6,462 research outputs found

    Port-site metastases in laparoscopic surgery: An experimental study

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    __Abstract__ Endoscopic imaging and instrumentation have allowed revolutionary changes in surgery. For many decades, in spite of pivotal improvements in and around surgery, the surgeon's hands and relatively simple instruments were the key elements of operative procedures. Manipulating tissues by hands and instruments under direct vision involves traumatizing healthy tissues. Avoiding undue tissue trauma is the goal of endoscopic surgery

    Kondo effect of Co adatoms on Ag monolayers on noble metal surfaces

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    The Kondo temperature TKT_K of single Co adatoms on monolayers of Ag on Cu and Au(111) is determined using Scanning Tunneling Spectroscopy. TKT_K of Co on a single monolayer of Ag on either substrate is essentially the same as that of Co on a homogenous Ag(111) crystal. This gives strong evidence that the interaction of surface Kondo impurities with the substrate is very local in nature. By comparing TKT_K found for Co on Cu, Ag, and Au (111)-surfaces we show that the energy scale of the many-electron Kondo state is insensitive to the properties of surface states and to the energetic position of the projected bulk band edges.Comment: 4 pages, 3 figure

    Many-core applications to online track reconstruction in HEP experiments

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    Interest in parallel architectures applied to real time selections is growing in High Energy Physics (HEP) experiments. In this paper we describe performance measurements of Graphic Processing Units (GPUs) and Intel Many Integrated Core architecture (MIC) when applied to a typical HEP online task: the selection of events based on the trajectories of charged particles. We use as benchmark a scaled-up version of the algorithm used at CDF experiment at Tevatron for online track reconstruction - the SVT algorithm - as a realistic test-case for low-latency trigger systems using new computing architectures for LHC experiment. We examine the complexity/performance trade-off in porting existing serial algorithms to many-core devices. Measurements of both data processing and data transfer latency are shown, considering different I/O strategies to/from the parallel devices.Comment: Proceedings for the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP); missing acks adde

    Kondo temperature of magnetic impurities at surfaces

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    Based on the experimental observation, that only the close vicinity of a magnetic impurity at metal surfaces determines its Kondo behaviour, we introduce a simple model which explains the Kondo temperatures observed for cobalt adatoms at the (111) and (100) surfaces of Cu, Ag, and Au. Excellent agreement between the model and scanning tunneling spectroscopy (STS) experiments is demonstrated. The Kondo temperature is shown to depend on the occupation of the d-level determined by the hybridization between adatom and substrate with a minimum around single occupancy.Comment: 4 pages, 2 figure

    Towards more effective identification keys: A study of people identifying plant species characters

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    Abstract Accurate species identification is essential for ecological monitoring and biodiversity conservation. Interactive plant identification keys have been considerably improved in recent years, mainly by providing iconic symbols, illustrations, or images for the users, as these keys are also commonly used by people with relatively little plant knowledge. Only a few studies have investigated how well morphological characteristics can be recognized and correctly identified by people, which is ultimately the basis of an identification key's success. This study consists of a systematic evaluation of people's abilities in identifying plant‚Äźspecific morphological characters. We conducted an online survey where 484 participants were asked to identify 25 different plant character states on six images showing a plant from different perspectives. We found that survey participants correctly identified 79% of the plant characters, with botanical novices with little or no previous experience in plant identification performing slightly worse than experienced botanists. We also found that flower characters are more often correctly identified than leaf characteristics and that characters with more states resulted in higher identification errors. Additionally, the longer the time a participant needed for answering, the higher the probability of a wrong answer. Understanding what influences users' plant character identification abilities can improve the development of interactive identification keys, for example, by designing keys that adapt to novices as well as experts. Furthermore, our study can act as a blueprint for the empirical evaluation of identifications keys. Read the free Plain Language Summary for this article on the Journal blog

    Disjoint minimal graphs

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    We prove that the number s(n) of disjoint minimal graphs supported on domains in R^n is bounded by e(n+1)^2. In the two-dimensional case we show that s(2) is at most three (the conjectured number is two).Comment: 14 page

    Commissioning of the CMS High Level Trigger

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    The CMS experiment will collect data from the proton-proton collisions delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to 14 TeV. The CMS trigger system is designed to cope with unprecedented luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger architecture only employs two trigger levels. The Level-1 trigger is implemented using custom electronics, while the High Level Trigger (HLT) is based on software algorithms running on a large cluster of commercial processors, the Event Filter Farm. We present the major functionalities of the CMS High Level Trigger system as of the starting of LHC beams operations in September 2008. The validation of the HLT system in the online environment with Monte Carlo simulated data and its commissioning during cosmic rays data taking campaigns are discussed in detail. We conclude with the description of the HLT operations with the first circulating LHC beams before the incident occurred the 19th September 2008

    Platinum Group Metal-Doped Tungsten Phosphates for Selective C-H Activation of Lower Alkanes

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    Platinum group metal (PGM)-based catalysts are known to be highly active in the total combustion of lower hydrocarbons. However, through an alternative catalyst design reported in this paper by isolating PGM-based active sites in a tungsten phosphate matrix, we present a class of catalysts for selective oxidation of n-butane, propane, and propylene that do not contain Mo or V as redox-active elements. Two different catalyst concepts have been pursued. Concept A: isolating Ru-based active sites in a tungsten phosphate matrix coming upon as ReO3-type structure. Concept B: dilution of PGM-based active sites through the synthesis of X-ray amorphous Ru tungsten phosphates supported on SiO2. Using a high-throughput screening approach, model catalysts over a wide compositional range were evaluated for C3 and C4 partial oxidation. Bulk crystalline and supported XRD amorphous phases with similar Ru/W/P compositions showed comparable performance. Hence, for these materials, composition is more crucial than the degree of crystallinity. Further studies for optimization on second-generation supported systems revealed even better results. High selectivity for n-butane oxidation to maleic anhydride and propane oxidation to an acrolein/acrylic acid has been achieved

    The Apollo ATCA Platform

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    We have developed a novel and generic open-source platform - Apollo - which simplifies the design of custom Advanced Telecommunications Computing Architecture (ATCA) blades by factoring the design into generic infrastructure and application-specific parts. The Apollo "Service Module" provides the required ATCA Intelligent Platform Management Controller, power entry and conditioning, a powerful system-on-module (SoM) computer, and flexible clock and communications infrastructure. The Apollo "Command Module" is customized for each application and typically includes two large field-programmable gate arrays, several hundred optical fiber interfaces operating at speeds up to 28 Gbps, memories, and other supporting infrastructure. The command and service module boards can be operated together or independently on the bench without need for an ATCA shelf.Comment: Submitted to the Proceedings for TWEPP 201
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