bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of the temperature dependence of the internal friction in PbTe crystals
Authors: Salamov B. G. , Davarashvili O. I. , Mamedov T. S. , Darsavelidze G. Sh. , Enukashvili M. I. , Akhmedzade N. D. 
Published: August 2006

AbstractIn this study, internal friction (IF) measurements in the temperature interval of 20–600 °C are investigated for p‐PbTe and n‐PbTe:Cr crystals with the use of a torsion pendulum at low frequencies such as 1 Hz. The corresponding processes of diffusion of oscillation energy are characterized by values of activation energy and frequency factor. We consider that relaxation processes of IF may be the result of the dislocations that slip on the different planes. The influence of chromium doping to PbTe causes the creation of additional barriers with the oscillation of dislocations and increment of cohesion forces within the nuclei of the dislocations. The latter significantly influences the increase of shear modulus from 1.3 × 104 N/m2 for pure PbTe to 3.14 × 104 N/m2 for Cr‐doped PbTe. Moreover, IF exhibits different characters in different temperature intervals. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison between ab‐initio and phenomenological modeling of the exchange couplings in diluted magnetic semiconductors: the case of Zn1–xCrxTe
Authors: Bouzerar Georges , Bouzerar Richard , Kudrnovský Josef , Ziman Timothy 
Published: August 2006

AbstractUsing a recently developed semi‐analytical method (Self‐Consistent Local RPA or SC‐LRPA) we study the stability of the ferromagnetic phase in diluted magnetic systems where the exchange coupling between magnetic impurities are of RKKY form. A short discussion of the relevance of these calculations with respect to the ferromagnetism observed in diluted ferromagnetic materials is provided. Then, within a two step approach, we study ferromagnetism in Zn1–x Crx Te. In the first step of our study, we calculate the magnetic couplings between Mn impurities within the LDA. In the second step, we diagonalize the resulting effective Heisenberg Hamiltonian using the SC‐LRPA. We also compare, when available, our calculations with Monte Carlo simulations and experimental measurements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study on the influence of surface imperfections on the properties of ferroelectric thin films in first‐order ferroelectric systems
Authors: Lin Shan , Lü Tianquan , Cao Wenwu 
Published: August 2006

AbstractA generalized Ginzburg–Landau–Devonshire (GLD) theory is used to study the properties of ferroelectric thin films sandwiched between two metal electrodes with a first‐order phase transition. By taking into account the effect of the imperfect surface layer and a natural boundary condition, the temperature and film‐thickness dependence of the spontaneous polarization and the dielectric susceptibility are calculated. The depolarization field makes the polarization distribution more uniform. In addition, an asymmetric hysteresis loop can be obtained due to the existence of asymmetrical imperfect surface layers. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recursive grid methods to compute value sets and Horowitz–Sidi bounds
Authors: Gutman Per‐Olof , Nordin Mattias , Cohen Bnayahu 
Published: August 2006

AbstractIn this paper, recursive extensions to the standard equidistant grid method are proposed whereby the gridding is adapted locally such that a prescribed distance is achieved between neighbouring points in the computed value set (template). Also presented is the Prune algorithm, which finds the outer border of a value set defined by a set of points whose nearest neighbour lies within a prescribed distance. The Prune algorithm is part of the recursive grid methods, but can also be used independently with other methods to compute value sets. As an alternative to analytical or search algorithms, a recursive grid algorithm is presented to compute Horowitz–Sidi bounds (QFT bounds, or boundaries). Isaac Horowitz's contribution to computational methods for QFT is outlined in the perspective of the presented algorithms. Copyright © 2006 John Wiley & Sons, Ltd.
Using mixed treatment comparisons and meta‐regression to perform indirect comparisons to estimate the efficacy of biologic treatments in rheumatoid arthritis
Authors: Nixon R. M. , Bansback N. , Brennan A. 
Published: August 2006

