1,469 research outputs found
Detection of Major River Bed Changes in the River Ebro (north-eastern Spain)
Detection of major river bed changes in River Ebro (northeastern Spain
Enhancements to the GW space-time method
We describe the following new features which significantly enhance the power
of the recently developed real-space imaginary-time GW scheme (Rieger et al.,
Comp. Phys. Commun. 117, 211 (1999)) for the calculation of self-energies and
related quantities of solids: (i) to fit the smoothly decaying time/energy
tails of the dynamically screened Coulomb interaction and other quantities to
model functions, treating only the remaining time/energy region close to zero
numerically and performing the Fourier transformation from time to energy and
vice versa by a combination of analytic integration of the tails and
Gauss-Legendre quadrature of the remaining part and (ii) to accelerate the
convergence of the band sum in the calculation of the Green's function by
replacing higher unoccupied eigenstates by free electron states (plane waves).
These improvements make the calculation of larger systems (surfaces, clusters,
defects etc.) accessible.Comment: 10 pages, 6 figure
Coherence and synchronization in diode-laser arrays with delayed global coupling
The dynamics of a semiconductor-laser array whose individual elements are
coupled in a global way through an external mirror is numerically analysed. A
coherent in-phase solution is seen to be preferred by the system at
intermediate values of the feedback coupling strength. At low values of this
parameter, a strong amplification of the spontaneous emission noise is
observed. A tendency towards chaos synchronization is also observed at large
values of the feedback strength.Comment: 8 pages, LaTeX, 6 PS figures, to appear in International Journal of
Bifurcation and Chao
Zero-lag long-range synchronization via dynamical relaying
We show that simultaneous synchronization between two delay-coupled
oscillators can be achieved by relaying the dynamics via a third mediating
element, which surprisingly lags behind the synchronized outer elements. The
zero-lag synchronization thus obtained is robust over a considerable parameter
range. We substantiate our claims with experimental and numerical evidence of
these synchronization solutions in a chain of three coupled semiconductor
lasers with long inter-element coupling delays. The generality of the mechanism
is validated in a neuronal model with the same coupling architecture. Thus, our
results show that synchronized dynamical states can occur over long distances
through relaying, without restriction by the amount of delay.Comment: 10 pages, 4 figure
Estudio del inicio y la finalización de la dentición permanente en un grupo de escolares de una población catalana
Este estudio pretende observar la erupción de la dentición permanente en niños y niñas residentes en una población de la provincia de Barcelona. La muestra se estudió en cuanto al sexo, la edad y los primeros y segundos molares erupcionados, encontrando que la primera pieza en aparecer es el primer molar a partir de los 5,33 años de edad, y de la misma forma, el segundo molar permanente es el que cierra todo el proceso eruptivo. Se adjuntan tablas para complementar la secuencia eruptiva
Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback
The dynamics of power distribution between longitudinal modes of a multimode
semiconductor laser subjected to external optical feedback is experimentally
analyzed in the low-frequency fluctuation regime. Power dropouts in the total
light intensity are invariably accompanied by sudden activations of several
longitudinal modes. These activations are seen not to be simultaneous to the
dropouts, but to occur after them. The phenomenon is statistically analysed in
a systematic way, and the corresponding delay is estimated.Comment: 3 pages, 4 figures, revte
Probing molecular arrangements of the organic semiconductor 2,7-Dioctyl[1]benzothieno[3,2- b][1]benzothiophene thin film at the interface by UV Resonant Raman scattering
Raman spectroscopy was employed to investigate nanometric thick films of the organic semiconductor 2,7-Dioctyl[1]benzothieno[3,2-b][1]benzothiophene, following a comprehensive vibrational characterization of the compound condensed phases at various excitation wavelengths. UV Raman excitation enabled the characterization of the thin films, revealing that the molecular orientation at the film/air interface is characterized by a different organization and/or a high degree of disorder compared to the bulk phase. The low penetration depth of the UV Raman excitation allows for the retrieval of this information, unlike the XRD data
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