35 research outputs found

    Nota sobre la composición mineralógica de unos piroxenos monoclínicos de Peñas de Haya (Guipúzcoa, Navarra)

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    Clinopyroxenes from Peñas de Haya (Guipúzcoa, Navarra) have been studied by X-ray single crystal diffraction. From chemical and crystal structure refinement it is shown that these pyroxenes are almost pure hedenbergite. The unitiell dimensions are: a = 9.867(3), b = 9.052(4), c = 5.253(0) A, p = 104.89(2)"

    Interface Motion and Pinning in Small World Networks

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    We show that the nonequilibrium dynamics of systems with many interacting elements located on a small-world network can be much slower than on regular networks. As an example, we study the phase ordering dynamics of the Ising model on a Watts-Strogatz network, after a quench in the ferromagnetic phase at zero temperature. In one and two dimensions, small-world features produce dynamically frozen configurations, disordered at large length scales, analogous of random field models. This picture differs from the common knowledge (supported by equilibrium results) that ferromagnetic short-cuts connections favor order and uniformity. We briefly discuss some implications of these results regarding the dynamics of social changes.Comment: 4 pages, 5 figures with minor corrections. To appear in Phys. Rev.

    Continuous Phase Measurement in the W7-X Infrared Interferometer by Means of a FPGA and High-Speed ADCs.

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    Interferometry is used for measuring line average electronic densities in fusion plasmas. The W7-X stellarator will employ a two-color CO2 (10.591 m) and CO (5.295 m) heterodyne-infrared interferometer as an electronic density measurement diagnostic. The frequency displacement is 40 MHz for the CO2 wavelength and 25 MHz for the CO, so these values will fix the heterodyne frequencies. Because the frequency gap between the two carriers is wide enough and the detector sensitivity is similar for both wavelengths, it is possible to use a single detector for the two signals; nevertheless, they should be split with filters. Traditionally, the intermediate-frequency signals should be filtered, downconverted to a lower frequency by the use of analog circuitry, and then processed. A new approach is proposed. The intermediate-frequency signals are directly sampled by means of high-speed analog-to-digital converters followed by a digital diplexer and a specific phase-meter processor implemented in a field-programmable gate array. Preliminary results from the W7-X infrared interferometer prototype, without plasma, are presented

    Experimental investigation of the temperatures and performance of a commercial ice-storage tank

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    [EN] This paper presents the results of an experimental installation with an internal melt-ice-on-coil tank which has a total capacity of 172 kWh. The aim of this work is to analyse the freezing process in a tank with counter-current spiral-shaped coils immersed in around 1855l water. An experimental campaign has been performed with different inlet temperatures and mass flow rates of the heat transfer fluid. This study analyses (i) the chiller performance, (ii) the ice-formation process and (iii) the energy consumption of the installation. Supply temperatures between 2.5 C and 5.2 C have been sufficient to charge the tank without using any nucleating agents. The lowest energy consumption has been achieved for the fastest charging tests.The authors gratefully acknowledge ACCIONA Infraestructuras for the financing support and collaboration. Parts of the experimental results used in this work were collected at Federico II University during the project "Layout d'impianto e metodi di controllo innovativi per la refrigerazione domestica, commerciale e professionale". A.W. Mauro acknowledges the financial support provided by Regione Campania.López-Navarro, A.; Biosca Taronger, J.; Torregrosa-Jaime, B.; Martínez Galván, IO.; Corberán, JM.; Esteban-Matías, JC.; Payá-Herrero, J. (2012). Experimental investigation of the temperatures and performance of a commercial ice-storage tank. International Journal of Refrigeration. 36(4):1310-1318. doi:10.1016/j.ijrefrig.2012.09.008S1310131836

    Bipolar supercurrent in graphene

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    Graphene -a recently discovered one-atom-thick layer of graphite- constitutes a new model system in condensed matter physics, because it is the first material in which charge carriers behave as massless chiral relativistic particles. The anomalous quantization of the Hall conductance, which is now understood theoretically, is one of the experimental signatures of the peculiar transport properties of relativistic electrons in graphene. Other unusual phenomena, like the finite conductivity of order 4e^2/h at the charge neutrality (or Dirac) point, have come as a surprise and remain to be explained. Here, we study the Josephson effect in graphene. Our experiments rely on mesoscopic superconducting junctions consisting of a graphene layer contacted by two closely spaced superconducting electrodes, where the charge density can be controlled by means of a gate electrode. We observe a supercurrent that, depending on the gate voltage, is carried by either electrons in the conduction band or by holes in the valence band. More importantly, we find that not only the normal state conductance of graphene is finite, but also a finite supercurrent can flow at zero charge density. Our observations shed light on the special role of time reversal symmetry in graphene and constitute the first demonstration of phase coherent electronic transport at the Dirac point.Comment: Under review, 12 pages, 4 Figs., suppl. info (v2 identical, resolved file problems

    Imported Human West Nile Virus Lineage 2 Infection in Spain: Neurological and Gastrointestinal Complications

