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Search Results: 1 - 10 of 1320 matches for " Olaf Nairz "
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Experimental verification of the Heisenberg uncertainty principle for hot fullerene molecules
Olaf Nairz,Markus Arndt,Anton Zeilinger
Physics , 2001, DOI: 10.1103/PhysRevA.65.032109
Abstract: The Heisenberg uncertainty principle for material objects is an essential corner stone of quantum mechanics and clearly visualizes the wave nature of matter. Here we report a demonstration of the Heisenberg uncertainty principle for the most massive, complex and hottest single object so far, the fullerene molecule C70 at a temperature of 900 K. We find a good quantitative agreement with the theoretical expectation: dx * dp = h, where dx is the width of the restricting slit, dp is the momentum transfer required to deflect the fullerene to the first interference minimum and h is Planck's quantum of action.
Diffraction of complex molecules by structures made of light
Olaf Nairz,Bj?rn Brezger,Markus Arndt,Anton Zeilinger
Physics , 2001, DOI: 10.1103/PhysRevLett.87.160401
Abstract: We demonstrate that structures made of light can be used to coherently control the motion of complex molecules. In particular, we show diffraction of the fullerenes C60 and C70 at a thin grating based on a standing light wave. We prove experimentally that the principles of this effect, well known from atom optics, can be successfully extended to massive and large molecules which are internally in a thermodynamic mixed state and which do not exhibit narrow optical resonances. Our results will be important for the observation of quantum interference with even larger and more complex objects.
"Interaction-Free" Imaging
Andrew G. White,Jay R. Mitchell,Olaf Nairz,Paul G. Kwiat
Physics , 1998, DOI: 10.1103/PhysRevA.58.605
Abstract: Using the complementary wave- and particle-like natures of photons, it is possible to make ``interaction-free'' measurements where the presence of an object can be determined with no photons being absorbed. We investigated several ``interaction-free'' imaging systems, i.e. systems that allow optical imaging of photosensitive objects with less than the classically expected amount of light being absorbed or scattered by the object. With the most promising system, we obtained high-resolution (10 \mu m), one-dimensional profiles of a variety of objects (human hair, glass and metal wires, cloth fibers), by raster scanning each object through the system. We discuss possible applications and the present and future limits for interaction-free imaging.
Robotic-based carbon ion therapy and patient positioning in 6 degrees of freedom: setup accuracy of two standard immobilization devices used in carbon ion therapy and IMRT
Alexandra D Jensen, Marcus Winter, Sabine P Kuhn, Jürgen Debus, Olaf Nairz, Marc W Münter
Radiation Oncology , 2012, DOI: 10.1186/1748-717x-7-51
Abstract: Position verifications in patients treated with carbon ion therapy and IMRT for head and neck malignancies were evaluated. Most patients received combined treatment regimen (IMRT plus carbon ion boost), immobilization was achieved with either Scotchcast or thermoplastic head masks. Position corrections in robotic-based carbon ion therapy allowing 6 DOF were compared to IMRT allowing corrections in 3 DOF for two standard immobilization devices. In total, 838 set-up controls of 38 patients were analyzed.Robotic-based position correction including correction of rotations was well tolerated and without discomfort. Standard deviations of translational components were between 0.5 and 0.8 mm for Scotchcast and 0.7 and 1.3 mm for thermoplastic masks in 6 DOF and 1.2 - 1.4 mm and 1.0 - 1.1 mm in 3 DOF respectively. Mean overall displacement vectors were between 2.1 mm (Scotchcast) and 2.9 mm (thermoplastic masks) in 6 DOF and 3.9 - 3.0 mm in 3 DOF respectively. Displacement vectors were lower when correction in 6 DOF was allowed as opposed to 3 DOF only, which was maintained at the traditional action level of > 3 mm for position correction in the pre-on-board imaging era.Setup accuracy for both systems was within the expected range. Smaller shifts were required when 6 DOF were available for correction as opposed to 3 DOF. Where highest possible positioning accuracy is required, frequent image guidance is mandatory to achieve best possible plan delivery and maintenance of sharp gradients and optimal normal tissue sparing inherent in carbon ion therapy.High-precision radiotherapy has raised the interest in positioning systems allowing patient positioning in more than three degrees of freedom (3DOF). Initial investigations have been carried out using the automated HexaPOD in combination with MV-cone-beam CT online correction [1,2], and some particle therapy centers have reported experiences with robotic-based treatment tables also enabling positioning in six degrees of freedom
A reverse genetic screen in Drosophila using a deletion-inducing mutagen
Knud Nairz, Peder Zipperlen, Charles Dearolf, Konrad Basler, Ernst Hafen
Genome Biology , 2004, DOI: 10.1186/gb-2004-5-10-r83
Abstract: The fruitfly Drosophila melanogaster has been the prime genetic model organism for almost a century. This success story is mainly founded on countless so-called forward genetic screens designed to elucidate gene functions on the basis of their mutant phenotypes. Many of those screens reached a scale that has been termed 'saturating' as they identify all nonredundant genes involved in a certain phenotypic trait. However, forward genetic screens are limited in that they are only capable of uncovering functions that are easily measurable or visible. Furthermore, genes having a redundant or nonessential role are less likely to be found by forward genetics.The reverse genetic approach to unravel gene function starts with the DNA sequence. Mutations within the gene are induced and identified by various techniques and only subsequently is the mutant phenotype analyzed [1]. Reverse genetics may be undirected or directed, the undirected approach involving random mutagenesis, commonly by transposable elements or by chemicals, the establishment of mutant collections, and the identification of mutations in the gene of interest [2-5]. In contrast, directed reverse genetics is based on techniques that allow for specific inactivation of a gene. These include specific knockdown of gene activities through RNA-mediated interference (RNAi) [6,7] and targeted gene disruption [8,9].Both undirected and directed reverse genetic techniques have certain advantages and drawbacks. Transposon-based mutagenesis tends to be nonrandom because of the occurrence of hotspots for transposon integration. The use of transposable elements of different origin, such as P-elements and piggyBac, which exhibit a different insertion bias, can partly circumvent this problem. However despite large-scale efforts, the ultimate goal of covering the whole Drosophila genome by insertion mutagenesis is far from being achieved [10,11]. Moreover, while null mutants of P-element-tagged genes (P-elements have the tendenc
Exact Black-Hole Solution With Self-Interacting Scalar Field
Olaf Bechmann,Olaf Lechtenfeld
Physics , 1995, DOI: 10.1088/0264-9381/12/6/013
Abstract: Einstein gravity minimally coupled to a self-interacting scalar field is investigated in the static and isotropic situation. We explicitly construct in partially closed form a new black-hole solution with exponentially decaying scalar hair. The symmetric interaction potential has both signs and a triple-well shape with a smooth but non-analytic minimum at vanishing field. We present numerical data as well as double series expansions around spatial infinity.
