bluuebunny/crossref_metadata_2025 huggingface dataset:
Model of Brand Choice with a No-Purchase Option Calibrated to Scanner-Panel Data
Authors: Chib Siddhartha , Seetharaman P.B. , Strijnev Andrei
Published: May 2004

In usual practice, researchers specify and estimate brand-choice models from purchase data, ignoring observations in which category incidence does not occur (i.e., no-purchase observations). This practice can be problematic if there are unobservable factors that affect the no-purchase and the brand-choice decisions. When such a correlation exists, it is important to model simultaneously the no-purchase and the brand-choice decisions. The authors propose a model suitable for scanner-panel data in which the no-purchase decision depends on the price, feature, and display of each brand in the category and on household stock of inventory. They link the no-purchase model to the brand-choice outcome through marketing-mix covariates and through unobservables that affect both outcomes. The authors assume that model parameters are heterogeneous across households and allow for a flexible correlation structure between the coefficients in the no-purchase model and those in the brand-choice model. The model formulation is more general than what is possible from either a nested logit model or a translog utility model and from models in which the no-purchase outcome is an additional outcome with the deterministic component of its utility set equal to zero. The authors estimate the proposed model using Bayesian Markov chain Monte Carlo estimation methods. They then apply the estimation methods to scanner-panel data on the cola product category and compare the results with those from the widely used nested logit model.
Waiting for the Web: How Screen Color Affects Time Perception
Authors: Gorn Gerald J. , Chattopadhyay Amitava , Sengupta Jaideep , Tripathi Shashank
Published: May 2004

The authors investigate the link between the color of a Web page's background screen while the page is downloading and the perceived quickness of the download. They draw on research that supports links between color and feelings of relaxation and between feelings of relaxation and time perception. The authors predict that the background screen color influences how quickly a page is perceived to download and that feelings of relaxation mediate this influence. In a series of experiments, they manipulate the hue, value, and chroma dimensions of the color to induce more or less relaxed feeling states. The findings suggest that for each dimension, colors that induce more relaxed feeling states lead to greater perceived quickness. The authors provide triangulating evidence with an alternative manipulation: the number of times subjects wait for a download. As does color, this also leads to variation in levels of relaxation and perceived quickness. A final experiment reveals that color not only affects perceived download quickness but also has consequences for users' evaluations of the Web site and their likelihood of recommending it to others.
The Augmented Latent Class Model: Incorporating Additional Heterogeneity in the Latent Class Model for Panel Data
Authors: Varki Sajeev , Chintagunta Pradeep K.
Published: May 2004

Marketing researchers have actively sought to account for the heterogeneity in households' preferences and responses to marketing-mix elements (e.g., price, promotion) when analyzing scanner-panel data. This is because not doing so biases response coefficient estimates that can potentially alter the conclusions drawn from such analyses. In this article, the authors present an extension to the latent class model (LCM) that accounts for additional heterogeneity by allowing households' preferences to be a continuous mixture of segment-level preferences. The authors show how their model generalizes the LCM by the mere addition of S + 1 parameters, where S refers to the number of segments. Because a limitation of the traditional LCM is that it does not adequately account for heterogeneity in responses across households, the authors' model mitigates this criticism leveled at the LCM. They then compare their model with the traditional LCM and the equivalent continuous mixture (random-effects) models in terms of model selection criteria and predictive ability. The results indicate that the authors' model outperforms both the LCM and the equivalent random-effects (logit) model on these criteria.
New technique for studying reaction forces during primate behaviors on vertical substrates
Authors: Vinyard Christopher J. , Schmitt Daniel
Published: May 2004

Recording reaction forces from primates during behaviors on vertical substrates, such as leaping, climbing, or biting trees, typically requires the design and construction of customized recording devices or mounting commercially available force platforms in a vertical position. The technical difficulties imposed by either option have hindered in vivo research on the kinetics of primate behaviors on vertical substrates. We describe a simple, inexpensive apparatus for recording forces from primate behaviors on vertical substrates. The apparatus includes an instrumented beam fastened directly to a horizontal force platform and a surrounding vertical substrate that does not contact the instrumented beam or platform. The contact piece at the end of the instrumented beam is positioned flush with the noninstrumented vertical substrate, and reaction forces elicited on this instrumented section are directed to the force platform. Because most of the vertical substrate is not instrumented, we can isolate and record forces from a single limb or jaw during a behavior. Biewener and Full ([1992] Biomechanics Structures and Positions: A Practical Approach; New York: Oxford University press, p. 45–73) gave seven criteria to consider when designing a customized force‐recording device. Where appropriate, we tested if our apparatus met their criteria. The apparatus accurately records forces in three orthogonal directions, has low cross‐talk, maintains a high frequency response, exhibits a linear response up to at least 200 Newtons, and displays a uniform response to a given force across the instrumented contact piece. Our design does not easily facilitate the identification of the point of force application. Therefore, joint moments cannot be easily calculated. This limitation, however, does not affect the apparatus's ability to accurately record the magnitude and direction of a force (as shown by other tests). We developed this apparatus to measure jaw forces during tree gouging in common marmosets (Callithrix jacchus), but the general design can be readily modified to study a variety of primate behaviors on vertical substrates. Am J Phys Anthropol, 2004. © 2004 Wiley‐Liss, Inc.
Comparison in processability and mechanical and thermal properties of ethylene–octene copolymer crosslinked by different techniques
Authors: Sirisinha Kalyanee , Meksawat Darinya
Published: May 2004

