AGN dust tori at low and high luminosities

A cornerstone of AGN unification schemes is the presence of an optically and geometrically thick dust torus. It provides the obscuration to explain the difference between type 1 and type 2 AGN. We investigate the influence of the dust distribution on the Eddington limit of the torus. For smooth dust distributions, the Eddingtion limit on the dust alone is 5 orders of magnitudes below the limit for electron scattering in a fully ionized plasma, while a clumpy dust torus has an Eddington limit slightly larger than the classical one. We study the behaviour of a clumpy torus at low and high AGN luminosities. For low luminosities of the order of ~10^42 erg/s, the torus changes its characteristics and obscuration becomes insufficient. In the high luminosity regime, the clumpy torus can show a behaviour which is consistent with the "receding torus" picture. The derived luminosity-dependent fraction of type-2-objects agrees with recent observational results. Moreover, the luminosity-dependent covering factor in a clumpy torus may explain the presence of broad-line AGN with high column densities in X-rays.Comment: 5 pages, 0 figures; Accepted for publication in MNRA

Poisson-Lie T-duality: Open Strings and D-branes

Global issues of the Poisson-Lie T-duality are addressed. It is shown that oriented open strings propagating on a group manifold $G$ are dual to $D$-brane - anti-$D$-brane pairs propagating on the dual group manifold \ti G. The $D$-branes coincide with the symplectic leaves of the standard Poisson structure induced on the dual group \ti G by the dressing action of the group $G$. T-duality maps the momentum of the open string into the mutual distance of the $D$-branes in the pair. The whole picture is then extended to the full modular space $M(D)$ of the Poisson-Lie equivalent \si-models which is the space of all Manin triples of a given Drinfeld double.T-duality rotates the zero modes of pairs of $D$-branes living on targets belonging to $M(D)$. In this more general case the $D$-branes are preimages of symplectic leaves in certain Poisson homogeneous spaces of their targets and, as such, they are either all even or all odd dimensional.Comment: 15 pages, LaTeX (references added

Particle Stirring in Turbulent Gas Disks: Including Orbital Oscillations

We describe the diffusion and random velocities of solid particles due to stochastic forcing by turbulent gas. We include the orbital dynamics of Keplerian disks, both in-plane epicycles and vertical oscillations. We obtain a new result for the diffusion of solids. The Schmidt number (ratio of gas to particle diffusivity) is Sc = 1 + (Omega t_stop)^2, in terms of the particle stopping time, t_stop, and the orbital frequency, Omega. The standard result, Sc = 1 + t_stop/t_eddy, in terms of the eddy turnover time, t_eddy, is shown to be incorrect. The main difference is that Sc rises quadratically, not linearly, with stopping time. Consequently, particles larger than ~ 10 cm in protoplanetary disks will suffer less radial diffusion and will settle closer to the midplane. Such a layer of boulders would be more prone to gravitational collapse. Our predictions of RMS speeds, vertical scale height and diffusion coefficients will help interpret numerical simulations. We confirm previous results for the vertical stirring of particles (scale heights and random velocities), and add a correction for arbitrary ratios of eddy to orbital times. The particle layer becomes thinner for t_eddy > 1/Omega, with the strength of turbulent diffusion held fixed. We use two analytic techniques -- the Hinze-Tchen formalism and the Fokker-Planck equation with velocity diffusion -- with identical results when the regimes of validity overlap. We include simple physical arguments for the scaling of our results.Comment: 17 pages, 7 figures, 2 tables, accepted to Icaru

Structure and thermodynamics of associating rods solutions

Thermoreversible sol-gel transitions in solutions of rod-like associating polymers are analyzed by computer simulations and by mean field models. The sol-gel transition is determined by the divergence of the cluster weight average. The analytically determined sol-gel transition is in good agreement with the simulation results. At low temperatures we observe a peak in the heat capacity, which maximum is associated with the precipitation transition. The gelation transition is sensitive to the number of associating groups per rod but nearly insensitive to the spatial distribution of associating groups around the rod. The precipitation is strongly dependent on both the number and distribution of associating groups per rod. We find negligible nematic orientational order at the gelation and precipitation transitions

Superconducting nanowire photon number resolving detector at telecom wavelength

The optical-to-electrical conversion, which is the basis of optical detectors, can be linear or nonlinear. When high sensitivities are needed single-photon detectors (SPDs) are used, which operate in a strongly nonlinear mode, their response being independent of the photon number. Nevertheless, photon-number resolving (PNR) detectors are needed, particularly in quantum optics, where n-photon states are routinely produced. In quantum communication, the PNR functionality is key to many protocols for establishing, swapping and measuring entanglement, and can be used to detect photon-number-splitting attacks. A linear detector with single-photon sensitivity can also be used for measuring a temporal waveform at extremely low light levels, e.g. in long-distance optical communications, fluorescence spectroscopy, optical time-domain reflectometry. We demonstrate here a PNR detector based on parallel superconducting nanowires and capable of counting up to 4 photons at telecommunication wavelengths, with ultralow dark count rate and high counting frequency

