bluuebunny/crossref_metadata_2025 huggingface dataset:
Large Eddy Simulation of a Compressible Boundary Layer
Authors: El‐Askary W. A. , Meinke M. , Schröder W.
Published: April 2003

A large eddy simulation of a compressible boundary layer is performed. To generate an appropriate inflow distribution the rescaling technique for compressible flows is discribed. In this method Morkovin's hypothesis in which the total temperature fluctuations are neglected compared with the static temperature fluctuations is applied to rescale and generate the temperature profile at inlet. This new technique is used for various large eddy simulations of subsonic and supersonic three‐dimensional boundary layers of a flat plate. Simulation results for the time‐averaged mean flow and Reynolds stresses are compared with numerical and analytical data to demonstrate the high quality of the method.
On Results' Accuracy at Two‐Dimensional Transonic Wind Tunnel Testing
Authors: Rašuo B.
Published: April 2003

The principal factors which influence the accuracy of two‐dimensional wind tunnel test results are analyzed. The influences of Reynolds number, Mach number and wall interference with reference to solid and flow blockage (blockage of wake) as well as the influence of side‐wall boundary layer control are analyzed.
Large‐eddy simulation of compressible rectangular duct flow
Authors: Rembold B. , Kleiser L.
Published: April 2003

Turbulent flow inside ducts differs significantly from the statistically one‐dimensional turbulent channel flow due to the additional confining lateral walls. Secondary flows in the corners are found which are known to affect the turbulence structure close to the walls. Most computations have been performed for incompressible or only slightly compressible flows and with square duct geometries (e.g. [1,2]). In the present study we address the effect of the aspect ratio on the flow structure in high subsonic rectangular duct flow using LES. Mean‐flow characteristics are analyzed and compared to square duct and channel flow data. We find good agreement with available incompressible DNS square duct data for low Mach number computations. For aspect ratios as high as five, the mean‐flow profile in the center of the longer side of the duct along the wall normal direction differs distinctively from channel flow for the present Mach 0.7 computations.
Numerical Simulation of Heat Loads in a Cryogenic H2/O2 Rocket Combustion Chamber
Authors: Haarmann T. M. , Koschel W. W.
Published: April 2003

A Finite Element solver for a coupled simulation of fluid and structure in an axisymmetric domain is presented. The method employs an explicit solution of the flow and structure variables. The computational domain of the fluid is discretised by unstructured triangles and rectangles while the sturcture domain is discretised by unstructured triangles only. For the purpose of code validation the solution of in total three test cases are shown. One test case deals with the structure only while the other two simulate heat transfer problems with a defined temperature distribution along a boundary wall and coupled conditions. Finally the code is used to simulate the heat load in a cryogenic H2/O2 rocket combustion chamber.
Towards a numerical simulation of a high temperature flow
Authors: Kolman D. , Kozel K. , Louda P. , Sopuch P.
Published: April 2003

Two mathematical models of unsteady plasma flows based on 3D finite volume methods for Navier‐Stokes equations are presented. In the first, cold jet model, the nondimensional NS equations are solved by the artificial compressibility method, and the results include time‐varying velocity fields for different Reynolds numbers. The second formulation is a compressible Stegger‐Warming flux vector splitting scheme that takes into account the non‐perfect character of the plasma fluid. Temperature and composition dependent gas properties are to be evaluated from real data.
Multiscale Considerations for Sound Generation in Low Mach Number Flows
Authors: Fortenbach Roland , Munz Claus‐Dieter
Published: April 2003

Classical approaches in aeroacoustics are mainly based on analytical solutions of the linear wave equations which are valid in the far field. The sound generation is approximated by source terms obtained from a flow simulation. This procedure designated as the ‘acoustic analogy’ was initiated in the classical work of Lighthill. In order to tackle the sound generation problem at low Mach numbers, we consider a multiple scale asymptotic analysis. As we deal with a fluid flow generating the sound itself, the asymptotic ansatz uses one time scale given by the flow convection, but two space scales due to the difference in fluid and sound velocity. The insight given by this analysis is used to obtain source terms describing the sound generation and perturbation equations for the sound propagation. Numerical results are shown for the example of a co‐rotating vortex pair.
Numerische Simulation der Ausbreitung von Umfangsmoden in axialsymmetrischen Rohren
Authors: Schönwald N. , Schemel C. , Thiele F. , Michel U.
Published: April 2003

Die Konstruktion leiser Flugzeuge gewinnt durch den ständig zunehmenden Flugverkehr und der damit einhergehenden Lärmbelastung immer mehr an Bedeutung. Eine wichtige Lärmquelle am Flugzeug, die besonders beim Start eine Rolle spielt, sind die Triebwerke. Durch die Einführung von Nebenstromtriebwerken konnte der Strahllärm der Triebwerke stark reduziert werden. Dies führte aber dazu, dass der durch den Fan verursachte tonale Lärm, der sich durch den Triebwerkseinlauf ausbreitet, zu einer wichtigen Komponente des Triebwerkslärms wurde. Für den Entwurfsprozeß bekommt die numerische Simulation der Schallausbreitung immer größere Bedeutung, da experimentelle Untersuchungen sehr aufwändig sind. Ziel ist die Simulation der Schallausbreitung von der Quelle bis ins Fernfeld mittels spezieller CAA‐Verfahren für axialsymmetrische Rohre.
On Integral Representation Formulae for Biharmonic Functions on the Ball
Authors: Burgeth Bernhard F.
Published: April 2003

