bluuebunny/crossref_metadata_2025_split huggingface dataset:
An analysis of the effect of a reliability paradigm shift on leading British aerospace companies
Authors: Jones J. A. , Warrington L. 
Published: October 2002

AbstractThe aerospace industry is moving towards a new paradigm for the statement of reliability specifications. This paradigm is not a technical metric inherent to a system in isolation, but rather encompasses the wider objectives, operational profile and logistic priorities of its customer. This customer focus is encapsulated in the metrics Failure Free Operating Period and Maintenance Free Operating Period. These metrics describe the duration of effective system operation, in the first case for systems where faults and maintenance are permitted and in the second for systems where faults may not be repaired. As part of the Department of Trade and Industry (DTI) funded Aerospace Project for Insertion of Reliability (ASPIRE) research programme, which itself is part of the Ultra Reliable Aircraft (URA) programme, representatives of leading aerospace companies were interviewed about their opinion n how this new reliability paradigm and associated concepts would affect their way of doing business and their engineering processes. It would appear that the aerospace industry is ready for a move to a more realistic set of reliability metrics and away from the old style MTBF based metrics. This sea change would most likely be welcomed by customers, but as yet the manufacturing companies are unconvinced that such a radical move would be a good thing. Much of the resistance to change is due to old‐fashioned, but well entrenched, beliefs in the traditional way of doing things. A move away from this would bring freshness to the industry and lead to cost and time savings as the traditional approach is dropped in favour of a more planned and thought out approach. Copyright © 2002 John Wiley & Sons, Ltd.
VB2000: Pushing valence bond theory to new limits
Authors: Li Jiabo , McWeeny Roy 
Published: October 2002

AbstractFull valence bond (VB) calculations for a system of N electrons have always been hindered by the rapidly growing value of N!, which effectively imposes a limit N < 20. Often, however, not all electrons in a molecule are of interest; if we focus on a “group” G of NG electrons (e.g., in an “active” region), then it is NG! that sets the limit. In this work, group function (GF) theory is used to represent a molecule as a collection of interacting electron groups, each with a many‐electron wave function of any chosen form (e.g., VB, MO‐SCF, MCSCF), and each GF is optimized individually in a step‐by‐step process. An efficient VB algorithm allows for up to 14 electrons in any VB group and this combination of GF and VB methods greatly extends the range of feasibility of molecular calculations with VB‐type wave functions: Thus, (1) a large system can be divided into any number of smaller subsystems (groups); (2) each group may contain any chosen number of electrons; (3) the form of any group function (including its level of accuracy) may be chosen at will by the program user. A number of sample calculations are briefly presented. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
The Dirac equation in the algebraic approximation: VIII. Comparison of finite basis set and finite element molecular Dirac–Hartree–Fock calculations for the H2, LiH, and BH ground states
Authors: Quiney H. M. , Glushkov V. N. , Wilson S. 
Published: October 2002

AbstractUsing basis sets of distributed s‐type Gaussian functions with positions and exponents optimized so as to support Hartree–Fock total energies with an accuracy approaching the sub‐μHartree level, Dirac–Hartree–Fock–Coulomb calculations are reported for the ground states of the H2, LiH, and BH molecules at their respective equilibrium geometries. The calculated energies are compared with those obtained by Kullie et al. using the finite element technique for the Dirac–Hartree–Fock–Coulomb problem. Finite basis set calculations using the Dirac–Hartree–Fock–Breit approximation are also reported and compared with a first‐order treatment of the frequency‐independent Breit interaction. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Liquid chromatography/electrospray tandem mass spectrometric analysis of incurred ractopamine residues in livestock tissues
Authors: Churchwell Mona I. , Holder C. Lee , Little David , Preece Steve , Smith David J. , Doerge Daniel R. 
Published: October 2002

