Spontaneous CP Violation in the Next-to-Minimal Supersymmetric Standard Model Revisited

We re-examine spontaneous CP violation at the tree level in the context of the next-to-minimal supersymmetric standard model (NMSSM) with two Higgs doublets and a gauge singlet field. We analyse the most general Higgs potential without a discrete Z_3 symmetry, and derive an upper bound on the mass of the lightest neutral Higgs boson consistent with present experimental data. We investigate, in particular, its dependence on the admixture and CP-violating phase of the gauge singlet field, as well as on tan(beta). To assess the viability of the spontaneous CP violation scenario, we estimate epsilon_K by applying the mass insertion approximation. We find that a non-trivial flavour structure in the soft-breaking A terms is required to account for the observed CP violation in the neutral kaon sector. Furthermore, combining the minimisation conditions for spontaneous CP violation with the constraints coming from K0-K0bar mixing, we find that the upper bound on the lightest Higgs-boson mass becomes stronger. We also point out that the electric dipole moments of electron and neutron are a serious challenge for SUSY models with spontaneous CP violation.Comment: 19 pages, LaTeX2e, 5 figures; matches the published versio

Mo and W bis-MGD enzymes: nitrate reductases and formate dehydrogenases

J Biol Inorg Chem (2004) 9: 791–799 DOI 10.1007/s00775-004-0573-9Molybdenum and tungsten are second- and third-row transition elements, respectively, which are found in a mononuclear form in the active site of a diverse group of enzymes that generally catalyze oxygen atom transfer reactions. Mononuclear Mo-containing enzymes have been classified into three families: xanthine oxidase, DMSO reductase, and sulfite oxidase. The proteins of the DMSO reductase family present the widest diversity of properties among its members and our knowledge about this family was greatly broadened by the study of the enzymes nitrate reductase and formate dehydrogenase, obtained from different sources. We discuss in this review the information of the better characterized examples of these two types of Mo enzymes and W enzymes closely related to the members of the DMSO reductase family. We briefly summarize, also, the few cases reported so far for enzymes that can function either with Mo or W at their active site

Structural and electron paramagnetic resonance (EPR) studies of mononuclear molybdenum enzymes from sulfate-reducing bacteria

Acc. Chem. Res., 2006, 39 (10), pp 788–796 DOI: 10.1021/ar050104kMolybdenum and tungsten are found in biological systems in a mononuclear form in the active site of a diverse group of enzymes that generally catalyze oxygen-atom-transfer reactions. The metal atom (Mo or W) is coordinated to one or two pyranopterin molecules and to a variable number of ligands such as oxygen (oxo, hydroxo, water, serine, aspartic acid), sulfur (cysteines), and selenium (selenocysteines) atoms. In addition, these proteins contain redox cofactors such as iron-sulfur clusters and heme groups. All of these metal cofactors are along an electron-transfer pathway that mediates the electron exchange between substrate and an external electron acceptor (for oxidative reactions) or donor (for reductive reactions). We describe in this Account a combination of structural and electronic paramagnetic resonance studies that were used to reveal distinct aspects of these enzymes

Structure of a Sixteen Heme Cytochrome by X-Ray Crystallography.

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Correlating EPR and X-ray structural analysis of arsenite-inhibited forms of aldehyde oxidoreductase

J Biol Inorg Chem (2007) 12:353–366 DOI 10.1007/s00775-006-0191-9Two arsenite-inhibited forms of each of the aldehyde oxidoreductases from Desulfovibrio gigas and Desulfovibrio desulfuricans have been studied by X-ray crystallography and electron paramagnetic resonance (EPR) spectroscopy. The molybdenum site of these enzymes shows a distorted square-pyramidal geometry in which two ligands, a hydroxyl/water molecule (the catalytic labile site) and a sulfido ligand, have been shown to be essential for catalysis. Arsenite addition to active as-prepared enzyme or to a reduced desulfo form yields two different species called A and B, respectively, which show different Mo(V) EPR signals. Both EPR signals show strong hyperfine and quadrupolar couplings with an arsenic nucleus, which suggests that arsenic interacts with molybdenum through an equatorial ligand. X-ray data of single crystals prepared from EPR-active samples show in both inhibited forms that the arsenic atom interacts with the molybdenum ion through an oxygen atom at the catalytic labile site and that the sulfido ligand is no longer present. EPR and X-ray data indicate that the main difference between both species is an equatorial ligand to molybdenum which was determined to be an oxo ligand in species A and a hydroxyl/water ligand in species B. The conclusion that the sulfido ligand is not essential to determine the EPR properties in both Mo-As complexes is achieved through EPR measurements on a substantial number of randomly oriented chemically reduced crystals immediately followed by X-ray studies on one of those crystals. EPR saturation studies show that the electron transfer pathway, which is essential for catalysis, is not modified upon inhibition

