bluuebunny/crossref_metadata_2025 huggingface dataset:
Calibration of pesticide leaching models: critical review and guidance for reporting
Authors: Dubus Igor G , Beulke Sabine , Brown Colin D
Published: September 2002

Calibration of pesticide leaching models may be undertaken to evaluate the ability of models to simulate experimental data, to assist in their parameterisation where values for input parameters are difficult to determine experimentally, to determine values for specific model inputs (eg sorption and degradation parameters) and to allow extrapolations to be carried out. Although calibration of leaching models is a critical phase in the assessment of pesticide exposure, lack of guidance means that calibration procedures default to the modeller. This may result in different calibration and extrapolation results for different individuals depending on the procedures used, and thus may influence decisions regarding the placement of crop‐protection products on the market. A number of issues are discussed in this paper including data requirements and assessment of data quality, the selection of a model and parameters for performing calibration, the use of automated calibration techniques as opposed to more traditional trial‐and‐error approaches, difficulties in the comparison of simulated and measured data, differences in calibration procedures, and the assessment of parameter values derived by calibration. Guidelines for the reporting of calibration activities within the scope of pesticide registration are proposed.

© 2002 Society of Chemical Industry
Laboratory evaluation of two novel strategies to control first‐instar gypsy moth larvae with spinosad applied to tree trunks
Authors: Wanner Kevin W , Helson Blair V , Harris Brenda J
Published: September 2002

Two strategies for controlling first‐instar larvae of gypsy moth (Lymantria dispar (L)), insecticidal bait and contact insecticide applied directly to the tree trunk, were evaluated in the laboratory. Spinosad was selected as a candidate natural‐product insecticide that is active both by contact and ingestion. Incorporated into artificial diet‐based bait, spinosad was toxic to neonate larvae with a minimal 10‐s feeding period, with an LC50 value of 20 (15–26, 95% confidence interval) mg liter−1. It was significant that neonate larvae did not discriminate between spinosad‐treated and control diet. Efficacy of diet‐based bait in the laboratory, however, was significantly impacted by previous exposure to diet; fed larvae did not stop at the bait and did not incur mortality, as compared to unfed larvae. Oak bark was a suitable substrate from which neonate larvae could contact spinosad residues. Spinosad applied directly to oak bark resulted in significant mortality after 1‐ and 4‐min crawling contact exposure times (LC50 = 24 [20–29, 95% CI] and 8.7 [6.9–11, 95% CI] mg liter−1, respectively) and contact activity persisted for 2 weeks. While contact activity was more potent on glass surfaces than on oak bark, the LC50 values differed only by factors of 2.4 and 3.6, for 1‐ and 4‐min exposures respectively.

© 2002 Society of Chemical Industry
Photochemical behaviour of dichlorprop [(±)‐2‐(2,4‐dichlorophenoxy)propanoic acid] in aqueous solution
Authors: Meunier Laurence , Gauvin Emmanuelle , Boule Pierre
Published: September 2002

Aqueous solutions of dichlorprop were irradiated under different conditions of pH, wavelength and oxygenation. The photochemical behaviour was found to be complex and many photoproducts were formed. However, at low concentrations the main photoproducts were 4‐chloropyrocatechol, 2‐chlorophenol, 4‐chlorophenol and 2,4‐dichlorophenol. Some other photoproducts were identified, namely 2‐(4‐chloro‐2‐hydroxyphenoxy)propanoic acid, 2‐(3,5‐dichloro‐2‐hydroxyphenyl)propanoic acid and 2,4‐dichlorophenyl acetate. From comparison with results previously obtained with mecoprop [2‐(4‐chloro‐2‐methylphenoxy)propanoic acid] it appears that the presence of a chlorine atom in position 2 on the ring strongly modifies the photochemical behaviour.

© 2002 Society of Chemical Industry
Haptenization of ovalbumin with the skin sensitizer methyl octanesulfonate: Characterization of the methylated OVA323‐339 T‐cell epitope at His331
Authors: Henriot Stéphanie , Lepoittevin Jean‐Pierre , Trifilieff Elisabeth
Published: September 2002

Our interest is focused on the induction of allergic contact dermatitis (ACD) by the strong skin sensitizer, methyl octanesulfonate, which is a potent methyl transfer agent, especially to histidine and methionine residues. We are particularly interested to study the effect of methylation on the presentation and recognition of the ovalbumin (OVA) T‐cell epitope, OVA323‐339, by the T‐cell receptor (TCR). Here we report the synthesis of the modified monomer N‐α‐Fmoc‐N‐τ‐methyl‐𝓁‐histidine and its incorporation by solid phase synthesis into the three possible methylated analogues of OVA323‐339, that were needed as references for the subsequent studies. Native OVA was haptenized by methyl octanesulfonate. Using classical protein chemistry techniques (trypsin digestion, gel permeation, HPLC, MS and Edman sequencing) we were able to show that OVA323‐339 was selectively methylated at His331. Circular dichroism (CD) studies showed that the methylation has no influence on the secondary structure of the peptide. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
High yield synthesis of tentoxin, a cyclic tetrapeptide
Authors: Loiseau Nicolas , Cavelier Florine , Noel Jean‐Pierre , Gomis Jean‐Marie
Published: September 2002