AbstractRactopamine HCl is a β‐adrenergic agonist (β‐agonist) recently approved by the U.S. Food and Drug Administration, but not other governmental agencies, for use in finishing swine. For these reasons, it was important to develop and validate mass spectrometric methods for the detection and confirmation of ractopamine residues in livestock marker tissues. Incurred tissues in cattle, sheep, turkeys, and ducks were generated during 7‐day ractopamine feeding (20 ppm in diets) periods. Disposition of ractopamine residues in liver and pigmented retinal epithelium was determined in animals slaughtered with withdrawal periods of 0, 3, and 7 days. Ractopamine residues, purified using solid‐phase extraction, were measured using liquid chromatography (LC) and electrospray with detection by tandem mass spectrometry (MS/MS) in the multiple reaction‐monitoring (MRM) mode. Total ractopamine residues (parent ractopamine + hydrolyzed conjugates) in liver were detected in all species on withdrawal day 0 (2–97 ppb) and were greatly diminished in all species by withdrawal day 7 (<1 ppb). Bovine and ovine retina had lower levels of ractopamine (0.5–3 ppb) than liver, and occular residues increased with withdrawal time, suggesting redistribution into this tissue. Lower limits of quantification were found to be approximately 0.1 ppb in liver and retina. Incurred ractopamine residues were confirmed by the precise and accurate agreement of MRM intensity ratios of diagnostic fragment ions (m/z 284, 164, and 121) from the protonated molecule between ractopamine residues in incurred samples and an authentic ractopamine standard. The limits of confirmation in liver and retina using recognized acceptance criteria were below 1 ppb. The high sensitivity and specificity for measurement and confirmation of ractopamine residues suggests this method will be applicable for regulatory residue surveillance programs. Copyright © 2002 John Wiley & Sons, Ltd.
Direct‐injection high performance liquid chromatography ion trap mass spectrometry for the quantitative determination of olanzapine, clozapine and N‐desmethylclozapine in human plasma
Authors: Kollroser Manfred , Schober Caroline 
Published: October 2002

AbstractA specific and sensitive direct‐injection high performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC/ESI‐MS/MS) method has been developed for the rapid identification and quantitative determination of olanzapine, clozapine, and N‐desmethylclozapine in human plasma. After the addition of the internal standard dibenzepin and dilution with 0.1% formic acid, plasma samples were injected into the LC/MS/MS system. Proteins and other large biomolecules were removed during an online sample cleanup using an extraction column (1 × 50 mm i.d., 30 µm) with a 100% aqueous mobile phase at a flow rate of 4 mL/min. The extraction column was subsequently brought inline with the analytical column by automatic valve switching. Analytes were separated on a 5 µm Symmetry C18 (Waters) analytical column (3.0 × 150 mm) with a mobile phase of acetonitrile/0.1% formic acid (20:80, v/v) at a flow rate of 0.5 mL/min. The total analysis time was 6 min per sample. The inter‐ and intra‐assay coefficients of variation for all compounds were <11%. By eliminating the need for extensive sample preparation, the proposed method offers very large savings in total analysis time. Copyright © 2002 John Wiley & Sons, Ltd.
An original approach to determining traces of tetracycline antibiotics in milk and eggs by solid‐phase extraction and liquid chromatography/mass spectrometry
Authors: Bruno Federica , Curini Roberta , Corcia Antonio Di , Nazzari Manuela , Pallagrosi Marco 
Published: October 2002

