Search results for "Matrix"

Asymptotical Convergence Evaluation for a Parabolic Problem Arising in Circuit Theory

1990

A New Culture Technique: An Approach to the in-Vitro Reconstitution of Endocrine Organs

1983

A new cell culture technique called three-dimensional-rotation culture (3dR-culture) has been developed. Its main characteristics are: (i) cultivation under constant rotation, and (ii) the use of a three-dimensional material that allows the cells to adhere and to grow in a three-dimensional arrangement. Two glassfibre materials and one gelatine-sponge proved suitable for the use in cell culture. The new technique has the advantage to yield in large numbers cells bound on a stable matrix that can easily be handled, e.g. for implantation.

Shape Description for Content-Based Image Retrieval

2000

The present work is focused on a global image characterization based on a description of the 2D displacements of the different shapes present in the image, which can be employed for CBIR applications.To this aim, a recognition system has been developed, that detects automatically image ROIs containing single objects, and classifies them as belonging to a particular class of shapes.In our approach we make use of the eigenvalues of the covariance matrix computed from the pixel rows of a single ROI. These quantities are arranged in a vector form, and are classified using Support Vector Machines (SVMs). The selected feature allows us to recognize shapes in a robust fashion, despite rotations or…

A Statistical Matrix Representation Using Sliced Orthogonal Nonlinear Correlations for Pattern Recognition

2000

In pattern recognition, the choice of features to be detected is a critical factor to determine the success or failure of a method; much research has gone into finding the best features for particular tasks [1]. When images are detected by digital cameras, they are usually acquired as rectangular arrays of pixels, so the initial features are pixel values. Some methods use those pixel values directly for processing, for instance in normal matched filtering [2], whereas other methods execute some degree of pre-processing, such as binarizing the pixel values [3].

Accuracy of stereotactic coordinate transformation using a localisation frame and computed tomographic imaging

1999

The accuracy of coordinate transformation from the computed tomographic (CT) space to the stereotactic frame space was analysed for frame-based stereotactic systems which use a localisation frame and coordinate transformation based on matrix calculation. The coordinate transformation was divided into three consecutive steps: (1) transforming the localisation frame into the CT image built up from pixels with distinct attenuation values, (2) determining the rod centres of the localisation frame in the CT image, and (3) coordinate transformation from the image to the frame space using the centres of the rods in the image space and algebraic, matrix-based calculation. The error contribution at …

Characterization of the metastatic properties of two methylcholantrene-induced fibrosarcoma in mice

1988

MC1 and MC2 murine fibrosarcomas, following intramuscular innplantation in mice, release different numbers of tumor cells into the bloodstream and differ in their lung colonization potential following intravenous inoculation. Since these biological properties could be related to a different degree of maligancy, in vivo and in vitro experiments were performed vvith these two tunnors in an attempt to correlate their spontaneous metas-tatic potential with other parameters related to tunnor cell invasion and metastasis. Following intramuscular inplantation the MC2 fibrosarcoma was observed to have a slow but progressive ability to spontaneously metastasize while the MC1 lacked this capability. …

Total Variation Based Image Restoration

2004

For the purpose of image restoration the process of image formation can be modeled in a first approximation by the formula [207] $$ {u_d} = Q\{ II(k*u) + n\} , $$ (1.1) where u represents the photonic flux k is the point spread function of the optical-captor joint apparatus П is a sampling operator, i.e., a Dirac comb supported by the centers of the matrix of digital sensors, n represents a random perturbation due to photonic or electronic noise, and Qis a uniform quantization operator mapping ℝ to a discrete interval of values, typically [0, 255].

Tridiagonal preconditioning for Poisson-like difference equations with flat grids: Application to incompressible atmospheric flow

2011

AbstractThe convergence of many iterative procedures, in particular that of the conjugate gradient method, strongly depends on the condition number of the linear system to be solved. In cases with a large condition number, therefore, preconditioning is often used to transform the system into an equivalent one, with a smaller condition number and therefore faster convergence. For Poisson-like difference equations with flat grids, the vertical part of the difference operator is dominant and tridiagonal and can be used for preconditioning. Such a procedure has been applied to incompressible atmospheric flows to preserve incompressibility, where a system of Poisson-like difference equations is …

Dynamic electric field assisted multi-dimensional liquid chromatography of biological samples

2005

Complex biological samples require very high resolution separation strategies. The platform introduced here capitalises on the hyphenation of liquid chromatographic (LC) and electric potential gradient electrochromatographic multi-dimensional separation genres. First-dimension selectivity is provided by simultaneous size exclusion (SEC) and strong cation exchange (SCX) chromatography modes, while the second dimension comprises reversed phase (RP) characteristics in a dynamic (time-variant) electric field. The time-variant potential gradient with reversal of polarity is applied across the second dimension monolithic capillary throughout the duration of the solvent strength gradient elution. …

Bloch surface waves engineering in one-dimensional photonic crystals with a chiral cap layer

2019

We investigate the localization properties of surface waves created at the interface between a truncated 1D photonic crystal and homogeneous medium in the presence of a chiral cap layer using the transfer matrix method. The numerical results show that the interface can support surface waves with both transverse electric and transverse magnetic polarizations. We demonstrate that the surface waves can be engineered by varying the chirality parameter of the cap layer, which plays an important role in controlling and localization of surface states. It is shown that the effect of a chirality parameter on surface waves with transverse electric polarization is more remarkable compared with surface…