Ensayo de una metodología innovadora para la detección de masas polimetálicas profundas: modelo geológico y exploración geotérmica preliminares de la Masa Valverde (Huelva).

Se presentan los resultados provisionales de los trabajos iniciales realizados para el Proyecto Innovative Geothermal Methodology to detect deep blind Polymetallic Ore Bodies, financiado por la CE Y co-financiado por DGICYT y organizaciones participantes. Los principales objetivos de este Proyecto son la cuantificación de los efectos térmicos "in situ" de masas polimetálicas profundas a fin de desarrollar nuevos métodos geotérmicos específicos que puedan detectar depósitos no aflorantes. Dichos métodos deberían proporcionar, previsiblemente, un procedimiento rápido y barato para la detección superficial de cuerpos profundos, midiendo perfiles térmicos en sondeos cortos. La exploración geotérmica permite, a diferencia de otros métodos (por ejemplo gravimetría), discriminar anomalías significativas. Para detectar pequeñas anomalías de temperatura (teniendo en cuenta que el efecto térmico decrece rápidamente hacia la superficie), la resolución térmica medida debe ser del orden de O,001ºC. Se han calibrado nuevos termistores muy sensibles en el Laboratoire National d'Essais (LNE) de París para obtener la máxima sensibilidad en el intervalo de temperaturas considerado (lO a 60ºC). Se miden conductividades térmicas sobre testigos con una precisión del 5% y una reproductibilidad del 2%, que permiten determinar las anomalías del gradiente de temperatura relacionadas con las litologías. Para poner a punto el método, se modelizarán las medidas y se compararán con la realidad de cuerpos conocidos, a fin de establecer un modelo fiable y de aplicación general. Esta metodología se ensaya en primer lugar en la MV (Masa Valverde, Huelva), descubierta y reconocida mediante sondeos por la E.N. Adaro, a fin de partir de un modelo suficientemente preciso para la modelización geotérmica. Los trabajos geológicos realizados integran observaciones de campo, examen y desmuestres de testigos de sondeos, geoquímica, geología estructural y estudio de testigos por diversas técnicas como petrografía, microscopía de menas, DRX, MEB, Microsonda Electrónica, etc. A pesar de la profundidad (en torno a los 600 m.l y de la complejidad de la estructura de MV puesta de manifiesto por el presente estudio, los resultados del primer año de investigación geológica -objeto de esta comunicación-, conducen a un modelo provisional que sirve de base a la interpretación de los datos térmicos. Dicho modelo difiere de los anteriormente conocidos en aspectos como: la posición, definición e interpretación de ciertos tramos litológicos; la demostración de muy frecuentes contactos tectónicos acompañados de procesos de deformación dúctil a veces muy intensa; la identificación de fallas o cabalgamientos que definen unidades independientes, entre las cuales los tramos litológicos, incluidos los cuerpos mineralizados, no son correlaciona bies; la estructura del cuerpo mineralizado, caracterizada por una superposición de escamas imbricadas con geometría antiformal, resultado de procesos tectónicos relacionados con la Tectónica de cabalgamientos de la región y recientemente demostrados -ITGE- en la parte española de la FPI (Faja Pirítica Ibérica). Los resultados provisionales arrojan, pues, un resultado coherente desde las diversas perspectivas de trabajo, particularmente por lo que respecta a los modelos geotérmico y geológico - geométrico, y permiten albergar fundadas esperanzas en una rápida puesta a punto del método, para su aplicación en exploración

Evolutionary history of hepatitis C virus genotype 5a in France, a multicenter ANRS study

The epidemic history of HCV genotype 5a is poorly documented in France, where its prevalence is very low, except in a small central area, where it accounts for 14.2% of chronic hepatitis C cases. A Bayesian coalescent phylogenetic investigation based on the E1 envelope gene and a non-structural genomic segment (NS3/4) was carried out to trace the origin of this epidemic using a large sample of genotype 5a isolates collected throughout France. The dates of documented transmissions by blood transfusion were used to calibrate five nodes in the phylogeny. The results of the E1 gene analysis showed that the best-fitting population dynamic model was the expansion growth model under a relaxed molecular clock. The rate of nucleotide substitutions and time to the most recent common ancestors (tMRCA) of genotype 5a isolates were estimated. The divergence of all the French HCV genotype 5a strains included in this study was dated to 1939 [95% HPD: 1921–1956], and the tMRCA of isolates from central France was dated to 1954 [1942–1967], which is in agreement with epidemiological data. NS3/4 analysis provided similar estimates with strongly overlapping HPD values. Phylodynamic analyses give a plausible reconstruction of the evolutionary history of HCV genotype 5a in France, suggesting the concomitant roles of transfusion, iatrogenic route and intra-familial transmission in viral diffusion

Effects of sleep deprivation on neural functioning: an integrative review

Sleep deprivation has a broad variety of effects on human performance and neural functioning that manifest themselves at different levels of description. On a macroscopic level, sleep deprivation mainly affects executive functions, especially in novel tasks. Macroscopic and mesoscopic effects of sleep deprivation on brain activity include reduced cortical responsiveness to incoming stimuli, reflecting reduced attention. On a microscopic level, sleep deprivation is associated with increased levels of adenosine, a neuromodulator that has a general inhibitory effect on neural activity. The inhibition of cholinergic nuclei appears particularly relevant, as the associated decrease in cortical acetylcholine seems to cause effects of sleep deprivation on macroscopic brain activity. In general, however, the relationships between the neural effects of sleep deprivation across observation scales are poorly understood and uncovering these relationships should be a primary target in future research

