bluuebunny/crossref_metadata_2025 huggingface dataset:
Pharmacy data in epidemiological studies: an easy to obtain and reliable tool
Authors: Monster Taco B. M. , Janssen Wilbert M. T. , de Jong Paul E. , de Jong‐van den Berg Lolkje T. W. ,   for the PREVEND Study Group
Published: October 2002

Purpose

The agreement between drug use measured in computerized pharmacy records and patient interviews or questionnaires is generally good. However, most investigations on this subject studied selected populations or subsets. We studied the coverage of Dutch pharmacy data for our study cohort, and the agreement between the different sources.

Methods

We used the data from 8592 subjects of an on‐going population‐based study, focused on the impact of microalbuminuria (PREVEND). Data on drug use was collected in a questionnaire and at community pharmacies. Drug use was measured in the year preceding the questionnaire. Agreement between the sources was measured using kappa‐values, sensitivity and positive predictive value.

Results

Pharmacy data could be collected for 7568 (88%) of the study cohort. Pharmacy data and questionnaires showed good agreement for antihypertensives, lipid lowering drugs, oral antidiabetics and oral contraceptives, but poor agreement for nitrates, hormone replacement therapy and painkillers.

Conclusions

Pharmacy data could be collected for a large proportion of our cohort. For chronically used drugs pharmacy data generally agrees well with questionnaires. However, for drugs used for shorter periods, as needed, or also available over‐the‐counter, the agreement is not so good. Pharmacy data can be a valuable source of drug information in epidemiological studies. Copyright © 2002 John Wiley & Sons, Ltd.
Thermogravimetric analysis of polyurethane–polysulfone blends
Authors: Filip Daniela , Macocinschi Doina
Published: October 2002

Thermal decomposition of blends of a poly(ester urethane) and poly(ether sulfone) with or without poly(urethane sulfone), taken as a compatibilizing agent, was studied by thermogravimetric analysis under dynamic conditions. Theoretical mass loss curves were compared with experimental ones and it was found that the blends studied possessed lower thermal stability than the pure polymers, indicating the presence of interactions in the degradation process. The shifts between the theoretical and experimental curves became smaller as the amounts of polysulfone increased, confirming the thermal stabilisation effect of this polymer. The analysis of activation energy revealed, for both binary and ternary systems, that ECR (Tmax corresponding to the main decomposition stage of polysulfone) increased as the amount of this polymer increased and also the reaction order became zero. For the polyurethane decomposition stages and blending revealed no significant changes as far as activation energy and order of reaction were concerned.

© 2002 Society of Chemical Industry
Patterns of performance on the Stroop Color and Word Test in children with learning, attentional, and psychiatric disabilities
Authors: Golden Zarabeth L. , Golden Charles J.
Published: October 2002

The study presented here investigated the performance of children with learning, psychiatric, and attentional disabilities on the Stroop Color and Word Test. Forty‐three children diagnosed with a full battery of tests as learning disabled (LD [reading]) in grades K through 6 were matched on age, gender, ethnicity, and grade with 43 normal controls. They were also matched with groups of 43 children with psychiatric disorders and 43 children with attentional problems. All subjects were given the Stroop test, which took about 4 minutes per subject. The results indicated clear differences between the groups, with the LD and the psychiatric/attention deficit/hyperactivity disorder (ADHD) groups generating unique profiles different from the normal controls. The children with LD showed slower reading speed and less interference, while the subjects with ADHD and diagnoses showed impairment only on the Color‐Word score. A discriminant analysis using the three basic Stroop scales was able to significantly differentiate the LD group from the non–learning‐disabled (NLD) group (89%) and the LD group from a joint Psychiatric/ADHD group (86%). However, results were poorer for differentiating a joint LD/ADHD group from the NLD group (68%) and the LD from the ADHD group (59%). © 2002 Wiley Periodicals, Inc.
1H and 13C NMR study of a series of C‐9‐substituted 19‐norsteroids
Authors: Dallery Laurence , Bertigny Jean‐Pierre , Doussot Joel , Garreau Robert , Guy Alain , Platzer Nicole
Published: October 2002

The 1H and 13C NMR spectra of a series of 9‐substituted 19‐norsteroids were completely assigned using a series of 2D NMR experiments, which included 1H–1H COSY, NOESY and 1H–13C heteronuclear HETCOR and HMQC. For second‐order spin systems, chemical shifts and coupling constants were obtained by simulation of the experimental spectrum. Criteria were deduced to characterize the stereochemistry of these different compounds (multiplet pattern of H‐8β and variation of chemical shifts). The results allow the easy determination of the configuration at C‐9. Conformational changes resulting from the substitution were studied by NMR and molecular modeling calculations (AM1). Copyright © 2001 John Wiley & Sons, Ltd.
Oxidation of thioanisole by peroxomolybdate ions: direct oxygen transfer from tetraperoxomolybdate ion
Authors: Bunton Clifford A. , Gillitt Nicholas D.
Published: October 2002

