Coherence estimate between a random and a periodic signal: Bias, variance, analytical critical values, and normalizing transforms     

Antonio Mauricio F.L. Miranda de S  Danton D. Ferreira  Edson W. Dias  Eduardo M.A.M. Mendes  Leonardo B. Felix 《Journal of The Franklin Institute》2009,346(9):841-853

The present work deals with recent results on the sampling distribution of the magnitude-squared coherence (also called just coherence) estimate between a random (Gaussian) and a periodic signal, in order to obtain analytical critical values, alternative expressions for the probability density function (PDF) as well as the variance and bias of the estimate. A comparison with the more general case of coherence estimation when both signals are Gaussian was also provided. The results indicate that the smaller the true coherence (TC) values the closer both distributions become. The behaviour of variance and bias as a function of the number of data segments and the TC is similar for both coherence estimates. Additionally, the effect of a normalizing function (Fisher's z transform) in the coherence estimated between a random and a periodic signal was also evaluated and normality has been nearly achieved. However, the variance was less equalized in comparison with coherence estimate between two Gaussian signals.  相似文献   

Domestic patents and developing countries: arguments for their study and data from Brazil (1980–1995)     

Eduardo da Motta e Albuquerque 《Research Policy》2000,29(9)

This paper presents data from Brazilian Patent Office (Instituto Nacional de Propriedade Industrial, INPI) and compares them with data from the United States Patent Office (USPTO). Developing countries have technological activities that are important locally but not significant at international level (imitation, local learning, adaptation of foreign innovations). These activities might be patentable only at national level. Therefore, the study of domestic patents of developing countries provides a broader picture than USPTO patents. This paper compares 8309 INPI patents with 475 USPTO patents (between 1980 and 1995). Domestic patent data show peculiarities in the Brazilian case, possibly shared with other countries in similar technological level: (a) high share of individual patents; (b) foreign-owned firms with important activities; (c) low firm involvement in R&D activities. Some characteristics are shared with developed countries: (a) domestic firms as the major patentees; (b) according to firm size, there is a U-shaped distribution of patents; (c) evidences of multi-technology large firms; (d) a relatively small share of firms have more than one patent in the whole period. The contrast between USPTO and national patenting statistics shows different rankings according to ownership structure, leading firms, industrial sectors, and international patent classification. These differences highlight sources of international competitiveness and point to weaknesses in Brazilian innovative activities. This paper concludes evaluating the contributions (and weaknesses) of this database for the evaluation of the Brazilian National System of Innovation.  相似文献   

3-min all-out effort on cycle ergometer is valid to estimate the anaerobic capacity by measurement of blood lactate and excess post-exercise oxygen consumption     

Alessandro Moura Zagatto  Paulo Eduardo Redkva  Rodrigo Araújo Bonetti de Poli  Joel Abraham Martinez González  Jeniffer Zanetti Brandani  Thiago Penedo 《European Journal of Sport Science》2019,19(5):645-652

The purpose of this study was to investigate the use of a single 3-min all-out maximal effort to estimate anaerobic capacity (AC) through the lactate and excess post-exercise oxygen consumption (EPOC) response methods (AC_{[La^?]+EPOCfast}) on a cycle ergometer. Eleven physically active men (age?=?28.1?±?4.0?yrs, height?=?175.1?±?4.2?cm, body mass?=?74.8?±?11.9?kg and ?O_2max?=?40.7?±?7.3?mL?kg^?1?min^?1), participated in the study and performed: i) five submaximal efforts, ii) a supramaximal effort at 115% of intensity of ?O_2max, and iii) a 3-min all-out maximal effort. Anaerobic capacity was estimated using the supramaximal effort through conventional maximal accumulated oxygen deficit (MAOD) and also through the sum of oxygen equivalents from the glycolytic (fast component of excess post-exercise oxygen consumption) and phosphagen pathways (blood lactate accumulation) (AC_{[La^?]+EPOCfast}), while during the 3-min all-out maximal effort the anaerobic capacity was estimated using the AC_{[La^?]+EPOCfast} procedure. There were no significant differences between the three methods (p?>?0.05). Additionally, the anaerobic capacity estimated during the 3-min all-out effort was significantly correlated with the MAOD (r?=?0.74; p?=?0.009) and AC_{[La^?]+EPOCfast} methods (r?=?0.65; p?=?0.029). Therefore, it is possible to conclude that the 3-min all-out effort is valid to estimate anaerobic capacity in physically active men during a single cycle ergometer effort.  相似文献   

