Numerical Simulation of Multicrack Propagation Behaviour in Steel Structure

This paper describes the numerical simulation method of the multi-crack propagation behaviour which appear in a part of civil engineering structures with complex geometrical configuration like steel bridges. Proposed method can treat the interaction of several cracks which locate in a short distance each other, and the process of their growth can be grasped. The method is based on the finite element method, and the linear fracture mechanics is assumed. Proposed method includes following tools for the simulation of the crack propagation behaviour: Automatic Mesh Generators for 3-D, 2-D structural analysis, and 2-D crack propagation analysis, Multi-level Structural Analysis Technique, Estimation Method of the crack growth and the angle of cracks and the modelling method of traffic loadings. The validity of the method is investigated by comparing the result to the experimental one

The Formation and Destruction of Molecular Clouds and Galactic Star Formation

We describe an overall picture of galactic-scale star formation. Recent high-resolution magneto-hydrodynamical simulations of two-fluid dynamics with cooling/heating and thermal conduction have shown that the formation of molecular clouds requires multiple episodes of supersonic compression. This finding enables us to create a scenario in which molecular clouds form in interacting shells or bubbles on a galactic scale. First we estimate the ensemble-averaged growth rate of molecular clouds over a timescale larger than a million years. Next we perform radiation hydrodynamics simulations to evaluate the destruction rate of magnetized molecular clouds by the stellar FUV radiation. We also investigate the resultant star formation efficiency within a cloud which amounts to a low value (a few percent) if we adopt the power-law exponent -2.5 for the mass distribution of stars in the cloud. We finally describe the time evolution of the mass function of molecular clouds over a long timescale (>1Myr) and discuss the steady state exponent of the power-law slope in various environments.Comment: 7 pages, 3 figures. Accepted for publication in Astronomy and Astrophysic

Hepatocyte growth factor ameliorates dermal sclerosis in the tight-skin mouse model of scleroderma

The tight-skin (TSK/+) mouse, a genetic model of systemic sclerosis (SSc), develops cutaneous fibrosis and defects in pulmonary architecture. Because hepatocyte growth factor (HGF) is an important mitogen and morphogen that contributes to the repair process after tissue injury, we investigated the role of HGF in cutaneous fibrosis and pulmonary architecture defects in SSc using TSK/+ mice. TSK/+ mice were injected in the gluteal muscle with either hemagglutinating virus of Japan (HVJ) liposomes containing 8 μg of a human HGF expression vector (HGF-HVJ liposomes) or a mock vector (untreated control). Gene transfer was repeated once weekly for 8 weeks. The effects of HGF gene transfection on the histopathology and expression of tumor growth factor (TGF)-β and IL-4 mRNA in TSK/+ mice were examined. The effect of recombinant HGF on IL-4 production by TSK/+ CD4(+ )T cells stimulated by allogeneic dendritic cells (DCs) in vitro was also examined. Histologic analysis revealed that HGF gene transfection in TSK/+ mice resulted in a marked reduction of hypodermal thickness, including the subcutaneous connective tissue layer. The hypodermal thickness of HGF-treated TSK/+ mice was decreased two-fold to three-fold compared with untreated TSK/+ mice. However, TSK/+ associated defects in pulmonary architecture were unaffected by HGF gene transfection. HGF gene transfection significantly inhibited the expression of IL-4 and TGF-β1 mRNA in the spleen and skin but not in the lung. We also performed a mixed lymphocyte culture and examined the effect of recombinant HGF on the generation of IL-4. Recombinant HGF significantly inhibited IL-4 production in TSK/+ CD4(+ )T cells stimulated by allogeneic DCs. HGF gene transfection inhibited IL-4 and TGF-β mRNA expression, which has been postulated to have a major role in fibrinogenesis and reduced hypodermal thickness, including the subcutaneous connective tissue layer of TSK/+ mice. HGF might represent a novel strategy for the treatment of SSc

Successful closure of large blunt macular chorioretinal rupture: a case report

The authors present a rare case of large chorioretinal rupture caused by blunt traumatic injury of the globe. A 22-year-old woman sustained a blunt injury to her left eye. The best-corrected Snellen visual acuity was 2/20 in her left eye, and hyphema and vitreous hemorrhage were noted. The day after the injury occurred the vitreous hemorrhage had disappeared. Fundus examination revealed a crescent-shaped retinal rupture three disc diameters in size near the macula, and a choroidal rupture six disc diameters in size that was over the vascular arcade. Three days after the injury, vitrectomy with internal limiting membrane peeling was performed. Postoperative prone positioning was maintained for 4 days. Five days postoperatively, closure of the ruptured retina was confirmed. The visual acuity improved to 16/20 4 months after surgery and this was maintained over a 48-month period. In conclusion, early vitrectomy with internal limiting membrane peeling after injury was effective for a case involving severe blunt chorioretinal rupture with closed globe injury