Addition of thioanisole (PhSMe) to Na2MoO4 in dilute hydrogen peroxide at pH 9.4 rapidly quenches the absorbance of the tetraperoxo complex, $\hbox{Mo}(\hbox{O}_{2})_{4}^{2-}$, which gradually regenerates as the PhSMe is oxidized to the sulfoxide. This direct oxygen transfer is followed by the decreasing absorbance of $\hbox{Mo}(\hbox{O}_{2})_{4}^{2-}$ at 452 nm. In dilute H2O2 the $\hbox{Mo}(\hbox{O}_{2})_{4}^{2-}$ becomes a steady‐state intermediate, and kinetics monitored by 1H NMR spectroscopy allow estimation of the second‐order rate constant for oxidation of PhSMe by $\hbox{MoO}(\hbox{O}_{2})_{3}^{2-}$ and rate constants for interconversion of $\hbox{MoO}(\hbox{O}_{2})_{3}^{2-}$ and $\hbox{MoO}(\hbox{O}_{2})_{4}^{2-}$. The steady‐state approximation breaks down at higher [H2O2], and with [H2O2] = 2 M the $\hbox{MoO}(\hbox{O}_{2})_{3}^{2-}$ and $\hbox{Mo}(\hbox{O}_{2})_{4}^{2-}$ are approximately in equilibrium; based on the rate constants of oxidation of PhSMe by $\hbox{MoO}(\hbox{O}_{2})_{3}^{2-}$ and $\hbox{Mo}(\hbox{O}_{2})_{4}^{2-}$ and the related association equilibrium constant, the observed and predicted rate constants for the overall oxidation of PhSMe are similar. Copyright © 2001 John Wiley & Sons, Ltd.
Kinetics and mechanism for oxime formation from methyl pyruvate
Authors: Córdova T. , Peraza A. J. , Calzadilla M. , Malpica A.
Published: October 2002

Rate and equilibrium constants for methyl pyruvate oxime formation were determined as a function of pH over the range 0–7 in aqueous solution at 30 °C and ionic strength 0.5 by spectrophotometric methods. The reaction occurs with rate‐determining carbinolamine dehydration over the entire range of pH investigated. Carbinolamine dehydration is not susceptible to detectable general acid–base catalysis by a carboxylic acid buffer or hydroxylamine/hydroxylammonium ion buffer. Specific acid catalysis for carbinolamine formation is dominant at­pH values below 5. Above that value, a pH‐independent, water‐catalyzed reaction becomes apparent. The­pH‐independent carbinolamine dehydration is unusually important with this substrate. Copyright © 2001 John Wiley & Sons, Ltd.
Hydrogen‐bond basicity of solutes in hydroxylic solvents from octanol–water partition coefficients
Authors: Berthelot Michel , Graton Jérôme , Ouvrard Carole , Laurence Christian
Published: October 2002

Hydrogen‐bond acceptor strengths of numerous bases can be extracted from octanol–water partition coefficients after subtraction of a hydrophobic‐cavity term proportional to the molecular volume of the solutes. A stepwise correlation analysis is carried out to compare these basicities in hydroxylic solvents with the pK
x(HB) hydrogen‐bonding basicity scale determined for the 1:1 association of 4‐fluorophenol in carbon tetrachloride. Within a family of bases, hydrogen‐bond acceptor ability in hydroxylic solvents is found to be predicted by the pK
x(HB) scale and the overall basicity of bifunctional and trifunctional solutes is precisely calculated by an exact summation ∑pK
x(HB) of the strengths of the individual basic sites. Plots of octanol–water partition coefficients against ∑pK
x(HB) present classical family‐dependent relationships separating the amines, pyridines and ethers from the other bases. This separation can be accounted for by a simple multiplicative term λ restoring the additivity of the basicity strengths. Careful dissection of the overall basicities of bifunctional compounds into their individual components reveals the considerable levelling effect of the hydroxylic solvents on the relative strengths of the different basic groups present in the same solute. A two‐parameter equation involving the molecular volume and the corrected summation for all basic sites ∑λpK
x(HB) is proposed to predict partitioning between octanol and water. Significant deviations from the equation are found when one of the basic centres of the solute is hindered by bulky substituents. Copyright © 2002 John Wiley & Sons, Ltd.
Kinetic study of hydrolysis of benzoates. Part XXIII—Influence of the substituent and temperature on the kinetics of the alkaline hydrolysis of alkyl benzoates in aqueous 2.25 MBu4NBr and 80% DMSO
Authors: Nummert Vilve , Piirsalu Mare
Published: October 2002