Biharmonic functions are solutions of the fourth order partial differential equation ΔΔu = 0. A simple method is proposed for deriving integral representation formulae for these functions u on the n‐dimensional ball. Poisson‐type representations in the setting of Hardy Spaces are obtained for biharmonic functions subject to Dirichlet, Riquier and other boundary conditions. The approach exploits algebraic properties of a first order partial differential operator and its resolvent.
Strong elastic constraints in mechanics: a multi‐valued averaging approach
Authors: Grammel G.
Published: April 2003

The Takens equation for modeling strong elastic constraints in mechanical systems is considered. Using averaging techniques, approximation orders for “passing through resonance” problems are provided. For “thick” resonance sets, the relevance of third order resonances is shown via a multi‐valued averaging approach.
Risikoparameter für schwere Herzerkrankungen mittels Auswertung von Langzeit‐EKGs durch Methoden der nichtlinearen Zeitreihenanalyse
Authors: Bach Harriet , Lang Patrick
Published: April 2003

Bei der Untersuchung von Langzeit‐EKGs bezüglich einer Risikoabschätzung für Plötzlichen Herztod finden in jüngster Zeit neben den etablierten linearen Verfahren (z.B. Standard‐HRV‐Parameter) auch zunehmend Methoden der nichtlineare Zeitreihenanalyse ihre Anwendung. Diese Ansätze zeigen sich hierbei in der erzielten Güte der Risikovorhersage den linearen Methoden oft deutlich überlegen. Im Rahmen dieser Arbeit durchgeführte Untersuchungen zur Bestimmung der Korrelationsdimension von Langzeit‐EKGs führen zum Schluss, dass diese selbst zwar nicht im strengen Sinne bestimmbar ist, die Korrrelationssummenverläufe allerdings sehr wohl zur Risikoklassi fikation geeignet sind. Dazu werden Entscheidungskriterien bestimmt, die eine Unterteilung der Patienten in Risikound Nichtrisikopatienten ermöglichen.
Semi‐Unstructured Grids in the Laser Simulation Program LASCAD
Authors: Altmann K. , Pflaum C. , Seider D.
Published: April 2003

Automatic grid generation is very important in industrial applications. Furthermore, in several applications discretization grids are needed which provide an anisotropic refinement and an accurate approximation of the derivatives of the solution. These requirements are fulfilled by semi‐unstructured grids. In this paper, we report how semi‐unstructured grids are used in the laser simulation program LASCAD [3].
Structure Analysis of Polynomial Modules with Pommaret Bases
Authors: Seiler Werner M.
Published: April 2003

We show how Pommaret bases of submodules of free polynomial modules can be used to extract structural information like the dimension, the depth or the Castelnuovo‐Mumford regularity. In particular, we discuss the syzygy theory of Pommaret bases and its use for the construction of free resolutions.
A Normal Form for Systems of Implicit Ordinary Differential Equations
Authors: Zehetleitner Kurt , Schlacher Kurt , Kugi Andreas
Published: April 2003

This contribution deals with the application of computer algebra based methods to the analysis of dynamic systems described by implicit ordinary differential equations. This type of system defines a submanifold of a certain jet space. We solve the problem whether this submanifold admits a parametrization by an explicit system, i.e. any solution of the original system is a solution of the explicit one and vice versa. Since this approach requires the formal integrability of the implicit system, a sketch of an algorithm for the computation of the formally integrable system is presented.
Nonparametric changepoint detection for time series
Authors: Franke J. , Kroisandt G.
Published: April 2003

We consider time series which change their structure repeatedly between a finite number of states, and we discuss algorithms to detect the changepoints for two particular situations. In the first case, the observed time series is a nonparametric autoregression of order p and the autoregression function changes sometimes. Here, we use a system of neural networks to estimate the autoregression functions and to detect the changepoints. In the second case, the time series is a piecewise linear process with stable innovations, where we assume that the various processes represent different dominating local frequencies, and we use wavelet packet coefficients to detect the changepoints.
Quadrature rules for qualocation
Authors: Junges Michael , Schneider Claus
Published: April 2003

Qualocation is a method for the numerical treatment of boundary integral equations on smooth curves which was developed by Chandler, Sloan and Wendland (1988‐2000) [1,2]. They showed that the method needs symmetric J–point–quadrature rules on [0, 1] that are exact for a maximum number of 1–periodic functions

$$ G _{\alpha} (x) \ggleich \sum ^{\infty} _{k=1} k ^{-\alpha} \cos (2 \pi kx), \qquad \alpha > {1 \over {2}}. $$

The existence of 2–point–rules of that type was proven by Chandler and Sloan. For J ∈ {3, 4} such formulas have been calculated numerically in [2]. We show that the functions Gα form a Chebyshev–system on [0, 1/2] for arbitrary indices á and thus prove the existence of such quadrature rules for any J.
Performance prediction of concentrator solar cells and modules from darkI–Vcharacteristics
Authors: Antón I. , Sala G. , Heasman K. , Kern R. , Bruton T. M.
Published: April 2003

