1,718 research outputs found
Hopf Map and Quantization on Sphere
Quantization of a system constrained to move on a sphere is considered by
taking a square root of the ``on sphere condition''. We arrive at the fibre
bundle structure of the Hopf map in the cases of and . This
leads to more geometrical understanding of monopole and instanton gauge
structures that emerge in the course of quantization.Comment: 9 pages, LaTeX2e, uses amsmath.st
Inequivalent Quantization in the Skyrme Model
Quantum mechanics on manifolds is not unique and in general infinite number
of inequivalent quantizations can be considered. They are specified by the
induced spin and the induced gauge structures on the manifold. The
configuration space of collective mode in the Skyrme model can be identified
with and thus the quantization is not unique. This leads to the
different predictions for the physical observables.Comment: 16 pages, LaTeX2
COCO_TS Dataset: Pixel-level Annotations Based on Weak Supervision for Scene Text Segmentation
The absence of large scale datasets with pixel-level supervisions is a
significant obstacle for the training of deep convolutional networks for scene
text segmentation. For this reason, synthetic data generation is normally
employed to enlarge the training dataset. Nonetheless, synthetic data cannot
reproduce the complexity and variability of natural images. In this paper, a
weakly supervised learning approach is used to reduce the shift between
training on real and synthetic data. Pixel-level supervisions for a text
detection dataset (i.e. where only bounding-box annotations are available) are
generated. In particular, the COCO-Text-Segmentation (COCO_TS) dataset, which
provides pixel-level supervisions for the COCO-Text dataset, is created and
released. The generated annotations are used to train a deep convolutional
neural network for semantic segmentation. Experiments show that the proposed
dataset can be used instead of synthetic data, allowing us to use only a
fraction of the training samples and significantly improving the performances
Lost equivalence of nonlinear sigma and models on noncommutative space
We show that the equivalence of nonlinear sigma and models which is
valid on the commutative space is broken on the noncommutative space. This
conclusion is arrived at through investigation of new BPS solitons that do not
exist in the commutative limit.Comment: 17 pages, LaTeX2
Berry Connections and Induced Gauge Fields in Quantum Mechanics on Sphere
Quantum mechanics on sphere is studied from the viewpoint that the
Berry's connection has to appear as a topological term in the effective action.
Furthermore we show that this term is the Chern-Simons term of gauge variables
that correspond to the extra degrees of freedom of the enlarged space.Comment: 12 pages, LaTeX2
Measurement of Single and Double Spin-Flip Probabilities in Inelastic Deuteron Scattering on 12C at 270 MeV
The deuteron single and double spin-flip probabilities, S1 and S2, have been
measured for the 12C(pol{d},pol{d}') reaction at Ed = 270 MeV for an excitation
energy range between 4 and 24 MeV and a scattering angular range between
Theta_lab = 2.5 and 7.5 deg. The extracted S1 exhibits characteristic values
depending on the structure of the excited state. The S2 is close to zero over
the measured excitation energy range. The SFP angular distribution data for the
2+ (4.44 MeV) and 1+ (12.71 MeV) states are well described by the microscopic
DWIA calculations
Developmental decrease in NMDA receptor desensitization associated with shift to synapse and interaction with postsynaptic density-95
NMDA receptors (NMDARs) play a crucial role in neuronal development, synaptic plasticity, and excitotoxicity; therefore, regulation of NMDAR function is important in both physiological and pathological conditions. Previous studies indicate that the NMDAR-mediated synaptic current decay rate increases during development because of a switch in receptor subunit composition, contributing to developmental changes in plasticity. To test whether NMDAR desensitization also changes during development, we recorded whole-cell NMDA-evoked currents in cultured rat hippocampal neurons. We found that glycine-independent desensitization of NMDARs decreases during development. This decrease was not dependent on a switch in subunit composition or differential receptor sensitivity to agonist-, Ca2+-, or Zn2+-induced increase in desensitization. Instead, several lines of evidence indicated that the developmental decrease in desensitization was tightly correlated with synaptic localization of the receptor, suggesting that association of NMDARs with proteins selectively expressed at synapses in mature neurons might account for developmental alterations in desensitization. Accordingly, we tested the role of interactions between PSD-95 (postsynaptic density-95) and NMDARs in regulating receptor desensitization. Overexpression of PSD-95 reduced NMDAR desensitization in immature neurons, whereas agents that interfere with synaptic targeting of PSD-95, or induce movement of NMDARs away from synapses and uncouple the receptor from PSD-95, increased NMDAR desensitization in mature neurons. We conclude that synaptic localization and association with PSD-95 increases stability of hippocampal neuronal NMDAR responses to sustained agonist exposure. Our results elucidate an additional mechanism for differentially regulating NMDAR function in neurons of different developmental stages or the response of subpopulations of NMDARs in a single neuron
Coulomb and nuclear breakup of a halo nucleus 11Be
Breakup reactions of the one-neutron halo nucleus 11Be on Pb and C targets at
about 70 MeV/u have been investigated by measuring the momentum vectors of the
incident 11Be, outgoing 10Be, and neutron in coincidence. The relative energy
spectra as well as the angular distributions of the 10Be+n center of mass have
been extracted for both targets. For the breakup on Pb target, the selection of
forward scattering angles is found to be effective to extract almost purely the
first-order E1 Coulomb breakup component, and to exclude the nuclear
contribution and higher-order Coulomb breakup components. This angle-selected
energy spectrum is thus used to deduce the spectroscopic factor for the
10Be(0+) 2s_1/2 configuration in 11Be which is found to be 0.72+-0.04 with
B(E1) up to Ex=4 MeV of 1.05+-0.06 e2fm2. The energy weighted E1 strength up to
Ex=4 MeV explains 70+-10% of the cluster sum rule, consistent with the obtained
spectroscopic factor. The non-energy weighted sum rule is used to extract the
root mean square distance of the halo neutron to be 5.77(16) fm, consistent
with previously known values. In the breakup with C target, we have observed
the excitations to the known unbound states in 11Be at Ex=1.78 MeV and 3.41
MeV. Angular distributions for these states show the diffraction pattern
characteristic of L=2 transitions, resulting in J^pi =(3/2,5/2)+ assignment for
these states. We finally find that even for the C target the E1 Coulomb direct
breakup mechanism becomes dominant at very forward angles.Comment: 14 pages, 7 figures, accepted for publication on Physical Review
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