bluuebunny/crossref_metadata_2025 huggingface dataset:
The simulation of inviscid, compressible flows using an upwind kinetic method on unstructured grids
Authors: Mathur J. S. , Weatherill N. P.
Published: October 2005

A kinetic flux‐vector‐splitting method has been used to solve the Euler equations for inviscid, compressible flow on unstructured grids. This method is derived from the Boltzmann equation and is an upwind, cell‐centered, finite volume scheme with an explicit time‐stepping procedure. The Delaunay triangulation has been used to generate the grids. The approach is demonstrated for three flow field simulations, namely the subsonic flow over a two‐component high‐lift aerofoil, the transonic flow over an aerofoil and the supersonic flow in a channel.
A numerical study of the laminar incompressible flow over a 6:1 prolate spheroid at 10° incidence
Authors: Rosenfeld Moshe , Wolfshtein Micha , Israeli Moshe
Published: October 2005

The steady incompressible laminar flow field over a 6:1 prolate spheroid at 10° incidence and a Reynolds number of 1·6 × 106 is investigated numerically by solving a reduced set of the Navier‐Stokes equations. The present study moves one step beyond the boundary layer approximation by relaxing the requirement of an imposed pressure field to permit the calculation of both attached and longitudinal vortical flow fields. The results shed light on the flow properties over slender bodies at intermediate incidence. The longitudinal vortex is found to be weak relative to vortex‐dominated flows. Nevertheless, it has pronounced effects on the flow near the surface and on global features of the flow field. A displacement velocity which describes the effect of the vortical flow on the outer inviscid flow is defined. The line on the spheroid where the displacement velocity vanishes closely follows the projection of the vortex centreline on the surface of the spheroid. It is demonstrated numerically that the convergence of the skin friction lines is not a unique criterion for identifying a vortex flow.
Fluid flow and heat transfer test problems for non‐orthogonal grids: Bench‐mark solutions
Authors: Demirdžić I. , Lilek Ž. , Perić M.
Published: October 2005

Four problems of fluid flow and heat transfer were designed in which non‐orthogonal, boundary‐fitted grids were to be used. These are proposed to serve as test cases for testing new solution methods. This paper presents solutions of the test problems obtained by using a multigrid finite volume method with grids of up to 320 × 320 control volumes. Starting from zero fields, iterations were performed until the sum of the absolute residuals had fallen seven orders of magnitude, thus ensuring that the variable values did not change to six most significant digits. By comparing the solutions for successive grids at moderate Reynolds and Rayleigh numbers, the discretization errors were estimated to be lower than 0·1%. The results presented in this paper may thus serve for comparison purposes as bench‐mark solutions.
Advection‐diffusion modelling using the modified QUICK scheme
Authors: Chen Yiping , Falconer Roger A.
Published: October 2005

In recent years the QUICK finite difference scheme has been increasingly used in solving the advection‐diffusion equation, particularly for water quality modelling studies relating to coastal and estuarine flows. This scheme has the benefits of mass conservation, reasonably high accuracy and computational efficiency in comparison with many other higher‐order‐accurate schemes reported in the recent literature. A von Neumann stability analysis showed that the explicit QUICK scheme has a severe stability constraint which depends upon the diffusion coefficient. It can be proved that this scheme is numerically unstable for the case of pure advection. Various modified forms of the implicit QUICK scheme have been formulated and their numerical stability properties have been studied and analysed. The modified QUICK schemes considered have been tested for transient simulations for the cases of pure advection and of advection and diffusion in an idealized one‐dimensional basin using three different initial boundary conditions: (a) a sharp front concentration gradient, (b) a Gaussian concentration distribution and (c) a plug source. Details of the comparisons between these modified schemes and with other typical second‐order‐accurate difference schemes are given, together with comparisons with the analytical solutions for each case. A two‐dimensional version of the semi‐time‐centred QUICK scheme (ADI‐QUICK), has also been applied to a two‐dimensional test case using the standard ADI technique and has been shown to be attractive in comparison with other comparable second‐order schemes.
Numerical study on the two‐phase flow distribution in a T‐junction
Authors: Moura L. F. M. , Rezkallah K. S.
Published: October 2005

The main objective of this paper is to investigate the ability of a two‐dimensional two‐fluid computer code to predict the phase separation in a T‐junction. A new semi‐implicit numerical scheme is developed for solving the two‐fluid model equations. Special attention is directed to the modelling of the constitutive for the interfacial friction term. Detailed distribution of void fraction, pressure and velocities are obtained for an air–water mixture in a vertical tee. Good agreement was obtained between the computer code results and the experimental data for the phase separation in the T‐junction.
Numerical computations of two‐dimensional solitary waves generated by moving disturbances
Authors: Cao Yusong , Beck Robert F. , Schultz William W.
Published: October 2005

