5,817 research outputs found
Quantum steering ellipsoids, extremal physical states and monogamy
A Corrigendum for this article has been published in 2015 New J. Phys. 17 019501Any two-qubit state can be faithfully represented by a steering ellipsoid inside the Bloch sphere, but not every ellipsoid inside the Bloch sphere corresponds to a two-qubit state. We give necessary and sufficient conditions for when the geometric data describe a physical state and investigate maximal volume ellipsoids lying on the physical-unphysical boundary. We derive monogamy relations for steering that are strictly stronger than the Coffman-Kundu- Wootters (CKW) inequality for monogamy of concurrence. The CKW result is thus found to follow from the simple perspective of steering ellipsoid geometry. Remarkably, we can also use steering ellipsoids to derive non-trivial results in classical Euclidean geometry, extending Eulers inequality for the circumradius and inradius of a triangle.The EPSRC and the ARC Centre of Excellence grant no. CE110001027. DJ is funded by the Royal
Society. TR would like to thank the Leverhulme Trust. SJ acknowledges EPSRC grant EP/
K022512/1
MLL5 expression as a biomarker for DNA hypermethylation and sensitivity to epigenetic therapy
Impact of birth weight and gender on early postnatal hypothalamic energy balance regulatory gene expression in the young lamb
Peer reviewedPreprin
IC 4406: a radio-infrared view
IC 4406 is a large (about 100'' x 30'') southern bipolar planetary nebula,
composed of two elongated lobes extending from a bright central region, where
there is evidence for the presence of a large torus of gas and dust. We show
new observations of this source performed with IRAC (Spitzer Space Telescope)
and the Australia Telescope Compact Array. The radio maps show that the flux
from the ionized gas is concentrated in the bright central region and
originates in a clumpy structure previously observed in H_alpha, while in the
infrared images filaments and clumps can be seen in the extended nebular
envelope, the central region showing toroidal emission. Modeling of the
infrared emission leads to the conclusion that several dust components are
present in the nebula.Comment: 22 pages, 7 figures, accepted for publication in The Astrophysical
Journal; v.2 has changes in both figures and content; preprint forma
Understanding Perceptual Judgment in Autism Spectrum Disorder Using the Drift Diffusion Model
Objective: Two-alternative forced-choice tasks are widely used to gain insight into specific areas of enhancement or impairment in individuals with autism spectrum disorder (ASD). Data arising from these tasks have been used to support myriad theories regarding the integrity, or otherwise, of particular brain areas or cognitive processes in ASD. The drift diffusion model (DDM) provides an account of the underlying processes which give rise to accuracy and reaction time (RT) distributions, and parameterizes these processes in terms which have direct psychological interpretation. Importantly, the DDM provides further insight into the origin of potential group differences in task performance. Here, for the first time, we used the DDM to investigate perceptual decision making in ASD. Method: Adults with (N = 25) and without ASD (N = 32) performed an orientation discrimination task. A drift diffusion model was applied to the full RT distributions. Results: Participants with ASD responded more slowly than controls, the groups did not differ in accuracy. Modeled parameters indicated that: (a) participants with ASD were more cautious than controls (wider boundary separation); (b) nondecision time was increased in ASD; and (c) the quality of evidence extracted from the stimulus (drift rate) did not vary between groups. Conclusions: Taking the behavioral data in isolation would suggest reduced perceptual sensitivity in ASD. However, DDM results indicated that despite response slowing, there was no evidence of differential perceptual sensitivity between participants with and without ASD. Future use of the DDM in investigations of perception and cognition in ASD is highly recommended. (PsycINFO Database Recor
A diffusion model decomposition of orientation discrimination in children with Autism Spectrum Disorder
Children with and without ASD performed an orientation discrimination task, in which the difficulty of the discrimination was equated across individuals. Behavioural results showed that subjects with ASD were slower in making a decision. A computational decomposition of data was performed and modelled parameters indicated that: (i) participants with ASD adopted a more conservative response criterion and (ii) motor response did not differ between groups. Our results confirm that differences in reaction times (RTs) and/or accuracy between participants with and without ASD in orientation discrimination may be related to differences in response conservativeness rather than in stimulus discriminability, in line with data previously reported from adults (Pirrone, Dickinson, Gomez, Stafford & Milne, 2017). This result has important implications for studies that have claimed impairments/enhancements in ASD on the basis of differences in RTs and/or accuracy alone
L-functions with large analytic rank and abelian varieties with large algebraic rank over function fields
The goal of this paper is to explain how a simple but apparently new fact of
linear algebra together with the cohomological interpretation of L-functions
allows one to produce many examples of L-functions over function fields
vanishing to high order at the center point of their functional equation. The
main application is that for every prime p and every integer g>0 there are
absolutely simple abelian varieties of dimension g over Fp(t) for which the BSD
conjecture holds and which have arbitrarily large rank.Comment: To appear in Inventiones Mathematica
Two-dimensional soliton cellular automaton of deautonomized Toda-type
A deautonomized version of the two-dimensional Toda lattice equation is
presented. Its ultra-discrete analogue and soliton solutions are also
discussed.Comment: 11 pages, LaTeX fil
A high-resolution radio survey of the Vela supernova remnant
This paper presents a high-resolution radio continuum (843 MHz) survey of the
Vela supernova remnant. The contrast between the structures in the central
pulsar-powered nebula of the remnant and the synchrotron radiation shell allows
the remnant to be identified morphologically as a member of the composite
class. The data are the first of a composite remnant at spatial scales
comparable with those available for the Cygnus Loop and the Crab Nebula, and
make possible a comparison of radio, optical and soft X-ray emission from the
resolved shell filaments. The survey, made with the Molonglo Observatory
Synthesis Telescope, covers an area of 50 square degrees at a resolution of
43'' x 60'', while imaging structures on scales up to 30'.Comment: 18 pages, 7 jpg figures (version with ps figures at
http://astro.berkeley.edu/~dbock/papers/); AJ, in pres
Exciton energy transfer in nanotube bundles
Photoluminescence is commonly used to identify the electronic structure of
individual nanotubes. But, nanotubes naturally occur in bundles. Thus, we
investigate photoluminescence of nanotube bundles. We show that their complex
spectra are simply explained by exciton energy transfer between adjacent tubes,
whereby excitation of large gap tubes induces emission from smaller gap ones
via Forster interaction between excitons. The consequent relaxation rate is
faster than non-radiative recombination, leading to enhanced photoluminescence
of acceptor tubes. This fingerprints bundles with different compositions and
opens opportunities to optimize them for opto-electronics.Comment: 5 pages, 5 figure
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