5,425 research outputs found

    Total electron scattering cross sections from thiophene for the (1-300 eV) impact energy range

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    Experimental electron scattering cross sections for thiophene in the impact energy range from 1 to 300 eV have been measured with a magnetically confined electron transmission-beam apparatus. Random uncertainty limits have been estimated to be less than 5%, and systematic errors derived from acceptance angle limitations have also been identified and evaluated. Experimental values are compared with our previous low energy (1-15 eV) R-matrix and intermediate/high energy (15-300 eV) IAM-SCAR+I calculations finding reasonable agreement, within the combined uncertainty limits. Some of the low energy shape and core-excited resonances predicted by previous calculations are experimentally confirmed in this study

    Rashba coupling in quantum dots: exact solution

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    We present an analytic solution to the problem of the Rashba spin-orbit coupling in semiconductor quantum dots. We calculate the exact energy spectrum, wave-functions, and spin--flip relaxation times. We discuss various effects inaccessible via perturbation theory. In particular, we find that the effective gyromagnetic ratio is strongly suppressed by the spin-orbit coupling. The spin-flip relaxation rate has a maximum as a function of the spin-orbit coupling and is therefore suppressed in both the weak- and strong coupling limits.Comment: 5 pages, 4 figs, reference adde

    Full-field swept-source optical coherence tomography and neural tissue classification for deep brain imaging

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    Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a realtime neurosurgical guidance tool. We present, to our knowledge, the first full-field swept-source optical coherence tomography system operating near a wavelength of 1310 nm. The proof-of-concept system was integrated with an endoscopic probe tip, that is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified into three brain tissue types

    First investigation of a novel 2D position-sensitive semiconductor detector concept

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    This paper presents a first study of the performance of a novel 2D position-sensitive microstrip detector, where the resistive charge division method was implemented by replacing the metallic electrodes with resistive electrodes made of polycrystalline silicon. A characterization of two proof-of-concept prototypes with different values of the electrode resistivity was carried out using a pulsed Near Infra-Red laser. The experimental data were compared with the electrical simulation of the sensor equivalent circuit coupled to simple electronics readout circuits. The good agreement between experimental and simulation results establishes the soundness of resistive charge division method in silicon microstrip sensors and validates the developed simulation as a tool for the optimization of future sensor prototypes. Spatial resolution in the strip length direction depends on the ionizing event position. The average value obtained from the protype analysis is close to 1.2% of the strip length for a 6 MIP signal.Comment: 14 pages, 12 figure

    Functional and molecular characterization of inherited platelet disorders in the Iberian Peninsula: results from a collaborative study

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    BACKGROUND: The diagnostic evaluation of inherited platelet disorders (IPDs) is complicated and time-consuming, resulting in a relevant number of undiagnosed and incorrectly classified patients. In order to evaluate the spectrum of IPDs in individuals with clinical suspicion of these disorders, and to provide a diagnostic tool to centers not having access to specific platelets studies, we established the project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" under the scientific sponsorship of the Spanish Society of Thrombosis and Haemostasis. PATIENTS/METHODS: Subjects were patients from a prospective cohort of individuals referred for clinical suspicion of IPDs as well as healthy controls. Functional studies included light transmission aggregation, flow cytometry, and when indicated, Western-blot analysis of platelet glycoproteins, and clot retraction analysis. Genetic analysis was mainly performed by sequencing of coding regions and proximal regulatory regions of the genes of interest. RESULTS: Of the 70 cases referred for study, we functionally and molecularly characterized 12 patients with Glanzmann Thrombasthenia, 8 patients with Bernard Soulier syndrome, and 8 with other forms of IPDs. Twelve novel mutations were identified among these patients. The systematic study of patients revealed that almost one-third of patients had been previously misdiagnosed. CONCLUSIONS: Our study provides a global picture of the current limitations and access to the diagnosis of IPDs, identifies and confirms new genetic variants that cause these disorders, and emphasizes the need of creating reference centers that can help health care providers in the recognition of these defects

    Degradación física de los suelos del sector comprendido entre la Sierra de las Guájara y el río Albuñuelas

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    The authors have carried out an study on potential physical degradation phenomena of tipical soils belonging to the sector between Sierra of Guájaras and the Albuñuelas river. Provisonal methodology for soil degradation evaluation F.A.O. (1980) was used, expressing the results as a porcentage of permeability reduction.Se realiza un estudio de los fenónemos de degradación física potencial que pueden sufrir los suelos modales del sector comprendido entre la Sierra de las Guájaras y el río Albuñuelas. Se emplea la Metodología provisional para la evaluación de la degradación de suelos de la F.A.O. (1980), expresando los resultados obtenidos en tanto por ciento de reducción de la permeabilidad

    Degradación física de los suelos del sector comprendido entre la Sierra de las Guájara y el río Albuñuelas

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    Se realiza un estudio de los fenónemos de degradación física potencial que pueden sufrir los suelos modales del sector comprendido entre la Sierra de las Guájaras y el río Albuñuelas. Se emplea la Metodología provisional para la evaluación de la degradación de suelos de la F.A.O. (1980), expresando los resultados obtenidos en tanto por ciento de reducción de la permeabilidad.The authors have carried out an study on potential physical degradation phenomena of tipical soils belonging to the sector between Sierra of Guájaras and the Albuñuelas river. Provisonal methodology for soil degradation evaluation F.A.O. (1980) was used, expressing the results as a porcentage of permeability reduction

    Non-perturbative effects in semi-leptonic B_c decays

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    We discuss the impact of the soft degrees of freedom inside the B_c meson on its rate in the semi-leptonic decay B_c -> X l nu_l where X denotes light hadrons below the D^0 threshold. In particular we identify contributions involving soft hadrons which are non-vanishing in the limit of massless leptons. These contributions become relevant for a measurement of the purely leptonic B_c decay rate, which due to helicity suppression involves a factor m_l^2 and thus is much smaller than the contributions involving soft hadrons.Comment: LaTeX, 22 pages, 1 figur

    Authentication of tequilas using pattern recognition and supervised classification

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    [Abstract] Sales of reputed, Mexican tequila grown substantially in last years and, therefore, counterfeiting is increasing steadily. Hence, methodologies intended to characterize and authenticate commercial beverages are a real need. They require a combination of analytical characterization and chemometric tools. This work reports concisely on the former and focus on the chemometric tools employed so far in connection with them. Further, a practical case study presents the classification capabilities of nine supervised classification methods to differentiate white, rested, aged and extra-aged tequilas. The largest set of certified tequilas employed so far was considered. In general, non linear methods performed best than linear ones (accuracy higher than 94% in both training and validation). The case study demonstrates that it is possible to develop fast, cheap, easy to implement and reliable analytical methodologies to authenticate and classify samples of tequilas.Xunta de Galicia; GRC2013-047Ministerio de Industria, Energía y Competitividad; FJCI-2015-2607
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