1,721,015 research outputs found
Reliability and validity of field-based fitness tests in youth soccer players
Full text linkThis study aimed to establish between-day reliability and validity of commonly used field-based fitness tests in youth soccer players of varied age and playing standards, and to discriminate between players without (“unidentified”) or with (“identified”) a direct route to professional football through their existing club pathway. Three-hundred-and-seventy-three Scottish youth soccer players (U11–U17) from three different playing standards (amateur, development, performance) completed a battery of commonly used generic field-based fitness tests (grip dynamometry, standing broad jump, countermovement vertical jump, 505 (505COD) and T-Drill (T-Test) change of direction and 10/20 m sprint tests) on two separate occasions within 7–14 days. The majority of field-based fitness tests selected within this study proved to be reliable measures of physical performance (ICC = 0.83–0.97; p less than .01). However, COD tests showed weaker reliability in younger participants (ICC = 0.57–0.79; p less than .01). The field-based fitness testing battery significantly discriminated between the unidentified and identified players; χ2 (7) = 101.646, p less than .001, with 70.2% of players being correctly classified. We have shown field-based fitness tests to be reliable measures of physical performance in youth soccer players. However, results from the 505COD and T-Test change of direction tests may be more variable in younger players, potentially due to complex demands of these tests and the limited training age established by these players. While the testing battery selected in this study was able to discriminate between unidentified and identified players, findings were inconsistent when attempting to differentiate between individual playing standards within the “identified” player group (development vs. performance)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Sarcopenia, mobility, and 24h movement behaviours in South African and Scottish older adults across different socioeconomic settings
Full text linkMobility relates to the basic human need of physical movement which declines with advancing age. Strong evidence of successful ageing can be found in mobility performance (walking, muscle strength, and physical functioning) evaluation. Previous evidence indicates that physical activity could prevent progression of mobility limitation and promote successful ageing. As such, the overall aim of this thesis is to determine effects of 24-h movement behaviours (physical activity, sedentary behaviour, and sleep) on musculoskeletal health, adiposity, and physical functioning in older adults. Chapter 1 reviews the evidence for these outcomes of interest. Subsequently, chapter 2 reports on changes in walking behaviour with increasing age in high-functioning older adults living in Scotland. However, individual intrinsic capacity is only one of the components of functional mobility and laboratory-based gait analysis can only provide a limited picture. Accordingly, in chapters 3-5, laboratory-based measurements of mobility have been translated into the real world by considering movement within the whole 24-h time period in older adult populations living in Scotland (high-income setting) and South African Townships (low-income setting). Chapter 3 describes compositional time differences in 24-h movement behaviour between Scottish and South African older adults. Chapters 4 and 5 investigates associations between 24-h movement behaviours, musculoskeletal health, adiposity, and physical functioning. Higher volumes of moderate- to vigorous-intensity physical activity were associated with better health outcomes in both samples, while sedentary behaviour presented a detrimental effect on other variables. However, differences in health outcomes associations were present between the Scottish and South African settings. The findings reported in this thesis demonstrates the importance of exploring 24-h movement behaviours in older adults from differing settings, to gain greater understanding of context and socioeconomic profiles, and how these link to health outcomes so that there is an understanding of how best to intervene
Neuromuscular Characteristics of Multiple Sclerosis Patients
Full text linkAim: The aim of this study was to describe the neuromuscular characteristics of Multiple Sclerosis (MS) patients. To help explain the neuromuscular characteristics physical activity levels, body composition and blood lipid profile were measured. In addition, Vitamin D was measured to determine if this was deficient in MS patients.
Hypothesis: We hypothesised that muscle fibre conduction velocity (MFCV) would be elevated and amplitude would be impaired in Multiple Sclerosis patients compared to an age and sex matched control group. In addition, we hypothesised that physical activity levels would be reduced, body composition would exhibit a higher percentage fat, blood lipid profile would be less favourable and Vitamin D levels would be reduced in the group of MS patients.
Methodology: 15 MS patients (53.8±10.5 years) and 14 age and sex matched control participants (54.6±9.6 years) were recruited for this study. Patients with a disability status (EDSS) (92) of between 4 and 6 were included in this study. All participants provided written informed consent after being fully informed of the procedures.
