliki Mouzaki 《Reading and writing》2013,26(5):615-646
In this study we propose a classification system for spelling errors and determine the most common spelling difficulties of Greek children with and without dyslexia. Spelling skills of 542 children from the general population and 44 children with dyslexia, Grades 3–4 and 7, were assessed with a dictated common word list and age-appropriate passages. Spelling errors were classified into broad categories, including phonological (graphophonemic mappings), grammatical (inflectional suffixes), orthographic (word stems), stress assignment (diacritic), and punctuation. Errors were further classified into specific subcategories. Relative proportions for a total of 11,364 errors were derived by calculating the opportunities for each error type. Nondyslexic children of both age groups made primarily grammatical and stress errors, followed by orthographic errors. Phonological and punctuation errors were negligible. Most frequent specific errors were in derivational affixes, stress diacritics, inflectional suffixes, and vowel historical spellings. Older children made fewer errors, especially in inflectional suffixes. Dyslexic children differed from nondyslexic ones in making more errors of the same types, in comparable relative proportions. Spelling profiles of dyslexic children did not differ from those of same-age children with poor reading skills or of younger children matched in reading and phonological awareness. In conclusion, spelling errors of both dyslexic and nondyslexic children indicate persistent difficulty with internalizing regularities of the Greek orthographic lexicon, including derivational, inflectional, and word (stem) families. This difficulty is greater for children with dyslexia. 相似文献
10.
Christos Dimitriadis 《Roeper Review》2013,35(2):107-122
This article presents findings from a case study of an in-classroom program based on ability grouping for Year 2 (ages 6–7) primary (elementary) children identified as high ability in mathematics. The study examined the role of classroom setting, classroom environment, and teacher’s approach in realizing and developing mathematical promise. The teacher’s approach was found to be fundamental to revealing and developing mathematical promise. However, a large regular classroom with a range of ability, along with some common beliefs that link mathematical prowess with competence in numerical calculations and that dominate the classroom environment, pose some major challenges for the teacher as well as obstacles and threats to the development of mathematical promise. The article illuminates these issues and suggests possible solutions. 相似文献