bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cost‐effectiveness analysis in colorectal cancer using a semi‐Markov model
Authors: Castelli Christel , Combescure Christophe , Foucher Yohann , Daures Jean‐Pierre 
Published: December 2007

AbstractCost and effectiveness are usually modeled according to one studied event or one health state with parametric or non‐parametric methods. In this paper, we propose an original method for assessing total costs while incorporating the dynamics of change in the health status of patients. A semi‐Markov model in which the distributions of sojourn times are explicitly defined is developed. The hazard function of sojourn times is modeled by Weibull distributions specific to each transition. A vector of covariates is incorporated into the hazard function of each transition. From a regression model for costs, a cumulative cost function is derived. An estimation of the mean cost per patient in each state defined in the semi‐Markov model could thus be made, and this enables us to identify the determinants of direct costs. The results of incremental net benefit (INB) are assessed using the bootstrap method. A cost‐effectiveness analysis is performed in order to compare two strategies of follow‐up in the colorectal cancer study. Two hundred and forty patients were enrolled in this study. Three health states are defined for patients with curative resection of colorectal cancer: alive without relapse, alive with relapse, and dead. The mean survival is 4.35 and 4.12 years, respectively, in the standard and moderate follow‐up groups. We show that mean cost differs significantly by follow‐up strategy and Dukes stage. Finally, the INB is assessed and this indicates that neither of the strategies compared was more cost‐effective than the other. Copyright © 2007 John Wiley & Sons, Ltd.
Stratification for the propensity score compared with linear regression techniques to assess the effect of treatment or exposure
Authors: Senn Stephen , Graf Erika , Caputo Angelika 
Published: December 2007

AbstractStratifying and matching by the propensity score are increasingly popular approaches to deal with confounding in medical studies investigating effects of a treatment or exposure. A more traditional alternative technique is the direct adjustment for confounding in regression models.This paper discusses fundamental differences between the two approaches, with a focus on linear regression and propensity score stratification, and identifies points to be considered for an adequate comparison. The treatment estimators are examined for unbiasedness and efficiency. This is illustrated in an application to real data and supplemented by an investigation on properties of the estimators for a range of underlying linear models. We demonstrate that in specific circumstances the propensity score estimator is identical to the effect estimated from a full linear model, even if it is built on coarser covariate strata than the linear model. As a consequence the coarsening property of the propensity score—adjustment for a one‐dimensional confounder instead of a high‐dimensional covariate—may be viewed as a way to implement a pre‐specified, richly parametrized linear model. We conclude that the propensity score estimator inherits the potential for overfitting and that care should be taken to restrict covariates to those relevant for outcome. Copyright © 2007 John Wiley & Sons, Ltd.
Assessing surrogacy from the joint modelling of multivariate longitudinal data and survival: Application to clinical trial data on chronic lymphocytic leukaemia
Authors: Deslandes Emmanuelle , Chevret Sylvie 
Published: December 2007

AbstractIn clinical research, we are often interested in assessing how a biomarker changes with time, and whether it could be used as a surrogate marker when evaluating the efficacy of a new drug. However, when the longitudinal marker is correlated with survival, linear mixed models for longitudinal data may be inappropriate. By contrast, it may be possible to recover information from the so‐called informative censoring by modelling both the longitudinal information and the survival process. The objective of this work is to jointly model longitudinal and survival data to assess surrogacy. Two competitive modelling strategies were used, either a multistate model summarizing the course of longitudinal data and occurrence of disease progression or death, or a joint longitudinal‐survival model. We present both analyses based on a case study from two randomized clinical trials that enrolled patients with stage A chronic lymphocytic leukaemia (CLL) in order to obtain further insights into these different approaches. Copyright © 2007 John Wiley & Sons, Ltd.
Robustness of a parametric model for informatively censored bivariate longitudinal data under misspecification of its distributional assumptions: A simulation study
Authors: Pantazis Nikos , Touloumi Giota 
Published: December 2007

AbstractRepeated measurements of surrogate markers are frequently used to track disease progression, but these series are often prematurely terminated due to disease progression or death. Analysing such data through standard likelihood‐based approaches can yield severely biased estimates if the censoring mechanism is non‐ignorable. Motivated by this problem, we have proposed the bivariate joint multivariate random effects (JMRE) model, which has shown that when correctly specified it performs well in terms of bias reduction and precision.The bivariate JMRE model is fully parametric and belongs to the class of shared parameters joint models where a survival model for the dropouts and a mixed model for the markers' evolution are linked through a multivariate normal distribution of random effects. As in every parametric model, robustness under violations of its distributional assumptions is of great importance. In this study we generated 500 simulated data sets assuming that random effects jointly follow a heavy‐tailed distribution, two skewed distributions or a mixture of two normal distributions. Moreover, we generated data where level‐1 errors or residuals in the survival part of the model follow a skewed distribution. Further sensitivity analysis on the effects of reduced sample size, increased level‐1 variances and altered fixed effects values was also performed.We found that fixed effects estimates are almost unaffected, but their standard errors (SEs) may be underestimated especially under heavily skewed distributions. The proposed model seems robust enough, but its performance on smaller data sets or under more extreme departures of its assumptions needs further investigation. Copyright © 2007 John Wiley & Sons, Ltd.
Properties of Cast Films Made of HCl‐Methanol Modified Corn Starch
Authors: Chung Yi‐Lin , Lai Hsi‐Mei 
Published: December 2007

