42,834 research outputs found

    Vascular challenges from pancreatoduodenectomy in the setting of coeliac artery stenosis

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    Coeliac artery stenosis due to median arcuate ligament compression or atherosclerotic disease is a frequently unrecognised challenge to recovery after pancreatoduodenectomy. The described case illustrates management with intraoperative superior mesenteric artery to hepatic artery bypass graft that led to haemorrhagic challenges postoperatively but ultimately a good recovery. Aspects of preoperative diagnosis, preoperative intervention and intraoperative management options are reviewed. Surgeons need to possess these tools to prevent complications from coeliac artery stenosis when pancreatoduodenectomy is required

    Wavelet Features for Recognition of First Episode of Schizophrenia from MRI Brain Images

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    Machine learning methods are increasingly used in various fields of medicine, contributing to early diagnosis and better quality of care. These outputs are particularly desirable in case of neuropsychiatric disorders, such as schizophrenia, due to the inherent potential for creating a new gold standard in the diagnosis and differentiation of particular disorders. This paper presents a scheme for automated classification from magnetic resonance images based on multiresolution representation in the wavelet domain. Implementation of the proposed algorithm, utilizing support vector machines classifier, is introduced and tested on a dataset containing 104 patients with first episode schizophrenia and healthy volunteers. Optimal parameters of different phases of the algorithm are sought and the quality of classification is estimated by robust cross validation techniques. Values of accuracy, sensitivity and specificity over 71% are achieved

    Potential contributions of noncontact atomic force microscopy for the future Casimir force measurements

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    Surface electric noise, i.e., the non-uniform distribution of charges and potentials on a surface, poses a great experimental challenge in modern precision force measurements. Such a challenge is encountered in a number of different experimental circumstances. The scientists employing atomic force microscopy (AFM) have long focused their efforts to understand the surface-related noise issues via variants of AFM techniques, such as Kelvin probe force microscopy or electric force microscopy. Recently, the physicists investigating quantum vacuum fluctuation phenomena between two closely-spaced objects have also begun to collect experimental evidence indicating a presence of surface effects neglected in their previous analyses. It now appears that the two seemingly disparate science communities are encountering effects rooted in the same surface phenomena. In this report, we suggest specific experimental tasks to be performed in the near future that are crucial not only for fostering needed collaborations between the two communities, but also for providing valuable data on the surface effects in order to draw the most realistic conclusion about the actual contribution of the Casimir force (or van der Waals force) between a pair of real materials.Comment: The paper appeared in the Proceedings to the 12th International Conference on Noncontact Atomic Force Microscopy (NC-AFM 2009) and Casimir 2009 Satellite Worksho

    Formation of small-scale structure in SUSY CDM

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    The lightest supersymmetric particle, most likely the lightest neutralino, is one of the most prominent particle candidates for cold dark matter (CDM). We show that the primordial spectrum of density fluctuations in neutralino CDM has a sharp cut-off, induced by two different damping mechanisms. During the kinetic decoupling of neutralinos, non-equilibrium processes constitute viscosity effects, which damp or even absorb density perturbations in CDM. After the last scattering of neutralinos, free streaming induces neutralino flows from overdense to underdense regions of space. Both damping mechanisms together define a minimal mass scale for perturbations in neutralino CDM, before the inhomogeneities enter the nonlinear epoch of structure formation. We find that the very first gravitationally bound neutralino clouds ought to have masses above 10^{-6} solar masses, which is six orders of magnitude above the mass of possible axion miniclusters.Comment: 7 pages, 3 figures, to appear in proceedings of "IDM 2002, 4th International Workshop on the Identification of Dark Matter

