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Matrix Used (matrix + used)
Selected AbstractsApproximation method for high-degree harmonics in normal mode modellingGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2002R. E. M. Riva Summary For some loading applications, the normal modes approach to the viscoelastic relaxation of a spherical earth requires the use of spherical harmonics up to a high degree. Examples include postseismic deformation (internal loading) and sea level variations due to glacial isostatic adjustment (external loading). In the case of postseismic modelling, the convergence of the solution, given as a spherical harmonic expansion series, is directly dependent on loading depth and requires several thousands of terms for shallow earthquake sources. The particular structure of the analytical fundamental solutions used in normal mode techniques usually does not allow a straightforward calculation, since numerical problems can readily occur due to the stiffness of the matrices used in the propagation routines. Here we show a way of removing this stiffness problem by approximating the fundamental matrix solutions, followed by a rescaling procedure, in this way we can virtually go up to whatever harmonic degree is required. [source] Optimization of structural dynamic behaviour based on effective modal parametersINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 5 2007S. Besset Abstract Optimization of complex structures often leads to high calculation costs. Indeed, the structure has to be frequently reanalysed in order to update the optimization criteria. We propose an optimization method based on effective modal parameters. These parameters are close to the modal matrices used for the modal analysis of a structure. Thus, once the structure has been analysed, it becomes very easy to calculate optimization criteria. First, we will explain the modal analysis that we will use in this paper. A modal model will be used to analyse the hollow parts of the structure. The modal analysis of the whole structure will be performed using substructuring and ,double modal synthesis' proposed by Jezequel. Secondly, we will explain how to obtain effective modal parameters and their use for optimization. Finally, we will show the efficiency of these parameters through the optimization of a complex structure, using two types of optimization methods. Copyright © 2006 John Wiley & Sons, Ltd. [source] Evaluation and standardisation of different matrices used for double-blind placebo-controlled food challenges to fishJOURNAL OF HUMAN NUTRITION & DIETETICS, Issue 5 2010E. Vassilopoulou Abstract Background:, Fish allergens represent one of the most common causes of adverse reactions to food worldwide. Double-blind placebo-controlled food challenges (DBPCFC) are the gold standard for food allergy diagnosis. However, no standardised recipes are available for common food allergens such as fish, and a well trained dietitian is essential for creating and standardising them. The present study aimed to create and standardise recipes for use in DBPCFCs to fish. Methods:, Three recipes were prepared. Employing a standardised procedure, a total of 35 panelists evaluated the different matrices using an evaluation form. A paired comparison test was used to estimate total evaluation's outcome. Fish allergic patients were challenged with different fish species blinded with the selected matrix and evaluated the recipe using the same form. Results:, From a base recipe and step-by-step modifications, a low fat recipe was selected among other recipes tested, which proved to be appropriate for fish blinding, in terms of taste, odour, appearance and blinding. Patients challenged with the final matrix found it acceptable, no matter which fish type was used. Conclusions:, In this pilot study, a recipe with satisfactory organoleptic characteristics was developed and validated for DBPCFC to fish. [source] Differential interactions of plasmid DNA, RNA and genomic DNA with amino acid-based affinity matricesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17-18 2010Angela Sousa Abstract The development of a strategy to plasmid DNA (pDNA) purification has become necessary for the development of gene therapy and DNA vaccine production processes in recent years, since this nucleic acid and most of contaminants, such as RNA, genomic DNA and endotoxins, are negatively charged. An ideal separation methodology may be achieved with the use of affinity interactions between immobilized amino acids and nucleic acids. In this study, the binding behaviour of nucleic acids under the influence of different environmental conditions, such as the composition and ionic strength of elution buffer, and the temperature, is compared with various amino acids immobilized on chromatography resins. Supercoiled (sc) plasmid isoform was isolated with all matrices used, but in some cases preferential interactions with other nucleic acids were found. Particularly, lysine chromatography showed to be an ideal technology mainly on RNA purification using low salt concentration. On the other hand, arginine ligands have shown a greater ability to retain the sc isoform comparatively to the other nucleic acids retention, becoming this support more adequate to sc pDNA purification. The temperature variation, competitive elution and oligonucleotides affinity studies also allowed to recognize the dominant interactions inherent to biorecognition of pDNA molecule and the affinity matrices. [source] Processing and mechanical behavior of carbon black graded rubber compoundsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Sandeep S. Ahankari Abstract Functionally graded rubber compounds (FGRCs) were prepared by construction based method. The matrix used was natural rubber (NR). Amorphous carbon black (N-330) was used as grading material. The gradation of nanoparticles in a rectangular geometry comprised the variation of particle