6,181 research outputs found

    High Pressure optical nanothermometer based on Er3+ photoluminescence

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    The optical properties of a sparsely investigated material, LaGdO3 doped with Er3+, are explored regarding its suitability as nanothermometer. Besides its excellent capabilities for dielectric applications, when doping with Er3+, this material provides a highly efficient upconversion photoluminescence (PL) for high temperature thermometry at high pressure due to its structural stability. LaGdO3 belongs to the perovskite-type ABO3 compounds with a B-type monoclinic C2/m space group (a = 14.43 Å; b = 3.69 Å; c = 9.00 Å; and ? = 100.70º) at ambient conditions. It undergoes a structural phase transition to a hexagonal ?3#?1 phase at 3GPa yielding a notable PL enhancement, thus enabling it as a potential high-pressure hightemperature nanothermometer.We acknowledge financial support from MAT2015-69508-P (MINECO/FEDER), MAT2015-71070-REDC; PGC2018-101464-B-I00 (MICIN/FEDER), IDIVAL 18/28, the European Research Council FET-OPEN NCLas H2020 Project (EU829161), and BSH Electrodomésticos España, S.A

    Osteomielitis vertebral cervical como complicación de cirugía faríngea: a propósito de un caso

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    Se presenta un caso de un a enferma de 59 años, diabética, afecta de un a osteomielitis vertebral cervical por Candida Albicans. La vía de infección fué la persistencia durante varios meses de unos tutores, colocados tras la resección de un a estenosis nasofaríngea , que impactaban sobre la cara anterior de la vértebra C3. El desarrollo insidioso y la ausencia de un cuadro clínico específico fué la causa del retraso diagnóstico.A 5 9 yea r ol d woma n wit h diabete s mellitu s presente d a cervica l vertebra l osteomyelitis du e t o Candid a Albicans. Th e chroni c implantatio n o f dilatio n tube s followin g th e resectio n o f a nasopharyngea l stenosis wa s th e mod e o f infection . Th e insidiou s an d prolonge d onse t an d n o specifica l clinica l pictur e wer e t h e caus e o f dela y i n th e diagnosi

    Low-temperature specific heat of real crystals: Possibility of leading contribution of optical and short-wavelength acoustical vibrations

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    We point out that the repeatedly reported glass-like properties of crystalline materials are not necessarily associated with localized (or quasilocalized) excitations. In real crystals, optical and short-wavelength acoustical vibrations remain damped due to defects down to zero temperature. If such a damping is frequency-independent, e.g. due to planar defects or charged defects, these optical and short-wavelength acoustical vibrations yield a linear-in-TT contribution to the low-temperature specific heat of the crystal lattices. At low enough temperatures such a contribution will prevail over that of the long-wavelength acoustical vibrations (Debye contribution). The crossover between the linear and the Debye regime takes place at TNT^* \propto \sqrt N, where NN is the concentration of the defects responsible for the damping. Estimates show that this crossover could be observable.Comment: 5 pages. v4: Error in Appendix corrected, which does not change the main results of the pape

    Electroexcitation of the Roper resonance from CLAS data

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    The helicity amplitudes of the electroexcitation of the Roper resonance on proton are extracted at 1.7 < Q2 < 4.2 GeV2 from recent high precision JLab-CLAS cross sections data and longitudinally polarized beam asymmetry for pi+ electroproduction on protons. The analysis is made using two approaches, dispersion relations and unitary isobar model, which give consistent results. It is found that the transverse helicity amplitude for the gamma* p --> P11(1440) transition, which is large and negative at Q2=0, becomes large and positive at Q2 ~ 2 GeV2, and then drops slowly with Q2. Longitudinal helicity amplitude, that was previously found from CLAS data as large and positive at Q2=0.4,0.65 GeV2, drops with Q2. These results rule out the presentation of P11(1440) as a 3qG hybrid state, and provide strong evidence in favor of this resonance as a first radial excitation of the 3q ground state.Comment: 3 pages, 2 figures, Talk on the Workshop on "The Physics of Excited Nucleons", Bonn, Germany, October 200

