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  1. 1

    Hydrodynamic Drag during Gliding in Swimming

    Publicação
    por Marinho, Daniel
    Outros Autores: Reis, Víctor M.; Alves, Francisco; Vilas Boas, J. Paulo; Machado, Leandro; Silva, António et al.
    Origem: uBibliorum
    This study used a computational fluid dynamics methodology to analyze the effect of body position on the drag coefficient during submerged gliding in swimming. The k-epsilon turbulent model implemented in the commercial code Fluent and applied to the flow around a three-dimensional model of a male adult swimmer was used. Two common gliding positions were investigated: a ventral position with the arms extended at the front, and a ventral position with the arms placed along side the trunk. The simulations were applied to flow velocities of between 1.6 and 2.0 m x s(-1), which are typical of elite swimmers when gliding underwater at the start and in the turns. The gliding position with the arms extended at the front produced lower drag coefficients than with the arms placed along the trunk. We therefore recommend that swimmers adopt the arms in front position rather than the arms beside the trunk position during the underwater gliding.
    2009 artigo Portugal acesso aberto
  2. 2

    Effect of Efavirenz on High-Density Lipoprotein Antioxidant Properties in HIV-Infected Patients

    Publicação
    por Pereira, SA
    Outros Autores: Batuca, JR; Caixas, U; Branco, T; Delgado-Alves, J; Germano, I et al.
    WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: * In previous work, we showed a long-term and concentration-dependent beneficial effect of the non-nucleoside reverse transcriptase inhibitor efavirenz (EFV) on high-density lipoproteins (HDL) in human immunodeficiency virus (HIV)-infected patients. * Furthermore, it has been suggested that instead of the current practice of only measuring HDL-chelesterol values, the evaluation of HDL function, namely its antioxidant properties, might be an improved tool for identifying subjects at increased risk for cardiovascular events. * Paraoxonase-1 (PON-1) is an enzyme associated with HDL that is responsible for HDL antioxidant function. WHAT THIS STUDY ADDS: * In the present work, we studied the effect of EFV on the activity of PON-1 and showed, for the first time, that EFV-based antiretroviral therapy is associated with a better antioxidant function, i.e. with a higher PON-1 activity. AIMS: A long-term and concentration-dependent beneficial effect of efavirenz (EFV) on cholesterol associated with high-density lipoprotein (HDL-c) in human immunodeficiency virus (HIV)-infected patients has been documented. Furthermore, it has been suggested that, instead of the current practice of only measuring HDL-c values, the evaluation of HDL quality might be an improved tool for identifying subjects at increased risk of cardiovascular events. Paraoxonase-1 (PON-1) is an enzyme associated with HDL that is involved in the onset of cardiovascular disease and responsible for HDL antioxidant function. The aim of the present study was to investigate the effect of EFV on the circulating activity of PON-1 in HIV-infected patients. METHODS: The patients included were adults with a documented HIV-1 infection, nontreated or treated with antiretroviral regimens including EFV 600 mg once daily as first therapeutic regimen for at least 3 months. The influence of treatment with EFV, HDL-c and CD4 cell count on PON-1 activity was analysed. RESULTS: HIV-infected White patients treated with EFV had higher PON-1 activity [77.35 U l(-1) (65.66, 89.04)] (P < 0.05) and higher PON-1 activity : HDL-c ratio [1.88 (1.49, 2.28)] (P < 0.01) than untreated patients. PON-1 activity was higher in Black patients (P < 0.001) and in patients with a CD4 cell count >500 cells ml(-1) (P= 0.0120). CONCLUSIONS: EFV-based antiretroviral regimens are associated with HDL particles with a better antioxidant function, i.e. with a higher PON-1 activity. The PON-1 activity of Black patients is higher than that found in Whites regardless of treatment. Ethnicity should be taken into consideration when studying drug effects on PON-1 activity.
    2009 artigo Portugal acesso aberto
  3. 3

    Ordinal logistic regression in epidemiological studies

    Publicação
    por Abreu, Mery Natali Silva
    Outros Autores: Siqueira, Arminda Lucia; Caiaffa, Waleska Teixeira
    Origem: Oasisbr
    Ordinal logistic regression models have been developed for analysis of epidemiological studies. However, the adequacy of such models for adjustment has so far received little attention. In this article, we reviewed the most important ordinal regression models and common approaches used to verify goodness-of-fit, using R or Stata programs. We performed formal and graphical analyses to compare ordinal models using data sets on health conditions from the National Health and Nutrition Examination Survey (NHANES II).
    2009 artigo Brasil
  4. 4