Two‐dimensional solitary waves generated by disturbances moving near the critical speed in shallow water are computed by a time‐stepping procedure combined with a desingularized boundary integral method for irrotational flow. The fully non‐linear kinematic and dynamic free‐surface boundary conditions and the exact rigid body surface condition are employed. Three types of moving disturbances are considered: a pressure on the free surface, a change in bottom topography and a submerged cylinder. The results for the free surface pressure are compared to the results computed using a lower‐dimensional model, i.e. the forced Korteweg–de Vries (fKdV) equation. The fully non‐linear model predicts the upstream runaway solitons for all three types of disturbances moving near the critical speed. The predictions agree with those by the fKdV equation for a weak pressure disturbance. For a strong disturbance, the fully non‐linear model predicts larger solitons than the fKdV equation. The fully non‐linear calculations show that a free surface pressure generates significantly larger waves than that for a bottom bump with an identical non‐dimensional forcing function in the fKdV equation. These waves can be very steep and break either upstream or downstream of the disturbance.
A least squares finite element method for viscoelastic fluid flow problems
Authors: Wang K. C. , Carey G. F.
Published: October 2005

Viscoelastic flows remain a demanding class of problems for approximate analysis, particularly at increasing Weissenberg numbers. Part of the difficulty stems from the convective behavior and in the treatment of the stress field as a primary unknown. This latter aspect has led to the use of higher‐order piecewise approximations for the stress approximation spaces in recent finite element research. The computational complexity of the discretized problem is increased significantly by this approach but at present it appears the most viable technique for solving these problems. Motivated by recent success in treating mixed systems and convective problems, we formulate here a least squares finite element method for the viscoelastic flow problem. Numerical experiments are conducted to test the method and examine its strengths and limitations. Some difficulties and open issues are identified through the numerical experiments. We consider the use of high degree elements (p refinement) to improve performance and accuracy.
Enhancing the mechanical integrity of the implant–bone interface with BoneWelding® technology: Determination of quasi‐static interfacial strength and fatigue resistance
Authors: Ferguson Stephen J. , Weber Urs , von Rechenberg Brigitte , Mayer Joerg
Published: October 2005

The BoneWelding® technology is an innovative bonding method, which offers new alternatives in the treatment of fractures and other degenerative disorders of the musculoskeletal system. The BoneWelding process employs ultrasonic energy to liquefy a polymeric interface between orthopaedic implants and the host bone. Polymer penetrates the pores of the surrounding bone and, following a rapid solidification, forms a strong and uniform bond between implant and bone. Biomechanical testing was performed to determine the quasi‐static push‐out strength and fatigue performance of 3.5‐mm‐diameter polymeric dowels bonded to a bone surrogate material (Sawbones solid and cellular polyurethane foam) using the BoneWelding process. Fatigue tests were conducted over 100,000 cycles of 20–100 N loading. Mechanical test results were compared with those obtained with a comparably‐sized, commercial metallic fracture fixation screw. Tests in surrogate bone material of varying density demonstrated significantly superior mechanical performance of the bonded dowels in comparison to conventional bone screws (p < 0.01), with holding strengths approaching 700 N. Even in extremely porous host material, the performance of the bonded dowels was equivalent to that of the bone screws. For both cellular and solid bone analog materials, failure always occurred within the bone analog material surrounding and distant to the implant; the infiltrated interface was stronger than the surrounding bone analog material. No significant decrease in interfacial strength was observed following conditioning in a physiological saline solution for a period of 1 month prior to testing. Ultrasonically inserted implants migrated, on average, less than 20 μm over, and interfacial stiffness remained constant the full duration of fatigue testing. With further refinement, the BoneWelding technology may offer a quicker, simpler, and more effective method for achieving strong fixation and primary stability for fracture fixation or other orthopaedic and dental implant applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Induction of chemokines and chemokine receptors CCR2b and CCR4 in authentic human osteoclasts differentiated with RANKL and osteoclast like cells differentiated by MCP‐1 and RANTES
Authors: Kim Michael S. , Magno Carly L. , Day Christopher J. , Morrison Nigel A.
Published: October 2005

Chemokines MCP‐1 and RANTES are induced when authentic bone resorbing human osteoclasts differentiate from monocyte precursors in vitro. In addition, MCP‐1 and RANTES can stimulate the differentiation of cells with the visual appearance of osteoclasts, being multinuclear and positive for tartrate resistance acid phosphatase (TRAP +). We show here that MIP1α is also potently induced by RANKL during human osteoclast differentiation and that this chemokine also induces the formation of TRAP + multinucleated cells in the absence of RANKL. MIP1α was able to overcome the potent inhibition of GM‐CSF on osteoclast differentiation, permitting the cells to pass through to TRAP + multinuclear cells, however these were unable to form resorption pits. Chemokine receptors CCR2b and CCR4 were potently induced by RANKL (12.6‐ and 49‐fold, P = 4.0 × 10−7 and 4.0 × 10−8, respectively), while CCR1 and CCR5 were not regulated. Chemokine treatment in the absence of RANKL also induced MCP‐1, RANTES and MIP1α. Unexpectedly, treatment with MCP‐1 in the absence of RANKL resulted in 458‐fold induction of CCR4 (P = 1.0 × 10−10), while RANTES treatment resulted in twofold repression (P = 1.0 × 10−4). Since CCR2b and CCR4 are MCP‐1 receptors, these data support the existence of an MCP‐1 autocrine loop in human osteoclasts differentiated using RANKL. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Interleukin‐1β induces osteopontin expression in pulmonary fibroblasts
Authors: Serlin David M. , Kuang Ping Ping , Subramanian Mangalalaxmy , O'Regan Anthony , Li Xinfang , Berman Jeffrey S. , Goldstein Ronald H.
Published: October 2005