Tentoxin is a naturally occurring phytotoxic cyclic tetrapeptide excreted by fungi of the Alternaria alternata family. The four total syntheses of tentoxin published to date give poor total yields, mainly owing to two difficulties, the introduction of the dehydro amino acid and more especially the cyclization step. Here we describe a method that stereospecifically introduces Z‐dehydrophenylalanine (ΔZPhe) by a modified Erlenmeyer aldolization reaction. The linear tetrapeptide, Boc‐R1Ala‐Leu‐R2ΔZPhe‐Gly‐OMe (R1, R2: CH3, 14CH3), the precursor of tentoxin, was obtained in a 72% yield from Boc‐Leu‐Gly‐OH. This linear tetrapeptide, labelled with carbon‐14, was used for a comparative study of four cyclization reagents DPPA, DCC–PfpOH, HBTU and HATU. This last was the most effective and gave tentoxin in a 81% cyclization yield. The activated ester formed with this reagent displayed an enhanced capacity for cyclization, permitting cyclization in concentrated medium (10 mM). This new synthetic route gave tentoxin in a 60% yield from Boc‐Leu‐Gly‐OH and offers a means of achieving the synthesis of hitherto elusive analogues. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Support vector machines for the classification and prediction of β‐turn types
Authors: Cai Yu‐Dong , Liu Xiao‐Jun , Xu Xue‐biao , Chou Kuo‐Chen
Published: September 2002

The support vector machines (SVMs) method is proposed because it can reflect the sequence‐coupling effect for a tetrapeptide in not only a β‐turn or non‐β‐turn, but also in different types of β‐turn. The results of the model for 6022 tetrapeptides indicate that the rates of self‐consistency for β‐turn types I, I′, II, II′, VI and VIII and non‐β‐turns are 99.92%, 96.8%, 98.02%, 97.75%, 100%, 97.19% and 100%, respectively. Using these training data, the rate of correct prediction by the SVMs for a given protein: rubredoxin (54 residues, 51 tetrapeptides) which includes 12 β‐turn type I tetrapeptides, 1 β‐turn type II tetrapeptide and 38 non‐β‐turns reached 82.4%. The high quality of prediction of the SVMs implies that the formation of different β‐turn types or non‐β‐turns is considerably correlated with the sequence of a tetrapeptide. The SVMs can save CPU time and avoid the overfitting problem compared with the neural network method. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Estimation of dispersion effects from robust design experiments with censored response data
Authors: Chowdhury Abdul H. , Fard Nasser S.
Published: September 2002

A method is presented for estimating dispersion effects (DE) from robust design experiments (RDE) with control and noise factors involving censored response data. This method is developed to discern the significance of DE from RDE and the method aims at analyzing a multi‐level/multi‐factor experiment. This method imputes censored data by a regression based imputation technique, assuming that the distribution of lifetime before and after censoring is identical. This method also models the residuals to identify important DE, assuming that the distribution of the observed random variables of the model is the same with or without censored response data. Finally, the method is demonstrated through a numerical example. Copyright © 2001 John Wiley & Sons, Ltd.
Confidence intervals and sample size determination for Cpm
Authors: Zimmer LS , Hubele NF , Zimmer WJ
Published: September 2002

The capability index, Cpm, sometimes called the Taguchi index, has the desirable characteristic of being sensitive to both dispersion and deviation of the process average from the engineering target. As a result, the proposed estimators of Cpm have a sampling distribution that is dependent on the non‐central chi‐square distribution. Hence, constructing confidence intervals, performing hypothesis testing or estimating sample size requirements necessitates manipulation of a rather complex functional expression, typically beyond the capabilities of practitioners who need readily available tools. Here, a simple graphical procedure is proposed and illustrated for obtaining exact confidence intervals for Cpm. The graphical procedure allows the user to simply enter the graph with an estimate of the index and a value of the non‐centrality parameter for a given sample size to arrive at end‐points of 90%, 95% or 99% one‐sided or two‐sided confidence intervals. Detailed tables are also provided to assist the user for a wider range of sample values and sample sizes. In addition, a procedure is also presented for determining the minimum sample size required for attaining a pre‐specified level of accuracy of the Cpm. Extensive tables are provided for the user with a simple example illustrating the facility of the technique. Copyright © 2001 John Wiley & Sons, Ltd.
The use of not logic in fault tree analysis
Authors: Andrews J. D.
Published: September 2002

Risk and safety assessments carried out on potentially hazardous industrial systems commonly employ fault tree analysis to predict the probability or frequency of system failure. Causes of the system failure mode are developed in an inverted tree structure where the events are linked using logic gates. The type of logic is usually restricted to AND and OR gates which makes the fault tree structure coherent. The use, directly or indirectly, of the NOT logic gate is generally discouraged as this can result in a non‐coherent structure. Non‐coherent structures mean that components' working states contribute to the failure of the system. The qualitative and quantitative analysis of such fault trees can present additional difficulties when compared to the coherent versions. This paper examines some of the difficulties that can occur, and what potential benefits can be derived from the incorporation of NOT logic. It is shown that the binary decision diagram (BDD) method can overcome some of the difficulties in the analysis of non‐coherent fault trees. Copyright © 2001 John Wiley & Sons, Ltd.
Eliciting engineering knowledge about reliability during design‐lessons learnt from implementation
Authors: Hodge R. , Evans M. , Marshall J. , Quigley J. , Walls L.
Published: September 2002

