bluuebunny/crossref_metadata_2025 huggingface dataset:
Flat polymer ribbons and other shapes by electrospinning
Authors: Koombhongse Sureeporn , Liu Wenxia , Reneker Darrell H.
Published: September 2002

In addition to round nanofibers, electrospinning a polymer solution can produce thin fibers with a variety of cross‐sectional shapes. Branched fibers, flat ribbons, ribbons with other shapes, and fibers that were split longitudinally from larger fibers were observed. The transverse dimensions of these asymmetric fibers were typically 1 or 2 μm, measured in the widest direction. A correlation of the branches and bends, observed in high‐frame‐rate videography of the electrified jets of polymer solutions from which the ribbons and branched fibers were produced, suggest that these phenomena occur at scales ranging from around 1 mm to 1 μm. The observation of fibers with these cross‐sectional shapes from a number of different kinds of polymers and solvents indicates that fluid mechanical effects, electrical charge carried with the jet, and evaporation of the solvent all contributed to the formation of the fibers. The influence of a skin on the jets of polymer solutions accounts for a number of the observations. The observed shapes can be used as guides for the extension of mathematical or computer‐generated models for the electrospinning process. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2598–2606, 2001
Effective interaction parameter between branched and linear polystyrene
Authors: Greenberg C. C. , Foster M. D. , Turner C. M. , Corona‐Galvan S. , Cloutet E. , Quirk R. P. , Butler P. D. , Hawker C.
Published: September 2002

Values of the effective interaction parameter (χ) between regular, long‐branched polystyrene chains and their linear analogues were measured with small‐angle neutron scattering for several star‐branched chains and one comb‐type polymer. The contribution to this interaction due to architecture alone increases monotonically with star functionality for the set of polymers studied here. The interaction appears to be less sensitive to variations in arm size than would be expected from fluctuation theory predictions by G. H. Fredrickson, A. Liu, and F. S. Bates (Macromolecules 1994, 27, 2503) for a purely entropic interaction due to architecture. The change in χ with the volume fraction of the star in the blend is in agreement with the theory, however. The magnitudes of the interaction in the star/linear blends are small enough that bulk phase separation is unlikely, whereas that in the comb/linear blend is about 20 times higher for the same number of arms. Thus, bulk phase separation can be readily expected for comb/linear blends at commercially relevant values of molecular weights. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2549–2561, 2001
Crystal growth rate in ultrathin films of poly(ethylene oxide)
Authors: Dalnoki‐Veress K. , Forrest J. A. , Massa M. V. , Pratt A. , Williams A.
Published: September 2002

Many dynamical properties of polymers, including segmental relaxation and chain diffusion, exhibit anomalies in thin‐film samples. We extend the studies of thin‐film dynamics to the case of semicrystalline polymers and present a study of the crystal growth rate for thin films of poly(ethylene oxide). We used optical microscopy and quartz crystal microbalance techniques to characterize the kinetics of crystallization for films with thicknesses from 40 to 1000 nm for a range of temperatures near the melting point. A remarkable slowing down of the crystal growth is observed at all temperatures studied for films with a thickness of less than ∼100 nm. The results can be used to suggest reductions of the mobility of chains at the crystal/amorphous interface. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2615–2621, 2001
Transesterification kinetics of poly(ethylene terephthalate) and poly(ethylene 2,6‐naphthalate) blends with the addition of 2,2′‐bis(1,3‐oxazoline)
Authors: Yang Haihua , He Jian , Liang Borun
Published: September 2002

The kinetics of the transesterification reaction between poly(ethylene terephthalate) (PET) and poly(ethylene 2,6‐naphthalate) (PEN) with and without the addition of a chain extender were studied with 1H NMR. Different kinetic approaches were considered, and a second‐order, reversible reaction was accepted for the PET/PEN reactive blend system. The addition of 2,2′‐bis(1,3‐oxazoline) (BOZ) promoted the transesterification reaction between PET and PEN in the molten state. The activation energy of the transesterification reaction for the PET/PEN reactive blend with BOZ (94.0 kJ/mol) was lower than that without BOZ (168.9KJ/mol). The rate constant k took an almost constant value for blend samples with different compositions mixed at 275 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2607–2614, 2001
Crystallization and chain conformation of semicrystalline and amorphous polymer blends studied by wide‐angle and small‐angle scattering
Authors: Huang Ching‐I , Chen Jun‐Rong
Published: September 2002

