bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative analysis of the volatile aroma components of pepino fruit by purge‐and‐trap and gas chromatography
Authors: Ruiz‐Beviá Francisco , Font Alicia , García Angela N , Blasco Pilar , Ruiz Juan J
Published: October 2002

A system specifically designed for the analysis of volatile organic compounds in water, called the purge‐and‐trap sample concentrator, has been set up to quantify the volatile aroma constituents of fruits. The technique shows some advantages over other conventional and new methods. The quantification of the major volatile compounds (3‐methyl‐2‐buten‐1‐ol, 3‐methyl‐3‐buten‐1‐ol and their acetates) of different pepino fruit samples has been performed using the purge‐and‐trap method. Relationships between the volatile content and the characteristics of fruits have been established.

© 2002 Society of Chemical Industry
Dynamic rheology of structural development in starch/decolourised hsian‐tsao leaf gum composite systems
Authors: Lai Lih‐Shiuh , Liao Chih‐Lun
Published: October 2002

The gelling process of decolourised hsian‐tsao leaf gum (dHG)/starch mixtures was monitored as a function of starch/gum ratio and starch type using a dynamic rheometer. It was found that the gelling process followed first‐order kinetics. At starch/gum ratios of 5:1, 4:2 and 3:3, dHG interacted with starch synergistically, resulting in a marked increase in storage modulus (G′). Both the gelling reaction rate constant and plateau G′ value as a function of starch/dHG ratio showed a maximum at a certain starch/gum ratio. These results indicated that a suitable starch/dHG ratio could facilitate the formation of a three‐dimensional network structure and the conversion of chains in the sol fraction into a gel. The maximum G′ value reached depended on the unique chemistry of each starch. Mixed systems with tapioca starch generally showed lower plateau G′ values than mixed systems with wheat or corn starch, possibly owing to the lower amylose content of tapioca starch.

© 2002 Society of Chemical Industry
Seasonal climate effects on root colour and compounds of red radish
Authors: Schreiner M , Huyskens‐Keil S , Peters P , Schonhof I , Krumbein A , Widell S
Published: October 2002

‘Nevadar’ radishes were grown throughout the year. Climate parameters (mean temperature, mean irradiation) and quality characteristics of radishes fulfilling consumer quality requirements, such as root colour, glucosinolates, monosaccharides and pectic substances, were determined. The quality characteristics strongly differed depending on the seasonal climate conditions. The seasonal dependence ranged from a slight climate influence (alkenyl glucosinolates r2 = 0.23), over a moderate climate effect (indolyl glucosinolates r2 = 0.40, glucose r2 = 0.50) up to a strongly distinctive climate influence (hue angle r2 = 0.77, chroma r2 = 0.72, fructose r2 = 0.81, pectic substances r2 = 0.99). Therefore, according to consumer‐oriented quality production of radish, the temperature and irradiation influence should be taken into account in the production process. Recommendations for quality production of radish will be the selection of bright red cultivars marked by a high photosynthetic capacity (yield > 0.80 mV) at relatively low mean irradiation intensities (50–100 µmol  m2 s−1) and lower mean temperatures (11–13 °C). Thus sufficient photochemical energy can be provided for the synthesis of quality‐determining compounds. For the production of bioactive radishes showing particularly relatively high contents of indolyl glucosinolates, cultivation should be carried out in spring and autumn. In summer cultivation, consumer preferences in taste can particularly be satisfied with the desired contents of alkenyl glucosinolates and monosaccharides.

© 2002 Society of Chemical Industry
Micellar medium effects on the hydrolysis of phenyl chloroformate in ionic, zwitterionic, nonionic, and mixed micellar solutions
Authors: Muñoz María , Rodríguez Amalia , Del Mar Graciani María , Luisa Moyá María
Published: October 2002

The spontaneous hydrolysis of phenyl chloroformate was studied in various anionic, nonionic, zwitterionic, and cationic aqueous micellar solutions, as well as in mixed anionic–nonionic micellar solutions. In all cases, an increase in the surfactant concentration results in a decrease in the reaction rate and micellar effects were quantitatively explained in terms of distribution of the substrate between water and micelles and the first‐order rate constants in the aqueous and micellar pseudophases. A comparison of the kinetic data in nonionic micellar solutions to those in anionic and zwiterionic micellar solutions makes clear that charge effects of micelles is not the only factor responsible for the variations in the reaction rate. Depletion of water in the interfacial region and its different characteristics as compared to bulk water, the presence of high ionic concentration in the Stern layer of ionic micelles, and differences in the stabilization of the initial state and the transition state by hydrophobic interactions with surfactant tails can also influence reactivity. The different deceleration of the reaction observed in the various micellar solutions studied was discussed by considering these factors. Synergism in mixed‐micellar solutions is shown through the kinetic data obtained in these media. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 445–451, 2002
Kinetics of reactions of OBrO with NO, O3, OClO, and ClO at 240–350 K
Authors: Li Zhuangjie , Jeong Gill‐Ran , Person Eric
Published: October 2002

