Ultra High Energy Tau Neutrinos and Fluorescence Detectors: A Phenomenological Approach

We investigate the possibility of detecting ultra-high energy cosmic tau-neutrinos by means of a process involving a double extensive air shower, the so-called Double-Bang Phenomenon. In this process a primary tau-neutrino interacts with an atmospheric quark creating a hadronic extensive air shower that contains a tau which subsequently decays creating a second extensive air shower. The number of these events strongly depends on the cross section and on the flux of ultra-high energy tau-neutrinos arriving at the Earth's atmosphere. We estimate the potential of optical detectors to observe Double-Bang events induced by tau-neutrinos with energies of about 1 EeV whose detection may confirm the maximal mixing observed in the atmospheric neutrinos also for ultra-high energy neutrinos, and give information on the neutrino flux and cross-section. For neutrino-nucleon Standard Model extrapolated cross-section and thick source model of flux (MPR), we estimate an event rate of 0.48/yr for an observatory with two fluorescence detectors with 90% efficiency in the neutrino energy range 0.5 < E_nu < 5 EeV.Comment: 17 pages, 6 eps figures, revtex 4, new calculation for the interaction probability end efficienc

AVALIAÇÃO DE REGISTROS SEDIMENTARES NA ÁREA DA ENCOSTA DA FACE LESTE DO DOMO DE ITABAIANA-SE: RESULTADOS PRELIMINARES

O Quaternário é reconhecido por variações das condições climáticas que deixaram na paisagem marcas dessas oscilações. O trabalho objetivou reconhecer características dos depósitos e estruturas presentes nas seções. A encosta encontra-se numa área susceptível as mudanças na sua estrutura, remodelando a forma do relevo, onde foram encontradas depósitos referentes a eventos de grande magnitude ou de alta torrencialidade capaz de remobilizar mantos de alteração em forma de fluxos em curtos

Sensitivity on Earth Core and Mantle densities using Atmospheric Neutrinos

Neutrino radiography may provide an alternative tool to study the very deep structures of the Earth. Though these measurements are unable to resolve the fine density layer features, nevertheless the information which can be obtained are independent and complementary to the more conventional seismic studies. The aim of this paper is to assess how well the core and mantle averaged densities can be reconstructed through atmospheric neutrino radiography. We find that about a 2% sensitivity for the mantle and 5% for the core could be achieved for a ten year data taking at an underwater km^3 Neutrino Telescope. This result does not take into account systematics related to the details of the experimental apparatus.Comment: 11 pages, 11 figures, accepted for publication in JCA

A clinically aligned experimental approach for quantitative characterization of patient-specific cardiovascular models

Recent improvements in computational tools opened the possibility of patient-specific modeling to aid clinicians during diagnosis, treatment, and monitoring. One example is the modeling of blood flow for surgical planning, where modeling can help predict the prognosis. Computational analysis is used to extract hemodynamic information about the case; however, these methods are sensitive to assumptions on blood properties, boundary conditions, and appropriate geometry accuracy. When available, experimental measurements can be used to validate the results and, among the modalities, ultrasound-based methods are suitable due to their relative low cost and non-invasiveness. This work proposes a procedure to create accurate patient-specific silicone replicas of blood vessels and a power Doppler compatible experimental setup able to simulate and measure realistic flow conditions. The assessment of silicone model geometry shows small discrepancies between these and the target geometries (median of surface error lies within 57 µm and 82 μm). Power Doppler measurements were compared against computational fluid dynamics results, showing discrepancies within 10% near the wall. The experimental approach offers a setup to quantify flow in in vitro systems and provide more accurate results where other techniques (e.g., particle image velocimetry and particle tracking velocimetry) have shown limitations due to the interference of the interface

A reduction in the UHE neutrino flux due to neutrino spin precession

Motivated by the stringent flux limits for UHE neutrinos coming from gamma ray burst or active galactic nuclei, we explore the possibility that the active neutrinos generated in such astrophysical objects could oscillate to sterile right handed states due to a neutrino magnetic moment mu_nu. We find that a value as small as mu_nu ~1E-15 mu_B could produce such a transition thanks to the intense magnetic fields that are expected in these objects.Comment: 5 pages, 1 figure, to appear in Physics Letters

A Review of Sympathetic and Parasympathetic Innervation in the Structural and Functional Maintenance of the Male Gonad

The nervous system controls and coordinates the functions of all body systems, including the male reproductive system. The male gonad, responsible for spermatogenesis and steroidogenesis, receives autonomous sympathetic and parasympathetic innervation, having a great influence on the structural and functional integrity of this organ. The testis receives autonomic innervation primarily at the superior and inferior poles, specifically by the superior and inferior spermatic nerves. This nervous control is wired into all testicular cell populations such as contractile cells (myoid cells), germ cells, and steroidogenic cells. Many studies have also described the influence of autonomic innervation on Sertoli cell control. Thus, any possible interference of physical or chemical agents whose action is directly or indirectly linked to the nervous control of the testicle can result in changes and/or damage to male reproduction, with emphasis on testicular impairment. The present chapter consists of a review of data about the effects of physical or chemical alterations on the autonomous innervation and its repercussions on male gonad. For this, it is necessary to understand the general aspect of the nervous system and the male gonad morphology and innervation, as well as the action of drugs or any methods that promote changes in the communication between these two systems

Trabalho, terra e geração de renda em três décadas de reflorestamentos no alto Jequitinhonha.

A partir dos anos 1970, as chapadas do Alto Jequitinhonha, localizadas no nordeste de Minas Gerais, até então áreas de uso comum de agricultores familiares, foram plantadas com eucaliptos. O objetivo deste artigo é comparar os efeitos do reflorestamento sobre a estrutura fundiária, valor da produção agrícola e ocupação rural com os efeitos da produção agrícola familiar sobre essas mesmas variáveis na microrregião homogênea de Capelinha, no Alto Jequitinhonha. Tal microrregião foi escolhida para o estudo por ser a área de maior concentração de eucaliptais da região. Foram utilizados dados secundários dos Censos do IBGE para os anos de 1970, 1980, 1985 e 1996, além de dados secundários de pesquisas realizadas sobre a região em questão, incluindo entrevistas com dirigentes de empresas e lideranças sindicais. O artigo conclui que, em trinta anos, o reflorestamento concentrou terras e criou um número reduzido de empregos; a agricultura familiar, ao contrário, teve suas áreas de terras comprimidas e super-exploradas em decorrência da perda das chapadas, mas continuou sendo a principal responsável pela geração de ocupações e rendas na região

Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure