bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing control of grid distribution in algebraic grid generation
Authors: Steinthorsson E. , Shih T. I.‐P. , Roelke R. J.
Published: November 2005

Three techniques are presented to enhance the control of grid‐point distribution for a class of algebraic grid generation methods known as the two‐, four‐ and six‐boundary methods. First, multidimensional stretching functions are presented, and a technique is devised to construct them based on the desired distribution of grid points along certain boundaries. Second, a normalization procedure is proposed which allows more effective control over orthogonality of grid lines at boundaries and curvature of grid lines near boundaries. And third, interpolating functions based on tension splines are introduced to control curvature of grid lines in the interior of the spatial domain. In addition to these three techniques, consistency conditions are derived which must be satisfied by all user‐specified data employed in the grid generation process to control grid‐point distribution. The usefulness of the techniques developed in this study was demonstrated by using them in conjunction with the two‐ and four‐boundary methods to generate several grid systems, including a three‐dimensional grid system in the coolant passage of a radial turbine blade with serpentine channels and pin fins.
Flow characteristics in the downstream region of a conical diffuser
Authors: Prinos P. , Goulas A.
Published: November 2005

Using the Navier‐Stokes equations in conjunction with the k‐ϵ model of turbulence, the characteristics of flow in the region downstream of a conical diffuser with 5° angle of inclination are calculated. Two representative stations 1D2 and 10D2 after the diffuser exit are selected for comparison against experimental results. The calculations indicate an underestimation of mean velocity and turbulence kinetic energy at the first station, while satisfactory agreement is obtained for the mean velocity at the second station. The use of a modified k‐ϵ model sensitive to adverse pressure conditions improves the predictions considerably. The effect of inlet properties and Reynolds number on the flow characteristics at the above stations is studied using various inlet profiles and a range of Reynolds numbers based on the inlet diameter from 50 000 to 280 000.
Complex turbulent compressible flow computation using a two‐layer approach
Authors: Mohammadi Bijan
Published: November 2005

A two‐layer approach is proposed to compute complex flows including separations. For high‐ and low‐Reynolds‐number regions we use a two‐equation k‐ϵ model and a one‐equation k‐L model respectively. A robust algorithm is proposed for the treatment of the convective part of the turbulence equations. Several complex configurations including separations are computed.
Influence of trailing‐edge grid structure on Navier‐Stokes computation of turbomachinery cascade flow
Authors: Chung Hee‐Taeg , Baek Je‐Hyun
Published: November 2005

Three kinds of grid system based on C‐type grid are examined in order to reveal their relative flow characteristics of the turbomachinery cascade, especially near the trailing edge and wake. Here, a semi‐conservative interpolation technique to treat the discontinuous boundary condition along the periodic boundary is proposed and is applied on the patched‐type grid structure. Computational results are presented to see the influence of trailing‐edge grid structure on the Navier‐Stokes solutions for the high‐turning transonic turbine cascade.
Analysis of fluid flow in constricted tubes and ducts using body‐fitted non‐staggered grids
Authors: Melaaen M. C.
Published: November 2005

A finite volume method for the calculation of laminar and turbulent fluid flows inside constricted tubes and ducts is described. The selected finite volume method is based on curvilinear non‐orthogonal co‐ordinates (body‐fitted co‐ordinates) and a non‐staggered grid arrangement. The grids are either generated by transfinite interpolation or an elliptic grid generator. The method is employed for calculation of laminar flows through a tube, a converging‐diverging duct and different constricted tubes by both a two‐ and a three‐dimensional computer program. In addition, turbulent flow through an axisymmetric constricted tube is calculated. Both the power law scheme and the second‐order upwind scheme are used. The calculated results are compared with the experimental data and with other numerical solutions.
Automatic mesh generation method for shallow water flow analysis
Authors: Kashiyama Kazuo , Okada Tsuyoshi
Published: November 2005

This paper presents a new automatic mesh generation method for the finite element analysis of shallow water flow. The key feature of this method is that the finite element mesh can be generated so that the element Courant number is nearly constant in the whole domain. It follows that the numerical stability and accuracy improve automatically. Moreover, the finite element mesh data, including the data of water depth, can be prepared automatically. The three‐node triangular element is used for the finite element. In order to show the efficiency of the method presented, the mesh obtained by this method is applied to some shallow water flow analyses. This method is shown to be a useful and powerful tool for the preparation of optimal finite element mesh data for shallow water flow analysis.
Boundary integral/spectral element approaches to the Navier‐Stokes equations
Authors: Occhialini J. M. , Muldowney G. P. , Higdon J. J. L.
Published: November 2005

Numerical algorithms are presented which combine spectral expansions on elemental subdomains with boundary integral formulations for solving viscous flow problems. Three distinct algorithms are described. The first demonstrates the use of spectral elements for the classic boundary integral method for steady Stokes flow. The second extends this algorithm to include domain integrals for solution of the unsteady Navier‐Stokes equations. The third algorithm explores the use of boundary integrals as a means of consolidating uncoupled elemental solutions in a domain decomposition approach. Numerical results demonstrating high‐order convergence are presented in each case.
Numerical solutions of a non‐linear density current: A benchmark solution and comparisons
Authors: Straka J. M. , Wilhelmson Robert B. , Wicker Louis J. , Anderson John R. , Droegemeier Kelvin K.
Published: November 2005

