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Kinds of Matrix Terms modified by Matrix Selected Abstracts4156: Inflammatory mediators in the aqueous humor from patients with uveitis associated with Behçet's disease and Vogt-Koyanagi-Harada diseaseACTA OPHTHALMOLOGICA, Issue 2010A ABU EL ASRAR Purpose We studied interphotoreceptor retinoid-binding protein (IRBP), a dominant autoimmune antigen in the eye. Methods Aqueous humour samples from 28 patients with active uveitis were analysed for immunoglobulin G (IgG) content as a marker for blood-ocular barrier breakdown and by gelatinase B zymography for the detection of inflammation. The data were correlated with the presence of intact IRBP (approximately 140 kD) as determined by Western blot analysis and with the clinical disease activity. Results Aqueous humour samples from control eyes and eyes with low disease activity showed positive immunoreactivity for intact IRBP. The IRBP signal weakened or disappeared with higher disease activity. Significant positive correlations were observed between disease activity and levels of gelatinase B/matrix metalloproteinase-9 (MMP-9) (rs=0.713; P<0.001) and IgG (rs=0.580; P=0.001). Significant negative correlations were found between levels of IRBP and disease activity (rs=-0.520; P=0.005) and levels of MMP-9 (rs=-0.727; P<0.001) and of IgG (rs=-0.834; P<0.001). Whereas neutrophil elastase converted intact IRBP into an immunoreactive 55 kD peptide in vitro, the conversion by neutrophil degranulates resembled more the in vivo context with a complete degradation of IRBP. Reversal of inflammation with immunosuppressive therapy was accompanied with reappearance of intact IRBP and disappearance of IgG and MMP-9. Conclusion The analysis of IRBP proteolysis is useful as a biomarker for uveitis and suggests that inhibition of proteinases might become a therapeutic strategy in an inflammatory context of a damaged blood-ocular barrier. [source] EFFECTS OF MIGRATION ON THE GENETIC COVARIANCE MATRIXEVOLUTION, Issue 10 2007Frédéric Guillaume In 1996, Schluter showed that the direction of morphological divergence of closely related species is biased toward the line of least genetic resistance, represented by gmax, the leading eigenvector of the matrix of genetic variance,covariance (the G -matrix). G is used to predict the direction of evolutionary change in natural populations. However, this usage requires that G is sufficiently constant over time to have enough predictive significance. Here, we explore the alternative explanation that G can evolve due to gene flow to conform to the direction of divergence between incipient species. We use computer simulations in a mainland,island migration model with stabilizing selection on two quantitative traits. We show that a high level of gene flow from a mainland population is required to significantly affect the orientation of the G -matrix in an island population. The changes caused by the introgression of the mainland alleles into the island population affect all aspects of the shape of G (size, eccentricity, and orientation) and lead to the alignment of gmax with the line of divergence between the two populations' phenotypic optima. Those changes decrease with increased correlation in mutational effects and with a correlated selection. Our results suggest that high migration rates, such as those often seen at the intraspecific level, will substantially affect the shape and orientation of G, whereas low migration (e.g., at the interspecific level) is unlikely to substantially affect the evolution of G. [source] THE MUTATION MATRIX AND THE EVOLUTION OF EVOLVABILITYEVOLUTION, Issue 4 2007Adam G. Jones Evolvability is a key characteristic of any evolving system, and the concept of evolvability serves as a unifying theme in a wide range of disciplines related to evolutionary theory. The field of quantitative genetics provides a framework for the exploration of evolvability with the promise to produce insights of global importance. With respect to the quantitative genetics of biological systems, the parameters most relevant to evolvability are the G -matrix, which describes the standing additive genetic variances and covariances for a suite of traits, and the M -matrix, which describes the effects of new mutations on genetic variances and covariances. A population's immediate response to selection is governed by the G -matrix. However, evolvability is also concerned with the ability of mutational processes to produce adaptive variants, and consequently the M -matrix is a crucial quantitative genetic parameter. Here, we explore the evolution of evolvability by using analytical theory and simulation-based models to examine the evolution of the mutational correlation, r,, the key parameter determining the nature of genetic constraints imposed by M. The model uses a diploid, sexually reproducing population of finite size experiencing stabilizing selection on a two-trait phenotype. We assume that the mutational correlation is a third quantitative trait determined by multiple additive loci. An individual's value of the mutational correlation trait determines the correlation between pleiotropic effects of new alleles when they arise in that individual. Our results show that the mutational correlation, despite the fact that it is not involved directly in the specification of an individual's fitness, does evolve in response to selection on the bivariate phenotype. The mutational variance exhibits a weak tendency to evolve to produce alignment of the M -matrix with the adaptive landscape, but is prone to erratic fluctuations as a consequence of genetic drift. The interpretation of this result is that the evolvability of the population is capable of a response to selection, and whether this response