bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation into the wrinkling behaviour of thin sheets in the cylindrical cup deep drawing process using bifurcation theory
Authors: Kim J. B. , Yoon J. W. , Yang D. Y. 
Published: February 2003

AbstractThe initiation and growth of wrinkles are influenced by many factors such as stress ratios, the mechanical properties of the sheet material, the geometry of the workpiece, and contact condition. It is difficult to analyse wrinkling initiation and growth while considering all the factors because the effects of the factors are very complex and studies of wrinkling behaviour may show a wide scattering of data even for small deviations in factors. In the present study, the bifurcation theory is introduced for the finite element analysis of wrinkling initiation and growth. All the above mentioned factors are conveniently considered by the finite element method. Wrinkling initiation is found by checking the determinant of the stiffness matrix and wrinkling behaviour is analysed by successive iteration with the perturbed guess along the eigenvector.Wrinkling initiation and growth in the cylindrical cup deep drawing process are analysed by using the proposed bifurcation algorithm. The mechanism of wrinkling initiation and growth in the cylindrical cup deep drawing process is investigated in detail. The results of the finite element analysis are compared with the experimental results. Through the finite element analyses of wrinkling growth for various material constants, the effects of plastic anisotropy and the strain hardening coefficient on the wrinkling behaviour of sheet metal are investigated. Copyright © 2003 John Wiley & Sons, Ltd.
Minimizing dynamic effects while using dynamic codes to simulate binder‐set processes
Authors: Hu Weilong 
Published: February 2003

AbstractWhen using a dynamic code to simulate a quasi‐static job, the dynamic effect is a very serious problem, such as in the binder set simulation in stamping process design. Dynamic effects generally consist of two different acting types, oscillation due to the kinetic energy of the blank and additional deformation thanks to the inertial action. For the binder set simulation, the inertial effect is more apt to change the simulation result due to less‐constrained forming of the blank. Light effect varies the magnitude of blank deformation. Seriousness shall result in the deformation type change of the forming blank, which could make simulating results useless for real‐world application. To aim at the dynamic problems, especially in the inertial effect, several useful and practical ways have been proposed in this paper. Some parameters that we can use to minimize dynamic effects during a simulation effectively include: the velocity type of the travelling part, damping, defining the travelling part and imposing additional loads on the forming blank. Finally, four associated simulation cases have been discussed to show how these enhancing methods can be applied in real stamping production. Copyright © 2003 John Wiley & Sons, Ltd.
Iterative solution of a hybrid method for Maxwell's equations in the frequency domain
Authors: Edlund Johan , Lötstedt Per , Strand Bo 
Published: February 2003

AbstractA hybrid method for solution of Maxwell's equations of electromagnetics in the frequency domain is developed as a combination between the method of moments and the approximation in physical optics. The equations are discretized by a Galerkin method and solved by an iterative block Gauss–Seidel method. The convergence of the iterations is studied theoretically and in numerical experiments. The accuracy of the hybrid method is compared to the method of moments for a cylinder with an incident field for different wavenumbers. Copyright © 2003 John Wiley & Sons, Ltd.
ε‐N,N,N‐Trimethyllysine‐specific ions in matrix‐assisted laser desorption/ionization‐tandem mass spectrometry
Authors: Hirota Junko , Satomi Yoshinori , Yoshikawa Kazuaki , Takao Toshifumi 
Published: February 2003

Abstractε‐N,N,N‐Trimethyllysine (Kme3) is a component of a number of proteins and plays an important role in the expression of their biological functions. Trimethylation, which causes an incremental increase in mass of 42.0470 Da from that of the corresponding MH+ ion, cannot be distinguished from the acetylation (+42.0106 Da), which also occurs on ε‐amino groups of Lys or α‐amino groups in many proteins, without high‐accuracy mass measurement which is accurate to within the second decimal place. MALDI‐MS and MS/MS have been applied for the analyses of post‐translational modifications of histone H3, which is known to contain both multiple acetylation and methylation sites in its sequence. During the measurements of the modified peptides, a novel fragmentation which involves the loss of trimethylamine from Kme3 was found. This characteristic fragmentation, which was observed to produce ions separated by 59 Da from the conventional precursor ion or sequence ions, would be useful for probing Kme3 units in the sequence. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of rabbit tear proteins by high‐pressure liquid chromatography/electrospray ionization mass spectrometry
Authors: Zhou Lei , Beuerman Roger W. , Barathi Amutha , Tan Donald 
Published: February 2003