A comparison between solutions from simulations of a non‐linear density current test problem was made in order to study the behaviour of a variety of numerical methods. The test problem was diffusion‐limited so that a grid‐converged reference solution could be generated using high spatial resolution. Solutions of the test problem using several different resolutions were computed by the participants of the ‘Workshop on Numerical Methods for Solving Nonlinear Flow Problems’, which was held on 11–13 September 1990 at the National Center for Supercomputing Applications (NCSA). In general, it was found that when the flow was adequately resolved, all of the numerical schemes produced solutions that contained the basic physics as well as most of the flow detail of the reference solution. However, when the flow was marginally resolved, there were significant differences between the solutions produced by the various models. Finally, when the flow was poorly resolved, none of the models performed very well. While higher‐order and spectral‐type schemes performed best for adequately and marginally resolved flow, solutions made with these schemes were virtually unusable for poorly resolved flow. In contrast, the monotonic schemes provided the most coherent and smooth solutions for poorly resolved flow, however with noticeable amplitude and phase speed errors, even at finer resolutions.
A kinetic theory solution method for the Navier–Stokes equations
Authors: Macrossan M. N. , Oliver R. I.
Published: November 2005

The kinetic‐theory‐based solution methods for the Euler equations proposed by Pullin and Reitz are here extended to provide new finite volume numerical methods for the solution of the unsteady Navier–Stokes equations. Two approaches have been taken. In the first, the equilibrium interface method (EIM), the forward‐ and backward‐flowing molecular fluxes between two cells are assumed to come into kinetic equilibrium at the interface between the cells. Once the resulting equilibrium states at all cell interfaces are known, the evaluation of the Navier–Stokes fluxes is straightforward. In the second method, standard kinetic theory is used to evaluate the artificial dissipation terms which appear in Pullin's Euler solver. These terms are subtracted from the fluxes and the Navier–Stokes dissipative fluxes are added in. The new methods have been tested in a 1D steady flow to yield a solution for the interior structure of a shock wave and in a 2D unsteady boundary layer flow. The 1D solutions are shown to be remarkably accurate for cell sizes large compared to the length scale of the gradients in the flow and to converge to the exact solutions as the cell size is decreased. The steady‐state solutions obtained with EIM agree with those of other methods, yet require a considerably reduced computational effort.
Three‐dimensional mesh embedding for the Navier–Stokes equations using upwind control volumes
Authors: Lapworth B. L.
Published: November 2005

A numerical model for the compressible Navier–Stokes equations using local mesh embedding is presented. The model solves for three‐dimensional turbulent flow using an algebraic mixing length model of turbulence. The technique of control volume upwinding is used to produce a novel treatment, whereby the hanging nodes on the mesh interfaces are left with null control volumes. This yields an efficient discretization scheme which ensures second‐order accuracy, flux conservation and stability at the mesh interfaces, whilst retaining a simple interpolative treatment for the hanging nodes. The discrete flow equations are solved using the semi‐implicit pressure correction method. The accuracy of the embedded mesh solver is demonstrated by modelling the three‐dimensional flow through a cascade of turbine vanes at design and off‐design conditions. Mesh embedding gives a saving of 48% in the number of nodes. The embedded mesh solutions compare well with fine structured mesh solutions and experimental measurements. The capability of the embedded mesh solver to perform solution adaptive calculations is demonstrated using a two‐dimensional mid‐height section of the cascade at the off‐design flow conditions.
A parabolic numerical procedure for three‐dimensional viscous rotating flows
Authors: Shi Qingping , Ribando R. J.
Published: November 2005

This paper presents the development of a parabolic numerical procedure for rotating flows and its applications to three‐dimensional viscous rotating flows. The formulation is based on the Navier–Stokes equations in general co‐ordinates fixed on a rotating frame, so that the rotation effect is included in the guess‐correct process. The use of body‐fitted curvilinear co‐ordinates makes it easier to handle the complex geometries of turbomachinery components. In the present work a k–ϵ turbulence model was used for the three‐dimensional numerical tests. The algorithm is equally applicable to incompressible and compressible flows. Comparisons of the predicted results with the experimental data were reasonably good, and the solutions were stable to rotational speeds up to at least 14 000 rpm.
Finite element analysis of lift build‐up due to aerofoil indicial motion
Authors: Shi Jun , Hitchings Dennis
Published: November 2005

In this paper the problem of impulsively started aerofoil or suden change of incidence of an aerofoil in incompressible potential flow is investigated. The essence of solution lies in the representation of a timely and spatially varying wake in a largely irrotational potential flow field. This is achieved by representing the wake through velocity potential difference, which seems to be the only way of imposing a velocity difference condition in the finite element context with velocity potentials as the basic unknowns. Superposition is employed to meet various boundary conditions, which is justified by the linearity of the problem. The finite element solutions are compared with those from singularity method.
On finite element approximation and stabilization methods for compressible viscous flows
Authors: Fortin M. , Manouzi H. , Soulaimani A.
Published: November 2005

This work is devoted to the numerical solution of the Navier–Stokes equations for compressible viscous fluids. Finite element approximations and stabilization techniques are addressed. We present methods to implement discontinuous approximations for the pressure and the density. An upwinding methodology is being investigated which combines the ideas behind the stream line Petrov–Galerkin method and the flux limiter methods aiming to introduce numerical diffusion only where it is necessary.
A comparison of numerical methods applied to non‐linear adsorption columns
Authors: Poulain Christophe A. , Finlayson Bruce A.
Published: November 2005

