bluuebunny/crossref_metadata_2025 huggingface dataset:
Navier—stokes computations of hypersonic flows
Authors: Hillier R. , Kirk D. , Soltani S.
Published: September 2004

The current interest in hypersonic flows is leading to significant
effort both to develop CFD methods and also to provide experimental
data for their evaluation. In our research we attempt to integrateCFD
and experiments as closely as possible so much so that most of our
experimental model designs are based upon preliminary flow field computations
in order to identify likely regions of importance and distribute
instrumentation as efficiently as possible. The experiments must also have
the CFD requirements clearly in mind. In particular we consider it
important to separate evaluation on the numerics (essentially
the algorithm) from modelling of the physics (which
includes the uncertainties of turbulence modelling) to this end our
experiments include laminar studies, for both attached and separated flows,
for which the physical equations are known exactly, as well as turbulent flow
studies. This paper concentrates mainly on our CFD efforts and
presents details of a high resolution solver for viscous flows together with
their predictions for a range of problems which are the subject of our
current and planned experiments.
An evaluation of iterative methods in the solution of a convection—diffusion problem
Authors: Feng Y.T. , Huang G.J. , Owen D. R. J. , Perić D.
Published: September 2004

In this paper we investigate the performance of CGS, BCGSTAB and GMRES with ILU preconditioner for solving convection‐diffusion problems. Numerical experiments indicate that BCGSTAB appears to be an
efficient and stable method. CGS sometimes suffers from severe numerical instability. GMRES shows a higher suitability and stability but the overall convergence rate may be lower.
Linear stability analysis of thermocapillary convection in
liquid bridges using a mixed finite difference‐spectral
method
Authors: Chen J.–C. , Sheu S.–S.
Published: September 2004

A linear stability analysis has been employed to
investigate the thermocapillary instability occurring in a
nonisothermal liquid bridge. The steady, axisymmetric basic
state was solved numerically using a finite difference method. A
mixed finite difference‐spectral method, combining the
advantages of both methods, was then used to reduce the linear
disturbance equations to an eigenvalue problem. The critical
Marangoni numbers for axisymmetric disturbances are predicted
for small Prandtl numbers and various aspect ratios. The effect
of surface heat transfer is also investigated. The present
results are compared with energy‐theory results and with the
results of other experiments.
On computation of two and three‐dimensional unsteady thermal
non‐newtonian flows
Authors: Ding D. , Townsend P. , Webster M.F.
Published: September 2004

In this article we report on progress in the development of software
tools for fluid flow prediction in the polymer processing industry. This
involves state‐of‐the‐art numerical techniques and the
study of a number of non‐trivial model flow problems, in an effort to
investigate realistic transient problems relevant to industrial processes.
Here we study particularly the effects of variations in non‐Newtonian
and heat transfer properties of the flowing materials in the flows, both
throughout the transient development period and at
steady‐state.
Predictions of unsteady flame spread and burning processes
by the vorticity‐stream function formulation of the compressible
navier‐stokes equations
Authors: Di Blasi Colomba
Published: September 2004

A two‐dimensional mathematical model of flame spread and
solid burning is presented. For the gas phase, it consists of
variable density, fully elliptic Navier‐Stokes momentum, energy
and chemical species mass equations. Combustion processes are
treated according to a one‐step, finite‐rate, reaction. The
solid phase model describes a porous cellulosic fuel for a range
of thicknesses from the thermally thin to the thermally thick
limit. Conductive and convective heat transfer takes place as
the solid degrades, by two first order Arrhenius reactions, to
volatiles and chars. Variations of solid phase densities account
for fuel burn‐out. Effects of gas phase and surface radiation
are also included. A steady formulation of gas phase equations
with respect to the unsteady solid phase mathematical model is
proposed, gas phase characteristic times being much shorter than
those of the solid phase. The non‐constant density Navier‐Stokes
equations are formulated in terms of vorticity and stream
function, avoiding the pressure‐velocity coupling and, at the
same time, the adoption of a sample‐fixed coordinate system
allows unsteady flame spread processes to be simulated. The
solution is computed numerically by means of an iterative,
operator‐splitting method based on implicit finite‐difference
approximations. Numerical simulations of the dynamics of flame
spread over cellulosic solids are presented and extinction
limits as a consequence of reduced rates of fuel generation are
determined.
A simultaneous iteration procedure for the finite element solution of
the enthalpy model for phase change heat conduction problems
Authors: Gong Zhen‐Xiang , Mujumdar Arun S.
Published: September 2004

Based on a lumped mass model and an incremental iteration method, an
efficient simultaneous iteration procedure is developed for the finite
element solution of the enthalpy model. This procedure uses Gauss elimination
to solve the resulting algebraic equation system. A one‐point quadrature
program based on the isoparametric quadrilateral element is incorporated for
the calculation of the heat conductance matrix, leading to a significant
reduction of the computation time.
Convective heat transfer in an annular fluid layer with centrifugal
force field
Authors: Aboubi K. , Robillard L. , Bilgen E. , Vasseur P.
Published: September 2004