AbstractThe molecular and physicochemical properties of the studied starches modified with 0.36% HCl in methanol at 25 °C and 45 °C were related to the film properties of these starches. The weight‐averaged molecular weight (Mw) and the number of long‐chain branches (DP 13‐36) of HCl‐methanol modified starch decreased with increasing degree of acid modification, but the number of short‐chain branches (DP < 6) increased. HCl‐methanol modification significantly decreased the ghost formation in gelatinized starch dispersions and the viscosity of starch film‐forming dispersions. Thus, the homogeneity of the produced starch films was improved and their opacity reduced. Proper HCl‐methanol modification produced corn starch films with lower moisture absorption rate and maximum moisture content under high relative humidity (RH = 97%) condition.
Effects of Soy Protein on Physical and Rheological Properties of Wheat Starch
Authors: Ribotta Pablo D. , Colombo Andrés , León Alberto E. , Añón M. Cristina 
Published: December 2007

AbstractIt is necessary to understand the interaction phenomena between proteins and polysaccharides for the development of starch‐based products with better physical and sensory properties. A simplified model system was chosen to study the influence of soy protein on physical and rheological properties of wheat starch and the possible interactions between them. Thermal and pasting behaviors of the slurries and texture properties, water retention capacity and ultra structure of soy protein‐wheat starch gels were analyzed. While soy protein isolate increased the viscosity of starch suspension during and after heating, gels with soy protein presented a weaker structure than wheat starch gels. Results suggested association between leached out material and swollen granule surface of starch with soy protein. Scanning electron microscopy reflected these changes in the gel ultrastructure.
A wideband MIMO channel model derived from the geometric elliptical scattering model
Authors: Pätzold Matthias , Hogstad Bjørn Olav 
Published: December 2007

AbstractIn this paper, we present a reference model for a wideband multiple‐input multiple‐output (MIMO) channel based on the geometric elliptical scattering model. The model takes into account the exact relationship between the angle of departure (AOD) and the angle of arrival (AOA). Based on this relationship, the statistical properties of the reference model are studied. Analytical solutions are presented for the three‐dimensional (3D) space‐time cross‐correlation function (CCF), the temporal autocorrelation function (ACF), the 2D space CCF, and finally the frequency correlation function (FCF). The correlation properties are studied and visualized under the assumption of isotropic as well as non‐isotropic scattering conditions. The proposed reference model can be used as a starting point for the derivation of a frequency‐selective space‐time MIMO channel simulator enabling the performance evaluation of multi‐antenna wideband communication systems. The reference model is also quite useful for studying the MIMO channel capacity under various propagation conditions imposed by the geometry of the underlying scattering model. Copyright © 2007 John Wiley & Sons, Ltd.
Mitigating the impact of node mobility on ad hoc clustering
Authors: Ghosh Rituparna , Basagni Stefano 
Published: December 2007

AbstractThis paper explores the impact of node mobility on distributed and mobility adaptive clustering (DMAC), a typical clustering protocol for mobile ad hoc networks. In particular, in this paper we evaluate the cost of maintaining the DMAC clustering structures when the nodes move according to three different mobility models, namely, the random way point model, the Brownian motion and the Manhattan mobility model. Via ns2‐based simulations, we have observed that the mobility models have different impact on protocol performance. The general trend, however, appears to be the same for networks of increasing size. The second contribution of this paper concerns investigating ways of mitigating the impact of mobility on the clustering structure and hence over the overall network performance. We consider a generalization of DMAC (GDMAC) where rules are established to decrease the number of cluster updates. Via simulation we have observed that GDMAC is effective in reducing the clustering overhead imposed by mobility, and the corresponding maintenance cost. Copyright © 2007 John Wiley & Sons, Ltd.
A modified hopfield network for mobility management
Authors: Taheri Javid , Zomaya Albert Y. 
Published: December 2007