The indoor performance of concentrator solar cells and modules at operating conditions is a complex task, owing to the required illumination and temperature conditions, and even more so during extensive procedures, such as on a production line. The solution proposed throughout this paper consists of predicting the illuminationI–Vcharacteristic of the solar cells, with the darkI–Vcurve and the photogenerated current as the only input data. As well as this, the technology‐dependent components of the series resistance are obtained from the dark characteristics for quality control. Theory and experiments on several types of concentrator cell have been carried out to validate the method. The equipment to be used on a production line has been developed by IES and used by BP Solar to test up to 25 000 cells and 2000 modules for the 480 kWppower plant using the EUCLIDESTMconcentrator. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic battery model for photovoltaic applications
Authors: Guasch D. , Silvestre S.
Published: April 2003

The main purpose of this paper is to offer a useful battery model for simulation of stand‐alone photovoltaic applications. At present, many models for battery behaviour simulation are available. Owing to the complex response of this element, these models are mainly concerned with stationary working point conditions. This paper presents an enhancement of a generic battery model, achieving a dynamic battery model for photovoltaic applications. It includes the use of automatic parameter extraction techniques and the solving of numerical calculation problems. It also introduces some new concepts, such as the maximum available capacity and the level of energy. Finally, a battery state of health estimation, has been added to complete the battery behaviour description, including non‐ideal effects, such as battery capacity reduction and self‐discharging current. Copyright © 2003 John Wiley & Sons, Ltd.
Multi‐component immunoaffinity subtraction chromatography: An innovative step towards a comprehensive survey of the human plasma proteome
Authors: Pieper Rembert , Su Qin , Gatlin Christine L. , Huang Shih‐Ting , Anderson N. Leigh , Steiner Sandra
Published: April 2003

In order to discover novel protein markers indicative of disease processes or drug effects, the proteomics technology platform most commonly used consists of high resolution protein separation by two‐dimensional electrophoresis (2‐DE), mass spectrometric identification of proteins from stained gel spots and a bioinformatic data analysis process supported by statistics. This approach has been more successful in profiling proteins and their disease‐ or treatment‐related quantitative changes in tissue homogenates than in plasma samples. Plasma protein display and quantitation suffer from several disadvantages: very high abundance of a few proteins; high heterogeneity of many proteins resulting in long charge trains; crowding of 2‐DE separated protein spots in the molecular mass range between 45–80 kD and in the isoelectric point range between 4.5 and 6. Therefore, proteomic technologies are needed that address these problems and particularly allow accurate quantitation of a larger number of less abundant proteins in plasma and other body fluids. The immunoaffinity‐based protein subtraction chromatography (IASC) described here removes multiple proteins present in plasma and serum in high concentrations effectively and reproducibly. Applying IASC as an upfront plasma sample preparation process for 2‐DE, the protein spot pattern observed in gels changes dramatically and at least 350 additional lower abundance proteins are visualized. Affinity‐purified polyclonal antibodies (pAbs) are the immunoaffinity reagents used to specifically remove the abundant proteins such as albumin, immunoglobulin G, immunoglobulin A, transferrin, haptoglobin, α‐1‐antitrypsin, hemopexin, transthyretin, α‐2‐HS glycoprotein, α‐1‐acid glycoprotein, α‐2‐macroglobulin and fibrinogen from human plasma samples. To render the immunoaffinity subtraction procedure recyclable, the pAbs are immobilized and cross‐linked on chromatographic matrices. Antibody‐coupled matrices specific for one protein each can be pooled to form mixed‐bed IASC columns. We show that up to ten affinity‐bound plasma proteins with similar solubility characteristics are eluted from a mixed‐bed column in one step. This facilitates automated chromatographic processing of plasma samples in high throughput, which is desirable in proteomic disease marker discovery projects.
Use of serological proteomic methods to find biomarkers associated with breast cancer
Authors: Rui Zhao , Jian‐Guo Ji , Yuan‐Peng Tong , Hai Pu , Bing‐Gen Ru
Published: April 2003

New technologies for the detection and therapy of early stage breast cancer are urgently needed. Pathological changes in breast might be reflected in proteomic patterns in serum. A proteomic tool was used to identify proteomic patterns in serum that distinguishes neoplastic from non‐neoplastic disease within the breast. Preliminary results derived from the serum analysis from 54 unaffected women and 76 petients with breast cancer were analyzed by two‐dimensional (2‐D) electrophoresis and matrix‐assisted laser desorption/ionization‐time of flight mass spectrometry, HSP27 was found up‐regulated while14‐3‐3 sigma was down‐regulated in the serum of breast cancer patients. The two protein biomarkers were then used to classify an independent set of 104 masked serum samples. The results showed that the protein pattern on 2‐D gels can completely segregate the serum of breast cancer from non‐cancer. The discriminatory pattern correctly identified all 69 breast cancer cases in the masked set. Of the 35 cases of non‐malignant disease, 34 were recognized as non‐cancer. These findings justify a prospective population‐based assessment of proteomic technology as a screening or diagnostic tool for breast cancer in high‐risk and general populations. These two protein biomarkers could also be used as targets for further study in drug design and breast cancer therapy.
Proteins from bovine tissues and biological fluids: Defining a reference electrophoresis map for liver, kidney, muscle, plasma and red blood cells
Authors: Talamo Fabio , D'Ambrosio Chiara , Arena Simona , Del Vecchio Prisco , Ledda Luigi , Zehender Goffredo , Ferrara Lino , Scaloni Andrea
Published: April 2003

