The effect of l-citrulline and watermelon juice supplementation on anaerobic and aerobic exercise performance     

Paul T. Cutrufello  Stephen J. Gadomski  Gerald S. Zavorsky 《Journal of sports sciences》2015,33(14):1459-1466

Citrulline has been proposed as an ergogenic aid, leading to an interest in watermelon given its high citrulline concentration. The aim of this study was to determine the effects of a single, pre-exercise dose of l-citrulline, watermelon juice, or a placebo on the total maximum number of repetitions completed over 5 sets, time to exhaustion, maximal oxygen consumption (VO₂max), anaerobic threshold, and flow-mediated vasodilation. A randomised double-blind within-participants study design was used to examine these effects among 22 participants (n = 11 males). Supplementation included either a 7.5% sucrose drink containing 6 g of l-citrulline, 710 mL of watermelon juice (~1.0 g citrulline), or a 7.5% sucrose placebo drink. Supplementation was administered 1 or 2 h before exercise testing to investigate a timing effect. There was no significant effect between the three supplements for the total number of repetitions, time to exhaustion, VO₂max, anaerobic threshold, or flow-mediated vasodilation. There was also no interaction observed relative to gender or supplement timing (P > 0.05). A single dose of l-citrulline or watermelon juice as a pre-exercise supplement appears to be ineffective in improving exercise performance; however, greater doses of l-citrulline have been shown to be safe and are currently left unexamined.  相似文献   

The Development of Sport in Museums     

J. Reilly 《国际体育史杂志》2015,32(15):1778-1783

Sport as a topic for museum collection, display, and interpretation has gradually developed over the last 100 years. However, until recently, there has been very little discussion or examination of the material culture of sport within the literature. Consequently, there is a misconception that sport in museums is relatively new, little is understood about the role and value of sporting heritage, and sporting collections are rarely used to inform historical study. In turn, the museum sector would benefit from more opportunities to work with sports historians whilst developing and delivering their sporting provision. Therefore, this paper examines the development of sport in museums, explores the current activity being developed in the field including the work of the Sport in Museums Network and the National Sporting Heritage Day, and offers practical information about how partnerships between academics and museum practitioners can be established to create a better understanding of the history and heritage of sport.  相似文献   

Osmotically driven drug delivery through remote-controlled magnetic nanocomposite membranes     

A. Zaher  S. Li  K. T. Wolf  F. N. Pirmoradi  O. Yassine  L. Lin  N. M. Khashab  J. Kosel 《Biomicrofluidics》2015,9(5)

Implantable drug delivery systems can provide long-term reliability, controllability, and biocompatibility, and have been used in many applications, including cancer pain and non-malignant pain treatment. However, many of the available systems are limited to zero-order, inconsistent, or single burst event drug release. To address these limitations, we demonstrate prototypes of a remotely operated drug delivery device that offers controllability of drug release profiles, using osmotic pumping as a pressure source and magnetically triggered membranes as switchable on-demand valves. The membranes are made of either ethyl cellulose, or the proposed stronger cellulose acetate polymer, mixed with thermosensitive poly(N-isopropylacrylamide) hydrogel and superparamagnetic iron oxide particles. The prototype devices'' drug diffusion rates are on the order of 0.5–2 μg/h for higher release rate designs, and 12–40 ng/h for lower release rates, with maximum release ratios of 4.2 and 3.2, respectively. The devices exhibit increased drug delivery rates with higher osmotic pumping rates or with magnetically increased membrane porosity. Furthermore, by vapor deposition of a cyanoacrylate layer, a drastic reduction of the drug delivery rate from micrograms down to tens of nanograms per hour is achieved. By utilizing magnetic membranes as the valve-control mechanism, triggered remotely by means of induction heating, the demonstrated drug delivery devices benefit from having the power source external to the system, eliminating the need for a battery. These designs multiply the potential approaches towards increasing the on-demand controllability and customizability of drug delivery profiles in the expanding field of implantable drug delivery systems, with the future possibility of remotely controlling the pressure source.  相似文献   

Informing in-season tactical periodisation in team sport: development of a match difficulty index for Super Rugby     

Samuel J. Robertson  David G. Joyce 《Journal of sports sciences》2015,33(1):99-107

In team sports, tactical periodisation refers to the planned manipulation of training loads with the aim of prioritising athlete readiness for matches of greatest importance. Although monitoring of athletes’ physical condition is often used to inform this planning, the direct influence of external factors on match difficulty has not been well quantified. In this study, a ‘match difficulty index’ (MDI) for use in Super Rugby was developed, based on the influence imparted by five external factors on previous match outcomes. Specifically, information relating to match location, days break between matches, time-zone change and opposition ladder position (both current and previous year) were collected for matches played during the 2011–2013 Super Rugby seasons. Logistic regression analyses were used to assess the importance of each of these factors with respect to match outcome (win/loss), with opposition ladder position and match location (home, domestic away or international) exerting the greatest influence on match difficulty. Three separate cross-validated models were constructed, with match outcome classification performance reported as 66.2%, 65.5% and 63.7% respectively. The three MDI models emanating from this study can each be used to inform tactical periodisation program design both prior to and during the regular season.  相似文献   

The impact of data reduction on the intra-trial reliability of a typical measure of lower limb musculoskeletal stiffness     

Mark P. Moresi  Elizabeth J. Bradshaw  David A. Greene  Geraldine A. Naughton 《Journal of sports sciences》2015,33(2):180-191

