2,532 research outputs found

    Assessment of long-range correlation in animal behaviour time series: the temporal pattern of locomotor activity of Japanese quail (Coturnix coturnix) and mosquito larva (Culex quinquefasciatus)

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    The aim of this study was to evaluate the performance of a classical method of fractal analysis, Detrended Fluctuation Analysis (DFA), in the analysis of the dynamics of animal behavior time series. In order to correctly use DFA to assess the presence of long-range correlation, previous authors using statistical model systems have stated that different aspects should be taken into account such as: 1) the establishment by hypothesis testing of the absence of short term correlation, 2) an accurate estimation of a straight line in the log-log plot of the fluctuation function, 3) the elimination of artificial crossovers in the fluctuation function, and 4) the length of the time series. Taking into consideration these factors, herein we evaluated the presence of long-range correlation in the temporal pattern of locomotor activity of Japanese quail ({\sl Coturnix coturnix}) and mosquito larva ({\sl Culex quinquefasciatus}). In our study, modeling the data with the general ARFIMA model, we rejected the hypothesis of short range correlations (d=0) in all cases. We also observed that DFA was able to distinguish between the artificial crossover observed in the temporal pattern of locomotion of Japanese quail, and the crossovers in the correlation behavior observed in mosquito larvae locomotion. Although the test duration can slightly influence the parameter estimation, no qualitative differences were observed between different test durations

    Fission stories: using PomBase to understand Schizosaccharomyces pombe biology

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    PomBase (www.pombase.org), the model organism database (MOD) for the fission yeast Schizosaccharomyces pombe, supports research within and beyond the S. pombe community by integrating and presenting genetic, molecular, and cell biological knowledge into intuitive displays and comprehensive data collections. With new content, novel query capabilities, and biologist-friendly data summaries and visualization, PomBase also drives innovation in the MOD community

    Effective field approach to the Ising film in a transverse field

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    We study the phase transitions of the spin-1/2 Ising film in a transverse field within the framework of the effective field theory. We evaluate the critical temperature of the film as a function of the exchange interactions, the transverse field and the film thickness. We find that, if the ratio of the surface exchange interactions to the bulk ones R=Js/J is smaller than a critical value Rc, the critical temperature Tc/J of the film is smaller than the bulk critical temperature Tc^B/J and approaches Tc^B/J as R increases further. On the other hand, if R>Rc, Tc/J is larger than both the bulk Tc^B/J and the surface Tc^S/J critical temperatures of the corresponding semi-infinite system, and approaches Tc^S as R increases further.Comment: 16 pages, 5 figures, elsart.cls (included

    Theoretical Study of Fluid Membranes of Spherical Topology with Internal Degrees of Freedom

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    A theoretical study of vesicles of topological genus zero is presented. The bilayer membranes forming the vesicles have various degrees of intrinsic (tangent-plane) orientational order, ranging from smectic to hexatic, frustrated by curvature and topology. The field-theoretical model for these `nn-atic' surfaces has been studied before in the low temperature (mean-field) limit. Work presented here includes the effects of thermal fluctuations. Using the lowest Landau level approximation, the coupling between order and shape is cast in a simple form, facilitating insights into the behaviour of vesicles. The order parameter contains vortices, whose effective interaction potential is found, and renormalized by membrane fluctuations. The shape of the phase space has a counter-intuitive influence on this potential. A criterion is established whereby a vesicle of finite rigidity may be burst by its own in-plane order, and an analogy is drawn with flux exclusion from a type-I superconductor.Comment: 34 pages + 4 Postscript figures. Uses RevTe

    Fetal body MRI and its application to fetal and neonatal treatment: an illustrative review

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    This Review depicts the evolving role of MRI in the diagnosis and prognostication of anomalies of the fetal body, here including head and neck, thorax, abdomen and spine. A review of the current literature on the latest developments in antenatal imaging for diagnosis and prognostication of congenital anomalies is coupled with illustrative cases in true radiological planes with viewable three-dimensional video models that show the potential of post-acquisition reconstruction protocols. We discuss the benefits and limitations of fetal MRI, from anomaly detection, to classification and prognostication, and defines the role of imaging in the decision to proceed to fetal intervention, across the breadth of included conditions. We also consider the current capabilities of ultrasound and explore how MRI and ultrasound can complement each other in the future of fetal imaging