We examine the crystallization and chain conformation behavior of semicrystalline poly(ethylene oxide) (PEO) and amorphous poly(vinyl acetate) (PVAc) mixtures with wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and small‐angle neutron scattering (SANS) experiments. For blends with PEO weight fractions (wtPEO) greater than or equal to 0.3, below the melting point of PEO, the WAXD patterns reveal that crystalline PEO belongs to the monoclinic system. The unit‐cell parameters are independent of wtPEO. However, the bulk crystallinity determined from WAXD decreases as wtPEO decreases. The scattered intensities from SAXS experiments show that the systems form an ordered crystalline/amorphous lamellar structure. In a combination of WAXD and SAXS analysis, the related morphological parameters are assigned correctly. With the addition of amorphous PVAc, both the average amorphous layer thickness and long spacing increase, whereas the average crystalline layer thickness decreases. We find that a two‐phase analysis of the correlation function from SAXS, in which the scattering invariant is linearly proportional to the volume fraction of lamellar stacks, describes quantitatively the crystallization behavior of PEO in the presence of PVAc. When wtPEO is close to 1, the samples are fully spaced‐filled with lamellar stacks. As wtPEO decreases from 1.0 to 0.3, more PVAc chains are excluded from the interlamellar region into the interfibrillar region. The fraction outside the lamellar stacks, which is completely occupied with PVAc chains, increases from 0 to 58%. Because the radius of gyration of PVAc with a random‐coil configuration determined from SANS is smaller than the average amorphous layer thickness from SAXS, we believe that the amorphous PVAc chains still persist with a random‐coil configuration even when the blends form an ordered structure. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2705–2715, 2001
Ryanodine receptor acts as a sensor for redox stress
Authors: Pessah Isaac N
Published: September 2002

Ryanoids have not attained importance as insecticides, but the increasing number of xenobiotic effectors known to influence Ca2+ signalling by interaction with ryanodine receptors (RyRs) may serve to identify new targets for insect control. A historical review of redox control of microsomal Ca2+ transport is given here, followed by recent evidence indicating that hyperactive Cys residues are an essential component of a transmembrane redox sensor. Focus is on the role of sulfhydryl chemistry in RyR regulation; metabolic quinonoid intermediates from pesticides and other environmental contaminants are of interest in this context.

© 2001 Society of Chemical Industry
Sensitivity of Venturia inaequalis to trifloxystrobin
Authors: Küng Färber Ruth B , Chin Khoon Min , Leadbitter Neil
Published: September 2002

The sensitivity of Venturia inaequalis to trifloxystrobin was monitored by both in vitro (spore germination) and in vivo tests (on apple seedlings). There was good correlation between the in vitro and in vivo results. Baseline sensitivity was established with 95 bulk isolates from Europe between 1995 and 1998 which showed a narrow sensitivity range‐factor of up to 17 between the least and most sensitive isolates. Monitoring of populations originating from trifloxystrobin‐treated and untreated orchards between 1995 and 1999 showed only sensitive isolates and no performance deficiencies were reported. Data also show that trifloxystrobin is not cross‐resistant to anilinopyrimidines and triazoles, but is cross‐resistant to kresoxim‐methyl, another strobilurin which also inhibits the cytochrome bc1 enzyme complex at the Qo‐site in the respiration chain of fungal mitochondria (QoI inhibitors). Under experimental conditions from a specific trial site in Switzerland, where trifloxystrobin has been tested since 1994, isolates containing conidia resistant to Qo inhibitors were detected in 1997 and 1999. However no obvious performance deficiencies were reported. Nevertheless these results demonstrate a risk for the development of practical resistance in V inaequalis to Qo inhibitors and therefore a need to apply resistance management principles strictly.

© 2002 Society of Chemical Industry
High level methoprene resistance in the mosquito Ochlerotatus nigromaculis (Ludlow) in Central California
Authors: Cornel Anthony J , Stanich Matthew A , McAbee Rory D , Mulligan F Steve
Published: September 2002

In the summer of 1998, failures of methoprene field applications to control the mosquito Ochlerotatus nigromaculis (Ludlow) were noticed in several pastures in the outskirts of Fresno, California, USA. Effective control with methoprene had been achieved for over 20 years prior to this discovery. Susceptibility tests indicated that the Fresno Oc nigromaculis populations had developed several thousand‐fold higher LC50 and LC90 tolerance levels to methoprene compared with methoprene‐naïve populations. The synergists piperonyl butoxide (PBO), S,S,S‐tributyl phosphorotrithioate and 3‐octylthio‐1,1,1‐trifluoro‐2‐propanone had little synergistic effect, suggesting that the mechanism of methoprene tolerance was not mediated by P450 monooxygenase or carboxylesterase enzyme degradation. As part of initiating a resistance management strategy, partial reversion back to methoprene susceptibility was achieved in a resistant population after six consecutive applications of Bacillus thuringiensis israelensis Goldberg & Marga coupled with two oil and two pyrethrum + PBO applications.

© 2002 Society of Chemical Industry
Field‐simulator studies of insecticide resistance to dimethylcarbamates and pyrethroids conferred by metabolic‐ and target site‐based mechanisms in peach‐potato aphids, Myzus persicae (Hemiptera: Aphididae)
Authors: Foster Stephen P , Denholm Ian , Devonshire Alan L
Published: September 2002

A range of insecticides was applied at recommended application rates against populations of Myzus persicae (Sulzer) carrying various combinations of three insecticide resistance mechanisms (carboxylesterase‐based metabolic resistance and two target‐site mechanisms, known as MACE and kdr), supported on either Chinese cabbage or potatoes in field simulator cages. Patterns of response were similar on both host species. MACE conferred extreme resistance to pirimicarb and triazamate (dimethylcarbamate insecticides). The kdr mechanism was associated with resistance to lambda‐cyhalothrin, cypermethrin and deltamethrin (pyrethroid insecticides). A mixture of pirimicarb plus lambda‐cyhalothrin was only effective against M persicae not carrying kdr or carrying kdr and low carboxylesterase‐based resistance. None of the insecticides tested was effective against M persicae carrying both MACE and kdr resistance. The implications of these findings for the formulation of control strategies, based on regular monitoring of resistance genotype frequencies, are discussed.