The crosslinking of metallocene ethylene–octene copolymer was investigated. The crosslinked polymers were prepared using two different techniques, i.e., peroxide crosslinking and silane–water crosslinking. In the former, the crosslinking reaction was conducted in a twin‐screw extruder, in the presence of dicumylperoxide. In the latter, the polymer was first grafted with vinyl trimethoxysilane in the extruder and subsequently crosslinked with water. The paper aims at investigation of the differences between these two techniques, in terms of processing and product mechanical and thermal properties. The results showed that the silane‐crosslinked polymers could be prepared with much higher gel contents than the peroxide‐crosslinked samples. The silane‐crosslinked polymers also retained the elastomeric characteristics of the pure polymer and showed remarkably higher extensibility, better thermal stability, and energy storage capacity. An explanation for the property differences between peroxide‐crosslinked and silane‐crosslinked polymers was proposed. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1179–1185, 2004
Radiation synthesis of hydrogels to enhance sandy soils water retention and increase plant performance
Authors: El‐Rehim H. A. Abd , Hegazy El‐Sayed A. , El‐Mohdy H. L. Abd
Published: May 2004

Preparation and characterization of superabsorbent hydrogels obtained by radiation induced crosslinking of polyacrylamide (PAAm), poly(acrylic acid) (PAAc), poly(vinyl alcohol) (PVA), and potassium polyacrylate (PAAcK) were investigated individually and in (PAAm)–binary systems for possible uses in agricultural fields. The swelling of the investigated hydrogels was mainly related to the type of their hydrophilic functional groups and/or the presence of polarized charges. The preparation conditions, such as irradiation dose and hydrogel blend compositions, that influence the water absorbency of PAAm/PAAcK copolymers and alter their gel content and crosslinking density were investigated. The higher the irradiation dose, the higher the gel content, and the lower the water absorbency. PAAm/PAAcK copolymer, possessing pore structure and fast swelling, was prepared by mixing the hydrogel components with a gas‐forming agent, namely, ammonium carbonate. Studies were also made on the applications of such hydrogels to improve the physical and water retention properties of sandy soil for agricultural purposes. The effect of different types and amounts of hydrogels added to sandy soil on the emergence, vegetative growth, and wilting time of corn (Zea mays) plants was investigated. As the hydrogel level increased, the average of plant height, leaf width, total dry weight, corncob production, and time to wilt increased. The obtained results suggested that the PAAm/PAAcK hydrogels can improve sandy soil properties for cultivation, because they often absorb and keep water one thousand times more than their own weight, reduce watering frequency of the plants, and enhance water retention of soil matrix that results in an increase in plant growth and performance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1360–1371, 2004
Investigations on the reactive surface modification of polycarbonate by surface‐reactive injection molding
Authors: Nagel J. , Bräuer M. , Hupfer B. , Grundke K. , Schwarz S. , Lehmann D.
Published: May 2004

A new procedure of surface modification was investigated in which the modification was coupled with the injection molding process. This procedure could save other commonly used surface modification procedures such as flame or plasma treatment. According to the procedure, a reactive modifier was applied to the surface of the mold cavity. On injection of the plastic melt, a chemical reaction took place, which attaches the modifier covalently to the resultant plastic part. In this contribution, conditions are considered for the modification of polycarbonate with poly(vinyl alcohol) and polyethylenimine as modifiers. The reaction in the melt was investigated and the modified surfaces of injection‐molded plates were characterized. The surface modification, realized with the new approach, was permanent. It allows for the introduction of special functional groups, which may be useful for further reactive processing stages such as reactive adhesive joining, reactive coating, metallization, or functionalization for special applications. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1186–1191, 2004
Synthetic clay nanocomposite‐based coatings prepared by UV‐cure photopolymerization
Authors: Shemper B. S. , Morizur J.‐F. , Alirol M. , Domenech A. , Hulin V. , Mathias L. J.
Published: May 2004

The effect of synthetic clay on the photopolymerization kinetics and coating properties of methyl α‐hydroxymethylacrylate (MHMA) systems in the presence of novel hydroxylated dimethacrylate crosslinkers is reported. In the presence of clay earlier onset of autoacceleration was observed, high rates of polymerization were achieved, and high final overall conversions were reached. Higher rates and increase in conversions were also observed as the clay content increased in the medium. To increase compatibility between clay and polymer matrix the use of Jeffamines as polymer/clay compatibilizers, based on ion–dipole interactions between ethylene oxide units and clay ions, was also investigated. Nanocomposite‐based films by photopolymerization of the mixtures coated on glass microscope slides were prepared and evaluated using X‐ray and TEM. The absence of Bragg diffraction peaks in all nanocomposite films indicated loss of organization of the clay layers and formation of well‐dispersed, exfoliated systems was confirmed by TEM. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1252–1263, 2004
On the application of a damped model to the falling weight impact characterization of glass beads–polystyrene composites
Authors: Sánchez‐Soto M. , Martínez A. B. , Santana O. O. , Gordillo A.
Published: May 2004

