Pion production in the inner disk around Cygnus X-1

Neutron production via ^{4}He breakup and p(p, n{pi}^+)p is considered in the innermost region of an accretion disk surrounding a Kerr Black Hole. These reactions occur in a plasma in Wien equilibrium, where (radiatively produced) pair production equals annihilation. Cooling of the disk is assumed to be due to unsaturated inverse Comptonization of external soft photons and to the energy needed to ignite both nuclear reactions. Assuming matter composition of 90% Hydrogen and 10% He, it is shown that, close to the border of this region, neutron production is essentially from ^{4}He breakup. Close to the horizon, the contribution from p(p, n{pi}^+)p to the neutron production is comparable to that from the breakup. It is shown that the viscosity generated by the collisions of the accreting matter with the neutrons may drive stationary accretion, for accretion rates below a critical value. In this case, solution to the disk equations is double-valued and for both solutions protons overnumber the pairs. It is claimed that these solutions may mimic the states of high and low luminosity observed in Cygnus X-1 and related sources. This would be explained either by the coupling of thermal instability to the peculiar behavior of the viscosity parameter alpha with the ion temperature that may intermittently switch accretion off or by the impossibility of a perfect tuning for both thermal and pair equilibrium in the disk, a fact that forces the system to undergo a kind of limit cycle behavior around the upper solution.Comment: 23 pages, 11 figure

Combined fibrolamellar carcinoma and cholangiocarcinoma exhibiting biphenotypic antigen expression: a case report

Fibrolamellar carcinoma (FLC), a variant of hepatocellular carcinoma (HCC), very rarely occurs in association with cholangiocarcinoma (CC). This report describes the first case of FLC coexisting with CC (FLC-CC) from Japan. Although the major part of the tumour located in the right lobe of the liver showed the typical features of FLC, CC was admixed with the FLC, not only in the primary hepatic tumour, but also in the lymph node metastases. Immunohistochemical analysis revealed that, although carcinoembryonic antigen (CEA), which can be detected with monoclonal antibodies in the cytoplasm and the cell surface of CC cells but not HCC cells, was expressed in only the CC cells in the primary tumour, it was expressed extensively in the cytoplasm of both CC and FLC cells in the metastatic and recurrent tumours. Furthermore, Hep Par 1, a hepatocyte specific antigen, was also expressed in both the FLC and CC cells. These findings suggest that, in this case, both FLC and CC were possibly derived from the same cancer stem cell with the capacity to differentiate into both hepatocytes and bile duct epithelium, and that both the cellular components, therefore, exhibited biphenotypic antigen expression

Ideologies of English in Japan: the perspective of policy and pedagogy

This paper examines the ideologies of language which underpin mainstream applied linguistic research and educational policy generation for English language teaching in Japan. Over the last 30 years a burgeoning literature has devoted itself to the task of researching and directing English language education in Japan, but has, by its own admission, had little success in effecting much change in what it perceives as a system incompatible with effective language learning. By surveying prominent academic studies on this topic and analysing these with reference to the policy reforms with which they interact, the paper makes explicit the linguistic and socio-political assumptions upon which this work is based and suggests that a critical awareness of these ideologies can assist in the production of sustainable language regulation