A number of high resolution two‐dimensional electrophoresis (2‐DE) reference maps for bovine tissues and biological fluids have been determined for animals in basal state. Among the 1863 distinct protein features detected in samples of liver, kidney, muscle, plasma and red blood cells, 509 species were identified and associated to 209 different genes. Difficulties in the identification were related to the poorly characterized Bos taurus genome and were solved by a combined matrix‐assisted laser desorption/ionisation‐mass spectrometry and liquid chromatography‐electrospray ionization tandem mass spectrometry approach. The experimental output allowed us to establish a 2‐DE database accessible through the World Wide Web network at the URL address (http://www.iabbam.na.cnr.it/Biochem). These reference maps may serve as a tool in future veterinary medical studies aimed at the evaluation of changes in protein repertoire for altered animal physiological conditions and infectious diseases, to the definition of molecular markers for novel diagnostic kits and vaccines, as well as the characterization of protein modifications in bovine materials following technological processes used in the food industry.
Protein targets of 1,4‐benzoquinone and 1,4‐naphthoquinone in human bronchial epithelial cells
Authors: Lamé Michael W. , Jones A. Daniel , Wilson Dennis W. , Segall Hank J.
Published: April 2003

Many aspects of the toxicity of xenobiotic compounds have been attributed to the consequences of covalent modification of specific proteins, but the nature and specificity of protein targets for classes of electrophilic toxins remain largely uncharacterized. For inhaled toxicants, the point of exposure or absorption lies with epithelial cells lining the pulmonary tree. In this study, abundant proteins in human bronchial epithelial cells that are arylated in vitro by two quinonoid compounds, 1,4‐benzoquinone (BQ) and 1,4‐naphthoquinone (NQ) have been detected using 14C‐labeled quinones and two‐dimensional gel electrophoresis. These proteins were identified using matrix assisted laser desorption/ionization mass spectrometry for tryptic mass mapping followed by sequence database searching. Corroborative identification of protein targets was obtained from the apparent isoelectric points, molecular weights, and the use of antibody probes. There were subtle differences in the protein targets of BQ and NQ, but both associated with the following abundant proteins, nucleophosmin, galectin‐1, probable protein disulfide isomerase, protein disulfide isomerase, 60 kDa heat shock protein, mitochondrial stress‐70 protein, epithelial cell marker protein, and S100‐type calcium binding protein A14. We further delineate the properties of these proteins that make them preferred targets and the evidence these adducts present for delivery of these quinones to subcellular compartments.
Mobilization of iron from cellular ferritin by ascorbic acid in neuroblastoma SK‐N‐SH cells: an EPR study
Authors: Baader S.L. , Bill E. , Trautwein A.X. , Bruchelt G. , Matzanke B.F.
Published: April 2003

The mobilization of iron from intracellular ferritin by ascorbic acid has been analysed in situ by electron paramagnetic resonance (EPR) spectroscopy. EPR enables a distinction between ferritins and other Fe3+‐binding cellular components. The ordered iron core of ferritin gives rise to a resonance signal which can be observed only at temperatures above 50 K. In the present study we clearly demonstrate that ascorbic acid is capable of mobilizing iron from ferritin in the cellular system by reduction of the ferric ion core in neuroblastoma SK‐N‐SH cells. This mechanism may open new ways in the therapy of this hardly curable tumor in stage IV, especially in combination with some cytostatic drugs.
Centriole and basal body formation during ciliogenesis revisited
Authors: Dirksen Ellen Roter
Published: April 2003

Summary— This review is concerned with the formation during ciliogenesis of centrioles and basal bodies, primarily in epithelial multiciliated cells from the developing vertebrate respiratory and reproductive tracts. During ciliated cell differentiation, in these as well as in other cell types, cilium formation is preceded by the formation of centrioles assembled from precursor structures having little resemblance to the mature organelle. The origin, composition and function of the centriole precursor structures in generating large numbers of centrioles in a short period of time during ciliogenesis is discussed. This review also focuses on the biochemistry of centrioles and basal bodies and on recent experimental evidence that DNA might be associated with these structures.
Xenopus c‐raf proto‐oncogene: cloning and expression during oogenesis and early development
Authors: Le Guellec René , Couturier Anne , Le Guellec Katherine , Paris Jeannie , Le Fur Nathalie , Philippe Michel
Published: April 2003

Summary— We have isolated and characterized a cDNA which contains the entire coding sequence of Xenopus laevis raf protein. raf mRNA is identified as a member of the class of maternal RNAs. It is already relatively abundant at the beginning of oogenesis and is stable at least until the midblastula transition. The RNA is also detected later during embryogenesis in particular in gastrula, neurula, tailbud and feeding tadpole. We have also found the RNA in several adult tissues (skin, testis, stomach, intestine) at different levels.
Expression of the nuclear protein mitotin in differentiating in vitro HL 60 cells
Authors: Philipova Radka N. , Vassilev Alex P. , Kaneva Radka P. , Andreeva Penka , Todorov Ivan T. , Hadjiolov Asen A.
Published: April 2003

Summary— Mitotin is a 125 kDa/pI 6.5 nuclear protein specific for proliferating cells and markedly increased prior to and during mitosis. This study presents evidence for the expression of this protein during dimethylsulfoxide (DMSO) induced differentiation of human promyelocytic leukemia HL 60 cells. The expression had been followed at two levels: as antigen, using a specific antimitotin monoclonal antibody and as mRNA, using a specific cDNA probe. The results from the immunofluorescent study show a gradual disappearance of mitotin in differentiating HL 60 cells starting from the fourth day after DMSO induction. On the other hand, the changes in the expression of mitotin mRNA were much more dramatic. This mRNA is expressed at a high level during the first three days of differentiation but shows a striking decrease after the fourth day. This correlates with the rapid changes in the number of blast cells in the differentiating HL 60 cell population. Therefore, the expression of mitotin mRNA can serve as a marker for the changes accompanying the termination of cell proliferation in differentiating cells.
Subcellular distribution of clathrin in cultured hypothalamic neurons
Authors: Goud Bruno , Faivre‐Bauman Annie , Picart Renée , Tixier‐Vidal Andrée
Published: April 2003