    Sobre o significado da significância estatística

    Publicação
    por Teixeira, Pedro Miguel Silva Costa Afonso
    2018 outro Portugal acesso aberto
  5. 5

    Measures of aggression and victimization in portuguese adolescents: Cross-cultural validation of the Revised Peer Experience Questionnaire

    Publicação
    por Queirós, Andreia N.
    Outros Autores: Vagos, Paula
    The goal of this research was to develop and psychometrically evaluate the Portuguese version of the Revised Peer Experience Questionnaire, which assesses aggression, victimization and prosocial behavior. Victimization and aggression among adolescents in school settings is a growing problem, not yet fully understood or properly evaluated, particularly in Portugal. A sample of 1320 adolescents was recruited (52.7% female), with ages varying from 10 to 18 years old, attending middle and high school. Confirmatory factor analysis confirms the measurement model of the instrument's bully and victim versions, as evaluating overt, relational, and reputational aggression/victimization and providing/receiving prosocial behavior, respectively. This measurement model was invariant across schooling and gender, showed adequate internal consistency indicators, and presented evidence for construct validity in relation to other variables. Descriptive analyses indicate that boys are more aggressive in overt and relational forms and victimized through overt aggression, whereas girls are more aggressive and victimized relationally. More than any form of aggression or victimization, boys and girls revealed higher values for engaging in and receiving prosocial behavior. These results suggest that this instrument is a reliable, valid, and structurally sound measure of aggression, victimization and prosocial behavior in this Portuguese school-based community sample. Hence, its use may assist researchers in gaining a better understanding of adolescent aggression and victimization. (PsycINFO Database Record
    2016 artigo Portugal acesso aberto
  6. 6

    Age of Crime Onset and Psychopathic Traits in Female Juvenile Delinquents

    Publicação
    por Pechorro, Pedro
    Outros Autores: Gonçalves, Rui Abrunhosa; Marôco, João; Nunes, Cristina; Jesus, Saúl Neves
    The aim of this study was to analyze the role of psychopathic traits in the age of crime onset of female juvenile delinquents. Using a sample of 132 young females from the Juvenile Detention Centers of the Portuguese Ministry of Justice and from schools in the Lisbon region, a group of early crime onset (n = 44), a group of late crime onset (n = 44), and a nondelinquent school group (n = 44) were formed. Results showed that early crime onset participants score higher on psychopathy measures, self-reported delinquency, and crime seriousness than late crime onset participants and school participants. Psychopathic-traits scores were significantly associated with age of crime onset, age at first trouble with the law, and frequency and seriousness of crime.
    2013 artigo Portugal acesso aberto
  7. 7

    Ashamed and Fused with Body Image and Eating: Binge Eating as an Avoidance Strategy

    Publicação
    por Duarte, Cristiana
    Outros Autores: Pinto-Gouveia, José; Ferreira, Cláudia
    Binge Eating Disorder (BED) is currently recognized as a severe disorder associated with relevant psychiatric and physical comorbidity, and marked emotional distress. Shame is a specific negative emotion that has been highlighted as central in eating disorders. However, the effect of shame and underlying mechanisms on binge eating symptomatology severity remained unclear. This study examines the role of shame, depressive symptoms, weight and shape concerns and eating concerns, and body image-related cognitive fusion, on binge eating symptomatology severity. Participated in this study 73 patients with the diagnosis of BED, established through a clinical interview-Eating Disorder Examination 17.0D-who completed measures of external shame, body-image related cognitive fusion, depressive symptoms and binge eating symptomatology. Results revealed positive associations between binge eating severity and depressive symptoms, shame, weight and shape concerns, eating concerns and body image-related cognitive fusion. A path analysis showed that, when controlling for the effect of depressive symptoms, external shame has a direct effect on binge eating severity, and an indirect effect mediated by increased eating concern and higher levels of body image-related cognitive fusion. Results confirmed the plausibility of the model, which explained 43% of the severity of binge eating symptoms. The proposed model suggests that, in BED patients, perceiving that others see the self negatively may be associated with an entanglement with body image-related thoughts and concerns about eating, which may, in turn, fuel binge eating symptoms. Findings have important clinical implications supporting the relevance of addressing shame and associated processes in binge eating. Copyright © 2015 John Wiley & Sons, Ltd.
    2017 artigo Portugal acesso aberto
  8. 8

    Strategic procedure in three stages for the selection of variables to obtain balanced results in public health research

