1,206 research outputs found
Electrodynamics of quasi-two-dimensional BEDT-TTF charge transfer salts
We consider the millimeter-wave electrodynamics specific to
quasi-two-dimensional conductors and superconductors based on the organic donor
molecule BEDT-TTF. Using realistic physical parameters, we examine the current
polarizations that result for different oscillating (GHz) electric and magnetic
field polarizations. We show that, in general, it is possible to discriminate
between effects (dissipation and dispersion) due to in-plane and interlayer ac
currents. However, we also show that it is not possible to selectively probe
any single component of the in-plane conductivity tensor, and that excitation
of interlayer currents is strongly influenced by the sample geometry and the
electromagnetic field polarization.Comment: 5 pages including 3 figures Minor correction to figure
Complex Response Function of Magnetic Resonance Spectrometers
A vectorial analysis of magnetic resonance spectrometers, based on traveling
wave resonators and including the reference arm and the automatic control of
frequency, has been developed. The proposed model, valid also for stationary
wave resonators, gives the response function of the spectrometer for any
working condition, including scalar detectors with arbitrary response law and
arbitrary excitation frequency. The purely dispersive and purely absorptive
linear responses are discussed in detail for different scalar detectors. The
developed approach allows for optimizing the performances of the spectrometer
and for obtaining the intrinsic lineshape of the sample in a very broad range
of working conditions. More complex setups can be modeled following the
proposed scheme.Comment: PDF Acrobat 4.0 file, 15 pages, 2 figures, revised version with added
reference and corrected typo
Quantum melting of the quasi-two-dimensional vortex lattice in kappa-(ET)2Cu(NCS)2
We report torque magnetization measurements in regions of the mixed state
phase diagram ( and T/) of the organic
superconductor (ET)Cu(NCS) where quantum fluctuations are
expected to dominate thermal effects. Over most of the field range below the
irreversibility line (), magneto-thermal instabilities are
observed in the form of flux jumps. The abrupt cessation of these instabilities
just below indicates a quantum melting transition from a
quasi-two-dimensional vortex lattice phase to a quantum liquid phase.Comment: 8 pages (inc. Figs), accepted for publication in Phys. Rev. Let
Threshold-based Naïve Bayes classifier
The Threshold-based Naive Bayes (Tb-NB) classifier is introduced as a (simple) improved version of the original Naive Bayes classifier. Tb-NB extracts the sentiment from a Natural Language text corpus and allows the user not only to predict how much a sentence is positive (negative) but also to quantify a sentiment with a numeric value. It is based on the estimation of a single threshold value that concurs to define a decision rule that classifies a text into a positive (negative) opinion based on its content. One of the main advantage deriving from Tb-NB is the possibility to utilize its results as the input of post-hoc analysis aimed at observing how the quality associated to the different dimensions of a product or a service or, in a mirrored fashion, the different dimensions of customer satisfaction evolve in time or change with respect to different locations. The effectiveness of Tb-NB is evaluated analyzing data concerning the tourism industry and, specifically, hotel guests' reviews from all hotels located in the Sardinian region and available on Booking.com. Moreover, Tb-NB is compared with other popular classifiers used in sentiment analysis in terms of model accuracy, resistance to noise and computational efficiency
Squamous Cell Carcinoma and Ledderhose Disease: A Case Report
Ledderhose disease is disorder of the plantar aponeurosis. This disease is not so common and can be tackled with a surgical or conservative approach. A case of a 73-year-old man came to our attention who had a 26-year history of painless bilateral plantar nodules coalescing into an indurated mass. An ulcerative nodule had been noted in the last 16 months on the right foot, in the absence of trauma, not responsive to conservative treatment, so we decided to perform a biopsy. The histopatologic examination showed squamous cell carcinoma, with warty, well-differentiated, low-grade malignancy. Surgical treatment was suggested, so, in pneumoischemia, we made a surgical incision including the skin lesion. Then we proceeded to sculpture the anterolateral thigh fasciacutaneous flap to obtain adequate soft tissue coverage. The tumor was completely removed. Current reconstructive possibilities comprise a good anatomofunctional recovery even in the case of large demolition requests for the therapy of advanced cases of the disease described in this article. Correlation between Ledderhose disease and the formation of malignant tumors has not been made as yet, but perhaps an element that could unite these pathologies can be researched in the lively cell proliferation that characterizes both. It would be interesting to analyze the biological substrate, as well as the systemic and local levels, in patients where both diseases are manifested
Evidence for Anisotropic Vortex Dynamics and Pauli Limitation in the Upper Critical Field of FeSe1-xTex
We have determined HC2(T) for FeSe1-xTex (x=0.52) single crystals using
resistivity measurements at high static and pulsed magnetic field, as well as
specific heat measurements up to 9T. We find that the significant anisotropy of
the initial slope of HC2(T) determined from resistivity measurements, is not
present when HC2 is determined from the specific heat results. This suggests
that the thermodynamic upper critical field is almost isotropic, and that
anisotropic vortex dynamics play a role. Further evidence of anisotropic vortex
dynamics is found in the behaviour in pulsed field. We also find that Pauli
limiting must be included in order to fit the temperature dependence of HC2,
indicating probably higher effective mass in FeSe1-xTex than in other Fe
superconductors
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