AbstractThe aim of this study was to develop a fast and reliable analytical procedure for the display of the protein components of tears that can be used to differentiate the status of the ocular surface. Using this new procedure, we analyzed the tear protein components following a corneal wound in the rabbit. Calibrated 10‐μL glass, fire‐polished capillary micropipettes were used to collect tears from New Zealand White rabbits prior to and daily for 9 days following a unilateral 6‐mm diameter centrally placed anterior keratectomy. Tear proteins were eluted by a reversed‐phase high‐performance liquid chromatography (RP‐HPLC) column and the tear protein profile was monitored by electrospray ionization (ESI) mass spectrometry positive total ion current (TIC) chromatography. Tear proteins were reliably separated into 17 peaks, each of which contained one or a number of protein components. The molecular weight of each protein component was determined by on‐line ESI. Major tear protein components, lactoferrin, lysozyme (minimally detectable in rabbit tears), albumin, lipocalin, lipophilin and β2‐microglobulin, were tentatively identified by this method. Based on the mass spectrometric data, β2‐microglobulin was found to be glycosylated with N‐acetylhexosamine. ESI‐positive TIC chromatograms and mass spectra revealed comparative differences in the tear protein spectra after corneal wounding. One day after wounding, rabbit lysozyme with a molecular weight of 14 717 Da was found to be 8‐fold higher in the tears of wounded eyes when compared with tears from unwounded eyes. It dropped back to normal 3 days after wounding. The expression of an unidentified tear protein with the molecular weight of 16 060 Da was also elevated after corneal wounding and returned to normal level by day 5. In this study, LC/ESI‐MS was developed as a fast, reproducible and simple method for the identification and analysis of many of the protein components of the tears. Importantly, this technique also allows quantification of each component resolved in the chromatogram. This method is very suitable for mapping peptides and proteins (<80 kDa) in tears. Copyright © 2003 John Wiley & Sons, Ltd.
Automated quantitative and isotopic (13C) analysis of dissolved inorganic carbon and dissolved organic carbon in continuous‐flow using a total organic carbon analyser
Authors: St‐Jean Gilles 
Published: February 2003

AbstractA method for the automated 13C analysis of dissolved inorganic and organic carbon species has been developed to operate on a continuous‐flow isotope ratio mass spectrometer (CF‐IRMS). For natural and anthropogenic carbon species, the 13C stable isotope has proven to be an excellent environmental tracer. Analytical performance tests were carried out on various organic compounds from easily oxidisable (sugar) to difficult (humic acid). A set of natural samples was also analysed to confirm the flexibility of the system. Analytical precision (2σ) is typically <0.20‰ with sample reproducibility from 0.10–0.35‰ depending on reactivity of material. We believe this to be the first successful use of a total organic carbon (TOC) analyser for both dissolved inorganic and, specifically, dissolved organic species for 13C stable isotope analysis in an automated CF‐IRMS system. Routine analysis is achieved fairly quickly, is relatively simple with little or no sample manipulation, and will allow new and exciting studies for stable isotope research in both natural abundance and organic tracer studies not easily achieved before. Copyright © 2003 John Wiley & Sons, Ltd.
Heuristic charge assignment for deconvolution of electrospray ionization mass spectra
Authors: Zheng Huiru , Ojha Piyush C. , McClean Stephen , Black Norman D. , Hughes John G. , Shaw Chris 
Published: February 2003

