2,149 research outputs found
Unveiling Palomar 2: The Most Obscure Globular Cluster in the Outer Halo
We present the first color-magnitude study for Palomar 2, a distant and
heavily obscured globular cluster near the Galactic anticenter. Our (V,V-I)
color-magnitude diagram (CMD), obtained with the UH8K camera at the CFHT,
reaches V(lim) = 24 and clearly shows the principal sequences of the cluster,
though with substantial overall foreground absorption and differential
reddening. The CMD morphology shows a well populated red horizontal branch with
a sparser extension to the blue, similar to clusters such as NGC 1261, 1851, or
6229 with metallicities near [Fe/H] = -1.3, placing it about 34 kpc
from the Galactic center. We use starcounts of the bright stars to measure the
core radius, half-mass radius, and central concentration of the cluster. Its
integrated luminosity is M_V = -7.9, making it clearly brighter and more
massive than most other clusters in the outer halo.Comment: 25 pages, aastex, with 8 postscript figures; accepted for publication
in AJ, September 1997. Also available by e-mail from
[email protected]. Please consult Harris directly for (big)
postscript files of Figures 1a,b (the images of the cluster
Inversion improves the recognition of facial expression in thatcherized images
The Thatcher illusion provides a compelling example of the face inversion effect. However, the marked effect of inversion in the Thatcher illusion contrasts to other studies that report only a small effect of inversion on the recognition of facial expressions. To address this discrepancy, we compared the effects of inversion and thatcherization on the recognition of facial expressions. We found that inversion of normal faces caused only a small reduction in the recognition of facial expressions. In contrast, local inversion of facial features in upright thatcherized faces resulted in a much larger reduction in the recognition of facial expressions. Paradoxically, inversion of thatcherized faces caused a relative increase in the recognition of facial expressions. Together, these results suggest that different processes explain the effects of inversion on the recognition of facial expressions and on the perception of the Thatcher illusion. The grotesque perception of thatcherized images is based on a more orientation-sensitive representation of the face. In contrast, the recognition of facial expression is dependent on a more orientation-insensitive representation. A similar pattern of results was evident when only the mouth or eye region was visible. These findings demonstrate that a key component of the Thatcher illusion is to be found in orientation-specific encoding of the features of the face
Constant net-time headway as key mechanism behind pedestrian flow dynamics
We show that keeping a constant lower limit on the net-time headway is the
key mechanism behind the dynamics of pedestrian streams. There is a large
variety in flow and speed as functions of density for empirical data of
pedestrian streams, obtained from studies in different countries. The net-time
headway however, stays approximately constant over all these different data
sets. By using this fact, we demonstrate how the underlying dynamics of
pedestrian crowds, naturally follows from local interactions. This means that
there is no need to come up with an arbitrary fit function (with arbitrary fit
parameters) as has traditionally been done. Further, by using not only the
average density values, but the variance as well, we show how the recently
reported stop-and-go waves [Helbing et al., Physical Review E, 75, 046109]
emerge when local density variations take values exceeding a certain maximum
global (average) density, which makes pedestrians stop.Comment: 7 pages, 7 figure
The tilt of mean sea level along the east coast of North America
The tilt of mean sea level along the North American east coast has been a subject of debate for many decades. Improvements in geoid and ocean circulation models, and GPS positioning of tide gauge benchmarks, provide an opportunity to produce new tilt estimates. Tilts estimated using tide gauge measurements referenced to high-resolution geoid models (the geodetic approach) and ocean circulation models (the ocean approach) are compared. The geodetic estimates are broadly similar, with tilts downward to the north through the Florida Straits and at Cape Hatteras. Estimates from the ocean approach show good agreement with the geodetic estimates, indicating a convergence of the two approaches and resolving the long standing debate as to the sign of the tilt. These tilts differ from those used by Yin and Goddard (2013) to support a link between changing ocean circulation and coastal sea level rise
The quick and the dead: when reaction beats intention