The second‐order rate constantsk2(M−1s−1) for the alkaline hydrolysis of substituted alkyl benzoates, C6H5CO(O)R (R = CH3, CH2Cl, CH2CN, CH2C≡CH, CH2C6H5, CH2CH2Cl, CH2CH2OCH3), were measured in aqueous 2.25 Mn‐Bu4NBr and in 80% (v/v) DMSO solution at several temperatures. The logkvalues were analyzed using the equation logk = logk0 + ρσ + δEsB. TheEsBscale has been proposed for the steric effect of alkyl substituents in the alkyl part of esters:EsB = (logkR − logkCH3), wherekis the rate constant for the acidic hydrolysis of substituted alkyl benzoates or acetates in water. As polar substituent parameters, both Taft σ* and σIconstants were used. The dual parameter treatments of the logkvalues with σ andEsBconstants gave excellent correlations (R = 0.997). For 2.25 Mn‐Bu4NBr, 80% (v/v) DMSO and pure water at 25 °C, calculated susceptibilities to the inductive effect of alkyl substituents ρ* were found to be 2.07, 2.21 and 1.64, respectively. The corresponding ρIvalues were 4.64, 4.94 and 3.64. The dependence of ρIon solvent and temperature in the alkaline hydrolysis of substituted alkyl benzoates was similar to that observed earlier formeta‐ andpara‐substituents in the alkaline hydrolysis of substituted phenyl benzoates and tosylates. The substituent dependence of the activation energy,E, was found to be completely caused by the polar effect. Susceptibility to steric effect in the alkaline hydrolysis of alkyl benzoates (δ ≈ 1) appeared to be independent of the solvent and temperature. Copyright © 2002 John Wiley & Sons, Ltd.
Biologically active polymers. V. Synthesis and antimicrobial activity of modified poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) derivatives with quaternary ammonium and phosphonium salts
Authors: Kenawy El‐Refaie , Abdel‐Hay Fouad I. , El‐Shanshoury Abd El‐Raheem R. , El‐Newehy Mohamed H.
Published: October 2002

Antimicrobial copolymers bearing quaternary ammonium and phosphonium salts based on a copolymer of glycidyl methacrylate and 2‐hydroxyethyl methacrylate were synthesized. Poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium salts. The antimicrobial activity of the obtained copolymers was studied against gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram‐positive bacteria (Bacillus subtilus and B. cereus), and the fungus Trichophyton rubrum by the cut‐plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram‐negative and gram‐positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 mm after 24 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2384–2393, 2002
Synthesis, optical, and electrochemical properties of novel copolymers on the basis of benzothiadiazole and electron‐rich arene units
Authors: Jayakannan M. , Van Hal Paul A. , Janssen René A. J.
Published: October 2002

Novel alternating conjugated copolymers (P1–P6) consisting of an electron‐deficient benzothiadiazole and a variety of electron‐rich thiophene‐arene‐thiophene units were synthesized by palladium‐catalyzed polycondensations (Stille and Suzuki reactions), aiming at processable materials with a reduced optical band gap. The structures of P1–P6 were confirmed by 1H NMR and 13C NMR, and their molecular weights were determined by size exclusion chromatography. In the Suzuki polycondensation, the role of the catalyst [Pd(PPh3)4 and Pd(OAc)2] on the resulting molecular weight was investigated. Pd(OAc)2 enhances the molecular weight of the polymers for both thiophene and phenylene bis‐boronic esters as compared with Pd(PPh3)4. The optical properties of the polymers were examined in solution and the solid state. The polymers with n‐octyl substituents (P1, P4, P5, and P6) on the thiophene rings possessed less‐planar structures as a result of torsional steric hindrance, and their absorption spectra appeared blueshifted as compared with their unsubstituted analogues (P2 and P3). The electrochemical properties of the polymers were studied using cyclic voltammetry. Although the alkyl substitution affects the oxidation potential, only marginal differences in the reduction potentials were observed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2360–2372, 2002
Structure development of polyamide‐66 fibers during drawing and their microstructure characterization
Authors: Vasanthan Nadarajah , Ruetsch Sigrid B. , Salem David R.
Published: October 2002

Structure development during drawing was studied for three sets of polyamide‐66 (PA66) fibers with density, optical microscopy, wide‐angle X‐ray diffraction, and Fourier transform infrared spectroscopy. The crystallinity, estimated by density measurements, remained virtually constant with increasing draw ratios, indicating that stress‐induced crystallization did not occur for the PA66 fibers drawn at room temperature, but there was a rapid transformation from a hedrite morphology to a fibrillar one. The absence of stress‐induced crystallization differed from the behavior of polyamide‐6, and this was attributed to the stronger hydrogen bonding between polyamide chains and the higher glass‐transition temperature of PA66. Polarized infrared spectroscopy was used to measure the transition‐moment angles of the vibrations at 936 and 906 cm−1, which were found to be 48 and 60°, respectively. The crystalline orientation was estimated from the band at 936 cm−1, and the increase with an increasing draw ratio was in close quantitative agreement with X‐ray diffraction data; this showed that infrared spectroscopy could be used reliably to measure the crystalline orientation of PA66 fibers. Because we were unable to obtain the transition‐moment angle of the amorphous bands, the amorphous orientation was obtained with Stein's equation. The amorphous orientation developed more slowly than the crystalline orientation, which is typical behavior for flexible‐chain polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1940–1948, 2002
Borehole deformation measurements and internal structure of some rock glaciers in Switzerland
Authors: Arenson Lukas , Hoelzle Martin , Springman Sarah
Published: October 2002