The present study deals with two‐dimensional convective motion due to
the effect of a centrifugal force field on a fluid contained between two
horizontal concentric cylinders, for the particular case of an adiabatic
inner boundary (zero heat flux) and a constant heat flux imposed on the outer
boundary. The normal terrestrial gravity is considered negligible. Governing
equations for a two‐dimensional flow field are solved using analytical and
numerical techniques. Based on a concentric flow approximation, the
analytical solution is obtained in terms of the Rayleigh number and the
radius ratio. The numerical solution is based on a finite difference method.
Results indicate that the flow field always consists of two symmetrical cells
at incipient convection even at radius ratios near unity. A good agreement is
found between the analytical and numerical solutions at finite amplitude
convection.
Effects of variable property and surface radiation on laminar natural
convection in a square enclosure
Authors: Sen Swarnendu , Sarkar A.
Published: September 2004

The interaction of variable property convection and surface radiation in
a differentially heated square cavity is considered. Effect of surface
radiation on natural convection has been studied from the point of view of
flow structure and isotherm patterns. Wherever possible, a comparative study
has been invoked between the outcome of the present work and the constant
property formulation. The finite element method has been used in the present
work and associated formulation schemes have been described in
detail.
Transport of a condensable species in nonisothermal tube flow
Authors: Kag Kim Young , Soo Kim Sang
Published: September 2004

We present the equations for condensation in cooled upward laminar flow
in tubes and consider their solution for low vapour concentrations and
variable vapour‐gas thermodynamic properties. We treated the full problem,
including coupling with the aerosol size distribution, by using the PSI‐CELL
(Particle Source in Cell) method. The particle trajectories start from the
point where the particles are generated homogeneous nucleation. Particle size
distribution and vapour scavenging by particles are obtained in forced
convection and mixed convection regions. Calculations were also conducted
with respect to tube diameters.
Fast fourier transform of spectral boundary elements for transient heat
conduction
Authors: Hill L.R. , Farris T.N.
Published: September 2004

The spectral boundary element method for solving two‐dimensional
transient heat conduction problems is developed. This method is combined with
the fast Fourier transform (FFT) to convert the solution between the time and
frequency domains. The fundamental solutions in the frequency domain,
required for the present method, are discussed. The resulting line
integrations in the frequency domain are discretized using constant boundary
elements and used in a Fortran boundary element program. Three examples are
used to illustrate the accuracy and effectiveness of the method in both the
frequency and time domains. First, the frequency domain solution procedure
is verified using the steady‐state example of a semi‐infinite half space with
a heat flux applied to a patch of the surface. This spectral boundary element
method is then applied to the problem of a circular hole in an infinite solid
subjected to a time‐varying heat flux, and solutions in both the frequency
and time domains are presented. Finally, the method is used to solve the
circular hole problem with a convection boundary condition. The accurary of
these results leads to the conclusion that the spectral boundary element
method in conjunction with the FFT is a viable option for transient problems.
In addition, this spectral approach naturally produces frequence domain
information which is itself of interest.
Combined forced and free laminar convective heat transfer from a
vertical plate with coupling of discontinuous surface heating
Authors: Kishinami Koki , Saito Hakaru , Suzuki Jun
Published: September 2004

Combined free and forced laminar air convective heat transfer from a
vertical composite plate with isolated discontinuous surface heating elements
has been studied numerically and experimentally. The problem has been
simplified by neglecting heat conduction in unheated elements of the plate to
accomplish a better understanding of the complicated combined/complicated
convection problem. In this study, it is most important in explaining the
heat transfer behaviour to clarify the interactions between buoyancy and
inertia forces in the convective field and also the coupling effects of
unheated elements upon the combined flow fields. Therefore, the temperature
distributions of the wall surface and local Nusselt number, obtained by
numerical calculations and experiments, have been discussed based on the
various parameters associated with the present convection problem, i.e.,
Grashof number GrL, Reynolds number ReL, geometry factor
D/L and stage number N. Heat transfer characteristics
Nut/Re1/2L of this combined and coupled
convection of air are presented as a function of a generalized coupling
dimensionless number GrL/Re2L, and stage number
N for certain values of the geometry factor of D/L.
A spectral multidomain technique for the computation of the czochralski
melt configuration
Authors: Raspo I. , Ouazzani J. , Peyret R.
Published: September 2004

This paper presents a spectral multidomain method for solving the
Navier‐Stokes equations in the vorticity‐stream function formulation. The
algorithm is based on an extensive use of the influence matrix technique and
so leads to a direct method without any iterative process. Numerical results
concerning the Czochralski melt configuration are reported and compared with
spectral monodomain solutions to show the advantage of the domain
decomposition for such a problem which solution presents a singular
behaviour.
A preconditioner for steady two‐dimensional turbulent flow simulation
Authors: Badcock K.J. , Glover I.C. , Richards B.E.
Published: September 2004

The approximate factorisation‐conjugate gradient squared (AF‐CGS) method
has been successfully demonstrated for unsteady turbulent aerofoil flows and
transonic inviscid flows in two and three dimensions. The method consists of
a conjugate gradient solution of the linear system at each step with the ADI
approximate factorisation as a preconditioner. In the present paper the
method is adapted to obtain rapid convergence for steady aerofoil flows when
compared to the basic explicit method. Modifications to the original method
are described, convergence criteria are examined and the method is
demonstrated for transonic flow including AGARD test case 9 for the RAE2822
aerofoil.
Numerical study of grey‐body surface radiation coupled with fluid flow
for general geometries using a finite volume multigrid solver
Authors: Kadinski L. , Perić M.
Published: September 2004

The paper presents a numerical technique for the simulation of the
effects of grey‐diffusive surface radiation on fluid flow using a finite
volume procedure for two‐dimensional (plane and axi‐symmetric) geometries.
The governing equations are solved sequentially, and the non‐linearities and
coupling of variables are accounted for through outer iterations
(coefficients updates). In order to reduce the number of outer iterations, a
multigrid algorithm was implemented. The radiating surface model assumes a
non‐participating medium, semi‐transparent walls and constant elementary
surface temperature and radiation fluxes. The calculation of view factors is
based on the analytical evaluation for the plane geometry and numerical
integration for axi‐symmetric geometry. Ashadowing algorithm was implemented
for the calculation of view factors in general geometries. The method for
the calculation of view factors was first tested by comparison with available
analytical solutions for a complex geometric configuration. The flow
prediction code combined with radiation heat transfer was verified by
comparisons with analytical one‐dimensional solutions. Further test
calculations were done for the flow and heat transfer in a cavity with a
radiating submerged body. As an example of the capabilities of the method,
transport processes in metalorganic chemical vapour deposition (MOCVD)
reactors were simulated.
Computation of isothermal and reacting Flows in turbojet
afterburners
Authors: Ravichandran M. , Ganesan V.
Published: September 2004

Computation have been made of the three‐dimensional flow field
development, chemical reaction and combustion processes in a typical
afterburner system under both isothermal and reacting flow conditions. The
calculations are based upon a numerical solution of the time‐averaged
transport equations for mass, momentum, turbulence kinetic energy,
dissipation rate, enthalpy and species concentrations using a finite‐volume
formulation. The physical models include the k—ε turbulence model, the
eddy break‐up model, a two‐step reaction model, a droplet vaporization and
combustion model and six‐flux radiation model. The mean flow structures are
presented in important longitudinal and cross‐sectional planes which show
certain striking similarities and contrasting differences for isothermal and
reacting flows. The flame stabilizer flow is shown to be dominated by a
complex combination of recirculation and vortex patterns. Combustion alters
convergence and mixing flow patterns downstream of the flame stabilizer, thus
influencing the selection of the fuel injection system. The predicted
reacting flow parameters identify a number of design parameters such as fuel
injector location, high degree reaction zone, nozzle opening area and the
corresponding fuel flow rate.
Axisymmetric laser welding of ceramic and metallic materials: finite
element modelling
Authors: Thomazin J.A. , Olson L.G. , Hirsch J.W.
Published: September 2004

In this paper, finite element techniques are used to model laser spot
welding of both metallic and ceramic materials. The materials modelled were
aluminum and alumina, a typical ceramic. In the formulation, the steady state
mass, momentum, and energy conservation equations are considered with surface
tension and buoyancy forces driving the fluid flow. The results indicate that
fluid flow must be considered in order to accurately model molten pool
characteristics for ceramics since the coupling of fluid flow to heat flow is
more important for ceramics than for metals.
Non‐local and local artificial boundary conditions for two‐dimensional
flow in an infinite channel
Authors: Patlashenko Igor , Givoli Dan
Published: September 2004

The numerical solution of problems involving two‐dimensional flow in an
infinite or a semi‐infinite channel is considered. Beyond a certain finite
region, where the flow and geometry may be general, a “tail” region is
assumed where the flow is potential and the channel is uniform. This
situation is typical in many cases of fluid‐structure interaction and flow
around obstacles in a channel. The unbounded domain is truncated by means of
an artificial boundary B, which separates between the finite computational
domain and the “tail.” On B, special boundary conditions are devised. In the
finite computational domain, the problem is solved using a finite element
scheme. Both non‐local and local artificial boundary conditions are
considered on B, and their performance is compared via numerical
examples.
The application of split‐coefficient matrix method to transient two
phase flows
Authors: Lu D.M. , Simpson H.C. , Gilchrist A.
Published: September 2004

An easy‐to‐use numerical model for transient two‐phase pipe flow
analyses was developed by applying the split‐coefficient matrix method (SCMM)
to a homogeneous equilibrium two‐phase flow model. The basic idea of the SCMM
is to split the Jacobian coefficient matrix into two sub‐vectors, each
associated with eigenvalues of the same sign. Hence, one‐sided finite
difference schemes can accordingly be applied to the sub‐vectors. The present
model was validated against experiments. It is numerically stable provided
that a criterion is met due to the use of a time explicit format. The
satisfactory agreement between the numerical and experimental results
indicates that the model may be used as a simple, efficient tool for general
engineering analyses of transient two‐phase flow. The advantages of applying
SCMM to transient two phase flows are briefly addressed, and it is applicable
to systems having real eigenvalues.
Conjugate heat transfer analysis of fluid flow in a phase‐change energy
storage unit
Authors: Li Hongjun , Hsieh C.K. , Goswami D.Y.
Published: September 2004