In electronic design the use of engineering knowledge and experience is considered important in understanding and estimating the reliability performance of complex systems. There are numerous methods proposed for eliciting this knowledge in order to ensure that the data collected are valid and reliable. In this paper we describe our experiences in implementing an elicitation process that aims to extract engineering knowledge about the impact of design changes on a new aerospace product that is a variant of an existing product. The elicitation procedures used will be outlined and the ways in which we evaluated their usefulness will be described. This research generated many useful insights from the engineers and facilitators involved in the elicitation exercise. This paper shares their perspectives on the gains and losses associated with the exercise and makes recommendations for enhancing future procedures based on the lessons learnt. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of confinement on mean excitation energy
Authors: Sabin Peter B. , Sabin John R.
Published: September 2002

The effects of confinement on the mean excitation energy of atoms and molecules is discussed in the context of a jellium ellipsoid cavity model. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 277–281, 2001
Loss of isocyanic acid from the internal oxadiazole ring of protonated molecules of some 2,5‐diaryl‐1,3,4‐oxadiazoles
Authors: Frański Rafał , Schroeder Grzegorz , Rybachenko Volodymir , Szwajka Oles P.
Published: September 2002

The fragmentation pattern of some protonated 2,5‐diaryl‐1,3,4‐oxadiazoles is discussed. An unusual decomposition consisting of elimination of the isocyanic acid molecule from the internal oxadiazole ring was found. This fragmentation pathway was deduced on the basis of B/E linked scan mass spectra of metastable ions with liquid secondary ion mass spectrometry as the ionization method and also of low‐energy CID mass spectra where electrospray was used as the ionization technique. High resolution measurements were also performed. Copyright © 2002 John Wiley & Sons, Ltd.
Automated system for simultaneous analysis of δ13C, δ18O and CO2 concentrations in small air samples
Authors: Ribas‐Carbo Miquel , Still Chris , Berry Joe
Published: September 2002

In this paper we present an automated system for simultaneous measurement of CO2 concentration, δ13C and δ18O from small (<1 mL) air samples in a short period of time (≈1 hour). This system combines continuous‐flow isotope ratio mass spectrometry (CF‐IRMS) and gas chromatography (GC) with an inlet system similar to conventional dual‐inlet methods permitting several measurement cycles of standard and sample air. Analogous to the dual‐inlet method, the precision of this system increases with the number of replicate cycles measured. The standard error of the mean for a measurement with this system is 0.7 ppm for the CO2 concentration and 0.05‰ for the δ13C and δ18O with four replicate cycles and 0.4 ppm and 0.03‰ respectively with nine replicate cycles. The mean offset of our measurements from NOAA/CMDL analyzed air samples was 0.08 ppm for the CO2 concentration, 0.01‰ for δ13C and 0.00‰ for δ18O. A specific list of the parts and operation of the system is detailed as well as some of the applications for micrometeorological and ecophysiological applications. Copyright © 2002 John Wiley & Sons, Ltd.
Combined quantum chemical and RRKM modeling of the main fragmentation pathways of protonated GGG. II. Formation of b2, y1, and y2 ions
Authors: Paizs Béla , Suhai Sándor
Published: September 2002

Quantum chemical and RRKM calculations were performed on protonated GGG in order to determine the atomic details of the main fragmentation pathways leading to formation of b2,y1, and y2 ions. Formation of y1 ions on the ‘diketopiperazine’ pathway is initiated from relatively high‐energy C‐terminal amide nitrogen protonated species for which the N‐terminal amide bond is in the cis isomerization state. The reaction goes through a transition structure which is only slightly less favored than the reactive configuration itself. RRKM calculations indicate that this reaction is extremely fast as soon as the fragmenting species have more internal energy than the reaction threshold. The calculated energetics suggests that y1 ions are formed on the ‘diketopiperazine’ pathway with a non‐negligible (6–10 kcal/mol) reverse activation barrier. Investigation of species occurring during the formation of b2 ions having an oxazolone structure indicates that y1 ions can be formed also from intermediates previously thought to result in only b2 ions. As the first step of the ‘bx‐yz’ pathway proposed here the extra proton must reach the nitrogen of the C‐terminal amide bond. Attack of the N‐terminal amide oxygen on the carbon center of the C‐terminal amide bond results in formation of the oxazolone ring while the detaching G leaves the precursor ion. Under low‐energy collision conditions the complex of protonated 2‐aminomethyl‐5‐oxazolone and G can rearrange to form a proton‐bonded dimer of these species. In such circumstances the extra proton is shared by the two monomers and dissociation of the dimer will be determined by the thermochemistry involved. Based on the ‘bx‐yz’ pathway one can easily explain the linear relationship between the logarithm of the y1/b2 ion abundance ratio and the proton affinity of the C‐terminal amino acid substituent for the series of H‐Gly‐Gly‐Xxx‐OH tripeptides where Xxx was varied (Morgan DG, Bursey MM. Org. Mass. Spectrom. 1994; 29: 354). The calculated energetics indicates that both y1 and b2 ions are formed with no reverse activation barrier on the ‘bx‐yz’ pathway. Copyright © 2002 John Wiley & Sons, Ltd.
Cluster ions derived from sodium and potassium tetrafluoroborate and their collision induced dissociation in an ion trap mass spectrometer
Authors: Van Stipdonk M. J. , Ince M. P. , Perera B. A. , Martin J. A.
Published: September 2002

