bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing Multi‐response Design Methods with Mixed Responses
Authors: Kros John F. , Mastrangelo Christina M. 
Published: July 2004

AbstractThe multi‐response optimization process is commonly applied to engineering design problems involving more than one quality characteristic of interest. Define quality characteristics as output responses that fall into three general categories: larger‐the‐better (LTB), smaller‐the‐better (STB), and nominal‐the‐best (NTB). In the multi‐response optimization process, the objective is to define a set of input factors that, when combined, provide the optimal overall response. This paper investigates the relationship between response types when they are mixed (i.e. LTB, and/or STB, and/or NTB) and the choice of approach. The paper demonstrates that the mix of response types impacts the choice of final input parameters and response levels. In addition, the choice of an additive versus a multiplicative approach may adversely impact the response relationship. That is, it may produce two optimal combinations of factor settings or drive responses away from their target values and toward their extreme values. Copyright © 2004 John Wiley & Sons, Ltd.
Using Computer Modeling to Optimize Cost and Maintain Performance Constraints for the Production of Aircraft Turbine Engines
Authors: Sheldon Karl E. , Anderson‐Cook C. M. , O'Brien W. F. 
Published: July 2004

AbstractThe use of computer models and simulation can be an effective way of gaining valuable information about a variety of engineering systems. In this paper, quadratic polynomial models are used to estimate gas turbine engine performance models in an extensive simulation. The goal of the simulation is maximize the tolerances on a number of engine design features, while still producing an engine that will have an overall 3‐sigma (99.74%) pass rate on a number of geometric and performance constraints. The tolerances are maximized by using an optimization routine to determine the greatest allowable standard deviations (all with equal weights) and thus help to reduce engine‐manufacturing cost. Details are provided about how the models and simulation were constructed, as well as how information about the system was extracted from simulation results. A comparison of current production guidelines is made with those suggested by the study to show how system improvements can be achieved. Copyright © 2004 John Wiley & Sons, Ltd.
Identification of novel cannabinoid receptor ligands via evolutionary de novo design and rapid parallel synthesis
Authors: Rogers‐Evans Mark , Alanine Alexander I. , Bleicher Konrad H. , Kube Dagmar , Schneider Gisbert 
Published: July 2004

AbstractA rapid entry to novel and patentable cannabinoid receptor (CB‐1) ligands has been identified using computer‐based de novo design in combination with parallel synthesis. Small targeted compound arrays were readily prepared from the designs yielding active hit rates of 6% and 10%, respectively. This represents a hit rate enrichment of up to two orders of magnitude compared with corporate compound collections and is the first report of the application of the TOPAS algorithm for the de novo design of GPCR ligands.
Prediction of Carbonic Anhydrase Activation by Tri‐/Tetrasubstituted‐pyridinium‐azole Compounds: A Computational Approach Using Novel Topochemical Descriptor
Authors: Bajaj Sanjay , Sambi S. S. , Madan A. K. 
Published: July 2004

AbstractA novel highly discriminating adjacency‐cum‐distance based topochemical descriptor, termed as Superadjacency topochemical index, has been derived and its discriminating power investigated with regard to activation of Carbonic anhydrase (CA) isozyme‐I by tri‐/tetrasubstituted‐pyridinium‐azole compounds. The new index is not only sensitive to the presence of heteroatoms but also overcomes the problem of degeneracy of many topological descriptors. The discriminating power of Superadjacency topochemical index was found to be far superior when compared with that of distance based Wiener's index and adjacency based Molecular connectivity index. The values of Wiener's index, path‐one Molecular connectivity index and Superadjacency topochemical index of each of the 42 substituted‐pyridinium‐azole compounds comprising the dataset were computed. Resultant data was analyzed and suitable models developed after identification of the active ranges. Subsequently, a biological activity was assigned to each of the compounds involved in the dataset using these models, which was then compared with the reported activation constants for Carbonic Anhydrase isozyme‐I. Excellent correlations were observed between the activation constants of CA isozyme‐I and all the topological/topochemical descriptors. The overall accuracy of prediction was about 91% for models based upon both Molecular connectivity index as well as Wiener's index, and 96% for model based upon Superadjacency topochemical index. Surprisingly, the accuracy of prediction in the active range was found to be 100% in all the models. Thus the proposed index offers a vast potential for structure‐activity/structure‐property studies.
QSAR of Human Steroid 5α‐Reductase Inhibitors: Where are the differences between isoenzyme type 1 and 2?
Authors: Hutter Michael C. , Hartmann Rolf W. 
Published: July 2004