Summary— The subcellular distribution of clathrin has been examined in developing hypothalamic neurons cultured in a chemically defined medium up to synapse formation (12–13 days in vitro) and exposed, or not, to a depolarizing concentration of KCl (60 mM for 3 min) followed, or not, by a return to control KCl concentration (3 mM KCl for 3 min). Previous studies have shown that such treatments induce in synaptic boutons a rapid vesicle depletion followed by massive restoration. Using an enzyme immunoassay, we have compared the relative proportion of assembled and unassembled pools of clathrin as a function of exposure to depolarizing or repolarizing concentrations of KCl. In parallel we have localized clathrin at the electron microscopic level using immunoperoxidase. Clathrin concentration in culture is lower (0.36 vs 0.75%) and the proportion of unassembled clathrin is much higher than in the adult brain (82 vs 14%). These proportions were not affected by depolarizing or repolarizing treatments. Morphologically clathrin was exclusively detected in two neuron compartments: perikarya and synaptic boutons. In perikarya clathrin was localized as a thick coat on plasma membrane coated pits and in the Golgi zone on coated buds and vesicles, presumably located in a trans compartment. In synaptic boutons clathrin immunoreaction was found as an irregular thin rim around synaptic vesicles, whatever the polarization state of the cells, but coated vesicles were extremely rare. Taken together these findings raise the problem of the functional meaning and localization of the large unassembled pool of clathrin in such neurons and question its role in vesicular traffic in synaptic boutons.
Changes in intracellular pH following egg activation and during the early cell cycle of the amphibian Pleurodeles waltlii, coincide with changes in MPF activity
Authors: Grandin Nathalie , Rolland Jean‐Paul , Charbonneau Michel
Published: April 2003

Summary— Previous work on Xenopus laevis suggests a temporal coincidence between inactivation of the M‐phase promoting factor (MPF) and intracellular pH (pHi) increase during egg activation. In addition, we recently showed that during the early cell cycle of Xenopus eggs, MPF activity cycling and pHi oscillations were temporally and functionally related [30]. In the present work, using eggs of another amphibian, Pleurodeles waltlii, which has a natural cell cycle considerably longer than that of Xenopus laevis, we show a temporal coincidence between MPF activity and pHi changes, both at the time of egg activation and at each of the following cell cycles. Egg activation‐induced phi changes in Pleurodeles did not involve classical plasma membrane ion exchangers, and were not due to the activation of a H+ conductance. On the other hand, the pHi oscillations intervening at each cell cycle were suppressed by inhibitors of protein synthesis or phosphorylation, as were their counterparts in Xenopus eggs. We propose that physiological pHi changes in Pleurodeles and Xenopus eggs might have a metabolic origin, in direct relation with the cascade of phosphorylations‐dephosphorylations of proteins implicated in the control of the cell cycle.
Phenotypic modulations of human umbilical vein endothelial cells and human dermal fibroblasts using two angiogenic assays
Authors: Bikfalvi Andreas , Cramer Elisabeth M. , Tenza Danièle , Tobelem Gérard
Published: April 2003

Summary— Different angiogenic assays in vitro have helped to define various events underlying angiogenesis. In this report we have compared the phenotypic modifications of human umbilical vein endothelial cells (HUVE cells) and human dermal fibroblasts using Matrigel and collagen gels. Both HUVE cells and human dermal fibroblasts form a network of anastomosing cords that apparently resemble blood capillaries when grown on Matrigel. The whole network was formed by several cellular aggregates joined to each other by cellular cords. Lumen formation was not observed in this angiogenic system. In opposite, considerable differences between HUVE cells and human dermal fibroblasts were observed in the three‐dimensional angiogenic assay on collagen gels described by Montesano et al [14]. These results indicate that data obtained with angiogenic systems using Matrigel must be interpreted with caution and that the assay described by Montesano et al [14], is more reliable to describe angiogenesis.
A cost effective small hospital in Bangladesh: what it can mean for emergency obstetric care
Authors: McCord C. , Chowdhury Q.
Published: April 2003

