bluuebunny/crossref_metadata_2025_split huggingface dataset:
Composition distributions within poly(vinylidene fluoride) spherulites as grown in blends with poly(methyl methacrylate)
Authors: Liu Jieping , Jungnickel Bernd‐Joachim 
Published: November 2005

AbstractUpon crystalline solidification of one component in a homogeneously molten polymer blend, composition profiles develop outside (i.e., in the rest melt) and behind (i.e., within the spherulites) the crystal growth front. The present article is devoted to the detailed verification and the interpretation of these distributions and their temporal development inside growing spherulites. To this end, the energy dispersive X‐ray emission (EDX) of suitable elements has been recorded locally resolved in a scanning electron microscope and evaluated correspondingly. The investigations were performed at the melt homogeneous blend of poly(vinylidene fluoride) (PVDF) as crystallizing and poly(methyl methacrylate) (PMMA) as steadily amorphous component. If the spherulites are not volume filling, the mean PMMA content 〈ϕPMMA〉 inside the PVDF spherulites is for all blends about 0.2 below the starting composition. ϕPMMA increases however slightly from the center of a spherulite to its border. That increase reflects the PMMA concentration in front of the spherulite surface, which increases likewise with time, and is clearly above the initial composition. There is at the spherulite surface, consequently, a remarkable jump in composition from the spherulite internal to its amorphous surroundings. It may amount up to 0.5. With volume filling spherulites, a slight variation of the composition from the center of a spherulite to its border is observed, too. This proves that also at these conditions composition profiles develop in the spherulite's surroundings. They remain however so weak that they do not inhibit crystallization even in its later stages. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 338–346, 2006
Meshless simulation of equilibrium swelling/deswelling of pH‐sensitive hydrogels
Authors: Wang Q. X. , Li H. , Lam K. Y. 
Published: November 2005

AbstractHydrogels have been widely used in microelectromechanical systems (MEMS) and Bio‐MEMS devices. In this article, the equilibrium swelling/deswelling of the pH‐stimulus cylindrical hydrogel in the microchannel is studied and simulated by the meshless method. The multi‐field coupling model, called multi‐effect‐coupling pH‐stimulus (MECpH) model, is presented and used to describe the chemical field, electric field, and the mechanical field involved in the problem. The partial differential equations (PDEs) describing these three fields are either nonlinear or coupled together. This multi‐field coupling and high nonlinear characteristics produce difficulties for the conventional numerical methods (e.g., the finite element method or the finite difference method), so an alternative—meshless method is developed to discretize the PDEs, and the efficient iteration technique is adopted to solve the nonlinear problem. The computational results for the swelling/deswelling diameter of the hydrogel under the different pH values are firstly compared with experimental results, and they have a good agreement. The influences of other parameters on the mechanical properties of the hydrogel are also investigated in detail. It is shown that the multi‐field coupling model and the developed meshless method are efficient, stable, and accurate for simulation of the properties of the stimuli‐sensitive hydrogel. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 326–337, 2006
Evaluation of Bi–W‐oxides for visible light photocatalysis
Authors: Finlayson A. P. , Tsaneva V. N. , Lyons L. , Clark M. , Glowacki B. A. 
Published: November 2005

AbstractPhotocatalytic solar water splitting has the potential to become a low‐carbon source of hydrogen fuel over the coming decades if the issue of low visible light absorption can be addressed without sacrificing chemical stability. We report on an investigation into the potential of the Bi–W‐oxides, Bi2WO6 and Bi6WO12, as visible light photocatalysts. X‐ray diffraction and Raman spectroscopy have been used to assess the structure of the oxides, whilst UV–vis diffuse reflectance spectroscopy analysed with the Kubelka–Munk function has been used to identify their optical band gaps. It has been revealed that Bi6WO12 shows significantly higher optical absorption in the region above 440 nm than either Bi2O3 or WO3, raising the possibility of enhanced photocatalytic activity under solar illumination. Bi2WO6 has a marginally lower band gap at 2.59 eV than Bi2O3 or WO3 but the results reported herein raise doubts concerning its chemical stability under aqueous, illuminated conditions for protracted periods of time. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of Cox's and relative survival models when estimating the effects of prognostic factors on disease‐specific mortality: a simulation study under proportional excess hazards
Authors: Teuff Gwenaël Le , Abrahamowicz Michal , Bolard Philippe , Quantin Catherine 
Published: November 2005

