968 research outputs found
Evaluation of Psychoacoustic Sound Parameters for Sonification
Sonification designers have little theory or experimental evidence to guide the design of data-to-sound mappings. Many mappings use acoustic representations of data values which do not correspond with the listener's perception of how that data value should sound during sonification. This research evaluates data-to-sound mappings that are based on psychoacoustic sensations, in an attempt to move towards using data-to-sound mappings that are aligned with the listener's perception of the data value's auditory connotations. Multiple psychoacoustic parameters were evaluated over two experiments, which were designed in the context of a domain-specific problem - detecting the level of focus of an astronomical image through auditory display. Recommendations for designing sonification systems with psychoacoustic sound parameters are presented based on our results
Low-density series expansions for directed percolation I: A new efficient algorithm with applications to the square lattice
A new algorithm for the derivation of low-density series for percolation on
directed lattices is introduced and applied to the square lattice bond and site
problems. Numerical evidence shows that the computational complexity grows
exponentially, but with a growth factor \lambda < \protect{\sqrt[8]{2}},
which is much smaller than the growth factor \lambda = \protect{\sqrt[4]{2}}
of the previous best algorithm. For bond (site) percolation on the directed
square lattice the series has been extended to order 171 (158). Analysis of the
series yields sharper estimates of the critical points and exponents.Comment: 20 pages, 8 figures (3 of them > 1Mb
T-PHOT: A new code for PSF-matched, prior-based, multiwavelength extragalactic deconfusion photometry
We present T-PHOT, a publicly available software aimed at extracting accurate
photometry from low-resolution images of deep extragalactic fields, where the
blending of sources can be a serious problem for the accurate and unbiased
measurement of fluxes and colours. T-PHOT has been developed within the
ASTRODEEP project and it can be considered as the next generation to TFIT,
providing significant improvements above it and other similar codes. T-PHOT
gathers data from a high-resolution image of a region of the sky, and uses it
to obtain priors for the photometric analysis of a lower resolution image of
the same field. It can handle different types of datasets as input priors: i) a
list of objects that will be used to obtain cutouts from the real
high-resolution image; ii) a set of analytical models; iii) a list of
unresolved, point-like sources, useful e.g. for far-infrared wavelength
domains. We show that T-PHOT yields accurate estimations of fluxes within the
intrinsic uncertainties of the method, when systematic errors are taken into
account (which can be done thanks to a flagging code given in the output).
T-PHOT is many times faster than similar codes like TFIT and CONVPHOT (up to
hundreds, depending on the problem and the method adopted), whilst at the same
time being more robust and more versatile. This makes it an optimal choice for
the analysis of large datasets. In addition we show how the use of different
settings and methods significantly enhances the performance. Given its
versatility and robustness, T-PHOT can be considered the preferred choice for
combined photometric analysis of current and forthcoming extragalactic optical
to far-infrared imaging surveys. [abridged]Comment: 23 pages, 20 figures, 2 table
Identification of z~>2 Herschel 500 micron sources using color-deconfusion
We present a new method to search for candidate z~>2 Herschel 500{\mu}m
sources in the GOODS-North field, using a S500{\mu}m/S24{\mu}m "color
deconfusion" technique. Potential high-z sources are selected against
low-redshift ones from their large 500{\mu}m to 24{\mu}m flux density ratios.
By effectively reducing the contribution from low-redshift populations to the
observed 500{\mu}m emission, we are able to identify counterparts to high-z
500{\mu}m sources whose 24{\mu}m fluxes are relatively faint. The recovery of
known z~4 starbursts confirms the efficiency of this approach in selecting
high-z Herschel sources. The resulting sample consists of 34 dusty star-forming
galaxies at z~>2. The inferred infrared luminosities are in the range
1.5x10^12-1.8x10^13 Lsun, corresponding to dust-obscured star formation rates
(SFRs) of ~260-3100 Msun/yr for a Salpeter IMF. Comparison with previous SCUBA
850{\mu}m-selected galaxy samples shows that our method is more efficient at
selecting high-z dusty galaxies with a median redshift of z=3.07+/-0.83 and 10
of the sources at z~>4. We find that at a fixed luminosity, the dust
temperature is ~5K cooler than that expected from the Td-LIR relation at z<1,
though different temperature selection effects should be taken into account.
The radio-detected subsample (excluding three strong AGN) follows the
far-infrared/radio correlation at lower redshifts, and no evolution with
redshift is observed out to z~5, suggesting that the far-infrared emission is
star formation dominated. The contribution of the high-z Herschel 500{\mu}m
sources to the cosmic SFR density is comparable to that of SMG populations at
z~2.5 and at least 40% of the extinction-corrected UV samples at z~4
(abridged).Comment: 33 pages in emulateapj format, 24 figures, 2 tables, accepted for
publication in the ApJ
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Disruption of chromosome 11 in canine fibrosarcomas highlights an unusual variability of CDKN2B in dogs.