In order to understand the mechanical processes that influence the deformation patterns of active rock glaciers, information about local horizontal and vertical deformations as well as knowledge of the internal structure and the temperature distribution is necessary. Results from borehole deformation measurements of three sites in the Swiss Alps show that despite different internal structures, similar phenomena can be observed. In contrast to temperate glaciers, permafrost within rock glaciers has distinct shear zones where horizontal and vertical differential movements are concentrated. In addition, a reduction in volume can be caused by compressive flow due to the presence of air voids within the permafrost. The flow velocity depends on the temperature, the surface and bedrock slopes of the rock glacier, and the composition of the ice‐rich frozen ground. Within degrading permafrost, the ice content decreases, the creep velocity increases and the shear zone rises towards the surface, where seasonal temperature changes and the presence of liquid water might also influence deformation. Copyright © 2002 John Wiley & Sons, Ltd.
Down‐regulation of (IIIb) and (IIIc) isoforms of fibroblast growth factor receptor 2 (FGFR2) is associated with malignant progression in human prostate
Authors: Naimi Benyoussef , Latil Alain , Fournier Georges , Mangin Philippe , Cussenot Olivier , Berthon Philippe
Published: October 2002

BACKGROUND

Fibroblast growth factors (FGFs) and their receptors (FGFRs) have a critical function in the cellular stroma/epithelium interaction for the development and homeostasis of human prostate. Imbalance in expression of these factors is associated with malignancy in several cancers.

METHODS

To quantify the expression of fibroblast growth factor receptor isoforms FGFR2(IIIb), FGFR2(IIIc), FGFR1(IIIc), and fibroblast growth factors FGF2 and FGF7 in normal and tumoral human prostate tissues, and human prostatic epithelial cell lines, we used quantitative real‐time polymerase chain reaction.

RESULTS

The expression of FGFR2(IIIb) mRNA is down‐regulated in 60% of the tumors studied (P < 0.0001). Furthermore, FGFR2(IIIb) is significantly reduced in androgen‐independent tumors (AI) compared with androgen‐responsive tumors (AD) (P = 0.02). A significant reduction in FGFR2(IIIc) expression is also observed in 80% of tumors (P = 0.001). However, unlike FGFR2(IIIb), the down‐regulation of FGFR2(IIIc) is not related to the androgen‐independent status (P = 0.09). On the other hand, neither FGFR1(IIIc) nor FGF2 and FGF7 have shown any significant variation in expression between normal and cancerous specimens.

CONCLUSIONS

These findings propose that decreased expression of not only FGFR2(IIIb) but also FGFR2(IIIc) isoforms may be a critical step in prostate cancer progression and furthermore suggest that FGFR2(IIIb) expression could be used as a marker for prostate cancer evolution from androgen‐dependent to androgen‐independent status. Prostate 52:245–252, 2002. © 2002 Wiley‐Liss, Inc.
Assessing equilibration and convergence in biomolecular simulations
Authors: Smith Lorna J. , Daura Xavier , van Gunsteren Wilfred F.
Published: October 2002

If molecular dynamics simulations are used to characterize the folding of peptides or proteins, a wide range of conformational states needs to be sampled. This study reports an analysis of peptide simulations to identify the best methods for assessing equilibration and sampling in these systems where there is significant conformational disorder. Four trajectories of a β peptide in methanol and four trajectories of an α peptide in water, each of 5 ns in length, have been studied. Comparisons have also been made with two 50‐ns trajectories of the β peptide in methanol. The convergence rates of quantities that probe both the extent of conformational sampling and the local dynamical properties have been characterized. These include the numbers of hydrogen bonds populated, clusters identified, and main chain torsion angle transitions in the trajectories. The relative equilibrium rates of different quantities are found to vary significantly between the two systems studied reflecting both the differences in peptide primary structure and the different solvents used. A cluster analysis of the simulation trajectories is identified as a very effective method for judging the convergence of the simulations. This is particularly the case if the analysis includes a comparison of multiple trajectories calculated for the same system from different starting structures. Proteins 2002;48:487–496. © 2002 Wiley‐Liss, Inc.
Mapping pathways of allosteric communication in GroEL by analysis of correlated mutations
Authors: Kass Itamar , Horovitz Amnon
Published: October 2002

An interesting example of an allosteric protein is the chaperonin GroEL. It undergoes adenosine 5′‐triphosphate‐induced conformational changes that are reflected in binding of adenosine 5′‐triphosphate with positive cooperativity within rings and negative cooperativity between rings. Herein, correlated mutations in chaperonins are analyzed to unravel routes of allosteric communication in GroEL and in its complex with its co‐chaperonin GroES. It is shown that analysis of correlated mutations in the chaperonin family can provide information about pathways of allosteric communication within GroEL and between GroEL and GroES. The results are discussed in the context of available structural, genetic, and biochemical data concerning short‐ and long‐range interactions in the GroE system. Proteins 2002;48:611–617. © 2002 Wiley‐Liss, Inc.
Progress toward virtual screening for drug side effects
Authors: Rockey William M. , Elcock Adrian H.
Published: October 2002

