Planning for Space Station Freedom laboratory payload integration

Space Station Freedom is being developed to support extensive missions involving microgravity research and applications. Requirements for on-orbit payload integration and the simultaneous payload integration of multiple mission increments will provide the stimulus to develop new streamlined integration procedures in order to take advantage of the increased capabilities offered by Freedom. The United States Laboratory and its user accommodations are described. The process of integrating users' experiments and equipment into the United States Laboratory and the Pressurized Logistics Modules is described. This process includes the strategic and tactical phases of Space Station utilization planning. The support that the Work Package 01 Utilization office will provide to the users and hardware developers, in the form of Experiment Integration Engineers, early accommodation assessments, and physical integration of experiment equipment, is described. Plans for integrated payload analytical integration are also described

Numération bactérienne en épifluorescence par la méthode couplée DAPI-INT : application à un cas concret

Un protocole simple de coloration par la méthode couplée DAPI-INT en microscopie à épifluorescence, associé à une lecture des préparations par caméra et vidéo-Imprimante, permet la mesure de paramètres biologiques impliqués directement dans les processus de dégradation de la matière organique en rivière : numérations de microflore totale, nombre de cellules physiologiquement actives (réduisant l'INT), nombre de cellules avec réserves de PHB, dimensions cellulaires et répartition en classes de taille aboutissant à l'évaluation de la biomasse carbonée.Tous les comptages et mesures sont réalisés à partir de clichés d'imprimante thermique, ce qui assure une reproductibilité et une comparaison entre échantillons plus objective qu'à partir de seules observations directes.Cette méthode permet de différer soit les comptages (échantillons fixés au formol après incubation à l'INT), soit surtout les mesures de dimensions cellulaires (archivage des clichés pour une exploitation ultérieure).Son application au cas de la rivière Charente montre une évolution particulière de la biomasse bactérienne en aval des rejets de l'agglomération d'Angoulême. La mise en évidence de cellules de grande taille (biovolume moyen de 0,3 µm3) et d'une population plus active pourrait traduire une modification physiologique de micro-organismes autochtones réagissant à des conditions de milieu particulières (rejets d'effluents carencés en azote).The increasing appreciation of heterotrophic bacterioplankton as an important and dynamic compartment in the carbon cycle of aquatic ecosystems has led to the development of methods allowing reproducible and reliable direct bacterial counts. Thus, since the 1970's, enumeration of bacteria by epifluorescence microscopy has become a widely used method for the estimation of cell number and biovolume. Cell counts are made using either the acridine orange (Hobbie et al. 1977) or the DAPI (Porter 1980) procedure on fixed samples. A tracer of cellular respiratory activity (INT) can be linked to either of these two methods before the samples are killed by formalin. Two observations of the same field, one in transmitted light, the other by epifluorescence, allow a determination of the percentage of active bacterioplankton (Tabor and Neihof 1982, Dufour 1990).However, the various authors working with these procedures have modified the protocol and up to now there has not been a standard method. Thus, before using it for the first time, numerous verifications about filters, concentration of dye solution and methods for estimating cell volume are necessary.In this study a simultaneous comparison, between three brands of filters, two dye solutions and three methods for numeration and cell volume estimation (by direct count, by photographs and by video graphic printer) has been performed.All the tests have been clone with samples collected from rivera or lakes. In comparison to laboratory cultures, natural bacteria are observed with difficulty on account of their small size and especially because natural organic matter absorbs dye solution and so interferes with counts. We prefer to use DAPI rather than acridine orange, because DAPI is colorless in direct light, so it doesn't interfere with enumeration of respiring bacteria (red crystal inside cell). To obtain the best contrast for observation in epifluorescence microscopy, a very fast drying in the open air and a structure less troublesome for the observation in direct light, we have chosen Millipore black filters. A camera associated with a video printer gives better results compared to the photographs : no fluorescent "halo" around the tell image and no waste of time waiting for development of the film. All counts and measures were made from video graphic printer photographs, which assures reproductibility and more objective comparisons between samples, compared to direct counts (with eyes) that are tiring and subjective. Finally, we can defer counting (samples fixed in formol after INT incubation) or cell size measurements (analysis of recorded photos) to a later time.On the basis of this tests, the DAPI-INT method in fluorescence microscopy, associated with the reading of slides with a camera and a video-printer, allows one to measure biological parameters directly implicated in the degradation of river organic matter : abundance of total microflora, number of physiologically active cells (reducing INT) and cells with PHB reserves, cell sizes and size range distribution used to evaluate carbon biomass.The application of this method to the river Charente (April to November 1991) shows a particular fate of bacterial biomass downstream from the city of Angouleme. A multifactor analysis of variance with a multiple range analyses (Tukey) shows that bacterial cells collected downstream from the effluent discharge of the Angouleme wastewater treatment plant are the largest (average cell volume up to 0.3 µm3) and the more active cells. Similar trends have also been observed by Servais and Garnier (1989) downstream from the Paris wastewater treatment plant (Achères) on the Seine river. These authors suggested that allochtonous populations associated with the urban sewage were different from the autochtonous populations (higher biovolume). To verify this hypothesis, a sampling campaign (June 92) was performed on five stations along an eight kilometers river reach. There weren't large size bacteria downstream from the effluent discharge of Frégeneuil, Fléac and St Michel wastewater treatment plants. We Pound the largest bacteria at Nersac. Thus it seems that these large bacteria don't came from wastewater treatment plant. The increase of autochtonous bacterial size could be interpretated as a nutritional stress, the increase of the C/N ratio preventing cellular division (nitrogen deficient sewages)

