7,098 research outputs found

    Tunneling into fractional quantum Hall liquids

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    Motivated by the recent experiment by Grayson et.al., we investigate a non-ohmic current-voltage characteristics for the tunneling into fractional quantum Hall liquids. We give a possible explanation for the experiment in terms of the chiral Tomonaga-Luttinger liquid theory. We study the interaction between the charge and neutral modes, and found that the leading order correction to the exponent α\alpha (I∼Vα)(I\sim V^\alpha) is of the order of ϵ\sqrt{\epsilon} (ϵ=vn/vc)(\epsilon=v_n/v_c), which reduces the exponent α\alpha. We suggest that it could explain the systematic discrepancy between the observed exponents and the exact α=1/ν\alpha =1/\nu dependence.Comment: Latex, 5 page

    Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings

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    In this work, we investigate the correlation between morphology, composition, and the mechanical properties of metallic amorphous tungsten-oxygen and amorphous tungsten-oxide films deposited by Pulsed Laser Deposition. This correlation is investigated by the combined use of Brillouin Spectroscopy and the substrate curvature method. The stiffness of the films is strongly affected by both the oxygen content and the mass density. The elastic moduli show a decreasing trend as the mass density decreases and the oxygen-tungsten ratio increases. A plateaux region is detected in correspondence of the transition between metallic and oxide films. The compressive residual stresses, moderate stiffness and high local ductility that characterize compact amorphous tungsten-oxide films make them promising for applications involving thermal or mechanical loads. The coefficient of thermal expansion is quite high (i.e. 8.9 ⋅\cdot 10−6^{-6} K−1^{-1}), being strictly correlated to the amorphous structure and stoichiometry of the films. Under thermal treatments they show a quite low relaxation temperature (i.e. 450 K). They crystallize into the γ\gamma monoclinic phase of WO3_3 starting from 670 K, inducing an increase by about 70\% of material stiffness.Comment: The research leading to these results has also received funding from the European Research Council Consolidator Grant ENSURE (ERC-2014-CoG No. 647554). The views and opinions expressed herein do not necessarily reflect those of the European Commissio

    Experimental measurement of photothermal effect in Fabry-Perot cavities

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    We report the experimental observation of the photothermal effect. The measurements are performed by modulating the laser power absorbed by the mirrors of two high-finesse Fabry-Perot cavities. The results are very well described by a recently proposed theoretical model [M. Cerdonio, L. Conti, A. Heidmann and M. Pinard, Phys. Rev. D 63 (2001) 082003], confirming the correctness of such calculations. Our observations and quantitative characterization of the photothermal effect demonstrate its critical importance for high sensitivity interferometric displacement measurements, as those necessary for gravitational wave detection.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let

    Multiple hydrodynamical shocks induced by Raman effect in photonic crystal fibres

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    We theoretically predict the occurrence of multiple hydrodynamical-like shock phenomena in the propagation of ultrashort intense pulses in a suitably engineered photonic crystal fiber. The shocks are due to the Raman effect, which acts as a nonlocal term favoring their generation in the focusing regime. It is shown that the problem is mapped to shock formation in the presence of a slope and a gravity-like potential. The signature of multiple shocks in XFROG signals is unveiled

    Fuzzy models for fingerprint description

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    Fuzzy models, traditionally used in the control field to model controllers or plants behavior, are used in this work to describe fingerprint images. The textures, in this case the directions of the fingerprint ridges, are described for the whole image by fuzzy if-then rules whose antecedents consider a part of the image and the consequent is the associated dominant texture. This low-level fuzzy model allows extracting higher-level information about the fingerprint, such as the existence of fuzzy singular points and their fuzzy position within the image. This is exploited in two applications: to provide comprehensive information for user of unattended automatic recognition systems and to extract linguistic patterns to classify fingerprints

    Prevalence of heavy smokers in the year 2000 in the province of Varese, Italy.

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    ABSTRACT: Prevalence of heavy smokers in the year 2000 in the Province of Varese, Italy. A. Imperatori, N. Rotolo, V. Conti, D. Di Natale, V. Tropeano, W. Mantovani. Background. Knowing the prevalence of heavy smokers (HS) by gender and age is a pre-requisite for bringing into effect public health measures against smoking-related diseases. Smoking prevalence data is available for the Italian Regions, however it is generally unknown for the Italian Provinces. Methods. In the year 2000 a survey of smoking prevalence was conducted by 47 general practitioners (GPs), by personal interview, in a large sample of the Varese Province population 45-74 years of age (28,034 subjects; 13,528 men, 14,506 women). Each surveyed subject was categorised either as ever HS (current/former smoker of at least 10 pack-years) or as non HS. The information on smoking habit collected by the GPs was anonymously pooled for analysis. Prevalence figures of smoking were tabulated by gender and by 5-year age-strata. Results. In the population 45-74 years of age the percentage of ever HS overall was 22.3% (34.4% of men; 11.0% of women). The prevalence of ever HS in both sexes combined progressively decreased with advancing age, from 23.6% (45-49 year stratum) to 19.5% (70-74 year stratum). Current HS were 24.5% of men and 9.5% of women. Conclusions. The year 2000 survey on smoking habit, showing 22.3% prevalence of ever HS in age range 45-74 years, is the first conducted in the Varese Province using a large population sample. The data on heavy cigarette smoking presented in this paper, stratified by gender and age, may be used to monitor changes in the smoking habit and in the incidence of smoking-related illnesses at the provincial level

    Improving the Sustainability of Dairy Slurry by A Commercial Additive Treatment

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    Ammonia (NH3), methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) emissions from livestock farms contribute to negative environmental impacts such as acidification and climate change. A significant part of these emissions is produced from the decomposition of slurry in livestock facilities, during storage and treatment phases. This research aimed at evaluating the eectiveness of the additive \u201cSOP LAGOON\u201d (made of agricultural gypsum processed with proprietary technology) on (i) NH3 and Greenhouse Gas (GHG) emissions, (ii) slurry properties and N loss. Moreover, the Life Cycle Assessment (LCA) method was applied to assess the potential environmental impact associated with stored slurry treated with the additive. Six barrels were filled with 65 L of cattle slurry, of which three were used as a control while the additive was used in the other three. The results indicated that the use of the additive led to a reduction of total nitrogen, nitrates, and GHG emissions. LCA confirmed the higher environmental sustainability of the scenario with the additive for some environmental impact categories among which climate change. In conclusion, the additive has beneficial eects on both emissions and the environment, and the nitrogen present in the treated slurry could partially displace a mineral fertilizer, which can be considered an environmental credit
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