3,306 research outputs found
Caucasian Infantsâ Attentional Orienting to Own- and Other-Race Faces
Infants show preferential attention toward faces and detect faces embedded within complex naturalistic scenes. Newborn infants are insensitive to race, but rapidly develop differential processing of own- and other-race faces. In the present study, we investigated the development of attentional orienting toward own- and other-race faces embedded within naturalistic scenes. Infants aged six-, nine- and twelve-months did not show differences in the speed of orienting to own- and other race faces, but other-race faces held infantsâ visual attention for longer. We also found a clear developmental progression in attentional capture and holding, with older infants orienting to faces faster and fixating them for longer. Results are interpreted within the context of the two-process model of face processing
Eye Movements and Behavioural Responses to Gaze-Contingent Expressive Faces in Typically Developing Infants and Infant Siblings
CELLO: A fast algorithm for Covariance Estimation
We present CELLO (Covariance Estimation and Learning through Likelihood Optimization), an algorithm for predicting the covariances of measurements based on any available informative features. This algorithm is intended to improve the accuracy and reliability of on-line state estimation by providing a principled way to extend the conventional fixed-covariance Gaussian measurement model. We show that in experiments, CELLO learns to predict measurement covariances that agree with empirical covariances obtained by manually annotating sensor regimes. We also show that using the learned covariances during filtering provides substantial quantitative improvement to the overall state estimate. © 2013 IEEE.United States. National Aeronautics and Space AdministrationSiemens Corporate ResearchUnited States. Office of Naval Research. Multidisciplinary University Research InitiativeMicro Autonomous Consortium Systems and Technolog
Hybrid Volitional Control of a Robotic Transtibial Prosthesis using a Phase Variable Impedance Controller
For robotic transtibial prosthesis control, the global kinematics of the
tibia can be used to monitor the progression of the gait cycle and command
smooth and continuous actuation. In this work, these global tibia kinematics
are used to define a phase variable impedance controller (PVIC), which is then
implemented as the nonvolitional base controller within a hybrid volitional
control framework (PVI-HVC). The gait progression estimation and biomechanic
performance of one able-bodied individual walking on a robotic ankle prosthesis
via a bypass adapter are compared for three control schemes: a passive
benchmark controller, PVIC, and PVI-HVC. The different actuation of each
controller had a direct effect on the global tibia kinematics, but the average
deviation between the estimated and ground truth gait percentage were 1.6%,
1.8%, and 2.1%, respectively, for each controller. Both PVIC and PVI-HVC
produced good agreement with able-bodied kinematic and kinetic references. As
designed, PVI-HVC results were similar to those of PVIC when the user used low
volitional intent, but yielded higher peak plantarflexion, peak torque, and
peak power when the user commanded high volitional input in late stance. This
additional torque and power also allowed the user to volitionally and
continuously achieve activities beyond level walking, such as ascending ramps,
avoiding obstacles, standing on tip-toes, and tapping the foot. In this way,
PVI-HVC offers the kinetic and kinematic performance of the PVIC during level
ground walking, along with the freedom to volitionally pursue alternative
activities.Comment: 7 pages, 7 figures, submitted to ICRA 202
The Sloan Digital Sky Survey Reverberation Mapping Project: Velocity Shifts of Quasar Emission Lines
Quasar emission lines are often shifted from the systemic velocity due to
various dynamical and radiative processes in the line-emitting region. The
level of these velocity shifts depends both on the line species and on quasar
properties. We study velocity shifts for the line peaks of various narrow and
broad quasar emission lines relative to systemic using a sample of 849 quasars
from the Sloan Digital Sky Survey Reverberation Mapping (SDSS-RM) project. The
coadded (from 32 epochs) spectra of individual quasars have sufficient
signal-to-noise ratio (SNR) to measure stellar absorption lines to provide
reliable systemic velocity estimates, as well as weak narrow emission lines.
The sample also covers a large dynamic range in quasar luminosity (~2 dex),
allowing us to explore potential luminosity dependence of the velocity shifts.