A method has been developed for conjugate heat transfer analysis of
fluid flow inside parallel channels formed by a phase change material (PCM)
separated from the fluid by a wall. The phase change in the PCM is two
dimensional and a hybrid analysis consisting of an analytical solution in one
direction and a finite‐difference method in another direction is used to
solve for the temperature in the PCM. The heat transfer fluid (HTF) inlet
temperature is given and the heat transfer between the HTF and the PCM is
treated as a conjugate problem that requires no iterations to obtain a
solution. The numerical results are found to be stable, convergent, and
accurate. Application of the method to the solution of heat extraction from a
phase‐change energy storage unit is given in detail and the numerical results
are shown to be accurate, based on an energy conservation analysis, to within
3%.
Mould filling simulation using finite elements
Authors: Codina R. , Schäfer U. , Oñate E.
Published: September 2004

In this paper we consider several aspects related to the application of
the pseudo‐concentration techniques to the simulation of mould filling
processes. We discuss, in particular, the smoothing of the front when finite
elements with interior nodes are employed and the evacuation of air through
the introduction of temporary free wall nodes. The basic numerical techniques
to solve the incompressible Navier—Stokes equations are also briefly
described. The main features of the numerical model are the use of
div‐stable velocity—pressure interpolations with discontinuous
pressures, the elimination of the pressure via an iterative penalty
formulation, the use of the SUPG approach to deal with
convection‐dominated problems and the temporal integration using the
generalized trapezoidal rule. At the end of the paper we present some
numerical results obtained for a two‐dimensional test problem showing
the ability of the method to capture complicated flow patterns.
A complementary volume approach for modelling three‐dimensional
Navier—Stokes equations using dual delaunay/voronoi
tessellations
Authors: Cavendish J.C. , Hall C.A. , Porsching T.A.
Published: September 2004

We describe a new mathematical approach for deriving and solving
covolume models of the three‐dimensional, incompressible
Navier—Stokes flow equations. The approach integrates three technical
components into a single modelling algorothm: automatic grid generation;
covolume equation generation; dual variable reduction.
HF chemical laser analysis of twin plane jets via a kinetic theory
approach
Authors: Chuang Shu‐Hao , Hong Zuu‐Chang
Published: September 2004

Solutions of the twin plane jets HF chemical laser flow based on a
turbulent kinetic theory, due to a modified Green’s function method, are
presented. The calculated results of probability density function
(PDF) of various chemical species in velocity space, and mass
fraction concentration distributions of various reactants and products in the
flow field, are revealed and discussed in this analysis. The transport
phenomena of different pumping rate, collisional deactivation rate, and
radiative deactivation rate in the interaction between the twin plane jets HF
chemical laser show that the properties of species mass fraction
concentrations, collisional reaction rate, and radiative incident intensity
are the dominant factors. The present study provides the fundamentals for
theoretical understanding of twin plane jets HF chemical laser and further
application to multiple‐jet HF chemical laser analysis.
The efficient solution of fluid dynamics problems by the combination
technique
Authors: Griebel Michael , Thurner Veronika
Published: September 2004

We study the sparse grid combination technique as an efficient method
for the solution of fluid dynamics problems. The combination technique needs
only
O(h–1n(log(h–1n))d–1)
grid points for d‐dimensional problems, instead of
O(h–dn) grid points used by the full grid method.
Here, hn = 2–n denotes the mesh width of the grids.
Furthermore, provided that the solution is sufficiently smooth, the accuracy
(with respect to the L2‐ and the
L∞‐norm) of the sparse grid combination solution
is
O(hαn(log(h–1n))d–1),
which is only slightly worse than O(hαn)
obtained by the full grid solution. Here, α includes the order of the
underlying discretization scheme, as well as the influence of singularities.
Thus, the combination technique is very economic on both storage requirements
and computing time, but achieves almost the same accuracy as the usual full
grid solution. Another advantage of the combination technique is that only
simple data structures are necessary. Where other sparse grid methods need
hierarchical data structures and thus specially designed solvers, the
combination method handles merely d‐dimensional arrays. Thus,
the implementation of the combination technique can be based on any “black
box solver”. However, for reasons of efficiency, an appropriate multigrid
solver should be used. Often, fluid dynamics problems have to be solved on
rather complex domains. A common approach is to divide the domain into
blocks, in order to facilitate the handling of the problem. We show that the
combination technique works on such blockstructured grids as well. When
dealing with complicated domains, it is often desirable to grade a grid
around a singularity. Graded grids are also supported by the combination
technique. Finally, we present the first results of numerical experiments
for the application of the combination method to CFD problems. There,
we consider two‐dimensional laminar flow problems with moderate
Reynolds numbers, and discuss the advantages of the combination
method.
Convective heat transfer in axisymmetric porous bodies
Authors: Rajamani Rajesh , Srinivas C. , Nithiarasu P. , Seetharamu K.N.
Published: September 2004

