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

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

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

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

The roman catholic church and contraception

The official position regarding the use of artificial means of family planning varies from religion to religion. With its steadfast opposition to the use of any form of contraception or sterilization, the Roman Catholic Church puts its 1.2 billion followers worldwide in the difficult dilemma of either adhering to the teaching of their church and thereby risk an unwanted pregnancy, or ignoring that teaching and use an artificial method of family planning, but thereby become marginalized by their church. Pope Francis has made a number of statements and actions indicating that their might be a possibility of some changes in the teaching of the Roman Catholic Church regarding a number of issues re-lated to the family, such as divorce, remarriage, gays and women’s rights. However he has continued to reaffirm the Church’s opposition to the use of any artificial method of family planning and has reiterated on a number of occasions that the Church will only allow the so called natural methods. This essay argues that in the opinion of the author, the time has come for the Roman Catholic hierarchy to revise this outdated position and allow catholics to resort to modern methods for limiting the size of their family, which is some-thing that a large percentage of the catholics are doing already anyway

Magnetic and structural properties of nanocrystalline PrCo3_3

The structure and magnetic properties of nanocrystalline PrCo$_3$ obtained from high energy milling technique are investigated by X-ray diffraction, Curie temperature determination and magnetic properties measurements are reported. The as-milled samples have been annealed in a temperature range of 1023 K to 1273 K for 30 mn to optimize the extrinsic properties. The Curie temperature is 349\,K and coercive fields of 55\,kOe at 10\,K and 12\,kOe at 293\,K are obtained on the samples annealed at 1023\,K. A simulation of the magnetic properties in the framework of micromagnetism has been performed in order to investigate the influence of the nanoscale structure. A composite model with hard crystallites embedded in an amorphous matrix, corresponding to the as-milled material, leads to satisfying agreement with the experimental magnetization curve. [ K. Younsi, V. Russier and L. Bessais, J. Appl. Phys. {\bf 107}, 083916 (2010)]. The microscopic scale will also be considered from DFT based calculations of the electronic structure of $R$Co$_x$ compounds, where $R$ = (Y, Pr) and $x$ = 2,3 and 5.Comment: To be published in J. Phys.: Conference Series in the JEMS 2010 special issue. To be found once published at http://iopscience.iop.org/1742-659

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