bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite element‐based model order reduction of electromagnetic devices
Authors: Zhu Y. , Cangellaris A. C.
Published: October 2002

In this paper an efficient algorithm is presented for the development of compact and passive macro‐models of electromagnetic devices through the systematic reduction of the order of discrete models for these devices obtained through the use of finite elements. The proposed methodology is founded on a new finite element formulation that casts Maxwell's curl equations in a state‐space form. Such state‐space representations are very compatible with a class of robust model order reduction techniques based on Krylov subspaces. However, the advantage of this compatibility appears to be hindered by the fact that the state matrix of the discretized Maxwellian system is of dimension almost twice that obtained from the finite element approximation of the electromagnetic vector wave equation. It is shown in this paper that the apparent penalty in both memory and computation efficiency can be avoided by a proper selection of the finite element expansion functions used for the discretization of the electromagnetic fields. More specifically, it is shown that the proper selection of expansion functions renders the state‐space form of the Maxwellian system equivalent to the discrete problem obtained from the approximation of the vector wave equation using tangentially continuous vector finite elements. This equivalence is then used to effect Krylov‐based model order reduction directly from the finite element approximation of the vector wave equation. In particular, a passive model order reduction algorithm is used for this purpose. The proposed reduced order macro‐modelling algorithm is demonstrated through its application to a variety of microwave passive components. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of interdigital capacitor and quasi‐lumped miniaturized filters using iterative method
Authors: Gharsallah A. , Gharbi A. , Desclos L. , Baudrand H.
Published: October 2002

This paper presents the application of an iterative method for fast computation of microstrip interdigital capacitor (IDC) and a quasi‐lumped miniaturized filter. The use of a 2D‐FFT algorithm allows simplifications in the calculation process leading to accurate results obtained 20 times faster than in the conventional method cases. Copyright © 2002 John Wiley & Sons, Ltd.
Single‐chain variable fragment antibodies against the neural adhesion molecule CHL1 (close homolog of L1) enhance neurite outgrowth
Authors: Dong Ling , Chen Suzhen , Richter Melanie , Schachner Melitta
Published: October 2002

The neural cell adhesion molecule CHL1 (close homolog of L1) plays important roles in neurite outgrowth and neuronal survival in vitro. Reproducible and functionally active CHL1 antibodies are critical for a better understanding of the functional properties of CHL1 in vitro and in vivo. We have isolated human single‐chain variable fragment (scFv) antibodies against mouse CHL1 from a human synthetic phage display library. To improve the binding activity of such antibodies, a clone (C12) was selected for affinity maturation by combined random mutagenesis of the VH gene and site‐directed cassette mutagenesis to introduce random mutations in the complementarity determining region 3 (CDR3) of the VL gene. From the mutant phage display library, we selected a clone (6C2) that gave the strongest signal as determined by ELISA. The dissociation constant of 6C2 (Kd 2.28 × 10−8 M) was increased approximately 85‐fold compared with the wild‐type clone C12 (Kd 1.93 × 10−6 M). 6C2 detected CHL1 by Western blot analysis in mouse brain homogenates and detected CHL1 in CHL1‐transfected cells by immunofluorescence. Furthermore, the wild‐type and affinity‐matured antibodies promoted neurite outgrowth of hippocampal and cerebellar neurons in vitro. Our results suggest that the affinity‐matured CHL1 scFv antibody will serve a range of applications in vitro and in vivo. © 2002 Wiley‐Liss, Inc.
Chronological changes in pyridoxine‐5′‐phosphate oxidase immunoreactivity in the seizure‐sensitive gerbil hippocampus
Authors: Kang Tae‐Cheon , Park Seung‐Kook , Hwang In Koo , An Sung‐Jin , Bahn Jae Hoon , Kim A. Yeon , Choi Soo Young , Kwon Oh‐Shin , Baek Nam‐In , Lee Hyeon Yong , Won Moo Ho
Published: October 2002

To identify the roles of pyridoxine‐5′‐phosphate (PNP) oxidase in epileptogenesis and the recovery mechanisms in spontaneous seizure, a chronological and comparative analysis of PNP oxidase expression was conducted. PNP oxidase immunoreactivity in a preseizure group of seizure‐sensitive (SS) gerbils was detected more strongly than that in a seizure‐resistant (SR) group. The density of PNP oxidase immunoreactivity in a 30 min postictal group was significantly lower than that in a preseizure group. In a 12 hr postictal group, PNP oxidase immunodensity had recovered to a preseizure level. The overexpression of PNP oxidase in the hippocampus of preseizure SS gerbils suggests that PNP or pyridoxal 5′‐phosphate plays an important role in the modulation of glutamic acid decarboxylase activity and γ‐aminobutyric acid reuptake as mediated by membrane transporter via neurons. In addition, this change in the PNP oxidase immunoreactivity following seizure may be a compensatory response designed to reduce epileptic activity in this animal. © 2002 Wiley‐Liss, Inc.
A daily diary study of affective responses to psychological contract breach and exceeded promises
Authors: Conway Neil , Briner Rob B.
Published: October 2002