Instrumented falling weight impact tests were carried out to characterize the mechanical behavior of a material pattern formed by polystyrene and different amounts of glass beads. This characterization was performed at high strain rate using two different impact arrangements: the first uses high impact energy at the striker, whereas the second uses a low‐impact energy. Starting from a conservative model, a nonconservative one has been proposed for the low‐energy impact configuration as a better approach to the material behavior. In this latter model, the energy losses were quantified through the restitution coefficient. Two alternative methods for its calculation are described. The results shows good agreement between the flexural modulus and break stresses calculated in either the low‐ or the high‐energy arrangement; however, the low‐energy impact method yields more confidence results. Using the proposed model, the composites' fracture onset was determined, and also in the samples with low content of glass beads, it was possible to assess the micromechanism of failure, given the estimation for the stress to produce crazing. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1271–1284, 2004
Process cure monitoring of unsaturated polyester resins, vinyl ester resins, and gel coats by Raman spectroscopy
Authors: Skrifvars Mikael , Niemelä Pentti , Koskinen Rauli , Hormi Osmo
Published: May 2004

The curing process of unsaturated polyester resins, vinyl ester resins, and gel coats was studied by using a process Raman spectrometer, equipped with a remote fiber‐optic probe. The resins were cured and Raman spectra were recorded during the curing reaction. The spectral changes were identified and, from the intensities, the cure process could be monitored. Gel times given by the resin suppliers correlated well with the Raman results. It could also be seen that the curing process continues for a long time, up to several weeks. Postcuring will finally complete the curing process. White and lightly colored gel coats could easily be monitored by Raman spectroscopy, but fluorescent problems were encountered with heavily colored pigments. The curing of laminates containing 50–70 wt % glass fiber mat could also be followed by Raman spectroscopy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1285–1292, 2004
Swelling behavior of PDMS–PMHS pervaporation membranes in ethyl acetate–water mixtures
Authors: Vilaplana F. , Osorio‐Galindo M. , Iborra‐Clar A. , Alcaina‐Miranda M. I. , Ribes‐Greus A.
Published: May 2004

Pervaporation composite membranes were prepared with a three‐layer structure: a PP support, a PEI microporous structure, and a PDMS–PMHS selective layer. Swelling tests were performed in water, ethyl acetate, and four different ethyl acetate–water mixtures, to calculate the diffusional and swelling parameters. Moreover, the dynamic–mechanical properties of the membranes were obtained before and after the swelling experiments, and their relaxation spectra were characterized with the Fuoss–Kirkwood equation and analyzed in terms of the free volume parameter. It was found that the ethyl acetate possesses high affinity with the composite membranes and that the absorption of these small molecules substantially modifies the viscoelastic behavior and structure of the active layer. The combination of swelling experiments and the study of the mechanical relaxations proved to be an appropriate technique to investigate the behavior of pervaporation membranes immersed in different mixtures. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1384–1393, 2004
A multidimensional approach to the study of human‐information interaction: A case study of collaborative information retrieval
Authors: Fidel Raya , Mark Pejtersen Annelise , Cleal Bryan , Bruce Harry
Published: May 2004

While most research in the area of human‐information behavior has focused on a single dimension—either the psychological or the social—this case study demonstrated the importance of a multidimensional approach. The Cognitive Work Analysis framework guided this field study of one event of collaborative information retrieval (CIR) carried out by design engineers at Microsoft, including observations and interviews. Various dimensions explained the motives for this CIR event and the challenges the participants encountered: the cognitive dimension, the specific task and decision, the organization of the teamwork, and the organizational culture. Even though it is difficult at times to separate one dimension from another, and all are interdependent, the analysis uncovered several reasons for design engineers to engage in CIR, such as when they are new to the organization or the team, when the information lends itself to various interpretations, or when most of the needed information is not documented. Similar multidimensional studies will enhance our understanding of human‐information behavior.
Recombinant antigen from Helicobacter pylori urease as vaccine against H. pylori‐associated disease
Authors: Fujii Ryoji , Morihara Fumiko , Fukushima Keigo , Oku Takashi , Hifumi Emi , Uda Taizo
Published: May 2004

It is well documented that the enzymatic active site of Helicobacter pylori urease is present in the β‐subunit. An important sequence of 135 amino acids of the β‐subunit was determined from the structure of H. pylori urease and by a homology‐based study of the urease of other bacteria and plants. The sequence (UreB) was expressed in Escherichia coli as a recombinant fusion protein with glutathione‐S‐transferase (GST). Seventeen monoclonal antibodies, UA‐1–17, were produced using the UreB‐GST as the immunogen. The obtained monoclonal antibodies showed a high specificity to UreB, and some of the MAbs cross‐reacted with Jack bean urease. About 70% of the established MAbs displayed an inhibitory effect on the enzymatic activity of the urease. Among them, UA‐15 MAb could reduce the activity by 53% and it immunologically binds to the bacterium infecting the human stomach mucosa. The antiserum induced by immunization with a recombinant UreB‐GST into rabbits displayed a specific binding to mucosal surfaces of the human stomach infected with the pathogen H. pylori. Moreover, the antiserum suppressed the enzymatic activity of H. pylori urease, while the purified H. pylori urease could not induce such an antiserum. © 2004 Wiley Periodicals, Inc.
Changes in the characteristics and survival rate of hepatocellular carcinoma from 1976 to 2000
Authors: Toyoda Hidenori , Kumada Takashi , Kiriyama Seiki , Sone Yasuhiro , Tanikawa Makoto , Hisanaga Yasuhiro , Hayashi Kazuhiko , Honda Takashi , Kitabatake Shusuke , Kuzuya Teiji , Nonogaki Koji , Kasugai Toshifumi , Shimizu Junichi
Published: May 2004

BACKGROUND

The authors analyzed changes in the characteristics and survival rate of patients with hepatocellular carcinoma (HCC) in the past 25 years.