The development and application of a computational protocol for conducting virtual screens of drug side interactions is described. A conventional drug‐docking algorithm (AutoDock) is used to conduct two separate studies. First, a series of docking simulations is performed by using guanosine diphosphate and adenosine diphosphate as prototype drugs with the goal of successfully differentiating known receptors from a large number of bait receptors. Using the electrostatic energy of the purine ring as a basis for discrimination allows the correct identification of receptors in blind studies with 100% specificity and 94% sensitivity. In a second study, similar methodology is used to investigate the binding of clinically relevant inhibitors (Gleevec, purvalanol A, and hymenialdisine) to a variety of protein kinase targets. Overall, excellent agreement between experimental and predicted preferences for kinase targets is obtained. An important conclusion from the latter study is that homology‐modeled structures of putative receptors may reasonably be used as targets for docking when directly solved crystal structures are not available. The prospects for routine application of the methodology as a means of identifying potential side interactions of candidate drugs are discussed. Proteins 2002;48:664–671. © 2002 Wiley‐Liss, Inc.
Effects of formulation on the run‐off of imidacloprid from turf
Authors: Armbrust Kevin L , Peeler Harold B
Published: October 2002

Imidacloprid is a pesticide often used to control insect pests on residential lawns and golf courses. To investigate its potential to be transported into non‐target aquatic systems by rainfall events, imidacloprid was applied as 5.0 g kg−1 GR and 750 g kg−1 WP to 12 plots planted with bermuda grass set on a 5% slope. The dimethylamine salt of the herbicide 2,4‐D was applied simultaneously to the plots in order to normalize the results to prior trials conducted with other pesticides. At a rate of 2.5 cm h−1, 5‐cm rainfall events were simulated at 24 and 48 h after application and 2.5‐cm events were simulated at 96 and 192 h. After each event water was collected from each plot and analyzed by HPLC for residual insecticide or herbicide. Approximately 1.4% of the insecticide formulated as WP and 1.9% of that formulated as GR was lost from the plots after four run‐off events. Of the total mass lost, 64% and 30% respectively occurred in the first and second run‐off events for the WP formulation versus 75% and 20% for the GR formulation. These values compare with a total mass export of 2.6% for 2,4‐D, of which 95% and 4% of the loss occurred respectively in the first and second run‐off events. The maximum concentration of imidacloprid detected in run‐off water was 0.49 mg litre−1 and occurred during the first run‐off event.

© 2002 Society of Chemical Industry
Antioxidant activity of the methanol fraction of Pluchea indica root extract
Authors: Sen T. , Dhara A. K. , Bhattacharjee S. , Pal S. , Nag Chaudhuri A. K.
Published: October 2002

Studies were carried out to evaluate the influence of the methanol fraction of Pluchea indica Less root extract (PIRE), the dual inhibitors (BW 755C and phenidone) and vitamin on both in vivo and in vitro free radical‐scavenging activities, CCl4‐induced lipid peroxidation and the metabolism of arachidonic acid by lipoxygenase. PIRE produced significant antiinflammatory activity against glucose oxidase‐induced paw oedema (in vivo), inhibited hydroxyl radical and superoxide generation, lysis of erythrocytes induced by hydrogen peroxide, CCl4‐induced lipid peroxidation and also dioxygenase activity of lipoxygenase (both in the presence and absence of hydrogen peroxide). Significantly higher free radical‐scavenging activity was observed with BW 755C and phenidone compared with PIRE. However, both BW 755C and phenidone stimulated hydroxyl radical generation compared with the observed inhibitory effects of PIRE and vitamin E. Copyright © 2002 John Wiley & Sons, Ltd.
Fighting fire with fire: using randomized gossip to combat stochastic scalability limits
Authors: Gupta Indranil , Birman Kenneth P. , van Renesse Robbert
Published: October 2002

The mechanisms used to improve the reliability of distributed systems often limit performance and scalability. Focusing on one widely‐used definition of reliability, we explore the origins of this phenomenon and conclude that it reflects a tradeoff arising deep within the typical protocol stack. Specifically, we suggest that protocol designs often disregard the high cost of infrequent events. When a distributed system is scaled, both the frequency and the overall cost of such events often grow with the size of the system. This triggers an O($n^{2}$) phenomenon, which becomes visible above some threshold sizes. Our findings suggest that it would be more effective to construct large‐scale reliable systems where, unlike traditional protocol stacks, lower layers use randomized mechanisms, with probabilistic guarantees, to overcome low‐probability events. Reliability and other end‐to‐end properties are introduced closer to the application. We employ a back‐of‐the‐envelope analysis to quantify this phenomenon for a class of strongly reliable multicast problems. We construct a non‐traditional stack, as described above, that implements virtually synchronous multicast. Experimental results reveal that virtual synchrony over a non‐traditional, probabilistic stack helps break through the scalability barrier faced by traditional implementations of the protocol. Copyright © 2002 John Wiley & Sons, Ltd.
Protection of keys against modification attack
Authors: Fung Wai W. , Golin Mordecai J. , Gray James W.
Published: October 2002