The psychological contract has been viewed as an explanatory framework for understanding the employment relationship, and is regarded by some researchers as central in understanding employee attitudes and behavior. Despite the importance ascribed to the psychological contract, it remains theoretically underdeveloped and has received limited empirical attention. This study takes a new approach to researching the psychological contract, through the use of daily diaries, and addresses a number of fundamental questions regarding its nature. Results show that both broken and exceeded promises occur regularly and in relation to virtually any aspect of work, that the importance of the promise contributes significantly to emotional reactions following broken and exceeded promises, and that the psychological contract is an important concept for understanding everyday fluctuations in emotion and daily mood. Copyright © 2002 John Wiley & Sons, Ltd.
Comparison of genuine (1851–1852 AD) and forged or reproduction Hawaiian Missionary stamps using Raman microscopy
Authors: Chaplin Tracey D. , Clark Robin J. H. , Beech David R.
Published: October 2002

The rare and valuable Hawaiian Missionary stamps from the Tapling Collection held at the British Library were analysed using Raman microscopy and shown to be printed with an ink composed of Prussian blue. Blue particles dispersed between the paper fibres of the stamps and present as optical brighteners were identified to be lazurite or the synthetic equivalent, ultramarine blue. Each cancellation or postmark, where present, is composed of carbon, vermilion, iron(III) oxide or a madder‐like organic pigment. The Raman analysis also showed that microscopic repair work on stamps can be identified. The genuine stamps were compared with 13 forged Hawaiian Missionary stamps, printed in the early 20th century, and with a set of eight reproduction items printed in 1985, from the Royal Philatelic Society London. Raman analysis of the forged stamps showed that the ink used is different from that of the genuine stamps, being a mixture of Prussian blue and ultramarine blue, or an organic blue pigment. Analysis of the 1985 reproduction stamps showed that they were printed with modern phthalocyanine blue ink, on paper coated with a yellow organic pigment to simulate aged paper. This analysis provides an invaluable and non‐destructive method for assisting in drawing a distinction between fraudulent or reproduction material and the genuine article. Copyright © 2002 John Wiley & Sons, Ltd.
What is observed in single molecule SERS, and why?
Authors: Otto Andreas
Published: October 2002

Proposed single molecule surface‐enhanced Raman scattering (SM‐SERS) mechanisms are discussed and problems in SM‐SERS of biological molecules are pointed out. It is unlikely that the single molecule signals can be explained exclusively by electromagnetic (EM) ‘hot spots’ in fractal structures or in narrow gaps. Care must be taken to recognize and avoid the signal of sp2‐carbon contamination, the origins of which are chemical impurities and/or photophysical reactions of the chosen adsorbate. As already pointed out by Käll and co‐workers, relatively large globular proteins fit only in wider gaps, and therefore the EM enhancement is several orders smaller than often reported enhancements in SM‐SERS. SM‐SERS of haemoglobin probably shows signals from the Fe‐porphyrin constituent among other unknown signals. It cannot be excluded that the haemoglobin is denatured and the haem group is situated in a smaller gap. Copyright © 2002 John Wiley & Sons, Ltd.
A study of the quality factors affecting the short‐term decomposition of field vegetable residues
Authors: Rahn C R , Lillywhite R D
Published: October 2002

Experiments were carried out to characterise the composition and decomposition of 13 vegetable crop residues. There was a considerable range of composition, with 55% of the dry matter being water‐soluble in onion compared with only 15% in wheat. The range of carbon/nitrogen ratio in the vegetable crops was narrow, between 9 and 24, compared with a C/N ratio of 58 in wheat. The decomposition of the residues could be described by the single‐exponential equationY = a + be−k(t − d), whereYis the proportion of residue remaining at any thermal time day degrees above 0 °C,ais the proportion of residue remaining at the end of the experiment,bis the corresponding proportion of the degradable fraction,kis the rate constant for the decomposition process anddis a delay factor (in units of thermal time) which delays the start of the decomposition process.Y,aandbare all expressed as percentages on a weight basis and, by definition,a + bmust equal 100 att  = 0. The value ofdis assumed to equal zero for all residues except those from leafy brassicas, for which it was set at 100. The half‐life of crop residue decomposition ranged from 145 day deg for onion to over 1400 day deg for wheat. The decomposition rate constant (k) was related to the C and N contents (r  = 0.84,p  = 0.001), and theaparameter to the crop's lignin content (r  = 0.74,p  = 0.004).

© 2001 Society of Chemical Industry
Effect of lipid oxidation and frozen storage on muscle proteins of Atlantic mackerel (Scomber scombrus)
Authors: Saeed Suhur , Howell Nazlin K
Published: October 2002

The effect of storage on the lipids and proteins in Atlantic mackerel stored for up to 24 months at −20 and −30 °C was studied. Traditional methods including the peroxide value, thiobarbituric acid‐reactive substances (TBARS) and a reverse phase HPLC method were used to determine the primary and secondary lipid oxidation products. All tests showed an increase in lipid oxidation products with storage time and at a higher storage temperature of −20 °C compared with samples stored at −30 °C. Antioxidants had a significant effect (P < 0.01) on the inhibition of lipid oxidation, as shown by the reduction in peroxide value and hydroxides, and malondialdehyde formation. Similarly, deterioration of protein structure and functionality in mackerel stored for 3, 6, 12 and 24 months was greater at −20 than −30 °C. ATPase activity in the myosin extract of Atlantic mackerel showed a significant decrease (P < 0.01) with progressive frozen storage. Protein solubility in high salt concentration (0.6 M NaCl) decreased (P < 0.01) during storage at both −20 and −30 °C but was greater at −20 °C. Interestingly, antioxidants BHT, vitamin C and vitamin E protected the proteins against complete loss of ATPase activity and protein solubility to a significant level (P < 0.01) for up to 1 year at −20 °C compared with samples stored without antioxidants. This study confirms the deleterious effect of lipid oxidation products on protein structure and function in frozen fatty fish.

