1,036 research outputs found

    Shubnikov-de Haas oscillations spectrum of the strongly correlated quasi-2D organic metal (ET)8[Hg4Cl12(C6H5Br)]2 under pressure

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    Pressure dependence of the Shubnikov-de Haas (SdH) oscillations spectra of the quasi-two di- mensional organic metal (ET)8[Hg4Cl12(C6H5Br)]2 have been studied up to 1.1 GPa in pulsed magnetic fields of up to 54 T. According to band structure calculations, its Fermi surface can be regarded as a network of compensated orbits. The SdH spectra exhibit many Fourier components typical of such a network, most of them being forbidden in the framework of the semiclassical model. Their amplitude remains large in all the pressure range studied which likely rules out chemical potential oscillation as a dominant contribution to their origin, in agreement with recent calculations relevant to compensated Fermi liquids. In addition to a strong decrease of the magnetic breakdown field and effective masses, the latter being likely due to a reduction of the strength of electron correlations, a sizeable increase of the scattering rate is observed as the applied pressure increases. This latter point, which is at variance with data of most charge transfer salts is discussed in connection with pressure-induced features of the temperature dependence of the zero-field interlayer resistanceComment: Eur. Phys. J. B, in pres

    Continuing high levels of HIV diagnoses in men who have sex with men in the United Kingdom.

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    Pressure dependence of the Shubnikov-de Haas oscillation pectrum of beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)3].DMF

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    The Shubnikov-de Haas (SdH) oscillation spectra of the beta''-(BEDT-TTF)4(NH4)[Cr(C2O4)\_3].DMF organic metal have been studied in pulsed magnetic fields of up to either 36 T at ambient pressure or 50 T under hydrostatic pressures of up to 1 GPa. The ambient pressure SdH oscillation spectra can be accounted for by up to six fundamental frequencies which points to a rather complex Fermi surface (FS). A noticeable pressure-induced modification of the FS topology is evidenced since the number of frequencies observed in the spectra progressively decreases as the pressure increases. Above 0.8 GPa, only three compensated orbits are observed, as it is the case for several other isostructural salts of the same family at ambient pressure. Contrary to other organic metals, of which the FS can be regarded as a network of orbits, no frequency combinations are observed for the studied salt, likely due to high magnetic breakdown gap values or (and) high disorder level evidenced by Dingle temperatures as large as about 7 K.Comment: To be published in European Physical Journal

    The BMV project: Search for photon oscillations into massive particles

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    In this contribution to PSAS08 we report on the research activities developed in our Toulouse group, in the framework of the BMV project, concerning the search for photon oscillations into massive particles, such as axion-like particles in the presence of a strong transverse magnetic field. We recall our main result obtained in collaboration with LULI at \'Ecole Polytechnique (Palaiseau, France). We also present the very preliminary results obtained with the BMV experiment which is set up at LNCMP (Toulouse, France).Comment: Proceedings of PSAS'08, to be published in Can. J. Phy

    Validation of the italian translation of the affective neuroscience personality scales

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    Summary.-The theoretical perspective on affective neuroscience advanced by Panksepp, identified six basic innate affective systems: the SEEK, FEAR, ANGER, SADNESS, PLAY, and CARE systems. (3) It has been proposed that the fundamental elements of human personality and its variants may be based on the different expressions of these basic emotional systems and their combinations. A self-report inventory, the Affective Neuroscience Personality Scales (ANPS), has been devised with the aim of studying and evaluating personality from this perspective. This study reports data on the initial validation of ANPS Italian translation on a sample of 418 adult participants. Descriptive statistics for each scale were calculated, assessing also their internal consistency, as a measure of reliability and factorial validity. Acceptable internal consistency was found in all but one scale (SADNESS), and a second-order factor analysis identified a more general affective feature of personality hinging on relational characteristics, independent of the dimensions of general positive and negative affect

    Measurement of sea waves

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    Sea waves constitute a natural phenomenon with a great impact on human activities, and their monitoring is essential for meteorology, coastal safety, navigation, and renewable energy from the sea. Therefore, the main measurement techniques for their monitoring are here reviewed, including buoys, satellite observation, coastal radars, shipboard observation, and microseism analysis. For each technique, the measurement principle is briefly recalled, the degree of development is outlined, and trends are prospected. The complementarity of such techniques is also highlighted, and the need for further integration in local and global networks is stressed

    de Haas-van Alphen oscillations in the underdoped cuprate YBa2_2Cu3_3O6.5_{6.5}

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    The de Haas-van Alphen effect was observed in the underdoped cuprate YBa2_2Cu3_3O6.5_{6.5} via a torque technique in pulsed magnetic fields up to 59 T. Above an irreversibility field of ∌\sim30 T, the magnetization exhibits clear quantum oscillations with a single frequency of 540 T and a cyclotron mass of 1.76 times the free electron mass, in excellent agreement with previously observed Shubnikov-de Haas oscillations. The oscillations obey the standard Lifshitz-Kosevich formula of Fermi-liquid theory. This thermodynamic observation of quantum oscillations confirms the existence of a well-defined, close and coherent, Fermi surface in the pseudogap phase of cuprates.Comment: published versio
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