390 research outputs found

    Water and the Biology of Prions and Plaques

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    This is an attempt to account for the insolubility and/or aggregation of prions and plaques in terms of a model of water consisting of an equilibrium between high 
density and low density microdomains. Hydrophobic molecules, including proteins, 
accumulate selectively into stable populations, enriched in high density water, at 
charged sites on biopolymers. In enriched high density water, proteins are probably 
partially unfolded and may precipitate out when released. All extracellular matrices 
contain such charged polymers. Prions, which have been shown to accumulate in soils 
and clays containing silicates and aluminates also probably accumulate in 
extracellular matrices. 
 
Release of proteins follows hydrolysis of the charged groups by highly reactive high 
density water. This is normally a slow process but is greatly accelerated by urea. 
Plaques may form with age and disease because of accumulation of urea and, perhaps, 
glucose in the blood. This favours precipitation of proteins emerging from matrices, 
rather than refolding and solution. Dialysis should, therefore, interfere with plaque 
formation and impede the development of some age-related diseases

    The future of citizen science: emerging technologies and shifting paradigms

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    Citizen science creates a nexus between science and education that, when coupled with emerging technologies, expands the frontiers of ecological research and public engagement. Using representative technologies and other examples, we examine the future of citizen science in terms of its research processes, program and participant cultures, and scientific communities. Future citizen‐science projects will likely be influenced by sociocultural issues related to new technologies and will continue to face practical programmatic challenges. We foresee networked, open science and the use of online computer/video gaming as important tools to engage non‐traditional audiences, and offer recommendations to help prepare project managers for impending challenges. A more formalized citizen‐science enterprise, complete with networked organizations, associations, journals, and cyberinfrastructure, will advance scientific research, including ecology, and further public education

    The future of citizen science: emerging technologies and shifting paradigms

    Get PDF
    Citizen science creates a nexus between science and education that, when coupled with emerging technologies, expands the frontiers of ecological research and public engagement. Using representative technologies and other examples, we examine the future of citizen science in terms of its research processes, program and participant cultures, and scientific communities. Future citizen‐science projects will likely be influenced by sociocultural issues related to new technologies and will continue to face practical programmatic challenges. We foresee networked, open science and the use of online computer/video gaming as important tools to engage non‐traditional audiences, and offer recommendations to help prepare project managers for impending challenges. A more formalized citizen‐science enterprise, complete with networked organizations, associations, journals, and cyberinfrastructure, will advance scientific research, including ecology, and further public education

    Intersubject Regularity in the Intrinsic Shape of Human V1

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    Previous studies have reported considerable intersubject variability in the three-dimensional geometry of the human primary visual cortex (V1). Here we demonstrate that much of this variability is due to extrinsic geometric features of the cortical folds, and that the intrinsic shape of V1 is similar across individuals. V1 was imaged in ten ex vivo human hemispheres using high-resolution (200 ÎŒm) structural magnetic resonance imaging at high field strength (7 T). Manual tracings of the stria of Gennari were used to construct a surface representation, which was computationally flattened into the plane with minimal metric distortion. The instrinsic shape of V1 was determined from the boundary of the planar representation of the stria. An ellipse provided a simple parametric shape model that was a good approximation to the boundary of flattened V1. The aspect ration of the best-fitting ellipse was found to be consistent across subject, with a mean of 1.85 and standard deviation of 0.12. Optimal rigid alignment of size-normalized V1 produced greater overlap than that achieved by previous studies using different registration methods. A shape analysis of published macaque data indicated that the intrinsic shape of macaque V1 is also stereotyped, and similar to the human V1 shape. Previoud measurements of the functional boundary of V1 in human and macaque are in close agreement with these results

    Pengaruh Kompetensi dan Pengembangan Karir terhadap Kepuasan Kerja dengan Komitmen Organisasional sebagai Variabel Mediasi (Studi Pegawai Politeknik Ilmu Pelayaran ( Pip ) Semarang)

