Upper Bound Theory for Deformation of Porous Materials

A porous material is idealized in such a way that it possesses an identical yield surface for any volume element throughout the material during a deformation processing. This makes it possible to derive an upper bound theorem on the basis of the plasticity theory for porous metals already proposed by the authors. The theorem is utilized to estimate extrusion pressures and the final density ratios for given initial densities. The estimated values agree well with experimental data. An alternative way of deriving an upper bound to the load is also presented on a modified yield criterion for porous metals

The Osher Upwind Scheme and its Application to Cosmic Gas Dynamics

Details of the second order Osher scheme for the multi-dimensional Euler equation are presented. The adopted method to attain the second order of accuracy differs from the existing second order formulation by Osher. The present method is easy to be implemented and can be applied to other first order upwind schemes. Two types of numerical integration forms are coded. One is written in the integral form (cell method), and the other is the usual finite-difference form. Both forms work well and can capture strong shocks without any auxiliary artificial damping. The integration form strictly satisfies the flux conservation even on geometrical singular coordinate lines, which inevitably appear in three dimensional calculations with bodies embedded. Hydrodynamic calculations of the interaction between a stellar wind and an accretion flow are performed to demonstrate the ability of the present method

New Constraints on Radiative Decay of Long-Lived Particles in Big Bang Nucleosynthesis with New 4^4He Photodisintegration Data

A recent measurement of $^4$He photodisintegration reactions, $^4$He($\gamma$,$p$)$^3$H and $^4$He($\gamma$,$n$)$^3$He with laser-Compton photons shows smaller cross sections than those estimated by other previous experiments at $E_\gamma \lesssim 30$ MeV. We study big-bang nucleosynthesis with the radiative particle decay using the new photodisintegration cross sections of $^4$He as well as previous data. The sensitivity of the yields of all light elements D, T, $^3$He, $^4$He, $^6$Li, $^7$Li and $^7$Be to the cross sections is investigated. The change of the cross sections has an influence on the non-thermal yields of D, $^3$He and $^4$He. On the other hand, the non-thermal $^6$Li production is not sensitive to the change of the cross sections at this low energy, since the non-thermal secondary synthesis of $^6$Li needs energetic photons of $E_\gamma \gtrsim 50$ MeV. The non-thermal nucleosynthesis triggered by the radiative particle decay is one of candidates of the production mechanism of $^6$Li observed in metal-poor halo stars (MPHSs). In the parameter region of the radiative particle lifetime and the emitted photon energy which satisfies the $^6$Li production above the abundance level observed in MPHSs, the change of the photodisintegration cross sections at $E_\gamma \lesssim 30$ MeV as measured in the recent experiment leads to $\sim 10$% reduction of resulting $^3$He abundance, whereas the $^6$Li abundance does not change for this change of the cross sections of $^4$He($\gamma$,$p$)$^3$H and $^4$He($\gamma$,$n$)$^3$He. The $^6$Li abundance, however, could show a sizable change and therefore the future precise measurement of the cross sections at high energy $E_\gamma \gtrsim$ 50 MeV is highly required.Comment: 10 pages, 7 figures, conclusion not changed, to be published in PR

