1,745 research outputs found
Radio emission from satellite-Jupiter interactions (especially Ganymede)
Analyzing a database of 26 years of observations of Jupiter from the
Nan\c{c}ay Decameter Array, we study the occurrence of Io-independent emissions
as a function of the orbital phase of the other Galilean satellites and
Amalthea. We identify unambiguously the emissions induced by Ganymede and
characterize their intervals of occurrence in CML and Ganymede phase and
longitude. We also find hints of emissions induced by Europa and, surprisingly,
by Amalthea. The signature of Callisto-induced emissions is more tenuous.Comment: 14 pages, 7 figures, in "Planetary Radio Emissions VIII", G. Fischer,
G. Mann, M. Panchenko and P. Zarka eds., Austrian Acad. Sci. Press, Vienna,
in press, 201
Rough Mirror as a Quantum State Selector: Analysis and Design
We report analysis of rough mirrors used as the gravitational state selectors in neutron beam and similar experiments. The key to mirror properties is its roughness correlation function (CF) which is extracted from the precision optical scanning measurements of the surface profile. To identify CF in the presence of fluctuation-driven fat tails, we perform numerical experiments with computer-generated random surfaces with the known CF. These numerical experiments provide a reliable identification procedure which we apply to the actual rough mirror. The extracted CF allows us to make predictions for ongoing GRANIT experiments. We also propose a radically new design for rough mirrors based on Monte Carlo simulations for the 1D Ising model. The implementation of this design provides a controlled environment with predictable scattering properties
Millimetre continuum observations of comet C/2009 P1 (Garradd)
Little is known about the physical properties of the nuclei of Oort cloud
comets. Measuring the thermal emission of a nucleus is one of the few means for
deriving its size and constraining some of its thermal properties. We attempted
to measure the nucleus size of the Oort cloud comet C/2009 P1 (Garradd). We
used the Plateau de Bure Interferometer to measure the millimetric thermal
emission of this comet at 157 GHz (1.9 mm) and 266 GHz (1.1 mm). Whereas the
observations at 266 GHz were not usable due to bad atmospheric conditions, we
derived a 3-sigma upper limit on the comet continuum emission of 0.41 mJy at
157 GHz. Using a thermal model for a spherical nucleus with standard thermal
parameters, we found an upper limit of 5.6 km for the radius. The dust
contribution to our signal is estimated to be negligible. Given the water
production rates measured for this comet and our upper limit, we estimated that
Garradd was very active, with an active fraction of its nucleus larger than
50%.Comment: Accepted for publication in Astronomy & Astrophysics. 5 pages, 2
figure
The Dust Trail of Comet 67P/Churyumov-Gerasimenko between 2004 and 2006
We report on observations of the dust trail of comet
67P/Churyumov-Gerasimenko (CG) in visible light with the Wide Field Imager at
the ESO/MPG 2.2m telescope at 4.7 AU before aphelion, and at 24 micron with the
MIPS instrument on board the Spitzer Space Telescope at 5.7 AU both before and
after aphelion. The comet did not appear to be active during our observations.