Eight numerical schemes (first‐order upstream finite difference, MacCormack, explicit Taylor–Galerkin, random choice, flux‐corrected transport, ENO, TVD, and Euler–Lagrange methods) are compared on the basis of their computational efficiency for one‐dimensional non‐linear convection–diffusion problems. For the ideal chromatographic equation for which an exact solution exists, errors plotted against computational times show that the best methods are the random choice, Euler–Lagrange and flux‐corrected MacCormack methods. Even when significant diffusion is added to the model, steep gradients are possible because of non‐linearities. In such an instance, the random choice and flux‐corrected transport methods give the best performance. One can now tackle more complicated problems and refer to this comparative study in order to choose an adequate numerical method which will provide sufficiently accurate results at a reasonable cost.
Steady flows of non‐Newtonian fluids past a porous plate with suction or injection
Authors: Mansutti D. , Pontrelli G. , Rajagopal K. R.
Published: November 2005

The problem of the steady flow of three classes of non‐linear fluids of the differential type past a porous plate with uniform suction or injection is studied. The flow which is studied is the counterpart of the classical ‘asymptotic suction’ problem, within the context of the non‐Newtonian fluid models. The non‐linear differential equations resulting from the balance of momentum and mass, coupled with suitable boundary conditions, are solved numerically either by a finite difference method or by a collocation method with a B‐spline function basis. The manner in which the various material parameters affect the structure of the boundary layer is delineated. The issue of paucity of boundary conditions for general non‐linear fluids of the differential type, and a method for augmenting the boundary conditions for a certain class of flow problems, is illustrated. A comparison is made of the numerical solutions with the solutions from a regular perturbation approach, as well as a singular perturbation.
An explicit transient algorithm for predicting incompressible viscous flows in Arbitrary Geometry
Authors: Mukhopadhyay A. , Sundararajan T. , Biswas G.
Published: November 2005

A numerical method for predicting viscous flows in complex geometries has been presented. Integral mass and momentum conservation equations are deploved and these are discretized into algebraic form through numerical quadrature. The physical domain is divided into a number of non‐orthogonal control volumes which are isoparametrically mapped on to standard rectangular cells. Numerical integration for unsteady mementum equations is performed over such non‐orthogonal cells. The explicitly advanced velocity components obtained from unsteady momentum equations may not necessarily satisfy the mass conservation condition in each cell. Compliance of the mass conservation equation and the consequent evolution of correct pressure distribution are accomplished through an iterative correction of pressure and velocity till divergence‐free condition is obtained in each cell. The algorithm is applied on a few test problems, namely, lid‐driven square and oblique cavities, developing flow in a rectangular channel and flow over square and circular cylinders placed in rectangular channels. The results exhibit good accuracy and justify the applicability of the algorithm.

This Explicit Transient Algorithm for Flows in Arbitrary Geometry is given a generic name EXTRAFLAG.
Optimal design of spiral casing tongue and wicket gate angle by decomposition method
Authors: Mrša Z.
Published: November 2005

A method of optimal design of Francis turbine tongue and wicket gate angle for given spiral casing is proposed. The potential flow in the doubly connected domain is decomposed into basic and circulation flows. The intensity of circulation is then calculated by the least‐squares method minimizing the error function equal to the sum of squares of differences between given and calculated circumferential velocities in the outflow boundary nodes. It is shown that the error function has a sharp minimum, which qualifies the proposed method as well defined. For given numerical example, the variations in the outflow velocity angles are much smaller for optimal than for already used non‐optimal design. A finite element method is used, with originally developed pre‐ and post‐processor and frontal solver suited for personal computers.
Simulation of vortex shedding including blockage by the random‐vortex and other methods
Authors: Stansby P. K. , Slaouti A.
Published: November 2005

Converged simulations of vortex shedding from a circular cylinder at a Reynolds number of 100 have been computed by the random‐vortex method incorporating the influence of blockage. The results are compared with converged finite‐element and spectral methods and close agreement for Strouhal number is obtained. Forces are, however, in less close agreement, particularly the fluctuating lift force. Strouhal numbers from simulations with zero blockage for Reynolds numbers between 60 and 180 are seen to be in very close agreement with experiments which are said to be effectively two‐dimensional. In this range the Strouhal number changes from 0·135 to 0·191. There are no corresponding experimental measurements for force.
Computation of free surface waves around an arbitrary body by a Navier‐Stokes solver using the psuedocompressibility technique
Authors: Liu H. , Ikehata M.
Published: November 2005

A Navier‐Stokes equation solver is developed for computing free surface wave and viscous flow around an arbitrary body, in which a free surface model is introduced into the pseudocompressibility solution. The governing equations are classified in a vectorial form, with primitive variables, and a block diagonal system is generated by the discretization of an implicit factorization method. A moving grid system fitted to both the free surface and body surface is generated by an effective cubic spline fitting technique. Two zero‐equation turbulence models, namely the Cebeci‐Smith model and the Baldwin‐Lomax model, are used for turbulent calculations. Numerical simulations are carried out for the free surface viscous flows generated by a submerged hydrofoil and a ship model. Computed results are in reasonable agreement with measurements.
Numerical simulation method for viscoelastic flows with free surfaces—fringe element generation method
Authors: Sato Toru , Richardson Stephen M.
Published: November 2005