© 2002 Society of Chemical Industry
The foaming properties of proteins isolated from barley
Authors: Kapp Gregory R , Bamforth Charles W
Published: October 2002

Albumin and hordein protein fractions have been isolated from barley by extraction with salt and aqueous ethanol respectively. Both produce stable foams as assessed by a shaking procedure, and in each case foaming was enhanced by denaturation of the proteins. Foam power was increased rather more for albumin than for hordein, especially by heat, and this was accompanied by an increase in hydrophobic character as assessed by the fluorochrome 1‐anilino‐8‐napthalenesulphonic acid. Iso‐α‐acids and reduced iso‐α‐acids increased the foam stability of both albumin and hordein, with there being a proportionately greater increase for the undenatured proteins. Albumin is resistant to hydrolysis by the cysteine proteinases ficin and papain but is hydrolysed by the serine proteinase trypsin. In the latter instance, hydrolysis is accompanied by a loss of foam stability. By contrast, hordein is resistant to digestion by trypsin but is susceptible to the action of ficin and papain. In these instances, limited proteolysis leads to a substantial enhancement of foam stability from hordein, though prolonged proteolysis is detrimental. Proteinase A from yeast hydrolyses both protein classes and lowers their ability to give stable foams. It is concluded that polypeptides derived from both albumin and hordein could make a contribution to the foam potential of beer.

© 2002 Society of Chemical Industry
Non‐destructive texture analysis of farmed Atlantic salmon using visual/near‐infrared reflectance spectroscopy
Authors: Isaksson Tomas , Swensen Lars P , Taylor Richard G , Fjæra Svein O , Skjervold Per O
Published: October 2002

Fillets of farmed Atlantic salmon were assessed by visual/near‐infrared (VIS/NIR) reflectance spectroscopy, Kramer shear force measurement and texture profile analysis (TPA). Comparison of the Kramer measurements between pairs of subsamples gave correlation coefficients of 0.85 for pre‐rigor (2 h after slaughter), 0.78 for post‐rigor (6 days after slaughter) and 0.97 for pre‐ and post‐rigor combined. TPA gave non‐significant correlations between subsamples. VIS/NIR fibre optic probe measurements gave cross‐validated correlation coefficients for prediction of Kramer shear force of 0.76 for pre‐rigor, 0.68 for post‐rigor and 0.94 for pre‐ and post‐rigor combined. Classification using linear discriminant analysis of the VIS/NIR measurements gave up to 79% correct classification into three categories: low Kramer shear force (2.13 × 10−2–4.41 × 10−2 J g−1), medium Kramer shear force (4.41 × 10−2–6.37 × 10−2 J g−1) and high Kramer shear force (6.37 × 10−2–7.90 × 10−2 J g−1). Using these class limits, no low‐Kramer‐shear‐force sample was misclassified as a high‐Kramer‐shear‐force sample, and vice versa. It can be concluded that non‐destructive VIS/NIR fibre optic probe measurement gives fair predictions of Kramer shear force. Its most useful application in salmon production plants may be to classify fillets into broad classes according to texture before further processing or sale.

© 2001 Society of Chemical Industry
The role of the mineral component in surface stabilization processes of a disturbed desert sandy surface
Authors: Yair A. , Verrecchia E.
Published: October 2002

The stabilization of sandy and loamy surfaces in semiarid and arid areas by topsoil crusts protecting the soil against wind or runoff erosion is well known. Destruction of such crusts, often by overgrazing, can enhance erosion and desertification. Crust recovery does not depend purely on biotic components of the crust and vegetation. Mineral components in the initial surface stabilization process are often overlooked. The present study focuses on the relative importance of the biotic and mineral components in the process of topsoil crust recovery in a sandy desert area located in the northwestern Negev Desert of Israel. Observations of the initial crust and of the disturbed surface, in the field and under the scanning electron microscope, showed that the mineral components of the crust recovered more quickly than its biotic elements. The implications for the rehabilitation of the disturbed ecosystem are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Oral bacteria in multi‐species biofilms can be killed by red light in the presence of toluidine blue
Authors: O'Neill John F. , Hope Christopher K. , Wilson Michael
Published: October 2002

Background and Objectives

Oral bacteria can be killed by light in the presence of a suitable photosensitizer, and this could be used in the treatment of oral infections. In these diseases, however, bacteria are present as biofilms, which are refractive to antimicrobial agents. The purpose of this study was to determine whether oral bacterial biofilms were susceptible to lethal photosensitization.

Study Design/Materials and Methods

Multi‐species biofilms of oral bacteria were irradiated with light from a helium/neon laser in the presence of toluidine blue O (TBO) and the survivors enumerated. Controls examining the effects of light and TBO alone were also included. The biofilms were also examined by confocal scanning laser microscopy (CSLM).

