570 research outputs found
Lexicality Effects in Reading Aloud: Where are They?
A report submitted by Michael J. Cortese to the Research and Creative Productions Committee in 2001 on contrasting models of word recognition and the criterion used to initiate pronunciation in reading aloud
Regularity effects in word naming: What are they?
In a word-naming experiment, word-body consistency was crossed with grapheme-to-phoneme regularity to test predictions of current models of word recognition. In the latency and error data, a clear effect of consistency was observed, with the influence of regularity somewhat weaker. In addition, simulation data from three contemporary models of word recognition were obtained for the stimuli used in the experiment in order to compare the modelsâ latencies with those of humans. The simulations showed that the human latency data are most consistent with the parallel-distributed-processing model of Plaut, McClelland, Seidenberg, and Patterson (1996), less so with the dual-process model (Zorzi, Houghton, & Butterworth, 1998), and least so with the dual-route-cascaded model (Coltheart & Rastle, 1994)
Learning New Words Affects Nonword Pronunciation in Children
In two experiments we examined how childrenâs nonword pronunciations are influenced by learning words. In Experiment 1, children pronounced nonwords before and after learning words sharing orthographic rimes with the nonwords. These rimes varied in spelling-to-sound consistency and regularity. Childrenâs nonword pronunciations were more sensitive to consistency and regularity after instruction than before. Experiment 2 expanded upon Experiment 1 by modifying the instruction to highlight regularity and consistency in rime unit neighborhoods and by including both younger (M age = 7.6) and older (M age = 9.92) participants. After instruction, Experiment 2 participants demonstrated greater sensitivity to rime unit consistency and regularity than Experiment 1 participants. In both experiments, the children, especially the younger participants, made more adultlike pronunciations after instruction than before. We conclude that learning words varying in consistency and regularity increased the childrenâs sensitivity to these properties
The SAMI Galaxy Survey: Global stellar populations on the size-mass plane
We present an analysis of the global stellar populations of galaxies in the
SAMI Galaxy Survey. Our sample consists of 1319 galaxies spanning four orders
of magnitude in stellar mass and includes all morphologies and environments. We
derive luminosity-weighted, single stellar population equivalent stellar ages,
metallicities and alpha enhancements from spectra integrated within one
effective radius apertures. Variations in galaxy size explain the majority of
the scatter in the age--mass and metallicity--mass relations. Stellar
populations vary systematically in the plane of galaxy size and stellar mass,
such that galaxies with high stellar surface mass density are older, more
metal-rich and alpha-enhanced than less dense galaxies. Galaxies with high
surface mass densities have a very narrow range of metallicities, however, at
fixed mass, the spread in metallicity increases substantially with increasing
galaxy size (decreasing density). We identify residual correlations with
morphology and environment. At fixed mass and size, galaxies with late-type
morphologies, small bulges and low Sersic n are younger than early-type, high
n, high bulge-to-total galaxies. Age and metallicity both show small residual
correlations with environment; at fixed mass and size, galaxies in denser
environments or more massive halos are older and somewhat more metal rich than
those in less dense environments. We connect these trends to evolutionary
tracks within the size--mass plane.Comment: 25 pages, 18 figures, MNRAS in press Corrected typo in author lis
The SAMI Galaxy Survey: Revising the Fraction of Slow Rotators in IFS Galaxy Surveys
The fraction of galaxies supported by internal rotation compared to galaxies
stabilized by internal pressure provides a strong constraint on galaxy
formation models. In integral field spectroscopy surveys, this fraction is
biased because survey instruments typically only trace the inner parts of the
most massive galaxies. We present aperture corrections for the two most widely
used stellar kinematic quantities and . Our
demonstration involves integral field data from the SAMI Galaxy Survey and the
ATLAS Survey. We find a tight relation for both and
when measured in different apertures that can be used as a linear
transformation as a function of radius, i.e., a first-order aperture
correction. We find that and radial growth curves are
well approximated by second order polynomials. By only fitting the inner
profile (0.5), we successfully recover the profile out to one
if a constraint between the linear and quadratic parameter in the
fit is applied. However, the aperture corrections for and
derived by extrapolating the profiles perform as well as applying
a first-order correction. With our aperture-corrected
measurements, we find that the fraction of slow rotating galaxies increases
with stellar mass. For galaxies with 11, the fraction
of slow rotators is percent, but is underestimated if galaxies
without coverage beyond one are not included in the sample
( percent). With measurements out to the largest aperture radius
the slow rotator fraction is similar as compared to using aperture corrected
values ( percent). Thus, aperture effects can significantly bias
stellar kinematic IFS studies, but this bias can now be removed with the method
outlined here.Comment: Accepted for Publication in the Monthly Notices of the Royal
Astronomical Society. 16 pages and 11 figures. The key figures of the paper
are: 1, 4, 9, and 1
The SAMI Galaxy Survey: gravitational potential and surface density drive stellar populations -- I. early-type galaxies
The well-established correlations between the mass of a galaxy and the