To simulate filling flow in injection moulding for viscoelastic fluids, a numerical method, based on a finite element method and a finite volume method, has been developed for incompressible isothermal viscoelastic flow with moving free surfaces. The advantages of this method are, first, good applicability to arbitrarily shaped mould geometries and, second, accurate treatment for boundary conditions on the free surface. Typical filling flows are simulated, namely filling flow into a 1:4 expansion cavity with and without an obstacle. Numerical results predict the position of weld lines and air‐traps. The method also indicates the effects of elongational flow on molecular orientation.
A characteristic‐based method for incompressible flows
Authors: Drikakis D. , Govatsos P. A. , Papantonis D. E.
Published: November 2005

A new characteristic‐based method for the solution of the 2D laminar incompressible Navier‐Stokes equations is presented. For coupling the continuity and momentum equations, the artificial compressibility formulation is employed. The primitives variables (pressure and velocity components) are defined as functions of their values on the characteristics. The primitives variables on the characteristics are calculated by an upwind diffencing scheme based on the sign of the local eigenvalue of the Jacobian matrix of the convective fluxes. The upwind scheme uses interpolation formulae of third‐order accuracy. The time discretization is obtained by the explicit Runge–Kutta method. Validation of the characteristic‐based method is performed on two different cases: the flow in a simple cascade and the flow over a backwardfacing step.
Numerical investigation of dynamic stall of an oscillating aerofoil
Authors: Guo W. H. , Fu D. X. , Ma Y. W.
Published: November 2005

The flow structure around an NACA 0012 aerofoil oscillating in pitch around the quarter‐chord is numerically investigated by solving the two‐dimensional compressible N–S equations using a special matrix‐splitting scheme. This scheme is of second‐order accuracy in time and space and is computationally more efficient than the conventional flux‐splitting scheme. A ‘rigid’ C‐grid with 149 × 51 points is used for the computation of unsteady flow. The freestream Mach number varies from 0.2 to 06 and the Reynolds number from 5000 to 20,000. The reduced frequency equals 0.25–0.5. The basic flow structure of dynamic stall is described and the Reynolds number effect on dynamic stall is briefly discussed. The influence of the compressibility on dynamic stall is analysed in detail. Numerical results show that there is a significant influence of the compressibility on the formation and convection of the dynamic stall vortex. There is a certain influence of the Reynolds number on the flow structure. The average convection velocity of the dynamic stall vortex is approximately 0.348 times the freestream velocity.
A semi‐collocated ocean model based on the SOMS approach
Authors: Dietrich David E. , Ko Dong‐Shan
Published: November 2005

In application to the Gulf of Mexico (GOM), a new DieCAST ocean model, which uses a modified Arakawa ‘a’ grid, and the SOMS model, which uses an Arakawa ‘c’ grid, give remarkably similar results. The new model avoids ‘null space’ problems of the standard ‘a’ grid approach by first using fourth‐order interpolations to a ‘c’ grid advection velocity, then applying incompressibility to the result. Accuracy is further improved by using fourth‐order pressure gradient approximations at ‘a’ grid locations. Incompressibility with general geometry is satisfied efficiently by a fast‐converging iteration with a regular gteometry elliptic solver. Results are compared with satellite‐measured r.m.s. sea surface elevation anomaly and detailed front structures, climatological mean thermocline and empirical orthogonal functions and other observations.
Parallel fluid dynamics computations in aerospace applications
Authors: Aliabadi S. K. , Tezduyar T. E.
Published: November 2005

Massively parallel finite element computations of the compressible Euler and Navier‐Stokes equations using parallel supercomputers are presented. The finite element formulations are based on the conservation variables and the streamline‐upwind/Petrov‐Galerkin (SUPG) stabilization method is used to prevent potential numerial oscillations due to dominant advection terms. These computations are based on both implicit and explicit methods and their parallel implementation assumes that the mesh is unstructured. The implicit computations are based on iterative strategies. Large‐scale 3D problems are solved using a matrix‐free iteration technique which reduces the memory requirements significantly. The flow problems we consider typically come from aerospace applications, including those in 3D and those involving moving boundaries interacting with boundary layers and shocks. Problems with fixed boundaries are solved using a semidiscrete formulation and the ones involving moving boundaries are solved using the deformable‐spatial‐domain/stabilized‐space‐time (DSD/SST) formulation.
A case study in parallel computation: Viscous flow around an ONERA M6 wing
Authors: Johan Zdeněk , Mathur Kapil K. , Johnsson S. Lennart , Hughes Thomas J. R.
Published: November 2005

We examine the solution of a practical engineering problem on a parallel computer. The problem involves the steady laminar viscous flow about an ONERA M6 wing and the computer is a 64‐processing‐node Connection Machine CM‐5E. We show that efficient domain decomposition procedures lead to a balanced load on the processors and low communication times. The net result is that solutions can be attained in roughly 20 min elapsed time for a 48,011‐node, 266,566‐element unstructured mesh. We conclude that this is sufficiently fast to support the design process.
Phenotypic and functional heterogeneity of GFAP‐expressing cells in vitro: Differential expression of LeX/CD15 by GFAP‐expressing multipotent neural stem cells and non‐neurogenic astrocytes
Authors: Imura Tetsuya , Nakano Ichiro , Kornblum Harley I. , Sofroniew Michael V.
Published: November 2005