An array of 4, 8mm Ag-AgCl electrodes was placed in a hard plastic mould in a straight line, leaving 12.5mm between each electrode. The array was positioned on the vastus lateralis between the innervation zone and the distal tendon and was orientated to follow the muscle fibre pennation direction. Electromyographic (EMG) data was collected via the electrodes whilst the participant carried out each contraction. Muscle fibre conduction velocity (MFCV) and root mean square (RMS) were calculated from the raw EMG signal collected during each contraction.
The protocol was carried out on both legs. Isometric knee extensions were standardised using the Bio-Dex Systems 3 Isokinetic Dynamometer and executed with the knee at 60° angle of flexion. Participants were tested under four different contraction intensities; 20, 40, 60 and 80% of the peak value of their maximum voluntary contraction (MVC). Their MVC was established for both legs. For each test condition the participant was required to carry out 3 isometric contractions for 7 seconds; each contraction was separated by 14 seconds rest. During each set of contractions the target force was visible on the Bio-Dex monitor. Participants obtained visual feedback from the Bio-Dex throughout each contraction allowing the participant to adjust the force they were required to produce to maintain their target force.
Whole body composition (fat mass, lean mass and bone mineral content) was measured by Dual-energy X-ray Absorptiometry (DEXA) using a Lunar Prodigy DF+ 13643, GE medical systems scanner. Whole body and thigh composition were extrapolated from the digitalised results of the scan.
Habitual physical activity was measured for 7 days using the GT1M Actigraph accelerometer, which was worn on the participants’ right hip during all waking hours. Data collected by and downloaded from the accelerometer was used to calculate each participant’s total and mean accelerometer counts per day.
A fasted 10ml sample of venous blood was drawn from an antecubital vein using a 10ml syringe and a 15mm gauge needle. The blood samples were analysed for total cholesterol, triglyceride and high density lipoproteins (HDL), low density lipoprotein (LDL) and Vitamin D concentration.
Results: Initial findings revealed that the patient group exhibited a significantly faster (P0.05) in MFCV over all the contractions between the groups. There was no significant difference (P>0.05) in MFCV between the dominant and non-dominant leg within each group.
Analysis of the RMS data revealed that there was no significant difference (P>0.05) over all the contractions between the patient and the control group in either the dominant or the non-dominant leg. However there was a highly significant difference (P<0.001) in RMS between contraction intensity in both legs in both groups.
There was a significant difference (P0.05) was identified between the dominant and non-dominant leg within each group.
There was no significant difference (P>0.05) in absolute lean thigh mass (LTM) between the two groups however the difference in relative lean thigh mass (lean thigh mass/lean body mass*100) between the groups was approaching significance (P=0.077).
The patient group exhibited a significantly (P0.05) in whole body or thigh bone mineral density (BMD) between the groups.
The patient group was significantly (P<0.05) less physically active than the control group; this was evident from their total accelerometer counts/day (patients 167088±113586, control 316401±108982) and mean accelerometer counts/day (patients 206.4±139.5, controls 364.5±120.6).
There was no significant difference (P>0.05) in blood lipid profile (cholesterol, triglycerides, HDL or LDL) between patients and control group. However there was a significant difference (P<0.05) in serum Vitamin D concentration between the patient and the control group.
Conclusion: MS patients exhibited faster MFCV with a similar number of motor units recruited than healthy ages and sex matched controls. However, an increased quantity of subcutaneous fat artificially elevates MFCV (110) and MS patients in this study exhibit higher percentage fat than the controls. Therefore, when accounting for this confounding variable we then showed that there was in fact no difference in MFCV between the groups. However the patients MFCV responded differently to the increased contraction intensity than the controls which suggests altered neuromuscular processing within the patient group.
The MS group had reduced physical activity levels which caused a slight disuse atrophy of the lower limbs which did not compromise muscle quality. Therefore, similar quality of the muscle has resulted in unaltered neuromuscular recruitment in MS patients.
Overall, the results indicate that there was no difference in neuromuscular characteristics of MS patients compared to age and sex matched controls, even in the presence of altered body composition and physical activity levels
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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