A user-centred approach to the design of an expert system for training     

Marcos Augusto Francisco Borges  & M. Cecília C. Baranauskas 《British journal of educational technology : journal of the Council for Educational Technology》1998,29(1):25-34

This paper reports the objectives, design approach and first results of a research project that aims to develop an intelligent computer-based learning environment for industrial applications. Jonas , an expert system, is part of a modelling/simulation environment which enables shopfloor workers to test and to put new philosophies of work into practice in the context of manufacture. Our approach is focused on three main ideas: the Intelligence Augmentation paradigm, user-centred system design and the constructionist theory of learning. The architecture of the modelling environment and the main features of Jonas are presented as an illustration of the design ideas discussed in the paper.  相似文献   

Effects of resistance training in HIV-infected patients: A meta-analysis of randomised controlled trials     

Roberto Poton  Marcos Polito  Paulo Farinatti 《Journal of sports sciences》2017,35(24):2380-2389

The relative effects of resistance training (RT) upon muscle fitness and immune function among HIV-infected patients are uncertain. The purpose of this study was to perform a meta-analysis to determine the effects of RT upon muscle strength, muscle mass and CD4 cells count and to identify potential moderators of those outcomes in HIV-infected patients. Meta-analyses use random or fixed-effects model depending on the heterogeneity of effect sizes, complemented with Hedge’s g correction factor. Thirteen trials were meta-analysed. Overall, RT increased muscle strength (35.5%, P < 0.01) and CD4 cell count (26.1%, P = 0.003) versus controls (P < 0.03), but not muscle mass (P = 0.051). Meta-regression followed by subgroup moderator analysis showed that gains in muscle strength followed a dose–response pattern with largest increase detected among trials with longer (24 weeks; 49.3%) than shorter intervention (<12 weeks; 39%), higher (Physiotherapy Evidence-Based Database [PEDro] scale = 6; 38.3%) than lower (PEDro = 5; 28.1%) quality, and longer (12 months; 59.7%) than shorter time under highly active antiretroviral therapy (HAART) (<6 months; 37.1%), (P < 0.01). RT appears to be efficacious to improve muscular strength (~35.5%) and CD4 cell count (~26.1%), but not muscle mass of HIV-infected patients. Effects upon strength were greater in studies with higher quality and among trials with longer RT and HAART.  相似文献   

Mediation role of cardiorespiratory fitness on the association between fatness and cardiometabolic risk in European adolescents: The HELENA study     

Carlos Cristi-Montero  Javier Courel-Ibez  Francisco B. Ortega  Jose Castro-Piero  Alba Santaliestra-Pasias  Angela Polito  Jrmy Vanhelst  Ascensin Marcos  Luis M. Moreno  Jonatan R. Ruiz  HELENA study group 《运动与健康科学(英文)》2021,10(3):360-367

PurposeThis study was aimed to analyze the mediation role of cardiorespiratory fitness (CRF) on the association between fatness and cardiometabolic risk scores (CMRs) in European adolescents.MethodsA cross-sectional study was conducted in adolescents (n = 525; 46% boys; 14.1 ± 1.1 years old, mean ± SD) from 10 European cities involved in the Healthy Lifestyle in Europe by Nutrition in Adolescence study. CRF was measured by means of the shuttle run test, while fatness measures included body mass index (BMI), waist to height ratio, and fat mass index estimated from skinfold thicknesses. A clustered CMRs was computed by summing the standardized values of homeostasis model assessment, systolic blood pressure, triglycerides, total cholesterol/high-density lipoprotein cholesterol ratio, and leptin.ResultsLinear regression models indicated that CRF acted as an important and partial mediator in the association between fatness and CMRs in 12–17-year-old adolescents (for BMI: coefficients of the indirect role β = 0.058 (95% confidence interval (95%CI): 0.023–0.101), Sobel test z = 3.11 (10.0% mediation); for waist to height ratio: β = 4.279 (95%CI: 2.242–7.059), z =3.86 (11.5% mediation); and for fat mass index: β = 0.060 (95%CI: 0.020–0.106), z = 2.85 (9.4% mediation); all p < 0.01).ConclusionIn adolescents, the association between fatness and CMRs could be partially decreased with improvements to fitness levels; therefore, CRF contribution both in the clinical field and public health could be important to consider and promote in adolescents independently of their fatness levels.  相似文献   

