bluuebunny/crossref_metadata_2025 huggingface dataset:
Ring‐chain interactions in solutions of cyclic and linear poly(methylene) ester oligomers in p‐dioxan and chloroform
Authors: Xu R. , Leonard J. , Bui V. T.
Published: October 2002

The thermodynamic behavior of ternary solutions containing one cyclic (CYC10 and CYC20) and one linear (LIN10 and LIN20) poly(methylene) ester oligomer, respectively, in p‐dioxan and chloroform were investigated through vapor‐pressure measurements. Experiments were carried out at 25, 30, 35, and 40 °C. The ring‐chain interaction parameters χ″ were evaluated using the Leonard's equation for a ternary polymer solution containing one ring polymer. Results indicated that the values of χ″ are concentration and solvent dependent, and they vary with molecular size and slightly with temperature. All χ″ values were positive for both CYC10/LIN10 and CYC20/LIN20 blends, with the higher values for the former system, indicating that both ring‐chain oligomer blends are nearly immiscible, and the difference between cyclic and linear oligomers decreases as molecular size increases. The positive χ″ agrees with differential scanning calorimetric measurements performed on ring‐chain oligomer blends that show two distinct endotherms for the blends. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1425–1433, 2002
Effect of inert diluent segment on the miscibility behavior of poly(vinylphenol) with poly(acetoxystyrene) blends
Authors: Kuo Shiao‐Wei , Chang Feng‐Chih
Published: October 2002

Polymer blends of poly(vinylphenol) (PVPh) and poly(styrene‐co‐vinylphenol) with poly(p‐acetoxystyrene) (PAS) were prepared by solution casting from tetrahydrofuran solution. The thermal properties and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy. Although hydrogen bonding existed between the PVPh and PAS segments, the experimental results indicated that PVPh is immiscible with PAS as shown by the existence of two glass‐transition temperatures over the entire composition range by DSC. This phenomenon is attributed to the strong self‐association of PVPh, intramolecular screening, and functional group accessibility effects of the PVPh/PAS blend system. However, the incorporation of an inert diluent moiety such as styrene into the PVPh chain renders the modified polymer to be miscible with PAS. Copolymers containing between 16 and 51 mol % vinylphenol were fully miscible with PAS according to DSC studies. These observed results were caused by the reduction of the strong self‐association of PVPh and the increase of the interassociation between PVPh and PAS segments with the incorporation of styrene on the PVPh chain. According to the Painter‐Coleman association model, the interassociation equilibrium constant of PVPh/PAS blends was determined by a model compound and polymer blend. Good correlation between these two methods was obtained after considering the intramolecular screening and functional group accessibility effect in the polymer blend. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1661–1672, 2002
Transient and athermal effects in the crystallization of polymers. I. Isothermal crystallization
Authors: Sajkiewicz Paweł
Published: October 2002

The isothermal crystallization of poly(propylene) and poly(ethylene terephthalate) was investigated with differential scanning calorimetry and optical microscopy. It was found that the induction time depends on the cooling rate to a constant temperature. The isothermal crystallization of the investigated polymers is a complex process and cannot be adequately described by the simple Avrami equation with time‐independent parameters. The results indicate that crystallization is composed of several nucleation mechanisms. The homogeneous nucleation occurring from thermal fluctuations is preceded by the nucleation on not completely melted crystalline residues that can become stable by an athermal mechanism as well as nucleation on heterogeneities. The nucleation rate depends on time, with the maximum shortly after the start of crystallization attributed to nucleation on crystalline residues (possible athermal nucleation) and on heterogeneities. However, the spherulitic growth rate and the exponentndo not change with the time of crystallization. The time dependence of the crystallization rate corresponds to the changes in the nucleation rate with time. The steady‐state crystallization rate in thermal nucleation is lower than the rate determined in a classical way from the half‐time of crystallization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1835–1849, 2002
Thermal lensing in poly(vinyl alcohol)/polyaniline blends
Authors: Pilla V. , Catunda T. , Balogh D. T. , Faria R. M. , Zilio S. C.
Published: October 2002

Nonlinear optical properties of poly(vinyl alcohol) (PVA)/polyaniline (PAni) blends were measured with the single‐beam Z‐scan technique with Fourier analysis. The results obtained with continuous wave (cw) excitation indicated that the self‐phase modulation had a thermal origin. Besides the Z‐scan technique, we also employed the time‐resolved mode‐mismatched thermal lens (TL) technique to obtain the temperature coefficient of the optical path length, ds/dT, and the thermal diffusivity coefficient, D, for the specific concentrations used in our blends. ds/dT varied between −0.8 and −1.0 × 10−4 K−1, whereas the thermal diffusivity varied between 1.0 and 1.3 × 10−3 cm2/s. The TL technique was further used to study the aging of the blends as they were heated to 90 °C. Unlike the electrical conductivity of PAni films, which presented a strong dependence on the doping level, the thermooptic properties presented only a slight variation with doping. This feature indicated that the PVA/glutaraldehyde network made the main contribution to the thermooptic properties (D and ds/dT) in the PAni blends. Similarly, dimethyl sulfoxide as a solvent determined the thermooptic properties of PAni solutions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1949–1956, 2002
Crystallization mechanism of regioregular poly(3‐alkyl thiophene)s
Authors: Malik Sudip , Nandi Arun K.
Published: October 2002