AbstractQuantitative Structure Activity Relationships have been established for inhibitors of human steroid 5α‐reductase including 6‐azasteroids and non‐steroidal compounds. From the applied descriptors, those related to the molecular geometry, electronic properties, and the electrostatic surface were derived from semi‐empirical AM1 calculations. A chemical reaction as part of the inhibitory action is indicated by the presence of the ionization potential in the descriptor space. Strong similarities between the variables for the prediction of the binding affinity to the type 1 and IC50 values for the type 2 isoform of the 5α‐reductase were observed. The most pronounced differences in the linear regression QSAR equations were found for the descriptors accounting for the hydrogen‐bonding interaction, suggesting a different hydrogen‐bonding pattern in the binding pocket of both isoforms. Furthermore, the topological indices together with the surface related descriptors point towards a lower content of aromatic amino acids in the binding site of the type 2 isoenzyme. Consequences for the design of new inhibitors are discussed.
The exclusion principle for interacting electrons: Kohn–Sham versus Thomas–Fermi
Authors: Nesbet R. K. 
Published: July 2004

AbstractMany anomalies and paradoxes in density‐functional theory arise from the assumption that an exact mean‐field theory of electrons requires only local potential functions. It is shown here that this assumption arises from a logical hiatus in deriving orbital‐based Kohn–Sham theory, which incorporates the exclusion principle for electrons, from density‐based Hohenberg–Kohn theory, which does not. The inconsistencies are removed by building the exclusion principle into density‐based theory from the outset. This logic replaces any implication regarding exact local potential functions by explicit specification of nonlocal potentials determined by exact N‐electron theory. These general results are examined here in the unrestricted Hartree–Fock variational model, using a two‐electron atom in its lowest triplet state 1s2s 3S as a test case to illustrate the implied inconsistencies and their resolution. It is shown that implications of the unrestricted Hartree–Fock model are not modified if overlap products are included in its variational functional. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Isospectral orthogonal polynomials from the Darboux transforms
Authors: Peña J. J. , Morales J. , Zamora‐Gallardo E. , García‐Ravelo J. 
Published: July 2004

AbstractOrthogonal polynomials (OP) are used in many branches of the mathematical and physical sciences; in particular they are part of the eigenfunctions of quantum chemical (QC) potential models. Recently, in the search for new solvable potentials to be useful in QC applications, the use of supersymmetry (SUSY) and Hamiltonian intertwining methods have shown the existence of isospectral potential partners. Also, it has been proved that SUSY is equivalent to the standard Darboux transform (DT) applied to Sturm–Liouville‐type problems. Consequently, because of the similarity between the differential equations of OP and of SL, we consider the application of the standard and generalized DT to find the isospectral OP that are partners of the standard one. To attain this purpose, we use a pair of transformations, a point canonical and a gauge, to convert the SL differential equation into a Schrödinger‐like equation allowing OP solutions. As a useful application of our proposal, we consider some of the most important OP by obtaining the generalized isospectral OP partners. Also, we shown the associated isospectral QC potentials for each of the orthogonal polynomials considered in this work. The proposed procedure can be used to obtain new orthogonal polynomials as well as to find new solvable QC potential models. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical studies on many‐band effects in superconductivity and magnetism
Authors: Nagao Hidemi 
Published: July 2004

