Effective Lagrangian description of Higgs mediated flavor violating electromagnetic transitions: implications on lepton flavor violation

Higgs mediated flavor violating electromagnetic interactions, induced at the one--loop level by a nondiagonal $Hf_if_j$ vertex, with $f_i$ and $f_j$ charged leptons or quarks, are studied within the context of a completely general effective Yukawa sector that comprises $SU_L(2)\times U_Y(1)$--invariant operators of up to dimension--six. Exact formulae for the one--loop $\gamma f_if_j$ and $\gamma \gamma f_if_j$ couplings are presented and their related processes used to study the phenomena of Higgs mediated lepton flavor violation. The experimental limit on the $\mu \to e\gamma$ decay is used to derive a bound on the branching ratio of the $\mu \to e\gamma \gamma$ transition, which is 6 orders of magnitude stronger than the current experimental limit. Previous results on the $\tau \to \mu \gamma$ and $\tau \to \mu \gamma \gamma$ decays are reproduced. The possibility of detecting signals of lepton flavor violation at $\gamma \gamma$ colliders is explored through the $\gamma \gamma \to l_il_j$ reaction, putting special emphasis on the $\tau \mu$ final state. Using the bound imposed on the $H\tau \mu$ vertex by the current experimental data on the muon anomalous magnetic moment, it is found that about half a hundred events may be produced in the International Linear Collider.Comment: 18 pages, 12 figure

Higgs mediated flavor violating top quark decays t --> u_i H, u_i gamma, u_i gamma gamma, and the process gamma gamma --> t c in effective theories

The rare top quark couplings $tu_i\gamma$ and $tu_i\gamma \gamma$ ($u_i=u,c$) induced at the one-loop level by a flavor violating $tu_iH$ vertex are studied within the context of an effective Yukawa sector that incorporates $SU_L(2)\times U_Y(1)$-invariant operators of up to dimension six. Data on the recently observed $D^0-\overline{D^0}$ mixing are employed to constrain the $tu_iH$ vertex, which is then used to predict the $t\to u_iH$, $t\to u_i\gamma$, and $t\to u_i\gamma \gamma$ decays, as well as the $\gamma \gamma \to \bar{t}u_i+t\bar{u}_i$ reaction in the context of the ILC. It is found that the $t\to cH$ and $t\to c\gamma \gamma$ decays can reach sizable branching ratios as high as $5\times 10^{-3}$ and $10^{-4}$, respectively. As for the $t\to c\gamma$ decay, it can have a branching ratio of $5\times 10^{-8}$ that is about 6 orders of magnitude larger than the standard model prediction, which, however, is still very small to be detected. As for $tc$ production, it is found that, due to the presence of a resonant effect in the convoluted cross section $\sigma(e^+e^-\to \gamma \gamma \to t\bar{c}+\bar{t}c)$, about $(0.5 - 2.7)\times 10^{3}$ $tc$ events may be produced at the ILC for a value of the Higgs mass near to the top mass.Comment: 5 pages and 3 figure

The decay b→sγb\to s\gamma in the presence of a constant antisymmetric tensor field

A constant antisymmetric 2-tensor can arise in general relativity with spontaneous symmetry breaking or in field theories formulated in a noncommutative space-time. In this work, the one-loop contribution of a nonstandard $WW\gamma$ vertex on the flavor violating quark transition $q_i\to q_j\gamma$ is studied in the context of the electroweak Yang-Mills sector extended with a Lorentz-violating constant 2-tensor. An exact analytical expression for the on shell case is presented. It is found that the loop amplitude is gauge independent, electromagnetic gauge invariant, and free of ultraviolet divergences. The dipolar contribution to the $b\to s\gamma$ transition together with the experimental data on the $B\to X_s\gamma$ decay is used to derive the constraint $\Lambda_{LV}>1.96$ TeV on the Lorentz-violating scale.Comment: 14 pages and 2 figure

Biosynthesis of Silver Nanoparticles Using Chenopodium ambrosioides

Biosynthesis of silver nanoparticles (AgNPs) was achieved using extract of Chenopodium ambrosioides as a reducer and coating agent at room temperature (25°C). Two molar solutions of AgNO3 (1 mM and 10 mM) and five extract volumes (0.5, 1, 2, 3, and 5 mL) were used to assess quantity, shape, and size of the particles. The UV-Vis spectra gave surface plasmon resonance at 434–436 nm of the NPs synthesized with AgNO3 10 mM and all extract volumes tested, showing a direct relationship between extract volumes and quantity of particles formed. In contrast, the concentration of silver ions was related negatively to particle size. The smallest (4.9 ± 3.4 nm) particles were obtained with 1 mL of extract in AgNO3 10 mM and the larger amount of particles were obtained with 2 mL and 5 mL of extract. TEM study indicated that the particles were polycrystalline and randomly oriented with a silver structure face centered cubic (fcc) and fourier transform infrared spectroscopy (FTIR) indicated that disappearance of the –OH group band after bioreduction evidences its role in reducing silver ions