Electrospray ionization was used to produce distributions of gas‐phase cluster ions from solutions of sodium and potassium tetrafluoroborate. The majority of the cluster species followed the trend (MBF4)nM+, where M = Na and K. The values of n, for both salts, ranged from 1–15. Collision induced dissociation (MS/MS and MSn) in an ion trap mass spectrometer was used to determine the dissociation pathways for the cluster ions. The (NaBF4)nNa+ cluster ions fragmented via two pathways: (a) the loss of one or multiple neutral BF3 molecules and (b) the loss of one or more NaBF4 units. Of the two, the product ions corresponding to the loss of BF3 units were more prominent. Unlike the Na salt, the (KBF4)nK+ cluster ions decomposed primarily by the loss of one or multiple KBF4 units. Similar differences in dissociation behavior were observed when the heated transfer capillary, normally used to desolvate ions, was used to investigate cluster ion stability to thermal degradation and dissociation. The dissociation profiles (decrease in ion abundance with increasing activation amplitude) for several (NaF)nNa+ and (KF)nK+ cluster ions were measured and compared to probe the influence of the relative stability of the alkali fluorides (NaF and KF) on the dissociation behavior exhibited by the tetrafluoroborate cluster distributions. We found that the (NaF)nNa+ cluster ions required higher activation amplitudes to induce fragmentation than the corresponding (KF)nK+ species, indicative of stronger ionic bonding and higher gas‐phase stability for the former. This in turn indicates that the reaction pathway involving only the loss of one or multiple units of BF3, favored for the (NaBF4)nNa+ cluster series, but not for the analogous (KBF4)nK+ series, may be due to the high gas‐phase stability of NaF, and relatively lower stability of KF, towards dissociation. Copyright © 2002 John Wiley & Sons, Ltd.
New algorithms for processing and peak detection in liquid chromatography/mass spectrometry data
Authors: Hastings Curtis A. , Norton Scott M. , Roy Sushmita
Published: September 2002

Two new algorithms for automated processing of liquid chromatography/mass spectrometry (LC/MS) data are presented. These algorithms were developed from an analysis of the noise and artifact distribution in such data. The noise distribution was analyzed by preparing histograms of the signal intensity in LC/MS data. These histograms are well fit by a sum of two normal distributions in the log scale. One new algorithm, median filtering, provides increased performance compared to averaging adjacent scans in removing noise that is not normally distributed in the linear scale. Another new algorithm, vectorized peak detection, provides increased robustness with respect to variation in the noise and artifact distribution compared to methods based on determining an intensity threshold for the entire dataset. Vectorized peak detection also permits the incorporation of existing algorithms for peak detection in ion chromatograms and/or mass spectra. The application of these methods to LC/MS spectra of complex biological samples is described. Copyright © 2002 John Wiley & Sons, Ltd.
Improved peptide detection with matrix‐assisted laser desorption/ionization mass spectrometry by trimethylation of amino groups
Authors: Stewart N. A. , Pham V. T. , Choma C. T. , Kaplan H.
Published: September 2002

Trimethyl α‐amino derivatives of peptides (penta to deca) with a permanent positive charge on their α‐amino groups were prepared by in vacuo reaction with iodomethane and subjected to matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS). Compared to the unmodified peptide, the signal intensity of the trimethyl α‐amino derivative in MALDI‐MS is increased by at least an order of magnitude. Similarly, an octapeptide with a trimethylated ϵ‐amino group derived from the solitary lysine residue of the B‐chain of insulin also shows the same relative increase in signal intensity. Another advantage of the in vacuo methylation procedure is that trimethylation of a peptide amino group can be carried out readily with a combination of isotopes 13CH3I and 12CH3I or CD3I and CH3I, yielding a doublet signal either 3 or 9 units apart, respectively. The presence or absence of such a doublet signal can be used as a criterion to discriminate between peptide and non‐peptide signals in the mass spectrum. Copyright © 2002 John Wiley & Sons, Ltd.
High‐throughput liquid chromatography ultraviolet/mass spectrometric analysis of combinatorial libraries using an eight‐channel multiplexed electrospray time‐of‐flight mass spectrometer
Authors: Fang Liling , Cournoyer Jason , Demee Michael , Zhao Jiang , Tokushige Duayne , Yan Bing
Published: September 2002

We report a high‐throughput liquid chromatography/mass spectrometry (LC/MS) protocol for analyzing large combinatorial libraries using an eight‐channel parallel LC/UV/MS (MUX‐LCT) system. System configuration, linear response range in UV absorbance, LC column selection, and flow rate were optimized for 24 h/7 day unattended operations. Combinatorial libraries were analyzed on this system at a rate of 3200 compounds per day for a 3.5 min cycle time per injection. This parallel system is compared with a single‐channel system in terms of performance and operation. Copyright © 2002 John Wiley & Sons, Ltd.
Taylor dispersion monitored by electrospray mass spectrometry: a novel approach for studying diffusion in solution
Authors: Clark Sonya M. , Leaist Derek G. , Konermann Lars
Published: September 2002