Results

CSLM revealed that the biofilms had structures similar to those of dental plaque. Although, the biofilms consisted of extremely large numbers of bacteria (∼9 × 109), 97.4% were killed following irradiation with 31.5 J of laser light in the presence of 25 μg/ml TBO.

Conclusions

Substantial numbers of oral bacteria in multi‐species biofilms can be killed by light in the presence of TBO. This may be useful in the treatment of dental plaque‐related diseases. Lasers Surg. Med. 31:86–90, 2002. © 2002 Wiley‐Liss, Inc.
The role of irreversibilities in competitive interaction: behavioral considerations from organization theory
Authors: Chen Ming‐Jer , Venkataraman S. , Sloan Black Sylvia , MacMillan Ian C.
Published: October 2002

Using behavioral insights from organization theory, this paper examines the significance of the irreversibility of an attacker's competitive move in interfirm competitive interaction. The study suggested that irreversibility is a multifaceted construct that is broadly composed of two dimensions: internal commitment (which is based on organizational inertia) and public commitment (which is based on the degree of publicity or public exposure received). It hypothesized that these two irreversibilities would have opposite effects on competitors' responses. The hypotheses were tested with data on competitive moves and countermoves exchanged by major US airlines. As predicted, the results reveal that internal commitment tended to reduce the likelihood of response, increased the response delay, and decreased the probability that the initial move will be matched; on the contrary, the impacts of public commitment were exactly the opposite. Copyright © 2002 John Wiley & Sons, Ltd.
Recent advances in the discovery of flavonoids and analogs with high‐affinity binding to P‐glycoprotein responsible for cancer cell multidrug resistance
Authors: Boumendjel Ahcène , Di Pietro Attilio , Dumontet Charles , Barron Denis
Published: October 2002

P‐glycoprotein (P‐gp) is a plasma membrane glycoprotein that confers multidrug resistance on cells by virtue of its ability to exclude cytotoxic drugs in an ATP‐dependent manner. The most commonly considered hypothesis is that P‐gp acts as an ATP‐driven drug‐export pump, the mechanism of which is not understood in detail. Therefore, a tremendous effort is being made to find out modulator molecules to inhibit P‐gp. We have been developing flavonoid derivatives as a new class of promising modulators using a new in vitro rational‐screening assay based on measurements of the binding‐affinity toward the C‐terminal nucleotide‐binding domain (NBD2) of P‐gp. This review is focused on our results obtained with a variety of flavonoids. Structure–activity relationships of flavonoids as potential MDR modulators are reported. © 2002 Wiley Periodicals, Inc. Med Res Rev, 22, No. 5, 512–529, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10015
Analysis and design of an adaptive polynomial predistorter with the loop delay estimator
Authors: Kim Donghyun , Lee Sangseol
Published: October 2002

Most adaptive linearization circuits for the nonlinear amplifier have a feedback loop that returns the output signal of the amplifier to the linearizer. The loop delay of the linearizer must be controlled precisely so that the convergence of the linearizer should be assured. In this Letter a delay control circuit is presented. It is a delay lock loop (DLL) with a modified early–late gate and can be easily applied to a DSP implementation. The proposed DLL circuit is applied to an adaptive linearizer with the use of a polynomial predistorter, and the simulation for a 16‐QAM signal is performed. The simulation results show that the proposed DLL eliminates the delay between the reference input signal and the delayed feedback signal of the linearizing circuit perfectly, so that the predistorter polynomial coefficients converge into the optimum value and a high degree of linearization is achieved. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 117–121, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10391
Path‐loss model of the 60‐GHz indoor radio channel
Authors: Fryziel M. , Loyez C. , Clavier L. , Rolland N. , Rolland P. A.
Published: October 2002

This work deals with path‐loss modeling of the indoor 60‐GHz multipath channel. Measurement campaigns show that radio waves are confined inside rooms and allow fadings to be investigated. To identify the distributions describing both small‐ and large‐scale fadings, goodness‐of‐fit tests are used and show they can be modeled by a log‐normal distribution. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 158–162, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10402
Wideband measurements for Multimedia Wireless System radio links
Authors: García Sánchez Manuel , Vázquez Alejos Ana , Cuiñas Iñigo
Published: October 2002

The results of a measurement campaign conducted to determine the wideband behavior of the radio channel assigned to Multimedia Wireless Systems (MWS) are described in this Letter. It has been found that small multipath components are present in the impulsive response of radio channels operating at 40 GHz with 80‐MHz bandwidths. Multipath and delay spread are limited by the spatial filtering of directive antennas used in MWS and the low reflection coefficient of building materials at these frequencies. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 224–227, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10423
The block‐Toeplitz‐matrix based CG‐FFT algorithm with an inexact sparse preconditioner for analysis of microstrip circuits
Authors: Chen R. S. , Yung Edward K. N. , Tsang K. F. , Mo L.
Published: October 2002

