127 research outputs found

    Unveiling the unknown of cool stars with high-resolution spectroscopy

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    Cool giant and supergiant stars are among the brightest populations in any stellar system and they are easily observable out to large distances, especially at infrared wavelengths. These stars also dominate the integrated light of star clusters in a wide range of ages, making them powerful tracers of stellar populations in more distant galaxies. High-resolution near-IR spectroscopy is a key tool for quantitatively investigating their kinematic, evolutionary and chemical properties. However, the systematic exploration and calibration of the NIR spectral diagnostics to study these cool stellar populations based on high-resolution spectroscopy is still in its pioneering stage. Any effort to make progress in the field is innovative and of impact on stellar archaeology and stellar evolution. This PhD project takes the challenge of exploring that new parameter space and characterizing the physical properties, the chemical content and the kinematics of cool giants and supergiants in selected disc fields and clusters of our Galaxy, with the ultimate goal of tracing their past and recent star formation and chemical enrichment history. By using optical HARPS-N and near-infrared GIANO-B high-resolution stellar spectra in the context of the large program SPA-Stellar Population Astrophysics: the detailed, age-resolved chemistry of the Milky Way disk” (PI L. Origlia), an extensive study of Arcturus, a standard calibrator for red giant stars, has been performed. New diagnostics of stellar parameters as well as optimal linelists for chemical analysis have been provided. Then, such diagnostics have been used to determine evolutionary properties, detailed chemical abundances of almost 30 different elements and mixing processes of a homogeneous sample of red supergiant stars in the Perseus complex

    Photoproduction of axion-like particles

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    We explore the sensitivity of photon-beam experiments to axion-like particles (ALPs) with QCD-scale masses whose dominant coupling to the Standard Model is either to photons or gluons. We introduce a novel data-driven method that eliminates the need for knowledge of nuclear form factors or the photon-beam flux when considering coherent Primakoff production off a nuclear target, and show that data collected by the PrimEx experiment could substantially improve the sensitivity to ALPs with 0.03≲ma≲0.30.03 \lesssim m_a \lesssim 0.3 GeV. Furthermore, we explore the potential sensitivity of running the GlueX experiment with a nuclear target and its planned PrimEx-like calorimeter. For the case where the dominant coupling is to gluons, we study photoproduction for the first time, and predict the future sensitivity of the GlueX experiment using its nominal proton target. Finally, we set world-leading limits for both the ALP-gluon coupling and the ALP-photon coupling based on public mass plots.Comment: 17 pages, 7 figures; v3 corrected PrimEx results for luminosity error; v2 added missing factor when drawing the GlueX limits on the ALP-gluon coupling, fixed convention discrepancy in the SeaQuest ALP-photon limits, other minor edit

    The GlueX DIRC Project

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    The GlueX experiment was designed to search for and study the pattern of gluonic excitations in the meson spectrum produced through photoproduction reactions at a new tagged photon beam facility in Hall D at Jefferson Laboratory. The particle identification capabilities of the GlueX experiment will be enhanced by constructing a DIRC (Detection of Internally Reflected Cherenkov light) detector, utilizing components of the decommissioned BaBar DIRC. The DIRC will allow systematic studies of kaon final states that are essential for inferring the quark flavor content of both hybrid and conventional mesons. The design for the GlueX DIRC is presented, including the new expansion volumes that are currently under development.Comment: 8 pages, 6 figure

    A new method for measuring and calibrating cinema audio systems for optimal sound quality

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    The aim of this research is to utilize new methodologies and technology in order to gain insight into how the modern cinema audio system could be calibrated to provide improved audio performance. To this end, both objective and subjective measurements were developed to better understand the audio preferences of listeners, the requirements of the audio systems inclusive of the acoustic environment, and how the two are related. Part of the data for this research was derived from a survey of re-recording mixers regarding their use and opinion of the current SMPTE standard. The survey confirmed anecdotal information suggesting that re-recording mixers use high-end pre-emphasis to compensate for the severe roll-off induced by the SMPTE X-curve. It is also noted that the re-recording mixers' opinions of how well their mix translates from dub-stage to cinema is correlated to how many years they have spent in the industry. The aim of this research is to utilize new methodologies and technology in order to gain insight into how the modern cinema audio system could be calibrated to provide improved audio performance. To this end, both objective and subjective measurements were developed to better understand the audio preferences of listeners, the requirements of the audio systems inclusive of the acoustic environment, and how the two are related. Part of the data for this research was derived from a survey of re-recording mixers regarding their use and opinion of the current SMPTE standard. The survey confirmed anecdotal information suggesting that re-recording mixers use high-end pre-emphasis to compensate for the severe roll-off induced by the SMPTE X-curve. It is also noted that the re-recording mixers' opinions of how well their mix translates from dub-stage to cinema is correlated to how many years they have spent in the industry. To further understand listener preference to in-room responses curves, a series of listening tests utilizing the BRS system were conducted using various sized cinemas, seating positions within the cinemas, audio tracks (including those mixed on a SMPTE calibrated dub-stage) and target curves. The overwhelming outcome was that regardless of cinema size, seating position or audio track utilized; the "curve" that listeners preferred is a relatively flat 0.9dB/octave slope with a 6.5dB bass boost below 105Hz and a -2.5dB roll off above 2.5kHz. Of the 5 target curves presented, the SMPTE X-curve place fourth with scores very near the low-rated perceptual anchor. This calls into question the notion of the X-curve providing "ideal" translation between dub-stage and cinema and in fact, challenges the concept of translation all together. Research was completed in an effort to identifying the number of microphone positions required, along with their placement, in order to accurately capture a cinema's response for calibration purposes. A novel experiment utilizing anechoic loudspeaker data as a guideline for xxi analysis demonstrated that, with proper data, the number of microphones and their positions plays a less critical factor in determining the room response. The collected data shows that even with as few as 4 microphones at varied positions, the resultant room response will trend towards the anechoic data above 1kHz. From around 300Hz to 1kHz, there is evidence of seat effects that may be resolved through randomizing the microphone heights. Below 300Hz, the room becomes the dominating factor and more than 5 microphone positions will be required to properly identify any problems

    Rapporto 2007 su consumo e dipendenze da sostanze in Emilia-Romagna.

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    Report on the state of legal and illegal substances use in the territory of Emilia-Romagna Region.Il report analizza il fenomeno delle dipendenze nel territorio della Regione Emilia-Romagna. La descrizione del fenomeno si sviluppa intorno all\u27analisi degli indicatori individuati dall\u27Osservatorio Europeo delle Dipendenze di Lisbona (OEDT): 1-uso di sostanze nella popolazione generale (questo indicatore va a rilevare i comportamenti nei confronti di alcol e sostanze psicoattive da parte della popolazione generale); 2-prevalenza d\u27uso problematico delle sostanze psicoattive; 3-domanda di trattamento degli utilizzatori di sostanze; 4-mortalit? degli utilizzatori di sostanze; 5-malattie infettive. Altri due importanti indicatori che si stanno sviluppando, e che vengono qui illustrati, sono l\u27analisi delle Schede di Dimissione Ospedaliera (SDO) e gli indicatori relativi alle conseguenza sociali dell\u27uso di droghe (criminalit? droga correlata). Inoltre sono state applicate diverse metodologie standard di stima sia per quantificare la quota parte sconosciuta di utilizzatori di sostanze che non afferiscono ai servizi, sia per identificarne alcune caratteristiche
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