A finite element method employing Galerkin’s approach is developed to
analyze free convection heat transfer in axisymmetric fluid saturated porous
bodies. The method is used to study the effect of aspect ratio and radius
ratio on Nusselt number in the case of a proous cylindrical annulus. Two
cases of isothermal and convective boundary conditions are considered. The
Nusselt number is always found to increase with radius ratio and Rayleigh
number. It exhibits a maximum when the aspect ratio is around unity; maximum
shifts towards lesser aspect ratios as Rayleigh number increases. Results are
compared with those in the literature, wherever available, and the agreement
is found to be good.
Plant closures in multiplant manufacturing firms: adding an international perspective
Authors: Richbell S.M. , Watts H.D.
Published: September 2004

Multinational firms sometimes have to choose between plants in different countries when selecting a plant for closure. This kind of decision is particularly characteristic of firms operating plants in the same industry but in different EU countries. An examination of a number of cross‐boundary closures in the EU illustrates the dominant role of plant economies of scale in encouraging the concentration of production on the largest pre‐existing site. National differences in labour characteristics can also be important. In making such closure decisions, managers need to be aware that they may be accused of misusing government subsidies, playing one group of workers or government against another group of workers and government, misjudging the political context of the environment in which the closed plant is set and, where the firms have their head offices in Europe, favouring their home country. Strategies are suggested for countering
The Student‐Centered Electronic Teaching Library: A New Model for Learning
Authors: Adalian Paul T. , Hoffman Irene M. , Rockman Ilene F. , Swanson Judy
Published: September 2004

As libraries are renovated, retrofitted, or re‐engineered to accom‐ modate robust infrastructures with scaleable Ethernet connectivity, reference personnel must actively help in the design of teaching and learning facilities supportive of technologies that add value and context to the educational experience. In this article, the authors describe the conceptualization, funding mechanisms, and creation of a Student‐centered Electronic Teaching classroom (SET) in a medium‐sized academic library. The SET is viewed as a combination of several elements: electronic classroom, information concourse, and multimedia laboratory. It is designed to foster collaborative learning among students and faculty, while teaching library users specific techniques to increase their information competency abilities.
Who Delivers? Partisan Clients in the Argentine Electoral Market
Authors: Calvo Ernesto , Murillo Maria Victoria
Published: September 2004

Why do some parties fail to benefit from patronage in pork‐ridden political systems? This article analyzes the interaction between patronage and partisanship to explain why some incumbents are more likely to benefit from pork politics than others. We explain such differences by focusing on political parties' access to resources (supply side) and voters' dependence on fiscal largesse (demand side). We show how these differences affect the patron's choice of public sector wages and employment. We use subnational level data to show different electoral returns from patronage for the two major political coalitions in Argentina—Peronism and the UCR‐Alianza—and their effect on preferences over public sector wages and employment.
Why Democracies May Actually Be Less Reliable Allies
Authors: Gartzke Erik , Gleditsch Kristian Skrede
Published: September 2004

Recent research builds on the observation that democracies have more durable alliances to argue that democracies make more reliable allies. This need not be the case. Alliances serve as commitment devices, adding ex ante credibility to states' claims about ex post behavior. Variation in alliance durability must reflect differences in the desirability of formalizing alignments. Put simply, democracies are “most improved” by formal commitments. We offer two related explanations for why democracies might actually be less reliable alliance partners. Information costs for participating in policymaking and the advantages of organized interest groups combined with distributional incentives generated by the periodic turnover of governments may conspire to make informal commitments on the part of democracies problematic. Determining the net effect of democratic virtue and vice is best done empirically. We test alliance reliability by focusing on intervention, rather than on the duration or the number of commitments. Our results suggest that democracies make less reliable allies.
The Impact of Income on the Taste for Revolt
Authors: MacCulloch Robert
Published: September 2004

The question of how the level of development affects revolutionary support in society is of fundamental importance. One approach to provide an answer has been to study the relationship between actual civil conflict and income at the national level. This article takes a different approach. It uses microdata sets based on surveys of revolutionary support across one‐quarter of a million people and identifies how the responses vary with their incomes. We find that a rise in GDP of $US 1,600 per capita in 2001 values decreases the chances of supporting revolt by 2.4 percentage points which represents a 41% drop in the proportion of people wanting a revolution. For a person who jumps from the bottom to top income quartile within their country, the probability declines by a similar amount. The results are robust to controlling for country and year effects, country‐specific time trends and take account of the potential endogeneity of GDP.
Measuring Ethnic Fractionalization in Africa
Authors: Posner Daniel N.
Published: September 2004