Mortality has improved dramatically in most of South Asia as a consequence of modest economic improvement, better nutrition and a combination of health education, immunization, family planning and home treatment of certain common diseases, especially diarrhea and respiratory infections. However, death rates are still much higher than in parts of the world with fully developed health services and residual mortality is largely due to conditions which require very basic hospital services such as surgery for complications of pregnancy, infections and trauma, transfusion, intravenous fluids, oxygen and intensive antibiotics. All of these can be made available in very simple and unsophisticated hospital facilities. It has generally been assumed that the cost of such facilities would be high, and cost effectiveness much less than that of preventive, educational and home care programs. In 1995, our 50 bed hospital in rural Bangladesh had a cost per patient‐day of 525 Bangladesh Takas (US$13.15) and a cost per capita for the population served of 25 Takas (US$0.62) per year. Every month 180 patients were admitted, one‐third with clearly life‐threatening or disabling conditions which could be successfully treated in such a facility. We adapted the Disability Adjusted Life Year (DALY) method of cost effectiveness analysis to calculate the DALYs (years of disability‐free life) preserved for individual patients during a 3‐month period, using what we considered to be very conservative estimates of the threat to life and the efficacy of treatment. The total cost of all hospital activities over the 3 months was divided by the sum of the DALYS for those patients who were successfully treated for clearly life threatening or disabling conditions, to give a cost per DALY of 437 Takas (US$10.93). This compares favorably with estimates by others of a cost per DALY of US$30 for measles immunization, $20 for acute lower respiratory infection detection and home treatment, or $2 for tetanus immunization of pregnant women. Sixty‐two percent of the DALYS saved came from emergency obstetric care (EmOC) related activities. We conclude that cost effective basic hospital service can be added to immunization, family planning and other basic health services now available in countries like Bangladesh with a very low increase in total cost and that the benefits which would accrue, particularly for maternal and perinatal mortality, would be great.
Relaxation of convex functionals: the gap problem
Authors: Acerbi E. , Bouchitté G. , Fonseca I.
Published: April 2003

It is shown that the relaxed energy

\mathcal{F}\left(u,A\right): =
\inf \Big\{
\lim\!\! \inf_{n\rightarrow + \infty }\!\int \limits_{A}\! f(x,\nabla u_{n})dx:\{u_{n}\} \subset W_{\text{loc}}^{1,\beta }(A;\mathbb{R}^{d}),\, u_{n}\!\rightarrow\! u \text{ in }L^{1}(A;\mathbb{R}^{d})
\Big\},

admits the representation

\mathcal{F}\left(u,A\right) = \int \limits_{A}f\left(x,\nabla u\right)dx + \mu _{s}\left(u,A\right),

where

f

is a convex, Carathéodory integrand satisfying a nonstandard “

α–β

” growth hypothesis,

β\in [α,Nα/(N-1))

. Sufficient conditions guaranteeing that

μ_s(u,·)=0

are discussed. An example asserting that this representation may fail in the quasiconvex case is provided.

Nous montrons que l’énergie relaxée

\mathcal{F}\left(u,A\right): =
\inf \Big\{
\lim\!\! \inf_{n\rightarrow + \infty }\!\int \limits_{A}\! f(x,\nabla u_{n})dx:\{u_{n}\} \subset W_{\text{loc}}^{1,\beta }(A;\mathbb{R}^{d}),\, u_{n}\!\rightarrow\! u \text{ in }L^{1}(A;\mathbb{R}^{d})
\Big\},

admet la représentation intégrale

\mathcal{F}\left(u,A\right) = \int \limits_{A}f\left(x,\nabla u\right)dx + \mu _{s}\left(u,A\right),

lorsque

f

est un intégrande convexe de Carathéodory vérifiant une condition de croissance non standard de type “

α–β

” avec

β\in [α,Nα/(N−1))

. Des conditions suffisantes assurant que

μ_s(u,·)=0

sont proposées ainsi qu’un exemple montrant que la représentation obtenue ne s’applique pas au cas quasiconvexe.
Uniqueness of the polar factorisation and projection of a vector-valued mapping
Authors: Burton G.R. , Douglas R.J.
Published: April 2003

This paper proves some results concerning the polar factorisation of an integrable vector-valued function

u

into the composition

u=u^{\#}∘s

, where

u^{\#}

is equal almost everywhere to the gradient of a convex function, and

s

is a measure-preserving mapping. It is shown that the factorisation is unique (i.e., the measure-preserving mapping

s

is unique) precisely when

u^{\#}

is almost injective. Not every integrable function has a polar factorisation; we introduce a class of counterexamples. It is further shown that if

u

is square integrable, then measure-preserving mappings

s

which satisfy

u=u^{\#}∘s

are exactly those, if any, which are closest to

u

in the

L^2

-norm.

Cet article prouve des résultats au sujet de la factorisation polaire d’une application à valeurs vectorielles sommable

u

en une composition

u=u^{\#}∘s

, où

u^{\#}

est égal presque partout à la dérivée d’une application convexe et

s

est une application conservant la mesure. On démontre que la factorisation est unique (c’est à dire l’application conservant la mesure

s

est unique), si et seulement si

u^{\#}

est presque injectif. Les applications sommables ne possèdent pas toujours les factorisations polaires ; on introduit des contre-examples. On prouve aussi que si

u

est de carré sommable, alors les applications conservant la mesure qui satisfont

u=u^{\#}∘s

sont précisement celles qui sont les plus près de

u

en

L^2

-norme.
The Political Economy of a Soviet Military R&D Failure: Steam Power for Aviation, 1932 to 1939
Authors: Harrison Mark
Published: April 2003

The behavior of principals and agents in the interwar Soviet economy can be studied through the failed attempt to develop a new aviation-engine technology based on the steam turbine. Some possible approaches to the evaluation of R&D failure are outlined. Soviet R&D agents competed for funding within a command system. Principals funded ventures in a context of biased information and adverse selection. In the presence of sunk costs budget constraints on individual projects were often loose, but were tightened periodically. There is evidence of rent seeking, but not that rents were distributed deliberately as political gifts to loyal agents.
Historia económica regional de España, siglos XIX y XX. Edited by Luis Germán, Enrique Llopis, Jordi Maluquer de Motes, and Santiago Zapata. Barcelona: Crítica, 2001.
Authors: Ringrose David
Published: April 2003

