bluuebunny/crossref_metadata_2025 huggingface dataset:
Restick following initial Angioseal use
Authors: Applegate Robert J. , Rankin Kevin M. , Little William C. , Kahl Frederic R. , Kutcher Michael A.
Published: January 2003

The Angioseal hemostatic device is currently in widespread use for arterial closure after both diagnostic and interventional procedures. Resticking of the artery in which an Angioseal device has been placed has been discouraged for up to 90 days after the initial device placement because of theoretical concerns of disruption or dislodgment of the hemostatic plug. However, no data are available to address this concern. We evaluated the incidence of vascular complications following restick of the artery in which an Angioseal device had been deployed ≤ 90 days previously in 181 patients. Restick occurred 1–7 days after device placement in 80 patients, 8–30 days in 34 patients, and 31–90 days in 66 patients. There were no major bleeding, vascular repair, vessel occlusion, or embolizations. Three large hematomas (1.7%) were noted. These data suggest that restick can be performed safely after initial Angioseal deployment. Cathet Cardiovasc Intervent 2003;58:181–184. © 2003 Wiley‐Liss, Inc.
Double scaling limit in the random matrix model: The Riemann‐Hilbert approach
Authors: Bleher Pavel M. , Its Alexander R.
Published: January 2003

We prove the existence of the double scaling limit in the unitary matrix model with quartic interaction, and we show that the correlation functions in the double scaling limit are expressed in terms of the integrable kernel determined by the ψ function for the Hastings‐McLeod solution to the Painlevé II equation. The proof is based on the Riemann‐Hilbert approach, and the central point of the proof is an analysis of analytic semiclassical asymptotics for the ψ function at the critical point in the presence of four coalescing turning points. © 2003 Wiley Periodicals, Inc.
Long‐time asymptotics of moving boundary problems using an Ehrenpreis‐type representation and its Riemann‐Hilbert nonlinearization
Authors: Fokas A. S. , Schultz P. F.
Published: January 2003

A new method for solving boundary value problems for linear and integrable nonlinear PDEs has recently been introduced. For a linear evolution equation with dispersion relation ω(k), in a time‐dependent concave domain, 𝓁(t) < x < ∞, 𝓁″(t) < 0, this method yields the solution q(x, t) as a line integral in the complex k‐plane, whose integrand has explicit (x, t)‐dependence of the form exp[ikx − iω(k)t]. For a nonlinear integrable evolution equation the situation is similar, but the integrand also involves the solution M(x, t, k) to a Riemann‐Hilbert problem whose jump function also has explicit (x, t)‐dependence of exponential form. These representations for linear and for nonlinear evolution equations are convenient for the study of the long‐time asymptotics, using the stationary phase and the Deift‐Zhou methods, respectively. Here we study the long‐time asymptotics in a time‐dependent concave domain for a linear evolution equation with a spatial derivative of arbitrary order, and for the defocusing nonlinear Schrödinger equation. For completeness we also study the long‐time asymptotics for a linear evolution equation with a spatial derivative of arbitrary order in the fixed domain 0 < x < ∞. © 2003 Wiley Periodicals, Inc.
Quercetin, a bioflavonoid, reverses development of tolerance and dependence to morphine
Authors: Singh Amanpreet , Naidu Pattipati S. , Kulkarni Shrinivas K.
Published: January 2003

Quercetin, a bioflavonoid (25 and 50 mg/kg), when chronically administered for 9 days, failed to produce any significant change in tail flick latency as compared to control mice. However, repeated administration of quercetin (25 and 50 mg/kg) for 9 days attenuated the development of tolerance to the analgesic effect of morphine (10 mg/kg). Quercetin (25 and 50 mg/kg) also suppressed naloxone (2 mg/kg)‐precipitated withdrawal jumps on day 10 in morphine‐tolerant mice. Pretreatment of mice with quercetin (10–50, ip) significantly reversed the morphine (5 mg/kg)‐induced delay in gastric transit, whereas a higher dose of quercetin (100 mg/kg) did not have any significant effect on morphine‐induced delay in gastric transit. Quercetin per se had no effect on gastric transit. In conclusion, the results of the present study suggest potential use of quercetin in alleviating the adverse effects of opioid treatment. Drug Dev. Res. 57:167–172, 2002. © 2003 Wiley‐Liss, Inc.
Evidence for the recognition of non‐nucleotide antagonists within the transmembrane domains of the human P2Y1 receptor
Authors: Guo Danping , Kügelgen Ivar von , Moro Stefano , Kim Yong‐Chul , Jacobson Kenneth A.
Published: January 2003