Osteopontin is a multifunctional matricellular protein identified as one of the most upregulated genes in pulmonary fibrosis. Experimental animal models have identified early pro‐fibrotic cytokines as essential to the pathogenesis of inflammation‐induced pulmonary fibrosis. However, the principal sources of osteopontin in the fibroproliferative lung, and the factors responsible for its induction, have not been fully defined. We isolated primary rat lung fibroblasts in culture to examine the expression and regulation of lung fibroblast‐derived osteopontin. Our results demonstrate a potent and dramatic increase in osteopontin expression induced by interleukin‐1β (IL‐1β), whereas tumor necrosis factor‐α, transforming growth factor‐β, and angiotensin II had minimal effect. Stimulation with IL‐1β resulted in the secretion of soluble osteopontin protein. We found that osteopontin expression by IL‐1β was regulated via signaling primarily through the mitogen‐activated protein kinase member ERK1/2, partially by p38 MAPK, but not at all by JNK. Finally, the mechanism of IL‐1β increase in osteopontin mRNA requires de novo transcription and translation. In conclusion, we find that osteopontin is expressed by primary lung fibroblasts and is potently upregulated by the early inflammatory and pro‐fibrotic cytokine IL‐1β. Activated fibroblasts may be a significant source of osteopontin production during lung fibrogenesis. J. Cell. Biochem. © 2005 Wiley‐Liss, Inc.
Interpolymer Complex between Hydroxypropyl Cellulose and Maleic Acid–Styrene Copolymer: Phase Behavior of Semi‐Dilute Solutions
Authors: Bumbu Gina‐Gabriela , Eckelt John , Wolf Bernhard A. , Vasile Cornelia
Published: October 2005

Summary: The phase behavior of a water/hydroxypropyl cellulose/maleic acid–styrene copolymer (H2O/HPC/MAc‐S) system was investigated in the semi‐dilute range by turbidimetry, rheology, and optical microscopy. The two polymers under investigation form interpolymer complexes via hydrogen bonding. In the case of a total polymer concentration of cpol = 5 mg · mL−1 a second phase segregates upon heating the homogeneous ternary system. By applying a constant shear rate ($\dot \gamma$ = 50 s−1) the phase separation temperature of the system is 10–15 °C lower than for an unsheared one. For cpol = 10 mg · mL−1 phase separation has already occurred at room temperature when the two binary polymer solutions are mixed. The distribution of the partners among the coexisting phases was examined by FT‐IR spectroscopy. The stoichiometry of the interpolymeric complex (IPC) was estimated to be HPC/MAc‐S = 40:60 (w/w) independent of cpol.

The phase separation temperature of HPC/MAc‐S aqueous mixtures versus the weight fraction of the HPC in the blend.

magnified image

The phase separation temperature of HPC/MAc‐S aqueous mixtures versus the weight fraction of the HPC in the blend.
Cognitive profiles of individual patients with Parkinson's disease and dementia: Comparison with dementia with lewy bodies and Alzheimer's disease
Authors: Janvin Carmen Cristea , Larsen Jan Petter , Salmon David P. , Galasko Douglas , Hugdahl Kenneth , Aarsland Dag
Published: October 2005

We describe the pattern of cognitive profiles within a community‐based sample of patients with Parkinson's disease (PD) and dementia (PDD) using cluster analyses, and compare the results with data from patients with Alzheimer's disease (AD) and dementia with Lewy bodies (DLB). Fifty patients with PDD and 39 with AD from Stavanger, Norway, and 62 patients with DLB from San Diego, CA, USA were diagnosed by either standardized clinical procedures or criteria (all PDD and all AD cases) or necropsy (all DLB cases). Four subgroups were identified: two subgroups with a subcortical cognitive profile (one with mild and one with moderate dementia severity), one subgroup with global impairment and severe dementia, and one subgroup with a cortical cognitive profile and moderate dementia. Of the patients with PDD and with DLB, 56% and 55%, respectively, had a subcortical cognitive profile, compared with only 33% of the AD patients. Conversely, 30% of the patients with PDD and 26% of those with DLB had a cortical cognitive profile, compared with 67% of the patients with AD. These findings suggest that in some patients with PDD, frontosubcortical changes are the main contributing factor to dementia, whereas in other patients, cortical and hippocampal changes are more important. © 2005 Movement Disorder Society
A one‐dimensional dynamic contact problem in linear viscoelasticity
Authors: Kim Jong Uhn
Published: October 2005

The initial‐boundary value problem associated with a linear viscoelastic bar which moves along its axis and against a stationary obstacle perpendicular to the axis is discussed. The existence of a solution is established by the penalty method and a multiplier technique. The uniqueness of the solution is also proved in a special case.
Remarks on the wave front of polarization: Polarized solutions for the evolution three‐dimensional Lame system
Authors: Chełminski K. , Łada A. , Sidz L.
Published: October 2005