Exploratory disease mapping: kriging the spatial risk function from regional count data
Olaf Berke
International Journal of Health Geographics , 2004, DOI: 10.1186/1476-072x-3-18
Abstract: To circumvent these critics one may use kriging along with already smoothed regional estimates, where smoothing is based on empirical Bayes estimates, also known as shrinkage estimates. The empirical Bayes step has the advantage of shrinking the unstable and often extreme estimates to the global or local mean, and also has a stabilising effect on variance by borrowing strength, as well. Negative interpolates are prevented by choice of the appropriate kriging method. The proposed mapping method is applied to the North Carolina SIDS data example as well as to an example data set from veterinary epidemiology. The SIDS data are modelled without spatial trend. And spatial interpolation is based on ordinary kriging. The second example is included to demonstrate the method when the phenomenon under study exhibits a spatial trend and interpolation is based on universal kriging.Interpolation of the regional estimates overcomes the areal bias problem and the resulting isopleth maps are easier to read than choropleth maps. The empirical Bayesian estimate for smoothing is related to internal standardization in epidemiology. Therefore, the proposed concept is easily communicable to map users.As with the analysis of any set of data, it is always good practice to begin by producing and inspecting graphs. A feel for the data can then be obtained and any outstanding features identified. In spatial epidemiology this is called disease mapping. Bithel [7], Diggle [14] and Lawson [25] provide recent reviews of disease mapping. Spatial epidemiology comprises at least three types of study focus [17,25]. These are (i) disease mapping, (ii) disease clustering and (iii) geographical correlation analysis but these distinctions are not strict. For example a disease map is also used for reporting the results of a geographical correlation study or to highlight areas of high or low disease incidence, i.e. cluster locations in a cluster study [4,14]. But in the following, disease mapping is consid
Adopting the Precautionary Principle in Designing and Managing Natura 2000 Areas (Exemplified by the Conservation of the Butterfly Maculinea Nausithous in a Rural Landscape North of Dresden (Saxony))
Olaf Bastian
Journal of Landscape Ecology , 2008, DOI: 10.2478/v10285-012-0002-7
Abstract: The precautionary principle is more and more incorporated into national law and decision-making on natural resource management and biodiversity conservation. In the coherent European network of protected areas Natura 2000, the precautionary principle finds expression in the obligation to provide favourable conditions for the long-term survival of species and habitats, especially of the priority ones listed in the annexes of the Habitats Directive and the Birds Directive. After describing principles, structure, implementation and procedures of this rather new instrument for nature conservation using the example of one of the various Natura 2000 areas in Saxony (Germany), opportunities and problems for biodiversity conservation are outlined with particular regard for the situation in an agricultural landscape. Special attention is given to the following questions: requirements of and actual threats to the target species (the butterfly Maculinea nausithous), legal means and economic incentives for suitable measures, the management plan, and the role of stakeholders. It turns out that Natura 2000 could be an effective tool to advance nature conservation, and with special regard to the precautionary principle. Every effort is necessary to gain more public acceptance of Natura 2000, as well as to improve scientific knowledge concerning species and habitats under protection.
Gibt es die Stadt noch – und welche Bibliothek braucht sie?
Olaf Eigenbrodt
Libreas : Library Ideas , 2007,
Nachdenken über den Raum der Bibliothek aus ikonologischer Perspektive
Olaf Eigenbrodt
Libreas : Library Ideas , 2009,
Abstract: Rezension zu Petra Hauke: Domus Sapientiae: Ein Beitrag zur Ikonologie der Bibliotheksraumgestaltung des 17./18. Jahrhunderts unter besonderer Berücksichtigung des Klosters St. Mang, Füssen. Bad Honnef: Bock + Herchen, 2007 (Beitr ge zur Bibliotheks- und Informationswissenschaft; 2). 258 Seiten: zahlreiche Illustrationen. – broschiert 34,80 €, ISBN-13: 978-3883472584
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