5,563 research outputs found
Recommended from our members
Measuring conditions for second order X-ray Bragg-spectrometry
The KL2,3 (α)1,2-lines of 19K, the L3M4,5 (α)1,2-lines of 48Cd, and the M5N6,7 (α)1,2-lines of 92U are lines of comparable energy in the region of approximately 3 keV. In none of these cases were we able to resolve the three doublets when recording the spectra in first order Bragg spectrometry using a PET crystal as the dispersing element. For the purpose of enhancing the resolving power of the spectrometer, the three α spectra were recorded in second order reflection, thereby transferring the lines into another spectral region dominated by X-ray quanta of half the energy. In order to achieve high net peak intensities as well as a high peak-to-background ratio and, consequently, a high level of detection capability, the discriminator settings should be optimized quite carefully. In this manner, we were able to resolve the three α doublets and estimate α2/α1 intensity ratios. Inexplicably, current monographs, e.g., by Goldstein et al, do not contain any indications about the rational use of high order spectrometry. Only a few rather old monographs contain some hints in this regard
The real cycle class map
The classical cycle class map for a smooth complex variety sends cycles in the Chow ring to cycles in the singular cohomology ring. We study two cycle class maps for smooth real varieties: the map from the I-cohomology ring to singular cohomology induced by the signature, and a new cycle class map defined on the Chow-Witt ring. For both maps, we establish basic compatibility results like compatibility with pullbacks, pushforwards and cup products. As a first application of these general results, we show that both cycle class maps are isomorphisms for cellular varieties
Initial beam-profiling tests with the NML prototype station at the Fermilab A0 Photoinjector
The beam-profile diagnostics station prototype for the superconducting rf
electron linac being constructed at Fermilab at the New Muon Lab has been
tested. The station uses intercepting radiation converter screens for the
low-power beam mode: either a 100-\mu m thick YAG:Ce single crystal
scintillator or a 1-\mu m thin Al optical transition radiation (OTR) foil. The
screens are oriented with the surface perpendicular to the beam direction. A
downstream mirror with its surface at 45 degrees to the beam direction is used
to direct the radiation into the optical transport. The optical system has
better than 20 (10) \mu m rms spatial resolution when covering a vertical field
of view of 18 (5) mm. The initial tests were performed at the A0 Photoinjector
at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for
beam sizes of 45 to 250 microns. Example results will be presented.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1
Apr 2011. New York, US
Gastropods from the Jurassic neptunian sills of Rocca Busambra (north-western Sicily, Italy): Patellogastropoda, Pleurotomarioidea, Scissurelloidea, Fissurelloidea and Eucycloidea
The gastropods from Jurassic neptunian sills of Rocca Busambra (Sicily, Italy) represent an extraordinary assemblage for richness and extremely high degree of novelty, consisting of about 250 species (two-thirds of which are new) of 20 superfamilies. A total of 38 species and 18 genera of Lottioidea, Pleurotomarioidea, Scissurelloidea, Fissurelloidea and Eucycloidea are described. Of these, 30 species and 9 genera are new, namely Ramusatomaria nuda gen. et sp. nov., Trapanimaria gattoi gen. et sp. nov., Trapanimaria nicolosiensis gen. et sp. nov., Trapanimaria? pallinii gen. et sp. nov., Trochotomaria conoidea sp. nov., Trochotomaria polymorpha sp. nov., Laevitomaria babalusciae sp. nov., Pyrgotrochus vorosi sp. nov., Auritoma lenticula gen. et sp. nov., Busambrella fasciata gen. et sp. nov., Emarginula (Emarginula) burgioi sp. nov., Emarginula (Tauschia) acutidens sp. nov., Propeucyclus sicanus gen. et sp. nov., Propeucyclus obesus gen. et sp. nov., Propeucyclus? semireticulatus gen. et sp. nov., Eucyclomphalus? marenostrum sp. nov., Toronyella lineata gen. et sp. nov., Toronyella margaritata gen. et sp. nov., Zarnglaffia polygonalis sp. nov., Zarnglaffia palermitana sp. nov., Ambercyclus cratisculptus sp. nov., Elymicyclus alternatus gen. et sp. nov., Elymicyclus ietumensis gen. et sp. nov., Elymicyclus martae gen. et sp. nov., Elymicyclus garibaldii gen. et sp. nov., Jurassiscala sturanii gen. et sp. nov., Jurassiscala? tenuiretis gen. et sp. nov., Fischeriella sicula sp. nov., Retimusina poseidoni gen. et sp. nov. and Retimusina? tritoni sp. nov. The new scissurelloidean family Auritomidae fam. nov. is erected. A palaeobiogeographical analysis indicates close relationships with coeval faunas from condensed pelagic carbonates of the central region of western Tethys
Computersimulation zur Verifizierung und Präsentation eines automatisch gesteuerten Mamma-Biopsiesystems
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Die computerunterstützte Simulations- und Animationstechnik ist ein allgemein anerkanntes Hilfsmittel bei der Planung und Realisierung von technischen Systemen. Der Schwerpunkt des Simulations- und Animationseinsatzes lag ursprünglich nur auf der Planungsabsicherung. Zunehmend wird die Simulation und Animation durchgängig in allen Phasen des Planungs- und Realisierungsprozesses genutzt. In einem Forschungsprojekt wurde eine neuartige automatisch gesteuerte Einrichtung zur präzisen Navigation medizinischer Instrumente innerhalb von MRTomographen, insbesondere zur histologischen Sicherung von Kleintumoren, entwickelt. Die gesamte Einrichtung läßt sich gemeinsam mit einem Patienten im Untersuchungsbereich eines MR-Tomographen positionieren. Mittels einer SD-Simulation wie auch Animation konnte eine Überprüfung und Optimierung des komplexen Gesamtsystems, d.h. der einzelnen Systemkomponenten und deren kinematischen Bewegungsabläufe erfolgen. Desweiteren wurde damit eine Grundlage für die Erstellung einer Präsentationsvorlage realisiert, um der Öffentlichkeit die einzelnen Ablaufvorgänge einfach und plausibel darzustellen und zukünftige Anwender in dieses System schnell einzuweisen
Stochastic analysis of different rough surfaces
This paper shows in detail the application of a new stochastic approach for
the characterization of surface height profiles, which is based on the theory
of Markov processes. With this analysis we achieve a characterization of the
scale dependent complexity of surface roughness by means of a Fokker-Planck or
Langevin equation, providing the complete stochastic information of multiscale
joint probabilities. The method is applied to several surfaces with different
properties, for the purpose of showing the utility of this method in more
details. In particular we show the evidence of Markov properties, and we
estimate the parameters of the Fokker-Planck equation by pure, parameter-free
data analysis. The resulting Fokker-Planck equations are verified by numerical
reconstruction of conditional probability density functions. The results are
compared with those from the analysis of multi-affine and extended multi-affine
scaling properties which is often used for surface topographies. The different
surface structures analysed here show in details advantages and disadvantages
of these methods.Comment: Minor text changes to be identical with the published versio
- …