bluuebunny/crossref_metadata_2025 huggingface dataset:
Asymptotic behaviour for random walks in random environments
Authors: Alili S.
Published: April 2003

In this paper we consider limit theorems for a random walk in a random environment, (Xn). Known results (recurrence-transience criteria, law of large numbers) in the case of independent environments are naturally extended to the case where the environments are only supposed to be stationary and ergodic. Furthermore, if ‘the fluctuations of the random transition probabilities around are small’, we show that there exists an invariant probability measure for ‘the environments seen from the position of (Xn)’. In the case of uniquely ergodic (therefore non-independent) environments, this measure exists as soon as (Xn) is transient so that the ‘slow diffusion phenomenon’ does not appear as it does in the independent case. Thus, under regularity conditions, we prove that, in this case, the random walk satisfies a central limit theorem for any fixed environment.
Ornstein–Uhlenbeck type processes with non-normal distribution
Authors: Jensen Jens Ledet , Pedersen Jan
Published: April 2003

We analyse a class of diffusion models that (i) allows an explicit expression for the likelihood function of discrete time observation, (ii) allows the possibility of heavy-tailed observations, and (iii) allows an analysis of the tails of the increments. The class simply consists of transformed Ornstein–Uhlenbeck processes and is of relevance for heavy-tailed time series. We also treat the question of the existence of an equivalent martingale measure for the class of models considered.
Optimal control of a truncated general immigration process through total catastrophes
Authors: Kyriakidis E. G.
Published: April 2003

A Markov decision model is considered for the control of a truncated general immigration process, which represents a pest population, by the introduction of total catastrophes. The optimality criterion is that of minimizing the expected long-run average cost per unit time. Firstly, a necessary and sufficient condition is found under which the policy of never controlling is optimal. If this condition fails, a parametric analysis, in which a fictitious parameter is varied over the entire real line, is used to establish the optimality of a control-limit policy. Furthermore, an efficient Markov decision algorithm operating on the class of control-limit policies is developed for the computation of the optimal policy.
An iterative approximation scheme for repetitive Markov processes
Authors: Tüfekçi Tolga , Güllü Refik
Published: April 2003

Repetitive Markov processes form a class of processes where the generator matrix has a particular repeating form. Many queueing models fall in this category such as M/M/1 queues, quasi-birth-and-death processes, and processes with M/G/1 or GI/M/1 generator matrices. In this paper, a new iterative scheme is proposed for computing the stationary probabilities of such processes. An infinite state process is approximated by a finite state process by lumping an infinite number of states into a super-state. What we call the feedback rate, the conditional expected rate of flow from the super-state to the remaining states, given the process is in the super-state, is approximated simultaneously with the steady state probabilities. The method is theoretically developed and numerically tested for quasi-birth-and-death processes. It turns out that the new concept of the feedback rate can be effectively used in computing the stationary probabilities.
A probabilistic analogue of the mean value theorem and its applications to reliability theory
Authors: Di Crescenzo Antonio
Published: April 2003

In a similar spirit to the probabilistic generalization of Taylor's theorem by Massey and Whitt [13], we give a probabilistic analogue of the mean value theorem. The latter is shown to be useful in various contexts of reliability theory. In particular, we provide various applications to the evaluation of the mean total profits of devices having random lifetimes, to the mean total-time-on-test at an arbitrary order statistic of a random sample of lifetimes, and to the mean maintenance cost for the second room of queueing systems in steady state characterized by two serial waiting rooms.
Optimal active redundancy allocation in k-out-of-n system
Authors: Mi Jie
Published: April 2003

A k-out-of-n system consisting of n components is one that works if and only if at least k of the n components work. Suppose there are n+r (1 ≤ r ≤ n) components available of which r will be used for active redundancy. From the given n+r components, r components are chosen to be used as active redundancies, and another r components receive active redundancies (i.e. these r components are bolstered). Consider a k-out-of-n system consisting of the r bolstered and the other n – r original components. The problem of which r components should be used for active redundancy, and where to allocate them in order to maximize the lifetime of the resulting k-out-of-n system is studied. It is shown that under the usual stochastic ordering ‘≤st’ the first r weakest components should be used for active redundancy and allocated in reverse order to the next r weakest components.
Bounded normal approximation in simulations of highly reliable Markovian systems
Authors: Tuffin Bruno
Published: April 2003

In this paper, we give necessary and sufficient conditions to ensure the validity of confidence intervals, based on the central limit theorem, in simulations of highly reliable Markovian systems. We resort to simulations because of the frequently huge state space in practical systems. So far the literature has focused on the property of bounded relative error. In this paper we focus on ‘bounded normal approximation’ which asserts that the approximation of the normal law, suggested by the central limit theorem, does not deteriorate as the reliability of the system increases. Here we see that the set of systems with bounded normal approximation is (strictly) included in the set of systems with bounded relative error.
Phase transition in the random triangle model
Authors: Häggström Olle , Jonasson Johan
Published: April 2003

