965 research outputs found

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

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    Higgs mediated flavor violating electromagnetic interactions, induced at the one--loop level by a nondiagonal HfifjHf_if_j vertex, with fif_i and fjf_j charged leptons or quarks, are studied within the context of a completely general effective Yukawa sector that comprises SUL(2)×UY(1)SU_L(2)\times U_Y(1)--invariant operators of up to dimension--six. Exact formulae for the one--loop γfifj\gamma f_if_j and γγfifj\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 μ→eγ\mu \to e\gamma decay is used to derive a bound on the branching ratio of the μ→eγγ\mu \to e\gamma \gamma transition, which is 6 orders of magnitude stronger than the current experimental limit. Previous results on the τ→μγ\tau \to \mu \gamma and τ→μγγ\tau \to \mu \gamma \gamma decays are reproduced. The possibility of detecting signals of lepton flavor violation at γγ\gamma \gamma colliders is explored through the γγ→lilj\gamma \gamma \to l_il_j reaction, putting special emphasis on the τμ\tau \mu final state. Using the bound imposed on the HτμH\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

    Testing the non-unitarity of the leptonic mixing matrix at FASER

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    The FASER experiment has detected the first neutrino events coming from LHC. Near future high-statistic neutrino samples will allow us to search for new physics within the neutrino sector. Motivated by the forthcoming promising FASER neutrino data, we study its potential for testing the unitarity of the neutrino lepton mixing matrix. Although it would be challenging for FASER to have strong constraints on this kind of new physics, we discuss its role in contributing to a future improved global analysis.Comment: 8 pages, 1 figure, preprin

    A statistical analysis of electric self-potential time series associated to two 1993 earthquakes in Mexico

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    Recent studies related with earthquake prediction involve statistical studies of the ground electric self-potential behavior. Published results about the complexity of this kind of processes encourage us to study the statistical behavior of the ground electric self-potential recorded in Guerrero state, Mexico. This region is characterized by high seismicity. The electric self-potential variations were recorded in the Acapulco station directly from the ground. The sampling period was four seconds and the data were stored from March to December of 1993. Two significant earthquakes (EQs) occurred near this station, 15 May and 24 October whose magnitudes were Mw=6.0 and Mw=6.6 respectively. A preliminary processing was carried out consisting of a moving average of the original time series in order to filter the very high frequencies and to complete short lacks of data and outliers. Then, a visual inspection of the complete filtered signal was performed to search some seismic electric signals (SES), which were ambiguously depicted. Subsequently, a detrending of µ=0 was applied with the windows of 3.3, 6.6 and 10 h. Later, the analysis of the spectral exponent β was made, showing changes during the total period examined, and the most evident changes occurred during the preparation mechanism of the Mw=6.6 EQ. Fifteen days before the 24 October EQ, a Brownian-noise like behavior was displayed (β≈2), having a duration of about two days. In addition a Higuchi fractal method and wavelet analysis were made confirming the presence of the β-anomaly

    One-loop effects of extra dimensions on the WW\gamma and WWZ vertices

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    The one-loop contribution of the excited Kaluza-Klein (KK) modes of the SUL(2)SU_L(2) gauge group on the off-shell WWγWW\gamma and WWZWWZ vertices is calculated in the context of a pure Yang-Mills theory in five dimensions and its phenomenological implications discussed. The use of a gauge-fixing procedure for the excited KK modes that is covariant under the standard gauge transformations of the SUL(2)SU_L(2) group is stressed. A gauge-fixing term and the Faddeev-Popov ghost sector for the KK gauge modes that are separately invariant under the standard gauge transformations of SUL(2)SU_L(2) are presented. It is shown that the one-loop contributions of the KK modes to the off-shell WWγWW\gamma and WWZWWZ vertices are free of ultraviolet divergences and well-behaved at high energies. It is found that for a size of the fifth dimension of R−1∼1TeVR^{-1}\sim 1TeV, the one-loop contribution of the KK modes to these vertices is about one order of magnitude lower than the corresponding standard model radiative correction. This contribution is similar to the one estimated for new gauge bosons contributions in other contexts. Tree-level effects on these vertices induced by operators of higher canonical dimension are also investigated. It is found that these effects are lower than those generated at the one-loop order by the KK gauge modes.Comment: 19 pages, 9 figures. Some typos were correcte

    Development and sedative effect of a new formulation of midazolam in chocolate bars

