bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exploring heterogeneity in tumour data using Markov chain Monte Carlo
Authors: de Gunst Mathisca C. M. , Dewanji Anup , Luebeck E. Georg 
Published: April 2003

AbstractWe describe a Bayesian approach to incorporate between‐individual heterogeneity associated with parameters of complicated biological models. We emphasize the use of the Markov chain Monte Carlo (MCMC) method in this context and demonstrate the implementation and use of MCMC by analysis of simulated overdispersed Poisson counts and by analysis of an experimental data set on preneoplastic liver lesions (their number and sizes) in the presence of heterogeneity. These examples show that MCMC‐based estimates, derived from the posterior distribution with uniform priors, may agree well with maximum likelihood estimates (if available). However, with heterogeneous parameters, maximum likelihood estimates can be difficult to obtain, involving many integrations. In this case, the MCMC method offers substantial computational advantages. Copyright © 2003 John Wiley & Sons, Ltd.
Geographical variation, population structure and gene flow between populations of Chrysophtharta agricola (Coleoptera: Chrysomelidae), a pest of Australian eucalypt plantations
Authors: Nahrung H.F. , Allen G.R. 
Published: April 2003

AbstractChrysophtharta agricola (Chapuis) is a pest of commercial eucalypt plantations in Tasmania and Victoria. Vagility of pest populations may result in difficulty predicting temporal and spatial pest outbreaks, and influence genetic resistance to chemical control. Gene flow in this pest species was estimated to assess predicability of attack, the potential efficacy of natural enemies, and the likelihood of resistance build-up. Ten geographic populations of C. agricola (six from Tasmania, one from the Australian Capital Territory, one from New South Wales and two from Victoria) were examined for genetic variation and gene flow using cellulose acetate allozyme electrophoresis. Six enzyme systems (PGI, PGD, PGM, IDH, HEX and MPI) were consistently polymorphic and scorable and were used to quantify estimated gene flow between populations. FST values and analysis of molecular variance indicated that gene flow was restricted between populations. Chrysophtharta agricola exhibited high levels of heterozygosity, probably because of high allelic diversity, and because all loci examined were polymorphic. The southern-most population was the most genetically different to other Tasmanian populations, and may also have been the most recently colonized. Limited gene flow implies that outbreaks of C. agricola should be spatially predictable and populations susceptible to control by natural enemies. Our results also imply that genetic resistance to chemical control may occur under frequent application of insecticide. However, testing population movement between plantations and native forest also needs to be conducted to assess gene flow between forest types.
RELEVANCE-BASED INCREMENTAL BELIEF UPDATING IN BAYESIAN NETWORKS
Authors: LIN YAN , DRUZDZEL MAREK J. 
Published: April 2003

Relevance reasoning in Bayesian networks can be used to improve efficiency of belief updating algorithms by identifying and pruning those parts of a network that are irrelevant for computation. Relevance reasoning is based on the graphical property of d-separation and other simple and efficient techniques, the computational complexity of which is usually negligible when compared to the complexity of belief updating in general. This paper describes a belief updating technique based on relevance reasoning that is applicable in practical systems in which observations and model revisions are interleaved with belief updating. Our technique invalidates the posterior beliefs of those nodes that depend probabilistically on the new evidence or the revised part of the model and focuses the subsequent belief updating on the invalidated beliefs rather than on all beliefs. Very often observations and model updating invalidate only a small fraction of the beliefs and our scheme can then lead to sub stantial savings in computation. We report results of empirical tests for incremental belief updating when the evidence gathering is interleaved with reasoning. These tests demonstrate the practical significance of our approach.
A HIERARCHY RESULT FOR RANDOM FORBIDDING CONTEXT PICTURE GRAMMARS
Authors: EWERT SIGRID , VAN DER WALT ANDRIES 
Published: April 2003