AbstractThis paper presents a new approach to solving the mobile location management problem using the Paging Cells (PCs) scheme. In this approach (HNN‐BDT‐PC), a combination of the Hopfield Neural Network (HNN) and the author's Ball Dropping Technique (BDT) is used to solve the problem. To this end, the location management cost of a network is embedded in the HNN parameters, and by iteration, the mobile network gradually moves toward an optimal state. The approach is inspired by the phenomenon that results from the natural movement of balls when they are dropped onto a non‐even plate (a plate with troughs and crests). Each trough of the plate corresponds to a PC, and the network corresponds to the whole plate. The aim is to find optimal PC configuration (i.e., the troughs) of the network. Three main procedures are used in the optimization process; in each optimization cycle, the HNN is launched to move the balls around the plate, and, by analogy, to move the PCs around the network to find the best configuration. Copyright © 2007 John Wiley & Sons, Ltd.
A UTP semantics for
Circus
Authors: Oliveira Marcel , Cavalcanti Ana , Woodcock Jim 
Published: December 2007

Abstract

Circus specifications define both data and behavioural aspects of systems using a combination of Z and CSP constructs. Previously, a denotational semantics has been given to Circus; however, a shallow embedding of Circus in Z, in which the mapping from Circus constructs to their semantic representation as a Z specification, with yet another language being used as a meta-language, was not useful for proving properties like the refinement laws that justify the distinguishing development technique associated with Circus. This work presents a final reference for the Circus denotational semantics based on Hoare and He’s
Unifying Theories of Programming
(UTP); as such, it allows the proof of meta-theorems about Circus including the refinement laws in which we are interested. Its correspondence with the CSP semantics is illustrated with some examples. We also discuss the library of lemmas and theorems used in the proofs of the refinement laws. Finally, we give an account of the mechanisation of the Circus semantics and of the mechanical proofs of the refinement laws.
An Improved Method for Preparing Dimethyl Disulfide Adducts for GC/MS Analysis
Authors: Shibahara Akira , Yamamoto Kouhei , Kinoshita Akemi , Anderson Barbara L. 
Published: December 2007

AbstractDimethyl disulfide (DMDS) adducts are prepared from fatty acid methyl esters to locate the double‐bond position in monoenoic fatty acids by gas chromatography/mass spectrometry. We improved our original procedure for preparing DMDS adducts with a simple device that can be made in any laboratory using a glass pipette and silica based packing material, Extelut NT.
Does sex matter in reintroduction of griffon vulturesGyps fulvus?
Authors: Bosé M. , Le Gouar P. , Arthur C. , Lambourdière J. , Choisy J.P. , Henriquet S. , Lecuyer P. , Richard M. , Tessier C. , Sarrazin F. 
Published: December 2007

AbstractIn small populations of monogamous species sex ratio bias and sex-skewed demographic traits could lead to higher extinction probabilities than in other mating systems. Therefore a knowledge of bias in sex ratio, mortality and movement would be useful to determine the optimal strategy for sampling founders prior to reintroduction. We used molecular sexing to sex wild-hatched cohorts of two colonies (one native and one reintroduced) and four released groups of griffon vulturesGyps fulvusin France. In wild-hatched cohorts the sex ratio was not different from equilibrium whatever the year. Similarly no bias was detected in the sex ratio of founding stocks. Recoveries, recaptures, movements and philopatry were not skewed according to sex in wild-hatched and released groups. Our study revealed that no sex bias occurred during the griffon vulture life cycle (i.e. birth, death and movement). Consequently, random sampling may be appropriate to constitute founding stock in reintroduction programmes for monomorphic vultures.
Reintroduction of the Arabian oryxOryx leucoryxin Jordan: war and redemption
Authors: Harding Lee E. , Abu-Eid Omar F. , Hamidan Nashat , al Sha'lan Ahmad 
Published: December 2007

AbstractFollowing the extinction of the Arabian oryxOryx leucoryxin the wild in 1972 Jordan began a reintroduction programme in 1978 with 11 founding animals. When the herd size reached 31 in 1983 most were released from captive breeding pens into the 342 km2Shaumari Nature Reserve, part of which (22 km2) was fenced the following year to protect the oryx and exclude livestock. The herd grew initially (between 1979 and 1986) at about 23% per year. In 1990, when the herd numbered 79, its management was preparing to release it into the wild outside the fenced reserve. However, Bedouin families fleeing the Gulf War in Kuwait and Iraq brought 1.6 million sheep, goats, camels, and donkeys into Jordan. These livestock so overgrazed potential oryx habitat throughout the arid rangelands that reintroduction was impossible. Overcrowding within Shaumari became apparent by 1995, when the population numbered 186. The herd's rate of increase began to decline as productivity and recruitment decreased and mortality increased. In 1997, to reduce overcrowding, the herd's management began dispersing them to other Middle Eastern countries and to another nature reserve in Jordan. By February 2006, 43 oryx remained at Shaumari. In 2005, however, the prospects improved when the United Nations Compensation Commission awarded Jordan the cost of environmental damages resulting from the 1990–1991 Gulf War. Part of this award is designated for renewal of the captive breeding and reintroduction programme.
Genetic evidence for survival of released captive-bred brown hares Lepus europaeus during restocking operations in Greece
Authors: Stamatis Costas , Suchentrunk Franz , Sert Hakan , Triantaphyllidis Costas , Mamuris Zissis 
Published: December 2007