results in an increase or decrease in evolvability depends on the way in which the bivariate phenotypic optimum is expected to move. Interestingly, both analytical and simulation results show that the mutational correlation experiences disruptive selection, with local fitness maxima at ,1 and +1. Genetic drift counteracts the tendency for the mutational correlation to persist at these extreme values, however. Our results also show that an evolving M -matrix tends to increase stability of the G -matrix under most circumstances. Previous studies of G -matrix stability, which assume nonevolving M -matrices, consequently may overestimate the level of instability of G relative to what might be expected in natural systems. Overall, our results indicate that evolvability can evolve in natural systems in a way that tends to result in alignment of the G -matrix, the M -matrix, and the adaptive landscape, and that such evolution tends to stabilize the G -matrix over evolutionary time. [source] EPISTASIS AND THE TEMPORAL CHANGE IN THE ADDITIVE VARIANCE-COVARIANCE MATRIX INDUCED BY DRIFTEVOLUTION, Issue 8 2004Carlos López-Fanjul Abstract The effect of population bottlenecks on the components of the genetic covariance generated by two neutral independent epistatic loci has been studied theoretically (additive, covA; dominance, covD; additive-by-additive, covAA; additive-by-dominance, covAD; and dominance-by-dominance, covDD). The additive-by-additive model and a more general model covering all possible types of marginal gene action at the single-locus level (additive/dominance epistatic model) were considered. The covariance components in an infinitely large panmictic population (ancestral components) were compared with their expected values at equilibrium over replicates randomly derived from the base population, after t consecutive bottlenecks of equal size N (derived components). Formulae were obtained in terms of the allele frequencies and effects at each locus, the corresponding epistatic effects and the inbreeding coefficient Ft. These expressions show that the contribution of nonadditive loci to the derived additive covariance (covAt) does not linearly decrease with inbreeding, as in the pure additive case, and may initially increase or even change sign in specific situations. Numerical examples were also analyzed, restricted for simplicity to the case of all covariance components being positive. For additive-by-additive epistasis, the condition covAt > covA only holds for high frequencies of the allele decreasing the metric traits at each locus (negative allele) if epistasis is weak, or for intermediate allele frequencies if it is strong. For the additive/dominance epistatic model, however, covAt > covA applies for low frequencies of the negative alleles at one or both loci and mild epistasis, but this result can be progressively extended to intermediate frequencies as epistasis becomes stronger. Without epistasis the same qualitative results were found, indicating that marginal dominance induced by epistasis can be considered as the primary cause of an increase of the additive covariance after bottlenecks. For all models, the magnitude of the ratio covAt/covA was inversely related to N and t. [source] CONSTANCY OF THE G MATRIX IN ECOLOGICAL TIMEEVOLUTION, Issue 6 2004Mats BjÖrklund Abstract The constancy of the genetic variance-covariance matrix (G matrix) across environments and populations has been discussed and tested empirically over the years but no consensus has so far been reached. In this paper, I present a model in which morphological traits develop hierarchically, and individuals differ in their resource allocation and acquisition patterns. If the variance in resource acquisition is many times larger than the variance in resource allocation then strong genetic correlations are expected, and with almost isometric relations among traits. As the variation in resource acquisition decreases below a certain threshold, the correlations decrease overall and the relations among traits become a function of the allocation patterns, and in particular reflecting the basal division of allocation. A strong bottleneck can break a pattern of strong genetic correlation, but this effect diminishes rapidly with increasing bottleneck size. This model helps to understand why some populations change their genetic correlations in different environments, whereas others do not, since the key factor is the relation between the variances in resource acquisition and allocation. If a change in environment does not lead to a change in this ratio, no change can be expected, whereas if the ratio is changed substantially then major changes can be expected. This model can also help to understand the constancy of morphological patterns within larger taxa as a function of constancy in resource acquisition patterns over time and environments. When this pattern breaks, for example on islands, larger changes can be expected. [source] SIMPLIFYING THE CLASS IV LINGUAL MATRIXJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 5 2005Gerald E. Denehy DDS [source] KINETIC BEHAVIOR OF SOYBEAN LIPOXYGENASE: A COMPARATIVE STUDY OF THE FREE ENZYME AND THE ENZYME IMMOBILIZED IN AN ALGINATE SILICA SOL-GEL MATRIX,JOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2000AN-FEI HSU Lipoxygenase (LOX) is an enzyme that regioselectively introduces a hydroperoxide into polyunsaturated fatty acids (PUFA). We recently reported a procedure that immobilizes soybean LOX within an alginate sol-gel matrix. In this study, the kinetic profile of free LOX was compared with that of the sol-gel immobilized LOX. The temperature dependent activity profile of free LOX was optimal at 25C whereas immobilized LOX had optimal activity over the temperature range of 25,35C. Enzyme