240 research outputs found

    Longitudinal profiles of Extensive Air Showers with inclusion of charm and bottom particles

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    Charm and bottom particles are rare in Extensive Air Showers but the effect of its presence can be radical in the development of the Extensive Air Showers (EAS). If such particles arise with a large fraction of the primary energy, they can reach large atmospheric depths, depositing its energy in deeper layers of the atmosphere. As a consequence, the EAS observables (XmaxX_{max}, RMSRMS and NmaxN_{max}) will be modified, as well as the shape of the longitudinal profile of the energy deposited in the atmosphere. In this paper, we will modify the CORSIKA Monte Carlo by the inclusion of charm and bottom production in the first interaction of the primary cosmic ray. Results for different selections of the typical xFx_F values of the heavy particles and distinct production models will be presented.Comment: Replacement of tex file by the correct versio

    Saturation Physics in Ultra High Energy Cosmic Rays: Heavy Quark Production

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    In this work we estimate the heavy quark production in the interaction of ultra high energy cosmic rays in the atmosphere, considering that the primary cosmic ray is a proton or a photon. At these energies the saturation momentum Q_{sat}^2 stays above the hard scale \mu_c^2=4m_c^2, implying charm production probing the saturation regime. In particular, we show that the ep HERA data presents a scaling on \tau_c = (Q^2+\mu_c^2)/Q_{sat}^2. We derive our results considering the dipole picture and the Color Glass Condensate formalism, which one shows to be able to describe the heavy quark production in photon-proton and proton-proton collisions. Nuclear effects are considered in computation of cross sections for scattering on air nuclei. Implications on the flux of prompt leptons at the earth are analyzed and a large suppression is predicted.Comment: 18 pages, 10 figures, 2 tables. Version to be published in JHE

    Searches for axion-like particles via γγ\gamma \gamma fusion at future e+e\mathrm{e}^+\mathrm{e}^- colliders

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    Opportunities for searches for axion-like particles (ALPs) coupling to photons in e+e\mathrm{e}^+\mathrm{e}^- collisions at the Future Circular Collider (FCC-ee) and International Linear Collider (ILC) are investigated. We perform a study of the photon-fusion production of ALPs decaying into two photons, e+eγγe+  a(γγ)  e\mathrm{e}^+\mathrm{e}^- \overset{\gamma \gamma}{\longrightarrow} \mathrm{e}^{+}\;a(\gamma \gamma)\;\mathrm{e}^{-}, over the light-by-light continuum background, for the planned FCC-ee and ILC center-of-mass energies and integrated luminosities. An analysis of the feasibility measurements is presented using parametrized simulations for two types of detectors. Upper limits at 95% confidence level (CL) on the cross section for ALP production, σ(γγaγγ)\sigma(\gamma \gamma \to a \to \gamma \gamma), and on the ALP-photon coupling are obtained over the ma0.1m_a \approx 0.1--1000 GeV ALP mass range, and compared to current and future collider searches. Production cross sections down to σ(γγaγγ)1\sigma(\gamma \gamma \to a \to \gamma \gamma) \approx 1 fb (1 ab) will be probed at ma1m_a\approx 1 (300) GeV, corresponding to constraints on the axion-photon coupling as low as gaγγ2103g_\mathrm{a\gamma \gamma} \approx 2\cdot10^{-3} TeV1^{-1}

    Spent grain as a new carrier for trypsin immobilisation

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    Trypsin is a widely used enzyme for protein hydrolysis and can be used to improve functional and nutritional properties of foods. This work compares different carriers obtained from spent grains as potential candidates for trypsin immobilisation. Covalent attachment to the carriers was tested using glutaraldehyde. The efficiency of immobilisation and activity, operation and storage stability of free and immobilised enzyme on supports were determined. The amount of immobilised protein achieved was high (up to 70 %) but there was a significant loss of enzyme activity with the immobilisation of trypsin. However, when a more purified enzyme from bovine pancreas was used, activity retention was almost 50 %. Trypsin was most successfully immobilised on the supports by covalent attachment using glyoxyl-derivatives. The stability of these immobilized enzymes was close to 100%.This work was co-financed by Social European Fund (public call 1/5.3/PRODEP/2003, financial application 1012.012, of measure 5/action 5.3 – Post-graduate training for academic staff submitted by Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Viana do Castelo).info:eu-repo/semantics/publishedVersio