AbstractTo prevent the decline of the brown hare Lepus europaeus, especially as a result of hunting pressure, restocking programmes, using hares from elsewhere, were carried out in Greece up to 2001. Using diagnostic RFLP mitochondrial DNA markers we traced the origins of released captive-bred brown hares. We provide evidence that released animals survived long enough to have at least one reproductive cycle and to transmit their genome. If, in the long-term, introgressed foreign genes survive, forming new genotypes with indigenous genes, this would demonstrate that they are successful in terms of competition. As nuclear gene pools are not markedly divergent between Greek and other European hares foreign nuclear genes should not be a serious handicap. Hence, in certain situations release programmes may be appropriate.
Causes and spatio-temporal variations of non-natural mortality in the Vulnerable Spanish imperial eagle Aquila adalberti during a recovery period
Authors: González Luis Mariano , Margalida Antoni , Mañosa Santi , Sánchez Roberto , Oria Javier , Molina José Ignacio , Caldera Javier , Aranda Antonio , Prada Luis 
Published: December 2007

AbstractThe analysis of 267 records of non-natural mortality of the Spanish imperial eagle Aquila adalberti over a 16-year period (1989-2004) shows an annual rate of 15.1 individuals found dead per year and that electrocution (47.7%) and poisoning (30.7%) were the most frequent causes of mortality. Most cases (91.7%) were of human origin, and of those 92.3% were accidental. Just over half (50.2%) were related to the transmission of electricity and human activity (collisions and electrocution), and 40.7% related to game practices and livestock protection (control of predators). No differences between sexes were found but subadults were electrocuted more frequently than expected whilst adults were poisoned more frequently. In breeding areas poison was the most frequent cause of mortality, whereas electrocution was the most common cause of death in dispersal areas. Poisoning occurred more frequently than expected in the Northern and Southern regions compared to the West-Central region. Electrocution was significantly more frequent in the West-Central region, and less common in the Southern region. The increase in electrocutions over the last few years is associated with previous non-permanent corrections on electricity power lines, whilst the increase in the cases of poisoning appears to be associated with the use of illegal poison in predator control by small game practices and for livestock protection. Permanent corrections in power lines and more research and awareness effort in the small game sector are recommended to reduce human-induced mortality in this Vulnerable species.
A Tale of Two Churches: The Ecclesiologies of The Episcopal Church and the Church of England Compared
Authors: Podmore Colin 
Published: December 2007

AbstractThis article compares key aspects of the ecclesiologies of The Episcopal Church and the Church of England. First, it examines and contrasts the underlying logic of their structures and the relationships between their constituent parts (General Synod/General Convention, diocese, parish/congregation). Against this background, it then looks at the place of bishops in the ecclesiologies of the two churches (in relation to clergy and parishes, in relation to diocesan synods/conventions and standing committees, and nationally). The American Presiding Bishop's role is contrasted with the traditional roles of primate and metropolitan. Throughout, attention is given to origins and historical development. Reference is also made to the relevant constitutional, canonical and liturgical provisions. Rapprochement between the two ecclesiologies is noted, especially with respect to the role of the laity, but the article argues that this is far from complete. Each church's ecclesiology continues to be determined by its origins; important modifications have been made within that framework, rather than overturning it. It is hoped that the analysis will illuminate the current disputes within The Episcopal Church and the crisis within the Anglican Communion that they have prompted.
The Contribution of Common Principles of Canon Law to Ecclesial Communion in Anglicanism
Authors: Doe Norman 
Published: December 2007

AbstractAn important recent development in worldwide Anglicanism is the emergence over recent years of a project to articulate the principles of canon law common to the churches of the Anglican Communion. This project seeks to express the juridical character of Anglicanism from a global perspective, not only to underscore the many fundamental values that Anglicans share in terms of their polity, ministry, doctrine, liturgy, rites and property, going to the very roots of Anglican identity, but also as a concrete resource for other churches in ecumenical dialogue with Anglicans. This article traces the development of the so-called ius commune project, describes the methodological challenges which it faces, and the process of producing a draft. It also seeks to compare the project with the juridical experiences of other international ecclesial communities, and briefly to place the project in the context of the debate about the adoption of an Anglican Covenant, an initiative proposed by the Lambeth Commission in 2004.