Searching for tau neutrinos with Cherenkov telescopes

Cherenkov telescopes have the capability of detecting high energy tau neutrinos in the energy range of 1--1000 PeV by searching for very inclined showers. If a tau lepton, produced by a tau neutrino, escapes from the Earth or a mountain, it will decay and initiate a shower in the air which can be detected by an air shower fluorescence or Cherenkov telescope. In this paper, we present detailed Monte Carlo simulations of corresponding event rates for the VERITAS and two proposed Cherenkov Telescope Array sites: Meteor Crater and Yavapai Ranch, which use representative AGN neutrino flux models and take into account topographic conditions of the detector sites. The calculated neutrino sensitivities depend on the observation time and the shape of the energy spectrum, but in some cases are comparable or even better than corresponding neutrino sensitivities of the IceCube detector. For VERITAS and the considered Cherenkov Telescope Array sites the expected neutrino sensitivities are up to factor 3 higher than for the MAGIC site because of the presence of surrounding mountains.Comment: arXiv admin note: text overlap with arXiv:1308.019

Effects of Lightning on Trees: A Predictive Model Based on in situ Electrical Resistivity

The effects of lightning on trees range from catastrophic death to the absence of observable damage. Such differences may be predictable among tree species, and more generally among plant life history strategies and growth forms. We used field‐collected electrical resistivity data in temperate and tropical forests to model how the distribution of power from a lightning discharge varies with tree size and identity, and with the presence of lianas. Estimated heating density (heat generated per volume of tree tissue) and maximum power (maximum rate of heating) from a standardized lightning discharge differed 300% among tree species. Tree size and morphology also were important; the heating density of a hypothetical 10 m tall Alseis blackiana was 49 times greater than for a 30 m tall conspecific, and 127 times greater than for a 30 m tall Dipteryx panamensis. Lianas may protect trees from lightning by conducting electric current; estimated heating and maximum power were reduced by 60% (±7.1%) for trees with one liana and by 87% (±4.0%) for trees with three lianas. This study provides the first quantitative mechanism describing how differences among trees can influence lightning–tree interactions, and how lianas can serve as natural lightning rods for trees

Using cosmic neutrinos to search for non-perturbative physics at the Pierre Auger Observatory

The Pierre Auger (cosmic ray) Observatory provides a laboratory for studying fundamental physics at energies far beyond those available at colliders. The Observatory is sensitive not only to hadrons and photons, but can in principle detect ultrahigh energy neutrinos in the cosmic radiation. Interestingly, it may be possible to uncover new physics by analyzing characteristics of the neutrino flux at the Earth. By comparing the rate for quasi-horizontal, deeply penetrating air showers triggered by all types of neutrinos, with the rate for slightly upgoing showers generated by Earth-skimming tau neutrinos, we determine the ratio of events which would need to be detected in order to signal the existence of new non-perturbative interactions beyond the TeV-scale in which the final state energy is dominated by the hadronic component. We use detailed Monte Carlo simulations to calculate the effects of interactions in the Earth and in the atmosphere. We find that observation of 1 Earth-skimming and 10 quasi-horizontal events would exclude the standard model at the 99% confidence level. If new non-perturbative physics exists, a decade or so would be required to find it in the most optimistic case of a neutrino flux at the Waxman-Bahcall level and a neutrino-nucleon cross-section an order of magnitude above the standard model prediction.Comment: 8 pages revtex, 4 eps figure

Study of The Crystallization of Zeolite NaA by Quasi-Elastic Light-Scattering Spectroscopy and Electron Microscopy

A study of the crystallization of the molecular sieve zeolite NaA from clear aluminosilicate solutions is reported. It was determined by powder X-ray diffraction that zeolite NaA was the only phase in the solid precipitate. The syntheses were monitored in situ by quasi-elastic light scattering spectroscopy. Characteristics of the products were examined by scanning and transmission electron microscopy. Our data show that nuclei formed from the clear aluminosilicate solution, that crystal growth occurred from the solution, that crystal growth was accelerated at elevated temperatures, and that aging the solution at room temperature before raising the synthesis temperature increased both the number of nuclei that formed and also the crystal growth rate for aging times up to a limit. Adding crushed seed crystal fragments to an unaged synthesis solution produced similar results to aging the solution, including reduced induction times, increased crystal growth rates, and polycrystalline product formation

