Matrix elements of the complete set of \Delta B = 2 and \Delta C = 2 operators in heavy meson chiral perturbation theory

Using heavy meson chiral perturbation theory, we consider the light quark-mass and spatial volume dependence of the matrix elements of \Delta B=2 and \Delta C=2 four-quark operators relevant for B^{0}_{(s)}{-}\bar{B}^{0}_{(s)} and D^{0}{-}\bar{D}^{0} mixing, and the B_{s} meson width difference. Our results for these matrix elements are obtained in the N_{f}=2+1 partially quenched theory, which becomes full QCD in the limit where sea and valence quark masses become equal. They can be used in extrapolation of lattice calculations of these matrix elements to the physical light quark masses and to infinite volume. An important conclusion of this paper is that the chiral extrapolations for matrix elements of heavy-light meson mixing beyond the Standard Model, and those relevant for the B_s width difference are more complicated than that for the Standard Model mixing matrix elements.Comment: 13 pages; version accepted for publicatio

The Information Content of the Limit Order Book and the Corresponding Trading Strategy

[[sponsorship]]交通大學財務金融研究所; 亞太金融研究發展基金會; 羅格斯大學[[notice]]待補頁數[[conferencetype]]國際[[conferencedate]]20130111~20130111[[conferencelocation]]新竹, 臺

A Rapid Flexible Method for Determining Bile Lipids

A rapid flexible method has been developed for the quantitative determination of bile lipids In gallbladder and hepatic bile and duodenal aspirates. Quantification of bile salts involves separation of bile salt conjugates from one another and other bile lipids by thin layer chromatography. The separated salts are determined using 3-hydroxysteroid dehydrogenase and gas liquid chromatography. Cholesterol is determined in petroleum ether extracts of saponified bile by application of the Lieberman-Burchard reaction. Phospholipid phosphorus is determined in purified bile lipid extracts by oxidation followed by application of Bartlett\u27s modification of the Fiske- SubbaRow method

Alcohol Use, Abuse, and Dependency in Shanghai

The use of alcohol for social and ceremonial occasions was recorded in Chinese history as early as 1760 B.C. during the Yin Dynasty (Ci-Hai Encyclopedia, 1979:936). The cultural tradition of ancient China placed alcoholic beverages at the center of social occasions, which presumably was the origin of the adage: Without wine, there is no li (or etiquette). Thus, the use of alcoholic beverages has always been accompanied by the concept of propriety and the discharging of one\u27s role obligations m social functions, rather than that of personal indulgence

Accumulation of a polyisoprene-linked amino sugar in polymyxin-resistant Salmonella typhimurium and Escherichia coli: Structural characterization and transfer to lipid A in the periplasm

Polymyxin-resistant mutants of Escherichia coli and Salmonella typhimurium accumulate a novel minor lipid that can donate 4-amino-4-deoxy-L-arabinose units (L-Ara4N) to lipid A. We now report the purification of this lipid from a pss- pmrAC mutant of E. coli and assign its structure as undecaprenyl phosphate-α-L-Ara4N. Approximately 0.2 mg of homogeneous material was isolated from an 8-liter culture by solvent extraction, followed by chromatography on DEAE-cellulose, C18 reverse phase resin, and silicic acid. Matrix-assisted laser desorption ionization/time of flight mass spectrometry in the negative mode yielded a single species [M - H]- at m/z 977.5, consistent with undecaprenyl phosphate-α-L-Ara4N (Mr = 978.41). 31P NMR spectroscopy showed a single phosphorus atom at -0.44 ppm characteristic of a phosphodiester linkage. Selective inverse decoupling difference spectroscopy demonstrated that the undecaprenyl phosphate group is attached to the anomeric carbon of the L-Ara4N unit. One- and two-dimensional 1H NMR studies confirmed the presence of a polyisoprene chain and a sugar moiety with chemical shifts and coupling constants expected for an equatorially substituted arabinopyranoside. Heteronuclear multiple-quantum coherence spectroscopy analysis demonstrated that a nitrogen atom is attached to C-4 of the sugar residue. The purified donor supports in vitro conversion of lipid IVA to lipid IIA, which is substituted with a single L-Ara4N moiety. The identification of undecaprenyl phosphate-α -L-Ara4N implies that L-Ara4N transfer to lipid A occurs in the periplasm of polymyxin-resistant strains, and establishes a new enzymatic pathway by which Gram-negative bacteria acquire antibiotic resistance

Developing an e-infrastructure for social science

We outline the aims and progress to date of the National Centre for e-Social Science e-Infrastructure project. We examine the challenges faced by the project, namely in ensuring outputs are appropriate to social scientists, managing the transition from research projects to service and embedding software and data within a wider infrastructural framework. We also provide pointers to related work where issues which have ramifications for this and similar initiatives are being addressed

Preferential tau aggregation in von Economo neurons and fork cells in frontotemporal lobar degeneration with specific MAPT variants.