The crystallization properties of three regioregular poly(3‐alkyl thiophene)s (P3ATs) are studied: poly(3‐hexyl thiophene) (P3HT), poly(3‐octyl thiophene) (P3OT), and poly(3‐dodecyl thiophene) (P3DDT). The morphology of the isothermally crystallized samples is a whisker type. The values of the enthalpy of fusion of ideal crystals (ΔH), determined from the melting point depression in the polymer–diluent system, are 99, 73.6, and 52 J/g for P3HT, P3OT, and P3DDT, respectively. The values of the equilibrium melting point (T), determined from the Hoffman–Weeks extrapolation procedure, are 300, 230, and 180 °C for P3HT, P3OT, and P3DDT, respectively. From the linear extrapolation of the P3AT data, the T and ΔH values of unsubstituted polythiophene are predicted to be 400 °C and 139 J/g, respectively. The crystallization kinetics of these polymers are studied with differential scanning calorimetry, and the Avrami exponents vary between 0.6 and 1.4, indicating one‐dimensional heterogeneous nucleation with linear growth. As the P3AT whiskers are produced from the chain‐folding process, the Lauritzen–Hoffman growth rate theory is applied to analyze the temperature coefficient of the crystallization rate data. Graphical plots indicate a transition from regime I to regime II during isothermal crystallization for all the P3ATs studied. The fold surface energy and the work of chain folding calculated from the slopes of the graphical plots decrease with an increase in the number of carbon atoms of the side chain. The primary crystallization process of the side‐chain crystallization is very fast and is attributed to the zipping effect of the main‐chain crystals. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2073–2085, 2002
A POMS short form for cancer patients: psychometric and structural evaluation
Authors: Baker Frank , Denniston Maxine , Zabora James , Polland Adrienne , Dudley William N.
Published: October 2002

The internal consistency, validity, and factor structure of the Shacham shortened version (37 items) of the 65‐item profile of mood states (POMS) were examined with a sample of 428 cancer patients who were awaiting bone marrow transplantation. Cronbach's alphas ranging from 0.78 to 0.91 were obtained for each of the six subscales of the POMS‐short form (POMS‐SF) and for the total 37‐item scale. Correlations with the CES‐D, the Self‐Rated Karnofsky, the MOS SF‐20 Physical Functioning, and the Bradburn Positive and Negative Affect Scales provided evidence of the convergent and discriminant validity of the POMS‐SF. Results of a confirmatory factor analysis were supportive of the 6‐factor interpretation of the POMS items in the 37‐item version of the POMS. Copyright © 2002 John Wiley & Sons, Ltd.
Geomorphic processes at a snowpatch hollow on Gassan volcano, northern Japan
Authors: Kariya Yoshihiko
Published: October 2002

Present‐day geomorphic processes, in a snowpatch hollow on an andesitic volcano (Gassan, 1984 m ASL; 38° 38′ N, 140° 02′ E) where late‐lying snow survives nearly 10 months every year, have been measured for several years. Although soil temperature data show a concentration of freeze‐thaw activities in autumn, these fluctuations rarely drop to the effective temperature range for frost shattering. Wetting and drying rather than frost action is thought responsible for debris production which ranges from 2.12 to 49.68 g m−2 a−1, equivalent to a rock surface retreat of 0.001 to 0.019 mm a−1. Thawing of seasonal frost and saturation of soils induces frost creep and gelifluction: maximum values of surface velocity and depth of soil movement are 0.9 cm a−1 and 14 cm, respectively. Annually, slope lowering of 0.3 cm occurs in the pro‐nival and sub‐nival wash‐rill zones. In comparison with other snowpatch sites in the world, rates of soil movement and rock surface denudation are considerably lower at the study site, while fluvial action seems important. Copyright © 2002 John Wiley & Sons, Ltd.
The mean annual temperature at the top of permafrost, the TTOP model, and the effect of unfrozen water
Authors: Riseborough D. W.
Published: October 2002

The effect of unfrozen water content on the thermal properties of the ground is discussed in the context of the TTOP model. In soils with a significant freezing characteristic the ratio of unfrozen and frozen conductivities is not single‐valued, which is an assumption of the TTOP model. Numerical simulations of the thermal regime for a range of fine‐grained soils are used to determine the effect of variable soil conductivity on the temperature at the top of permafrost. Results show that the temperature dependent conductivity function can be used with a temperature based on the surface freezing index to estimate an appropriate single value of the frozen conductivity for use in the TTOP model. Copyright © 2002 John Wiley & Sons, Ltd.
Flexible fiberoptic bronchoscopic removal of a fractured synthetic tracheostomy tube in a 3‐year‐old child
Authors: Ng Daniel K. , Cherk Sharon W. , Law Albert K.
Published: October 2002

