We propose a new approach for vision based longitudinal and lateral vehicle control which makes extensive use of binocular stereopsis. Longitudinal control --- i.e. maintaining a safe, constant distance from the vehicle in front --- is supported by detecting and measuring the distances to leading vehicles using binocular stereo. A known camera geometry with respect to the locally planar road is used to map the images of the road plane in the two camera views into alignment. Any significant residual image disparity then indicates an object not lying in the road plane and hence a potential obstacle. This approach allows us to separate image features into those lying in the road plane, e.g. lane markers, and those due to other objects. The features which lie on the road are stationary in the scene and appear to move only because of the egomotion of the vehicle. Measurements on these features are used for dynamic update of (a) the camera parameters in the presence of camera vibration and changes in road slope (b) the lateral position of the vehicle with respect to the lane markers. In the absence of this separation, image features due to vehicles which happen to lie in the search zone for lane markers would corrupt the estimation of the road boundary contours. This problem has not yet been addressed by any lane marker based vehicle guidance approach, but has to be taken very seriously, since usually one has to cope with crowded traffic scenes where lane markers are often obstructed by vehicles. Lane markers are detected and used for lateral control, i.e. following the road while maintaining a constant lateral distance to the road boundary. For that purpose we model the road and hence the shape of the lane markers as clothoidal curves, the curvatures of which we estimate recursively along the image sequence. These curvature estimates also provide desirable look-ahead information for a smooth ride in the car.
The chemistry of titanocene bisborane complexes Cp2Ti(HBcat')2 (1a−g) (HBcat' = catecholborane or a substitued catecholborane) and monoborane complexes Cp2Ti(HBcat')(L) (2−4) (L = PMe3, PhSiH3, or PhCCPh) is reported. These complexes are unusual σ-complexes. The B−H bond in the catecholborane of 1 acts as a two-electron-donor ligand. The 4-tert-butyl version 1a was studied in depth and underwent ligand substitution reactions with PMe3, CO, PhSiH3, and PhCCPh. The products of the reaction of 1a with PMe3 and PhSiH3 are the novel monoborane σ-complexes Cp2Ti(HBcat')(PMe3) (2a; HBcat' = HBO2C6H3-4-t-Bu) and Cp2Ti(HBcat')(PhSiH3) (3; HBcat' = HBO2C6H3-4-t-Bu), in which the catecholborane remains a two-electron-donating ligand. Reaction with CO formed Cp2Ti(CO)2. Reaction with PhCCPh formed Cp2Ti(HBcat')(PhCCPh) (4; HBcat' = HBO2C6H3-4-t-Bu), which was observed in solution and reductively eliminated the vinyl boronate ester (Ph)(Bcat')CC(Ph)(H). The rates for the reactions of 1a with these substrates showed a first-order dependence on the concentration of 1a and a zero-order dependence on the concentrations of both the departing HBcat' and the incoming ligand. The substitution reaction proceeded at the same rate ((3.8 ± 0.3) × 10-4) regardless of the identity of the incoming ligand. The entropy of activation was +30 ± 5 eu. These data are consistent with a dissociative substitution mechanism for the reaction of 1a with these substrates. The ΔH⧧ value of 25 ± 3 kcal mol-1 for these reactions provides an upper limit for the strength of the borane−metal interaction. Electronic effects on the reaction rate support a bonding model involving back-donation from titanium to the borane, and the unusual steric effects allow a proposal for the geometric changes that occur upon formation of the transition state.
The single-operation deracemization of 3H indolines and tetrahydroquinolines is described. An asymmetric redox approach was employed, in which a phosphoric acid catalyst, oxidant, and reductant are present in the reaction mixture. The simultaneous presence of both oxidant and reductant was enabled by phase separation and resulted in the isolation of highly enantioenriched starting materials in high yields.
Overall, we were able to classify approximately 70 percent of hospital-led health networks and 90 percent of hospital-led health systems into well-defined organizational clusters. Given the widespread perception that organizational change in healthcare has been chaotic, our research suggests that important and meaningful similarities exist across many evolving organizations. The resulting taxonomy provides a new lexicon for researchers, policymakers, and healthcare executives for characterizing key strategic and structural features of evolving organizations. The taxonomy also provides a framework for future inquiry about the relationships between organizational strategy, structure, and performance, and for assessing policy issues, such as Medicare Provider Sponsored Organizations, antitrust, and insurance regulation.
Data center computing is becoming pervasive in many organizations. Computing frameworks such as MapRe-duce [17], Hadoop [6] and Dryad [25], split jobs into small tasks that are run on the cluster’s compute nodes.
Community-based participatory research (CBPR) increasingly is seen as a potent tool for studying and addressing urban environmental health problems by linking place-based work with efforts to help effect policy-level change. This paper explores a successful CBPR and organizing effort, the Toxic Free Neighborhoods Campaign, in Old Town National City (OTNC), CA, United States, and its contributions to both local policy outcomes and changes in the broader policy environment, laying the groundwork for a Specific Plan to address a host of interlocking community concerns. After briefly describing the broader research of which the OTNC case study was a part, we provide background on the Environmental Health Coalition (EHC) partnership and the setting in which it took place, including the problems posed for residents in this light industrial/residential neighborhood. EHC's strong in-house research, and its training and active engagement of promotoras de salud (lay health promoters) as co-researchers and policy change advocates, are described. We explore in particular the translation of research findings as part of a policy advocacy campaign, interweaving challenges faced and success factors and multi-level outcomes to which these efforts contributed. The EHC partnership's experience then is compared with that of other policy-focused CBPR efforts in urban environmental health, emphasizing common success factors and challenges faced, as these may assist other partnerships wishing to pursue CBPR in urban communities.