    Shine on you crazy diamond: Symbolism and social use of fluorite ornaments in Iberia’s late prehistory

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    Fluorite ornaments have been recorded in different sites of Europe since Upper Paleolithic. Due to its visual appearance and physical properties, some translucent or transparent mineralogies like fluorite were searched for or casually acquired by late prehistory’s human communities. After intensive research on archaeological contexts from the Iberian Peninsula with personal ornaments from 4th to 2nd millennia BCE, we have recently identified and characterized for the first time an important number of fluorite ornaments, confronting a previous background where little attention was paid. Our work has been carried out in different archaeological collections and museums from the whole Iberian Peninsula by non-destructive techniques (Raman spectroscopy, portable X-ray fluorescence (p-XRF) and X-ray Diffraction (XRD), that revealed the nature of fluorite ornaments and points to its consideration as scarce and highly symbolic items during late prehistory. A total of 36 fluorite beads from 23 sites are here recorded and studied, many of them unpublished or wrong catalogued as other mineralogies. These adornments could have important roles in trade and use among the communities of Iberia from the 4th millennium BCE onwards, because of their scarcity and its recurrent association with important funerary complex and exotic materials. Fluorite ornaments could have been significant and special symbols in the development of new and exclusive raw materials in the context of increasing social complexity and inequality

    Distribución y consumo de cuentas de fluorita y translúcidas en la península ibérica del VI al II milenios ANE

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    Translucent minerals were valued in prehistoric societies for their rarity and socially used as highly symbolic elements. This work addresses the use and nature of Iberian translucent beads. We present the results of chemical (Raman spectroscopy, portable X-ray fluorescence, X-ray diffraction and visible (Vis)/near-infrared (NIR) spectroscopy) and contextual analyses and provide a review of the archaeological literature on the manufacture and use of translucent items during Iberian Late Prehistory. A total of 54 translucent beads from 47 sites, primarily burials, were analyzed; 33 were made from fluorite, while the remaining 21 were made of diverse translucent minerals (calcite, quartz and different silicates). The scarcity of translucent items in the archaeological record, the regional and supraregional scale of its exchange, and its recursive association to other valuables in singular contexts reinforces the idea that their owners/wearers enjoyed a high status.info:eu-repo/semantics/publishedVersio

    Avaliação de ferramentas na furação de laminados compósitos

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    Drilling of polymeric matrix composite structuresThe development of cutting tools becomes a challenge to the industry of composite materials to obtain high quality holes, minimizing damage. This work aims to examine the influence of various parameters such as feed rate and tool geometry on thrust forces developed during drilling operations and on the extent of damage. In this work, a comparative study of tool geometry with the aim of reducing the associated damage during drilling process is presented. In the end a good combination of tool geometry and drilling parameters based on experimental work will be presented.O desenvolvimento de ferramentas de corte torna-se um desafio à indústria de materiais compósitos, na obtenção de furos de elevada qualidade, minimizando o dano. Este trabalho visa analisar a influência de vários parâmetros, tais como o avanço e a geometria de ferramenta, nas forças desenvolvidas durante a furação e na extensão do dano. Neste artigo é apresentado um estudo comparativo de geometrias de broca com o objectivo de reduzir o dano associado à furação, que permitirá determinar qual a melhor selecção de parâmetros de furação, atendendo às diferentes geometrias de ferramenta

    Interpretation of gravity data to delineate structural features connected to low-temperature geothermal resources at Northeastern Portugal

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    A great number of low-temperature geothermal fields occur in Northern-Portugal related to fractured rocks. The most important superficial manifestations of these hydrothermal systems appear in pull-apart tectonic basins and are strongly conditioned by the orientation of the main fault systems in the region. This work presents the interpretation of gravity gradient maps and 3D inversion model produced from a regional gravity survey. The horizontal gradients reveal a complex fault system. The obtained 3D model of density contrast puts into evidence the main fault zone in the region and the depth distribution of the granitic bodies. Their relationship with the hydrothermal systems supports the conceptual models elaborated from hydrochemical and isotopic water analyses. This work emphasizes the importance of the role of the gravity method and analysis to better understand the connection between hydrothermal systems and the fractured rock pattern and surrounding geology. (c) 2013 Elsevier B.V. All rights reserved
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