Study of The Effects of Initial-Bred Nuclei on Zeolite NaA Crystallization by Quasi-Elastic Light Scattering Spectroscopy and Electron Microscopy

Synthesis studies have been conducted at 25, 60, and 80 °C with a clear solution batch composition that produces zeolite NaA. Aluminosilicate precursor material was added to promote the synthesis and to evaluate the effects of adding initial-bred nuclei that were created by a precursor “seed” reaction. It is shown that the initial-bred nuclei promoted the crystallization rate, that the crystalline mass produced was increased when using the initial-bred nuclei, and that the nucleation of a second population was not inhibited by the addition of initial-bred nuclei as seeds

Lightning damage stimulates beetle activity in a tropical forest

Disturbance alters the structure of ecological communities. Localized disturbances in tropical rainforests often create canopy gaps - patches of forest where large trees have fallen or are defoliated. Lightning is a major cause of large-tree mortality, and consequently gaps, in tropical forests. Lightning-caused gaps consist of abundant dead standing wood which likely is a predictable resource for saproxylic arthropods, specifically wood-boring beetles (Coleoptera). The goal of this study was to provide a preliminary evaluation of the beetles that are attracted to lightning-damaged trees in a tropical forest. We placed flight intercept traps in the subcanopy of 8 trees (4 struck trees and 4 unaffected trees of the same size and species) on Barro Colorado Island, Panama in 2018. Collected beetles were counted and identified to subfamily. Abundance analyses focused on Platypodinae (pinhole borers) and Scolytinae (bark beetles), both of which were significantly more abundant near struck trees vs. unaffected trees. These results suggest that the dead wood of trees struck by lightning is an identifiable resource for saproxylic beetles. Ongoing research will examine differences in beetle communities associated with treefall gaps and lightning gaps. Ultimately, this research will clarify the relevance of lightning to the maintenance of beetle diversity in tropical forests.https://ir.library.louisville.edu/uars/1024/thumbnail.jp

The epidemiology and outcomes of central nervous system infections in Far North Queensland, tropical Australia; 2000-2019

Background The epidemiology of central nervous system (CNS) infections in tropical Australia is incompletely defined. Methods A retrospective study of all individuals in Far North Queensland, tropical Australia, who were diagnosed with a CNS infection between January 1, 2000, and December 31, 2019. The microbiological aetiology of the infection was correlated with patients' demographic characteristics and their clinical course. Results There were 725 cases of CNS infection during the study period, meningitis (77.4%) was the most common, followed by brain abscess (11.6%), encephalitis (9.9%) and spinal infection (1.1%). Infants (24.3%, p<0.0001) and Aboriginal and Torres Strait Islander Australians (175/666 local residents, 26.3%, p<0.0001) were over-represented in the cohort. A pathogen was identified in 513 cases (70.8%); this was viral in 299 (41.2%), bacterial in 175 (24.1%) and fungal in 35 (4.8%). Cryptococcal meningitis (24 cases) was diagnosed as frequently as pneumococcal meningitis (24 cases). There were only 2 CNS infections with a S. pneumoniae serotype in the 13-valent pneumococcal vaccine after its addition to the National Immunisation schedule in 2011. Tropical pathogens-including Cryptococcus species (9/84, 11%), Mycobacterium tuberculosis (7/84, 8%) and Burkholderia pseudomallei (5/ 84, 6%)-were among the most common causes of brain abscess. However, arboviral CNS infections were rare, with only one locally acquired case-a dengue infection in 2009-diagnosed in the entire study period. Intensive Care Unit admission was necessary in 14.3%; the overall case fatality rate was 4.4%. Conclusion Tropical pathogens cause CNS infections as commonly as traditional bacterial pathogens in this region of tropical Australia. However, despite being highlighted in the national consensus guidelines, arboviruses were identified very rarely. Prompt access to sophisticated diagnostic and supportive care in Australia's well-resourced public health system is likely to have contributed to the cohort's low case-fatality rate