In 1997, Anderson and Kuhn described an attack against tamper‐resistant devices wherein a secret key stored in EEPROM is compromised using a simple and low‐cost attack. The attack consists of setting bits in the EEPROM using low‐cost probes and observing the effect on the output of the device. These attacks are extremely general, as they apply to virtually any cryptosystem. The objective of the present work is to explore cryptographic techniques with the goal of raising the cost (in terms of time and money) of carrying out the EEPROM modification attack by class I attackers, at least to a point where it is as prohibitive as the cost of purchasing more expensive equipment. We propose the m‐permutation protection scheme in which the key will be encoded in a special way and burned into the EEPROM of the device. To attack the scheme, the attacker needs to be able to solve for K in the equation K $= \bigoplus^{m}_{i=1}$ P$_i$, in which P$_i$'s are unknown. It is observed that the $m$‐permutation protection scheme does not distribute the key K uniformly. However, analysis shows that $m=3$ or $m=5$ are already good enough practically to provide strong security if the encoding is done properly, and that $m > 5$ may not give significant improvement to the security of the scheme. Copyright © 2002 John Wiley & Sons, Ltd.
Testing for software vulnerability using environment perturbation
Authors: Du Wenliang , Mathur Aditya P.
Published: October 2002

We describe a methodology for testing a software system for possible security flaws. Based on the observation that most security flaws are caused by the program's inappropriate interactions with the environment, and are triggered by a user's malicious perturbation on the environment (which we call an environment fault), we view the security testing problem as the problem of testing for the fault‐tolerance properties of a software system. We consider each environment perturbation as a fault and the resulting security compromise a failure in the toleration of such faults. Our approach is based on the well‐known technique of fault injection. Environment faults are injected into the system under test and system behavior observed. The failure to tolerate faults is an indicator of a potential security flaw in the system. An Environment‐Application Interaction (EAI) fault model is proposed which guides us to decide what faults to inject. Based on EAI, we have developed a security testing methodology, and applied it to several applications. We have successfully identified a number of vulnerabilities including vulnerabilities in the Windows NT operating system. Copyright © 2002 John Wiley & Sons, Ltd.
Theoretical investigation of the Ziegler–Natta catalysis in heterogeneous conditions
Authors: Markovits A. , Minot C.
Published: October 2002

We present ab initio calculations on the Ziegler–Natta catalysis in heterogeneous conditions. Both cluster and periodic models with different basis sets have been used to explain the chemical reactivity of the various species that are involved. In heterogeneous conditions, several parameters contribute to the catalysis: the oxidation state of the titanium atom, the structure of the titanium site, the interaction with the support, MgCl2, and the cocatalyst, AlR3. This article yields to a synthetic view of the catalytic activity. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002
Classification and stabilizability analysis of bimodal piecewise affine systems
Authors: Imura Jun‐ichi
Published: October 2002

This paper presents a classification of bimodal piecewise affine systems from the viewpoint of well‐posedness. First, we address the feedback well‐posedness problem of a general class of bimodal piecewise affine systems, which is the problem of feedback equivalence to a well‐posed system. Next, based on this result, we classify all feedback well‐posed systems into four classes to address the control problem of piecewise affine systems in a systematic way. As its application, the stabilizability problem with well‐posedness is discussed for each class, and several remarks on stabilizability are given. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis of a static anti‐windup compensator via linear matrix inequalities
Authors: Saeki Masami , Wada Nobutaka
Published: October 2002

In this paper, we propose a design method of a static anti‐windup compensator that guarantees robust stability subject to input saturation and suppresses the degradation of robust performance during the saturation period. In previous studies, this problem has been considered to be equivalent to a static output feedback design problem, which is essentially a non‐convex problem. We show that this problem can be reduced to an equivalent convex problem by using an appropriate sector transformation. The numerical solution can be obtained efficiently by solving linear matrix inequalities (LMIs). Further, a constant scaling matrix is introduced to the condition in order to reduce the conservativeness. In this case, since the design problem is no more LMIs, an algorithm for solving the problem by LMI iterations is presented. Four numerical examples are given to illustrate the effectiveness of the proposed method. Copyright © 2002 John Wiley & Sons, Ltd.
Effects of flow regulation and sediment flushing on instream habitat and benthic invertebrates in a New Zealand river influenced by a volcanic eruption
Authors: Collier Kevin J.
Published: October 2002

