Charged Current Neutrino Cross Section and Tau Energy Loss at Ultra-High Energies

We evaluate both the tau lepton energy loss produced by photonuclear interactions and the neutrino charged current cross section at ultra-high energies, relevant to neutrino bounds with Earth-skimming tau neutrinos, using different theoretical and phenomenological models for nucleon and nucleus structure functions. The theoretical uncertainty is estimated by taking different extrapolations of the structure function F2 to very low values of x, in the low and moderate Q2 range for the tau lepton interaction and at high Q2 for the neutrino-nucleus inelastic cross section. It is at these extremely low values of x where nuclear shadowing and parton saturation effects are unknown and could be stronger than usually considered. For tau and neutrino energies E=10^9 GeV we find uncertainties of a factor 4 for the tau energy loss and of a factor 2 for the charged current neutrino-nucleus cross section.Comment: 20 pages and 11 figure

Electrochemical Estimation of the Corrosion Rate of Magnesium/Aluminium Alloys

The corrosion rate of AZ31, AZ80, and AZ91D magnesium/aluminium alloys immersed in 3.5 wt.% NaCl was determined comparing gravimetric and electrochemical measurements. The findings revealed that, for all investigated materials, a fraction of the metallic surface exposed to the corrosive medium did not reveal a normal electrochemical response to the applied signal. This may be associated with phenomena such as partial disintegration of specimens into fine metallic particles, electrochemical formation of ions, and/or anomalous chemical attack occurring simultaneously with the normal electrochemical corrosion attack. The abnormal electrochemical behaviour was more evident for lower amounts of aluminium in the bulk composition of the investigated materials. Thus, the electrochemical estimates of pure Mg and the AZ31 alloy were not reliable and tended to underestimate corrosion losses.Peer Reviewe

Effect of Cyclosporin A and Zidovudine on Immune Abnormalities Observed in the Murine Acquired Immunodeficiency Syndrome

Two therapeutic modalities, zidovudine (targeting retroviral replication) and cyclosporin A (targeting immunopathologic consequences of retroviral expression) were evaluated in a murine model of AIDS. In previous studies, cyclosporin A treatment (40 or 60 mg/kg/day) before and after infection with LP-BM5 murine leukemia viruses protected against the development of immunodeficiency disease. The present study extends these findings. First, a low dose of cyclosporin A (20 mg/kg/day) was ineffective, and treatment initiated 5 days after infection did not protect against virus-induced lymphoproliferation and hypergammaglobulinemia. Second, zidovudine added to drinking water (0.1 mg initiated 5 days after infection and continued for 8 weeks) was more effective than 0.2 mg/ml, given day 5–12 after infection. This treatment reduced lymph node size, disease severity as determined histologically, retrovirus-induced gp70 expression, and IgE (but not IgM and IgG) levels. Third, combined treatment had an additive, protective effect on lymphocyte proliferative capacity. This successful dual therapeutic strategy in a mouse model has potential applicability for similar approaches in treating human immunodeficiency virus infection

Feynman scaling violation on baryon spectra in pp collisions at LHC and cosmic ray energies

A significant asymmetry in baryon/antibaryon yields in the central region of high energy collisions is observed when the initial state has non-zero baryon charge. This asymmetry is connected with the possibility of baryon charge diffusion in rapidity space. Such a diffusion should decrease the baryon charge in the fragmentation region and translate into the corresponding decrease of the multiplicity of leading baryons. As a result, a new mechanism for Feynman scaling violation in the fragmentation region is obtained. Another numerically more significant reason for the Feynman scaling violation comes from the fact that the average number of cutted Pomerons increases with initial energy. We present the quantitative predictions of the Quark-Gluon String Model (QGSM) for the Feynman scaling violation at LHC energies and at even higher energies that can be important for cosmic ray physics.Comment: 21 pages, 11 figures, and 1 table. arXiv admin note: substantial text overlap with arXiv:1107.1615, arXiv:1007.320

Correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys

X-ray photoelectron spectroscopy (XPS) was used in order to investigate the correlation between the surface chemistry and the atmospheric corrosion of AZ31, AZ80 and AZ91D magnesium alloys exposed to 98% relative humidity at 50 °C. Commercially pure magnesium, used as the reference material, revealed MgO, Mg(OH)2 and tracers of magnesium carbonate in the air-formed film. For the AZ80 and AZ91D alloys, the amount of magnesium carbonate formed on the surface reached similar values to those of MgO and Mg(OH)2. A linear relation between the amount of magnesium carbonate formed on the surface and the subsequent corrosion behaviour in the humid environment was found. The AZ80 alloy revealed the highest amount of magnesium carbonate in the air-formed film and the highest atmospheric corrosion resistance, even higher than the AZ91D alloy, indicating that aluminium distribution in the alloy microstructure influenced the amount of magnesium carbonate formedThanks to the MCYT for the financial support given to this work (Project MAT2006-13179-C02-01-02)Peer reviewe

Electronic properties of correlated metals in the vicinity of a charge order transition: optical spectroscopy of α\alpha-(BEDT-TTF)2M_2MHg(SCN)4_4 (MM = NH4_4, Rb, Tl)

The infrared spectra of the quasi-two-dimensional organic conductors $\alpha$-(BEDT-TTF)$_2$$M$Hg(SCN)$_4$ ($M$ = NH$_4$, Rb, Tl) were measured in the range from 50 to 7000 \cm down to low temperatures in order to explore the influence of electronic correlations in quarter-filled metals. The interpretation of electronic spectra was confirmed by measurements of pressure dependant reflectance of $\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ at T=300 K. The signatures of charge order fluctuations become more pronounced when going from the NH$_4$ salt to Rb and further to Tl compounds. On reducing the temperature, the metallic character of the optical response in the NH$_4$ and Rb salts increases, and the effective mass diminishes. For the Tl compound, clear signatures of charge order are found albeit the metallic properties still dominate. From the temperature dependence of the electronic scattering rate the crossover temperature is estimated below which the coherent charge-carriers response sets in. The observations are in excellent agreement with recent theoretical predictions for a quarter-filled metallic system close to charge order

Microsolvation of NO3 -: Structural exploration and bonding analysis

Exploration of the potential energy surfaces (PESs) of various microsolvated species associated with the microsolvation of the nitrate anion using density functional theory methods uncovers a rich and complex structural diversity previously unnoticed in the scientific literature for the [NO3(H2O)n]−, n = 1–6 clusters. Two types of interactions are at play in stabilizing the clusters: traditional water to water and charge assisted nitrate to water hydrogen bonds (HBs). The formal negative charge on oxygen atoms in nitrate strengthens hydrogen bonding among water molecules. There is outstanding agreement between available experimental data (sequential hydration enthalpies, IR spectra, and vertical detachment energies) and the corresponding expectation values obtained from our structures. Each PES is heavily populated in the vicinities of the corresponding global minimum with multiple structures contributing to the experimental properties. The last two statements, in conjunction with results from other works (see for example Phys. Chem. Chem. Phys. 2014, 16, 19241) place a warning on the generalized and naive practice of assigning experimental observations to individual structures

Performance of a Permanent-Magnet Cylindrical Hall-Effect Thruster

The performance of a low-power cylindrical Hall thruster, which more readily lends itself to miniaturization and low-power operation than a conventional (annular) Hall thruster, was measured using a planar plasma probe and a thrust stand. The field in the cylindrical thruster was produced using permanent magnets, promising a power reduction over previous cylindrical thruster iterations that employed electromagnets to generate the required magnetic field topology. Two sets of ring-shaped permanent magnets are used, and two different field configurations can be produced by reorienting the poles of one magnet relative to the other. A plasma probe measuring ion flux in the plume is used to estimate the current utilization for the two magnetic topologies. The measurements indicate that electron transport is impeded much more effectively in one configuration, implying higher thrust efficiency. Thruster performance measurements on this configuration were obtained over a power range of 70-350 W and with the cathode orifice located at three different axial positions relative to the thruster exit plane. The thrust levels over this power range were 1.25-6.5 mN, with anode efficiencies and specific impulses spanning 4-21% and 400-1950 s, respectively. The anode efficiency of the permanent-magnet thruster compares favorable with the efficiency of the electromagnet thruster when the power consumed by the electromagnets is taken into account

