3,630 research outputs found
Electro-spinon in one-dimensional Mott insulator
The low-energy dynamical optical response of dimerized and undimerized spin
liquid states in a one-dimensional charge transfer Mott insulator is
theoretically studied. An exact analysis is given for the low-energy asymptotic
behavior using conformal field theory for the undimerized state. In the
dimerized state, the infrared absorption due to the bound state of two
solitons, i.e, the breather mode, is predicted with an accurate estimate for
its oscillator strength, offering a way to detect experimentally the excited
singlet state. Effects of external magnetic fields are also discussed.Comment: 5 pages, 2 figures, some typos are correcte
Entanglement Cost of Three-Level Antisymmetric States
We show that the entanglement cost of the three-dimensional antisymmetric
states is one ebit.Comment: 8page
Projection neurons in lamina III of the rat spinal cord are selectively innervated by local dynorphin-containing excitatory neurons
Large projection neurons in lamina III of the rat spinal cord that express the neurokinin 1 receptor are densely innervated by peptidergic primary afferent nociceptors and more sparsely by low-threshold myelinated afferents. However, we know little about their input from other glutamatergic neurons. Here we show that these cells receive numerous contacts from nonprimary boutons that express the vesicular glutamate transporter 2 (VGLUT2), and form asymmetrical synapses on their dendrites and cell bodies. These synapses are significantly smaller than those formed by peptidergic afferents, but provide a substantial proportion of the glutamatergic synapses that the cells receive (over a third of those in laminae I–II and half of those in deeper laminae). Surprisingly, although the dynorphin precursor preprodynorphin (PPD) was only present in 4–7% of VGLUT2 boutons in laminae I–IV, it was found in 58% of the VGLUT2 boutons that contacted these cells. This indicates a highly selective targeting of the lamina III projection cells by glutamatergic neurons that express PPD, and these are likely to correspond to local neurons (interneurons and possibly projection cells). Since many PPD-expressing dorsal horn neurons respond to noxious stimulation, this suggests that the lamina III projection cells receive powerful monosynaptic and polysynaptic nociceptive input. Excitatory interneurons in the dorsal horn have been shown to possess IA currents, which limit their excitability and can underlie a form of activity-dependent intrinsic plasticity. It is therefore likely that polysynaptic inputs to the lamina III projection neurons are recruited during the development of chronic pain states
Non-local Matching Condition and Scale-invariant Spectrum in Bouncing Cosmology
In cosmological scenarios such as the pre-big bang scenario or the ekpyrotic
scenario, a matching condition between the metric perturbations in the pre-big
bang phase and those in the post big-bang phase is often assumed. Various
matching conditions have been considered in the literature. Nevertheless
obtaining a scale invariant CMB spectrum via a concrete mechanism remains
impossible. In this paper, we examine this problem from the point of view of
local causality. We begin with introducing the notion of local causality and
explain how it constrains the form of the matching condition. We then prove a
no-go theorem: independent of the details of the matching condition, a scale
invariant spectrum is impossible as long as the local causality condition is
satisfied. In our framework, it is easy to show that a violation of local
causality around the bounce is needed in order to give a scale invariant
spectrum. We study a specific scenario of this possibility by considering a
nonlocal effective theory inspired by noncommutative geometry around the bounce
and show that a scale invariant spectrum is possible. Moreover we demonstrate
that the magnitude of the spectrum is compatible with observations if the
bounce is assumed to occur at an energy scale which is a few orders of
magnitude below the Planckian energy scale.Comment: 15 pages, 2 figures; v3: clarifications added, changes in references,
version to appear in PR
Twisted K-theory and finite-dimensional approximation
We provide a finite-dimensional model of the twisted K-group twisted by any
degree three integral cohomology class of a CW complex. One key to the model is
Furuta's generalized vector bundle, and the other is a finite-dimensional
approximation of Fredholm operators.Comment: 26 pages, LaTeX 2e, Xypic; main theorem improve
On non commutative sinh-Gordon Equation
We give a noncommutative extension of sinh-Gordon equation. We generalize a
linear system and Lax representation of the sinh-Gordon equation in
noncommutative space. This generalization gives a noncommutative version of the
sinh-Gordon equation with extra constraints, which can be expressed as global
conserved currents.Comment: 7 Page
Incoherent Noise and Quantum Information Processing
Incoherence in the controlled Hamiltonian is an important limitation on the
precision of coherent control in quantum information processing. Incoherence
can typically be modelled as a distribution of unitary processes arising from
slowly varying experimental parameters. We show how it introduces artifacts in
quantum process tomography and we explain how the resulting estimate of the
superoperator may not be completely positive. We then go on to attack the
inverse problem of extracting an effective distribution of unitaries that
characterizes the incoherence via a perturbation theory analysis of the
superoperator eigenvalue spectra.Comment: 15 pages, 5 figures, replaced with future JCP published versio
Spin wave dispersion softening in the ferromagnetic Kondo lattice model for manganites
Spin dynamics is calculated in the ferromagnetic (FM) state of the
generalized Kondo lattice model taking into account strong on-site correlations
between e_g electrons and antiferromagnetic (AFM) exchange among t_{2g} spins.
Our study suggests that competing FM double-exchange and AFM super-exchange
interaction lead to a rather nontrivial spin-wave spectrum. While spin
excitations have a conventional Dq^2 spectrum in the long-wavelength limit,
there is a strong deviation from the spin-wave spectrum of the isotropic
Heisenberg model close to the zone boundary. The relevance of our results to
the experimental data are discussed.Comment: 6 RevTex pages, 3 embedded PostScript figure
An Endogenous Murine Leukemia Viral Genome Contaminant in a Commercial RT-PCR Kit is Amplified Using Standard Primers for XMRV
During pilot studies to investigate the presence of viral RNA of xenotropic murine leukemia virus (MLV)-related virus (XMRV) infection in sera from chronic fatigue syndrome (CFS) patients in Japan, a positive band was frequently detected at the expected product size in negative control samples when detecting a partial gag region of XMRV using a one-step RT-PCR kit. We suspected that the kit itself might have been contaminated with small traces of endogenous MLV genome or XMRV and attempted to evaluate the quality of the kit in two independent laboratories. We purchased four one-step RT-PCR kits from Invitrogen, TaKaRa, Promega and QIAGEN in Japan. To amplify the partial gag gene of XMRV or other MLV-related viruses, primer sets (419F and 1154R, and GAG-I-F and GAG-I-R) which have been widely used in XMRV studies were employed. The nucleotide sequences of the amplicons were determined and compared with deposited sequences of a polytropic endogenous MLV (PmERV), XMRV and endogenous MLV-related viruses derived from CFS patients. We found that the enzyme mixtures of the one-step RT-PCR kit from Invitrogen were contaminated with RNA derived from PmERV. The nucleotide sequence of a partial gag region of the contaminant amplified by RT-PCR was nearly identical (99.4% identity) to a PmERV on chromosome 7 and highly similar (96.9 to 97.6%) to recently identified MLV-like viruses derived from CFS patients. We also determined the nucleotide sequence of a partial env region of the contaminant and found that it was almost identical (99.6%) to the PmERV. In the investigation of XMRV infection in patients of CFS and prostate cancer, researchers should prudently evaluate the test kits for the presence of endogenous MLV as well as XMRV genomes prior to PCR and RT-PCR tests
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