10,000 publications from this institution
This article presents an extensive study on the selectivity, scope and structure-activity relations for the Pd-catalyzed amination of (het)aryl halides with primary amines. Aryl iodies, which are known to be more reluctant substrates to Pd-catalyzed amination, were also successfully converted.
An earlier procedure that estimates the peak deformation in base-isolated buildings is extended to include overturning and thereby estimate the peak axial forces in individual isolators. Such tools can be used as part of a design procedure to predict and subsequently eliminate bearing tension by modifying the design. The procedure is based on nonlinear response history analysis of an isolated block using an advanced bearing model that incorporates the relation between axial load and bearing response, known as axial-load effects. Rocking of the structure and bearing axial-load effects are found to have little influence on the peak lateral bearing deformation; median response spectra are within 10% of those when rocking is neglected entirely. Furthermore, bearing axial-load effects can usually be neglected in determining the maximum and minimum bearing axial forces; cases are identified where the error in neglecting such effects exceed 10%. Because the structure has been modeled as rigid, the limitations of the procedure should be assessed for superstructure designs that allow significant structural deformation.
Stomata are major conduits for the diffusion of many trace gas species between leaves and the atmosphere. The role of the stomata on controlling gas exchange between the terrestrial biosphere and the atmosphere at the landscape, meso- and global-scales has only recently been recognized. Further advances in modelling large-scale trace gas exchange will depend on our ability to understand and model stomatal mechanics at the scale of the pertinent sub-unit, which is typically that of the canopy. This paper describes two approaches for estimating canopy stomatal conductance. One approach is based on 'bottom-up' scaling. This approach computes canopy stomatal conductance by integrating detailed leaf-level and environmentally-driven, physiological processes with the use of a detailed canopy micrometeorology model. The other approach is based on 'top-down' scaling. It interprets the integrated canopy stomatal conductance from measured fluxes of trace gas exchange. Frameworks for extending these scaling approaches to non-idea conditions are given. 96 refs., 5 figs.
Abstract The enantioselective reaction of diethylzinc (II) with the benzaldehydes (I), yielding the alcohols (III), is catalyzed by polymer‐bound chiral amino alcohols.
Die gewaltige Expansion und Verstarkung der Aktivitaten der amerikanischen Polizei, der Strafgerichte sowie der Gefangnisse wahrend der letzten dreisig Jahre zielte erstens auf eine bestimmte Gesellschaftsschicht ab, zweitens auf die „Rassenzugehorigkeit“ und drittens auf bestimmte Orte. Sie hat deshalb nicht etwa zu einer Masseneinkerkerung, sondern vielmehr zu einer Hypereinkerkerung (sub-)proletarischer mannlicher Schwarzer aus dem implodierenden Ghetto gefuhrt. Diese dreifache Selektivitat zeigt, dass die Errichtung des gigantischen Bestrafungsstaates, der die USA an die Weltspitze der Inhaftierungsrate gebracht hat, zum einen eine verspatete Reaktion auf die Burgerrechtsbewegung und die Ghettoaufstande Mitte der 1960er Jahre ist, und zum anderen ein Instrument, das die neoliberale Revolution nutzte, um den gering qualifizierten Teilen der postindustriellen Arbeiterklasse unsichere Arbeit als normale Perspektive aufzuerlegen. Das doppelte Paar von Strafvollzug und marodem Hyperghetto auf der einen Seite und uberwachtem „workfare“ auf der anderen Seite ist kein moralisches Dilemma, sondern ein politisches Problem, das eine breite Untersuchung des Zusammenhangs zwischen ethnischem Stigma, gesellschaftlicher Ungleichheit und Bestrafung im Postfordismus erfordert. Schlusselworter: Hypereinkerkerung, soziale Klasse, „Rasse“, Ghetto, workfare, Stigma, Bestrafungsstaat, USA
Almost all work on texture in the computer vision and graphics communities has modeled the texture as tangential, i.e. lying in the tangent plane to the surface. This is equivalent to thinking of the texture as a pattern painted on the surface. Three-dimensional textures, where the elements may point out of the surface, have largely been ignored. We study a special class of 3D textures, perpendicular textures where we can model the elements as being normal to the surface. The perspective projection of perpendicularly textured surfaces results in several interesting phenomena, which do not occur in the much-studied tangential texture case. These include occlusion, foreshortening and illumination. In this paper, we study the geometry of the problem, modeling the locations of the elements of the texture as being a realization of a spatial point process. Relations between slant and tilt of the surface, density and height of elements and occlusions are derived. Occlusions can now be used as a cue to infer shape, instead of being treated as a source of error.
Reproducing bugs is hard. Deterministic replay systems address this problem by providing a high-fidelity replica of an original program run that can be repeatedly executed to zero-in on bugs. Unfortunately, existing replay systems for multiprocessor programs fall short. These systems either incur high overheads, rely on non-standard multiprocessor hardware, or fail to reliably reproduce executions. Their primary stumbling block is data races -- a source of nondeterminism that must be captured if executions are to be faithfully reproduced.
This paper provides scaling relationships between constituent properties and the uniaxial tensile response of synthetic “brick and mortar” composite materials inspired by nacre. The macroscopic strength and ductility (work of fracture) are predicted in terms of the brick properties (size, strength, and layout) and interface cohesive properties (e.g., maximum shear and normal stresses and separations). The results illustrate the trade-off between increasing strength and decreasing ductility with the increasing aspect ratio of the bricks. The models can be used to identify optimum mortar properties that maximize toughness for a given brick strength.
Background: Reviews have highlighted anxious youths’ affective disturbances, specifically, elevated negative emotions and reliance on ineffective emotion regulation strategies. However, no study has examined anxious youth’s emotional reactivity and regulation in real‐world contexts. Methods: This study utilized an ecological momentary assessment approach to compare real‐world emotional experiences of 65 youth with generalized anxiety disorder, social anxiety disorder, or social phobia (ANX) and 65 age‐matched healthy controls (CON), ages 9–13 years. Results: Hierarchical linear models revealed that ANX reported higher levels of average past‐hour peak intensity of nervous, sad and upset emotions than CON youth but similar levels during momentary reports of current emotion. As expected, ANX youth reported more frequent physiological reactions in response to a negative event; however, there were no group differences in how frequently they used cognitive–behavioral strategies. Avoidance, distraction and problem solving were associated with the down‐regulation of all negative emotions except nervousness for both ANX and CON youth; however, group differences emerged for acceptance, rumination and physiological responding. Conclusions: In real‐world contexts, ANX youth do not report higher levels of momentary negative emotions but do report heightened negative emotions in response to challenging events. Moreover, ANX youth report no differences in how frequently they use adaptive regulatory strategies but are more likely to have physiological responses to challenging events. They are also less effective at using some strategies to down‐regulate negative emotion than CON youth.