I sampled five sites above and below a dam in the central North Island of New Zealand on five to six occasions to examine the effects on benthic substrates, periphyton and invertebrate communities of (i) degree of flow regulation and (ii) flushing of sediment stored behind a dam. A series of volcanic eruptions during the course of this study provided the opportunity to investigate the effects of a period of high sediment delivery on this regulated river. The operation of the dam prior to sluicing of stored sediment appeared to have little impact on substrate size distribution or fine suspendable sediment levels. Periphyton biomass was markedly higher below than above the dam when sampling was preceded by a period of stable baseflow, but over all sampling dates biomass and inorganic content of periphyton did not appear to be related to degree of flow regulation. The taxonomic richness, biomass and density of invertebrate communities were lowest directly below, rather than above, the dam on most dates, and the site below the dam differed significantly from some of the downstream sites. However, changes in invertebrate abundance and diversity generally did not follow the expected gradient of flow regulation impacts except for the mayfly Deleatidium. Multiple regression analyses implicated substrate size and the biomass and inorganic content of periphyton as significant predictor variables for invertebrate density, biomass and taxonomic richness on sampling dates not influenced by recent sediment flushes, whereas degree of flow regulation was a significant predictor for densities of the dominant chironomid Cricotopus. The volcanic eruption led to deposition of fine silt that had passed through the dam with the residual flow and coarser sediments released during subsequent dam flushes. Flushing of stored sediment during large floods increased levels of sand and gravel directly below the dam and upstream of a large island in the middle reaches of the river, and also appeared to increase scouring of periphyton and associated invertebrates downstream. Overall, invertebrate communities in the study reach appeared to be structured more by periphyton accrual patterns, changes in substrate composition, the occurrence of large floods and natural longitudinal gradients than degree of flow regulation. These findings suggest that site‐specific and large‐scale factors can obscure generalized reach‐scale patterns expected along regulated rivers. Copyright © 2002 John Wiley & Sons, Ltd.
The phase transition in random horn satisfiability and its algorithmic implications
Authors: Istrate Gabriel
Published: October 2002

Letc> 0 be a constant, and Φ be a random Horn formula withnvariables andm=c· 2nclauses, chosen uniformly at random (with repetition) from the set of all nonempty Horn clauses in the given variables. By analyzing PUR, a natural implementation of positive unit resolution, we show that limn→∞Pr(Φ is satisfiable) = 1 −F(e−c), whereF(x) = (1 −x)(1 −x2)(1 −x4)(1 −x8) …. Our method also yields as a byproduct an average‐case analysis of this algorithm. Published 2002 Wiley Periodicals, Inc. Random Struct. Alg., 20: 483–506, 2002
3D reconstruction from uncalibrated‐camera optical flow and its reliability evaluation
Authors: Kanatani Kenichi , Ohta Naoya , Shimizu Yoshiyuki
Published: October 2002

We present a scheme for reconstructing a 3D structure from optical flow observed by a camera with an unknown focal length in a statistically optimal way as well as evaluating the reliability of the computed shape. First, the flow fundamental matrices are optimally computed from the observed flow. They are then decomposed into the focal length, its rate of change, and the motion parameters. Next, the flow is optimally corrected so that it satisfies the epipolar equation exactly. Finally, the 3D positions are computed, and their covariance matrices are evaluated. By simulations and real‐image experiments, we test the performance of our system and observe how the normalization (gauge) for removing indeterminacy affects the description of uncertainty. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(9): 1–10, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10133
Network meta‐analysis for indirect treatment comparisons
Authors: Lumley Thomas
Published: October 2002

I present methods for assessing the relative effectiveness of two treatments when they have not been compared directly in a randomized trial but have each been compared to other treatments. These network meta‐analysis techniques allow estimation of both heterogeneity in the effect of any given treatment and inconsistency (‘incoherence’) in the evidence from different pairs of treatments. A simple estimation procedure using linear mixed models is given and used in a meta‐analysis of treatments for acute myocardial infarction. Copyright © 2002 John Wiley & Sons, Ltd.
Flexible parametric proportional‐hazards and proportional‐odds models for censored survival data, with application to prognostic modelling and estimation of treatment effects
Authors: Royston Patrick , Parmar Mahesh K. B.
Published: October 2002

Modelling of censored survival data is almost always done by Cox proportional‐hazards regression. However, use of parametric models for such data may have some advantages. For example, non‐proportional hazards, a potential difficulty with Cox models, may sometimes be handled in a simple way, and visualization of the hazard function is much easier. Extensions of the Weibull and log‐logistic models are proposed in which natural cubic splines are used to smooth the baseline log cumulative hazard and log cumulative odds of failure functions. Further extensions to allow non‐proportional effects of some or all of the covariates are introduced. A hypothesis test of the appropriateness of the scale chosen for covariate effects (such as of treatment) is proposed. The new models are applied to two data sets in cancer. The results throw interesting light on the behaviour of both the hazard function and the hazard ratio over time. The tools described here may be a step towards providing greater insight into the natural history of the disease and into possible underlying causes of clinical events. We illustrate these aspects by using the two examples in cancer. Copyright © 2002 John Wiley & Sons, Ltd.
Penalized likelihood approach to estimate a smooth mean curve on longitudinal data
Authors: Jacqmin‐Gadda Hélène , Joly Pierre , Commenges Daniel , Binquet Christine , Chêne Geneviève
Published: October 2002

