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We apply the knowledge discovery process to the mapping of current topics in a particular field of science. We are interested in how articles form clusters and what are the contents of the found clusters. A framework involving web scraping, keyword extraction, dimensionality reduction and clustering using the diffusion map algorithm is presented. We use publicly available information about articles in high-impact journals. The method should be of use to practitioners or scientists who want to overview recent research in a field of science. As a case study, we map the topics in data mining literature in the year 2011. 相似文献
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13.
This article is concerned with the career patterns of Finnish intellectuals and professionals. It aims to illuminate the trajectories of individuals who studied in universities in the 1960's and later found various types of positions in Finnish society. It illustrates certain aspects of this career differentiation and the role of the university in this process. The group being studied represents the professional and managerial core of society. Many of the individuals concerned hold visible positions in the public life of the nation. They do not, however, form any unitary class. The educated population is divided into various sections and levels which display quite different models of career trajectories and different forms of social influence. This diversity makes both the study of the impact of university education and the system of careers an extremely complex research theme. 相似文献
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In this study, we measured the vertical and horizontal take-off forces, plantar pressures and activation patterns of four muscles (vastus lateralis, gluteus maximus, tibialis anterior, gastrocnemius) in 10 ski jumpers in simulated laboratory conditions when wearing either training shoes or ski jumping boots. We found significant differences in vertical ( P ? 0.001), horizontal ( P ? 0.05) and resultant ( P ? 0.001) take-off velocities and vertical force impulse ( P ? 0.01). We found no significant differences in the jumpers' initial take-off positions; however, the jumping boots condition resulted in a smaller displacement in the final position of the following joint angles: ankle angle ( P ? 0.001), knee angle ( P ? 0.001), hip angle ( P ? 0.01) and shank angle relative to the horizontal ( P ? 0.01). This corresponds with less electromyographic activity during take-off in both the gastrocnemius (300 to 200 ms and 200 to 100 ms before take-off) and gluteus maximus (300 to 200 ms and 100 to 0 ms before take-off). During the early take-off in the jumping boots condition, significantly more pressure was recorded under the heel ( P ? 0.001), whereas the forefoot was more highly loaded at the end of the take-off. Differences in take-off velocity (representing the final output of the take-off) can be accounted for in the main by the different use of plantar flexion, emphasizing the role of the knee and hip extensors when wearing jumping boots. We conclude that the stiffness of the structure of the jumping boots may result in a forward shift of pressure, thus limiting the effective vertical force. To avoid this pressure shift, the pattern of movement of simulated take-offs should be carefully controlled, particularly when wearing training shoes. 相似文献
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Jarmo Perttunen Heikki Kyrolainen Paavo V. Komi Ari Heinonen 《Journal of sports sciences》2013,31(5):363-370
The triple jump is a demanding field event in which a jumper must tolerate extremely high impact forces while maintaining high horizontal speed. The present study was designed to clarify the mechanical loading characteristics and the role of neuromuscular function in the triple jump. Seven national triple jumpers (4 males, 3 females) volunteered to perform 3-6 jumps. The mean best performances were 14.32 - 0.45 m and 11.90 - 0.28 m for males and females, respectively. The three longest triple jumps for each jumper were selected for final analysis. The mean contact times were 0.139 s (hop), 0.157 s (step) and 0.177 s (jump). The largest ground reaction forces were observed in the step (15.2 times body weight), while the highest peak pressures were recorded under the heel and forefoot. The plantar pressure of the lateral side of the forefoot was highly related to the length of the triple jump ( P ? 0.05-0.01). In addition, electromyograms of both legs suggested that mechanical loading places high demands on the neuromuscular system, as characterized by the high rate of activation in the pre-activity phase followed by high eccentric activity. Thus, the high activities of the gastrocnemius, vastus lateralis and hip extensor muscles seem to play an important role in preventing unnecessary yielding of the jumper during the braking phase. 相似文献
16.
Antti Mero Riikka Raitanen Joerg Birkmayer Paavo Komi 《Journal of sports sciences》2013,31(3):311-319
Abstract The aim of this study was to assess the effects of nicotinamide adenine dinucleotide hydride (NADH) on maximal oxygen uptake ([Vdot]O2max), maximal anaerobic running time, and mental performance. Eight men were exposed to a supplement treatment (30 mg NADH as ENACHI tablets per day) and to a placebo treatment, each of 4 weeks' duration, in a balanced, double-blind, and cross-over design. The two treatments were separated by a 14-week wash-out period. The results indicated that [Vdot]O2max, maximal anaerobic running time, and the ability to concentrate were similar in the NADH and placebo conditions. There were also no differences in blood lactate, creatine kinase, reaction time or feelings of fatigue between the treatments. A counter-movement jump performed at rest and 2 min after the aerobic test differed significantly (P ≤ 0.05) between the treatment conditions and was higher in the NADH group. In conclusion, the NADH supplementation for 4 weeks had no effects on [Vdot]O2max, maximal anaerobic running time or mental performance. 相似文献
17.