AbstractWe present a two‐dimensional two‐sublattice system to investigate two‐band effects in magnetism and superconductivity. The spin susceptibility of the sublattice system is calculated, and the expression of the effective exchange integral in Heisenberg model for the sublattice is derived in the framework of the Hubbard model. We find the possibility of the appearance of ferromagnetic order around half‐filling in a two‐band system. Within the extended Hubbard model, a coupled gap equation for the two‐band superconductivity is also derived by using a mean‐field approximation. The results suggest that the superconducting order becomes larger by the pair‐scattering process. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Brueckner orbitals, Dyson orbitals, and correlation potentials
Authors: Ortiz J. V. 
Published: July 2004

AbstractOne‐electron, correlation potentials are closely related to the concepts of Brueckner orbitals and Dyson orbitals. Brueckner orbitals arise from fulfillment of a maximum‐overlap condition between a reference, Slater determinant and the many‐electron wavefunction. This condition may be used to define an energy‐independent, correlation potential for a given state. Dyson orbitals, in contrast, are associated with electron binding energies and are obtained from a pseudoeigenvalue problem with an energy‐dependent, correlation potential. The Brueckner doubles (BD)‐T1 approximation of the electron propagator employs an approximate Brueckner determinant in its reference state. Dyson orbitals generated with this approximation are expressed in the Brueckner orbital basis. An application of this approximation to the photoelectron spectrum of Al3O enables the assignment of peaks to distinct isomers. Dyson orbitals for the lowest electron detachment energies have high overlaps with occupied Brueckner orbitals that diagonalize the corresponding Fock operator. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical studies on effective exchange integrals using spin correlation function analysis and magnetic effective density functional (MEDF) method
Authors: Kitagawa Y. , Yamanaka S. , Takeda R. , Shoji M. , Koizumi K. , Nishiyama Y. , Maruno Y. , Kawakami T. , Okumura M. , Yamaguchi K. 
Published: July 2004

AbstractNew schemes for effective exchange integrals (Jab) and approximate spin‐projected energies for low spin states (EAPLS) were examined on simple two‐site radical models. These schemes are based on Hubbard model and include ionic term in wavefunction. By estimation of expectation values of spin correlation function, those schemes could directly calculate Jab and EAPLS values without the approximation that on‐site spins for high‐spin (HS) state was equivalent to one of low‐spin (LS) state. Calculated Jab values by new scheme were larger than conventional ones in short spin–spin distance, suggesting an importance of the on‐site spins and ionic term. On the other hand, new EAPLS values were similar to conventional ones. Estimation methods for new Jab and EAPLS also were derived by using HS state energy, LS state energy, and 〈Ŝ2〉LS analytically. To correct dynamical correlation, magnetic effective density functional (MEDF) method was successfully applied to calculate new Jab and EAPLS. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Risk, regulation and the right to know: exploring the impacts of access to information on the governance of environmental risk
Authors: Gouldson Andy 
Published: July 2004

AbstractWithin the context of broader debates on the potential of more open, inclusive and deliberative approaches to decision‐making, this paper examines the influence that enhanced access to environmental information has had on the governance of industry in the UK. After considering the extent to which information on emissions from industrial sites is practicably accessible to stakeholders, it examines the strategies that the different actors have adopted as a response to the provision of enhanced access to environmental information. In so doing, it highlights the pros and cons of greater transparency and more open engagement from the perspective of regulators, industry, community and pressure groups. It then assesses the impacts of access to information, both on the governance networks through which the different actors interact in an attempt to influence the emissions of the chemicals sector and on the environmental outcomes associated with these networks. It concludes that the provision of access to information has been associated with the emergence of new forms of engagement between regulators, industry and stakeholder groups and that this has coincided with (but has not been the main cause of) dramatic improvements in the environmental performance of the associated firms. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Use of QUASES™/XPS measurements to determine the oxide composition and thickness on an iron substrate
Authors: Grosvenor A. P. , Kobe B. A. , McIntyre N. S. , Tougaard S. , Lennard W. N. 
Published: July 2004

