9,740 research outputs found
A review of self-processing biases in cognition
When cues in the environment are associated with self (e.g., one’s own name, face, or coffee cup), these items trigger processing biases such as increased attentional focus, perceptual prioritization and memorial support. This paper reviews the existing literature on self-processing biases before introducing a series of studies that provide new insight into the influence of the self on cognition. In particular, the studies examine affective and memorial biases for self-relevant stimuli, and their flexible application in response to different task demands. We conclude that self-processing biases function to ensure that self-relevant information is attended to and preferentially processed because this is a perpetual goal of the self-system. However, contrary task-demands or priming can have an attenuating effect on their influence, speaking to the complexity and dynamism of the self-processing system in cognition
An empirical Bayesian analysis applied to the globular cluster pulsar population
We describe an empirical Bayesian approach to determine the most likely size
of an astronomical population of sources of which only a small subset are
observed above some limiting flux density threshold. The method is most
naturally applied to astronomical source populations at a common distance
(e.g.,stellar populations in globular clusters), and can be applied even to
populations where a survey detects no objects. The model allows for the
inclusion of physical parameters of the stellar population and the detection
process. As an example, we apply this method to the current sample of radio
pulsars in Galactic globular clusters. Using the sample of flux density limits
on pulsar surveys in 94 globular clusters published by Boyles et al., we
examine a large number of population models with different dependencies. We
find that models which include the globular cluster two-body encounter rate,
, are strongly favoured over models in which this is not a factor. The
optimal model is one in which the mean number of pulsars is proportional to
. This model agrees well with earlier work by Hui et al.
and provides strong support to the idea that the two-body encounter rate
directly impacts the number of neutron stars in a cluster. Our model predicts
that the total number of potentially observable globular cluster pulsars in the
Boyles et al. sample is 1070, where the uncertainties signify
the 95% confidence interval. Scaling this result to all Galactic globular
clusters, and to account for radio pulsar beaming, we estimate the total
population to be 2280.Comment: 8 pages, 6 figures, 3 tables, corrected a few minor formatting errors
which have also been submitted as an erratum to MNRA
The Formation of Population III Binaries from Cosmological Initial Conditions
Previous high resolution cosmological simulations predict the first stars to
appear in the early universe to be very massive and to form in isolation. Here
we discuss a cosmological simulation in which the central 50 solar mass clump
breaks up into two cores, having a mass ratio of two to one, with one fragment
collapsing to densities of 10^{-8} g/cc. The second fragment, at a distance of
800 astronomical units, is also optically thick to its own cooling radiation
from molecular hydrogen lines, but is still able to cool via collision-induced
emission. The two dense peaks will continue to accrete from the surrounding
cold gas reservoir over a period of 10^5 years and will likely form a binary
star system.Comment: Accepted by Science, first published online on July 9, 2009 in
Science Express. 16 pages, 4 figures, includes supporting online materia
The self-reference effect on memory in early childhood
The self-reference effect in memory is the advantage for information encoded about self, relative to other people. The early development of this effect was explored here using a concrete encoding paradigm. Trials comprised presentation of a self- or other-image paired with a concrete object. In Study 1, 4- to 6-year-old children (N = 53) were asked in each trial whether the child pictured would like the object. Recognition memory showed an advantage for self-paired objects. Study 2 (N = 55) replicated this finding in source memory. In Study 3 (N = 56), participants simply indicated object location. Again, recognition and source memory showed an advantage for self-paired items. These findings are discussed with reference to mechanisms that ensure information of potential self-relevance is reliably encoded
Microwave radiative transfer studies of precipitation
Since the deployment of the DMSP SSM/I microwave imagers in 1987, increased utilization of passive microwave radiometry throughout the 10 - 100 GHz spectrum has occurred for measurement of atmospheric constituents and terrestrial surfaces. Our efforts have focused on observations and analysis of the microwave radiative transfer behavior of precipitating clouds. We have focused particular attention on combining both aircraft and SSM/I radiometer imagery with ground-based multiparameter radar observations. As part of this and the past NASA contract, we have developed a multi-stream, polarized radiative transfer model which incorporates scattering. The model has the capability to be initialized with cloud model output or multiparameter radar products. This model provides the necessary 'link' between the passive microwave radiometer and active microwave radar observations. This unique arrangement has allowed the brightness temperatures (TB) to be compared against quantities such as rainfall, liquid/ice water paths, and the vertical structure of the cloud. Quantification of the amounts of ice and water in precipitating clouds is required for understanding of the global energy balance
Pulsar extinction
Radio emission from pulsars, attributed to an instability associated with the creation of electron-positron pairs from gamma rays was investigated. The condition for pair creation therefore lead to an extinction condition. The relevant physical processes were analyzed in the context of a mathematical model, according to which radiation originated at the polar caps and magnetic field lines changed from a closed configuration to an open configuration at the force balance or corotation radius
Optical radiation from the Crab pulsar
Possible mechanisms for producing the optical radiation from the Crab pulsar are proposed and discussed. There are severe difficulties in interpreting the radiation as being produced by an incoherent process, whether it be synchrotron radiation, inverse-Compton radiation or curvature radiation. It is proposed therefore that radiation in the optical part of the spectrum is coherent. In the polar cap model, a small bunch of electrons and positrons forms near each primary electron as a result of the pair-production cascade process. Ambient electric fields give rise to energy separation, as a result of which either the electrons or positrons will dominate the radiation from each bunch. The roll-off in the infrared is ascribed to synchrotron absorption by electrons and positrons located between the surface of the star and the force-balance radius. Various consequences of this model, which may be subjected to observational test, are discussed
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