Interpretations of J/ψJ/\psi suppression

We review the two main interpretations of $J/\psi$ suppression proposed in the literature. The phase transition (or deconfining) scenario assumes that below some critical value of the local energy density (or of some other geometrical quantity which depends both on the colliding systems and on the centrality of the collision), there is only nuclear absorption. Above this critical value the absorptive cross-section is taken to be infinite, i.e. no $J/\psi$ can survive in this hot region. In the hadronic scenario the $J/\psi$ dissociates due both to nuclear absorption and to its interactions with co-moving hadrons produced in the collision. No discontinuity exists in physical observables. We show that an equally good description of the present data is possible in either scenario.Comment: 12 pages, LaTeX, uses epsfig and ioplppt; review talk given by A. Capella at the International Symposium on Strangness in Quark Matter, Santorini (Greece), April 1997; Figs. 1 and 2 not available but can be found in Refs. 13 and 6 respectivel

Refuerzo de la escayola mediante fibras de lana mineral procedentes del reciclaje de rcd

Con la entrada en vigor del Código Técnico de la edificación el uso de lanas minerales está cada día más generalizado tanto en obras de rehabilitación como en obra nueva. Por lo tanto, la generación de residuos de este tipo de material aislante cobra una mayor importancia. El objetivo principal de la investigación que se presenta en esta ponencia es analizar la viabilidad del reciclaje de fibras obtenidas de las lanas minerales procedentes de los RCD como material alternativo a las fibras de vidrio cortadas que se utilizan en la actualidad como elementos de refuerzo en los prefabricados de yeso. Para ello se realizan series de escayola E-35 aditivadas con residuo de lana de roca y con residuo de lana de vidrio en diferentes porcentajes de adición. Dichas series se repiten cambiando este aditivo por fibra de vidrio E de 25mm de longitud con el fin de realizar un análisis comparativo con respecto a las series aditivadas con residuo de lanas minerales. Todas las series se someten al ensayo Shore C para determinar su dureza superficial y a ensayos mecánicos correspondientes para determinar su resistencia a flexotracción y a compresión. A partir de los resultados obtenidos se concluye que, con residuo de lana de roca se aumenta la Dureza Shore C en todos los porcentajes de adición, llegando a mejorar en un 12% con respecto a la fibra de vidrio, con un porcentaje de adición del 2%. Sin embargo, se obtienen valores inferiores de resistencia a flexotracción para todos sus porcentajes de adición. La mayor diferencia, un 50%, aparece con el porcentaje de adición del 4%. En el ensayo de resistencia a compresión los resultados obtenidos en las series aditivadas con residuo de lana de roca son superiores para todos los porcentajes de adición estudiados. La mayor diferencia aparece para el 3% de adición, en el que las series aditivadas con residuo de lana de roca superan en un 36% a las aditivadas con fibra de vidrio. Con respecto a las series aditivadas con residuo de lana de vidrio se concluye que, mejoran la dureza superficial linealmente en torno al 5% para todos los porcentajes de adición, con respecto a las series aditivadas con fibra de vidrio. Los valores de resistencia a flexotracción son superiores hasta el 3% de adición, llegando esta mejora al 26% con el 1% de adición. Los valores obtenidos en el ensayo de resistencia a compresión son mayores para todos los porcentajes de adición, excepto para el 4%. Esta mejora alcanza el 41% para el porcentaje de adición del 3%. Como conclusión final decir que las series aditivadas con lanas minerales procedentes del reciclaje obtienen mejores resultados en los ensayos realizados que las fibras utilizadas en la actualidad como refuerzo del yeso, por lo que resulta viable su sustitución