Recent findings show that the predominant multipotent neural stem cells (NSCs) isolated from postnatal and adult mouse brain express glial fibrillary acid protein (GFAP), a protein commonly associated with astrocytes, and that primary astrocyte cultures can contain GFAP‐expressing cells that act as multipotent NSCs when transferred to neurogenic conditions. The relationship of GFAP‐expressing NSCs to GFAP‐expressing astrocytes is unclear, but has important implications. We compared the phenotype and neurogenic potential of GFAP‐expressing cells derived from different CNS regions and maintained in vitro under different conditions. Multiple labeling immunohistochemistry revealed that both primary astrocyte cultures and adherent neurogenic cultures derived from postnatal or adult periventricular tissue contained subpopulations of GFAP‐expressing cells that co‐expressed nestin and LeX/CD15, two molecules associated with NSCs. In contrast, GFAP‐expressing cells in similar cultures prepared from adult cerebral cortex did not express detectable levels of LeX/CD15, and exhibited no neurogenic potential. Fluorescence‐activated cell sorting (FACS) of both primary astrocyte cultures and adherent neurogenic cultures for LeX/CD15 showed that GFAP‐expressing cells competent to act as multipotent NSCs were concentrated in the LeX‐positive fraction. Using neurosphere assays and a transgenic ablation strategy, we confirmed that the predominant NSCs in primary astrocyte and adherent neurogenic cultures were GFAP‐expressing cells. These findings demonstrate that GFAP‐expressing cells derived from postnatal and adult forebrain are heterogeneous in both molecular phenotype and neurogenic potential in vitro, and that this heterogeneity exists before exposure to neurogenic conditions. The findings provide evidence that GFAP‐expressing NSCs are phenotypically and functionally distinct from non‐neurogenic astrocytes. © 2005 Wiley‐Liss, Inc.
Albumin induces cellular fibrosis by upregulating transforming growth factor‐beta ligand and its receptors in renal distal tubule cells
Authors: Liu Hung‐Chang , Liao Tung‐Nan , Lee Tao‐Chen , Chuang Lea‐Yea , Guh Jinn‐Yuh , Liu Shu‐Fen , Hu Min‐Shou , Yang Ya‐Lin , Lin Shyh‐Horng , Hung Min‐Yuan , Huang Jau‐Shyang , Hung Tsung‐Jen , Chen Chun‐Da , Chiang Tai‐An , Chan Jun‐Yu , Chen Sen‐Yi , Yang Yu‐Lin
Published: November 2005

Albuminuria is indicative of nephropathy. However, little literature has focused on the role of albumin in renal distal tubule fibrosis. We used a well‐defined distal tubule cell, Madin‐Darby Canine Kidney (MDCK). Proliferation and cytotoxicity were examined. The conditioned supernatant was collected and subjected to ELISA assay for detection of fibronectin and TGF‐β1. Reverse transcription‐PCR and Western blot assay were performed to evaluate the expression of mRNA and protein of two types of TGF‐β receptors (TbetaR). Flow cytometry assay and phosphotyrosine (pY)‐specific antibodies were used to assay the phosphorylation status of TbetaR. We showed that albumin dose dependently (0, 0.1, 1, or 10 mg/ml) inhibited cellular growth in MDCK cells without inducing cellular cytoxicity. In addition, albumin significantly upregulated the secretion of both fibronectin and TGF‐β1 at dose over 1 mg/ml. Moreover, 24 h pretreatment of albumin significantly enhanced exogenous TGF‐β1‐induced secretion of fibronectin. These observations were reminiscent of the implications of TbetaR since TbetaR appears to correlate with the susceptibility of cellular fibrosis. We found that albumin significantly increased protein levels of type I TbetaR (TbetaRI) instead of type II receptors (TbetaRII). In addition, phosphorylation level of TbetaRII of both pY259 and pY424 was significantly enhanced instead of pY336. The novel observation indicates that extreme dose of albumin upregulates TGF‐β autocrine loop by upregulating TGF‐β1, TbetaRI, and the receptor kinase activity of TbetaRII by inducing tyrosine phosphorylation on key amino residue of TbetaRII in renal distal tubule cells. These combinational effects might contribute to the pathogenesis of renal fibrosis. J. Cell. Biochem. 97: 956–968, 2006. © 2005 Wiley‐Liss, Inc.
Prevalent mutations in prostate cancer
Authors: Dong Jin‐Tang
Published: November 2005

Quantitative and structural genetic alterations cause the development and progression of prostate cancer. A number of genes have been implicated in prostate cancer by genetic alterations and functional consequences of the genetic alterations. These include the ELAC2 (HPC2), MSR1, and RNASEL (HPC1) genes that have germline mutations in familial prostate cancer; AR, ATBF1, EPHB2 (ERK), KLF6, mitochondria DNA, p53, PTEN, and RAS that have somatic mutations in sporadic prostate cancer; AR, BRCA1, BRCA2, CHEK2 (RAD53), CYP17, CYP1B1, CYP3A4, GSTM1, GSTP1, GSTT1, PON1, SRD5A2, and VDR that have germline genetic variants associated with either hereditary and/or sporadic prostate cancer; and ANXA7 (ANX7), KLF5, NKX3‐1 (NKX3.1), CDKN1B (p27), and MYC that have genomic copy number changes affecting gene function. More genes relevant to prostate cancer remain to be identified in each of these gene groups. For the genes that have been identified, most need additional genetic, functional, and/or biochemical examination. Identification and characterization of these genes will be a key step for improving the detection and treatment of prostate cancer. © 2005 Wiley‐Liss, Inc.
Lymphocyte enhancer‐binding factor 1 (Lef1) inhibits terminal differentiation of osteoblasts
Authors: Kahler Rachel A. , Galindo Mario , Lian Jane , Stein Gary S. , van Wijnen Andre J. , Westendorf Jennifer J.
Published: November 2005