© 2002 Society of Chemical Industry
Antibacterial activity of bactenecin 5 fragments and their interaction with phospholipid membranes
Authors: Tokunaga Yoko , Niidome Takuro , Hatakeyama Tomomitsu , Aoyagi Haruhiko
Published: September 2002

Bactenecin 5 (Bac 5) is an antibacterial 43mer peptide isolated from bovine neutrophils. It consists of an Arg‐rich N‐terminal region and successive repeats of Arg‐Pro‐Pro‐Ile (or Phe). We synthesized Bac 51‐23 and several related peptides to clarify the roles these regions play in antibacterial activity. An assay of antibacterial activity revealed that such activity requires the presence of Arg residues at or near the N‐terminus, as well as a chain length exceeding 15 residues. None of the peptides exhibited haemolytic activity. Polyproline II‐like CD curves were observed for most of the peptides. Measurements of the membrane perturbation and fusion indicated that the perturbation and fusogenic activities of the peptides were, generally, parallel to their antibacterial activities. Amino acid substitution in the repeating region had some effect on antibacterial activity. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Configuration and racemization determination of cysteine residues in peptides by chiral derivatization and HPLC: application to oxytocin peptides
Authors: Szabó Sándor , Szókán Gyula , Khlafulla Abdulrahim M. , Almás Márta , Kiss Csaba , Rill Attila , Schön István
Published: September 2002

An improved RP‐HPLC method was developed for the determination of the configuration and stereochemical purity of cysteine residues in peptides. The method consists of oxidation of cysteine and cystine residues to cysteic acid, followed by hydrolysis and pre‐column chiral derivatization with Val‐Marfey's reagent. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Synthesis of linear and comb‐like peptide constructs containing up to four copies of a T cell epitope and their capacity to stimulate T cells
Authors: Mack Jürgen , Falk Kirsten , Rötzschke Olaf , Walk Tilmann , Strominger Jack L. , Jung Günther
Published: September 2002

Polypeptide constructs containing up to four copies of the T cell epitope 306‐318 of influenza virus haemagglutinin have been synthesized on solid phase. Between the copies, a non‐natural PEG‐based spacer amino acid has been introduced. The oligomeric epitopes were analysed by RP‐HPLC and ES‐MS. The arrangement of the epitopes within the peptide constructs was either linear or comb‐like. The proliferative response in a T helper cell assay induced by these oligomerized epitopes has been tested, showing that the linearly arranged epitopes are more effective than the comb‐like oligomers. Copyright © 2001 European Peptide Society and John Wiley & Sons, Ltd.
Amino acid modifications in the wild type sequence p53 232–240 overcome the poor immunogenicity of this self tumour epitope
Authors: Baratin Myriam , Kayibanda Michèle , Ziol Marianne , Romieu Raphäelle , Briand Jean‐Paul , Guillet Jean‐Gérard , Viguier Mireille
Published: September 2002

A major limitation in antigen‐specific cancer vaccines is that most of the tumour antigens that are potent candidates for broad applicability originate from self proteins. The peptides presented by tumour cells are derived from tissue‐specific differentiation proteins, from proteins altered by genetic mutation or by non mutated proteins that are normally silent in most adult tissues. As a consequence, T‐cell responses elicited against those antigens are rather weak. Several data showed that amino acid modifications could enhance the immunogenicity of such antigens by priming T‐cells that have escaped central tolerance based on a poor avidity. In this regard, this strategy could be powerful for inducing immunity against tumours. The present report focuses on the murine wild type epitope p53 232–240 that is poorly immunogenic. It shows that substitution of the two cysteine residues by serine or amino butyric acid derivatives and substitution of the two methionine residues by norleucine residues resulted in enhanced stability of the MHC/peptide complex. The MHC binding affinity of analogue peptides was enhanced between 10 and 100 fold. They were also potent immunogens, stronger than was the original wild type epitope; T‐cell responses were increased up to 50 times. Moreover, the effector T‐cells elicited by three of these peptides cross reacted with the natural epitope. These observations have important implications for strategies that use the modified‐peptide epitope. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Study of the yeast Saccharomyces cerevisiae F1FO‐ATPase ε‐subunit
Authors: Aznar‐Derunes Céline , Manigand Claude , Picard Philippe , Dautant Alain , Goetz Michael , Schmitter Jean‐Marie , Precigoux Gilles
Published: September 2002

