Effects of cigarette smoking on cardiac autonomic function during dynamic exercise     

Goncalo V. Mendonca  Fernando D. Pereira  Bo Fernhall 《Journal of sports sciences》2013,31(9):879-886

Abstract

The purpose of this study was to investigate the acute effect of cigarette smoking on cardiac autonomic function in young adult smokers during dynamic exercise. Fourteen healthy young smokers (21.4 ± 3.4 years) performed peak and submaximal exercise protocols under control and smoking conditions. Resting and submaximal beat-to-beat R-R series were recorded and spectrally decomposed using the fast Fourier transformation. Smoking resulted in a significant decrease in work time, [Vdot]O_2peak and peak O₂ pulse (P < 0.05). Heart rate increased at rest and during submaximal exercise after smoking (P < 0.05). The raw high frequency and low frequency power were significantly reduced by smoking, both at rest and during exercise (P < 0.05). The low to high frequency ratio was higher after smoking (P < 0.05). The normalised low frequency power was also significantly increased by smoking, but only at rest (P < 0.05). These data demonstrate that the tachycardic effect elicited by smoking is accompanied by acute changes in heart rate spectral components both at rest and during exercise. Therefore, the cardiac autonomic control is altered by smoking not only at rest, but also during exercise, resulting in reduced vagal modulation and increased sympathetic dominance.  相似文献   

List of Reviewers     

Coral Falco  Javier Molina-García  Octavio Álvarez  Isaac Estevan 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):381-382

The aim of this study was to investigate the effects of target distance on temporal and impact force parameters that are important performance factors in taekwondo kicks. Forty-nine taekwondo athletes (age = 24.5 ± 5.9 years; mass = 79.9 ± 10.8 kg) were recruited: 13 male experts, 21 male novices, 8 female experts, and 6 female novices. Impact force, reaction time, and execution time were computed. Three-way repeated measure ANOVAs revealed significant ‘distance’ effect on impact force, reaction time, and execution time (p = 0.001). Comparisons between distance conditions revealed that taekwondo athletes kicked with higher impact force from short distance (17.6 ± 7.5 N/kg) than from long distance (13.1 ± 5.7 N/kg) (p < 0.001), had lower reaction time from short distance (498 ± 90 ms) and normal distance (521 ± 111 ms) than from long distance (602 ± 121 ms) (p < 0.001), and had lower execution time from short distance (261 ± 69 ms/m) than from normal distance (306 ± 105 ms/m) or from long distance (350 ± 106 ms/m) (p = 0.003 and p < 0.001, respectively). In conclusion, target distance affected the kick performance; as distance increases, impact force decreased and reaction time increased. Therefore, when reaction to a simple visual stimulus is needed, kicking from a long distance is not recommended, as longer time is required to respond.  相似文献   

Pre-service Teachers’ False Beliefs in Superstitions and Pseudosciences in Relation to Science and Technology     

Fuertes-Prieto  Miguel Ángel  Andrés-Sánchez  Santiago  Corrochano-Fernández  Diego  Urones-Jambrina  Carmen  Delgado-Martín  Mª Laura  Herrero-Teijón  Pablo  Ruiz  Camilo 《Science & Education》2020,29(5):1235-1254

Science & Education - In order to increase scientific competence within the general population, it is important that teachers and educators have a realistic image of science and scientists,...  相似文献   

An instructional model for web-based e-learning education with a blended learning process approach     

Fernando Alonso  Genoveva López  Daniel Manrique  José M. Viñes 《British journal of educational technology : journal of the Council for Educational Technology》2005,36(2):217-235

Web‐based e‐learning education research and development now focuses on the inclusion of new technological features and the exploration of software standards. However, far less effort is going into finding solutions to psychopedagogical problems in this new educational category. This paper proposes a psychopedagogical instructional model based on content structure, the latest research into information processing psychology and social contructivism, and defines a blended approach to the learning process. Technologically speaking, the instructional model is supported by learning objects, a concept inherited from the object‐oriented paradigm.  相似文献   

The Sources of Error in Spanish Writing (Research Note)     

Fernando Justicia  Sylvia Defior  Santiago Pelegrina  Francisco J. Martos 《Journal of Research in Reading》1999,22(2):198-202

The main aim of this study was to determine the pattern of errors in Spanish spelling. Specifically, we were interested in discovering if all Spanish words have similar levels of spelling difficulty or whether there are types of words that cause a high percentage of spelling errors. 972 children aged between 8 to 10 years were requested to write a short spontaneous story. Our objective was to analyse and to propose a classification system for the errors made by children in the initial stages of the acquisition of spelling skills. The results indicate (a) that the diverse forms of only 20 Spanish words produce 36 per cent of the spelling errors in Spanish, and (b) that substitution is the most frequent type of error (68 per cent of total errors), which occurs as a consequence of an inadequate knowledge of the rules of phoneme-grapheme correspondence. These findings have relevance for the teaching of writing in Spanish.  相似文献   

