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31.
Margarete O. Domingues Sônia M. Gomes Anamaria Gomide José R. Pereira Pedro Pinho 《Journal of Computational and Applied Mathematics》2010,234(8):2377-2389
In the Sparse Point Representation (SPR) method the principle is to retain the function data indicated by significant interpolatory wavelet coefficients, which are defined as interpolation errors by means of an interpolating subdivision scheme. Typically, a SPR grid is coarse in smooth regions, and refined close to irregularities. Furthermore, the computation of partial derivatives of a function from the information of its SPR content is performed in two steps. The first one is a refinement procedure to extend the SPR by the inclusion of new interpolated point values in a security zone. Then, for points in the refined grid, such derivatives are approximated by uniform finite differences, using a step size proportional to each point local scale. If required neighboring stencils are not present in the grid, the corresponding missing point values are approximated from coarser scales using the interpolating subdivision scheme. Using the cubic interpolation subdivision scheme, we demonstrate that such adaptive finite differences can be formulated in terms of a collocation scheme based on the wavelet expansion associated to the SPR. For this purpose, we prove some results concerning the local behavior of such wavelet reconstruction operators, which stand for SPR grids having appropriate structures. This statement implies that the adaptive finite difference scheme and the one using the step size of the finest level produce the same result at SPR grid points. Consequently, in addition to the refinement strategy, our analysis indicates that some care must be taken concerning the grid structure, in order to keep the truncation error under a certain accuracy limit. Illustrating results are presented for 2D Maxwell’s equation numerical solutions. 相似文献
32.
John W.Grove 《数学物理学报(B辑英文版)》2010,30(2):563-594
This article describes mathematical models for phase separated mixtures of materials that are in pressure and velocity equilibrium but not necessarily temperature equilibrium. General conditions for constitutive models for such mixtures that exhibit a single mixture sound speed are discussed and specific examples are described. 相似文献
33.
34.
Mouad Arrad Mehriban Aliyeva Sérgio M. Vilas-Boas Mohammed Kaddami Hannu Sippola Pekka Taskinen Simão P. Pinho 《Journal of solution chemistry》2018,47(4):774-786
The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol·kg?1. 相似文献
35.
A.R. Melro P.P. Camanho F.M. Andrade Pires S.T. Pinho 《International Journal of Solids and Structures》2013,50(11-12):1906-1915
This paper presents the application of a new constitutive damage model for an epoxy matrix on micromechanical analyses of polymer composite materials. Different representative volume elements (RVEs) are developed with a random distribution of fibres. Upon application of periodic boundary conditions (PBCs) on the RVEs, different loading scenarios are applied and the mechanical response of the composite studied. Focus is given to the influence of the interface between fibre and matrix, as well as to the influence of the epoxy matrix, on the strength properties of the composite, damage initiation and propagation under different loading conditions. 相似文献
36.
Renata Monteiro-Maia Maria B Ortigão-de-Sampaio Rosa T Pinho Luiz RR Castello-Branco 《Journal of immune based therapies and vaccines》2006,4(1):1-6
We hypothesize that the energy strategy of a cell is a key factor for determining how, or if, the immune system interacts
with that cell. Cells have a limited number of metabolic states, in part, depending on the type of fuels the cell consumes.
Cellular fuels include glucose (carbohydrates), lipids (fats), and proteins. We propose that the cell's ability to switch
to, and efficiently use, fat for fuel confers immune privilege. Additionally, because uncoupling proteins are involved in
the fat burning process and reportedly in protection from free radicals, we hypothesize that uncoupling proteins play an important
role in immune privilege. Thus, changes in metabolism (caused by oxidative stresses, fuel availability, age, hormones, radiation,
or drugs) will dictate and initiate changes in immune recognition and in the nature of the immune response. This has profound
implications for controlling the symptoms of autoimmune diseases, for preventing graft rejection, and for targeting tumor
cells for destruction. 相似文献
37.
