Flavor stability analysis of supernova neutrino fluxes compared with simulations

We apply a linearized stability analysis to simplified models of accretion-phase neutrino fluxes streaming from a supernova. We compare the results with recent numerical studies and find excellent agreement. This provides confidence that a linearized stability analysis can be further applied to more realistic models.Comment: Contribution to the Proceedings of HANSE 2011 workshop, 4 pages, 2 figure

Suppression of Self-Induced Flavor Conversion in the Supernova Accretion Phase

Self-induced flavor conversions of supernova (SN) neutrinos can strongly modify the flavor dependent fluxes. We perform a linearized flavor stability analysis with accretion-phase matter profiles of a 15 M_sun spherically symmetric model and corresponding neutrino fluxes. We use realistic energy and angle distributions, the latter deviating strongly from quasi-isotropic emission, thus accounting for both multi-angle and multi-energy effects. For our matter and neutrino density profile we always find stable conditions: flavor conversions are limited to the usual MSW effect. In this case one may distinguish the neutrino mass hierarchy in a SN neutrino signal if the mixing angle theta_13 is as large as suggested by recent experiments.Comment: 4 pages, 5 figures; minor edits, matches the version published in PR

Supernova neutrino halo and the suppression of self-induced flavor conversion

Neutrinos streaming from a supernova (SN) core occasionally scatter in the envelope, producing a small "neutrino halo" with a much broader angle distribution than the primary flux originating directly from the core. Cherry et al. (2012) have recently pointed out that, during the accretion phase, the halo actually dominates neutrino-neutrino refraction at distances exceeding some 100 km. However, the multiangle matter effect (which increases if the angle distribution is broader) still appears to suppress self-induced flavor conversion during the accretion phase.Comment: related to our previous PRL 108 (2012) 061101 [arXiv:1109.3601]; v2 with appendix on analytic treatment of halo, matches the published versio

Investigating Best Practices of Conservation Education for the African Wildlife Foundation

Effective conservation education has the ability to improve educational opportunities and expand environmental support in places where it is implemented. The African Wildlife Foundation (AWF) was founded in 1961 to promote wildlife conservation, land and habitat protection, community empowerment, and economic development across Africa (AWF, 2012). Until recently, AWF had not ventured into the formal education realm and, while they do not currently own or operate schools of their own, the organization is working to develop conservation education curricula to help support its mission. AWF will construct new schools and improve the infrastructure of existing schools to create effective learning environments for conservation topics. This study seeks to provide AWF with expert opinions and related curricular developments to help support their efforts at improving conservation education in Sub-Saharan Africa. A review of relevant literature focusing on the successful development and implementation of conservation education curricula was conducted and analyzed. Live interviews were conducted to obtain views from conservation education experts around the world. Nineteen interviews were conducted in total. These interviews provide expert opinions on environmental education, particularly conservation, in developing nations. Additionally, these interviews highlight existing environmental and conservation education curricula that contemporary experts identify as exemplary, and they include advice and guidance from experts within the education field. Qualitative analyses of these interviews were conducted using NVivo 10 software. Recommendations to AWF were developed based on the information reviewed throughout this process. The research shows that an emphasis on teacher capacity, community involvement, local context of curriculum, long-term project goals, and local relevance must be given significant consideration during curriculum development and implementation in order to maximize the probability of success

An Investigation Of The Impact Of Degree Of IFRS Implementation On The Comparative Accuracy And Bias Of Equity Securities Analysts East And West European Firms Earnings Forecasts

This research investigates the comparative impact of country specific degree of IFRS implementation upon the accuracy and bias of West European and East European firms equity securities analysts earnings forecasts for 29 European countries 12 of which are characterized as being East European.  We utilize measures of equity securities analysts earnings forecast accuracy and bias in making comparisons of the impact of country specific degree of IFRS implementation upon the statistical properties of earnings forecasts for firms having domiciles in East European and West European countries.  Our results indicate that (1) analysts earnings forecast accuracy and earning forecast bias decreases in the sense that their association with magnitudes earnings changes decreases in relation with country specific degree of implementation of IFRS and (2) the degree of reduction in analysts earnings forecast accuracy and bias is statistically more pronounced for East European firms than for West European Firms.  Our results persist after controlling for cross-listing of ADRs on US securities exchanges.   Bases upon this evidence we conclude that the benefits of implementation of IFRS is marginally greater for East European firms that for West European firms

An Investigation Of The Comparative Accuracy And Bias Of Equity Securities Analysts East And West European Firms Earnings Forecasts

This research investigates the comparative accuracy and bias of West European and East European firms equity securities analysts earnings forecasts for 29 European countries 12 of which are characterized as being East European.  We utilize measures of equity securities analysts earnings forecast accuracy and bias in making comparisons of the statistical properties of earnings forecasts for firms having domiciles in East European and West European countries.  Our results indicate that securities analysts earnings forecasts for companies domiciled with East European countries display larger forecast error and greater degree of optimistic forecast bias.  Our results persist after controlling for cross-listing of ADRs on US securities exchanges. We generalize our results using the growing literature on the ever-changing characteristics of the Russian people, Russian business professionals and the rapidly evolving Russian stock market and the transitional Russian political economy

Constraining the cosmic radiation density due to lepton number with Big Bang Nucleosynthesis

The cosmic energy density in the form of radiation before and during Big Bang Nucleosynthesis (BBN) is typically parameterized in terms of the effective number of neutrinos N_eff. This quantity, in case of no extra degrees of freedom, depends upon the chemical potential and the temperature characterizing the three active neutrino distributions, as well as by their possible non-thermal features. In the present analysis we determine the upper bounds that BBN places on N_eff from primordial neutrino--antineutrino asymmetries, with a careful treatment of the dynamics of neutrino oscillations. We consider quite a wide range for the total lepton number in the neutrino sector, eta_nu= eta_{nu_e}+eta_{nu_mu}+eta_{nu_tau} and the initial electron neutrino asymmetry eta_{nu_e}^in, solving the corresponding kinetic equations which rule the dynamics of neutrino (antineutrino) distributions in phase space due to collisions, pair processes and flavor oscillations. New bounds on both the total lepton number in the neutrino sector and the nu_e -bar{nu}_e asymmetry at the onset of BBN are obtained fully exploiting the time evolution of neutrino distributions, as well as the most recent determinations of primordial 2H/H density ratio and 4He mass fraction. Note that taking the baryon fraction as measured by WMAP, the 2H/H abundance plays a relevant role in constraining the allowed regions in the eta_nu -eta_{nu_e}^in plane. These bounds fix the maximum contribution of neutrinos with primordial asymmetries to N_eff as a function of the mixing parameter theta_13, and point out the upper bound N_eff < 3.4. Comparing these results with the forthcoming measurement of N_eff by the Planck satellite will likely provide insight on the nature of the radiation content of the universe.Comment: 17 pages, 9 figures, version to be published in JCA