39 research outputs found

    On the Characterization of Wind Profiles Generated by Road Traffic

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    Diabetes and metabolic disorders. Their impact on cardiovascular events in liver transplant patients

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    Cardiovascular diseases are currently one of the most important causes of morbidity and mortality in liver transplant patients over the long term. Therefore, evaluating prognostic factors for cardiovascular events (CVEs) in this population is essential for taking preventive measures. The aim of this study was to identify the impact of diabetes and other metabolic disorders on CVEs in liver transplant patients. Three hundred fifty-six liver transplant recipients who survived at least 6 months after surgery were enrolled. Patients were followed for a median time of 118 months (12–250 months). All cardiovascular events were carefully recorded and detailed in the patients’ charts. Demographic data, diabetes, hypertension, dyslipidemia, weight changes, and a diagnosis of metabolic syndrome both before and after transplantation were noted to assess their possible relationship with CVE. The presence of a diagnosis of metabolic-associated fatty liver disease (MAFLD) was also evaluated. Immunosuppressive therapy was included in the analysis. Diabetes mellitus (DM), especially when present before transplantation, was strongly associated with CVEs (hazard risk HR 3.10; 95% confidence interval CI: 1.60–6.03). Metabolic syndrome was found to be associated with CVEs in univariate analysis (HR 3.24; 95% CI: 1.36–7.8), while pretransplantation and de novo MAFLD were not. Immunosuppressive therapy had no influence on predisposing transplanted patients to CVEs during follow-up. Further prospective studies may be useful in investigating the risk factors for CVEs after liver transplantation and improving the long-term survival of transplant patients

    Radio frequency over fiber technology for SKA-low receiver

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    The signal reception chain is an essential element for achieving the square kilometer array-low (SKA-low) system requirements in terms of high sensitivity and dynamic range. The balance between gain, linearity, and low power consumption, as well as the cost, are fundamental parameters that influence the selection of the most suitable technology for SKA-low. Further factors, such as low self-generated radio frequency (RF) interference, high reliability, robustness under extreme environment, and last but not least, the distance between the antennas and the acquisition systems, have impacts on the selection for both architecture and receiver system design. The selected technology for the SKA-low RF signal transportation is RF-over-fiber systems, where the preamplified RF signal picked up by the antennas is carried via analogue modulation over optical fiber. The rationales behind the selection are reported, along with descriptions on the development of the receiver prototypes. The prototypes were deployed and installed on the demonstrator arrays at the selected SKA-low site in Western Australian. Particular attention has been put on the thermal characterization of the receiver system under the actual operating temperature on site, especially when both transmitting part and the optical medium are subjected to external ambient temperature variations. Performance issues encountered in the demonstrator arrays are also discussed along with some proposals for future activities

    Numerical Prediction And Experimental Validation Of Rotor Thermal Instability

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    LectureThe increasing demand of higher efficiency and increased equipment compactness is pushing the modern rotordynamic design towards higher and higher bearing peripheral speeds. Due to the increased viscous dissipation, fluid film bearings are prone to the development of rotor asymmetrical heating (de Jongh 1994) and hence thermal rotor bowing, rotor thermal imbalance and consequent synchronous vibration increase. Differential heating and synchronous rotor vibrations are directly linked leading to a complex feedback loop which can cause thermal rotor instability often referred as Morton effect (de Jongh 1994). In the present work, the stability of a rotor bearing system is numerically simulated following two different approaches: a classical linear stability approach suggested by Murphy et al. (Murphy 2009) and an iterative FEM thermo-structural-dynamic analysis. Results are compared with measurements obtained during an experimental campaign carried out at the GE oil & Gas facility in Florence on a real scale between-bearing dummy rotor. During the experiments, the rotor differential temperature at the journal bearing section has been continuously monitored via telemetry as well as rotor vibration at bearing, mid span and overhung location. For the linear stability approach, the rotor differential temperature is estimated by making use of a steady thin-film tilting pad journal bearing (TPJB) code developed at the Department of Industrial Engineering of the University of Florence while the iterative method takes advantage of an experimentally fit correlation between rotor vibration and differential rotor temperature used to couple the dynamic and thermo-structural rotor simulations

    Biexciton initialization by two-photon excitation in site-controlled quantum dots: the complexity of the antibinding state case