Some remarks complementary to the work of N. Dencker in [1] concerning the wave front of polarization are given. The theorem due to N. Dencker about the propagation of a wave front of polarization is applied to solutions for the evolution of the three‐dimensional Lame system. The propagation of polarized solutions is established.
The boundary equation method in the third initial boundary value problem of the theory of elasticity. Part 1. Existence theorems
Authors: Chudinovich I. Yu.
Published: October 2005

This work deals with four variants of boundary equations appearing if the third main initial boundary value problem is solved with the help of elastic retarded potentials. The solvability of these equations is proved, and the smoothness of their solutions researched.
Decay properties of periodic, radially symmetric solutions of Sine‐Gordon‐type equations
Authors: Scarpellini B.
Published: October 2005

We investigate the radially symmetric, nonlinear wave equation
equation image
and discuss the asymptotic behaviour as r → ∞ of solutions which are T‐periodic in time t. It is shown that only two possibilities of decay can arise, namely polynomial like t−½(n−1) and exponential e−bt for some b > 0. Existence results are obtained.
Outgassing and contamination: Strict solution of a Boltzman‐like model
Authors: Belleni‐Morante A. , Busoni G.
Published: October 2005

We consider a Boltzmann‐like model of a problem of outgassing and contamination in a region ℛ. For simplicity, we assume that ℛ = ℛ1 ∪ ℛ2 ∪ ℛ3, where ℛ1 is the slab {x: −a < x < 0}, ℛ2 = {x:0 < x < b}, ℛ3 = {x: b < x < b1}. ℛ1 is the region where the contaminant particles are produced, ℛ2 is the ‘cavity’ where such particles migrate and interact with some inert gas, usually at low pressure, and ℛ3 is the region which is contaminated by the particles coming from ℛ2. In each of the three regions, the behaviour of the contaminant particles is represented by means of a Boltzmann‐like equation.

We prove that such a mathematical problem has a unique positive strict solution, belonging to a suitable Banach space Y. A system of ordinary differential equations is also derived, which gives the global balances of the contaminant particles in each of the three regions.
A solution formula for a non‐convex scalar hyperbolic conservation law with monotone initial data
Authors: Kunik Matthias
Published: October 2005

In this paper we prove an explicit representation formula for the solution of a one‐dimensional hyperbolic conservation law with a non‐convex flux function but monotone initial data. This representation formula is similar to those of Lax [10] and Kunik [7,8] and enables us to compute the solution pointwise explicitly. This result is a generalization of a theorem given in Kunik [8] where the case of only one inflexion point for the fluxes was considered. Its proof uses the polygonal method of Dafermos [2]. The application of this method leads to a simple explicit construction of the solutions for a Kynch sedimentation process [9] and to an explicit parameter representation for the shock curves evolving during the sedimentation process.
Finite element approximation of a microstructure evolution
Authors: Roubiček Tomáš
Published: October 2005

The evolution model of a microstructure described as appropriately generalized Young measures, which was developed in [11], is discretized here by means of a suitably adapted finite element method. The convergence of the approximate solutions is proved, and a one‐dimensional example is treated to discuss some implementation experience and to show some illustrative results.
Continuous dependence of the scattering amplitude on the surface of an obstacle
Authors: Ramm A. G.
Published: October 2005

Let Dj,j = 1,2, be two bounded domains (obstacles) in ℝn, n ≥ 2, with the boundaries Γj. Let Aj be the scattering amplitude corresponding to Dj. The Dirichlet boundary condition is assumed on Γj. A formula is derived for A:= A1 − A2. This formula is used for a derivation of the estimate of ∣A1 − A2∣ in terms of the distance d(Γ1, Γ2) between Γ1 and Γ2. If d(Gamma;1, Gamma;2) ⩽ ϵ, then ∣A∣ ⩽ cϵ, where c is a positive constant which depends on Γ1 and Γ2 provided that one of the boundaries is of C1,λ class, 0 < λ < 1, and the other one is a polyhedron which approximates the first one. The results are useful, in particular, for boundary elements method of solving scattering problems.
Vacuum and non‐vacuum solutions of the quasi‐hydrodynamic semiconductor model in thermal equilibrium
Authors: Unterreiter A.
Published: October 2005

The quasi‐hydrodynamical model for bipolar semiconductor devices in thermal equilibrium admits in general solutions for which the non‐negative electron‐ or hole‐density is not strict positive. In this paper sufficient conditions depending on the device's data which lead to or prevent vacuum are presented. The transformation of the model equations to a single semilinear elliptic mixed boundary value problem for the electrostatic potential V reduces the vacuum‐non‐vacuum discussion to an investigation of the range of V. Monotonicity arguments and the employment of local sub‐ and supersolutions allow to estimate the size as well as the distance from the Dirichlet boundary of the respective vacuum sets. An one‐dimensional model is analysed in some detail.
Parallel block preconditioning based on SSOR and MILU
Authors: Washio Takumi , Hayami Ken
Published: October 2005