AbstractAn original and highly specific method able to identify and quantify traces of five tetracycline antibiotics (TCAs) in milk and eggs is presented. This method uses a single solid‐phase extraction (SPE) cartridge for simultaneous extraction and purification of TCAs in the above matrices. After diluting 5 mL of intact whole milk or 2 g egg samples with Na2EDTA‐containing water, samples are passed through a 0.5‐g Carbograph 4 extraction cartridge. After analyte elution from the SPE cartridge, an aliquot of the final extract is injected into a liquid chromatography/mass spectrometry (LC/MS) instrument equipped with an electrospray ion source and a single quadrupole. MS data acquisition is performed in the positive‐ion mode and by a time‐scheduled multiple‐ion selected ion‐monitoring program. With methanol as organic modifier, the in‐source collision‐induced dissociation (CID) process generated fragment ions able to pick up one methanol molecule. In several cases, these methanol‐adduct fragment ions have m/z values higher than those of the protonated molecules. This event is rarely encountered in MS, thus making the analysis of TCAs by this method extremely specific. Compared with a conventional published method, the present protocol extracted larger amounts of TCAs from both milk and egg and decreased the analysis time by a factor of 3. Recovery of TCAs in milk at the 25‐ppb level ranged between 81 and 96% with relative standard deviation (RSD) no larger than 9%. Recovery of TCAs in egg at the 50‐ppb level ranged between 72 and 92% with RSD no larger than 7%. Estimated limits of quantification(S/N = 10) of the method were 2–9 ppb TCAs in whole milk and 2–19 ppb TCAs in eggs. Copyright© 2002 John Wiley & Sons, Ltd.
Rapid quantitation of globotriaosylceramide in human plasma and urine: a potential application for monitoring enzyme replacement therapy in Anderson‐Fabry disease
Authors: Boscaro Francesca , Pieraccini Giuseppe , Marca Giancarlo la , Bartolucci Gianluca , Luceri Cristina , Luceri Francesca , Moneti Gloriano 
Published: October 2002

AbstractA method for measuring globotriaosylceramide (Gb3, or GL3) levels in plasma and urine of humans affected by Anderson‐Fabry disease has been developed. The analyses are performed using flow injection analysis‐electrospray ionization‐tandem mass spectrometry (FIA‐ESI‐MS/MS). The method is rapid, sensitive and hence suitable for high‐throughput analyses, requiring only a simple 50‐fold dilution for the preparation of plasma and urine samples. The detection of the analytes of interest was achieved using a triple quadrupole instrument operating in the multiple reaction monitoring mode. The linearity of the calibration standard responses, the intra‐ and inter‐assay precision, the accuracy and the detection limit of the method were evaluated. The proposed method allows a rapid and accurate assessment of globotriaosylceramide in biological samples. Data obtained from healthy volunteers and Anderson‐Fabry affected subjects suggest a potential role for this technique in monitoring the effectiveness of Anderson‐Fabry disease therapy. The results obtained in two actual cases treated with enzyme replacement therapy are reported and discussed. Copyright © 2002 John Wiley & Sons, Ltd.
A novel structural analysis of glycerophosphocholines as TFA/K+ adducts by electrospray ionization ion trap tandem mass spectrometry
Authors: Ho Yen‐Peng , Huang Ping‐Chen 
Published: October 2002

AbstractWhen collisionally activated dissociation (CAD) of glycerophosphocholine (GPC) species is examined using quadrupole ion trap mass spectrometry (QITMS), the spectral patterns differ from those obtained using sector or quadrupole mass spectrometry. Methods employed in the structural analysis of GPCs using a sector or quadrupole mass spectrometers are not necessarily useful for an ion trap mass spectrometer. A novel method is presented for structurally analyzing GPCs that involves the CAD of trifluoroacetic acid (TFA) adducts of kaliated GPCs. Solutions of GPCs in 0.1% TFA/methanol were electrosprayed to produce precursor ions by attaching a trifluoroacetic acid (TFA) molecule to a kaliated GPC molecule. The CAD‐MS/MS spectra obtained by QITMS revealed a dramatic increase in the abundance of fragment ions, corresponding to the losses of sn‐1 and sn‐2 fatty acyl substituents. A preferential loss of the sn‐1 fatty acyl group over the loss of the sn‐2 fatty acyl group was observed among the GPC standards examined. A GPC extract from egg yolk was directly analyzed by this method without prior separation. The identities and positions of fatty acyl substituents of over 20 GPC species were identified. Some isomers present in very low relative abundance, which could not be analyzed by QITMS/MS using other ions as precursors, were identified by the TFA attachment method. Copyright © 2002 John Wiley & Sons, Ltd.
On the use of breakdown graphs combined with energy‐dependent mass spectrometry to provide a complete picture of fragmentation processes
Authors: Butcher Colin P. G. , Dyson Paul J. , Johnson Brian F. G. , Langridge‐Smith Patrick R. R. , McIndoe J. Scott , Whyte Christopher 
Published: October 2002