We report on a 3‐year‐old boy, who was tracheotomized for prolonged ventilatory support in response to respiratory failure due to spinal muscular atrophy. He aspirated a fractured synthetic tracheostomy tube. It was successfully removed by flexible fiberoptic bronchoscopy. Pediatr Pulmonol. 2002; 34:141–143. © 2002 Wiley‐Liss, Inc.
Prognostic factors in cystic fibrosis in a single center in Brazil: A survival analysis
Authors: Oliveira Maria Christina Lopes A. , Reis Francisco José C. , Oliveira Eduardo A. , Colosimo Enrico A. , Monteiro Ana Paula A.F. , Penna Francisco José
Published: October 2002

The purpose of the present study was to identify prognostic factors related to death in patients with cystic fibrosis (CF). Records of 127 patients with CF submitted to a systematic protocol were retrospectively reviewed. Prognostic factors associated with demographic, nutritional, clinical, and laboratory findings on admission were studied. The median follow‐up was 44 months. The analysis was conducted in two steps. First, in a univariate analysis, variables associated with death outcome were identified by the log‐rank test. Then the variables that were significantly associated with adverse outcome were included in a multivariate analysis. This analysis, using the Cox proportional hazards model, was performed to identify variables that were independently associated with a worse prognosis. Only variables that remained independently associated with adverse outcome were included in the final model.

Three variables were identified as independent predictors of adverse outcome: age at diagnosis under 3 months (relative risk (RR) = 13, 95% CI = 4.5–34,P < 0.001); Shwachman‐Kulczycki (S‐K score) score below 70; and birth weight under 3,000 g. An interaction effect between S‐K score and birth weight was identified. The relative risk of death for the S‐K score was 24 (95% CI = 3–195) when birth weight was lower than 3,000 g; on the other hand, when birth weight was 3,000 g or more, the relative risk for the S‐K score was 1.4 (95% CI = 0.24–8.83).

The combination of three factors (low S‐K score, low birth weight, and young age at diagnosis) is indicative of a poor prognosis in CF patients. Pediatr Pulmonol. 2002; 34:3–10. © 2002 Wiley‐Liss, Inc.
Mutational analysis of ETV6 in prostate carcinoma
Authors: Kibel Adam S. , Faith Dennis A. , Bova G. Steven , Isaacs William B.
Published: October 2002

BACKGROUND

In an effort to better understand the molecular events responsible for progression of prostate carcinoma to metastatic disease, we have recently identified a homozygous deletion at 12p12‐13 involving ETV6 (tel). Although mutational analysis of ETV6 has not been examined previously in prostate carcinoma, it is an attractive candidate prostate cancer tumor suppressor gene since as it previously has been implicated in malignancy. Therefore, we decided to analyze 43 prostate cell lines, xenografts, and metastatic foci for inactivating mutations.

METHODS

DNA was isolated from 7 cell lines, 18 xenografts, and 18 metastatic deposits. Single‐strand conformational polymorphism (SSCP) analysis of ETV6, was performed by polymerase chain reaction (PCR) amplification of each exon by using intron specific primers. PCR products were then resolved by gel electrophoresis, and aberrantly migrating PCR products were then sequenced.

RESULTS

Two previously described polymorphisms and four novel sequence changes were identified. Polymorphisms at nucleotide 258 (G → A, Thr → Thr) and 602 (T → C, Leu → Pro) were identified in eight and one specimen(s), respectively. Analysis of noncancerous DNA confirmed the presence of the polymorphisms in the germ‐line. Four possible mutations were identified at nucleotides 24 (T → G, Cys → Trp), 380 (G → A, Arg → Glu), 776 (G → T, Arg → Leu), and 876 (C → T, Leu → Leu). Three were in xenografts or cell lines. Because normal DNA was not available, these could represent rare polymorphisms. The sole mutation in a clinical specimen, at nucleotide 876, did not result in an amino acid change.

CONCLUSION

Our data suggest that mutational inactivation ETV6 may occur in prostate carcinoma. The functional significance of these potential inactivating mutations remains to be determined. Prostate 52: 305–310, 2002. © 2002 Wiley‐Liss, Inc.
Local energy landscape flattening: Parallel hyperbolic Monte Carlo sampling of protein folding
Authors: Zhang Yang , Kihara Daisuke , Skolnick Jeffrey
Published: October 2002

