323,498 research outputs found
Free space optical system performance for a Gaussian beam propagating through non Kolmogorov weak turbulence
No full textAtmospheric turbulence has been described for many years by Kolmogorov's power spectral density model because of its simplicity. Unfortunately several experiments have been reported recently that show Kolmogorov theory is sometimes incomplete to describe atmospheric statistics properly, in particular in portions of the troposphere and stratosphere. It is known that free space laser system performance is limited by atmospheric turbulence. In this paper we use a non-Kolmogorov power spectrum which uses a generalized exponent instead of constant standard exponent value 11/3 and a generalized amplitude factor instead of constant value 0.033. Using this spectrum in weak turbulence, we carry out, for a Gaussian beam propagating along a horizontal path, analysis of long term beam spread, scintillation, probability of fade, mean signal to noise ratio and mean bit error rate as variation of the spectrum exponent. Our theoretical results show that for alpha values lower than 11/3 , but not for alpha close to 3 , there is a remarkable increase of scintillation and consequently a major penalty on the system performance. However when alpha assumes values close to 3 or for alpha values higher than 11/3 scintillation decreases leading to an improvement on the system performanc
Body composition and physical health in sports practice: An editorial
No full text: The assessment of the health status of athletes, at all ages, is an aspect of fundamental importance, and, in recent years, the analysis of body composition has become a fundamental and essential part in its evaluation, such as in the optimization of sports performance [...]
Nutritional status and quality of life in a sample of immigrants. A research program.
No full textThe paper provides an overview of a national research program to identify the health, nutritional status and quality of life in the immigrant population.
This report analizes the main anthropological aspects of the program concerning the assessment of anthropometric and psychosocial characteristics of the immigrant population, as well as this group's nutritional habits
Psychosocial indicators and distress in immigrants living in Italian reception centres.
No full textDespite the high rate of migration to Italy, there are still no comprehensive studies of psychosocial
distress in the different groups of immigrants. The objective of the present study was to
investigate the psychosocial status of immigrants living in Bologna (Italy). We conducted a crosssectional
survey of 396 immigrants (313 males and 83 females) from Africa, Asia and eastern
Europe (Senegalese, Moroccans, Tunisians, Pakistanis, Kosovars and Roma) using questionnaires
administered by trained anthropologists. Except for Tunisians, the psychological distress and
discomfort of the immigrant groups are low, and the perception of their quality of life and wellbeing
is good. In the groups that have spent more time in Italy, the percentage of subjects wishing
to return to their native country is generally higher. Immigrants living in Bologna exhibit a good
psychosocial state and seem to have positively interacted with their new environment
Anthropometric characteristics and physical performance in a sample of Italian children, 11-14 years old.
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The physical structure of basketball players: Comparison between young and adult athletes
No full textThe aims of the present study were to investigate if the physical characteristics of adult basketball players are already present in teenage players, and to identify the anthropometric features that characterize the different playing positions. The sample consists of 40 teenage athletes and 40 adult athletes playing in the same basketball league and on teams occupying the same position in the standings. By analyzing and comparing subjects grouped by age and playing position, it was possible to identify characters present at a young age and also in adulthood, as well as those present in one sample but not in the other. This allowed us to establish the reliability of a character as a predictor of a certain playing position. In the young athletes, the centers have larger dimensions than the other three positions. The differences among the latter are smaller, although the forwards have a longer-limbed structure than the guards and better memorization and associative abilities than the playmakers. In the adults, the playmakers have the smallest dimensions while the centers have the largest ones. The values of the forwards and guards are intermediate, although the former are taller and have a wider pelvis. In adulthood, there seems to be a closer relationship between the physical characteristics and the playing position. This could be due to the fact that the developing body structure determines a choice of position most suitable to the player's physical characteristics. On the other hand, the body structure is also influenced by the requirements of the position
Valutazione della composizione corporea mediante MBIA: osservazioni metodologiche sulla variabilità della misura d’impedenza. Nota preliminare.
