327 research outputs found

    Slowdown estimates for one-dimensional random walks in random environment with holding times

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    We consider a one dimensional random walk in random environment that is uniformly biased to one direction. In addition to the transition probability, the jump rate of the random walk is assumed to be spatially inhomogeneous and random. We study the probability that the random walk travels slower than its typical speed and determine its decay rate asymptotic.Comment: 13 pages. There are corrections in the extreme value lemmas and the quenched slowdown estimate

    Color confinement due to topological defects -- restoration of residual gauge symmetries

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    The local gauge symmetry remaining even after imposing a gauge fixing condition is called the residual local gauge symmetry, which is spontaneously broken in the perturbative vacuum, and is expected to be restored in the true confining vacuum. Indeed, the criterion for restoring a special choice of the residual gauge symmetry was shown to be equivalent to the Kugo-Ojima color confinement criterion in the Lorenz gauge. In the previous paper, we demonstrated that such restoration can occur even in the Maximal Abelian gauge due to topological defects. However, it was later found that the topological defects introduced in the previous paper give an infinite Euclidean action and hence do not contribute to the path integral. In this paper, therefore, we reexamine modified topological defects giving a finite Euclidean action to contribute to the path integral. We show the restoration of the residual local gauge symmetry in the Maximal Abelian gauge due to such a class of topological defects.Comment: 17pages, 3figures, minor changes: modified explanations in sect. III and Appendix

    Tailored surface porosities on ceramic foams

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    Novel ceramic foams with tailored surface porosities have been prepared by direct blowing of powder compact, and followed by modulated gas release from the blown bodies. The processing methodologies to produce precisely controlled pore configuration have been discussed in terms of: the direct blowing of powder compacts with a phenoric resin, to form an array of interconnected spherical pores with various unique surfaces comprised of relatively denser, zebra-stripe type (denser and porous) and highly oriented grains, to provide improved mechanical strength and sufficient fluid permeability, that has been created by using one-pot blowing process. These simple and versatile approaches can be used to tailor pore configurations, and fabricate macroporous monoliths with various distinct characteristics

    Successful treatment of ascites accumulation and diarrhea associated with protein-losing enteropathy with oral equine placenta extract supplementation in a dog: A case report

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    Background: Protein-losing enteropathy (PLE) is characterized by leakage of serum proteins into the intestinal lumen, indicating hypoproteinemia. Immunosuppressive agents are the mainstay of treatment, but in many cases, patients are forced to taper off early owing to the induction of liver damage. Case Description: An 8-year-old, non-spayed female Chihuahua presented with diarrhea and ascites effusion lasting 2 weeks. Based on the results of radiography and blood tests, a diagnosis of PLE was made. Prednisolone (3 mg/kg semel in die [SID]) and MitoMax (200 mg/day) were administered, but ascites accumulation and diarrhea did not improve. Thus, azathioprine (2 mg/kg/day) was added, but there was no improvement, and liver damage developed. The liver injury did not improve immediately, but diarrhea and ascites effusion improved after serum total protein and serum albumin levels increased after they had decreased. Subsequent tapering of prednisolone from 3 mg/kg SID to 1 mg/kg SID, combined with MitoMax (200 mg/day) and equine placenta extract (eqPE) (2 ml/day), resulted in no recurrence of ascites or diarrhea. Conclusion: In canine PLE with prolonged diarrhea and ascites effusion, supplementation with eqPE may be considered a reasonable additional therapeutic strategy

    EP2, but not EP4, steadily stimulates the Gαs-protein pathway

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    EP2 and EP4 prostanoid receptors have long been considered to have similar roles, since they are known to couple with Gαs-protein and activate cAMP-mediated signaling pathways. In this study, we re-evaluated the results of cAMP assays with or without phosphodiesterase (PDE) inhibitor pretreatment. Here, we show that in the absence of PDE inhibitor pretreatment, prostaglandin E2 causes accumulation of cAMP in EP2 receptors, whereas markedly low levels of cAMP accumulated in EP4 receptors. By applying the Black/Leff operational model calculation, we found that EP2 receptors have a biased ability to intrinsically activate the Gαs-protein-mediated pathway, whereas EP4 receptors have strong biased activity for the Gαi-protein-mediated pathway. Thus, EP2 and EP4 receptors may not be similar Gαs-coupled receptors but instead substantially different receptors with distinct roles