AbstractMixed treatment comparison (MTC) is a generalization of meta‐analysis. Instead of the same treatment for a disease being tested in a number of studies, a number of different interventions are considered. Meta‐regression is also a generalization of meta‐analysis where an attempt is made to explain the heterogeneity between the treatment effects in the studies by regressing on study‐level covariables. Our focus is where there are several different treatments considered in a number of randomized controlled trials in a specific disease, the same treatment can be applied in several arms within a study, and where differences in efficacy can be explained by differences in the study settings. We develop methods for simultaneously comparing several treatments and adjusting for study‐level covariables by combining ideas from MTC and meta‐regression.We use a case study from rheumatoid arthritis. We identified relevant trials of biologic verses standard therapy or placebo and extracted the doses, comparators and patient baseline characteristics. Efficacy is measured using the log odds ratio of achieving six‐month ACR50 responder status. A random‐effects meta‐regression model is fitted which adjusts the log odds ratio for study‐level prognostic factors. A different random‐effect distribution on the log odds ratios is allowed for each different treatment. The odds ratio is found as a function of the prognostic factors for each treatment. The apparent differences in the randomized trials between tumour necrosis factor alpha (TNF−∝) antagonists are explained by differences in prognostic factors and the analysis suggests that these drugs as a class are not different from each other. Copyright © 2006 John Wiley & Sons, Ltd.
Advances in statistical human genetics over the last 25 years
Authors: Elston Robert C. , Anne Spence M. 
Published: August 2006

AbstractThe past 25 years has seen an explosion in the number of genetic markers that can be measured on DNA samples at an ever decreasing cost. Although basic statistical methods for analysing such data gathered on samples of either independent individuals or family members, one or two markers at a time, were already well developed before this explosion occurred, there has been a corresponding burst in activity to develop multiple marker models to find disease‐causing gene variants, capitalizing on the data that have become available, to increase the power of such methods. This has required the concomitant development of faster algorithms to speed up the computation of various likelihoods. For linkage analysis, to obtain the approximate locations for genes of interest, Mendelian segregation models have been extended to be more realistic and statistical models that do not assume specific modes of inheritance have been extended to allow for the analysis of larger pedigree structures. For association analysis, to obtain more precise locations for genes of interest, the recent completion of the first stage of the HapMap project has spurred the development, still underway, of novel experimental designs and analytical methods to combat the curse of dimensionality and the resulting multiple testing problem. Perhaps the greatest current challenge concerns how best to gather and synthesize the many lines of evidence possible in order to discover the genetic determinants underlying complex diseases. Copyright © 2006 John Wiley & Sons, Ltd.
An autoregressive linear mixed effects model for the analysis of longitudinal data which show profiles approaching asymptotes
Authors: Funatogawa Ikuko , Funatogawa Takashi , Ohashi Yasuo 
Published: August 2006

AbstractIn longitudinal data, a continuous response sometimes shows a profile approaching an asymptote. For such data, we propose a new class of models, autoregressive linear mixed effects models in which the current response is regressed on the previous response, fixed effects, and random effects. Asymptotes can shift depending on treatment groups, individuals, and so on, and can be modelled by fixed and random effects. We also propose error structures that are useful in practice. The estimation methods of linear mixed effects models can be used as long as there is no intermittent missing. Copyright © 2006 John Wiley & Sons, Ltd.
Cobol minefield detection
Authors: Veerman Niels , Verhoeven Ernst‐Jan 
Published: August 2006

AbstractIn Cobol, procedures can be programmed in ways that lead to unexpected behaviour and reduced portability. This behaviour is recognized as so‐called ‘mines’: programming practices containing hidden dangers and requiring extreme caution. Cobol mines can be created intentionally or by a programming error, and can be tripped at an unforeseen moment. This leads to minefields in source code with unseen hazards, which complicate understanding and maintenance, and which can lead to costly breakdowns of business critical software systems. We discuss Cobol mines and the dangers that come with them, having implemented a mine detector for Cobol. Our detector was deployed in an industrial situation, and a number of minefields were found in production systems. By restructuring a complex legacy application, we argue that code restructuring can be used to combat minefields. Copyright © 2006 John Wiley & Sons, Ltd.
A theory of regression testing for behaviourally compatible object types
Authors: Simons Anthony J. H. 
Published: August 2006