AbstractWe propose a new algorithm for deconvolution of electrospray ionization mass spectra based on direct assignment of charge to the measured signal at each mass‐to‐charge ratio (m/z). We investigate two heuristics for charge assignment: the entropy‐based heuristic is adapted from a deconvolution algorithm by Reinhold and Reinhold;10 the multiplicative‐correlation heuristic is adapted from the multiplicative‐correlation deconvolution algorithm of Hagen and Monnig.6 The entropy‐based heuristic is insensitive to overestimates of zmax, the maximum ion charge. We test the deconvolution algorithm on two single‐component samples: the measured spectrum of human beta‐endorphin has two prominent and one very weak line whereas myoglobin has a well‐developed quasi‐gaussian envelope of 17 peaks. In both cases, the deconvolution algorithm gives a clean deconvoluted spectrum with one dominant peak and very few artefacts. The relative heights of the peaks due to the parent molecules in the deconvoluted spectrum of a mixture of two peptides, which are expected to ionize with equal efficiency, give an accurate measure of their relative concentration in the sample. Copyright © 2003 John Wiley & Sons, Ltd.
Validating methods for measuring δ18O and δ13C in otoliths from freshwater fish
Authors: Guiguer K. R. R. A. , Drimmie R. , Power M. 
Published: February 2003

AbstractThe ability of the phosphoric acid digestion technique to extract carbon dioxide from biogenic carbonates and reliably reproduce δ18O and δ13C signatures from standard reference materials (NBS‐18, NBS‐19) was tested and shown to produce accurate, unbiased measurements of non‐biologic materials. The effects of roasting preparation methods commonly reported when analyzing biogenic carbonates were also tested in a series of experiments using reference standards and otoliths obtained from aquacultured Arctic charr and rainbow trout. Roasting had no effect on the isotope measurement of reference standards. No significant differences between mean oxygen isotope signatures from paired experiments with roasted and non‐roasted fish otoliths were found. However, otolith oxygen isotope measurements were significantly enriched in comparison to rearing water‐based measurements for both species. Agreement between expected isotopic equilibrium and measured otolith δ18O values varied as a function of roasting temperature and between species. Criteria for the selection of appropriate roasting temperatures are suggested and favour 350°C in freshwater fish where unbiased estimates of average rearing water temperatures and known differences in rearing temperatures were obtained. Carbon isotopic disequilibria were observed for both species. A mixing model analysis established differences in the percentage of metabolically derived carbon in studied otoliths, with Arctic charr deriving a greater proportion of otolith δ13C from metabolism as a result of higher metabolic rates. Copyright © 2003 John Wiley & Sons, Ltd.
Structural studies of glutenin subunits 1Dy10 and 1Dy12 by matrix‐assisted laser desorption/ionisation mass spectrometry and high‐performance liquid chromatography/electrospray ionisation mass spectrometry
Authors: Cunsolo Vincenzo , Foti Salvatore , Saletti Rosaria , Gilbert Simon , Tatham Arthur S. , Shewry Peter R. 
Published: February 2003

AbstractStructural studies of the high molecular weight (HMW) glutenin subunits 1Dy10 and 1Dy12 of bread wheat were conducted using matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS) and reversed‐phase high‐performance liquid chromatography/electrospray ionisation mass spectrometry (RP‐HPLC/ESI‐MS). For both proteins, MALDI‐TOFMS analysis showed that the isolated fractions contained a second component with a mass about 500–540 Da lower than the major component. The testing and correction of the gene‐derived amino acid sequences of both proteins were performed by direct MALDI‐TOFMS analysis of their tryptic peptide mixture and analysis of the digests was performed by recording several MALDI mass spectra of the mixture at low, medium and high mass ranges, optimising the matrix and the acquisition parameters for each mass range. Complementary data were obtained by RP‐HPLC/ESI‐MS analysis of the tryptic digest. This resulted in the coverage of the whole protein sequences except for two short fragments (T1 and T8), which are identical in the two homologous subunits, and for an additional dipeptide (T14) in subunit 1Dy12, which were not detected. It also demonstrated that, in contrast to the gene‐derived data, the sequence of subunit 1Dy12 does not include the dipeptide Gly‐Gln between residues Gln454 and Pro455, and that the lower mass components present in both fractions correspond to the same sequences lacking short peptides that are probably lost from the protein N‐ or C‐termini. Finally, the results obtained provide evidence for the lack of a substantial level of glycosylation or other post‐translational modifications of the two subunits, and demonstrate that mass spectrometric mapping is the most useful method presently available for the direct verification of the gene‐derived sequences of HMW glutenin subunits and similar proteins. Copyright © 2003 John Wiley & Sons, Ltd.
Application of tandem mass spectrometry combined with gas chromatography and headspace solid‐phase dynamic extraction for the determination of drugs of abuse in hair samples
Authors: Lachenmeier Dirk W. , Kroener Lars , Musshoff Frank , Madea Burkhard 
Published: February 2003