Kinetics for the reactions of OBrO with NO, O3, OClO, and ClO at 240–350 K were investigated using the technique of discharge flow coupled with mass spectrometry. The Arrhenius expression for the OBrO reaction with NO was determined to be k1 = (2.37 ± 0.96) × 10−13 exp[(607 ± 63)/T] cm3 molecule−1 s−1. The reactions of OBrO with O3, OClO, and ClO are slow chemical processes at 240–350 K. Upper limit rate constants for the OBrO reactions with O3, OClO, and ClO at 240–350 K were estimated to be k2 < 5.0 × 10−15 cm3 molecule−1 s−1, k3 < 6.0 × 10−14 cm3 molecule−1 s−1, and k4 < 1.5 × 10−13 cm3 molecule−1 s−1, respectively. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 430–437, 2002
Permanganate oxidation of unsaturated alcohols in alkaline media
Authors: Jáky Miklós , Simon‐Trompler Edit
Published: October 2002

A study was made on permanganate oxidation of olefinic and acetylenic alcohols in aqueous alkali media. Deprotonation constants of alcohols can be calculated from the kinetic data. The rate constant of alkoxide group oxidation exceeded that of the unsaturated bond. For oxidation of the alcoholic group a mechanism based on hydride ion transfer is proposed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 561–567, 2002
Developing a framework to investigate the impact of e‐commerce on the management of internal business processes
Authors: Barnes David , Hinton Matthew , Mieczkowska Suzanne
Published: October 2002

This paper develops a theoretical framework for use in research investigating the impact of e‐commerce on the management of internal business processes. Managing the business processes that facilitate order fulfilment and delivery of goods and services supplied to customers is the prime concern of operations management. Despite the growing importance of e‐commerce to organizations of all types, e‐operations is a neglected area of study. Yet many of the problems associated with e‐commerce have centred on an inability to ‘deliver the goods’, often literally. Effective and efficient operations management is as important in e‐commerce as it is in traditional business. The framework, developed by integrating literature from the academic traditions of operations management and information systems, identifies three key issues: business process integration (the extent to which business processes for clicks and mortar e‐commerce are integrated with those for bricks and mortar), information systems integration (the extent to which intra‐ and inter‐organizational information systems are capable of communicating and sharing information with each other) and the operating context (types of customers, the e‐commerce business model and organizational factors). The framework is being used in case study‐based research that aims to describe and model current practice in organizations engaged in e‐commerce. The paper describes how the framework was applied in three financial services companies. The framework proved to be a useful basis for the research, enabling key emergent themes to be identified. However, in order to fully explain all of the research findings it was subsequently necessary to modify the framework to take account of the strategic context of each organization. The modified framework will be used as the basis of further case studies being conducted in organizations in other sectors. Copyright © 2002 John Wiley & Sons, Ltd.
Low level 809‐nm diode laser‐induced in vitro stimulation of the proliferation of human gingival fibroblasts
Authors: Kreisler Matthias , Christoffers Ann B. , Al‐Haj Haitham , Willershausen Brita , d'Hoedt Bernd
Published: October 2002

Background and Objective

The authors investigated the effects of low level laser irradiation on the proliferation rate of human gingival fibroblasts (HGF) in vitro.

Study Design/Materials and Methods

HGF were obtained from gingival connective tissue explants and cultured under standard conditions. 110 cell cultures in their logarithmic growth phase were spread on 96‐well tissue culture plates and were irradiated at energy fluences of 1.96–7.84 J/cm2. Another 110 cultures served as control. An 809‐nm semiconductor laser operated at a power output of 10 mW in the cw‐mode was used. The time of exposure varied between 75 and 300 seconds. Laser treatment was performed alternatively once, twice, and three times at a 24‐hour interval. After lasing, incubation was continued for 24 hours. The proliferation rate was determined by means of fluorescence activity of a redox indicator added to the cell culture. Proliferation was determined 24, 48, and 72 hours after irradiation and expressed in relative fluorescence units (RFU).

Results

The irradiated cells revealed a considerably higher proliferation activity. The differences were highly significant 24 hour after irradiation (Mann‐Whitney U‐test, P < 0.05) but decreased in an energy‐dependent manner after 48 and 72 hour after irradiation.

Conclusions

A cellular effect of the soft laser irradiation on HGF is evident. Its duration, however, seems to be limited. These findings might be clinically relevant, indicating that repeated treatments are necessary to achieve a positive laser effect in clinical applications. Lasers Surg. Med. 30:365–369, 2002. © 2002 Wiley‐Liss, Inc.
Hallervorden‐Spatz syndrome resembling a typical Tourette syndrome
Authors: Scarano Valentina , Pellecchia Maria Teresa , Filla Alessandro , Barone Paolo
Published: October 2002

A young man presenting with a Tourette syndrome‐like disorder that was the main clinical manifestation of Hallervorden‐Spatz syndrome is described. It is recommended that, even in the case of slow progression, HSS should be considered in the differential diagnosis of TS‐like disorders. ©2002 Movement Disorders Society
Genetic and clinical heterogeneity in paroxysmal kinesigenic dyskinesia: Evidence for a third EKD gene
Authors: Spacey Sian D. , Valente Enza‐Maria , Wali Gurusidheshwar M. , Warner Thomas T. , Jarman Paul R. , Schapira Anthony H.V. , Dixon Peter H. , Davis Mary B. , Bhatia Kailash P. , Wood Nicholas W.
Published: October 2002

