118,363 research outputs found
Beatrix von Bayern, Gräfin von Görz
No full textGräfin in ganzer
Figur auf einer Bank sitzend, in den erhobenen Händen je einen
dreieckigen Wappenschild haltend (r.: Bayern, l.: Görz) über denen
die Initialen r. B (= Beatrix) bzw. l. h (= Heinrich II. von Görz,
Gemahl der Beatrix). Hintergrund mit Rosenranken gemustert
The BEaTriX X-ray facility at work:activities and future development
No full textThe BEaTriX (Beam Expander Testing X-ray) facility has completed the commissioning phase. This unique compact facility – that occupies an area of 8 x 14 m2 - provides a large (170 mm × 60 mm) collimated (< 2.5 arcsec) monochromatic beam at the energy of 4.51 keV. Its concept is based on the combination of a microfocus X-ray source, a parabolic mirror, and a set of silicon crystals, one of which is asymmetrically cut with respect to the lattice planes. The tests have proven the BEaTriX capability to perform the acceptance tests for Point Spread Function and Effective Area of the NewAthena Silicon Pore Optics Mirror Modules (MM) with a 3 MM/day throughput. The second BEaTriX beamline at the X-ray of 1.49 keV is currently being developed. The optomechanical design, and simulation of alignment tolerances have been completed. The parabolic mirror is being polished at INAF-OAB, on the basis of the experience matured with producing the parabolic mirror for the 4.51 keV beam line. The crystals for the monochromator (Quartz 10-10) and the beam expander (ADP 101) are being procured. Differently from the 4.51 keV beam line, all three crystals for the 1.49 keV are asymmetrically cut, as a special design has been adopted to guarantee the specifications. Owing to the good results obtained by BEaTriX at the INAF labs in Italy, a feasibility study is also ongoing to replicate the facility with a similar design at cosine B.V. in The Netherlands (where the MMs will be produced) for measuring the MMs SPO at 1.49 and 6.4 keV before and after the vibrational tests.</p
BEaTriX, expanded x-ray beam facility for testing modular elements of telescope optics: an update
No full textWe present in this paper an update on the design of BEaTriX (Beam Expander Testing X-ray facility), an X-ray apparatus to be realized at INAF/OAB and that will generate an expanded, uniform and parallel beam of soft X-rays. BEaTriX will be used to perform the functional tests of X-ray focusing modules of large X-ray optics such as those for the ATHENA X-ray observatory, using the Silicon Pore Optics (SPO) as a baseline technology, and Slumped Glass Optics (SGO) as a possible alternative. Performing the tests in X-rays provides the advantage of an in-situ, at-wavelength quality control of the optical modules produced in series by the industry, performing a selection of the modules with the best angular resolution, and, in the case of SPOs, there is also the interesting possibility to align the parabolic and the hyperbolic stacks directly under X-rays, to minimize the aberrations. However, a parallel beam with divergence below 2 arcsec is necessary in order to measure mirror elements that are expected to reach an angular resolution of about 4 arcsec, since the ATHENA requirement for the entire telescope is 5 arcsec. Such a low divergence over the typical aperture of modular optics would require an X-ray source to be located in a several kilometers long vacuum tube. In contrast, BEaTriX will be compact enough (5 m x 14 m) to be housed in a small laboratory, will produce an expanded X-ray beam 60 mm x 200 mm broad, characterized by a very low divergence (1.5 arcsec HEW), strong polarization, high uniformity, and X-ray energy selectable between 1.5 keV and 4.5 keV. In this work we describe the BEaTriX layout and show a performance simulation for the X-ray energy of 4.5 keV
Alignment and qualification of BEaTriX X-ray facility for testing the ATHENA space telescope
No full textLAUREA MAGISTRALEATHENA (Advanced Telescope for High ENergy Astrophysics) è la missione a raggi X di classe L, selezionata dall’Agenzia Spaziale Europea (ESA) e prevista per i primi anni 2030. I numerosi Silicon Pore Optics Mirror Modules (SPO MM), che costituiranno il telescopio spaziale a raggi X di ATHENA, richiedono un nuovo approccio dal punto di vista delle attrezzature di supporto a terra (GSE). Il laboratorio BEaTriX (Beam Expander Testing X-ray), realizzato presso INAF-Osservatorio Astronomico di Brera (Merate, Italia), è l’unica struttura adibita al processo di Assemblaggio, Integrazione e Verifica (AIV) di ATHENA, in grado di eseguire in sequenza i test di convalida a raggi X degli SPO MM rispettando il tasso di produzione. L’innovativo design ottico di BEaTriX, costituito da particolari elementi ottici (specchio parabolico, monocromatori ed espansore di fascio), è in grado di creare, in un piccolo volume, un fascio monocromatico, espanso e poco divergente di raggi X, così da illuminare un intero SPO MM con un’unica esposizione e garantendo un notevole risparmio di tempo e denaro. Il lavoro di tesi si focalizza sull’allineamento dei componenti ottici e sulla qualifica del fascio a raggi X prodotto dal sistema ottico, con l’intento di soddisfare i requisiti imposti dall’ESA. Inoltre la tesi indaga un metodo per caratterizzare il fascio di BEaTriX a raggi X che include la ricostruzione del fronte d’onda e la sua analisi attraverso l’utilizzo dei polinomi di Zernike, al fine di comprendere le aberrazioni ottiche di cui è affetto il fascio stesso.ATHENA (Advanced Telescope for High ENergy Astrophysics) is the Large X-ray mission selected by ESA for early 2030s. The ATHENA X-ray Space Telescope will be composed by a large number of Silicon Pore Optics Mirror Modules (SPO MMs) that requires a novel approach also from the Ground Support Equipment (GSE) point of view. The BEaTriX (Beam Expander Testing X-ray) facility, built at INAF-Brera Astronomical Observatory (Merate, Italy), is the unique facility for the ATHENA AIV process able to sequentially perform the X-ray acceptance tests of the SPO MMs sustaining the production rate. The BEaTriX innovative optical design, composed by elements (the parabolic mirror, the monochromators, and the Beam Expander), provides a monochromatic, expanded and low-divergent X-ray beam in a small volume to illuminate a complete SPO MM in a single exposure, with a considerable time and cost saving. The thesis work focuses on the alignment of the optical components and the qualification of the X-ray beam obtained after the optical chain to fulfill the ESA requirements. Moreover, the thesis investigates a method to characterize the BEaTriX X-ray beam that includes the wavefront reconstruction and its analysis through a development in Zernike polynomials, in order to understand the optical aberrations that affect the BEaTriX X-ray beam
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Peter Rabbit, Dougal und Mary Poppins. Die Erzählwelten von Beatrix Potter und Emma Thompson
No full textHoffmann L. Peter Rabbit, Dougal und Mary Poppins. Die Erzählwelten von Beatrix Potter und Emma Thompson. In: Frizzoni B, Lötscher C, eds. "Bring me that horizon!" Neue Perspektiven auf Ästhetik und Praxis populärer Literaturen und Medien. Zürich: Chronos; 2020: 43-52
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
- …