Two kinds of parallel preconditioners for the solution of large sparse linear systems which arise from the 2‐D 5‐point finite difference discretization of a convection‐diffusion equation are introduced. The preconditioners are based on the SSOR or MILU preconditioners and can be implemented on parallel computers with distributed memories. One is the block preconditioner, in which the interface components of the coefficient matrix between blocks are ignored to attain parallelism in the forward‐backward substitutions. The other is the modified block preconditioner, in which the block preconditioner is modified by taking the interface components into account. The effect of these preconditioners on the convergence of preconditioned iterative methods and timing results on the parallel computer (Cenju) are presented.
An energy‐consistent material‐point method for dynamic finite deformation plasticity
Authors: Love E. , Sulsky D. L.
Published: October 2005

Energy consistency for the material‐point method (MPM) is examined for thermodynamically consistent hyperelastic‐plastic materials. It is shown that MPM can be formulated with implicit, three‐ field variational, finite element algorithms which dissipate energy and conserve momentum for that class of material models. With a consistent mass matrix the resulting overall numerical method inherits the energy‐dissipative and momentum‐conserving properties of the mesh solution. Thus, the proposed MPM algorithm satisfies by construction a time‐discrete form of the second law of thermo‐ dynamics. Properties of the method are illustrated in numerical examples. Copyright © 2005 John Wiley & Sons, Ltd.
Use of higher‐order shape functions in the scaled boundary finite element method
Authors: Vu Thu Hang , Deeks Andrew J.
Published: October 2005

The scaled boundary finite element method is a novel semi‐analytical technique, whose versatility, accuracy and efficiency are not only equal to, but potentially better than the finite element method and the boundary element method for certain problems. This paper investigates the possibility of using higher‐order polynomial functions for the shape functions. Two techniques for generating the higher‐order shape functions are investigated. In the first, the spectral element approach is used with Lagrange interpolation functions. In the second, hierarchical polynomial shape functions are employed to add new degrees of freedom into the domain without changing the existing ones, as in the p‐version of the finite element method. To check the accuracy of the proposed procedures, a plane strain problem for which an exact solution is available is employed. A more complex example involving three scaled boundary subdomains is also addressed. The rates of convergence of these examples under p‐refinement are compared with the corresponding rates of convergence achieved when uniform h‐refinement is used, allowing direct comparison of the computational cost of the two approaches. The results show that it is advantageous to use higher‐order elements, and that higher rates of convergence can be obtained using p‐refinement instead of h‐refinement. Copyright © 2005 John Wiley & Sons, Ltd.
An adaptive finite element method for transient compressible flows
Authors: Probert J. , Hassan O. , Peraire J. , Morgan K.
Published: October 2005

An adaptive finite element method for the solution of time dependent strongly compressible flows in two dimensions is described. The computational domain is represented by an unstructured assembly of linear triangular elements and the mesh adaptation is achieved by local regeneration of the grid, using an error estimation procedure coupled to an automatic triangular mesh generator. Problems involving shock propagation are solved to illustrate the numerical performance of the proposed approach.
Analysis of orthogonal metal cutting processes
Authors: Tyan T. , Yang Wei H.
Published: October 2005

The orthogonal metal cutting process for a controlled contact tool is simulated using a limit analysis theorem. The basic principles are stated in the form of a primal optimization problem with an objective function subjected to constraints of the equilibrium equation, its static boundary conditions and a constitutive inequality. An Eulerian reference co‐ordinate is used to describe the steady state motion of the workpiece relative to the tool. Based on a duality theorem, a dual functional bounds the objective functional of the primal problem from above by a sharp inequality. The dual formulation seeks the least upper bound and thus recovers the maximum of the primal functional theoretically. A finite element approximation of the continuous variables in the dual problem reduces it to a convex programming. Since the original dual problem admits discontinuous solutions in the form of bounded variation functions, care must be taken in the finite element approximation to account for such a possibility. This is accomplished by a combined smoothing and successive approximation algorithm. Convergence is robust from any initial iterate. Results are obtained for a wide range of control parameters including cutting depth, rake angle, rake length and friction. The converged solutions provide information on cutting force, chip thickness, chip stream angle and shear angle which agree well both in values and trend with the published data. But the available data represent only a small subset in the range of parameters exhaustively investigated in this paper.
Structural properties of chalcopyrite thin films studied by Raman spectroscopy
Authors: Papadimitriou D. , Esser N. , Xue C.
Published: October 2005

This paper reviews the structural properties of ternary chalcopyrite absorbers for solar‐cell device applications studied by Raman Spectroscopy. Raman mode assignment in CuGaSe2 is reviewed according to the results of previous and present Raman and IR spectroscopic studies. The compositional dependence of Raman modes, in particular, the composition dependent frequency shift of the A1‐mode, is suggested for the analysis of the chalcopyrite film structure. Order and disorder effects are discussed with reference to the excitation of phonon modes assigned to Cu–Au ordered phases and to defect related phases, respectively. Phase separation effects associated with the formation of secondary microcrystalline CuxSe‐ or CuxS‐phases and the observation of Raman scattering from these phases are also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scattering of light from metallic films with a corrugated surface: Magnetic field effects in the Voigt geometry
Authors: Jacobo‐Escobar J. H. , Cocoletzi Gregorio H.
Published: October 2005