This study introduces a novel framework for evaluating passage and XML retrieval. The framework focuses on a user’s effort
to localize relevant content in a result document. Measuring the effort is based on a system guided reading order of documents.
The effort is calculated as the quantity of text the user is expected to browse through. More specifically, this study seeks
evaluation metrics for retrieval methods following a specific fetch and browse approach, where in the fetch phase documents
are ranked in decreasing order according to their document score, like in document retrieval. In the browse phase, for each
retrieved document, a set of non-overlapping passages representing the relevant text within the document is retrieved. In
other words, the passages of the document are re-organized, so that the best matching passages are read first in sequential
order. We introduce an application scenario motivating the framework, and propose sample metrics based on the framework. These
metrics give a basis for the comparison of effectiveness between traditional document retrieval and passage/XML retrieval
and illuminate the benefit of passage/XML retrieval. 相似文献
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Changes in muscle activity with increasing running speed 总被引：3，自引：2，他引：1
Electromyographic (EMG) activity of the leg muscles and the ground reaction forces were recorded in 17 elite male middle-distance runners, who performed isometric maximal voluntary contractions (MVC) as well as running at different speeds. Electromyograms were recorded from the gluteus maximus, vastus lateralis, biceps femoris, gastrocnemius and tibialis anterior. The results indicated that the averaged EMG (aEMG) activities of all the muscles studied increased (P < 0.05) with increasing running speed, especially in the pre-contact and braking phases. At higher speeds, the aEMG activities of the gastrocnemius, vastus lateralis, biceps femoris and gluteus maximus exceeded 100% MVC in these same phases. These results suggest that maximal voluntary contractions cannot be used as an indicator of the full activation potential of human skeletal muscle. Furthermore, the present results suggest that increased pre-contact EMG potentiates the functional role of stretch reflexes, which subsequently increases tendomuscular stiffness and enhances force production in the braking and/or propulsive phases in running. Furthermore, a more powerful force production in the optimal direction for increasing running speed effectively requires increased EMG activity of the two-joint muscles (biceps femoris, rectus femoris and gastrocnemius) during the entire running cycle. 相似文献
19.
Leinonen Seija Müller Kurt Leppänen Paavo H.T. Aro Mikko Ahonen Timo Lyytinen Heikki 《Reading and writing》2001,14(3-4):265-296
Subgroups of Finnish dyslexic adults (N = 84)displaying, relative to each other, a distinctivecombination of accuracy and speed of oral text readingwere compared in phonological and orthographicprocessing, verbal short-term memory and readinghabits. Inaccurate phonological decoding appeared todetermine the number of errors made in text reading,while inability to utilize effectively rapid lexicalaccess of words manifested as slow text reading speed.Phonological and orthographic word recognitionprocesses were less tightly integrated among dyslexicthan normal readers. Our results indicate thatadvanced orthographic processing skills might help anumber of the dyslexic readers to compensate for theirserious phonological deficits. The subgroups alsodiffered from each other in reading habits. Arelatively fast reading speed, even with numerouserrors, appears to be more rewarding in everydayreading than a slower but more accurate readingstyle. 相似文献
20.
Carita Kiili Donald J. Leu Miika Marttunen Jarkko Hautala Paavo H. T. Leppänen 《Reading and writing》2018,31(3):533-557
This study assessed the ability of 426 students (ages 12–13) to critically evaluate two types of online locations on health issues: an academic resource and a commercial resource. The results indicated limited evaluation abilities, especially for the commercial resource, and only a small, partial association with prior stance and offline reading ability. Only about half (51.4%) of the students questioned the credibility of the commercial online resource and only about 19% of the students showed an ability to fully recognize commercial bias. Wide variation existed in students’ ability to evaluate online information, as approximately one-fourth of the students performed poorly when evaluating the overall credibility of both online resources and one-fourth performed well. Logistic regression models showed that offline reading skills accounted for only 8.8% of the variance for the academic online resource and 15.1% of that for the commercial resource. No association appeared between evaluation and background knowledge, although an association with prior stance was observed for each online resource. The results are discussed in light of previous research and the need to pay greater attention to the critical evaluation of online resources during classroom instruction. 相似文献