Diffusion approximation of a multilocus model with assortative mating

To understand the effect of assortative mating on the genetic evolution of a population, we consider a finite population in which each individual has a type, determined by a sequence of n diallelic loci. We assume that the population evolves according to a Moran model with weak assortative mating, strong recombination and low mutation rates. With an appropriate rescaling of time, we obtain that the evolution of the genotypic frequencies in a large population can be approximated by the evolution of the product of the allelic frequencies at each locus, and the vector of the allelic frequencies is approximately governed by a diffusion. We present some features of the limiting diffusions (in particular their boundary behaviour and conditions under which the allelic frequencies at different loci evolve independently). If mutation rates are strictly positive then the limiting diffusion is reversible and, under some assumptions, the critical points of the stationary density can be characterised.Comment: 56 pages, 8 figures ; corrected typo

The nature of turbulence in OMC1 at the star forming scale: observations and simulations

Aim: To study turbulence in the Orion Molecular Cloud (OMC1) by comparing observed and simulated characteristics of the gas motions. Method: Using a dataset of vibrationally excited H2 emission in OMC1 containing radial velocity and brightness which covers scales from 70AU to 30000AU, we present the transversal structure functions and the scaling of the structure functions with their order. These are compared with the predictions of two-dimensional projections of simulations of supersonic hydrodynamic turbulence. Results: The structure functions of OMC1 are not well represented by power laws, but show clear deviations below 2000AU. However, using the technique of extended self-similarity, power laws are recovered at scales down to 160AU. The scaling of the higher order structure functions with order deviates from the standard scaling for supersonic turbulence. This is explained as a selection effect of preferentially observing the shocked part of the gas and the scaling can be reproduced using line-of-sight integrated velocity data from subsets of supersonic turbulence simulations. These subsets select regions of strong flow convergence and high density associated with shock structure. Deviations of the structure functions in OMC1 from power laws cannot however be reproduced in simulations and remains an outstanding issue.Comment: 12 pages, 8 figures, accepted A&A. Revised in response to referee. For higher resolution, see http://www.astro.phys.au.dk/~maikeng/sim_paper

Electric potential distributions at the interface between plasmasheet clouds

At the interface between two plasma clouds with different densities, temperatures, and/or bulk velocities, there are large charge separation electric fields which can be modeled in the framework of a collisionless theory for tangential discontinuities. Two different classes of layers were identified: the first one corresponds to (stable) ion layers which are thicker than one ion Lamor radius; the second one corresponds to (unstable) electron layers which are only a few electron Larmor radii thick. It is suggested that these thin electron layers with large electric potential gradients (up to 400 mV/m) are the regions where large-amplitude electrostatic waves are spontaneously generated. These waves scatter the pitch angles of the ambient plasmasheet electron into the atmospheric loss cone. The unstable electron layers can therefore be considered as the seat of strong pitch angle scattering for the primary auroral electrons

Legami curati - legami curanti. 'Cliniche della concertazione' e violenze di quartiere