properties of its stars are considered evidence for mass driving the evolution
of the stellar population. However, for early-type galaxies (ETGs), we find
that color and stellar metallicity [Z/H] correlate more strongly with
gravitational potential than with mass , whereas stellar population
age correlates best with surface density . Specifically, for our sample
of 625 ETGs with integral-field spectroscopy from the SAMI Galaxy Survey,
compared to correlations with mass, the color--, [Z/H]--, and
age-- relations show both smaller scatter and less residual trend with
galaxy size. For the star formation duration proxy [/Fe], we find
comparable results for trends with and , with both being
significantly stronger than the [/Fe]- relation. In determining the
strength of a trend, we analyze both the overall scatter, and the observational
uncertainty on the parameters, in order to compare the intrinsic scatter in
each correlation. These results lead us to the following inferences and
interpretations: (1) the color-- diagram is a more precise tool for
determining the developmental stage of the stellar population than the
conventional color--mass diagram; and (2) gravitational potential is the
primary regulator of global stellar metallicity, via its relation to the gas
escape velocity. Furthermore, we propose the following two mechanisms for the
age and [/Fe] relations with : (a) the age-- and
[/Fe]-- correlations arise as results of compactness driven
quenching mechanisms; and/or (b) as fossil records of the
relation in their disk-dominated progenitors.Comment: 9 pages, 4 figures, 1 table Accepted to Ap
The GALEX Arecibo SDSS Survey. I. Gas Fraction Scaling Relations of Massive Galaxies and First Data Release
We introduce the GALEX Arecibo SDSS Survey (GASS), an on-going large program
that is gathering high quality HI-line spectra using the Arecibo radio
telescope for an unbiased sample of ~1000 galaxies with stellar masses greater
than 10^10 Msun and redshifts 0.025<z<0.05, selected from the SDSS
spectroscopic and GALEX imaging surveys. The galaxies are observed until
detected or until a low gas mass fraction limit (1.5-5%) is reached. This paper
presents the first Data Release, consisting of ~20% of the final GASS sample.
We use this data set to explore the main scaling relations of HI gas fraction
with galaxy structure and NUV-r colour. A large fraction (~60%) of the galaxies
in our sample are detected in HI. We find that the atomic gas fraction
decreases strongly with stellar mass, stellar surface mass density and NUV-r
colour, but is only weakly correlated with galaxy bulge-to-disk ratio (as
measured by the concentration index of the r-band light). We also find that the
fraction of galaxies with significant (more than a few percent) HI decreases
sharply above a characteristic stellar surface mass density of 10^8.5 Msun
kpc^-2. The fraction of gas-rich galaxies decreases much more smoothly with
stellar mass. One of the key goals of GASS is to identify and quantify the
incidence of galaxies that are transitioning between the blue, star-forming
cloud and the red sequence of passively-evolving galaxies. Likely transition
candidates can be identified as outliers from the mean scaling relations
between gas fraction and other galaxy properties. [abridged]Comment: 25 pages, 12 figures. Accepted for publication in MNRAS. Version with
high resolution figures available at
http://www.mpa-garching.mpg.de/GASS/pubs.ph
Pauli Diagonal Channels Constant on Axes
We define and study the properties of channels which are analogous to unital
qubit channels in several ways. A full treatment can be given only when the
dimension d is a prime power, in which case each of the (d+1) mutually unbiased
bases (MUB) defines an axis. Along each axis the channel looks like a
depolarizing channel, but the degree of depolarization depends on the axis.
When d is not a prime power, some of our results still hold, particularly in
the case of channels with one symmetry axis. We describe the convex structure
of this class of channels and the subclass of entanglement breaking channels.
We find new bound entangled states for d = 3.
For these channels, we show that the multiplicativity conjecture for maximal
output p-norm holds for p=2. We also find channels with behavior not exhibited
by unital qubit channels, including two pairs of orthogonal bases with equal
output entropy in the absence of symmetry. This provides new numerical evidence
for the additivity of minimal output entropy
The SAMI Galaxy Survey: A Range in S0 Properties Indicating Multiple Formation Pathways
It has been proposed that S0 galaxies are either fading spirals or the result
of galaxy mergers. The relative contribution of each pathway, and the
environments in which they occur remains unknown. Here we investigate stellar
and gas kinematics of 219 S0s in the SAMI Survey to look for signs of multiple
formation pathways occurring across the full range of environments. We identify
a large range of rotational support in their stellar kinematics, which
correspond to ranges in their physical structure. We find that
pressure-supported S0s with below 0.5 tend to be more compact and
feature misaligned stellar and gas components, suggesting an external origin
for their gas. We postulate that these S0s are consistent with being formed
through a merger process. Meanwhile, comparisons of ellipticity, stellar mass
and S\'ersic index distributions with spiral galaxies shows that the
rotationally supported S0s with above 0.5 are more consistent with
a faded spiral origin. In addition, a simulated merger pathway involving a
compact elliptical and gas-rich satellite results in an S0 that lies within the
pressure-supported group. We conclude that two S0 formation pathways are
active, with mergers dominating in isolated galaxies and small groups, and the
faded spiral pathway being most prominent in large groups ().Comment: 14 pages, 12 figures, accepted for publication in MNRA
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