activity, measured in aqueous buffer, for both the free and immobilized LOX preparations had Km values of 2.5 and 1.40 mmoles/L, respectively, and Vmax values of 0.056 and 0.02 ,mol/min, respectively. The relative rates of oxidation of linoleic acid and acylgfycerols containing linoleoyl residues catalyzed by free and immobilized LOX also were determined The results showed that both free and immobilized LOX favor linoleic acid as a substrate. Relative substrate preference for free LOX was linoleic acid >1-monolinolein > 1,3-dilinolein >trilinolein, and for immobilized LOX was linoleic acid >l, 3-dilinolein >1-monolinolein >trilinolein. In general, LOX immobilized in alginate silica sol-gel matrix retained the physical and chemical characteristics of free LOX. [source] Criminal cognitions and personality: what does the PICTS really measure?CRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 3 2000Dr Vincent Egan Introduction The Psychological Inventory of Criminal Thinking Styles (PICTS) is a measure of the criminal cognitions and thinking styles that maintain offending. The scale comprises 8 a priori thinking styles and two validation scales, the validation scales having been found to be unreliable. Owing to the large amount of apparently shared variance in the original validation study, this data matrix needs re-analysis. Results from the PICTS were examined in relation to general measures of individual differences, in order to link the PICTS to the broader literature on the characteristics of offenders. Method The original PICTS data-matrix was re-analysed using a more parsimonious method of analysis. The PICYS was also given to 54 detained, mentally disordered offenders along with the NEO-Five Factor Inventory, the Sensation-Seeking Scale (SSS), the Attention Deficit Scales for Adults (ADSA) and, as a measure of general intelligence, the Standard Progressive Matrices. Results Principal components analysis suggested that the PICTS really comprised two factors: a lack of thoughtfulness (i.e. lack of attention to one's experience), and wilful hostility, with the first factor being most well defined. Intelligence was not associated with any factor of criminal thinking style. High scores on the ADSA and Disinhibition and Boredom Susceptibility subscales of the SSS were associated with much greater endorsement of criminal sentiments; high Neuroticism, low Extroversion, and low Agreeableness were slightly lower correlates. Discussion The issues involved in criminogenic cognitions need clarification and to be linked to the broader literature on cognitive distortions and personality. Interventions targeted at dismantling impulsive destructive behaviour, whether it be thoughtlessness or wilful hostility, may be effected by increasing thinking skills, so breaking down the cognitions that maintain criminal behaviour. Copyright © 2000 Whurr Publishers Ltd. [source] The antecedents of non-affective psychosis in a birth-cohort, with a focus on measures related to cognitive ability, attentional dysfunction and speech problemsACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2010J. Welham Welham J, Scott J, Williams GM, Najman JM, Bor W, O'Callaghan M, McGrath J. The antecedents of non-affective psychosis in a birth-cohort, with a focus on measures related to cognitive ability, attentional dysfunction, and speech problems. Objective:, Adults with non-affective psychosis show subtle deviations in a range of developmental trajectories as children and adolescents. Method:, Based on a birth-cohort (n = 3801), we examined the Peabody Picture Vocabulary Test (PPTV) at age 5, and Raven's Standard Progressive Matrices (RSPM) and Wide Range Achievement Test reading scale (WRAT-R) at age 14. Items related to speech problems and attentional dysfunction were available from maternal- or self-report. At age 21, we identified 60 cohort members who were screen-positive for non-affective psychosis (SP-NAP). Results:, Impaired performance on the PPVT and RSPM (but not WRAT-R) predicted SP-NAP for males only. Male cohort members in the highest quartile for attentional dysfunction at ages 5 and 14 were about 5,8 times more likely to develop SP-NAP. SP-NAP in males was significantly associated with speech problems at age 14. Conclusion:, Males who develop non-affective psychoses have subtle impairments in cognitive capacity prior to the development of their psychotic disorder. [source] Stability Enhancement of All-Solid-State H+ ISEs with Cross-Linked Silicon-Urethane MatricesELECTROANALYSIS, Issue 8 2005Nak-Hyun Kwon Abstract An all-solid-state hydrogen-ion-selective electrode (ASHISE) was fabricated using the polymer hybrid membrane. Polymer membranes composed of Tecoflex polyurethane (TPU), polyvinyl chloride (PVC), silicon rubber (SR), and additives (KTpClPB, DOA, and TDDA) were cast on a carbon rod. The TPU/SR hybrid membrane exhibited a longer lifetime and a higher sensitivity in the sensing of the H+ ion compared to conventional TPU/PVC and PVC/SR hybrid membranes. Moreover, the addition of SiCl4 to TPU-based matrices enhanced the potentiometric response and ISE stability, due to the chemical bonding between Si and CO in urethane, in which the cross-linking configuration was confirmed by DSC, FT-IR, and XPS experiments. TPU/SR membranes containing SiCl4 were rendered more stable and showed a pH response over a wide range (i.e., pH,2,11.5) with the slope of 60±2,mV/pH for more than four months. The ASHISE exhibited a small interfering potential variation in the wide range of the salt concentration (from 1.0×10,6,M up to 0.1,M). The ASHISE showed a result comparable to a commercial clinical blood analyzer. [source] Heavy Metals in Matrices of Food Interest: Sequential Voltammetric Determination at Trace and Ultratrace Level of