600 research outputs found
Two Distinct Electronic Contributions in the Fully Symmetric Raman Response of High Cuprates
We show by non resonant effect in HgBaCuO (Hg-1201)and by Zn
substitutions in YBaCuO (Y-123) compounds that the fully
symmetric Raman spectrum has two distinct electronic contributions. The
A response consists in the superconducting pair breaking peak at the
2 energy and a collective mode close to the magnetic resonance energy.
These experimental results reconcile the \textit{d-wave} model to the A
Raman response function in so far as a collective mode that is distinct from
the pair breaking peak is present in the A channel.Comment: 4 pages, 2 figure
New hos-based parameter estimation methods for speech recognition in noisy environments
The problem of recognition in noisy environments is addressed. Often, a recognition system is used in a noisy environment and there is no possibility of training it with noisy samples. Classical speech analysis techniques are based on second-order statistics and their performance dramatically decreases when noise is present in the signal under analysis. New methods based on higher order statistics (HOS) are applied in a recognition system and compared against the autocorrelation method. Cumulant-based methods show better performance than autocorrelation-based methods for low SNRPeer ReviewedPostprint (published version
K^+ production in baryon-baryon and heavy-ion collisions
Kaon production cross sections in nucleon-nucleon, nucleon-delta and
delta-delta interactions are studied in a boson exchange model. For the latter
two interactions, the exchanged pion can be on-mass shell, only contributions
due to a virtual pion are included via the Peierls method by taking into
account the finite delta width. With these cross sections and also those for
pion-baryon interactions, subthreshold kaon production from heavy ion
collisions is studied in the relativistic transport model.Comment: to appear in Phys. Rev.
SPH-based simulation of multi-material asteroid collisions
We give a brief introduction to smoothed particle hydrodynamics methods for
continuum mechanics. Specifically, we present our 3D SPH code to simulate and
analyze collisions of asteroids consisting of two types of material: basaltic
rock and ice. We consider effects like brittle failure, fragmentation, and
merging in different impact scenarios. After validating our code against
previously published results we present first collision results based on
measured values for the Weibull flaw distribution parameters of basalt.Comment: Accepted and to be published in Astronomical Note
Resonances in the one-dimensional Dirac equation in the presence of a point interaction and a constant electric field
We show that the energy spectrum of the one-dimensional Dirac equation in the
presence of a spatial confining point interaction exhibits a resonant behavior
when one includes a weak electric field. After solving the Dirac equation in
terms of parabolic cylinder functions and showing explicitly how the resonant
behavior depends on the sign and strength of the electric field, we derive an
approximate expression for the value of the resonance energy in terms of the
electric field and delta interaction strength.Comment: 9 pages. To appear in Physics Letters
- …