We use random context picture grammars to generate pictures through successive refinement. The productions of such a grammar are context-free, but their application is regulated — "permitted" or "forbidden" — by context randomly distributed in the developing picture. Grammars using this relatively weak context often succeed where context-free grammars fail, e.g. in generating the Sierpiński carpets. On the other hand it proved possible to develop iteration theorems for three subclasses of these grammars, namely a pumping–shrinking, a pumping and a shrinking lemma for context-free, random permitting and random forbidding context picture grammars, respectively. Finding necessary conditions is problematic in the case of most models of context-free grammars with context-sensing ability, since they consider a variable and its context as a finite connected array. We have already shown that context-free picture grammars are strictly weaker than both random permitting and random forbidding context picture grammars, also that random permitting context is strictly weaker than random context. We now show that grammars which use forbidding context only are strictly weaker than random context picture grammars.
Experimentally manipulated change in children's proactive and reactive aggressive behavior
Authors: Phillips Nancy C. , Lochman John E. 
Published: April 2003

AbstractThe current study assessed the effectiveness of two behavior manipulations created to differentially lower aggressive responses in a laboratory task. It was hypothesized that the reactive anger manipulation would have the greatest effect for reactive aggressive behavior and the instrumental manipulation would significantly affect proactive aggressive behavior and slightly affect the reactive behavior. Fifty participants played pinball in competition for points against an unknown peer, whose responses were actually controlled by the experimenter. Participants could push a noise button, sending the peer an annoying noise; a tilt button, interfering with the opponent's game; or a no answer button, offering a pro‐social alternative to aggression. After playing four rounds, participants were randomly assigned to either a reactive anger or a positive instrumental manipulation group; they then played pinball again for four rounds. Results indicate that the instrumental manipulation significantly lowered aggressive responses for both reactive and proactive behavior. The reactive manipulation effected aggressive responses only for use of the noise button and produced significantly lower levels of anger. Aggr. Behav. 29:215–227, 2003. © 2003 Wiley‐Liss, Inc.
Pauson‐Khand‐Reaktion: Beginn der katalytischen Ära
Authors: Gibson (née Thomas) Susan E. , Stevenazzi Andrea 
Published: April 2003

AbstractAls eine Folge des wachsenden Umweltbewusstseins sind heute Syntheseverfahren nicht mehr akzeptabel, die auf dem Einsatz von giftigen und teuren Übergangsmetallverbindungen in nichtkatalytischen Mengen beruhen. Eines der am längsten bekannten Beispiele für eine solche metallvermittelte Umwandlung ist die Pauson‐Khand‐Reaktion, eine [2+2+1]‐Cyclocarbonylierung mit einem Cyclopentenon als Produkt. Trotz der frühen Beschreibung katalytischer Varianten erneut durch Pauson et al. werden bis heute fast ausschließlich stöchiometrische Prozesse angewendet, allerdings wurde im vergangenen Jahrzehnt, und vor allem in den unmittelbar zurückliegenden Jahren, über eine Vielzahl an neuen Entwicklungen zur katalytischen Pauson‐Khand‐Reaktion berichtet, sodass mittlerweile mehrere katalytische Verfahren bekannt sind. Daneben hat sich die asymmetrische Katalyse bei der Pauson‐Khand‐Reaktion als tragfähiger Prozess herausgestellt. Mit Blick auf die eindrucksvollen Entwicklungen der letzten Jahre sind wir der Auffassung, dass ein umfassender und kritischer Überblick über die katalytische Pauson‐Khand‐Reaktion geeignet ist, Wege zur praktischen Anwendung und zukünftige Entwicklungen aufzuzeigen.
What consumers know and what they do: An investigation of consumer knowledge, awareness, and use of privacy protection strategies
Authors: Dommeyer Curt J. , Gross Barbara L. 
Published: April 2003

This study examines consumer knowledge of privacy-related laws and practices, and consumer awareness and use of strategies that may protect the consumer's privacy. Consumers were found to have very little knowledge of direct marketing practices and regulations. While consumers were fairly well informed on privacy-protection strategies, their use of these strategies was quite low. This study also investigates whether several consumer traits, namely gender, age, telephone number listing status, and desire to receive direct marketing solicitations, had any relationship to the consumer's awareness and use of privacy-protection strategies. It was found that males and young people were more likely than their counterparts to be aware of privacy-protection strategies. Those most likely to use privacy-protection strategies were young people and people who disliked receiving direct marketing solicitations.
Determinants of health care utilization by German sickness fund members ‐ with application to risk adjustment
Authors: Breyer Friedrich , Heineck Martin , Lorenz Normann 
Published: April 2003