In most studies of the impact of ethnic diversity on economic growth, diversity is hypothesized to affect growth through its effect on macroeconomic policies. This article shows that most measures of ethnic diversity (including the commonly used ELF measure) are inappropriate for testing this hypothesis. This is because they are constructed from enumerations of ethnic groups that include all of the ethnographically distinct groups in a country irrespective of whether or not they engage in the political competition whose effects on macroeconomic policymaking are being tested. I present a new index of ethnic fractionalization based on an accounting of politically relevant ethnic groups in 42 African countries. I employ this measure (called PREG, for Politically Relevant Ethnic Groups) to replicate Easterly and Levine's influential article on Africa's “growth tragedy.” I find that PREG does a much better job of accounting for the policy‐mediated effects of ethnic diversity on economic growth in Africa than does ELF.
The spatiotemporal characterization of endplate reoccupation, with special reference to the superposition patterns of the presynaptic elements and the postsynaptic receptor regions during muscle reinnervation
Authors: Wang Songyan , Kawabuchi Masaru , Zhou Chong Jian , Hirata Kazuho , Tan Huibing , Kuraoka Akio
Published: September 2004

Abstract  In this study, an immunohistochemical investigation was carried out to define spatiotemporal characteristics of superposition patterns of the presynaptic elements and the postsynaptic acetylcholine receptor (AChR) sites during the period of endplate regeneration after sciatic nerve crush. The extent of close correspondence of terminal Schwann cell (TSC)‐, or axon terminal‐, apposing AChR sites was quantitated with three‐dimensional images of neuromuscular junctions (NMJs) taken under confocal laser‐scanning microscopy. After 3‐weeks post‐crush (wpc), reoccupation of regenerating TSCs and later arriving axon terminals proceeded within the scope of previously denervated AChR plaques. During this period, the areas of presynaptic elements and the areas of postsynaptic elements were highly correlated. TSCs rapidly reoccupied a greater part of the postsynaptic receptors. In contrast, there was a slower increase of the contact areas of AChR sites overlapped by the axon terminals. Reoccupation by the presynaptic elements at 20 wpc was almost completed in a majority of NMJs, but some anomalous changes still continued to occur in a small proportion of the NMJs (20–30%). Our results suggest that: (a) with gradual increase of the contact areas between presynaptic and postsynaptic elements, imperfect reinnervation and regeneration, due to spatial mismatching or unbalanced growth between presynaptic and postsynaptic elements, result in sporadic remodeling; (b) the difference in superposition patterns between TSCs and axon terminals depends on the ability of making alignment to the endplate gutters in regenerating NMJs; and (c) a complex set of anatomical relationships among the three endplate components affects the process of endplate reoccupation synthetically.
Neuropathy and cognitive impairment following vaccination with the OspA protein of Borrelia burgdorferi
Authors: Latov Norman , Wu Anita T. , Chin Russell L. , Sander Howard W. , Alaedini Armin , Brannagan Thomas H.
Published: September 2004

Abstract  Neurological syndromes that follow vaccination or infection are often attributed to autoimmune mechanisms. We report six patients who developed neuropathy or cognitive impairment, within several days to 2 months, following vaccination with the OspA antigen of Borrelia burgdorferi. Two of the patients developed cognitive impairment, one chronic inflammatory demyelinating polyneuropathy (CIDP), one multifocal motor neuropathy, one both cognitive impairment and CIDP, and one cognitive impairment and sensory axonal neuropathy. The patients with cognitive impairment had T2 hyperintense white matter lesions on magnetic resonance imaging. The similarity between the neurological sequelae observed in the OspA‐vaccinated patients and those with chronic Lyme disease suggests a possible role for immune mechanisms in some of the manifestations of chronic Lyme disease that are resistant to antibiotic treatment.
A very large Schwannoma originating from the median nerve in carpal tunnel
Authors: Gündes Hakan , Tosun Bilgehan , Müezzinoglu Bahar , Alici Tugrul
Published: September 2004

Abstract  Schwannomas are common benign nerve tumors occurring in the peripheral nerves. A very large schwannoma of more than 5 years duration, originating from the median nerve in the carpal tunnel in a 38‐year‐old woman, is reported. There was a painful mass, 60 mm in length and 42 mm in diameter, on the palm without signs of sensory disturbance or atrophy on the thenar muscles. Surgical removal was performed under high‐power magnification by separating the sensory and motor fascicles from the tumor. Histological examination resulted in a Schwannoma. At 4‐year follow‐up, the patient was asymptomatic with excellent relief of symptoms. The tumor did not recur. Although cases have been reported in the literature, this is one of the largest ever described without any neurologic deficit.
Carpal tunnel syndrome in elderly patients: results of surgical decompression
Authors: Mondelli Mauro , Padua Luca , Reale Fabio
Published: September 2004