We study the scattering of electromagnetic waves from a corrugated surface of a metallic film, which has a flat surface in contact with a semi‐infinite superlattice. External magnetic fields are accounted for, in the Voigt configuration, to calculate the scattered field amplitudes up to first order on the corrugation height. Two‐zero order minima and two‐first order peaks are obtained as a result of the coupling of the incident light with the magnetoplasmons at the corrugated surface. The peaks are associated with the p = ±1 terms in the expansion of the fields. We find that the splitting of the minima is affected by the external field and the superlattice. In the absence of the superlattice the external field splits the symmetric and antisymmetric film modes, however, the presence of the superlattice closes the gap. The gap also depends on the angle of incidence. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of sample size formulae for 2 × 2 cross‐over designs applied to bioequivalence studies
Authors: Siqueira Arminda Lucia , Whitehead Anne , Todd Susan , Lucini María M.
Published: October 2005

We consider the comparison of two formulations in terms of average bioequivalence using the 2 × 2 cross‐over design. In a bioequivalence study, the primary outcome is a pharmacokinetic measure, such as the area under the plasma concentration by time curve, which is usually assumed to have a lognormal distribution. The criterion typically used for claiming bioequivalence is that the 90% confidence interval for the ratio of the means should lie within the interval (0.80, 1.25), or equivalently the 90% confidence interval for the differences in the means on the natural log scale should be within the interval (−0.2231, 0.2231). We compare the gold standard method for calculation of the sample size based on the non‐central t distribution with those based on the central t and normal distributions. In practice, the differences between the various approaches are likely to be small. Further approximations to the power function are sometimes used to simplify the calculations. These approximations should be used with caution, because the sample size required for a desirable level of power might be under‐ or overestimated compared to the gold standard method. However, in some situations the approximate methods produce very similar sample sizes to the gold standard method. Copyright © 2005 John Wiley & Sons, Ltd.
Symbolic execution of floating‐point computations
Authors: Botella Bernard , Gotlieb Arnaud , Michel Claude
Published: October 2005

Symbolic execution is a classical program testing technique which evaluates a selected control flow path with symbolic input data. A constraint solver can be used to enforce the satisfiability of the extracted path conditions as well as to derive test data. Whenever path conditions contain floating‐point computations, a common strategy consists of using a constraint solver over the rationals or the reals. Unfortunately, even in a fully IEEE‐754‐compliant environment, this leads not only to approximations but also can compromise correctness: a path can be labelled as infeasible although there exists floating‐point input data that satisfy it. In this paper, the peculiarities of symbolic execution of programs with floating‐point numbers are addressed. Issues in the symbolic execution of this kind of program are carefully examined and a constraint solver is described that supports constraints over floating‐point numbers. Preliminary experimental results demonstrate the value of the approach proposed. Copyright © 2005 John Wiley & Sons, Ltd.
Quinolinic acid reduces the antioxidant defenses in cerebral cortex of young rats
Authors: Leipnitz Guilhian , Schumacher Cristiana , Scussiato Karina , Dalcin Karina B. , Wannmacher Clóvis M.D. , Wyse Angela T.D. , Dutra‐Filho Carlos S. , Wajner Moacir , Latini Alexandra
Published: October 2005

Quinolinic acid (QA), the major metabolite of the kynurenine pathway, is found at increased concentrations in brain of patients affected by various common neurodegenerative diseases, including Huntington's disease and Alzheimer's disease. Recently, a role for QA in the pathophysiology of glutaric acidemia type I (GAI) was postulated. Considering that oxidative stress has been recently involved in the pathophysiology of the brain injury in these neurodegenerative disorders; in the present study, we investigated the in vitro effect of QA on various parameters of oxidative stress, namely total radical‐trapping antioxidant potential (TRAP), total antioxidant reactivity (TAR), glutathione (GSH) levels, thiobarbituric acid‐reactive substances (TBA‐RS) measurement and chemiluminescence in cerebral cortex of 30‐day‐old rats. QA diminished the brain non‐enzymatic antioxidant defenses, as determined by the reduced levels of TRAP, TAR and GSH. We also observed that QA significantly increased TBA‐RS and chemiluminescence. Therefore, in vitro QA‐treatment of rat cortical supernatants induced oxidative stress by reducing the tissue antioxidant defenses and increasing lipid oxidative damage, probably as a result of free radical generation. In addition, we examined the effect of QA on TBA‐RS levels in the presence of glutaric acid (GA) and 3‐hydroxyglutaric acid (3HGA), which are accumulated in GAI, as well as in the presence of 3‐hydroxykynurenine (3HK), a tryptophan metabolite of the kynurenine pathway with antioxidant properties. It was verified that the single addition of QA or GA plus 3HGA to the incubation medium significantly stimulated in vitro lipid peroxidation. Furthermore, 3HK completely prevented the TBA‐RS increase caused by the simultaneous addition of QA, GA and 3HGA. Taken together, it may be presumed that QA induces oxidative stress in the brain, which may be associated, at least in part, with the pathophysiology of central nervous system abnormalities of neurodegenerative diseases in which QA accumulates.
Telemedicine and robotics: Paving the way to the globalization of surgery
Authors: Senapati S. , Advincula A.P.
Published: October 2005