<p>Evapotranspiration (E<sub>ET</sub>) observed by eddy covariance (EC) towers is composed of physical evaporation (E<sub>E</sub>) from wet surfaces and biological transpiration (E<sub>T</sub>), that involves soil moisture uptake by roots and water vapor transfer regulated through the canopy-stomatal conductance (g<sub>C</sub>) during photosynthesis. E<sub>T</sub> plays a dominant role in the global water cycle and represents 80% of the total terrestrial E<sub>ET</sub>. Understanding the magnitude and variability of E<sub>T</sub> are critical to assess the ecophysiological responses of vegetation to drought. While separating E<sub>T</sub> signals from lumped E<sub>ET</sub> observations and/or simulating E<sub>T</sub> by terrestrial systems models is insufficiently constrained owing to the large uncertainties in disentangling g<sub>C</sub> from the aggregated canopy-substrate conductance (g<sub>cS</sub>), evaluating ecosystem E<sub>T</sub> derived through partitioning E<sub>ET</sub> observations (or model simulation) is also challenging due to the absence of any ecosystem-scale measurements of this biotic flux and g<sub>C</sub>. To date, the main methods for partitioning EC-E<sub>ET</sub> observations are largely based on regressing E<sub>ET</sub> with gross photosynthesis (P<sub>g</sub>) and atmospheric vapor pressure deficit (D<sub>A</sub>) observations. However, such methods ignore the essential feedback of the surface energy balance (SEB) and canopy temperature (T<sub>C</sub>) on g<sub>C</sub> and E<sub>T</sub>.</p><p>This study demonstrates partitioning E<sub>ET</sub> observations into E<sub>T</sub> and E<sub>E</sub> [soil evaporation (E<sub>Es</sub>) and interception evaporation (E<sub>Ei</sub>)] through an ‘analytical solution’ of g<sub>C</sub>, T<sub>C</sub> and canopy vapor pressures by employing a Shuttleworth-Gurney vegetation-substrate energy balance model with minimal complexity. The model is called TRANSPIRE (Top-down partitioning evapotRANSPIRation modEl), which ingests remote sensing land surface temperature (LST) and leaf area index (L<sub>ai</sub>) information in conjunction with meteorological, sensible heat flux (H) and E<sub>ET</sub> observations from EC tower into the SEB equations for retrieving canopy and soil temperatures (T<sub>S</sub>, T<sub>C</sub>), g<sub>C</sub>, and E<sub>T</sub>.</p><p>E<sub>T</sub> estimates from TRANSPIRE were tested and evaluated with a remote sensing based E<sub>T</sub> estimate from an analytical model (STIC1.2), where lumped E<sub>ET</sub> was partitioned by employing a moisture availability constraints across an aridity gradient in the North Australian Tropical Transect (NATT) by using time-series of 8-day MODIS Terra LST and LAI products in conjunction with EC measurements from 2011 to 2018. Both methods captured the seasonal pattern of E<sub>T</sub>/E<sub>ET</sub> ratio in a very similar way. While E<sub>T</sub> accounted for 60±10% of the annual E<sub>ET</sub> in the tropical savanna, E<sub>T</sub> in the arid mulga contributed 75±12% of the annual E<sub>ET</sub>. Seasonal variation of E<sub>T</sub> was higher in the arid, semi-arid ecosystems (50 - 90%), as compared to the humid tropical ecosystem (10 - 50%). The TRANSPIRE model reasonably captured E<sub>T</sub> variations along with soil moisture and precipitation dynamics in both sparse and homogeneous vegetation and showed the potential of partitioning E<sub>ET</sub> observations for cross-site comparison with a variety of models.</p>
Synthesis of Saturated Five-Membered Nitrogen Heterocycles via Pd-Catalyzed C-N Bond-Forming Reactions Transition Metal Catalyzed Approaches to Lactones Involving C-O Bond Formation The Formation of Csp2-S and Csp2-Se Bonds by Substitution and Addition Reactions Catalyzed by Transition Metal Complexes Palladium-Catalysis for Oxidative 1,2-Difunctionalization of Alkenes Rhodium-Catalyzed C-H Aminations The Palladium Catalyzed Synthesis of Aromatic Heterocycles New Reactions of Copper Acetylides: Catalytic Dipolar Cycloadditions and Beyond Transition Metal-Catalyzed Synthesis of Monocyclic Five-Membered Aromatic Heterocycles Transition Metal-Catalyzed Synthesis of Fused Five-Membered Aromatic Heterocycles Carbon-Heteroatom Bond Formation by RhI-Catalyzed Ring-Opening Reactions Gold-Catalyzed Addition of Nitrogen and Sulfur Nucleophiles to C-C Multiple Bonds Gold-Catalyzed Addition of Oxygen Nucleophiles to C-C Multiple Bonds
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Sterically Hindered Chelating Alkyl Phosphines Provide Large Rate Accelerations in Palladium-Catalyzed Amination of Aryl Iodides, Bromides, and Chlorides, and the First Amination of Aryl TosylatesBlake C. Hamann and John F. HartwigView Author Information Department of Chemistry, Yale University P.O. Box 208107, New Haven, Connecticut 06520-8107 Cite this: J. Am. Chem. Soc. 1998, 120, 29, 7369–7370Publication Date (Web):July 11, 1998Publication History Received20 April 1998Published online11 July 1998Published inissue 1 July 1998https://pubs.acs.org/doi/10.1021/ja981318ihttps://doi.org/10.1021/ja981318irapid-communicationACS PublicationsCopyright © 1998 American Chemical SocietyRequest reuse permissionsArticle Views7031Altmetric-Citations322LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-AlertscloseSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Alkyls,Anions,Aromatic compounds,Ligands,Organic reactions Get e-Alerts