The random triangle model was recently introduced as a random graph model that captures the property of transitivity that is often found in social networks, i.e. the property that given that two vertices are second neighbors, they are more likely to be neighbors. For parametersp∊ [0,1] andq≥ 1, and a finite graphG= (V,E), it assigns to elements η of {0,1}Eprobabilities which are proportional towheret(η) is the number of triangles in the open subgraph. In this paper the behavior of the random triangle model on the two-dimensional triangular lattice is studied. By mapping the system onto an Ising model with external field on the hexagonal lattice, it is shown that phase transition occurs if and only ifp= (q−1)−2/3andq>qcfor a critical valueqcwhich turns out to equalIt is furthermore demonstrated that phase transition cannot occur unlessp=pc(q), the critical value for percolation of open edges for givenq. This implies that forq≥qc,pc(q) = (q−1)−2/3.
A note on losses in M/GI/1/n queues
Authors: Righter Rhonda
Published: April 2003

Let Ln be the number of losses during a busy period of an M/GI/1/n queueing system. We develop a coupling between Ln and Ln+1 and use the resulting relationship to provide a simple proof that when the mean service time equals the mean interarrival time, ELn = 1 for all n. We also show that Ln is increasing in the convex sense when the mean service time equals the mean interarrival time, and it is increasing in the increasing convex sense when the mean service time is less than the mean interarrival time.
Gastric function and its contribution to the postprandial metabolic response of the Burmese pythonPython molurus
Authors: Secor Stephen M.
Published: April 2003

The large intact prey ingested by Burmese pythons require considerable processing by the stomach before passage into the small intestine. To investigate the function and cost of gastric digestion and its contribution to postprandial metabolic response for the Burmese python, I examined the rate of gastric digestion, the postprandial profile of gastric pH and the effects of decreasing gastric workload on the metabolic cost of digestion, referred to as specific dynamic action (SDA). Ingested meal mass (equivalent to 25% of snake body mass) was reduced by 18% within 1 day postfeeding, by which time intragastric pH had decreased from 7.5 to 2. Gastric pH was maintained at 1.5 for the next 5–7 days, after which it returned to 7.5. The SDA generated by digesting an intact rat meal was reduced by 9.1%, 26.0%, 56.5% and 66.8%,respectively, when pythons were fed steak, ground rat, liquid diet or ground rat directly infused into the small intestine. The production of HCl and enzymes and other gastric functions represent an estimated 55% of the python's SDA generated from the digestion of an intact rodent meal. Additional contributors to SDA include protein synthesis (estimated 26%),gastrointestinal upregulation (estimated 5%) and the activities of the pancreas, gallbladder, liver, kidneys and intestines during digestion(estimated 14%). Operating on a `pay before pumping' principle, pythons must expend endogenous energy in order to initiate acid production and other digestive processes before ingested nutrients can be absorbed and channeled into metabolic pathways.
Aquatic turning performance by the whirligig beetle: constraints on maneuverability by a rigid biological system
Authors: Fish Frank E. , Nicastro Anthony J.
Published: April 2003

Turning performance is constrained by morphology, where the flexibility of the body and the mobility and position of the control surfaces determine the level of performance. The use of paddling appendages in conjunction with the rigid bodies of aquatic arthropods could potentially limit their turning performance. Whirligig beetles (Coleoptera: Gyrinidae) are rigid-bodied, but these aquatic insects can swim rapidly in circular patterns. Turning performance of swimming whirligig beetles (Dineutes horni) was assessed by videotaping beetles in a small (115 mm diameter) arena at 500 frames s–1 and 1000 frames s–1. Curved trajectories were executed as continuous powered turns. Asymmetrical paddling of the outboard legs was used to power the turn. Turns were produced also by abduction of the inboard elytra and vectored thrust generated from sculling of the wing at 47.14 Hz. The abducted elytra increased drag and acted as a pivot. Swimming speeds varied from 0.06 m s–1 to 0.55 m s–1 (4.7–44.5 L s–1). Relative minimum radius was 24%of body length. Maximum rate of turn was 4428 degrees s–1 with maximum centripetal acceleration of 2.86 g. Turning radius was weakly associated with swimming velocity,although minimum values of the radius showed no correlation with velocity. Turning rate was also related indirectly to radius and directly to centripetal acceleration. Compared to vertebrates with flexible bodies, the relative turning radius of whirligig beetles is constrained by a rigid body and use of drag-based propulsive mechanisms. However, these mechanisms permit continuous turning, and the size of the beetle permits higher turn rates with lower centripetal accelerations.
New Morphology-controlled Poly(aniline) Synthesis Using Anionic Porphyrin Aggregate as a Template
Authors: Hatano Tsukasa , Takeuchi Masayuki , Ikeda Atsushi , Shinkai Seiji
Published: April 2003

It was found that 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS), which is known to aggregate in a one-dimensional direction in water, acted as a template for electrochemical polymerization of aniline on ITO electrode. Examinations using cyclic voltammetry (CV) and UV–vis spectroscopy established that J-aggregated TPPS molecules were entrapped in the resultant poly(aniline). Scanning electron microscopy (SEM) observation established that poly(aniline) grew up to a nanosized rod-like structure, reflecting the aggregation structure of TPPS. It is a very novel and important finding that poly(aniline), which has been believed to result in only “rigid” film, can be morphologically controlled using a “template method”.
Book Reviews
Authors: Lev Benjamin , Kaiser Mark , Adenso-Díaz B. , Cooper Robert B. , Zilinskas Antanas
Published: April 2003