Among the major difficulties in protein structure prediction is the roughness of the energy landscape that must be searched for the global energy minimum. To address this issue, we have developed a novel Monte Carlo algorithm called parallel hyperbolic sampling (PHS) that logarithmically flattens local high‐energy barriers and, therefore, allows the simulation to tunnel more efficiently through energetically inaccessible regions to low‐energy valleys. Here, we show the utility of this approach by applying it to the SICHO (SIde‐CHain‐Only) protein model. For the same CPU time, the parallel hyperbolic sampling method can identify much lower energy states and explore a larger region phase space than the commonly used replica sampling (RS) Monte Carlo method. By clustering the simulated structures obtained in the PHS implementation of the SICHO model, we can successfully predict, among a representative benchmark 65 proteins set, 50 cases in which one of the top 5 clusters have a root‐mean‐square deviation (RMSD) from the native structure below 6.5 Å. Compared with our previous calculations that used RS as the conformational search procedure, the number of successful predictions increased by four and the CPU cost is reduced. By comparing the structure clusters produced by both PHS and RS, we find a strong correlation between the quality of predicted structures and the minimum relative RMSD (mrRMSD) of structures clusters identified by using different search engines. This mrRMSD correlation may be useful in blind prediction as an indicator of the likelihood of successful folds. Proteins 2002;48:192–201. © 2002 Wiley‐Liss, Inc.
1.3‐Å resolution structure of human glutathione S‐transferase with S‐hexyl glutathione bound reveals possible extended ligandin binding site
Authors: Le Trong Isolde , Stenkamp Ronald E. , Ibarra Catherine , Atkins William M. , Adman Elinor T.
Published: October 2002

Cytosolic glutathione S‐transferases (GSTs) play a critical role in xenobiotic binding and metabolism, as well as in modulation of oxidative stress. Here, the high‐resolution X‐ray crystal structures of homodimeric human GSTA1‐1 in the apo form and in complex with S‐hexyl glutathione (two data sets) are reported at 1.8, 1.5, and 1.3Å respectively. At this level of resolution, distinct conformations of the alkyl chain of S‐hexyl glutathione are observed, reflecting the nonspecific nature of the hydrophobic substrate binding site (H‐site). Also, an extensive network of ordered water, including 75 discrete solvent molecules, traverses the open subunit–subunit interface and connects the glutathione binding sites in each subunit. In the highest‐resolution structure, three glycerol moieties lie within this network and directly connect the amino termini of the glutathione molecules. A search for ligand binding sites with the docking program Molecular Operating Environment identified the ordered water network binding site, lined mainly with hydrophobic residues, suggesting an extended ligand binding surface for nonsubstrate ligands, the so‐called ligandin site. Finally, detailed comparison of the structures reported here with previously published X‐ray structures reveal a possible reaction coordinate for ligand‐dependent conformational changes in the active site and the C‐terminus. Proteins 2002;48:618–627. © 2002 Wiley‐Liss, Inc.
Distinguishing native conformations of proteins from decoys with an effective free energy estimator based on the OPLS all‐atom force field and the surface generalized born solvent model
Authors: Felts Anthony K. , Gallicchio Emilio , Wallqvist Anders , Levy Ronald M.
Published: October 2002

Protein decoy data sets provide a benchmark for testing scoring functions designed for fold recognition and protein homology modeling problems. It is commonly believed that statistical potentials based on reduced atomic models are better able to discriminate native‐like from misfolded decoys than scoring functions based on more detailed molecular mechanics models. Recent benchmark tests on small data sets, however, suggest otherwise. In this work, we report the results of extensive decoy detection tests using an effective free energy function based on the OPLS all‐atom (OPLS‐AA) force field and the Surface Generalized Born (SGB) model for the solvent electrostatic effects. The OPLS‐AA/SGB effective free energy is used as a scoring function to detect native protein folds among a total of 48,832 decoys for 32 different proteins from Park and Levitt's 4‐state‐reduced, Levitt's local‐minima, Baker's ROSETTA all‐atom, and Skolnick's decoy sets. Solvent electrostatic effects are included through the Surface Generalized Born (SGB) model. All structures are locally minimized without restraints. From an analysis of the individual energy components of the OPLS‐AA/SGB energy function for the native and the best‐ranked decoy, it is determined that a balance of the terms of the potential is responsible for the minimized energies that most successfully distinguish the native from the misfolded conformations. Different combinations of individual energy terms provide less discrimination than the total energy. The results are consistent with observations that all‐atom molecular potentials coupled with intermediate level solvent dielectric models are competitive with knowledge‐based potentials for decoy detection and protein modeling problems such as fold recognition and homology modeling. Proteins 2002;48:404–422. © 2002 Wiley‐Liss, Inc.
Larvicidal activity against Plutella xylostella of cordycepin from the fruiting body of Cordyceps militaris
Authors: Kim Jun‐Ran , Yeon Sung‐Hum , Kim Ho‐San , Ahn Young‐Joon
Published: October 2002