AbstractA behavioural theory of object compatibility is presented, which has implications for object‐oriented regression testing. The theory predicts that only certain models of state refinement yield compatible types, dictating the legitimate design styles to be adopted in object statecharts. The theory also predicts that conformity‐testing using regression tests is inadequate. Functionally complete test‐sets that are applied as regression tests to subtype objects are usually expected to cover the functionality of the original type, even though they are clearly not expected to cover extra functionality introduced in the subtype. However, such regression testing is proven to cover strictly less than the original state‐space in the new context and so provides much weaker confidence than expected. A different retesting model is proposed, based on full automatic test regeneration from the subtype's specification. This method can guarantee equivalent levels of confidence after retesting. The behavioural conformity desired by regression testing can then be proven by verification in the theory. Copyright © 2006 John Wiley & Sons, Ltd.
Polyyne synthesis using carbene/carbenoid rearrangements
Authors: Chalifoux Wesley A. , Tykwinski Rik R. 
Published: August 2006

AbstractRearrangement of a carbene/carbenoid intermediate to form an acetylene moiety, known as the Fritsch–Buttenberg–Wiechell (FBW) rearrangement, was developed for the formation of polyynes and polyyne frameworks within highly conjugated organic materials. Necessary precursors can be prepared through formation of an alkynyl ketone, followed by dibromoolefination under Corey–Fuchs conditions. The carbenoid rearrangement is brought about by treatment of the dibromoolefin with BuLi under mild conditions. The success of these FBW reactions is quite solvent‐dependent, and nonpolar hydrocarbon solvents (e.g., hexanes, toluene, benzene) work quite well, while use of ethereal solvents such as diethyl ether and tetrahydrofuran (THF) does not provide the desired polyyne product. This protocol was successfully applied to the formation of silyl, alkyl, alkenyl, and aryl polyynes, including di‐, tri‐, and tetrayne products, as well as the construction of two‐dimensional carbon‐rich molecules. A one‐pot variant of this procedure is being developed and is particularly applicable toward the synthesis of polyyne natural products. Formation of a series of triisopropylsilyl end‐capped polyynes, from the triyne to decayne, was achieved. Third‐order nonlinear optical properties of these polyynes were evaluated. This study shows that the molecular second hyperpolarizabilities for the polyynes as a function of length increase at a rate that is higher than all other nonaromatic organic oligomers. © 2006 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 6: 169–182; 2006: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20081
Co‐ordinated voltage control of DFIG wind turbines in uninterrupted operation during grid faults
Authors: Hansen Anca D. , Michalke Gabriele , Sørensen Poul , Lund Torsten , Iov Florin 
Published: August 2006

AbstractEmphasis in this article is on the design of a co‐ordinated voltage control strategy for doubly fed induction generator (DFIG) wind turbines that enhances their capability to provide grid support during grid faults. In contrast to its very good performance in normal operation, the DFIG wind turbine concept is quite sensitive to grid faults and requires special power converter protection. The fault ride‐through and grid support capabilities of the DFIG address therefore primarily the design of DFIG wind turbine control with special focus on power converter protection and voltage control issues. A voltage control strategy is designed and implemented in this article, based on the idea that both converters of the DFIG (i.e. rotor‐side converter and grid‐side converter) participate in the grid voltage control in a co‐ordinated manner. By default the grid voltage is controlled by the rotor‐side converter as long as it is not blocked by the protection system, otherwise the grid‐side converter takes over the voltage control. Moreover, the article presents a DFIG wind farm model equipped with a grid fault protection system and the described co‐ordinated voltage control. The whole DFIG wind farm model is implemented in the power system simulation toolbox PowerFactory DIgSILENT. The DFIG wind farm ride‐through capability and contribution to voltage control in the power system are assessed and discussed by means of simulations with the use of a transmission power system generic model developed and delivered by the Danish Transmission System Operator Energinet.dk. The simulation results show how a DFIG wind farm equipped with voltage control can help a nearby active stall wind farm to ride through a grid fault, without implementation of any additional ride‐through control strategy in the active stall wind farm. Copyright © 2006 John Wiley &Sons, Ltd.
An analysis of refinement in an abortive paradigm
Authors: Deutsch Moshe , Henson Martin C. 
Published: August 2006