Gouveia CA Oliveira A Pinho S Vasconcelos C Carvalho F Moreira RF Dinis-Oliveira RJ 《Biomedical chromatography : BMC》2012,26(8):1041-1047
The development of analytical techniques that enable the use of hair as an alternative matrix for the analysis of drugs of abuse is useful for confirming the exposure in a larger time window (weeks to months, depending on the length of the hair shaft). In the present study a methodology aimed at the simultaneous quantification of cocaine and morphine in human hair was developed and validated. After decontamination, hair samples (20?mg) were incubated with a mixture of methanol/hydrochloric acid (2:1) at 65?°C overnight (~16?h) in order to extract the drugs of the matrix. Purification was performed by solid-phase extraction using mixed-mode extraction cartridges. After derivatization with N-methyl-N-(trimethylsilyl) trifluoroacetamide, blank, standards and samples were analyzed by gas chromatography/electron impact-mass spectrometry (GC-EI/MS). The method proved to be selective, as there were no interferences of endogenous compounds with the same retention time as cocaine, morphine and ethylmorphine (internal standard). The regression analysis for both analytes showed linearity in the range 0.25-10.00?ng/mg with correlation coefficients ranging from 0.9989 to 0.9991. The coefficients of variation oscillated between 0.83 and 14.60%. The limits of detection were 0.01 and 0.02?ng/mg, and the limits of quantification were 0.03 and 0.06?ng/mg for cocaine and morphine, respectively. The proposed GC-EI/MS method provided an accurate and simple assay with adequate precision and recovery for the quantification of cocaine and morphine in hair samples. The proof of applicability was performed in hair samples obtained from drug addicts enrolled in a Regional Detoxification Treatment Center. The importance of hair samples is highlighted, since positives results were obtained when urine immunoassay analyses were negative. Copyright ? 2012 John Wiley & Sons, Ltd. 相似文献
38.
A mathematical model consisting of a system of two ordinary differential equations is formulated to represent the interrelationship
between healthy and radiated cells at a given cite. Three different modes of radiation are considered: constant, decaying,
and periodic radiation. For the constant case, precise criteria for persistence and extinction are obtained. In the decaying
case, it is shown that the radiated cells always become extinct. Finally in the periodic case, criteria are obtained for a
perturbed positive periodic solution.
Dedicated to the memory of Professor Miklós Farkas 相似文献
39.
R.M. Zorzenon dos Santos S. T.R. Pinho C. P. Ferreira P. C.A. da Silva 《The European physical journal. Special topics》2007,143(1):125-132
Malaria is an important cause of morbidity and mortality
worldwide. One striking aspect regarding malaria is the fact that
individuals living in endemic areas do not develop immunity
against the parasite, falling ill whenever they are exposed to
the parasite. The understanding of why immunity is not developed
in the usual way against Plasmodium is crucial to the improvement of
treatment and prevention. In this work, we study
some aspects of the dynamics of the blood cycle of malaria using
both modelling and data analysis of observed case-histories
described by parasitemia time series. By comparing our simulations
with experimental results we have shown that the different
behaviour observed among patients may be associated to
differences in the efficiency of the immune system to control the
infection. 相似文献
40.
E. Pinho Melo Silvia M. B. Costa Joaquim M. S. Cabral 《Photochemistry and photobiology》1996,63(2):169-175
Abstract— Near UV absorbance and fluorescence spectroscopy show conformational changes of a recombinant cutinase from Fusarium solani incorporated in sodium-di-2-ethylhexyl sulfosuccinate (AOT)-iso-octane reversed micelles with W0 = [H2 O]/[AOT] = 20. Excitation spectra were used to decompose cutinase absorbance in its Trp and Tyr components, showing that the latter absorb red-shifted in the native cutinase in aqueous solution as compared to free Tyr, whereas in reverse micelles and denatured cutinase no shift is detected. Emission maxima variations (λmax 303, 311 and 335 nm, respectively in aqueous, reverse micelles and thermally denatured cutinase) reflect progressive changes in the micropolarity of the environment and exposure of Trp residues at the protein surface. The encapsulation of cutinase in AOT-iso-octane reversed micelles induces a time-dependent denaturation measured by fluorescence intensity changes at 330 nm, which match the profile of enzyme activity loss in this media. 相似文献