14,291 research outputs found

    Method of fabricating a photovoltaic module of a substantially transparent construction

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    A method characterized by the steps of positioning a plurality of uniformly dimensioned photovoltaic cells in registered relation with a plurality of openings formed in a planar tool is disclosed. The method allows acess to the P contact surface of each of the cells. The steps of the method are: (1) connecting the N contact surface of alternate cells to the P contact surface of the cells interposed therebetween, (2) removing therefrom residue of solder flux, (3) applying to the N contact surfaces of the cells a transparent adhesive, (4) placing a common transparent cover plate in engaged relation with the adhesive, (5) placing a film over the circular openings for hermetically sealing the openings, and (6) establishing a vacuum between the film and the cover plate

    Optimization of Al/AlOx/AlAl/AlO_x/Al-Layer Systems for Josephson Junctions from a Microstructure Point of View

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    Al/AlOx/AlAl/AlO_x/Al-layer systems are frequently used for Josephson junction-based superconducting devices. Although much work has been devoted to the optimization of the superconducting properties of these devices, systematic studies on influence of deposition conditions combined with structural analyses on the nanoscale are rare up to now. We have focused on the optimization of the structural properties of Al/AlOx/AlAl/AlO_x/Al-layer systems deposited on Si(111) substrates with a particular focus on the thickness homogeneity of the AlOxAlO_x-tunnel barrier. A standard high-vacuum electron-beam deposition system was used and the effect of substrate pretreatment, different Al-deposition temperatures and Al-deposition rates was studied. Transmission electron microscopy was applied to analyze the structural properties of the Al/AlOx/AlAl/AlO_x/Al-layer systems to determine the thickness homogeneity of the AlOxAlO_x layer, grain size distribution in the Al layers, Al-grain boundary types and the morphology of the Al/AlOxAl/AlO_x interface. We show that the structural properties of the lower Al layer are decisive for the structural quality of the whole Al/AlOx/AlAl/AlO_x/Al-layer system. Optimum conditions yield an epitaxial Al(111) layer on a Si(111) substrate with an Al-layer thickness variation of only 1.6 nm over more than 10 μm\mu m and large lateral grain sizes up to 1 μm\mu m. Thickness fluctuations of the AlOxAlO_x-tunnel barrier are minimized on such an Al layer which is essential for the homogeneity of the tunnel current. Systematic variation of the Al-deposition rate and deposition temperature allows to develop an understanding of the growth mechanisms

    Early-type Galaxies in the Cluster Abell 2390 at z=0.23

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    To examine the evolution of the early-type galaxy population in the rich cluster Abell 2390 at z=0.23 we have gained spectroscopic data of 51 elliptical and lenticular galaxies with MOSCA at the 3.5 m telescope on Calar Alto Observatory. This investigation spans both a broad range in luminosity (-19.3>M_B>-22.3) and uses a wide field of view of 10'x10', therefore the environmental dependence of different formation scenarios can be analysed in detail as a function of radius from the cluster centre. Here we present results on the surface brightness modelling of galaxies where morphological and structural information is available in the F814W filter aboard the Hubble Space Telescope (HST) and investigate for this subsample the evolution of the Fundamental Plane.Comment: 5 pages, 5 figures, to appear in "Carnegie Observatories Astrophysics Series, Vol. 3: Clusters of Galaxies: Probes of Cosmological Structure and Galaxy Evolution", ed. J. S. Mulchaey, A. Dressler, and A. Oemler (Pasadena: Carnegie Observatories, http://www.ociw.edu/ociw/symposia/series/symposium3/proceedings.html

    Ring current proton decay by charge exchange

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    Explorer 45 measurements during the recovery phase of a moderate magnetic storm have confirmed that the charge exchange decay mechanism can account for the decay of the storm-time proton ring current. Data from the moderate magnetic storm of 24 February 1972 was selected for study since a symmetrical ring current had developed and effects due to asymmetric ring current losses could be eliminated. It was found that after the initial rapid decay of the proton flux, the equatorially mirroring protons in the energy range 5 to 30 keV decayed throughout the L-value range of 3.5 to 5.0 at the charge exchange decay rate calculated by Liemohn. After several days of decay, the proton fluxes reached a lower limit where an apparent equilibrium was maintained, between weak particle source mechanisms and the loss mechanisms, until fresh protons were injected into the ring current region during substorms. While other proton loss mechanisms may also be operating, the results indicate that charge exchange can entirely account for the storm-time proton ring current decay, and that this mechanism must be considered in all studies involving the loss of proton ring current particles

    Economic Effects of Regional Tax Havens

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    How does the opportunity to use tax havens influence economic activity in nearby non-haven countries? Analysis of affiliate-level data indicates that American multinational firms use tax haven affiliates to reallocate taxable income away from high-tax jurisdictions and to defer home country taxes on foreign income. Ownership of tax haven affiliates is associated with reduced tax payments by nearby non-haven affiliates, the size of the effect being equivalent to a 20.8 percent tax rate reduction. The evidence also indicates that use of tax havens indirectly stimulates the growth of operations in non-haven countries in the same region. A one percent greater likelihood of establishing a tax haven affiliate is associated with 0.5 to 0.7 percent greater sales and investment growth by non-haven affiliates, implying a complementary relationship between haven and non-haven activity. The ability to avoid taxes by using tax haven affiliates therefore appears to facilitate economic activity in non-haven countries within regions.

    Geophysical characteristics of the Atlantic Ocean

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