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    The aim of this work was to assess the stability and sedative effect of midazolam in chocolate bars. The stability of 5 g chocolate bars containing 6 mg midazolam hydrochloride was evaluated at room temperature (25 ± 2 °C), at 4 and 40 °C, by HPLC. Drug plasma levels were measured and the sedative effect was confirmed in six healthy volunteers according to the Ramsay’s scale. Data regarding chocolate bar administration were compared to those from the apple juice solution. Pharmacokinetic data were processed using the WinNonLin 5.2 software. Midazolam in chocolate bars remained stable for 14 days at room temperature and exposed to light; for 90 days at 4 and 40 °C protected from light, and showed a longer shelf life, better flavour and appearance, inducing the same sedative effect as the apple juice preparation. Raspberry flavour masked midazolam unpleasing taste most favourably.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Identification of two fnr genes and characterisation of their role in the anaerobic switch in Sphingopyxis granuli strain TFA

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    Copyright © The Author(s) 2020. Sphingopyxis granuli strain TFA is able to grow on the organic solvent tetralin as the only carbon and energy source. The aerobic catabolic pathway for tetralin, the genes involved and their regulation have been fully characterised. Unlike most of the bacteria belonging to the sphingomonads group, this strain is able to grow in anoxic conditions by respiring nitrate, though not nitrite, as the alternative electron acceptor. In this work, two fnr-like genes, fnrN and fixK, have been identified in strain TFA. Both genes are functional in E. coli and Sphingopyxis granuli although fixK, whose expression is apparently activated by FnrN, seems to be much less effective than fnrN in supporting anaerobic growth. Global transcriptomic analysis of a ΔfnrN ΔfixK double mutant and identification of Fnr boxes have defined a minimal Fnr regulon in this bacterium. However, expression of a substantial number of anaerobically regulated genes was not affected in the double mutant. Additional regulators such regBA, whose expression is also activated by Fnr, might also be involved in the anaerobic response. Anaerobically induced stress response genes were not regulated by Fnr but apparently induced by stress conditions inherent to anaerobic growth, probably due to accumulation of nitrite and nitric oxide.Grants BIO2014-57545-R and PGC2018-097151-B-I00, co-funded by the Spanish Ministerio de Ciencia e Innovación and the European Regional Development Fund; fellowships from the FPU program (Ministerio de Universidades, Spain)

    The response of Sphingopyxis granuli strain TFA to the hostile anoxic condition

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    © The Author(s) 2019. Sphingomonads comprises a group of interesting aerobic bacteria because of their ubiquity and metabolic capability of degrading many recalcitrant contaminants. The tetralin-degrader Sphingopyxis granuli strain TFA has been recently reported as able to anaerobically grow using nitrate as the alternative electron acceptor and so far is the only bacterium with this ability within the sphingomonads group. To understand how strain TFA thrives under anoxic conditions, a differential transcriptomic analysis while growing under aerobic or anoxic conditions was performed. This analysis has been validated and complemented with transcription kinetics of representative genes of different functional categories. Results show an extensive change of the expression pattern of this strain in the different conditions. Consistently, the most induced operon in anoxia codes for proteases, presumably required for extensive changes in the protein profile. Besides genes that respond to lack of oxygen in other bacteria, there are a number of genes that respond to stress or to damage of macromolecules, including genes of the SOS DNA-damage response, which suggest that anoxic conditions represent a hostile environment for this bacterium. Interestingly, growth under anoxic conditions also resulted in repression of all flagellar and type IV pilin genes, which suggested that this strain shaves its appendages off while growing in anaerobiosis.Grant BIO2014-57545-R, co-funded by the Spanish Ministerio de Educación y Ciencia and the European Regional Development Fund; fellowships from the FPU program (Ministerio de Educación y Ciencia, Spain)

    Microalgae Cultivation for Secondary Metabolite Production

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    Microalgae including cyanobacteria have been recognized as an excellent source of fine chemicals, renewable fuels, vitamins, and proteins and usually are found in health food stores around the world. However, the accumulation of these compounds generally occurs at end of the exponential growth phase; furthermore, biomass density in cultivation commonly is low. Open cultures have been used for pigment, biofuels, and biomass production, but these types of culture system are not a good choice for the production of fine chemicals, due to contamination problems and the expensive production costs. Closed photobioreactors can be operated in a continuous cultivation providing an increase on biomass density and contamination-free condition and generally working at a maximum growth rate under specific conditions; besides, these systems can recycle the consumed culture medium at least three times before a new enriched medium is supplied, generating a more cost-effective production system. In addition, microalgae metabolism can be manipulated to provoke a specific secondary metabolite accumulation by the addition of organic carbon source or changing light intensity or both. In other words, photobioreactors can operate in continuous mode, with efficient light supply and the supplementation of organic carbon source to produce fine biochemicals such as anticancer, antibacterial, antioxidant, lectins, antiviral compounds, and biofuels
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