The yeast Saccharomyces cerevisiae F1FO‐ATPase ε‐subunit (61 residues) was synthesized by the solid‐phase peptide approach under both acidic and basic strategies. Only the latter strategy allowed us to obtain a pure ε‐subunit. The strong propensity of the protein to produce few soluble dimeric species depending on pH has been proved by size‐exclusion chromatography, electrophoresis and mass spectrometry. A circular dichroism study showed that an aqueous solution containing 30% trifluoroethanol or 200 mM sodium dodecyl sulphate is required for helical folding. In both solvents at acidic pH, the ε‐subunit is soluble and monomeric. Copyright © 2002 European Peptide Society and John Wiley & Sons, Ltd.
Transient rate matrix determination for the complex system
Authors: Qamber Isa S.
Published: September 2002

This paper presents new techniques dealing with the reliability of complex systems. A power station reliability assessment model is used to illustrate the approach. Before calculating the state transient probabilities for the overall electrical power plant, the failure and repair rates of each generating unit are needed. These two coefficients can form a transition rate matrix, which represents each generator. To form the overall system a special technique is required. In the present study the direct‐differentiation and the Kronecker algebra methods are used to form the overall transition rate matrix, which represents the whole system. Forming the overall system is the first part (major part) of the current study. The second part is to calculate the state transient probabilities, following the Adams method. Two electric power plants from the State of Bahrain are analysed as examples. Copyright © 2001 John Wiley & Sons, Ltd.
Arsenosugar identification in seaweed extracts using high‐performance liquid chromatography/electrospray ion trap mass spectrometry
Authors: Miguens‐Rodriguez Maria , Pickford Russell , Thomas‐Oates Jane E. , Pergantis Spiros A.
Published: September 2002

The development of analytical techniques suitable for providing structural information on a wide range of elemental species is a growing necessity. For arsenic speciation a variety of mass spectrometric techniques, mainly inductively coupled plasma mass spectrometry (ICP‐MS) and electrospray tandem mass spectrometry (ES‐MS/MS) coupled on‐line with high‐performance liquid chromatography (HPLC), are in use. In this paper we report the identification of arsenic species present in samples of marine origin (seaweed extracts) using ES ion trap mass spectrometry (IT) multistage mass spectrometry (MSn). Both reversed‐phase and anion‐exchange HPLC have been coupled on‐line to ES‐ITMS. Product ion scans with multiple stages of tandem MS (MSn; n = 2–4) were used to acquire diagnostic data for each arsenosugar. The spectra contain structurally characteristic fragment ions for each of the arsenosugars examined. In addition it was observed that upon successive stages of collision‐induced dissociation (CID) a common product ion (m/z 237) was formed from all four arsenosugars examined. This product ion has the potential to be used as an indicator for the presence of dimethylated arsenosugars (dimethylarsinoylribosides). The HPLC/ES‐ITMSn method developed allows the sensitive identification of arsenosugars present in crude seaweed extracts without the need for extended sample preparation. In fact, sample preparation requirements are identical to those typically employed for HPLC/ICP‐MS analysis. Additionally, the resulting product ions are structurally diagnostic of the arsenosugars examined, and tandem mass spectra are reproducible and correspond well to those obtained using other low‐energy CID techniques. As a result, the HPLC/ES‐ITMSn approach minimises the potential for arsenic species misidentification and has great potential as a means of overcoming the need for characterised standards. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of the saliva from patients with oral cancer by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Chen Yu‐Chie , Li Tzu‐Ying , Tsai Ming‐Fei
Published: September 2002

Using matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS), this study analyzed the saliva obtained from patients with oral cancer and compared these mass spectra with those obtained from healthy controls. Saliva without pre‐treatment was mixed directly with a sinapinic acid matrix. Alpha‐amylase (57 kDa) dominated the high mass range in the MALDI mass spectra of the saliva from healthy subjects, but the peak was suppressed for patients with oral cancer and was replaced by a peak at m/z 66 k in the spectra of patients' samples (15 out of 20). Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) with in‐gel tryptic digestion combined with matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) was employed to characterize this 66‐kDa protein, which was thus shown to be albumin. However, based on SDS‐PAGE results, concentrations of both alpha‐amylase and albumin in patients' saliva were significantly higher than those in healthy subjects. This discrepancy was shown to be due to MALDI suppression effects due to the albumin. MALDI‐MS thus has potential as a possible rapid diagnostic screening tool for oral cancer. Copyright © 2002 John Wiley & Sons, Ltd.
In situ analysis of solvents on breath and blood: a selected ion flow tube mass spectrometric study
Authors: Wilson Paul F. , Freeman Colin G. , McEwan Murray J. , Milligan Daniel B. , Allardyce Randall A. , Shaw Geoffrey M.
Published: September 2002

