514 research outputs found

    Percolation Transition in the Heterogeneous Vortex State in NbSe2

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    A percolation transition in the vortex state of a superconducting 2H-NbSe2 crystal is observed in the regime where vortices form a heterogeneous phase consisting of ordered and disordered domains. The transition is signaled by a sharp increase in critical current that occurs when the volume fraction of disordered domains, obtained from pulsed measurements of the current-voltage characteristics, reaches the value Pc= 0.26. Measurements on different vortex states show that while the temperature of the transition depends on history and measurement speed, the value of Pc and the critical exponent characterizing the approach to it, r =1.97 Ā±\pm 0.66, are universal

    Soft-tissue material properties and mechanogenetics during cardiovascular development.

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    During embryonic development, changes in the cardiovascular microstructure and material properties are essential for an integrated biomechanical understanding. This knowledge also enables realistic predictive computational tools, specifically targeting the formation of congenital heart defects. Material characterization of cardiovascular embryonic tissue at consequent embryonic stages is critical to understand growth, remodeling, and hemodynamic functions. Two biomechanical loading modes, which are wall shear stress and blood pressure, are associated with distinct molecular pathways and govern vascular morphology through microstructural remodeling. Dynamic embryonic tissues have complex signaling networks integrated with mechanical factors such as stress, strain, and stiffness. While the multiscale interplay between the mechanical loading modes and microstructural changes has been studied in animal models, mechanical characterization of early embryonic cardiovascular tissue is challenging due to the miniature sample sizes and active/passive vascular components. Accordingly, this comparative review focuses on the embryonic material characterization of developing cardiovascular systems and attempts to classify it for different species and embryonic timepoints. Key cardiovascular components including the great vessels, ventricles, heart valves, and the umbilical cord arteries are covered. A state-of-the-art review of experimental techniques for embryonic material characterization is provided along with the two novel methods developed to measure the residual and von Mises stress distributions in avian embryonic vessels noninvasively, for the first time in the literature. As attempted in this review, the compilation of embryonic mechanical properties will also contribute to our understanding of the mature cardiovascular system and possibly lead to new microstructural and genetic interventions to correct abnormal development

    Amniotic membrane transplantation for wound dehiscence after deep lamellar keratoplasty: a case report

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    <p>Abstract</p> <p>Purpose</p> <p>To report amniotic membrane (AM) transplantation in a patient with wound dehiscence 5 months after deep lamellar keratoplasty (DLKP)</p> <p>Methods</p> <p>The patient was an 84-year-old Japanese man who had undergone right DLKP 5 months earlier for central corneal scarring due to recurrent stromal herpetic keratitis. He developed wound dehiscence with corneal stromal melting due to recurrence of stromal herpes in both the donor and recipient sites. "AM roll-in filling technique" and AM patching were performed.</p> <p>Results</p> <p>Following AM transplantation, stromal inflammation subsided and complete epithelization occurred within 10 days of surgery.</p> <p>At 8 months postoperatively, biomicroscopy revealed stable wound apposition or stromal gain. Following AM transplantation, stromal inflammation subsided and complete epithelialization was achieved within 10 days after surgery.</p> <p>Conclusion</p> <p>AM transplantation may offer an effective treatment modality for herpetic corneal wound dehiscence after DLKP.</p

    An efficient computational method for a stochastic dynamic lot-sizing problem under service-level constraints

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    We provide an efficient computational approach to solve the mixed integer programming (MIP) model developed by Tarim and Kingsman [8] for solving a stochastic lot-sizing problem with service level constraints under the staticā€“dynamic uncertainty strategy. The effectiveness of the proposed method hinges on three novelties: (i) the proposed relaxation is computationally efficient and provides an optimal solution most of the time, (ii) if the relaxation produces an infeasible solution, then this solution yields a tight lower bound for the optimal cost, and (iii) it can be modified easily to obtain a feasible solution, which yields an upper bound. In case of infeasibility, the relaxation approach is implemented at each node of the search tree in a branch-and-bound procedure to efficiently search for an optimal solution. Extensive numerical tests show that our method dominates the MIP solution approach and can handle real-life size problems in trivial time. -------------------------------------------------------------------------------

    Betatrophin levels are related to the early histological findings in nonalcoholic fatty liver disease

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    Betatrophin, a liver hormone, regulates glucose and lipid metabolism. We investigated the betatrophin levels in nonalcoholic fatty liver disease (NAFLD) and searched for any relationship with histological severity and metabolic parameters. Fifty males with NAFLD [Nonalcoholic Steatohepati-tis (NASH) (n = 32); non-NASH (n = 18)] and 30 healthy controls were included. Plasma betatrophin was measured by ELISA method. Insulin sensitivity was assessed by HOMA-IR index. Histological features were scored by the semi quantitative classification and combined as the NAFLD activity score (NAS). Betatrophin levels in the non-NASH group were significantly higher than the controls. Betatrophin was positively correlated to the age, waist circumference, total cholesterol, triglycerides, LDL cholesterol, glucose, insulin, HOMA-IR index and gamma glutamyl transpeptidase levels, and negatively correlated to the steatosis and NAS. In the stepwise linear regression analysis, the triglyceride (Ī² = 0.457, p &lt; 0.001), glucose (Ī² = 0.281, p = 0.02) and NAS (Ī² = āˆ’0.260, p = 0.03) were the independent determinants of betatrophin. Betatrophin levels are higher in the early stages of NAFLD and tend to decrease when the disease progresses. This could be an important preliminary mechanistic finding to explain the increased frequency of glucose intolerance during the course of NAFLD
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