bluuebunny/crossref_metadata_2025_split huggingface dataset:
Coupled lattice‐Boltzmann and finite‐difference simulation of electroosmosis in microfluidic channels
Authors: Hlushkou Dzmitry , Kandhai Drona , Tallarek Ulrich 
Published: August 2004

AbstractIn this article we are concerned with an extension of the lattice‐Boltzmann method for the numerical simulation of three‐dimensional electroosmotic flow problems in porous media. Our description is evaluated using simple geometries as those encountered in open‐channel microfluidic devices. In particular, we consider electroosmosis in straight cylindrical capillaries with a (non)uniform zeta‐potential distribution for ratios of the capillary inner radius to the thickness of the electrical double layer from 10 to 100. The general case of heterogeneous zeta‐potential distributions at the surface of a capillary requires solution of the following coupled equations in three dimensions: Navier–Stokes equation for liquid flow, Poisson equation for electrical potential distribution, and the Nernst–Planck equation for distribution of ionic species. The hydrodynamic problem has been treated with high efficiency by code parallelization through the lattice‐Boltzmann method. For validation velocity fields were simulated in several microcapillary systems and good agreement with results predicted either theoretically or obtained by alternative numerical methods could be established. Results are also discussed with respect to the use of a slip boundary condition for the velocity field at the surface. Copyright © 2004 John Wiley & Sons, Ltd.
Accuracy analysis of super compact scheme in non‐uniform grid with application to parabolized stability equations
Authors: Esfahanian V. , Ghader S. , Ashrafi Kh. 
Published: August 2004

AbstractA brief derivation of the super compact finite difference method (SCFDM) in non‐uniform grid points is presented. To investigate the accuracy of the SCFDM in non‐uniform grid points the Fourier analysis is performed. The Fourier analysis shows that the grid aspect ratio plays a crucial role in the accuracy of the SCFDM in a non‐uniform grid. It is also found that the accuracy of the higher order relations of the SCFDM is more sensitive to grid aspect ratio than the lower order relations. In addition, to obtain a mathematical representation of the accuracy and making clear the role of the aspect ratio in the accuracy of the SCFDM in non‐uniform grids, the modified equation approach is used. For the sake of demonstrating the analytical results obtained from the Fourier analysis and the modified equation approach, the super compact finite difference method is applied to solve the Blasius boundary layer and the non‐linear parabolized stability equations as numerical examples indicating the difficulty with non‐uniform grid spacing using the super compact scheme. Copyright © 2004 John Wiley & Sons, Ltd.
From cells to tissues: Fluorescence confocal microscopy in the study of histological samples
Authors: Transidico Pietro , Bianchi Marco , Capra Maria , Pelicci Pier Giuseppe , Faretta Mario 
Published: August 2004

AbstractOur knowledge of the genetic mechanisms controlling cell proliferation and differentiation usually originates from in vitro cultured cell line models. However, the definition of the molecular switches involved in control of homeostasis and the understanding of the changes occurring in neoplastic transformation require looking at single cells as the components of a complex tissue network. Histological examination of tissue samples can gain a substantial amount of information from high‐resolution fluorescence analysis. In particular, confocal microscopy can help in the definition of functional pathways using multiparameter analysis. In this report, we present acquisition and analysis procedures to obtain high‐resolution data from tissue sections. Confocal microscopy coupled to computational restoration, statistical evaluation of spatial correlations, and morphological analysis over large tissue areas were applied to colorectal samples providing a molecular fingerprint of the biological differences inferred from classical histological examination. Microsc. Res. Tech. 64:89–95, 2004. © 2004 Wiley‐Liss, Inc.
Improvement in volume estimation from confocal sections after image deconvolution
Authors: Difato F. , Mazzone F. , Scaglione S. , Fato M. , Beltrame F. , Kubínová L. , Janáček J. , Ramoino P. , Vicidomini G. , Diaspro A. 
Published: August 2004