METHODS

Trends in clinical characteristics and survival rate of patients with HCC were evaluated retrospectively based on data from 1365 patients who were diagnosed, treated, and followed between 1976 and 2000.

RESULTS

Between 1976–1995, the number of patients with smaller tumors, a less advanced tumor stage, and with a lower Child–Pugh class increased markedly. No differences were observed in the distributions of these three factors between the periods 1991–1995 and 1996–2000. The year of HCC diagnosis, tumor size, tumor stage, Child–Pugh class, and the kind of initial treatment received correlated significantly with patient survival rates by multivariate analysis. The year of HCC diagnosis was found to contribute independently to the improvement in patient survival rates. Using the Kaplan–Meier comparison, the time periods during which the highest patient survival rates occurred were found to be 1991–1995/1996–2000, 1986–1990, and 1976–1985, in that order. The authors did not observe a difference with regard to survival rates between patients in the 1991–1995 and 1996–2000 groups.

CONCLUSIONS

The characteristics of patients with HCC changed dramatically from 1976 to 1995 (but not in the past 10 years) toward the earlier detection of HCC. This contributed to the improvement noted in patient survival rates during this period. The year of HCC diagnosis was found to be an independent factor for the improved survival rates by multivariate analysis. This indicated that the progress of treatment and care for patients with HCC contributed to the annual improvement in patient survival rates. Cancer 2004. © 2004 American Cancer Society.
The incompressible limit of solutions of the two‐dimensional compressible Euler system with degenerating initial data
Authors: Dutrifoy Alexandre , Hmidi Taoufik
Published: May 2004

Using Strichartz estimates, it is possible to pass to the limit in the weakly compressible 2‐D Euler system, when the Mach number ϵ tends to zero, even if the initial data are not uniformly smooth. More precisely, their norms in Sobolev spaces embedded inC1can be allowed to grow as small powers of ϵ−1.

This leads to results of convergence to solutions of the incompressible Euler system whose regularity is critical, such as vortex patches or Yudovich solutions. © 2000 Wiley Periodicals, Inc.
Allergen extracts directly mobilize and activate human eosinophils
Authors: Svensson Lena , Rudin Anna , Wennerås Christine
Published: April 2004

Allergic diseases are characterized by the presence of eosinophils, which are recruited to the affected tissues by chemoattractants produced by T cells, mast cells and epithelium. Our objective was to evaluate if allergens can directly activate human eosinophils. The capacity of purified allergen extracts to elicit eosinophil chemotaxis, respiratory burst, degranulation and up‐regulationof the adhesion molecule complement receptor 3 (CR3) was determined in eosinophils isolated from healthy blood donors. Eosinophils stimulated with an extract from house dust mite (HDM) released thegranule protein major basic protein (MBP) and up‐regulated the surface expression of CR3. Cat allergen extracts also induced the up‐regulation of CR3, but not the release of MBP; instead cat, as well as birch and grass allergens, elicited the release of eosinophil peroxidase (EPO). In addition, grass pollen extract caused the secretion of MBP. None of the allergens stimulated eosinophilic cationic protein release, nor production of free oxygen radicals. Both HDM and birch extracts were chemotactic for eosinophils. These findings establish that common aeroallergens can directly activate eosinophils in vitro. We propose that eosinophil activation in vivo is not exclusively mediated by cytokines and chemokines of the allergic inflammatory reaction, but could partly be theresult of direct interaction between allergens and eosinophils.
[{Zn(enMe)2}2(enMe)2{Zn2As8V12O40(H2O)}]·4H2O: A Hybrid Molecular Material Based on Covalently Linked Inorganic Zn−As−V Clusters and Transition Metal Complexes via enMe Ligands
Authors: Zheng Shou‐Tian , Zhang Jie , Yang Guo‐Yu
Published: May 2004

A novel zinc‐substituted polyoxovanadate, [{Zn(enMe)2}2(enMe)2{Zn2As8V12O40(H2O)}]·4H2O 1 (enMe = 1,2‐diaminopropane), which is built up from Zn2As8V12O40(H2O) clusters and Zn(enMe)2 complexes, and further connected together by trans‐enMe ligands, has been hydrothermally prepared and characterized by X‐ray crystallography. The study of the magnetic susceptibility of 1 demonstrates the presence of antiferromagnetic interaction between VIV cations in 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Designed Assembly of Low‐dimensional Molecular Units: Novel Neutral Coordination Polymers Based on (Phosphonodithioato)NiII Complexes
Authors: Aragoni M. Carla , Arca Massimiliano , Champness Neil R. , Chernikov Aleksey V. , Devillanova Francesco A. , Isaia Francesco , Lippolis Vito , Oxtoby Neil S. , Verani Gaetano , Vatsadze Sergey Z. , Wilson Claire
Published: May 2004

