An evolutionary algorithm for global optimization based on self-organizing maps

In this article, a new population-based algorithm for real-parameter global optimization is presented, which is denoted as self-organizing centroids optimization (SOC-opt). The proposed method uses a stochastic approach which is based on the sequential learning paradigm for self-organizing maps (SOMs). A modified version of the SOM is proposed where each cell contains an individual, which performs a search for a locally optimal solution and it is affected by the search for a global optimum. The movement of the individuals in the search space is based on a discrete-time dynamic filter, and various choices of this filter are possible to obtain different dynamics of the centroids. In this way, a general framework is defined where well-known algorithms represent a particular case. The proposed algorithm is validated through a set of problems, which include non-separable problems, and compared with state-of-the-art algorithms for global optimization.     

Wireless video transmission using feedback-controlled adaptive h.264 source and channel coding

For wireless video, the present paper demonstrates that combining adaptive source and channel coding can provide a robust service over a wide range of transmission channel conditions. Various feedback-controlled adaptive coding solutions are considered for orthogonal frequency-division multiplexing-based systems. At the receiver, the reliabilities of subchannels (SCHs) are estimated and decisions are fed back to the transmitter to adapt modulation modes and channel code-rates to provide reliable transmission and yet avoid over-protection. The resulting available transmission capacity (which can vary widely with channel conditions) can inform an online collaborating source coder which itself exploits the available feedback to reduce error propagation. To ensure further improvement for fading channels, an efficient low-delay retransmission arrangement is also considered in which only the contents of unreliable SCHs within an erroneous packet are retransmitted. Simulation results demonstrate that such collaborative adaptive source and channel coding can provide efficient use of a continuously varying wireless channel.     

Wavelet-based time-domain solution of multiconductor transmission lines with skin and proximity effect

A time-domain wavelet-based method for the analysis of transmission lines (TLs) characterized by the presence of skin and proximity effects is presented. The method is based on the time domain TL equations, expressed in terms of transient resistance and convolution operator. A formulation of the convolution in the wavelet domain is presented here, and is used to expand the TL equations in the wavelet domain. In this way, the TL equations, properly discretized in the space variable, are reduced to an algebraic system characterized by a sparse block matrix whose blocks are easily calculated. The solution of the system is conveniently performed using standard techniques, avoiding step by step procedures. The method can be applied to linear and nonlinear problems, characterized by conductors of different shapes. The results obtained are compared with standard techniques, showing both accuracy and CPU time reduction.     

Comments on "Deficiencies in the way scattering parameters are Taught"

Equivalent representation of multiport circuits by the use of scattering parameters is of fundamental importance, especially in the microwave circuits area. However, in most cases, only a few pages of textbooks are devoted to this topic; based on the author's experience, the students find it somehow difficult to understand the physical meaning of scattering parameters (while they find other representations, like Z, Y, hybrid, or transmission parameters, easy to understand). For this reason, the contribution given by Sadiku (IEEE Trans. Educ., Vol. 46, no. 3, Aug. 2003, pp. 399-404) is very important. Furthermore, in Sadiku's paper, three nontrivial examples are reported, through which the students can gain understanding of this fundamental tool. In two of the three examples, some points are unclear; this correspondence analyzes this lack of clarity.     

Analysis of Integrated Circuit System s by An Innovative Wavelet-Based Scattering Matrix Approach

This paper proposes the use of scattering parameters (S-parameters) in the wavelet domain for the analysis of coupled multiconductor transmission lines, high-speed integrated circuits, and interconnects. S-parameters-based computing techniques are widely used in the analysis of networks characterized by a large number of integrated devices and interconnects. The theoretical and practical definition of the wavelet-based S matrix is shown, and then some numerical examples of its use and potential in the analysis of systems with linear and nonlinear terminations is shown and compared with other numerical techniques. The computational costs and the memory requirements of the wavelet representation of scattering matrix are also addressed     

Intracranial hemorrhage in achondroplasia

The neurological manifestations of achondroplasia include megalencephaly, hydrocephalus, and progressive myelopathy or radiculopathy secondary to spinal stenosis. Subarachnoid and intracerebral hemorrhage have not been previously reported in association with achondroplastic dwarfism. This report describes two patients with achondroplasia who have died secondary to intracranial hemorrhage. At autopsy, the source of hemorrhage was found to be an arteriovenous malformation of the choroid plexus in one case and a ruptured aneurysm of the left middle cerebral artery in the other.     