AbstractThe confocal microscope can image a specimen in its natural environment forming a 3D image of the whole structure by scanning it and collecting light through a small aperture (pinhole), allowing in vivo and in vitro observations. So far, the confocal fluorescence microscope (CFM) is considered a true volume imager because of the role of the pinhole that rejects information coming from out‐of‐focus planes. Unfortunately, intrinsic imaging properties of the optical scheme presently employed yield a corrupted image that can hamper quantitative analysis of successive image planes. By a post‐image collection restoration, it is possible to obtain an estimate, with respect to a given optimization criterium, of the true object, utilizing the impulse response of system or Point Spread Function (PSF). The PSF can be measured or predicted so as to have a mathematical and physical model of the image‐formation process. Further modelling and recording noise as an additive Gaussian process has used the regularized Iterative Constrained Tykhonov Miller (ICTM) restoration algorithm for solving the inverse problem. This algorithm finds the best estimate iteratively searching among the possible positive solutions; in the Fourier domain, such an approach is relatively fast and elegant. In order to compare the effective improvement in the quantitative image information analysis, we measured the volume of reference objects before and after image restoration, using the isotropic Fakir method. Microsc. Res. Tech. 64:151–155, 2004. © 2004 Wiley‐Liss, Inc.
Adaptive image‐processing technique and effective visualization of confocal microscopy images
Authors: Sun Yinlong , Rajwa Bartek , Robinson J. Paul 
Published: August 2004

AbstractA common observation about confocal microscopy images is that lower image stacks have lower voxel intensities and are usually blurred in comparison with the upper ones. The key reasons are light absorption and scattering by the objects and particles in the volume through which light passes. This report proposes a new technique to reduce such noise impacts in terms of an adaptive intensity compensation and structural sharpening algorithm. With these image‐processing procedures, effective 3D rendering techniques can be applied to faithfully visualize confocal microscopy data. Microsc. Res. Tech. 64:156–163, 2004. © 2004 Wiley‐Liss, Inc.
Backscattered light confocal imaging of intracellular MTT‐formazan crystals
Authors: Bernas Tytus , Dobrucki Jurek W. 
Published: August 2004

AbstractMetabolically active animal and plant cells reduce MTT tetrazolium salt to a corresponding nonfluorescent formazan. Reduction of MTT by viable cells is exploited in a number of tests widely used in biological research. The aim of this study was to optimize a microscopy method of detecting small crystals of MTT‐formazan formed in intact cells maintained in in vitro cultures. We examined scattering properties of small intracellular crystals of MTT formazan and found that the efficiency of light scattering was dependent on wavelength. Small (<3 μm) crystals of MTT‐formazan, formed in viable cells, scattered red, but not blue, light. Large crystals, which are formed later at a stage when cells begin to lose viability, scattered both red and blue light. We conclude that optimal detection of early stages of crystallization of MTT‐formazan in living cells is possible using confocal microscopy of red, but not blue, scattered light. High contrast and resolution of images can be achieved by filtering out interference effects in the frequency domain. Microsc. Res. Tech. 64:126–134, 2004. © 2004 Wiley‐Liss, Inc.
Saturation modified point spread functions in two‐photon microscopy
Authors: Cianci Gianguido C. , Wu Jianrong , Berland Keith M. 
Published: August 2004

AbstractExcitation saturation can dramatically alter the effective imaging point spread function (PSF) in two‐photon fluorescence microscopy. The saturation‐modified PSF can have important implications for resolution in fluorescence imaging as saturation leads to both an increased fluorescence observation volume and an altered spatial profile for the PSF. We introduce here a computational approach to accurately quantify molecular excitation profiles that represent the modified imaging PSF in two‐photon microscopy under the influence of excitation saturation. An analytical model that accounts for pulsed laser excitation is developed to calculate the influence of saturation at any location within the excitation laser profile. The overall saturation modified molecular excitation profiles are then evaluated numerically. Our results demonstrate that saturation can play an important role in two‐photon fluorescence microscopy even with relatively modest excitation levels. Microsc. Res. Tech. 64:135–141, 2004. © 2004 Wiley‐Liss, Inc.
Three‐dimensional microscopy migrates to the web with “PowerUp Your Microscope”
Authors: Bonetto Paola , Boccacci Patrizia , Scarito Marco , Davolio Mirko , Epifani Mattia , Vicidomini Giuseppe , Tacchetti Carlo , Ramoino Paola , Usai Cesare , Diaspro Alberto 
Published: August 2004