The range of books reviewed is wide, covering theory and applications in operations research, statistics, management science, econometrics, mathematics, computers, and information systems (no software is reviewed). In addition, we include books in other fields that emphasize technical applications. Publishers who wish to have their books reviewed should send them to Professor Benjamin Lev. We list the books received; not all books received can be reviewed because space and time are limited. Those who would like to review books are urged to send me their names, addresses, and specific areas of expertise. We commission all reviews and do not accept unsolicited book reviews. Readers are encouraged to suggest books that might be reviewed or to ask publishers to send me copies of such books.
Dynamic Workforce Scheduling for British Telecommunications plc
Authors: Lesaint David , Voudouris Christos , Azarmi Nader
Published: April 2003

British Telecommunications plc (BT) employs thousands of field engineers across the UK to maintain networks, repair faults, and provide service to customers. To allocate work efficiently, BT developed Work Manager, an information system that automates work management and field communications. In 1996, the Intelligent Systems Research group of BT enhanced Work Manager with a dynamic scheduler (DS) based on a combination of heuristic search and constraint-based reasoning. Rolled out in 1997 and reaching 20,000 engineers in 1998, DS with Work Manager is saving BT $150 million a year on operational costs. When deployed over the targeted workforce of 40,000 people, the system will save an estimated $250 million a year.
An Asset and Liability Management System for Towers Perrin-Tillinghast
Authors: Mulvey John M. , Gould Gordon , Morgan Clive
Published: April 2003

Towers Perrin-Tillinghast employs a stochastic asset-and-liability management system for helping its pension plan and insurance clients understand the risks and opportunities related to capital market investments and other major decisions. The system has three major components: (1) a stochastic scenario generator (CAP:Link); (2) a nonlinear optimization simulation model (OPT:Link); and (3) a flexible liability- and financial-reporting module (FIN:Link). Each part improves over existing technology as compared with traditional actuarial approaches. The integrated investment system links asset risks to liabilities so that company goals are best achieved. For example, US WEST saved $450 to $1,000 million in opportunity costs in its pension plan by following the advice of the asset-and-liability system.
The Use of Data Envelopment Analysis in Banking Institutions: Evidence from the Commercial Bank of Greece
Authors: Athanassopoulos Antreas D. , Giokas Dimitris
Published: April 2003

Since 1988, the Commercial Bank of Greece (CBG) has instituted performance measurement systems for bank branches using data envelopment analysis (DEA). This is the first application of DEA in Greece and among the few around the world that have resulted in continuous use of the method within a large-scale organization. The project was undertaken by a mixed team of banking experts assisted by academics specializing in developing bank branch performance measurement systems. During the project (1988–1994) the performance measurement technology was transferred and acquired by the staff of the bank. Various methodological issues arose during this study regarding the objectives of assessing branch performance, the importance of input/output sets in assessing branch efficiency, and the behavioral implications of management control systems. The CBG (Commercial Bank of Greece) has accepted data envelopment analysis as a useful tool for assessing branch performance and for obtaining insights to support decisions.
Reverse-Logistics Strategy for Product Take-Back
Authors: Klausner Markus , Hendrickson Chris T.
Published: April 2003

Product take-back of consumer products is generally expensive, especially reverse logistics. In the take-back program for power tools in Germany, costs exceed revenues for recycling power tools. Systematic analysis of take-back alternatives can make take-back policies more attractive. For example, an alternative take-back system for power tools would combine profitable remanufacturing and unprofitable materials recycling. The profit from remanufacturing could cover the loss from recycling as well as the costs of reverse logistics, allowing the manufacturer a profit. Remanufacturing requires a continuous flow of returned postconsumer products. By buying back end-of-life products, firms could control the flow of returned products. We developed a model that allows us to determine the optimal amount to spend on buy-back and the optimal unit cost of reverse logistics. We can use the latter to select a suitable reverse-logistics system for end-of-life products. We apply our model to the remanufacturing take-back concept for power tools, using empirical data on the current take-back program.
Implementing Industrial Ecology: The AT&T Matrix System
Authors: Allenby Braden R.
Published: April 2003

Industrial ecology, the multidisciplinary study of coupled economic and environmental systems, provides the intellectual basis for understanding and implementing the vision of sustainable development in the firm. Using this approach, AT&T developed a matrix system which, when applied to the firm's products and operations, laid the groundwork for systemic improvements in the firm's environmental performance.
Xilinx Improves Its Semiconductor Supply Chain Using Product and Process Postponement
Authors: Brown Alexander O. , Lee Hau L. , Petrakian Raja
Published: April 2003

The semiconductor firm Xilinx uses two different postponement strategies: product postponement and process postponement. In product postponement, the products are designed so that the product's specific functionality is not set until after the customer receives it. Xilinx designed its products to be programmable, allowing customers to fully configure the function of the integrated circuit using software. In process postponement, a generic part is created in the initial stages of the manufacturing process. In the later stages, this generic part is customized to create the finished product. Xilinx manufactures a small number of generic parts and holds them in inventory. The use of these generic parts allows Xilinx to hold less inventory in those finished products that it builds to stock. And for some finished products, Xilinx can perform the customization steps quickly enough to allow it to build to order.
Book Reviews
Authors: Lev Benjamin , Murphy Frederic H. , Fowler Bruce W.
Published: April 2003

