Periodic orbit quantization of chaotic systems with strong pruning

The three-disk system, which for many years has served as a paradigm for the usefulness of cycle expansion methods, represents an extremely hard problem to semiclassical quantization when the disks are moved closer and closer together, since (1) pruning of orbits sets in, rendering the symbolic code incomplete, and (2) the number of orbits necessary to obtain accurate semiclassical eigenvalues proliferates exponentially. In this note we show that an alternative method, viz. harmonic inversion, which does not rely on the existence of complete symbolic dynamics or other specific properties of systems, provides a key to solving the problem of semiclassical quantization of systems with strong pruning. For the closed three-disk system we demonstrate how harmonic inversion, augmented by a signal cross-correlation technique, allows one to semiclassically calculate the energies up to the 28th excited state with high accuracy.Comment: 9 pages, 3 figures, submitted to Phys. Lett.

Comment on "Recurrences without closed orbits"

In a recent paper Robicheaux and Shaw [Phys. Rev. A 58, 1043 (1998)] calculate the recurrence spectra of atoms in electric fields with non-vanishing angular momentum not equal to 0. Features are observed at scaled actions ``an order of magnitude shorter than for any classical closed orbit of this system.'' We investigate the transition from zero to nonzero angular momentum and demonstrate the existence of short closed orbits with L_z not equal to 0. The real and complex ``ghost'' orbits are created in bifurcations of the ``uphill'' and ``downhill'' orbit along the electric field axis, and can serve to interpret the observed features in the quantum recurrence spectra.Comment: 2 pages, 1 figure, REVTE

Person to Person in Costa Rica

While still in the midst of their study abroad experiences, students at Linfield College write reflective essays. Their essays address issues of cultural similarity and difference, compare lifestyles, mores, norms, and habits between their host countries and home, and examine changes in perceptions about their host countries and the United States. In this essay, Katie Main describes her observations during her study abroad program at Centro Cultural e Historico Jose Figueres Ferrer, in San Ramón, Costa Rica

A Manufacturer Design Kit for Multi-Chip Power Module Layout Synthesis

The development of Multi-Chip Power Modules (MCPMs) has been a key factor in recent advancements in power electronics technologies. MCPMs achieve higher power density by combining multiple power semiconductor devices into one package. The work detailed in this thesis is part of an ongoing project to develop a computer-aided design software tool known as PowerSynth for MCPM layout synthesis and optimization. This thesis focuses on the definition and design of a Manufacturer Design Kit (MDK) for PowerSynth, which enables the designer to design an MCPM for a manufacturer’s fabrication process. The MDK is comprised of a layer stack and technology library, design rule checking (DRC), and layout versus schematic checking. File formats have been defined for layer stack and design rule input, and import functions have been written and integrated with the existing user interface and data structures to allow PowerSynth to accept these file formats as a form of input. Finally, an exhaustive DRC function has been implemented to allow the designer to verify that a synthesized layout meets all design rules before committing the design to manufacturing. This function was validated by running DRC on an example layout solution using two different sets of design rules

Periodic orbit quantization of chaotic maps by harmonic inversion

A method for the semiclassical quantization of chaotic maps is proposed, which is based on harmonic inversion. The power of the technique is demonstrated for the baker's map as a prototype example of a chaotic map.Comment: 7 pages, 1 figure, accepted for publication in Phys. Lett.

Corporate Governance and the Board's Locus of Control:the case of the ABI's treatment of footprints

This paper discusses the degree to which codes of corporate governance and the guidelines that develop around them tend to shift the locus of control away from the board of directors. It is argued that even in principles-based codes of governance such outcomes are an unavoidable consequence and that policy makers should weigh such consequences carefully before promulgating codes and guidelines. The case of the treatment of footprints (incentive plan performance averaging periods) by the UK’s Association of British Insurers (ABI) is analysed to illustrate the problem

PenDraw - A Language for Improving Take-Up of SVG

The case is presented for preferring a dedicated Computer Graphics (CG) language to the traditional conventional language plus add-on. PenDraw is presented as an existing language that overcomes many problems of CG add-ons, providing compile-time checking and reduced need for run-time debugging. PenDraw produces well-formed SVG. Evidence is given that PenDraw decreases development costs. Evidence is presented that PenDraw has brought CG programming to a wider ability range of potential users than professional programmers. It is argued that, given its qualities, PenDraw should be able to improve the take-up of CG programming. Such take-up is expected to be slow at first, given the market-place focus on interactivity and 3D. But it is believed that PenDraw's expressive power and cost benefits should lead to growth in its use, and in use of SVG