AbstractQUASES™ Analyze and Generate were used to model the extrinsic loss structures for XPS spectra of oxide films grown on iron in such a way that their thickness and structure could be determined. The Generate program used in conjunction with spectra of model iron oxides allowed for both magnetite (Fe3O4) and maghaemite (γ‐Fe2O3) structures to be identified in all films studied. These structures were identified as overlying layers in the oxide films and were usually intermixed at their interface. The absence of other iron oxide structures within the film could be tested based on their goodness of fit to the experimental spectrum. Comparison of the thickness values obtained using Generate with those found using nuclear reaction analysis suggested that the Generate results were higher by 20%. This difference likely resulted from the use of a calculated inelastic mean free path value for Fe 2p electrons in the Generate calculation rather than using the real attenuation length. For oxide films whose thickness approached 10 nm, the QUASES™ results for photoelectron spectra obtained with a Zr achromatic x‐ray source were compared with those from the standard Al monochromatic source. In this particular case, the oxide thicknesses obtained using Generate and Analyze were found to be more consistent when the Zr source was used. Copyright © 2004 John Wiley & Sons, Ltd.
Photoelectron core levels for enargite, Cu3AsS4
Authors: Pratt Allen 
Published: July 2004

AbstractThe mineral chemistry of enargite surfaces and near‐surfaces prepared by fracture within an ultrahigh vacuum are investigated using XPS and synchrotron radiation XPS (SRXPS). The purpose of the study is to identify surface core‐level line positions in high‐resolution photoelectron spectra. The XPS spectra obtained using monochromatic Al Kα radiation show that there are near‐identical monosulphide line positions in S 2p spectra for the As–S and Cu–S bonds in enargite. The SRXPS spectra for sulphur are remarkably similar to the XPS spectra for sulphur, showing that there is minimal difference in the chemical environment between sulphur atoms at the surface and in the mineral matrix. The Cu 2p XPS data have only cuprous contributions and a minor surface contribution. The surface Cu contribution is observed as a high‐binding‐energy tail in the Cu 2p3/2 spectrum. The As 3d data for both XPS and SRXPS show contributions from arsenic atoms at the surface and in the bulk mineral matrix. The surface contribution is distinct and is found 1 eV below the bulk contribution. The results of the study suggest that, following fracture, the enargite surface is reorganized in such a manner that the surface is characterized by protrusions of individual arsenic atoms. Copyright © 2004 John Wiley & Sons, Ltd.
On sample size for sensitivity and specificity in prospective diagnostic accuracy studies
Authors: Li Jialiang , Fine Jason 
Published: July 2004

AbstractThe design of a study of disease screening tests may be based on hypothesis tests for the sensitivity and specificity of the tests. The case‐control study requires knowledge of the disease status of patients at the time of enrollment. This may not be possible in a prospective setting, when the gold standard is obtained subsequent to the initial screening and the number of diseased individuals is random and can not be fixed by design. Several ad hoc procedures for determining the total sample size are commonly used by practitioners, for example, the prevalence inflation method. The properties of these methods are not well understood. We develop a formal method for sample size and power calculations based on the unconditional power properties of the test statistics. The approach provides novel insights into the behaviour of the commonly used methods. We find that the ad hoc prevalence inflation method may serve as a useful approximation to our rigorous framework for sample size determination in the prospective set‐up. The design of a large population‐based study of mammography for breast cancer screening illustrates the key issues. Copyright © 2004 John Wiley & Sons, Ltd.
Hierarchical modelling of small area and hospital variation in short‐term prognosis after acute myocardial infarction A longitudinal study of 35‐ to 74‐year‐old men in Denmark between 1978 and 1997
Authors: Rasmussen Søren 
Published: July 2004