Lef1 is a transcriptional regulator of the Wnt/β‐catenin signaling cascade. Wnts directly augment bone formation and osteoblast differentiation from mesenchymal stem cells by receptor‐mediated pathways involving Lrp5 and Frizzled. We previously reported that Lef1 represses Runx2‐dependent activation of the late osteoblast differentiation gene, osteocalcin. Lef1 is expressed in preosteoblasts but is undetectable in fully differentiated osteoblasts. To determine if downregulation of Lef1 is necessary for osteoblast maturation, we constitutively overexpressed Lef1 in MC3T3‐E1 preosteoblasts. Lef1‐overexpressing cells produced alkaline phosphatase (ALP) and osteocalcin later, and at lower levels than control cells. Moreover, the extracellular matrices of Lef1‐overexpressing cell cultures never mineralized. To further examine the role of Lef1 in osteoblasts, we suppressed Lef1 expression in MC3T3‐E1 cells by RNA interference. Transient expression of a Lef1 shRNA efficiently reduced murine Lef1 levels and transcriptional activity. Stable suppression of Lef1 in MC3T3 preosteoblasts did not affect proliferation or Runx2 levels; however, ALP production and matrix mineralization were accelerated by 3–4 days. Gene chip analyses identified 14 genes that are differentially regulated in Lef1‐suppressed cells. These data outline a role for Lef1 in delaying osteoblast maturation and suggest that Lef1 controls the expression of multiple genes in osteoblasts. J. Cell. Biochem. 97: 969–983, 2006. © 2005 Wiley‐Liss, Inc.
Innovative ways of making aid effective in Ghana: tied aid versus direct budgetary support
Authors: Quartey Peter
Published: November 2005

In 2003, the government of Ghana and its development partners agreed on an aid package dubbed the multi‐donor budgetary support (MDBS), which would ensure continuous flow of aid to finance the government's poverty related expenditures. This paper examines the MDBS, specifically focusing on how it overcomes the problems of tied aid and other project support. It concludes that the MDBS is innovative and could work in Ghana, but it would need trust and a well‐designed, coordinated effort on the part of the government of Ghana and its development partners. Second, its effectiveness would depend crucially on measures to help reduce the debt burden, so that the government would not be compelled to use aid inflows to service its debt. Finally, the MDBS could be more effective if it did not have to operate alongside other project support. Copyright © 2005 John Wiley & Sons, Ltd.
Mutant human tumor suppressor p53 modulates the activation of mitogen‐activated protein kinase and nuclear factor‐κB, but not c‐Jun N‐terminal kinase and activated protein‐1
Authors: Gulati Anthony P. , Yang Yang‐Ming , Harter David , Mukhopadhyay Asok , Aggarwal Bharat A. , Benzil Deborah L. , Whysner John , Albino Anthony P. , Murali Raj , Jhanwar‐Uniyal Meena
Published: November 2005

The roles of the mitogen‐activated kinase protein (MAPK) pathway, nuclear factor‐kappa B (NF‐κB), and activator protein‐1 (AP‐1) in cellular responses to growth factors and mitogen are well established. However, the manner by which these proliferative pathways are affected by the tumor suppressor protein p53 is not fully understood. We report here the results of an investigation of the status of p53 on two human melanoma cell lines with wild‐type p53 (SK‐Mel‐186) or mutant p53 (SK‐Mel‐110). The basal levels of the activated extracellular‐signal regulated kinases 1 and 2 (ERK1/2) were high in cells with wild‐type p53, but low in cells with mutant p53. The 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA)‐induced activation of ERK1/2 through the phosphorylation of threonine and tyrosine at 202 and 204, respectively, was demonstrated in both cell lines, however, in a discrete manner. TPA‐induced activation of ERK1/2 was sustained in wild‐type p53 cells, while only a transient activation was seen in mutant p53 cells. Inhibition of MAPK kinase (MEK), an upstream kinase, by U0126, blocked TPA‐induced activation of ERK1/2 in wild‐type p53 cells and in mutant p53 cells. Treatment of wild‐type p53 (SK‐Mel 186) cells with small interfering RNA (siRNA) of p53 displayed a transient induction of activation of ERK1/2 following TPA treatment, indicating that p53 has a role in the regulation of the activation of ERK1/2. NF‐κB activity decreased significantly in cells with wild‐type p53, while enhanced NF‐κB activity was evident in cells with mutant p53. The expression of either wild‐type or mutant p53 had a similar effect on TPA‐induced Jun N‐terminal kinase (JNK) activation, indicating specificity for the ERK pathway. Similarly, AP‐1 binding activity showed a transient variation in both cell lines after TPA treatment but with different kinetics. These observations suggest that both wild‐type and mutant p53 can modulate the activation pathways for ERK1/2, and NF‐κB distinctively, while modulating the pathways of JNK and AP‐1 similarly. These differences may influence cellular processes such as proliferation, differentiation, and apoptosis. © 2005 Wiley‐Liss, Inc.
Global weak solutions to the problem of continuous sedimentation of an ideal suspension
Authors: Bustos María Cristina , Concha Fernando , Wendland Wolfgang
Published: November 2005