Site‐directed mutagenesis was used to search for amino acid residues of the human P2Y1 receptor involved in the binding of the P2 receptor antagonists pyridoxal‐5′‐phosphate‐6‐azophenyl‐2,4‐disulfonate (PPADS), its analogue 6‐(2′‐chloro‐phenylazo)‐pyridoxal‐α5‐phosphate (MRS 2210), the suramin analogue 8‐8′‐[carbonylbis(imino‐3,1‐phenylene)]bis(1,3,5‐naphthalene‐trisulfonate) (NF023), and Reactive blue 2. Receptors containing single amino acid replacements at positions in transmembrane helical domains (TMs) 3, 5, 6, and 7 critical for the activation of the receptor by nucleotide agonists were expressed in COS‐7 (African green monkey kidney) cells. Inositol phosphate accumulation was induced by 2‐methylthioadenosine 5′‐diphosphate (2‐MeSADP). In wild type human P2Y1 receptors, PPADS (10 to 60 µM), MRS 2210 (10 µM), NF023 (100 µM), and Reactive blue 2 (10 µM) shifted the concentration‐response curve of 2‐MeSADP in a parallel manner to the right. For PPADS, a pA2 value of 5.2 was estimated. The shifts caused by MRS 2210, NF023, and Reactive blue 2 corresponded to apparent pKB values of 5.6, 5.0, and 5.8, respectively. In K280A mutant receptors, the affinities of PPADS, MRS 2210, NF023, and Reactive blue 2 were about 6‐ to 60‐fold lower than those observed at wild type receptors. The K280A mutation also caused an approximately 1,000‐fold increase in the EC50 value of the agonist 2‐MeSADP, similar to previous observations. In contrast, no major change in antagonistic potency was observed at receptors with other mutations in TMs 3, 5, 6, and 7. Thus, the residue Lys280 (6.55), which is located within the upper third of TM 6 of the human P2Y1 receptor, is not only critical for the activation of the receptor but also plays an important role in the binding of pyridoxal derivatives and a number of other chemically unrelated P2 receptor antagonists. Lys280 seems to belong to an overlapping region of the respective binding sites. Drug Dev. Res. 57:173–181, 2002. Published 2003 Wiley‐Liss, Inc.
Suppression of experimental zymosan‐induced arthritis by intraperitoneal administration of adenosine
Authors: Baharav Ehud , Dubrosin Anatoly , Fishman Pnina , Bar‐Yehuda Sara , Halpren Marisa , Weinberger Abraham
Published: January 2003

The anti‐inflammatory effect of methotrexate (MTX) is mediated by the increasing extracellular concentration of adenosine. The response of the immune system to activation of cell membrane subclass receptors for adenosine initiates intracellular signaling pathways, which causes immunomodulatory responses. To test the direct immunomodulatory effects of systemic administration of adenosine on animal model of inflammation, zymosan induced arthritis (ZIA) in mice was employed. Sterile zymosan (30 µg) was injected directly into the knee cleft of 60 mice, divided into 3 equal groups. The experimental groups received, every second day, 0, 0.25, and 0.5 mg/kg adenosine intraperitoneally. Inflammatory intensity was evaluated clinically by knee swelling measurement, histology, the total white blood cell (WBC) count, and serum tumor necrosis factor‐alpha (TNF‐α) levels served as markers of systemic inflammatory reaction. As observed, only the mice that received the higher dose of 0.5 mg/kg adenosine developed a significantly milder arthritis. A 23.9% reduction (P < 0.004) of the mean knee diameter swelling was noted. The histological inflammatory parameters and WBC count in the 0.5 mg/kg adenosine‐treated mice were also decreased (6,555 ± 510/mm3 vs. 9,250 ± 530 WBC/mm3 in the untreated mice, P > 0.006; 9,188 ± 588 WBC/mm3 in the 0.25 mg/kg adenosine‐treated group). Serum TNF‐α levels were significantly reduced (78.1 pg/ml in the 0.5 mg/kg adenosine‐treated group vs. 124.3 pg/ml, in the control group, P < 0.004). The data indicate a remarkable clinical beneficial effect, as well as a local and systemic anti‐inflammatory response that was noted on administration of 0.5 mg/kg adenosine every alternate day to mice with inflammatory arthritis. Drug Dev. Res. 57:182–186, 2002. © 2003 Wiley‐Liss, Inc.
Age‐related susceptibility to brain ischemia in mice
Authors: Fuentes‐Vargas Monica , Santiago‐Mejia Jacinto , Pinzon Enrique , Rodriguez Rodolfo
Published: January 2003

In this study, we evaluated the effect of age on survival and on neurological alterations produced by bilateral sequential common carotid artery (CCA) sectioning in mice. Male mice, 3–4 (young), 20–30 (adult), and 40–60 (aged) weeks old, underwent sequential CCA sectioning at an interval of 32 days. After the second surgery, mortality was registered continuously over a period of 24 h and thereafter every 24 h up to 3 days. Neurological assessment was performed 24 h after the second surgery. The influence of age on survival was analyzed using a log‐rank test, and survival curves were generated by the Kaplan‐Meier method. In mice with previous left CCA sectioning, sectioning of the contralateral artery induced a wide range of neurological alterations and a high mortality rate. Young and aged animals had a significantly lower (P < 0.05) survival rate as compared to adults (3, 6, 9, and 12 h after the second surgery), thus confirming that young and aged animals are, in fact, less resistant to brain ischemia. In contrast, the percentage of mice showing severe neurological alterations increased with age. This observation coincides with clinical evidence showing that elderly tend to have a worse outcome than younger patients do. These findings indicate that, besides morphological changes, studies of influence of age on the susceptibility to brain ischemia should include mortality and functional endpoints. Drug Dev. Res. 57:161–166, 2002. © 2003 Wiley‐Liss, Inc.
Effects of ReN1869, a CNS‐available antihistamine, on capsaicin‐ and histamine‐induced neurogenic inflammation in healthy subjects
Authors: Thomsen Mikael S. , Hansen Anker J. , Olsen Uffe B. , Reeh Peter , Ingwersen Steen , Schaffler Klaus , Seibel Klaus
Published: January 2003