Abstract  This study prospectively compared preoperative and postoperative (6 months after surgical release) clinical and electrophysiological evaluation and self‐administered Boston questionnaire (BQ) findings of a series of elderly carpal tunnel syndrome (CTS) patients with those of young and adult patients. Three hundred twenty three consecutive hands (282 patients) underwent surgery between 1997 and 2000. Patients were divided into four age groups: group 1 (20–40 years), 49 hands; group 2 (41–54 years), 96 hands; group 3 (55–69 years), 106 hands; and group 4 (70–90 years), 72 hands. Sex ratio, education, duration and bilaterality of CTS, history of wrist and hand trauma, connective tissue and thyroid diseases, diabetes, polyneuropathy, renal failure, and other nerve entrapment syndromes were recorded. The elderly group (group 4) only had more cases of diabetes than groups 1 and 2 (young and adult patients). Before surgery, elderly patients showed more severe clinical objective and electrophysiological findings than young and adult patients. Preoperative subjective findings (BQ scores) were similar in all four groups. Although their absolute postoperative BQ scores and clinical objective and electrophysiological stages improved, elderly patients showed less improvement in all findings than the 20–54 age groups, presumably due to greater preoperative damage and less repair capacity of the compressed nerve. This, however, is not a contraindication for surgical release in elderly patients.
Nerve conduction abnormalities in the trembler‐j mouse: A model for Charcot‐Marie‐Tooth disease type 1A?
Authors: Meekins Gregg D. , Emery Michael J. , Weiss Michael D.
Published: September 2004

Abstract  The trembler‐j mouse is a spontaneously occurring, demyelinating mutant secondary to a point mutation involving a leucine for proline substitution in the first transmembrane domain of the peripheral‐myelin protein‐22 (PMP‐22) gene. It is considered to be a model for Charcot‐Marie‐Tooth disease type 1A (CMT1A), largely based upon pathologic observations. However, functional studies demonstrating homology with CMT1A patients have not been documented. Sciatic nerve conduction was performed on 30 and 72‐day‐old wildtype and trembler‐j mice in a blinded fashion. The findings in the mutants in both age groups were consistent with profound demyelination. Trembler‐j mice appear to have a greater degree of motor nerve conduction slowing relative to human studies involving patients with PMP‐22 gene duplication. Functionally, the trembler‐j is a good murine model for CMT1A associated with an identical point mutation but may represent a more severe disease phenotype than CMT1A secondary to PMP‐22 gene duplication.
Role of insulin‐like growth factor‐I in the treatment of painful small fiber predominant neuropathy
Authors: Windebank Anthony J. , Sorenson Eric J. , Civil Richard , O'Brien Peter C.
Published: September 2004

Abstract  Idiopathic, painful, small fiber predominant peripheral neuropathy is resistant to symptomatic treatment. Previous treatments have not been directed toward repairing the underlying deficit. Growth factors hold promise as agents to encourage axonal regrowth. In vitro, insulin‐like growth factor‐I (IGF‐I) has been shown to prevent neuronal apoptosis, to increase axonal growth, and to support myelination. Using a double‐blind, placebo‐controlled design, 40 patients were randomized to treatment with recombinant human IGF‐I (0.05 mg/kg twice daily by subcutaneous injection) or placebo for 6 months. There were no significant adverse events and minor adverse events occurred equally in both groups. The primary outcome measure was change in score on an analog pain scale. Secondary endpoints included quantitative sensory testing, quantitative autonomic testing, neuropathy impairment score, nerve conduction studies, and neuropathy symptom and change score. There was no significant difference in the primary endpoint between the two groups. Analysis of secondary endpoints and a global impression of improvement by patients and physicians did not show consistent differences between the groups. IGF‐I was safe, but did not improve symptoms in this 6‐month trial.
Radiation synovectomy by188Re‐Sulfide in haemophilic synovitis
Authors: Li P. , Chen G. , Zhang H. , Shen Z.
Published: September 2004

Summary. Radiation synovectomy is a safe and effective treatment for chronic haemophilic synovitis causing recurrent haemarthroses. This study reports results of 29188Re‐sulfide radiation synovectomies in knee joint with a follow‐up 18 months. Using the absorbed dose factor, three groups of radioactivity dose (555 MBq, 687 MBq and 917 MBq) were used according to the synovium thickness that measured by MRI. Excellent and good results (haemarthrosis reduction from 75 to 100%) were obtained in 71% of cases at 18 months. Comparison of the results, no significant difference was found among the radioactivity dose groups. Radiation was well contained within the knee. There were no observed or identified complications including the detectable harm to the articular cartilage, as shown by MRI.
Haemostatic management of intraoral bleeding in patients with congenital deficiency of α2‐plasmin inhibitor or plasminogen activator inhibitor‐1
Authors: Morimoto Y. , Yoshioka A. , Imai Y. , Takahashi Y. , Minowa H. , Kirita T.
Published: September 2004

Summary.  Haemostatic management of intraoral bleeding was investigated in patients with congenital α2‐plasmin inhibitor (α2‐PI) deficiency or congenital plasminogen activator inhibitor‐ 1 (PAI‐1) deficiency. When extracting teeth from patients with congenital α2‐PI deficiency, we advocate that 7.5–10 mg kg−1 of tranexamic acid be administered orally every 6 h, starting 3 h before surgery and continuing for about 7 days. For the treatment of continuous bleeding, such as post‐extraction bleeding, 20 mg kg−1 of tranexamic acid should be administered intravenously, and after achieving local haemostasis 7.5 mg kg−1 of tranexamic acid should be administered orally every 6 h for several days. In addition, when treating haematoma caused by labial or gingival laceration or buccal or mandibular contusion, haemostasis should be achieved by administering 7.5–10 mg kg−1 of tranexamic acid every 6 h. Tranexamic acid can also be used for haemostatic management of intraoral bleeding in patients with congenital PAI‐1 deficiency, but is less effective when compared with use in patients with congenital α2‐PI deficiency. Continuous infusion of 1.5 mg kg−1 h−1 of tranexamic acid is necessary for impacted tooth extraction requiring gingival incision or removal of local bone.
Endometrial ablation for von Willebrand disease‐related menorrhagia – experience with seven cases
Authors: Rubin G. , Wortman M. , Kouides P. A.
Published: September 2004