This work describes a novel approach for monitoring analyte diffusion in solution that is based on electrospray ionization mass spectrometry (ESI‐MS). A mass spectrometer at the end of a laminar flow tube is used to measure the Taylor dispersion of an initially sharp boundary between two solutions of different analyte concentration. This boundary is dispersed by the laminar flow profile in the tube. However, this effect is diminished by analyte diffusion that continuously changes the radial position, and hence the flow velocity of individual analyte molecules. The steepness of the resulting dispersion profile therefore increases with increasing diffusion coefficient of the analyte. A theoretical framework is developed to adapt the equations governing the dispersion process to the case of mass spectrometric detection. This novel technique is applied to determine the diffusion coefficients of choline and cytochrome c. The measured diffusion coefficients, (11.9 ± 1.0) × 10−10 m2 s−1 and (1.35 ± 0.08) × 10−10 m2 s−1, respectively, are in agreement with the results of control experiments where the Taylor dispersion of these two analytes was monitored optically. Due to the inherent selectivity and sensitivity of ESI‐MS, it appears that the approach described in this work could become a valuable alternative to existing methods for studying diffusion processes, especially for experiments on multicomponent systems. Copyright © 2002 John Wiley & Sons, Ltd.
Influence of the 6th and 10th spatial harmonics on the peak shape of a quadrupole mass filter with round rods
Authors: Douglas D. J. , Konenkov N. V.
Published: September 2002

The influence of the ratio of the rod radius, r, to field radius, r0, on the peak shape for a linear quadrupole mass filter constructed with round rods has been investigated. The expansion of the potential in multipoles, $\phi _N,\Phi (x, y) = \sum_{N = 0}^{\infty} A_N \phi_N/r_{0}^{N}$, has been considered, and the peak shape and resolution have been determined by numerical calculation of ion trajectories in quadrupoles with different ratios, r/r0. Geometries that make the dodecapole term (A6) zero (r/r0 = 1.14511) do not give the best performance because the contribution of the 20‐pole term, A10, must be considered. The optimum ratio is r/r0 ≈ 1.13. With this ratio the dodecapole term (A6) is ca. 1 × 10−3, but its effects are partially compensated by the A10 term which has similar magnitude, but opposite sign. Copyright © 2002 John Wiley & Sons, Ltd.
Characterisation of adducts of the lipid peroxidation product 4‐hydroxy‐2‐nonenal and amyloid β‐peptides by liquid chromatography/electrospray ionisation mass spectrometry
Authors: Magni F. , Galbusera C. , Tremolada L. , Ferrarese C. , Kienle M. Galli
Published: September 2002

Alzheimer's disease is characterised by brain neuritic plaques composed of a 39–44 amino acid peptide (Aβ). Lipid peroxidation is an early event induced by these amyloid β‐peptides, leading to the formation of 4‐hydroxy‐2‐nonenal (HNE), which is one of the major end products of this process. HNE has been reported to form adducts via a stable covalent binding to proteins through a Michael addition to amino acid residues with a nucleophilic side chain. The present study reports an investigation of the conditions for formation of Aβ‐HNE (Aβ 1–28 and Aβ 1–42) adducts, and their characterisation by liquid chromatography/electrospray ionisation mass spectrometry (LC/ESI‐MS). The results suggest that one or more HNE moieties are localised in the 6–16 region of these adducts, while Asp‐1, Lys‐16 and Lys‐28 are not modified under the described reaction conditions. Copyright © 2002 John Wiley & Sons, Ltd.
The application of molecular phylogenetics to the analysis of viral genome diversity and evolution
Authors: McCormack Grace P. , Clewley Jonathan P.
Published: September 2002

DNA sequencing and molecular phylogenetics are increasingly being used in virology laboratories to study the transmission of viruses. By reconstructing the evolutionary history of viral genomes the behaviour of viral populations can be modelled, and the future of epidemics may be forecast. The manner in which such viral DNA sequences are analysed is the focus of this review. Many researchers resort to the often‐quoted ‘black box’ approach because phylogenetics theory can be daunting, and phylogenetics software packages can appear to be difficult to use. However, because phylogenetic analyses are often used in important and sensitive arenas, for example to provide evidence indicating transmission between persons, it is vital that appropriate care is taken to estimate reliably true relationships. In this review, we discuss how a molecular phylogenetics study should be approached, give an overview of the methods and programs for analysing DNA sequence data, and point readers to appropriate texts for further details. The aim of this review, therefore, is to provide researchers with an easy to understand guide to molecular phylogenetics, with special reference to viral genomes. Copyright © 2002 John Wiley & Sons, Ltd.
Protein–protein interactions as targets for antiviral chemotherapy
Authors: Loregian Arianna , Marsden Howard S. , Palù Giorgio
Published: September 2002