Slow dynamics in a turbulent von K\'arm\'an swirling flow

We present an experimental study of a turbulent von K\'arm\'an flow produced in a cylindrical container using two propellers. The mean flow is stationary up to $Re = 10^4$, where a bifurcation takes place. The new regime breaks some symmetries of the problem, and is time-dependent. The axisymmetry is broken by the presence of equatorial vortices with a precession movement, being the velocity of the vortices proportional to the Reynolds number. The reflection symmetry through the equatorial plane is broken, and the shear layer of the mean flow appears displaced from the equator. These two facts appear simultaneously. In the exact counterrotating case, a bistable regime appears between both mirrored solutions and spontaneous reversals of the azimuthal velocity are registered. This evolution can be explained using a three-well potential model with additive noise. A regime of forced periodic response is observed when a very weak input signal is applied.Comment: Improved model, additional results and figures, accepted in PR

Classification of Generalized Symmetries for the Vacuum Einstein Equations

A generalized symmetry of a system of differential equations is an infinitesimal transformation depending locally upon the fields and their derivatives which carries solutions to solutions. We classify all generalized symmetries of the vacuum Einstein equations in four spacetime dimensions. To begin, we analyze symmetries that can be built from the metric, curvature, and covariant derivatives of the curvature to any order; these are called natural symmetries and are globally defined on any spacetime manifold. We next classify first-order generalized symmetries, that is, symmetries that depend on the metric and its first derivatives. Finally, using results from the classification of natural symmetries, we reduce the classification of all higher-order generalized symmetries to the first-order case. In each case we find that the generalized symmetries are infinitesimal generalized diffeomorphisms and constant metric scalings. There are no non-trivial conservation laws associated with these symmetries. A novel feature of our analysis is the use of a fundamental set of spinorial coordinates on the infinite jet space of Ricci-flat metrics, which are derived from Penrose's ``exact set of fields'' for the vacuum equations.Comment: 57 pages, plain Te

mm-Wave DRW Antenna Phase Centre Determination

This document presents an approach to the phase centre determination of a dielectric rod waveguide (DRW) antenna by means of measurements obtained with a planar measuring system at millimeter wave lengths. Phase centre determination by the least squares fit technique is described in this document for different DRW antennas (silicon and sapphire). Results at different operating frequencies are offered

Point defects on graphene on metals

Understanding the coupling of graphene with its local environment is critical to be able to integrate it in tomorrow's electronic devices. Here we show how the presence of a metallic substrate affects the properties of an atomically tailored graphene layer. We have deliberately introduced single carbon vacancies on a graphene monolayer grown on a Pt(111) surface and investigated its impact in the electronic, structural and magnetic properties of the graphene layer. Our low temperature scanning tunneling microscopy studies, complemented by density functional theory, show the existence of a broad electronic resonance above the Fermi energy associated with the vacancies. Vacancy sites become reactive leading to an increase of the coupling between the graphene layer and the metal substrate at these points; this gives rise to a rapid decay of the localized state and the quenching of the magnetic moment associated with carbon vacancies in free-standing graphene layers

Antiproton modulation in the Heliosphere and AMS-02 antiproton over proton ratio prediction

We implemented a quasi time-dependent 2D stochastic model of solar modulation describing the transport of cosmic rays (CR) in the heliosphere. Our code can modulate the Local Interstellar Spectrum (LIS) of a generic charged particle (light cosmic ions and electrons), calculating the spectrum at 1AU. Several measurements of CR antiparticles have been performed. Here we focused our attention on the CR antiproton component and the antiproton over proton ratio. We show that our model, using the same heliospheric parameters for both particles, fit the observed anti-p/p ratio. We show a good agreement with BESS-97 and PAMELA data and make a prediction for the AMS-02 experiment

Quantum oscillations of self-dual Abrikosov-Nielsen-Olesen vortices

The mass shift induced by one-loop quantum fluctuations on self-dual ANO vortices is computed using heat kernel/generalized zeta function regularization methods. The quantum masses of super-imposed multi-vortices with vorticity lower than five are given. The case of two separate vortices with a quantum of magnetic flux is also discussed.Comment: RevTex, 13 pages, 4 figures, 7 tables. Minor corrections. Version to appear in Physical Review