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41.
Tiago Roux Oliveira Alessandro Jacoud Peixoto Liu Hsu 《Journal of The Franklin Institute》2012,349(4):1397-1415
This paper addresses the design of a sliding mode based extremum-seeking controller for a class of single-input–single-output (SISO) uncertain nonlinear systems with unmatched and state-dependent strong nonlinearities. We demonstrate that it is possible to achieve an arbitrarily small neighborhood of the desired optimal point using only output-feedback. The key idea is the combination of a periodic switching function with a norm state observer. As an important advantage, we show that the proposed scheme achieves extremum-seeking for all initial conditions, i.e., the real-time optimization algorithm has global convergence properties. An application to a simple nonderivative optimizer illustrates the viability of the proposed approach. 相似文献
42.
Elisabetta Conte Ilaria Grazzani Alessandro Pepe 《Early education and development》2018,29(6):814-830
Research Findings: In this study, we investigated associations among social cognition skills (specifically, emotion knowledge and theory of mind), language abilities, and 3 varieties of prosocial behavior (helping, sharing, and comforting) in early childhood. The effects of age and gender were also taken into account. Participants were 149 Italian children between 24 and 47 months of age (M = 35.6 months, SD = 6.77 months). We adopted a multitrait mixed-methods research design, using direct measures of emotion knowledge, theory of mind, and language as well as naturalistic observations of children’s free play with peers to detect the frequency with which they engaged in prosocial behaviors. Ordinal logistic regression analyses showed that helping behaviors were especially accounted for by emotion knowledge and gender, whereas variance in sharing behaviors was mostly explained by theory-of-mind ability and language. Practice or Policy: The findings encourage those involved in early childhood education to develop training and intervention programs to enhance children’s emotional, linguistic, and cognitive skills. Given that these results were obtained with children as young as 2 and 3 years, preventive intervention should be implemented during the earliest years of life. 相似文献
43.
Alessandro Fornasiero Aldo Savoldelli Damiano Fruet Gennaro Boccia Barbara Pellegrini Federico Schena 《Journal of sports sciences》2018,36(11):1287-1295
The aims of the study were to describe the physiological profile of a 65-km (4000-m cumulative elevation gain) running mountain ultra-marathon (MUM) and to identify predictors of MUM performance. Twenty-three amateur trail-runners performed anthropometric evaluations and an uphill graded exercise test (GXT) for VO2max, ventilatory thresholds (VTs), power outputs (PMax, PVTs) and heart rate response (HRmax, HR@VTs). Heart rate (HR) was monitored during the race and intensity was expressed as: Zone I (VT2) for exercise load calculation (training impulse, TRIMP). Mean race intensity was 77.1%±4.4% of HRmax distributed as: 85.7%±19.4% Zone I, 13.9%±18.6% Zone II, 0.4%±0.9% Zone III. Exercise load was 766±110 TRIMP units. Race time (11.8±1.6h) was negatively correlated with VO2max (r = ?0.66, P <0.001) and PMax (r = ?0.73, P <0.001), resulting these variables determinant in predicting MUM performance, whereas exercise thresholds did not improve performance prediction. Laboratory variables explained only 59% of race time variance, underlining the multi-factorial character of MUM performance. Our results support the idea that VT1 represents a boundary of tolerable intensity in this kind of events, where exercise load is extremely high. This information can be helpful in identifying optimal pacing strategies to complete such extremely demanding MUMs. 相似文献
44.
Alessandro Moura Zagatto Miran Kondric Beat Knechtle Pantelis Theo Nikolaidis Billy Sperlich 《Journal of sports sciences》2018,36(7):724-731
Table tennis is a racket sport characterised by an intermittent movement profile, including short rallies interspersed with short breaks. In contrast to other racket sports, information is lacking regarding the: (i) physiological responses during table tennis matches and training; and (ii) practical recommendations for enhancing aerobic and anaerobic performance in table tennis by improving cardio-metabolic and neuro-muscular fitness, anthropometry and nutritional strategies. Therefore, this review article attempts to narratively provide an overview of the physiology of table tennis by describing the metabolic mechanisms underlying match play and outlining a framework for practical recommendations for improving cardio-metabolic and neuro-muscular fitness, anthropometry as well as nutritional strategies. A second aim was to stimulate future research on table tennis and to point out study limitations in this context. In general, the most important finding is that the rally duration is short at around 3.5s, with a longer rest time of around 8–20s, resulting in an effort-rest ratio ranging from 0.15 to 0.22 in official matches and energetic demands during match relatively low. Future studies should focus on the relationship between energetic demand and table tennis performance with a view to predicting performance in table tennis using physiological parameters. 相似文献
45.
