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Francesco Caruso, Giorgio Alessandri, Francesca Ciccarese, Giovanni Cesana, Matteo Uccelli, Giorgio Castello, Roberta Villa, Stefano Olmi
Hepatobiliopancreatic surgery is challenging becouse of the complexity of resections and reconstructions and variability of vascular anatomy. The arterial vascularization of the liver is susteined by the common hepatic artery (CHA) that originates from the celiac trunk (CT). The CHA bifurcates into the gastroduodenal artery (GDA) and proper hepatic artery (PHA) 0.5-1 cm medial to the common bile duct (CBD), and the PHA bifurcates into a right and a left branch at hepatic hilum. The most frequent variants are the right hepatic artery (RHA) from the superior mesenteric artery (SMA), the left hepatic artery (LHA) from the left gastric artery (LGA) or a combination of these two variants...
June 12, 2017: Annali Italiani di Chirurgia
Mircea Muresan, Ovidiu Jimborean, Gabriela Jimborean, Radu Neagoe, Serban Bancu, Muresan Simona, Cristian Borz
INTRODUCTION: In vascular surgery the crossover iliofemoral bypass grafting is a well-known surgical technique. In general surgery the repair of an abdominal defect using a Polypropylene mesh is also a standard procedure. A particular technique is defined by the performance of these 2 separate procedures inside a single operation in which the crossover arterial graft is directed from the retroperitoneal space toward the contra-lateral femoral bifurcation through a Polypropylene mesh which closes the musculoaponeurotic layers of the abdominal wall...
June 8, 2017: Annali Italiani di Chirurgia
Odo Diekmann, Mats Gyllenberg, J A J Metz, Shinji Nakaoka, André M de Roos
No abstract text is available yet for this article.
June 19, 2017: Journal of Mathematical Biology
Sierra N Cullati, Lilian Kabeche, Arminja N Kettenbach, Scott A Gerber
In mitosis, cells undergo a precisely orchestrated series of spatiotemporal changes in cytoskeletal structure to divide their genetic material. These changes are coordinated by a sophisticated network of protein-protein interactions and posttranslational modifications. In this study, we report a bifurcation in a signaling cascade of the NIMA-related kinases (Neks) Nek6, Nek7, and Nek9 that is required for the localization and function of two kinesins essential for cytokinesis, Mklp2 and Kif14. We demonstrate that a Nek9, Nek6, and Mklp2 signaling module controls the timely localization and bundling activity of Mklp2 at the anaphase central spindle...
June 19, 2017: Journal of Cell Biology
Mona Habibi, Jörg Rottler, Steven S Plotkin
Mechanical unfolding of mutated apo, disulfide-reduced, monomeric superoxide dismutase 1 protein (SOD1) has been simulated via force spectroscopy techniques, using both an all-atom (AA), explicit solvent model and a coarse-grained heavy-atom Gō (HA-Gō) model. The HA-Gō model was implemented at two different pulling speeds for comparison. The most-common sequence of unfolding in the AA model agrees well with the most-common unfolding sequence of the HA-Gō model, when the same normalized pulling rate was used...
June 16, 2017: Biochimica et Biophysica Acta
N A Caraballo-Arias, V Ferro
In the past badlands have been often considered as ideal field laboratories for studying landscape evolution because of their geometrical similarity to larger fluvial systems. For a given hydrological process, no scientific proof exists that badlands can be considered a model of river basin prototypes. In this paper the measurements carried out on 45 Sicilian calanchi, a type of badlands that appears as a small-scale hydrographic unit, are used to establish their morphological similarity with river systems whose data are available in the literature...
June 16, 2017: Science of the Total Environment
Nabanita Saikia, Shashi P Karna, Ravindra Pandey
The gas and solvent phase stability of noncanonical (Gua)n nucleobases is investigated in the framework of dispersion-corrected density functional theory (DFT). The calculated results strongly support the high tendency for the dimerization of (Gua)n bases in both gas and solvent phases. An interplay between intermolecular and bifurcated H-bonds is suggested to govern the stability of (Gua)n bases which bears a correlation with the description of dispersion correction terms employed in the DFT calculations. For example, a higher polarity is predicted for (Gua)n bases by the dispersion-corrected DFT in contrast to the non-polar nature of (Gua)3 and (Gua)4 predicted by the hybrid meta-GGA calculations...