Trace Elements in Hair: Relevance to Air Pollution

Elemental concentrations of single hair samples taken from 2003 to 2012 had been evaluated by X-ray fluorescence for the assessment of the relation between calcium and cancer. Early results implied a mechanism linking hair and serum element concentrations with a shift in element levels over time. After 2009, pollution-attributable differences were seen in the levels of Ca, Sr, P, Cl, Br, K, S, elements under renal control by parathyroid hormone (PTH), as well as Cu, Zn, Ti. Especially, hair taken from February to March 2011 showed low [Cu] and [Zn] indicating about half of the normal serum level and often three orders of magnitude higher [Ti] than typical. These specimens also showed higher serum [S] than usual, and except for one patient with PTH-related disease, all the subjects had the normal or lower hair calcium than typical for earlier years. Almost all the subjects showed store-operated Ca channel gating. The pollution era is associated with an increase in hair Na, a decrease in K, and abnormally low P, suggesting a functional deterioration of Na+/K+-ATPase. These results can be attributed to increases in serum Ca and S coincident with breathing the polluted air; the incorporated Ca closes the ion channels of hair matrix cells but may be moved with P to bone, resulting in the abnormal P deficiency, likely producing an ATP shortage in serum. This insufficient ATP supply may result in inactivated molecular pumps and hypokalemia contributing to fatal ventricular fibrillation in patients with myocardial infarction. The pollution increase [S] in serum may be excreted by forming sulfide compounds with Cu and Zn, resulting in Cu deficiency necessary for making elastin to repair damage in blood vessels. The K and Cu deficiencies observed appear to account for the reported increase in infarction mortality after high-pollution days

Defective Morphogenesis and Functional Maturation in Fetal Islet-Like Cell Clusters From OLETF Rat, A Model of NIDDM

A failure in the compensate proliferation of pancreatic β-cells, as the primary pathogenic event, has been reported in OLETF rat, a model of NIDDM. The aim of the present study is to define whether the β-cell defect is attributed to the fetal stage islet development, if so, whether the defect involves down regulation of PDX-1 protein expression. Morphological changes, β-cell function, and the expression of PDX-1 protein were examined in the cultured fetal islet-like cell clusters (ICCs) from OLETF rats along with their diabetes-resistant control counterpart LETO rats in the presence of 5.5 or 11.1mM glucose for 48, 72, 96, and 120-hr, respectively. We have observed four abnormalities in the ICCs of OLETF rats. First, a defective morphogenesis was noted during the 72 to 120-hr ICC culture, a period characterized by a dramatic increase in both β-cell and non-β-cell (α,σ, and PP) populations in control rats. This defective morphogenesis was demonstrated by a growth retardation of epithelial stratification and poor development of both β-cell and non-β-cell masses along with a parallel decline in relevant islet hormone contents. Second, a functional defect was characterized by failure to response to glucose during the 96 to 120- hr-cultured ICCs. Third, the ultrastructural analysis revealed a significant reduction in the number of secretory granules. Four, Western blot analysis showed a significant decrease of PDX-1 protein expression in the OLETF ICCs cultured in 11.1mM glucose for 48 to 72-hr and in 5.5mM glucose for 120-hr. Therefore, we concluded that during the fetal stage of islet development, OLETF rats exhibit both morphological and functional defects

Ornithine Decarboxylase Antizyme Induces Hypomethylation of Genome DNA and Histone H3 Lysine 9 Dimethylation (H3K9me2) in Human Oral Cancer Cell Line

Background: Methylation of CpG islands of genome DNA and lysine residues of histone H3 and H4 tails regulates gene transcription. Inhibition of polyamine synthesis by ornithine decarboxylase antizyme-1 (OAZ) in human oral cancer cell line resulted in accumulation of decarboxylated S-adenosylmethionine (dcSAM), which acts as a competitive inhibitor of methylation reactions. We anticipated that accumulation of dcSAM impaired methylation reactions and resulted in hypomethylation of genome DNA and histone tails. Methodology/Principal Findings: Global methylation state of genome DNA and lysine residues of histone H3 and H4 tails were assayed by Methylation by Isoschizomers (MIAMI) method and western blotting, respectively, in the presence or absence of OAZ expression. Ectopic expression of OAZ mediated hypomethylation of CpG islands of genome DNA and histone H3 lysine 9 dimethylation (H3K9me2). Protein level of DNA methyltransferase 3B (DNMT3B) and histone H3K9me specific methyltransferase G9a were down-regulated in OAZ transfectant. Conclusions/Significance: OAZ induced hypomethylation of CpG islands of global genome DNA and H3K9me2 by down-regulating DNMT3B and G9a protein level. Hypomethylation of CpG islands of genome DNA and histone H3K9me2 is a potent mechanism of induction of the genes related to tumor suppression and DNA double strand break repair