The kinematic differences between accurate and inaccurate squash forehand drives for athletes of different skill levels     

Benjamin K. Williams  Ross H. Sanders  Joong Hyun Ryu  Philip Graham-Smith  Peter J. Sinclair 《Journal of sports sciences》2020,38(10):1115-1123

ABSTRACT

To maintain the accuracy of squash shots under varying conditions, such as the oncoming ball’s velocity and trajectory, players must adjust their technique. Although differences in technique between skilled and less-skilled players have been studied, it is not yet understood how players vary their technique in a functional manner to maintain accuracy under varying conditions. This study compared 3-dimensional joint and racket kinematics and their variability between accurate and inaccurate squash forehand drives of 9 highly skilled and 9 less-skilled male athletes. During inaccurate shots, less-skilled players hit the ball with a more open racket, demonstrating a difference in this task-relevant parameter. No joint kinematic differences were found for accuracy for either group. Coordinated joint rotations at the elbow and wrist both displayed a “zeroing-in” effect, whereby movement variability was reduced from the initiation of propulsive joint rotation to a higher consistency at ball-impact; potentially highlighting the “functionality” of the variability prior to the impact that enabled consistent task-relevant parameters (racket orientation and velocity) under varying conditions. Further, highly skilled players demonstrated greater consistency of task-relevant parameters at impact than less-skilled players. These findings highlight the superior ability of highly skilled players to adjust their technique to achieve consistent task-relevant parameters and a successful shot.  相似文献   

Effects of purposeful soccer heading on circulating small extracellular vesicle concentration and cargo     

Eric R. Muoz  Jaclyn B. Caccese  Brittany E. Wilson  Kyle T. Shuler  Fernando V. Santos  Carolina T. Cabn  John J. Jeka  Dianne Langford  Matthew B. Hudson 《运动与健康科学(英文)》2021,10(2):122

BackgroundConsidering the potential cumulative effects of repetitive head impact (HI) exposure, we need sensitive biomarkers to track short- and long-term effects. Circulating small extracellular vesicles (sEVs) (<200 nm) traffic biological molecules throughout the body and may have diagnostic value as biomarkers for disease. The purpose of this study was to identify the microRNA (miRNA) profile in circulating sEVs derived from human plasma following repetitive HI exposure.MethodsHealthy adult (aged 18–35 years) soccer players were randomly assigned to one of 3 groups: the HI group performed 10 standing headers, the leg impact group performed 10 soccer ball trapping maneuvers over 10 min, and the control group did not participate in any soccer drills. Plasma was collected before testing and 24 h afterward, and sEVs were isolated and characterized via nanoparticle tracking analysis. Next-generation sequencing was utilized to identify candidate miRNAs isolated from sEVs, and candidate microRNAs were analyzed via quantitative polymerase chain reaction. In silico target prediction was performed using TargetScan (Version 7.0; targetscan.org) and miRWalk (http://mirwalk.umm.uni-heidelberg.de/) programs, and target validation was performed using luciferase reporter vectors with a miR-7844-5p mimic in human embryonic kidney (HEK) 293T/17 cells.ResultsPlasma sEV concentration and size were not affected across time and group following repetitive HI exposure. After 24 h, the HI read count from next-generation sequencing showed a 4-fold or greater increase in miR-92b-5p, miR-423-5p, and miR-24-3p and a 3-fold or greater decrease in miR-7844-5p, miR-144-5p, miR-221-5p, and miR-22-3p. Analysis of quantitative polymerase chain reaction revealed that leg impact did not alter the candidate miRNA levels. To our knowledge, miR-7844-5p is a previously unknown miRNA. We identified 8 miR-7844-5p mRNA targets: protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B), LIM and senescent cell antigen-like domains 1 (LIMS1), autophagy-related 12 (ATG12), microtubule-associated protein 1 light chain 3 beta (MAP1LC3B), integrin subunit alpha-1 (ITGA1), mitogen-activated protein kinase 1 (MAPK1), glycogen synthase kinase 3β (GSK3β), and mitogen-activated protein kinase 8 (MAPK8).ConclusionCollectively, these data indicate repetitive HI exposure alters plasma sEV miRNA content, but not sEV size or number. Furthermore, for the first time we demonstrate that previously unknown miR-7844-5p targets mRNAs known to be involved in mitochondrial apoptosis, autophagy regulation, mood disorders, and neurodegenerative disease.  相似文献   

