303 research outputs found

    Concave Plasmonic Particles: Broad-Band Geometrical Tunability in the Near Infra-Red

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    Optical resonances spanning the Near and Short Infra-Red spectral regime were exhibited experimentally by arrays of plasmonic nano-particles with concave cross-section. The concavity of the particle was shown to be the key ingredient for enabling the broad band tunability of the resonance frequency, even for particles with dimensional aspect ratios of order unity. The atypical flexibility of setting the resonance wavelength is shown to stem from a unique interplay of local geometry with surface charge distributions

    Editorial: Videos in der (Hochschul-)Lehre

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    24.04.2014 | Thomas Antretter, Johannes Dorfinger, Martin Ebner, Michael Kopp, Walther Nagler, Jutta Pauschenwein, Michael Raunig, Manfred Rechberger, Herwig Rehatschek, Patrick Schweighofer, Reinhard Staber & Martin Teufel (Graz

    Efficient template attacks

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    This is the accepted manuscript version. The final published version is available from http://link.springer.com/chapter/10.1007/978-3-319-08302-5_17.Template attacks remain a powerful side-channel technique to eavesdrop on tamper-resistant hardware. They model the probability distribution of leaking signals and noise to guide a search for secret data values. In practice, several numerical obstacles can arise when implementing such attacks with multivariate normal distributions. We propose efficient methods to avoid these. We also demonstrate how to achieve significant performance improvements, both in terms of information extracted and computational cost, by pooling covariance estimates across all data values. We provide a detailed and systematic overview of many different options for implementing such attacks. Our experimental evaluation of all these methods based on measuring the supply current of a byte-load instruction executed in an unprotected 8-bit microcontroller leads to practical guidance for choosing an attack algorithm.Omar Choudary is a recipient of the Google Europe Fellowship in Mobile Security, and this research is supported in part by this Google Fellowship

    Development of robust metal-supported SOFCs and stack components in EU METSAPP consortium

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    The potential of MS-SOFCs was demonstrated through the previous EU METSOFC project, which concluded that the development of oxidation resistant novel metal-supported solid oxide fule cell (MS-SOFC) design and stack is the requirement to advance this technology to the next level. The following EU METSAPP project has been executed with an overall aim of developing advanced metal-supported cells and stacks based on a robust, reliable and up-scalable technology. During the project, oxidation resistant nanostructured anodes based on modified SrTiO3 were developed and integrated into MS-SOFCs to enhance their robustness. In addition, the manufacturing of metal-supported cells with different geometries, scalability of the manufacturing process was demonstrated and more than 200 cells with an area of ∼150 cm2 were produced. The electrochemical performance of different cell generations was evaluated and best performance and stability combination was observed with doped SrTiO3 based anode designs. Furthermore, numerical models to understand the corrosion behavior of the MS-SOFCs were developed and validated. Finally, the cost effective concept of coated metal interconnects was developed, which resulted in 90% reduction in Cr evaporation, three times lower Cr2O3 scale thickness and increased lifetime. The possibility of assembling these cells into two radically different stack designs was demonstrated

    Adiponutrin Functions as a Nutritionally Regulated Lysophosphatidic Acid Acyltransferase

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    SummaryNumerous studies in humans link a nonsynonymous genetic polymorphism (I148M) in adiponutrin (ADPN) to various forms of fatty liver disease and liver cirrhosis. Despite its high clinical relevance, the molecular function of ADPN and the mechanism by which I148M variant affects hepatic metabolism are unclear. Here we show that ADPN promotes cellular lipid synthesis by converting lysophosphatidic acid (LPA) into phosphatidic acid. The ADPN-catalyzed LPA acyltransferase (LPAAT) reaction is specific for LPA and long-chain acyl-CoAs. Wild-type mice receiving a high-sucrose diet exhibit substantial upregulation of Adpn in the liver and a concomitant increase in LPAAT activity. In Adpn-deficient mice, this diet-induced increase in hepatic LPAAT activity is reduced. Notably, the I148M variant of human ADPN exhibits increased LPAAT activity leading to increased cellular lipid accumulation. This gain of function provides a plausible biochemical mechanism for the development of liver steatosis in subjects carrying the I148M variant

    Transition from localized surface plasmon resonance to extended surface plasmon-polariton as metallic nanoparticles merge to form a periodic hole array

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    W. Andrew Murray, Simion Astilean, and William L. Barnes, Physical Review B, Vol. 69, article 165407 (2004). "Copyright © 2004 by the American Physical Society."We present results of experiments to determine the dispersion of the plasmon modes associated with periodic silver nanoparticle and nanohole arrays fabricated using an extension of the nanosphere lithography technique. Ordered monolayers of polystyrene nanospheres were used as a deposition mask through which silver was deposited by thermal evaporation, subsequent removal of the nanospheres thus leaving an array of metallic nanoparticles. By reactive-ion etching of the nanospheres in an oxygen plasma prior to silver deposition, arrays consisting of particles of increasing size were fabricated. The extremities of the particles eventually merge to create a continuous metallic network perforated by subwavelength holes, thus allowing a study of the particle-hole transition. Combining optical measurements of transmittance and reflectance with information gained using scanning electron microscopy, three separate regimes were observed. For low etch times the samples comprise mainly individual nanoparticles and the optical response is dominated by localized surface plasmon resonances that show no dispersion. As the etch time is increased almost all of the nanoparticles merge with adjacent particles, although many defects are present—notably where some particles fail to merge, a small gap being left between them. The presence of these defects prevents an abrupt structural transition from metallic nanoparticles to a continuous metallic film perforated by an array of nanoholes. The presence of such gaps also results in dispersion data that lack clearly defined features. A further increase in etch time leads to samples with no gaps: instead, a continuous metal film perforated by a nanohole array is produced. The optical response of these structures is dominated by extended surface plasmon-polariton modes
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