Paroxysmal kinesigenic dyskinesia (PKD) is characterised by paroxysms of choreic, dystonic, ballistic, or athetoid movements. The attacks typically last seconds to minutes in duration and are induced by sudden voluntary movement. PKD loci have been identified on chromosome 16. We present the clinical and genetic details of two British and an Indian family with PKD. Linkage to the PKD loci on chromosome 16 has been excluded in one of these families, providing evidence for a third loci for PKD. Detailed clinical descriptions highlight the presence of both adolescent and infantile seizures in some of the PKD families. This study attempts to clarify the relationship of adolescent and infantile seizures to PKD and provides evidence that PKD is both genetically and clinically heterogeneous. © 2002 Movement Disorder Society
Evidence for shoulder girdle dystonia in selected patients with cervical disc prolapse
Authors: Becker Georg , Berg Daniela , Kruse Niels , Schröder Ute , Warmuth‐Metz Monika , Rieckmann Peter , Naumann Markus , Reiners Karlheinz
Published: October 2002

Some patients with cervical disc herniation suffer from persistent nuchal pain and muscle spasms after decompressive surgery despite the lack of clinical and radiological signs for actual spinal root compression. Sonographic examination of the brain in some of these patients showed increased echogenicity of the lentiform nuclei as described in patients with idiopathic dystonia. This has been linked to an altered Menkes protein level and copper metabolism. We suggest a relationship between persistent nuchal pain after adequate cervical disc surgery and dystonic movement disorders. Thirteen patients with persistent nonradicular nuchal pain after at least one cervical disc surgery and without evidence of continuing spinal root compression and 13 age‐matched controls were included. All patients had a complete neurological examination, ultrasound, and MRI scan of the brain. In addition, Menkes protein mRNA levels of leucocytes were analyzed in patients and controls. All patients with persistent nuchal pain exhibited a constant tonic unilateral shoulder elevation associated with an ipsilateral hypertrophy of the trapezius muscle. Ultrasound examination showed an increased echogenicity of the lentiform nucleus in one patient unilaterally and in 10 patients bilaterally but in none of the controls. On MRI the T2‐values of the lentiform nuclei were found to be higher in patients exhibiting a hyperechogenicity of the lentiform nuclei compared to controls (P = 0.01). In addition, Menkes protein mRNA levels were decreased in patients with cervical disc herniation (P = 0.03). Clinical, neuroimaging, and biochemical findings of this selected patient sample with chronic nuchal pain and muscle spasms after cervical disc surgery resemble alterations in patients with idiopathic cervical dystonia. This suggests a link between both disorders. A peripheral trauma to the nerve roots may precipitate dystonic movements in susceptible patients and chronic dystonic muscle contraction would account for the persistent nuchal pain. © 2002 Movement Disorder Society
Did Charles Dickens describe progressive supranuclear palsy in 1857?
Authors: Larner A.J.
Published: October 2002

A character from one of Charles Dickens's lesser known works is presented, whose attributes suggest a possible diagnosis of progressive supranuclear palsy.
Genetics of parkinsonism
Authors: Gwinn‐Hardy Katrina
Published: October 2002

Parkinson's disease (PD) was noted to have a familial component as early as 1880 (Leroux, 1880). More recently, the discovery of several genetic factors influencing parkinsonism has emphasized the importance of heredity in PD. The clinical spectrum of familial parkinsonism is wide; it includes not only PD, but also dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), essential tremor, and other disorders. In the general population, it is likely that PD results from combined genetic and environmental factors, most of which are not yet known. The discovery of causal mutations in the gene for α‐synuclein, parkin, and of genetic linkages to chromosomes 2p4, 4p5, and three loci on 1q6–8 have revolutionized PD research. This review focuses on recent progress in the Mendelian genetics of PD and those diseases in which parkinsonism is a prominent feature, and considers how these discoveries modify our beliefs regarding the etiology and pathogenesis of these disorders.
Riluzole prolongs survival time and alters nuclear inclusion formation in a transgenic mouse model of Huntington's disease
Authors: Schiefer Johannes , Landwehrmeyer G. Bernhard , Lüesse Hans‐Gerd , Sprünken Arne , Puls Christiane , Milkereit Anna , Milkereit Eva , Kosinski Christoph M.
Published: October 2002

Glutamate excitotoxicity has been suggested to contribute to the pathogenesis of Huntington's disease (HD). Riluzole is a substance with glutamate antagonistic properties that is used for neuroprotective treatment in amyotrophic lateral sclerosis and which is currently tested in clinical trials for treatment of HD. R6/2 transgenic mice, which express exon 1 of the human HD gene with an expanded CAG triplet repeat, serve as a well‐characterized mouse model for HD with progressing neurological abnormalities and limited survival. We treated R6/2 HD transgenic mice with riluzole orally beginning at a presymptomatic stage until death to investigate its potential neuroprotective effects in this mouse model and found that survival time in the riluzole group was significantly increased in comparison to placebo‐treated transgenic controls. Additionally, the progressive weight loss was delayed and significantly reduced by riluzole treatment; behavioral testing of motor coordination and spontaneous locomotor activity, however, showed no statistically significant differences. We also examined the formation of the HD characteristic neuronal intranuclear inclusions (NII) immunohistologically. At a late disease stage, striatal NII from riluzole‐treated transgenic mice showed profound changes in ubiquitination, i.e., NII were less ubiquitinated and surrounded by ubiquitinated micro‐aggregates. Staining with antibodies directed against the mutated huntingtin revealed no significant difference in this component of NII. Taken together, these data suggest that riluzole is a promising candidate for neuroprotective treatment in human HD. © 2002 Movement Disorder Society
Current trends in QSAR on NO donors and inhibitors of nitric oxide synthase (NOS)*†
Authors: Kontogiorgis Christos A. , Hadjipavlou‐Litina Dimitra
Published: October 2002