1982 FIFA World Cup: from Spain’s struggle for democratic legitimacy to Italy’s rediscovery of football nationalism     

Juan Antonio Simón 《Soccer & Society》2019,20(7-8):948-959

ABSTRACT

One of the most memorable moments in the World Cups history is Marco Tardelli’s second goal in Italy’s win over Germany in the 1982 World Cup finals. Better known as Tardelli’s scream, it is thus a perfect object to analyse in order to understand football’s deeper social meanings and its political and cultural undertones, in this case both for the World Cup champions, Italy, and for the host country, Spain. In the Spanish case, organizing the World Cup was a huge political opportunity for the just restored democracy to showcase to the world a modern and pluralistic society leaving behind the authoritarian and outdated dictatorship. As for Italy, their first World Cup winning since World War II was heavily politically used by actors across the political spectrum. Such nationalistic approach constituted a novelty after decades of a low profile national discourse.  相似文献   

Hypocalcemia in an 11 Year Old Child: <Emphasis Type="Italic">A Difficult Case to Treat</Emphasis>     

P. Purohit  D. Khera  K. Singh 《Indian journal of clinical biochemistry : IJCB》2018,33(4):489-490

Hypocalcemia is a laboratory and clinical abnormality that is observed especially in neonates and paediatric patients. Laboratory hypocalcaemia is often asymptomatic but it can manifest as central nervous system irritability, paraesthesia, tetany (i.e. contraction of hands, arms, feet, larynx, bronchioles), seizures, and even psychiatric changes in children. Cardiac function may also be impaired because of poor muscle contractility. We report a unique case of an eleven year old male child who presented with chronic kidney disease associated with severe hypocalcemia, tonic-clonic seizures, hypovitaminosis D but normal electroencephalogram and electrocardiography. The child required prolonged intravenous calcium gluconate therapy to correct his ionised calcium levels.  相似文献   

Quality flaw prediction in Spanish Wikipedia: A case of study with verifiability flaws     

Edgardo Ferretti  Leticia Cagnina  Viviana Paiz  Sebastián Delle Donne  Rodrigo Zacagnini  Marcelo Errecalde 《Information processing & management》2018,54(6):1169-1181

In this work, we present the first quality flaw prediction study for articles containing the two most frequent verifiability flaws in Spanish Wikipedia: articles which do not cite any references or sources at all (denominated Unreferenced) and articles that need additional citations for verification (so-called Refimprove). Based on the underlying characteristics of each flaw, different state-of-the-art approaches were evaluated. For articles not citing any references, a well-established rule-based approach was evaluated and interesting findings show that some of them suffer from Refimprove flaw instead. Likewise, for articles that need additional citations for verification, the well-known PU learning and one-class classification approaches were evaluated. Besides, new methods were compared and a new feature was also proposed to model this latter flaw. The results showed that new methods such as under-bagged decision trees with sum or majority voting rules, biased-SVM, and centroid-based balanced SVM, perform best in comparison with the ones previously published.  相似文献   

Roger A. Lohmann. (2016). Above the Bottom Line: Financial Management in Human Services. Washington,DC: NASW Press (322 pp., $46.00, paperback,ISBN# 978-0871014986)     

Karun K. Singh 《Journal of Teaching in Social Work》2018,38(2):238-240

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Effect of different loading conditions on running mechanics at different velocities     

Germán Carretero-Navarro  Doménico Cherubini  Wolfgang Taube 《European Journal of Sport Science》2019,19(5):595-602

