The role of the entry-and-stretch phase at the different paces of race in front crawl swimming

The aim of this study was to determine the role played by the entry-and-stretch phase in the coordination of swimming, at the different paces of race. Three national level swimmers (two men and one woman) were recorded, in lateral and bottom views, in three swimming paces: sprint (50 m and 100 m), middle-distance (200 m and 400 m) and long-distance (800 m and 1500 m). Anatomical landmark positions were obtained by manual digitalisation of the videos. Computational fluid dynamics and experimental studies (with a strain gauge balance and particle image velocimetry method) were used to measure and to calculate the external forces applied to the hand and to the forearm and to visualise the flow around the profile. Entry-and-stretch is the phase which varies the most according to the swimming pace. This phase can be decomposed into two sub-phases: one, the extension forward coordinated with the insweep of the opposite arm, and another one, the rotation downward coordinated with the upsweep. Results show that, at the three paces, this phase is not propulsive and could contribute essentially to maintain the horizontal balance of the body.     

Detecting bias in meta-analyses of distance education research: big pictures we can rely on

This article has two interrelated purposes. The first is to explain how various forms of bias, if introduced during any stage of a meta-analysis, can provide the consumer with a misimpression of the state of a research literature. Five of the most important bias-producing aspects of a meta-analysis are presented and discussed. Second, armed with this information, we examine 15 meta-analyses of the literatures of distance education (DE), online learning (OL), and blended learning (BL), conducted from 2000 to 2014, with the intention of assessing potential sources of bias in each. All of these meta-analyses address the question: “How do students taking courses through DE, OL, and BL compare to students engaged in pure classroom instruction in terms of learning achievement outcomes?” We argue that questions asked by primary researchers must change to reflect issues that will drive improvements in designing and implementing DE, OL, and BL courses.     

How Canadian universities use social media to brand themselves

This paper explores social media marketing strategies applied by Canadian universities as a tool for institutional branding, recruitment and engagement of home and international students. The target sample involves the total population of Canadian university-status institutions (N = 106). Qualitative data were collected from two major social networking websites, Facebook and Twitter, over the span of six months to provide a comprehensive picture. Additionally, student enrolment data were compiled with the purpose of associating social media implementation with fluctuations of student enrolment. Results reveal that the Twitter platform is generally much more popular to carry conversations, but that Facebook remains the preferred website for university-initiated postings; most of these university-led postings, whether on Twitter or Facebook, relate to campus/student news and events. Findings point to institutions as only one of many message generators, while students and a host of third parties have become the dominant ones.     

博物馆观众研究简史(三)——20世纪90年代至今

博物馆观众研究领域最早的成果可以追溯到吉尔曼(Gilman)在1911年的研究工作,本文对观众评估研究的关注对象与问题进行了历史性的批判分析。本研究揭示了各类研究建立的范式,包括对实施机制的说明、对评估客观性的审问、对文化民主化研究和营销相关研究之间不协调性的强调。本文结合多年经济危机和理性化带来的影响,介绍了20世纪90年代至今博物馆观众研究的工具化,并结合观众研究的他律性的特点进行分析,提出了这一领域面临的四大挑战。     

Media Production

Bob Westmoreland's Teleproduction Shortcuts: A Manual for Low-Budget Television Production in a Small Studio (Norman: University of Oklahoma Press, 1974—$10.95)

Joseph F. Robinson's Videotape Recording.: Theory and Practice (New York: Hastings House, 1975– $18.50)

L. Bernard Happe's Your Film & the Lab (New York: Hastings House, 1974 —$11.50/6.50)     

Ponctuation et Connecteurs: Une Approche Textuelle et Génétique

Two experiments were carried out in order to study the development of textual punctuation use in children from 7 to 13. Four unpunctuated stories (following Mandler & Johnson’s narrative grammars 1977) involving or not a connective (et/alors/après) at different places were submitted to subjects who had to write them down in adding punctuation marks. The results show a strong textual impact on the frequency of punctuation which is higher at the beginning and at the end of the stories. We found also a strong impact of connectedness: the frequencies and types of punctuation marks varied in relation to connectives:et was rarely punctuated;alors was mainly associated with commas whereasaprès was more often associated whith periods. These effects were significant mainly from 11 years of age on, except for the impact ofet already observed at 7 years of age.     

Common morality and computing

This article shows how common morality can be helpful in clarifying the discussion of ethical issues that arise in computing. Since common morality does not always provide unique answers to moral questions, not all such issues can be resolved, however common morality does provide a clear answer to the question whether one can illegally copy software for a friend.     

Seroprevalence of SARS-CoV-2 infection among children in Children’s Hospital Zagreb during the initial and second wave of COVID-19 pandemic in Croatia

IntroductionThe study aimed to investigate the prevalence and titres of anti-SARS-CoV-2 antibodies in children treated at the Children’s Hospital Zagreb in the first and the second wave of the COVID-19 pandemic. Statistical significance of difference at two time points was done to determine how restrictive epidemiological measures and exposure of children to COVID-19 infection affect this prevalence in different age groups.Materials and methodsAt the first time point (13th to 29th May 2020), 240 samples and in second time point (24th October to 23rd November 2020), 308 serum samples were tested for anti-SARS-CoV-2 antibodies by enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescence immunoassay (ECLIA). Confirmation of results and titre determination was done using virus micro-neutralization test. Subjects were divided according to gender, age and epidemiological history.ResultsSeroprevalence of anti-SARS-CoV-2 antibodies differs significantly in two time points (P = 0.010). In first time point 2.9% of seropositive children were determined and in second time point 8.4%. Statistically significant difference (P = 0.007) of seroprevalence between two time points was found only in a group of children aged 11-19 years. At the first time point, all seropositive children were asymptomatic with titre < 8. At the second time point, 69.2% seropositive children were asymptomatic with titre ≥ 8.ConclusionsThe prevalence of anti-SARS-CoV-2 antibodies was significantly lower at the first time point than at the second time point. Values of virus micro-neutralization test showed that low titre in asymptomatic children was not protective at the first time point but in second time point all seropositive children had protective titre of anti-SARS-CoV-2 antibodies.