CP violation in Higgs decays

We study CP violation in fermion pair decays of Higgs boson. We idenfy some CP odd observables related to the tree level decay amplitude. We find that a few thousand Higgs boson decay events can already provide important information about CP violation. If the Higgs boson is produced, such an analysis could be carried out at the SSC, LHC and NLC.Comment: 9 pages, Revtex, UM-P-93/11, OZ-93/

The VirS/VirR two-component system regulates the anaerobic cytotoxicity, intestinal pathogenicity, and enterotoxemic lethality of Clostridium perfringens type C isolate CN3685.

Clostridium perfringens vegetative cells cause both histotoxic infections (e.g., gas gangrene) and diseases originating in the intestines (e.g., hemorrhagic necrotizing enteritis or lethal enterotoxemia). Despite their medical and veterinary importance, the molecular pathogenicity of C. perfringens vegetative cells causing diseases of intestinal origin remains poorly understood. However, C. perfringens beta toxin (CPB) was recently shown to be important when vegetative cells of C. perfringens type C strain CN3685 induce hemorrhagic necrotizing enteritis and lethal enterotoxemia. Additionally, the VirS/VirR two-component regulatory system was found to control CPB production by CN3685 vegetative cells during aerobic infection of cultured enterocyte-like Caco-2 cells. Using an isogenic virR null mutant, the current study now reports that the VirS/VirR system also regulates CN3685 cytotoxicity during infection of Caco-2 cells under anaerobic conditions, as found in the intestines. More importantly, the virR mutant lost the ability to cause hemorrhagic necrotic enteritis in rabbit small intestinal loops. Western blot analyses demonstrated that the VirS/VirR system mediates necrotizing enteritis, at least in part, by controlling in vivo CPB production. In addition, vegetative cells of the isogenic virR null mutant were, relative to wild-type vegetative cells, strongly attenuated in their lethality in a mouse enterotoxemia model. Collectively, these results identify the first regulator of in vivo pathogenicity for C. perfringens vegetative cells causing disease originating in the complex intestinal environment. Since VirS/VirR also mediates histotoxic infections, this two-component regulatory system now assumes a global role in regulating a spectrum of infections caused by C. perfringens vegetative cells

The Study of Teacher Written Feedback: The Effectiveness of Electronic Feedback on Student Writing Revisions

The effectiveness of teacher written feedback has been a subject of debate in second language writing for decades. The most basic debate in this area among ESL writing researchers is whether teacher written feedback in various forms has any positive effects on student writing revisions. Among other researchers, Ferris, Lee, Ene & Upton and Stevenson & Phakiti argued that while the effectiveness of error feedback in the traditional paper-and-pen form (Ferris, 1999, 2002, 2003, 2004, 2006 and Lee, 2008a, 2008b), computer-facilitated form (Ene & Upton, 2014) or computer-generated form (Stevenson & Phakiti, 2013) was not conclusive, more research should be done to explore in what ways error feedback can be improved. Indeed, the heterogeneity of these studies characterized by different focus, research designs, institutional and instructional contexts, and participant backgrounds, alongside some methodological flaws and misinterpretation of findings identified in my critical review has possibly undermined the validity and reliability of the studies, giving rise to these mixed results for both paper-and-pen feedback and computer-based feedback. As such, the causality between different forms of feedback treatment and their outcomes of error reduction is questioned. With the primary interest in improving the effectiveness of teacher written feedback in error correction, ‘Mark My Words’ (‘MMWs’), the interactive-based electronic feedback system, was designed in such a way to accommodate individual learners’ language needs and to be more responsive to various error types. This study focused on examining on the effectiveness of ‘Mark My Words’ (‘MMWs’), as a kind of computer-facilitated feedback (i.e. electronic feedback), in improving students’ error reduction in their writing revisions, under a controlled condition. The mixed methods approach was adopted, namely the ‘error count’ method and ‘questionnaire’, in this study. The participants were 62 second-year engineering students enrolled in an English for Specific Purposes course in a Hong Kong University. Efforts were made to avoid the impact of extraneous variables on the validity and reliability of the research outcomes under such controlled condition. The positive results of this study can contribute some sort of concrete evidence to the growing body of literature of the ‘effectiveness of teacher written feedback’ and ‘second language writing’, thus clarifying some mixed results of the previous research

Application of Bayesian graphs to SN Ia data analysis and compression

Bayesian graphical models are an efficient tool for modelling complex data and derive self-consistent expressions of the posterior distribution of model parameters. We apply Bayesian graphs to perform statistical analyses of Type Ia supernova (SN Ia) luminosity distance measurements from the joint light-curve analysis (JLA) data set. In contrast to the $\chi^2$ approach used in previous studies, the Bayesian inference allows us to fully account for the standard-candle parameter dependence of the data covariance matrix. Comparing with $\chi^2$ analysis results, we find a systematic offset of the marginal model parameter bounds. We demonstrate that the bias is statistically significant in the case of the SN Ia standardization parameters with a maximal 6 $\sigma$ shift of the SN light-curve colour correction. In addition, we find that the evidence for a host galaxy correction is now only 2.4 $\sigma$. Systematic offsets on the cosmological parameters remain small, but may increase by combining constraints from complementary cosmological probes. The bias of the $\chi^2$ analysis is due to neglecting the parameter-dependent log-determinant of the data covariance, which gives more statistical weight to larger values of the standardization parameters. We find a similar effect on compressed distance modulus data. To this end, we implement a fully consistent compression method of the JLA data set that uses a Gaussian approximation of the posterior distribution for fast generation of compressed data. Overall, the results of our analysis emphasize the need for a fully consistent Bayesian statistical approach in the analysis of future large SN Ia data sets.Comment: 14 pages, 13 figures, 5 tables. Submitted to MNRAS. Compression utility available at https://gitlab.com/congma/libsncompress/ and example cosmology code with machine-readable version of Tables A1 & A2 at https://gitlab.com/congma/sn-bayesian-model-example/ v2: corrected typo in author's name. v3: 15 pages, incl. corrections, matches the accepted versio

Contractile deficits in engineered cardiac microtissues as a result of MYBPC3 deficiency and mechanical overload.

The integration of in vitro cardiac tissue models, human induced pluripotent stem cells (hiPSCs) and genome-editing tools allows for the enhanced interrogation of physiological phenotypes and recapitulation of disease pathologies. Here, using a cardiac tissue model consisting of filamentous three-dimensional matrices populated with cardiomyocytes derived from healthy wild-type (WT) hiPSCs (WT hiPSC-CMs) or isogenic hiPSCs deficient in the sarcomere protein cardiac myosin-binding protein C (MYBPC3-/- hiPSC-CMs), we show that the WT microtissues adapted to the mechanical environment with increased contraction force commensurate to matrix stiffness, whereas the MYBPC3-/- microtissues exhibited impaired force development kinetics regardless of matrix stiffness and deficient contraction force only when grown on matrices with high fibre stiffness. Under mechanical overload, the MYBPC3-/- microtissues had a higher degree of calcium transient abnormalities, and exhibited an accelerated decay of calcium dynamics as well as calcium desensitization, which accelerated when contracting against stiffer fibres. Our findings suggest that MYBPC3 deficiency and the presence of environmental stresses synergistically lead to contractile deficits in cardiac tissues