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1.
Educational research has shown that high school and university students also follow the Aristotelian idea about motion; for example, a continuous action of a force is necessary to keep an object in motion. The survey presented in this article aims at a deeper investigation of secondary education students' ideas about the forces involved in objects moving under the sole influence of gravity. The main objectives are: (1) to investigate other ideas or difficulties, which intervene and determine students' mental models about motion and force, and (2) to reveal how the students in the sample are grouped according to their alternative conceptions. Our study has been mainly determined by the revision in Science Curriculum established in Greece three years ago. A survey has been administered to a total of 146 students (15–16 years old) attending six typical public high schools in Greece. The results presented show that the traditional instruction is pertinent while the approaches of the New Physics Curriculum have not been effectively expanded to the schools. The majority of the students exhibited the idea that the original force is continuously exerted to the ball during its motion. On the other hand, multivariate analysis has identified three discernible groups of students which have exhibited a persistent and rather consistent approach: (1) An extended group of students having the above misconception, (2) a second group of students which, generally, responded correctly to the tasks, and (3) a third group of students, which ignored the presence of the gravitational force and/or believe that the action-reaction forces are both exerted to the ball during its motion. 相似文献
2.
Athanassios Protopapas Svetlana Gerakaki Stella Alexandri 《Journal of Research in Reading》2006,29(4):418-432
Greek is a language with lexical stress that marks stress orthographically with a special diacritic. Thus, the orthography and the lexicon constitute potential sources of stress assignment information in addition to any possible general default metrical pattern. Here, we report two experiments with secondary education children reading aloud pseudo‐word stimuli, in which we manipulated the availability of lexical (using stimuli resembling particular words) and visual (existence and placement of the diacritic) information. The reliance on the diacritic was found to be imperfect. Strong lexical effects as well as a default metrical pattern stressing the penultimate syllable were revealed. Reading models must be extended to account for multisyllabic word reading including, in particular, stress assignment based on the interplay among multiple possible sources of information. 相似文献
3.
Race walking is an Olympic event where no visible loss of contact should occur and the knee must be straightened until midstance. The purpose of this study was to analyse ground reaction forces of world-class race walkers and associate them with key spatiotemporal variables. Nineteen athletes race walked along an indoor track and made contact with two force plates (1000 Hz) while being filmed using high-speed videography (100 Hz). Race walking speed was correlated with flight time (r = .46, p = .049) and flight distance (r = .69, p = .001). The knee's movement from hyperextension to flexion during late stance meant the vertical push-off force that followed midstance was smaller than the earlier loading peak (p < .001), resulting in a flattened profile. Athletes with narrower stride widths experienced reduced peak braking forces (r = .49, p = .046), peak propulsive forces (r = .54, p = .027), peak medial forces (r = .63, p = .007) and peak vertical push-off forces (r = .60, p = .011). Lower fluctuations in speed during stance were associated with higher stride frequencies (r = .69, p = .001), and highlighted the importance of avoiding too much braking in early stance. The flattened trajectory and consequential decrease in vertical propulsion might help the race walker avoid visible loss of contact (although non-visible flight times were useful in increasing stride length), while a narrow stride width was important in reducing peak forces in all three directions and could improve movement efficiency. 相似文献
4.
Athanassios Protopapas Katerina Katopodi Angeliki Altani George K. Georgiou 《Scientific Studies of Reading》2018,22(3):248-263
Word list reading fluency is theoretically expected to depend on single word reading speed. Yet the correlation between the two diminishes with increasing fluency, while fluency remains strongly correlated to serial digit naming. We hypothesized that multi-element sequence processing is an important component of fluency. We used confirmatory factor analyses with serial and discrete naming tasks with matched items, including digits, dice, objects, number words, and words, performed by about 100 Greek children in each of Grades 1, 3, and 5. Separable serial and discrete factors emerged across grades, consistent with distinct skill dimensions. Loadings were greater for serial than discrete, suggesting that discrete processing does not fully determine serial processing. Average serial performance differed more than discrete between grades, consistent with improvement beyond single-item speed. Serial word reading aligned increasingly with the serial factor at higher grades. Thus, word reading fluency is gradually dominated by skill in simultaneously processing multiple successive items through different stages (termed “cascading”), beyond automatization of individual words. 相似文献
5.
Brian Hanley Catherine B. Tucker Athanassios Bissas 《Journal of sports sciences》2018,36(11):1250-1255
Race walking is an event where the knee must be straightened from first contact with the ground until midstance. The aim of this study was to compare knee angle measurements between 2D videography and 3D optoelectronic systems. Passive retroreflective markers were placed on the right leg of 12 race walkers and 3D marker coordinate data captured (250 Hz), with 2D video data (100 Hz) recorded simultaneously. Knee angle data were first derived based on the markers’ coordinates, and separately by using a 3D model that also incorporated thigh and shank clusters; the video data were analysed using both automatic tracking and manual digitising, creating four conditions overall. Differences were calculated between conditions for stance (using root mean square values), and at discrete events. There were few differences between systems, although the 3D model produced larger angles at midstance than using automatic tracking and marker coordinates (by 3 – 6°, P < 0.05). These differences might have occurred because of how the 3D model locates the hip joint, and because of the addition of marker clusters. 2D videography gave similar results to the 3D model when using manual digitising, as it allowed for errors caused by skin movement to be corrected. 相似文献
6.
