3,900 research outputs found

    Local and nonlocal solvable structures in ODEs reduction

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    Solvable structures, likewise solvable algebras of local symmetries, can be used to integrate scalar ODEs by quadratures. Solvable structures, however, are particularly suitable for the integration of ODEs with a lack of local symmetries. In fact, under regularity assumptions, any given ODE always admits solvable structures even though finding them in general could be a very difficult task. In practice a noteworthy simplification may come by computing solvable structures which are adapted to some admitted symmetry algebra. In this paper we consider solvable structures adapted to local and nonlocal symmetry algebras of any order (i.e., classical and higher). In particular we introduce the notion of nonlocal solvable structure

    NIKEL_AMC: Readout electronics for the NIKA2 experiment

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    The New Iram Kid Arrays-2 (NIKA2) instrument has recently been installed at the IRAM 30 m telescope. NIKA2 is a state-of-art instrument dedicated to mm-wave astronomy using microwave kinetic inductance detectors (KID) as sensors. The three arrays installed in the camera, two at 1.25 mm and one at 2.05 mm, feature a total of 3300 KIDs. To instrument these large array of detectors, a specifically designed electronics, composed of 20 readout boards and hosted in three microTCA crates, has been developed. The implemented solution and the achieved performances are presented in this paper. We find that multiplexing factors of up to 400 detectors per board can be achieved with homogeneous performance across boards in real observing conditions, and a factor of more than 3 decrease in volume with respect to previous generations.Comment: 21 pages; 16 figure

    Nonlocal aspects of λ\lambda-symmetries and ODEs reduction

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    A reduction method of ODEs not possessing Lie point symmetries makes use of the so called λ\lambda-symmetries (C. Muriel and J. L. Romero, \emph{IMA J. Appl. Math.} \textbf{66}, 111-125, 2001). The notion of covering for an ODE Y\mathcal{Y} is used here to recover λ\lambda-symmetries of Y\mathcal{Y} as nonlocal symmetries. In this framework, by embedding Y\mathcal{Y} into a suitable system Yâ€Č\mathcal{Y}^{\prime} determined by the function λ\lambda, any λ\lambda-symmetry of Y\mathcal{Y} can be recovered by a local symmetry of Yâ€Č\mathcal{Y}^{\prime}. As a consequence, the reduction method of Muriel and Romero follows from the standard method of reduction by differential invariants applied to Yâ€Č\mathcal{Y}^{\prime}.Comment: 13 page

    Rodents as natural hosts of zoonotic Schistosoma species and hybrids: an epidemiological and evolutionary perspective from West Africa

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    The complex multi-host disease dynamics of schistosomiasis and Schistosoma spp., including the emergence of zoonotic parasite hybrids, remain largely unexplored in West Africa. We elucidated the role of wild small mammals as reservoir for zoonotic Schistosoma species and hybrids in endemic areas of Senegal. We identified Schistosoma mansoni, Schistosoma bovis, and a Schistosoma haematobium/S. bovis hybrid, with local prevalence in wild rodents ranging from 1.9% to 28.6%. Our findings indicate that rodents may be an important local reservoir for zoonotic schistosomiasis in endemic areas of West Africa, amplifying transmission to humans and acting as natural definitive hosts of schistosome hybrids

    ESAF-Simulation of the EUSO-Balloon

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    For the JEM-EUSO CollaborationThe EUSO-Balloon is a balloon borne ultraviolet (UV) telescope, which is being developed as a pathfinder of the JEM-EUSO mission (Extreme Universe Space Observatory onboard the Japanese Experiment Module on the International Space Station (ISS), see this conference proceedings). Designed as a scaled version of JEM-EUSO, the EUSO-Balloon will serve as a technology demonstrator. From 2014 on, it is planned to conduct a number of missions, between a few and several tens of hours at an altitude of approx. 40 km. Besides proving the robustness of the JEM-EUSO technology it will perform UV background studies under many different ground conditions and potentially observe extended air showers (EAS) induced by ultra-high-energy cosmic rays (UHECR) of the order of 10^18 eV. The detector design consists of a system of Fresnel lenses focussing the incoming 300 - 400 nm UV fluorescence photons onto an array of multi-anode photomultipliers. Generated photoelectrons are then readout by the front end electronics, converted into digital data and saved to disc if a trigger is issued. The ESAF (EUSO Simulation and Analysis Framework) software package is designed to simulate space based observation of EAS, taking into account every physical process from EAS generation, progagation of light in atmosphere, detector response and eventually reconstruction. EUSO-Balloon specifications such as the optics and dedicated electronics components have been implemented in the code to study the expected instrument behavior and its ability to resolve the UHECR arrival direction. In this poster we describe ESAF simuations of the EUSO-Balloon. Furthermore, we present results concerning the expected performance in terms of spatial resolution and background studies

    Oxidative Alteration of Ferrous Smectites: A Formation Pathway for Martian Nontronite?

