248 research outputs found

    Modeling environmental responses of plantassociations by fuzzy set theory

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    A method for studying the response of vegetation to environmental gradients, based on the community niche and fuzzy set theory, is presented. The approach is illustrated using an example from perennial halophilous vegetation along the Northern Adriatic coast of Italy. Compatibility curves are obtained by fuzzy set theoretical methods, and are used tomodel the response functions of plant associations to environmental gradients, including soil and ground water salinity, soil pH, soil and ground water temperature, percentage of sand, and variations in the ground water level. The compatibility curves summarize the similarity of a given plant community, with a particular value of an environmental variable, to the species combination of a given plant association. Compatibility curves offer an alternative approach to non-linear regression and best fit analyses normally used to model single species responses to environmental gradients. The approach is particularly useful given there is no singlemechanisticmodel that can capture the exact shape of the functional response along environmental gradients, and given that environmental data are commonly affected by high levels of noise

    Kinetics of Rhodopsin Deactivation and Its Role in Regulating Recovery and Reproducibility of Rod Photoresponse

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    The single photon response (SPR) in vertebrate phototransduction is regulated by the dynamics of R* during its lifetime, including the random number of phosphorylations, the catalytic activity and the random sojourn time at each phosphorylation level. Because of this randomness the electrical responses are expected to be inherently variable. However the SPR is highly reproducible. The mechanisms that confer to the SPR such a low variability are not completely understood. The kinetics of rhodopsin deactivation is investigated by a Continuous Time Markov Chain (CTMC) based on the biochemistry of rhodopsin activation and deactivation, interfaced with a spatio-temporal model of phototransduction. The model parameters are extracted from the photoresponse data of both wild type and mutant mice, having variable numbers of phosphorylation sites and, with the same set of parameters, the model reproduces both WT and mutant responses. The sources of variability are dissected into its components, by asking whether a random number of turnoff steps, a random sojourn time between steps, or both, give rise to the known variability. The model shows that only the randomness of the sojourn times in each of the phosphorylated states contributes to the Coefficient of Variation (CV) of the response, whereas the randomness of the number of R* turnoff steps has a negligible effect. These results counter the view that the larger the number of decay steps of R*, the more stable the photoresponse is. Our results indicate that R* shutoff is responsible for the variability of the photoresponse, while the diffusion of the second messengers acts as a variability suppressor

    Pedestrians moving in dark: Balancing measures and playing games on lattices

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    We present two conceptually new modeling approaches aimed at describing the motion of pedestrians in obscured corridors: * a Becker-D\"{o}ring-type dynamics * a probabilistic cellular automaton model. In both models the group formation is affected by a threshold. The pedestrians are supposed to have very limited knowledge about their current position and their neighborhood; they can form groups up to a certain size and they can leave them. Their main goal is to find the exit of the corridor. Although being of mathematically different character, the discussion of both models shows that it seems to be a disadvantage for the individual to adhere to larger groups. We illustrate this effect numerically by solving both model systems. Finally we list some of our main open questions and conjectures

    Mortality reduction with use of oral beta-blockers in patients with acute coronary syndrome

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    OBJECTIVES: Recent studies have revealed a relationship between beta-blocker use and worse prognosis in acute coronary syndrome, mainly due to a higher incidence of cardiogenic shock. However, the relevance of this relationship in the reperfusion era is unknown. The aim of this study was to analyze the outcomes of patients with acute coronary syndrome that started oral beta-blockers within the first 24 hours of hospital admission (group I) compared to patients who did not use oral beta-blockers in this timeframe (group II). METHODS: This was an observational, retrospective and multicentric study with 2,553 patients (2,212 in group I and 341 in group II). Data regarding demographic characteristics, coronary treatment and medication use in the hospital were obtained. The primary endpoint was in-hospital all-cause mortality. The groups were compared by ANOVA and the chi-square test. Multivariate analysis was conducted by logistic regression and results were considered significant when

    Sexual life and dysfunction after maternal morbidity: A systematic review

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    © 2015 Andreucci et al. Background: Because there is a lack of knowledge on the long-term consequences of maternal morbidity/near miss episodes on women's sexual life and function we conducted a systematic review with the purpose of identifying the available evidence on any sexual impairment associated with complications from pregnancy and childbirth. Methods: Systematic review on aspects of women sexual life after any maternal morbidity and/or maternal near miss, during different time periods after delivery. The search was carried out until May 22nd, 2015 including studies published from 1995 to 2015. No language or study design restrictions were applied. Maternal morbidity as exposure was split into general or severe/near miss. Female sexual outcomes evaluated were dyspareunia, Female Sexual Function Index (FSFI) scores and time to resume sexual activity after childbirth. Qualitative syntheses for outcomes were provided whenever possible. Results: A total of 2,573 studies were initially identified, and 14 were included for analysis after standard selection procedures for systematic review. General morbidity was mainly related to major perineal injury (3rd or 4th degree laceration, 12 studies). A clear pattern for severity evaluation of maternal morbidity could not be distinguished, unless when a maternal near miss concept was used. Women experiencing maternal morbidity had more frequently dyspareunia and resumed sexual activity later, when compared to women without morbidity. There were no differences in FSFI scores between groups. Meta-analysis could not be performed, since included studies were too heterogeneous regarding study design, evaluation of exposure and/or outcome and time span. Conclusion: Investigation of long-term repercussions on women's sexual life aspects after maternal morbidity has been scarcely performed, however indicating worse outcomes for those experiencing morbidity. Further standardized evaluation of these conditions among maternal morbidity survivors may provide relevant information for clinical follow-up and reproductive planning for women

    Validation of the WHO Disability Assessment Schedule (WHODAS 2.0) 12-item tool against the 36-item version for measuring functioning and disability associated with pregnancy and history of severe maternal morbidity

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    © 2018 World Health Organization; licensed by John Wiley & Sons Ltd on behalf of International Federation of Gynecology and Obstetrics. Objective: To validate the WHO Disability Assessment Schedule 2.0 (WHODAS 2.0) 12-item tool against the 36-item version for measuring functioning and disability associated with pregnancy and the occurrence of maternal morbidity. Methods: This is a secondary analysis of the Brazilian retrospective cohort study on long-term repercussions of severe maternal morbidity (SMM) among women who delivered at a tertiary facility (COMMAG study). We compared WHODAS-12 and WHODAS-36 scores of women with and without SMM using measures of central tendency and variability, tests for instruments’ agreement (Bland-Altman plot), confirmatory factor analysis (CFA), and Cronbach alpha coefficient for internal consistency. Results: The COMMAG study enrolled 638 women up to 5 years postpartum. Although the median WHODAS-36 and -12 scores for all women were statistically different (13.04 and 11.76, respectively; P<0.001), there was a strong linear correlation between them. Furthermore, the mean difference and the differences in variance analyses demonstrated agreement of total scores between the two versions. CFA demonstrated how the WHODAS-12 questions are divided into six previously defined factors and Cronbach alpha showed good internal consistency. Conclusion: WHODAS-12 demonstrated agreement with WHODAS-36 for total score and was a good instrument for screening functioning and disability among postpartum women, with and without SMM
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