Mahdi ha ventisei anni, è alto e di corporatura atletica ed è cieco in quanto vittima di un’aggressione in cui ha perso la vista. Una situazione come questa descritta, mette al lavoro una rete complessa che associa professionisti dell’aiuto, della cura, dell’educazione e del controllo, al di là di ciò che questi stessi operatori possono immaginare. La metodologia della “Clinica della Concertazione”, intesa come “Laboratorio di etica comunicazionale applicata”, riconosce a Mahdi e ai vari membri della sua famiglia il ruolo di architetti di questa rete. Se i professionisti non resistono a questa costruzione collettiva, vedranno disporsi numerosi sistemi relazionali in equilibrio di cui potranno sfruttare le risorse in un processo ricostruttore di legami. Più che un dispositivo descrittivo, la Clinica della Concertazione è un dispositivo terapeutico creativo retto da regole aleatorie che sfuggono a un progetto di padronanza assoluta. Si tratta, in un dibattito che non esclude alcun membro di questo collettivo ma, proprio al contrario, promotore di tutti i passi estensivi, di differenziare senza dissociare, con tutte le persone interessate ciò che apparterrà alla sfera privata da ciò che apparterrà alla sfera pubblica, riconoscendo la legittimità delle dinamiche compensative vendicative e delle dinamiche protettrici delle generazioni future, individuando le loro articolazioni, le loro compatibilità e incompatibilità permettendo lo sviluppo preferibilmente, di quelle che sono ricostruttrici e preventive. Résumé Mahdi a vingt-six ans, il est grand et de stature athlétique. Il est aveugle. Il a été victime d’une agression qui lui a ôté la vue. Une situation comme celle de Mahdi met au travail un réseau complexe associant des professionnels de l’aide, du soin, de l’éducation et du contrôle, au-delà de ce que ces mêmes professionnels peuvent imaginer. La Méthodologie de la « Clinique de Concertation », en tant que « Laboratoire d’éthique communicationelle appliquée», reconnaît que Mahdi et les membres de sa famille font d’emblée partie des architectes de ce réseau. Si les professionnels ne résistent pas à cette construction collective, ils verront se disposer plusieurs systèmes relationnels en équilibre dont ils pourront exploiter les ressources dans des processus reconstructeurs de liens. Plus qu’un dispositif descriptif, la « Clinique de Concertation » est un dispositif thérapeutique créatif régi par des règles aléatoires échappant à un projet de maîtrise absolue. Il s’agit, dans un débat collectif n’excluant aucun membre de ce même collectif, bien au contraire, promoteur de toutes les démarches extensives, de différencier sans dissocier, avec toutes les personnes intéressées ce qui va appartenir à la sphère privée de ce qui va appartenir à la sphère publique, tout en reconnaissant la légitimité des dynamiques compensatoires vengeresses et des dynamiques protectrices des générations futures, en repérant leurs articulations, leurs compatibilités et leurs incompatibilités, de développer préférentiellement celles qui sont reconstructrices et préventives. Abstract Mahdi is twenty-six years old, he is tall and athletic. He is blind, because he was attacked. This kind of situation puts at work a complex network of professionals of help, care, education and control, beyond everything they can expect. The methodology of the « Clinic of Concertation », as a « Laboratory of applied communicational ethics », recognises that Mahdi and the members of his family are directly part of this network. If the professionals do not resist to this collective construction, they will see laying out different relational systems in balance from which they can exploit the resources in the process of reconstructive links. More than a narrative device, the "Clinic of Concertation" is a creative therapeutic device governed by random rules beyond an absolute mastery. It is, in a collective discussion that does not exclude any member of the collective, but on the contrary, that promotes every extensive step, about differentiating without dissociating, with all interested persons, what will belong to the private sphere and what will belong to the public sphere, while recognizing the legitimacy of the compensatory dynamics of revenge and the protective dynamics of future generations, by identifying their joints, their compatibilities and their incompatibilities, by developing preferentially those reconstructive and preventive

Interplanetary boundary layers at 1 AU

The structure and nature of discontinuities in the interplanetary magnetic field at 1 AU in the period March 18, 1971 to April 9, 1971, is determined by using high-resolution magnetic field measurements from Explorer 34. The discontinuities that were selected for this analysis occurred under a variety of interplanetary conditions at an average rate of 0.5/hr. This set does not include all discontinuities that were present, but the sample is large and it is probably representative. Both tangential and rotational discontinuities were identified, the ratio of TD's to RD's being approximately 3 to 1. Tangential discontinuities were observed every day, even among Alfvenic fluctuations. The structure of most of the boundary layers was simple and ordered, i.e., the magnetic field usually changed smoothly and monotonically from one side of the boundary layer to the other