This article evaluates the quantitative structure‐activity relationships (QSAR) of nitric oxide (NO) radical donors and nitric oxide synthases (NOS) inhibitors, using the C‐QSAR program of Biobyte. Furoxans, triazines, amidoximes, tetrazoles, imidazoles and Nω−2‐nitroarylamino acid analogues were included in this survey. In nine out of seventeen cases, the clog P plays a significant part in the QSAR of the NO radical donors and of the NOS inhibition. Many of the compounds must be interacting with a hydrophobic space in a non‐specific way. In some cases molecular refractivity CMR/MR as well as sterimol parameters (B1 and L) are important. Electronic effects, with the exception of the Hammett's constant σ and the Swain–Lupton parameter F, are not found to govern the biological activity. Stereochemical and electronic features are also found to be important. Indicator variables were used after the best model was found to account for the usual structural features. © 2002 Wiley Periodicals, Inc. Med Res Rev, 22, No. 4, 385–418, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10012
The Neumann problem, cylindrical outlets and Sobolev spaces
Authors: Thäter Gudrun
Published: October 2002

The Neumann problem is crucial in mathematical physics. Nevertheless, as far as cylindrical domains are concerned there is still the open question how to construct solutions to data in usual Sobolev spaces since the standard Kondratiev theory does not apply. In this paper that unsatisfactory gap is filled and moreover, data with polynomial asymptotic behaviour are considered. As interesting special case we find solutions with bounded Dirichlet integral. Copyright © 2002 John Wiley & Sons, Ltd.
Electromagnetic scattering by a perfectly conducting obstacle in a homogeneous chiral environment: solvability and low‐frequency theory
Authors: Athanasiadis C. , Costakis G. , Stratis I. G.
Published: October 2002

The scattering of plane time‐harmonic electromagnetic waves propagating in a homogeneous isotropic chiral environment by a bounded perfectly conducting obstacle is studied. The unique solvability of the arising exterior boundary value problem is established by a boundary integral method. Integral representations of the total exterior field, as well as of the left and right electric far‐field patterns are derived. A low‐frequency theory for the approximation of the solution to the above problem, and the derivation of the far‐field patterns is also presented. Copyright © 2002 John Wiley & Sons, Ltd.
A mathematical model for a spatial predator–prey interaction
Authors: Palumbo Annunziata , Valenti Giovanna
Published: October 2002

A predator–prey model is proposed within the general scheme of extended thermodynamics. An additional equation of balance is needed to account for the flux of the number density of the predator as an independent field variable. Copyright © 2002 John Wiley & Sons, Ltd.
Compact dual‐frequency shorted rhombic microstrip antenna with a pair of slits
Authors: Lin Yi‐Fang , Kuo Chin‐Chun , Chen Hua‐Ming
Published: October 2002

By using a pair of shorting pins, the dual‐frequency operation of a single‐feed rhombic microstrip antenna with a pair of slits is presented. This shorted dual‐frequency microstrip antenna can result in a much reduced antenna size, and provide a tunable frequency ratio of ∼1.26–2.33 for the two operating frequencies by varying the inset slit length. Simulated results with the use of the software also have been conducted to study the characteristics of these antennas. Details of the proposed designs are described and discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 183–186, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10411
High‐resolution fiber Bragg grating sensor system using linear‐cavity fiber laser scheme
Authors: Peng Peng‐Chun , Tseng Hong‐Yih , Chi Sien
Published: October 2002

A high‐resolution fiber Bragg grating (FBG) sensor system using a linear‐cavity fiber laser scheme is proposed and numerically studied. The proposed sensor system can improve the sensing accuracy by using a discriminating FBG pair in conjunction with a fiber laser scheme. This FBG sensor system can resolve the temperature up to 0.0005°C theoretically and can be applied for strain sensing and temperature sensing with high precision. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 323–325, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10450
Pseudo‐isotropic and maximum‐bandwidth points for axially excited chiral sculptured thin films
Authors: Lakhtakia Akhlesh
Published: October 2002

Chiral sculptured thin films (STFs) are periodically anisotropic, and exhibit the circular Bragg phenomenon over a certain wavelength regime on axial excitation. Among the key deposition parameters for the growth of a chiral STF is the so‐called vapor incidence angle χv. Analysis based on data on the related columnar thin films (CTFs) shows that pseudo‐isotropic values of χv can exist. Similarly, a maximum‐bandwidth value of χv is also shown to be possible. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 367–371, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10464
Microstrip antennas for cellular and wireless communication systems
Authors: Słobodzian P. , Borowiec R.
Published: October 2002

The Letter describes problems related to use of microstrip antennas in cellular and wireless telecommunications systems. Because of the unique properties, microstrip technology is nowadays often used to manufacture small internal antennas for portable terminals as well as antenna arrays for base stations. It also seems to be a very promising technology for multisystem antennas, for which there is an ever‐growing demand. The Letter also presents a short overview of currently available solutions and ones under development by the authors, along with some key problems related to their design. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 380–384, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10468
In vitro and in vivo maturation of oocytes from gonadotrophin‐treated brushtail possums
Authors: Glazier Andrew M. , Mate Karen E. , Rodger John C.
Published: October 2002