volume fraction along thickness direction. Its performance was evaluated for structural application through various mechanical and surface properties like tensile strength, modulus, tear strength, elongation at break, hardness, fracture surface by scanning electron microscopy, etc. At the same percentage of nanofiller loading, FGRCs show enhanced properties, i.e., modulus and tear strength (in some grades) compared to uniformly dispersed rubber compounds (UDRCs). Modulus of FGRCs, for a given particular stacking sequence of the layers, increases as much as by 275% compared to UDRCs. The ultimate properties like tensile strength and elongation at break made up for the modulus enhancement that decreases to as minimum as 50 and 80%, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] An Empirically Based Method of Q-Matrix Validation for the DINA Model: Development and ApplicationsJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 4 2008Jimmy De La Torre Most model fit analyses in cognitive diagnosis assume that a Q matrix is correct after it has been constructed, without verifying its appropriateness. Consequently, any model misfit attributable to the Q matrix cannot be addressed and remedied. To address this concern, this paper proposes an empirically based method of validating a Q matrix used in conjunction with the DINA model. The proposed method can be implemented with other considerations such as substantive information about the items, or expert knowledge about the domain, to produce a more integrative framework of Q-matrix validation. The paper presents the theoretical foundation for the proposed method, develops an algorithm for its practical implementation, and provides real and simulated data applications to examine its viability. Relevant issues regarding the implementation of the method are discussed. [source] Dissociation mechanisms and implication for the presence of multiple conformations for peptide ions with arginine at the C-terminus: time-resolved photodissociation studyJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 7 2010So Hee Yoon Abstract Time-resolved photodissociation (PD) patterns of singly protonated peptides with arginine at the C-terminus (C-arg peptide ions) have been used to classify the dissociation channels into two categories, i.e. high-energy channels generating v, w and x and low-energy ones generating b, y and z. x + 1 formed by C,CO cleavage seems to be the intermediate ion in high-energy channels just as a + 1 is for N-arg peptide ions. Difference in time-resolved pattern indicates that the two sets of channels, high- and low-energy ones, are not in direct competition. Noncompetitive dissociation is also indicated by the observation of anomalous effect of matrix used in matrix-assisted laser desorption ionization, a cooler matrix generating more high-energy product ions both in spontaneous dissociation and in PD. Results from detailed investigation suggest that the two sets of channels start from two (or more) different conformations. Copyright © 2010 John Wiley & Sons, Ltd. [source] Compaction of pharmaceutical tablets with different polymer matrices studied by FTIR imaging and X-ray microtomographyJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2008Patrick Wray Abstract Water soluble polymers are often used in tablet compaction for their desirable compaction and dissolution properties. ATR-FTIR spectroscopic imaging has been used to analyze in situ the spatial distribution of different components in tablets with different compositions. Caffeine tablets made of three different polymer matrices, microcrystalline cellulose, hydroxypropyl methylcellulose (HPMC) and lactose, were investigated. It was found that the distribution of caffeine is strongly affected by the composition of polymer matrix used in the tablet. X-ray tomography was used to analyze the caffeine distribution as a complementary technique. The results obtained were compared to the ATR-FTIR spectroscopic images. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:4269,4277, 2008 [source] Influence of Matrix Type on Surface Roughness of Three Resins for Provisional Crowns and Fixed Partial DenturesJOURNAL OF PROSTHODONTICS, Issue 2 2009Raul Ayuso-Montero DDS Abstract Purpose: This study evaluated the effect of matrix type on the surface roughness of resins for provisional crowns and fixed partial dentures. Materials and Methods: Ninety specimens of two acrylic resins (Trim II, Tab2000) and one bis-acryl composite (Protemp II Garant) were fabricated using one of three matrices: irreversible hydrocolloid (Cavex CA37), poly(vinyl siloxane) (Aquasil) or vacuum-formed matrix (Bio-flow Hard). The sample size for each resin-matrix combination was 10. The vestibular face of one natural maxillary central incisor was used as a model to fabricate all the specimens, following the custom fabrication technique. The average roughness measurements, Ra (,m), were obtained using a profilometer, and the data were analyzed using Kruskal-Wallis and Mann-Whitney U- tests. The results were contrasted against the surface roughness of the tooth using a one-sample t- test. Results: Aquasil and vacuum-formed matrix had a smoother surface than Cavex CA37 regardless of the resin tested (p < 0.05). Protemp II Garant had the smoothest surface regardless of the matrix used, with no significant differences when polymerized against the three different matrices. Trim II polymerized against Cavex CA37 had a rougher (p < 0.05) surface than Aquasil or vacuum-formed matrix. Tab2000 had the smoothest surface (p < 0.05) when polymerized against a vacuum-formed matrix. Conclusions: There is no universal matrix that produces the smoothest surface: this depends on the compatibility between the resin and the matrix. Protemp II Garant polymerized against Cavex CA37 matrix yields a surface that is smooth enough not to require polishing unless this surface is adjusted. [source] | |||||||||||||