Weighted vests are widely used to improve running economy and performance. However, it is not well-studied how running mechanics are adapted to counteract the higher peak vertical ground reaction forces (Fpeak) while running with such a device. Therefore, the present study aimed to investigate the effects of different loading conditions on running mechanics at different velocities. Thirteen subjects participated in two separate sessions one week apart. In the first session, maximal aerobic speed (MAS) was determined through a maximal incremental running test while in the second session, they were instructed to run during one minute under different loading (0%, +10% and +20% of body mass [BM]) and velocity (60%, 80% and 100% of MAS) conditions in a random order. Spatiotemporal data were recorded and then running mechanics modelled using the spring-mass model. The main results indicated that vertical and leg stiffness (Kvert and Kleg, respectively) were increased (P?P?>?.05) when load was changed. At the same time, alterations of the running kinematics were observed such as longer contact times, reduced flight times, stride frequencies and step lengths, as well as an increase of the centre of mass dynamics. Based on these results it is assumed that runners maintain a certain stiffness level for each velocity despite different loading conditions. As a consequence, Fpeak increases and this probably causes spatiotemporal adjustments in the movement kinematics.  相似文献   

Diverging discourses: Examining how college students majoring in communication define diversity     

Drew T. Ashby-King  Lisa K. Hanasono 《Qualitative Research Reports in Communication》2019,20(1):9-18

Colleges and universities in the United States often promote diversity through a neoliberal lens by framing diversity as a celebration of individual differences or a commodity that students can gain by attending their institution. In communication courses, diversity has been conceptualized through both neoliberal and critical lenses, but limited research has investigated how communication students define and explain diversity. The focus of this study was to understand how communication students define diversity. We performed thematic analyses on open-ended survey responses to investigate how communication students define diversity. Four themes emerged from our analyses: (a) diversity is a mechanism for unifying communities, (b) diversity is an affirmation of individual differences, (c) diversity is a harbinger of acceptance and equality, and (d) diversity is a disruptive force that re-centers the voices of traditionally marginalized people. Our findings indicate most communication students define diversity through a neoliberal lens. However, 3% of our participants conceptualized diversity through a critical lens by explaining that diversity should create space for those who are marginalized to have their voices heard. We conclude by providing recommendations for communication instructors to incorporate more critical conversations about diversity into their classrooms and foster diverging discourses about diversity across communication curricula.  相似文献   

Identifying a classic in history,philosophy, and social studies of science     

Luciano Boschiero  K. Brad Wray 《Metascience》2018,27(2):181-182

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The Socio-Cultural Image of Childhood (Based on an Analysis of Soviet and Russian Feature Films about Children)     

K.N. Polivanova  M.A. Shakarova 《Russian Education & Society》2018,60(4):348-369

The current state of childhood research is grounded in classical psychological theories, and Russian psychology is tied to cultural and historical theory in particular. These theories were invented to generalize and make sense of the realities of childhood as they existed at the time when these theories were created. Rapid social changes, especially during recent decades, have led to the emergence of a wide range of sources that bear witness to how the day-to-day life of childhood has changed. The understanding of childhood has continued to transform from one era to another. A metaphor was even coined to describe it, and at some point there was even a specific metaphor coined, “the disappearance of childhood.” This article seeks to explore how the image of childhood has changed in relation to the image of adulthood. As material for analysis, we chose Soviet and Russian movies from the 1940s to 2000s. The study is based on the assumption that a sequential analysis based on Yuri Lotman’s theory of the structure of the text demonstrates how the image of childhood changes over time. If in the 1940s and 1950s the child was presented as immature and not quite grown up, the adult was portrayed as the embodiment of the ideal form of the individual, and the main conflict was structured around childish immaturity, then gradually over the decades more and more main characters who were children and adults were portrayed as different kinds of individuals, and the child (or teenager) sometimes came to embody obviously negative features. The child–adult dichotomy itself lost its significance.  相似文献