AbstractIn many countries, social health insurance systems are being reformed in favor of more competition among insurers, while premiums are community rated by regulation. The implicit incentives for insurers to engage in risk selection can only be curtailed using appropriate systems of risk‐adjusted equalization payments among insurers. To develop these systems, predictors of individual utilization patterns have to be identified, e.g. via regression analysis using previous utilization data. In some countries such as Germany, such data are hardly ever available. In the early nineties, a number of sickness funds participated in an experiment in which individual utilization data were collected. Our data set covers more than 70 000 members of company sickness funds over a 5‐year period. We analyze socio‐demographic determinants of utilization which could be used as risk adjusters in a risk equalization scheme. Our results suggest that besides age and sex, the set of risk adjusters should include income, family status and a dummy for the last year of life. Copyright © 2002 John Wiley & Sons, Ltd.
Missing.... presumed at random: cost‐analysis of incomplete data
Authors: Briggs Andrew , Clark Taane , Wolstenholme Jane , Clarke Philip 
Published: April 2003

AbstractWhen collecting patient‐level resource use data for statistical analysis, for some patients and in some categories of resource use, the required count will not be observed. Although this problem must arise in most reported economic evaluations containing patient‐level data, it is rare for authors to detail how the problem was overcome. Statistical packages may default to handling missing data through a so‐called ‘complete case analysis’, while some recent cost‐analyses have appeared to favour an ‘available case’ approach. Both of these methods are problematic: complete case analysis is inefficient and is likely to be biased; available case analysis, by employing different numbers of observations for each resource use item, generates severe problems for standard statistical inference. Instead we explore imputation methods for generating ‘replacement’ values for missing data that will permit complete case analysis using the whole data set and we illustrate these methods using two data sets that had incomplete resource use information. Copyright © 2002 John Wiley & Sons, Ltd.
A bibliometric analysis of health economics articles in the economics literature: 1991‐2000
Authors: Rubin Rose M. , Chang Cyril F. 
Published: April 2003

AbstractThis paper describes and analyzes trends in health economics articles indexed in the economics literature from 1991 to 2000, demonstrating the robust state of publication in the field during the past decade. While articles, pages, and the number of journals increased, single authorship declined dramatically from almost half of articles published to only one‐third, and papers with four or more authors increased three‐fold. Over three‐fourths of articles were analyses of healthcare markets or health production, while policy oriented articles constituted the third largest share. Author concentration ratios decreased almost by half and the Herfindhal–Hirschman index of author concentration declined from 14 in 1991 to only 4 in 1999. Copyright © 2003 John Wiley & Sons, Ltd.
MRI of focal nodular hyperplasia (FNH) with gadobenate dimeglumine (Gd‐BOPTA) and SPIO (ferumoxides): An intra‐individual comparison
Authors: Grazioli Luigi , Morana Giovanni , Kirchin Miles A. , Caccia Paolo , Romanini Laura , Bondioni Maria P. , Procacci Carlo , Chiesa Antonio 
Published: April 2003