A general tool for circuit analysis based on wavelet transform

This paper deals with a generalized method for the time‐domain solution of electrical networks. The aim is to explore a new technique for the numerical simulation of circuits considering linear, time‐varying and non‐linear cases. By using the wavelet transform of the electrical quantities, differentiation and integration in the time domain are replaced by matrix multiplication. Then, the classical circuit differential equations obtained by mesh‐current, node‐voltage or state variables methods are transformed in algebraic equations. The numerical efficiency of wavelets makes the method effective for a fast and reliable numerical circuit simulation. Comparisons with analytical solutions and PSPICE simulations are presented in order to evaluate the numerical characteristics of the proposed method. Copyright © 2000 John Wiley & Sons, Ltd.     

A new locus for hemiplegic migraine maps to chromosome 1q31

A single familial hemiplegic migraine locus has been previously mapped to 19p13.1 and associated with mutations in a calcium channel gene (CACNL1A4). We describe a new 39-member four-generation family from Wyoming of German-Native American descent with autosomal dominant familial hemiplegic migraine that is not linked to the chromosome 19p locus. Affected individuals showed a stereotypic pattern of migrainous headache associated with hemisensory and hemiparetic attacks, without other headache types. Eighty-three percent reported minor head trauma as a trigger for individual attacks. Seventy-two percent reported other typical migraine triggers for the attacks. Attack frequency decreased with age and the overall course was benign. Genetic linkage studies of this family found strong evidence for the disease gene in this family being located at chromosome 1q31. Multipoint analysis showed lod scores > 3 in a 44-cm region flanked by D1S158 and D1S2781, using 80% penetrance and a phenocopy rate of 1/50. Haplotype and multipoint analysis, including flanking markers, suggested incomplete penetrance and variable expressivity of the disease. A single affected patient who reports atypical symptoms including daily headaches likely represents a phenocopy. This new locus for hemiplegic migraine suggests that mutations of additional calcium channels in the region may cause the disease.     

Analysis of Power Lines Uncertain Parameter Influence on Power Line Communications

In this paper, we analyze the effects of power lines parameters' uncertainties on the efficiency of a powerline communication (PLC) system. An estimate of the upper and lower bounds' system response due to the uncertainties is given. The analyzed system is schematized as a connection of multiport devices described by their scattering parameter matrices and an adjoint method for sensitivity calculations, based on the use of a wavelet expansion, is used to determine the bounds. The wavelet based sensitivity analysis allows a direct determination of the time domain sensitivity avoiding computationally expensive convolution integral calculations; in addition a fast and accurate bounds calculation is obtained avoiding statistical Monte Carlo simulations. The bounds determination allows the estimate of noteworthy quantities for the tuning of currently used modulation schemes for PLC such as orthogonal frequency-division modulation.     

Hereditary lymphedema: evidence for linkage and genetic heterogeneity

Hereditary or primary lymphedema is a developmental disorder of the lymphatic system which leads to a disabling and disfiguring swelling of the extremities. Hereditary lymphedema generally shows an autosomal dominant pattern of inheritance with reduced penetrance, variable expression and variable age at onset. Three multigeneration families demonstrating the phenotype of hereditary lymphedema segregating as an autosomal dominant trait with incomplete penetrance were genotyped for 366 autosomal markers. Linkage analysis yielded a two-point LOD score of 6.1 at straight theta = 0. 0 for marker D5S1354 and a maximum multipoint LOD score of 8.8 at marker D5S1354 located at chromosome 5q34-q35. Linkage analysis in two additional families using markers from the linked region showed one family consistent for linkage to distal chromosome 5. In the second family, linkage to 5q was excluded for all markers in the region with LOD scores Z < -2.0. The vascular endothelial growth factor C receptor ( FLT4 ) was mapped to the linked region, and partial sequence analysis identified a G-->A transition at nucleotide position 3360 of the FLT4 cDNA, predicting a leucine for proline substitution at residue 1126 of the mature receptor in one nuclear family. This study localizes a gene for primary lymphedema to distal chromosome 5q, identifies a plausible candidate gene in the linked region, and provides evidence for a second, unlinked locus for primary lymphedema.