AbstractIn many prognostic studies focusing on mortality of persons affected by a particular disease, the cause of death of individual patients is not recorded. In such situations, the conventional survival analytical methods, such as the Cox's proportional hazards regression model, do not allow to discriminate the effects of prognostic factors on disease‐specific mortality from their effects on all‐causes mortality. In the last decade, the relative survival approach has been proposed to deal with the analyses involving population‐based cancer registries, where the problem of missing information on the cause of death is very common. However, some questions regarding the ability of the relative survival methods to accurately discriminate between the two sources of mortality remain open. In order to systematically assess the performance of the relative survival model proposed by Esteveet al., and to quantify its potential advantages over the Cox's model analyses, we carried out a series of simulation experiments, based on the population‐based colon cancer registry in the French region of Burgundy. Simulations showed a systematic bias induced by the ‘crude’ conventional Cox's model analyses when individual causes of death are unknown. In simulations where only about 10 per cent of patients died of causes other than colon cancer, the Cox's model over‐estimated the effects of male gender and oldest age category by about 17 and 13 per cent, respectively, with the coverage rate of the 95 per cent CI for the latter estimate as low as 65 per cent. In contrast, the effect of higher cancer stages was under‐estimated by 8–28 per cent. In contrast to crude survival, relative survival model largely reduced such problems and handled well even such challenging tasks as separating the opposite effects of the same variable on cancer‐relatedversusother‐causes mortality. Specifically, in all the cases discussed above, the relative bias in the estimates from the Esteveet al.'s model was always below 10 per cent, with the coverage rates above 81 per cent. Copyright © 2005 John Wiley & Sons, Ltd.
Sample size calculations for a split‐cluster, beta‐binomial design in the assessment of toxicity
Authors: Hendriks J. C. M. , Teerenstra S. , Punt‐Van der Zalm J. P. E. , Wetzels A. M. M. , Westphal J. R. , Borm G. F. 
Published: November 2005

AbstractMouse embryo assays are recommended to test materials used for in vitro fertilization for toxicity. In such assays, a number of embryos is divided in a control group, which is exposed to a neutral medium, and a test group, which is exposed to a potentially toxic medium. Inferences on toxicity are based on observed differences in successful embryo development between the two groups. However, mouse embryo assays tend to lack power due to small group sizes. This paper focuses on the sample size calculations for one such assay, the Nijmegen mouse embryo assay (NMEA), in order to obtain an efficient and statistically validated design. The NMEA follows a stratified (mouse), randomized (embryo), balanced design (also known as a split‐cluster design). We adopted a beta‐binomial approach and obtained a closed sample size formula based on an estimator for the within‐cluster variance. Our approach assumes that the average success rate of the mice and the variance thereof, which are breed characteristics that can be easily estimated from historical data, are known. To evaluate the performance of the sample size formula, a simulation study was undertaken which suggested that the predicted sample size was quite accurate. We confirmed that incorporating the a priori knowledge and exploiting the intra‐cluster correlations enable a smaller sample size. Also, we explored some departures from the beta‐binomial assumption. First, departures from the compound beta‐binomial distribution to an arbitrary compound binomial distribution lead to the same formulas, as long as some general assumptions hold. Second, our sample size formula compares to the one derived from a linear mixed model for continuous outcomes in case the compound (beta‐)binomial estimator is used for the within‐cluster variance. Copyright © 2005 John Wiley & Sons, Ltd.
Testing independence between two Poisson‐generated multinomial variables in case‐series and cohort studies
Authors: Hocine Mounia , Guillemot Didier , Tubert‐Bitter Pascale , Moreau Thierry 
Published: November 2005

AbstractIn case‐series or cohort studies, we propose a test of independence between the occurrences of two types of recurrent events (such as two repeated infections) related to an intermittent exposure (such as an antibiotic treatment). The test relies upon an extension of a recent method for analysing case‐series data, in the presence of one type of recurrent event. The test statistic is derived from a bivariate Poisson generated‐multinomial distribution. Simulations for checking the validity of the test concerning the type I error and the power properties are presented. The test is illustrated using data from a cohort on antibiotics bacterial resistance in schoolchildren. Copyright © 2005 John Wiley & Sons, Ltd.
Dynamic balancing randomization in controlled clinical trials
Authors: Heritier Stephane , Gebski Val , Pillai Avinesh 
Published: November 2005