The range of books reviewed is wide, covering theory and applications in operations research, statistics, management science, econometrics, mathematics, computers, and information systems (no software is reviewed). In addition, we include books in other fields that emphasize technical applications. Publishers who wish to have their books reviewed should send them to Professor Benjamin Lev. We list the books received; not all books received can be reviewed because space and time are limited. Those who would like to review books are urged to send me their names, addresses, and specific areas of expertise. We commission all reviews and do not accept unsolicited book reviews. Readers are encouraged to suggest books that might be reviewed or to ask publishers to send me copies of such books.
Book Reviews
Authors: Lev Benjamin , Sherali Hanif D. , Zilinskas Antanas , Voss Stefan , Reisman Arnold
Published: April 2003

The range of books reviewed is wide, covering theory and applications in operations research, statistics, management science, econometrics, mathematics, computers, and information systems (no software is reviewed). In addition, we include books in other fields that emphasize technical applications. Publishers who wish to have their books reviewed should send them to Professor Benjamin Lev. We list the books received; not all books received can be reviewed because space and time are limited. Those who would like to review books are urged to send me their names, addresses, and specific areas of expertise. We commission all reviews and do not accept unsolicited book reviews. Readers are encouraged to suggest books that might be reviewed or to ask publishers to send me copies of such books.
Rethinking Project Selection at the Monterey Bay Aquarium
Authors: Felli James C. , Kochevar Randall E. , Gritton Bruce R.
Published: April 2003

In 1995, the Monterey Bay Aquarium started an experimental business unit called Electronic Outreach. Electronic Outreach's mission was to employ emerging technologies to deliver the aquarium's messages of ocean stewardship to diverse and scattered audiences. Faced with many projects from which to choose, the Electronic Outreach team wanted to determine which projects were most likely to succeed before they actually had to dedicate resources to development. We constructed two models to help them accomplish this: a multiattribute-value model to quantify a project's alignment with the aquarium's mission and a discounted-cash-flow model to quantify a project's viability as a business venture. We then combined the outputs of these two models into a two-dimensional framework to allow the Electronic Outreach team members to focus on monetary-nonmonetary trade-offs when evaluating potential projects.
Production Scheduling Theory: Just Where Is It Applicable?
Authors: Portougal Victor , Robb David J.
Published: April 2003

A proliferation of scheduling research has done little to improve production planning practice, despite calls for more comprehensive models. Using a four-factor classification of planning environments (planning level, production type, production strategy, and production cycle time) we show scheduling theory is relevant in few settings. For example, in increasingly common short-cycle environments, where production cycle times are shorter than the planning period, the order in which one processes jobs is seldom important. Moreover, even in long-cycle environments, capacity is seldom fixed, with managers often negotiating for enough capacity to make scheduling fairly easy. Based on extensive consulting experience in Australasia, we call for caution in applying scheduling theory. While complex models are pertinent in some cases, more benefit often arises from establishing appropriate performance measures, planning periods, capacity negotiation processes, and uncertainty reduction measures.
Determining Rail Fleet Sizes for Shipping Automobiles
Authors: Sherali Hanif D. , Maguire Lawrence W.
Published: April 2003

Automobile manufacturers (shippers) provide railroad companies with annual forecasts of their monthly shipping volumes from various origins to different destinations. The railroad companies (carriers) jointly operate pools of railcars to transport automobiles. Each pool comprises equipment of a particular type and serves one or more shippers. RELOAD, a fleet management group within TTX (an independent company), manages the repositioning of empty railcars of each type for the carriers. The problem is to determine the smallest fleet size that will provide adequate service. The parties involved have settled on a coordinated use of static and dynamic fleet-sizing models along with appropriate correction factors to recommend the number of railcars of each type that should be acquired for any year. The approach incorporates such operating realities as queue times, forecast accuracy, and daily demand variability. By using this process, the railroad companies have reduced equipment commitments, saving over half a billion dollars annually.
Police Officers' and Students' Beliefs about Telling and Detecting Trivial and Serious Lies
Authors: Vrij Aldert , Taylor Rachel
Published: April 2003

This questionnaire study investigated whether 52 police officers and 54 students expect differences between trivial (low stake) and serious (high stake) lies which are told by themselves or by others. We investigated differences in how often such lies occur, how difficult it is to detect them, whether telling these lies results in nervousness and requires mental effort and whether verbal and nonverbal behaviours would give these lies away. Results revealed that police officers and students had similar ideas about these issues, although these were not always accurate. For example, both groups reported that serious lies require more mental effort and are more stressful for the liar than trivial lies, but neither of the two groups indicated that this would affect liars' behaviour accordingly.
Identification of the first non‐Jewish mutation in familial Dysautonomia
Authors: Leyne Maire , Mull James , Gill Sandra P. , Cuajungco Math P. , Oddoux Carole , Blumenfeld Anat , Maayan Channa , Gusella James F. , Axelrod Felicia B. , Slaugenhaupt Susan A.
Published: April 2003

