8,763 research outputs found

    Preferred levels for background ducking to produce esthetically pleasing audio for TV with clear speech

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    In audio production, background ducking facilitates speech intelligibility while allowing the background to fulfill its purpose, e.g., to create ambience, set the mood, or convey semantic cues. Technical details for recommended ducking practices are not currently documented in the literature. Hence, we first analyzed common practices found in TV documentaries. Second, a listening test investigated the preferences of 22 normal-hearing participants on the Loud- ness Difference (LD) between commentary and background during ducking. Highly personal preferences were observed, highlighting the importance of object-based personalization. Sta- tistically significant difference was found between non-expert and expert listeners. On average, non-experts preferred LDs that were 4 LU higher than the ones preferred by experts. A sta- tistically significant difference was also found between Commentary over Music (CoM) and Commentary over Ambience (CoA). Based on the test results, we recommend at least 10 LU difference for CoM and at least 15 LU for CoA. Moreover, a computational method based on the Binaural Distortion-Weighted Glimpse Proportion (BiDWGP) was found to match the median preferred LD for each item with good accuracy (mean absolute error = 1.97 LU ± 2.50)

    Modeling the RV jitter of early M dwarfs using tomographic imaging

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    In this paper we show how tomographic imaging (Zeeman Doppler Imaging, ZDI) can be used to characterize stellar activity and magnetic field topologies, ultimately allowing to filter out the radial velocity (RV) activity jitter of M-dwarf moderate rotators. This work is based on spectropolarimetric observations of a sample of five weakly-active early M-dwarfs (GJ 205, GJ 358, GJ 410, GJ479, GJ 846) with HARPS-Pol and NARVAL. These stars have v sin i and RV jitters in the range 1-2 km/s and 2.7-10.0 m/s rms respectively. Using a modified version of ZDI applied to sets of phase-resolved Least-Squares- Decon- volved (LSD) profiles of unpolarized spectral lines, we are able to characterize the distribution of active regions at the stellar surfaces. We find that darks spots cover less than 2% of the total surface of the stars of our sample. Our technique is e cient at modeling the rotationally mod- ulated component of the activity jitter, and succeeds at decreasing the amplitude of this com- ponent by typical factors of 2-3 and up to 6 in optimal cases. From the rotationally modulated time-series of circularly polarized spectra and with ZDI, we also reconstruct the large-scale magnetic field topology. These fields suggest that bi-stability of dynamo processes observed in active M dwarfs may also be at work for moderately active M dwarfs. Comparing spot distributions with field topologies suggest that dark spots causing activity jitter concentrate at the magnetic pole and/or equator, to be confirmed with future data on a larger sample.Comment: 34 pages, accepted for publication in MNRA

    Epidemiology of insomnia : prevalence, course, risk factors, and public health burden

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    This paper summarizes recent epidemiological evidence on insomnia, including its prevalence, incidence, and risk factors, as well as its course and consequences. There is now substantial evidence that insomnia is a significant public health problem. It is a highly prevalent condition, both as a symptom and a syndrome, and is often a persistent condition over time. Its persistence is associated with increased risk for mental (major depression), physical (hypertension), and occupational health problems (disability). Chronic insomnia also carries heavy economic burden, both in terms of direct healthcare costs and, more importantly, in terms of human resources loss due to the illness and lack of treatment. These findings have direct implications for community-based prevention and intervention programs and for future research including the need for: a) longitudinal, population-based studies aimed at evaluating whether we can prevent insomnia among at-risk individuals; b) clinical studies evaluating whether the morbidity associated with chronic insomnia is reversible; and c) prospective health economic evaluations of prevention programs using different dissemination technologies

    Developement dynamics of organic farming : elements for debate

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    Synthetic overview of the third workshop : development dynamics of organic farming

    Organic Farming Training and needs of stakeholders (Teachers and advisers); Status and proposals