Abstract The aim of this study was to analyse lower limb joint moments, powers and electromyography patterns in elite race walking. Twenty international male and female race walkers performed at their competitive pace in a laboratory setting. The collection of ground reaction forces (1000 Hz) was synchronised with two-dimensional high-speed videography (100 Hz) and electromyography of seven lower limb muscles (1000 Hz). As well as measuring key performance variables such as speed and stride length, normalised joint moments and powers were calculated. The rule in race walking which requires the knee to be extended from initial contact to midstance effectively made the knee redundant during stance with regard to energy generation. Instead, the leg functioned as a rigid lever which affected the role of the hip and ankle joints. The main contributors to energy generation were the hip extensors during late swing and early stance, and the ankle plantarflexors during late stance. The restricted functioning of the knee during stance meant that the importance of the swing leg in contributing to forward momentum was increased. The knee flexors underwent a phase of great energy absorption during the swing phase and this could increase the risk of injury to the hamstring muscles. 相似文献
7.
Giorgios P Paradisis Athanassios Bissas Panagiotis Pappas Elias Zacharogiannis Apostolos Theodorou Olivier Girard 《Journal of sports sciences》2013,31(17):2026-2036
ABSTRACTAs the effect of performance level on sprinting mechanics has not been fully studied, we examined mechanical differences at maximal running speed (MRS) over a straight-line 35 m sprint amongst sprinters of different performance levels. Fifty male track and field sprinters, divided in Slow, Medium and Fast groups (MRS: 7.67 ± 0.27 m?s?1, 8.44 ± 0.22 m?s?1, and 9.37 ± 0.41 m?s?1, respectively) were tested. A high-speed camera (250 Hz) recorded a full stride in the sagittal plane at 30–35 m. MRS was higher (p < 0.05) in Fast vs. Medium (+11.0%) and Slow (+22.1%) as well as in Medium vs. Slow (+10.0%). Twelve, eight and seven out of 21 variables significantly distinguished Fast from Slow, Fast from Medium and Medium from Slow sprinters, respectively. Propulsive phase was signi?cantly shorter in Fast vs. Medium (?17.5%) and Slow (?29.4%) as well as in Medium vs. Slow (?14.4%). Fast sprinters had significantly higher vertical and leg stiffness values than Medium (+44.1% and +18.1%, respectively) and Slow (+25.4% and +22.0%, respectively). MRS at 30–35 m increased with performance level during a 35-m sprint and was achieved through shorter contact time, longer step length, faster step rate, and higher vertical and leg stiffness. 相似文献
8.
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
9.
There is a substantial amount of public concern about patient safety, as, according to estimates from major studies, hundreds of thousands die in hospitals each year all over the developed world as a result of medical errors that could have been prevented. Unprecedented research commissioned by the EU has found that almost one out of every four families has experienced a serious medical error. Greek citizens concerning about serious medical errors in the hospital environment, were at the top of the list. Greek Ombudsman's report on medical errors has raised the debate among health policy makers as to the appropriate response to the problem. Proposals range from the implementation of nationwide mandatory reporting with public release of performance data, to voluntary reporting and quality-assurance efforts that protect the confidentiality of error-related data. Any successful safety program will first require a national effort to make significant investments in information systems, along with providing an environment and education that enables to contribute to an active quality improvement process. In this paper we propose the development and implementation of Medical Error Reporting Information System (MERIS), in order to identify, collect, analyse and report medical errors and patient adverse events, as a tool for enhancing patient safety and health care quality. We also describe the necessary organisational structure and the infrastructure environment of the system and the barriers to its successful implementation. 相似文献
10.
The aim of this study was to analyse lower limb work patterns in world-class race walkers. Seventeen male and female athletes race walked at competitive pace. Ground reaction forces (1000 Hz) and high-speed videos (100 Hz) were recorded and normalised joint moments, work and power, stride length, stride frequency and speed estimated. The hip flexors and extensors were the main generators of energy (24.5 J (±6.9) and 40.3 J (±8.3), respectively), with the ankle plantarflexors (16.3 J (±4.3)) contributing to the energy generated during late stance. The knee generated little energy but performed considerable negative work during swing (?49.1 J (±8.7)); the energy absorbed by the knee extensors was associated with smaller changes in velocity during stance (r = .783, P < .001), as was the energy generated by the hip flexors (r = ?.689, P = .002). The knee flexors did most negative work (?38.6 J (±5.8)) and the frequent injuries to the hamstrings are probably due to this considerable negative work. Coaches should note the important contributions of the hip and ankle muscles to energy generation and the need to develop knee flexor strength in reducing the risk of injury. 相似文献