ReN1869 (elsewhere referred to as NNC 05‐1869) is a new tricyclic compound which is chemically related to amitriptyline, but is without any significant interaction with other receptors except for the histamine H1‐receptor, where it functions as an antagonist. The compound exhibits antinociceptive effects in rodent models of chronic pain and is effective against inflammation of neurogenic origin. The present trial was designed to assess the effect of a single dose of ReN1869 in humans on neurogenic inflammation induced by capsaicin and histamine and on the concomitant itch and pain sensation. Twenty‐four healthy male subjects were enrolled in this randomized, double‐blind, two‐period, crossover trial consisting of a single oral dose of 95 mg ReN1869 and matching placebo. Thirty minutes after dosing the participants received, in a randomized order, either histamine (on the skin of the palmar forearm, prick test) before capsaicin (on the skin of the back) in both trial periods and capsaicin before histamine in both periods. Several pharmacodynamic tests were performed after the capsaicin/histamine application: laser somatosensory‐evoked potentials (Laser‐SEP), sensory and pain threshold to laser stimuli of increasing intensity, planimetry of areas of wheal and flare, pinprick hyperalgesia, brush‐evoked pain, allodynia, skin reflection spectrometry (colorimetry), and visual analog scale of itch. ReN1869 had significant effects on the histamine‐induced phenomena. No wheal could be evoked in 14/21 evaluated subjects in contrast to all placebo‐treated subjects. The area of flare was reduced by 80% and itching by 65%. The flare induced by capsaicin was only slightly (not significantly) reduced by ReN1869. However, ReN1869 strongly influenced Laser‐SEP evoked by nociceptive stimuli from the capsaicin‐treated skin area by a 25% reduction of the amplitude of the P2 component, whereas the N1 component was not affected. This observation reflects a central analgesic effect without a peripheral component. The dosing was well tolerated and no particular adverse events were related to the trial drug. Conclusively, ReN1869 represents a new class of antihistamines that has antiinflammatory properties (related to antihistaminergic effects) as well as central analgesic effects (probably mediated centrally through histamine H1 receptors). Drug Dev. Res. 57:193–199, 2002. © 2003 Wiley‐Liss, Inc.
Effects of Ginkgo biloba extract (EGb 761) on gene expression: Possible relevance to neurological disorders and age‐associated cognitive impairment
Authors: DeFeudis Francis V.
Published: January 2003

Ginkgo biloba leaf extract (EGb 761), which contains many constituents, including flavonoid glycosides and terpenoids (ginkgolides, bilobalide), is used to treat cerebrovascular and peripheral vascular insufficiency, as well as cognitive impairment and other symptoms of dementia. Recent studies have indicated that these therapeutic effects of EGb 761 probably involve modification of the expression of many genes by actions involving several of its active constituents. As examples: EGb 761 and its ginkgolide B constituent inhibit the expression of the peripheral benzodiazepine receptor in the adrenal cortex and decrease circulating levels of corticosterone in the rat, effects that provide a mechanism for explaining the “antistress” action of the extract. Both the flavonoid and terpenoid constituents of EGb 761 decrease the expression of inducible nitric oxide synthase (iNOS), supporting an action of the extract of opposing the deleterious effects of excessive formation of NO. EGb 761 upregulates several genes that encode vital antioxidant enzymes, including heme oxygenase‐1 and the regulatory and catalytic subunits of γ‐glutamyl‐cysteinyl synthetase. Dietary treatment of mice with EGb 761 upregulates the expression of genes encoding neuronal tyrosine/threonine phosphatase 1 and microtubule‐associated tau in the cerebral cortex, findings that are of interest since these proteins are associated with the intracellular neurofibrillary tangles found in the brain in Alzheimer's disease. Bilobalide upregulates two mitochondrial‐DNA‐encoded genes, subunit III of cytochrome c oxidase and subunit ND1 of NADH dehydrogenase, indicating a fundamental mechanism that may underlie EGb 761‐induced neuroprotection. Collectively, such results indicate that the therapeutic effects of EGb 761 on cognitive impairment (dementia) may involve its action of altering gene expression. Drug Dev. Res. 57:214–235, 2002. 2003 Wiley‐Liss, Inc.
Development of CDD‐0102 as a selective M1 agonist for the treatment of Alzheimer's disease
Authors: Messer William S. , Bachmann Kenneth A. , Dockery Colleen , El‐Assadi Afif A. , Hassoun Ezdihar , Haupt Nicola , Tang Bin , Li Xuemei
Published: January 2003

