A numerically robust blind equalization scheme applied to MIMO communication systems     

Flávio R.  M. Pavan  Magno T.  M. Silva  Maria D. Miranda 《Journal of The Franklin Institute》2018,355(1):596-624

In this paper, we propose a numerically robust blind equalization scheme to mitigate cochannel and intersymbol interferences and separate signals from a convolutive mixture in multiple-input multiple-output (MIMO) communication systems. The robustness of the proposed scheme is achieved through a particular dual-mode operation applied to a constant-modulus-based space-time algorithm that corrects phase rotations. In the first mode of operation, the consistency in the nonlinear estimates of the transmitted signals is ensured. In the second mode, the Euclidean norms of the equalizer coefficient vectors decrease along the iterations, which allows the algorithm to return to the first mode of operation, where the estimation of the transmitted signals really occurs. In particular, we apply this scheme to a multimodulus version of the multiuser Shalvi-Weinstein algorithm (MU-SWA). By means of a deterministic stability analysis assuming the persistence of excitation condition, we show that the dual-mode MU-SWA does not diverge.  相似文献   

Assessment of passive drag in swimming by numerical simulation and analytical procedure     

Tiago M. Barbosa  Rui Ramos  António J. Silva  Daniel A. Marinho 《Journal of sports sciences》2018,36(5):492-498

The aim was to compare the passive drag-gliding underwater by a numerical simulation and an analytical procedure. An Olympic swimmer was scanned by computer tomography and modelled gliding at a 0.75-m depth in the streamlined position. Steady-state computer fluid dynamics (CFD) analyses were performed on Fluent. A set of analytical procedures was selected concurrently. Friction drag (D_f), pressure drag (D_pr), total passive drag force (D_f+pr) and drag coefficient (C_D) were computed between 1.3 and 2.5 m · s^?1 by both techniques. D_f+pr ranged from 45.44 to 144.06 N with CFD, from 46.03 to 167.06 N with the analytical procedure (differences: from 1.28% to 13.77%). C_D ranged between 0.698 and 0.622 by CFD, 0.657 and 0.644 by analytical procedures (differences: 0.40–6.30%). Linear regression models showed a very high association for D_f+pr plotted in absolute values (R² = 0.98) and after log–log transformation (R² = 0.99). The C_D also obtained a very high adjustment for both absolute (R² = 0.97) and log–log plots (R² = 0.97). The bias for the D_f+pr was 8.37 N and 0.076 N after logarithmic transformation. D_f represented between 15.97% and 18.82% of the D_f+pr by the CFD, 14.66% and 16.21% by the analytical procedures. Therefore, despite the bias, analytical procedures offer a feasible way of gathering insight on one’s hydrodynamics characteristics.  相似文献   

Aerobic exercise training performed by parents reduces mice offspring adiposity     

Paulo Vitor da Silva Romero  Débora Alves Guariglia  Francielli Ferreira Da Rocha  Caroline de Carvalho Picoli  Gustavo Renan Gilio  Gabriel Sergio Fabricio 《Journal of sports sciences》2018,36(14):1578-1585

The present study aimed to determine the effects of physical training performed by parents on mice offspring adiposity. Male and female parents underwent an aerobic training protocol for 7 weeks. The trained and sedentary parents were allowed to mate and the resultant offspring divided in: S (Offspring from Sedentary Parents), T (Offspring from Trained Parents), ST (Offspring from Sedentary Father and Trained Mother) and TS (Offspring from Trained Father and Sedentary Mother). After weaning, offspring was euthanized, blood collected and samples of mesenteric and inguinal fat pads used to isolate adipocytes for morphologic and histological analyses. Lee index, mesenteric fat pad, sum of visceral fat and total fat weight of female T was reduced in comparison to the other groups (p < 0.05). Periepididymal and sum of visceral fat in male T group was also reduced when compared to the other groups (p < 0.05). The diameter of mesenteric and inguinal adipocytes of T group was smaller compared to all groups comparisons for both sexes (p < 0.05). In summary, exercise training performed by parents reduced visceral offspring adiposity, the diameter of subcutaneous adipocytes and improved metabolic parameters associated to metabolic syndrome.  相似文献   

Effect of a pilot multi-component intervention on motor performance and metabolic risks in overweight/obese youth     