X-ray crystal structure and EPR spectra of "arsenite-inhibited" Desulfovibriogigas aldehyde dehydrogenase: a member of the xanthine oxidase family

J. Am. Chem. Soc., 2004, 126 (28), pp 8614–8615 DOI: 10.1021/ja0490222X-ray crystallography has been used to determine the structure of arsenite-inhibited aldehyde dehydrogenase from Desulfovibrio gigas, a member of the xanthine oxidase family of mononuclear molybdenum enzymes. The structure shows an AsO3 moiety bound to the molybdenum atom of the active site through one of the oxygen atoms. A reduced sample of arsenite-inhibited aldehyde dehydrogenase has a Mo(V) signal that shows anisotropic hyperfine and quadrupole coupling to one arsenic atom. This signal has a strong resemblance with a previously reported signal for arsenite-inhibited xanthine oxidase

MEMBRO FANTASMA EM AMPUTADOS DE GUERRA

O membro fantasma é a experiência de possuir um membro ausente que se comporta similarmente ao membro real, englobando a sensação e dor. Os objectivos deste trabalho foi avaliar a prevalência da dor pós-amputação em amputados de guerra, em Portugal, e a sua caracterização. A prevalência da sensação fantasma e dor no coto e as suas implicações na dor fantasma constituem objectivos secundários, assim como o impacto da dor no quotidiano destes doentes e seu bem-estar físico e social

Resgate de germoplasma de Stylosanthes em áreas do semi-árido baiano.

O bioma caatinga apresenta uma paisagem bastante diversificada, na qual se destaca principalmente a família guminosae.Algumas espécies de leguminosas têm potencial para serem empregadas na alimentação animal, permitindo o pastoreio direto ou, sendo conservada, na forma de feno ou silagem. Entre as diversas leguminosas existentes em ambientes tropicais e subtropicais, destaca-se o gênero Stylosanthes. Neste, a maioria das espécies constituintes são perenes, dotadas de um potente sistema radicular, resistente à seca e apresentando boa adaptação a solos de baixa fertilidade. Para enriquecimento do banco de germoplasma de espécies forrageiras da Universidade Estadual de Feira de Santana, no estado da Bahia, foram realizadas expedições para coleta de acessos de Stylosanthes, com os dados de passaporte registrados em caderneta de coleta, com as principais informações tais como latitude e longitude, tipo de solo, de vegetação, dentre outros. Foram feitas exsicatas e os acessos coletados, após a triagem dos frutos e manejo de sementes, foram armazenados em um banco de sementes e acondicionados em potes herméticos com sílica gel; as exsicatas foram depositadas no herbário da Universidade Estadual de Feira de Santana ? HUEFS, onde estão sendo identificados por especialistas. Dentre os 57 acessos coletados, foram identificados cinco espécies, havendo diferenças de cor de sementes e tipo de planta prostrada ou ereta

Neutrino Masses and Mixings from Supersymmetry with Bilinear R--Parity Violation: A Theory for Solar and Atmospheric Neutrino Oscillations

The simplest unified extension of the MSSM with bi-linear R--Parity violation naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino acquires mass by mixing with neutralinos, while the other two get mass radiatively. We have performed a full one-loop calculation of the neutralino-neutrino mass matrix in the bi-linear \rp MSSM, taking special care to achieve a manifestly gauge invariant calculation. Moreover we have performed the renormalization of the heaviest neutrino, needed in order to get meaningful results. The atmospheric mass scale and maximal mixing angle arise from tree-level physics, while solar neutrino scale and oscillations follow from calculable one-loop corrections. If universal supergravity assumptions are made on the soft-supersymmetry breaking terms then the atmospheric scale is calculable as a function of a single \rp violating parameter by the renormalization group evolution due to the non-zero bottom quark Yukawa coupling. The solar neutrino problem must be accounted for by the small mixing angle (SMA) MSW solution. If these assumptions are relaxed then one can implement large mixing angle solutions, either MSW or just-so. The theory predicts the lightest supersymmetic particle (LSP) decay to be observable at high-energy colliders, despite the smallness of neutrino masses indicated by experiment. This provides an independent way to test this solution of the atmospheric and solar neutrino anomalies.Comment: 46 pages, references added + several misprints correcte

Microstructure identification via detrended fluctuation analysis of ultrasound signals

We describe an algorithm for simulating ultrasound propagation in random one-dimensional media, mimicking different microstructures by choosing physical properties such as domain sizes and mass densities from probability distributions. By combining a detrended fluctuation analysis (DFA) of the simulated ultrasound signals with tools from the pattern-recognition literature, we build a Gaussian classifier which is able to associate each ultrasound signal with its corresponding microstructure with a very high success rate. Furthermore, we also show that DFA data can be used to train a multilayer perceptron which estimates numerical values of physical properties associated with distinct microstructures.Comment: Submitted to Phys. Rev.