bluuebunny/crossref_metadata_2025_split huggingface dataset:
Borehole deformation measurements and internal structure of some rock glaciers in Switzerland
Authors: Arenson Lukas , Hoelzle Martin , Springman Sarah 
Published: October 2002

AbstractIn 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

AbstractBACKGROUNDFibroblast 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.METHODSTo 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.RESULTSThe 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.CONCLUSIONSThese 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

AbstractIf 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

AbstractAn 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

AbstractThe 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

AbstractImidacloprid 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

AbstractStudies 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

AbstractThe 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

AbstractIn 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

AbstractWe 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

AbstractWe 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

AbstractThis 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

AbstractIn 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

AbstractI 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

AbstractLetc> 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

AbstractWe 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

AbstractI 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

AbstractModelling 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.