Immigration,motherhood and parental involvement: narratives of communal agency in the face of power asymmetry     

Giselle Del Carmen Martinez Negrette 《Discourse: Studies in the Cultural Politics of Education》2019,40(6):967-969

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Reading difficulties in Albanian     

Avdyli R  Cuetos F 《Annals of dyslexia》2012,62(3):137-152

Albanian is an Indo-European language with a shallow orthography, in which there is an absolute correspondence between graphemes and phonemes. We aimed to know reading strategies used by Albanian disabled children during word and pseudoword reading. A pool of 114 Kosovar reading disabled children matched with 150 normal readers aged 6 to 11?years old were tested. They had to read 120 stimuli varied in lexicality, frequency, and length. The results in terms of reading accuracy as well as in reading times show that both groups were affected by lexicality and length effects. In both groups, length and lexicality effects were significantly modulated by school year being greater in early grades and later diminish in length and just the opposite in lexicality. However, the reading difficulties group was less accurate and slower than the control group across all school grades. Analyses of the error patterns showed that phonological errors, when the letter replacement leading to new nonwords, are the most common error type in both groups, although as grade rises, visual errors and lexicalizations increased more in the control group than the reading difficulties group. These findings suggest that Albanian normal children use both routes (lexical and sublexical) from the beginning of reading despite of the complete regularity of Albanian, while children with reading difficulties start using sublexical reading and the lexical reading takes more time to acquire, but finally both routes are functional.  相似文献   

Inequality of opportunity for educational achievement in Latin America: Evidence from PISA 2006–2009     

Luis Fernando Gamboa  Fábio D. Waltenberg 《Economics of Education Review》2012

We evaluate how far away six Latin American countries stand from a normative goal of equality of opportunity for educational achievement in PISA 2006–2009. We work with alternative characterizations of types: gender, school type (public or private), parental education, and their combinations. Following Checchi–Peragine's (2010) non-parametric method, we find that inequality of opportunity for educational achievement in Latin America ranges from less than 1% to up to 25%, depending on the year, the country, the subject and the specification of circumstances. These magnitudes are substantial with respect to what is found in comparator countries. Parental education and school type prove to be important sources of inequality of opportunity, contrary to gender. By means of sensitivity analyses, while most results show small to moderate variation in terms of magnitudes, in ordinal terms (rankings) they remain quite stable. Brazil stands out as the most opportunity-unequal country of the sample.  相似文献   

Multi-objective optimization design of bridge piers with hybrid heuristic algorithms     

Francisco J. Martinez-Martin  Fernando Gonzalez-Vidosa  Antonio Hospitaler  Víctor Yepes 《浙江大学学报(A卷英文版)》2012,13(6):420-432

This paper describes one approach to the design of reinforced concrete (RC) bridge piers, using a three-hybrid multi-objective simulated annealing (SA) algorithm with a neighborhood move based on the mutation operator from the genetic algorithms (GAs), namely MOSAMO1, MOSAMO2 and MOSAMO3. The procedure is applied to three objective functions: the economic cost, the reinforcing steel congestion and the embedded CO₂ emissions. Additional results for a random walk and a descent local search multi-objective algorithm are presented. The evaluation of solutions follows the Spanish Code for structural concrete. The methodology was applied to a typical bridge pier of 23.97 m in height. This example involved 110 design variables. Results indicate that algorithm MOSAMO2 outperforms other algorithms regarding the definition of Pareto fronts. Further, the proposed procedure will help structural engineers to enhance their bridge pier designs.  相似文献   

Children’s Models about Colours in Nahuatl-Speaking Communities     

Leticia Gallegos-Cázares  Fernando Flores-Camacho  Elena Calderón-Canales  Elvia Perrusquía-Máximo  Beatriz García-Rivera 《Research in Science Education》2014,44(5):699-725

This paper presents the development and structure of indigenous children’s ideas about mixing colours as well as their ideas about each colour, derived from their traditions. The children were interviewed both at school and outside it, and an educational proposal was implemented. Ideas expressed in the school context were analysed using the partial possible model, which states that the inferences and explanations used to describe a subject consist of constricting ideas, rules of correspondence, and a set of phenomenological inferences about processes. After identifying these components in the children’s ideas, we developed models to describe their conceptions about mixing colours. We employed a different approach to analyse children’s ideas related to their cultural context. The results showed that children change from a conception that focuses on colours as entities that do not change and as properties of objects (model 1) to the idea that colour represents a quality of substances or objects that can be modified by mixing colours (model 2). Cultural context analysis showed that stories are independent from one another and that they are not connected to colour mixing processes, only to the actions of colour on people. We concluded that students generate independent constructions between school and cultural knowledge.  相似文献