    Generalized parton distributions in the deuteron

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    We introduce generalized quark and gluon distributions in the deuteron, which can be measured in exclusive processes like deeply virtual Compton scattering and meson electroproduction. We discuss the basic properties of these distributions, and point out how they probe the interplay of nucleon and parton degrees of freedom in the deuteron wave function

    From stone masonry to emigrant’s mansions. Changes in vernacular architecture in central Portugal

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    The research made for this purpose was realized to study the connection between the way of life, the climate, the geology and the vernacular architecture in the parish of Cernache do Bonjardim, municipality of Sertã, central region of Portugal, where various styles of rural houses can be found. The traditional rural home of this territory is constituted by stone walls, mostly made of shales or granite and has two floors: a lower floor with a place for animals or food storage, and an upper floor with the kitchen/living-room and bedrooms. Usually, both floors are joined by outside stairs. Each available space, for instance under these stairs, is used to keep animals like swine or hens, goats or rabbits, and to store food. Usually there is a piece of ground around the house used for the plantation of vegetables and fruit trees. This kind of home is adapted to the people's way of living and the climate, using local materials like stone or wood. In the 19th century there was an emigration wave to Brazil. When the people returned they wanted to show their acquired richness and (sometimes) culture to the neighbours in the village and constructed large houses of mansion-type, which didn't show the strong adaption to the environment anymore, but had other functionalities and a better comfort. As the transportation means improved, the building material was no more limited to the local offer. The emigration from the sixties of the 20th century until today brought new kinds of buildings. Their style was influenced from the country of emigration. There is no more relation to the local style of building. For the construction, modern materials like concrete, tile walls and roof tiles are used. The major conclusions of the research are that the vernacular architecture of the studied region has changed from houses adapted to the climate and the rural way of life, to larger and no more "typical" buildings. The main reasons for this change are the return of emigrants from abroad and its influence, the availability of new materials, the better education and income of the people, the wish to life more comfortably, and the change of the people´s way of life from farming to employment.info:eu-repo/semantics/publishedVersio

    The optical identifcation of events with poorly defined locations: The case of the Fermi GBM GRB140801A

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    We report the early discovery of the optical afterglow of gamma-ray burst (GRB) 140801A in the 137 deg2^2 3-σ\sigma error-box of the Fermi Gamma-ray Burst Monitor (GBM). MASTER is the only observatory that automatically react to all Fermi alerts. GRB 140801A is one of the few GRBs whose optical counterpart was discovered solely from its GBM localization. The optical afterglow of GRB 140801A was found by MASTER Global Robotic Net 53 sec after receiving the alert, making it the fastest optical detection of a GRB from a GBM error-box. Spectroscopy obtained with the 10.4-m Gran Telescopio Canarias and the 6-m BTA of SAO RAS reveals a redshift of z=1.32z=1.32. We performed optical and near-infrared photometry of GRB 140801A using different telescopes with apertures ranging from 0.4-m to 10.4-m. GRB 140801A is a typical burst in many ways. The rest-frame bolometric isotropic energy release and peak energy of the burst is Eiso=5.540.24+0.26×1052E_\mathrm{iso} = 5.54_{-0.24}^{+0.26} \times 10^{52} erg and Ep,rest280E_\mathrm{p, rest}\simeq280 keV, respectively, which is consistent with the Amati relation. The absence of a jet break in the optical light curve provides a lower limit on the half-opening angle of the jet θ=6.1\theta=6.1 deg. The observed EpeakE_\mathrm{peak} is consistent with the limit derived from the Ghirlanda relation. The joint Fermi GBM and Konus-Wind analysis shows that GRB 140801A could belong to the class of intermediate duration. The rapid detection of the optical counterpart of GRB 140801A is especially important regarding the upcoming experiments with large coordinate error-box areas.Comment: in press MNRAS, 201
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