4,975 research outputs found

    Scaling limit for a drainage network model

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    We consider the two dimensional version of a drainage network model introduced by Gangopadhyay, Roy and Sarkar, and show that the appropriately rescaled family of its paths converges in distribution to the Brownian web. We do so by verifying the convergence criteria proposed by Fontes, Isopi, Newman and Ravishankar.Comment: 15 page

    Non-Equilibrium Modeling of the Fe XVII 3C/3D ratio for an Intense X-ray Free Electron Laser

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    We present a review of two methods used to model recent LCLS experimental results for the 3C/3D line intensity ratio of Fe XVII (Bernitt et al. 2012), the time-dependent collisional-radiative method and the density-matrix approach. These are described and applied to a two-level atomic system excited by an X-ray free electron laser. A range of pulse parameters is explored and the effects on the predicted Fe XVII 3C and 3D line intensity ratio are calculated. In order to investigate the behavior of the predicted line intensity ratio, a particular pair of A-values for the 3C and 3D transitions was chosen (2.22 ×\times 1013^{13} s1^{-1} and 6.02 ×\times 1012^{12} s1^{-1} for the 3C and 3D, respectively), but our conclusions are independent of the precise values. We also reaffirm the conclusions from Oreshkina et al.(2014, 2015): the non-linear effects in the density matrix are important and the reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to the laser pulse parameters, namely pulse duration, pulse intensity, and laser bandwidth. It is also shown that for both models the lowering of the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio has a significant contribution due to the emission from the plasma after the laser pulse has left the plasma volume. Laser intensities above 1×1012\sim 1\times 10^{12} W/cm2^{2} are required for a reduction in the 3C/3D line intensity ratio below the expected time independent oscillator strength ratio

    Contact process under renewals I

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    Motivated by questions regarding long range percolation, we investigate a non-Markovian analogue of the Harris contact process in Zd\mathbb{Z}^d: an individual is attached to each site xZdx \in \mathbb{Z}^d, and it can be infected or healthy; the infection propagates to healthy neighbors just as in the usual contact process, according to independent exponential times with a fixed rate λ\lambda; nevertheless, the possible recovery times for an individual are given by the points of a renewal process with heavy tail; the renewal processes are assumed to be independent for different sites. We show that the resulting processes have a critical value equal to zero.Comment: 13 page

    Sistemas de produção de mudas de coqueiro.

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    Neste trabalho são apresentados algumas considerações a respeito das vantagens e desvantagens observadas para utilização dos dois sistemas, cabendo ao produtor a opção por aquele que melhor se adapte as considerações locais

    Produção integrada de coco: normas técnicas específicas e documentos de acompanhamento.

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    Apresenta as normas técnicas para produção do coco.bitstream/item/26591/1/doc-71.pdfISSN 1517-1329

    Produção de mudas de coqueiros, Cocos nucifera L., pelo sistema alternativo.

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    Apresenta método de produção alternativa de mudas de coqueiro.bitstream/item/81099/1/CPATC-COM.-TEC.-22-98.pd

    Reliability and validity of the Pittsburgh Sleep Quality Index in breast cancer patients

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    Purpose: We aimed to assess the factor structure, internal consistency, test-retest reliability, and construct validity of the European Portuguese version of the Pittsburgh Sleep Quality Index (PSQI) in breast cancer patients. Methods: This study was based on a cohort of breast cancer patients, among whom the PSQI was used to measure sleep quality three years after cancer diagnosis (N = 474). A sample of 62 participants underwent additional PSQI testing, wore a wrist actigraph for five consecutive days, and was reevaluated with the PSQI after one month. A confirmatory factor analysis, considering the components suggested by the principal component analysis (PCA), was performed to determine model fit. To evaluate internal consistency and test-retest reliability, Cronbach’s alpha and intraclass correlation coefficient (ICC) were calculated, respectively. To assess construct validity, Spearman’s correlation coefficients were computed between PSQI scores and actigraphy measures and other theoretical related constructs. Results: PCA suggested one or two components. The latter showed better fit to the data, though the two factors were strongly correlated (r = 0.76) and internal consistency was not satisfactory for one of the factors. Regarding the one-factor model, internal consistency (Cronbach’s alpha = 0.70) and test-retest reliability (ICC = 0.76) were adequate. Sleep duration, habitual sleep efficiency, and sleep disturbance dimensions were significantly correlated with the corresponding actigraphy measures; the PSQI global score derived from the one-factor model was more strongly correlated with subjective sleep complaints (r ≥ 0.60). Conclusions: The unidimensional construct of the European Portuguese version of the PSQI showed adequate reliability and validity among breast cancer patients.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalization (POCI-01-0145-FEDER-016867) and national funding from the Foundation for Science and Technology (FCT) (Portuguese Ministry of Science, Technology and Higher Education) (PTDC/DTP-EPI/7283/2014) under the Unidade de Investigação em Epidemiologia - Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref.UID/DTP/04750/2013); the PhD Grant SFRH/BD/92630/2013 (Filipa Fontes) co-funded by the FCT and the POPH/FSE Program

    Trajectories of sleep quality during the first three years after breast cancer diagnosis

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    Objective: To identify trajectories of sleep quality up to three years after breast cancer diagnosis and to assess differences in characteristics of patients across distinct trajectories. Methods: A total of 458 breast cancer patients underwent a neurological evaluation before treatment and at one and three years after diagnosis. Clinical data were obtained throughout the follow-up. Anxiety and depression were evaluated at baseline, using the Hospital Anxiety and Depression Scale. In all sessions of follow-up, sleep quality was assessed using the Pittsburgh Sleep Quality Index. Model-based clustering was used to identify groups of patients with homogeneous variation in sleep quality. Results: We identified three trajectories of variation in sleep quality, named “low” (LSQ), “medium” (MSQ), and “high sleep quality” (HSQ). Women in the HSQ trajectory presented good sleep quality during the three years. LSQ and MSQ trajectories were characterized by poor sleep quality during the whole period, although during the first year the latter depicted a significant deterioration of sleep quality and the former a significant improvement. Patients included in the LSQ trajectory were more likely to have clinically significant anxiety and depression at baseline. The two trajectories with worse sleep quality were associated with neuropathic pain three years after cancer diagnosis. Conclusions: This study provides a model for describing the variation in sleep quality during the first three years after breast cancer diagnosis, based on three main trajectories. Further studies are needed understanding the heterogeneity of the individual trajectories within each of these major patterns of variation.This study was funded by FEDER through the Operational Programme Competitiveness and Internationalization (POCI-01-0145-FEDER-016867) and national funding from the Foundation for Science and Technology – FCT (Portuguese Ministry of Science, Technology and Higher Education) (PTDC/DTP-EPI/7283/2014) under the Unidade de Investigação em Epidemiologia - Instituto de Saúde Pública da Universidade do Porto (EPIUnit) (POCI-01-0145-FEDER-006862; Ref.UID/DTP/04750/2013); the PhD Grant SFRH/BD/92630/2013 (Filipa Fontes) co-funded by the FCT and the POPH/FSE Program. Data management activities up to the first year of follow-up were supported by the Chair on Pain Medicine of the Faculty of Medicine, University of Porto and by the Grünenthal Foundation – Portugal
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