Copper, Lead, Cadmium, Zinc, Arsenic, Selenium, Manganese and Iron in MealsELECTROANALYSIS, Issue 18 2004Clinio Locatelli Abstract The voltammetric methods are very suitable and versatile techniques for the simultaneous metal determination in complex matrices. The present work, regarding the sequential determination of Cu(II), Pb(II), Cd(II), Zn(II) by square-wave anodic stripping voltammetry (SWASV), As(III), Se(IV) by square-wave cathodic stripping voltammetry (SWCSV) and Mn(II), Fe(III) by square-wave voltammetry (SWV) in matrices involved in foods and food chain as wholemeal, wheat and maize meal, are an interesting example of the possibility to sequentially determine each single element in real samples. Besides the set up of the analytical method, particular attention is aimed either at the problem of possible signal interference or to show that, using the peak area Ap as instrumental datum, it is possible to achieve lower limits of detection. The analytical procedure was verified by the analysis of the standard reference materials: Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. Precision, as repeatability, and accuracy, expressed as relative standard deviation and relative error, respectively, were lower than 6% in all cases. In the presence of reciprocal interference, the standard addition method considerably improved the resolution of the voltammetric technique. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meals sampled on market for sale. A critical comparison with spectroscopic measurements is also discussed. [source] Photochemistry of cis -3-Diazo-5,6-dimethyl-1,4-oxathian-2-one S -Oxide in Argon MatricesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2006Orlagh C. M. O'Sullivan Abstract The photochemistry of the ,-diazo sulfoxide 7 has been investigated in solid argon at 10 K by IR spectroscopy. The sulfinyl carbene was not detected directly but instead underwent photochemically induced hetero-Wolff rearrangement to the sulfine 8 which could be detected and characterized following irradiation at 248 nm. Further photochemical reaction of this intermediate led to the oxathiirane 9 which was most readily detected on irradiation of 7 at 308 nm. The matrix-isolated species were identified by comparison of experimental and calculated IR spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] The Frequency Accrual Speed Test (FAST): psychometric intelligence and personality correlatesEUROPEAN JOURNAL OF PERSONALITY, Issue 2 2001Ulrich Ettinger Performance on a putative psychophysical measure of information processing related to intelligence (Vickers' 1995 Frequency Accrual Speed Test, FAST) was assessed in relation to two psychometric measures of intelligence (Raven's Advanced Progressive Matrices and the Mill Hill vocabulary test). Participants (N,=,57) completed the Eysenck Personality Questionnaire , Revised (EPQ-R), and performed the FAST task under either low (70 dB) or high (90 dB) levels of white noise. FAST correlated with Raven's (r,=,0.56) and Mill Hill (r,=,0.28), as expected. FAST total scores were not affected by personality or personality-by-noise interactions. However, a measure of consistency of FAST performance (i.e. the standard deviation) was correlated negatively with total FAST scores (r,=,,0.37) and positively with (EPQ-R) extraversion (r,=,0.34). The results are discussed in terms of the validity of the FAST to explicate the information processing variables in psychometric intelligence. Copyright © 2001 John Wiley & Sons, Ltd. [source] On the measurement of social orientations in the minimal group paradigm: norms as moderators of the expression of intergroup biasEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 2 2001Lowell Gaertner Contrary to most other research conducted in the minimal group paradigm tradition, Bornstein, Crum, Wittenbraker, Harring, Insko and Thibaut (1983a) found little evidence of ingroup favoritism when they employed a revised measurement system (i.e. the Multiple Alternative Matrices; MAMs). The current experiment examined whether Bornstein et al.'s effects could be attributed to norms that prohibit intergroup discrimination, which are made salient by framing the outcome values in the intergroup allocation task as monetary payment. We manipulated the salience of prohibitive norms by varying whether participants allocated on the MAMs monetary payment, bonus money or feelings. Participants more strongly associated ,having to be fair and equal' with payment than with bonus or feelings and category members made fewer allocations that maximized the ingroup's relative and absolute profit and more allocations that minimized intergroup differences when allocating monetary payment than when allocating bonus money or feelings. Copyright © 2001 John Wiley & Sons, Ltd. [source] Porous Structures: In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide-Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative Engineering (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Mater. Abstract Synthetic biodegradable polymers serve as temporary substrates that accommodate cell infiltration and tissue in-growth in regenerative medicine. To allow tissue in-growth and nutrient transport, traditional three-dimensional (3D) scaffolds must be prefabricated with an interconnected porous structure. Here we demonstrated for the first time a unique polymer erosion process through which polymer matrices evolve from a solid coherent film to an assemblage of microspheres with an interconnected 3D porous structure. This polymer system was developed on the highly versatile platform of polyphosphazene-polyester blends. Co-substituting a polyphosphazene backbone with both hydrophilic glycylglycine dipeptide and hydrophobic 4-phenylphenoxy group generated a polymer with strong hydrogen bonding capacity. Rapid hydrolysis of the polyester component permitted the formation of 3D void space filled with self-assembled polyphosphazene spheres. Characterization of such self-assembled porous structures revealed macropores (10,100 ,m) between spheres as well as micro- and nanopores on the sphere surface. A similar degradation pattern was confirmed in vivo using a rat subcutaneous implantation model. 