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Extracting information from the rapidly growing sequence data in DNA databases poses formidable computational problems. Over the last few years a number of approaches have been formulated to mathematically characterize the base distribution and composition characteristics of DNA sequences with a view to aiding biologists in their quest for rapidly identifying sequence segments of interest and make comparative studies of genes and genomes. Methods based on graphical representations have been found to be intuitively appealing and potentially highly informative and have led to several interesting applications. In this paper we briefly review the motivations and major methods of graphical representation and mathematical characterization of DNA sequences, analyze the strengths and weaknesses of current techniques and consider some of the important applications that have been made using these techniques. We finally discuss some of the new developments and applications areas that are likely to be of much importance in bringing the usefulness of this approach to the notice of the wider scientific community. [ABSTRACT FROM AUTHOR]

GUTTA is a small spherical tokamak (R = 16cm, a = 8cm, Ip = 150kA) operating at the St. Petersburg State University since 2004 in the scope of the IAEA CRP “Joint Research using Small Tokamaks”. Main scientific activities on GUTTA include development of new and improvement of existing mathematical models of plasma control, relevant for application on large tokamaks and ITER and verification of them on GUTTA; studies on the ECRH/EBW assisted breakdown and non-solenoid plasma formation in low aspect ratio tokamak; development of diagnostics; training and education of students. In this paper design properties of Gutta will be presented. Regimes of operation of the tokamak and plasma shape parameters are described and first results of the plasma formation and start-up studied will be discussed. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The a⁁ versus a method, which is based on simple linear regression analysis, is commonly used to quantify inspection probability of detection (POD). Bias in flaw sizing will, however, cause bias in POD estimates. This paper describes a statistical model for adjusting for bias in POD estimates that is caused by flaw sizing errors. The model is fit by using the method of maximum likelihood. Our simulation studies that show how the use of our model will adjust for flaw-sizing bias. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The determination of the number (n) of unobserved sources is an important issue in Blind Source Separation (BSS) of linear and instantaneous mixtures. However BSS is already a difficult task, so we generally assume that this number (n) is known and a priori fixed. In this paper, we address this issue as a Bayesian model selection problem and view the determination of this number (n) as a hypothesis testing problem via comparison of Bayes factors and study the computation of these factors by two numerical approximations: importance sampling from the posterior and simulated annealing sampling. Seeking for a general solution may be tricky to this problem, so we will be interested in blind separation of sparse sources modeled by a double exponential prior “π(.) ∝ exp(-λ|.|)”. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Take-off is an essential stage of all flight. In the present paper, the aerodynamic performance and force generation mechanism in drosophila voluntary take-off have been studied numerically. The approach involves the simulation of the flow by solving the two-dimensional unsteady incompressible N-S equations. The wing motion model is established based on the results of experiment. Insights into the unsteady aerodynamic force generation process are gained from the force and flow structure information. The results show that the second flap is the main propulsive phase. Both added inertial forces and vorticity induced forces are important to the force generation. [ABSTRACT FROM AUTHOR]