    Quenched large deviations for multidimensional random walk in random environment with holding times

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    We consider a random walk in random environment with random holding times, that is, the random walk jumping to one of its nearest neighbors with some transition probability after a random holding time. Both the transition probabilities and the laws of the holding times are randomly distributed over the integer lattice. Our main result is a quenched large deviation principle for the position of the random walk. The rate function is given by the Legendre transform of the so-called Lyapunov exponents for the Laplace transform of the first passage time. By using this representation, we derive some asymptotics of the rate function in some special cases.Comment: This is the corrected version of the paper. 24 page

    近赤外線分光法を用いた局所酸素飽和度による熱傷深度測定の検討

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    The burn severity depends on the wound depth and area affected. Hitherto burn depth has been judged mainly by visual observation, although concerns have been raised about its validity. The regional tissue blood flow (rTBF) measured by laser Doppler imaging (LDI) in damaged tissue correlates with the depth. However, very few reports are available on the significance of the regional tissue oxygen saturation (rSO2) as an indicator of burn depth. We investigated whether rSO2 by Near-infrared spectroscopy (NIRS) in burn injuries correlates with rTBF by LDI, which would facilitate quantification of the severity of the tissue damage. Methods: We measured rTBF and rSO2 in 50 lesions from 14 patients of burn injury within 24 hours after injury. The correlation between rTBF and rSO2 was evaluated by Spearman rank correlation analysis. Results: The rSO2 (%; range, 52-82) by NIRS and the rTBF (perfusion unit; range, 61-704) by LDI in burn lesions were positively correlated (r=0.755, p<0.001). This statistically positive correlation still remained significant (r=0.678, p<0.001) after the rSO2 values were standardized. Conclusion: This study suggests that NIRS determination of rSO2 in burn injuries shows promise as a reliable and quick method to estimate the depth of burn lesion.博士(医学)・乙第1343号・平成26年7月22日© 2014 Seki Tadahiko et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Cellular density‐dependent increases in HIF‐1α compete with c‐Myc to down‐regulate human EP4 receptor promoter activity through Sp‐1‐binding region

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    The up‐regulated expression of E‐type prostanoid (EP) 4 receptors has been implicated in carcinogenesis; however, the expression of EP4 receptors has also been reported to be weaker in tumor tissues than in normal tissues. Indeed, EP4 receptors have been suggested to play a role in the maintenance of colorectal homeostasis. This study aimed to examine the underlying mechanisms/reasons for why inconsistent findings have been reported regarding EP4 receptor expression levels in homeostasis and carcinogenesis by focusing on cellular densities. Thus, the human colon cancer HCA‐7 cells, which retain some functional features of normal epithelia, and luciferase reporter genes containing wild‐type or mutated EP4 receptor promoters were used for elucidating the cellular density‐dependent mechanisms about the regulation of EP4 receptor expression. In silico analysis was also utilized for confirming the relevance of the findings with respect to colon cancer development. We here demonstrated that the expression of EP4 receptors was up‐regulated by c‐Myc by binding to Sp‐1 under low cellular density conditions, but was down‐regulated under high cellular density conditions via the increase in the expression levels of HIF‐1α protein, which may pull out c‐Myc and Sp‐1 from DNA‐binding. The tightly regulated EP4 receptor expression mechanism may be a critical system for maintaining homeostasis in normal colorectal epithelial cells. Therefore, once the system is altered, possibly due to the transient overexpression of EP4 receptors, it may result in aberrant cellular proliferation and transformation to cancerous phenotypes. However, at the point, EP4 receptors themselves and their mediated homeostasis would be no longer required
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