Dominique Silva Silveira  Luis Filipe Gomes Barbosa Ferreira Lemos  Rafael Miranda Tassitano  Maria Teresa Cattuzzo  Anderson Henry Pereira Feitoza  Luisa Maria Seara Moreira Carneiro Aires 《Journal of sports sciences》2018,36(20):2317-2326

This study evaluated the effect of a multi-component intervention on motor performance (MP) and metabolic risk markers (MRM) in overweight/obese youth. A secondary aim was to examine whether changes in MP are associated to changes in MRM. A 3-month multi-component intervention was performed, consisting of physical exercise sessions (twice/week;1h), nutritional education sessions (once/month), and parental support (twice/week). The sample included 35 volunteers (7–13 y.o), allocated to intervention (INT, n = 17) and control (CONT, n = 18) group. Variables were measured pre (T0) and post intervention (T1). Fasting blood samples were analyzed for MRM. MP tests included the measurement of health related physical fitness components and motor coordination performance (KTK battery). To assess food intake, a 24-hour recall diary was used. GLM-ANCOVA was performed. Standardized scores were calculated for the outcome variables, and multilinear regressions were applied to analyze associations between the key variables. INT group showed improvements in MP, glycolytic and hepatic profiles. After adjustments for MVPA, SB, total intake and maturational stage, negative associations between %ΔMP and %Δglycolytic (β = -.424; 95%CI:-0.343:-0.022), and %Δhepatic scores (β = -.382 95%CI:-0.001:-0.009) were observed. The intervention produced a moderate-to-high effect on the MP and some MRM. Changes in MP were inversely associated with changes in glycolytic and hepatic markers.  相似文献   

Antecedents and consequents of student satisfaction in higher technical-vocational education: evidence from Brazil     

de Oliveira Silva  Jorge Henrique  de Sousa Mendes  Glauco Henrique  Ganga  Gilberto Miller Devós  Mergulhão  Ricardo Coser  Lizarelli  Fabiana Letícia 《International Journal for Educational and Vocational Guidance》2020,20(2):351-373

International Journal for Educational and Vocational Guidance - This article proposes a model of antecedents and consequences of student satisfaction in Higher Technical-Vocational Education (HTVE)...  相似文献   

Playing outdoor and practising sport: A study of physical activity levels in Portuguese children     

Paula Silva  Maria Paula Santos 《European Journal of Sport Science》2017,17(2):208-214

In outdoor activities, it seems reasonable that the longer children spend in spontaneous physical activity (PA), the higher the probability of being active. Indeed, the time spent outdoor has been identified as a variable consistently associated with the children’s PA. Outdoor playing, such as the organized sports practice, appears associated with healthier lifestyle standards. All the recommendations mention the importance of increasing daily PA practice in children and teenagers, but few studies highlight the relationship between outdoor play and the recommended PA levels. The purpose of this study is to investigate the relationships between the frequency of outdoor play, the frequency of the organized sports practice, and the compliance of the recommendations for PA practice in children in the inner city area of Porto. The sample of this study is composed of 422 individuals (mean age of 11.6 years). Two hundred and twenty-five of them were girls and 197 were boys from the sixth grade (elementary schools located in the inner city area of Porto). PA was objectively evaluated using accelerometers. Participants reported frequency of participation in different PA contexts, such as sports practice and outdoor play. The results show a predictor effect of participating in sports three or more times per week on compliance of PA guidelines.

In conclusion, organized sports practice seems more effective than outdoor play to reach the recommended levels of PA in children.  相似文献   

How players exploit variability and regularity of game actions in female volleyball teams     

Ana Ramos  Patrícia Coutinho  Pedro Silva  Keith Davids  Isabel Mesquita 《European Journal of Sport Science》2017,17(4):473-481

Variability analysis has been used to understand how competitive constraints shape different behaviours in team sports. In this study, we analysed and compared variability of tactical performance indices in players within complex I at two different competitive levels in volleyball. We also examined whether variability was influenced by set type and period. Eight matches from the 2012 Olympics competition and from the Portuguese national league in the 2014–2015 season were analysed (1496 rallies). Variability of setting conditions, attack zone, attack tempo and block opposition was assessed using Shannon entropy measures. Magnitude-based inferences were used to analyse the practical significance of compared values of selected variables. Results showed differences between elite and national teams for all variables, which were co-adapted to the competitive constraints of set type and set periods. Elite teams exploited system stability in setting conditions and block opposition, but greater unpredictability in zone and tempo of attack. These findings suggest that uncertainty in attacking actions was a key factor that could only be achieved with greater performance stability in other game actions. Data suggested how coaches could help setters develop the capacity to play at faster tempos, diversifying attack zones, especially at critical moments in competition.  相似文献   

