21,096 research outputs found

    Hinting at primary composition using asymmetries in time distributions

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    Evidence of azimuthal asymmetries in the time structure and signal size have been found in non-vertical showers at the Pierre Auger Observatory. It has been previously shown that the asymmetry in time distributions offers a new possibility for the determination of the mass composition. New studies have demonstrated that the dependence of the asymmetry parameter in the rise-time and fall-time distributions with sec(theta) shows a clear peak. Both, the position of the peak, X_asymax, and the size of the asymmetry at X_asymax are sensitive to primary mass composition and have a small dependence on energy. In this paper a study of the discriminating power of the new observables to separate primary species is presented.Comment: To be published in the Proceedings of 29th International Cosmic Ray Conference (ICRC 2005), Pune, India, August 3-10, 200

    Comment on the Adiabatic Condition

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    The experimental observation of effects due to Berry's phase in quantum systems is certainly one of the most impressive demonstrations of the correctness of the superposition principle in quantum mechanics. Since Berry's original paper in 1984, the spin 1/2 coupled with rotating external magnetic field has been one of the most studied models where those phases appear. We also consider a special case of this soluble model. A detailed analysis of the coupled differential equations and comparison with exact results teach us why the usual procedure (of neglecting nondiagonal terms) is mathematically sound.Comment: 9 page

    Electron cloud buildup and impedance effects on beam dynamics in the future circular e+e− collider and experimental characterization of thin TiZrV vacuum chamber coatings

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    The Future Circular Collider FCC-ee is a study toward a high luminosity electron-positron collider with a centre-of-mass energy from 91 GeV to 365 GeV. Due to the beam parameters and pipe dimensions, collective effects and electron cloud can be very critical aspects for the machine and can represent the main limitations to its performance. An estimation of the electron cloud build up in the main machine components and an impedance model are required to analyze the induced instabilities and to find solutions for their mitigation. Special attention has been given to the resistive wall impedance associated with a layer of nonevaporable getter (NEG) coating on the vacuum chamber required for electron cloud mitigation. The studies presented in this paper will show that minimizing the thickness of this coating layer is mandatory to increase the single bunch instability thresholds in the proposed lepton collider at 45.6 GeV. For this reason, NEG thin films with thicknesses below 250 nm have been investigated by means of numerical simulations to minimize the resistive wall impedance. In parallel, an extensive measurement campaign was performed at CERN to characterize these thin films, with the purpose of finding the minimum effective thickness satisfying vacuum and electron cloud requirements

    Studies on Reticulitermes lucifugus Rossi (Isoptera: Rhinotermitidae): a review of associated hindgut flagellates and investigations on protist species of the Sicilian subspecies, R. lucifugus \u201cSicily\u201d

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    The present study was conducted on protist species from R. lucifugus \u201cSicily\u201d subspecies in a field site of Palermo (Sicily, Italy) on June 2015. Since protist species associated with R. lucifugus in Europe are still confused and recent revisions are lacking, this work aims at achieving greater clarity on these symbiosis trough a review of the literature in light of new phylogenetic studies on this termite species. The purpose of this work was also to highlight and quantify protists associated with the Sicilian subspecies, R. l. \u201cSicily\u201d. Results pointed out the real protist community attributable to R. lucifugus from the literature and showed 13 protist species detected in the subspecies R. l. \u201cSicily\u201d. These species were consistent with previous reports except for Spironympha sp., mentioned for the first time from this termite. Total protist population estimates was 26,814.71 \ub1 1,121.92 protists per termite. Dinenympha exilis and D. gracilis were found in greater abundance with relative species abundance of 17%. Monocercomonas termitis, Microjoenia hexamitoides, Trichonympha minor and Pyrsonympha flagellata could be used to distinguish R. lucifugus because these protists are not found in other Reticulitermes species