June 19, 2017: Physical Chemistry Chemical Physics: PCCP
Sankar Basu, Debasish Mukharjee
There has been considerable debate about the contribution of salt bridges to the stabilization of protein folds, in spite of their participation in crucial protein functions. Salt bridges appear to contribute to the activity-stability trade-off within proteins by bringing high-entropy charged amino acids into close contacts during the course of their functions. The current study analyzes the modes of association of salt bridges (in terms of networks) within globular proteins and at protein-protein interfaces...
July 2017: Journal of Molecular Modeling
Jadranka Stojanovska, El-Sayed H Ibrahim, Aamer R Chughtai, Elizabeth A Jackson, Barry H Gross, Jon A Jacobson, Alexander Tsodikov, Brian Daneshvar, Benjamin D Long, Thomas L Chenevert, Ella A Kazerooni
Intrathoracic fat volume, more specifically, epicardial fat volume, is an emerging imaging biomarker of adverse cardiovascular events. The purpose of this work is to show the feasibility and reproducibility of intrathoracic fat volume measurement applied to contrast-enhanced multidetector computed tomography images. A retrospective cohort study of 62 subjects free of cardiovascular disease (55% females, age = 49 ± 11 years) conducted from 2008 to 2011 formed the study group. Intrathoracic fat volume was defined as all fat voxels measuring -50 to -250 Hounsfield Unit within the intrathoracic cavity from the level of the pulmonary artery bifurcation to the heart apex...
March 2017: Tomography: a Journal for Imaging Research
S Visser, R Nicks, O Faugeras, S Coombes
The Nunez model for the generation of electroencephalogram (EEG) signals is naturally described as a neural field model on a sphere with space-dependent delays. For simplicity, dynamical realisations of this model either as a damped wave equation or an integro-differential equation, have typically been studied in idealised one dimensional or planar settings. Here we revisit the original Nunez model to specifically address the role of spherical topology on spatio-temporal pattern generation. We do this using a mixture of Turing instability analysis, symmetric bifurcation theory, centre manifold reduction and direct simulations with a bespoke numerical scheme...
June 15, 2017: Physica D. Nonlinear Phenomena
Danilo Samuel Jodas, Aledir Silveira Pereira, João Manuel R S Tavares
Image assessment of the arterial system plays an important role in the diagnosis of cardiovascular diseases. The segmentation of the lumen and media-adventitia in intravascular (IVUS) images of the coronary artery is the first step towards the evaluation of the morphology of the vessel under analysis and the identification of possible atherosclerotic lesions. In this study, a fully automatic method for the segmentation of the lumen in IVUS images of the coronary artery is presented. The proposed method relies on the K-means algorithm and the mean roundness to identify the region corresponding to the potential lumen...
June 10, 2017: Medical Image Analysis
Ruie Lu, Sen Yang, Yitong Li, Kaiyun Chen, Yun Jiang, Bi Fu, Yin Zhang, Chao Zhou, Minwei Xu, Xuan Zhou
The glassy transition of superparamagnetic (SPM) (r < r0) nanoparticle systems usually occurs at a very low temperature that greatly limits its application to high temperatures. In this work, we report a spin-glass-like (SGL) behavior near the Curie point (TC), i.e., T0 = 330 K, in La0.67Sr0.33MnO3 (LSMO) nanofibers (NFs) composed of nanoparticles beyond the SPM size (r ≫ r0), resulting in a significant increase of the glass transition temperature. This SGL transition near the TC of bulk LSMO can be explained to be the scenario of locally ordered clusters embedded in a disordered host, in which the assembly of nanoparticles has a magnetic core-shell model driven by surface spin glass...
June 16, 2017: Physical Chemistry Chemical Physics: PCCP
Maxim Kuznetsov, Andrey Kolobov, Andrey Polezhaev
We investigate numerically the behavior of a two-component reaction-diffusion system of Fitzhugh-Nagumo type before the onset of subcritical Turing bifurcation in response to local rigid perturbation. In a large region of parameters, the initial perturbation evolves into a localized structure. In a part of that region, closer to the bifurcation line, this structure turns out to be unstable and covers all the available space over the course of time in a process of self-completion. Depending on the parameter values in two-dimensional (2D) space, this process happens either through generation and evolution of new peaks on oscillatory tails of the initial pattern, or through the elongation, deformation, and rupture of initial structure, leading to space-filling nonbranching snakelike patterns...
