Oxygen adsorption on the Ru (10 bar 1 0) surface: Anomalous coverage dependence

Oxygen adsorption onto Ru (10 bar 1 0) results in the formation of two ordered overlayers, i.e. a c(2 times 4)-2O and a (2 times 1)pg-2O phase, which were analyzed by low-energy electron diffraction (LEED) and density functional theory (DFT) calculation. In addition, the vibrational properties of these overlayers were studied by high-resolution electron loss spectroscopy. In both phases, oxygen occupies the threefold coordinated hcp site along the densely packed rows on an otherwise unreconstructed surface, i.e. the O atoms are attached to two atoms in the first Ru layer Ru(1) and to one Ru atom in the second layer Ru(2), forming zigzag chains along the troughs. While in the low-coverage c(2 times 4)-O phase, the bond lengths of O to Ru(1) and Ru(2) are 2.08 A and 2.03 A, respectively, corresponding bond lengths in the high-coverage (2 times 1)-2O phase are 2.01 A and 2.04 A (LEED). Although the adsorption energy decreases by 220 meV with O coverage (DFT calculations), we observe experimentally a shortening of the Ru(1)-O bond length with O coverage. This effect could not be reconciled with the present DFT-GGA calculations. The nu(Ru-O) stretch mode is found at 67 meV [c(2 times 4)-2O] and 64 meV [(2 times 1)pg-2O].Comment: 10 pages, figures are available as hardcopies on request by mailing [email protected], submitted to Phys. Rev. B (8. Aug. 97), other related publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm

Optimization methods and their use in low-energy electron-diffraction calculations

The speed of automatic optimization procedures used in surface structure determination by low-energy electron diffraction can be greatly enhanced by the use of linear approximations in the calculation of scattering amplitudes. It is shown how linear approximations can be used in the calculation of derivatives of intensities which are required in the least-squares optimization method. The derivatives with respect to structural and nonstructural parameters are calculated applying a combination of analytic and numerical methods in connection with approximations of the sum over lattice points in the angular momentum representation. Special cases for different structural and nonstructural parameters and simplifications for special geometries are discussed. The computational effort becomes nearly independent of the number of free parameters and enables the analysis of complex surface structures

Symbiosis between the TRECVid benchmark and video libraries at the Netherlands Institute for Sound and Vision

Audiovisual archives are investing in large-scale digitisation efforts of their analogue holdings and, in parallel, ingesting an ever-increasing amount of born- digital files in their digital storage facilities. Digitisation opens up new access paradigms and boosted re-use of audiovisual content. Query-log analyses show the shortcomings of manual annotation, therefore archives are complementing these annotations by developing novel search engines that automatically extract information from both audio and the visual tracks. Over the past few years, the TRECVid benchmark has developed a novel relationship with the Netherlands Institute of Sound and Vision (NISV) which goes beyond the NISV just providing data and use cases to TRECVid. Prototype and demonstrator systems developed as part of TRECVid are set to become a key driver in improving the quality of search engines at the NISV and will ultimately help other audiovisual archives to offer more efficient and more fine-grained access to their collections. This paper reports the experiences of NISV in leveraging the activities of the TRECVid benchmark

Bounded-width polynomial-size branching programs recognize exactly those languages in NC1

AbstractWe show that any language recognized by an NC1 circuit (fan-in 2, depth O(log n)) can be recognized by a width-5 polynomial-size branching program. As any bounded-width polynomial-size branching program can be simulated by an NC1 circuit, we have that the class of languages recognized by such programs is exactly nonuniform NC1. Further, following Ruzzo (J. Comput. System Sci. 22 (1981), 365–383) and Cook (Inform. and Control 64 (1985) 2–22), if the branching programs are restricted to be ATIME(logn)-uniform, they recognize the same languages as do ATIME(log n)-uniform NC1 circuits, that is, those languages in ATIME(log n). We also extend the method of proof to investigate the complexity of the word problem for a fixed permutation group and show that polynomial size circuits of width 4 also recognize exactly nonuniform NC1

Environmental Impact Determinants: An Empirical Analysis based on the STIRPAT Model

AbstractThis paper attempt to investigate the impact of economic and population growth, urbanization level, energy intensity and Kyoto protocol obligations on carbon dioxide emissions using the STIRPAT model (STochastic Impacts by Regression on Population, Affluence and Technology). Our sample of countries is decomposed into groups according to the revenue level and the analyzed period extends from 1980 through 2010. Using several methods to estimate panel data, we find that there is a significant effect of economic growth, population growth, urbanization level and Kyoto protocol on emissions level and this effect depends on the revenue level

The role of sea-level change and marine anoxia in the Frasnian-Famennian (Late Devonian) mass extinction

