10,382 research outputs found

    Reset and switch protocols at Landauer limit in a graphene buckled ribbon

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    Heat produced during a reset operation is meant to show a fundamental bound known as Landauer limit, while simple switch operations have an expected minimum amount of produced heat equal to zero. However, in both cases, present-day technology realizations dissipate far beyond these theoretical limits. In this paper we present a study based on molecular dynamics simulations, where reset and switch protocols are applied on a graphene buckled ribbon, employed here as a nano electromechanical switch working at the thermodynamic limit

    A Machine Learning-Based Approach for Audio Signals Classification using Chebychev Moments and Mel-Coefficients

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    This paper proposes a machine learning-based architecture for audio signals classification based on a joint exploitation of the Chebychev moments and the Mel-Frequency Cepstrum Coefficients. The procedure starts with the computation of the Mel-spectrogram of the recorded audio signals; then, Chebychev moments are obtained projecting the Cadence Frequency Diagram derived from the Mel-spectrogram into the base of Chebychev moments. These moments are then concatenated with the Mel-Frequency Cepstrum Coefficients to form the final feature vector. By doing so, the architecture exploits the peculiarities of the discrete Chebychev moments such as their symmetry characteristics. The effectiveness of the procedure is assessed on two challenging datasets, UrbanSound8K and ESC-50

    SiO collimated outflows driven by high-mass YSOs in G24.78+0.08

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    We imaged the molecular outflows towards the cluster of high-mass young stellar objects G24.78+0.08 at high-angular resolution using SiO emission, which is considered the classical tracer of protostellar jets. We performed SiO observations with the VLA interferometer in the J = 1-0 v=0 transition and with the SMA array in the 5-4 transition. A complementary IRAM 30-m single-dish survey in the (2-1), (3-2), (5-4), and (6-5) SiO lines was also carried out. Two collimated SiO high-velocity outflows driven by the A2 and C millimeter continuum massive cores have been imaged. On the other hand, we detected no SiO outflow driven by the young stellar objects in more evolved evolutionary phases that are associated with ultracompact (B) or hypercompact (A1) HII regions. The LVG analysis reveals high-density gas (10^3-10^4 cm-3), with well constrained SiO column densities (0.5-1 10^15 cm-2). The driving source of the A2 outflow is associated with typical hot core tracers such as methyl formate, vinyl cyanide, cyanoacetilene, and acetone. The driving source of the main SiO outflow in G24 has an estimated luminosity of a few 10^4 Lsun (typical of a late O-type star) and is embedded in the 1.3 mm continuum core A2, which in turn is located at the centre of a hot core that rotates on a plane perpendicular to the outflow main axis. The present SiO images support a scenario similar to the low-mass case for massive star formation, where jets that are clearly traced by SiO emission, create outflows of swept-up ambient gas usually traced by CO.Comment: Astronomy & Astrophysics, in pres

    Improving the energy performance of a 3D-printed wall using recycled material

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    In this paper, we present the results of a preliminary experimental campaign conducted on a 3D-printed wall 40 cm thick made of three concrete walls, connected by metal pins and concrete curbs to form three types of cavity - one rectangular and two triangular. The tests were performed in a climatic chamber at the Pietro Pisa Laboratory of the University of Brescia. The wall thermal performance has been evaluated by examining four scenarios in which the cavities have been filled with insulating material made of cellulose-based recycled flakes characterized by a declared thermal conductivity of 0.038 W/mK. The wall thermal transmittance U is measured based on the temperatures and heat fluxes measured through the structure. Based on the degree of filling, the wall thermal transmittance ranges between 1.58 W/m2K for the wall without insulation, and 0.28 W/m2K for the configuration with all cavities completely filled

    The phase diagram of L\'evy spin glasses

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    We study the L\'evy spin-glass model with the replica and the cavity method. In this model each spin interacts through a finite number of strong bonds and an infinite number of weak bonds. This hybrid behaviour of L\'evy spin glasses becomes transparent in our solution: the local field contains a part propagating along a backbone of strong bonds and a Gaussian noise term due to weak bonds. Our method allows to determine the complete replica symmetric phase diagram, the replica symmetry breaking line and the entropy. The results are compared with simulations and previous calculations using a Gaussian ansatz for the distribution of fields.Comment: 20 pages, 7 figure

    Forensic Diagnosis of Freshwater or Saltwater Drowning Using the Marker Aquaporin 5: An Immunohistochemical Study