Most cellular and viral processes depend on the coordinated formation of protein–protein interactions. With a better understanding of the molecular biology and biochemistry of human viruses it has become possible to screen for and detect inhibitors with activity against specific viral functions and to develop new approaches for the treatment of viral infections. A novel strategy to inhibit viral replication is based on the disruption of viral protein–protein complexes by peptides that mimic either face of the interaction between subunits. Peptides and peptide mimetics capable of dissociating protein–protein interactions have such exquisite specificity that they hold great promise as the next generation of therapeutic agents. This review is focused on recent developments using peptides and small molecules to inhibit protein–protein interactions between cellular and/or viral proteins with comments on the practicalities of transforming chemical leads into derivatives with the characteristics desired of medicinal compounds. Copyright © 2002 John Wiley & Sons, Ltd.
Three‐dimensional nonlinearH∞guidance law
Authors: Yang Ciann‐Dong , Chen Hsin‐Yuan
Published: September 2002

This paper proposes a novel three‐dimensional missile guidance law design based on nonlinearH∞control. The complete nonlinear kinematics of pursuit–evasion motion is considered in the three‐dimensional spherical co‐ordinates system; neither linearization nor small angle assumption is made here. The nonlinearH∞guidance law is expressed in a simple form by solving the associated Hamilton–Jacobi partial differential inequality analytically. Unlike adaptive guidance laws, the implement of the proposed robustH∞guidance law does not require the information of target acceleration, while ensuring acceptable interceptive performance for arbitrary target with finite acceleration. The resulting pursuit–evasion trajectories for both theH∞‐guided missile and the worst‐case target are determined in closed form, and the performance robustness against variations in target acceleration, in engagement condition, and in control loop gain, is verified by numerical simulations. Copyright © 2001 John Wiley & Sons, Ltd.
Inverse filtering and deconvolution
Authors: Saberi Ali , Stoorvogel Anton A. , Sannuti Peddapullaiah
Published: September 2002

This paper studies the so‐called inverse filtering and deconvolution problem from different angles. To start with, both exact and almost deconvolution problems are formulated, and the necessary and sufficient conditions for their solvability are investigated. Exact and almost deconvolution problems seek filters that can estimate the unknown inputs of the given plant or system either exactly or almostly whatever may be the unintended or disturbance inputs such as measurement noise, external disturbances, and model uncertainties that act on the system. As such they require strong solvability conditions. To alleviate this, several optimal and suboptimal deconvolution problems are formulated and studied. These problems seek filters that can estimate the unknown inputs of the given system either exactly, almostly or optimally in the absence of unintended (disturbance) inputs, and on the other hand, in the presence of unintended (disturbance) inputs, they seek that the influence of such disturbances on the estimation error be as small as possible in a certain norm (H2orH∞) sense. Both continuous‐ and discrete‐time systems are considered. For discrete‐time systems, the counter parts of all the above problems when an 𝓁‐step delay in estimation is present are introduced and studied. Next, we focus on the exact and almost deconvolution but this time when the uncertainties in plant dynamics can be structurally modeled by a Δ‐block as a feedback element to the nominally known plant dynamics. This is done either in the presence or absence of external disturbances. Copyright © 2001 John Wiley & Sons, Ltd.
Uses of solar radiation pressure for satellite formation flight
Authors: Williams Trevor , Wang Zhong‐Sheng
Published: September 2002

One fundamental way in which satellite formation flight differs from conventional orbital proximity operations is that extended mission durations are required. Consequently, long‐term perturbation effects, and in particular, those due to the oblateness of the Earth, must be corrected for if the formation is to persist. This paper considers a novel non‐propulsive means for countering the differential orbital plane precession that is the major formation perturbation produced by oblateness. The approach taken is to make use of the solar radiation pressure acting on a relatively small surface, termed a solar wing, that is fixed to the satellite. The resulting torque causes the orbit to precess; if the wing is sized correctly, this motion will cancel, on average, with that due to oblateness, so maintaining the formation without use of propellant. It will be shown that the long‐term orbital effects of the solar wing control input (the wing orientation angle) are highly nonlinear, and exhibit strong coupling between the orbital inclination and the longitude of the ascending node. Finally, numerical results are given to illustrate the approach. Copyright © 2002 John Wiley & Sons, Ltd.
Co‐ordination and control of distributed spacecraft systems using convex optimization techniques
Authors: Tillerson Michael , Inalhan Gokhan , How Jonathan P.
Published: September 2002

Formation flying of multiple spacecraft is an enabling technology for many future space science missions. However, the co‐ordination and control of these instruments poses many difficult design challenges. This paper presents fuel/time‐optimal control algorithms for a co‐ordination and control architecture that was designed for a fleet of spacecraft. This architecture includes low‐level formation‐keeping algorithms and a high‐level fleet planner that creates trajectories to re‐size or re‐target the formation. The trajectory and formation‐keeping optimization algorithms are based on the solutions of linear and integer programming problems. The result is a very flexible optimization framework that can be used off‐line to analyse various aspects of the mission design and in real time as part of an onboard autonomous formation flying control system. The overall control approach is demonstrated using a nonlinear simulation environment that includes realistic measurement noises, disturbances, and actuator nonlinearities. Copyright © 2002 John Wiley & Sons, Ltd.
On the design of gain‐scheduled trajectory tracking controllers
Authors: Silvestre Carlos , Pascoal Antonio , Kaminer Isaac
Published: September 2002

