Neutrino Oscillations at Supernova Core Bounce Generate the Strongest Gravitational-Wave Bursts

During the core bounce of a supernova collapse resonant active-to-active ($\nu_a \to \nu_a$), as well as active-to-sterile ($\nu_a \to \nu_s$) neutrino ($\nu$) oscillations can take place. Besides, over this phase weak magnetism increases antineutrino ($\bar{\nu}$) mean free paths, and thus its luminosity. Because the oscillation feeds mass-energy into the target $\nu$ species, the large mass-squared difference between species ($\nu_a \to \nu_s$) implies a huge amount of power to be given off as gravitational waves ($L_{\textrm{GWs}} \sim 10^{49}erg s$^{-1}$), due to anisotropic but coherent$\nu$flow over the oscillation length. This anisotropy in the$\nu$-flux is driven by both the {\it universal spin-rotation} and the spin-magnetic coupling. The new spacetime strain estimated this way is still several orders of magnitude larger than those from$\nu$ diffusion (convection and cooling) or quadrupole moments of the neutron star matter. This new feature turns these bursts the more promising supernova gravitational-wave signal that may be detected by observatories as LIGO, VIRGO, etc., for distances far out to the VIRGO cluster of galaxies.Comment: 10 pages, 1 figure, Proceedings of International Workshop on Astronomy and Relativistic Astrophysics, Olinda (Brazil), October 12-16 (2003), to be published in Int. J. Mod. Phys.

Nonlinear electrodynamics and the Pioneer 10/11 spacecraft anomaly

The occurrence of the phenomenon known as photon acceleration is a natural prediction of nonlinear electrodynamics (NLED). This would appear as an anomalous frequency shift in any modeling of the electromagnetic field that only takes into account the classical Maxwell theory. Thus, it is tempting to address the unresolved anomalous, steady; but time-dependent, blueshift of the Pioneer 10/11 spacecrafts within the framework of NLED. Here we show that astrophysical data on the strength of the magnetic field in both the Galaxy and the local (super)cluster of galaxies support the view on the major Pioneer anomaly as a consequence of the phenomenon of photon acceleration. If confirmed, through further observations or lab experiments, the reality of this phenomenon should prompt to take it into account in any forthcoming research on both cosmological evolution and origin and dynamical effects of primordial magnetic fields, whose seeds are estimated to be very weak.Comment: Final version accepted for publication in Europhysics Letters, uses EPL style, 7 page

Silvopastoral Systems: Analyses of an Alternative to Open Swards

Silvopasture is a sustainable land use management practiced in most continents in the world including parts of southern Europe, but is not broadly used in northern and western Europe. The importance of this practice has been recognised and the last draft of the EU regulation by the European Agricultural Fund for Rural Development (http://europa.eu.int/comm/agriculture/capreform/rurdevprop_en.pdf) includes specifically funding for establishment of agroforestry practices in Europe. This paper discusses the advantages of managing semi intensive grassland within a silvopastoral system from an ecological, productive and social point of view in the south, south-central and western countries of Europe

Neutrino mass spectrum from gravitational waves generated by double neutrino spin-flip in supernovae

The supernova (SN) neutronization phase produces mainly electron ($\nu_e$) neutrinos, the oscillations of which must take place within a few mean-free-paths of their resonance surface located nearby their neutrinosphere. The state-of-the-art on the SN dynamics suggests that a significant part of these $\nu_e$ can convert into right-handed neutrinos in virtue of the interaction of the electrons and the protons flowing with the SN outgoing plasma, whenever the Dirac neutrino magnetic moment be of strength $\mu_\nu < 10^{-11} \mu_{\rm B}$, with $\mu_{\rm B}$ being the Bohr magneton. In the supernova envelope, part of these neutrinos can flip back to the left-handed flavors due to the interaction of the neutrino magnetic moment with the magnetic field in the SN expanding plasma (Kuznetsov & Mikheev 2007; Kuznetsov, Mikheev & Okrugin 2008), a region where the field strength is currently accepted to be $B \gtrsim 10^{13}$ ~G. This type of $\nu$ oscillations were shown to generate powerful gravitational wave (GW) bursts (Mosquera Cuesta 2000, Mosquera Cuesta 2002, Mosquera Cuesta & Fiuza 2004, Loveridge 2004). If such double spin-flip mechanism does run into action inside the SN core, then the release of both the oscillation-produced $\nu_\mu$s, $\nu_\tau$s and the GW pulse generated by the coherent $\nu$ spin-flips provides a unique emission offset $\Delta T^{emission}_{\rm GW} \leftrightarrow \nu = 0$ for measuring the $\nu$ travel time to Earth. As massive $\nu$s get noticeably delayed on its journey to Earth with respect to the Einstein GW they generated during the reconversion transient, then the accurate measurement of this time-of-flight delay by SNEWS + LIGO, VIRGO, BBO, DECIGO, etc., might readily assess the absolute $\nu$ mass spectrum.Comment: 14 pages, 2 figures, ApJ aastex.cls style. In press by The Astrophysical Journa

Isotermas de sorción y transición vítrea de la pulpa de borojó (Borojoa patinoi Cuatr.)