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    Background and Objectives: Aquaporins are a family of water channel proteins. In this study, the renal and intrapulmonary expression of aquaporin-5 (AQP5) was examined in forensic autopsy cases to evaluate it as a drowning marker and to differentiate between freshwater drowning and saltwater drowning. Materials and Methods: Cases were classified into three groups: freshwater drowning (FWD), saltwater drowning (SWD), and controls (CTR). Samples were obtained from forensic autopsies at less than 72 h postmortem (15 FWD cases, 15 SWD cases, and 17 other cases) and were subjected to histological and immunohistochemical investigations. Results: In FWD group, intrapulmonary AQP5 expression was significantly suppressed compared with SWD and CTR; there was no significant difference in AQP5 expression among the other two groups. The same differences in expression were also observed in the kidney. Conclusions: These observations suggest that AQP5 expression in alveolar cells was suppressed by hypotonic water to prevent hemodilution. Moreover, it is possible to hypothesize that in the kidney, with the appearance of hypo-osmotic plasma, AQP5 is hypo-expressed, as a vital reaction, to regulate the renal reabsorption of water. In conclusion, the analysis of renal and intrapulmonary AQP5 expression would be forensically useful for differentiation between FWD and SWD, or between FWD and death due to other causes

    Spectra of sparse non-Hermitian random matrices: an analytical solution

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    We present the exact analytical expression for the spectrum of a sparse non-Hermitian random matrix ensemble, generalizing two classical results in random-matrix theory: this analytical expression forms a non-Hermitian version of the Kesten-Mckay law as well as a sparse realization of Girko's elliptic law. Our exact result opens new perspectives in the study of several physical problems modelled on sparse random graphs. In this context, we show analytically that the convergence rate of a transport process on a very sparse graph depends upon the degree of symmetry of the edges in a non-monotonous way.Comment: 5 pages, 5 figures, 12 pages supplemental materia

    Validation of the italian version of the behavioral inhibition questionnaire (Biq) for preschool children

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    Behavioral Inhibition (BI) is a temperamental trait characterized by fear and wariness in reaction to new and unfamiliar stimuli, both social and non-social. BI has been recognized as possible forerunner of anxiety disorders, especially social anxiety and phobia; therefore, its assessment is clinically relevant. The present study aimed to examine the psychometric properties of the Italian adaptation of the Behavioral Inhibition Questionnaire (BIQ), which measures BI in preschool children. The BIQ was completed by 417 Italian parents (230 mothers, 187 fathers) of 270 preschoolers aged 3–5. Confirmatory factor analysis showed a good internal validity: the factorial structure was corresponding to the original six-factor version. Results showed excellent internal consistency, significant item-total correlations, good inter-rater reliability, convergent validity (by correlating the BIQ with the Italian Questionnaires of Temperament-QUIT, the Anxiety-Shy Conner’s Scale and the Laboratory Temperament Assessment Battery) and discriminant validity (i.e., no correlation with Conners’ ADHD scale). Significant correlations emerged between BI indexes and total BIQ scores of parents and maternal (but not paternal) versions of the questionnaire. Altogether, the results are promising and consistent with previous validation studies, suggesting the BIQ as a reliable and valid measure for evaluating parents’ perception of BI in Italian preschoolers

    ALMA reveals the feeding of the Seyfert 1 nucleus in NGC 1566

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    We report ALMA observations of CO(3-2) emission in the Seyfert 1 galaxy NGC 1566, at a spatial resolution of 25 pc. Our aim is to investigate the morphology and dynamics of the gas inside the central kpc, and to probe nuclear fueling and feedback phenomena. NGC 1566 has a nuclear bar of 1.7 kpc radius and a conspicuous grand design spiral starting from this radius. The ALMA field of view, of diameter 0.9 kpc, lies well inside the nuclear bar and reveals a molecular trailing spiral structure from 50 to 300~pc in size, which is contributing to fuel the nucleus, according to its negative gravity torques. The spiral starts with a large pitch angle from the center and then winds up in a pseudo-ring at the inner Lindblad resonance (ILR) of the nuclear bar. This is the first time that a trailing spiral structure is clearly seen driving the gas inwards inside the ILR ring of the nuclear bar. This phenomenon shows that the massive central black hole has a significant dynamical influence on the gas, triggering its fueling. The gaseous spiral is well correlated with the dusty spiral seen through extinction in HST images, and also with a spiral feature emitting 0.87mm continuum. This continuum emission must come essentially from cold dust heated by the interstellar radiation field. The HCN(4-3) and HCO+(4-3) lines were simultaneously mapped and detected in the nuclear spiral. The HCO+(4-3) line is 3 times stronger than the HCN(4-3), as expected when star formation excitation dominates over active galactic nucleus (AGN) heating. The CO(3-2)/HCO+(4-3) integrated intensity ratio is \sim 100. The molecular gas is in remarkably regular rotation, with only slight non-circular motions at the periphery of the nuclear spiral arms. These perturbations are quite small, and no outflow nor AGN feedback is detected.Comment: 11 pages, 16 figures, accepted in Astronomy and Astrophysic
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