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    In this work, we present a biexciton state population in (111)B oriented site-controlled InGaAs quantum dots (QDs) by resonant two photon excitation. We show that the excited state recombines emitting highly pure single photon pairs entangled in polarization. The discussed cases herein are compelling due to the specific energetic structure of pyramidal InGaAs QDs—an antibinding biexciton—a state with a positive binding energy. We demonstrate that resonant two-photon excitation of QDs with antibinding biexcitons can lead to a complex excitation-recombination scenario. We systematically observed that the resonant biexciton state population is competing with an acoustic-phonon assisted population of an exciton state. These findings show that under typical two-photon resonant excitation conditions, deterministic biexciton state initialization can be compromised. This complication should be taken into account by the community members aiming to utilize similar epitaxial QDs with an antibinding biexciton

    Preliminary tests to design an ad hoc signal acquisition chain for the Sardinia Aperture Array Demonstrator

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    The Sardinia Aperture Array Demonstrator (SAD) is an Italian facility, which is composed of 128 prototypical Vivaldi antennas, specifically designed to operate across the 50-500 MHz frequency range. As well known, one of the major burden at low frequency are the radio frequency interferences, thus after several accurate measurement campaigns we realized that a specific signal conditioning is needed in order to feed the digital beamformer with the proper signal level. In this paper, we report the results of the preliminary tests that we carried out in order to design an ad hoc receiving chain for the SAD array

    Procedura di montaggio del sistema di movimentazione e controllo del ramo N/S per il sistema BIRALES

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    Lo scopo di questo documento è quello di descrivere la procedura dell’installazione del nuovo sistema di movimentazione delle antenne cilindrico paraboliche del ramo Nord/Sud del radiotelescopio “Croce del Nord”, studiato per venire incontro alle esigenze del programma “Space Surveillance and Tracking”, oltre a programmi scientifici quale la ricerca degli FRB. Oltre alla procedura di installazione, è indicata la lista del materiale necessario alla replicazione e i disegni costruttivi, e viene inoltre descritta la procedura di manutenzione

    I Lavori Pubblici nello “Istituto Nazionale di Astrofisica” nel triennio 2020 - 2022. Adozione dello schema di “Programma Triennale Lavori Pubblici dello "Istituto Nazionale di Astrofisica" Triennio 2020-2022, "Elenco dei Lavori” per l’anno 2020, ed “Elenco degli interventi sotto 100 mila euro”.

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    Il rapporto tecnico contiene approfondimenti ai fini della adozione del “Programma Triennale dei Lavori Pubblici 2020 – 2022”, nella sua articolazione annuale e triennale, volto alla riqualificazione, gestione, recupero, attraverso una attenta e corretta programmazione, dell’ingente patrimonio immobiliare dell’Ente, caratterizzato prevalentemente da strutture di grande pregio storico, artistico, scientifico e paesaggistico. Il documento ha inoltre la finalità di definire gli interventi da inserire nello “Schema di Programma Triennale dei Lavori Pubblici 2020-2022", in particolare nell’“Elenco dei Lavori” per l’anno 2020, selezionati in considerazione delle priorità stabilite per Legge in relazione alle disponibilità economiche autonome delle Strutture di Ricerca e della proposta di assegnazione dei fondi destinati ad interventi di edilizia nel Bilancio dell’Ente avanzata dal “Tavolo Tecnico Permanente per il Patrimonio Immobiliare e i Lavori Pubblici”

    Allocazione delle risorse per l’attuazione del “Programma dei Lavori Pubblici" per il Triennio 2020-2022 ed “Elenco dei Lavori” 2020.

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    Per l’attuazione degli interventi edilizi dell’Istituto relativamente al triennio 2020-2022 si è predisposto il quadro di dettaglio delle risorse che sono state rese disponibili per tale scopo, con riferimento alla opportuna allocazione delle medesime nel relativo Bilancio di previsione per l’annualità 2021. Il rapporto a tal fine preparato dalla struttura tecnica denominata “Tavolo Tecnico Permanente per il Patrimonio Immobiliare e i Lavori Pubblici”, è stato redatto sulla scorta degli approfondimenti tecnici ed amministrativi compiuti in fase di istruttoria sulle richieste formulate dalle Strutture di ricerca ubicate su tutto il territorio nazionale, costituenti il quadro generale delle esigenze
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