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11.
Apostolos Gerontas 《Science & Education》2014,23(8):1681-1700
Chromatographic instrumentation has been really influential in shaping the modern chemical practice, and yet it has been largely overlooked by history of science.Gas chromatography in the 1960s was considered the analytical technique closer to becoming dominant, and being the first automated chromatography set the standards that all the subsequent chromatographic instrumentation had to fulfill. Networks of specialists, groups of actors, corporate strategies and the analytical practice itself, were all affected and in many ways because of the entrance of gas chromatography in the chemical laboratory and in the instrumentation market. This paper gives a view of the early history of the gas chromatography instrumentation, relates it to the broader research-technology phenomenon and discusses issues of education and group reproduction in the case of the groups of technologists of the era. The chaotic elements of knowledge transfer during the instrumentation revolution in chemistry are being highlighted and they are being connected to the observable radical innovation of the period. 相似文献
12.
Apostolos S. Theodorou Carlton B. Cooke Roderick F. G. J. King Colin Hood Terry Denison Barney G. Wainwright 《Journal of sports sciences》2013,31(11):853-859
We investigated the effect of an acute creatine loading (25 g per day for 4 days) and longer-term creatine supplementation (5 g of creatine or 5 g of placebo per day for 2 months) on the performance of 22 elite swimmers during maximal interval sessions. After the acute creatine loading, the mean of the average interval swim times for all swimmers (n = 22) improved (44.3 +/- 16.5 s before vs 43.7 +/- 16.3 s after supplementation; P ? 0.01). Three of the 22 swimmers did not respond positively to supplementation. After 2 months of longer term creatine supplementation or placebo,neither group showed a significant change in swimming performance (38.7 +/-13.5 s before vs 38.7 +/- 14.1 s after for the creatine group; 48.7 +/- 18.0 s before vs 48.7 +/- 18.1 s after for the placebo group). We conclude that, in elite swimmers, 4 days of acute creatine loading improves swimming performance significantly when assessed by maximal interval sessions. However, longer-term supplementation for 2 months (5 g of creatine per day) did not benefit significantly the creatine group compared with the placebo group. 相似文献
13.
Efthimis N. Efthimiadis Nicos Malevris Apostolos Kousaridas Alexandra Lepeniotou Nikos Loutas 《Information Retrieval》2009,12(3):352-379
The study reports on a longitudinal and comparative evaluation of Greek language searching on the web. Ten engines, five global
(A9, AltaVista, Google, MSN Search, and Yahoo!) and five Greek (Anazitisi, Ano-Kato, Phantis. Trinity, and Visto), were evaluated
using (a) navigational queries in 2004 and 2006; and (b) by measuring the freshness of the search engine indices in 2005 and
2006. Homepage finding queries for known Greek organizations were created and searched. Queries included the name of the organization
in its Greek and non-Greek, English or transliterated equivalent forms. The organizations represented ten categories: government
departments, universities, colleges, travel agencies, museums, media (TV, radio, newspapers), transportation, and banks. The
freshness of the indices was evaluated by examining the status of the returned URLs (live versus dead) from the navigational
queries, and by identifying if the engines have indexed 32480 active (live) Greek domain URLs. Effectiveness measures included
(a) qualitative assessment of how engines handle the Greek language; (b) precision at 10 documents (P@10); (c) mean reciprocal
rank (MRR); (d) Navigational Query Discounted Cumulative Gain (NQ-DCG), a new heuristic evaluation measure; (e) response time;
(f) the ratio of the dead URL links returned, (g) the presence or absence of URLs and the decay observed over the period of
the study. The results report on which of the global and Greek search engines perform best; and if the performance achieved
is good enough from a user’s perspective. 相似文献
14.
Bin Rong Rui Liu Zhenyu Li Changxi Feng Guangchao You Fafitis Apostolos 《天津大学学报(英文版)》2017,23(3):258-266
Finite element analysis and parametric studies were performed to investigate the flexural capacity of the panel zone of diaphragm-through joints between concretefilled square steel tubular columns and H-shaped steel beams.Through the comparisons of failure modes,load–displacement curves,and bearing capacity,it was found that the flexural capacity of the panel zone of diaphragmthrough joints was determined by the tensile action and influence of the web of H-shaped steel beams,and the axial load should be taken into account.The steel tube and the diaphragm were the major parts of the joint that resisted the bending moment.The contribution of in-filled concrete had little influence on the flexural capacity of the panel zone of the joint and could be neglected.According to the results of these numerical studies,a formula that considered the influence of the web of H-shaped steel beams and the axial load was developed based on the yield lines in the diaphragm and the steel tube.The results of the proposed formula were in good agreement with the numerical data of this investigation. 相似文献
15.
Apostolos S. Theodorou Vassilios Panoutsakopoulos Timothy A. Exell Polyxeni Argeitaki Giorgos P. Paradisis Athanasia Smirniotou 《Journal of sports sciences》2017,35(4):346-354
The aim of this study was to investigate the relative influence of step length (SL) and step frequency (SF) on step velocity (SV) during the approach run of high-level long jumpers and to quantify the asymmetry of these step characteristics. Spatiotemporal data of the approach run were collected during national competition from 10 long jumpers (age 26.2 ± 4.1 years, height 1.84 ± 0.06 m, mass 72.77 ± 3.23 kg, personal best performance 7.96 ± 0.30 m). Analyses were conducted for total approach, early approach and late approach. For the total approach 4/10 athletes were SF reliant and 6/10 athletes favoured neither characteristic. At the early approach, 3/10 athletes were SF reliant and 7/10 athletes favoured neither. During late approach 2/10 athletes demonstrated SL reliance, 7/10 athletes were SF reliant and 1/10 athletes favoured neither. Four athletes displayed significant asymmetry for SL and three for SF. However, no athletes demonstrated significant asymmetry for SV indicating that the asymmetrical demands of take-off do not have a marked influence on step characteristic asymmetry, probably due to the constraints of the event. Consideration should be given to the potentially conflicting demands between limbs for individual athletes. 相似文献
16.