The time course of nuclear maturation of oocytes was examined in brushtail possums, Trichosurus vulpecula. Oocytes were recovered from ovarian follicles > 2 mm in diameter after pregnant mares' serum gonadotrophin/porcine luteinizing hormone (PMSG/LH) treatment (in vivo matured) or 72 hr after PMSG treatment (in vitro matured). Oocytes recovered from small (< 2 mm) and large (> 2 mm) follicles were also assessed for their ability to mature in vitro. Staining with the DNA‐specific dye Hoechst 33342 was used to assess the stage of nuclear development by fluorescence microscopy. The process of nuclear maturation progressed rapidly in vivo, as oocytes collected at 20–27 hr post‐LH all had a GV, but by 28–29.5 hr post‐LH approximately a third of eggs were MII. By 30‐hr post‐LH, more than 70% of oocytes had reached MII stage and all ovulated eggs were MII. In vitro, all oocytes were at germinal vesicle stage at the start of culture. After 24 hr of culture, 67% of oocytes had progressed to metaphase I/anaphase I of meiosis. After 36 hr, 25% of oocytes had completed maturation to metaphase II, increasing to 52% after 48 hr. Maturation of oocytes after 48 hr in culture was unaffected by the presence or absence of granulosa cells, PMSG or LH/porcine follicle stimulating hormone (FSH). More oocytes from large follicles (55%) completed maturation by 48 hr than from small follicles (15%). The potential of oocytes to mature after 48 hr in culture was dependent on the follicle harvested having reaching a critical diameter of 1.5 mm. Mol. Reprod. Dev. 62:504–512, 2002. © 2002 Wiley‐Liss, Inc.
MR tagging early after myocardial infarction in mice demonstrates contractile dysfunction in adjacent and remote regions
Authors: Epstein Frederick H. , Yang Zequan , Gilson Wesley D. , Berr Stuart S. , Kramer Christopher M. , French Brent A.
Published: October 2002

The purpose of this study was to use MR myocardial tagging to assess regional cardiac function after myocardial infarction (MI) in mice. Eight mice were imaged before and 1 day after MI. MRI included cine imaging, myocardial tagging, and contrast‐enhanced imaging. Regional percent circumferential shortening (%CS) was measured from the tagged images, and the region of hyperenhancement on the contrast‐enhanced images was used to determine the infarcted, adjacent, and remote zones. Ejection fraction (EF) fell from 59% ± 6% at baseline to 32% ± 6% after MI (P < 0.01). At baseline, %CS was 14.5% ± 3.4%. After MI, %CS was 0.7% ± 4.4% in the infarcted zone, 7.4% ± 4.4% in the adjacent zone, and 11.8% ± 4.2% in the remote zone. %CS was statistically different for all comparisons between the infarcted, adjacent, remote, and baseline groups (P < 0.01). MR tagging can detect regional differences in myocardial function post‐MI in mice. Magn Reson Med 48:399–403, 2002. © 2002 Wiley‐Liss, Inc.
Changes in CBF‐BOLD coupling detected by MRI during and after repeated transient hypercapnia in rat
Authors: Dutka Michael V. , Scanley B. Ellen , Does Mark D. , Gore John C.
Published: October 2002

The effect of hypercapnia on the cerebral metabolic rate of oxygen consumption (CMRO2) remains incompletely understood. This study examined the relationship between susceptibility (blood oxygenation level dependent (BOLD)) and perfusion‐weighted (flow‐sensitive alternating inversion recovery (FAIR)) MRI techniques both during induction of repeated transient hypercapnia (THC) and after return to normocapnia during whisker barrel functional activation. During induction of THC the FAIR signal became significantly elevated over control after 100 s of hypercapnia (P = 0.039), with a trend of increasing significance to 5 min (P = 0.000008). The FAIR signal in the activated cortex during subsequent normocapnia was significantly increased compared to pre‐THC control after each successive period of THC. The mean grouped FAIR signal increased by 81% ± 63% after one exposure (P = 0.021), by 163% ± 55% after the second exposure (P = 0.0002), and by 240% ± 54% after the third exposure (P = 0.000002). The mean grouped BOLD signal trended upward, but did not increase significantly during or after exposure 1, 2, or 3. These data demonstrate increased uncoupling of perfusion‐weighted from susceptibility imaging techniques, both in nonactivated cortex during hypercapnia, and with activation after multiple exposures to THC. These results are consistent with saturation of BOLD contrast as well as with increases in CMRO2 with stimulation after multiple exposures to THC. Magn Reson Med 48:262–270, 2002. © 2002 Wiley‐Liss, Inc.
Ventilation‐perfusion ratio of signal intensity in human lung using oxygen‐enhanced and arterial spin labeling techniques
Authors: Mai Vu M. , Liu Benjamin , Polzin Jason A. , Li Wei , Kurucay Saban , Bankier Alexander A. , Knight‐Scott Jack , Madhav Priti , Edelman Robert R. , Chen Qun
Published: October 2002

