1,721,078 research outputs found
Physiological responses to acute airborne particle exposure during maximal aerobic power
No full textWe measured physiological effects of airborne particle exposure in athletes.\ud
Intensity exercise close to maximal aerobic capacity was considered.\ud
Particles were generated through incense-burning indoor phenomena.\ud
Statistically significant differences were found between high and low scenarios.\ud
No differences were measured in terms of exhaled nitric oxide
Plastic changes induced by muscle focal vibration. A possible mechanism for long-term motor improvements
No full textRepetitive focal vibrations can induce positive and persistent after-effects. There is still no satisfactory interpretation of the underlying mechanisms. A rationale, which can provide consistency among different results, is highly desirable to guide both the use of the application and future research. To date, interpretive models are formulated to justify the results, depending on the specific protocol adopted. Indeed, protocol parameters, such as stimulus intensity and frequency, intervention time and administration period, are variable among different studies. However, in this article, we have identified features of the protocols that may allow us to suggest a possible common mechanism underlying the effectiveness of focal vibration under different physiologic and pathologic conditions. Since repetitive focal muscle vibration induces powerful and prolonged activation of muscle proprioceptors, we hypothesize that this intense activation generates adaptive synaptic changes along sensory and motor circuits. This may lead to long-term synaptic potentiation in the central network, inducing an enhancement of the learning capability. The plastic event could increase proprioceptive discriminative ability and accuracy of the spatial reference frame and, consequently, improve motor planning and execution for different motor functions and in the presence of different motor dysfunctions. The proposed mechanism may explain the surprising and sometimes particularly rapid improvements in motor execution in healthy and diseased individuals, regardless of specific physical training. This hypothetic mechanism may require experimental evidence and could lead to extend and adapt the application of the “learning without training” paradigms to other functional and recovery needs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
PHYSIOLOGICAL MODIFICATIONS INDUCED BY ACUTE AIRBORNE PARTICLE EXPOSURE DURING HIGH INTENSITY
No full textIntroduction In industrialized countries most common physical activities usually occurs in urban microenvironments with high levels of airborne particles (PM10) concentrations. Exercising in polluted urban areas increases particles inhaled amount as a result of the increased minute ventilation (Carlisle and Sharp, 2001). Since there is a lack of studies investigating acute physiological effects of high PM10 levels, this study aimed to assess physiological parameters during incremental maximal aerobic tests on a cycloergometer under low and high PM10 exposures. Methods Following informed consent, 9 male amateur cyclists performed 2 tests for each environmental condition: low and high PM10 concentration. Exposure scenarios were replicated using a fully controlled environmental chamber. Peak oxygen consumption (VO2peak), carbon dioxide production (VCO2peak), respiratory frequency (RFpeak), tidal volume (VTpeak), pulmonary ventilation (VEpeak), hearth rate (HRpeak) and mechanical power output (Ppeak) values were recorded for each trial. Gross efficiency (GE) was determined using the ratio between mechanical power output and metabolic power input. T-test was applied to evaluate differences (p<0.05) between physiological parameters. Results According to trial protocol, all subjects achieved equal mechanical power (Ppeak) in the 4 incremental tests. No significant differences in HRpeak, RFpeak and VEpeak were found. VTpeak increased (p<0.05) under high exposure (39.69 ± 8.12 ml•kg-1) compared to low exposure (38.16 ± 6.75 ml•kg-1). Differences (p<0.05) for VO2peak were found between low (38.39 ± 4.05 ml•kg-1•min-1) and high particles concentration conditions (41.68 ± 4.31 ml•kg-1•min-1). Since same mechanical work was expressed while significant VO2peak differences were recorded, GE reduced (p<0.02) during sustained exercise under high PM10 concentrations (21.47 ± 1.74 %) compared to low (23.24 ± 1.35 %) with a mean difference of 1.77%. Discussion The present findings indicate that during high intensity exercise GE is affected by high PM10 concentrations. As GE is defined one of the most important functional abilities of cyclists (Coyle, 1995), results suggest that cyclist’s athletic performances are impaired by polluted microenvironments. References Carlisle AJ, Sharp NC. (2001) Exercise and outdoor ambient air pollution. Br J Sports Med 35(4), 214–22. Coyle EF. (1995) Integration of the physiological factor
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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