Optimal sampling frequency in recording of resistance training exercises     

Paolo Bardella  Irene Carrasquilla García  Marco Pozzo  Julio Tous-Fajardo  Eduardo Saez de Villareal 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(1):102-114

The purpose of this study was to analyse the raw lifting speed collected during four different resistance training exercises to assess the optimal sampling frequency. Eight physically active participants performed sets of Squat Jumps, Countermovement Jumps, Squats and Bench Presses at a maximal lifting speed. A linear encoder was used to measure the instantaneous speed at a 200 Hz sampling rate. Subsequently, the power spectrum of the signal was computed by evaluating its Discrete Fourier Transform. The sampling frequency needed to reconstruct the signals with an error of less than 0.1% was f_99.9 = 11.615 ± 2.680 Hz for the exercise exhibiting the largest bandwidth, with the absolute highest individual value being 17.467 Hz. There was no difference between sets in any of the exercises. Using the closest integer sampling frequency value (25 Hz) yielded a reconstruction of the signal up to 99.975 ± 0.025% of its total in the worst case. In conclusion, a sampling rate of 25 Hz or above is more than adequate to record raw speed data and compute power during resistance training exercises, even under the most extreme circumstances during explosive exercises. Higher sampling frequencies provide no increase in the recording precision and may instead have adverse effects on the overall data quality.  相似文献   

Correlations between serum and salivary hormonal concentrations in response to resistance exercise     

Cadore E  Lhullier F  Brentano M  Silva E  Ambrosini M  Spinelli R  Silva R  Kruel L 《Journal of sports sciences》2008,26(10):1067-1072

The aim of present study was to examine the relationships between serum and salivary values of free testosterone, dehydroepiandrosterone, and cortisol before and after a session of resistance exercise. Twenty-eight healthy men (mean age 40 years, s = 4) participated in the present study. Serum and salivary samples were collected at rest and after a multiple-sets resistance exercise protocol, of approximately 25 minutes duration. Concentrations of free testosterone, dehydroepiandrosterone, and cortisol were measured using radioimmunoassay kits. No significant correlation was observed between serum free testosterone and salivary testosterone (r = 0.22 to 0.26, P > 0.05). Serum cortisol was significantly correlated with salivary cortisol before (r = 0.52, P = 0.005) and after (r = 0.62, P = 0.001) the exercise protocol. Serum and salivary concentrations of dehydroepiandrosterone were significantly correlated before (r = 0.68, P < 0.001) and after (r = 0.7, P < 0.001) exercise. The results of the present study suggest that even under exercise conditions, the salivary values of cortisol and dehydroepiandrosterone can reflect the behaviour of these hormones in blood. However, further studies are necessary to verify if salivary testosterone reflects the behaviour of serum free testosterone during resistance exercise.  相似文献   

Effects of AM3 (Inmunoferon) on increased serum concentrations of interleukin-6 and tumour necrosis factor receptors I and II in cyclists     

Cordova A  Monserrat J  Villa G  Reyes E  Soto MA 《Journal of sports sciences》2006,24(6):565-573

The aims of this study were to examine the changes in plasma concentrations of inflammatory cytokines induced by training and competition in professional cyclists. We report the serum concentrations of interleukin-6 (IL-6), tumour necrosis factor alpha (TNF-a), tumour necrosis factor receptors I and II (TNFR-I and -II) in a prospective, randomized, double-blind trial involving the administration of AM3 (Inmunoferon), an oral booster immunomodulator, or placebo to 16 professional cyclists (n = 8 in each group) for 65 consecutive days. Serum was collected just before treatment began (baseline), at the end of pre-competition training, before the mountain stage of the competition (60 days), 4 h after finishing this stage (62 days), and 18 h after the fifth and last day of competition (65 days). To determine the normal levels of cytokines and soluble TNF receptors, individual samples from 14 moderately trained healthy controls were studied. After 60 days of training, the serum concentrations of IL-6 did not differ significantly from those at the beginning of the study for either group of cyclists (placebo and AM3). A significant rise was seen in IL-6 concentrations in both the AM3 and placebo groups at 62 days, 4 h after finishing the mountain stage. The increase was significantly greater in the placebo group than in the AM3 group. At 65 days of treatment, 18 h after the fifth and last day of competition, IL-6 concentrations were similar to those recorded at the end of the training, but were significantly higher in the placebo group than in the AM3 group. At the end of training, serum TNFR-I concentrations in both groups of cyclists were significantly lower than at baseline. The concentrations of serum TNFR-I and -II both 4 h after finishing the mountain stage and 18 h after the fifth and last day of competition were significantly higher than those recorded after training in both groups. Professional cycling competition is associated with increases in serum IL-6 and TNFR-I and -II concentrations. Inmunoferon treatment reduced significantly the concentrations of IL-6 but not those of TNFR-I and -II.  相似文献   