12 weeks of implantation resulted in an interconnected porous structure with 82,87% porosity. Cell infiltration and collagen tissue in-growth between microspheres observed by histology confirmed the formation of an in situ 3D interconnected porous structure. It was determined that the in situ porous structure resulted from unique hydrogen bonding in the blend promoting a three-stage degradation mechanism. The robust tissue in-growth of this dynamic pore forming scaffold attests to the utility of this system as a new strategy in regenerative medicine for developing solid matrices that balance degradation with tissue formation. [source] In situ Porous Structures: A Unique Polymer Erosion Mechanism in Biodegradable Dipeptide-Based Polyphosphazene and Polyester Blends Producing Matrices for Regenerative EngineeringADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Meng Deng Abstract Synthetic biodegradable polymers serve as temporary substrates that accommodate cell infiltration and tissue in-growth in regenerative medicine. To allow tissue in-growth and nutrient transport, traditional three-dimensional (3D) scaffolds must be prefabricated with an interconnected porous structure. Here a unique polymer erosion process through which polymer matrices evolve from a solid coherent film to an assemblage of microspheres with an interconnected 3D porous structure is demonstrated for the first time. This polymer system is developed on the highly versatile platform of polyphosphazene-polyester blends. Co-substituting a polyphosphazene backbone with both hydrophilic glycylglycine dipeptide and hydrophobic 4-phenylphenoxy group generates a polymer with strong hydrogen bonding capacity. Rapid hydrolysis of the polyester component permits the formation of 3D void space filled with self-assembled polyphosphazene spheres. Characterization of such self-assembled porous structures reveals macropores (10,100 ,m) between spheres as well as micro- and nanopores on the sphere surface. A similar degradation pattern is confirmed In vivo using a rat subcutaneous implantation model. 12 weeks of implantation results in an interconnected porous structure with 82,87% porosity. Cell infiltration and collagen tissue in-growth between microspheres observed by histology confirms the formation of an in situ 3D interconnected porous structure. It is determined that the in situ porous structure results from unique hydrogen bonding in the blend promoting a three-stage degradation mechanism. The robust tissue in-growth of this dynamic pore forming scaffold attests to the utility of this system as a new strategy in regenerative medicine for developing solid matrices that balance degradation with tissue formation. [source] Simultaneous Immobilization of Bioactives During 3D Powder Printing of Bioceramic Drug-Release MatricesADVANCED FUNCTIONAL MATERIALS, Issue 10 2010Elke Vorndran Abstract The combination of a degradable bioceramic scaffold and a drug-delivery system in a single low temperature fabrication step is attractive for the reconstruction of bone defects. The production of calcium phosphate scaffolds by a multijet 3D printing system enables localized deposition of biologically active drugs and proteins with a spatial resolution of approximately 300,µm. In addition, homogeneous or localized polymer incorporation during printing with HPMC or chitosan hydrochloride allows the drug release kinetics to be retarded from first to zero order over a period of 3,4 days with release rates in the range 0.68%,0.96%,h,1. The reduction in biological activity of vancomycin, heparin, and rhBMP-2 following spraying through the ink jet nozzles is between 1% and 18%. For vancomycin, a further loss of biological activity following incorporation into a cement and subsequent in vitro release is 11%. While previously acknowledged as theoretically feasible, is its shown for the first time that bone grafts with simultaneous geometry, localized organic bioactive loading, and localized diffusion control are a physical reality. This breakthrough offers a new future for patients by providing the required material function to match patient bone health status, site of repair, and age. [source] Dye-Doped Polyhedral Oligomeric Silsesquioxane (POSS)-Modified Polymeric Matrices for Highly Efficient and Photostable Solid-State LasersADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Roberto Sastre Abstract Here, the design, synthesis, and characterization of laser nanomaterials based on dye-doped methyl methacrylate (MMA) crosslinked with octa(propyl-methacrylate) polyhedral oligomeric silsesquioxane (8MMAPOSS) is reported in relation to their composition and structure. The influence of the silicon content on the laser action of the dye pyrromethene 567 (PM567) is analyzed in a systematic way by increasing the weight proportion of POSS from 1 to 50%. The influence of the inorganic network structure is studied by replacing the 8MMAPOSS comonomer by both the monofunctionalized heptaisobutyl-methacryl-POSS (1MMAPOSS), which defines the nanostructured linear network with the POSS cages appearing as pendant groups of the polymeric chains, and also by a new 8-hydrogenated POSS incorporated as additive to the polymeric matrices. The new materials exhibit enhanced thermal, optical, and mechanical properties with respect to the pure organic polymers. The