AbstractPurposeTo compare the efficacy of two different MR contrast agents for the detection and diagnosis of focal nodular hyperplasia (FNH).Materials and MethodsFifty patients with 83 FNH lesions detected on spiral CT were studied in two different MRI sessions with Gd‐BOPTA (MultiHance®) and ferumoxides (Endorem®). MRI with Gd‐BOPTA was performed precontrast (T1wGRE and T2wTSE sequences) and during the dynamic and late (1–3 hours) phases after injection (T1wGRE sequences only). MRI with ferumoxides (T1wGRE and T2wTSE sequences) was performed before and at least 30 minutes after injection. Hyper‐ or isointensity of FNH in the late phase was considered typical for Gd‐BOPTA, while isointensity or lesion hypointensity was considered typical for ferumoxides.ResultsWith Gd‐BOPTA, 83 FNH lesions (100%) appeared hyperintense during the arterial phase of dynamic MRI. All but one lesion was iso‐ or slightly hyperintense in the portal‐venous and equilibrium phases. In the late phase, 81 FNH lesions were hyper‐ or isointense to the surrounding parenchyma, with two lesions appearing slightly hypointense. With ferumoxides, a significant (P < 0.001) number (21/83, 25.3%) of FNH lesions (mean diameter = 16.8 ± 6.6 mm) were not visible. Of the visible FNH lesions, 38/62 were slightly hyperintense, and 24/62 were isointense to the surrounding parenchyma on the T2wTSE images. On the T1wGRE images, 42/62 lesions were isointense, 19/62 were slightly hyperintense, and one lesion was slightly hypointense. Seventeen lesions in 12 patients with previous neoplasia were all detected after Gd‐BOPTA administration, whereas only nine of these 17 lesions (52.9%) were detected after ferumoxide administration. Two of these nine lesions showed atypical enhancement features.ConclusionGd‐BOPTA‐enhanced MRI is significantly better than ferumoxide‐enhanced MRI for the identification and characterization of FNH. J. Magn. Reson. Imaging 2003;17:593–602. © 2003 Wiley‐Liss, Inc.
Ex vivo magnetic resonance microscopy of an osteochondral transfer
Authors: Petersen Erik F. , Fishbein Kenneth W. , Laouar Leila , Spencer Richard G.S. , Wenz James F. 
Published: April 2003

AbstractA 49‐year‐old woman with right knee pain and a chondral defect on the medial femoral condyle underwent an osteochondral transfer. The patient initially had pain relief, but then sustained a twisting injury and had progressive chondromalacia and pain on the affected side. She subsequently underwent a total knee replacement, and the tissue from the osteochondral transfer (OATS) site was harvested for analysis. In vitro MR microimaging of the excised joint segment revealed undamaged, full‐thickness cartilage on the OATS plug, intact cartilage on the posterior condyle, and severely thinned and damaged cartilage on the anterior condyle. Alcian blue‐stained sections revealed that proteoglycans were present throughout the OATS core but were nearly absent in the native cartilage. Quantitative T1 data acquired after equilibration with Gd‐DTPA indicated a distribution of matrix fixed charge in the OATS plug and anterior tissue that agreed well with histology and literature observations, while the posterior native cartilage appeared to have fixed charge similar to that of the OATS tissue. Histology revealed poor graft integration between OATS and native cartilage, with a distinct layer of fibrous tissue at the posterior interface. MRI images, by comparison, showed a hypointense feature at the posterior interface but uniform intensity across the anterior interface. Quantitative T2, magnetization transfer and T1 data acquired with and without gadolinium contrast showed dependences on depth, location, and pathology that were consistent with measurements reported in the literature for articular cartilage. J. Magn. Reson. Imaging 2003;17:603–608. Published 2003 Wiley‐Liss, Inc.
Large‐scale soil maps and a supplementary database for land use planning in Estonia
Authors: Reintam Loit , Kull Ain , Palang Hannes , Rooma Igna 
Published: April 2003

AbstractA soil map at the scale 1:10,000 serves as a major important document for land owners and local governments, which allows them to use soil information in their daily activity. The intensity of exploitation of soil maps will increase when the very map and its legend are supplemented, within colored and indexed polygons, with information about soil texture and reaction by layers, but also about the thickness and characterization of the epipedon, quality indices for soil assessment, classes of stoniness, and prevalent fractions of stones, erosion risk, etc. Special maps of agronomical status, with a list of proper measures for improvement of soils and their associations, should form a regular component of large‐scale mapping. As decrease in arable land and increase in the forest area are common trends in land use, these maps and general soil data should serve as the fundamental source of information for decision making concerning land use. Data indicating the suitability of any soil for any crop should be entered in a database. Application of GIS on any level of national economy, digitization of a large‐scale soil database and making it accessible to land users would allow to expand the amount of available information for each soil map polygon.
Crosslinked Poly(amido‐amine)s as Superior Matrices for Chemical Incorporation of Highly Efficient Organic Nonlinear Optical Dyes
Authors: Abbotto Alessandro , Beverina Luca , Chirico Giberto , Facchetti Antonio , Ferruti Paolo , Gilberti Manuela , Pagani Giorgio A. 
Published: April 2003