A search for neutral Higgs bosons in the MSSM and models with two scalar field doublets

A search is described for the neutral Higgs bosons h^0 and A^0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z^0 h^0 and h^0 A^0 production channels is based on data corresponding to an integrated luminosity of 25 pb^{-1} from e^+e^- collisions at centre-of-mass energies between 130 and 172GeV collected with the OPAL detector at LEP. The observation of a number of candidates consistent with Standard Model background expectations is used in combination with earlier results from data collected at the Z^0 resonance to set limits on m_h and m_A in general models with two scalar field doublets and in the MSSM. For example, in the MSSM, for tan(beta) > 1, minimal and maximal scalar top quark mixing and soft SUSY-breaking masses of 1 TeV, the 95% confidence level limits m_h > 59.0 GeV and m_A > 59.5 GeV are obtained. For the first time, the MSSM parameter space is explored in a detailed scan.A search is described for the neutral Higgs bosons h^0 and A^0 predicted by models with two scalar field doublets and, in particular, the Minimal Supersymmetric Standard Model (MSSM). The search in the Z^0 h^0 and h^0 A^0 production channels is based on data corresponding to an integrated luminosity of 25 pb^{-1} from e^+e^- collisions at centre-of-mass energies between 130 and 172 GeV collected with the OPAL detector at LEP. The observation of a number of candidates consistent with Standard Model background expectations is used in combination with earlier results from data collected at the Z^0 resonance to set limits on m_h and m_A in general models with two scalar field doublets and in the MSSM. For example, in the MSSM, for tan(beta) > 1, minimal and maximal scalar top quark mixing and soft SUSY-breaking masses of 1 TeV, the 95% confidence level limits m_h > 59.0 GeV and m_A > 59.5 GeV are obtained. For the first time, the MSSM parameter space is explored in a detailed scan

Spin alignment of leading K∗(892)0K^{*}(892)^{0} mesons in hadronic Z0Z^0 decays

Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The values of the real part of the off-diagonal element rho_1-1 are negative at large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x_p range. The K^*0 fragmentation function has also been measured and the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per hadronic Z^0 decay.Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The values of the real part of the off-diagonal element rho_1-1 are negative at large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x_p range. The K^*0 fragmentation function has also been measured and the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per hadronic Z^0 decay.Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The values of the real part of the off-diagonal element rho_1-1 are negative at large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x_p range. The K^*0 fragmentation function has also been measured and the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per hadronic Z^0 decay.Helicity density matrix elements for inclusive K*(892)^0 mesons from hadronic Z^0 decays have been measured over the full range of K^*0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x_p values above 0.3, with the matrix element rho_00 rising to 0.66 +/- 0.11 for x_p > 0.7. The values of the real part of the off-diagonal element rho_1-1 are negative at large x_p, with a weighted average value of -0.09 +/- 0.03 for x_p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the qq(bar) system from the Z^0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x_p range. The K^*0 fragmentation function has also been measured and the total rate determined to be 0.74 +/- 0.02 +/- 0.02 K*(892)^0 mesons per hadronic Z^0 decay.Helicity density matrix elements for inclusive K ∗ (892) 0 mesons from hadronic Z 0 decays have been measured over the full range of K ∗ 0 momentum using data taken with the OPAL experiment at LEP. A preference for occupation of the helicity zero state is observed at all scaled momentum x p values above 0.3, with the matrix element ϱ 00 rising to 0.66 ± 0.11 for x p > 0.7. The values of the real part of the off-diagonal element ϱ 1 - 1 are negative at large x p , with a weighted average value of −0.09 ± 0.03 for x p > 0.3, in agreement with new theoretical predictions based on Standard Model parameters and coherent fragmentation of the q q system from the Z 0 decay. All other helicity density matrix elements measured are consistent with zero over the entire x p range. The K ∗ 0 fragmentation function has also been measured and the total rate determined to be 0.74 ± 0.02 ± 0.02 K ∗ (892) 0 mesons per hadronic Z 0 decay

Investigation of Transformation Temperatures, Microstructure and Shape Memory Properties of NiTi, NiTiZr and NiTiHf Alloys

The influence of zirconium and hafnium additions in substitution to titanium, is investigated on TiNi shape memory alloy. Microstructural and thermomechanical studies are conducted on an arc-melted Ti38Ni50Hf12 alloy. Results are compared with those of an equiatomic TiNi. We confirm the increase of the phase transformation temperatures due to the additions of Zr and Hf. The presence of oxides in the cast alloy was detected. The lattice parameter is measured from a residue of electroextraction. It was found that a0=1,1547±0,0001nm. A stoichiometry of (Ti, Hf) 4Ni2 Ox (with x≤1) is suggested. It appears that this ternary alloy exhibit an improved shape recovery when it is pre-strained in austenite state (for Ms < T < As) . In this case it displays 100% of recovery for 4% of deformation