organization of the molecular units in these nanomaterials is studied through a structural analysis by solid-state NMR. The domain size of the dispersed phase assures a homogeneous distribution of POSS into the polymer, thus, a continuous phase corresponding to the organic matrix incorporates these nanometer-sized POSS crosslinkers at a molecular level, in agreement with the transparency of the samples. The silicon,oxygen core framework has to be covalently bonded into the polymer backbone instead of being a simple additive and both the silica content and crosslinked degree exhibit a critical influence on the laser action. [source] Protein-Enabled Synthesis of Monodisperse Titania Nanoparticles On and Within Polyelectrolyte MatricesADVANCED FUNCTIONAL MATERIALS, Issue 14 2009Eugenia Kharlampieva Abstract Here, the results of a study of the mechanism of bio-enabled surface-mediated titania nanoparticle synthesis with assistance of polyelectrolyte surfaces are reported. By applying atomic force microscopy, surface force spectroscopy, circular dichroism, and in situ attenuated total reflection Fourier-transform infrared spectroscopy, structural changes of rSilC-silaffin upon its adsorption to polyelectrolyte surfaces prior to and during titania nanoparticle growth are revealed. It is demonstrated that the adhesion of rSilC-silaffin onto polyelectrolyte surfaces results in its reorganization from a random-coil conformation in solution into a mixed secondary structure with both random coil and , -sheet structures presented. Moreover, the protein forms a continuous molecularly thin layer with well-defined monodisperse nanodomains of lateral dimensions below 20,nm. It is also shown that rSilC embedded inside the polylelectrolyte matrix preserves its titania formation activity. It is suggested that the surface-mediated, bio-enabled synthesis of nanostructured materials might be useful to develop general procedures for controlled growth of inorganic nanomaterials on reactive organic surfaces, which opens new perspectives in the design of tailored, in situ grown, hybrid inorganic,organic nanomaterials. [source] Investigating Global and Local Categorical Map Configuration Comparisons Based on Coincidence MatricesGEOGRAPHICAL ANALYSIS, Issue 2 2009T. K. Remmel The simple and intuitive nature of the coincidence matrix has not only made it the current "gold standard" for accuracy assessment (based on a sample of map pixels), but also a common tool for describing difference between two categorical maps (when all pixels are enumerated). It is this latter case of map comparison that this article explores. Coincidence matrices, although providing significant information regarding thematic agreement between two categorical maps (composition), can lack significantly in terms of conveying information about differences or similarities in the spatial arrangement (configuration) of those map categories in geographic space. This article introduces means for distilling the available configuration information from a coincidence matrix while demonstrating some simple categorical map comparisons. Specifically, while the coincidence matrix summarizes per-pixel compositional persistence or change, the introduced technique further quantifies the global and local configurational uncertainty between compared maps. I demonstrate how this quantification of configurational uncertainty can be used to gauge which thematic mismatch types are most significant and how to measure/present local configurational uncertainty in a spatial context. Implementation is through a straightforward mathematical algorithm in R that is illustrated by several examples. La sencillez y características las matrices de confusión (tablas de contingencia o de error) no sólo la ha convertido en (1) el estándar por excelencia para la evaluación de confiabilidad (veracidad o validez) de mapas temáticos en escala nominal (en base de una muestra de pixeles en un mapa), sino también en (2) una herramienta común para describir la diferencia entre dichos mapas (cuando todos los pixeles son tomados en cuenta). Este segundo uso de las matrices de confusión es el tema explorado por el presente artículo. A pesar de proporcionar información importante acerca de la confiabilidad temática entre dos mapas de categorías nominales (composición), las matrices de confusión sufren de limitaciones importantes cuando el objetivo es extraer información acerca del patrón o arreglo espacial (configuración) de las categorías del mapa. El presente artículo presenta herramientas para destilar la información de configuración espacial disponible a partir de una matriz de confusión, y al mismo tiempo, ilustra algunas comparaciones entre mapas de categorías nominales. En términos más concretos, la matriz de confusión resume la persistencia o cambio en la composición a nivel de cada pixel. La nueva técnica presentada en este estudio incluye además la cuantificación de la incertidumbre en la configuración de los mapas comparados. El autor demuestra cómo esta cuantificación puede ser utilizada para darse una idea de cuáles tipos de errores temáticos son más importantes, y cómo se puede medir e ilustrar la incertidumbre de la configuración local en el contexto espacial. La implementación del método se realiza a través de un algoritmo matemático sencillo en lenguaje R, el mismo que es ilustrado con varios ejemplos. [source] Tissue Engineering: Scaffold-Mediated 2D Cellular Orientations for Construction of Three Dimensionally Engineered Tissues Composed of Oriented Cells and Extracellular Matrices (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Mater. Novel technology for fabrication of 3D-engineered tissues consisting of oriented cells and extracellular matrices (ECM) is described by Yoshida and