AbstractA new method combination, headspace solid‐phase dynamic extraction coupled with gas chromatography/tandem mass spectrometry (HS‐SPDE/GC/MS/MS), is introduced to determine drugs of abuse in hair samples. This highly automated procedure utilizes SPDE for pre‐concentration and on‐coating derivatization as well as GC and triple quadrupole MS/MS for selective and sensitive detection. All these steps, apart from washing and cutting of the hair samples, are performed without manual intervention on a robot‐like autosampler.SPDE is a solventless extraction technique related to solid‐phase microextraction (SPME). The analytes are absorbed from the sample headspace directly into a hollow needle with an internal coating of polydimethylsiloxane by repeated aspirate/dispense cycles.The HS‐SPDE/GC/MS/MS procedure was applied to the analysis of methadone, the trimethylsilyl derivatives of cannabinoids and the trifluoroacetyl derivatives of amphetamines and designer drugs. The method was shown to be sensitive with detection limits between 6 and 52 pg/mg hair matrix and precision between 0.4 and 7.8% by the use of an internal standard technique. Linearity was obtained from 0.1–20 ng/mg with coefficients of correlation between 0.995 and 0.999.Compared with conventional methods of hair analysis, HS‐SPDE/GC/MS/MS is easier to use, substantially faster, with the degree of sensitivity and reproducibility demanded in clinical and forensic toxicology. The main advantage of the SPDE technique in relation to SPME is the robustness of the capillary. Copyright © 2003 John Wiley & Sons, Ltd.
Generalized monotonic regression using random change points
Authors: Holmes C. C. , Heard N. A. 
Published: February 2003

AbstractWe introduce a procedure for generalized monotonic curve fitting that is based on a Bayesian analysis of the isotonic regression model. Conventional isotonic regression fits monotonically increasing step functions to data. In our approach we treat the number and location of the steps as random. For each step level we adopt the conjugate prior to the sampling distribution of the data as if the curve was unconstrained. We then propose to use Markov chain Monte Carlo simulation to draw samples from the unconstrained model space and retain only those samples for which the monotonic constraint holds. The proportion of the samples collected for which the constraint holds can be used to provide a value for the weight of evidence in terms of Bayes factors for monotonicity given the data. Using the samples, probability statements can be made about other quantities of interest such as the number of change points in the data and posterior distributions on the location of the change points can be provided. The method is illustrated throughout by a reanalysis of the leukaemia data studied by Schell and Singh. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of HIV‐1 and HIV‐2 infectivity from a prospective cohort study in Senegal
Authors: Gilbert Peter B. , McKeague Ian W. , Eisen Geoffrey , Mullins Christopher , Guéye‐NDiaye Aissatou , Mboup Souleymane , Kanki Phyllis J. 
Published: February 2003