We report measurements of residual vapour levels of xylenes and trimethylbenzenes, present following a floor re‐surfacing procedure, using the technique of selected ion flow tube mass spectrometry (SIFT‐MS). A subject exposed to controlled amounts of xylene and mesitylene was monitored by direct breath exhalation over a 4‐hour period after exposure to the volatile organic compounds (VOCs) had stopped. The headspace gases above 5‐mL blood samples taken over this period were also monitored. The decays of the solvent levels with time were fitted to a two‐compartment model with residence times for xylene and mesitylene of 0.37 h and 0.38 h, respectively (compartment one) and 2.5 h and 2.8 h, respectively (compartment two). Copyright © 2002 John Wiley & Sons, Ltd.
Small angle neutron scattering measurements of synthetic polymer dispersions in matrix‐assisted laser desorption/ionization matrixes
Authors: Bauer Barry J. , Byrd H. C. Michelle , Guttman Charles M.
Published: September 2002

Small angle neutron scattering (SANS) is used to measure the size and the dispersion of synthetic polymers in matrix‐assisted laser desorption/ionization (MALDI) matrixes. Deuterated polystyrene (DPS) and dithranol in tetrahydrofuran were deposited by electrospray onto a substrate for small angle neutron scattering (SANS) measurements. DPS with 6050 and 27 000 g mol−1 molecular masses were prepared at mass fractions between 0.2 and 6%. All samples contained large aggregates of DPS with characteristic sizes >200 Å that represent hundreds of aggregated chains. Samples of mass fraction 1% DPS (6050 g mol−1) in 2,5‐dihydroxybenzoic acid, all‐trans‐retinoic acid, and sinapinic acid also have large zero angle scattering characteristic of large aggregates. The morphological trend obtained from the SANS measurements of the DPS aggregate size in the four matrixes is dithranol > 2,5‐dihydroxybenzoic acid > all‐trans‐retinoic acid > sinapinic acid. These measurements indicate that DPS in dithranol exhibits the most strong phase separation, while DPS in sinapinic acid shows considerable domain mixing. All of these matrixes produce MALDI signal strength under appropriate conditions, suggesting that strong phase separation does not diminish the signal‐to‐noise ratio. DPS (188 000 g mol−1) in biphenyl was used as a model system of a matrix that can be either crystalline or amorphous. SANS data shows that above the biphenyl melting point, a conventional solution is formed that has molecularly dispersed polymers. Upon crystallization, there is strong aggregation of the DPS into large domains. Therefore, the crystalline matrixes commonly used in MALDI measurements probably cause large aggregations of polymers to be present during the MALDI process. Published in 2002 by John Wiley & Sons, Ltd.
Generic fast gradient liquid chromatography/tandem mass spectrometry techniques for the assessment of the in vitro permeability across the blood–brain barrier in drug discovery
Authors: Chu Inhou , Liu Fei , Soares Anthony , Kumari Pramila , Nomeir Amin A.
Published: September 2002

Rapid, generic gradient liquid chromatography/tandem mass spectrometry (LC/MS/MS) assays, designed to accelerate sample analyses, have been developed to keep pace with the productivity of advanced synthetic procedures. In this study, LC/MS/MS was combined with an in vitro, cell‐based, blood–brain barrier (BBB) model to evaluate the potential of new chemical entities (NCEs) to cross the BBB. This in vitro assay provides the permeability of discovery compounds across a monolayer of a primary culture of bovine brain microvessel endothelial cells in a fraction of the time that is required for in vivo studies (brain/plasma concentrations), using only 2 mg of the compound. The results are consistent with in vivo brain/plasma concentration ratio data. Copyright © 2002 John Wiley & Sons, Ltd.
Poly(amide ester)s from 2,6‐pyridinedicarboxylic acid and ethanolamine derivatives: identification of macrocycles by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Chevallier Pascale , Soutif Jean‐Claude , Brosse Jean‐Claude , Brunelle Alain
Published: September 2002

The influence of the polycondensation pathway and aminoalcohol structure was investigated in the synthesis of poly(amide ester)s by polytransesterification from ethyl pyridine‐2,6‐dicarboxylate and 2‐amino‐2‐methylpropan‐1‐ol or the corresponding bis(amide alcohol), or by polycondensation from the diacid dichloride. Both linear and cyclic structures were identified by steric exclusion chromatography (SEC) and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS). Transesterification led to cyclic oligomers (macrocycles) with 2–14 pyridine moities in the ring whereas polycondensation from the diacid dichloride gave low molecular weight polymers (Mn = 1800) and macrocycles. Copyright © 2002 John Wiley & Sons, Ltd.
A theorem for UGAS and ULES of (passive) nonautonomous systems: robust control of mechanical systems and ships
Authors: Fossen Thor. I. , Loría Antonio , Teel Andrew
Published: September 2002

The main contribution of this paper is a theorem to guarantee uniform global asymptotic stability (UGAS) and uniform local exponential stability (ULES) for a class of nonlinear non‐autonomous systems which includes passive systems. These properties (and a uniform local Lipschitz condition) guarantee robustness of stability while weaker properties, like uniform global stability plus global convergence, do not. Our main result is then used in the tracking control problem of mechanical systems and ships. We use an adaptive backstepping design and prove UGAS of the closed‐loop tracking error system, in particular, we obtain that both the tracking and parameter estimation errors converge uniformly globally to zero. Copyright © 2001 John Wiley & Sons, Ltd.
Linear, parameter‐varying control and its application to a turbofan engine
Authors: Balas Gary J.
Published: September 2002