This study investigates the distribution of ventilation‐perfusion (V/Q) signal intensity (SI) ratios using oxygen‐enhanced and arterial spin labeling (ASL) techniques in the lungs of 10 healthy volunteers. Ventilation and perfusion images were simultaneously acquired using the flow‐sensitive alternating inversion recovery (FAIR) method as volunteers alternately inhaled room air and 100% oxygen. Images of the T1 distribution were calculated for five volunteers for both selective (T1f) and nonselective (T1) inversion. The average T1 was 1360 ms ± 116 ms, and the average T1f was 1012 ms ± 112 ms, yielding a difference that is statistically significant (P < 0.002). Excluding large pulmonary vessels, the average V/Q SI ratios were 0.355 ± 0.073 for the left lung and 0.371 ± 0.093 for the right lung, which are in agreement with the theoretical V/Q SI ratio. Plots of the V/Q SI ratio are similar to the logarithmic normal distribution obtained by multiple inert gas elimination techniques, with a range of ratios matching ventilation and perfusion. This MRI V/Q technique is completely noninvasive and does not involve ionized radiation. A limitation of this method is the nonsimultaneous acquisition of perfusion and ventilation data, with oxygen administered only for the ventilation data. Magn Reson Med 48:341–350, 2002. © 2002 Wiley‐Liss, Inc.
Reliability of hand‐held dynamometry in spinal muscular atrophy
Authors: Merlini Luciano , Mazzone Elena Stacy , Solari Alessandra , Morandi Lucia
Published: October 2002

We have assessed the reliability of hand‐held myometry in 33 patients with spinal muscular atrophy (SMA), testing elbow flexion, handgrip, three‐point pinch, knee flexion, knee extension, and foot dorsiflexion, and determining intraclass correlation coefficients (ICC). Interrater reliability was high for upper limbs, with an ICC of 0.92 for three‐point pinch and 0.98 for elbow flexion and grip. For lower limbs interrater reliability was good with ICC >0.85 for all measures except foot dorsiflexion. Test–retest results were excellent with ICC >0.91 in all instances. Hand‐held myometry is easily performed in SMA patients of various ages and muscle strengths, is a reliable measure of limb muscle strength, and can be used in longitudinal studies and clinical trials. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 64–70, 2002
Axonal hyperpolarization associated with acute hypokalemia: Multiple excitability measurements as indicators of the membrane potential of human axons
Authors: Kuwabara Satoshi , Kanai Kazuaki , Sung Jia‐Ying , Ogawara Kazue , Hattori Takamichi , Burke David , Bostock Hugh
Published: October 2002

Multiple nerve excitability measurements have been proposed for clinical testing of nerve function, and an important determinant of excitability is membrane potential. We report a patient with acquired hypokalemic paralysis in whom multiple excitability indices (stimulus‐response curve, strength‐duration properties, threshold electrotonus, recovery cycle) were measured during and after an acute hypokalemic attack (serum K+ level, 2.1 mEq/L and 4.5 mEq/L, respectively). During hypokalemia, there was a shift of the stimulus‐response curve to the right, a decrease in strength‐duration time constant, a “fanning‐out” of responses during threshold electrotonus, a reduction in relative refractory period, and an increase in superexcitability; all of these indicate axonal hyperpolarization, presumably due to the K+ equilibrium potential being more negative. These indices returned to normal 20 h later, associated with normalization of the serum K+ level. These results demonstrate that the changes associated with hypokalemic paralysis are not confined to muscle and that axons undergo hyperpolarization in vivo. Multiple excitability measurements can be used as a tool to identify changes in membrane potential of human axons. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 283–287, 2002
Managing waiting times of backordered demands in single‐stage (Q, r) inventory systems
Authors: Boyacı Tamer , Gallego Guillermo
Published: October 2002

We present a service constrained (Q, r) model that minimizes expected holding and ordering costs subject to an upper bound on the expected waiting time of demands that are actually backordered. We show that, after optimizing over r, the average cost is quasiconvex in Q for logconcave continuous lead time demand distributions. For logconcave discrete lead time demand distributions we find a single‐pass efficient algorithm based on a novel search stopping criterion. The algorithm also allows for bounds on the variability of the service measure. A brief numerical study indicates how the bounds on service impact the optimal average cost and the optimal (Q, r) choice. The discrete case algorithm can be readily adapted to provide a single pass algorithm for the traditional model that bounds the expected waiting time of all demands (backordered or not). © 2002 Wiley Periodicals, Inc. Naval Research Logistics 49: 557–573, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/nav.10028
Lazy evaluation in penniless propagation over join trees
Authors: Cano Andrés , Moral Serafín , Salmerón Antonio
Published: October 2002

In this paper, we investigate the application of the ideas behind Lazy propagation to the Penniless propagation scheme. Probabilistic potentials attached to the messages and the nodes of the join tree are represented in a factorized way as a product of (approximate) probability trees, and the combination operations are postponed until they are compulsory for the deletion of a variable. We tested two variations of the basic Lazy scheme: One is based on keeping a hash table for the operations with probabilistic potentials that are carried out more than once during the propagation, to avoid repeating computations; the other uses a heuristic method to determine the order of the operations when combining a set of potentials. © 2002 Wiley Periodicals, Inc.
Better approximation ratios for the single‐vehicle scheduling problems on line‐shaped networks
Authors: Karuno Yoshiyuki , Nagamochi Hiroshi , Ibaraki Toshihide
Published: October 2002

