2,831 research outputs found
Calculation of the Thomas-Ehrman shift in F and O(p,p) cross section with the Gamow shell model
The F nucleus is situated at the proton drip-line and is unbound by
proton emission by only about 500 keV. Continuum coupling is then prominent in
this nucleus. Added to that, its low-lying spectrum consists of narrow proton
resonances as well. It is then a very good candidate to study nuclear structure
and reactions at proton drip-line. The low-lying spectrum and scattering
proton-proton cross section of F have then been calculated with the
coupled-channel Gamow shell model framework for that matter using an effective
Hamiltonian. Experimental data are very well reproduced, as well as in its
mirror nucleus N. Isospin-symmetry breaking generated by the Coulomb
interaction and continuum coupling explicitly appears in our calculations. In
particular, the different continuum couplings in F and N
involving partial waves allow to explain the different ordering of
low-lying states in their spectrum.Comment: 7 pages, 2 figures, accepted for publication in Phys. Rev. C.
(Letters
Online Data Stream Learning and Classification with Limited Labels
Mining data streams such as Internet traffic andnetwork security is complex. Due to the difficulty of storage, datastreams analytics need to be done in one scan. This limits thetime to observe stream feature and hence, further complicatesthe data mining processes. Traditional supervised data miningwith batch training natural is not suitable to mine data streams.This paper proposes an algorithm for online data streamclassification and learning with limited labels using selective selftrainingsemi-supervised classification. The experimental resultsshow it is able to achieve up to 99.6% average accuracy for 10%labeled data and 98.6% average accuracy for 1% labeled data. Itcan classify up to 34K instances per second
Transition Density and Pressure at the Inner Edge of Neutron Star Crusts
Using the nuclear symmetry energy that has been recently constrained by the
isospin diffusion data in intermediate-energy heavy ion collisions, we have
studied the transition density and pressure at the inner edge of neutron star
crusts, and they are found to be 0.040 fm
fm and 0.01 MeV/fm MeV/fm,
respectively, in both the dynamical and thermodynamical approaches. We have
also found that the widely used parabolic approximation to the equation of
state of asymmetric nuclear matter gives significantly higher values of
core-crust transition density and pressure, especially for stiff symmetry
energies. With these newly determined transition density and pressure, we have
obtained an improved relation between the mass and radius of neutron stars.Comment: 7 pages, 3 figures, proceeding of "The International Workshop on
Nuclear Dynamics in Heavy-Ion Reactions and the Symmetry Energy (IWND2009)
Online peer-to-peer traffic identification based on complex events processing of traffic event signatures
Peer-to-Peer (P2P) applications are bandwidth-heavy and lead to network congestion. The masquerading nature of P2P traffic makes conventional methods of its identification futile. In order to manage and control P2P traffic efficiently preferably in the network, it is necessary to identify such traffic online and accurately. This paper proposes a technique for online P2P identification based on traffic events signatures. The experimental results show that it is able to identify P2P traffic on the fly with an accuracy of 97.7%, precision of 98% and recall of 99.2%
Pressure dependence of the charge-density-wave gap in rare-earth tri-tellurides
We investigate the pressure dependence of the optical properties of CeTe,
which exhibits an incommensurate charge-density-wave (CDW) state already at 300
K. Our data are collected in the mid-infrared spectral range at room
temperature and at pressures between 0 and 9 GPa. The energy for the single
particle excitation across the CDW gap decreases upon increasing the applied
pressure, similarly to the chemical pressure by rare-earth substitution. The
broadening of the bands upon lattice compression removes the perfect nesting
condition of the Fermi surface and therefore diminishes the impact of the CDW
transition on the electronic properties of Te.Comment: 5 pages, 4 figure
Z topology and superconductivity from symmetry lowering of a 3D Dirac Metal AuPb
3D Dirac semi-metals (DSMs) are materials that have massless Dirac electrons
and exhibit exotic physical properties It has been suggested that structurally
distorting a DSM can create a Topological Insulator (TI), but this has not yet
been experimentally verified. Furthermore, quasiparticle excitations known as
Majorana Fermions have been theoretically proposed to exist in materials that
exhibit superconductivity and topological surface states. Here we show that the
cubic Laves phase AuPb has a bulk Dirac cone above 100 K that gaps out upon
cooling at a structural phase transition to create a topologically non trivial
phase that superconducts below 1.2 K. The nontrivial Z = -1 invariant in
the low temperature phase indicates that AuPb in its superconducting state
must have topological surface states. These characteristics make AuPb a
unique platform for studying the transition between bulk Dirac electrons and
topological surface states as well as studying the interaction of
superconductivity with topological surface states
An evolved disk surrounding the massive main sequence star MWC 297?
We present the results of the interferometric observations of the
circumstellar disk surrounding MWC 297 in the continuum at 230 GHz (1.3 mm) and
in the (J=2-1) rotational transitions of CO,CO and CO
using the Submillimeter Array. At a distance of 250 pc, MWC 297 is one of the
closest, young massive stars (M 10 M) to us. Compact
continuum emission is detected towards MWC 297 from which we estimate a disk
mass (gas+dust) of 0.07 M and a disk radius of 80 AU. Our
result demonstrates that circumstellar disks can survive around massive stars
well into their main sequence phase even after they have become optically
visible. Complementing our observations with the data compiled from the
literature, we find the submm dust opacity index to be between 0.1 and
0.3. If the emission is optically thin, the low value of indicates the
presence of relatively large grains in the disk, possibly because of grain
growth. We do not detect any CO emission associated with the continuum source.
We argue that the CO emission from the disk is likely optically thin, in
which case, we derive an upper limit to the gas mass which implies significant
depletion of molecular gas in the disk. The mass of this disk and the
evolutionary trends observed are similar to those found for intermediate mass
Herbig Ae stars and low mass T Tauri stars.Comment: 4 pages, 3 Figures, accepted for publication in ApJ
Suppression of decoherence by bath ordering
The dynamics of two coupled spins-1/2 coupled to a spin-bath is studied as an
extended model of the Tessieri-Wilkie Hamiltonian \cite{TWmodel}. The pair of
spins served as an open subsystem were prepared in one of the Bell states and
the bath consisted of some spins-1/2 is in a thermal equilibrium state from the
very beginning. It is found that with the increasing the coupling strength of
the bath spins, the bath forms a resonant antiferromagnetic order. The
polarization correlation between the two spins of the subsystem and the
concurrence are recovered in some extent to the isolated subsystem. This
suppression of the subsystem decoherence may be used to control the quantum
devices in practical applications.Comment: 32 pages, Chinese Physics (accepted
Evidence for coupling between collective state and phonons in two-dimensional charge-density-wave systems
We report on a Raman scattering investigation of the charge-density-wave
(CDW), quasi two-dimensional rare-earth tri-tellurides Te (= La, Ce,
Pr, Nd, Sm, Gd and Dy) at ambient pressure, and of LaTe and CeTe under
externally applied pressure. The observed phonon peaks can be ascribed to the
Raman active modes for both the undistorted as well as the distorted lattice in
the CDW state by means of a first principles calculation. The latter also
predicts the Kohn anomaly in the phonon dispersion, driving the CDW transition.
The integrated intensity of the two most prominent modes scales as a
characteristic power of the CDW-gap amplitude upon compressing the lattice,
which provides clear evidence for the tight coupling between the CDW condensate
and the vibrational modes
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