In this Letter, the inexact preconditioned conjugate‐gradient (CG) algorithm with inner–outer iteration and the block‐Toeplitz‐matrix–based fast–Fourier‐ transform (FFT) technique are applied to dense matrix equations from the mixed potential integral equation (MPIE) to enhance the computational efficiency of the CG‐FFT algorithm. Numerical calculations show that the preconditioned CG‐FFT algorithm with this preconditioner converges nearly 30 times as fast as the conventional one for the analysis of microstrip. Some typical microstrip discontinuities are analyzed and the good results demonstrate the validity of the proposed algorithm. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 347–351, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10459
Accurate model of E‐plane waveguide junction with loaded rectangular coupling cavity
Authors: Chumachenko Vitaliy P.
Published: October 2002

An accurate model of a loaded E‐plane right‐angle bend in the rectangular waveguide is presented. The development is obtained with the use of the domain‐product technique, with the edge effects taken into account. The approach can be also applied to the T junction and the cross junction. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 351–354, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10460
Experimental estimation of wide‐band radio channel parameters with the use of a spectrum analyzer and the Hilbert transform
Authors: Páez Ingrid , Loredo Susana , Valle Luis , Torres Rafael P.
Published: October 2002

In this Letter a method is presented for measuring the main parameters required to estimate the capacity of the radio channel for wide‐band communications as the root‐mean‐square time delay and the coherence bandwidth. This method is based on the possibility of estimating the power‐delay profile from the knowledge of only the module of the transfer function of the channel in conjunction with the Hilbert transform. The major advantages of the method are first, the possibility to experimentally characterize the wide‐band channel performance by employing widely used and low‐cost instrumentation, and second, the possibility to extend the technique to outdoor radio channels. The error associated with the approximated method is quantified, so that it can be used from an engineering point of view in the planning and development of wide‐band wireless communications systems. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 393–397, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10472
Pulmonary ventilation and perfusion scanning using hyperpolarized helium‐3 MRI and arterial spin tagging in healthy normal subjects and in pulmonary embolism and orthotopic lung transplant patients
Authors: Lipson David A. , Roberts David A. , Hansen‐Flaschen John , Gentile Thomas R. , Jones Gordon , Thompson Alan , Dimitrov Ivan E. , Palevsky Harold I. , Leigh John S. , Schnall Mitchell , Rizi Rahim R.
Published: October 2002

Conventional nuclear ventilation/perfusion (V/Q) scanning is limited in spatial resolution and requires exposure to radioactivity. The acquisition of pulmonary V/Q images using MRI overcomes these difficulties. When inhaled, hyperpolarized helium‐3 (3He) permits MRI of gas distribution. Magnetic labeling of blood (arterial spin‐tagging (AST)) provides images of pulmonary perfusion. Three normal subjects, two patients who had undergone single lung transplantation for emphysema, and one subject with pulmonary embolism (PE), were imaged. 3He distribution and blood perfusion appeared uniform in the normal subjects and throughout the lung allografts. Gas distribution and perfusion in the emphysematous lungs were non‐uniform and paralleled radiographic abnormalities. AST imaging alone revealed a lower‐lobe wedge‐shaped perfusion defect in the patient with PE that corresponded to computed tomography (CT) imaging. Hyperpolarized 3He gas is demonstrated to provide ventilation images of the lung. Blood perfusion information may be obtained during the same examination using the AST technique. The sequential application of these imaging methods provides a novel tool for studying V/Q relationships. Magn Reson Med 47:1073–1076, 2002. © 2002 Wiley‐Liss, Inc.
Neuromuscular fatigue and aging: Central and peripheral factors
Authors: Allman Brian L. , Rice Charles L.
Published: October 2002

A limited number of studies have investigated the effect of old age on neuromuscular fatigue, yet a variety of protocols have been used to compare the fatigability of old and young humans. These include voluntary isometric and isokinetic contraction protocols at maximal and submaximal intensities, and electrical stimulation protocols of continuous or intermittent stimulation at a variety of stimulation frequencies. The results of these studies are summarized in this review. Although it seems reasonable to suggest that age‐related changes in muscle morphology and motor unit remodeling, as well as the associated loss of strength and slowed contractile properties, may improve the resistance to neuromuscular fatigue in old humans, the collective results suggest that it is not possible to make this generalization. In fact, it cannot be generalized that the muscles of old humans are either more or less fatigable than young adults because the extent of the difference in fatigability relies strongly on the fatigue task performed (task‐dependency). Age‐related changes that occur within the neuromuscular system may result in some candidate fatigue sites increasing or decreasing their susceptibility to failure under specific task conditions. These candidate fatigue sites include central drive, muscle membrane excitability, excitation–contraction coupling mechanisms, and metabolic capacities. The effect of old age on these various central and peripheral sites is discussed with respect to their relative contribution during different fatigue tasks. Moreover, the impact of the possible confounding effects of subject habituation, physical activity status, and sex on the fatigability comparison is addressed. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25: 000–000
Influence of insulin‐like growth factor‐I (IGF‐I) on nerve autografts and tissue‐engineered nerve grafts
Authors: Fansa Hisham , Schneider Wolfgang , Wolf Gerald , Keilhoff Gerburg
Published: October 2002