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    An organization would expect the productivity of its employees for the achievement of organizational goals. Work productivity is seen as the ability of employees to achieve the desired results, in achieving the desired results would require a positive work attitude of employees. Therefore it is expected for the organization must be aware and create a management system that takes into account the factors that affect the work attitude of employees in order to achieve the goals of the organization itself. The purpose of this study was to analyze the effect of competence and career development to organizational commitment in the EmployeeSeamanshipPolytechnicSemarang. To analyze the effect of competence, career development and organizational commitment to job satisfaction within the Employee Seamanship Polytechnic Semarang. To analyze the effect of competence and career development to job satisfaction and organizational commitment in environmental mediation Employee Seamanship Polytechnic Semarang.In this studytook thepopulationin this studywere employees ofthe PolytechnicSemarangSeamanship, amounting to 218 persons. Sampling with random samplingtechniquethatrandomlysampling142respondents. Keywords: competence, career development, organizational commitment and job satisfactio

    Automated Segmentation of Hippocampal Subfields From Ultra-High Resolution In Vivo MRI

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    Recent developments in MRI data acquisition technology are starting to yield images that show anatomical features of the hippocampal formation at an unprecedented level of detail, providing the basis for hippocampal subfield measurement. However, a fundamental bottleneck in MRI studies of the hippocampus at the subfield level is that they currently depend on manual segmentation, a laborious process that severely limits the amount of data that can be analyzed. In this article, we present a computational method for segmenting the hippocampal subfields in ultra-high resolution MRI data in a fully automated fashion. Using Bayesian inference, we use a statistical model of image formation around the hippocampal area to obtain automated segmentations. We validate the proposed technique by comparing its segmentations to corresponding manual delineations in ultra-high resolution MRI scans of 10 individuals, and show that automated volume measurements of the larger subfields correlate well with manual volume estimates. Unlike manual segmentations, our automated technique is fully reproducible, and fast enough to enable routine analysis of the hippocampal subfields in large imaging studies.National Institutes of Health (U.S.) (NIH NCRR; Grant number: P41-RR14075)National Institutes of Health (U.S.) (Grant R01 RR16594-01A1)National Institutes of Health (U.S.) (Grant NAC P41-RR13218)Biomedical Informatics Research Network (BIRN002)Biomedical Informatics Research Network (U24 RR021382)National Institute of Biomedical Imaging and Bioengineering (U.S.) (R01 EB001550)National Institute of Biomedical Imaging and Bioengineering (U.S.) (R01EB006758)National Institute of Biomedical Imaging and Bioengineering (U.S.) (NAMIC U54-EB005149)National Institute of Neurological Disorders and Stroke (U.S.) (R01 NS052585-01)National Institute of Neurological Disorders and Stroke (U.S.) (R01 NS051826)Mental Illness and Neuroscience Discovery (MIND) InstituteEllison Medical Foundation (Autism & Dyslexia Project

    Renormalization-group Method for Reduction of Evolution Equations; invariant manifolds and envelopes

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    The renormalization group (RG) method as a powerful tool for reduction of evolution equations is formulated in terms of the notion of invariant manifolds. We start with derivation of an exact RG equation which is analogous to the Wilsonian RG equations in statistical physics and quantum field theory. It is clarified that the perturbative RG method constructs invariant manifolds successively as the initial value of evolution equations, thereby the meaning to set t0=tt_0=t is naturally understood where t0t_0 is the arbitrary initial time. We show that the integral constants in the unperturbative solution constitutes natural coordinates of the invariant manifold when the linear operator AA in the evolution equation has no Jordan cell; when AA has a Jordan cell, a slight modification is necessary because the dimension of the invariant manifold is increased by the perturbation. The RG equation determines the slow motion of the would-be integral constants in the unperturbative solution on the invariant manifold. We present the mechanical procedure to construct the perturbative solutions hence the initial values with which the RG equation gives meaningful results. The underlying structure of the reduction by the RG method as formulated in the present work turns out to completely fit to the universal one elucidated by Kuramoto some years ago. We indicate that the reduction procedure of evolution equations has a good correspondence with the renormalization procedure in quantum field theory; the counter part of the universal structure of reduction elucidated by Kuramoto may be the Polchinski's theorem for renormalizable field theories. We apply the method to interface dynamics such as kink-anti-kink and soliton-soliton interactions in the latter of which a linear operator having a Jordan-cell structure appears.Comment: 67 pages. No figures. v2: Additional discussions on the unstable motion in the the double-well potential are given in the text and the appendix added. Some references are also added. Introduction is somewhat reshape
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