Dimitrios Draganidis Athanasios Chatzinikolaou Athanasios Z. Jamurtas Jose Carlos Barbero Dimitrios Tsoukas Apostolos Spyridon Theodorou 《Journal of sports sciences》2013,31(7):714-722
Abstract The purpose of this study was to determine the recovery rate of football skill performance following resistance exercise of moderate or high intensity. Ten elite football players participated in three different trials: control, low-intensity resistance exercise (4 sets, 8–10 repetitions/set, 65–70% 1 repetition maximum [1RM]) and high-intensity resistance exercise (4 sets, 4–6 repetitions/set, 85–90% 1RM) in a counterbalanced manner. In each experimental condition, participants were evaluated pre, post, and at 24, 48, 72 h post exercise time points. Football skill performance was assessed through the Loughborough Soccer Passing Test, long passing, dribbling, shooting and heading. Delayed onset muscle soreness, knee joint range of motion, and muscle strength (1RM) in squat were considered as muscle damage markers. Blood samples analysed for creatine kinase activity, C-reactive protein, and leukocyte count. Passing and shooting performance declined (P < 0.05) post-exercise following resistance exercise. Strength declined post-exercise following high-intensity resistance exercise. Both trials induced only a mild muscle damage and inflammatory response in an intensity-dependent manner. These results indicate that football skill performance is minimally affected by acute resistance exercise independent of intensity suggesting that elite players may be able to participate in a football practice or match after only 24 h following a strength training session. 相似文献
17.
A questionnaire, as a basic tool of organization of scientific observation, consists of two schemas: a data schema that corresponds
to the specifications and the conceptual determinations of scientific vocabulary and a communicative schema that organizes
the communication between the scientists and respondents depending on the particular characteristics of the asked population.
The objective of this paper is the design of a documentation model for the questions of a questionnaire that would allow the
detection of similar questions throughout a database. Such a model can successfully manage the documentation problems of comparative
longitudinal research, whereas the questions of a questionnaire are repeated and changed slightly or go unchanged through
the waves. It can also help researchers that are concerned with secondary analysis, for the detection of similar questions
of similar or even different studies. 相似文献
18.
This paper analyzes how different R&D strategies of incumbent firms affect the quantity and quality of their entrepreneurial spawning. When examining entrepreneurial ventures of ex-employees of firms with different R&D strategies, three things emerge: First, firms with persistent R&D investments and a general superiority in sales, exports, productivity, profitability and wages are less likely to generate entrepreneurs than firms with temporary or no R&D investments. Second, start-ups from knowledge intensive business service (KIBS) firms with persistent R&D investments have a significantly increased probability of survival. No corresponding association between the R&D strategies of incumbents and survival of entrepreneurial spawns is found for incumbents in manufacturing sectors. Third, spin-outs from KIBS-firms are more likely to survive if they start in the same sector, indicating the importance of inherited knowledge. These findings suggest that R&D intensive firms are less likely to generate employee start-ups, but their entrepreneurial spawns tend to be of higher quality. 相似文献
19.
Apostolos Mavridis Aikaterini Katmada Thrasyvoulos Tsiatsos 《Educational technology research and development : ETR & D》2017,65(6):1451-1470
This study examined the effects of using an online flexible educational game on students’ attitude towards mathematics as compared to the traditional method of solving mathematical problems. Moreover, the study assessed the learning effectiveness of the game and investigated potential gender differences in the game’s effectiveness on changing students’ attitude. The participants of the study were 79 students who were randomly assigned to a control and treatment group, as well as four coordinator teachers. The game was configurable and it was used as a supplementary teaching method. The intervention lasted 14 weeks and the data collection was based on quantitative measures and interviews. The results of the analysis indicated that the game approach was effective on improving students’ attitude towards mathematics and that it also resulted in better learning outcomes in the treatment group as compared to that of the control group. Furthermore, it was shown that the gender of the students did not influence the positive effect of the game on students’ attitude. These results suggest that the incorporation of flexible games into the traditional teaching of mathematics could possibly bring beneficial effects. 相似文献
20.
Flora Panteli Athanasia Smirniotou Apostolos Theodorou 《Journal of sports sciences》2016,34(12):1116-1123
The purpose of the study was to investigate possible changes at step pattern and technical performance of the long jump approach run in seven young long jumpers by modifying the performance environment (long jump runway versus track lane) and the nested actions (run-through with take-off versus complete long jump). Our findings suggest that the step pattern and technical aspects of the approach run are affected by environmental context and nested task constraints. In terms of environmental context, it appears that practising the training routine of run-through followed by take-off on the long jump runway allows athletes to simulate competition conditions in terms of step regulation and technical efficacy. The task of run-through followed by take-off on the track lane failed to initiate visual perception, step regulation and technical efficiency at the steps preceding the instant of take-off. In terms of nested task constraints, when run-ups were followed by jump for distance instead of only a take-off, a higher level of consistency was achieved and step regulation was based on perception–action coupling. Practising long jump run-up accuracy at a setting not containing the informational elements of the performance environment fails to develop the key elements of the skill. 相似文献