This paper describes application of parameter‐dependent control design methods to a turbofan engine. Parameter‐dependent systems are linear systems, whose state‐space descriptions are known functions of time‐varying parameters. The time variation of each of the parameters is not known in advance, but is assumed to be measurable in real‐time. Three linear, parameter‐varying (LPV) approaches to control design are discussed. The first method is based on linear fractional transformations which relies on the small gain theorem for bounds on performance and robustness. The other methods make use of either a single (SQLF) or parameter‐dependent (PDQLF) quadratic Lyapunov function to bound the achievable level of performance. The latter two techniques are used to synthesize controllers for a high‐performance turbofan engine. A LPV model of the turbofan engine is constructed from Jacobian linearizations at fixed power codes for control design. The control problem is formulated as a model matching problem in the ℋ︁∞and LPV framework. The objective is decoupled command response of the closed‐loop system to pressure and rotor speed requests. The performance of linear, ℋ︁∞point designs are compared with the SQLF and PDQLF controllers. Nonlinear simulations indicate that the controller synthesized using the SQLF approach is slightly more conservative than the PDQLF controller. Nonlinear simulations with the SQLF and PDQLF controllers show very robust designs that achieve all desired performance objectives. Copyright © 2002 John Wiley & Sons, Ltd.
Identification of linear parameter varying models
Authors: Bamieh Bassam , Giarré Laura
Published: September 2002

We consider identification of a certain class of discrete‐time nonlinear systems known as linear parameter varying system. We assume that inputs, outputs and the scheduling parameters are directly measured, and a form of the functional dependence of the system coefficients on the parameters is known. We show how this identification problem can be reduced to a linear regression, and provide compact formulae for the corresponding least mean square and recursive least‐squares algorithms. We derive conditions on persistency of excitation in terms of the inputs and scheduling parameter trajectories when the functional dependence is of polynomial type. These conditions have a natural polynomial interpolation interpretation, and do not require the scheduling parameter trajectories to vary slowly. This method is illustrated with a simulation example using two different parameter trajectories. Copyright © 2002 John Wiley & Sons, Ltd.
Development and operation of a document database for university research and education activities
Authors: Nonaka Yusuke , Inoue Sozo , Hatano Katsuhiko , Harada Tsutomu , Nomura Yoshinari , Iwaihara Mizuho , Mine Tsunenori , Ushijima Kazuo
Published: September 2002

The academic staff research and education activity database of Kyushu University is a document database system which enables each academic staff member to input and update his or her activity report, administrators to maintain the database, and visitors to search and read reports via the Internet.

Those databases and user interfaces can handle mixed report formats by storing metadata of formats and constraints. Through an analysis of the update history of the system and e‐mail records between users and developers, we confirmed that distributed administration style reduced human work load and that the majority of bugs are confined to small components. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 41–53, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10043
An algorithm for an eye tracking system with self‐calibration
Authors: Takegami Takeshi , Gotoh Toshiyuki , Ohyama Ghen
Published: September 2002

This paper proposes a simple and highly accurate eye tracking system. The eye image is observed by a system, such as an infrared eye tracking system, where the relative position between the head and the camera is kept invariant. Calibration where the examinee is instructed to gaze at a particular marker is avoided, and the calibration is executed automatically using only the input time sequence images. In the eye image, when the relative position to the camera is kept invariant, two queues exist to estimate the eye direction, which are the center coordinate and the flatness of the pupil. There are problems in the accuracy and the stability of the detection in the flatness data, however, although the absolute direction can be estimated. In the study, the eye direction is estimated as follows. The flatness is estimated by using multiple images. The eye parameters, such as the radius and the center of the eye rotation, are corrected, and the eye direction is estimated with stability. An evaluation experiment used actual eye images, and it was found that a more accurate measurement is realized, compared to the estimation of the eye direction based on flatness. Thus, the usefulness of the proposed method is demonstrated. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(10): 10–20, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10125
Development of teaching material for cultivating logical thinking ability in a confrontational game system
Authors: Sasaki Hitoshi , Takeya Makoto
Published: September 2002

The importance of cultivating logical thinking ability has been strongly emphasized. In addition, logical aptitude tests are included in entrance and employment exams, and logical thinking ability is used as a criterion in admission and hiring decisions. Consequently, this study has developed material for cultivating logical thinking ability in the form of a confrontational (two‐player) game learning system. The programs constructed by students combat each other, and are then analyzed and improved as a means of supporting the cultivation of logical thinking ability. This paper proposes such a resource for cultivating logical thinking ability and reports the results of its experimental use in teaching high school students. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 1–10, 2001
Bitstream scaling by reference frame altering
Authors: Shimizu Atsushi , Sagata Atsushi , Watanabe Hiroshi , Kobayashi Naoki
Published: September 2002