Familial Dysautonomia is an autosomal recessive disease with a remarkably high carrier frequency in the Ashkenazi Jewish population. It has recently been estimated that as many as 1 in 27 Ashkenazi Jews is a carrier of FD. The FD gene has been identified as IKBKAP, and two disease‐causing mutations have been identified. The most common mutation, which is present on 99.5% of all FD chromosomes, is an intronic splice site mutation that results in tissue‐specific skipping of exon 20. The second mutation, R696P, is a missense mutation that has been identified in 4 unrelated patients heterozygous for the major splice mutation. Interestingly, despite the fact that FD is a recessive disease, normal mRNA and protein are expressed in patient cells. To date, the diagnosis of FD has been limited to individuals of Ashkenazi Jewish descent and identification of the gene has led to widespread diagnostic and carrier testing in this population. In this report, we describe the first non‐Jewish IKBKAP mutation, a proline to leucine missense mutation in exon 26, P914L. This mutation is of particular significance because it was identified in a patient who lacks one of the cardinal diagnostic criteria for the disease–pure Ashkenazi Jewish ancestry. In light of this fact, the diagnostic criteria for FD must be expanded. Furthermore, in order to ensure carrier identification in all ethnicities, this mutation must now be considered when screening for FD. © 2003 Wiley‐Liss, Inc.
Brief communication: Y‐chromosome haplotypes in Egypt
Authors: Lucotte G. , Mercier G.
Published: April 2003

We analyzed Y‐chromosome haplotypes in the Nile River Valley in Egypt in 274 unrelated males, using the p49a,f TaqI polymorphism. These individuals were born in three regions along the river: in Alexandria (the Delta and Lower Egypt), in Upper Egypt, and in Lower Nubia. Fifteen different p49a,f TaqI haplotypes are present in Egypt, the three most common being haplotype V (39.4%), haplotype XI (18.9%), and haplotype IV (13.9%). Haplotype V is a characteristic Arab haplotype, with a northern geographic distribution in Egypt in the Nile River Valley. Haplotype IV, characteristic of sub‐Saharan populations, shows a southern geographic distribution in Egypt. Am J Phys Anthropol 121:000–000, 2003. © 2003 Wiley‐Liss, Inc.
Comparative morphology of the pollical distal phalanx
Authors: Shrewsbury M.M. , Marzke M.W. , Linscheid R.L. , Reece S.P.
Published: April 2003

Functional analysis of human pollical distal phalangeal (PDP) morphology is undertaken to establish a basis for the assessment of fossil hominid PDP morphology. Features that contribute to the effectiveness of grips involving the distal thumb and finger pulp areas include: 1) distal thumb interphalangeal joint morphology, facilitating PDP conjunct pronation with flexion; 2) differentiation of a proximal, mobile pulp region from a distal, stable pulp region, providing for firm precision pinch grips and precision handling of objects; and 3) asymmetric attachment of the flexor pollicis longus (FPL) tendon fibers, favoring PDP conjunct pronation. A proportionately larger size of the ulnar vs. radial ungual spine suggests differential loading intensity of the ulnar side of the proximal ungual pulp and supporting nail bed. Stresses at the distal interphalangeal joint are indicated by the presence of a sesamoid bone within the volar (palmar) plate, which also increases the length of the flexor pollicis longus tendon moment arm. Dissections of specimens from six nonhuman primate genera indicate that these human features are shared variably with individuals in other species, although the full pattern of features appears to be distinctively human. Humans share variably with these other species all metric relationships examined here. The new data identify a need to systematically review long‐standing assumptions regarding the range of precision and power manipulative capabilities that might reasonably be inferred from morphology of the distal phalangeal tuberosity and from the FPL tendon insertion site on the PDP. Am J Phys Anthropol 121:000–000, 2003. © 2003 Wiley‐Liss, Inc.
Brief communication: Study of noncarious cervical tooth lesions in samples of prehistoric, historic, and modern populations from the South of France
Authors: Aubry M. , Mafart B. , Donat B. , Brau J.J.
Published: April 2003

Noncarious tooth lesions (NCTL) are frequent findings in contemporary dental practices. Unlike other dental and periodontal diseases, NCTL have not been studied in an anthropological context. The purpose of the present study was to compare the prevalence of NCTL in three archaeological samples from the Copper Age and Middle Ages and in subjects examined in three dental practices. Both archaeological samples and dental‐practice subjects were from southern France. In the archaeological sample group, no NCTL were detected in 3,927 teeth from 259 individuals. In the dental‐practice group, prevalence rates were in agreement with current epidemiological data. Our data also suggest that prevalence of NCTL increases with age and is higher in females. Premolars were the most affected tooth type. Occurrence of NCTL has long been attributed to toothbrushing and to erosion by intrinsic and extrinsic acids. More recently, occlusal stress associated with tooth flexure has been implicated. The reasons underlying the total absence of NCTL in archaeological samples are discussed. The most likely explanations involve differences in lifestyle, diet, and dental condition. Am J Phys Anthropol 121:000–000, 2003. © 2003 Wiley‐Liss, Inc.
The electrochemistry of some ferrocene derivatives: redox potential and substituent effects
Authors: Batterjee Suzan M. , Marzouk M. I. , Aazab M. E. , El‐Hashash M. A.
Published: April 2003