AbstractIn the design of randomized clinical trials, balancing of treatment allocation across important prognostic factors (strata) improves the efficiency of the final comparisons. Whilst randomization methods exist which attempt to balance treatments across the strata (permuted blocks, minimization, biased coin), these approaches assign equal importance for all the strata. Dynamic balancing randomization (DBR) is a tree‐based method proposed by Signoriniet al. allowing different levels of imbalance in different strata which ensures a balance for each level of prognostic risk factors (conditional balance) whilst at the same time preserving randomness. We present a simple modification to the original approach to maintain a marginal balance over important strata and examine the properties of this modification. Two important measures of performance are used to provide comparisons between the approaches: a loss function, which can be interpreted as the squared norm of the imbalance vector, and a forcing index which conveys the degree of randomness. A comparison of DBR with minimization and a biased coin design is carried out by simulation on two simulated trials. Copyright © 2005 John Wiley & Sons, Ltd.
A Bayesian approach to jointly estimate centre and treatment by centre heterogeneity in a proportional hazards model
Authors: Legrand Catherine , Ducrocq Vincent , Janssen Paul , Sylvester Richard , Duchateau Luc 
Published: November 2005

AbstractWhen multicentre clinical trial data are analysed, it has become more and more popular to look for possible heterogeneity in outcome between centres. However, beyond the investigation of such heterogeneity, it is also interesting to consider heterogeneity in treatment effect over centres. For time‐to‐event outcomes, this may be investigated by including a random centre effect and a random treatment by centre interaction in a Cox proportional hazards model.Assuming independence between the random effects, we propose a Bayesian approach to fit our proposed model. The parameters of interest are the variance components σ and σ of these random effects, which can be interpreted as a measure of centre and treatment effect over centres heterogeneity of the hazard. These variance components are estimated from their marginal posterior density after integrating out the fixed treatment effect and the random effects. As this integration cannot be performed analytically, the marginal posterior density is approximated using the Laplace integration technique. Statistical inference is then based on the characteristics of the posterior marginal density, such as the mode and the standard deviation. We demonstrate the proposed technique using data from a pooled database of seven EORTC bladder cancer clinical trials. Substantial centre and treatment effect over centres heterogeneity in disease‐free interval was found. Copyright © 2005 John Wiley & Sons, Ltd.
Metopic suture in fetuses with Apert syndrome at 22–27 weeks of gestation
Authors: Faro C. , Chaoui R. , Wegrzyn P. , Levaillant J. M. , Benoit B. , Nicolaides K. H. 
Published: November 2005

AbstractObjectivesTo examine the possible association of skull deformity and the development of the cranial sutures in fetuses with Apert syndrome.MethodsThree‐dimensional (3D) ultrasound was used to examine the metopic and coronal sutures in seven fetuses with Apert syndrome at 22–27 weeks of gestation. The gap between the frontal bones in the transverse plane of the head at the level of the cavum septi pellucidi was measured and compared to findings in 120 anatomically normal fetuses undergoing routine ultrasound examination at 16–32 weeks.ResultsIn the normal group, the gap between the frontal bones in the metopic suture at the level of the cavum septi pellucidi, decreased significantly with gestation from a mean of 2.2 mm (5th and 95th centiles: 1.5 mm and 2.9 mm) at 16 weeks to 0.9 mm (5th and 95th centiles: 0.3 mm and 1.6 mm) at 32 weeks. In the seven cases with Apert syndrome, two‐dimensional ultrasound examination demonstrated the characteristic features of frontal bossing, depressed nasal bridge and bilateral syndactyly. On 3D examination there was complete closure of the coronal suture and a wide gap in the metopic suture (15–23 mm).ConclusionIn normal fetuses, cranial bones are believed to grow in response to the centrifugal pressure from the expanding brain and proximity of the dura to the suture is critical in maintaining its patency. In Apert syndrome, the frontal bossing may be a mere consequence of a genetically predetermined premature closure of the coronal suture. Alternatively, there is a genetically predetermined deformation of the brain, which in turn, through differential stretch of the dura in the temporal and frontal regions, causes premature closure of the coronal suture and impaired closure of the metopic suture. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Gasdruckschwingungen und Strömungsgeräusche in Druckbegrenzungsventilen und Rohrleitungen. Pneumatic oszillations and current noises in pressure control valves
Authors: Surek Dominik , Stempin Silke 
Published: November 2005