This paper aims to propose a penalized likelihood approach to estimate a smooth mean curve for the evolution with time of a Gaussian variable taking into account the correlation structure of longitudinal data. The model is an extension of the mixed effects linear model including an unspecified function of timef(t). The estimatorf̂(t) is defined as the solution of the maximization of the penalized likelihood and is approximated on a basis of cubic M‐spline with a reduced number of knots. We present modifications of four criteria (cross‐validation, generalized cross‐validation, T of Rice, Akaike's criterion) to estimate the smoothing parameter when data are correlated; these four criteria gave very similar results in the simulation study. The simulation study showed also the superiority of the Bayesian confidence bands of the mean curve over the frequentist ones. We develop empirical Bayes estimates of subject‐specific deviations. This approach was applied to study the progression of CD4+ lymphocyte counts in a cohort of HIV patients treated with protease inhibitors. Copyright © 2002 John Wiley & Sons, Ltd.
HARTEX—a safe real‐time kernel for distributed computer control systems
Authors: Angelov C. K. , Ivanov I. E. , Burns A.
Published: October 2002

A hard real‐time kernel is presented for distributed computer control systems (DCCS), highlighting a number of novel features, such as integrated scheduling of hard and soft real‐time tasks as well as tasks and resources; high‐performance time management supporting safe DCCS operation in a hard real‐time environment; synchronization and communication featuring event notification via vector semaphores and transparent communication through implicit (content‐oriented) message addressing. Conventional queues have been substituted by Boolean vectors and vector processing techniques throughout the kernel, resulting in efficient and highly deterministic behaviour, which is characterized by very low overhead and constant execution time of kernel operations, independent of the number of tasks involved. Copyright © 2001 John Wiley & Sons, Ltd.
A security scheme for Aglets
Authors: Ono Kouichi , Tai Hideki
Published: October 2002

Aglets, a framework and runtime platform for mobile agents developed by the IBM Tokyo Research Laboratory, is an advanced system of mobile agents written in Java, and is already used in some commercial applications. Using mobile agent technologies provides potential benefits to applications, but they also pose security threats to those applications. These threats not only come as malicious agents, but also in the form of malicious hosts. In this paper we introduce security features against these threats. Access control and message protection can prevent attacks by malicious agents. Server authentication allows agents to avoid movement to malicious hosts and blocks suspicious agents coming from malicious hosts. Copyright © 2002 John Wiley & Sons, Ltd.
Eternal—a component‐based framework for transparent fault‐tolerant CORBA
Authors: Narasimhan P. , Moser L. E. , Melliar‐Smith P. M.
Published: October 2002

Enterprises are increasingly involved in worldwide round‐the‐clock e‐commerce and e‐business, which requires them to be operational 24 hours per day, 7 days per week. With outages leading to loss of revenue, reputation and customers, fault tolerance becomes increasingly important. By mixing the fault tolerance logic into the application logic, existing fault tolerance practices render applications more complex, more prone to errors, and more difficult to maintain and build. The Eternal system is a component‐based middleware framework that provides transparent fault tolerance for enterprise applications, and that ensures continuous$24\times7$operation without requiring special skills of the application programmers. The Eternal system implements the new Fault‐Tolerant CORBA standard. Copyright © 2002 John Wiley & Sons, Ltd.
Spatial and temporal profile of haloperidol‐induced immediate‐early gene expression and phosphoCREB binding in the dorsal and ventral striatum of amphetamine‐sensitized rats
Authors: Hsieh Huei‐Ching , Li Hui‐Yun , Lin Ming‐Yu , Chiou Ya‐Fen , Lin Shao‐Yun , Wong Chung‐Hung , Chen Jin‐Chung
Published: October 2002

To determine if D2 dopamine receptor‐mediated nuclear signaling is altered during the development of amphetamine sensitization, we examined the expression of immediate‐early gene (IEG) products, Fos, Jun, and Fos‐related antigen (FRA), in both controls and amphetamine‐sensitized rats after a challenge with the D2 antagonist haloperidol. When chronic saline‐ or amphetamine (5 mg/kg, i.p. for 14 days)‐treated rats were challenged with 2 mg/kg haloperidol at withdrawal day 3 (w3), more 35‐kDa FRA was induced in the ventral striatum of the control group than in the amphetamine‐treated rats. In contrast, more Jun and 35‐kDa FRA were expressed in the ventral striatum of the amphetamine‐treated group than in the controls when haloperidol was given at w10. Topographical analyses indicate that the decrease in FRA immunoreactive neuronal density in amphetamine‐treated rats at w3 were located in the dorsolateral caudate/putamen and the nucleus accumbens shell and core subregions. Conversely, the increase in Jun‐immunoreactive neurons in amphetamine‐treated rats at w10 was observed in the dorsolateral caudate/putamen; in the case of the FRAs, the increase was observed in the nucleus accumbens shell. In addition, the time‐dependent profile of IEG expression paralleled the activation of an upstream regulator, cAMP‐response element binding protein, in the ventral striatum after haloperidol treatment. These neurochemical changes may be associated with behavioral plasticity, since amphetamine‐treated rats displayed a lower amount of locomotor activity when exposed to a novel environment at w3, but had recovered at w10. Overall, the current study reveals that there is a distinct temporal and spatial profile of haloperidol‐induced IEG expression and/or CREB phosphorylation in amphetamine‐treated rats, suggesting that there is a critical transition between the early and late withdrawal periods. Synapse 45:230–244, 2002. © 2002 Wiley‐Liss, Inc.