Sterile neutrinos, dark matter, and resonant effects in ultra high energy regimes

Interest in light dark matter candidates has recently increased in the literature; some of these works consider the role of additional neutrinos, either active or sterile. Furthermore, extragalactic neutrinos have been detected with energies higher than have ever been reported before. This opens a new window of opportunities to the study of neutrino properties that were unreachable up to now. We investigate how an interaction potential between neutrinos and dark matter might induce a resonant enhancement in the oscillation probability, an effect that may be tested with future neutrino data.Comment: 11 pages, 2 figures, to be published in PL

Suppression of viscous fluid fingering: a piecewise constant-injection process

The injection of a fluid into another of larger viscosity in a Hele-Shaw cell usually results in the formation of highly branched patterns. Despite the richness of these structures, in many practical situations such convoluted shapes are quite undesirable. In this letter we propose an efficient and easily reproducible way to restrain these instabilities based on a simple piecewise constant pumping protocol. It results in a reduction in the size of the viscous fingers by one order of magnitude.Comment: Published in Phys. Rev.

The reactor antineutrino anomaly and low energy threshold neutrino experiments

Short distance reactor antineutrino experiments measure an antineutrino spectrum a few percent lower than expected from theoretical predictions. In this work we study the potential of low energy threshold reactor experiments in the context of a light sterile neutrino signal. We discuss the perspectives of the recently detected coherent elastic neutrino-nucleus scattering in future reactor antineutrino experiments. We find that the expectations to improve the current constraints on the mixing with sterile neutrinos are promising. We also analyse the measurements of antineutrino scattering off electrons from short distance reactor experiments. In this case, the statistics is not competitive with inverse beta decay experiments, although future experiments might play a role when compare it with the Gallium anomaly.Comment: 9 pages, 6 figures, 1 table, matches published versio

Epidemiology of cattle diseases in the northeast of La Pampa, Argentina

A cross-sectional survey was carried out on 350 farms in the north east of La Pampa Province, Argentina. The goal was to record the prevalence of cattle diseases reported by farmers. Farms wereA stratified into three categories on the basis of adult herd size (300 to 500 cattle, 500 to 900 cattle and greater than 900 cattle) and a random sample selected from each strata. According to the productive system, farms were classified as fattening (F), cow-calf (C) and cow-calf-fattening (CF). Presented data are part of a comprehensive survey on cattle farms performed by INTA and Ministry of Production staff. The information described on this assay corresponds to principal signs and health problems recorded in different farms. Actinosis (n=115 farms), bovine respiratory diseases (BRD) (n=77), neonatal calf diarrhea (NCD) (n=60), copper deficiency (n=54), and blackleg, gas gangrene and enterotoxaemia (BGE) (n=39) were the main diseases. NCD and BGE were geographically distributed on the southern half area, while actinosis, copper deficiency and pneumonia were distributed on the central-west area. BRD also showed a second risk area on the northwest. According to production system, BRD was found to be associated to F, while NCD, copper deficiency and BGE were associated to CF. According to strata level, no differences were found for any diseases considered for the present essay

Massive Black Hole Binary Systems in Hierarchical Scenario of Structure Formation

The hierarchical scenario of structure formation describes how objects like galaxies and galaxy clusters are formed by mergers of small objects. In this scenario, mergers of galaxies can lead to the formation of massive black hole (MBH) binary systems. On the other hand, the merger of two MBH could produce a gravitational wave signal detectable, in principle, by the Laser Interferometer Space Antenna (LISA). In the present work, we use the Press-Schechter formalism, and its extension, to describe the merger rate of haloes which contain massive black holes. Here, we do not study the gravitational wave emission of these systems. However, we present an initial study to determine the number of systems formed via mergers that could permit, in a future extension of this work, the calculation of the signature in gravitational waves of these systems.Comment: to match the published version in International Journal of Modern Physics