Analysis of serpentine folded-waveguide slow-wave structure using elliptical conformal transformation

Elliptical conformal transformation was used to derive closed form expressions for the equivalent circuit series inductance and shunt capacitance per period of a serpentine folded-waveguide slow-wave structure including the effects of the beam-hole. The lumped parameters were subsequently interpreted for the dispersion and interaction impedance characteristics of the structure. The analysis was benchmarked for two typical millimeter-wave structures operating in Ka- and W-bands, against measurement, 3D electromagnetic modeling using CST Microwave Studio, parametric analysis and equivalent circuit analysis. (C) 2010 Elsevier GmbH. All rights reserved.

Influence of glycosidic linkage on the nature of carbohydrate binding in beta-prism I fold lectins: An X-ray and molecular dynamics investigation on banana lectin-carbohydrate complexes

The three crystal structures reported here provide details of the interactions of mannose and the mannosyl-alpha-1,3-mannose component of a pentamannose with banana lectin and evidence for the binding of glucosyl-alpha-1,2-glucose to the lectin. The known structures involving the lectin include a complex with glucosyl-beta-1,3-glucose. Modeling studies on the three disaccharide complexes with the reducing end and the nonreducing end at the primary binding site are also provided here. The results of the Xray and modeling studies show that the disaccharides with an alpha-1,3 linkage prefer to have the nonreducing end at the primary binding site, whereas the reducing end is preferred at the site when the linkage is beta-1,3 in mannose/glucose-specific beta-prism I fold lectins. In the corresponding galactose-specific lectins, however, alpha-1,3-linked disaccharides cannot bind the lectin with the nonreducing end at the primary binding site on account of steric clashes with an aromatic residue that occurs only when the lectin is galactose-specific. Molecular dynamics simulations based on the known structures involving banana lectin enrich the information on lectin-carbohydrate interactions obtained from crystal structures. They demonstrate that conformational selection as well as induced fit operate when carbohydrates bind to banana lectin.

Method for measurement of the angles of an equilateral (60-deg) prism

A simple technique is devised io measure the angles of equilateral (60-deg) prisms, without using the expensive spectrometers, autocollimators, and angle gauges. The method can be extended to unpolished and opaque prisms made out of materials other than glass. (C) 1997 Society of Photo-Optical Instrumentation Engineers.

Non-resonant perturbation formula for interaction impedance measurement for a folded-waveguide SWS

The non-resonant perturbation formula for the measurement of interaction impedance of a folded-waveguide slow-wave structure was derived for the relevant electromagnetic field configuration at the axis of the beam-hole of the structure. Efficacy of the theory was benchmarked through virtual measurement using 3D electromagnetic modeling in CST-studio.

A waveguide problem involving a thick iris in the theory of electromagnetism

The problem of electromagnetic wave propagation in a rectangular waveguide containing a thick iris is considered for its complete solution by reducing it to two suitable integral equations, one of which is of the first kind and the other is of the second kind. These integral equations are solved approximately, by using truncated Fourier series for the unknown functions. The reflection coefficient is computed numerically from the two integral equation approaches, and almost the same numerical results are obtained. This is also depicted graphically against the wave number and compared with thin iris results, which are computed by using complementary formulations coupled with Galerkin approximations. While the reflection coefficient for a thin iris steadily increases with the wave number, for a thick iris it fluctuates and zero reflection occurs. The number of zeros of the reflection coefficient for a thick iris increases with the thickness. Thus a thick iris becomes completely transparent for some discrete wave numbers. This phenomenon may be significant in the modelling of rectangular waveguides.

Analysis of Serpentine folded-waveguide slow-wave structures by elliptical conformal transformation

Analysis of the serpentine folded-waveguide slow-wave structure was carried out using elliptical conformal transformation, for the dispersion and interaction impedance characteristics of the structure. The results obtained from the present analysis were compared with those from 3D electromagnetic simulation using MAFIA.

Measurement of Stress-Strain Response of A Rammed Earth Prism In Compression Using Fiber Bragg Grating Sensors

A comparative study of strain response and mechanical properties of rammed earth prisms, has been made using Fiber Bragg Grating (FBG) sensors (optical) and clip-on extensometer (electro-mechanical). The aim of this study is to address the merits and demerits of traditional extensometer vis-à-vis FBG sensor; a uni-axial compression test has been performed on a rammed earth prism to validate its structural properties from the stress - strain curves obtained by two different methods of measurement. An array of FBG sensors on a single fiber with varying Bragg wavelengths (..B), has been used to spatially resolve the strains along the height of the specimen. It is interesting to note from the obtained stress-strain curves that the initial tangent modulus obtained using the FBG sensor is lower compared to that obtained using clip-on extensometer. The results also indicate that the strains measured by both FBG and extensometer sensor follow the same trend and both the sensors register the maximum strain value at the same time.