To overcome the problems of limited donor nerves for nerve reconstruction, we established nerve grafts made from cultured Schwann cells and basal lamina from acellular muscle and used them to bridge a 2‐cm defect of the rat sciatic nerve. Due to their basal lamina and to viable Schwann cells, these grafts allow regeneration that is comparable to autologous nerve grafts. In order to enhance regeneration, insulin‐like growth factor (IGF‐I) was locally applied via osmotic pumps. Autologous nerve grafts with and without IGF‐I served as controls. Muscle weight ratio was significantly increased in the autograft group treated with IGF‐I compared to the group with no treatment; no effect was evident in the tissue‐engineered grafts. Autografts with IGF‐I application revealed a significantly increased axon count and an improved g‐ratio as indicator for “maturity” of axons compared to autografts without IGF‐I. IGF‐I application to the engineered grafts resulted in a decreased axon count compared to grafts without IGF‐I. The g‐ratio, however, revealed no significant difference between the groups. Local administration of IGF‐I improves axonal regeneration in regular nerve grafts, but not in tissue‐engineered grafts. Seemingly, in these grafts the interactive feedback mechanisms of neuron, glial cell, and extracellular matrix are not established, and IGF‐I cannot exert its action as a pleiotrophic signal. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 87‐93, 2002
Warranty reserves for nonstationary sales processes
Authors: Ja Shau‐Shiang , Kulkarni Vidyadhar G. , Mitra Amitava , Patankar Jayprakash G.
Published: October 2002

Estimation of warranty costs, in the event of product failure within the warranty period, is of importance to the manufacturer. Costs associated with replacement or repair of the product are usually drawn from a warranty reserve fund created by the manufacturer. Considering a stochastic sales process, first and second moments (and thereby the variance) are derived for the manufacturer's total discounted warranty cost of a single sale for single‐component items under four different warranty policies from a manufacturer's point of view. These servicing strategies represent a renewable free‐replacement, nonrenewable free‐replacement, renewable pro‐rata, and a nonrenewable minimal‐repair warranty plans. The results are extended to determine the mean and variance of total discounted warranty costs for the total sales over the life cycle of the product. Furthermore, using a normal approximation, warranty reserves necessary for a certain protection level, so that reserves are not completely depleted, are found. Results and their managerial implications are studied through an extensive example. © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 499–513, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10023
A quadtree data structure for the coupled finite‐element/element‐free Galerkin method
Authors: Karutz H. , Kraetzig W. B.
Published: October 2002

In the present paper, we derive an efficient data structure for the organization of the nodes in the coupled finite element/element‐free Galerkin method. With respect to its implementation, we compare various approaches of recursive spatial discretizations that facilitate most flexible handling of the nodes. The goal of the paper is to refine the implementation issues of the data structure which is fundamental to the element‐free Galerkin method and thus to speed‐up this otherwise computationally rather expensive meshfree method. Copyright © 2001 John Wiley & Sons, Ltd.
An energy and momentum conserving method for rigid–flexible body dynamics
Authors: Puso Michael Anthony
Published: October 2002

In this work, an energy and momentum conserving method is developed for doing coupled flexible and rigid body dynamics. The main focus is on the bilateral connection of flexible finite elements to rigid bodies. The coupling of rigid bodies at joints is also introduced. Existing conserving algorithms for individual (un‐coupled) rigid and flexible bodies are exploited and modified for the coupled system. By using the appropriate rigid body rotational update and generalized force definitions, the resulting rigid–flexible and rigid–rigid systems are unconditionally stable and conserve linear and angular momentum. The conservation and stability properties are demonstrated in numerical simulation. Published in 2001 by John Wiley & Sons, Ltd.
A point interpolation meshless method based on radial basis functions
Authors: Wang J. G. , Liu G. R.
Published: October 2002

A point interpolation meshless method is proposed based on combining radial and polynomial basis functions. Involvement of radial basis functions overcomes possible singularity associated with the meshless methods based on only the polynomial basis. This non‐singularity is useful in constructing well‐performed shape functions. Furthermore, the interpolation function obtained passes through all scattered points in an influence domain and thus shape functions are of delta function property. This makes the implementation of essential boundary conditions much easier than the meshless methods based on the moving least‐squares approximation. In addition, the partial derivatives of shape functions are easily obtained, thus improving computational efficiency. Examples on curve/surface fittings and solid mechanics problems show that the accuracy and convergence rate of the present method is high. Copyright © 2002 John Wiley & Sons, Ltd.
An orthotropic damage model for masonry structures
Authors: Berto Luisa , Saetta Anna , Scotta Roberto , Vitaliani Renato
Published: October 2002

An orthotropic damage model specifically developed for the analysis of brittle masonry subjected to in‐plane loading is described. Four independent internal damage parameters, one in compression and one in tension for each of the two natural axes of the masonry, are defined allowing the stiffness recovery at crack closure as well as the different inelastic behaviour along each natural axis to be considered. The damage field of the material is defined in terms of four equivalent stresses and results, in the space of the in‐plane effective stresses, in a double pyramid with a rectangular base where the slopes of the faces correspond to the internal friction angle of the material. The equivalent stresses also control the growth of the damage parameters. The returning path from the effective to the damaged stresses is given by multiplication by a fourth‐rank damage effect tensor, which is a function of the damage parameters and of the effective stress state. Mesh size regularization is achieved by means of an enhanced local method taking into account the finite element size. Good agreement has been found in the comparison between numerical results and experimental data both for masonry shear panels and for a large‐scale masonry holed wall. Copyright © 2002 John Wiley & Sons, Ltd.
Mature dendritic cells make clusters with T cells in the invasive margin of colorectal carcinoma
Authors: Suzuki Akitake , Masuda Akihiro , Nagata Hitoshi , Kameoka Shingo , Kikawada Yayoi , Yamakawa Mitsunori , Kasajima Takeshi
Published: October 2002