GENETIC VARIABILITY OF Gallibacterium anatis STRAINS ISOLATED FROM PERUVIAN COMMERCIAL BIRDS WITH RESPIRATORY INFECTIONS

El propósito del estudio fue determinar la variabilidad genética de 96 cepas de Gallibacterium anatis aisladas de aves comerciales con sintomatología respiratoria, provenientes de Arequipa (2), Ica (3), La Libertad (27), Lima (62), Madre de Dios (1) y Ucayali (1), y recolectadas desde el 2007 al 2011. Las cepas se tipificaron mediante pruebas de fermentación de carbohidratos y sensibilidad a nueve antimicrobianos. La variabilidad genética de las cepas de G. anatis se determinó mediante ERIC-PCR, previa identificación por PCR usando cebadores específicos. Del análisis de fermentación de carbohidratos se obtuvieron perfiles que correspondieron a 10 biovares, todos los cuales se encontraron en Lima y el 45.8% de las cepas pertenecieron al biovar 4. Con respecto a la sensibilidad antimicrobiana, el 40.8% de las cepas fueron resistentes a todos los antimicrobianos estudiados, en tanto que el 94.8 y 95.8% fueron resistentes a enrofloxacina y ciprofloxacina. Por ERIC-PCR se obtuvieron 24 perfiles de ADN no asociados con los biovares, lo cual indica la existencia de variabilidad genética intraespecífica en cepas de G. anatis circulantes en Perú.The purpose of this study was to determine the genetic variability of strains of Gallibacterium anatis isolated in commercial poultry with respiratory symptoms from Arequipa (2), Ica (3), La Libertad (27), Lima (62), Madre de Dios (1) and Ucayali (1), collected from 2007 to 2011. Strains were typified by carbohydrate fermentation tests and sensitivity to nine antimicrobials. The genetic variability of these strains was determined by ERIC-PCR, after identification by PCR using specific primers. The analysis of carbohydrate fermentation profiles corresponded to 10 biovars, all of which were found in Lima and 45.8% of the strains belonged to biovar 4. Concerning antimicrobial susceptibility, 40.8% of strains were resistant to all antimicrobials studied, while 94.8 and 95.8% were resistant to enrofloxacin and ciprofloxacin. By ERIC-PCR 24 DNA profiles associated with biovars were obtained, indicating the existence of intraspecific genetic variability in strains of G. anatis circulating in Peru

EcoCyc: A comprehensive view of Escherichia coli biology

EcoCyc (http://EcoCyc.org) provides a comprehensive encyclopedia of Escherichia coli biology. EcoCyc integrates information about the genome, genes and gene products; the metabolic network; and the regulatory network of E. coli. Recent EcoCyc developments include a new initiative to represent and curate all types of E. coli regulatory processes such as attenuation and regulation by small RNAs. EcoCyc has started to curate Gene Ontology (GO) terms for E. coli and has made a dataset of E. coli GO terms available through the GO Web site. The curation and visualization of electron transfer processes has been significantly improved. Other software and Web site enhancements include the addition of tracks to the EcoCyc genome browser, in particular a type of track designed for the display of ChIP-chip datasets, and the development of a comparative genome browser. A new Genome Omics Viewer enables users to paint omics datasets onto the full E. coli genome for analysis. A new advanced query page guides users in interactively constructing complex database queries against EcoCyc. A Macintosh version of EcoCyc is now available. A series of Webinars is available to instruct users in the use of EcoCyc

Monocytes regulate the mechanism of T-cell death by inducing Fas-mediated apoptosis during bacterial infection.

Monocytes and T-cells are critical to the host response to acute bacterial infection but monocytes are primarily viewed as amplifying the inflammatory signal. The mechanisms of cell death regulating T-cell numbers at sites of infection are incompletely characterized. T-cell death in cultures of peripheral blood mononuclear cells (PBMC) showed 'classic' features of apoptosis following exposure to pneumococci. Conversely, purified CD3(+) T-cells cultured with pneumococci demonstrated necrosis with membrane permeabilization. The death of purified CD3(+) T-cells was not inhibited by necrostatin, but required the bacterial toxin pneumolysin. Apoptosis of CD3(+) T-cells in PBMC cultures required 'classical' CD14(+) monocytes, which enhanced T-cell activation. CD3(+) T-cell death was enhanced in HIV-seropositive individuals. Monocyte-mediated CD3(+) T-cell apoptotic death was Fas-dependent both in vitro and in vivo. In the early stages of the T-cell dependent host response to pneumococci reduced Fas ligand mediated T-cell apoptosis was associated with decreased bacterial clearance in the lung and increased bacteremia. In summary monocytes converted pathogen-associated necrosis into Fas-dependent apoptosis and regulated levels of activated T-cells at sites of acute bacterial infection. These changes were associated with enhanced bacterial clearance in the lung and reduced levels of invasive pneumococcal disease

EcoCyc: a comprehensive database of Escherichia coli biology

EcoCyc (http://EcoCyc.org) is a comprehensive model organism database for Escherichia coli K-12 MG1655. From the scientific literature, EcoCyc captures the functions of individual E. coli gene products; their regulation at the transcriptional, post-transcriptional and protein level; and their organization into operons, complexes and pathways. EcoCyc users can search and browse the information in multiple ways. Recent improvements to the EcoCyc Web interface include combined gene/protein pages and a Regulation Summary Diagram displaying a graphical overview of all known regulatory inputs to gene expression and protein activity. The graphical representation of signal transduction pathways has been updated, and the cellular and regulatory overviews were enhanced with new functionality. A specialized undergraduate teaching resource using EcoCyc is being developed