Selective muscarinic agonists might be useful in the treatment of Alzheimer's disease. To help characterize the activity and functional selectivity of two M1 muscarinic agonists, secretion of amyloid precursor protein, brain penetration, side effect profiles, cognition‐enhancing properties, oral bioavailability, and acute toxicity were evaluated. CDD‐0102 stimulated the secretion of APP from CHO‐K1 cells expressing M1 receptors and penetrated into the brain following i.p. administration in rodents. CDD‐0102 produced relatively few cholinergic side effects (e.g., diarrhea, salivation) following i.p. administration in mice. The effects of muscarinic agonists on memory function were examined following bilateral injections of 192 IgG‐saporin into the diagonal band of rats to lesion basal forebrain cholinergic pathways. 192 IgG‐saporin produced decreases in cortical and hippocampal choline acetyltransferase activity and impaired performance of a paired‐run, delayed‐alternation task in a T‐maze relative to vehicle‐injected controls. Toxin‐treated rats performed significantly better following i.p. injections (1 mg/kg) of either xanomeline or CDD‐0102 as compared with saline. Prominent cholinergic side effects (e.g., diarrhea) were apparent only following xanomeline treatments. In separate studies, oral administration of CDD‐0102 (10 mg/kg) reversed the memory deficits induced by 192 IgG‐saporin in the T‐maze task. Rats achieved 54 ± 4.2% correct choices with saline, but 94 ± 1.2% following CDD‐0102 injection. In acute toxicity studies in mice, the LD50 of CDD‐0102 was greater than 1,000 mg/kg orally; 190 mg/kg i.p. The LD50 of xanomeline was 100 mg/kg p.o. and 75 mg/kg i.p. In summary, both xanomeline and CDD‐0102 displayed beneficial effects on memory function, while CDD‐0102 also exhibited a low side effect profile and low toxicity. CDD‐0102 warrants further evaluation as a therapeutic agent for the treatment of Alzheimer's disease. Drug Dev. Res. 57:200–213, 2002. © 2003 Wiley‐Liss, Inc.
Customers as assets
Authors: Gupta Sunil , Lehmann Donald R.
Published: January 2003

Customers are important intangible assets of a firm that should be valued and managed. Although researchers and practitioners have recently emphasized customer relationships and customer lifetime value, these concepts have had limited impact on the business and investment community for two main reasons: (a) they require extensive data and complex modeling, and (b) researchers have not shown a strong link between customer and firm value. We address these two issues in this article. First, we show how one can use publicly available information and a simple formula to estimate the lifetime value of a customer for a publicly traded firm. We illustrate this with several examples and case studies. Second, we provide a link between customer and firm value. We then show how this link provides guidelines for strategic decisions such as mergers and acquisitions as well as for assessing the value of a firm even when the traditional financial approaches (e.g., price–earnings ratio) fail.
Creating virtual product experiences: The role of telepresence
Authors: Klein Lisa R.
Published: January 2003

Given that direct product experience is generally the optimal method for consumers to learn about products, marketers should strive for verisimilitude in marketing communications. This research explores how computer-mediated environments can engender virtual product experiences. The construct of telepresence, a sense of presence in a remote environment, is used to examine the process by which media characteristics influence consumer responses. Through two experimental studies, we evaluate the effect of two media characteristics—user control and media richness—on the creation of telepresence and assess the impact of telepresence on consumer beliefs about and attitudes toward the advertised product. Results show that user control and media richness both contribute to creating a sense of telepresence. Moreover, through telepresence, these media characteristics influence consumers’ cognitive responses.
Expanding to direct channel: Market coverages as entry barrier
Authors: Choi S. Chan
Published: January 2003

A direct marketer can be either a manufacturer selling directly to the final consumers or a retailer that sells an assortment of products from multiple manufacturers. From a manufacturer's point of view, expanding to an online direct channel seems very attractive because intermediaries can be bypassed in reaching final consumers, while the Internet has substantially lowered the entry barrier. With the rapid diffusion of electronic commerce, numerous manufacturers have been considering a direct online channel as an alternative or a supplement to existing retailer channels. However, we observe in the real market that not many manufacturers are fully engaged in online retailing. One major factor frequently mentioned is the conflict with existing dealers who will not be pleased with a manufacturer's attempt to cannibalize their sales. This paper attempts to provide another explanation by comparing theoretical market coverage of manufacturers in a direct channel and a channel with intermediaries. We show that the direct channel can support fewer firms than the traditional retailer channel does, which becomes an effective entry barrier to latecomers. In equilibrium, the products are positively but finitely differentiated in their qualities, and the top two quality tiers would capture more than 75% of the direct channel's market potential (i.e., the “finiteness property”). Thus latecomers would find it difficult to gain a substantial market share against the existing pioneers in the competitive direct market unless they can find other meaningful ways to differentiate horizontally. The sales data of the online retail industry supports our finding.
Monitoring dyslexics' intelligence and attainments: A follow‐up study
Authors: Thomson Michael
Published: January 2003

Intelligence (Wechsler Intelligence Scale for Children R and III, 1992) and written language attainment (BAS Word Reading, Neale Analysis of Reading, Vernon Graded Word Spelling) data for around 250 children attending a specialist school for dyslexics are presented. The Wechsler scales data show some evidence for ‘ACID’ and ‘SCAD’ profile effects on the subtests, with specifically weak Index scores on Freedom from Distractibility and Processing Speed. The relationship between intelligence and reading development is also examined, with evidence for significant correlations between intelligence and written language and a longitudinal study showing that there is no ‘Matthew’ or drop‐off effect in intelligence. The attainments tests demonstrate that the widening gap between a dyslexic's chronological age and his/her attainments can be closed, and how attainments may be monitored within the context of ‘growth curves’. The results are discussed in relation to recent reports (e.g. B.P.S. on Dyslexia, Literacy and Psychological Assessment) on the relationship between intelligence and attainments and it is concluded that this report could be seriously misleading for practising educational psychologists. Copyright © 2003 John Wiley & Sons, Ltd.
Age‐related improvements in auditory temporal resolution in reading‐impaired children
Authors: Hautus Michael J. , Setchell Gregory J. , Waldie Karen E. , Kirk Ian J.
Published: January 2003