We derive average line peak velocity shifts as a function of quasar luminosity
for different lines, and quantify their intrinsic scatter. We further quantify
how well the peak velocity can be measured for various lines as a function of
continuum SNR, and demonstrate there is no systematic bias in the line peak
measurements when the spectral quality is degraded to as low as SNR~3 per SDSS
pixel. Based on the observed line shifts, we provide empirical guidelines on
redshift estimation from [OII]3728, [OIII]5008, [NeV]3426, MgII, CIII],
HeII1640, broad Hbeta, CIV, and SiIV, which are calibrated to provide unbiased
systemic redshifts in the mean, but with increasing intrinsic uncertainties of
46, 56, 119, 205, 233, 242, 400, 415, and 477 km/s, in addition to the
measurement uncertainties. These more realistic redshift uncertainties are
generally much larger than the formal uncertainties reported by the redshift
pipelines for spectroscopic quasar surveys, and demonstrate the infeasibility
of measuring quasar redshifts to better than ~200 km/s with only broad lines.Comment: matched to the published version; minor changes and conclusions
unchange
Observational limits on type 1 active galactic nucleus rate in COSMOS
We present black hole masses and accretion rates for 182 Type 1 active galactic nuclei (AGNs) in COSMOS.
We estimate masses using the scaling relations for the broad H ÎČ, Mg ii, and C iv emission lines in the
redshift ranges 0.16 < z < 0.88, 1 < z < 2.4, and 2.7 < z < 4.9. We estimate the accretion rate using an
Eddington ratio LI/L_(Edd) estimated from optical and X-ray data.We find that very few Type 1 AGNs accrete below
LI/L_(Edd) ⌠0.01, despite simulations of synthetic spectra which show that the survey is sensitive to such Type
1 AGNs. At lower accretion rates the broad-line region may become obscured, diluted, or nonexistent. We find
evidence that Type 1 AGNs at higher accretion rates have higher optical luminosities, as more of their emission
comes from the cool (optical) accretion disk with respect to shorter wavelengths. We measure a larger range
in accretion rate than previous works, suggesting that COSMOS is more efficient at finding low accretion rate
Type 1 AGNs. However, the measured range in accretion rate is still comparable to the intrinsic scatter from the
scaling relations, suggesting that Type 1 AGNs accrete at a narrow range of Eddington ratio, with LI/L_(Edd) ⌠0.1
Observational Limits on Type 1 AGN Accretion Rate in COSMOS
We present black hole masses and accretion rates for 182 Type 1 AGN in
COSMOS. We estimate masses using the scaling relations for the broad Hb, MgII,
and CIV emission lines in the redshift ranges 0.16<z<0.88, 1<z<2.4, and
2.7<z<4.9. We estimate the accretion rate using an Eddington ratio L_I/L_Edd
estimated from optical and X-ray data. We find that very few Type 1 AGN accrete
below L_I/L_Edd ~ 0.01, despite simulations of synthetic spectra which show
that the survey is sensitive to such Type 1 AGN. At lower accretion rates the
BLR may become obscured, diluted or nonexistent. We find evidence that Type 1
AGN at higher accretion rates have higher optical luminosities, as more of
their emission comes from the cool (optical) accretion disk with respect to
shorter wavelengths. We measure a larger range in accretion rate than previous
works, suggesting that COSMOS is more efficient at finding low accretion rate
Type 1 AGN. However the measured range in accretion rate is still comparable to
the intrinsic scatter from the scaling relations, suggesting that Type 1 AGN
accrete at a narrow range of Eddington ratio, with L_I/L_Edd ~ 0.1.Comment: Accepted for pulication in ApJ. 7 pages, 5 figures, table 1 available
on reques
Infants show pupil dilatory responses to happy and angry facial expressions
Facial expressions are one way in which infants and adults communicate emotion. Infants scan expressions similarly to adults, yet it remains unclear whether they are receptive to the affective information they convey. The current study investigates six-, nine- and twelve-month infantsâ (N = 146) pupillary responses to the six âbasicâ emotional expressions (happy, sad, surprise, fear, anger, and disgust). To do this we use dynamic stimuli and gaze-contingent eye-tracking to simulate brief interactive exchanges, alongside a static control condition. Infantsâ arousal responses were stronger for dynamic compared to static stimuli. And for dynamic stimuli we found that, compared to neutral, infants showed dilatory responses for happy and angry expressions only. Although previous work has shown infants can discriminate perceptually between facial expressions, our data suggest that sensitivity to the affective content of all six basic emotional expressions may not fully emerge until later in ontogeny
- âŠ