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Participation in sports, body composition, and fitness characteristics in children according to ethnic background
No full textParticipation in sports has important implications, being associated with health and social features. The objectives of this study were to verify whether there were any differences in sport participation between immigrant and Italian children and whether there was any relation with their body composition and fitness characteristics. A survey was conducted on 1432 children attending primary school in the Emilia-Romagna (northern Italy). Anthropometric measurements, fitness characteristics, and data about participation in sports were considered. Italian children were more likely to participate in sports than immigrants and boys than girls. Among immigrants, the lowest values were observed in Asians. Eastern European males and Latin American females displayed the widest dimensions. Eastern Europeans generally showed the highest values of strength, while Latin Americans had the highest values of flexibility. Asian children showed the highest values of centripetal fat, and a high percentage of them exceeded the %F reference. These aspects, together with the low frequency of practicing sports, place Asians at greater risks for health. Sex and ethnic group are the most informative variables associated with participation in sports by children. Interventions including health education lessons and promoting the participation in sports for immigrant children attending schools need to be encouraged
Bioimpedance vector analysis of elite, subelite, and low-level male volleyball players
No full textPurpose: To establish a specific player profile on body-composition parameters and to provide a data set of bioelectric impedances values for male volleyball players. Methods: The study included 201 athletes (age 26.1 [5.4] y, height 191.9 [9.7] cm, weight 86.8 [10.8] kg) registered in the Italian volleyball divisions. The athletes were divided into 3 groups: The elite group comprised 75 players participating in the 1st (Super Lega) division, the subelite group included 65 athletes performing in the 2nd (Serie A2) division, and the low-level group included 61 players participating in the 3rd (Serie B) division. Bioelectric impedance, body weight, and height of the athletes were measured in the second half of the competitive season. In addition, bioelectrical impedance vector analysis was performed. Results: The elite group showed a greater amount of fat-free mass (FFM) and total body water (TBW) and a lower fat mass (FM) than the subelite group (P < .05). In addition, the elite players were taller and heavier and had a higher FFM, FM, TBW, and body cellular mass than the low-level athletes (P < .05). Finally, the mean impedance vectors of the elite group significantly differed from those measured in the normal population and in the other 2 groups (P < .05). Conclusions: This study provides an original data set of body-composition and bioelectric impedance reference values of elite male volleyball players. The results might be useful for interpretation of individual bioimpedance vectors and for defining target regions for volleyball players
Anthropometry and functional movement patterns in elite Male volleyball players of different competitive levels
No full textThe aim of this study was to establish specific profiles for anthropometry and functional movement parameters and identify which characteristics can be modified by training to achieve a better quality of movement in elite male volleyball players competing at the Italian National League (Super Lega = 39, aged 25.6 6 4.7 years and A2 = 30, aged 26.2 6 5.3 years). Another aim was to value functional movement patterns in relation to morphological traits, with special focus on differences by division and playing positions. Statistical significance was set at p # 0.05. According to discriminant analysis, the differences between players of the 2 Divisions were primarily due to nonmodifiable parameters (humerus width, height, and bicrestiliac width) and modifiable parameters (contracted arm circumference and muscle area of upper arm). Our results highlighted differences according to playing positions. Middle hitters and opposites were taller, heavier and generally showed wide dimensions in contracted arm circumference, upper limb length widths, and handgrip strength than the players of the other roles. Percentage of fat mass was low in players of all roles, such as endomorph somatotype component. Ectomor-phic component was maximal in middle hitters, whereas mesomorphic component was maximal in liberos. The players of the 2 Divisions did not show differences in the movement patterns, even if approximately 33% of them showed a dysfunctional movement, with a prevalence of asymmetric movements in the shoulder mobility test. Multiple regression showed that, in volleyball players, an optimal flexibility and mobility was closely related to anthropometric characters with particular emphasis on body fat
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