On the Internet, the transmission rates and the quality of the transmission paths vary with the user's connection environment. Thus, to provide image transmission services on the Internet, bitstream scaling techniques are essential to convert to any transmission rate in real time. Already proposed scaling methods include methods that reduce the number of coding bits for the DCT coefficients and methods that discard coded frames not referenced by other frames. However, the degrees of freedom in scaling in previous methods are inadequate to provide image transmission services on the Internet. In this paper, we propose a bitstream scaling method that discards the reference frames to limit the computational costs. In the proposed method, instead of a search for motion vectors, new motion vectors are estimated from the original motion vectors and the reference relationship in motion‐compensated prediction is altered. The degrees of freedom in scaling can be expanded while limiting the computational costs. The estimated motion vectors are compared to the motion vectors detected from the decoded frame to verify the accuracy of the motion vector estimation method. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 11–21, 2001
A morphological filter with region expansion to extract minute convex regions and its applications to medical image processing
Authors: Hagihara Yoshihiro , Kobatake Hidefumi
Published: September 2002

In recent years morphological filters (M‐filters) have been used in a wide range of fields since they offer various capabilities through the use of the shape of structural elements in the image. In this paper the authors propose an M‐filter which can minimize the effect of the background for the purpose of extracting undefined minute convex regions such as lesions in medical X‐ray images. The proposed method is based on expanding the region by padding for each brightness level. In addition, the authors consider an approach to implement their proposed method effectively, then describe the resulting algorithm in detail. Experiments comparing the proposed method and a method using only conventional opening calculations are performed. In experiments using binary images and multibit simulation data and in experiments on the extraction of minute calcification images in a mammogram or kidney–lung shadows from real chest CTs, the proposed method was shown to be superior to the conventional method using opening calculations. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 22–31, 2001
A new fitness function for shape detection using genetic algorithm
Authors: Toyama Fubito , Shoji Kenji , Miyamichi Juichi
Published: September 2002

When genetic algorithms (GA) are used for shape detection, the fitness function (evaluation function for chromosomes) must be designed in an appropriate way. Considering shape detection in terms of finding the parameters of model objects to provide the best matching with an input edge image, the chromosome is defined in terms of the object's parameters, and the fitness function is defined in terms of the rate of matching between the edge image of a model object generated using the chromosome's parameters and the input edge image. In this study, the model image and input image are divided into four images each by applying four directional filters, and the fitness function is defined as the sum of the matching rates for each edge direction. Experiments with flat objects were performed to compare the proposed fitness with the conventional technique. The results suggested that the proposed method required slightly more computation time (about 10%) than the conventional fitness function while improving the matching rate from 49% to 93%. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 54–60, 2001
High‐speed production system using dynamic two‐way switching of match algorithm
Authors: Nambo Hidetaka , Kimura Haruhiko , Hirose Sadaki
Published: September 2002

Expert systems support reasoning based on experts' knowledge and data represented through a set of rules, thus substituting for human experts. Production systems are a popular tool for expert system building. However, production systems suffer from slow processing speed, and extensive research has been conducted to improve their performance. In particular, processing of high‐cost rules takes an extremely long time. This study offers dynamical switching between direct match algorithm, which was previously proposed for high‐cost rule processing, and conventional Rete algorithm; it is found that the two algorithms prove to make a complementary pair which ensures efficient processing. In addition, rules for which this dynamical switching is appropriate are defined, and efficiency of the proposed approach is confirmed through experiments with sample knowledge bases. © 2001 Scripta Technica, Syst Comp Jpn, 32(9): 61–70, 2001
Improvement of the method for monitoring autonomic nervous activity by pupillary flash response
Authors: Yamaji Kazutsuna , Hirata Yutaka , Usui Shiro
Published: September 2002

In our previous study, we proposed a noninvasive method for monitoring autonomic nervous activity from the changes in dynamic parameters of a pupillary flash response. The advantage of the method is that it allows independent evaluation of sympathetic and parasympathetic nervous activities. However, the sensitivity of the sympathetic parameter is lower than that of the parasympathetic one. This disadvantage should be eliminated for practical use. In this paper, an improved method that focuses on this issue is proposed. The improvement has been achieved by adopting a comblike flash response of which availability was examined based on the analysis using the pupillary muscle plant model. Validity of the improved method has been demonstrated by applying it to the subject whose autonomic nervous activity has been modified by sympathomimetic and sympatholytic drugs. © 2001 Scripta Technica, Syst Comp Jpn, 32(13): 23–30, 2001
Learning action sequences using recurrent neural network with multiresolutional channel
Authors: Morita Satoru
Published: September 2002

The author proposes a recurrent neural network structure that enables associations between resolution, field of view, and actions in order to connect actions with the surrounding view for executing multiresolutional vision control. In general, when a neural network is used, there are cases when some patterns cannot be learned. The current study describes obtaining surrounding views necessary for capturing actions by using a hereditary algorithm in order to control multiresolutional vision. The article demonstrates how in practice actions of a pan–tilt camera can be captured using multiresolutional vision control. © 2001 Scripta Technica, Syst Comp Jpn, 32(13): 31–40, 2001
Real‐time scheduling algorithms for maximum utilization of secondary battery in portable devices with discrete frequency control
Authors: Nakamoto Yukikazu , Tsujino Yoshihiro , Tokura Nobuki
Published: September 2002