The insecticidal activities of methanol extracts of Cordyceps militaris Link (Ascomycotina: Clavicipitaceae) cultured on fresh pupae of Bombyx mori L against 3rd‐instar larvae of Plutella xylostella L were examined using direct contact application. The larvicidal activity was more pronounced in an extract of C militaris fruiting body than in an extract of the pupae separated from the culture. The biologically active constituent of the Cordyceps fruiting body was characterized as cordycepin (3′‐deoxyadenosine) by spectroscopic analysis. Responses varied according to dose, exposure time and application method. In a leaf‐dipping test, cordycepin at 500 mg litre−1 caused no mortality at 1 DAT (day after treatment) but 78 and 100% mortality at 2 and 4 DAT, respectively, whereas 34 and 88% mortality at 3 and 5 DAT, respectively was observed at 300 mg litre−1. Cordycepin caused body colour change from pale green to dark brown and eventually body lysis. These results suggested that the larvicidal action may be attributable to a direct effect rather than an inhibitory action on chitin synthesis. There was a significant difference in insecticidal activity of cordycepin between leaf dipping (500 mg litre−1) with 100% mortality and topical application (10 µg per larva) with 0% mortality, suggesting that cordycepin has stomach action. Cordycepin merits further study as a potential P xylostella control agent or as a lead compound.

© 2002 Society of Chemical Industry
Seed dressings to control slug damage in oilseed rape
Authors: Simms Louise C , Mullins Christopher E , Wilson Michael J
Published: October 2002

Slugs are major pests of oilseed rape that are poorly controlled by conventional bait pellets. A series of laboratory experiments investigated the potential of seed‐dressings to control slug damage in this crop. Four compounds: metaldehyde, methiocarb, cinnamamide and 3,5‐dimethoxycinnamic acid (DMCA) were tested at a range of doses for phytotoxicity and ability to reduce damage by Deroceras reticulatum (Müller). Metaldehyde and methiocarb were not phytotoxic at any doses, whereas all doses of cinnamamide and DMCA were. All compounds reduced slug damage, but metaldehyde and methiocarb consistently performed better than cinnamamide and DMCA. Metaldehyde and methiocarb seed‐dressings were compared with baited pellets containing the same active ingredients at recommended field doses. The seed‐dressings protected plants from damage by D reticulatum and Arion subfuscus (Draparnaud) as well as, or better than, baited pellets. We therefore recommend that metaldehyde and methiocarb should be field‐tested as seed dressings to control slugs in oilseed rape.

© 2002 Society of Chemical Industry
The ABC of pharmaceutical trial design: some basic principles
Authors: Julious Steven , Zariffa Névine
Published: October 2002

This is a teaching paper intended as a quick introduction to some of the key concepts in the design of pharmaceutical trials for those new to the industry.

Since the first ‘modern’ randomized clinical trial was reported in 1948 by the Medical Research Council, clinical trials have become a central component in the assessment of new therapies. The primary objective of any clinical trial is to obtain an unbiased and reliable assessment of a given regimen response independent of any known or unknown prognostic factors. The essential principals of trial design can be thought of as the ABC of allocation at random, blinding and controlled. In addition, the three Rs of endpoint selection – representative, reliability and reproducibility – are relevant in this context.

This paper briefly describes the basic concepts for clinical trials and highlights possible points to consider. It draws heavily on the principles highlighted in the International Conference on Harmonisation guidelines as well as recommendations in the CONSORT statement. Copyright © 2002 John Wiley & Sons, Ltd.
Computational resiliency
Authors: Lee Joohan , Chapin Steve J. , Taylor Stephen
Published: October 2002

The notion ofcomputational resiliencyrefers to the ability of a distributed application to tolerate intrusion when under information warfare (IW) attack. This technology seeks an active strengthening of a military mission, rather than protecting its network infrastructure using static defensive measures such as network security, intrusion sensors, and firewalls. Computational resiliency involves the dynamic use of replication, guided by mission policy, to achieve intrusion tolerance so that even undetected attacks do not cause mission failure; however, it goes further to dynamically regenerate replication in response to an IW attack, allowing the level of system assurance to be restored and maintained. Replicated structures are protected through several techniques such as camouflage, dispersion, and layered security policy. This paper describes a prototype concurrent programming technology that we have developed to support computational resiliency and describes how the library has been applied in two prototypical applications. Copyright © 2002 John Wiley & Sons, Ltd.
All linear methods are equal—and extendible to (some) nonlinearities
Authors: Gertler Janos
Published: October 2002

Several linear methods of residual generation for fault detection and diagnosis are reviewed. The parity relation approach is introduced in some detail, for both additive and parametric faults. The Chow–Willsky scheme, various diagnostic observers and principal component analysis are compared to the additive version. The ‘local approach’ and the least‐squares estimation of parameter changes are shown to be related to the parametric variant. Nonlinear extensions are demonstrated for all the techniques under additive faults. Copyright © 2002 John Wiley & Sons, Ltd.
Robust multiple‐fault detection filter
Authors: Chen Robert H. , Speyer Jason L.
Published: October 2002