Individuals with developmental dyslexia show impairments in processing that require precise timing of sensory events. Here, we show that in a test of auditory temporal acuity (a gap‐detection task) children ages 6–9 years with dyslexia exhibited a significant deficit relative to age‐matched controls. In contrast, this deficit was not observed in groups of older reading‐impaired individuals (ages 10–11 years; 12–13 years) or in adults (ages 23–25 years). It appears, therefore, that early temporal resolution deficits in those with reading impairments may significantly ameliorate over time. However, the occurrence of an early deficit in temporal acuity may be antecedent to other language‐related perceptual problems (particularly those related to phonological processing) that persist after the primary deficit has resolved. This result suggests that if remedial interventions targeted at temporal resolution deficits are to be effective, the early detection of the deficit and early application of the remedial programme is especially critical. Copyright © 2003 John Wiley & Sons, Ltd.
Evaluation of an exercise‐based treatment for children with reading difficulties
Authors: Reynolds David , Nicolson Roderick I. , Hambly Helen
Published: January 2003

An evaluation is reported of an exercise‐based approach to remediation of dyslexia‐related disorders. Pupils in three years of a Warwickshire junior school were screened for risk of literacy difficulty using the Dyslexia Screening Test (DST). The 35 children scoring 0.4 or over on the DST were divided randomly into two groups matched for age and DST score. One quarter of the participants had an existing diagnosis of dyslexia, dyspraxia or ADHD. Both groups received the same treatment at school but the intervention group used the DDAT exercise programme daily at home. Performance on the DST and specialist cerebellar/vestibular and eye movement tests were assessed initially and after six months. Cerebellar/vestibular signs were substantially alleviated following the exercise treatment whereas there were no significant changes for the control group. Even after allowing for the passage of time, there were significant improvements for the intervention group in postural stability, dexterity, phonological skill, and (one‐tailed) for naming fluency and semantic fluency. Reading fluency showed a highly significant improvement for the intervention group, and nonsense passage reading was also improved significantly. Significantly greater improvements for the intervention group than the control group occurred for dexterity, reading, verbal fluency and semantic fluency. Substantial and significant improvements (compared with those in the previous year) also occurred for the exercise group on national standardized tests of reading, writing and comprehension. It is concluded that, in addition to its direct effects on balance, dexterity and eye movement control, the benefits of the DDAT exercise treatment transferred significantly to cognitive skills underlying literacy, to the reading process, and to standardized national literacy attainment tests. Copyright © 2003 John Wiley & Sons, Ltd.
Long‐time constants of irregular AC losses in a large superconducting coil
Authors: Hamajima Takataro , Yoshida Motonobu , Shimamura Hiroshi , Harada Naokara , Tsuda Masa , Takahata Kazuya , Satow Takashi
Published: January 2003

A large superconducting coil wound with a Cable‐in‐Conduit (CIC) conductor caused an additional AC loss, which cannot be estimated from the short conductor sample test results. It was confirmed that the additional AC loss was generated by long current loops in the CIC conductor. Magnetic field decays of the loops with various long‐time constants were observed through Hall probes. We propose a mechanism for the formation of the long loops. The CIC conductor is composed of several staged subcables. If one strand on the surface of a subcable contacts the other strand on the surface of the adjacent subcable, the two strands must encounter each other again at the LCM (Least Common Multiplier) distance of all staged cable pitches and thereby form a pair of long loops. We numerically traced each strand in the CIC according to a method in which the subcables at all substages rotate around the center of inertia. The calculated long‐time constants of the long loops were slightly shorter than the observed ones. We labeled all strands by order in a real CIC conductor, disassembling the cable carefully after peeling the conduit. It was found that the strands in a triplex were widely displaced from their original positions, so that their contacting lengths became longer than the calculated ones. This fact makes the time constant of the loop longer and hence can explain the observed long‐time constants. The proposed mechanism is effective for estimating the long loops causing additional AC losses in the coil. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 50–57, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10064
A speed control method for a PM motor using a speed observer and a low‐resolution encoder
Authors: Ohishi Kiyoshi , Ogawa Yasuaki , Dohmaki Hideo
Published: January 2003

This paper proposes a new speed control method for a PM motor using a low‐resolution encoder and a speed observer. The servo system should be economical and simple. For this purpose, this paper realizes the high‐performance speed control system using a low‐resolution encoder, whose performance is nearly equal to the performance of speed servo system using a conventional optical encoder. The speed observer uses the information of motor current and motor voltage. The rotor position is calculated by the estimated value of speed observer. This observer has the influence of electrical parameter variation. This paper proposes the correction algorithm of both the voltage error of PWM inverter and the electrical parameter variation. The experimental results and numerical simulation results point out that the proposed speed control system has the desired speed response with respect to parameter variations and load torque perturbation. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 66–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10121
Analysis of TOF transient currents affected by circuit time constants
Authors: Kikuchi Yoshiaki , Wakamatsu Takashi , Takahashi Hideaki , Endo Isao
Published: January 2003