BACKGROUND: In dogs in the western world neoplasia constitutes the most frequently diagnosed cause of death. Although there appear to be similarities between canine and human cancers, rather little is known about the cytogenetic and molecular alterations in canine tumours. Different dog breeds are susceptible to different types of cancer, but the genetic basis of the great majority of these predispositions has yet to be discovered. In some retriever breeds there is a high incidence of soft tissue sarcomas and we have previously reported alterations of chromosomes 11 and 30 in two poorly differentiated fibrosarcomas. Here we extend our observations and present a case report on detail rearrangements on chromosome 11 as well as genetic variations in a tumour suppressor gene in normal dogs. RESULTS: BAC hybridisations on metaphases of two fibrosarcomas showed complex rearrangements on chromosome 11, and loss of parts of this chromosome. Microsatellite markers on a paired tumour and blood DNA pointed to loss of heterozygosity on chromosome 11 in the CDKN2B-CDKN2A tumour suppressor gene cluster region. PCR and sequencing revealed the homozygous loss of coding sequences for these genes, except for exon 1beta of CDKN2A, which codes for the N-terminus of p14ARF. For CDKN2B exon 1, two alleles were observed in DNA from blood; one of them identical to the sequence in the dog reference genome and containing 4 copies of a 12 bp repeat found only in the canine gene amongst all species so far sequenced; the other allele was shorter due to a missing copy of the repeat. Sequencing of this exon in 141 dogs from 18 different breeds revealed a polymorphic region involving a GGC triplet repeat and a GGGGACGGCGGC repeat. Seven alleles were recorded and sixteen of the eighteen breeds showed heterozygosity. CONCLUSION: Complex chromosome rearrangements were observed on chromosome 11 in two Labrador retriever fibrosarcomas. The chromosome alterations were reflected in the loss of sequences corresponding to two tumour suppressor genes involved in cell-cycle progression. Sequencing of CDKN2B across many different breeds revealed a widespread polymorphism within the first exon of the gene, immediately before the ankyrin coding sequences
Sampling-based Algorithms for Optimal Motion Planning
During the last decade, sampling-based path planning algorithms, such as
Probabilistic RoadMaps (PRM) and Rapidly-exploring Random Trees (RRT), have
been shown to work well in practice and possess theoretical guarantees such as
probabilistic completeness. However, little effort has been devoted to the
formal analysis of the quality of the solution returned by such algorithms,
e.g., as a function of the number of samples. The purpose of this paper is to
fill this gap, by rigorously analyzing the asymptotic behavior of the cost of
the solution returned by stochastic sampling-based algorithms as the number of
samples increases. A number of negative results are provided, characterizing
existing algorithms, e.g., showing that, under mild technical conditions, the
cost of the solution returned by broadly used sampling-based algorithms
converges almost surely to a non-optimal value. The main contribution of the
paper is the introduction of new algorithms, namely, PRM* and RRT*, which are
provably asymptotically optimal, i.e., such that the cost of the returned
solution converges almost surely to the optimum. Moreover, it is shown that the
computational complexity of the new algorithms is within a constant factor of
that of their probabilistically complete (but not asymptotically optimal)
counterparts. The analysis in this paper hinges on novel connections between
stochastic sampling-based path planning algorithms and the theory of random
geometric graphs.Comment: 76 pages, 26 figures, to appear in International Journal of Robotics
Researc
Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b
Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad
near-infrared H and K-band spectra of the young exoplanet HR8799b have been
obtained. In addition, six new narrow-band photometric measurements have been
taken across the H and K bands. These data are combined with previously
published photometry for an analysis of the planet's atmospheric properties.
Thick photospheric dust cloud opacity is invoked to explain the planet's red
near-IR colors and relatively smooth near-IR spectrum. Strong water absorption
is detected, indicating a Hydrogen-rich atmosphere. Only weak CH4 absorption is
detected at K band, indicating efficient vertical mixing and a disequilibrium
CO/CH4 ratio at photospheric depths. The H-band spectrum has a distinct
triangular shape consistent with low surface gravity. New giant planet
atmosphere models are compared to these data with best fitting bulk parameters,
Teff = 1100K +- 100 and log(g) = 3.5 +-0.5 (for solar composition). Given the
observed luminosity, log(Lobs/Lsun) ~ -5.1, these values correspond to a radius
of 0.75 Rjup (+0.17, -0.12) and mass ~ 0.72 Mjup (+2.6,-0.6) -- strikingly
inconsistent with interior/evolution models. Enhanced metallicity (up to ~ 10
times that of the Sun) along with thick clouds and non-equilibrium chemistry
are likely required to reproduce the complete ensemble of spectroscopic and
photometric data and the low effective temperatures (< 1000K) required by the
evolution models.Comment: 17 pages, accepted for publication in The Astrophysical Journa
Imaging and spectroscopy of arcs around the most luminous X-ray cluster RX J1347.5-1145
The cluster RX J1347.5-1145, the most luminous cluster in the X-ray
wavelengths, was imaged with the newly installed Space Telescope Imaging
Spectrograph (STIS) on-board HST. Its relatively high redshift (0.451) and
luminosity indicate that this is one of the most massive of all known clusters.
The STIS images unambiguously show several arcs in the cluster. The largest two
arcs (> 5 arcsec in length) are symmetrically situated on opposite sides of the
cluster, at a distance of ~ 35 arcsec from the central galaxy. The STIS images
also show approximately 100 faint galaxies within the radius of the arcs whose
combined luminosity is ~ 4 x 10^11 Lsun. We also present ground-based
spectroscopic observations of the northern arc which show one clear emission
line at 6730 A, which is consistent with an identification as [OII] 3727 A,
implying a redshift of 0.81 for this arc. The southern arc shows a faint
continuum but no emission features. The surface mass within the radius of the
arcs (240 kpc), as derived from the gravitational lensing, is 6.3 x 10^14 Msun.
The resultant mass-to-light ratio of ~1200 is higher than what is seen in many
clusters but smaller than the value recently derived for some `dark' X-ray
clusters (Hattori et al. 1997). The total surface mass derived from the X-ray
flux within the radius of the arcs is ~2.1 - 6.8 x 10^14 Msun, which implies
that the ratio of the gravitational to the X-ray mass is ~1 to 3. The surface
GAS mass within this radius is ~3.5 x 10^13 Msun, which implies that at least
6% of the total mass within this region is baryonic.Comment: 3 figures. Replaced with the final version as appears in the
Astrophysical Journal Letters (Jan 10, 1998 issue). This incorporates some
important revision
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