This volume is a collection of nineteen essays, seventeen of which summarize the economic history of the individual autonomous regions established in Spain as part of the transition to democratic government that began in 1975. The last two essays are valiant efforts to synthesize some of the information in the first seventeen. The first of the concluding essays discusses the persistence of pre-nineteenth-century structures in Spain during the nineteenth century. The second examines the relationship of the various autonomous regions within Spain to the European Union.
Système Éducatif et Performances Économiques au Royaume-Uni 19eet 20eSiècles. By Vincent Carpentier. Paris: L'Harmattan, 2001. Pp. 295. Paper.
Authors: Mitch David
Published: April 2003

One strain of French structuralism has argued for the existence of long-run economic cycles driven by Marxist class and economic dynamics. Vincent Carpentier employs this approach in his study of the relationship between economic and educational change in the United Kingdom over the past two centuries. The basic framework was developed by Carpentier's mentor, Louis Fontvielle of the University of Montpellier, who has used it to examine the same relationship for France. According to this framework, leading modern economies such as those of France and the United Kingdom over the past two centuries have experienced four Kondratieff cycles of 50 years duration each. During the first three cycles, the level of resources devoted to education tended to move counter-cyclically; in the fourth cycle, the relationship reversed to move pro-cyclically. Fontvielle's explanation of this pattern is that during the first three cycles, during expansionary phases, high returns to physical capital implied pressures to cut back on public educational investments while during downturns, social stresses and contradictions in the system led to expanding educational investments. However in the fourth cycle, since 1945, both the rise of the welfare state and the increasing contribution of an educated labor force to productivity due to the increasing importance of science-based technical change resulted in the level of educational investments moving pro-cyclically.
Looking for Work, Searching for Workers: American Labor Markets During Industrialization. By Joshua L. Rosenbloom. New York: Cambridge University Press, 2002. Pp. xvi, 208. $20.00, paper.
Authors: Fishback Price V.
Published: April 2003

Joshua Rosenbloom provides a superb study of the operations of the U.S. labor market between the Civil War and World War I. The book weaves fascinating descriptions of the various ways in which employers and workers established connections together with clear summaries of an extensive amount of background quantitative work. Although the analysis is firmly grounded on a series of more technical statistical studies, most of the book does not emphasize econometrics. Instead, the findings are effectively summarized using graphs, simple means and telling anecdotes that illustrate the experiences of many workers. The book is beautifully written and can be used by economists, historians, and both graduate and undergraduate students to obtain a clearer understanding of how markets work.
The American Dole: Unemployment Relief and the Welfare State in the Great Depression. By Jeff Singleton. Westport, CT: Greenwood Press, 2000. Pp. viii, 243. $72.95.
Authors: Fleck Robert K.
Published: April 2003

In this book, Jeff Singleton provides a detailed history of relief programs prior to and during the Great Depression. He also assesses the obstacles to welfare reform since the 1930s, and he generally argues for more reliance on social insurance and public employment as alternatives to means-tested welfare programs. The book will be of interest to scholars seeking to understand the details and evolution of relief institutions before and during the New Deal, as well as to those interested in the historical origins of modern policy.
The Spirit of Capitalism: Nationalism and Economic Growth. By Liah Greenfeld. Cambridge, MA: Harvard University Press, 2001. Pp. xi, 541. $45.00.
Authors: Hall John A.
Published: April 2003

The title of this book attests to the fact that the author “communed” with Max Weber's famous thesis whilst doing her own research. She is absolutely at one with Weber—and Keynes!—in insisting that there is a spirit of capitalism, an irrationality underlying rational calculation whereby one continues to work even when one's needs have been met. Spirit of this sort is held to be a cultural idiosyncracy rather than an a universal norm. However, this spirit has nothing to do with religion, not least for the central reason given by Tawney—namely that Protestant reformers sought to control the economy quite as much as did their predecessors. The author offers us a bold and sustained alternative view: economic growth resulted from one thing and one thing only—the presence of nationalism.
Gender, Growth and Trade: The Miracle Economies of the Postwar Years. By David Kucera. London: Routledge, 2001. Pp. xi, 217.
Authors: Hunt Jennifer
Published: April 2003

The central theme of this book is the interplay of women's employment and the macro-economy in postwar Germany and Japan. David Kucera introduces the distinction between two possible types of flexibility in the labor market. The first occurs in the absence of interference with the market mechanism from laws or institutions. This flexibility may reduce unemployment and increase the response time to shocks, at the cost of low wages and insufficient training. In the second type of flexibility, a buffer group provides this flexibility, while core workers are protected from the vagaries of the market and receive training and high wages. Kucera argues that by using women as a buffer group to protect men, Japan is able at a macro-level to reap the benefits of both the “low-road” and “high-road” approaches. Bolstering this argument, and showing that Germany pursues instead the simpler “high-road” strategy, is the most important aim of the book.
Southeast Asian History and the Mediterranean Analogy
Authors: Sutherland Heather
Published: April 2003