ACCURACY AND ERROR IN ELECTORAL FORECASTS: THE CASE OF MEXICO     

Beltran  Ulises; Valdivia  Marcos 《Int. Journal of Public Opinion Research》1999,11(2):115-134

Forecast errors in preelectoral polls are common. Since theNicaraguan Election in 1990, a common assumption is that wheredemocratic practices are not equal to those of the developedcountries (authoritarian, in transition, etc.), the errors inpredicting electoral outcomes with the help of pre-electoralpolls result mostly from contextual effects related to the authoritariannature of the political systems. Forecast errors in developeddemocracies have been explained by flaws in sampling (GreatBritain), last minute changes in preferences (Spain, UnitedStates, and France) and a social desirability bias in the UnitedStates. The intention of this paper is to show that in Mexicoboth the accuracy and the sources of error in predicting electoralresults are very similar to those confronted by pollsters elsewhere:mostly sampling and allocation of nonrespondents and those whoare undecided. An extensive data set of pre-electoral pollsconducted in Mexico shows an average error in the order of 3–5percentage points. Some of this error could be related to sociallydesirable answers derived from contextual effects, but thiseffect is small and must not be generalized.  相似文献   

Muscle activity and pedal force profile of triathletes during cycling to exhaustion     

Diefenthaeler F  Coyle EF  Bini RR  Carpes FP  Vaz MA 《Sports biomechanics / International Society of Biomechanics in Sports》2012,11(1):10-19

The purpose of this study was to analyze pedaling cadence, pedal forces, and muscle activation of triathletes during cycling to exhaustion. Fourteen triathletes were assessed at the power output level relative to their maximal oxygen uptake (355 +/- 23 W). Cadence, pedal forces, and muscle activation were analyzed during start, middle, and end test stages. Normal and tangential forces increased from the start to the end of the test (-288 +/- 33 to -352 +/- 42 N and -79 +/- 45 to -124 +/- 68 N, respectively) accompanied by a decrease in cadence (96 +/- 5 to 86 +/- 6 rpm). Muscle activation increased from the start to the middle and the end in the gluteus maximus (27 +/- 5.5% and 76 +/- 9.3%) and in the vastus lateralis (13 +/- 3.5% and 27 +/- 4.4%), similar increase was observed from the start to the end in the rectus femoris and the vastus medialis (50 +/- 9.3% and 20 +/- 5.7%, respectively). Greater normal force along with enhanced activation of knee and hip extensor muscles is linked with fatigue and declines in cadence of triathletes during cycling to exhaustion.  相似文献   

What do I want to feel? Emotion goals in childhood,adolescence, and adulthood     

Belén López-Pérez  Michaela Gummerum  Marcos Jiménez  Maya Tamir 《Child development》2023,94(1):315-328

Beliefs about emotion utility can influence context-sensitive emotion goals (i.e., desired emotional responses). Although key for emotion regulation, emotion goals have been overlooked in children and adolescents. In 2018–2019 results of Studies 1 and 2 showed that children (N = 192, M_age = 8.65, 47% girls, 96% White) were less motivated by and found anger less useful in confrontation than adolescents (N = 192, M_age = 12.96, 50% girls, 93% White) and adults (N = 195, M_age = 29.82, 51% women, 96% White). The link between emotion goals and beliefs about emotion utility was weaker in children. In 2021, Study 3 (N = 60, 8-year-olds, 47% girls, 90% White) ruled out expectations as a possible explanation for the previous findings. Context-sensitive utility of emotions may be acquired during development.  相似文献   