A new robust multiple‐fault detection and identification algorithm is determined. Different from other algorithms which explicitly force the geometric structure by using eigenstructure assignment or geometric theory, this algorithm is derived from solving an optimization problem. The output error is divided into several subspaces. For each subspace, the transmission from one fault, denoted the associated target fault, is maximized while the transmission from other faults, denoted the associated nuisance fault, is minimized. Therefore, each projected residual of the robust multiple‐fault detection filter is affected primarily by one fault and minimally by other faults. The transmission from process and sensor noises is also minimized so that the filter is robust with respect to these disturbances. It is shown that, in the limit where the weighting on each associated nuisance fault transmission goes to infinity, the filter recovers the geometric structure of the restricted diagonal detection filter of which the Beard–Jones detection filter and unknown input observer are special cases. Filter designs can be obtained for both time‐invariant and time‐varying systems. Copyright © 2002 John Wiley & Sons, Ltd.
Fault estimation—a standard problem approach
Authors: Stoustrup J. , H. Niemann H.
Published: October 2002

This paper presents a range of optimization based approaches to fault diagnosis. A variety of fault diagnosis problems are reformulated in the so‐called standard problem set‐up introduced in the literature on robust control. Once the standard problem formulations are given, the fault diagnosis problems can be solved by standard optimization techniques. The proposed methods include (1) fault diagnosis (fault estimation, (FE)) for systems with model uncertainties; FE for systems with parametric faults, and FE for a class of nonlinear systems. Copyright © 2002 John Wiley & Sons, Ltd.
Control of minimally constrained cobots
Authors: Hodgson Antony J. , Emrich Richard
Published: October 2002

Cobots are devices which use computer‐oriented passive constraints to guide an end‐effector driven by a human. This synergistic union of human skill and robotic precision is desired in fields such as surgical robotics (our application area of interest) where the surgeon would prefer not to hand over control of a procedure to an autonomous robot. Typical cobot designs intrinsically allow at most one degree of freedom of motion, but there are some tasks (such as using a bone saw to cut a plane in knee replacement surgery) where allowing two or more degrees of freedom is desireable. While it is possible to use selective constraint alignment to increase the apparent degrees of freedom of a cobot, this requires more actuators than are strictly necessary for the task, as well as a force sensor to detect the user's intent. We, therefore, introduce here the concept of minimally constrained cobots for multiple degree of freedom (DOF) tasks such as planar cutting, and outline a general framework for controlling such devices. We illustrate our control algorithms by using a planar cart example and discuss how they might be applied to potential designs for three‐dimensional parallel cobots intended for surgical applications. © 2002 Wiley Periodicals, Inc.
Design and evaluation of the asynchronous voice meeting system AVM
Authors: Nishimoto Takuya , Yuki Hidehiro , Kawahara Takehiko , Araki Masahiro , Niimi Yasuhisa
Published: October 2002

A voice communication system for asynchronous meetings held in non‐real time will attract a broad range of users because it is convenient and easy to use with mobile devices. To realize such a system, however, it will be necessary to make possible the natural input of the progressive process of speech at the same time as facilitating the quotation of audio information and outlining of others' references.

This study reports the design and evaluation of a new interface for effective asynchronous voice meetings, the AVM (Asynchronous Voice Meeting System), a client—server‐type meeting system that uses overlapping speech. Speeches were, in particular, displayed as text information on the client side for the effective visualization of comments made during these voice meetings. The proposed system AVM was compared with an electronic bulletin board system by discussing the same topic. Using the AVM, the total number of speech utterances decreased, and the total amount of letters dropped to 48% compared to the conventional electronic bulletin board system. Subjective evaluations also rated the AVM highly, indicating the usefulness of the proposed system. © 2002 Wiley Periodicals, Inc. Syst Comp Jpn, 33(11): 61–69, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1164
Adaptive dose finding for phase I clinical trials of drugs used for chemotherapy of cancer
Authors: Potter Douglas M.
Published: October 2002

Phase I clinical trials of cancer chemotherapy drugs are intended to determine the maximum tolerable dose (MTD). Thestandard method employed is a rule‐based dose‐escalation scheme in which escalation depends on the number of patients at a dose level that have dose‐limiting toxicity (DLT). The MTD is thus defined in terms of the rules and a series of dose levels selected for sampling. For some trials it is desirable to have a more precise definition of the MTD, and to determine the MTD more accurately than possible with the rule‐based schemes. Continuous reassessment methods (CRMs) define the MTD to be the dose at which a fixed fraction of patients experience DLT, and thus appear suited to these trials. It is shown, however, that these methods can have failure modes that in fact make them unattractive. An alternative data‐driven dose‐finding method is described that combines the robustness of the rule‐based methods and with features of CRMs. The method has two stages. In the first stage, doses are escalated by a factor of 1.5. In the second stage, which begins at the first instance of DLT, a two‐parameter logistic dose–response model estimates the MTD from the DLT experience of all patients. The model is initialized by setting the dose (d10) at which 10 per cent of patients would experience DLT to half the dose at which the first DLT was observed, and the dose (d90) at which 90 per cent would experience DLT to ten times d10. Weights are assigned such that the information at d10 and d90 is equivalent to that of one patient at each of the two doses. Cohorts of three patients are treated in both stages, and the dose for a new cohort in the second stage is the estimated MTD. The only prior information required to specify the design completely is the dose which will be given to the first cohort. Two stopping rules are investigated; among the requirements for these are that at least three (or four) DLTs be observed and at least nine patients be treated in the second stage. Simulations show that a coefficient of variation of approximately 0.4 on a target DLT probability of 0.3 is obtained over a wide variation in dose–response characteristics of the study drug. The performance of the new method is compared to that of rule‐based methods. Copyright © 2002 John Wiley & Sons, Ltd.
Early selection in a randomized phase II clinical trial
Authors: Steinberg Seth M. , Venzon David J.
Published: October 2002