AbstractZur Begrenzung zulässiger Drücke in Verdichter‐ und Pumpenanlagen werden Druckbegrenzungsventile oder Sicherheitsventile eingesetzt. Beim Erreichen des zulässigen Druckes öffnen die Ventile und blasen den geförderten Luftvolumenstrom in die Umgebung oder das geförderte Gas in einen drucklosen Behälter ab. Dadurch kann die nachfolgende Anlage und die zugehörigen Geräte vor unzulässig hohem Druck oder vor einem zu hohen Vakuum geschützt werden. Druckbegrenzungsventile und Sicherheitsventile werden in der Regel in der gleichen Nennweite der Druck‐ bzw. Saugstutzen der Verdichter ausgeführt. Dadurch treten Umlenkungen und Wirbelgebiete auf, die zu Strömungsgeräuschen führen können. Um die Strömungsgeräusche in Druckbegrenzungsventilen zu senken, werden im folgenden Beitrag die Gasdruckschwingungen, die Schalldruckschwingungen und die Schalldruckpegel solcher Ventile untersucht und ausgemessen.
Zur Kompression von Klassischen Turbo‐Molekularpumpen. On the compression in classical turbomolecular pumps
Authors: Voss Gerhard 
Published: November 2005

AbstractIn diesem Artikel wird ein für die Praxis nützliches Modell vorgestellt, das es erlaubt, die Kompressions‐Kurven einer Klassischen Turbo‐Molekularpumpe zu berechnen und systematisch zu analysieren.Das Modell basiert auf einer einfachen Differentialgleichung für den Druck als Funktion des Ortes im Inneren der Turbo‐Molekularpumpe. Die Lösung dieser Differentialgleichung ermöglicht sowohl die Berechnung der Kompressions‐Kurven bei endlichem Gas‐Durchsatz (Q > 0) als auch die Berechnung des Druck‐Verlaufs im Inneren der Turbo‐Molekularpumpe.Es wird die Hypothese aufgestellt, dass die Kompressions‐Kurve für Gas‐Durchsatz Null aus einer Kompressions‐Kurve bei endlichem Gas‐Durchsatz – z. B. Q = 1 sccm – errechnet werden kann.Der Vergleich mit experimentellen Daten zeigt, dass das vorgestellte Modell eine exzellente qualitative und quantitative Beschreibung der beobachteten Phänomene liefert.
A bi-dimensional approach to assessing the volumetric evolution of an exploited sandbank
Authors: Norro Alain , Pichot Georges , Pison Virginie , Ozer José 
Published: November 2005

Abstract
We analyse the multi-annual evolution of bathymetry along several cross-sections of the Kwintebank (one of the Flemish Banks). An important issue in the area is the intensive exploitation under regulations imposed by the Belgian authorities that aim to guarantee sustainability of extractions. All bathymetric data collected during the period 1987–2000 at a frequency of approximately four surveys per year are analysed, to identify volumetric temporal trends. The errors inherent in the measurements taken with a single-beam instrument are examined. The lack of indisputable quality criteria led to the choice of robust statistical methods. A statistically significant annual decline of approximately 1.5% in bank volume is shown. Another practical conclusion is that a big increase in sampling frequency is necessary if the authorities set a criterion regarding the long-term sustainability of the bank and wish to have a swift guarantee that this criterion is being observed.
Differential inhibitory effects of methylmalonic acid on respiratory chain complex activities in rat tissues
Authors: Pettenuzzo Leticia F. , Ferreira Gustavo da C. , Schmidt Anna Laura , Dutra‐Filho Carlos S. , Wyse Angela T.S. , Wajner Moacir 
Published: November 2005