Abstract“PowerUp Your Microscope” is a software package designed and realized for the optimization of 3D optical microscopy image quality using the Internet and inverse problems computational approaches. The package is mainly devoted to 3D microscopy users, being operative for wide‐field, confocal, and multiphoton microscopy. It provides the microscopy community with an extremely easy and comparatively powerful access to advanced image restoration methods. The core of the computational section is the optical system modeling and inverse deconvolution implementation, which is strongly linked to Web‐based software and technology. This project constitutes a real and effective migration to the Web, extending computational approaches to image restoration to the whole microscopy user community, regardless of their background. Microsc. Res. Tech. 64:196–203, 2004. © 2004 Wiley‐Liss, Inc.
Liquid chromatography coupled to nuclear magnetic resonance spectroscopy for the identification of isoflavone glucoside malonates in T. pratense L. leaves.
Authors: de Rijke Eva , de Kanter Frans , Ariese Freek , Brinkman Udo A. Th. , Gooijer Cees 
Published: August 2004

AbstractPrevious studies revealed that the main isoflavones in extracts of leaves of T. pratense L. are biochanin A and formononetin, their 7‐O‐glucosides, and two glucoside malonate isomers of each of them. Since LC–MS(/MS) did not provide sufficient information to distinguish the glucoside malonate isomers, in the present paper LC–NMR as well as off‐line two‐dimensional NMR were used to obtain further structural information. Matrix solid‐phase dispersion (MSPD) was applied to obtain sufficiently high analyte concentrations to perform LC–NMR. Stop‐flow reversed‐phase LC–NMR was performed using a gradient of deuterated water and deuterated acetonitrile. Off‐line COSY and NOESY experiments were carried out to determine the positions of the glucose moiety on the flavonoid aglycone, and of the malonate moiety on the glucose. Based on the fragmentation patterns in MS/MS and the NMR spectra, the two formononetin glucoside malonate isomers were identified as 7‐O‐β‐D‐glucoside 6´´‐O‐malonate and 7‐O‐β‐D‐glucoside 4´´‐O‐malonate; i.e. they only differ in the substitution position of the malonate group on the glucoside ring. The biochanin A glucoside malonate isomers, however, have quite different structures. The main and later eluting isomer is biochanin A 7‐O‐β‐D‐glucoside 6´´‐O‐malonate, and the minor and earlier eluting isomer is 5‐hydroxy‐7‐methoxyisoflavone 4´‐O‐β‐D‐glucoside 4´´‐O‐malonate: the positions of the methoxy group and the glucoside 6´´‐O‐malonate group on the flavonoid skeleton are interchanged.
Degrees of d. c. e. reals
Authors: Downey Rod , Wu Guohua , Zheng Xizhong 
Published: August 2004

AbstractA real α is called a c. e. real if it is the halting probability of a prefix free Turing machine. Equivalently, α is c. e. if it is left computable in the sense that L(α) = {q ∈ ℚ : q ≤ α} is a computably enumerable set. The natural field formed by the c. e. reals turns out to be the field formed by the collection of the d. c. e. reals, which are of the form α—β, where α and β are c. e. reals. While c. e. reals can only be found in the c. e. degrees, Zheng has proven that there are Δ02 degrees that are not even n‐c. e. for any n and yet contain d. c. e. reals, where a degree is n‐c. e. if it contains an n‐c. e. set. In this paper we will prove that every ω‐c. e. degree contains a d. c. e. real, but there are ω + 1‐c. e. degrees and, hence Δ02 degrees, containing no d. c. e. real. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Weak computability and representation of reals
Authors: Zheng Xizhong , Rettinger Robert 
Published: August 2004

AbstractThe computability of reals was introduced by Alan Turing [20] by means of decimal representations. But the equivalent notion can also be introduced accordingly if the binary expansion, Dedekind cut or Cauchy sequence representations are considered instead. In other words, the computability of reals is independent of their representations. However, as it is shown by Specker [19] and Ko [9], the primitive recursiveness and polynomial time computability of the reals do depend on the representation. In this paper, we explore how the weak computability of reals depends on the representation. To this end, we introduce three notions of weak computability in a way similar to the Ershov's hierarchy of Δ02‐sets of natural numbers based on the binary expansion, Dedekind cut and Cauchy sequence, respectively. This leads to a series of classes of reals with different levels of computability. We investigate systematically questions as on which level these notions are equivalent. We also compare them with other known classes of reals like c. e. and d‐c. e. reals. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spaces allowing Type‐2 Complexity Theory revisited
Authors: Schröder Matthias 
Published: August 2004