Some cultural and economic factors leading to neglect, abuse and violence in respect of children within the family in Sri Lanka     

Wimala de Silva Ph.D. 《Child abuse & neglect》1981,5(4):391-405

The paper provides an overview of the present position. It attempts to identify the causational factors in situations of child neglect, abuse and violence and to pinpoint areas where there is a lacuna in information and knowledge. The study takes prevalence of abandoned children, failure to meet a child's basic needs and underutilization of services provided free by the state as indices of neglect. Measured in these terms it seems that though in Sri Lanka children are considered a blessing, yet they are also subject to neglect though this is not deliberate on the part of parents but arising from numerous factors, mainly poverty and ignorance. Other influences also operate such as cultural values and weaknesses in the delivery systems. Today females of all socioeconomic levels seek employment, both locally and abroad. This can lead to child neglect since community services for child care are inadequate and traditional help is dwindling. The negative impact on children of certain aspects of modernization is also considered. Abuse of children manifests itself mainly in child domestic labour and the exploitation, particularly of malformed and diseased children, in the trade of begging. Violence as judged by reported cases is minimal. But considering social attitudes regarding physical punishment, its prevalence may be wider than generally believed. The need for statistics and studies on all aspects of child care and child behaviour have come out in the study.  相似文献   

Validation of clay modeling as a learning tool for the periventricular structures of the human brain          下载免费PDF全文

Veronica Akle  Ricardo A. Peña‐Silva  Diego M. Valencia  Carlos W. Rincón‐Perez 《Anatomical sciences education》2018,11(2):137-145

Visualizing anatomical structures and functional processes in three dimensions (3D) are important skills for medical students. However, contemplating 3D structures mentally and interpreting biomedical images can be challenging. This study examines the impact of a new pedagogical approach to teaching neuroanatomy, specifically how building a 3D‐model from oil‐based modeling clay affects learners’ understanding of periventricular structures of the brain among undergraduate medical students in Colombia. Students were provided with an instructional video before building the models of the structures, and thereafter took a computer‐based quiz. They then brought their clay models to class where they answered questions about the structures via interactive response cards. Their knowledge of periventricular structures was assessed with a paper‐based quiz. Afterward, a focus group was conducted and a survey was distributed to understand students’ perceptions of the activity, as well as the impact of the intervention on their understanding of anatomical structures in 3D. Quiz scores of students that constructed the models were significantly higher than those taught the material in a more traditional manner (P < 0.05). Moreover, the modeling activity reduced time spent studying the topic and increased understanding of spatial relationships between structures in the brain. The results demonstrated a significant difference between genders in their self‐perception of their ability to contemplate and rotate structures mentally (P < 0.05). The study demonstrated that the construction of 3D clay models in combination with autonomous learning activities was a valuable and efficient learning tool in the anatomy course, and that additional models could be designed to promote deeper learning of other neuroanatomy topics. Anat Sci Educ 11: 137–145. © 2017 American Association of Anatomists.  相似文献   

A questionnaire for listening to students’ voices in the assessment of teaching quality in a classical medical school     

Maria Filomena Gaspar  Anabela Mota Pinto  Hugo Camilo F. da Conceição  José António Pereira da Silva 《Assessment & Evaluation in Higher Education》2008,33(4):445-453

The purpose of this study was to develop a teaching quality assessment questionnaire and assess its reliability by using it with a sample of first‐year medical students. Principal components analysis with varimax orthogonal rotation resulted in the development of a 12‐item, two‐component tool, adequate for use in lectures and small‐group sessions. The two components were named ‘curriculum’ and ‘relationship’. The Cronbach coefficient alpha values indicated high reliability and internal consistency. According to the results obtained this teaching quality scale is a reliable measure and may be useful in identifying themes in disciplines and among teachers that may benefit from some professional development. Amongst its advantages is that it can be used with an optical reading tool.  相似文献