A new methodology is proposed for the design of trajectory tracking controllers for autonomous vehicles. The design technique builds on gain scheduling control theory. An application is made to the design of a trajectory tracking controller for a prototype autonomous underwater vehicle (AUV). The effectiveness and advantages of the new control laws derived are illustrated in simulation using a full set of non‐linear equations of motion of the vehicle. Copyright © 2002 John Wiley & Sons, Ltd.
Sampled‐data implementation of a gain scheduled controller
Authors: Stilwell Daniel J. , Lawrence Douglas A.
Published: September 2002

A continuous‐time gain‐scheduled controller must be transformed to a corresponding discrete‐time controller for sampled‐data implementation. We show that certain linearization properties of a continuous‐time gain scheduled controller are inherited by its sampled‐data implementation. We also show that a similar relationship exists for multi‐rate gain scheduled controllers arising in flight control applications. Copyright © 2002 John Wiley & Sons, Ltd.
Control of a six‐axis pneumatic robot
Authors: Mattiazzo G. , Mauro S. , Raparelli T. , Velardocchia M.
Published: September 2002

The article presents a control system for a six‐degree of freedom (DOF) anthropomorphic robot powered entirely by pneumatic actuators. The control uses digital valves driven by pulse width modulation (PWM) to regulate air flow to the actuators. The robot is equipped with position sensors, which are used to provide feedback signals for local fuzzy controllers actuating the individual servoaxes. Trajectory tracking is guided by a module, which computes the robot's inverse kinematics, generating the references for the servoaxes. Experimental results illustrated in the article indicate that the controller is effective both in controlling single axes, and in tracking a trajectory. © 2002 Wiley Periodicals, Inc.
Joint tracking controller for multi‐link flexible robot using disturbance observer and parameter adaptation scheme
Authors: Cheong Joono , Youm Youngil , Chung Wan Kyun
Published: September 2002

An improved composite controller of singular perturbation approach is designed for controlling a multi‐link flexible robot with uncertainties. We adopt the standard form of a singular perturbation approach for modeling. To reduce the coupling effect from flexibility, the bandwidth of a slow subsystem is modulated by considering the fundamental frequency. The disturbance observer provides a means for defining the bandwidth of a slow subsystem as well as compensating disturbances. At the same time, uncertainties in the fast subsystem are updated to enhance the capability for vibration suppression in conjunction with PID (Proportional‐integrative derivative) modal feedback. We draw conditions for Lyapunov stability of the modal feedback and adaptive scheme. A numerical simulation will support the validity of our research results. © 2002 Wiley Periodicals, Inc.
On the expected value of the minimum assignment
Authors: Buck Marshall W. , Chan Clara S. , Robbins David P.
Published: September 2002

The minimum k‐assignment of an m × n matrix X is the minimum sum of k entries of X, no two of which belong to the same row or column. Coppersmith and Sorkin conjectured that if X is generated by choosing each entry independently from the exponential distribution with mean 1, then the expected value of its minimum k‐assignment is given by an explicit formula, which has been proven only in a few cases. In this paper we describe our efforts to prove the Coppersmith–Sorkin conjecture by considering the more general situation where the entries xij of X are chosen independently from different distributions. In particular, we require that xij be chosen from the exponential distribution with mean 1/ricj. We conjecture an explicit formula for the expected value of the minimum k‐assignment of such X and give evidence for this formula. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 33–58, 2002
Image data compression with nonuniform block segmentation and luminance approximation using bilinear curved surface patches
Authors: Hasegawa Makoto , Yamasaki Issei
Published: September 2002

A grayscale image is subdivided into nonuniform blocks and luminance values in each block are approximated by a bilinear curved surface patch. (1) Comparison with a method using triangular plain patches shows that a bilinear curved surface patch is more efficient. (2) Encoding luminance values on block vertices which construct patch is discussed. A method of encoding by adaptive prediction with Z‐scanning is proposed. (3) The S/N of the reconstructed image (ITE test chart: a portrait with monotonous background under 0.38 bpp) is higher than the case of down‐sampling JPEG. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 31–40, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10097
A dynamical model of figure‐ground reversal perception based on the role of visual attention
Authors: Yasukochi Ken , Sakaguchi Yutaka
Published: September 2002

In an attempt to clarify the dynamical process in human visual perception, we propose a neural network model explaining the figure‐ground reversal phenomenon of a three‐dimensional ambiguous figure, and examine its behavior in numerical experiments. In contrast to conventional models that explain perceptual reversal at a “symbolic representation level” using the oscillation between two memorized patterns in a network, our model tries to explain this phenomenon at a “structural representation level.” That is, the model has a field that represents the 3D structure of the visual input and the spatial distribution of visual attention, where the attention and structural representation interact with each other to bring dynamical change in the perceived structure. Another important feature of our model is that it reflects both space‐oriented and object‐oriented properties of visual attention. By discussing the structure and operation of our model, we introduce the concept of the “dynamics of perception and attention” as a general framework for understanding the dynamical transition of human visual perception. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 21–30, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10104
Extraction and classification of pulmonary organs based on thoracic 3D CT images
Authors: Tozaki Tetsuya , Kawata Yoshiki , Niki Noboru , Ohmatsu Hironobu
Published: September 2002