We present the sedimentation of an ideal suspension in a continuous thickener as an initial value problem and study the transient states by constructing the corresponding global weak solutions. Finally, we obtain a way to control the operation of the thickener.
On non‐stationary flows of incompressible asymmetric fluids
Authors: Łukaszewicz Grzegorz
Published: November 2005

We consider an initial boundary value problem for the system of equations describing non‐stationary flows of incompressible asymmetric fluids. We prove the existence of a local in time, weak solution of the problem in the case when the initial density is not separated from zero by a positive constant.
Modelling and solving fixed‐bed adsorption
Authors: Aracil J. , Casillas J. L. , Martínez M. , López‐Gómez J.
Published: November 2005

In this paper we develop a mathematical model for packed‐bed adsorption of a single component, directed toward the purification of β‐lactamic antibiotics. The model describes the removal of sorbates from an aqueous stream entering a bed packed with spherical sorbent particles. Then, assuming that the adsorption isotherm is linear, an exact solution for this model is found.
Relative entropy maximization and directed diffusion equations
Authors: Illner Reinhard , Neunzert Helmut
Published: November 2005

Motivated by the concept of maximum entropy methods in signal and image processing, we introduce and discuss a class of ‘directed diffusion equations’ with suitable boundary conditions. The paradigmatic ‘directed diffusion equation’ is
equation image
The relative entropy \documentclass{article}\pagestyle{empty}\begin{document}$ Sb[f](t): = - \int_\Omega {f(t,x)} \;\ln \;(f(t,x)/b(x))dx $\end{document} is rapidly increasing along solution trajectories of (i). This suggests that solving (i) will yield efficient procedures for entropy maximization. We also discuss the asymptotic behavior of solutions of (i)—this is readily done because (i) has a large family of Ljapunov functionals.
Evolution of a microstructure: A convexified model
Authors: Roubíček Tomáš
Published: November 2005

It is known that, in a steady‐state case, the variational principle of minimal non‐convex potential energy creates a microstructure. This paper tries to formulate evolution of such microstructure on a basis of an energy variational principle (of the Hamilton type) involving a kinetic and a Rayleigh dissipative energies with the generalized impulse respecting a ‘convexified’ geometry. The existence of a solution is proved, using an approximation by a semi‐discretization in time. Some quantitative properties are investigated, too.
On directed diffusion with measurable background
Authors: Illner Reinhard , Tie Jinghzi
Published: November 2005

We show that the ‘directed diffusion equation’

with periodic boundary conditions has a unique weak solution u whenever b is measurable and bounded above and below by positive constants. Also, limt→∞u(t,x) in Lp, 1⩽p≤∞.
Beyond quenching for singular reaction‐diffusion problems
Authors: Chan C. Y. , Ke Lan
Published: November 2005

Let f(u) be twice continuously differentiable on [0, c]) for some constant c such that f(0) > 0,f′ ⩾ 0,f″ ⩾ 0, and limu→cf(u) = ∞. Also, let χ(S) be the characteristic function of the set S. This article studies all solutions u with non‐negative ut, in the region where u < c and with continuous ux for the problem: uxx – ut = − f(u)χ({u < c}), 0 < x < a, 0 < t < ∞, subject to zero initial and first boundary conditions. For any length a larger than the critical length, it is shown that if ∫f(u) du < ∞, then as t tends to infinity, all solutions tend to the unique steady‐state profile U(x), which can be computed by a derived formula; furthermore, increasing the length a increases the interval where U(x)  c by the same amount. For illustration, examples are given.
On boundary controllability of one‐dimensional vibrating systems by W, p‐controls for p ∈ [2, ∞]
Authors: Krabs W. , Leugering G.
Published: November 2005

This paper is concerned with boundary control of one‐dimensional vibrating media whose motion is governed by a wave equation with a 2n‐order spatial self‐adjoint and positive‐definite linear differential operator with respect to 2n boundary conditions. Control is applied to one of the boundary conditions and the control function is allowed to vary in the Sobolev space W, p for p∈[2, ∞] With the aid of Banach space theory of trigonometric moment problems, necessary and sufficient conditions for null‐controllability are derived and applied to vibrating strings and Euler beams.

For vibrating strings also, null‐controllability by Lp‐controls on the boundary is shown by a direct method which makes use of d'Alembert's solution formula for the wave equation.
Stability and asymptotic behaviour in a reaction–diffusion system
Authors: Feng Wei
Published: November 2005

This paper is concerned with some qualitative analysis for a coupled system of five reaction–diffusion equations which arises from a physiology model. The uniform boundedness of the time‐dependent solution is obtained under various boundary conditions. Sufficient conditions are also given to ensure the asymptotic stability of the non‐negative steady‐state solutions under Dirichlet or Robin boundary condition for each component. Under homogeneous Neumann boundary condition for some components the time‐dependent solution is proven to converge to a constant steady state determined by the initial functions.
Guided waves by electromagnetic gratings and non‐uniqueness examples for the diffraction problem
Authors: Bonnet‐Bendhia Anne‐Sophie , Starling Felipe
Published: November 2005