Time‐of‐flight (TOF) transient currents affected by circuit time constants of RC at the measurements are calculated. The one‐dimensional carrier distributions by diffusion and drift transport are used in the calculations, and the strong drift and weak drift transport induces the typical TOF currents, the nondispersive and the dispersive types, respectively. For these waveforms, it is examined whether we should choose the current or the voltage measurements from RC and the observation time scale. The simulation results here pointed out that in the case of either TOF type, the TOF current method required the setting of RC value less than 1/100 of the transit time Tr, and that the voltage method required RC be more than 100 times Tr and in addition at the voltage measurements the circuit time constants have no influence on the TOF waveforms in the initial time. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(1): 1–7, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10139
Influence of common XPD and XRCC1 variant alleles on p53 mutations in lung tumors
Authors: Hou Sai‐Mei , Ryk Charlotta , Kannio Annamaria , Angelini Sabrina , Fält Susann , Nyberg Fredrik , Husgafvel‐Pursiainen Kirsti
Published: January 2003

The DNA repair proteins XPD and XRCC1 are involved in the nucleotide and base excision repair of DNA lesions induced by many tobacco and environmental carcinogens. Common variant alleles at the XPD (312Asn, 751Gln) and XRCC1 (399Gln) loci have been identified and associated with increased risk for lung cancer. We therefore investigated a possible effect of these variant alleles on the frequency and spectrum of p53 mutations in the tumors of 97 Swedish lung cancer patients (56 never‐smokers and 41 age‐, gender‐, and hospital‐matched ever‐smokers). The p53 gene was mutated in 4 never‐smokers (7%) and 11 ever‐smokers (27%). Smoking‐related transversion‐type mutations predominated over transitions among smokers (8:3), but not among never‐smokers (1:3). None of the variant alleles altered the overall frequency of p53 mutation. Transversions, however, were marginally increased among patients with at least one XPD variant allele compared with patients who were wild‐type homozygotes (73% vs. 25% for the Asp312Asn polymorphism, P = 0.095; 78% vs. 33% for Lys751Gln, P = 0.085). Five of six women or six of seven smokers who carried at least one XPD 751Gln allele had p53 transversion. The XRCC1 variant allele did not show any effect on the p53 mutation. We conclude that the XPD variant alleles may be associated with an increased frequency of smoking‐related p53 mutations in lung tumors, presumably due to reduced DNA repair proficiency. Environ. Mol. Mutagen. 41:37–42, 2003. © 2003 Wiley‐Liss, Inc.
Modelling extreme rainfall data within a catchment region
Authors: Cocchi Daniela , Scagliarini Michele
Published: January 2003

The present work examines the extreme behaviour of monthly rainfall in the Reno River catchment area (Italy). The data are recorded by a network of monitoring sites for which a single model, valid for the whole region, can be built. As a first step, a generalized extreme value (GEV) model is fitted to monthly rainfall maxima for each site. As a further step, we have introduced a second level into the model whereby the GEV site‐specific parameters depend on covariates by means of hyperparameters common to the area. The maximum likelihood method is used for the purposes of estimation. We employed an extra‐sample set of monitoring sites in order to compare the results obtained using the catchment model with the single‐site models estimated by classical one‐level extreme value analysis. Copyright © 2003 John Wiley & Sons, Ltd.
Bootstrap simulations for evaluating the uncertainty associated with peaks‐over‐threshold estimates of extreme wind velocity
Authors: Pandey M. D. , Van Gelder P. H. A. J. M. , Vrijling J. K.
Published: January 2003

In the peaks‐over‐threshold (POT) method of extreme quantile estimation, the selection of a suitable threshold is critical to estimation accuracy. In practical applications, however, the threshold selection is not so obvious due to erratic variation of quantile estimates with minor changes in threshold. To address this issue, the article investigates the variation of quantile uncertainty (bias and variance) as a function of threshold using a semi‐parametric bootstrap algorithm. Furthermore, the article compares the performance of L‐moment and de Haan methods that are used for fitting the Pareto distribution to peak data.

The analysis of simulated and actual U.S. wind speed data illustrates that the L‐moment method can lead to almost unbiased quantile estimates for certain thresholds. A threshold corresponding to minimum standard error appears to provide reasonable estimates of wind speed extremes. It is concluded that the quantification of uncertainty associated with a quantile estimate is necessary for selecting a suitable threshold and estimating the design wind speed. For this purpose, semi‐parametric bootstrap method has proved to be a simple, practical and effective tool. Copyright © 2003 John Wiley & Sons, Ltd.
Can public policy be influenced?
Authors: Herzberg Agnes M. , Frew Lee
Published: January 2003

A series of conferences concerned with the implications of statistics and science on public policy is discussed. Some thoughts about the influence of public policy on matters of the environment are presented. Copyright © 2003 John Wiley & Sons, Ltd.
Systematic sample design for the estimation of spatial means
Authors: Ambrosio Flores Luis , Iglesias Martínez Luis , Marín Ferrer Carmen
Published: January 2003