AbstractBoth breakdown graphs and energy‐dependent (ED) maps provide a means of visually representing the fragmentation processes resulting from collision‐induced dissociation at different energies. The two presentation methods may be combined for a complete picture of the appearance, disappearance and maximum abundance collision potentials of each of the ions involved in the fragmentation process. A demonstration of this approach is presented using two very different classes of compound, an amino acid and a transition metal carbonyl cluster. Copyright © 2002 John Wiley & Sons, Ltd.
Amino acid and peptide conjugates of protoporphyrin: preparation and analysis by high‐performance liquid chromatography, high‐performance liquid chromatography/electrospray ionization mass spectrometry and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Razzaque M. A. , Lord G. A. , Lim C. K. 
Published: October 2002

AbstractAmino acid and peptide conjugates of protoporphyrin have been prepared by reacting protoporphyringen with cysteine, glutathione and peptides containing a free thiol group under acidic conditions. The conjugates were formed by the addition of the thioamino acids or peptides to the vinyl groups of protoporphyrin during the autoxidation of protoporphyinogen to protoporphyrin and is free‐radical‐mediated. The conjugates were separated by high‐performance liquid chromatography (HPLC) and characterized by HPLC/electrospray ionization mass spectrometry (HPLC/ESI‐MS) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). All the conjugates formed were diconjugates consisting of diastereoisomers. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative analysis of two‐dimensional gel‐separated proteins using isotopically marked alkylating agents and matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Gehanne Sylvie , Cecconi Daniela , Carboni Lucia , Righetti Pier Giorgio , Domenici Enrico , Hamdan Mahmoud 
Published: October 2002

AbstractWe describe a simple approach for the relative quantification of individual proteins within a mixture. The method is based on the differential labelling of the mixtures by use of a commercially available acrylamide and deuterium‐labelled [2,3,3′‐d3]‐acrylamide to alkylate proteins prior to two‐dimensional (2‐D) gel electrophoresis. The tryptic digests of the separated proteins were subjected to reflector matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) analysis and the relative peak heights of cysteine‐containing peptides were used to quantify their precursor proteins. This approach was tested for the relative quantification of proteins within an artificial mixture of standard proteins and for proteins observed in a 2‐D map of rat serum. A good correlation was found between the measured ratios derived from MALDI‐TOF data and those theoretically calculated prior to 2‐D analysis via known mixing ratios of the two alkylating reagents. The described procedure has proved to be effective for comparative measurements of protein abundances within the investigated mixtures. Copyright © 2002 John Wiley & Sons, Ltd.
On the covariance of the level sizes in random recursive trees
Authors: van der Hofstad Remco , Hooghiemstra Gerard , Van Mieghem Piet 
Published: October 2002

AbstractIn this paper we study the covariance structure of the number of nodes k and l steps away from the root in random recursive trees. We give an analytic expression valid for all k, l and tree sizes N. The fraction of nodes k steps away from the root is a random probability distribution in k. The expression for the covariances allows us to show that the total variation distance between this (random) probability distribution and its mean converges in probability to zero. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 20: 519–539, 2002
Large‐scale site diversity for satellite communication networks
Authors: Luglio M. , Mancini R. , Riva C. , Paraboni A. , Barbaliscia F. 
Published: October 2002