AbstractMethylmalonic acidemia is an inherited metabolic disorder biochemically characterized by tissue accumulation of methylmalonic acid (MMA) and clinically by progressive neurological deterioration and kidney failure, whose pathophysiology is so far poorly established. Previous studies have shown that MMA inhibits complex II of the respiratory chain in rat cerebral cortex, although no inhibition of complexes I–V was found in bovine heart. Therefore, in the present study we investigated the in vitro effect of 2.5 mM MMA on the activity of complexes I–III, II, II–III and IV in striatum, hippocampus, heart, liver and kidney homogenates from young rats. We observed that MMA caused a significant inhibition of complex II activity in striatum and hippocampus (15–20%) at low concentrations of succinate in the medium, but not in the peripheral tissues. We also verified that the inhibitory property of MMA only occurred after exposing brain homogenates for at least 10 min with the acid, suggesting that this inhibition was mediated by indirect mechanisms. Simultaneous preincubation with the nitric oxide synthase inhibitor Nω‐nitro‐l‐arginine methyl ester (l‐NAME) and catalase (CAT) plus superoxide dismutase (SOD) did not prevent MMA‐induced inhibition of complex II, suggesting that common reactive oxygen (superoxide, hydrogen peroxide and hydroxyl radical) and nitric (nitric oxide) species were not involved in this effect. In addition, complex II–III (20–35%) was also inhibited by MMA in all tissues tested, and complex I–III only in the kidney (53%) and liver (38%). In contrast, complex IV activity was not changed by MMA in all tissues studied. These results indicate that MMA differentially affects the activity of the respiratory chain pending on the tissues studied, being striatum and hippocampus more vulnerable to its effect. In case our in vitro data are confirmed in vivo in tissues from methylmalonic acidemic patients, it is feasible that that the present findings may be related to the pathophysiology of the tissue damage characteristic of these patients.
The electronic harvest
Authors: SECORD JAMES 
Published: November 2005

Science in the Nineteenth-Century Periodical: An Electronic Index, v. 1.0, hriOnline <http://www.sciper.org> [accessed 30 June 2005].Geoffrey Cantor and Sally Shuttleworth (eds.), Science Serialized: Representations of the Sciences in Nineteenth-Century Periodicals. Dibner Institute Studies in the History of Science and Technology. Cambridge, MA and London: MIT Press, 2004. Pp. vi+358. ISBN 0-262-03318-6. £25.95 (hardback).Geoffrey Cantor, Gowan Dawson, Graeme Gooday, Richard Noakes, Sally Shuttleworth and Jonathan Topham (eds.), Science in the Nineteenth-Century Periodical: Reading the Magazine of Nature. Cambridge Studies in Nineteenth-Century Literature and Culture. Cambridge: Cambridge University Press, 2004. Pp. xi+329. ISBN 0-521-83637-9. £45.00 (hardback).Louise Henson, Geoffrey Cantor, Gowan Dawson, Richard Noakes, Sally Shuttleworth and Jonathan R. Topham (eds.), Culture and Science in the Nineteenth-Century Media. The Nineteenth Century Series. Aldershot: Ashgate, 2004. Pp. xxv+296. ISBN 0-7546-3574-0. £47.50 (hardback).
Review of: The rare ERBB2 variant Ile654Val is associated with an increased familial breast cancer risk
Authors: Campbell I. G. 
Published: November 2005

Citation of original article:B. Frank, K. Hemminki, M. Wirtenberger, J. L. Bermejo, P. Bugert, R. Klaes, R. K. Schmutzler, B. Wappenschmidt, C. R. Bartram, B. Burwinkel. The rare ERBB2 variant lle654Val is associated with an increased familial breast cancer risk. Carcinogenesis 2005; 26: 643–7.Abstract of the original articleOverexpression of the proto-oncogene ERBB2 (HER2/NEU) has been observed in 20–30% of breast cancers involving poor prognosis. Genetic alterations within ERBB2 have been shown to induce carcinogenesis and metastasis. We investigated eight annotated single nucleotide polymorphisms for occurrence in familial breast cancer samples. The confirmed variants Ile654Val, Ile655Val and Ala1170Pro were analysed in subsequent epidemiological studies on familial breast cancer risk. While Ala1170Pro resides within a C-terminally located regulatory domain, the two adjacent polymorphisms Ile654Val and Ile655Val are part of the transmembrane domain. A case–control study analysing a cohort of 348 German familial breast cancer cases and 960 corresponding controls showed no significant association of either Ile655Val (OR = 1.05, 95% CI = 0.82–1.34, P = 0.728) or Ala1170Pro (OR = 0.94, 95% CI = 0.74–1.20, P = 0.632) with familial breast cancer risk. Differences in haplotype frequencies between cases and controls could also not be detected. The ERBB2 variant Ile654Val, however, revealed an increased risk for carriers of the heterozygous Val654 allele (OR = 2.56, 95% CI = 1.08–6.08, P = 0.028). The rare Val654 variant is linked with the more frequent Val655, resulting in two consecutive valine instead of two isoleucine residues within the transmembrane domain. Computational analyses suggest that the Val654–Val655 allele provokes receptor dimerisation and activation, thus stimulating kinase activity and cell transformation. We hypothesise that ERBB2 Val654 represents an oncogenic variant which might, in addition, influence clinical outcome and predict a worse prognosis.