Effects and prevalence of responders after a multicomponent intervention on cardiometabolic risk factors in children and adolescents with overweight/obesity: Action for health study     

Caroline Brand  Clarice Maria De Lucena Martins  Vanilson Batista Lemes  Maria Luisa Félix Pessoa  Arieli Fernandes Dias  Eduardo Lusa Cadore 《Journal of sports sciences》2020,38(6):682-691

ABSTRACT

This study aimed to verify the effect of a multicomponent intervention on cardiometabolic risk factors (CMRF), and to determine the prevalence of responders on CMRF among children and adolescents with overweight/obesity. This is a quasi-experimental study, developed with 35 children and adolescents with overweight/obesity (control group (CG) = 18; intervention group (IG) = 17), aged between 7 and 13 years. Participants in IG underwent a multicomponent intervention for 12 weeks. The following variables were evaluated: anthropometric measures, maturational stages and CMRF (body fatness, HOMA-IR, triglycerides, high-density and low-density lipoprotein) (HDL-C, LDL-C), total cholesterol (TC), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and AST/ALT ratio. Mixed analysis of variance and the prevalence of responders were used for statistical analysis. There was a significant time x group interaction on body fatness (p < 0.001), HOMA-IR (p = 0.01), HDL-C (p < 0.001), LDL-C (p = 0.009) and TC (p < 0.001). The prevalence of responders for CMRF in IG and CG was respectively: body fatness (47%; 0%; p = 0.04), HOMA-IR (58.8%; 16.6%; p = 0.04); triglycerides (17.6%; 5.5%; p = 0.31); HDL-C (76.4%; 5.5%; p = 0.01), LDL-C (35.3%; 5%; p = 0.08), TC (64.7%; 5%; p = 0.01), AST (5.8%; 0%; p = 0.87), ALT (29.4%; 11.1%; p = 0.24) and AST/ALT ratio (24.4%; 22.2%; p = 0.67). Multicomponent intervention induced positive changes on CMRF along with a higher prevalence of positive adaptations in IG than the CG in some of the cardiometabolic outcomes assessed.  相似文献   

Piaget and school education: A socio-cultural challenge     

Eduardo Martí 《Prospects》1996,26(1):141-158

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Conceptual change or Conceptual Profile change?     

Eduardo F. Mortimer 《Science & Education》1995,4(3):267-285

In this paper I draw an overview of a new model to analyse conceptual evolution in the classroom, based on the notion of Conceptual Profile. This model differs from conceptual change models in suggesting that it is possible to use different ways of thinking in different domains and that a new concept does not necessarily replace previous and alternative ideas. According to this model, learning science is to change a conceptual profile and become conscious of the different zones of the profile, which includes commonsense and scientific ideas.To exemplify how the Conceptual Profile notion can help to understand the evolution of conceptions in the classroom I shall determine the different zones that constitute the epistemological and ontological profile of the concepts of the atom and of physical states of matter.  相似文献   

Flipping the Classroom in Freshman English Library Instruction: A Comparison Study of a Flipped Class Versus a Traditional Lecture Method     

Eduardo Rivera 《New Review of Academic Librarianship》2017,23(1):18-27

A problem that Instruction Librarians often grapple with is the lack of time that is necessary to deliver, and assess, proper library instruction to students so the students grasp the Information Literacy concepts that are delivered especially in one or two instruction sessions. This article examines using the flipped classroom model in English library instruction classes where the works cited page of students final paper was assessed according to a rubric designed to assess the Authority, Timeliness, and Variety of the sources cited. The study compared results of flipped classroom sections against traditional lecture method classes with mixed results.  相似文献