3,876 research outputs found
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
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 IâII and half of those in deeper laminae). Surprisingly, although the dynorphin precursor preprodynorphin (PPD) was only present in 4â7% of VGLUT2 boutons in laminae IâIV, 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
Entanglement Cost of Three-Level Antisymmetric States
We show that the entanglement cost of the three-dimensional antisymmetric
states is one ebit.Comment: 8page
Dust properties in the cold and hot gas phases of the ATLAS3D early-type galaxies as revealed by AKARI
The properties of the dust in the cold and hot gas phases of early-type
galaxies (ETGs) are key to understand ETG evolution. We thus conducted a
systematic study of the dust in a large sample of local ETGs, focusing on
relations between the dust and the molecular, atomic, and X-ray gas of the
galaxies, as well as their environment. We estimated the dust temperatures and
masses of the 260 ETGs from the ATLAS3D survey, using fits to their spectral
energy distributions primarily constructed from AKARI measurements. We also
used literature measurements of the cold (CO and HI) and X-ray gas phases. Our
ETGs show no correlation between their dust and stellar masses, suggesting
inefficient dust production by stars and/or dust destruction in X-ray gas. The
global dust-to-gas mass ratios of ETGs are generally lower than those of
late-type galaxies, likely due to dust-poor HI envelopes in ETGs. They are also
higher in Virgo Cluster ETGs than in group and field ETGs, but the same ratios
measured in the central parts of the galaxies only are independent of galaxy
environment. Slow-rotating ETGs have systematically lower dust masses than
fast-rotating ETGs. The dust masses and X-ray luminosities are correlated in
fast-rotating ETGs, whose star formation rates are also correlated with the
X-ray luminosities. The correlation between dust and X-rays in fast-rotating
ETGs appears to be caused by residual star formation, while slow-rotating ETGs
are likely well evolved, and thus exhausting their dust. These results appear
consistent with the postulated evolution of ETGs, whereby fast-rotating ETGs
form by mergers of late-type galaxies and associated bulge growth, while
slow-rotating ETGs form by (dry) mergers of fast-rotating ETGs. Central cold
dense gas appears to be resilient against ram pressure stripping, suggesting
that Virgo Cluster ETGs may not suffer strong related star formation
suppression.Comment: 18 pages, 7 figures, accepted for publication in A&
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
New BPS Solitons in 2+1 Dimensional Noncommutative CP^1 Model
Investigating the solitons in the non-commutative model, we have
found a new set of BPS solitons which does not have counterparts in the
commutative model.Comment: 8 pages, LaTeX2e, references added, improvements to discussions,
Version to be published in JHE
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
Preprotachykinin A (PPTA) is expressed by a distinct population of excitatory neurons in the mouse superficial spinal dorsal horn including cells that respond to noxious and pruritic stimuli
The superficial dorsal horn, which is the main target for nociceptive and pruritoceptive primary afferents, contains a high density of excitatory interneurons. Our understanding of their roles in somatosensory processing has been restricted by the difficulty of distinguishing functional populations among these cells. We recently defined three non-overlapping populations among the excitatory neurons, based on the expression of neurotensin, neurokinin B (NKB) and gastrin-releasing peptide (GRP). Here we identify and characterise another population: neurons that express the tachykinin peptide substance P. We show with immunocytochemistry that its precursor protein (preprotachykinin A, PPTA) can be detected in ~14% of lamina I-II neurons, and these are concentrated in the outer part of lamina II. Over 80% of the PPTA-positive cells lack the transcription factor Pax2 (which determines an inhibitory phenotype), and these account for ~15% of the excitatory neurons in this region. They are different from the neurotensin, NKB or GRP neurons, although many of them contain somatostatin, which is widely expressed among superficial dorsal horn excitatory interneurons. We show that many of these cells respond to noxious thermal and mechanical stimuli, and to intradermal injection of pruritogens. Finally, we demonstrate that these cells can also be identified in a knock-in Cre mouse line (Tac1Cre), although our findings suggest that there is an additional population of neurons that transiently express PPTA. This population of substance P-expressing excitatory neurons is likely to play an important role in transmission of signals that are perceived as pain and itch
- âŚ