This article develops a practical approach to undertaking systematic sampling for the estimation of the spatial mean of an attribute in a selected area. A design‐based approach is used to estimate population parameters, but it is combined with elements of a model‐based approach in order to identify the spatial correlation structure, to evaluate the relative efficiency of the sample mean under simple random and systematic sampling, to estimate sampling error and to assess the sample size needed in order to achieve a desired level of precision. Using two case studies (land use estimation and weed seedbank in soil) it is demonstrated how the practical basis for the design of systematic samples provided in this work should be applied and it is shown that if the spatial correlation is ignored the sampling error of the sample mean and the sample size needed in order to achieve a desired level of precision with systematic sampling are overestimated. Copyright © 2003 John Wiley & Sons, Ltd.
Extracting quantitative dynamics from 222Rn gaseous emissions of mud volcanoes
Authors: Albarello D. , Lapenna V. , Martinelli G. , Telesca L.
Published: January 2003

In this work we explore the inner time dynamics of 222Rn gaseous emissions of a bubbling mud volcano located in northern Apennines (Italy). In order to discriminate shallow environmental effects, barometric and temperature series have been also monitored and compared with 222Rn data. The Lomb periodogram and the Higuchi techniques have been applied to characterize the time dynamics of the experimental time series. No significant periodicity has been identified and the power spectrum is characterised by a monotonic decrease with frequency f which follows a typical power law (∝f−α). Our findings suggest to consider the 222Rn time series as a realization of an antipersistent stochastic process. This indicates that the dynamics underlying Radon emissions from bubbling mud volcanoes is complex and that a relatively large number of unknown factors control the process. This result discourages the use of bubbling gaseous emissions for the monitoring of geodynamic processes. Copyright © 2003 John Wiley & Sons, Ltd.
Interannual variability in a plankton time series
Authors: Dowd Michael , Martin Jennifer L. , LeGresley Murielle M. , Hanke Alex , Page Fred H.
Published: January 2003

Temporal changes in a plankton time series are examined, with an emphasis on interannual variability. A stochastic cycle model is used which describes an annual cycle with a fixed frequency, but a randomly varying amplitude and phase. A state space representation is used with the Kalman filter, and associated fixed‐interval smoother, to provide estimation of the time‐varying state. Parameter estimation relies on maximum likelihood methods. A data set is considered comprised of an irregularly sampled time series of plankton (dinoflagellate) abundance over a 12 year period in the Bay of Fundy, off the east coast of Canada. Analysis of the log10‐transformed data indicated timing changes in the seasonal cycle of up to 23 days. Significant variations in abundance relative to the mean cycle were found for some highly sampled summer periods. Case deletion diagnostics identified two influential observations, one of which has a large impact on the estimated system noise. Examination of the sampling protocol, or monitoring design, indicates the need to reduce the observation error variance in order to improve detection of interannual variations in plankton abundance. Copyright © 2003 Crown in the right of Canada. Published by John Wiley & Sons, Ltd.
Density estimate and its application to analysis of temperature series
Authors: Horová Ivana , Zelinka Jiří , Brázdil Rudolf , Budíková Marie
Published: January 2003

Nonparametric density estimates attempt to reconstruct the probability density from which a random sample has come, using the sample values and as few assumptions as possible about the density. These methods are smoothing operations on the sample distribution. Methods of kernel estimates represent one of the most effective nonparametric methods. These methods are simple to understand, easy to implement and they have very good mathematical properties. We employed the automatic procedure for the selection of the bandwidth, the kernel and the order of the kernel. This procedure is used for analysis of air temperature fluctuations for series of Central England and Prague–Klementinum in the periods 1661–2000 and 1771–2000, respectively. Graphical representation of the family of estimated densities in three dimensional space provide a better explanation of the long‐term trends in temperature distribution of both series. Copyright © 2003 John Wiley & Sons, Ltd.
System identification of the Vincent Thomas suspension bridge using earthquake records
Authors: Smyth Andrew W. , Pei Jin‐Song , Masri Sami F.
Published: January 2003

The Vincent Thomas Bridge in the Los Angeles metropolitan area, is a critical artery for commercial traffic flow in and out of the Los Angeles Harbor, and is at risk in the seismically active Southern California region, particularly because it straddles the Palos Verdes fault zone. A combination of linear and non‐linear system identification techniques is employed to obtain a complete reduced‐order, multi‐input–multi‐output (MIMO) dynamic model of the Vincent Thomas Bridge based on the dynamic response of the structure to the 1987 Whittier and 1994 Northridge earthquakes.

Starting with the available acceleration measurements (which consists of 15 accelerometers on the bridge structure and 10 accelerometers at various locations on its base), an efficient least‐squares‐based time‐domain identification procedure is applied to the data set to develop a reduced‐order, equivalent linear, multi‐degree‐of‐freedom model. Although not the main focus of this study, the linear system identification method is also combined with a non‐parametric identification technique, to generate a reduced‐order non‐linear mathematical model suitable for use in subsequent studies to predict, with good fidelity, the total response of the bridge under arbitrary dynamic environments.