AbstractModels for analysis of trends in hospital and small area variation in case fatality after acute myocardial infarction are presented. The data are from administrative registries in Denmark. Hierarchical modelling in a logistic regression with a Bayesian approach is used. Model selection is undertaken using the deviance and the Bayesian information criteria. There is a modest trend for hospital variation in case‐fatality rates that coincides with the introduction of new treatment strategies. This hospital variation is considerably larger than the variation at the area level. There is no trend for variation of the case‐fatality rates at the area level. Unstructured random effects slightly outperform spatially correlated random effects at the area level. Somewhat high correlations over time within hospitals and within areas were detected for the case‐fatality rates. Heavy‐tailed distributions (T‐distributions) could be an alternative for the random effect distribution in data from administrative registries and compete in the model selection with the normal distribution in this study. Copyright 2004 John Wiley & Sons, Ltd.
Validation and updating of predictive logistic regression models: a study on sample size and shrinkage
Authors: Steyerberg Ewout W. , Borsboom Gerard J. J. M. , van Houwelingen Hans C. , Eijkemans Marinus J. C. , Habbema J. Dik F. 
Published: July 2004

AbstractA logistic regression model may be used to provide predictions of outcome for individual patients at another centre than where the model was developed. When empirical data are available from this centre, the validity of predictions can be assessed by comparing observed outcomes and predicted probabilities. Subsequently, the model may be updated to improve predictions for future patients.As an example, we analysed 30‐day mortality after acute myocardial infarction in a large data set (GUSTO‐I,n= 40 830). We validated and updated a previously published model from another study (TIMI‐II,n= 3339) in validation samples ranging from small (200 patients, 14 deaths) to large (10 000 patients, 700 deaths). Updated models were tested on independent patients. Updating methods included re‐calibration (re‐estimation of the intercept or slope of the linear predictor) and more structural model revisions (re‐estimation of some or all regression coefficients, model extension with more predictors). We applied heuristic shrinkage approaches in the model revision methods, such that regression coefficients were shrunken towards their re‐calibrated values. Parsimonious updating methods were found preferable to more extensive model revisions, which should only be attempted with relatively large validation samples in combination with shrinkage. Copyright © 2004 John Wiley & Sons, Ltd.
A shortened stress evaluation tool (ASSET)
Authors: Faragher E. B. , Cooper C. L. , Cartwright S. 
Published: July 2004

AbstractAwareness is increasing that workplace characteristics can directly influence the physical and mental well‐being of employees, adversely affecting an organization's overall performance. As the effect of work‐related stress on employee health is of particular concern, many companies are looking to develop stress risk assessment programmes. However, the measurement instruments commonly used to examine workplace stressors are long, complex and developed primarily for white‐collar workers—making evaluations expensive and potentially inaccurate for most employee groups. An alternative, two‐stage, risk assessment process is proposed, whereby a short questionnaire is used initially to screen all employees and then conventional risk assessment tools used to evaluate in detail just those individuals identified as having a potential stress problem. The ASSET questionnaire was developed as a short instrument suitable for the first stage of this process. The three main sections of the questionnaire measure employee perceptions of their job, organizational commitment and employee health. Tests involving 9196 employees in 10 public and private sector organizations within the British Isles found ASSET to be quick and easy to complete, generating a high response rate. It has a small number of reliable factors for ease of interpretation, and has excellent validity. Copyright © 2004 John Wiley & Sons, Ltd.
Improving design quality using meta‐pattern transformations: a metric‐based approach
Authors: Tahvildari Ladan , Kontogiannis Kostas 
Published: July 2004

AbstractImproving the design quality of large object‐oriented systems during maintenance and evolution is widely regarded as a high‐priority objective. Furthermore, for such systems that are subject to frequent modifications, detection and correction of design defects may easily become a very complex task that is even not tractable for manual handling. Therefore, the use of automatic or semi‐automatic detection and correction techniques and tools can assist reengineering activities. This paper proposes a framework whereby object‐oriented metrics can be used as indicators for automatically detecting situations for particular transformations to be applied in order to improve specific design quality characteristics. The process is based both on modeling the dependencies between design qualities and source code features, and on analyzing the impact that various transformations have on software metrics that quantify the design qualities being improved. Copyright © 2004 John Wiley & Sons, Ltd.