789 research outputs found
Picosecond time-resolved pure-rotational coherent anti-Stokes Raman spectroscopy for N-2 thermometry
This paper was published in Optics Letters and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=ol-34-23-3755. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Peer reviewedPublisher PD
Sizing of single fluorescently stained DNA fragments by scanning microscopy
We describe an approach to determine DNA fragment sizes based on the fluorescence detection of single adsorbed fragments on specifically coated glass cover slips. The brightness of single fragments stained with the DNA bisintercalation dye TOTOâ1 is determined by scanning the surface with a confocal microscope. The brightness of adsorbed fragments is found to be proportional to the fragment length. The method needs only minute amount of DNA, beyond inexpensive and easily available surface coatings, like polyâlâlysine, 3âaminoproyltriethoxysilane and polyornithine, are utilizable. We performed DNAâsizing of fragment lengths between 2 and 14 kb. Further, we resolved the size distribution before and after an enzymatic restriction digest. At this a separation of buffers or enzymes was unnecessary. DNA sizes were determined within an uncertainty of 7-14%. The proposed method is straightforward and can be applied to standardized microtiter plate
Politische Kommunikation zwischen politischen Eliten und Bevölkerung: Leitfaden fĂŒr eine sicherheitspolitische Debatte in Deutschland
"Sicherheitspolitik wird von den politischen Eliten in Deutschland auch heute noch wie ein ungeliebtes Stiefkind der politischen Kommunikation behandelt. Die Bundesrepublik hat sich jedoch seit der Wiedervereinigung in ihrem auĂen- und sicherheitspolitischen Agieren fundamental verĂ€ndert. Waren die ersten AuslandseinsĂ€tze der Bundeswehr noch von langen Debatten begleitet, so stehen deren StreitkrĂ€fte heute an zahlreichen Orten der Welt im Einsatz. Eine in einen offenen Kommunikationsprozess eingebettete BegrĂŒndung dafĂŒr erfolgte jedoch von Seiten der verantwortlichen Akteure nicht. Die Bundesregierung entscheidet sich bewusst fĂŒr ihr ziviles wie militĂ€risches Engagement im internationalen Krisenmanagement mit den dazugehörigen Kosten und Risiken. Da BeschlĂŒsse in einem so sensiblen Politikfeld jedoch nicht abgekoppelt von der Gesellschaft stattfinden dĂŒrfen, gilt es, ĂŒber eine pro-aktive und konsequente Vermittlungsarbeit die Entscheidungen und die sich daraus ergebenden Konsequenzen gegenĂŒber dem BĂŒrger ĂŒberzeugend zu vertreten und zu verantworten. Nur durch einen offenen Kommunikationsprozess kann die UnterstĂŒtzung und Legitimation fĂŒr politische Handlungen erreicht werden. Wichtig hierfĂŒr sind nicht nur die Inhalte, sondern auch Form und Struktur des Dialogs." (Autorenreferat
Multi-Step Processing of Spatial Joins
Spatial joins are one of the most important operations for combining spatial objects of several relations. In this paper, spatial join processing is studied in detail for extended spatial objects in twodimensional data space. We present an approach for spatial join processing that is based on three steps. First, a spatial join is performed on the minimum bounding rectangles of the objects returning a set of candidates. Various approaches for accelerating this step of join processing have been examined at the last yearâs conference [BKS 93a]. In this paper, we focus on the problem how to compute the answers from the set of candidates which is handled by
the following two steps. First of all, sophisticated approximations
are used to identify answers as well as to filter out false hits from
the set of candidates. For this purpose, we investigate various types
of conservative and progressive approximations. In the last step, the
exact geometry of the remaining candidates has to be tested against
the join predicate. The time required for computing spatial join
predicates can essentially be reduced when objects are adequately
organized in main memory. In our approach, objects are first decomposed
into simple components which are exclusively organized
by a main-memory resident spatial data structure. Overall, we
present a complete approach of spatial join processing on complex
spatial objects. The performance of the individual steps of our approach
is evaluated with data sets from real cartographic applications.
The results show that our approach reduces the total execution
time of the spatial join by factors
Efficient Processing of Spatial Joins Using R-Trees
Abstract: In this paper, we show that spatial joins are very suitable to be processed on a parallel hardware platform. The parallel system is equipped with a so-called shared virtual memory which is well-suited for the design and implementation of parallel spatial join algorithms. We start with an algorithm that consists of three phases: task creation, task assignment and parallel task execu-tion. In order to reduce CPU- and I/O-cost, the three phases are processed in a fashion that pre-serves spatial locality. Dynamic load balancing is achieved by splitting tasks into smaller ones and reassigning some of the smaller tasks to idle processors. In an experimental performance compar-ison, we identify the advantages and disadvantages of several variants of our algorithm. The most efficient one shows an almost optimal speed-up under the assumption that the number of disks is sufficiently large. Topics: spatial database systems, parallel database systems
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