Regiodivergent and Stereoselective Hydrosilylation of 1,3‐Disubstituted Allenes

Methods for the highly stereoselective and regiodivergent hydrosilylation of 1,3‐disubstituted allenes have been developed. The synthesis of E allylsilanes is accomplished with palladium NHC catalysts, and trisubstituted Z alkenylsilanes are accessed with nickel NHC catalysts. Unsymmetrically substituted allenes are well tolerated with nickel catalysis and afford Z alkenylsilanes. Evidence for a plausible mechanism was obtained through an isotopic double‐labeling crossover study.Silanes with a choice: The hydrosilylation of 1,3‐disubstituted allenes, which have presented a notorious challenge for regioselective additions, can now be accomplished with outstanding levels of regio‐ and stereocontrol. By altering the metal catalyst and ligand structure, access to trisubstituted Z alkenylsilanes or trans allylsilanes is provided in a simple catalytic operation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112189/1/anie_201503521_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112189/2/9088_ftp.pd

Regiodivergent and Stereoselective Hydrosilylation of 1,3‐Disubstituted Allenes

Methods for the highly stereoselective and regiodivergent hydrosilylation of 1,3‐disubstituted allenes have been developed. The synthesis of E allylsilanes is accomplished with palladium NHC catalysts, and trisubstituted Z alkenylsilanes are accessed with nickel NHC catalysts. Unsymmetrically substituted allenes are well tolerated with nickel catalysis and afford Z alkenylsilanes. Evidence for a plausible mechanism was obtained through an isotopic double‐labeling crossover study.Silane haben die Wahl: Die Hydrosilylierung von 1,3‐disubstituierten Allenen, die sonst äußerst schwierige Substrate für regioselektive Additionen sind, kann jetzt mit ausgezeichneter Regio‐ und Stereoselektivität durchgeführt werden. Durch den Wechsel von Metallkatalysator und Ligand werden entweder trisubstituierte Z‐Alkenylsilane oder trans‐Allylsilane erhalten.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112220/1/ange_201503521_sm_miscellaneous_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/112220/2/9216_ftp.pd

Damage by two Douglas-fir cone & seed insects: Correlation with cone crop size

Damage by the Douglas-fir cone moth, <i>Barbara colfaxiana</i> (Kearfott), in year N was significantly related to the size of the cone crop the preceding vear (N-1) in the interior of British Columbia but not at the coast. Damage by the Douglas-fir cone gall midge, <i>Contarinia oregonensis</i> Foote, at the coast was also significantly related to cone crop size the preceding year. Fluctuations in cone crop size appear to limit populations of these cone insects

Using GENI for experimental evaluation of Software Defined Networking in smart grids

The North American Electric Reliability Corporation (NERC) envisions a smart grid that aggressively explores advance communication network solutions to facilitate real-time monitoring and dynamic control of the bulk electric power system. At the distribution level, the smart grid integrates renewable generation and energy storage mechanisms to improve the reliability of the grid. Furthermore, dynamic pricing and demand management provide customers an avenue to interact with the power system to determine the electricity usage that best satisfies their lifestyle. At the transmission level, efficient communication and a highly automated architecture provide visibility in the power system and as a result, faults are mitigated faster than they can propagate. However, such higher levels of reliability and efficiency rest on the supporting communication infrastructure. To date, utility companies are moving towards Multiprotocol Label Switching (MPLS) because it supports traffic engineering and virtual private networks (VPNs). Furthermore, it provides Quality of Service (QoS) guarantees and fail-over mechanisms in addition to meeting the requirement of non-routability as stipulated by NERC. However, these benefits come at a cost for the infrastructure that supports the fullMPLS specification. With this realization and given a two week implementation and deployment window in GENI, we explore the modularity and flexibility provided by the low cost OpenFlow Software Defined Networking (SDN) solution. In particular, we use OpenFlow to provide 1.) automatic fail-over mechanisms, 2.) a load balancing, and 3.) Quality of Service guarantees: all essential mechanisms for smart grid networks

Assessing Medical Students’, Residents’, and the Public's Perceptions of the Uses of Personal Digital Assistants

Although medical schools are encouraging the use of personal digital assistants (PDAs), there have been few investigations of attitudes toward their use by students or residents and only one investigation of the public's attitude toward their use by physicians. In 2006, the University of Louisville School of Medicine surveyed 121 third- and fourth-year medical students, 53 residents, and 51 members of the non-medical public about their attitudes toward PDAs. Students were using either the Palm i705 or the Dell Axim X50v; residents were using devices they selected themselves (referred to in the study generically as PDAs). Three survey instruments were designed to investigate attitudes of (a) third- and fourth-year medical students on clinical rotations, (b) Internal Medicine and Pediatrics residents, and (c) volunteer members of the public found in the waiting rooms of three university practice clinics. Both residents and medical students found their devices useful, with more residents (46.8%) than students (16.2%) (p < 0.001) rating PDAs “very useful.” While students and residents generally agreed that PDAs improved the quality of their learning, residents’ responses were significantly higher (p < 0.05) than students’. Residents also responded more positively than students that PDAs made them more effective as clinicians. Although members of the public were generally supportive of PDA use, they appeared to have some misconceptions about how and why physicians were using them. The next phase of research will be to refine the research questions and survey instruments in collaboration with another medical school

Explicit Lie-Poisson integration and the Euler equations

We give a wide class of Lie-Poisson systems for which explicit, Lie-Poisson integrators, preserving all Casimirs, can be constructed. The integrators are extremely simple. Examples are the rigid body, a moment truncation, and a new, fast algorithm for the sine-bracket truncation of the 2D Euler equations.Comment: 7 pages, compile with AMSTEX; 2 figures available from autho

Signature of the Simplicial Supermetric

We investigate the signature of the Lund-Regge metric on spaces of simplicial three-geometries which are important in some formulations of quantum gravity. Tetrahedra can be joined together to make a three-dimensional piecewise linear manifold. A metric on this manifold is specified by assigning a flat metric to the interior of the tetrahedra and values to their squared edge-lengths. The subset of the space of squared edge-lengths obeying triangle and analogous inequalities is simplicial configuration space. We derive the Lund-Regge metric on simplicial configuration space and show how it provides the shortest distance between simplicial three-geometries among all choices of gauge inside the simplices for defining this metric (Regge gauge freedom). We show analytically that there is always at least one physical timelike direction in simplicial configuration space and provide a lower bound on the number of spacelike directions. We show that in the neighborhood of points in this space corresponding to flat metrics there are spacelike directions corresponding to gauge freedom in assigning the edge-lengths. We evaluate the signature numerically for the simplicial configuration spaces based on some simple triangulations of the three-sphere (S^3) and three-torus (T^3). For the surface of a four-simplex triangulation of S^3 we find one timelike direction and all the rest spacelike over all of the simplicial configuration space. For the triangulation of T^3 around flat space we find degeneracies in the simplicial supermetric as well as a few gauge modes corresponding to a positive eigenvalue. Moreover, we have determined that some of the negative eigenvalues are physical, i.e. the corresponding eigenvectors are not generators of diffeomorphisms. We compare our results with the known properties of continuum superspace.Comment: 24 pages, RevTeX, 4 eps Figures. Submitted to Classical Quantum Gravit