    Shear strength of adhesively bonded polyolefins with minimal surface preparation

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    Interest in polyethylene and polypropylene bonding has increased in the last years. However, adhesive joints with adherends which are of low surface energy and which are chemically inert present several difficulties. Generally, their high degree of chemical resistance to solvents and dissimilar solubility parameters limit the usefulness of solvent bonding as a viable assembly technique. One successful approach to adhesive bonding of these materials involves proper selection of surface pre-treatment prior to bonding. With the correct pre-treatment it is possible to glue these materials with one or more of several adhesives required by the applications involved. A second approach is the use of adhesives without surface pre-treatment, such as hot melts, high tack pressure-sensitive adhesives, solvent-based specialty adhesives and, more recently, structural acrylic adhesives as such 3M DP-8005® and Loctite 3030®. In this paper, the shear strengths of two acrylic adhesives were evaluated using the lap shear test method ASTM D3163 and the block shear test method ASTM D4501. Two different industrial polyolefins (polyethylene and polypropylene) were used for adherends. However, the focus of this study was to measure the shear strength of polyethylene joints with acrylic adhesives. The effect of abrasion was also studied. Some test specimens were manually abraded using 180 and 320 grade abrasive paper. An additional goal of this work was to examine the effect of temperature and moisture on mechanical strength of adhesive joints

    Sifting composite from elementary models at FCCee and CePC

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    New Physics models with either an elementary or composite origin are often associated with a similar imprint in a direct search at colliders, case in point being the production of a light pseudoscalar in association with a monochromatic photon from the decay of a Z boson at future e+ee+e- colliders. We exploit the correlation between the discovery of a signal in the Z decays and electroweak precision measurements as a tool to distinguish a composite model from an elementary scalar one. Our results offer an appealing and rich physics case for future colliders and demonstrate how a lepton collider at the Z mass can be a discovery machine for new physics in the Higgs sector.Comment: 7 Pages, 2 Figure

    Innovative business models

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    One of the biggest challenges media businesses are facing is the redefinition of distribution and consumption patterns, shifting from traditional channels such as print, real time radio and TV to online, including digital formats like on-demand videos and podcasts. This digital revolution demands media workers and managers to consider a change from the former one-size-fits-all business model to a panoply of tailor-made models.info:eu-repo/semantics/publishedVersio

    The distance to the LMC cluster NGC 1866 and the surrounding field

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    We use the Main Sequence stars in the LMC cluster NGC 1866 and of Red Clump stars in the local field to obtain two independent estimates of the LMC distance. We apply an empirical Main Sequence-fitting technique based on a large sample of subdwarfs with accurate {\sl Hipparcos} parallaxes in order to estimate the cluster distance modulus, and the multicolor Red Clump method to derive distance and reddening of the LMC field. We find that the Main Sequence-fitting and the Red Clump distance moduli are in significant disagreement; NGC 1866 distance is equal to (mM)0,NGC1866=18.33±\rm (m-M)_{0,NGC 1866}=18.33\pm0.08 (consistent with a previous estimate using the same data and theoretical Main Sequence isochrones), while the field stars provide (mM)0,field=18.53±\rm (m-M)_{0,field}=18.53\pm0.07. This difference reflects the more general dichotomy in the LMC distance estimates found in the literature. Various possible causes for this disagreement are explored, with particular attention paid to the still uncertain metallicity of the cluster and the star formation history of the field stars.Comment: 5 pages, incl. 1 figure, uses emulateapj.sty, ApJ accepte

    AI and journalism, robot journalism and algorithms

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    Automated journalism is also known as algorithmic journalism or robot journalism and consists of news articles generated by computer programmes. Through artificial intelligence (AI) software, stories are produced automatically by computers rather than human reporters. These programmes interpret, organise, and present data in human-readable ways. The process involves an algorithm that scans large amounts of data, selects from an assortment of preprogrammed article structures, orders key points, and inserts details such as names, places, amounts, rankings, statistics, and other figures. The output can also be customized to fit a certain voice, tone, or style. Until now, despite it being a growing trend, not that many media outlets worldwide have used automated journalism on a large scale. Pioneer adopters include The Associated Press, Forbes, ProPublica, and The Los Angeles Times. Early implementations were mainly used for stories based on statistics and numerical figures. Common topics include sports recaps32, weather, financial reports, real estate analysis, and earnings reviews.info:eu-repo/semantics/publishedVersio

    Estoque de carbono em Terra Preta do Índio no Município de Iranduba-AM.

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    O presente trabalho objetivou estimar o estoque de carbono até um metro de profundidade em uma área de TPI de aproximadamente seis hectares
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