The concept of delivering health services at a distance, or telemedicine is becoming an emerging tool for the field of surgery. For the surgical services, telepresence surgery through robotics is gradually being incorporated into health care practices. This article will provide a brief overview of the principles surrounding telemedicine and telepresence surgery as they specifically relate to robotics. Where limitations have been reached in laparoscopy, robotics has allowed further steps forward. The development of robotics in medicine has been a progression from passive to immersive technology. In gynecology, the utilization of robotics has evolved from the use of Aesop®, a robotic arm for camera manipulation, to full robotic systems such as Zeus®, and the daVinci® surgical system. These systems have not only been used directly for a variety of procedures but have also become a useful tool for conferencing and the mentoring of surgeons from afar. As this mode of technology becomes assimilated into the culture of surgery and medicine globally, caution must be taken to carefully navigate the economic, legal and ethical implications of telemedicine. Despite the challenges faced, telepresence surgery holds promise for more widespread applications.
rapid voluntary stomach eversion in a free-living shark
Authors: brunnschweiler juerg m. , andrews paul l.r. , southall emily j. , pickering mark , sims david w.
Published: October 2005

video observation of oral gastric eversion in a free-living caribbean reef shark (carcharhinus perezi) shows voluntary gastric eversion followed by retraction not only occurs, but is extremely rapid (lasting ∼0.3 s). eversion may occur by stomach relaxation–oesophageal contraction coupled with increased abdominal pressures to enable prolapse, and retraction by a mechanism analogous to suction feeding. this behaviour provides a ‘cleansing’ function for removing indigestible food particles, parasites or mucus from the stomach lining. sharks, and possibly other animals with similar gut morphologies, may use this technique to help maintain a healthy alimentary tract.
sexual maturity, fecundity and embryonic development of the spiny dogfish, squalus acanthias, in the eastern mediterranean sea
Authors: chatzispyrou archontia , megalofonou persefoni
Published: October 2005

the reproductive biology of the spiny dogfish, squalus acanthias, was investigated throughout a year, in the eastern mediterranean sea. one hundred and eighty specimens were sampled of which 119 were females and 61 males, ranging from 320 to 755 mm and from 350 to 820 mm total length (tl), respectively. the minimum size of mature females was 515 mm and 470 mm tl for mature males (smaller compared with sizes in other studies). gonadosomatic index (gsi) and hepatosomatic index (hsi) were higher during june and august in female dogfish, respectively; in males gsi had a peak in july and hsi showed its highest value in april. a total of 39 gravid females was identified with tl ranging between 570 and 755 mm. only 28 of them were bearing embryos; candled uteri were observed in the 11 other gravid animals. a positive relationship was recorded between maternal length and litter size. ovarian fecundity ranged between 1 and 6 (mean 2.1±1.1); uterine fecundity ranged from 1 to 6 (mean 3.3±1.2). the size of the pups varied from 72 to 220 mm tl and their weight ranged between 1.6–48.5 g (mean 11.7±8.6). the spiny dogfish was compared with fish from other study areas and was found to be smaller in size in the eastern mediterranean sea, reaching maturity at smaller sizes and obtaining lower fecundity than female fish in other areas.
interpretation of vertebral growth marks as annuli in the sandbar shark carcharhinus plumbeus: analysis of vertebrae of captive specimens
Authors: torres borja , morey gabriel , tomás javier
Published: October 2005

four captive specimens of sandbar shark carcharhinus plumbeus from the l'oceanogràfic aquarium (valencia, spain) were studied: one adult female (192 cm total length [tl]) reared for five months, her two new born pups (a female, 61 cm tl and a male, 60 cm tl), and one juvenile female, born in captivity, dead at nine months of age (90 cm tl). comparative measurements of length and diameter of vertebrae from three different regions of the vertebral column showed that vertebrae above the pelvic fins (nos. 59–63) are the biggest in this species. consequently, these vertebrae are preferred for age estimation given that growth marks are easier to identify. the only present mark in the vertebrae of the two neonate specimens was at the edge and was interpreted as the birth mark. a mark at a similar distance was present in the vertebrae of the juvenile and adult females.

adult female vertebrae analysis shows 23 marks without any variation in the banding pattern distribution during free-range growth and short period of captivity. the juvenile individual shows two clear growth marks developed after birth. the presence of these marks in a 9-month old individual suggests that the counting of all vertebral growth marks as annuli may result in the overestimation of age for this shark species.
implications of different brood pouch structures in syngnathid reproduction
Authors: monteiro n.m. , almada v.c. , vieira m.n.
Published: October 2005

the evolutionary radiation of the family syngnathidae was accompanied by a diversification of structures involved in male parental care whose anatomical variations may signal differences in reproductive strategies, with increasing egg protection possibly affecting female investment in offspring or larvae quality at the end of the embryonic development phase. an analysis of egg numbers showed significant differences between syngnathids with and without marsupium, suggesting that the brood pouch, besides increasing protection to the male and its eggs, also introduced the ability to carry an additional number of offspring per pregnancy, from one or more females. curiously, even though larvae sizes do not significantly differ between the considered brooding structures (controlling for male length), seahorse larvae were smaller than expected, given the large volume of the pear-shaped eggs. these observations suggest that the sealed seahorse pouch, although allowing the transport of a great number of offspring and capable of multiple consecutive pregnancies, may impose serious functional constraints, namely those related with oxygenation of the developing larvae, thus explaining the increased egg surface together with the presence of specific salinity control mechanisms inside the marsupium.
larval growth and mortality of japanese spanish mackerel (scomberomorus niphonius) in the central seto inland sea, japan
Authors: shoji jun , maehara tsutomu , tanaka m.
Published: October 2005