Analysis of non-uniform waveguide in MZI and optimization of the power confinement in the waveguide

The technological world has attained a new dimension with the advent of miniaturization and a major breakthrough has evolved in the form of moems, technically more advanced than mems. This breakthrough has paved way for the scientists to research and conceive their innovation. This paper presents a mathematical analysis of the wave propagation along the non-uniform waveguide with refractive index varying along the z axis implemented on the cantilever beam of MZI based moem accelerometer. Secondly the studies on the wave bends with minimum power loss focusing on two main aspects of bend angle and curvature angle is also presented.

Crystal structure of a beta-prism II lectin from Remusatia vivipara

The crystal structure of a beta-prism II (BP2) fold lectin from Remusatia vivipara, a plant of traditional medicinal value, has been determined at a resolution of 2.4 A. This lectin (RVL, Remusatia vivipara lectin) is a dimer with each protomer having two distinct BP2 domains without a linker between them. It belongs to the ``monocot mannose-binding'' lectin family, which consists of proteins of high sequence and structural similarity. Though the overall tertiary structure is similar to that of lectins from snowdrop bulbs and garlic, crucial differences in the mannose-binding regions and oligomerization were observed. Unlike most of the other structurally known proteins in this family, only one of the three carbohydrate recognition sites (CRSs) per BP2 domain is found to be conserved. RVL does not recognize simple mannose moieties. RVL binds to only N-linked complex glycans like those present on the gp120 envelope glycoprotein of HIV and mannosylated blood proteins like fetuin, but not to simple mannose moieties. The molecular basis for these features and their possible functional implications to understand the different levels of carbohydrate affinities in this structural family have been investigated through structure analysis, modeling and binding studies. Apart from being the first structure of a lectin to be reported from the Araceae/Arum family, this protein also displays a novel mode of oligomerization among BP2 lectins.

Quaternary association in beta-prism I fold plant lectins: Insights from X-ray crystallography, modelling and molecular dynamics

Dimeric banana lectin and calsepa, tetrameric artocarpin and octameric heltuba are mannose-specific beta-prism I fold lectins of nearly the same tertiary structure. MD simulations on individual subunits and the oligomers provide insights into the changes in the structure brought about in the protomers on oligomerization, including swapping of the N-terminal stretch in one instance. The regions that undergo changes also tend to exhibit dynamic flexibility during MD simulations. The internal symmetries of individual oligomers are substantially retained during the calculations. Energy minimization and simulations were also carried out on models using all possible oligomers by employing the four different protomers. The unique dimerization pattern observed in calsepa could be traced to unique substitutions in a peptide stretch involved in dimerization. The impossibility of a specific mode of oligomerization involving a particular protomer is often expressed in terms of unacceptable steric contacts or dissociation of the oligomer during simulations. The calculations also led to a rationale for the observation of a heltuba tetramer in solution although the lectin exists as an octamer in the crystal, in addition to providing insights into relations among evolution, oligomerization and ligand binding.

Probabilistic Shared Cache Management (PriSM)

Effective sharing of the last level cache has a significant influence on the overall performance of a multicore system. We observe that existing solutions control cache occupancy at a coarser granularity, do not scale well to large core counts and in some cases lack the flexibility to support a variety of performance goals. In this paper, we propose Probabilistic Shared Cache Management (PriSM), a framework to manage the cache occupancy of different cores at cache block granularity by controlling their eviction probabilities. The proposed framework requires only simple hardware changes to implement, can scale to larger core count and is flexible enough to support a variety of performance goals. We demonstrate the flexibility of PriSM, by computing the eviction probabilities needed to achieve goals like hit-maximization, fairness and QOS. PriSM-HitMax improves performance by 18.7% over LRU and 11.8% over previously proposed schemes in a sixteen core machine. PriSM-Fairness improves fairness over existing solutions by 23.3% along with a performance improvement of 19.0%. PriSM-QOS successfully achieves the desired QOS targets.