Fifteen ferrocene derivatives I–IX (four of which have been prepared for the first time: II, IIIf, V and VIII) have been prepared by Friedel–Crafts acetylation, Claisen condensation, Michael reaction, and ring closure by hydrazine hydrate. The anodic behaviour of these compounds has been studied by cyclic voltammetry at a platinum electrode in an aprotic solvent. All these substituted ferrocenes exhibit a reversible one‐electron oxidation reduction centred at each iron centre, and the effect of substituents on the half‐wave oxidation potential is discussed in terms of their electronic properties. Linear correlations have been observed between these potentials and the Hammett σx constant for the substituents. Cyclic voltammetry has been carried out for ferrocene derivatives IIIa, V and IX. Copyright © 2003 John Wiley & Sons, Ltd.
Interfacial properties of PP/PP composites
Authors: Kitayama T. , Utsumi S. , Hamada H. , Nishino T. , Kikutani T. , Ito H.
Published: April 2003

All‐polypropylene (PP/PP) composites, consisting of homoisotactic PP fibers and a propylene–ethylene random copolymer matrix, were manufactured. The interfacial morphologies and mechanical deformation of the composites were investigated. It was found that a transcrystalline layer was formed in the matrix depending on the molding conditions. This layer is composed of two regions with different morphologies: In one region close (<300 nm) to the fibers, lamellae exist very densely and the c‐axes of the crystal lattices are oriented along the longitudinal direction of the fiber. In the other region, a little away (>300 nm) from the fiber, a cross‐hatched structure was observed. The well‐developed transcrystalline layer could be highly elongated, and no debonding was observed at the fiber/matrix interface by the tensile stress in the direction perpendicular to the fiber. It is conceivable that this is the reason for the observed improvement of the transverse tensile properties in the PP/PP composite with a transcrystalline layer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2875–2883, 2003
Glass‐transition temperatures and rheological behavior of methyl methacrylate–styrene random copolymers
Authors: Liu Guodong , Zhang Liucheng , Yao Yanmei , Yang Liting , Gao Jungang
Published: April 2003

Poly(methyl methacrylate‐ran‐styrene) copolymers were synthesized under monomer‐starved conditions by emulsion copolymerization. The glass‐transition temperatures (Tg's) of the copolymers were measured by differential scanning calorimetry (DSC) and torsional braid analysis (TBA). The results showed that the methyl methacrylate–styrene random copolymers produced an asymmetric Tg versus composition curve, which could not even be interpreted by the Johnston equation with different contributions of dyads to the Tg of the copolymer considered. A new sequence distribution equation concerning different contributions of triads was introduced to predict the copolymer's Tg. The new equation fit the experimental data exactly. Also, the Tg determined by TBA (TgTBA) was higher than the one determined by DSC (TgDSC) and the difference was not constant. The rheological behavior of the copolymers was also studied. TgTBA − TgDSC increased with increasing flow index of the melt of the copolymer, and the reason was interpreted. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2891–2896, 2003
Effect of different isocyanates on the properties of soy‐based polyurethanes
Authors: Javni Ivan , Zhang Wei , Petrović Zoran S.
Published: April 2003

New types of polyurethanes were prepared by reacting soybean oil‐based polyol and different isocyanates. The polyurethanes can be used as foams, elastomers, coatings, adhesives, etc. Their properties strongly depend on crosslinking density and the structure of isocyanates. Aromatic triisocyanates impart the highest density, glass transition, modulus, and tensile strength, but have the lowest elongation at break, swelling in toluene, and impact resistance. Aliphatic triisocyanates and diisocyanates give rubbery materials with the highest elongation at break, highest swelling, and the lowest tensile strength. Polyurethanes with aromatic and cycloaliphatic diisocyanates were similar in properties, with values between those of the two groups. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2912–2916, 2003
Chemical preparation of conducting polyfuran/poly(2‐chloroaniline) composites and their properties: A comparison of their components, polyfuran and poly(2‐chloroaniline)
Authors: Gök Ayşegül , Sarı Bekir , Talu Muzaffer
Published: April 2003

Conductive homopolymers and composites of poly(2‐chloroaniline) (P2ClAn) and polyfuran (PFu) were synthesized chemically in hydrous and anhydrous media, and their properties were investigated. The polymers and composites were characterized by Fourier infrared spectroscopy, ultraviolet‐visible absorption spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, magnetic susceptibility, and conductivity measurements. It was found that the PFu/P2ClAn composite is thermally more stable than both the P2ClAn/PFu composite and the homopolymers. It was determined from Gouy scale measurements that conducting mechanisms of homopolymers and composites are polaron and bipolaron in nature. It was observed that the conductivity and magnetic susceptibility values changed with a changing amount of the guest polymer in the prepared composites. The conductivity (3.21 × 10−2 S/cm) of the P2ClAn/PFu (55.8% m/m) composite was found to be higher than the conductivities of both homopolymers (σPFu = 1.44 × 10−5 S/cm; σP2ClAn = 1.32 × 10−3 S/cm). It was determined that the composites synthesized had different conductivities and morphological and thermal properties from changing synthesis order. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2924–2931, 2003
Effect of crosslinked structure on SO2 gas sorption properties in amino‐functional copolymers
Authors: Matsuguchi Masanobu , Sakurada Katsuya , Sakai Yoshiro
Published: April 2003

