3,074 research outputs found
Z(3) Symmetric Dimensional Reduction of (2+1)D QCD
Here we present a candidate for a Z(3)-symmetric reduced action for the
description of the (2+1)D SU(3) gauge theoryComment: 2 pages, Statistical QCD pro
On cognition, structured sequence processing, and adaptive dynamical systems
Cognitive neuroscience approaches the brain as a cognitive system: a system that functionally is conceptualized in terms of information processing. We outline some aspects of this concept and consider a physical system to be an information processing device when a subclass of its physical states can be viewed as representational/cognitive and transitions between these can be conceptualized as a process operating on these states by implementing operations on the corresponding representational structures. We identify a generic and fundamental problem in cognition: sequentially organized structured processing. Structured sequence processing provides the brain, in an essential sense, with its processing logic. In an approach addressing this problem, we illustrate how to integrate levels of analysis within a framework of adaptive dynamical systems. We note that the dynamical system framework lends itself to a description of asynchronous event-driven devices, which is likely to be important in cognition because the brain appears to be an asynchronous processing system. We use the human language faculty and natural language processing as a concrete example through out
QCD with Adjoint Scalars in 2D: Properties in the Colourless Scalar Sector
We present a numerical study of an SU(3) gauged 2D model for adjoint scalar
fields, defined by dimensional reduction of pure gauge QCD in (2+1)D at high
temperature. In the symmetric phase of its global Z_2 symmetry, two colourless
boundstates, even and odd under Z_2, are identified. Their respective
contributions (poles) in correlation functions of local composite operators A_n
of degree n=2p and 2p+1 in the scalar fields (p=1,2) fulfill factorization. The
contributions of two particle states (cuts) are detected. Their size agrees
with estimates based on a meanfield-like decomposition of the p=2 operators
into polynomials in p=1 operators. No sizable signal in any A_n correlation can
be attributed to 1/n times a Debye screening length associated with n
elementary fields. These results are quantitatively consistent with the picture
of scalar ``matter'' fields confined within colourless boundstates whose
residual ``strong'' interactions are very weak.Comment: 27 pages, improved presentation of results and some references added,
as accepted by Nucl. Phys.
Field Tuning the G-Factor in InAs Nanowire Double Quantum Dots
We study the effects of magnetic and electric fields on the g-factors of
spins confined in a two-electron InAs nanowire double quantum dot. Spin
sensitive measurements are performed by monitoring the leakage current in the
Pauli blockade regime. Rotations of single spins are driven using
electric-dipole spin resonance. The g-factors are extracted from the spin
resonance condition as a function of the magnetic field direction, allowing
determination of the full g-tensor. Electric and magnetic field tuning can be
used to maximize the g-factor difference and in some cases altogether quench
the EDSR response, allowing selective single spin control.Comment: Related papers at http://pettagroup.princeton.ed
Literacy: A cultural influence on functional left-right differences in the inferior parietal cortex
The current understanding of hemispheric interaction is limited. Functional hemispheric specialization is likely to depend on both genetic and environmental factors. In the present study we investigated the importance of one factor, literacy, for the functional lateralization in the inferior parietal cortex in two independent samples of literate and illiterate subjects. The results show that the illiterate group are consistently more right-lateralized than their literate controls. In contrast, the two groups showed a similar degree of left-right differences in early speech-related regions of the superior temporal cortex. These results provide evidence suggesting that a cultural factor, literacy, influences the functional hemispheric balance in reading and verbal working memory-related regions. In a third sample, we investigated grey and white matter with voxel-based morphometry. The results showed differences between literacy groups in white matter intensities related to the mid-body region of the corpus callosum and the inferior parietal and parietotemporal regions (literate > illiterate). There were no corresponding differences in the grey matter. This suggests that the influence of literacy on brain structure related to reading and verbal working memory is affecting large-scale brain connectivity more than grey matter per se
Screening Masses in Dimensionally Reduced (2+1)D Gauge Theory
We discuss the screening masses and residue factorisation of the SU(3) (2+1)D
theory in the dimensional reduction formalism. The phase structure of the
reduced model is also investigated.Comment: 3 pages, Lattice 2001(gaugetheories
Radio frequency charge sensing in InAs nanowire double quantum dots
We demonstrate charge sensing of an InAs nanowire double quantum dot (DQD)
coupled to a radio frequency (rf) circuit. We measure the rf signal reflected
by the resonator using homodyne detection. Clear single dot and DQD behavior
are observed in the resonator response. rf-reflectometry allows measurements of
the DQD charge stability diagram in the few-electron regime even when the dc
current through the device is too small to be measured. For a signal-to-noise
ratio of one, we estimate a minimum charge detection time of 350 microseconds
at interdot charge transitions and 9 microseconds for charge transitions with
the leads.Comment: Related papers at http://pettagroup.princeton.ed
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