Recent progress in helical CT technology has given rise to considerable interest and expectations regarding diagnosis based on 3D CT images. In this context, computer‐aided diagnosis techniques for 3D CT images are required. This study introduces a method for analysis of thoracic 3D CT images, which contain important information for lung cancer diagnosis. The lung field includes the bronchi and pulmonary arteries and veins, as well as other organs; lung cancer influences these organs in a complicated and intermixed way. The proposed method supports extraction and classification of bronchi, arteries, and veins from thoracic 3D CT images using anatomical knowledge and 3D image processing technologies, and analysis of the relations between these pulmonary organs and suspected lung cancer. The extraction of pulmonary organs includes removal of bias components, extraction of bronchi and blood vessels, discrimination between bronchi and blood vessels, and identification of arteries and veins among blood vessels. Quantitative relations between suspected lung cancer and adjacent pulmonary organs are found. The effectiveness of the proposed method is shown using 3D CT images of healthy and cancerous lungs. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 42–53, 2001
A stochastic speech understanding method to generate interlingual representations
Authors: Tanigaki Koichi , Sagisaka Yoshinori
Published: September 2002

The purpose of this paper is to create an understanding system that can reduce the recognition error that prevents semantic analysis, and that is robust to speech input. A method is proposed in which semantic analysis and speech recognition are integrated on the basis of a statistical model, and the procedure is optimized as a high‐level recognition process from speech to semantics. As a method of realizing the idea effectively and efficiently, search of the word graph by means of a decision tree is proposed. Using the proposed method, an identification experiment is performed for the semantics represented by the intermediate language. It is a problem of segmentation of utterances into an average of 1.6 semantic units, and the assignment of the semantic units to 7600 classes characterized by combinations of utterance action and concept. In the speech recognition experiment the understanding error is improved by 8.5% compared to the case in which the 1‐best recognition candidate is input. © 2002 Scripta Technica, Syst Comp Jpn, 33(3): 52–62, 2002
Shell, Nigeria and the Ogoni. A study in unsustainable development: II. Corporate social responsibility and ‘stakeholder management’ versus a rights‐based approach to sustainable development
Authors: Boele Richard , Fabig Heike , Wheeler David
Published: September 2002

In the first paper in this trilogy (Boeleet al., 2001) we described the history of the Royal Dutch/Shell Group from its inception in 1890 through to the year 2000, discussed briefly the importance of corporate reputation to the group and described the significant impacts on Shell of the events of 1995 in Nigeria. We traced the relationship of the Shell Petroleum Development Corporation in Nigeria to impacts on the natural and social environments of the Niger Delta and more specifically on the Ogoni. Finally we discussed the emergence of political resistance and significant conflict between Shell and the Movement for the Survival of the Ogoni People (MOSOP) and concluded that, despite significant apparent changes in attitude at the group level, distrust and antipathy towards Shell remained entrenched in Ogoni. In this second paper, we explore in more detail issues raised by economic globalization for the practice of corporate social responsibility and stakeholder management, and contrast these concepts with an alternative ‘rights‐based’ approach to sustainable development. We relate our observations to Shell's current approach and conclude that the Shell group and specifically the Shell Petroleum Development Corporation in Nigeria may require an alternative approach to sustainable development if they wish to merit the full confidence of communities in areas of the world as complex and distressed as Ogoni. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Towards strategic planning and regional sustainability: Hong Kong in the Pearl River Delta Region
Authors: Chan Roger C. K.
Published: September 2002

This paper examines the wider spatial and governmental context for promoting sustainable development policies in Hong Kong. It examines the spatial frameworks and the territory‐specific approaches adopted in Hong Kong since the 1970s. Despite the claim of a non‐interventionist approach, government intervention for the purposes of promoting economic growth was evident in the development model of Hong Kong under the British rule. Additionally, the notion of strategic planning at the regional level was absent from the spatial framework. This was so even with the growing economic interaction between Hong Kong and the other cities in the Pearl River Delta Region (PRDR) in the 1980s and remained so in the early years of the SAR government. With economic integration between Hong Kong and the PRDR, strategic planning has to take on a different form. The diversity of the socio‐economic context and the complexity of political processes in the PRDR offer enormous opportunities to all stakeholders. Hong Kong should be more proactive in bringing the region together with a view to attaining regional sustainability. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
Environmental policy and planning in Hong Kong: an emerging regional agenda
Authors: Hills Peter
Published: September 2002

For the past 20 years, environmental policy in Hong Kong has been driven by responses to a variety of local problems resulting in an array of environmental ordinances and supporting regulations addressing air, water and noise pollution problems, waste management and the use of EIA in the development planning process. Hong Kong's approach to environmental policy has been based on the conventional ‘command and control’ model of environmental management. It has, however, become increasingly apparent that many of Hong Kong's environmental problems cannot be effectively addressed solely by local initiatives but must involve broader collaborative efforts with authorities in neighbouring Guangdong Province. Furthermore, the Hong Kong SAR's efforts to address sustainability issues, which are still at an early stage, may also be facilitated by a regional rather than purely local perspective as well as by one that explores the utility of the ecological modernization model. This paper discusses the recent evolution of environmental policy in Hong Kong, the emergence of a regional environmental management agenda and the potential of ecological modernization as a basis for the development of a broader strategy to manage the environmental problems of the Pearl River Delta Region. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.