Historians of Southeast Asia have been inspired by Fernand Braudel's classic The Mediterranean because of its focus on the sea and multidisciplinary approach, and because it seems to solve two recalcitrant historiographical problems: the definition of time and space, and the reconciliation of local identities and external influence. But while Braudel's prose and intellectual ambition are justly seen as inspiring, conceptual confusion and analytic evasion limit his contribution.
Lukas D. Tsitsipis. A linguistic anthropology
of praxis and language shift: Arvanítika (Albanian) and
Greek in contact. (Oxford Studies in Language Contact.)
Oxford: Clarendon Press, 1998. Pp. xi, 163. Hb. $78.00.
Authors: Hill Jane H.
Published: April 2003

Tsitsipis's valuable and sophisticated
linguistic-anthropological study reports on research conducted
over a number of years in two Albanian-speaking communities
in southern Greece, Spáta in the district of Attika,
and Kiriáki in the district of Biotia. These towns
historically spoke Arvanítika, a Tosk dialect of Albanian.
Although both communities date at least to the fourteenth century,
they contrast sharply in that the first is very close to Athens,
while the second is in a mountainous, isolated area. Kiriáki
has a younger generation of fluent Arvanítika speakers,
but language shift to Greek is advanced in both communities
– shaped, according to Tsitsipis, not only by economic
changes involving improved transportation and communication,
the mechanization of agriculture, and urbanization, which have
accelerated since the 1950s, but also by the ideological formations
associated with the consolidation of the Greek nation-state,
dating from the mid-19th century. The latter process focused
symbolically on the exaltation of the heritage of the Greeks,
and especially of their language. While adding considerable
nuance to our understanding of the situation, Tsitsipis confirms
the findings of Eric Hamp (1978:161–62; quoted by Tsitsipis
on p. 11) that Arvanítika speakers “unflinchingly
and happily accept the axioms that Greek is the oldest culture,
Greek literature the first … and the Greek language the
oldest, the richest … the only one with a true grammar.
Magnus Huber, Ghanaian Pidgin English in its
West African context: A sociohistorical and structural
analysis. Amsterdam & Philadelphia: John Benjamins,
1999. Pp. xviii, 318. Hb.
Authors: Avram Andrei A.
Published: April 2003

This book, it must be said from the outset, is a
remarkable addition to the literature on pidgin and creole
languages. It is particularly important because it investigates
the diachrony and synchrony of an English-lexicon contact language
on which very little has been previously published, and whose
very existence has been called into question by some.
Habitus as the principle for social practice: A proposal
for critical discourse analysis
Authors: SCHEUER JANN
Published: April 2003

Critical discourse analysts are often criticized
for interpreting linguistic data in political contexts, placing
the data in an artificial environment motivated by political
agendas rather than scientific inquiry, and thereby disregarding
findings that would follow from a data-internal and more
empirically grounded analysis. This article argues that critical
discourse analysis may gain proficiency for social analysis
by adopting concepts suitable for cultural and historical analysis
of socialization, as found in Bourdieu. Application is demonstrated
in a study of a job interview, with close linguistic analysis;
close attention is given to the applicant by drawing on evaluations
after the interview and on a retrospective interview with the
applicant. It is proposed that a method combining linguistic
and socio-historical analysis may offer advantages to critical
discourse analysis, including a more systematic approach to
text-external contexts and qualified, balanced perception of
the social agent as a creative yet socially determined
individual.
Visual imagery is not always like visual perception
Authors: Arterberry Martha E. , Craver-Lemley Catherine , Reeves Adam
Published: April 2003

The “Perky effect” is the interference of visual imagery with vision. Studies of this effect show that visual imagery has more than symbolic properties, but these properties differ both spatially (including “pictorially”) and temporally from those of vision. We therefore reject both the literal picture-in-the-head view and the entirely symbolic view.
The nature of mental imagery: How null is the “null hypothesis”?
Authors: Dalla Barba Gianfranco , Rosenthal Victor , Visetti Yves-Marie
Published: April 2003

Is mental imagery pictorial? In Pylyshyn's view no empirical data provides convincing support to the “pictorial” hypothesis of mental imagery. Phenomenology, Pylyshyn says, is deeply deceiving and offers no explanation of why and how mental imagery occurs. We suggest that Pylyshyn mistakes phenomenology for what it never pretended to be. Phenomenological evidence, if properly considered, shows that mental imagery may indeed be pictorial, though not in the way that mimics visual perception. Moreover, Pylyshyn claims that the “pictorial hypothesis” is flawed because the interpretation of “picture-like” objects in mental imagery takes a homunculus. However, the same point can be objected to Pylyshyn's own conclusion: if imagistic reasoning involves the same mechanisms and the same forms of representation as those that are involved in general reasoning, if they operate on symbol-based representations of the kind recommended by Pylyshyn (1984) and Fodor (1975), don't we need a phenomenological homunculus to tell an imagined bear from the real one?
So be good for goodness' sake
Authors: Hartung John
Published: April 2003

Altruism is traditionally encouraged by promoting a goal, for example, going to heaven. In contrast, Rachlin argues that altruistic behavior can be sufficiently reinforced by the abstract intrinsic reward that comes from maintaining an unbroken pattern of altruistic behavior. In my experience, there are very few people for whom this is true. For fellow atheists and anti-theists, I suggest an alternative.
Neural substrates of visual percepts, imagery, and hallucinations
Authors: Grossberg Stephen
Published: April 2003

Recent neural models clarify many properties of mental imagery as part of the process whereby bottom-up visual information is influenced by top-down expectations, and how these expectations control visual attention. Volitional signals can transform modulatory top-down signals into supra-threshold imagery. Visual hallucinations can occur when the normal control of these volitional signals is lost.