AbstractThe basic concept of Type‐2 Theory of Effectivity (TTE) to define computability on topological spaces (X, τ) or limit spaces (X,→) are representations, i. e. surjection functions from the Baire space ontoX. Representations having the topological property of admissibility are known to provide a reasonable computability theory. In this article, we investigate several additional properties of representations which guarantee that such representations induce a reasonable Type‐2 Complexity Theory on the represented spaces. For each of these properties, we give a nice characterization of the class of spaces that are equipped with a representation having the respective property. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some recent developments on Shannon's General Purpose Analog Computer
Authors: Silva Graça Daniel 
Published: August 2004

AbstractThis paper revisits one of the first models of analog computation, the General Purpose Analog Computer (GPAC). In particular, we restrict our attention to the improved model presented in [11] and we show that it can be further refined. With this we prove the following: (i) the previous model can be simplified; (ii) it admits extensions having close connections with the class of smooth continuous time dynamical systems. As a consequence, we conclude that some of these extensions achieve Turing universality. Finally, it is shown that if we introduce a new notion of computability for the GPAC, based on ideas from computable analysis, then one can compute transcendentally transcendental functions such as the Gamma function or Riemann's Zeta function. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Some subrecursive versions of Grzegorczyk's Uniformity Theorem
Authors: Skordev Dimiter 
Published: August 2004

AbstractA theorem published by A. Grzegorczyk in 1955 states a certain kind of effective uniform continuity of computable functionals whose values are natural numbers and whose arguments range over the total functions in the set of the natural numbers and over the natural numbers. Namely, for any such functional a computable functional with one function‐argument and the same number‐arguments exists such that the values of the first of the functionals at functions dominated by a given one are completely determined by their restrictions to numbers not exceeding the corresponding values of the second functional at the given function. We prove versions of this theorem for the class of the primitive recursive functionals and for the class of the elementary recursive ones. Analogous results can be proved for many other subrecursive classes of functionals. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fold zone analysis in wiping die bending process by using experimental and numerical approaches
Authors: Mkaddem Ali , Potiron Alain 
Published: August 2004

AbstractThis paper deals with an analysis of the fold zone of bent parts within the sheet thickness by means of micro hardness measurement and numerical modelling. The failure risk has to be accurately predicted by using a continuum damage mechanics in order to avoid some expensive experiments. In this reason, a 3D numerical model, based on Lemaitre damage formulations, has been developed. The scalar damage variable D as well as the hardening law are taken to be isotropic within the sheet. The numerical approach is based on an incremental integration scheme of the constitutive equations coupled with ductile damage and von Mises criteria. The corresponding numerical algorithm is implemented into ABAQUS/Standard code. During bending operation, the damage variable evolution is computed and the hydrostatic stress effect is investigated within the sheet thickness. The hardening and plastic strain evolutions have been compared with the micro hardness one deduced from experimental tests. The comparison between experimental and numerical results illustrates the capability of the model in 3D process simulation, particularly in bending processes. Copyright © 2004 John Wiley & Sons, Ltd.
Application of piece‐wise linear weight functions for 2D 8‐node quadrilateral element in contact problems
Authors: Luo Chouping , Klisinski Marek 
Published: August 2004