Dendritic cells (DCs) take up tumour‐specific antigen and migrate to regional lymph nodes to generate anti‐tumour immunity. Although DC infiltration within human tumour tissue has been reported, the subset distribution has not been fully investigated. This study used immunohistochemistry to investigate DC subset distribution in colorectal adenocarcinoma. DCs expressing CD83, which are considered to be mature DCs, were present mainly in the invasive margin of cancer stroma. CD83+ DCs in the invasive margin formed clusters with lymphocytes, the majority of which were CD45RO+ T cells. The number of CD4+ T cells was greater than that of CD8+ T cells in these DC–lymphocyte clusters. The elongated cytoplasmic processes of CD83+ DCs engulfed CD4+ T cells. DCs that express CD1a were located throughout tumour tissue. Although the number of CD1a+ DCs was almost the same as that of CD83+ DCs in the invasive margin of cancer stroma, CD1a+ DCs were mostly scattered and rarely formed clusters with lymphocytes. DCs that expressed both CD1a and CD83 were rare. Moreover, about 20% of lymphocytes in DC–lymphocyte clusters were positive for Ki‐67, and CD83+ DCs were attached to Ki‐67+ cells. CD83+ DCs were also present in T‐cell areas that had a distinctive structure involving the presence of B‐cell lymphoid follicles. These results suggest that in the invasive margin of the colorectal cancer stroma, mature CD83+ DCs form clusters with T cells to promote T‐cell activation for the generation of tumour‐specific immunity. Copyright © 2002 John Wiley & Sons, Ltd.
Apoptosis in B‐cell lymphomas and reactive lymphoid tissues always involves activation of caspase 3 as determined by a new in situ detection method
Authors: Dukers Danny F. , Oudejans Joost J. , Vos Wim , ten Berge Rosita L. , Meijer Chris J. L. M.
Published: October 2002

In vitro studies indicate that in lymphomas, execution of apoptosis involves activation of effector caspases. To investigate activation of effector caspases in vivo in biopsy specimens of lymphomas, a new assay was developed using antibodies against active caspase 3 and p89, a protein fragment generated by caspase‐specific cleavage of poly‐ADP ribose polymerase (PARP). Using this assay, it was found that in B‐cell lymphomas, levels of active caspase 3/p89‐positive cells correlate strongly with morphologically recognizable apoptotic cells. The number of active caspase 3/p89‐positive cells was low in follicular lymphomas and usually high in diffuse large cell lymphomas. Highest numbers were found in Burkitt lymphomas and in two biopsies of diffuse large B‐cell lymphomas (DLCLs) obtained several days after initiation of therapy. It is concluded that apoptosis in reactive lymphoid tissues and in B‐cell lymphomas always involves activation of effector caspase 3 and cleavage of one of the major effector caspase substrates, PARP‐1. Moreover, levels of effector caspase activation are constantly low in low‐grade follicular lymphomas and vary considerably in DLCL and Burkitt lymphoma. Copyright © 2002 John Wiley & Sons, Ltd.
Expression of the PDGF α‐receptor 1.5 kb transcript, OCT‐4, and c‐KIT in human normal and malignant tissues. Implications for the early diagnosis of testicular germ cell tumours and for our understanding of regulatory mechanisms
Authors: Palumbo Camilla , van Roozendaal Kees , Gillis Ad J. , van Gurp Ruud H. , de Munnik Hannie , Wolter Oosterhuis J. , van Zoelen E. Joop , Looijenga Leendert H.
Published: October 2002

Human testicular germ cell tumours of adolescents and adults (TGCTs), including their precursor lesion carcinoma in situ (CIS), show expression of a 1.5 kb alternative transcript of the platelet‐derived growth factor (PDGF) α‐receptor gene. The so‐called P2 promoter involved is located in intron 12 and its activity was found to be mutually exclusive with activity of the classical promoter (P1), which encodes the full‐length receptor. The presence of the 1.5 kb transcript could be a putative marker for the early molecular diagnosis of TGCTs. In order to validate the RT‐PCR approach, this study shows that not more than 100 transcripts are necessary to obtain positivity in the test used; moreover, samples from TGCTs or CIS‐containing tissues can be diluted many‐fold before resulting in false‐negative findings. This study also shows that within TGCTs, as in TGCT‐derived cell lines, expression of the 1.5 kb transcript is differentiation‐dependent and positively correlated with expression of the embryonic transcription factor OCT‐4/POU5F1. Furthermore, the results indicate that in some non‐TGCT cancers and cell lines the 1.5 kb transcript is also expressed, but without concomitant OCT‐4/POU5F1 expression. The 1.5 kb transcript is also present in early B cells and derived leukaemias (B‐ALL). In spite of similarities in chromosomal location, down‐regulation upon differentiation of TGCTs, and PDGF α‐receptor and c‐KIT (the stem cell factor receptor) both being a tyrosine kinase receptor, no correlation was found between activity of the P2 promoter of the PDGF α‐receptor gene and expression of c‐KIT. In conclusion, the 1.5 kb transcript of the PDGF α‐receptor is expressed in various cells and tissues, including particular blood cells. Although this may hamper the use of this transcript as a marker for malignancies in general, it does not appear to interfere with assays for the early detection of TGCTs. Copyright © 2002 John Wiley & Sons, Ltd.
Expression of glycoprotein 90K in human malignant pleural mesothelioma: correlation with patient survival
Authors: Strizzi L. , Muraro R. , Vianale G. , Natoli C. , Talone L. , Catalano A. , Mutti L. , Tassi G. , Procopio A.
Published: October 2002

