4,834 research outputs found

    A model for Hopfions on the space-time S^3 x R

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    We construct static and time dependent exact soliton solutions for a theory of scalar fields taking values on a wide class of two dimensional target spaces, and defined on the four dimensional space-time S^3 x R. The construction is based on an ansatz built out of special coordinates on S^3. The requirement for finite energy introduces boundary conditions that determine an infinite discrete spectrum of frequencies for the oscillating solutions. For the case where the target space is the sphere S^2, we obtain static soliton solutions with non-trivial Hopf topological charges. In addition, such hopfions can oscillate in time, preserving their topological Hopf charge, with any of the frequencies belonging to that infinite discrete spectrum.Comment: Enlarged version with the time-dependent solutions explicitly given. One reference and two eps figures added. 14 pages, late

    Like grandparents, like parents: Empirical evidence and psychoanalytic thinking on the transmission of parenting styles

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    The authors discuss the issue of intergenerational transmission of parenting from an empirical and psychoanalytic perspective. After presenting a framework to explain their conception of parenting, they describe intergenerational transmission of parenting as a key to interpreting and eventually changing parenting behaviors. Then they present (1) the empirical approach aimed at determining if there is actually a stability across generations that contributes to harsh parenting and eventually maltreatment and (2) the psyphoanalytic thinking that seeks to explain the continuity in terms of representations and clinical phenomena. The authors also discuss the relationship between the attachment and the caregiving systems and hypothesize a common base for the two systems in childhood experience. Finally, they propose the psychoanalytic perspective as a fruitful theoretical framework to integrate the evidence for the neurophysiological mediators and moderators of intergenerational transmission. Psychoanalytically informed research can provide clinically relevant insights and hypotheses to be tested

    Epiluminescence microscopy for the diagnosis of doubtful melanocytic skin lesions: Comparison of the ABCD rule of dermatoscopy and a new 7-point checklist based on pattern analysis

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    Objective: To compare the reliability of a new 7-point checklist based on simplified epiluminescence microscopy (ELM) pattern analysis with the ABCD rule of dermatoscopy and standard pattern analysis for the diagnosis of clinically doubtful melanocytic skin lesions. Design: In a blind study, ELM images of 342 histologically proven melanocytic skin lesions were evaluated for the presence of 7 standard criteria that we called the 'ELM 7-point checklist.' For each lesion, 'overall' and 'ABCD scored' diagnoses were recorded. From a training set of 57 melanomas and 139 atypical non-melanomas, odds ratios were calculated to create a simple diagnostic model based on identification of major and minor criteria for the '7-point scored' diagnosis. A test set of 60 melanomas and 86 atypical non-melanomas was used for model validation and was then presented to 2 less experienced ELM observers, who recorded the ABCD and 7-point scored diagnoses. Settings: University medical centers. Patients: A sample of patients with excised melanocytic lesions. Main Outcome Measures: Sensitivity, specificity, and accuracy of the models for diagnosing melanoma. Results: From the total combined sets, the 7-point checklist gave a sensitivity of 95% and a specificity of 75% compared with 85% sensitivity and 66% specificity using the ABCD rule and 91% sensitivity and 90% specificity using standard pattern analysis (overall ELM diagnosis). Compared with the ABCD rule, the 7-point method allowed less experienced observers to obtain higher diagnostic accuracy values. Conclusions: The ELM 7-point checklist provides a simplification of standard pattern analysis because of the low number of features to identify and the scoring diagnostic system. As with the ABCD rule, it can be easily learned and easily applied and has proven to be reliable in diagnosing melanoma

    Development and Validation of an Index Based on EAT-Lancet Recommendations: The Planetary Health Diet Index

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    The EAT-Lancet Commission has proposed a planetary health diet. We propose the development of the Planetary Health Diet Index (PHDI) based on this proposed reference diet. We used baseline dietary data obtained through a 114-item FFQ from 14, 779 participants of the Longitudinal Study on Adult Health, a multicenter cohort study conducted in Brazil. The PHDI has 16 components and a score from 0 to 150 points. Validation and reliability analyses were performed, including principal component analyses, association with selected nutrients, differences in means between groups (for example, smokers vs. non-smokers), correlations between components and total energy intake, Cronbach''s alpha, item-item correlations, and linear regression analysis between PHDI with carbon footprint and overall dietary quality. The mean PHDI was 60.4 (95% CI 60.2:60.5). The PHDI had six dimensions, was associated in an expected direction with the selected nutrients and was significantly (p < 0.001) lower in smokers (59.0) than in non-smokers (60.6). Cronbach''s alpha value was 0.51. All correlations between components were low, as well as between components and PHDI with total energy intake. After adjustment for age and sex, the PHDI score remained associated (p < 0.001) with a higher overall dietary quality and lower carbon footprint. Thus, we confirmed the PHDI validity and reliability

    Activation of the motor cortex during phasic rapid eye movement sleep

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    When dreaming during rapid eye movement (REM) sleep, we can perform complex motor behaviors while remaining motionless. How the motor cortex behaves during this state remains unknown. Here, using intracerebral electrodes sampling the human motor cortex in pharmacoresistant epileptic patients, we report a pattern of electroencephalographic activation during REM sleep similar to that observed during the performance of a voluntary movement during wakefulness. This pattern is present during phasic REM sleep but not during tonic REM sleep, the latter resembling relaxed wakefulness. This finding may help clarify certain phenomenological aspects observed in REM sleep behavior disorder

    Soma térmica de fases de desenvolvimento de cultivares de arroz irrigado em função da época de semeadura.

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    O desenvolvimento da planta de arroz é afetado pela temperatura do ar e assim, a influência da temperatura nos processos de desenvolvimento vegetal pode ser expressa pela soma térmica, com unidade graus dia (ºC dia). O objetivo deste trabalho foi determinar a soma térmica de fases de desenvolvimento de quatro cultivares de arroz em três épocas de cultivo. Foi conduzido um experimento na área de várzea do Departamento de Fitotecnia da Universidade Federal de Santa Maria com três datas de semeadura (17/10/2011, 18/11/2011 e 19/12/2011) e quatro cultivares de ciclos distintos: IRGA 421 (ciclo superprecoce), BRS Querência (ciclo precoce), IRGA 424 (ciclo médio) e SCSBRS Tio Taka (ciclo tardio). A duração (º C dia) da fase de emergência - diferenciação de panícula aumentou com o atraso da data de semeadura, enquanto a duração da fase antese ? início da maturação dos grãos foi similar entre as cultivares semeadas no período recomendado pelo zoneamento agrícola
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