The reactions of phosphonodithioato complexes [Ni(ROdtp)2] [where ROdtp = (4‐MeOPh)(RO)PS2; R = Et, Me] with 4,4′‐bipy and N,N′‐bis‐(3‐pyridinylmethylene)benzene‐1,4‐diamine (bdpy), respectively, yield the 1:1 coordination polymers [Ni(EtOdtp)2(bipy)]8 and [Ni(MeOdtp)2(bdpy)]∞, whose syntheses and single‐crystal X‐ray diffraction analyses are reported. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Clear‐Cut Lanthanide(III)/Actinide(III) Differentiation in Coordination of Pyrazine to Tris(cyclopentadienyl) Complexes of Cerium and Uranium, Involving Reversible UIII → UIV Oxidation
Authors: Mehdoui Thouraya , Berthet Jean‐Claude , Thuéry Pierre , Ephritikhine Michel
Published: May 2004

In contrast to the [Ce(C5H4R)3] complexes (where R = tBu, SiMe3), which react with pyrazine to give the Lewis base adducts [Ce(C5H4R)3(pyz)] (where R = tBu 1, SiMe3 2), the uranium analogues are oxidized by the azine molecule to the dinuclear UIV complexes [{U(C5H4R)3}2(μ‐pyz)] (R = tBu 3, SiMe3 4). The U−N distances of approximately 2.32 Å in the crystal structures of 3 and 4 are characteristic of UIV−N bond lengths of terminally‐coordinated amide groups. The formation constants of 1 and 3 in THF at 23 °C are 0.28(6) and 8(1) × 103, respectively, permitting the clear differentiation between the two metallocenes by means of the nitrogen ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Quantification of linolenic acid isomers by gas chromatography‐mass spectrometry and deconvolution of overlapping chromatographic peaks
Authors: Mjøs Svein A.
Published: May 2004

The use of a technique for deconvolution of overlapping chromatographic peaks, Gentle, has been evaluated for quantification of alpha linolenic acid isomers analysed by gas chromatography‐mass spectrometry. Mixtures containing varying amounts of linolenic acid methyl ester isomers with two or three trans double bonds were analysed by two different temperature programs. Overlapping chromatographic peaks were resolved by Gentle, and the areas of the resolved peaks were compared with reference values calculated by use of internal standards. The results show that the small differences that exist between the mass spectra of the analysed isomers are sufficient to achieve deconvolution of severely overlapping peaks. The errors were larger than seen for quantification of chromatographically resolved peaks. Especially for small peaks in a peak cluster, the errors relative to the peak size were large.
Characterization of oils of hazelnuts from Asturias, Spain
Authors: Bada Juan Carlos , León‐Camacho Manuel , Prieto Manuela , Alonso Leocadio
Published: May 2004

Nine varieties of virgin hazelnut oil from different autochthonous cultivars from distinct locations in Asturias (Spain) were obtained by extraction under a pressure of 280 kg/cm2 at a temperature of 45 °C. The extracted oils were separated and filtered. The overall composition (percentages of husk, oil and moisture) of unhusked seeds was determined as well as moisture, ash, total sulfur and heat power of the husks for their possible use as biomass. Recovery of the oil extraction procedure for its application to the production of extra virgin edible hazelnut oil was studied. Fatty acid, tocopherol and sterol compositions as determined by capillary column gas chromatography and triglyceride compositions as determined by high performance liquid chromatography are reported in this study. All values were compared with a Turkish and a French hazelnut oil, with solvent‐extracted hazelnut oil and with a 75/25 blend. A cluster analysis was performed as a criterion to differentiate the different hazelnut oils as groups.
Childhood obesity: time for treatment or prevention?
Authors: Koletzko Berthold
Published: May 2004

No abstracts.
An unsteady multiblock multigrid scheme for lifting forward flight rotor simulation
Authors: Allen C. B.
Published: May 2004

Numerical simulation of multi‐bladed lifting rotors in forward flight is considered. The flow‐solver presented is multiblock and unsteady, which is essential for forward flight, and also includes multigrid acceleration to reduce run‐times. A structured multiblock grid generator specifically for rotor blades has also been developed and is presented here. Previous work has shown that hovering lifting rotor flows are particularly expensive to simulate, since the capture of the vortical wake below the disc requires a long numerical integration time; more than 20 revolutions for an unsteady simulation, or more than 40000 time‐steps for a single grid steady simulation. It is demonstrated here that only two or three revolutions are required to obtain a converged solution for forward flight, since the wake is swept downstream. This requires less than 1.5 × the run‐time of a steady hovering simulation, for the same grid density around each blade, even though an unsteady simulation is required and the complete disk must be solved rather than one blade as in hover. It is demonstrated that very fine meshes are required to capture the unsteady tip vortex motion, and the effects on blade loading of blade‐vortex interaction and rotor shaft inclination are also considered. Copyright © 2004 John Wiley & Sons, Ltd.
Generalized Fourier analyses of the advection–diffusion equation—Part I: one‐dimensional domains
Authors: Christon Mark A. , Martinez Mario J. , Voth Thomas E.
Published: May 2004