The expression of the tumour‐associated glycoprotein 90K in patients with malignant pleural mesothelioma (MM) has not been described. This study used enzyme‐linked immunoassay (ELISA) to measure 90K in pleural effusions (PEs) and sera from patients with MM (n=28), lung cancer (LC) (n=14) and benign pleural disease (BPD) (n=15). Immunohistochemistry was used to investigate 90K expression in MM and LC tissue sections. The expression of 90K was further evaluated in vitro by ELISA and western blot analysis of conditioned media and cellular extracts of MM, LC and normal human mesothelial (NHM) cell cultures. Finally, the relationships between 90K expression in MM and patient age and survival were studied. The mean 90K level was significantly higher (p<0.05) in PEs of MM patients (11.0±6.6 µg/ml) than in LC (6.1±3.2 µg/ml) or BPD (6.2±5.0 µg/ml) patients. Immunohistochemistry showed a positive reaction for 90K in MM biopsy sections and positive staining limited to inflammatory infiltrates in LC sections. The level of 90K was significantly higher in cell culture media of MM than of LC or NHM (p<0.001). Bands representing proteins with molecular weight of approximately 90 kDa were detected by western blot in MM cellular extracts. An inverse correlation between PE 90K levels and MM patient age (r=−0.45; p=0.017) and a positive correlation between serum 90K levels and MM patient survival (r=0.62; p=0.006) were detected by linear regression analysis. Kaplan–Meier univariate analysis showed increased survival probability for MM patients with serum 90K level >7.3 µg/ml (log rank, p<0.05). This is the first report in MM of the expression of 90K and of its potential diagnostic and prognostic application. Copyright © 2002 John Wiley & Sons, Ltd.
Expression of trefoil peptides (TFF1, TFF2, and TFF3) in gastric carcinomas, intestinal metaplasia, and non‐neoplastic gastric tissues
Authors: Leung Wai K. , Yu Jun , Chan Francis K. L. , To Ka F. , Chan Michael W. Y. , Ebert M. P. A. , Ng Enders K. W. , Sydney Chung S. C. , Malfertheiner Peter , Sung Joseph J. Y.
Published: October 2002

Trefoil factor family (TFF) domain peptides consist of three members that play a role in intestinal mucosal defence and repair, and in tumourigenesis. The role of the three TFF members in the gastric carcinogenesis cascade remains poorly defined. This study examined seven gastric cell lines, 50 gastric cancers and their adjacent non‐cancer tissues, and tissues from 40 non‐cancer patients, in order to elucidate the chronology of TFF expression in various stages of gastric carcinogenesis. TFF expression was determined by RT‐PCR, immunohistochemistry, and western blot. Aberrant expression of TFF1, TFF2, and TFF3 was frequently detected in gastric cell lines. Specifically, TFF1 was detected in all non‐cancer patients, but was detected in only 50% of gastric cancer and 66% of adjacent normal tissues. TFF2 expression was demonstrated in 87.5% of non‐cancer patients, 34% of gastric carcinomas, and 58% of adjacent non‐cancer tissues. There was a significant correlation between TFF1 and TFF2 expression in gastric cancer and adjacent non‐cancer tissues (p<0.001). By contrast, TFF3 was detected in 25% of non‐cancer patients and showed a predilection for areas with intestinal metaplasia (p=0.005). Sixty‐two per cent of gastric cancers and 24% of neighbouring non‐cancer tissues showed TFF3 expression. Immunoreactivity against TFF3 was demonstrated in goblet cells of intestinal metaplasia and within the cytoplasm and nuclei of tumour cells. Progressive loss of TFF1 and TFF2, together with the induction of TFF3, is likely to be involved in the early stage of the multi‐step gastric carcinogenesis pathway. Copyright © 2002 John Wiley & Sons, Ltd.
Is unexplained third trimester intrauterine death of fetuses with gastroschisis caused by umbilical cord compression due to acute extra‐abdominal bowel dilatation?
Authors: Kalache Karim D. , Bierlich Anke , Hammer Hannes , Bollmann Rainer
Published: October 2002

We report on a case of gastroschisis in which sudden dilatation of extra‐abdominal bowel at 34+1 weeks was followed by an unusual umbilical flow velocity waveform (diastolic notching). The condition was associated with normal umbilical Doppler indices, brain sparing effect and a non‐reactive cardiotocograph (CTG). Findings at postnatal surgery strongly suggested severe cord compression by the herniated dilated bowel. The significance of notching in the umbilical artery waveform is discussed, as is the potential importance of this sign in the prepartum management of fetuses with gastroschisis. Copyright © 2002 John Wiley & Sons, Ltd.