87,328 research outputs found
Grayâs revised Reinforcement Sensitivity Theory in relation to Attention-Deficit/Hyperactivity and Tourette-like behaviors in the general population
Attention-Deficit/Hyperactivity Disorder (ADHD) and Tourette Syndrome (TS) present as distinct conditions clinically; however, they show comorbidity and inhibitory control deficits have been proposed to underlie both. The role of reinforcement sensitivity in ADHD has been studied previously, but no study has addressed this in relation to TS-like behaviors in the general population. The present study examined these associations within the remit of the revised Reinforcement Sensitivity Theory (rRST). One hundred and thirty-eight participants completed psychometric measures of the rRST, and self-report checklists for ADHD- and TS-like behaviors
New measure of electron correlation
We propose to quantify the "correlation" inherent in a many-electron (or
many-fermion) wavefunction by comparing it to the unique uncorrelated state
that has the same single-particle density operator as it does.Comment: Final version to appear in PR
Second-order electronic correlation effects in a one-dimensional metal
The Pariser-Parr-Pople (PPP) model of a single-band one-dimensional (1D)
metal is studied at the Hartree-Fock level, and by using the second-order
perturbation theory of the electronic correlation. The PPP model provides an
extension of the Hubbard model by properly accounting for the long-range
character of the electron-electron repulsion. Both finite and infinite version
of the 1D-metal model are considered within the PPP and Hubbard approximations.
Calculated are the second-order electronic-correlation corrections to the total
energy, and to the electronic-energy bands. Our results for the PPP model of 1D
metal show qualitative similarity to the coupled-cluster results for the 3D
electron-gas model. The picture of the 1D-metal model that emerges from the
present study provides a support for the hypothesis that the normal metallic
state of the 1D metal is different from the ground state.Comment: 21 pages, 16 figures; v2: small correction in title, added 3
references, extended and reformulated a few paragraphs (detailed information
at the end of .tex file); added color to figure
Short range correlations in relativistic nuclear matter models
Short range correlations are introduced using unitary correlation method in a
relativistic approach to the equation of state of the infinite nuclear matter
in the framework of the Hartree-Fock approximation. It is shown that the
correlations give rise to an extra node in the ground-state wave-function in
the nucleons, contrary to what happens in non-relativistic calculations with a
hard core. The effect of the correlations in the ground state properties of the
nuclear matter and neutron matter is studied. The nucleon effective mass and
equation of state (EOS) are very sensitive to short range correlations. In
particular, if the pion contact term is neglected a softening of the EOS is
predicted. Correlations have also an important effect on the neutron matter EOS
which presents no binding but only a very shallow minimum contrary to the
Walecka model.Comment: 8pages, 4 figure
Aspects of short range correlations in a relativistic model
In the present work short range correlations are introduced for the first
time in a relativistic approach to the equation of state of the infinite
nuclear matter in the framework of the Hartree-Fock approximation using an
effective Hamiltonian derived from the Walecka model. The
unitary correlation method is used to introduce short range correlations. The
effect of the correlations in the ground state properties of the nuclear matter
is discussed.Comment: 7 pages, 3 figure
Contextualized Word Representations for Reading Comprehension
Reading a document and extracting an answer to a question about its content
has attracted substantial attention recently. While most work has focused on
the interaction between the question and the document, in this work we evaluate
the importance of context when the question and document are processed
independently. We take a standard neural architecture for this task, and show
that by providing rich contextualized word representations from a large
pre-trained language model as well as allowing the model to choose between
context-dependent and context-independent word representations, we can obtain
dramatic improvements and reach performance comparable to state-of-the-art on
the competitive SQuAD dataset.Comment: 6 pages, 1 figure, NAACL 201
4-point effective actions in open and closed superstring theory
Recently the effective action for the 4-point functions in abelian open
superstring theory has been derived, giving an explicit construction of the
bosonic and fermionic terms of this infinite series. In the present
work we generalize this result to the nonabelian case. We test our result, at
and order, with several existing versions for these
terms, finding agreement in most of the cases. We also apply these ideas to
derive the effective action for the 4-point functions of the NS-NS sector of
closed superstring theory, to all order in .Comment: 26 pages, 1 figure. To appear in JHE
Carbon in Spiral Galaxies from Hubble Space Telescope Spectroscopy
We present measurements of the gas-phase C/O abundance ratio in six H II
regions in the spiral galaxies M101 and NGC 2403, based on ultraviolet
spectroscopy using the Faint Object Spectrograph on the Hubble Space Telescope.
The C/O ratios increase systematically with O/H in both galaxies, from log C/O
approximately -0.8 at log O/H = -4.0 to log C/O approx. -0.1 at log O/H = -3.4.
C/N shows no correlation with O/H. The rate of increase of C/O is somewhat
uncertain because of uncertainty as to the appropriate UV reddening law, and
uncertainty in the metallicity dependence on grain depletions. However, the
trend of increasing C/O with O/H is clear, confirming and extending the trend
in C/O indicated previously from observations of irregular galaxies. Our data
indicate that the radial gradients in C/H across spiral galaxies are steeper
than the gradients in O/H. Comparing the data to chemical evolution models for
spiral galaxies shows that models in which the massive star yields do not vary
with metallicity predict radial C/O gradients that are much flatter than the
observed gradients. The most likely hypothesis at present is that stellar winds
in massive stars have an important effect on the yields and thus on the
evolution of carbon and oxygen abundances. C/O and N/O abundance ratios in the
outer disks of spirals determined to date are very similar to those in dwarf
irregular galaxies. This implies that the outer disks of spirals have average
stellar population ages much younger than the inner disks.Comment: 38 pages, 9 postscript figures, uses aaspp4.sty. Accepted for
publication in The Astrophysical Journa
To be or not to Be? - First Evidence for Neutrinoless Double Beta Decay
Double beta decay is indispensable to solve the question of the neutrino mass
matrix together with oscillation experiments. Recent analysis of the most
sensitive experiment since nine years - the HEIDELBERG-MOSCOW experiment in
Gran-Sasso - yields a first indication for the neutrinoless decay mode. This
result is the first evidence for lepton number violation and proves the
neutrino to be a Majorana particle. We give the present status of the analysis
in this report. It excludes several of the neutrino mass scenarios allowed from
present neutrino oscillation experiments - only degenerate scenarios and those
with inverse mass hierarchy survive. This result allows neutrinos to still play
an important role as dark matter in the Universe. To improve the accuracy of
the present result, considerably enlarged experiments are required, such as
GENIUS. A GENIUS Test Facility has been funded and will come into operation by
early 2003.Comment: 16 pages, latex, 10 figures, Talk was presented at International
Conference "Neutrinos and Implications for Physics Beyond the Standard
Model", Oct. 11-13, 2002, Stony Brook, USA, Proc. (2003) ed. by R. Shrock,
also see Home Page of Heidelberg Non-Accelerator Particle Physics Group:
http://www.mpi-hd.mpg.de/non_acc
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