May 2017: Physical Review. E
Francesco Marino, Giovanni Giacomelli, Stephane Barland
We investigate the formation of localized domains through front pinning in a periodically forced, bistable semiconductor laser with long-delayed optoelectronic feedback. At difference with 1D spatially extended systems, the transition from the pinning to the propagation regime occurs via two separated bifurcations, each corresponding to the unpinning of one of the fronts surrounding the localized domain. The bifurcation splitting is systematically explored, unveiling the crucial role played by the forcing frequency...
May 2017: Physical Review. E
Jia-Zeng Wang, Rui-Zhen Wang
An analytical steady-state solution of the stochastic model describing the integrated dynamics of the membrane voltage and the gating of a single channel is presented. The voltage density function experiences bifurcation in the parameter space, and the threshold is determined by the comparison between the rates of the voltage evolution and that of the channel gating. It is singular at the reversal potential if the voltage evolves faster than the channel gating. As an application, the entropy production rate associated with the gating currents is calculated; its variation tendency in parameter space is consistent to that of the number of transitions counted from the sample paths...
May 2017: Physical Review. E
Aaron C True, John P Crimaldi
Inhalant flows draw fluid into an orifice from a reservoir and are ubiquitous in engineering and biology. Surprisingly, there is a lack of quantitative information on viscous inhalant flows. We consider here laminar flows (Reynolds number Re≤100) developing after impulsive inhalation begins. We implement finite element simulations of flows with varying Re and extraction height h (orifice height above a bottom bed). Numerical results are experimentally validated using particle image velocimetry measurements in a physical model for a representative flow case in the middle of the Re-h parameter space...
May 2017: Physical Review. E
Janina Hesse, Jan-Hendrik Schleimer, Susanne Schreiber
Prominent changes in neuronal dynamics have previously been attributed to a specific switch in onset bifurcation, the Bogdanov-Takens (BT) point. This study unveils another, relevant and so far underestimated transition point: the saddle-node-loop bifurcation, which can be reached by several parameters, including capacitance, leak conductance, and temperature. This bifurcation turns out to induce even more drastic changes in synchronization than the BT transition. This result arises from a direct effect of the saddle-node-loop bifurcation on the limit cycle and hence spike dynamics...
May 2017: Physical Review. E
S Altmeyer, Richard M Lueptow
We present a numerical study of wavy supercritical cylindrical Couette flow between counter-rotating cylinders in which the wavy pattern propagates either prograde with the inner cylinder or retrograde opposite the rotation of the inner cylinder. The wave propagation reversals from prograde to retrograde and vice versa occur at distinct values of the inner cylinder Reynolds number when the associated frequency of the wavy instability vanishes. The reversal occurs for both twofold and threefold symmetric wavy vortices...
May 2017: Physical Review. E
Gregory P Marchildon, Caroline A Beck, Tarun R Katapally, Sylvia Abonyi, James A Dosman, Jo-Ann Episkenew
BACKGROUND: A complex, poorly understood bifurcated health policy regime exists for Canada's First Nations people for extended health benefits coverage. This research adds to a small body of literature on the regime's impact on access and quality of care and its role in perpetuating health inequities in First Nations populations. METHODS: Using a case study of sleep apnea care in Saskatchewan, we identified issues of health service access and coverage through a literature review of extended benefits programs, legislation and policies and through 10 key informant interviews with federal and provincial extended benefit program administrators and sleep medicine physicians...
May 2017: Healthcare Policy, Politiques de Santé
Gaspar Cano, Rui Dilão
We show that action potentials in the Hodgkin-Huxley neuron model result from a type I intermittency phenomenon that occurs in the proximity of a saddle-node bifurcation of limit cycles. For the Hodgkin-Huxley spatially extended model, describing propagation of action potential along axons, we show the existence of type I intermittency and a new type of chaotic intermittency, as well as space propagating regular and chaotic diffusion waves. Chaotic intermittency occurs in the transition from a turbulent regime to the resting regime of the transmembrane potential and is characterised by the existence of a sequence of action potential spikes occurring at irregular time intervals...
June 14, 2017: Journal of Computational Neuroscience
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