A randomized phase II clinical trial design can be employed when one wishes to be able to select one of several similar therapies or variants of a therapy for inclusion in a subsequent, definitive, phase III trial. It is not necessary in this type of trial to formally identify a superior arm using the usual parameters and stringent criteria employed for hypothesis testing. Simon, Wittes and Ellenberg have described methods and sample sizes for selecting the superior arm from among k possible arms. In this paper, we describe an approach based on statistical selection theory which allows one to potentially make a decision to end accrual to a randomized phase II trial at an interim point of the trial, and to select one of two arms as being worthy of further evaluation in a subsequent study. This method requires that an adequate gap in the number of responses between the two arms be observed at the interim point in order to limit the probability that the selected arm is actually inferior by more than an indifference amount. Published in 2002 by John Wiley & Sons, Ltd.
Alliance capability, stock market response, and long‐term alliance success: the role of the alliance function
Authors: Kale Prashant , Dyer Jeffrey H. , Singh Harbir
Published: October 2002

This paper addresses two key questions: (1) what factors influence firms' ability to build alliance capability and enjoy greater alliance success, where firm‐level alliance success is measured in two ways: (a) abnormal stock market gains following alliance announcements and (b) managerial assessments of long term alliance performance; and (2) are the two alternate ways of assessing alliance success correlated? We find that firms with greater alliance experience and, more importantly, those that create a dedicated alliance function (with the intent of strategically coordinating alliance activity and capturing/disseminating alliance‐related knowledge) realize greater success with alliances. More specifically, firms with a dedicated alliance function achieve greater abnormal stock market gains (average of 1.35%) and report that 63 percent of alliances are successful whereas firms without an alliance function achieve much lower stock market gains (average of 0.18%) and only a 50 percent long‐term success rate. We also find a positive correlation between stock market‐based measures of alliance success and alliance success measured through managerial assessments. In addition to providing insights into the development of alliance capability among firms, this paper is one of the first to provide empirical support for the efficient markets argument by demonstrating that the initial stock market response to a key event positively correlates to the long‐term performance and value of the event. Copyright © 2002 John Wiley & Sons, Ltd.
Do formal contracts and relational governance function as substitutes or complements?
Authors: Poppo Laura , Zenger Todd
Published: October 2002

Relational exchange arrangements supported by trust are commonly viewed as substitutes for complex contracts in interorganizational exchanges. Many argue that formal contracts actually undermine trust and thereby encourage the opportunistic behavior they are designed to discourage. In this paper, we develop and test an alternative perspective: that formal contracts and relational governance function as complements. Using data from a sample of information service exchanges, we find empirical support for this proposition of complementarity. Managers appear to couple their increasingly customized contracts with high levels of relational governance (and vice versa). Moreover, this interdependence underlies their ability to generate improvements in exchange performance. Our results concerning the determinants of these governance choices show their distinct origins, which further augments their complementarity in practice. Copyright © 2002 John Wiley & Sons, Ltd.
Strategic alliances as social capital: a multidimensional view
Authors: Koka Balaji R. , Prescott John E.
Published: October 2002

Defining social capital in terms of the information benefits available to a firm due to its strategic alliances we present a theory of social capital that conceptualizes it as a multidimensional construct. We draw from the literature to argue that social capital yields three distinctly different kinds of information benefits in the form of information volume, information diversity, and information richness. This extends current theoretical and empirical research by specifying and empirically demonstrating three interrelated yet distinct dimensions of social capital. Firms vary in their levels of social capital not just on their structural position in an alliance network but also in the dynamics that underlie alliance formation and maintenance. More importantly, the different dimensions of social capital theoretically provide differential benefits. We establish the construct validity of our proposed three‐dimensional conceptualization of social capital using longitudinal data on the population of strategic alliances formed during the period 1980–94 by firms in the global steel industry. In addition, we establish predictive validity by demonstrating that the information dimensions have differential effects on firm performance, using firm nationality as a contingency. Copyright © 2002 John Wiley & Sons, Ltd.
Predicting project delivery rates using the Naive–Bayes classifier
Authors: Stewart B.
Published: October 2002