AbstractThe present study is a continuation of our previous work with the aim to reduce problems caused by standard higher order elements in contact problems. The difficulties can be attributed to the inherent property of the Galerkin method which gives uneven distributions of nodal forces resulting in oscillating contact pressures. The proposed remedy is use of piece‐wise linear weight functions. The methods to establish stiffness and/or mass matrix for 8‐node quadrilateral element in 2D are presented, i.e. the condensing and direct procedures. The energy and nodal displacement error norms are also checked to establish the convergence ratio. Interpretation of calculated contact pressures is discussed. Two new 2D 8‐node quadrilateral elements, QUAD8C and QUAD8D, are derived and tested in many examples, which show their good performance in contact problems. Copyright © 2004 John Wiley & Sons, Ltd.
Cancer incidence among children in France, 1990–1999
Authors: Desandes Emmanuel , Clavel Jacqueline , Berger Claire , Bernard Jean‐Louis , Blouin Pascale , de Lumley Lionel , Demeocq François , Freycon Fernand , Gembara Piotr , Goubin Aurélie , Le Gall Edouard , Pillon Pascale , Sommelet Danièle , Tron Isabelle , Lacour Brigitte 
Published: August 2004

AbstractBackgroundCancer is the second most important cause of death for children aged less than 15 years in France, unintentional injuries being the leading cause. The aim of the present study was to estimate the incidence of childhood cancer from six Childhood Cancer Registries covering 32% of France.ProcedureIncident cancer cases diagnosed between 1990 and 1999 in children (0–14 years) resident in the administrative areas covered by each Registry were included. Annual age‐standardized rates (ASRs) were adjusted by the world population. The estimated annual percent change (EAPC) was used to measure trend towards changes in the annual age‐standardized incidence rate.ResultsWith 4234 registered cases, the ASRs per million children were 137.5 for all cancers combined, 42.3 for leukemia, 29.1 for central‐nervous‐system tumors, 15.6 for lymphomas, 14.1 for sympathetic‐nervous‐system tumors, and 9.1 for renal tumors. The ASR of all cancers combined was slightly higher in males (145.8 per million children) than in females (128.7 per million children) with an M/F ratio of 1.2. No significant incidence trend was observed, with an EAPC of +0.2% [IC 95% (−2.5; +3.0); P = 0.89].ConclusionsThe estimated incidence rates are similar to those reported in previous studies in European and North American countries. These results will contribute to the development of National Registration of Childhood Cancer in France and support the national research program on childhood cancer. © 2004 Wiley‐Liss, Inc.
Interferon‐γ sensitizes osteosarcoma cells to fas‐induced apoptosis by up‐regulating fas receptors and caspase‐8
Authors: Inaba Hiroto , Glibetic Maria , Buck Steven , Ravindranath Yaddanapudi , Kaplan Joseph 
Published: August 2004

AbstractBackgroundOsteosarcoma is the third most frequent neoplasm in adolescents. Although chemotherapy, frequently used in pre‐ and post‐operative settings, has resulted in significant improvement in disease‐free survival, some patients show little sensitivity to chemotherapy and alternative therapeutic strategies are needed. Because the Fas ligand/Fas receptor (CD95, APO‐1) apoptosis pathway is a potential therapeutic target in osteosarcomas, we examined the effect of IFN‐γ on Fas‐induced apoptosis in four osteosarcoma cell lines.Procedure and ResultsAs measured by flow cytometry, all cell lines expressed cell surface IFN‐γ receptors, and when cultured for 2 days in the presence of IFN‐γ, all cell lines exhibited a significant increase in expression of Fas receptors. By flow cytometric detection of intracellular fragmented DNA as a marker of apoptosis, all cell lines cultured with either IFN‐γ or anti‐Fas antibody (clone CH‐11) alone showed only moderate apoptosis, whereas significantly high levels of apoptosis occurred in cells cultured with both IFN‐γ and CH‐11. Western blotting analysis also revealed that IFN‐γ caused up‐regulation of caspase‐8 in all cell lines, but no change in Fas‐associated death domain protein (FADD/MORT1) or caspase‐3. Both caspase‐8 and caspase‐3 were activated when apoptosis was induced with both IFN‐γ and CH‐11. Addition to cultures of z‐IETD‐fmk, an inhibitor of caspase‐8, significantly blocked this apoptosis.ConclusionsIFN‐γ sensitizes osteosarcoma cells to Fas‐induced apoptosis through up‐regulation of Fas receptor and caspase‐8. Combined immunotherapy with IFN‐γ and either anti‐Fas monoclonal antibody or cytotoxic T cells that bear Fas ligand might be a useful adjunctive therapy for patients with osteosarcoma. © 2004 Wiley‐Liss, Inc.