Transient reconnection in the cusp during strongly negative IMF B y

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94721/1/jgra16996.pd

Neutral and Charged Polymers at Interfaces

Chain-like macromolecules (polymers) show characteristic adsorption properties due to their flexibility and internal degrees of freedom, when attracted to surfaces and interfaces. In this review we discuss concepts and features that are relevant to the adsorption of neutral and charged polymers at equilibrium, including the type of polymer/surface interaction, the solvent quality, the characteristics of the surface, and the polymer structure. We pay special attention to the case of charged polymers (polyelectrolytes) that have a special importance due to their water solubility. We present a summary of recent progress in this rapidly evolving field. Because many experimental studies are performed with rather stiff biopolymers, we discuss in detail the case of semi-flexible polymers in addition to flexible ones. We first review the behavior of neutral and charged chains in solution. Then, the adsorption of a single polymer chain is considered. Next, the adsorption and depletion processes in the many-chain case are reviewed. Profiles, changes in the surface tension and polymer surface excess are presented. Mean-field and corrections due to fluctuations and lateral correlations are discussed. The force of interaction between two adsorbed layers, which is important in understanding colloidal stability, is characterized. The behavior of grafted polymers is also reviewed, both for neutral and charged polymer brushes.Comment: a review: 130 pages, 30 ps figures; final form, added reference

Catálogo sinonímico de los táxones ibero-baleares de la familia Meloidae (Coleoptera)

We present an up to date synonymic list of the Iberian and Balearic fauna of Meloidae (Coleoptera). This current list includes all synonymies for 65 taxa at the species level. We have checked most of the original references for all taxa and names cited in the catalogue. This revision leads to various corrections and changes in the spelling of some names and in publication dates and pagination of original references with respect to previous catalogues. The work is illustrated with photographs of 13 type specimens. Some nomenclatural and taxonomic problems require additional work, and their solution might produce further changes in the current list. Most relevant among these problems are the revision of <i>M. maculosopunctata</i> nomenclature, the confirmation of the specific identification of the single Iberian record for <i>M. tricincta</i>, the revision of the taxonomic status of <i>Meloe ibericus</i>, herein maintained at the species level while waiting for the needed revision of the <i>M. brevicollis</i> species group, the evaluation of the taxonomic status of <i>Sitaris melanura</i> and the taxonomic problem of the subgenus <i>Meloe</i> in the Balearic Islands.<br><br>En este trabajo presentamos un listado sinonímico actualizado de la fauna de Meloidae (Coleoptera) de la Península Ibérica e Islas Baleares. En el listado actual se recogen las sinonimias correspondientes a 65 táxones de nivel especie. Se han revisado las publicaciones donde se incluyen las descripciones originales de la mayoría de los táxones y nombres de las especies ibero baleares de Meloidae. Esta revisión ha llevado a diversas correcciones y actualizaciones tanto en la grafía de algunos nombres, como en las las referencias originales, incluyendo cambios de fechas o de paginación con respecto a catálogos anteriores. El trabajo se ilustra con fotografías de 13 ejemplares tipo. Existen una serie de problemas nomenclaturales y taxonómicos aún por resolver, que podrían producir cambios en el listado actual. Entre estos problemas destacan el caso de la nomenclatura de <i>M. maculosopunctata</i> que requiere revisión, la adscripción específica correcta de la cita ibérica de <i>M. tricincta</i>, la revisión del estatus taxonómico de <i>Meloe ibericus</i>, que se mantiene a nivel específico en espera de la revisión del grupo de especies afines a <i>M. brevicollis</i>, la revisión del estatus de <i>Sitaris melanura</i> y el problema taxonómico del subgénero <i>Meloe</i> en las Islas Baleares

Les Houches 2011: Physics at TeV Colliders New Physics Working Group Report

We present the activities of the "New Physics" working group for the "Physics at TeV Colliders" workshop (Les Houches, France, 30 May-17 June, 2011). Our report includes new agreements on formats for interfaces between computational tools, new tool developments, important signatures for searches at the LHC, recommendations for presentation of LHC search results, as well as additional phenomenological studies.Comment: 243 pages, report of the Les Houches 2011 New Physics Group; fix three figure

Hadron Energy Reconstruction for the ATLAS Calorimetry in the Framework of the Non-parametrical Method

This paper discusses hadron energy reconstruction for the ATLAS barrel prototype combined calorimeter (consisting of a lead-liquid argon electromagnetic part and an iron-scintillator hadronic part) in the framework of the non-parametrical method. The non-parametrical method utilizes only the known $e/h$ ratios and the electron calibration constants and does not require the determination of any parameters by a minimization technique. Thus, this technique lends itself to an easy use in a first level trigger. The reconstructed mean values of the hadron energies are within $\pm 1$ of the true values and the fractional energy resolution is $[(58\pm3)/\sqrt{E}+(2.5\pm0.3)$. The value of the $e/h$ ratio obtained for the electromagnetic compartment of the combined calorimeter is $1.74\pm0.04$ and agrees with the prediction that $e/h > 1.7$ for this electromagnetic calorimeter. Results of a study of the longitudinal hadronic shower development are also presented. The data have been taken in the H8 beam line of the CERN SPS using pions of energies from 10 to 300 GeV.Comment: 33 pages, 13 figures, Will be published in NIM