Supernova explosions and the birth of neutron stars

We report here on recent progress in understanding the birth conditions of neutron stars and the way how supernovae explode. More sophisticated numerical models have led to the discovery of new phenomena in the supernova core, for example a generic hydrodynamic instability of the stagnant supernova shock against low-mode nonradial deformation and the excitation of gravity-wave activity in the surface and core of the nascent neutron star. Both can have supportive or decisive influence on the inauguration of the explosion, the former by improving the conditions for energy deposition by neutrino heating in the postshock gas, the latter by supplying the developing blast with a flux of acoustic power that adds to the energy transfer by neutrinos. While recent two-dimensional models suggest that the neutrino-driven mechanism may be viable for stars from about 8 solar masses to at least 15 solar masses, acoustic energy input has been advocated as an alternative if neutrino heating fails. Magnetohydrodynamic effects constitute another way to trigger explosions in connection with the collapse of sufficiently rapidly rotating stellar cores, perhaps linked to the birth of magnetars. The global explosion asymmetries seen in the recent simulations offer an explanation of even the highest measured kick velocities of young neutron stars.Comment: 10 pages, 8 figures, 19 ps files; to be published in Proc. of Conf. "40 Years of Pulsars: Millisecond Pulsars, Magnetars, and More", August 12-17, 2007, McGill Univ., Montreal, Canada; high-resolution images can be obtained upon request; incorrect panel in fig.8 replace

Análisis comparativo del uso de las tecnologías de la información y comunicación (TIC), en la gestión empresarial de los hoteles ubicados en la ciudad de Estelí, Nicaragua entre los años 2008 y 2016

La presente investigación está dirigida al análisis de las Tecnologías de Información y Comunicación (TIC) en la gestión hotelera de los hoteles de la ciudad de Estelí, utilizando como referente un estudio realizado en 2008 y comparando resultados con el año 2016, es un estudio de tipo cuantitativo, se aplicaron 19 encuestas a gerentes, administradores de los hoteles y entrevistas para complementar los análisis estadísticos. Como resultado se encontró que hay cambios significativos en la implementación de nuevas tecnologías como: la incorporación de nuevos equipos tecnológicos (hardware), e incremento de programas (software) específicos para hoteles. El 30% de los encuestados afirmó que la principal limitante es la falta de capacitación y el 28% indica que los altos costos para incorporar las TIC, encontrando diferencia en las dificultades entre los dos años. La hipótesis planteada se acepta en un 84% las TIC han provocado cambios en la gestión empresarial y el uso de tecnología está dirigido al marketing de los hoteles a través del internet. Se proponen seis líneas estratégicas para la mejora del uso de las TIC

Internal dynamics of the 3-Pyrroline-N-Oxide ring in spin-labeled proteins

Site-directed spin labeling is a versatile tool to study structure as well as dynamics of proteins using EPR spectroscopy. Methanethiosulfonate (MTS) spin labels tethered through a disulfide linkage to an engineered cysteine residue were used in a large number of studies to extract structural as well as dynamic information on the protein from the rotational dynamics of the nitroxide moiety. The ring itself was always considered to be a rigid body. In this contribution, we present a combination of high-resolution X-ray crystallography and EPR spectroscopy of spin-labeled protein single crystals demonstrating that the nitroxide ring inverts fast at ambient temperature while exhibiting nonplanar conformations at low temperature. We have used quantum chemical calculations to explore the potential energy that determines the ring dynamics as well as the impact of the geometry on the magnetic parameters probed by EPR spectroscopy

Why APRC is misleading and how it should be reformed

The annual percentage rate of charge (APRC) designed to reflect all costs of borrowing is a widely used measure to compare different credit products. It disregards completely, however, risks of possible future changes in interest and exchange rates. As an unintended consequence of the general advice to minimize APRC, many borrowers take adjustable-rate mortgages with extremely short interest rate period or foreign currency denominated loans and run into an excessive risk without really being aware of it. To avoid this, we propose a new, risk-adjusted APRC incorporating also the potential costs of risk hedging. This new measure eliminates most of the virtual advantages of riskier structures and reduces the danger of excessive risk taking. As an illustration, we present the latest Hungarian home loan trends but lessons are universal

Genetic analysis of a rabies virus host shift event reveals within-host viral dynamics in a new host

Host shift events play an important role in epizootics as adaptation to new hosts can profoundly affect the spread of the disease and the measures needed to control it. During the late 1990s, an epizootic in Turkey resulted in a sustained maintenance of rabies virus (RABV) within the fox population. We used Bayesian inferences to investigate whole genome sequences from fox and dog brain tissues from Turkey to demonstrate that the epizootic occurred in 1997 (±1 year). Furthermore, these data indicated that the epizootic was most likely due to a host shift from locally infected domestic dogs, rather than an incursion of a novel fox or dog RABV. No evidence was observed for genetic adaptation to foxes at consensus sequence level and dN/dS analysis suggested purifying selection. Therefore, the deep sequence data were analysed to investigate the sub-viral population during a host shift event. Viral heterogeneity was measured in all RABV samples; viruses from the early period after the host shift exhibited greater sequence variation in comparison to those from the later stage, and to those not involved in the host shift event, possibly indicating a role in establishing transmission within a new host. The transient increase in variation observed in the new host species may represent virus replication within a new environment, perhaps due to increased replication within the CNS, resulting in a larger population of viruses, or due to the lack of host constraints present in the new host reservoir

Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at √s=7 TeV

Bose-Einstein correlations of same-sign charged pions, produced in protonproton collisions at a 7 TeV centre-of-mass energy, are studied using a data sample collected by the LHCb experiment. The signature for Bose-Einstein correlations is observed in the form of an enhancement of pairs of like-sign charged pions with small four-momentum difference squared. The charged-particle multiplicity dependence of the Bose-Einstein correlation parameters describing the correlation strength and the size of the emitting source is investigated, determining both the correlation radius and the chaoticity parameter. The measured correlation radius is found to increase as a function of increasing charged-particle multiplicity, while the chaoticity parameter is seen to decreas