Higher education (HE) systems around the world have experienced profound structural changes, particularly since the late 1960s to early 1970s, essentially driven by the need to expand access to tertiary education. This has resulted in a diversity of HE institutions (HEI) with different roles, missions and statuses, as well as academic staff with diverse perspectives and motivations. The present study is based on a survey undertaken in Portugal by a trade union, which aimed to collect faculty perspectives on a proposed HE reform sent out for public discussion by the government. Questions addressed the reorganization of the HEI network, the internal restructuring of HEI, the funding system and the binary divide of HEI (universities and polytechnics). The survey results showed a disparity of faculty perspectives about the proposed reform, closely related to the diversity of HEI. Respondents from lower academic categories and from smaller HEI were more opposed to reorganizing the HEI network. This reorganization was more widely accepted by university staff, who were also more in favour of a binary system than were polytechnic respondents. Although there was general agreement about the need to change the funding system, polytechnic respondents were strongly against a funding differentiation between universities and polytechnics. Despite an overall reformist trend, the enthusiasm for reforms declined substantially when the questions had a direct reference to the respondent’s region or institution. It is argued that HE expansion has driven the diversification of HEI, leading to a range of perspectives about the HE system and the way it should be changed. These conclusions may contribute to insights into other HE systems around the world where institutional diversification has been sought by public policies. 相似文献
46.
Although Venice is regarded as being one of the most important centres of glass manufacture and trade in Western Europe, little is known about the origins of the Venetian glassmaking. Some archaeologists suggest there is a continuity in the history of glass making, in its transplantation from the Roman centres of the mainland (Altino and Aquileia), first to some islands of the lagoon, and later to the town. Some others, instead, think that there was no continuity at all and that the art of glassmaking was imported in Venice from the Islamic glass factories of the Middle East. Of great help in answering this and other technological questions is the information about the composition of ancient glass from well-dated excavations that allows to conclude on the early technology, sources of raw materials and long-distance trade. Some significant glass findings, including fragments of pots used for glass melting, were found on the island of Torcello and, more recently, in two emergency excavations in the historic centre of Venice. In this paper, the chemical composition of a large set of glass findings (and related materials) from the Venetian lagoon dating from the 7th to the 13th centuries is determined by X-ray microanalysis in order to throw new light on the glassmaking technology in the early centuries of the Venetian tradition. The results show that in this period there occurred a gradual transition from the Roman technique (a two-ingredient formulation with silica-lime sand and natron as a fluxer), towards the use of silica sand and soda plant ash. There is evidence, therefore, for a production continuity with the Roman period (melting pots and glass scraps with a natron-based composition), yet restricted to transparent blown items. No evidence was found for a local production of glass tesserae for the mosaics of the church of St. Maria Assunta in Torcello. 相似文献
47.
Domenico Meleleo Nicola Bartolomeo Liliana Cassano Alessandro Nitti Giovanna Susca Giuseppina Mastrototaro 《European Journal of Sport Science》2017,17(6):710-719
Purpose: Conventional Bioelectrical Impedance Analysis (BIA) or Bioelectrical Impedance Vector Analysis (BIVA) can provide direct evaluations of body composition. The purpose of this study was to evaluate lean and fat mass (FM), and hydration of children involved in daily competitive sports. Methods: 190 non-athletic [8.2–10.5 years] and 29 competitive children [8.0–10.5 years] were enrolled. They were evaluated: at baseline (t0), 6 months (t1) and one year (t2). Anthropometric, BIA and BIVA, lean and FM, and hydration evaluations were performed. Results: Resistance (R/h) and reactance (Xc/h) were lower at t0 in competitive individuals when compared to controls. Xc/h (+3.28) significantly increases in competitive when compared to non-competitive individuals (+0.66, p for difference: 0.011), while phase angle (PA) was lower at t0 (5.72 vs. 6.17, p?<?.001) and after 6 months (p?=?.001). Total body water adjusted for height (TBW/h) significantly increased only in non-athletes (+0.50?±?0.13, p?<?.001) between t0 and t1. At t1, extracellular water (ECW) significantly decreased (p?=?.026) in the two groups: ?0.45?±?0.19% in non-competitive, ?1.63?±?0.49% in competitive subjects, while intracellular water (ICW) increased. At one-year follow-up (t2), there were no statistically significant differences in R/h, Xc/h and PA in competitive individuals when compared to baseline and t1. Furthermore, we observed at t2 that hours/week of training, age, male gender and body mass index can influence FFM/h and FM/h in both competitive and non-competitive subjects. In particular, a direct correlation was for hours/week and FFM/h, inverse for hours/week and FM/h. Conclusions: Body mass index does not allow evaluating differences in lean body mass and FM between athletes and non-athletes. BIA and BIVA can give more reliable details about body composition differences in competitive adolescents and non-competitive, outlining a progressive decline in ECW and increase in ICW without affecting TBW composition of athletes. 相似文献
48.