SO2 gas sorption properties were examined for poly(styrene‐co‐chloromethyl styrene) functionalized with N,N‐dimethyl‐1,3‐propanediamine (DMPDA). The DMPDA‐functional copolymers were prepared under various reaction conditions. Two types of SO2 sorption behaviors were observed for these DMPDA‐functional copolymers: SO2 sorption capacity was very high irrespective of slow sorption/desorption rates (type I), and the sorption/desorption rates were very fast while SO2 sorption capacity was small (type II). Fourier transform infrared analysis and dielectric loss measurement revealed that the type II sorption behavior was obtained for the highly crosslinked DMPDA‐functional copolymers. The degree of crosslinking was affected by both the solvent used to react DMPDA with the copolymer and the percent conversion of the chloromethyl styrene group. It was confirmed that DMPDA‐functional copolymers having a highly crosslinked structure are suitable materials in quartz crystal microbalance (QCM)‐type polymeric SO2 gas sensors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2982–2987, 2003
Inhibition of furin‐like enzymes blocks interleukin‐1α/oncostatin M–stimulated cartilage degradation
Authors: Milner J. M. , Rowan A. D. , Elliott S.‐F. , Cawston T. E.
Published: April 2003

Objective

To investigate the role of furin‐like enzymes in the proteolytic cascades leading to cartilage breakdown and to examine which collagenase(s) contribute to collagen degradation.

Methods

Bovine nasal cartilage was stimulated to resorb with the addition of interleukin‐1α (IL‐1α)/oncostatin M (OSM) in the presence or absence of a furin inhibitor, Dec‐RVKR‐CH2Cl, or selective matrix metalloproteinase 1 (MMP‐1) inhibitors. Collagen and proteoglycan levels were determined by assay of hydroxyproline and sulfated glycosaminoglycan, respectively. Collagenase and gelatinase activity were measured using 3H‐acetylated collagen and gelatin zymography, respectively.

Results

The addition of Dec‐RVKR‐CH2Cl to stimulated cartilage reduced the release of collagen fragments and the levels of active collagenase and MMP‐2, suggesting that furin‐like enzymes are involved in the cascades leading to activation of procollagenases. At MMP inhibitor concentrations that selectively inhibit MMP‐1, no inhibition of collagen release was observed, but increasing the concentration to the 50% inhibition concentration for MMP‐13 resulted in a 50% blockage of collagen release. The addition of Dec‐RVKR‐CH2Cl to resorbing cartilage also partially blocked proteoglycan release, thus demonstrating a role for furin‐activated enzymes in the pathways leading to proteoglycan degradation.

Conclusion

Furin‐like enzymes are involved in cascades leading to activation of procollagenases and degradation of collagen. MMP‐13, which can be activated by furin‐processed membrane‐type 1 MMP‐1, appears to be a major collagenase involved in collagen degradation induced by IL‐1α/OSM. Furin‐like enzymes also appear to play a role in the pathways leading to proteoglycan degradation. These findings are of importance when considering proteinase inhibition as a target for therapeutic intervention in arthritic diseases.
Antinuclear antibodies following infliximab treatment in patients with rheumatoid arthritis or spondylarthropathy
Authors: De Rycke Leen , Kruithof Elli , Van Damme Nancy , Hoffman Ilse E. A. , Van den Bossche Nancy , Van den Bosch Filip , Veys Eric M. , De Keyser Filip
Published: April 2003

Objective

To investigate the effect of infliximab treatment on antinuclear antibodies (ANAs), anti–double‐stranded DNA (anti‐dsDNA), antinucleosome, antihistone, and anti–extractable nuclear antigen (anti‐ENA) antibodies in rheumatoid arthritis (RA) and spondylarthropathy (SpA) patients.

Methods

Sera from 62 RA and 35 SpA patients treated with infliximab were tested at baseline and week 30 (RA group) or week 34 (SpA group). ANAs were tested by indirect immunofluorescence (IIF) on HEp‐2 cells. Anti‐dsDNA antibodies were detected by IIF on Crithidia luciliae and by enzyme‐linked immunosorbent assay (ELISA) and were further isotyped with γ, μ, and α chain–specific conjugates at various time points. Antinucleosome antibodies were tested by ELISA. Antihistone and anti‐ENA antibodies were detected by line immunoassay.

Results

Initially, 32 of 62 RA patients and 6 of 35 SpA patients tested positive for ANAs. After infliximab treatment, these numbers shifted to 51 of 62 (P < 0.001) and 31 of 35 (P < 0.001), respectively. At baseline, none of the RA or SpA patients had anti‐dsDNA antibodies. After infliximab treatment, 7 RA patients (P = 0.016) and 6 SpA patients (P = 0.031) became positive for anti‐dsDNA antibodies. All 7 anti‐dsDNA–positive RA patients had IgM and IgA anti‐dsDNA antibodies. Three of the 6 anti‐dsDNA–positive SpA patients had IgM and IgA anti‐dsDNA antibodies, and 2 had IgM anti‐dsDNA antibodies alone. In both diseases, the IgM anti‐dsDNA antibodies appeared before the IgA anti‐dsDNA antibodies. During the observation period, no IgG anti‐dsDNA antibodies or lupus symptoms were observed. The development of antinucleosome, antihistone, or anti‐ENA antibodies following infliximab treatment was observed in some patients, but the numbers were not statistically significant.