growth and mortality rates of larval japanese spanish mackerel (scomberomorus niphonius) were estimated by using otolith daily increments in 1997 and 1998 in the sea of hiuchi, central seto inland sea. there was no day–night difference in the abundance and size-distribution of s. niphonius larvae in the 3–10 mm size-classes, indicating the larvae were efficiently collected by the larva-net used for sampling (1.3 m mouth diameter, 0.5 mm mesh). mean absolute growth rate (0.748 mm d−1 in 1997, 0.821 mm d−1 in 1998), weight specific growth coefficient (g: 0.402 in 1997, 0.444 in 1998) and mortality coefficient (m: 0.784 in 1997 and 0.625 in 1998) were among the highest reported for marine fish larvae. scomberomorus niphonius seems to have evolved survival strategies characterized by fast growth with strong piscivory that can reduce duration of the larval period with the high mortality. in 1997, spatial distribution of the larvae was not well corresponded to that of their prey, clupeid larvae, and the larval feeding incidence was lower than in 1998. recruitment potential assessed by examining the ratio of g:m was lower in 1997 (0.513 in 1997, 0.711 in 1998) due to the lower g and higher m values. prey fish availability may be one of the important determinants for the recruitment potential by controlling the larval mortality due to starvation and/or starvation-related predation.
a revised description of scorpaena maderensis (scorpaenidae) by means of meristic and morphometric analysis
Authors: mesa g. la
Published: October 2005

a sample of 178 specimens, collected along the south-eastern cost of sicily (central mediterranean sea), was analysed. most meristic counts and measurements given by previous authors were updated, due to the larger variability observed in the present sample. sexual dimorphism was observed in fish-size and in other morphometric measurements, mostly concerning the head region. the most useful diagnostic characters of scorpaena maderensis were the presence of cycloid scales on the chest and the pectoral fin base, some features of body coloration and the shortness of supraocular tentacles, the latter two being easily detectable also during field observation. only a few morphometric and meristic measurements, along with some morphological features, were indicated as further elements to distinguish s. maderensis from s. porcus.
record of acanthocybium solandri in the central mediterranean sea, with notes on parasites
Authors: romeo t. , azzurro e. , mostarda e.
Published: October 2005

one specimen of wahoo, acanthocybium solandri was caught in june 2004 by artisanal fishermen in the straits of messina, sicily. this epipelagic species has a circum-tropical distribution and in the mediterranean has been recorded only twice. meristic characteristics, gonads and stomach contents were analysed. two species of parasites, the giant trematodes hirudinella ventricosa and the monogenean neothoracocotyle acanthocybii were detected in the stomach and in the gills, respectively. the presence of these helminths, typical of hosts captured in atlantic and pacific waters is consistent with the migration of this specimen via gibraltar.
modeling category coordination: comments and complications
Authors: hampton james a.
Published: October 2005

consideration of color alone can give a misleading impression of the three approaches to category coordination: the nativist, empiricist and culturalist models. empiricist models can benefit from a wider range of correlational information in the environment. also, all three approaches may explain a set of perceptual categories within the human repertoire. finally, a suggestion is offered for supplementing the naming game by varying the social status of agents.
betrayal aversion is reasonable
Authors: koehler jonathan j. , gershoff andrew d.
Published: October 2005

we accept sunstein's claim that people often use moral heuristics to make judgments and decisions. however, in situations that include a risk of betrayal, we disagree with sunstein about when the relevant moral heuristic may be said to “misfire.” we suggest that the moral heuristic people apply to avoid the possibility of safety-product betrayal may be reasonable.
it takes a(n) (agent-based) village
Authors: satterfield teresa
Published: October 2005

steels & belpaeme (s&b) take technical and conceptual shortcuts that have significant negative consequences on simulation implementation and agent behavior. justifiably, their model represents a proof of concept of the role of culturalism in category formation; nevertheless, the absence of detailed information concerning the embodiment of agents and the superficial implementation of learning approaches make their results less relevant than they could be.
asymmetrical behavior without an asymmetrical brain: corpus callosum and neuroplasticity
Authors: miu andrei c.
Published: October 2005

the theory put forward by vallortigara & rogers (v&r) to explain the versatility of directional asymmetries at the population level argues that the strength of lateralization is controlled by social learning. this shaping of behavioral asymmetries by a non-stationary pressure probably involves a marked degree of neuroplasticity. i discuss the limits of neuroplasticity along with the evolution of the corpus callosum.
a categorial mutation
Authors: vilarroya oscar
Published: October 2005

the proposal of steels & belpaeme (s&b) is on the right track to solve the nativist/empiricist/culturalist controversy. however, their nativist model of colour categorization does not correspond to a proper genetic model. colour perception is the outcome of a complex process of development. a direct correspondence between genes and colour categories cannot be the right approach to the problem.