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Selected Abstracts(,6 -Arene)ruthenium(N-heterocyclic carbene) Complexes for the Chelation-Assisted Arylation and Deuteration of Arylpyridines: Catalytic Studies and Mechanistic InsightsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Amparo Prades Abstract A series of (,6 -arene)ruthenium complexes have been tested in the arylation of arylpyridines. One (,6 - p -cymene)ruthenium(N-heterocyclic carbene) complex (labelled as 1 in the text) was found to be the most effective, being capable of arylating a wide set of substantially different arylpyridines. Complex 1 is also able to promote the regioselective deuteration of a series of arylated N-heterocycles, via a nitrogen-directed mechanism. Two of the deuterated amines were used to measure the kinetic isotope effect (KIE) in the arylation process. The detection of an inverse KIE, together with the observation that the CH activation process does not require the addition of a base, suggest that the rate-limiting step in the arylation process may be different to that of previously reported studies. [source] Localization of mobile robots: Development and comparative evaluation of algorithms based on odometric and inertial sensorsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 12 2005G. Ippoliti An autonomous mobile robot must be able to elaborate the measures provided by the sensor equipment to localize itself with respect to a coordinate system. The precision of the location estimate depends on the sensor accuracy and on the reliability of the measure processing algorithm. The purpose of this article is to propose a low cost positioning system using internal sensors like odometers and optical fiber gyroscopes. Three simple localization algorithms based on different sensor data processing procedures are presented. Two of them operate in a deterministic framework, the third operates in a stochastic framework where the uncertainty is induced by sensing and unmodeled robot dynamics. The performance of the proposed localization algorithms are tested through a wide set of laboratory experiments and compared in terms of localization accuracy and computational cost. © 2005 Wiley Periodicals, Inc. [source] Does early adolescent sex cause depressive symptoms?JOURNAL OF POLICY ANALYSIS AND MANAGEMENT, Issue 4 2006Joseph J. Sabia A recent study by the Heritage Foundation (Rector, Johnson, & Noyes, 2003) found evidence of a positive relationship between early sexual intercourse and depressive symptoms. This finding has been used to bolster support for funding abstinenceonly sex education. However, promoting abstinence will only yield mental health benefits if there is a causal link between sexual intercourse and depression. Using the National Longitudinal Study of Adolescent Health (Add Health), I carefully examine the relationship between early teen sex and several measures of depression. Controlling for a wide set of individuallevel and familylevel observable characteristics, crosssection estimates consistently show a significant positive relationship between early sexual activity for females and three measures of adverse mental health: selfreported depression, a belief that one's life is not worth living, and serious thoughts of suicide. However, differenceindifference estimates reflect no evidence of a significant relationship between early teen sex and depressive symptoms. These findings suggest that the positive association observed by Rector et al. (2003) can be explained by unmeasured heterogeneity. Thus, promoting abstinence among adolescents is unlikely to alleviate depressive symptoms.© 2006 by the Association for Public Policy Analysis and Management. [source] Supply, Factor Shares and Inflation Persistence: Re-examining Euro-area New-Keynesian Phillips Curves,OXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 2004Peter McAdam Abstract Using euro-area data, we re-examine the empirical success of New-Keynesian Phillips curves (NKPCs). We re-estimate with a suitably specified optimizing supply side (which attempts to treat non-stationarity in factor income shares and mark-ups) that allows us to derive estimates of technology parameters, marginal costs and ,price gaps'. Our resulting estimates of the euro-area NKPCs are robust, provide reasonable estimates for fixed-price durations and discount rates and embody plausible dynamic properties. Our method for identifying the underlying determinants of NKPCs has general applicability to a wide set of countries as well as of use for sectoral studies. [source] The (Fo,Fc) Fourier synthesis: a probabilistic studyACTA CRYSTALLOGRAPHICA SECTION A, Issue 5 2008Rocco Caliandro (Fo,Fc) and (2Fo,Fc) Fourier syntheses are considered the most powerful tools for recovering the remainder of a structure and for correcting crystal structure models. A probabilistic approach has been applied to derive the formula for the variance for the expected value of the coefficient (Fo,Fc). This has allowed a better understanding of the features of the difference Fourier synthesis; in particular, a subset of well phased reflections has been separated from the subset of reflections best phased by the standard Fo Fourier synthesis. An iterative procedure, based on the electron-density modification of the difference Fourier map, has been devised which aims to improve phase and modulus estimates of the reflections with higher variance value, by using as lever arm the set of reflections with lower variance value. The new procedure (DEDM) has been implemented and verified on a wide set of test structures, the partial models of which were obtained by molecular replacement or by automatic model-building routines applied to experimental electron-density maps. Phase and modulus estimates of the difference Fourier syntheses improve in all the test cases; as a consequence, the quality of the difference Fourier maps also improves in the region where the target structure deviates from the partial model. A new procedure is suggested, combining DEDM with standard electron-density modification techniques, which leads to significant reduction of the phase errors. The procedure may be considered a starting point for further developments. [source] Forecasting Substantial Data Revisions in the Presence of Model Uncertainty,THE ECONOMIC JOURNAL, Issue 530 2008Anthony Garratt A recent revision to the preliminary measurement of GDP(E) growth for 2003Q2 caused considerable press attention, provoked a public enquiry and prompted a number of reforms to UK statistical reporting procedures. In this article, we compute the probability of ,substantial revisions' that are greater (in absolute value) than the controversial 2003 revision. The predictive densities are derived from Bayesian model averaging over a wide set of forecasting models including linear, structural break and regime-switching models with and without heteroscedasticity. Ignoring the nonlinearities and model uncertainty yields misleading predictives and obscures recent improvements in the quality of preliminary UK macroeconomic measurements. [source] Welfare reform in European countries: a microsimulation analysis,THE ECONOMIC JOURNAL, Issue 516 2007Herwig Immervoll This article compares the effects of increasing traditional welfare to introducing in-work benefits in the 15 (pre-enlargement) countries of the European Union. We use a labour supply model encompassing responses to taxes and transfers along both the intensive and extensive margins, and the EUROMOD microsimulation model to estimate current marginal and participation tax rates. We quantify the equity-efficiency trade-off for a range of elasticity parameters. In most countries, because of large existing welfare programmes with high phase-out rates, increasing traditional welfare is undesirable unless the redistributive tastes of the government are extreme. In contrast, the in-work benefit reform is desirable in a very wide set of cases. [source] | |||||||||||||