AbstractWe report on the synthesis and characterization of new crosslinked polymeric matrices, pertaining to the class of poly(amido‐amine)s (PAAs), functionalized with highly performing nonlinear optical (NLO) heterocycle‐based dyes as side‐chain substituents. Linear, soluble, and highly crosslinked NLO‐functionalized PAA networks can be easily prepared under mild conditions. The wide‐ranging tunability of optical and mechanical properties of these matrices makes them a superior alternative to conventional high‐Tg thermoplastic polymers.magnified image
Molecular Dynamics Simulation of Azobenzene Liquid Crystalline Polymers
Authors: Pavel Dumitru , Shanks Robert , Sangari Samra , Alazaroaie Silvia , Hurduc Nicolae 
Published: April 2003

AbstractThis paper presents a computational conformational study undertaken to explain the liquid crystalline behaviour of some polyethers with high transition temperature values. The study is based on a very significant number of polymers and copolymers (over 1 400) that were simulated to investigate the correlation between the chain geometry, flexibility, inter‐chain interactions and orientational properties over liquid crystalline behaviour. Some of the simulated polymers were synthesised from 3,3‐bis(chloromethyl)oxetane and various bisphenols with linear or bent geometry, such as: 4,4′‐dihydroxyazobenzene, 4,4′‐dihydroxydiphenyl, bisphenol‐A, 4,4′‐dihydroxybenzophenone and 4,4′‐dihydroxydiphenylsulfone. These polymers are of great interest as they allow chemical modifications due to the reactivity of the oxetane ring. For certain structures the molecular simulation evidenced difficult conformational changes associated with the distribution of the structural units in the chain. The phase transfer catalysis technique used for the polymer synthesis can generate different transfer ratios (from aqueous to the organic phase) for each bisphenol, with direct implications to the chain conformation. Therefore, the reaction conditions of the phase transfer catalyst can strongly influence chain conformation and the physical properties.A typical conformation of a random copolymer chain corresponding to sample 1, with predictive ‘discotic’ mesophase.magnified imageA typical conformation of a random copolymer chain corresponding to sample 1, with predictive ‘discotic’ mesophase.
The Quenched Instationary Polymerization Systems (QUIPS)
Authors: Schnöll‐Bitai Irene 
Published: April 2003

AbstractThe common element of quenched instationary polymerization systems is that at a given time all radicals present are deactivated by an efficient and fast quench reaction. Quenched instationary polymerizations can be carried out in a variety of ways distinguished by the way periods differing in their initiation characteristics are combined. The total chain length distribution of the resulting polymer is always the sum of the quenched radical and polymer chain length distribution. This distribution is either completely or at least partially dominated by the contribution of the quenched radical spectrum. Depending on the experimental conditions monomodal or multimodal distributions are obtained which can be characterized by their extrema (maximum, points of inflection) and peak widths (absolute, relative). The location of the extrema are related to the experimental parameters and can be used in an unambiguous way for the direct determination of the rate constant of propagation. Absolute peak widths (defined as the difference between two succeeding points of inflection) are invariant quantities with respect to the number, molar mass and hyper distribution which is only true for Poisson (and narrow Gauss) distributions. Relative peak widths are a valuable tool for the direct determination of axial dispersion which occurs in size exclusion chromatography. Comparison of experimental and ideal relative peak widths can be used for the direct determination of the axial dispersion.
The influence of the type of termination and [R0] (termination by combination) on the total (number) chain length distribution for single δ‐pulse initiation.magnified imageThe influence of the type of termination and [R0] (termination by combination) on the total (number) chain length distribution for single δ‐pulse initiation.