Hepatocyte growth factor prevents lupus nephritis in a murine lupus model of chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) induced in (C57BL/6 × DBA/2) F1 (BDF1) mice by the injection of DBA/2 mouse spleen cells represents histopathological changes associated with systemic lupus erythematosus (SLE), primary biliary cirrhosis (PBC) and Sjogren's syndrome (SS), as indicated by glomerulonephritis, lymphocyte infiltration into the periportal area of the liver and salivary glands. We determined the therapeutic effect of hepatocyte growth factor (HGF) gene transfection on lupus using this chronic GVHD model. Chronic GVHD mice were injected in the gluteal muscle with either HVJ liposomes containing 8 μg of the human HGF expression vector (HGF-HVJ liposomes) or mock vector (untreated control). Gene transfer was repeated at 2-week intervals during 12 weeks. HGF gene transfection effectively prevented the proteinuria and histopathological changes associated with glomerulonephritis. While liver and salivary gland sections from untreated GVHD mice showed prominent PBC- and SS-like changes, HGF gene transfection reduced these histopathological changes. HGF gene transfection greatly reduced the number of splenic B cells, host B cell major histocompatibility complex class II expression, and serum levels of IgG and anti-DNA antibodies. IL-4 mRNA expression in the spleen, liver, and kidneys was significantly decreased by HGF gene transfection. CD28 expression on DBA/2 CD4+ T cells was decreased by the addition of recombinant HGF in vitro. Furthermore, IL-4 production by DBA/2 CD4+ T cells stimulated by irradiated BDF1 dendritic cells was significantly inhibited by the addition of recombinant HGF in vitro. These results suggest that HGF gene transfection inhibited T helper 2 immune responses and reduced lupus nephritis, autoimmune sialoadenitis, and cholangitis in chronic GVHD mice. HGF may represent a novel strategy for the treatment of SLE, SS and PBC

Paving ways to documenting an invisible linguistic minority in Japan: Ikema

This presentation introduces our collaborative project (involving researchers from Canada, Japan, and the U.S.) on the language of Ikema in Okinawa, Japan. We highlight the problems we encountered and our attempts to overcome them - a necessary step before engaging in “Documentary Linguistics” (Himmelmann 1998) on Ikema. Ikema is a typical endangered language: no longer acquired by children and only spoken by a decreasing number of older speakers. Islanders express concerns that their mother tongue is disappearing, but most feel that the move toward monolingualism in Standard Japanese is inevitable and even desirable. This is an expected outcome; although, linguistically speaking, Ikema and other Okinawan languages should be considered as constituting a separate language group, for many years the Japanese government treated them as merely ‘dialects’ of Japanese. The 1916 government initiative of homogenizing the nation by spreading Standard Japanese was so successful that ‘dialect’ speakers believe that they are speaking inferior versions of Japanese. In fact, remaining Ikema speakers still recall the infamous ‘dialect placards’, which were placed around their necks as a form of punishment when they used Ikema at school. It is thus not surprising that islanders initially showed suspicion and resistance when our team showed interest in Ikema. However, we soon started finding community leaders with concerns about their rapidly disappearing language. Through discussions with us, these leaders started to realize that documenting Ikema for future generations in collaboration with our group is a significant first step. We also recognized the importance of establishing our presence in the community through getting involved in local projects, e.g. a kindergarten teacher’s project of compiling booklets to promote Ikema for the community, and local activists’ attempt to archive and display a large number of precious photos taken by an ethnographer in the 1960’s. By participating in these projects, we have been slowly gaining the trust of the community, which, we hope, will take us to our eventual goal of conducting a large scale community-centered documentation project. In fact, more recently we have been provided with opportunities to record narratives by older speakers (80s-90s), and to work with younger speakers (60s-70s) in eliciting sentences. Knowing their difficult history and our genuine involvement with community activities have been critical in decreasing tensions which existed in the community. These tensions may continue to exist, but we need to keep paving ways toward documenting Ikema and hopefully other invisible minority languages in Okinawa

Metallicity Dependence of Molecular Cloud Hierarchical Structure at Early Evolutionary Stages

The formation of molecular clouds out of HI gas is the first step toward star formation. Its metallicity dependence plays a key role to determine star formation through the cosmic history. Previous theoretical studies with detailed chemical networks calculate thermal equilibrium states and/or thermal evolution under one-zone collapsing background. The molecular cloud formation in reality, however, involves supersonic flows, and thus resolving the cloud internal turbulence/density structure in three dimension is still essential. We here perform magnetohydrodynamics simulations of 20 km s^-1 converging flows of Warm Neutral Medium (WNM) with 1 uG mean magnetic field in the metallicity range from the Solar (1.0 Zsun) to 0.2 Zsun environment. The Cold Neutral Medium (CNM) clumps form faster with higher metallicity due to more efficient cooling. Meanwhile, their mass functions commonly follow dn/dm proportional to m^-1.7 at three cooling times regardless of the metallicity. Their total turbulence power also commonly shows the Kolmogorov spectrum with its 80 percent in the solenoidal mode, while the CNM volume alone indicates the transition towards the Larson's law. These similarities measured at the same time in the unit of the cooling time suggest that the molecular cloud formation directly from the WNM alone requires a longer physical time in a lower metallicity environment in the 1.0-0.2 Zsun range. To explain the rapid formation of molecular clouds and subsequent massive star formation possibly within 10 Myr as observed in the Large/Small Magellanic Clouds (LMC/SMC), the HI gas already contains CNM volume instead of pure WNM.Comment: 23 pages, 11 figures. Accepted for publication in Ap