We consider two variants of the single‐vehicle scheduling problem on line‐shaped networks. Let L = (V, E) be a line, where V = {v1, v2, … , vn} is a set of n vertices and E = {{vi, vi+1}|i = 1, 2, … , n − 1} is a set of edges. The travel times w(u, v) and w(v, u) are associated with each edge {u, v} ∈ E, and each job, which is also denoted as v and is located at vertex v ∈ V, has release time r(v) and handling time h(v). There is a single vehicle, which is initially situated at v1 ∈ V, and visits all vertices to process the jobs before it returns back to v1. The first problem asks to find an optimal routing schedule of the vehicle that minimizes the completion time. This is NP‐hard [21], and there exists an approximate algorithm with the approximation ratio of 2 [12]. In this paper, we improve this ratio to 1.5. On the other hand, the second problem minimizes the maximum lateness, under the assumption that all release times r(v) are zero, but there are due times d(v) for v ∈ V and d(vn+1) for the vehicle. This problem is also NP‐hard [13]. We improve the previous best‐known approximation ratio of 2, which was obtained in [11], to 1.5. © 2002 Wiley Periodicals, Inc.
Altered odor‐induced expression of c‐fos and arg 3.1 immediate early genes in the olfactory system after familiarization with an odor
Authors: Montag‐Sallaz M. , Buonviso N.
Published: October 2002

In adult rats, repeated exposure to an odorant, in absence of any experimentally delivered reinforcement, leads to a drastic decrease in mitral/tufted (M/T) cell responsiveness, not only for the familiar odor but also for other novel odors. In the present study, using two different and complementary in situ hybridization methods, we analyzed the effect of familiarization with an odorant on c‐fos and arg 3.1 mRNA expression levels, and we examined the odor specificity of this effect. Odor exposure induces a specific increase in c‐fos and arg 3.1 expression in some particular olfactory bulb quadrants. Previous familiarization with the test odor results in a decreased expression of both IEGs in these quadrants, leading to the alteration of the odor‐specific pattern of c‐fos and arg 3.1 expression. In contrast, this odor‐specific pattern is not affected when different odors are used for familiarization and test. Similarly, an odor‐specific familiarization effect leading to a reduced c‐fos and arg 3.1 expression was also detected in the cingulate cortex and in the anterior piriform cortex. These results support our hypothesis that the decrease in M/T cell responsiveness following a preceding familiarization with an odorant may be related to a particular form of synaptic plasticity involving changes at the genomic level, and reveals further insight in olfactory information processing and the cellular mechanisms underlying familiarization in the olfactory system. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 61–72, 2002
Serotonergic sensory‐motor neurons mediate a behavioral response to hypoxia in pond snail embryos
Authors: Kuang Shihuan , Doran Shandra A. , Wilson Richard J. A. , Goss Greg G. , Goldberg Jeffrey I.
Published: October 2002

Oxygen (O2) is one of the most important environmental factors that affects both physiological processes and development of aerobic animals, yet little is known about the neural mechanism of O2 sensing and adaptive responses to low O2 (hypoxia) during development. In the pond snail, Helisoma trivolvis, the first embryonic neurons (ENC1s) to develop are a pair of serotonergic sensory‐motor cells that regulate a cilia‐driven rotational behavior. Here, we report that the ENC1‐ciliary cell circuit mediates an adaptive behavioral response to hypoxia. Exposure of egg masses to hypoxia elicited a dose‐dependent and reversible acceleration of embryonic rotation that mixed capsular fluid, thereby facilitating O2 diffusion to the embryo. The O2 partial pressures (Po2) for threshold, half‐maximal, and maximal rotational response were 60, 28, and 13 mm Hg, respectively. During hypoxia, embryos relocated to the periphery of the egg masses where higher Po2 levels occurred. Furthermore, intermittent hypoxia treatments induced a sensitization of the rotational response. In isolated ciliary cells, ciliary beating was unaffected by hypoxia, suggesting that in the embryo, O2 sensing occurs upstream of the motile cilia. The rotational response of embryos to hypoxia was attenuated by application of the serotonin receptor antagonist, mianserin, correlated to the development of ENC1‐ciliary cell circuit, and abolished by laser‐ablation of ENC1s. Together, these data suggest that ENC1s are unique oxygen sensors that may provide a good single cell model for the examination of mechanistic, developmental, and evolutionary aspects of O2 sensing. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 73–83, 2002
Development of the specialized AMPA receptors of auditory neurons
Authors: Sugden Steven G. , Zirpel Lance , Dietrich Craig J. , Parks Thomas N.
Published: October 2002

At maturity, the AMPA receptors of auditory neurons exhibit very rapid desensitization kinetics and high permeability to calcium, reflecting the predominance of GluR3 flop and GluR4 flop subunits and the paucity of GluR2. We used mRNA analysis and immunoblotting to contrast the development of AMPA receptor structure in the chick cochlear nucleus [nucleus magnocellularis (NM)] with that of the slowly desensitizing and calcium‐impermeable AMPA receptors of brainstem motor neurons in the nucleus of the glossopharyngeal/vagal nerves. The relative abundance of transcripts for GluRs 1–4 changes substantially in auditory (but not motor) neurons after embryonic day (E)10, with large decreases in GluR2 and increases in GluR3 and GluR4. Relative to the motor neurons, NM neurons show a higher abundance of flop isoforms of GluRs 2–4 at E10, suggesting that auditory neurons are already biased toward expression of flop isoforms before the onset of synaptic function at E11. Immunoreactivities in NM show very distinct developmental patterns from E13 onward: GluR2 declines by >90%, GluR3 increases threefold, and GluR4 remains relatively constant. Our results show that there are a series of critical points during normal development, most occurring after the onset of function, when rapid changes in receptor structure (occurring via both transcriptional and post‐transcriptional control mechanisms) produce the specialized AMPA receptor functions that enable auditory neurons to accurately encode acoustic information. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 189–202, 2002
Essential boundary condition enforcement in meshless methods: boundary flux collocation method
Authors: Wu Cheng‐Kong C. , Plesha Michael E.
Published: October 2002