Conclusion

Infliximab treatment may induce ANAs, and especially IgM and IgA anti‐dsDNA antibodies, in RA and SpA patients. However, no anti‐dsDNA IgG antibodies or lupus symptoms were observed during the period of observation in this study, and the development of antinucleosome, antihistone, or anti‐ENA antibodies was not statistically significant. These observations do not exclude potential induction of clinically significant lupus in the long term, and further followup is therefore mandatory.
Low prevalence of antibodies to glucose‐6‐phosphate isomerase in patients with rheumatoid arthritis and a spectrum of other chronic autoimmune disorders
Authors: Matsumoto Isao , Lee David M. , Goldbach‐Mansky Raphaela , Sumida Takayuki , Hitchon Carol A. , Schur Peter H. , Anderson Ronald J. , Coblyn Jonathan S. , Weinblatt Michael E. , Brenner Michael , Duclos Bernard , Pasquali Jean‐Louis , El‐Gabalawy Hani , Mathis Diane , Benoist Christophe
Published: April 2003

Objective

Arthritis in the K/BxN mouse model results from pathogenic immunoglobulins that recognize glucose‐6‐phosphate isomerase (GPI), a glycolytic enzyme residing in the cytoplasm of all cells. Antibodies directed against GPI can, alone, transfer arthritis to healthy recipients. Previous experiments have revealed significant titers of anti‐GPI antibodies in the serum of many patients with rheumatoid arthritis (RA). We evaluated the generality of these observations in cohorts of patients with 12 different arthritic and chronic autoimmune diseases and in population‐matched healthy control subjects.

Methods

Anti‐GPI antibodies were assayed in 811 individual serum samples by enzyme‐linked immunosorbent assay with 2 forms of GPI, recombinant and native. Results were confirmed by immunoblotting.

Results

Several patients had significantly elevated anti‐GPI antibody titers, but without the prevalence or the specificity reported previously. Only 15% of RA patients had anti‐GPI antibodies (range 12–29% in different cohorts), with a higher prevalence in patients with active disease. Psoriatic arthritis, undifferentiated arthritis, and spondylarthropathy patients also displayed anti‐GPI antibodies at similar frequencies (12–25%). Similar titers were detected in a proportion (5–10%) of control subjects or patients with Crohn's disease or sarcoidosis. Very high titers were found in rare cases of RA and systemic lupus erythematosus.

Conclusion

No disease‐specific pattern of antibody positivity to GPI was apparent. While the antibody‐mediated mechanism at play in the mouse model may exemplify a generic mechanism for some forms of arthritis in humans, GPI itself does not appear to be a target common to the majority of RA patients.
Pathogenic T cells in murine lupus exhibit spontaneous signaling activity through phosphatidylinositol 3‐kinase and mitogen‐activated protein kinase pathways
Authors: Niculescu Florin , Nguyen Phuong , Niculescu Teodora , Rus Horea , Rus Violeta , Via Charles S.
Published: April 2003

Objective

To determine the activation status of two cytoplasmic signaling pathways, phosphatidylinositol 3‐kinase (PI 3‐kinase) and the mitogen‐activated protein kinase (MAPK) family.

Methods

We studied the pathogenic CD4+ T cells that drive disease in the parent‐into‐F1 mouse model of lupus‐like chronic graft‐versus‐host disease (GVHD). We determined immunoprecipitated kinase activity for PI 3‐kinase and MAPK members (Raf‐1, extracellular signal–regulated kinase 1 [ERK‐1], c‐Jun N‐terminal kinase 1 [JNK‐1], and p38 MAPK) from either unfractionated splenocytes or purified donor CD4+ T cells. Uninjected normal mice served as negative controls, and acute GVHD mice served as positive controls.

Results

Compared with negative controls, unfractionated splenocyte kinase activity from chronic GVHD mice was significantly increased for PI 3‐kinase and JNK‐1, but not for Raf‐1, p38 MAPK, or ERK‐1. Increased PI 3‐kinase and JNK‐1 activity was also seen in acute GVHD splenocytes, as was increased Raf‐1 and p38 MAPK activity. The pattern of increased PI 3‐kinase and JNK‐1 activity seen in unfractionated chronic GVHD splenocytes was also seen in isolated donor, but not host, CD4+ T cells from chronic GVHD mice, indicating that donor CD4+ T cell signaling activity accounted for at least a portion of the activity observed in unfractionated splenocytes. Increased ERK‐1 activity was not seen in either donor or host CD4+ T cells. This pattern of cytoplasmic signaling pathway in donor CD4+ T cells was associated with increased T cell receptor membrane signaling activation (Lck and Fyn phosphorylation) and increased transcription activation (phosphorylation of inhibitor of nuclear factor κB), confirming the biologic significance of these observations.

Conclusion

The pathogenic T cells driving disease in this murine model exhibit activation in the form of spontaneous cytoplasmic signaling pathway activity that can be detected without in vitro restimulation and involves a T cell–specific (PI 3‐kinase) and a nonspecific stress/cytokine pathway (JNK‐1). These results raise the possibility that a full characterization of the signaling pathways active in pathogenic lupus T cells might lead to new therapeutic targets.