    Occam's razor meets WMAP

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    Using a variety of quantitative implementations of Occam's razor we examine the low quadrupole, the ``axis of evil'' effect and other detections recently made appealing to the excellent WMAP data. We find that some razors {\it fully} demolish the much lauded claims for departures from scale-invariance. They all reduce to pathetic levels the evidence for a low quadrupole (or any other low \ell cut-off), both in the first and third year WMAP releases. The ``axis of evil'' effect is the only anomaly examined here that survives the humiliations of Occam's razor, and even then in the category of ``strong'' rather than ``decisive'' evidence. Statistical considerations aside, differences between the various renditions of the datasets remain worrying

    Effects of weak self-interactions in a relativistic plasma on cosmological perturbations

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    The exact solutions for linear cosmological perturbations which have been obtained for collisionless relativistic matter within thermal field theory are extended to a self-interacting case. The two-loop contributions of scalar λϕ4\lambda\phi^4 theory to the thermal graviton self-energy are evaluated, which give the O(λ)O(\lambda) corrections in the perturbation equations. The changes are found to be perturbative on scales comparable to or larger than the Hubble horizon, but the determination of the large-time damping behavior of subhorizon perturbations requires a resummation of thermally induced masses.Comment: 11 pages, REVTEX, 4 postscript figures included by epsf.sty - expanded version (more details on the resummation of thermal masses which is required for the late-time damping behaviour

    Phase analysis of the cosmic microwave background from an incomplete sky coverage

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    Phases of the spherical harmonic analysis of full-sky cosmic microwave background (CMB) temperature data contain useful information complementary to the ubiquitous angular power spectrum. In this letter we present a new method of phase analysis on incomplete sky maps. It is based on Fourier phases of equal-latitude pixel rings of the map, which are related to the mean angle of the trigonometric moments from the full-sky phases. They have an advantage for probing regions of interest without tapping polluted Galactic plane area, and can localize non-Gaussian features and departure from statistical isotropy in the CMB.Comment: 5 pages, 3 figures submitted to MNRAS Letters, replaced with minor change

    Aminoacyl tRNA synthetase complex interacting multifunctional protein 1 simultaneously binds Glutamyl-Prolyl-tRNA synthetase and scaffold protein aminoacyl tRNA synthetase complex interacting multifunctional protein 3 of the multi-tRNA synthetase complex

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    Higher eukaryotes have developed extensive compartmentalization of amino acid (aa) - tRNA coupling through the formation of a multi-synthetase complex (MSC) that is composed of eight aa-tRNA synthetases (ARS) and three scaffold proteins: aminoacyl tRNA synthetase complex interacting multifunctional proteins (AIMP1, 2 and 3). Lower eukaryotes have a much smaller complex while yeast MSC consists of only two ARS (MetRS and GluRS) and one ARS cofactor 1 protein, Arc1p (Simos et al., 1996), the homolog of the mammalian AIMP1. Arc1p is reported to form a tripartite complex with GluRS and MetRS through association of the N-terminus GST-like domains (GST-L) of the three proteins (Koehler et al., 2013). Mammalian AIMP1 has no GST-L domain corresponding to Arc1p N-terminus. Instead, AIMP3, another scaffold protein of 18 kDa composed entirely of a GST-L domain, interacts with Methionyl-tRNA synthetase (MARS) (Quevillon et al., 1999) and Glutamyl-Prolyl-tRNA Synthetase (EPRS) (Cho et al., 2015). Here we report two new interactions between MSC members: AIMP1 binds to EPRS and AIMP1 binds to AIMP3. Interestingly, the interaction between AIMP1 and AIMP3 complex makes it the functional equivalent of a single Arc1p polypeptide in yeast. This interaction is not mapped to AIMP1 N-terminal coiled-coil domain, but rather requires an intact tertiary structure of the entire protein. Since AIMP1 also interacts with AIMP2, all three proteins appear to compose a core docking structure for the eight ARS in the MSC complex

    Space and time from translation symmetry

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    We show that the notions of space and time in algebraic quantum field theory arise from translation symmetry if we assume asymptotic commutativity. We argue that this construction can be applied to string theory.Comment: 10 pages, Essential changes and additions, in particular, in the discussion of string field theor
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