    Tractography of developing white matter of the internal capsule and corpus callosum in very preterm infants

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    To investigate in preterm infants associations between Diffusion Tensor Imaging (DTI) parameters of the posterior limb of the internal capsule (PLIC) and corpus callosum (CC) and age, white matter (WM) injury and clinical factors. In 84 preterm infants DTI was performed between 40-62 weeks postmenstrual age on 3 T MR. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) values and fibre lengths through the PLIC and the genu and splenium were determined. WM injury was categorised as normal/mildly, moderately and severely abnormal. Associations between DTI parameters and age, WM injury and clinical factors were analysed. A positive association existed between FA and age at imaging for fibres through the PLIC (r = 0.48 p < 0.001) and splenium (r = 0.24 p < 0.01). A negative association existed between ADC and age at imaging for fibres through the PLIC (r = -0.65 p < 0.001), splenium (r = -0.35 p < 0.001) and genu (r = -0.53 p < 0.001). No association was found between DTI parameters and gestational age, degree of WM injury or categorical clinical factors. These results indicate that in our cohort of very preterm infants, at this young age, the development of the PLIC and CC is ongoing and independent of the degree of prematurity or WM injury.Neuro Imaging Researc

    Multimodal image analysis of clinical influences on preterm brain development.

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    OBJECTIVE: Premature birth is associated with numerous complex abnormalities of white and gray matter and a high incidence of long-term neurocognitive impairment. An integrated understanding of these abnormalities and their association with clinical events is lacking. The aim of this study was to identify specific patterns of abnormal cerebral development and their antenatal and postnatal antecedents. METHODS: In a prospective cohort of 449 infants (226 male), we performed a multivariate and data-driven analysis combining multiple imaging modalities. Using canonical correlation analysis, we sought separable multimodal imaging markers associated with specific clinical and environmental factors and correlated to neurodevelopmental outcome at 2 years. RESULTS: We found five independent patterns of neuroanatomical variation that related to clinical factors including age, prematurity, sex, intrauterine complications, and postnatal adversity. We also confirmed the association between imaging markers of neuroanatomical abnormality and poor cognitive and motor outcomes at 2 years. INTERPRETATION: This data-driven approach defined novel and clinically relevant imaging markers of cerebral maldevelopment, which offer new insights into the nature of preterm brain injury. Ann Neurol 2017;82:233-246

    Hidden in plain sight: What remains to be discovered in the eukaryotic proteome?

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    The first decade of genome sequencing stimulated an explosion in the characterization of unknown proteins. More recently, the pace of functional discovery has slowed, leaving around 20% of the proteins even in well-studied model organisms without informative descriptions of their biological roles. Remarkably, many uncharacterized proteins are conserved from yeasts to human, suggesting that they contribute to fundamental biological processes. To fully understand biological systems in health and disease, we need to account for every part of the system. Unstudied proteins thus represent a collective blind spot that limits the progress of both basic and applied biosciences. We use a simple yet powerful metric based on Gene Ontology (GO) biological process terms to define characterized and uncharacterized proteins for human, budding yeast, and fission yeast. We then identify a set of conserved but unstudied proteins in S. pombe , and classify them based on a combination of orthogonal attributes determined by large-scale experimental and comparative methods. Finally, we explore possible reasons why these proteins remain neglected and propose courses of action to raise their profile and thereby reap the benefits of completing the catalog of proteins' biological roles

    The Potential Utility for Massage Therapy During Pregnancy to Decrease Stress and Tobacco Use

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    Background: A significant number of women continue to smoke tobacco during pregnancy despite the increased risk of complications to fetal and infant development. Therefore, effective interventions are needed to assist pregnant women with the process of tobacco cessation. Traditional counseling programs have demonstrated some success; however, novel approaches that target stressas a mechanism in the maintenance of addiction would be valuable.Objective: To examine the role of stress in addiction and the utility of massage therapy to decrease stress during pregnancy.Conclusion: Preliminary evidence suggests massage therapy may be beneficial to decreasing tobacco use, and research in pregnant populations is needed
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