Combinatorial Group Theory: COMBINATORIAL GROUP THEORY

Every organisation from the scale of whole countries down to small companies has a list of system developments which have ended in various forms of disaster. The nature of the failures varies but typical examples are: cost overruns; timescale overruns and sometimes, loss of life. The post-mortems to these systems reveal a wide range of reasons all the way from hardware failures, through software errors right to major system level mistakes. More importantly a large number of these systems share one attribute: complexity. This paper presents a fresh look at the nature of complexity in the building of computer based systems.

http://ieeexplore.ieee.org/iel3/4458/12639/00581896.pdf

Complex systems

Self-Organized Criticality

Expression.- Spectral Clustering Gene Ontology Terms to Group Genes by Function.- Dynamic De-Novo Prediction of microRNAs Associated with Cell Conditions: A Search Pruned by Expression.- Clustering Gene Expression Series with Prior Knowledge.- A Linear Time Biclustering Algorithm for Time Series Gene Expression Data.- Time-Window Analysis of Developmental Gene Expression Data with Multiple Genetic Backgrounds.- Phylogeny.- A Lookahead Branch-and-Bound Algorithm for the Maximum Quartet Consistency Problem.- Computing the Quartet Distance Between Trees of Arbitrary Degree.- Using Semi-definite Programming to Enhance Supertree Resolvability.- An Efficient Reduction from Constrained to Unconstrained Maximum Agreement Subtree.- Pattern Identification in Biogeography.- On the Complexity of Several Haplotyping Problems.- A Hidden Markov Technique for Haplotype Reconstruction.- Algorithms for Imperfect Phylogeny Haplotyping (IPPH) with a Single Homoplasy or Recombination Event.- Networks.- A Faster Algorithm for Detecting Network Motifs.- Reaction Motifs in Metabolic Networks.- Reconstructing Metabolic Networks Using Interval Analysis.- Genome Rearrangements.- A 1.375-Approximation Algorithm for Sorting by Transpositions.- A New Tight Upper Bound on the Transposition Distance.- Perfect Sorting by Reversals Is Not Always Difficult.- Minimum Recombination Histories by Branch and Bound.- Sequences.- A Unifying Framework for Seed Sensitivity and Its Application to Subset Seeds.- Generalized Planted (l,d)-Motif Problem with Negative Set.- Alignment of Tandem Repeats with Excision, Duplication, Substitution and Indels (EDSI).- The Peres-Shields Order Estimator for Fixed and Variable Length Markov Models with Applications to DNA Sequence Similarity.- Multiple Structural RNA Alignment with Lagrangian Relaxation.- Faster Algorithms for Optimal Multiple Sequence Alignment Based on Pairwise Comparisons.- Ortholog Clustering on a Multipartite Graph.- Linear Time Algorithm for Parsing RNA Secondary Structure.- A Compressed Format for Collections of Phylogenetic Trees and Improved Consensus Performance.- Structure.- Optimal Protein Threading by Cost-Splitting.- Efficient Parameterized Algorithm for Biopolymer Structure-Sequence Alignment.- Rotamer-Pair Energy Calculations Using a Trie Data Structure.- Improved Maintenance of Molecular Surfaces Using Dynamic Graph Connectivity.- The Main Structural Regularities of the Sandwich Proteins.- Discovery of Protein Substructures in EM Maps.

Algorithms in Bioinformatics: 5th International Workshop, WABI 2005, Mallorca, Spain, October 3-6, 2005, Proceedings (Lecture Notes in Computer Science / Lecture Notes in Bioinformatics)

Microwave passive and active devices containing dielectric resonators and the design procedures used to characterize these components are reviewed. The emphasis has been on low noise, small size, low cost and high temperature stability. Both filter and oscillator applications are described. The applications of dielectric resonators in the millimeter-wave frequency band are also discussed. >

http://ieeexplore.ieee.org/iel2/741/1062/00027611.pdf

Dielectric resonators

This article explores an optimization procedure for microwave filters and multiplexers. The procedure is initialized by a classical filter synthesis based on a segmented electromagnetic synthesis that provides the basic dimensions of the structure. The optimization loop, which combines a global electromagnetic analysis and a coupling identification, improves the structure response compared to an empirical optimization.

Direct electromagnetic optimization of microwave filters

Sand automata as cellular automata

A one-dimensional cellular automaton is a dynamical system which consisting in a juxtaposition of cells whose state changes over discrete time according to that of their neighbors. One of its simplest behaviors is nilpotency: all configurations of cells are mapped after a finite time into a given "null" configuration. Our main result is that nilpotency is equivalent to the condition that all configurations converge towards the null configuration for the Cantor topology, or, equivalently, that all cells of all configurations asymptotically reach a given state.

/pdf/nilpotency-and-limit-sets-of-cellular-automata-4dlxtkbphe.pdf

Nilpotency and Limit Sets of Cellular Automata

The highest short-term frequency-stable microwave resonator oscillators utilize liquid-helium-cooled sapphire dielectric resonators. The temperature coefficient of frequency of such resonators is very small due to residual paramagnetic impurities canceling the temperature coefficient of permittivity (TCP). At high temperatures, which are accessible in space or with liquid nitrogen, the effect is too weak, and if extra impurities are added, the loss introduced is too great. An alternative technique involves using two low-toss dielectric materials with TCP of opposite sign. Following this approach, a sapphire-rutile resonator was designed with mode frequency-temperature turning points between 50-80 K, with Q-factors of order 10/sup 7/. Previous designs used thin disks of rutile fixed to the ends of the sapphire cylinder. Due to the high permittivity of rutile, such resonators have a high density of spurious modes. By placing rings at the end faces instead of disks, the majority of the spurious modes are raised above the operation frequency and the requirement for thin disks is removed. Finite-element analysis has been applied and compares well with experiment. The application to the design of high stability "fly-wheel"oscillators for atomic frequency standards is discussed.

Cryogenically cooled sapphire-rutile dielectric resonators for ultrahigh-frequency stable oscillators for terrestrial and space applications [atomic frequency standards]

Pierre Guillon

Papers

Direct electromagnetic optimization of microwave filters

Sand automata as cellular automata

Nilpotency and Limit Sets of Cellular Automata

Cryogenically cooled sapphire-rutile dielectric resonators for ultrahigh-frequency stable oscillators for terrestrial and space applications [atomic frequency standards]

An accurate wavelet neural-network-based model for electromagnetic optimization of microwave circuits