Double-leg repeated jumping tasks are commonly used as measures of lower limb stiffness in exercise science research. Within similar stiffness calculations, variation in data-reduction criteria exists. The impact of these varied data-reduction methods on stiffness measures is unknown. Sixteen adolescent female participants from varied physical activity backgrounds performed 15 self-paced, bent-knee continuous jumps (CJb) on two force plates. Leg stiffness was calculated as the ratio of the peak force and the centre of mass displacement for each contact. Using combinations of criteria based on previous literature, 83 data-reduction methods were applied to the raw data. Data reduction suitability was assessed based on intra-trial reliability, the number of participants excluded and the average contacts excluded. Four data-reduction methods were deemed suitable for use with adolescent female populations, with three consecutive contacts within 1 SD of the average jump frequency considered optimal. The average individual stiffness values were not greatly influenced by the data-reduction method; however, for a single participant, a stiffness change of up to 6 kN · m^?1 (30%) was observed. The role and potential impact of data-reduction methods used to evaluate measures of lower limb stiffness during repeated jumping tasks warrants consideration.  相似文献   

Lexicomp Online and Micromedex 2.0     

Amy J. Chatfield 《Journal of the Medical Library Association》2015,103(2):112-113

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Reinforcing attitudes in a gatewatching news era: Individual-level antecedents to sharing fact-checks on social media     

Michelle A. Amazeen  Chris J. Vargo  Toby Hopp 《Communication monographs》2019,86(1):112-132

Despite the prevalence of fact-checking, little is known about who posts fact-checks online. Based upon a content analysis of Facebook and Twitter digital trace data and a linked online survey (N?=?783), this study reveals that sharing fact-checks in political conversations on social media is linked to age, ideology, and political behaviors. Moreover, an individual’s need for orientation (NFO) is an even stronger predictor of sharing a fact-check than ideological intensity or relevance, alone, and also influences the type of fact-check format (with or without a rating scale) that is shared. Finally, participants generally shared fact-checks to reinforce their existing attitudes. Consequently, concerns over the effects of fact-checking should move beyond a limited-effects approach (e.g., changing attitudes) to also include reinforcing accurate beliefs.  相似文献   

Talent,Schmalent: An Instructional Design/Action Research Framework for the Professionalization of Teaching in Academic Libraries     

Alexander J. Carroll  Kevin Michael Klipfel 《The Journal of Academic Librarianship》2019,45(2):110-118

When myths become canonical beliefs within a professional culture, they can have a profound impact on professional practice. In this paper we identify as a pernicious educational myth the belief that the ability to teach well is a naturally occurring innate talent or skill. The first two sections of the paper aim to demonstrate (i) that the concept of the naturally gifted teacher is a myth based on factually incorrect assumptions about expertise development and (ii) that this myth has several major negative implications for professional practices around teaching in academic libraries. We then we draw on the education literature to offer an alternative model for the cultivation of teaching excellence, an instructional design/action research framework that prioritizes ‘deliberative’ practice over innate talent. We close with suggestions for how academic librarians and library administrators can implement this framework within their institutions.  相似文献   

��It depends on what science teacher you got��: urban science self-efficacy from teacher and student voices     

Virginia L. J. Bolshakova  Carla C. Johnson  Charlene M. Czerniak 《Cultural Studies of Science Education》2011,6(4):961-997

In the United States today, urban schools serve the majority of high-poverty and high minority populations including large numbers of Hispanic students. While many Hispanic students perform below grade level in middle school science, the science teaching community as a whole is lacking elements of diversity as teachers struggle to meet the needs of all learners. Researchers have recognized that science teacher effectiveness, one consequence of self-efficacy among teachers, is associated with future science achievement and science-related careers of their students. This qualitative study explores how three science teachers’ effectiveness in the classroom impacts students’ science self-efficacy beliefs at one urban middle school. Hispanic students were the focus of this investigation due to demographics and history of underperformance within this district. Teachers’ perspectives, as well as outside observer evaluations of instructional strategies and classroom climates were triangulated to explore dynamics that influence students’ interests and motivation to learn science using a framework to link teachers’ sense of efficacy (focusing on student outcomes). Findings suggest the impact teacher effectiveness can have on student outcomes, including strengthened student science self-efficacy and increased science achievement. Building awareness and support in teachers’ sense of efficacy, as well as developing respectful and supportive relationships between educator/facilitator and pupil during the transition to middle school may construct permanence and accomplishment for all in science.  相似文献   

Curricular innovation in an undergraduate medical program: What is “appropriate” assessment?     

Valerie Ruhe  J. Donald Boudreau 《Educational Assessment, Evaluation and Accountability》2011,23(3):187-200

In post-secondary education, there is a widely-held belief in a “gold standard” for evaluative studies of curricular innovations. In this context, “appropriate” assessment is understood to refer to experimental designs and statistically significant differences in group outcomes. Yet in our evaluative study of a medical undergraduate program, we did not find these concepts to be particularly applicable. Based on our experience, we now feel that it is appropriate to assemble an eclectic mix of scientific findings, show how they have been used for program improvement, and articulate the program’s theoretical rationale and social significance. In the absence of statistically significant differences, this comprehensive argument can be used to justify the deployment of curricular innovations. The same may be true of other educational programs that target hard-to-measure changes in affective domains.  相似文献