Se han evaluado propiedades fisicoquímicas de la pulpa de borojó fresco y liofilizado, humectado a diferentes niveles de humedad. Se realizaron análisis de humedad (xw), sólidos solubles, ºBrix, carbohidratos (azúcares mayoritarios, pectina (TP) y fibra (TF)), pH, acidez valorable (Ac) y polifenoles totales. Igualmente, se analizaron las isotermas de sorción y se ajustaron adecuadamente a los modelos de BET, GAB, Henderson y Caurie. Las transiciones de fase fueron determinadas mediante calorimetría diferencial de barrido (DSC). Se identificó la temperatura de transición vítrea (Tg) de las muestras en función de la humedad, la Tg de la disolución máximamente crioconcentrada (Tg’ = –46,9 ºC) y la temperatura de formación del último cristal de hielo en el producto (Tm’ = –30,1). La variación de Tg en función de la xw se ajustó al modelo de Gordon y Taylor, lo que permitió obtener la cantidad de agua no congelable de la muestra (Wg’ = 0,177 g agua/g muestra). El análisis conjunto de los datos permitió identificar qué condiciones de almacenamiento ambiente (20 ºC y humedad relativa entre un 35 y un 65%) no aseguran el estado vítreo del borojó liofilizado. Por este motivo, se recomienda la adición de algunas sustancias de alto peso molecular.The physicochemical properties of fresh borojó pulp and lyophilised pulp humidified to different moisture levels were evaluated. Humidity (xw), soluble solids, ºBrix, carbohydrates (major sugars, pectin (TP) and fibre (TF)), pH, titratable acidity (Ac) and total polyphenols were determined. The sorption isotherms were also determined and appropriately fitted to the BET, GAB, Henderson and Caurie models. The phase transitions were determined by differential scanning calorimetry (DSC). The glass transition temperature (Tg) for the samples as a function of humidity, the Tg of the maximally cryoconcentrated solution (Tg’ = -46.9 °C) and the temperature of formation of the last ice crystal in the product (Tm’ = -30.1) were identified. The variation of Tg as a function of xw was fitted to the Gordon and Taylor model, which enabled us to obtain the amount of unfreezable water in the sample (Wg’=0.177 g water/g sample). The combined analysis of the data enabled us to show that ambient storage conditions (20 °C and relative humidity of between 35% and 65%) do not ensure that the vitreous state of lyophilised borojó pulp is maintained. Therefore, the addition of high molecular weight substances is recommended.Ciencias Experimentale

Constraints on Cosmological Models and Reconstructing the Acceleration History of the Universe with Gamma-Ray Burst Distance Indicators

Gamma-ray bursts (GRBs) have been regarded as standard candles at very high redshift for cosmology research. We have proposed a new method to calibrate GRB distance indicators with Type Ia supernova (SNe Ia) data in a completely cosmology-independent way to avoid the circularity problem that had limited the direct use of GRBs to probe cosmology [N. Liang, W. K. Xiao, Y. Liu, and S. N. Zhang, Astrophys. J. 685, 354 (2008).]. In this paper, a simple method is provided to combine GRB data into the joint observational data analysis to constrain cosmological models; in this method those SNe Ia data points used for calibrating the GRB data are not used to avoid any correlation between them. We find that the $\Lambda$CDM model is consistent with the joint data in the 1-$\sigma$ confidence region, using the GRB data at high redshift calibrated with the interpolating method, the Constitution set of SNe Ia, the cosmic microwave background radiation from Wilkinson Microwave Anisotropy Probe five year observation, the baryonic acoustic oscillation from the spectroscopic Sloan Digital Sky Survey Data Release 7 galaxy sample, the x-ray baryon mass fraction in clusters of galaxies, and the observational Hubble parameter versus redshift data. Comparing to the joint constraints with GRBs and without GRBs, we find that the contribution of GRBs to the joint cosmological constraints is a slight shift in the confidence regions of cosmological parameters to better enclose the $\Lambda$CDM model. Finally, we reconstruct the acceleration history of the Universe up to $z>6$ with the distance moduli of SNe Ia and GRBs and find some features that deviate from the $\Lambda$CDM model and seem to favor oscillatory cosmology models; however further investigations are needed to better understand the situation.Comment: 14 pages, 9 figures, 2 tables; v3: the revised version, fig. 6 and some discussions added, accepted for for publication in Phys. Rev. D; v4: the published version (Phys. Rev. D 81, 083518, 2010

Effects of CPT and Lorentz Invariance Violation on Pulsar Kicks

The breakdown of Lorentz's and CPT invariance, as described by the Extension of the Standard Model, gives rise to a modification of the dispersion relation of particles. Consequences of such a modification are reviewed in the framework of pulsar kicks induced by neutrino oscillations (active-sterile conversion). A peculiar feature of the modified energy-momentum relations is the occurrence of terms of the form \delta {\bbox \Pi}\cdot {\bf {\hat p}}, where \delta {\bbox \Pi} accounts for the difference of spatial components of flavor depending coefficients which lead to the departure of the Lorentz symmetry, and ${\bf {\hat p}}={\bf p}/p$, being ${\bf p}$ the neutrino momentum. Owing to the relative orientation of ${\bf p}$ with respect to \delta {\bbox \Pi}, the {\it coupling} \delta {\bbox \Pi}\cdot {\bf {\hat p}} may induce the mechanism to generate the observed pulsar velocities. Topics related to the velocity distribution of pulsars are also discussed.Comment: 10 pages, 1 figur

Anisotropic Pressures in Very Dense Magnetized Matter

The problem of anisotropic pressures arising as a consequence of the spatial symmetry breaking introduced by an external magnetic field in quantum systems is discussed. The role of the conservation of energy and momentum of external fields as well as of systems providing boundary conditions in quantum statistics is considered. The vanishing of the average transverse momentum for an electron-positron system in its Landau ground state is shown, which means the vanishing of its transverse pressure. The situation for neutron case and Strange Quark Matter (SQM) in $\beta$-equilibrium is also briefly discussed. Thermodynamical relations in external fields as well as the form of the stress tensor in a quantum relativistic medium are also discussed. The ferromagnetic symmetry breaking is briefly discussed.Comment: 10 page