Johnson et al. (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) proposed one of the first explicit links between marine anoxia, transgression and mass extinction for the Frasnian–Famennian (F–F, Late Devonian) mass extinction. This cause-and-effect nexus has been accepted by many but others prefer sea-level fall and cooling as an extinction mechanism. New facies analysis of sections in the USA and Europe (France, Germany, Poland), and comparison with sections known from the literature in Canada, Australia and China reveal several high-frequency relative sea-level changes in the late Frasnian to earliest Famennian extinction interval. A clear signal of major transgression is seen within the Early rhenana Zone (e.g. drowning of the carbonate platform in the western United States). This is the base of transgressive–regressive Cycle IId of the Johnson et al. (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) eustatic curve. This was curtailed by regression and sequence boundary generation within the early linguiformis Zone, recorded by hardground and karstification surfaces in sections from Canada to Australia. This major eustatic fall probably terminated platform carbonate deposition over wide areas, especially in western North America. The subsequent transgression in the later linguiformis Zone, recorded by the widespread development of organic-rich shale facies, is also significant because it is associated with the expansion of anoxic deposition, known as the Upper Kellwasser Event. Johnson et al.'s (Johnson, J.G., Klapper, G., Sandberg, C.A., 1985. Devonian eustatic fluctuations in Euramerica. Geological Society of America Bulletin 96, 567–587) original transgression-anoxia–extinction link is thus supported, although some extinction losses of platform carbonate biota during the preceeding regression cannot be ruled out. Conodont faunas suffered major losses during the Upper Kellwasser Event, with deep-water taxa notably affected. This renders unreliable any eustatic analyses utilising changes in conodont biofacies. Claims for a latest Frasnian regression are not supported, and probably reflect poor biostratigraphic dating of the early linguiformis Zone sequence boundary

Metastable precursors during the oxidation of the Ru(0001) surface

Using density-functional theory, we predict that the oxidation of the Ru(0001) surface proceeds via the accumulation of sub-surface oxygen in two-dimensional islands between the first and second substrate layer. This leads locally to a decoupling of an O-Ru-O trilayer from the underlying metal. Continued oxidation results in the formation and stacking of more of these trilayers, which unfold into the RuO_2(110) rutile structure once a critical film thickness is exceeded. Along this oxidation pathway, we identify various metastable configurations. These are found to be rather close in energy, indicating a likely lively dynamics between them at elevated temperatures, which will affect the surface chemical and mechanical properties of the material.Comment: 11 pages including 9 figures. Submitted to Phys. Rev. B. Related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

Evolution of the cosmic ray anisotropy above 10^{14} eV

The amplitude and phase of the cosmic ray anisotropy are well established experimentally between 10^{11} eV and 10^{14} eV. The study of their evolution into the energy region 10^{14}-10^{16} eV can provide a significant tool for the understanding of the steepening ("knee") of the primary spectrum. In this letter we extend the EAS-TOP measurement performed at E_0 around 10^{14} eV, to higher energies by using the full data set (8 years of data taking). Results derived at about 10^{14} and 4x10^{14} eV are compared and discussed. Hints of increasing amplitude and change of phase above 10^{14} eV are reported. The significance of the observation for the understanding of cosmic ray propagation is discussed.Comment: 4 pages, 3 figures, accepted for publication on ApJ Letter

The polypill in the primary prevention of cardiovascular disease: cost-effectiveness in the Dutch population

OBJECTIVES: The aim of the present study was to estimate the cost-effectiveness of the polypill in the primary prevention of cardiovascular disease. DESIGN: A health economic modeling study. SETTING: Primary health care in the Netherlands. PARTICIPANTS: Simulated individuals from the general Dutch population, aged 45-75 years of age. INTERVENTIONS: Opportunistic screening followed by prescription of the polypill to eligible individuals. Eligibility was defined as having a minimum 10-year risk of cardiovascular death as assessed with the SCORE function of alternatively 5%, 7.5%, or 10%. Different versions of the polypill were considered, depending on composition: 1) the Indian polycap, with three different types of blood pressure lowering drugs, a statin, and aspirin; 2) as 1) but without aspirin; 3) as 2) but with a double statin dose. In addition, a scenario of (targeted) separate antihypertensive and/or statin medication was simulated. PRIMARY OUTCOME MEASURES: Cases of acute myocardial infarction or stroke prevented, QALYs gained, and the costs per QALY gained. All interventions were compared with usual care. RESULTS: All scenarios were cost-effective with an incremental cost-effectiveness ratio between €7,900-12,300 per QALY compared with usual care. Most health gains were achieved with the polypill without aspirin and containing a double dose of statins. With a 10-year risk of 7.5% as threshold, this pill would prevent approximately 3.5% of all cardiovascular events. CONCLUSIONS: Opportunistic screening based on global cardiovascular risk assessment followed by polypill prescription to those with increased risk offers a cost-effective strategy. Most health gain is achieved by the polypill without aspirin and a double statin dose

Quality of life and symptom assessment in randomized clinical trials of bladder cancer: A systematic review

OBJECTIVES: Patient-reported outcomes (PRO) help patients, caretakers, clinicians, and policy makers make informed decisions regarding treatment effectiveness. Our objective was to assess the quality of PRO reporting and methodological strengths and weaknesses in randomized controlled trials (RCT) in bladder cancer.; METHODS: A systematic literature search of bladder cancer RCT published between January 2004 and March 2014 was performed. Relevant studies were evaluated using a predetermined extraction form that included trial demographics, clinical and PRO characteristics, and standards of PRO reporting based on recommendations of the International Society for Quality of Life Research.; RESULTS: In total, 9 RCTs enrolling 1,237 patients were evaluated. All studies were in patients with nonmetastatic disease. In 5 RCTs, a PRO was the primary end point. Most RCTs did not report the mode of administration of the PRO instrument or the methods of collecting data. No RCT addressed the statistical approaches for missing data.; CONCLUSIONS: We found that few RCTs in bladder cancer report PRO as an outcome. Efforts to expand PRO reporting to more RCTs and improve the quality of PRO reporting according to recognized standards are necessary for facilitating clinical decision making. Copyright 2015 Elsevier Inc. All rights reserved