This paper presents a detailed multi‐methods comparison of the spatial errors associated with finite difference, finite element and finite volume semi‐discretizations of the scalar advection–diffusion equation. The errors are reported in terms of non‐dimensional phase and group speed, discrete diffusivity, artificial diffusivity, and grid‐induced anisotropy. It is demonstrated that Fourier analysis provides an automatic process for separating the discrete advective operator into its symmetric and skew‐symmetric components and characterizing the spectral behaviour of each operator. For each of the numerical methods considered, asymptotic truncation error and resolution estimates are presented for the limiting cases of pure advection and pure diffusion. It is demonstrated that streamline upwind Petrov–Galerkin and its control‐volume finite element analogue, the streamline upwind control‐volume method, produce both an artificial diffusivity and a concomitant phase speed adjustment in addition to the usual semi‐discrete artifacts observed in the phase speed, group speed and diffusivity. The Galerkin finite element method and its streamline upwind derivatives are shown to exhibit super‐convergent behaviour in terms of phase and group speed when a consistent mass matrix is used in the formulation. In contrast, the CVFEM method and its streamline upwind derivatives yield strictly second‐order behaviour. In Part II of this paper, we consider two‐dimensional semi‐discretizations of the advection–diffusion equation and also assess the affects of grid‐induced anisotropy observed in the non‐dimensional phase speed, and the discrete and artificial diffusivities. Although this work can only be considered a first step in a comprehensive multi‐methods analysis and comparison, it serves to identify some of the relative strengths and weaknesses of multiple numerical methods in a common analysis framework. Published in 2004 by John Wiley & Sons, Ltd.
Boundary‐fitted non‐linear dispersive wave model for regions of arbitrary geometry
Authors: Beji S. , Barlas B.
Published: May 2004

A vertically integrated non‐linear dispersive wave model is expressed in non‐orthogonal curvilinear co‐ordinate system for simulating shallow or deep water wave motions in regions of arbitrary geometry. Both dependent and independent variables are transformed so that an irregular physical domain is converted into a rectangular computational domain with contravariant velocities. Thus, the wall condition for enclosures surrounding a typical physical domain, such as a channel, port or harbor, is satisfied accurately and easily. The numerical scheme is based on staggered grid finite‐difference approximations, which result in implicit formulations for the momentum equations and semi‐explicit formulation for the continuity equation. Test cases of linear wave propagation in converging, diverging and circular channels are performed to check the reliability of model simulations against the analytical solutions. Cnoidal waves of different steepness values in a circular channel are also considered as examples to non‐linear wave propagation within curved walls. In closing, remarks concerning versatility and practical uses of the numerical model are made. Copyright © 2004 John Wiley & Sons, Ltd.
Evaluation of an energy relaxation method for the simulation of unsteady, viscous, real gas flows
Authors: Bongiovanni Emmanuel , Ern Alexandre , Glinsky‐Olivier Nathalie
Published: May 2004

This study investigates a new energy relaxation method designed to capture the dynamics of unsteady, viscous, real gas flows governed by the compressible Navier–Stokes equations. We focus on real gas models accounting for inelastic molecular collisions and yielding temperature‐dependent heat capacities. The relaxed Navier–Stokes equations are discretized using a mixed finite volume/finite element method and a high‐order time integration scheme. The accuracy of the energy relaxation method is investigated on three test problems of increasing complexity: the advection of a periodic set of vortices, the interaction of a temperature spot with a weak shock, and finally, the interaction of a reflected shock with its trailing boundary layer in a shock tube. In all cases, the method is validated against benchmark solutions and the numerical errors resulting from both discretization and energy relaxation are assessed independently. Copyright © 2004 John Wiley & Sons, Ltd.
On the discontinuous Galerkin method for the numerical solution of the Navier–Stokes equations
Authors: Dolejší Vít
Published: May 2004

The paper deals with the use of the discontinuous Galerkin finite element method (DGFEM) for the numerical solution of viscous compressible flows. We start with a scalar convection–diffusion equation and present a discretization with the aid of the non‐symmetric variant of DGFEM with interior and boundary penalty terms. We also mention some theoretical results. Then we extend the scheme to the system of the Navier–Stokes equations and discuss the treatment of stabilization terms. Several numerical examples are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Cubic eddy‐viscosity turbulence models for strongly swirling confined flows with variable density
Authors: Yang Xiaodong , Ma Huiyang
Published: May 2004

An investigation on the predictive performance of cubic eddy‐viscosity turbulence models for strongly swirling confined flows with variable density is presented. Comparisons of the prediction with the experiments show some improvements of cubic models over the linear k–ε model. The linear k–ε model does not contain any mechanism to represent the interaction of swirl and density variation and as a consequence it performs poorly. With appropriate modelling, two‐equation cubic turbulence models can capture the subcritical nature of the flow, represent the azimuthal velocity profiles of combined forced‐free vortex motion, and predict the combined effects of swirl and density variation fairly well. However, the calibration of model coefficients is still a topic of investigation. Further amendments are also needed for the equations of k and ε to take into account the effects of swirl and density gradients correctly. Copyright © 2004 John Wiley & Sons, Ltd.
Head and neck tumor sites differ in prevalence and spectrum of p53 alterations but these have limited prognostic value
Authors: Bosch Franz X. , Ritter Daniel , Enders Christel , Flechtenmacher Christa , Abel Ulrich , Dietz Andreas , Hergenhahn Manfred , Weidauer Hagen
Published: May 2004