co-workers on page 1001. They prepare disulfide-crosslinked hydrogels with oriented pores to induce cellular orientations on and in the scaffolds. Finally, 3D-oriented engineered tissues with 2D-cell and ECM orientation are successfully obtained by decomposing template gel with reductant agent. [source] Scaffold-Mediated 2D Cellular Orientations for Construction of Three Dimensionally Engineered Tissues Composed of Oriented Cells and Extracellular MatricesADVANCED FUNCTIONAL MATERIALS, Issue 7 2009Hiroaki Yoshida Abstract Various hydrogels, such as poly(, -glutamic acid) (, -PGA), gelatin (GT), alginic acid (Alg), and agarose (Aga), with 3D interconnected and oriented fibrous pores (OP gels) are prepared for 3D polymeric cellular scaffolds by using silica fiber cloth (SC) as template. After the preparation of these hydrogels with the SC templates, the latter are subsequently removed by washing with hydrofluoric acid solution. Scanning electron microscopy (SEM) clearly shows OP structures in the hydrogels. These various types of OP gels are successfully prepared in this way, independently of the crosslinking mechanism, such as chemical (, -PGA or GT), coordinate-bonded (Alg), or hydrogen-bonded (Aga) crosslinks. SEM, confocal laser scanning microscopy, and histological evaluations clearly demonstrate that mouse L929 fibroblast cells adhere to and extend along these OP structures on/in , -PGA hydrogels during 3D cell culture. The L929 cells that adhere on/in the oriented hydrogel are viable and proliferative. Furthermore, 3D engineered tissues, composed of the oriented cells and extracellular matrices (ECM) produced by the cells, are constructed in vitro by subsequent decomposition of the hydrogel with cysteine after 14 days of cell culture. This novel technology to fabricate 3D-engineered tissues, consisting of oriented cells and ECM, will be useful for tissue engineering. [source] Rapid Determination of Gallamine Triethiodide (Flaxedil®) and Pancuronium Bromide (Pavulon®) in Pharmaceutical and Urine Matrices by Means of Modified-Carbon-Paste Ion-Selective ElectrodesHELVETICA CHIMICA ACTA, Issue 4 2005A new analytical method for the determination of gallamine triethiodide (Flaxedil®; 1) and pancuronium bromide (Pavulon®; 2), two muscle relaxants used in surgical operations and in pain relief, has been developed. Our approach relies on rapid, precise, and sensitive potentiometric sensors based on modified-carbon-paste ion-selective electrodes (CP-ISEs). Linear calibration graphs in the working ranges of ca. 4.5,892 and 7.3,733,,g/ml (in H2O, pH,7.0, T=25°) were established for 1 and 2, respectively; and Nernst slopes corresponding to three- or two-electrons transfers, respectively, were obtained. The method works best in a pH range of 7,9. Average relative errors of 2.12 and 2.14%, with average standard deviations of 1.98,2.47 and 2.64,3.45, respectively, were obtained for urine samples of 1 and 2. The corresponding relative errors for the pharmaceutical samples were 1.59 and 1.64%, with standard deviations of 0.54,1.34 and 0.52,1.67, respectively. Statistical Student and F tests were applied to the data, and satisfactory results were obtained. [source] Dynamic Hydrogels: Switching of 3D Microenvironments Using Two-Component Naturally Derived Extracellular Matrices (Adv. Mater.ADVANCED MATERIALS, Issue 6 20106/2010) The front cover image depicts a two-component extracellular matrix (ECM) in which one component acts as a stable structural element (which supports cell attachment and migration) and another component gels or dissolves reversibly (a modulatory component). Samuel K. Sia and co-workers show on p. 686 that by dynamically adding or removing crosslinks in the modulatory component, properties of the composite ECM, such as the ability of cells to migrate and the rate of diffusive transport, can be altered. [source] Dynamic Hydrogels: Switching of 3D Microenvironments Using Two-Component Naturally Derived Extracellular MatricesADVANCED MATERIALS, Issue 6 2010Brian M. Gillette This article describes fabrication of a two-component extracellular matrix (ECM) in which one component acts as a stable structural element and another component gels or dissolves reversibly (a modulatory component). Using a composite collagen-alginate ECM, reversible crosslinking of the alginate (the modulatory component) via application of calcium or citrate modulates cell mobility in a 3D collagen matrix (the structural component). [source] UMD-predictor, a new prediction tool for nucleotide substitution pathogenicity,application to four genes: FBN1, FBN2, TGFBR1, and TGFBR2,HUMAN MUTATION, Issue 6 2009Mélissa Yana Frédéric Abstract Approximately half of gene lesions responsible for human inherited diseases are due to an amino acid substitution, showing that this mutational mechanism plays a large role in diseases. Distinguishing neutral sequence variations from those responsible for the phenotype is of major interest in human genetics. Because in vitro validation of mutations is not always possible in diagnostic settings, indirect arguments must be accumulated to define whether a missense variation is causative. To further differentiate neutral variants from pathogenic nucleotide substitutions, we developed a new tool, UMD-Predictor®. This tool provides a combinatorial approach that associates the following data: localization within the protein, conservation, biochemical properties of the mutant and wild-type residues, and the potential impact of the variation on mRNA. To evaluate this new tool, we compared it to the SIFT, PolyPhen, and SNAP software, the BLOSUM62 and Yu's Biochemical Matrices. All tools were evaluated using variations from well-validated datasets extracted from four UMD,LSDB databases (UMD,FBN1, UMD,FBN2, UMD,TGFBR1, and