Everyday behaviour involves a trade-off between planned actions and reaction to environmental events.Evidence from neurophysiology, neurology and functional brain imaging suggests different neural bases for the control of different movement types. Here we develop a behavioural paradigm to test movement dynamics for intentional versus reaction movements and provide evidence for a ‘reactive advantage’ in movement execution, whereby the same action is executed faster in reaction to an opponent. We placed pairs of participants in competition with each other to make a series of button presses. Within subject analysis of movement times revealed a 10 per cent benefit for reactive actions. This was maintained when opponents performed dissimilar actions, and when participants competed against a computer, suggesting that the effect is not related to facilitation produced by action observation. Rather, faster ballistic movements may be a general property of reactive motor control, potentially providing a useful means of promoting survival
Fairness-Aware Ranking in Search & Recommendation Systems with Application to LinkedIn Talent Search
We present a framework for quantifying and mitigating algorithmic bias in
mechanisms designed for ranking individuals, typically used as part of
web-scale search and recommendation systems. We first propose complementary
measures to quantify bias with respect to protected attributes such as gender
and age. We then present algorithms for computing fairness-aware re-ranking of
results. For a given search or recommendation task, our algorithms seek to
achieve a desired distribution of top ranked results with respect to one or
more protected attributes. We show that such a framework can be tailored to
achieve fairness criteria such as equality of opportunity and demographic
parity depending on the choice of the desired distribution. We evaluate the
proposed algorithms via extensive simulations over different parameter choices,
and study the effect of fairness-aware ranking on both bias and utility
measures. We finally present the online A/B testing results from applying our
framework towards representative ranking in LinkedIn Talent Search, and discuss
the lessons learned in practice. Our approach resulted in tremendous
improvement in the fairness metrics (nearly three fold increase in the number
of search queries with representative results) without affecting the business
metrics, which paved the way for deployment to 100% of LinkedIn Recruiter users
worldwide. Ours is the first large-scale deployed framework for ensuring
fairness in the hiring domain, with the potential positive impact for more than
630M LinkedIn members.Comment: This paper has been accepted for publication at ACM KDD 201
Cooling of Quark Stars in the Color Superconductive Phase: Effect of Photons from Glueball decay
The cooling history of a quark star in the color superconductive phase is
investigated. Here we specifically focus on the 2-flavour color (2SC) phase
where novel process of photon generation via glueball (GLB) decay have been
already investigated (Ouyed & Sannino 2001). The picture we present here can in
principle be generalized to quark stars entering a superconductive phase where
similar photon generation mechanisms are at play. As much as 10^{45}-10^{47}
erg of energy is provided by the GLB decay in the 2SC phase. The generated
photons slowly diffuse out of the quark star keeping it hot and radiating as a
black-body (with possibly a Wien spectrum in gamma-rays) for millions of years.
We discuss hot radio-quiet isolated neutron stars in our picture (such as RX
J185635-3754 and RX J0720.4-3125) and argue that their nearly blackbody spectra
(with a few broad features) and their remarkably tiny hydrogen atmosphere are
indications that these might be quark stars in the color superconductive phase
where some sort of photon generation mechanism (reminiscent of the GLB decay)
has taken place. Fits to observed data of cooling compact stars favor models
with superconductive gaps of Delta_2SC = 15-35 MeV and densities
rho_2SC=(2.5-3.0)rho_N (rho_N being the nuclear matter saturation density) for
quark matter in the 2SC phase. If correct, our model combined with more
observations of isolated compact stars could provide vital information to
studies of quark matter and its exotic phases.Comment: 7 journal pages, 4 figures, accepted for publication in MNRAS (more
discussions on photon cooling versus neutrino cooling before and after
pairing of quarks
Foreword and Supplemental Information, Swine Day
It is with great pleasure that we present the 2016 Swine Industry Day Report of Progress. This report contains updates and summaries of applied and basic research conducted at Kansas State University during the past year. We hope that the information will be of benefit as we attempt to meet the needs of the Kansas swine industry
Swine Day 2015 Supplements
It is with great pleasure that we present the 2015 Swine Industry Day Report of Progress. This report contains updates and summaries of applied and basic research conducted at Kansas State University during the past year. We hope that the information will be of benefit as we attempt to meet the needs of the Kansas swine industry
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