    Publicação
    por Lozano,Manuel
    Outros Autores: Manyes,Lara; Peiró,Juanjo; Iftimi,Adina; Ramada,José María
    Origem: Oasisbr
    Multidisciplinary research in public health is approached using methods from many scientific disciplines. One of the main characteristics of this type of research is dealing with large data sets. Classic statistical variable selection methods, known as “screen and clean”, and used in a single-step, select the variables with greater explanatory weight in the model. These methods, commonly used in public health research, may induce masking and multicollinearity, excluding relevant variables for the experts in each discipline and skewing the result. Some specific techniques are used to solve this problem, such as penalized regressions and Bayesian statistics, they offer more balanced results among subsets of variables, but with less restrictive selection thresholds. Using a combination of classical methods, a three-step procedure is proposed in this manuscript, capturing the relevant variables of each scientific discipline, minimizing the selection of variables in each of them and obtaining a balanced distribution that explains most of the variability. This procedure was applied on a dataset from a public health research. Comparing the results with the single-step methods, the proposed method shows a greater reduction in the number of variables, as well as a balanced distribution among the scientific disciplines associated with the response variable. We propose an innovative procedure for variable selection and apply it to our dataset. Furthermore, we compare the new method with the classic single-step procedures.
    2018 artigo Brasil acesso aberto
  9. 9

    Assessment of Autonomic Function by Phase Rectification of RRInterval Histogram Analysis in Chagas Disease

    Publicação
    por Nasari Junior,Olivassé
    Outros Autores: Benchimol-Barbosa,Paulo Roberto; Pedrosa,Roberto Coury; Nadal,Jurandir
    Origem: Oasisbr
    Background:In chronic Chagas disease (ChD), impairment of cardiac autonomic function bears prognostic implications. Phase‑rectification of RR-interval series isolates the sympathetic, acceleration phase (AC) and parasympathetic, deceleration phase (DC) influences on cardiac autonomic modulation.Objective:This study investigated heart rate variability (HRV) as a function of RR-interval to assess autonomic function in healthy and ChD subjects.Methods:Control (n = 20) and ChD (n = 20) groups were studied. All underwent 60-min head-up tilt table test under ECG recording. Histogram of RR-interval series was calculated, with 100 ms class, ranging from 600–1100 ms. In each class, mean RR-intervals (MNN) and root-mean-squared difference (RMSNN) of consecutive normal RR-intervals that suited a particular class were calculated. Average of all RMSNN values in each class was analyzed as function of MNN, in the whole series (RMSNNT), and in AC (RMSNNAC) and DC (RMSNNDC) phases. Slopes of linear regression lines were compared between groups using Student t-test. Correlation coefficients were tested before comparisons. RMSNN was log-transformed. (α < 0.05).Results:Correlation coefficient was significant in all regressions (p < 0.05). In the control group, RMSNNT, RMSNNAC, and RMSNNDCsignificantly increased linearly with MNN (p < 0.05). In ChD, only RMSNNAC showed significant increase as a function of MNN, whereas RMSNNT and RMSNNDC did not.Conclusion:HRV increases in proportion with the RR-interval in healthy subjects. This behavior is lost in ChD, particularly in the DC phase, indicating cardiac vagal incompetence.
    2015 artigo Brasil acesso aberto
  10. 10

    Assessing vaccine data recording in Brazil

    Publicação
    por Novaes,Mario Lucio de Oliveira
    Outros Autores: Almeida,Renan Moritz Varnier Rodrigues de; Bastos,Ronaldo Rocha
    Origem: Oasisbr
    ABSTRACT: Objectives: Vaccines represent an important advancement for improving the general health of a population. The effective recording of vaccine data is a factor for the definition of its supply chain. This study investigated vaccine data recording relatively to data collected from vaccination rooms and data obtained from a government-developed Internet platform. Methods: The monthly recorded total number of diphtheria and tetanus toxoids and pertussis vaccine (alone or in combination with the Haemophilus influenzae type b conjugate vaccine) doses administered in a medium-sized city of the Southeast region of Brazil was collected for the period January/2006 through December/2010 from two sources: City level (directly from vaccination rooms, the study "gold standard"), and Federal level (from an Internet platform developed by the country government). Data from these sources were compared using descriptive statistics and the Percentage error. Results: The data values made available by the Internet platform differed from those obtained from the vaccination rooms, with a Percentage error relatively to the actual values in the range [-0.48; 0.39]. Concordant values were observed only in one among the sixty analyzed months (1.66%). Conclusions: A frequent and large difference between the number of diphtheria and tetanus toxoids and pertussis vaccine doses administered in the two levels was detected.
    2015 artigo Brasil acesso aberto