606 research outputs found
On the interpretation of echelle diagrams for solar-like oscillations. Effect of centrifugal distortion
This work aims at determining the impact of slow to moderate rotation on the
regular patterns often present in solar-like oscillation spectra. We focus on
the well-known asteroseismic diagnostic echelle diagrams, examining how
rotation may modify the estimates of the large and small spacings, as well as
the identification of modes. We illustrate the work with a real case: the
solar-like star Bootis. The modeling takes into account rotation effects
on the equilibrium models through an effective gravity and on the oscillation
frequencies through both perturbative and non-perturbative calculations. We
compare the results of both type of calculations in the context of the regular
spacings (like the small spacings and the scaled small spacings) and echelle
diagrams. We show that for echelle diagrams the perturbative approach remains
valid for rotational velocities up to 40-50 km/s. We show that for the
rotational velocities measured in solar-like stars, theoretical oscillation
frequencies must be corrected up to the second-order in terms of rotation rate,
including near degeneracy effects. For rotational velocities of about 16 km/S
and higher, diagnostics on large spacings and on modal identification through
echelle diagrams can be significantly altered by the presence of the
components of the rotationally split modes. We found these effects to be
detectable in the observed frequency range. Analysis of the effects of rotation
on small spacings and scaled small spacings reveals that these can be of the
order of, or even larger than surface effects, typically turbulence,
microscopic diffusion, etc. Furthermore, we show that scaled spacings are
significantly affected by stellar distortion even for small stellar rotational
velocities (from 10-15 km/s) and therefore some care must be taken when using
them as indicators for probing deep stellar interiors.Comment: 10 pages,5 figures, accepted for publication in ApJ;
http://iopscience.iop.org/0004-637X/721/1/537
Prospects for Measuring Differential Rotation in White Dwarfs Through Asteroseismology
We examine the potential of asteroseismology for exploring the internal
rotation of white dwarf stars. Data from global observing campaigns have
revealed a wealth of frequencies, some of which show the signature of
rotational splitting. Tools developed for helioseismology to use many solar
p-mode frequencies for inversion of the rotation rate with depth are adapted to
the case of more limited numbers of modes of low degree. We find that the small
number of available modes in white dwarfs, coupled with the similarity between
the rotational-splitting kernels of the modes, renders direct inversion
unstable. Accordingly, we adopt what we consider to be plausible functional
forms for the differential rotation profile; this is sufficiently restrictive
to enable us to carry out a useful calibration. We show examples of this
technique for PG 1159 stars and pulsating DB white dwarfs. Published frequency
splittings for white dwarfs are currently not accurate enough for meaningful
inversions; reanalysis of existing data can provide splittings of sufficient
accuracy when the frequencies of individual peaks are extracted via
least-squares fitting or multipeak decompositions. We find that when mode
trapping is evident in the period spacing of g modes, the measured splittings
can constrain dOmega/dr.Comment: 26 pages, 20 postscript figures. Accepted for publication in The
Astrophysical Journa
Listenersâ perceptions of the certainty and honesty of a speaker are associated with a common prosodic signature
The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics. Yet, how such epistemic vigilance is achieved from naturalistic sensory inputs remains unclear. Here we show that listenersâ perceptions of the certainty and honesty of other speakers from their speech are based on a common prosodic signature. Using a data-driven method, we separately decode the prosodic features driving listenersâ perceptions of a speakerâs certainty and honesty across pitch, duration and loudness. We find that these two kinds of judgments rely on a common prosodic signature that is perceived independently from individualsâ conceptual knowledge and native language. Finally, we show that listeners extract this prosodic signature automatically, and that this impacts the way they memorize spoken words. These findings shed light on a unique auditory adaptation that enables human listeners to quickly detect and react to unreliability during linguistic interactions
Publisher Correction: Listenersâ perceptions of the certainty and honesty of a speaker are associated with a common prosodic signature
Correction to: Nature Communications https://doi.org/10.1038/s41467-020-20649-4, published online 8 February 2021.
The original version of the Supplementary Information associated with this Article contained errors in Supplementary Figures 1, 3, 4, 5, 7 and 8 and an error in the figure legend of Supplementary Figure 8. The HTML has been updated to include a corrected version of the Supplementary Information; the original incorrect version of the Supplementary Information file can be found as Supplementary Information associated with this Correction
Musical coordination in a large group without plans nor leaders
A widespread belief is that large groups engaged in joint actions that require a high level of flexibility are unable to coordinate without the introduction of additional resources such as shared plans or hierarchical organizations. Here, we put this belief to a test, by empirically investigating coordination within a large group of 16 musicians performing collective free improvisationâa genre in which improvisers aim at creating music that is as complex and unprecedented as possible without relying on shared plans or on an external conductor. We show that musicians freely improvising within a large ensemble can achieve significant levels of coordination, both at the level of their musical actions (i.e., their individual decisions to play or to stop playing) and at the level of their directional intentions (i.e., their intentions to change or to support the music produced by the group). Taken together, these results invite us to reconsider the range and scope of actions achievable by large groups, and to explore alternative organizational models that emphasize decentralized and unscripted forms of collective behavior
Persistence of characteristics of an ordered flux line lattice above the second peak in
We report Small Angle Neutron Scattering measurements of the flux lines
lattice (FLL) in . As previously reported, the
scattered intensity decreases strongly when the magnetic field is increased,
but it remains measurable far above the second peak. The direct observation of
Bragg peaks proves that the characteristics of a lattice are still present. No
structural features related to a symmetry breaking, such as a liquid like or an
amorphous state, can be observed. However, the associated scattered intensity
is very low and is difficult to explain. We discuss the coexistence between two
FLL states as a possible interpretation.Comment: accepted for publication in Phys Rev
Wave chaos in rapidly rotating stars
Effects of rapid stellar rotation on acoustic oscillation modes are poorly
understood. We study the dynamics of acoustic rays in rotating polytropic stars
and show using quantum chaos concepts that the eigenfrequency spectrum is a
superposition of regular frequency patterns and an irregular frequency subset
respectively associated with near-integrable and chaotic phase space regions.
This opens new perspectives for rapidly rotating star seismology and also
provides a new and potentially observable manifestation of wave chaos in a
large scale natural system.Comment: 5 pages, 3 figures; accepted for publication in Phys. Rev.
Listenersâ perceptions of the certainty and honesty of a speaker are associated with a common prosodic signature
The success of human cooperation crucially depends on mechanisms enabling individuals to detect unreliability in their conspecifics. Yet, how such epistemic vigilance is achieved from naturalistic sensory inputs remains unclear. Here we show that listenersâ perceptions of the certainty and honesty of other speakers from their speech are based on a common prosodic signature. Using a data-driven method, we separately decode the prosodic features driving listenersâ perceptions of a speakerâs certainty and honesty across pitch, duration and loudness. We find that these two kinds of judgments rely on a common prosodic signature that is perceived independently from individualsâ conceptual knowledge and native language. Finally, we show that listeners extract this prosodic signature automatically, and that this impacts the way they memorize spoken words. These findings shed light on a unique auditory adaptation that enables human listeners to quickly detect and react to unreliability during linguistic interactions
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