The tumor site is a strong clinical factor in head and neck squamous cell carcinoma (HNSCC). To clarify the biologic and clinical role of p53 alterations in HNSCC, we have examined the prevalence and the nature of p53 alterations in a large cohort of tumors from the different sites. For immunohistochemical analysis of p53 protein expression, we introduced tyramide signal amplification immunohistochemistry (TSA‐IHC) on a tissue microarray. This allowed the discrimination between normal low‐level expression and reduced or lost expression. Two hundred fifty‐three tumors were subjected to mutational analysis by genomic DNA sequencing, employing also the p53 GeneChip from Affymetrix. The prevalence of all p53 alterations, i.e., mutations, overexpression and loss of expression, was significantly higher in hypopharyngeal tumors than in the other sites (p = 0.001). Laryngeal tumors showed the lowest rate of p53 alterations, but revealed a distinct mutation spectrum: most mutations affected exon 5 (p = 0.013) and the S2′ domain (p = 0.002), and most hot‐spot 248 mutations occurred in the larynx (p < 0.001). Sequencing by p53GeneChip technology was shown to be only insignificantly more sensitive than dideoxy sequencing. In agreement with p53 mutations occurring prior to invasiveness, their prevalence did not increase with tumor stage, and all mutation classes lacked prognostic significance. The large patient cohort of this study showed that p53 is differentially affected in the different tumor sites of the head and neck, but its mode of inactivation does not play a major role in tumor progression. © 2004 Wiley‐Liss, Inc.
National Polyp Study data: Evidence for regression of adenomas
Authors: Loeve Franka , Boer Rob , Zauber Ann G. , van Ballegooijen Marjolein , van Oortmarssen Gerrit J. , Winawer Sidney J. , Habbema J. Dik F.
Published: May 2004

The data of the National Polyp Study, a large longitudinal study on surveillance of adenoma patients, is used for testing assumptions on the adenoma‐carcinoma sequence. The observed adenoma and colorectal cancer incidence in the National Polyp Study were compared with the simulated outcomes of the MISCAN‐COLON model of epidemiology and control of colorectal cancer for the U.S. population based on expert opinion. Variants of this model were explored in order to identify assumptions on the adenoma‐carcinoma sequence that are consistent with the study observations. The high observed adenoma detection rates at surveillance and low observed colorectal cancer incidence in the National Polyp Study could only be explained by assuming a high incidence rate of adenomas accompanied by regression of adenomas. The National Polyp Study data suggest that adenoma prevalence results from a dynamic process of both formation as well as regression of adenomas. This lowers the expectations for the effects of colorectal cancer screening strategies that focus on adenoma detection. © 2004 Wiley‐Liss, Inc.
Allelic loss but absence of mutations in the polyspecific transporter gene BWR1A on 11p15.5 in hepatoblastoma
Authors: Albrecht Steffen , Hartmann Wolfgang , Houshdaran Farzad , Koch Arend , Gärtner Barbara , Prawitt Dirk , Zabel Bernhard U. , Russo Pierre , von Schweinitz Dietrich , Pietsch Torsten
Published: May 2004

Chromosomal region 11p15.5 shows frequent maternal allelic loss in embryonal tumors, including rhabdomyosarcoma (RMS), Wilms' tumor (WT) and hepatoblastoma (HB), consistent with the presence of at least one tumor suppressor gene in this region, which should be paternally imprinted, i.e., expressed from the maternal allele only. The BWR1A gene encodes a polyspecific transmembrane transporter and is located on 11p15.5. It is highly expressed in liver, paternally imprinted and was found to be mutated in an RMS cell line, making it a plausible tumor suppressor gene for HB. We therefore screened 62 HBs, 3 HB cell lines and 1 pediatric hepatocellular carcinoma for BWR1A mutations using single‐strand conformation polymorphism analysis. Allelic loss on 11p15.5 was assessed by PCR‐based microsatellite analysis in 56 of the cases for which constitutional DNA was available. BWR1A mRNA expression was determined in 14 HBs by differential RT‐PCR of matched cDNA samples from tumor and normal liver. Western blot analysis was performed on 4 tumors and matching normal liver tissue. Except for sequence polymorphisms (in exons 2, 3 and 10 as well as in introns 6 and 7), no mutations were found. Thirteen HBs (23%) had allelic loss on 11p15.5; this included BWR1A in 12 but it was telomeric to BWR1A in 1. Expression of BWR1A mRNA was reduced in 11 out of 14 cases by 19—92%, independent from allelic loss of 11p15.5. By Western blot analysis, all 4 tumors and matching liver samples displayed a 48–51 kd band corresponding to BWR1A. These results make it unlikely that BWR1A is the target of the allelic deletions in HB. However, similar to the putative 11p15.5 tumor suppressor H19, BWR1A appears to be reduced in expression. Reduced expression in the absence of mutations may contribute to HB development; however, to understand the significance of this finding will require further studies on the function of BWR1A, specifically its role in liver development. © 2004 Wiley‐Liss, Inc.
Biomarkers of dietary fatty acid intake and the risk of breast cancer: A meta‐analysis
Authors: Saadatian‐Elahi Mitra , Norat Teresa , Goudable Joëlle , Riboli Elio
Published: May 2004