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    The work carried out made it possible to better understand the devices of training, the knowledge of the training and development stakeholders, their expectations in the domainof organic farming. If the general principles and techniques of organic farming are fairly well known, their variation in practice is not easily normative. The courses, primarily based on knowledge transfer, are not very effective and the surveyed actors highlighted the value of networks and non-formal trainings. Proposals for changing devices are presented being based on such an innovative action in the Loire Valley with teachers and trainers. The issue of the integration of e-learning in these devices is presented with its potentialsand limits. The issue of educational resources concerning their format, their contents as the media used and their accessibility is addressed with proposals based on Swiss and the Loire Valley achievements

    Analytical Ultra High Vacuum Scanning Electron Microscopy with Field Emission Gun for Surface Study

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    Surface studies can be carried out with a scanning electron microscope (SEM) having an ultra high vacuum specimen chamber. The main application of this SEM was the micro Auger analysis, but it is also interesting to combine the usual surface study technique with SEM observations. Indeed, these latter give valuable in formation about the topographic, chemical and crystallographic aspects of the surface when the secondary, backscattered and transmission SEM modes are used. The SEM performances are increased by the use of a field emission gun, the high brightness beam of this gun gives new observation possibilities such as the imaging of crystallographic defects on solid samples

    Magnetic cycles of the planet-hosting star Tau Bootis: II. a second magnetic polarity reversal

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    In this paper, we present new spectropolarimetric observations of the planet-hosting star Tau Bootis, using ESPaDOnS and Narval spectropolarimeters at Canada-France-Hawaii Telescope (CFHT) and Telescope Bernard Lyot (TBL), respectively. We detected the magnetic field of the star at three epochs in 2008. It is a weak magnetic field of only a few Gauss, oscillating between a predominant toroidal component in January and a dominant poloidal component in June and July. A magnetic polarity reversal was observed relative to the magnetic topology in June 2007. This is the second such reversal observed in two years on this star, suggesting that Tau Boo has a magnetic cycle of about 2 years. This is the first detection of a magnetic cycle for a star other than the Sun. The role of the close-in massive planet in the short activity cycle of the star is questioned. Tau Boo has strong differential rotation, a common trend for stars with shallow convective envelope. At latitude 40 deg., the surface layer of the star rotates in 3.31 d, equal to the orbital period. Synchronization suggests that the tidal effects induced by the planet may be strong enough to force at least the thin convective envelope into corotation. Tau Boo shows variability in the Ca H & K and Halpha throughout the night and on a night to night time scale. We do not detect enhancement in the activity of the star that may be related to the conjunction of the planet. Further data is needed to conclude about the activity enhancement due to the planet.Comment: 9 pages, 5 figures, 3 tables Accepted to MNRA

    Complex magnetic topology and strong differential rotation on the low-mass T Tauri star V2247 Oph

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    From observations collected with the ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, we report the detection of Zeeman signatures on the low-mass classical TTauri star (cTTS) V2247Oph. Profile distortions and circular polarisation signatures detected in photospheric lines can be interpreted as caused by cool spots and magnetic regions at the surface of the star. The large-scale field is of moderate strength and highly complex; moreover, both the spot distribution and the magnetic field show significant variability on a timescale of only one week, as a likely result of strong differential rotation. Both properties make V2247Oph very different from the (more massive) prototypical cTTS BPTau; we speculate that this difference reflects the lower mass of V2247Oph. During our observations, V2247Oph was in a low-accretion state, with emission lines showing only weak levels of circular polarisation; we nevertheless find that excess emission apparently concentrates in a mid-latitude region of strong radial field, suggesting that it is the footpoint of an accretion funnel. The weaker and more complex field that we report on V2247Oph may share similarities with those of very-low-mass late-M dwarfs and potentially explain why low-mass cTTSs rotate on average faster than intermediate mass ones. These surprising results need confirmation from new independent data sets on V2247Oph and other similar low-mass cTTSs.Comment: MNRAS (in press) - 12 pages, 9 figure
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