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    We report the first human case of West Nile virus (WNV) lineage 2 infection imported to Spain by a traveler returning from Romania. Serum, cerebrospinal fluid and urine samples were analyzed and West Nile virus infection was identified by PCR and serological tests. The patient developed fever, diarrhea and neurological symptoms, accompanied by mild pancreatitis, described previously in very few cases as a complication of WNV infection and by alithiasic cholecystitis. Viral RNA was detected in urine until 30 days after the onset of symptoms and neutralizing antibodies were detected at very low titers. The phylogenetic analysis in a fragment of the NS5 gene of the virus showed a homology with sequences from WNV lineage 2 belonging to the monophyletic Central/Southern European group.This work was partially funded by the Instituto de Salud Carlos III Projects “PI14CIII/00014” and “PI19CIII_00014”.S

    Ge/Si nanowire mesoscopic Josephson junctions

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    The controlled growth of nanowires (NWs) with dimensions comparable to the Fermi wavelengths of the charge carriers allows fundamental investigations of quantum confinement phenomena. Here, we present studies of proximity-induced superconductivity in undoped Ge/Si core/shell NW heterostructures contacted by superconducting leads. By using a top gate electrode to modulate the carrier density in the NW, the critical supercurrent can be tuned from zero to greater than 100 nA. Furthermore, discrete sub-bands form in the NW due to confinement in the radial direction, which results in stepwise increases in the critical current as a function of gate voltage. Transport measurements on these superconductor-NW-superconductor devices reveal high-order (n = 25) resonant multiple Andreev reflections, indicating that the NW channel is smooth and the charge transport is highly coherent. The ability to create and control coherent superconducting ordered states in semiconductor-superconductor hybrid nanostructures allows for new opportunities in the study of fundamental low-dimensional superconductivity

    Heterozygous and Homozygous Variants in SORL1 Gene in Alzheimer's Disease Patients: Clinical, Neuroimaging and Neuropathological Findings

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    In the last few years, the SORL1 gene has been strongly implicated in the development of Alzheimer’s disease (AD). We performed whole-exome sequencing on 37 patients with early-onset dementia or family history suggestive of autosomal dominant dementia. Data analysis was based on a custom panel that included 46 genes related to AD and dementia. SORL1 variants were present in a high proportion of patients with candidate variants (15%, 3/20). We expand the clinical manifestations associated with the SORL1 gene by reporting detailed clinical and neuroimaging findings of six unrelated patients with AD and SORL1 mutations. We also present for the first time a patient with the homozygous truncating variant c.364C>T (p.R122*) in SORL1, who also had severe cerebral amyloid angiopathy. Furthermore, we report neuropathological findings and immunochemistry assays from one patient with the splicing variant c.4519+5G>A in the SORL1 gene, in which AD was confirmed by neuropathological examination. Our results highlight the heterogeneity of clinical presentation and familial dementia background of SORL1-associated AD and suggest that SORL1 might be contributing to AD development as a risk factor gene rather than as a major autosomal dominant gene.This work was supported by the Instituto de Salud Carlos III (PI17/01067) and AGAUR from the Autonomous Catalan Government (2017SGR1134). Dr. Víctor Antonio Blanco-Palmero is supported by the Instituto de Salud Carlos III (ISCIII, Spanish Biomedical Research Institute) through a “Río Hortega” contract (CM18/0095). Dr. Sara Llamas-Velasco is supported by the Instituto de Salud Carlos III (ISCIII; Spanish Biomedical Research Institute) through a “Juan Rodés” contract (JR 18/00046).S

    Occipital peripheral nerve stimulation in the management of chronic intractable occipital neuralgia in a patient with neurofibromatosis type 1: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Occipital peripheral nerve stimulation is an interventional pain management therapy that provides beneficial results in the treatment of refractory chronic occipital neuralgia. Herein we present a first-of-its-kind case study of a patient with neurofibromatosis type 1 and bilateral occipital neuralgia treated with occipital peripheral nerve stimulation.</p> <p>Case presentation</p> <p>A 42-year-old Caucasian woman presented with bilateral occipital neuralgia refractory to various conventional treatments, and she was referred for possible treatment with occipital peripheral nerve stimulation. She was found to be a suitable candidate for the procedure, and she underwent implantation of two octapolar stimulating leads and a rechargeable, programmable, implantable generator. The intensity, severity, and frequency of her symptoms resolved by more than 80%, but an infection developed at the implantation site two months after the procedure that required explantation and reimplantation of new stimulating leads three months later. To date she continues to experience symptom resolution of more than 60%.</p> <p>Conclusion</p> <p>These results demonstrate the significance of peripheral nerve stimulation in the management of refractory occipital neuralgias in patients with neurofibromatosis type 1 and the possible role of neurofibromata in the development of occipital neuralgia in these patients.</p

    Gypsum-rich horizons as seen in the field and under the microscope

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    1 Pag.Gypsum is a minor component of many soils throughout the world. However, mainly in dry countries, gypsum determines the appearance and behavior of some horizons.We propose refinements in the description of these horizons, linked with the interpretation of their constitution, behavior and genesis.Peer reviewe
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