1,917 research outputs found

    Jarlskog-like invariants for theories with scalars and fermions

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    Within the framework of theories where both scalars and fermions are present, we develop a systematic prescription for the construction of CP-violating quantities that are invariant under basis transformations of those matter fields. In theories with Spontaneous Symmetry Breaking, the analysis involves the vevs' transformation properties under a scalar basis change, with a considerable simplification of the study of CP violation in the scalar sector. These techniques are then applied in detail to the two Higgs-doublet model with quarks. It is shown that there are new invariants involving scalar-fermion interactions, besides those already derived in previous analyses for the fermion-gauge and scalar-gauge sectors.Comment: 12 pages, Latex, no figure

    A Complex Case of Cholestasis in a Patient with ABCB4 and ABCB11 Mutations

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    The low-phospholipid-associated cholelithiasis (LPAC) syndrome is a form of symptomatic cholelithiasis occurring in young adults, characterized by recurrence of symptoms after cholecystectomy and presence of hepatolithiasis. The case refers to a healthy 39-year-old Caucasian male who presented with abdominal pain and jaundice. His blood tests showed conjugated hyperbilirubinemia and elevated liver enzymes (total bilirubin 6.65 mg/dL, γ-glutamyltransferase 699 IU/L) and abdominal computed tomography revealed dilation of common bile duct and left intrahepatic ducts. Magnetic resonance cholangiopancreatography identified choledocholithiasis, retrieved by endoscopic retrograde cholangiopancreatography, after which there was a worsening of jaundice (total bilirubin 23 mg/dL), which persisted for several weeks, possibly due to ciprofloxacin toxicity. After an extensive workup including liver biopsy, the identification of two foci of hepatolithiasis on reevaluation abdominal ultrasound raised the hypothesis of LPAC syndrome and the patient was started on ursodeoxycholic acid, with remarkable improvement. Genetic testing identified the mutation c.1954A>G (p.Arg652Gly) in ABCB4 gene (homozygous) and c.1331T>C (p.Val444Ala) in ABCB11 gene (heterozygous). In conclusion, we describe the unique case of an adult male with choledocholithiasis, hepatolithiasis, and persistent conjugated hyperbilirubinemia after retrieval of stones, fulfilling the criteria for LPAC syndrome and with possible superimposed drug-induced liver injury, in whom ABCB4 and ABCB11 mutations were found, both of which had not been previously described in association with LPAC.info:eu-repo/semantics/publishedVersio

    The effects of corruption on earnings management

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    This study provides empirical evidence on the effects of corruption, as proxied by Transparency International’s Corruption Perception Index, on earnings management. It tests the hypothesis of positive association between the countries’ level of corruption and the level of earnings management using a sample of foreign firms with American Depositary Receipts (ADR) in the U.S. market. Findings indicate that corruption perception is related to higher incentives for firms to manipulate earnings in the case of emerging countries. Such results are not identified in developed countries.info:eu-repo/semantics/publishedVersio

    On fermion masses and mixing in a model with A4A_4 symmetry

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    In a recently proposed multi-Higgs extension of the standard model in which discrete symmetries, A4A_4 and Z3Z_3 are imposed we show that, after accommodating the fermion masses and the mixing matrices in the charged currents, the mixing matrices in the neutral currents induced by neutral scalars are numerically obtained. However, the flavor changing neutral currents are under control mainly by mixing and/or mass suppressions in the neutral scalar sector.Comment: Version accepted for publication in International Journal of Modern Physics A. In this version we added a discussion on the charged lepton and neutrino masses. The title has been changed. Other minor changes do not modify the conclusion

    Large Neutrino Mixing with Universal Strength of Yukawa Couplings

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    We analyse, within the framework of universal strength for Yukawa couplings (USY), various structures for the Dirac and Majorana neutrino mass matrices giving rise, through the see-saw mechanism, to a degenerate mass spectrum. A specific USY ansatz is presented for the charged lepton and neutrino effective mass matrix, leading to quasi-degenerate neutrinos and a leptonic mixing matrix which provides a large angle solution for both the atmospheric and solar neutrino problems.Comment: 7 pages, ReVTeX, small comments adde

    A Rare Cause of Abdominal Pain in a Patient with Acute Necrotizing Pancreatitis.

