7,645 research outputs found

    Magnitude of visual accommodation to a head-up display

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    The virtual image symbology of head-up displays (HUDs) is presented at optical infinity to the pilot. This design feature is intended to help pilots maintain visual focus distance at optical infinity. However, the accommodation response could be nearer than optical infinity, due to an individual's dark focus response. Accommodation responses were measured of two age groups of airline pilots to: (1) static symbology on a HUD; (2) a landing site background at optical infinity; (3) the combination of the HUD symbology and the landing site background; and (4) complete darkness. Results indicate that magnitude of accommodation to HUD symbology, with and without the background, is not significantly different from an infinity focus response for either age group. The dark focus response is significantly closer than optical infinity for the younger pilots, but not the older pilots, a finding consistent with previous research

    K* resonance effects on direct CP violation in B -> pi pi K

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    Charged and neutral B decays into two charged pions and a charged or a neutral kaon are analyzed within the QCD factorization scheme where final state interactions before and after hadronization are included. The K*(892) and K*(1430) resonance effects are taken into account using the presently known pion-Kaon strange vector and scalar form factors. The weak decay amplitudes, which are calculated at leading power in Lambda_QCD/m_b and at the next-to-leading order in the strong coupling constant, include the hard scattering and annihilation contributions. The end point divergences of these weak final state interactions are controlled by two complex parameters determined through a fit to the available effective mass and helicity angle distribution, CP asymmetry and K*(892) branching ratio data. The predicted K*(1430) branching ratios and the calculated direct CP violation asymmetries are compared to the Belle and BABAR Collaboration data.Comment: Comments: 22 pages, 2 figures and 3 tables. In this new version, the results are unchanged, but, the last paragraph of the Section "RESULTS AND SUMMARY" (now called "RESULTS AND DISCUSSION") has been replaced by a new Section "SUMMARY AND OUTLOOK". To appear in Physical Review

    A sub-product construction of Poincare-Einstein metrics

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    Given any two Einstein (pseudo-)metrics, with scalar curvatures suitably related, we give an explicit construction of a Poincar\'e-Einstein (pseudo-)metric with conformal infinity the conformal class of the product of the initial metrics. We show that these metrics are equivalent to ambient metrics for the given conformal structure. The ambient metrics have holonomy that agrees with the conformal holonomy. In the generic case the ambient metric arises directly as a product of the metric cones over the original Einstein spaces. In general the conformal infinity of the Poincare metrics we construct is not Einstein, and so this describes a class of non-conformally Einstein metrics for which the (Fefferman-Graham) obstruction tensor vanishes.Comment: 23 pages Minor correction to section 5. References update

    Resonances and weak interactions in D+→π+π−π+D^+ \to\pi^+ \pi^- \pi^+ decays

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    We describe the ππ\pi\pi SS-wave in D+→π+π−π+D^+ \to\pi^+ \pi^- \pi^+ decays using a unitary model for the ππ\pi\pi Final State Interactions (FSI). The three body decay is treated as a quasi two-body process where, at the weak vertex, the D meson decays into a resonance and a pion. The weak part of the decay amplitude is evaluated using the effective weak Hamiltonian within the factorization approximation.Comment: 4 pages. Contribution to the X Hadron Physics, Florianopolis-Brazil, March 26-31, 200

    Plasmonic crystal demultiplexer and multiports

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    Artificially built periodic optical structures in dielectric and metallic media have generated considerable interest due to their potential for optical device miniaturization. In this context plasmonics, i.e., optics based on surface plasmon polaritons (SPPs) offers new exciting prospects. SPPs are hybrid light/electron surface waves at the interface between a dielectric and a metal and as such hold the potential for 2D optical functionality. Indeed, SPP elements as mirrors, splitters and interferometers have been recently demonstrated. However, for plasmonics to qualify at the information technology level requires necessarily the realization of wavelength division (demultiplexing) which constitutes a fundamental ingredient of optical communication. In the following we experimentally demonstrate 2D SPP demultiplexing in the visible spectral range by using photonic crystals for SPPs (plasmonic crystals). In addition, we demonstrate that plasmonic crystal are capable of realizing integrated linear multiports which could constitute building blocks of analog or quantum optical computing.Comment: Nano Lett.7, 1697 (2007

    Mol. Cell. Proteomics

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    Chemical cross-linking in combination with mass spectrometric analysis offers the potential to obtain low-resolution structural information from proteins and protein complexes. Identification of peptides connected by a cross-link provides direct evidence for the physical interaction of amino acid side chains, information that can be used for computational modeling purposes. Despite impressive advances that were made in recent years, the number of experimentally observed cross-links still falls below the number of possible contacts of cross-linkable side chains within the span of the cross-linker. Here, we propose two complementary experimental strategies to expand cross-linking data sets. First, enrichment of cross-linked peptides by size exclusion chromatography selects cross-linked peptides based on their higher molecular mass, thereby depleting the majority of unmodified peptides present in proteolytic digests of cross-linked samples. Second, we demonstrate that the use of proteases in addition to trypsin, such as Asp-N, can additionally boost the number of observable cross-linking sites. The benefits of both SEC enrichment and multiprotease digests are demonstrated on a set of model proteins and the improved workflow is applied to the characterization of the 20S proteasome from rabbit and Schizosaccharomyces pombe

    The Making of Cloud Applications An Empirical Study on Software Development for the Cloud

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    Cloud computing is gaining more and more traction as a deployment and provisioning model for software. While a large body of research already covers how to optimally operate a cloud system, we still lack insights into how professional software engineers actually use clouds, and how the cloud impacts development practices. This paper reports on the first systematic study on how software developers build applications in the cloud. We conducted a mixed-method study, consisting of qualitative interviews of 25 professional developers and a quantitative survey with 294 responses. Our results show that adopting the cloud has a profound impact throughout the software development process, as well as on how developers utilize tools and data in their daily work. Among other things, we found that (1) developers need better means to anticipate runtime problems and rigorously define metrics for improved fault localization and (2) the cloud offers an abundance of operational data, however, developers still often rely on their experience and intuition rather than utilizing metrics. From our findings, we extracted a set of guidelines for cloud development and identified challenges for researchers and tool vendors

    Time resolution of the Atlas Tile calorimeter and its performance for a measurement of heavy stable particles

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    Time resolution of the Atlas Tile calorimeter modules has been measured using the test beam data. The resolution depends on an energy deposited in a given cell and is equal to about 1.5 nsns at EE = 1 GeVGeV, 270 psps at EE = 25 GeVGeV (high gain), 700 psps at EE = 25 GeVGeV (low gain) and 170 psps at EE = 150 GeVGeV. These values have to be compared to the time of flight of relativistic particles to reach first samples of Tile calorimeter (from 8.3 nsns to 20 nsns). Time of Flight measurement using Tile Calorimeter can be used to identify, and combined with momentum measurements by Atlas inner detector, to measure the mass of exotic heavy stable particles. The results are compared to previous analysis using the Atlas muon spectrometercite{KRAAN2}
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