An efficient method for electromagnetic characterization of 2-D geometries in stratified media

Cataloged from PDF version of article.A numerically efficient technique, based on the spectral-domain method of moments (MoM) in conjunction with the generalized pencil-of-functions (GPOF) method, is developed for the characterization of two-dimensional geometries in multilayer planar media. This approach provides an analytic expression for all the entries of the MoM matrix, explicitly including the indexes of the basis and testing functions provided that the Galerkin’s MoM is employed. This feature facilitates an efficient modification of the geometry without the necessity of recalculating the additional elements in the MoM matrix. To assess the efficiency of the approach, the results and the matrix fill times are compared to those obtained with two other efficient methods, namely, the spatial-domain MoM in conjunction with the closed-form Green’s functions, and a fast Fourier transform algorithm to evaluate the MoM matrix entries. Among these, the spectral-domain MoM using the GPOF algorithm is the most efficient approach for printed multilayer geometries

On Integrability of Semi-invariant Submanifolds of Trans-Sasakian Finsler Manifolds

We introduce the notion of trans-Sasakian Finsler manifold, then study semi-invariant submanifold F^m = (Y, Y\u27, F) of a trans-Sasakian Finsler manifold F^{2n+1} + (bar-Y, bar-Y\u27, bar-F) and we discuss the integrability conditions of the distrubitions of the semi-invariant submanifolds of the trans-Sasakian Finsler manifold

Programmed –1 frameshifting by kinetic partitioning during impeded translocation.

Programmed –1 ribosomal frameshifting (−1PRF) is an mRNA recoding event utilized by cells to enhance the information content of the genome and to regulate gene expression. The mechanism of –1PRF and its timing during translation elongation are unclear. Here, we identified the steps that govern –1PRF by following the stepwise movement of the ribosome through the frameshifting site of a model mRNA derived from the IBV 1a/1b gene in a reconstituted in vitro translation system from Escherichia coli. Frameshifting occurs at a late stage of translocation when the two tRNAs are bound to adjacent slippery sequence codons of the mRNA. The downstream pseudoknot in the mRNA impairs the closing movement of the 30S subunit head, the dissociation of EF-G, and the release of tRNA from the ribosome. The slippage of the ribosome into the –1 frame accelerates the completion of translocation, thereby further favoring translation in the new reading frame

Coeliac trunk and common hepatic artery variations in children: an analysis with computed tomography angiography

Background: Understanding the coeliac trunk (CeT) and hepatic artery anatomy is important not only in preventing iatrogenic injuries but also in planning surgical procedures in children. Therefore, the aim of this study is to analyse the prevalence of CeT and common hepatic artery (CHA) variations in the paediatric population.   Materials and methods: One hundred and seventy-four children who underwent abdominal multidetector computed tomography (MDCT) angiography, either because of trauma or liver transplantation, were analysed retrospectively. The patterns of CeT, CHA and their variant branches were revealed and compared with previous studies involving adults.   Results: A total of 157 (90.2%) of the 174 patients had normal CeT anatomy, whereas 17 (9.8%) had variations. Five types of CeT variations were identified according to Song’s classification in which ‘hepatosplenic trunk + left gastric artery + superior mesenteric artery’ was the most prevalent. One hundred-twelve (64.4%) of the 174 patients had normal CHA anatomy; however, 62 (35.6%) had variations. Six types of CHA variations were identified according to Michel’s and Hiatt’s classification. The most common was ‘replaced left hepatic artery originating from left gastric artery’.   Conclusions: The prevalences of CeT and hepatic artery variations are high in children, as they are in older patients. Awareness of these variations is important in terms of avoiding iatrogenic injury and in promoting surgical procedure planning for liver transplantation or abdominal tumour surgery