Abstract

This paper presents a new strand of investigation which complements our previous investigation of refinement for specifications whose semantics is given by
partial
relations (using Z as a linguistic vehicle for this semantics). It revolves around extending our mathematical apparatus so as to continue our quest for examining mathematically the essence of the lifted-totalisation semantics (which underlies the de facto standard notion of refinement in Z) and the role of the semantic elements in model-theoretic refinement, but this time in the
abortive paradigm
. The analysis is given in two salient parts. In the first part, we consider the simpler framework of
operation-refinement:
we examine the (
de facto
) standard account of operation-refinement in this regime by introducing a simpler,
normative
theory which captures the notion of
firing-conditions
refinement directly in the language and in terms of the natural properties of preconditions and postconditions. In the second part, we generalise our analysis to a more intricate investigation of
simulation-based
data-refinement
. The proof-theoretic approach we undertake in the formal analysis provides us with a mathematical apparatus which enables us to examine
precisely
the relationships amongst the various theories of refinement. This enables us to examine the general mathematical role that the values play in model-theoretic refinement in the abortive paradigm, as well as the significance of the unique interaction of these values with the notions of
lifting
(of data simulations) and
lifted-totalisation
(of operations) in this regime. Furthermore, we generalise this mathematical analysis to a more
conceptual
one which also involves
extreme specifications
.
Impact of Polypropylene Amount on Functional Outcome and Quality of Life after Inguinal Hernia Repair by the TAPP Procedure Using Pure, Mixed, and Titanium‐coated Meshes
Authors: Horstmann Ruediger , Hellwig Matthias , Classen Claus , Röttgermann Susanne , Palmes Daniel 
Published: August 2006

AbstractBackgroundLaparoscopic inguinal hernia repair requires the use of prosthetic material. This prospective, single‐center study was intended to investigate the impact of the amount of polypropylene (PP) mesh used in hernia repair on functional results and quality of life.MethodsFor this series, 672 consecutive patients with primary inguinal hernia undergoing transabdominal preperitoneal hernia repair (TAPP) using a heavyweight PP mesh (Prolene 10 × 15 cm, 1.5 g, group I, n = 232), a mixed PP‐ and Polyglactin mesh (Vypro II, 10 × 15 cm, 0.53 g, group II, n = 217), or a light‐weight titanized PP mesh (Ti‐Mesh, 10 × 15 cm, 0.24 g, group III, n = 223) were compared in terms of postoperative complications (seroma, wound healing disorders), quality of life score (pain development, physical condition, urologic disorders), and hernia recurrence.ResultsDuring a 12‐month follow‐up there were no significant differences in the recurrence rate (1.3%‐1.7%). Patients with a pure PP mesh (group I) showed significantly more postoperative seromas (12.1% versus 4.1%/1.8%), foreign body sensations (9.1% versus 5.5%/3.5%), and sensitivity to weather changes (5.6% versus 3.2%/2.2%) compared to groups II and III. In all groups, the quality of life score was improved postoperatively. However, among those patients in our series with few preoperative complaints, the postoperative quality of life was worsened when heavy‐weight PP meshes (group I+II) were used but significantly improved when light‐weight titanized PP meshes were used.ConclusionsComparable functional results, fewer postoperative complications, and improved quality of life can be achieved by reducing the amount of PP in meshes used for laparoscopic hernia repair by TAPP procedure.
Comparison of Spinal Cord Protection Utilizing Left Atrial‐Femoral with Femoral‐Femoral Bypass in Patients with Traumatic Rupture of the Aortic Isthmus
Authors: Weiman Darryl S. , Gurbuz A. Tayfun , Gursky Andrei , Valaulikar Ganpat , Pate James W. 
Published: August 2006