We consider the two‐dimensional scalar problem of the diffraction of a plane wave by an infinite grating of conducting bodies immersed in a periodical dielectric medium. A Fredholm‐type formulation is derived and studied. The existence of a solution is proved and some uniqueness results are established. A detailed description of the guided modes of the grating is carried out. Finally, various non‐uniqueness examples for the diffraction problem are exhibited.
Solitary wave solutions and cnoidal wave solutions to the combined KdV and mKdV equation
Authors: Lou Sen‐Yue , Chen Li‐Li
Published: November 2005

This paper presents a mapping approach for the construction of exact solutions to the combined KdV and mKdV equation. There exist two types of soliton solutions which will reduce back to those of the KdV and mKdV equations in some appropriate limits. Four types of the general cnoidal wave solutions are also obtained.
A posteriori error analysis for linearization of nonlinear elliptic problems and their discretizations
Authors: Han Weimin
Published: November 2005

The paper is devoted to a posteriori quantitative analysis for errors caused by linearization of non‐linear elliptic boundary value problems and their finite element realizations. We employ duality theory in convex analysis to derive computable bounds on the difference between the solution of a non‐linear problem and the solution of the linearized problem, by using the solution of the linearized problem only. We also derive computable bounds on differences between finite element solutions of the nonlinear problem and finite element solutions of the linearized problem, by using finite element solutions of the linearized problem only. Numerical experiments show that our a posteriori error bounds are efficient.
Properties of simple model problems for reacting gas flows
Authors: Tegnér J. K.
Published: November 2005

The compressible Navier–Stokes equations for reacting gases are extremely complex. Simpler models have been considered, and for these completely non‐physical propagation speeds have been observed. These model problems are stiff, meaning that several different scales are present in the solution. Numerical solution of non‐reacting flows almost always involves addition of extra dissipation. It will be shown that this action will render a totally wrong propagation speed for a simple model equation of reacting flows. This problem will be accentuated by increasing stiffness of the problem. Existence and uniqueness of a solution to this model equation is proved. The dependence of the propagation speed on the viscosity and a term governing the stiffness (comparable to the reaction rate for a more complete model) is investigated. A remedy for the wrong propagation speed for this simple model equation is proposed such that the speed is correct although the front is smeared out.
Control problems with state constraints for shape memory alloys
Authors: Sokołowski J. , Sprekels J.
Published: November 2005

In this paper, two different control problems with state constraints for shape memory alloys are considered: in the non‐isothermal case, we study boundary control problems, and in the isothermal situation, a dynamical shape optimization problem is considered. In both cases, the transverse displacement is the constrained state variable. The first‐order conditions of optimality are derived.
Subsolutions and super solutions to systems of parabolic equations with applications to generalized Fujita‐type systems
Authors: Lu G. , Sleeman B. D.
Published: November 2005

A constructive method for obtaining subsolutions and supersolutions to the Cauchy problem for systems of parabolic equations is discussed. Applications of the method to Fujita‐type systems are considered leading to global existence and finite time blow‐up results.
Large time asymptotics for a class of wave equations of higher order with a variable coefficient and time‐independent incitation
Authors: Winter Matthias
Published: November 2005

We consider the equation (−1)m∇m (p∇mu) + ∂u = ƒ in ℝn × [0, ∞] for arbitrary positive integers m and n and under the assumptions p −1, ƒ ϵ C and p > 0. Under the additional assumption that the differential operator (−1)m∇m (p∇mu) has no eigenvalues we derive an asymptotic expansion for u(x,t) as t → including all terms up to order o(1). In particular, we show that for 2m ≥ n terms of the orders tα, log t, (log t)2 and tβ·log t as t → ∞ may occur.
Thermal deformations of inhomogeneous elastic plates
Authors: Tiihonen Timo , Pietikäinen Reijo
Published: November 2005

We consider thermal deformations of transversally inhomogenous elastic plates. Thin plate equations are derived as limits of full three‐dimensional models both in the linear as well as in the non‐linear case with appropriate convergence proofs. In the non‐linear case also the corresponding von Kármán equations are formulated. It is obtained that the inhomogeneity leads to the loss of some symmetry properties at the von Kármán equations.
The identification problem for the exponential Radon transform
Authors: Solmon Donald C.
Published: November 2005

The exponential Radon transform, which arises in single photon emission computed tomography, is defined by ℛ ƒ(μ:ω,s) = ∫Rƒ(sω + tomega;⟂) eμt dtƒ. Here ƒ is a compactly supported distribution in the plane which represents the location and intensity of a radio‐pharmaceutical in a body of constant, but unknown, attenuation μ, and ω is a direction. The identification problem is to determine the attenuation μ from the data ℛƒ with ƒ unknown. We will show that μ can be determined from the data if and only if ƒ is not a radial distribution and give formulae for computing μ when ƒ is not radial.
On an initial boundary value problem for the equations of ideal magneto‐hydrodynamics
Authors: Secchi Paolo
Published: November 2005

We study an initial boundary value problem for the symmetric hyperbolic quasilinear system of the equations of ideal magneto‐hydrodynamics with a perfectly conducting wall boundary condition. Existence of a unique classical solution is proved inside a suitable class of functions of Sobolev type. Moreover, solutions inside the above class are shown to depend continuously in strong norm on the data.