The spread of portable devices has increased the importance of low‐power energy techniques. The authors have already proposed a real‐time scheduling algorithm which maximizes the utilization time of the secondary battery while preserving deadlines of real‐time tasks with arbitrary frequency control. This paper addresses a scheduling problem which maximizes the utilization time of the secondary battery with discrete frequency control. First, a decision problem corresponding to the scheduling problem is NP‐complete when the frequency can be changed on task switching. Second, when the frequency can be changed at an arbitrary time we propose an optimal scheduling algorithm which maximizes utilized time of the secondary battery under preserving a deadline of real‐time tasks, and demonstrate the correctness of the algorithm and its computation complexity. For each arrival task, the computation complexity of the algorithm is O(n) in general, where n is the number of tasks awaiting execution, and is O(1) in the amortized analysis when each task arrives in the order of its deadline. © 2002 Scripta Technica, Syst Comp Jpn, 33(3): 41–51, 2002
Struggling toward sustainability: considering grassroots development
Authors: Stevens Kris , Morris John
Published: September 2002

Grassroots development (GRD) has long been seen as a way of involving the uninvolved stakeholders, a problem identified in other types of development. In examining traditional GRD this paper demonstrates that many of the neo‐liberal leanings that have been identified as problematic in macro‐scale development are also found in traditional GRD. These are shown to be detrimental to project outcomes. This paper's main contribution is to embed communitarian assumptions into GRD, an action that leads to the articulation of a communitarian grassroots development (CGRD). Extant case studies and conceptual graphic interpretations are used to illustrate the dimensions of CGRD. Central is the need for personal growth and its consequent contribution to community. It is argued that CGRD leads to sustainable development, a goal unattained under neo‐liberal assumptions. Copyright © 2001 John Wiley & Sons, Ltd. and ERP Environment
Urban regeneration and community development in Scotland: converging agendas for action
Authors: Lloyd M. Gregory
Published: September 2002

Devolution is having a marked effect on policy design and delivery in Scotland. In particular, it is possible to identify a focus on a distinctive Scottish agenda, and in the priorities for action. Intervention is directed in particular at the community, in terms of its general well‐being, and in promoting positive discrimination for disadvantaged areas and groups. Community planning and Social Inclusion Partnerships are the vehicles for this approach. Significantly, the theme of leadership runs through these measures, and this may yet enable a more stable programme for community development to be sustained into the future. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment.
Dana Meadows: asking hard questions, speaking simple truths
Authors: Meadows Dennis
Published: September 2002

This paper was presented at the annual meeting of the System Dynamics Society, Atlanta, Georgia; 25 July 2001, in a special session in memory of Dana Meadows. In this talk, Dennis Meadows reviews Dana's career, the fundamental contributions she made to the field of system dynamics, and the continuing relevance of her work to the issues facing us today. Copyright © 2002 John Wiley & Sons, Ltd.
Using system dynamics to improve public participation in environmental decisions
Authors: Stave Krystyna A.
Published: September 2002

Dana Meadows believed that computer simulation models and systems thinking could be powerful tools for democracy, helping make social decisions and the assumptions on which they are based more transparent and open to public debate. She also believed that people should be more involved in making conscious and informed choices about their future. In the environmental arena, pressure to increase public participation in decision‐making is growing. Not only is public involvement seen as a cornerstone of democratic ideals, it is increasingly seen by decision‐makers as a practical means of putting decisions into effect. Involving the public in decision‐making helps avoid public obstruction of decisions and garners public resources for their implementation. However, traditional approaches to public involvement, which rely heavily on information campaigns, facilitated discussions, and public hearings for conveying information and capturing stakeholder input, frequently leave participants dissatisfied. They are often perceived as one‐way communication from agency experts to stakeholders or as a mechanism for powerful special interest groups to serve their own ends. System dynamics has the potential to improve public participation in environmental decisions by providing a framework for structured deliberation when stakeholders are involved in making decisions and a more transparent and participatory educational framework to persuade stakeholders to help implement decisions. This article describes a case study using group model building to support a stakeholder advisory group examining transportation and related air quality problems. One of the most valuable effects of the approach was the information feedback it added to the advisory process. Copyright © 2002 John Wiley & Sons, Ltd.
Assessment and monitoring in clinical trials when survival curves have distinct shapes: a Bayesian approach with Weibull modelling
Authors: Lecoutre Bruno , Mabika Bienvenu , Derzko Gérard
Published: September 2002

The comparison of Weibull distributions with unequal shape parameters, in the case of right censored survival data obtained from independent samples, is considered within the framework of Bayesian statistical methodology. The procedures are illustrated with the example of a mortality study where a new treatment is compared to a placebo. The posterior distributions about relevant parameters, which may provide support for a conclusion of clinical superiority of the treatment, and the predictive distributions, which may guide decision about early stopping at an interim analysis, are considered for a class of appropriate priors. Copyright © 2002 John Wiley & Sons, Ltd.