Identification of arches in 2D granular packings

We identify arches in a bed of granular disks generated by a molecular dynamic-type simulation. We use the history of the deposition of the particles to identify the supporting contacts of each particle. Then, arches are defined as sets of mutually stable disks. Different packings generated through tapping are analyzed. The possibility of identifying arches from the static structure of a deposited bed, without any information on the history of the deposition, is discussed.Comment: 12 pages, 7 figure

Variational analysis of self-focusing of intense ultrashort pulses in gases

By using perturbation theory we derive an expression for the electrical field of a Gaussian laser pulse propagating in a gas medium. This expression is used as a trial solution in a variational method to get quasianalytical solutions for the width, intensity and self-focusing distance of ultrashort pulse. The approximation gives an improved agreement with results of numerical simulations for a broad range of values of the input power of the pulse than previous analytical results available in the literature.Comment: 19 pages, 8 figure

Analytical operator solution of master equations describing phase-sensitive processes

We present a method of solving master equations which may describe, in their most general form, phase sensitive processes such as decay and amplification. We make use of the superoperator technique.Comment: 10 pages, LaTex, 3 figures, accepted for publication in International Journal of Modern Physics

Estudio clínico morfológico de la deformación del borde dorsal del cuello en caballos cruzados de carruaje en Sevilla y Córdoba (Andalucía, España)

The aim of this study was to a clinical, morphological of deformation dorsal neck edge on in horse of carriage in Seville and Cordoba, Andalusia, Spain. We studied a total of 110 horses. Clinical examination was performed and morphological considering weight and body condition was measured cervical perimeter. Deformation of the dorsal edge of the neck in all cases studied was evident. Morphological study to consider the deformation of the dorsal edge of the neck taking into account the ridge of the neck (score of 1 to 5) evidenced: for score 0: 33.6%; score 1: 51.8%; Rankings 2: 10%; Rated: 4.5 % for score 4 and 5 no horse was observed in these categories. The average diameter of the neck was 92.54cm, the average neck length was 92.46 cm and the weight was 3.92kg. The statistical result of the degree of deformation of the neck with the weight was 0.465 and the correlation between the degrees of deformation with weight was 0.652. The degree of correlation between neck circumference and body condition was 0.634. In conclusion deformation dorsal edge of the collar in horses used for carriage crossed in Cordoba and Seville, Spain, was observed a prevalence of 66%.Se plantea como objetivo un estudio clínico morfológico de la deformación del borde dorsal del cuello en caballos de carruaje en Sevilla y Córdoba, Andalucía-España. Fueron estudiados un total de 110 caballos. Se practicó un examen clínico y morfológico considerando condición corporal peso y se midió el perímetro cervical. El estudio morfológico para considerar la deformación del borde dorsal del cuello tomando en cuenta la cresta de la nuca (puntuación del 1 al 5) evidencio: para la puntuación 0: 33.6%; puntuación 1: 51.8%; puntuación 2: 10%; puntuación: 4.5%, para la puntuación 4 y 5 ningún caballo se observó en estas categorías. El promedio del diámetro del cuello fue de 92.54cm, el promedio de la longitud del cuello fue de 92.46 cm y el peso fue de 3.92Kg. Los resultados estadísticos del grado de deformación del cuello con el peso fue de 0.465 y la correlación entre el grado de deformación con el peso fue de 0.652. El grado de correlación entre el perímetro cervical y la condición corporal fue de 0.634. En conclusión se observó la deformación del borde dorsal del cuello en caballos cruzados empleados para carruajes en Córdoba y Sevilla, España, con una prevalencia puntual de 66%

Gaussian tripartite entanglement in the simultaneous measurement of position and momentum

In this work, we prove the generation of genuine tripartite continuous-variable entanglement in the unitary dynamics of the simultaneous measurement process of position and momentum observables raised by Arthurs and Kelly, considering a measurement configuration where the system under examination is a rotated, displaced, and squeezed vacuum state. Under these assumptions, the measurement configuration is entirely described by a Gaussian state. Then, through the positive partial transpose criterion (PPT), we certify genuine tripartite entanglement by testing the non-separability of the three $\left(1~ \text{vs}~2\right)$-mode bipartitions of the system. This process allows us to classify the qualitative properties of the entanglement in the category of fully inseparable Gaussian states according to the classification exposed in [Giedke et al., \href{https://link.aps.org/doi/10.1103/PhysRevA.64.052303}{Phys. Rev. A \textbf{64}, 052303 (2001)}]. Besides, we determine the quantitative entanglement properties of the system using the residual tripartite R{\'e}nyi-2 entanglement as a quantifier measure.Comment: 15 pages, 8 figure

Dynamics of zonal flow-like structures in the edge of the TJ-II stellarator

The dynamics of fluctuating electric field structures in the edge of the TJ-II stellarator, that display zonal flow-like traits, is studied. These structures have been shown to be global and affect particle transport dynamically [J.A. Alonso et al., Nucl. Fus. 52 063010 (2012)]. In this article we discuss possible drive (Reynolds stress) and damping (Neoclassical viscosity, geodesic transfer) mechanisms for the associated ExB velocity. We show that: (a) while the observed turbulence-driven forces can provide the necessary perpendicular acceleration, a causal relation could not be firmly established, possibly because of the locality of the Reynolds stress measurements, (b) the calculated neoclassical viscosity and damping times are comparable to the observed zonal flow relaxation times, and (c) although an accompanying density modulation is observed to be associated to the zonal flow, it is not consistent with the excitation of pressure side-bands, like those present in geodesic acoustic oscillations, caused by the compression of the ExB flow field