Free actions on handlebodies

The equivalence (or weak equivalence) classes of orientation-preserving free actions of a finite group G on an orientable three-dimensional handlebody of genus g?1 can be enumerated in terms of sets of generators of G. They correspond to the equivalence classes of generating n-vectors of elements of G, where n=1+(g−1)/|G|, under Nielsen equivalence (or weak Nielsen equivalence). For Abelian and dihedral G, this allows a complete determination of the equivalence and weak equivalence classes of actions for all genera. Additional information is obtained for other classes of groups. For all G, there is only one equivalence class of actions on the genus g handlebody if g is at least 1+?(G)|G|, where ?(G) is the maximal length of a chain of subgroups of G. There is a stabilization process that sends an equivalence class of actions to an equivalence class of actions on a higher genus, and some results about its effects are obtained.     

Gauge-invariant poisson brackets for chromohydrodynamics

Noncanonical hamiltonian structures are presented both for Yang-Mills Vlasov plasmas, and for ideal fluids interacting with Yang-Mills fields. These hamiltonian structures are given Lie-algebraic interpretations.     

Accurate background monitoring circuit for BC6-equipped varian-techtron AA5 and AA6 atomic absorption spectrometers

A low-cost circuit permits the accurate simultaneous measurement of both background-corrected atomic absorption spectrometric signals and background-only signals.     

Using an Iterated Prisoner's Dilemma with Exit Option to Study Alliance Behavior: Results of a Tournament and Simulation

Nearly half of all strategic alliances fail (Park and Russo, 1996; Dyer et al., 2001), often because of opportunistic behavior by one party or the other. We use a tournament and simulation to study strategies in an iterated prisoner's dilemma game with exit option to shed light on how a firm should react to an opportunistic partner. Our results indicate that a firm should give an alliance partner a second chance following an opportunistic act but that subsequent behavior should be contingent on the value of the next best opportunity outside the alliance. Firms should be more forgiving if the potential benefits from the alliance exceed other opportunities. The strategies were also found to be robust across a wide range of game lengths. The implications of these results for alliance strategies are discussed. Steven E. Phelan received his PhD in economics from La Trobe University (Australia) in 1998. Following five years at the University of Texas at Dallas, he joined the faculty of the University of Nevada Las Vegas in 2003. Dr. Phelan's research interests include competitive dynamics, organizational efficiency, acquisition and alliance performance, and entrepreneurial competence. His methods of choice to study these phenomena include agent-based modelling, experimental game theory, and event studies. Prior to joining academia, Dr. Phelan held executive positions in the telecommunications and airline industries and was a principal partner in Bridges Management Group, a consultancy specializing in strategic investment decisions. Richard J. Arend is a graduate of the University of British Columbia's doctoral program in Policy Analysis and Strategy. He is on the Management faculty of the University of Nevada, Las Vegas, arriving most recently from the Management faculty of New York University's Stern School of Business. Dr. Arend's interests lie in the analysis of unusual modes of firm value creation and destruction, where he has published in several top journals. He is a professional engineer with work and consulting experience in aerospace and computing. Darryl A. Seale joined the faculty of UNLV in 1999, following three years at Kent State University and the University of Alabama in Huntsville. Prior to Alabama, he completed his Ph.D. and M.S. degrees in Business Administration at the University of Arizona, his M.B.A. from Penn State University, and spent over ten years in management and market planning positions in the health care industry. Professor Seale's research interests include strategic decision making, bargaining and negotiation, and behavioral game theory. His research has been funded by the National Science Foundation and has been published in top-tier journals including Management Science, OBHDP, Games and Economic Behavior, and Strategic Management Journal. His teaching interests include business policy/strategy, managerial decision making, and bargaining and negotiation.     

Geometric gradient-flow dynamics with singular solutions

The gradient-flow dynamics of an arbitrary geometric quantity is derived using a generalization of Darcy’s Law. We consider flows in both Lagrangian and Eulerian formulations. The Lagrangian formulation includes a dissipative modification of fluid mechanics. Eulerian equations for self-organization of scalars, 1-forms and 2-forms are shown to reduce to nonlocal characteristic equations. We identify singular solutions of these equations corresponding to collapsed (clumped) states and discuss their evolution.     

Microwave-assisted parallel synthesis of fused heterocycles in a novel parallel multimode reactor

New rotor types using disposable glass vials for small-scale parallel synthesis in multimode microwave reactors are introduced. One rotor comprises 16 groups of four vials, whereas the second uses four silicon carbide plates with a 6 x 4 matrix to process the vials. Both rotors achieve utmost temperature homogeneity upon microwave irradiation and can be used for microwave-mediated reactions at temperatures of up to 200 degrees C and pressures of 20 bar. The generation of three different heterocycle libraries furnishing thiophenes, oxindoles, and benzimidazoles using the new rotor types is described.     

Directing the polar organization of microtubules

Microtubules (MTs) are polar protein filaments that participate in critical biological functions ranging from motor protein direction to coordination of chromosome separation during cell division. The effective facilitation of these processes, however, requires careful regulation of the polar orientation and spatial organization of the assembled MTs. We describe here an artificial approach to polar MT assembly that enables us to create three-dimensional polar-oriented synthetic microtubule organizing centers (POSMOCs). Utilizing engineered MT polymerization in concert with functionalized micro- and nanoscale particles, we demonstrate the controllable polar assembly of MTs into asters and the variations in aster structure determined by the interactions between the MTs and the functionalized organizing particles. Inspired by the aster-like form of biological structures such as centrosomes, these POSMOCs represent a key step toward replicating biology's complex materials assembly machinery.