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61.
We present Laplace field microscopy as a method for generating intrinsic contrast of transparent specimens. This technique uses a spatial light modulator to perform the Laplacian of the field in the Fourier plane of a microscope image. The resulting image incorporates phase information and thus renders high contrast images from phase objects. We demonstrate the potential of the method by imaging index-matched beads, unlabeled tissue slices, and dynamic live cells. 相似文献
62.
R. Cristescu C. PopescuA.C. Popescu S. GrigorescuI.N. Mihailescu A.A. CiucuS. Iordache A. AndronieI. Stamatin E. Fagadar-CosmaD.B. Chrisey 《Applied Surface Science》2011,257(12):5293-5297
We report the deposition by MAPLE of metallized nanostructured (5,10,15,20-tetraphenyl)porphinato manganese(III) chloride thin films onto gold screen-printed electrodes, or 〈1 1 1〉 Si substrates. The deposited nanostructures were characterized by atomic force microscopy and exhibited globular structures with average diameters decreasing with laser fluence. Raman spectroscopy showed that no major decomposition appeared. We have investigated the Mn(III)-metalloporphyrin thin films by cyclic voltammetry in order to evaluate the potential bio/chemosensing activity on dopamine neurotransmitter analyte. We have found that the manganese(III)-porphyrin is appropriate as a single mediator for dopamine sensing in the specific case of gold screen-printed electrodes. 相似文献
63.
In this paper we develop a theoretical model for the magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated magnetic monodomain nanoparticles. Both dipole-field and dipole-dipole magnetic and electric interactions between the magnetic monodomain particles are taken into account in the Hamiltonian of the system. Using the pair correlation function in a colloidal suspension of magnetic nanoparticles developed by Ivanov and Kuznetsova (2001) [11], the complex dielectric constant of a magnetic colloid is modeled as a function of the light polarization direction, the magnetic field intensity and magnetic particle concentration and diameter. The two main features of the model are that, on the one hand, it predicts the possibility of magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated monodomain nanoparticles, and on the other hand, unlike the existing models for diluted samples, it predicts a non-linear dependence of dichroism and birefringence on magnetic particle concentration. 相似文献
64.
65.
Ovidiu Popescu 《Applied Mathematics Letters》2011,24(1):1-4
The aim of this paper is to extend a very recent result proved by Dori? (2009) [4], as well as other theorems given by Rhoades (2001) [2] and Dutta and Choudhury (2008) [3]. 相似文献
66.
Liviu Horia Popescu 《Journal of Differential Equations》2004,203(1):28-37
In the present work, we give necessary and sufficient conditions for linear differential non-autonomous equations on a Banach space, that satisfy exponential dichotomy, to be topologically equivalent. We shall also prove that such equations are structurally stable. 相似文献
67.
Higher order elements were first design for linear problems where, in certain situations, they present advantages over the lower order elements. A method to efficiently extend their use to geometrical nonlinear problems as panel flutter and postbuckling behavior is presented. The chaotic and limit-cycle oscillations of an isotropic plate are obtained based on direct integration of the discretized equation of motion. The plate is modeled using the von Karman theory and the geometrical nonlinearities are separated in a nonlinear term of the first kind which manifests especially in the prebuckling and buckling regimes, and a nonlinear term of the second kind which is responsible for the postbuckling behavior. A fifth order, fully compatible element has been used to model thin plates while the inplane loads where introduced through a membrane element. The aerodynamics was modeled using the first order 'piston theory. The method introduces the concept of a deteriorated form of the second geometric matrix which is equivalent to neglecting higher order terms in the strain energy of the plate. This allows for a drastic reduction in the computational effort with no observable loss of accuracy. Well established results in the literature are used to validate the method. 相似文献
68.
Dorin Popescu 《Journal of Algebra》2009,321(10):2782-2797
The Stanley's Conjecture on Cohen–Macaulay multigraded modules is studied especially in dimension 2. In codimension 2 similar results were obtained by Herzog, Soleyman-Jahan and Yassemi. As a consequence of our results Stanley's Conjecture holds in 5 variables. 相似文献
69.
We introduce the notion of n-nuanced MV-algebra by performing a Łukasiewicz–Moisil nuancing construction on top of MV-algebras. These structures extend both MV-algebras and Łukasiewicz–Moisil algebras, thus unifying two important types of structures in the algebra of logic. On a logical level, n-nuanced MV-algebras amalgamate two distinct approaches to many valuedness: that of the infinitely valued Łukasiewicz logic, more related in spirit to the fuzzy approach, and that of Moisil n-nuanced logic, which is more concerned with nuances of truth rather than truth degree. We study n-nuanced MV-algebras mainly from the algebraic and categorical points of view, and also consider some basic model-theoretic aspects. The relationship with a suitable notion of n-nuanced ordered group via an extension of the Γ construction is also analyzed. 相似文献
70.
Mihai Popescu 《Journal of Applied Mathematics and Computing》2009,31(1-2):385-394
The quadratic functional minimization with differential restrictions represented by the command linear systems is considered. The optimal solution determination implies the solving of a linear problem with two points boundary values. The proposed method implies the construction of a fundamental solution S(t)—a n×n matrix—and of a vector h(t) defining an adjoint variable λ(t) depending of the state variable x(t). From the extremum necessary conditions it is obtained the Riccati matrix differential equation having the S(t) as unknown fundamental solution is obtained. The paper analyzes the existence of the Riccati equation solution S(t) and establishes as the optimal solution of the proposed optimum problem. Also a superior limit of the minimum for the considered quadratic functionals class are evaluated. 相似文献