Summary.  Background:  Endometrial ablation has recently gained popularity as a treatment of menorrhagia in the general population. In the von Willebrand disease (VWD) patient, intuitively, it would appear that the failure rate would be higher because of the underlying hypocoaguability increasing the likelihood for re‐bleeding. In a consecutive series of seven patients, we assessed the efficacy and safety of endometrial ablation in VWD‐related menorrhagia.

Patients and methods:  We performed a retrospective analysis using chart review and a 21‐item questionnaire administered to seven (six type 1, one type 2A) women who underwent endometrial ablation between the years 1997 and 2001. Parameters assessed included operative complications, the development of abdominal pains, recurrence of menstrual bleeding post‐ablation and the change in the pre‐/post‐ablation quality of life (QOL). Three patients underwent endomyometrial resection and one each underwent rollerball, thermal, electrocautery and balloon ablation. All patients were pre‐treated with i.v. desmopressin (DDAVP) except the 2A patient who received Humate P. Mean age of the patient was 41 ± 6 years and follow‐up was for 45 months (range 31–73) post‐ablation.

Results:  No significant perioperative bleeding complications were observed in any of the patients. All patients initially responded (two amenorrhoea, four hypomenorrhoea, one moderate improvement). In all patients, QOL assessed by 10 parameters improved significantly following the ablation procedure, regardless of the specific technique used. However, at the end of follow‐up, only one patient remained amenorrheic, one was hypomenorrheic, one had moderate improvement and four patients experienced recurrence of menorrhagia, three eventually requiring a hysterectomy at a median of 11 months post‐ablation.

Conclusion:  Endometrial ablation appears to be a safe procedure that improves the QOL in patients with VWD‐related menorrhagia. However, its long‐term efficacy appears to be lower in VWD patients when compared with women with menorrhagia without VWD.
Liver biopsy in patients with inherited disorders of coagulation and chronic hepatitis C
Authors: Theodore D. , Fried M. W. , Kleiner D. E. , Kroner B. L. , Goedert J. J. , Eyster M. E. , Faust S. P. , Sherman K. E. , Kessler C. M. , Francis C. , Aledort L. M.
Published: September 2004

Summary.  Liver biopsy plays a pivotal role in the management of patients with a variety of liver diseases, including chronic hepatitis C virus. The major risk of the procedure is the potential for significant haemorrhagic complications. Although the data are limited, the procedure does not appear to pose excessive risk to the patient with inherited disorders of coagulation, provided that adequate haemostasis can be achieved prior to the liver biopsy. This requires close coordination of care between the hepatologist and the haematologist. Indications for liver biopsy should be the same in patients with haemophilia as in other populations.
Survival analysis of patients with haemophilia at the International Haemophilia Training Centre, Bangkok, Thailand
Authors: Chuansumrit A. , Krasaesub S. , Angchaisuksiri P. , Hathirat P. , Isarangkura P.
Published: September 2004

Summary.  Haemophiliac treatment in less developed countries is limited to locally prepared fresh frozen plasma, cryoprecipitate, cryo‐removed plasma and lyophilized products as replacement therapy. Factor concentrate is seldom used because of the high price. The present study reports the survival analysis of 164 patients comprising 138 haemophilia A and 26 haemophilia B cases from 134 families registered at the International Haemophilia Training Centre‐Bangkok, Faculty of Medicine, Ramathibodi Hospital, Mahidol University from 1971 to 2000. The duration of follow‐up ranged from 1 to 27 years and 8 months with a median of 9 years and 1 month. They received treatment on demand of bleedings, and 85 patients received additional home treatment for early bleedings. The proportion of death was 15.2%. The Kaplan–Meier survival curves revealed the median (95% CI) survival time of patients with severe and moderate degrees of 35 years and 6 months (21.4–49.7), and 38 years and 1 month (28.8–47.3), respectively. To compare the progressive achievement of haemophilia care services, the treatment period was divided into three decades: 1971–1980, 1981–1990 and 1991–2000. The patients with unaided proper walking increased from 62.8% in the first decade to 84.5% in the third decade. However, one‐third of the patients developed one to four chronic haemarthrosis determined by clinical evaluation, especially patients with severe degree. Moreover, the estimated probability of a survival time beyond 13 years of age among patients with severe degree increased from 0.85 in the first decade to 0.94 and 1 in the second and third decades, respectively. Thus, established haemophilia care, even with limited resources, has significantly decreased the risk of death and increased the survival time among patients with haemophilia.