Tau aggregation is a hallmark feature in a subset of patients with frontotemporal dementia (FTD). Early and selective loss of von Economo neurons (VENs) and fork cells within the frontoinsular (FI) and anterior cingulate cortices (ACC) is observed in patients with sporadic behavioral variant FTD (bvFTD) due to frontotemporal lobar degeneration (FTLD), including FTLD with tau inclusions (FTLD-tau). Recently, we further showed that these specialized neurons show preferential aggregation of TDP-43 in FTLD-TDP. Whether VENs and fork cells are prone to tau accumulation in FTLD-tau remains unclear, and no previous studies of these neurons have focused on patients with pathogenic variants in the gene encoding microtubule-associated protein tau (FTLD-tau/MAPT). Here, we examined regional profiles of tau aggregation and neurodegeneration in 40 brain regions in 8 patients with FTLD-tau/MAPT and 7 with Pick's disease (PiD), a sporadic form of FTLD-tau that often presents with bvFTD. We further qualitatively assessed the cellular patterns of frontoinsular tau aggregation in FTLD-tau/MAPT using antibodies specific for tau hyperphosphorylation, acetylation, or conformational change. ACC and mid-insula were among the regions most affected by neurodegeneration and tau aggregation in FTLD-tau/MAPT and PiD. In these two forms of FTLD-tau, severity of regional neurodegeneration and tau protein aggregation were highly correlated across regions. In FTLD-tau/MAPT, VENs and fork cells showed disproportionate tau protein aggregation in patients with V337 M, A152T, and IVS10 + 16 variants, but not in patients with the P301L variant. As seen in FTLD-TDP, our data suggest that VENs and fork cells represent preferentially vulnerable neuron types in most, but not all of the MAPT variants we studied

Long run credit risk diversification: empirical decomposition of corporate bond spreads

Following the reduced-form models of Duffee (1999) and Jarrow, Lando and Yu (2003), this study investigates the risk diversification issue of corporate bond portfolios. Considering especially long run market behavior, our empirical decomposition of corporate bond yield spreads indicates that the idiosyncratic component serves as a good vehicle for risk diversification. Moreover, the diosyncratic spread provides significant inferences about observed conditional corporate bond default rate, while full spread does not. Applying an affine model from Duffie and Singleton (1999), we find that the idiosyncratic credit spreads do not respond empirically to Treasury yields, unlike what is suggested in the structural model of Longstaff and Schwartz (1995) and literatures that follow. Systematic credit spreads are however positively related to Treasury yields in the long-run, but negatively so in the short run, suggesting the validity of both the tax and the option hypotheses. A long-run and optimal decomposition scheme yields an idiosyncratic credit spread measure at a median of 60 b.p. for the Baa index and is specifically compatible with Duffee’s model. It is insensitive to interest rate in the short-run, but would rise slightly with a positive shock in the long run at a rate of one to a hundred. Our findings in the study contribute to the risk practice of bond portfolio diversification

Long run credit risk diversification: empirical decomposition of corporate bond spreads

Following the reduced-form models of Duffee (1999) and Jarrow, Lando and Yu (2003), this study investigates the risk diversification issue of corporate bond portfolios. Considering especially long run market behavior, our empirical decomposition of corporate bond yield spreads indicates that the idiosyncratic component serves as a good vehicle for risk diversification. Moreover, the diosyncratic spread provides significant inferences about observed conditional corporate bond default rate, while full spread does not. Applying an affine model from Duffie and Singleton (1999), we find that the idiosyncratic credit spreads do not respond empirically to Treasury yields, unlike what is suggested in the structural model of Longstaff and Schwartz (1995) and literatures that follow. Systematic credit spreads are however positively related to Treasury yields in the long-run, but negatively so in the short run, suggesting the validity of both the tax and the option hypotheses. A long-run and optimal decomposition scheme yields an idiosyncratic credit spread measure at a median of 60 b.p. for the Baa index and is specifically compatible with Duffee’s model. It is insensitive to interest rate in the short-run, but would rise slightly with a positive shock in the long run at a rate of one to a hundred. Our findings in the study contribute to the risk practice of bond portfolio diversification