589 research outputs found
Modeling Perceptions of Valence in Diverse Music: Roles of Acoustic Features, Agency and Individual Variation
We investigate the roles of the acoustic parameters intensity and spectral flatness in the modeling of continuously measured perceptions of affect in nine diverse musical extracts. The extract sources range from Australian Aboriginal and Balinese music, to classical music from Mozart to minimalism and Xenakis; and include jazz, ambient, drum n' bass and performance text. We particularly assess whether modeling perceptions of the valence expressed by the music, generally modeled less well than the affective dimension of arousal, can be enhanced by inclusion of perceptions of change in the sound, human agency, musical segmentation, and random effects across participants, as model components. We confirm each of these expectations, and provide indications that perceived change in the music may eventually be subsumed adequately under its components such as acoustic features and agency. We find that participants vary substantially in the predictors useful for modeling their responses (judged by the random effects components of mixed effects cross-sectional time series analyses). But we also find that pieces do too, while yet sharing sufficient features that a single common model of the responses to all nine pieces has competitive precision
Relationships between generated musical structure, performers’ physiological arousal and listener perceptions in solo piano improvisation
What musical structures do improvisers produce, and how do these relate to their physiological arousal while performing and to listener perceptions? Nine professional improvisers performed both structured and free improvisations. We hypothesised that increases in performers’ arousal and attention during structural transitions would be reflected by changes in skin conductance. Consistent with the hypothesis, skin conductance changed particularly around transitions. Improvisers then listened to their improvisations, continuously rating musical change. Fourteen non-musicians also rated change, and separately rated perceptions of affect. Their perceptions related to structural parameters, though these were less influenced by musical features than those of the performers
A bright millisecond radio burst of extragalactic origin
Pulsar surveys offer one of the few opportunities to monitor even a small
fraction (~0.00001) of the radio sky for impulsive burst-like events with
millisecond durations. In analysis of archival survey data, we have discovered
a 30-Jy dispersed burst of duration <5 ms located three degrees from the Small
Magellanic Cloud. The burst properties argue against a physical association
with our Galaxy or the Small Magellanic Cloud. Current models for the free
electron content in the Universe imply a distance to the burst of <1 Gpc No
further bursts are seen in 90-hr of additional observations, implying that it
was a singular event such as a supernova or coalescence of relativistic
objects. Hundreds of similar events could occur every day and act as insightful
cosmological probes.Comment: 18 pages, 4 figures. Accepted by Science. Published electronically
via Science Express on September 27, 200
Optical Observations of the Binary Millisecond Pulsars J2145-0750 and J0034-0534
We report on optical observations of the low-mass binary millisecond pulsar
systems J0034-0534 and J2145-0750. A faint (I=23.5) object was found to be
coincident with the timing position of PSR J2145-0750. While a galaxy or
distant main-sequence star cannot be ruled out, its magnitude is consistent
with an ancient white dwarf, as expected from evolutionary models. For PSR
J0034-0534 no objects were detected to a limiting magnitude of R=25.0,
suggesting that the white dwarf in this system is cold. Using white dwarf
cooling models, the limit on the magnitude of the PSR J0034-0534 companion
suggests that at birth the pulsar in this system may have rotated with a period
as short as 0.6 ms. These observations provide further evidence that the
magnetic fields of millisecond pulsars do not decay on time scales shorter than
1 Gyr.Comment: 6 pages, uuencoded, gz -9 compressed postscript, accepted by ApJ
A New Method for Obtaining Binary Pulsar Distances and its Implications for Tests of General Relativity
We demonstrate how measuring orbital period derivatives can lead to more
accurate distance estimates and transverse velocities for some nearby binary
pulsars. In many cases this method will estimate distances more accurately than
is possible by annual parallax, as the relative error decreases as t^-5/2.
Unfortunately, distance uncertainties limit the degree to which nearby
relativistic binary pulsars can be used for testing the general relativistic
prediction of orbital period decay to a few percent. Nevertheless, the measured
orbital period derivative of PSR B1534+12 agrees within the observational
uncertainties with that predicted by general relativity if the proper-motion
contribution is accounted for.Comment: 4 pages, latex, uuencoded compressed postscript + source, no figures,
uses aaspptwo.sty and dec.sty, accepted for publication in ApJL, omitted
reference now include
Are the distributions of Fast Radio Burst properties consistent with a cosmological population?
High time resolution radio surveys over the last few years have discovered a
population of millisecond-duration transient bursts called Fast Radio Bursts
(FRBs), which remain of unknown origin. FRBs exhibit dispersion consistent with
propagation through a cold plasma and dispersion measures indicative of an
origin at cosmological distances. In this paper we perform Monte Carlo
simulations of a cosmological population of FRBs, based on assumptions
consistent with observations of their energy distribution, their spatial
density as a function of redshift and the properties of the interstellar and
intergalactic media. We examine whether the dispersion measures, fluences,
inferred redshifts, signal-to-noises and effective widths of known FRBs are
consistent with a cosmological population. Statistical analyses indicate that
at least 50 events at Parkes are required to distinguish between a constant
co-moving FRB density, and a FRB density that evolves with redshift like the
cosmological star formation rate density.Comment: 11 pages, 7 figures, 3 table
Spin-down evolution and radio disappearance of the magnetar PSR J16224950
We report on 2.4 yr of radio timing measurements of the magnetar PSR
J16224950 using the Parkes telescope, between 2011 November and 2014 March.
During this period the torque on the neutron star (inferred from the rotational
frequency derivative) varied greatly, though much less erratically than in the
2 yr following its discovery in 2009. During the last year of our measurements
the frequency derivative decreased in magnitude monotonically by 20\%, to a
value of s, a factor of 8 smaller than when
discovered. The flux density continued to vary greatly during our monitoring
through 2014 March, reaching a relatively steady low level after late 2012. The
pulse profile varied secularly on a similar timescale as the flux density and
torque. A relatively rapid transition in all three properties is evident in
early 2013. After PSR J16224950 was detected in all of our 87 observations
up to 2014 March, we did not detect the magnetar in our resumed monitoring
starting in 2015 January and have not detected it in any of the 30 observations
done through 2016 September.Comment: 8 pages, 5 figures, submitted to Ap
Relativistic spin precession in the binary PSR J11416545
PSR J11416545 is a precessing binary pulsar that has the rare potential to
reveal the two-dimensional structure of a non-recycled pulsar emission cone. It
has undergone of relativistic spin precession in the
years since its discovery. In this paper, we present a detailed Bayesian
analysis of the precessional evolution of the width of the total intensity
profile, to understand the changes to the line-of-sight impact angle ()
of the pulsar using four different physically motivated prior distribution
models. Although we cannot statistically differentiate between the models with
confidence, the temporal evolution of the linear and circular polarisations
strongly argue that our line-of-sight crossed the magnetic pole around MJD
54000 and that only two models remain viable. For both these models, it appears
likely that the pulsar will precess out of our line-of-sight in the next
years, assuming a simple beam geometry. Marginalising over suggests
that the pulsar is a near-orthogonal rotator and provides the first
polarization-independent estimate of the scale factor () that
relates the pulsar beam opening angle () to its rotational period ()
as : we find it to be at 1.4
GHz with 99\% confidence. If all pulsars emit from opposite poles of a dipolar
magnetic field with comparable brightness, we might expect to see evidence of
an interpulse arising in PSR J11416545, unless the emission is patchy.Comment: Accepted for publication in Astrophysical Journal Letter
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