Specific relevance instructions promote selective reading strategies: evidences from eye tracking and oral summaries     

Jos A. Len  Jos David Moreno  Inmaculada Escudero  Ricardo Olmos  Marcos Ruiz  Robert F. Lorch 《Journal of Research in Reading》2019,42(2):432-453

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A linear optimization approach to the combined production planning model     

Maria Cristina N. Gramani  Paulo M. França  Marcos N. Arenales 《Journal of The Franklin Institute》2011,348(7):1523-1536

Two fundamental processes usually arise in the production planning of many industries. The first one consists of deciding how many final products of each type have to be produced in each period of a planning horizon, the well-known lot sizing problem. The other process consists of cutting raw materials in stock in order to produce smaller parts used in the assembly of final products, the well-studied cutting stock problem. In this paper the decision variables of these two problems are dependent of each other in order to obtain a global optimum solution. Setups that are typically present in lot sizing problems are relaxed together with integer frequencies of cutting patterns in the cutting problem. Therefore, a large scale linear optimizations problem arises, which is exactly solved by a column generated technique. It is worth noting that this new combined problem still takes the trade-off between storage costs (for final products and the parts) and trim losses (in the cutting process). We present some sets of computational tests, analyzed over three different scenarios. These results show that, by combining the problems and using an exact method, it is possible to obtain significant gains when compared to the usual industrial practice, which solve them in sequence.  相似文献   

An analysis of two styles of arm action in the vertical countermovement jump     

Marcos Gutiérrez-Dávila  Francisco J. Amaro  Juan M. Garrido 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(2):135-143

The aim of this study was to determine the effect of two arm swing techniques, the simultaneous arm swing and the early arm swing, on vertical countermovement jump performance and on the contribution of the arms to vertical movement at the centre of mass (CM) during the propulsion phase. Participants were 28 athletes practicing sports in which the vertical jump constitutes a basic ability. Ground reaction forces were recorded by a force platform and the sagittal plane motion was recorded by a video camera. Although at take-off the vertical velocity (2.7 ± 0.2 m/s for simultaneous technique vs. 2.8 ± 0.2 m/s for early technique; p = 0.040) and position (1.18 ± 0.06 m for simultaneous vs. 1.17 ± 0.05 m for early; p = 0.033) of the CM were significantly different, no difference was observed in jump height (1.56 ± 0.01 m in both techniques). The arm action differed during the initial and final propulsion phases in both styles but the accumulated vertical contribution was similar. The practical implication in sports is that the use of the arm-swing technique to reach the maximum jump height should be determined by tactical demands instead of the technical execution of the arms.  相似文献   

Anticipatory strategies of team-handball goalkeepers     

Marcos Gutierrez-Davila  Manuel Ortega  Jose Campos  Juan Parraga 《Journal of sports sciences》2013,31(12):1321-1328

Abstract

This study seeks to discover whether handball goalkeepers employ a general anticipatory strategy when facing long distance throws and the effect of uncertainty on these strategies. Seven goalkeepers and four throwers took part. We used a force platform to analyse the goalkeeper's movements on the basis of reaction forces and two video cameras synchronised at 500 Hz to film the throw using 3D video techniques. The goalkeepers initiated their movement towards the side of the throw 193 ± 67 ms before the release of the ball and when the uncertainty was reduced the time increased to 349 ± 71 ms. The kinematics analysis of their centre of mass indicated that there was an anticipatory strategy of movement with certain modifications when there was greater uncertainty. All the average scores referring to velocity and lateral movement of the goalkeeper's centre of mass are significantly greater than those recorded for the experimental situation with bigger uncertainty. The methodology used has enabled us to tackle the study of anticipation from an analysis of the movement used by goalkeepers to save the ball.  相似文献