Observations of spatial and velocity structure in the Orion Molecular Cloud

Observations are reported of H2 IR emission in the S(1) v=1-0 line at 2.121 microns in the Orion Molecular Cloud, OMC1, using the GriF instrument on the Canada-France-Hawaii Telescope. GriF is a combination of adaptive optics and Fabry-Perot interferometry, yielding a spatial resolution of 0.15" to 0.18" and a velocity discrimination as high as 1 km/s. Thanks to the high spatial and velocity resolution of the GriF data, 193 bright H2 emission regions can be identified in OMC1. The general characteristics of these features are described in terms of radial velocities, brightness and spatial displacement of maxima of velocity and brightness, the latter to yield the orientation of flows in the plane of the sky. Strong spatial correlation between velocity and bright H2 emission is found and serves to identify many features as shocks. Important results are: (i) velocities of the excited gas illustrate the presence of a zone to the south of BN-IRc2 and Peak 1, and the west of Peak 2, where there is a powerful blue-shifted outflow with an average velocity of -18 km/s. This is shown to be the NIR counterpart of an outflow identified in the radio from source I, a very young O-star. (ii) There is a band of weak velocity features (<5 km/s) in Peak 1 which may share a common origin through an explosive event, in the BN-IRc2 region, with the fast-moving fingers (or bullets) to the NW of OMC1. (iii) A proportion of the flows are likely to represent sites of low mass star formation and several regions show multiple outflows, probably indicative of multiple star formation within OMC1. The high spatial and velocity resolution of the GriF data show these and other features in more detail than has previously been possible.Comment: 27 pages, 19 figures, submitted to A&A Version 2: Several additions, including a section on protostellar candidates in OMC1, have been made based on the referee's suggestions v3: corrected typograph

Reliability analysis of bonded joints with variations in adhesive thickness

Bonded joints are used in several industrial applications as a surrogate of more expensive repairs, but their reliability must be ascertained. Failure in a bonded joint mainly occurs in the adhesive due to stress concentrations that directly depend on the adhesive thickness. In practice, it is difficult to ensure a good accuracy of the final adhesive thickness, leading to uncertainty to its spatial variability. This uncertainty greatly influences the strength of the bonded joint. This work deals with one of the main key issues in bonded joints: the influence of the spatial variations in the adhesive thickness on the reliability of the joint and an excessive shear stress level caused by the adhesive thickness variations may lead to failure. This paper provides reliability analysis by considering the adhesive thickness as a stochastic field. The experimental thickness field is obtained so as to identify the stochastic parameters. These parameters are then introduced in a structural reliability model to evaluate the failure probability. Results show the influence of adhesive thickness uncertainty on bonded joint failure. © 2012 Taylor & Francis

Improved version of the eikonal model for absorbing spherical particles

We present a new expression of the scattering amplitude, valid for spherical absorbing objects, which leads to an improved version of the eikonal method outside the diffraction region. Limitations of this method are discussed and numerical results are presented and compared successfully with the Mie theory.Comment: 7 pages, postscript figures available on cpt.univ-mrs.fr, to appear in J. Mod. Optic

Sputtered Tungsten Oxide as Hole Contact for Silicon Heterojunction Solar Cells

Reactively sputtered tungsten oxide WOx was investigated as hole contact on n type crystalline silicon. Varying the oxygen gas flow during sputtering enables variation of the WOx conductivity from 0.01 to 1000 amp; 937; cm, while the band bending at the interface and the implied fill factor FF change by 70 meV and 1.5 . SputteredWOx shows higher resistivity and higher absorption in the visible range compared with indium tin oxide ITO . Therefore, stacks of WOx and ITO are used in solar cells. It was found that at least 20 nm thick WOx is needed to prevent detrimental effects of the ITO work function on the band bending at the junction, the implied FF, and the real FF of solar cells. WOx hole contacts of different thicknesses and conductivity were applied in solar cells and it was found that the highest FF is achieved using about 20 nm thick interlayers of WOx with the highest possible conductivity. It was found that sputtering enables a drastic improvement of WOx silicon solar cells compared with thermal evaporation, due to the precise control of the WOx conductivity. Unfortunately, the resistivity of the sputteredWOx is still limiting the FF of these device