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    Ferric (Fe3+-bearing) smectites, including nontronite, constitute the majority of hydrous mineral exposures observed on Mars. These smectite exposures are commonly interpreted as weathering products of Martian basaltic crust. However, ferrous (Fe2+-dominated) smectites, not ferric, are the thermo-dynamically predicted products of weathering in anoxic conditions, as predicted for early Mars. Earth was anoxic until the Proterozoic Great Oxidation Event; Mars likely experienced an analogous oxidative evolution to its present oxidized state, but the timing of this evolution is unresolved. We hypothesize that Fe3+-smectites observed by orbital spectroscopy are not the initial products of Noachian-era chemical weathering, but are instead the oxidative products of primary Fe2+-smectites. To test this hypothesis experimentally, we synthesized ferrous smectites and exposed them to Mars-relevant oxidants

    Retrieval of Compositional Endmembers from Mars Exploration Rover Opportunity Observations in a Soil-filled Fracture in Marathon Valley, Endeavour Crater Rim

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    The Opportunity rover investigated a gentle swale on the rim of Endeavour crater called Marathon Valley where a series of bright planar outcrops are cut into polygons by fractures. A wheel scuff performed on one of the soil-filled fracture zones revealed the presence of three end-members identified on the basis of Pancam multispectral imaging observations covering ~0.4 to 1 ÎŒm: red and dark pebbles, and a bright soil clod. Multiple overlapping Alpha Particle X-ray Spectrometer (APXS) measurements were collected on three targets within the scuff zone. The field of view of each APXS measurement contained various proportions of the Pancam-based end-members. Application of a log maximum likelihood method for retrieving the composition of the end-members using the 10 APXS measurements shows that the dark pebble end-member is compositionally similar to average Mars soil, with slightly elevated S and Fe. In contrast, the red pebble end-member exhibits enrichments in Al and Si and is depleted in Fe and Mg relative to average Mars soil. The soil clod end-member is enriched in Mg, S, and Ni. Thermodynamic modeling of the soil clod end-member composition indicates a dominance of sulfate minerals. We hypothesize that acidic fluids in fractures leached and oxidized the basaltic host rock, forming the red pebbles, and then evaporated to leave behind sulfate-cemented soil

    Retrieval of Compositional End-Members From Mars Exploration Rover Opportunity Observations in a Soil-Filled Fracture in Marathon Valley, Endeavour Crater Rim

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    The Opportunity rover investigated a gentle swale on the rim of Endeavour crater called Marathon Valley where a series of bright planar outcrops are cut into polygons by fractures. A wheel scuff performed on one of the soil‐filled fracture zones revealed the presence of three end‐members identified on the basis of Pancam multispectral imaging observations covering ~0.4 to 1 ÎŒm: red and dark pebbles, and a bright soil clod. Multiple overlapping Alpha Particle X‐ray Spectrometer (APXS) measurements were collected on three targets within the scuff zone. The field of view of each APXS measurement contained various proportions of the Pancam‐based end‐members. Application of a log maximum likelihood method for retrieving the composition of the end‐members using the 10 APXS measurements shows that the dark pebble end‐member is compositionally similar to average Mars soil, with slightly elevated S and Fe. In contrast, the red pebble end‐member exhibits enrichments in Al and Si and is depleted in Fe and Mg relative to average Mars soil. The soil clod end‐member is enriched in Mg, S, and Ni. Thermodynamic modeling of the soil clod end‐member composition indicates a dominance of sulfate minerals. We hypothesize that acidic fluids in fractures leached and oxidized the basaltic host rock, forming the red pebbles, and then evaporated to leave behind sulfate‐cemented soil

    K*(892)(0) and phi(1020) production at midrapidity in pp collisions at root s=8 TeV

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    The production of K* (892)(0) and phi(1020) in pp collisions at root s = 8 TeV was measured by using Run 1 data collected by the ALICE collaboration at the CERN Large Hadron Collider (LHC). The P-T-differential yields d(2)N/dydp(T), in the range 0 < p(T) < 20 GeV/c for K*(0) and 0.4 < p(T) < 16 GeV/c for phi have been measured at midrapidity, vertical bar y vertical bar < 0.5. Moreover, improved measurements of the K*(0)(892) and phi (1020) at root s = 7 TeV are presented. The collision energy dependence of p(T) distributions, p(T)-integrated yields, and particle ratios in inelastic pp collisions are examined. The results are also compared with different collision systems. The values of the particle ratios are found to be similar to those measured at other LHC energies. In pp collisions a hardening of the particle spectra is observed with increasing energy, but at the same time it is also observed that the relative particle abundances are independent of the collision energy. The P-T-differential yields of K*(0) and phi in pp collisions at root s = 8 TeV are compared with the expectations of different Monte Carlo event generators
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