1,721,208 research outputs found
COMPORTAMENTO TERMICO DEL POLI-P-FENILEN SOLFURO SEGUITO MEDIANTE SPETTROSCOPIA INFRAROSSA
No full textElectrical behaviour of poly(p-phenylene sulfide) conducting composites
No full textThe resistivity of poly(p-phenylene sulfide) (I) filled with Fe, graphite, or acetylene carbon black was presented as a function of the vol. fraction of filler. The effective medium approxn. theory and the gel theory proposed by Flory were used to fit the exptl. data. The 2 theories gave crit. thresholds quite different from the exptl. ones. The active contribution of I matrix to the elec. charge transport must be excluded
Logarithmic Sobolev inequalities in non-commutative algebras
No full textWe study the relations between (tight) logarithmic Sobolev inequalities, entropy decay and spectral gap inequalities for Markov evolutions on von Neumann algebras. We prove that log-Sobolev inequalities (in the non-commutative form defined by Olkiewicz and Zegarlinski in Ref. 25) imply spectral gap inequalities, with optimal relation between the constants. Furthermore, we show that a uniform exponential decay of a proper relative entropy is equivalent to a modified version of log-Sobolev inequalities. The relations among the mentioned inequalities are investigated and often depend on some regularity conditions, which are also discussed. With regard to this aspect, we provide an example of a positive identity-preserving semigroup not verifying the usually requested regularity conditions (which are always fulfilled for reversible classical Markov processes)
Matrix Spatial Specification models
Full text linkIn this paper we study a family of linear regression models with spatial dependence in the errors and in the dependent variable. The spatial dependence is modeled by arbitrary matrix functions Vn and Mn respectively, indexed by a scalar parameter and, eventually, by two (possibly distinct) weight matrices, D and W.
We define the quasi maximum likelihood estimator and study its asymptotic properties under non-Gaussian errors. We use the results on the general model to define a wide class of spatial models, defined as matrix transformations of a given weight matrix. This family is large enough to encompass some popular models used in the spatial econometric literature, such as SARAR and MESS models. By defining broad families of models, where matrix transformations are associated to distribution functions, we provide some insights into the difference between specifications, with emphasis on advantages and shortcomings as well as on interpretation of the parameters and correspondences between models
Generalized spatial matrix specifications
Full text linkAbstract.: In this article, we propose a model that generalizes some of the most popular choices in spatial linear modeling, such as the SAR and MESS models. Our idea builds on their representation as link functions applied to a spatial weight W, corresponding to the uniform and exponential distributions, respectively. By allowing for more general families of distribution functions, one can encompass both models and capture different spatial patterns. We provide some insights into the difference between specifications, with emphasis on advantages and shortcomings as well as on interpretation of the parameters and correspondences between models. By exploiting the possibility to obtain a formal power series representation of the link family, we define the quasi maximum likelihood estimator and study its asymptotic properties under Gaussian and non Gaussian errors. By applying our approach to data on 2000 US election participation, as in LeSage and Pace (2007), we show that this model is able to capture a finite order neighboring spillover structure, as opposed to the infinite order implied by both the SAR and MESS models
Cristallizzazione da fuso del poli(p-fenilen solfuro) seguita mediante diffrazione di raggi X a dispersione di energia
No full textCaratterizzazione chimico-fisica di polifenileni etileni cristallini e liquido cristallini
No full textPreparazione di superfici polimeriche non trombogeniche mediante aggancio di inbitori di trombina
No full textSono stati legati covalentemente sulla superficie di un polimero, un copolimero vinil alcool-etilene (70-30), inibitori reversibili di trombina quali p-amino benzamidina e dansil arginina. E' stato trovato che la trombina viene legata alla superficie dei polimeri derivatizzati in quantità dipendenti sia dalla concentrazione che dal tipo di inibitore. Il potere inibente dei materiali è stato valutato mediante test biologici in vitro (PTT). E' stato constatato che aumentando la quantità di inibitore legato si riscontra un tempo di coagulazione più lungo e che la formazione di fibrina è più lenta quando la trombina è inibita dalla dansil arginina
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