Alessandro M. Zagatto Fabio Y. Nakamura Fabio Milioni Willian E. Miyagi Rodrigo A. B. de Poli Johnny Padulo 《Journal of sports sciences》2017,35(24):2453-2460
The purpose of the study was to investigate the sensitivity of an alternative maximal accumulated oxygen deficit (MAODALT) method to discriminate the “anaerobic” capacity while comparing: least trained (LT) participants (n = 12), moderately trained (MT) participants (n = 12), endurance trained (ET) participants (n = 16), and rugby (RG) players (n = 11). Participants underwent a graded exercise test on a treadmill and a supramaximal effort for assessing MAODALT. MAODALT was calculated as the sum of oxygen equivalents from the phosphagen and glycolytic metabolic pathways. MAODALT was significantly higher (P < 0.05) in RG (64.4 ± 12.1 mL · kg?1) than in ET (56.8 ± 5.4 mL · kg?1; effect size [ES] = 0.77; +13.5%), MT (53.8 ± 5.3 mL · kg?1; ES = 1.08; +19.8%), and LT (49.9 ± 4.5 mL · kg?1; ES = 1.50; +36.4%). In addition, the magnitude-based inference analysis revealed that MAODALT was likely (LT vs. MT), very likely (MT vs. RG, and ET vs. RG) and most likely (LT vs. ET, and LT vs. RG) different between all groups, except for MT and ET, which presented an unclear difference. In conclusion, MAODALT was sensitive enough to distinguish the “anaerobic” capacity in individuals with different training status, especially for RG players compared with LT participants and MT participants. 相似文献
49.
Claudio Di Lorito Annabelle Long Adrian Byrne Rowan H.Harwood John R.F.Gladman Stefan Schneider Pip Logan Alessandro Bosco Veronika van der Wardt 《运动与健康科学(英文)》2021,10(1):29-47
Background:The evidence concerning which physical exercise characteristics are most effective for older adults is fragmented.We aimed to characterize the extent of this diversity and inconsistency and identify future directions for research by undertaking a systematic review of metaanalyses of exercise interventions in older adults.Methods:We searched the Cochrane Database of Systematic Reviews,PsycInfo,MEDLINE,Embase,CINAHL,AMED,SPORTDiscus,and Web of Science for articles that met the following criteria:(1)meta-analyses that synthesized measures of improvement(e.g.,effect sizes)on any outcome identified in studies of exercise interventions;(2)participants in the studies meta-analyzed were adults aged 65+or had a mean age of 70+;(3)meta-analyses that included studies of any type of exercise,including its duration,frequency,intensity,and mode of delivery;(4)interventions that included multiple components(e.g.,exercise and cognitive stimulation),with effect sizes that were computed separately for the exercise component;and(5)meta-analyses that were published in any year or language.The characteristics of the reviews,of the interventions,and of the parameters improved through exercise were reported through narrative synthesis.Identification of the interventions linked to the largest improvements was carried out by identifying the highest values for improvement recorded across the reviews.The study included 56 meta-analyses that were heterogeneous in relation to population,sample size,settings,outcomes,and intervention characteristics.Results:The largest effect sizes for improvement were found for resistance training,meditative movement interventions,and exercise-based active videogames.Conclusion:The review identified important gaps in research,including a lack of studies investigating the benefits of group interventions,the characteristics of professionals delivering the interventions associated with better outcomes,and the impact of motivational strategies and of significant others(e.g.,carers)on intervention delivery and outcomes. 相似文献
50.
The review looks at the recent review of children's television broadcasting by the governmental regulator in the UK, Ofcom. It suggests that the research represents a valuable addition to the policy literature by filling the gap in previous research, particularly by providing an in-depth analysis of the economics of the sector. However, it questions the direct impact of the report on the subject matter if it is integrated (as proposed) into the more general review of Public Service Broadcasting. 相似文献