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ERP to chess stimuli reveal expert-novice differences in the amplitudes of N2 and P3 components
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2013 Society for Psychophysiological Research.ERP experiments were conducted to analyze the underlying neural events when chess players make simple judgments of a board position. Fourteen expert players and 14 age-matched novices viewed, for each of four tasks, 128 unique positions on a mini (4 × 4) chess board each presented for 0.5 s. The tasks were to respond: (a) if white king was in check, (b) if black knight was present, (c) if white king was not in check, and (d) if no black knight was present. Experts showed an enhanced N2 with check targets and a larger P3 with knight targets, relative to novices. Expert-novice differences in posterior N2 began as early as 240 ms on check-related searches. Results were consistent with the view that prolonged N2 components reflect matching of current perceptual input to memory, and thus are sensitive to experts' superior pattern recognition and memory retrieval of chunks
Angular Power Spectrum of the Microwave Background Anisotropy seen by the COBE Differential Microwave Radiometer
The angular power spectrum estimator developed by Peebles (1973) and Hauser &
Peebles (1973) has been modified and applied to the 2 year maps produced by the
COBE DMR. The power spectrum of the real sky has been compared to the power
spectra of a large number of simulated random skies produced with noise equal
to the observed noise and primordial density fluctuation power spectra of power
law form, with . Within the limited range of spatial scales
covered by the COBE DMR, corresponding to spherical harmonic indices 3 \leq
\ell \lsim 30, the best fitting value of the spectral index is with the Harrison-Zeldovich value approximately
0.5 below the best fit. For 3 \leq \ell \lsim 19, the best fit is . Comparing the COBE DMR at small to
the at from degree scale anisotropy experiments
gives a smaller range of acceptable spectral indices which includes .Comment: 22 pages of LaTex using aaspp.sty and epsf.sty with appended
Postscript figures, COBE Preprint 94-0
ISOCAM spectro-imaging of the H2 rotational lines in the supernova remnant IC443
We report spectro-imaging observations of the bright western ridge of the
supernova remnant IC 443 obtained with the ISOCAM circular variable filter
(CVF) on board the Infrared Space Observatory (ISO). This ridge corresponds to
a location where the interaction between the blast wave of the supernova and
ambient molecular gas is amongst the strongest. The CVF data show that the 5 to
14 micron spectrum is dominated by the pure rotational lines of molecular
hydrogen (v = 0--0, S(2) to S(8) transitions). At all positions along the
ridge, the H2 rotational lines are very strong with typical line fluxes of
10^{-4} to 10^{-3} erg/sec/cm2/sr. We compare the data to a new time-dependent
shock model; the rotational line fluxes in IC 443 are reproduced within factors
of 2 for evolutionary times between 1,000 and 2,000 years with a shock velocity
of 30 km/sec and a pre-shock density of 10^4 /cm3.Comment: To appear in Astronomy and Astrophysic
Random copying in space
Random copying is a simple model for population dynamics in the absence of
selection, and has been applied to both biological and cultural evolution. In
this work, we investigate the effect that spatial structure has on the
dynamics. We focus in particular on how a measure of the diversity in the
population changes over time. We show that even when the vast majority of a
population's history may be well-described by a spatially-unstructured model,
spatial structure may nevertheless affect the expected level of diversity seen
at a local scale. We demonstrate this phenomenon explicitly by examining the
random copying process on small-world networks, and use our results to comment
on the use of simple random-copying models in an empirical context.Comment: 26 pages, 11 figures. Based on invited talk at AHRC CECD Conference
on "Cultural Evolution in Spatially Structured Populations" at UCL, September
2010. To appear in ACS - Advances in Complex System
Specsim: The MIRI Medium Resolution Spectrometer Simulator
MIRI, the Mid-InfraRed Instrument, is one of four instruments being built for
the James Webb Space Telescope, and is developed jointly between an
EuropeanConsortium and the US. In this paper we present a software data
simulator for one of MIRI's four instruments: the Integral Field Unit (IFU)
Medium Resolution Spectrometer (MIRI-MRS), the first mid-infrared IFU
spectrograph, and one of the first IFUs to be used in a space mission. To give
the MIRI community a preview of the properties of the MIRI-MRS data products
before the telescope is operational, the Specsim tool has been developed to
model, in software, the operation of the spectrometer. Specsim generates
synthetic data frames approximating those which will be taken by the instrument
in orbit. The program models astronomical sources and generates detector frames
using the predicted and measured optical properties of the telescope and MIRI.
These frames can then be used to illustrate and inform a range of operational
activities, including data calibration strategies and the development and
testing of the data reduction software for the MIRI-MRS. Specsim will serve as
a means of communication between the many consortium members by providing a way
to easily illustrate the performance of the spectrometer under different
circumstances, tolerances of components and design scenarios.Comment: 8 pages, 5 figures; A high resolution version is available at
http://www.roe.ac.uk/~npfl/Publications/lgw+06.ps.gz (Changed URL of high-res
version
Spectroscopy of Na<sup>+</sup>·Rg and transport coefficients of Na<sup>+</sup> in Rg (Rg=He-Rn)
High-level ab initio calculations are used to obtain accurate potential energy curves for Na+·Kr, Na+·Xe, and Na+·Rn. These data are used to calculate spectroscopic parameters for these three species, and the data for the whole Na+·Rg series (Rg=He-Rn) are compared. Potentials for the whole series are then used to calculate both mobilities and diffusion coefficients for Na+ moving through a bath of each of the six rare gases, under conditions that match previous experimental determinations. Different available potentials and experimental data are then statistically compared. It is concluded that the present potentials are very accurate. The potential and other data for Na+·Rn appear to be the first such reported
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C, N and noble gases in different pH and grain size fractions of pre-solar diamonds from Boriskino chondrite
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On the variations of the elemental composition of the P3 component in presolar diamonds
Analysis of noble gas element variations in the P3 component of presolar diamonds indicates that a special mechanism of element fractionation is required to explain the variations
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