AbstractIntroductionPostoperative paraplegia remains a dreaded complication of repair of traumatic rupture of the aortic isthmus. Claims have been made that left atrial‐femoral bypass provides better spinal cord protection. To test the hypothesis that left atrial‐femoral bypass is better than femoral vein‐to‐femoral artery bypass in regard to postoperative paraplegia, we concurrently compared the two techniques.MethodsWe compared the occurrence of paraplegia in 18 patients whose ruptures were repaired utilizing left atrial‐femoral bypass with 10,000 units of systemic heparin (group A) and 72 patients with femoral‐femoral bypass with heparin 300 units/kg and an oxygenator (group B) operated on between January 1995 and July 2004.ResultsThe mortality rate was 5.6% (5/90), with no statistical difference between the two groups. Postoperative paraplegia was present in three (16.7%) group A patients and five group B (6.9%) patients. However, the specific etiology of the neurologic defect was not clear, as one patient’s paraplegia was transient following a period of cardiac arrest, and four others had had neurologic injuries prior to the aortic repair. Median aortic cross‐clamp times were shorter in group A (34 minutes vs. 49 minutes). No patient required reexploration for bleeding, and no patient developed a graft infection.ConclusionsParaplegia rates were higher in the left atrial‐femoral group, but the difference was not statistically significant. This occurred despite the decreased cross‐clamp times in this group. In patients undergoing repair of traumatic rupture of the aortic isthmus, left atrial‐femoral bypass does not provide better spinal cord protection than femoral‐femoral bypass.
Retrosternal Goiter: The Need for Median Sternotomy
Authors: Ahmed Mohamed E. , Ahmed Elnazeer O. , Mahadi Seif I. 
Published: August 2006

AbstractIntroductionThe aim of this study was to analyze the features of patients with goiter who underwent thyroidectomy via a cervical incision and a median sternotomy in Khartoum.MethodsA total of 267 thyroidectomies were performed in Khartoum Teaching Hospital during the period from January 2002 to December 2003. There were 40 patients with evidence of retrosternal goiter (15%). Of those 40 patients, 13 had clinical and radiologic evidence of deep retrosternal extension of the goiter possibly necessitating sternotomy. Only 9 of the 13 patients actually required sternotomy, which accounted for 3.4% of all thyroidectomies performed (n = 267). The clinical, radiologic, and pathologic findings of those 9 sternotomy patients were analyzed and compared to those of the 258 patients who underwent cervical thyroidecomy.ResultsTotal thyroidectomy was undertaken in all nine patients. Six of them had retrosternal extension on the right side of the mediastinum, and three had bilateral extension. Seven patients had symptoms of respiratory distress, and two were asymptomatic. The duration of the goiter ranged between 7 and 30 years. The chest radiograph and computed tomography scan revealed that the retrosternal part was below the level of the aortic knuckle at the tracheal bifurcation in all cases. The histopathology revealed a simple multinodular goiter in eight of the nine patients (89%) and in one patient with papillary carcinoma. Five of the nine patients underwent intraoperative prophylactic tracheostomy due to tracheomalacia.ConclusionsA long‐standing goiter with deep (below the aortic knuckle) mediastinal extension and tracheal space compromise can be postulated to increase the likelihood of sternotomy.
Bycatch: complementary information for understanding fish behaviour. Namibian Cape hake (M. capensis and M. paradoxus) as a case study
Authors: Gordoa Ana , Lesch Heinrich , Rodergas Silvia 
Published: August 2006

Abstract
To identify spatio-temporal distribution in Namibian Cape hake (M. paradoxus and M. capensis), incidental hake catch by the horse mackerel fleet and targeted catch by the hake fleet were analysed for the period 1999–2004. The targeted catch, 45 955 fishing days, came from hake fishery logbooks and the incidental catch, 24 689 trawls, from observers' sample data collected aboard vessels of the horse mackerel fleet. A strong negative relationship between monthly catch rates (cpue) and bycatch was observed, confirming that the seasonal change in catchability is caused by differences in hake vertical dispersion. The October trends were an exception: both cpue and bycatch were negative. A drop in catchability at different depths of the fishing grounds indicates that M. capensis migrates to shallower water (<200 m) at the peak of spawning. Although there was no significant relationship between annual catch rates and bycatch, probably because of the short length of the time-series, annual bycatch should not be discarded as an indicator of hake recruitment. The results highlight the potential informative component of bycatch in identifying population patterns that cannot be extracted from the targeted catch.