AbstractThe utilization of high frequencies, such as Ka‐band and beyond, necessary to avoid the highly congested lower satellite frequencies and to get larger bandwidth availability is considered for many developing satellite systems.The new satellite low‐margin systems in Ka‐band will need to be designed using fade countermeasures to counteract rain attenuation. One of these techniques foresees the possibility of switching the communication link among different Earth stations spread on a very large territory to reduce the system outage time to the joint outage time of all the stations.The design of such systems depends on the probability that the Earth stations simultaneously exceed their margins.In this paper, a well‐assessed model is utilized for the prediction of joint statistics of rain attenuation in multiple locations, using Monte Carlo simulation. The model is based on a pair of multi‐variate normal processes whose parameters are related to those characterizing the single‐location statistics and whose covariance matrices are assumed to depend only on the distances between locations.The main results concerning both the probability and margin improvement will be presented and discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Interference evaluations and simulations for multisatellite multibeam systems
Authors: Loreti Pierpaolo , Luglio Michele 
Published: October 2002

AbstractThird generation communication systems will be characterized by full integration between terrestrial and satellite components. To this aim, global coverage along with not severe requirements for user terminals are mandatory for the satellite segment and the use of constellations of satellites in low or medium Earth orbits (LEO or MEO) seems to be a viable solution. Those satellite systems will adopt multibeam antennas to achieve high spectral efficiency and low‐cost terminals. Thus, interference becomes one of the most limiting factors in terms of both link availability and capacity.The paper presents a more complete interference model than previously published in literature. The identification of the interfering users set has been introduced and all the factors impacting interference generation or isolation have been considered in case of both FDMA and CDMA access. This model is suitable for instantaneous analysis of multisatellite constellations. It has been implemented and time‐domain simulations have been performed to evaluate the impairments due to co‐channel interference for different access techniques for LEO configuration.Simulation results on interference and users spatial distribution, on trade‐offs between interference and system capacity will be presented. Finally, the main interference mitigation techniques will be listed and discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Arguments, contradictions, resistances, and conceptual change in students' understanding of atomic structure
Authors: Niaz Mansoor , Aguilera Damarys , Maza Arelys , Liendo Gustavo 
Published: October 2002

AbstractMost general chemistry courses and textbooks emphasize experimental details and lack a history and philosophy of science perspective. The objective of this study is to facilitate freshman general chemistry students' understanding of atomic structure based on the work of Thomson, Rutherford, and Bohr. It is hypothesized that classroom discussions based on arguments/counterarguments of the “heuristic principles,” on which these scientists based their atomic models, can facilitate students' conceptual understanding. This study is based on 160 freshman students enrolled in six sections of General Chemistry I (three sections formed part of the experimental group). All three models (Thomson, Rutherford, and Bohr) were presented to the experimental and control group students in the traditional manner, as found in most textbooks. After this, the three sections of the experimental group participated in the discussion of six items with alternative responses. Students were first asked to select a response and then participate in classroom discussions leading to arguments in favor or against the selected response and finally select a new response. Three weeks after having discussed the six items, both the experimental and control groups presented a monthly exam (based on the three models) and after another 3 weeks a semester exam. Results obtained show that given the opportunity to argue and discuss, students' understanding can go beyond the simple regurgitation of experimental details. Performance of the experimental group showed contradictions, resistances, and progressive conceptual change with considerable and consistent improvement in the last item. It is concluded that if we want our students to understand scientific progress and practice, then it is important that we include the experimental details not as a “rhetoric of conclusions” (Schwab, 1962, The teaching of science as enquiry, Cambridge, MA, Harward University Press; Schwab, 1974, Conflicting conceptions of curriculum, Berkeley, CA, McCutchan) but as “heuristic principles” (Lakatos, 1970, Criticism and the growth of knowledge, Cambridge, UK, Cambridge University Press, pp. 91–195), which were based on arguments, controversies, and interpretations of the scientists. © 2002 Wiley Periodicals, Inc. Sci Ed 86:505–525, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/sce.10035