AbstractFrom a prospective cohort study of 1948 initially human immunodeficiency virus (HIV) uninfected female commercial sex workers followed between 1985 and 1999 in Dakar, Senegal, the authors compared the male to female per infectious sexual exposure transmission probability of HIV types one (HIV‐1) and two (HIV‐2). New non‐parametric competing risks failure time methods were used, which minimized modelling assumptions and controlled for risk factors for HIV infection. The HIV‐1 versus HIV‐2 infectivity ratio over time was estimated by the ratio of smoothed non‐parametric kernel estimates of the HIV‐1 and HIV‐2 infection hazard functions in sex workers, adjusted by an estimate of the relative HIV‐1 versus HIV‐2 prevalence in the partner population. HIV‐1 was found to be significantly more infectious than HIV‐2 throughout the follow‐up period (P < 0.001). The HIV‐1/HIV‐2 infectivity ratio was inferred to be approximately constant over time, with estimated common value 3.55. The finding of greater HIV‐1 infectivity persisted in sensitivity analyses and in covariate‐adjusted analyses, with adjusted infectivity ratio estimates ranging between 3.40 and 3.86. Understanding the mechanisms by which HIV‐1 infects more efficiently than HIV‐2 may be useful in the development of HIV‐1 vaccines. Additionally, the methodology developed here may be useful for analysing other data sets. Copyright © 2003 John Wiley & Sons, Ltd.
Missing data in the 2×2 table: patterns and likelihood‐based analysis for cross‐sectional studies with supplemental sampling
Authors: Lyles Robert H. , Allen Andrew S. 
Published: February 2003

AbstractStandard measures of crude association in the context of a cross‐sectional study are the risk difference, relative risk and odds ratio as derived from a 2× 2 table. Most such studies are subject to missing data on disease, exposure, or both, introducing bias into the usual complete‐case analysis. We describe several scenarios distinguished by the manner in which missing data arise, and for each we adjust the natural multinomial likelihood to properly account for missing data. The situations presented allow for increasing levels of generality with regard to the missing data mechanism. The final case, quite conceivable in epidemiologic studies, assumes that the probability of missing exposure depends on true exposure and disease status, as well as upon whether disease status is missing (and conversely for the probability of missing disease information). When parameters relating to the missing data process are inestimable without strong assumptions, we propose maximum likelihood analysis subsequent to collecting supplemental data in the spirit of a validation study. Analytical results give insight into the bias inherent in complete‐case analysis for each scenario, and numerical results illustrate the performance of likelihood‐based point and interval estimates in the most general case. Adjustment for potential confounders via stratified analysis is also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Estimating the probability of toxicity at the target dose following an up‐and‐down design
Authors: Stylianou Mario , Proschan Michael , Flournoy Nancy 
Published: February 2003

AbstractOne of the most important aspects of a phase I trial or other acute toxicity study is estimating accurately the probability of toxicity that is associated with the recommended dose. We use the biased coin up‐and‐down design to allocate and isotonic regression to estimate toxicity probabilities and determine the recommended dose. We then derive, using bootstrap methods, an estimate of the probability of toxicity at the recommended dose. Small sample properties of this estimator are also evaluated. Published in 2003 by John Wiley & Sons, Ltd.
H1‐Receptor activation triggers the endogenous nitric oxide signalling system in the rat submandibular gland
Authors: Borda Enri , Stranieri Graciela , Sterin-Borda Leonor 
Published: February 2003

Background: Histamine is released from mast cells by immunologic and non‐immunologic stimuli during salivary gland inflammation, regulating salivary secretion. The receptor‐secretory mechanism has not been studied in detail.Aims: The studies reported were directed toward elucidating signal transduction/second messenger pathways within the rat submandibular gland associated with 2‐thiazolylethylamine (ThEA)‐induced H1‐receptor responses.Materials and methods: To assess the H1 receptor subtype expression in the rat submandibular gland, a radioligand binding assay was performed. The study also included inositolphosphates and cyclic GMP accumulation, protein kinase C and nitric oxide synthase activities, and amylase release.Results: The histamine H1 receptor subtype is expressed on the rat submandibular gland with high‐affinity binding sites. The ThEA effect was associated with activation of phosphoinositide‐specific phospholipase C, translocation of protein kinase C, stimulation of nitric oxide synthase activity and increased production of cyclic GMP. ThEA stimulation of nitric oxide synthase and cyclic GMP was blunted by agents able to interfere with calcium movilization, while a protein kinase C inhibitor was able to stimulate ThEA action. On the other hand, ThEA stimulation evoked amylase release via the H1 receptor but was not followed by the L‐arginine/nitric oxide pathway activation.Conclusions: These results suggest that, apart from the effect of ThEA on amylase release, it also appears to be a vasoactive chemical mediator that triggers vasodilatation, modulating the course of inflammation.