Element‐free Galerkin (EFG) methods are based on a moving least‐squares (MLS) approximation, which has the property that shape functions do not satisfy the Kronecker delta function at nodal locations, and for this reason imposition of essential boundary conditions is difficult. In this paper, the relationship between corrected collocation and Lagrange multiplier method is revealed, and a new strategy that is accurate and very simple for enforcement of essential boundary conditions is presented. The accuracy and implementation of this new technique is illustrated for one‐dimensional elasticity and two‐dimensional potential field problems. Copyright © 2001 John Wiley & Sons, Ltd.
Elastoplastic dynamic analysis with hybrid stress elements
Authors: Teixeira de Freitas J. A. , Wang Z. M.
Published: October 2002

The stress model of the hybrid finite element formulation is applied to the solution of dynamic elastoplastic structural problems. The stress field is approximated in the domain of the elements and the displacements on its boundary. The displacement, velocity and acceleration approximations in the domain of the element are implicit, in the sense that they result from a combination of the stress estimate with the time integration procedure that ensures that the equilibrium condition is locally satisfied. The finite elements are subdivided in plastic cells where a gradient dependent model is implemented using a hybrid formulation based on the approximation of the plastic parameter and the plastic radiation fields in the domain and on the boundary of the plastic cells, respectively. Generalized variables associated with orthogonal and naturally hierarchical bases are used. The resulting solving systems are symmetric, sparse, p‐adaptive and well suited to parallel processing. The performance of the element is assessed using a representative set of testing problems. Copyright © 2001 John Wiley & Sons, Ltd.
On the optimal cooling strategy for variable‐speed continuous casting
Authors: Constales D. , Kačur J. , Van Keer R.
Published: October 2002

In this paper, we consider the inverse problem of determining the optimal cooling parameters for continuous casting under changing casting speed. We rely on automatic differentiation to support different search methods for the parameter values that will minimize a given cost functional, which can include a variety of criteria: surface temperature evolution and variation, interface position, full solidification point. In the direct problem we use a fixed‐domain transformation to solve the corresponding free‐boundary problem to high accuracy. Numerical experiments are provided to illustrate and support the effectiveness of the present concept. Copyright © 2001 John Wiley & Sons, Ltd.
A procedure for approximation of the error in the EFG method
Authors: Gavete L. , Cuesta J. L. , Ruiz A.
Published: October 2002

In this paper, we present a procedure to estimate the error in elliptic equations using the element‐free Galerkin (EFG) method, whose evaluation is computationally simple and can be readily implemented in existing EFG codes. The estimation of the error works very well in all numerical examples for 2‐D potential problems that are presented here, for regular and irregular clouds of points. Moreover, it was demonstrated that this method is very simple in terms of economy and gives a good performance.

The results show that the error in EFG approximation may be estimated via the error estimator described in this paper. The quality of the estimation of the error is demonstrated by numerical examples. The implemented procedure of error approximation allows the global energy norm error to be estimated and also gives a good evaluation of local errors. It can, thus, be combined with a full adaptive process of refinement or, more simply, provide guidance for redesign of cloud of points. Copyright © 2001 John Wiley & Sons, Ltd.
Optimal mesh design for the finite element approximation of reaction–diffusion problems
Authors: Xenophontos Christos
Published: October 2002

We consider the numerical approximation of singularly perturbed problems, and in particular reaction–diffusion problems, by the h version of the finite element method. We present guidelines on how to design non‐uniform meshes both in one and two dimensions that are asymptotically optimal as the meshwidth tends to zero. We also present the results of numerical computations showing that robust, optimal rates can be achieved even in the pre‐asymptotic range. Copyright © 2001 John Wiley & Sons, Ltd.
Adaptive backward Euler time stepping with truncation error control for numerical modelling of unsaturated fluid flow
Authors: Kavetski Dmitri , Binning Philip , Sloan Scott W.
Published: October 2002

An automatic time stepping scheme with embedded error control is developed and applied to the moisture‐based Richards equation. The algorithm is based on the first‐order backward Euler scheme, and uses a numerical estimate of the local truncation error and an efficient time step selector to control the temporal accuracy of the integration. Local extrapolation, equivalent to the use of an unconditionally stable Thomas–Gladwell algorithm, achieves second‐order temporal accuracy at minimal additional costs. The time stepping algorithm also provides accurate initial estimates for the iterative non‐linear solver. Numerical tests confirm the ability of the scheme to automatically optimize the time step size to match a user prescribed temporal error tolerance. An important merit of the proposed method is its conceptual and computational simplicity. It can be directly incorporated into existing or new software based on the backward Euler scheme (currently prevalent in subsurface hydrologic modelling), and markedly improves their performance compared with simple fixed or heuristic time step selection. The generality of the approach also makes possible its use for solving PDEs in other engineering applications, where strong non‐linearity, stability or implementation considerations favour a simple and robust low‐order method, or where there is a legacy of backward Euler codes in current use. Copyright © 2001 John Wiley & Sons, Ltd.