The importance of accurate estimation of software development effort is well recognized in software engineering. In recent years, machine learning approaches have been studied as possible alternatives to more traditional software cost estimation methods. The objective of this paper is to investigate the utility of the machine learning algorithm known as the Naive–Bayes classifier for estimating software project effort. We present empirical experiments with the Benchmark 6 data set from the International Software Benchmarking Standards Group to estimate project delivery rates and compare the performance of the Naive–Bayes approach to two other machine learning methods—model trees and neural networks. A project delivery rate is defined as the number of effort hours per function point. The approach described is general and can be used to analyse not only software development data but also data on software maintenance and other types of software engineering. The paper demonstrates that the Naive–Bayes classifier has a potential to be used as an alternative machine learning tool for software development effort estimation. Copyright © 2002 John Wiley & Sons, Ltd.
Rapid simulator development for multicast protocol analysis
Authors: Simon Robert , Rabinovich Paul
Published: October 2002

When evaluating new protocols and algorithms it is often desirable to be able to rapidly build a specialized simulator from scratch. The advantage of this approach is that software designers can avoid the often‐steep learning curve associated with using existing simulators, and that specialized simulators can have significant computational advantages over general‐purpose programs. The drawback is that simulators can be complex to develop and debug. This paper describes our experiences developing SESAME, a Java‐based simulator designed to analyze multicast protocol performance. By using an appropriate set of design patterns we were able to rapidly develop a reusable and easy‐to‐implement framework for multicast algorithm and protocol analysis. We developed several useful approaches for rapid simulation development, including a multicast visualization tool and techniques for simulating concurrent processing within a computer network that substantially simplified code development and maintenance. Owing to performance concerns, we also ran an extensive series of performance tests of different priority queue implementations. Our design approach and the lessons that we learned in developing SESAME can be applied to rapid simulation development in general. Further, our performance results suggest that by using commercial off‐the‐shelf Java development environments it is possible to obtain sufficient performance for many time‐sensitive applications such as discrete event simulation. Copyright © 2001 John Wiley & Sons, Ltd.
A taxonomy and survey of grid resource management systems for distributed computing
Authors: Krauter Klaus , Buyya Rajkumar , Maheswaran Muthucumaru
Published: October 2002

The resource management system is the central component of distributed network computing systems. There have been many projects focused on network computing that have designed and implemented resource management systems with a variety of architectures and services. In this paper, an abstract model and a comprehensive taxonomy for describing resource management architectures is developed. The taxonomy is used to identify approaches followed in the implementation of existing resource management systems for very large‐scale network computing systems known as Grids. The taxonomy and the survey results are used to identify architectural approaches and issues that have not been fully explored in the research. Copyright © 2001 John Wiley & Sons, Ltd.
Application and programming experience with the Ara mobile agent system
Authors: Peine Holger
Published: October 2002

We describe a mobile agent application for distributed searching of the global Usenet network, implemented on top of the Ara mobile agent system. After short overviews of Ara and the Usenet, the application is presented in detail, beginning with some critical thoughts on mobile agent applications in general. The function and performance of the search application is then described, demonstrating the advantage of using mobile agents over an equivalent stationary implementation of the same application under certain conditions, and also discussing the limits of such conditions. This is followed by descriptions of the language to express the search queries and of the search algorithms employed. The application presentation closes with a critical discussion. The paper then concludes with some observations about mobile agent programming in general. Copyright © 2002 John Wiley & Sons, Ltd.
A TACOMA retrospective
Authors: Johansen Dag , Lauvset Kåre J. , van Renesse Robbert , Schneider Fred B. , Sudmann Nils P. , Jacobsen Kjetil
Published: October 2002

For seven years, the TACOMA project has investigated the design and implementation of software support for mobile agents. A series of prototypes has been developed, with experiences in distributed applications driving the effort. This paper describes the evolution of these TACOMA prototypes, what primitives each supports, and how the primitives are used in building distributed applications. Copyright © 2002 John Wiley & Sons, Ltd.
Enterprise frameworks: issues and research directions
Authors: Mili Hafedh , Fayad Mohamed , Brugali Davide , Hamu David , Dori Dov
Published: October 2002

Enterprise frameworks are a special class of application frameworks. They are distinguished from other application frameworks in terms of scale and focus. In terms of focus, application frameworks typically cover one particular aspect of an application, either a domain‐dependent aspect (e.g., billing in a web‐based customer‐to‐business ordering system), or a computational infrastructure aspect such as distribution, man‐machine interface, or persistence, etc. Generally, an application framework alone delivers no useful end‐user function. With infrastructure frameworks, we still have to plug in domain functionalities, while with domain frameworks, we need to set‐up the infrastructure. In contrast, enterprise frameworks embody a reference architecture for an entire application, covering both the infrastructure aspects of the application, and much of the domain‐specific functionality. Instantiating an enterprise framework is nothing short of application engineering, where the architecture and many of the components are reusable. While creativity and continual improvement may be the major ingredients for building a good application framework, anything related to enterprise frameworks, be it building, documenting, or instantiating them, is complex and requires careful design and planning. In this paper, we identify the issues involved in building, using, and maintaining enterprise frameworks, both from research and practical perspective. Copyright © 2002 John Wiley & Sons, Ltd.