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    INTRODUCTION: Walled-off necrosis (WON) is a potentially lethal late complication of acute pancreatitis (AP) and occurs in less than 10% of AP cases. It can be located in or outside the pancreas. When infected, the mortality rate increases and can reach 100% if the collection is not drained. Its treatment is complex and includes, at the beginning, intravenous antibiotics, which permit sepsis control and a delay in the therapeutic intervention, like drainage. Nowadays, a minimally invasive approach is advised. Depending on the location of the collection, computed tomography (CT)-guided drainage or endoscopic necrosectomy are the primary options, then complemented by surgical necrosectomy if needed. Infected WON of the abdominal wall has been rarely described in the literature and there is no report of any infection with Citrobacter freundii. CASE: We present the case of a 61-year-old man with necrotizing AP complicated by WON of the left abdominal wall, infected with Citrobacter freundii that was successfully treated with CT-guided percutaneous drainage and intravenous antibiotics. CONCLUSION: Infected WON accounts for considerable mortality and its location in the abdominal wall is rare; it can be treated with antibiotics and CT-guided drainage with no need for further intervention.info:eu-repo/semantics/publishedVersio

    Bio-inspired Systems for Carbon Dioxide Capture, Sequestration and Utilization

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    This chapter reviews the study and development of biological, enzymatic and bio-molecular systems for carbon dioxide capture and further sequestration or even utilization. Regardless of the interest on the use of the captured CO2 as C1 synthon on the manufacture of added-value compounds, there is a tremendous unbalance between the requirements of the contemporary society (leading to a massive production of carbon dioxide) and the framework of commercialization of the products from CO2 utilization. In this context, viable options are storage as a solid in the form of calcium or magnesium carbonate and conversion into other energetic frameworks. In addition, it is important to highlight that the conventional energy resources are progressively being replaced by renewable resources. While the change in energetic paradigm is not accomplished, systems that capture and convert carbon dioxide are highly sought. To this end, bio-inspired systems will be presented, starting from the use of compounds from the chiral pool, such as amino acids, saccharides and related bio-polymers, involved in the physical and chemical capture, sequestration and/or utilization of CO2. Additionally, enzymatic systems are presented in the context of sequestration of CO2 in the form of solid carbonates or even utilization of this C1 synthon in the preparation of fuels and commodity chemicals. Carbonic anhydrase is by far the most studied enzyme, as it catalyses the inter-conversion between CO2 and hydrogencarbonate in an effective mode. The biological option comprises the utilization of methanogens, acetogens and other organisms leading to the formation of added-value compounds. Most of the described systems are based on microbial electro-synthesis model and microbial carbon-capture cell prototypes

    Advances in electrochemical reduction of CO2 in ionic liquid-based electrolytes [Resumo]

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    ABSTRACT: Electrochemical reduction of CO2 was for the first time reported in 1870 [1], but it was only after 2010 that this field was the subject of intense research efforts. The use of renewable electricity to convert CO2 into products that are currently derived from fossil products and have high carbon footprint will certainly make this technology one pillar of a sustainable chemical industry. The scepticism towards the availability of cost effective products derived from CO2 electro-reduction that customers will be willing to buy has shifted to the belief that they can be commercially viable. Turning electrochemical CO2 reduction into a commercial technology will depend on economics, on the price of electricity, efficiency of the process and the value of the products. One way to improve the economics and improve the efficiency of the process is to integrate CO2 capture with conversion [2,3]. In this way the energy intensive regeneration step of the capture media can be eliminated and also CO2 transportation and storage. Ionic liquids are ideal media to achieve this integration, due to high CO2 adsorption capacity, high selectivity, wide electrochemical windows and nearly zero vapour pressure. The present work reports the progress of electrochemical reduction of CO2 in ionic liquids and the work of the authors in this field. It has been recognized that ionic liquids promote CO2 electro-reduction through lowering the reduction potential, the suppression of the competing hydrogen evolution reaction and by increasing the selectivity towards the target products. However, the understanding of the interactions between ionic liquids, CO2 and catalyst is still quite limited, but fundamental for synthetizing more efficient electrolytes for CO2 electro-reduction [4]. Thus, current cation and anion effects will be analysed and an overview of the current performance of heterogeneous electro-catalysts in ionic liquid- based electrolytes for CO2 electro-reduction will be provided.N/

    Unification and fermion mass relations in low string scale D-brane models

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    In this talk, gauge coupling evolution is analyzed in D-brane inspired models with two Higgs doublets and a U(3)xU(2)xU(1)^N gauge symmetry. In particular, we focus on D-brane configurations with two or three abelian factors. We find that the correct hypercharge assignment of the Standard Model particles is reproduced for six viable models distinguished by different brane configurations. We also investigate the bottom tau quark mass relation and find that the correct low energy m_b / m_\tau ratio is obtained for equal b-\tau Yukawa couplings at a string scale around 10^3 TeV.Comment: 10 pages, 3 figures. Talk presented at the ``Corfu Summer Institute'', Corfu-Greece, September 4-14, 2005. To appear in the proceedings of RTN workshop on the Quest for Unification Theory Confronts Experimen
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