The use of the fatty acid composition of adipose tissue, erythrocyte membranes, serum and plasma as biological markers of fatty acid intake was recently introduced in epidemiological studies. The biomarkers of fatty acid intake have the advantage of providing quantitative measurement independent of energy intake and of the subject's memory. We performed a meta‐analysis of published results of epidemiological studies of the composition of fatty acids in biological samples and breast cancer risk. The analysis was based on 3 cohort and 7 case‐control studies including 2,031 cases and 2,334 controls. The summary statistic used was the average of the relative risk estimated for each level of the fatty acid on study, weighted by the inverse of its variance. Random effect models were assumed when the test for heterogeneity was significant. Overall relative risks were estimated for studies including pre‐ and post‐menopausal breast cancer and separately for post‐menopausal women. In cohort studies, a significant protective effect was found for total n‐3 polyunsaturated fatty acids, while total monounsaturated fatty acids, oleic acid (C18:1 n‐9c) and palmitic acid (C16:0) were significantly associated with an increase of breast cancer risk. Total saturated fatty acids were significantly associated with breast cancer risk in cohort studies only in postmenopausal women. For case‐control studies, the only finding was for alpha linolenic acid (C18:3, n‐3), which showed an inverse association bordering on statistical significance. The findings of cohort studies fit well with hypotheses derived from experimental animal studies. More epidemiological cohort studies that integrate biological markers of dietary fatty acid intake are needed in order to determine the contribution of different types of fatty acids in the etiology of breast cancer. © 2004 Wiley‐Liss, Inc.
Variability of southeastern Queensland rainfall and climate indices
Authors: Murphy Bradley F. , Ribbe Joachim
Published: May 2004

The variability of climate indices and rainfall in southeastern (SE) Queensland (Qld) is studied. Using high‐resolution gridded rainfall data for all of Australia and global sea‐surface temperatures (SSTs), the relationship between Australia‐wide rainfall (and in SE Qld in particular) and SST indices and the southern oscillation index (SOI) have been investigated. It is found that SE Qld is more subject to the breakdown of correlations between the SOI and rainfall than any other part of Australia. Model predictions suggest that this is probable in the future.

Considering only time scales longer than interannual, it was found that SSTs in the central tropical Pacific Ocean (TPO; represented by the Niño‐4 index) correlated best with SE Qld rainfall. Eastern TPO (Niño‐3) SSTs and the SOI produced successively weaker correlations. The time series of the second modes of variability of SSTs over the Pacific and Indian Oceans were shown to have limited impact on SE Qld rainfall variability.

The data were split into periods before and after 1946, when Australian mean rainfall changed. Whereas the SOI correlations with rainfall in SE Australia were similar in both periods, in SE Qld the correlations were very weak in the earlier period (0.06) but very strong in the later period (0.72). The Niño‐4 index correlated better than the Niño‐3 index in both periods, but both indexes showed smaller changes from the earlier to the later periods than the SOI. Copyright © 2004 Royal Meteorological Society.
On the role of statistics in climate research
Authors: Zwiers Francis W. , von Storch Hans
Published: May 2004

We review the role of statistical analysis in the climate sciences. Special emphasis is given to attempts to construct dynamical knowledge from limited observational evidence, and to the ongoing task of drawing detailed and reliable information on the state, and change, of climate that is needed, for example, for short‐term and seasonal forecasting. We conclude with recommendations of how to improve the practice of statistical analysis in the climate sciences by drawing more efficiently on relevant developments in statistical mathematics. Copyright © 2004 Environment Canada. Published by John Wiley & Sons, Ltd.
An agricultural drought risk‐assessment model for corn and soybeans
Authors: Wu Hong , Hubbard Kenneth G. , Wilhite Donald A.
Published: May 2004

An agricultural drought risk‐assessment model was developed for Nebraska, USA, for corn and soybeans on the basis of variables derived from the standardized precipitation index and crop‐specific drought index using multivariate techniques. This model can be used to assess real‐time agricultural drought risk for specific crops at critical times before and during the growing season by retaining previous, and adding current, weather information as the crops pass through the various development stages. This model will be helpful to decision makers, ranging from agricultural producers to policy makers and from local to national levels.

The results of the model validation using three different datasets show that the risk‐assessment accuracy improves as the crop develops. At the end of April, before corn is planted, the average assessment accuracy rate of drought risks on final yield is 60%. At the beginning of July, when corn is at the vegetative stage, the average assessment accuracy rate reaches 76%. In late July, when corn is at the ovule stage, the rate increases to 85%. The rates are 89% in the second half of August and the end of September, when corn is at the reproduction and ripening stages respectively. The model assessment accuracy for soybeans is lower than that for corn at the same growth stages because weather has less impact on soybeans than on corn. A reliable assessment, with 80% assessment accuracy rate, begins at mid‐August, when soybeans are at pod formation stage. In early September and October, when soybeans are at pod fill and ripening stages respectively, the model is able to assess risks on soybean yield with 83% and 81% accuracy rates respectively. Copyright © 2004 Royal Meteorological Society