Results of this study yield measurements of the equivalent linear modal properties (frequencies, mode shapes and non‐proportional damping) as well as quantitative measures of the extent and nature of non‐linear interaction forces arising from strong ground shaking. It is shown that, for the particular subset of observations used in the identification procedure, the apparent non‐linearities in the system restoring forces are quite significant, and they contribute substantially to the improved fidelity of the model. Also shown is the potential of the identification technique under discussion to detect slight changes in the structure's influence coefficients, which may be indicators of damage and degradation in the structure being monitored. Difficulties associated with accurately estimating damping for lightly damped long‐span structures from their earthquake response are discussed. The technical issues raised in this paper indicate the need for added spatial resolution in sensor instrumentation to obtain identified mathematical models of structural systems with the broadest range of validity. Copyright © 2003 John Wiley & Sons, Ltd.
Flammability of polystyrene layered silicate (clay) nanocomposites: Carbonaceous char formation
Authors: Morgan Alexander B. , Harris Richard H. , Kashiwagi Takashi , Chyall Leonard J. , Gilman Jeffrey W.
Published: January 2003

Polymer layered‐silicate (clay) nanocomposites have not only the unique advantage of reduced flammability, but also improved mechanical properties. This is a key advantage over many flame retardants, which reduce flammability but also reduce the mechanical properties of the polymer. In our efforts to further understand the mechanism of flame retardancy with polymer‐clay nanocomposites, we investigated the effect of the clay, the loading level and polymer melt viscosity on the flammability of polystyrene‐clay nanocomposites. The nanoscale dispersion of the clay in the polymer was analysed by wide‐angle X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Cone calorimetry and gasification studies were used to evaluate the flammability of these nanocomposites. There were major reductions in peak heat release rates (HRRs), and increased carbonaceous char formation, for these nanocomposites. It was determined that while the viscosity of the PS nanocomposite played a role in lowering the peak HRR, the clay loading level had the largest effect on peak HRR. Finally, it was found that clay catalysed carbonaceous char formation, and the reinforcement of the char by the clay was responsible for the lowered flammability of these nanocomposites. Published in 2002 by John Wiley & Sons, Ltd.
Short communication: Carbon nanotubes as flame retardants for polymers
Authors: Beyer Günter
Published: January 2003

Flame retardant nanocomposites were synthesized by melt‐blending ethylene‐vinyl acetate copolymer (EVA) with multi wall carbon nanotubes. Fire property measurements by cone calorimeter revealed that the incorporation of multi wall carbon nanotubes into EVA significantly reduced the peak heat release rates compared with the virgin EVA. Peak heat release rates of EVA with multi‐wall carbon nanotubes were slightly improved compared with EVA nanocomposites based on modified layered silicates. Char formation is the main important factor for these improvements. There was also a synergistic effect by the combination of carbon nanotubes and organoclays resulting in an overall more perfect closed surface with improved heat release values. Copyright © 2002 John Wiley & Sons, Ltd.
Update for combustion properties of wood components
Authors: Dietenberger Mark
Published: January 2003

The combustion properties of various biomass and wood materials from various references and from our laboratory were reanalysed. The net heat of combustion for cellulosic materials was found to be 13.23 kJ/g times the ratio of stoichiometric oxygen mass to fuel mass, ro, regardless of the material composition. Bomb calorimeter data for original, charred and volatilized material components provide gross heating values, while elemental analysis of the materials for carbon, hydrogen, oxygen and ash provide direct evaluation for ro. We corrected these data as provided in various references by converting gross heating values to lower heating values and converting elemental compositions, char fractions and ro to a moisture‐free and ash‐free basis. Some existing formulae were found to disagree with data from vegetation, charred wood with high ash content, and with volatiles from cellulose treated with the fire retardant NaOH. We also established various functional correlations of ro with elemental compositions, or volatization fractions of untreated and treated materials, or material fractions for cellulose, lignin and extractives, or volatile fractions for tar, combustible gases and inert gases in pure nitrogen carrier gas. An interesting predictive result provides nearly constant heat of combustion while the volatile tar fraction is decreasing and combustible and inert gas fractions are increasing with time during the charring of Douglas‐fir wood. Published in 2002 John Wiley & Sons, Ltd.
Investigation and correlation of manikin and bench‐scale fire testing of clothing systems
Authors: Lee Calvin , Kim Il Young , Wood Alycia
Published: January 2003

The US Army currently has five flame/thermal protective clothing systems to provide protection for soldiers against fire hazards. The protective performance of these clothing systems against burn injuries was investigated in full‐scale manikin tests. The protective performance of fabric layers of these clothing systems was also examined in bench‐scale tests. In addition, air gap thicknesses and distributions of the five clothing systems were determined by using a three‐dimensional laser scanning technique. In this paper, test conditions of the manikin and bench‐scale tests are compared, and the test results are correlated in light of the air gap measurements. The behavior of individual sensors on the manikin with similar test conditions to those of bench‐scale tests are compared with the bench‐scale tests. It is found that if the air gap distribution of a clothing system is known, bench‐scale tests could provide useful information for full‐scale performance, especially bench‐scale tests with zero air gap measurements. Published in 2002 by John Wiley & Sons, Ltd.