UMD,TGFBR2) that contain all published mutations of the corresponding genes, that is, 1,945 mutations, among which 796 different substitutions corresponding to missense mutations. Our results show that the UMD-Predictor® algorithm is the most efficient tool to predict pathogenic mutations in this context with a positive predictive value of 99.4%, a sensitivity of 95.4%, and a specificity of 92.2%. It can thus enhance the interpretation of variations in these genes, and could easily be applied to any other disease gene through the freely available UMD® generic software (http://www.umd.be). Hum Mutat 30:1,8, 2009. © 2009 Wiley-Liss, Inc. [source] A Global Approach to Fiber nD Architectures and Self-Sealing Matrices: From Research to ProductionINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2 2005F. A. Christin Thermostructural composites (TSC) improvement is one of the key factors to ensure future competitiveness of aeronautical and space engines. The TSC technology developed in Snecma Propulsion Solide is based on continuous fiber-reinforced composites and carbon or ceramics matrices deposited by chemical vapor infiltration. This article presents a status of the latest improvements for cost savings of composite reinforcements (so-called texture) and specific matrices developed to increase both durability and temperature capability of previous ceramic composites, operating in oxidative environments. [source] The effect of chronic benzodiazepine use on cognitive functioning in older persons: good, bad or indifferent?INTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 12 2007E. J. M. Bierman Abstract Objective This study investigates the effects of benzodiazepine (BZ) use on cognitive performance in elderly persons in a longitudinal design. Study design and setting Data were obtained from the Longitudinal Aging Study Amsterdam (LASA), in the Netherlands. 2,105 respondents (,62 years of age) were included and had repeated measurements over a period of 9 years. For all BZs the type, dosage, frequency and duration of use was measured. The equivalent of a dose of diazepam was determined with regard to type and dosage and a cumulative dosage was calculated. General cognitive functioning was measured with the Mini-Mental State Examination, information processing speed was measured with the coding task, fluid intelligence with Raven's Coloured Progressive Matrices and episodic memory with the Auditory Verbal Learning Test. Multilevel analyses were used to investigate the relationship between BZ use and cognitive decline. Results A negative effect of BZ use on cognitive performance was found. However, the effect sizes were very small. Conclusion This study suggests that both duration and cumulative exposure to BZ has a small negative effect on the long-term cognitive functioning of elderly people in the community. Copyright © 2007 John Wiley & Sons, Ltd. [source] Resilience in relation to personality and intelligenceINTERNATIONAL JOURNAL OF METHODS IN PSYCHIATRIC RESEARCH, Issue 1 2005Oddgeir Friborg Abstract Resilience is a construct of increasing interest, but validated scales measuring resilience factors among adults are scarce. Here, a scale named the Resilience Scale for Adults (RSA) was crossvalidated and compared with measures of personality (Big Five/5PFs), cognitive abilities (Raven's Advanced Matrices, Vocabulary, Number series), and social intelligence (TSIS). All measures were given to 482 applicants for the military college. Confirmatory factor analyses confirmed the fit of the five-factor model, measuring ,personal strength', ,social competence', ,structured style', ,family cohesion' and ,social resources'. Using Big Five to discriminate between well adjusted and more vulnerable personality profiles, all resilience factors were positively correlated with the well adjusted personality profile. RSA-personal strength was most associated with 5PFs-emotional stability, RSA-social competence with 5PFs-extroversion and 5PFs-agreeableness, as well as TSIS-social skills, RSA-structured style with 5PFs-conscientiousness. Unexpectedly but interestingly, measures of RSA-family cohesion and RSA-social resources were also related to personality. Furthermore, the RSA was unrelated to cognitive abilities. This study supported the convergent and discriminative validity of the scale, and thus the inference that individuals scoring high on this scale are psychologically healthier, better adjusted, and thus more resilient. Copyright © 2005 Whurr Publishers Ltd. [source] Positive Presentation Management and Intelligence and the Personality Differentiation by Intelligence Hypothesis in Job ApplicantsINTERNATIONAL JOURNAL OF SELECTION AND ASSESSMENT, Issue 2 2006Filip De Fruyt Both positive presentation management (PPM) and intelligence are considered as factors influencing the variability of personality self-descriptions. The relationship between PPM and intelligence and the personality differentiation by intelligence hypothesis were examined in a large sample (N=20,183) of job applicants administered the Standard Progressive Matrices and the NEO-PI-R. A composite of 10 NEO-PI-R items served as a PPM marker. Contrary to expectations, PPM and intelligence were not related. Only the variance in openness scores was slightly and linearly associated with IQ, and the variance for neuroticism and extraversion scores was somewhat higher in the IQ range beyond 115. However, congruence and Structural Equation Modelling analyses comparing personality structures for different IQ samples underscored the structural invariance of the NEO-PI-R. It is concluded that the NEO-PI-R keeps its structural properties for individuals across the IQ distribution in selection assessment. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||