On the dust environment of Main-Belt Comet 313P/Gibbs

We present observations carried out using the 10.4 m Gran Telescopio Canarias and an interpretative model of the dust environment of activated asteroid 313P/Gibbs. We discuss three different models relating to different values of the dust parameters, i.e, dust loss rate, maximum and minimum sizes of particles, power index of the size distribution, and emission pattern. The best model corresponds with an isotropic emission of particles which started on August 1st. The size of grains were in the range of $0.1-2000$ $\mu$m, with velocities for 100 $\mu$m particles between $0.4-1.9$ m$~$s$^{-1}$, with a dust production rate in the range of $0.2-0.8$ kg$~$s$^{-1}$. The dust tails' brightness and morphology are best interpreted in terms of a model of sustained and low dust emission driven by water-ice sublimation, spanning since 2014 August 1st, and triggered by a short impulsive event. This event produced an emission of small particles of about 0.1 $\mu$m with velocities of $\sim$4 m$~$s$^{-1}$. From our model we deduce that the activity of this Main-Belt Comet continued for, at least, four months, since activation.Comment: 14 pages, 4 figures, 2 tables. Accepted for publication in The Astrophysical Journa

Dust loss from activated asteroid P/2015 X6

We present observations and dust tail models of activated asteroid P/2015 X6 from deep imaging data acquired at the 10.4m Gran Telescopio Canarias (GTC) from mid-December 2015 to late January 2016. The results of the modeling indicate that the asteroid has undergone a sustained dust loss over a two-month or longer period. The dust parameters, derived from multidimensional fits of the available images, are compatible with either ice sublimation or rotational instability processes. An impulsive event, as it could be associated to an impact with another body, is less likely. A power-law distribution of particles, with minimum and maximum radius of 1 $\mu$m and 1 cm, and power index of --3.3 is found to be consistent with the observations. Depending on the ejection velocity model adopted, the particle velocities are found in the 0.3 to 10 m s$^{-1}$ range. The activation time was between 18-26 days before discovery. The total ejected mass from that time to the most recent observation is in the range 5-9$\times$10$^6$ kg. No dust features giving indication of past activity earlier than the activation time have been observed.Comment: Accepted by ApJ, May 15th 201

Generations of orthogonal surface coordinates

Two generation methods were developed for three dimensional flows where the computational domain normal to the surface is small. With this restriction the coordinate system requires orthogonality only at the body surface. The first method uses the orthogonal condition in finite-difference form to determine the surface coordinates with the metric coefficients and curvature of the coordinate lines calculated numerically. The second method obtains analytical expressions for the metric coefficients and for the curvature of the coordinate lines

On the transmission of light through a single rectangular hole

In this Letter we show that a single rectangular hole exhibits transmission resonances that appear near the cutoff wavelength of the hole waveguide. For light polarized with the electric field pointing along the short axis, it is shown that the normalized-to-area transmittance at resonance is proportional to the ratio between the long and short sides, and to the dielectric constant inside the hole. Importantly, this resonant transmission process is accompanied by a huge enhancement of the electric field at both entrance and exit interfaces of the hole. These findings open the possibility of using rectangular holes for spectroscopic purposes or for exploring non-linear effects.Comment: Submitted to PRL on Feb. 9th, 200

On the logarithmic comparison theorem for integrable logarithmic connections

Let $X$ be a complex analytic manifold, $D\subset X$ a free divisor with jacobian ideal of linear type (e.g. a locally quasi-homogeneous free divisor), $j: U=X-D \to X$ the corresponding open inclusion, $E$ an integrable logarithmic connection with respect to $D$ and $L$ the local system of the horizontal sections of $E$ on $U$. In this paper we prove that the canonical morphisms between the logarithmic de Rham complex of $E(kD)$ and $R j_* L$ (resp. the logarithmic de Rham complex of $E(-kD)$ and $j_!L$) are isomorphisms in the derived category of sheaves of complex vector spaces for $k\gg 0$ (locally on $X$)Comment: Terminology has changed: "linear jacobian type" instead of "commutative differential type"); no Koszul hypothesis is needed in theorem (2.1.1); minor changes. To appear in Proc. London Math. So

The design of an automated verification of redundant systems

Handbook describes design processes, presents design considerations and techniques, gives tutorial material on implementation and methodology, shows design aids, illustrates use of design aids and application samples, and identifies general practices to be adhered to or avoided

Energy partition and segregation for an intruder in a vibrated granular system under gravity

The difference of temperatures between an impurity and the surrounding gas in an open vibrated granular system is studied. It is shown that, in spite of the high inhomogeneity of the state, the temperature ratio remains constant in the bulk of the system. The lack of energy equipartition is associated to the change of sign of the pressure diffusion coefficient for the impurity at certain values of the parameters of the system, leading to a segregation criterium. The theoretical predictions are consistent with previous experimental results, and also in agreement with molecular dynamics simulation results reported in this paper.Comment: To appear in Phys. Rev. Let

Modified Renormalization Strategy for Sandpile Models

Following the Renormalization Group scheme recently developed by Pietronero {\it et al}, we introduce a simplifying strategy for the renormalization of the relaxation dynamics of sandpile models. In our scheme, five sub-cells at a generic scale $b$ form the renormalized cell at the next larger scale. Now the fixed point has a unique nonzero dynamical component that allows for a great simplification in the computation of the critical exponent $z$. The values obtained are in good agreement with both numerical and theoretical results previously reported.Comment: APS style, 9 pages and 3 figures. To be published in Phys. Rev.

Scattering of surface plasmons by one-dimensional periodic nanoindented surfaces

In this work, the scattering of surface plasmons by a finite periodic array of one-dimensional grooves is theoretically analyzed by means of a modal expansion technique. We have found that the geometrical parameters of the array can be properly tuned to achieve optimal performance of the structure either as a Bragg reflector or as a converter of surface plasmons into light. In this last case, the emitted light is collimated within a few degrees cone. Importantly, we also show that a small number of indentations in the array are sufficient to fully achieve its functional capabilities.Comment: 5 pages, 5 figures; changed sign convention in some definition