Our images probe large dust grains emitted from the comet that have a radiation
pressure parameter beta<0.01. We compare our observations with simulated images
generated with a dynamical model of the cometary dust and constrain the
emission speeds, size distribution, production rate and geometric albedo of the
dust. We achieve the best fit to our data with a differential size distribution
exponent of -4.1, and emission speeds for a beta=0.01 particle of 25 m/s at
perihelion and 2 m/s at 3 AU. The dust production rate in our model is on the
order of 1000 kg/s at perihelion and 1 kg/s at 3 AU, and we require a dust
geometric albedo between 0.022 and 0.044. The production rates of large (>10
micron) particles required to reproduce the brightness of the trail are
sufficient to also account for the coma brightness observed while the comet was
inside 3 AU, and we infer that the cross-section in the coma of CG may be
dominated by grains of the order of 60-600 micron.Comment: 79 pages, 13 figures, 6 tables. Accepted for publication in Icaru
The taste & affect music database: Subjective rating norms for a new set of musical stimuli
Music is a ubiquitous stimulus known to influence human affect, cognition, and behavior. In the context of eating behavior, music has been associated with food choice, intake and, more recently, taste perception. In the latter case, the literature has reported consistent patterns of association between auditory and gustatory attributes, suggesting that individuals reliably recognize taste attributes in musical stimuli. This study presents subjective norms for a new set of 100 instrumental music stimuli, including basic taste correspondences (sweetness, bitterness, saltiness, sourness), emotions (joy, anger, sadness, fear, surprise), familiarity, valence, and arousal. This stimulus set was evaluated by 329 individuals (83.3% women; Mage = 28.12, SD = 12.14), online (n = 246) and in the lab (n = 83). Each participant evaluated a random subsample of 25 soundtracks and responded to self-report measures of mood and taste preferences, as well as the Goldsmiths Musical Sophistication Index (Gold-MSI). Each soundtrack was evaluated by 68 to 97 participants (Mdn = 83), and descriptive results (means, standard deviations, and confidence intervals) are available as supplemental material at osf.io/2cqa5. Significant correlations between taste correspondences and emotional/affective dimensions were observed (e.g., between sweetness ratings and pleasant emotions). Sex, age, musical sophistication, and basic taste preferences presented few, small to medium associations with the evaluations of the stimuli. Overall, these results suggest that the new Taste & Affect Music Database is a relevant resource for research and intervention with musical stimuli in the context of crossmodal taste perception and other affective, cognitive, and behavioral domains.info:eu-repo/semantics/acceptedVersio
Full-Course Oral Levofloxacin for Treatment of Hospitalized Patients with Community-Acquired Pneumonia
Most guidelines for the management of hospitalized patients with community-acquired pneumonia (CAP) recommend commencing therapy with intravenous antibiotics, primarily because of concern about absorption of oral antibiotics in acutely ill patients. However, patients who respond are rapidly switched to oral therapy, which has been shown to reduce costs and to shorten the length of stay. The aim of the present study was to determine whether a full course of oral antibiotics is as efficacious and as safe as intravenous-to-oral sequential antibiotic therapy for the treatment of hospitalized, non-ICU patients with CAP. In an open-labelled, controlled study, 129 hospitalized patients with CAP were randomly assigned in a 2:1 ratio to receive either a full course of oral levofloxacin (500mg q12h) or an intravenous-to-oral sequential therapy consisting of intravenous ceftriaxone (2g q24h) with or without clarithromycin (500mg q12h) followed by an oral antibiotic (a beta-lactam agent in the majority of patients). The primary study endpoint was the resolution of CAP; secondary endpoints included length of stay and overall mortality. CAP resolved in 72 of 79 (91.1%) patients in the levofloxacin group and in 34 of 37 (91.9%) patients in the intravenous-to-oral sequential therapy group (difference, −0.8%, 95%CI, −11.6-10.0). Median length of stay was 8 days (range, 2-74 days) in the levofloxacin group and 10 days (range, 3-29 days) in the intravenous-to-oral sequential therapy group (P=0.28). Day 30 mortality rates were 1.3% (1 of 79) and 8.1% (3 of 37), respectively (difference, −6.8%, 95%CI, −16.0-2.3). Full-course oral levofloxacin is as efficacious and as safe as standard intravenous-to-oral sequential antibiotic therapy for the treatment of hospitalized patients with CA
Normal subgroups in the Cremona group (long version)
Let k be an algebraically closed field. We show that the Cremona group of all
birational transformations of the projective plane P^2 over k is not a simple
group. The strategy makes use of hyperbolic geometry, geometric group theory,
and algebraic geometry to produce elements in the Cremona group that generate
non trivial normal subgroups.Comment: With an appendix by Yves de Cornulier. Numerous but minors
corrections were made, regarding proofs, references and terminology. This
long version contains detailled proofs of several technical lemmas about
hyperbolic space
Outburst of Comet 17P/Holmes Observed With The Solar Mass Ejection Imager
We present time-resolved photometric observations of Jupiter family comet
17P/Holmes during its dramatic outburst of 2007. The observations, from the
orbiting Solar Mass Ejection Imager (SMEI), provide the most complete measure
of the whole-coma brightness, free from the effects of instrumental saturation
and with a time-resolution well-matched to the rapid brightening of the comet.
The lightcurve is divided into two distinct parts. A rapid rise between the
first SMEI observation on UT 2007 October 24 06h 37m (mid-integration) and UT
2007 October 25, is followed by a slow decline until the last SMEI observation
on UT 2008 April 6 22h 16m (mid-integration). We find that the rate of change
of the brightness is reasonably well-described by a Gaussian function having a
central time of UT 2007 October 24.54+/-0.01 and a full-width-at-half-maximum
0.44+/-0.02 days. The maximum rate of brightening occurs some 1.2 days after
the onset of activity. At the peak the scattering cross-section grows at
1070+/-40 km^2/s while the (model-dependent) mass loss rates inferred from the
lightcurve reach a maximum at 3+/-10^5 kg/s. The integrated mass in the coma
lies in the range (2 to 90)x10^10 kg, corresponding to 0.2% to 10% of the
nucleus mass, while the kinetic energy of the ejecta is (0.6 to 30) MTonnes
TNT. The particulate coma mass could be contained within a shell on the nucleus
of thickness ~1.5 to 60 m. This is comparable to the distance traveled by
conducted heat in the century since the previous outburst of 17P/Holmes. This
coincidence is consistent with, but does not prove, the idea that the outburst
was triggered by the action of conducted heat, possibly through the
crystallization of buried amorphous ice.Comment: 27 pages, 8 figures;
http://www2.ess.ucla.edu/~jingli/Holmes_SMEI/17P_Holmes.htm
The evolution of plasma parameters on a coronal source surface at 2.3 Rs during solar minimum
We analyze data from the Solar and Heliospheric Observatory to produce global
maps of coronal outflow velocities and densities in the regions where the solar
wind is undergoing acceleration. The maps use UV and white light coronal data
obtained from the Ultraviolet Coronagraph Spectrometer and the Large Angle
Spectroscopic Coronagraph, respectively, and a Doppler dimming analysis to
determine the mean outflow velocities. The outflow velocities are defined on a
sphere at 2.3 Rs from Sun-center and are organized by Carrington Rotations
during the solar minimum period at the start of solar cycle 23. We use the
outflow velocity and density maps to show that while the solar minimum corona
is relatively stable during its early stages, the shrinkage of the north polar
hole in the later stages leads to changes in both the global areal expansion of
the coronal hole and the derived internal flux tube expansion factors of the
solar wind. The polar hole areal expansion factor and the flux tube expansion
factors (between the coronal base and 2.3 Rs) start out as super-radial but
then they become more nearly radial as the corona progresses away from solar
minimum. The results also support the idea that the largest flux tube expansion
factors are located near the coronal hole/streamer interface, at least during
the deepest part of the solar minimum period.Comment: 12 Figures, Accepted for publication in Ap
Jupiter radio emission induced by Ganymede and consequences for the radio detection of exoplanets
International audienceBy analysing a database of 26 yr of observations of Jupiter with the Nancay Decameter Array, we unambiguously identify the radio emissions caused by the Ganymede-Jupiter interaction. We study the energetics of these emissions via the distributions of their intensities, duration, and power, and compare them to the energetics of the Io-Jupiter radio emissions. This allows us to demonstrate that the average emitted radio power is proportional to the Poynting flux from the rotating Jupiter's magnetosphere intercepted by the obstacle. We then generalize this result to the radio-magnetic scaling law that appears to apply to all plasma interactions between a magnetized flow and an obstacle, magnetized or not. Extrapolating this scaling law to the parameter range corresponding to hot Jupiters, we predict large radio powers emitted by these objects, that should result in detectable radio flux with new-generation radiotelescopes. Comparing the distributions of the durations of Ganymede-Jupiter and Io-Jupiter emission events also suggests that while the latter results from quasi-permanent Alfven wave excitation by Io, the former likely results from sporadic reconnection between magnetic fields Ganymede and Jupiter, controlled by Jupiter's magnetic field geometry and modulated by its rotation
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