bluuebunny/crossref_metadata_2025 huggingface dataset:
Animal models for the study of adenosine receptor function
Authors: Yaar R. , Jones M.R. , Chen J.‐F. , Ravid Katya
Published: August 2004

Adenosine receptors represent a family of G‐protein coupled receptors that are ubiquitously expressed in a wide variety of tissues. This family contains four receptor subtypes: A1 and A3, which mediate inhibition of adenylyl cyclase; and A2a and A2b, which mediate stimulation of this enzyme. Currently, all receptor subtypes have been genetically deleted in mouse models except for the A2b adenosine receptor, and some have been overexpressed in selective tissues of transgenic mice. Studies involving these transgenic mice indicated that receptor levels are rate limiting, as effects were amplified upon increases in receptor level. The knockout models pointed to clusters of activities related to the physiologies of the cardiovascular and the nervous systems, which are either reduced or enhanced upon specific receptor deletion. Interestingly, the trend of effects on these systems is similar in the A1 and A3 adenosine receptor knockout mice and opposite to the effects observed in the A2a adenosine receptor knockout model. This review summarizes in vitro studies on pathways affected by each adenosine receptor, and primarily focuses on the above in vivo models generated to investigate the physiologic role of adenosine receptors. Furthermore, it illustrates the need for multiple adenosine receptor subtype deficiency studies in mice and the deletion of the A2b subtype. © 2005 Wiley‐Liss, Inc.
Involvement of the Fhit gene in the ionizing radiation‐activated ATR/CHK1 pathway
Authors: Hu Baocheng , Han Shuang‐Yin , Wang Xiang , Ottey Michelle , Potoczek Magdalena B. , Dicker Adam , Huebner Kay , Wang Ya
Published: August 2004

Fragile Histidine Triad (Fhit) gene deletion, methylation, and reduced Fhit protein expression occur in about 70% of human epithelial tumors and, in some cancers, are clearly associated with tumor progression. Specific Fhit signal pathways have not been identified, although it has been shown that Fhit overexpression leads to apoptosis in many cancer cell lines. We report in this study that Fhit−/− cells derived from gene knockout mice show much stronger S and G2 checkpoint responses than their wild type counterparts. The strong checkpoint responses are regulated by the ATR/CHK1 pathway, which contributes to the radioresistance of Fhit−/− cells. These results indicate an association of Fhit gene inactivation with increased survival after DNA damage, which is related to the over‐active checkpoints regulated by the ATR/CHK1 pathway. These results also suggest the potential effects of Fhit‐dependent DNA damage response on tumor progression. © 2004 Wiley‐Liss, Inc.
Complex H2AX phosphorylation patterns by multiple kinases including ATM and DNA‐PK in human cells exposed to ionizing radiation and treated with kinase inhibitors
Authors: Wang Hongyan , Wang Minli , Wang Huichen , Böcker Wilfried , Iliakis George
Published: August 2004

In eukaryotic cells, DNA double strand breaks (DSBs) cause the prompt phosphorylation of serine 139 at the carboxy terminus of histone H2AX to generate γ‐H2AX, detectable by Western blotting or immunofluorescence. The consensus sequence at the phosphorylation site implicates the phosphatidylinositol 3‐like family of protein kinases in H2AX phosphorylation. It remains open whether ATM (ataxia telangiectasia mutated) is the major H2AX kinase, or whether other members of the family, such as DNA‐PK (DNA dependent protein kinase) or ATR (ATM and Rad3 related), contribute in a functionally complementary manner. To address this question, we measured global H2AX phosphorylation in cell lysates and foci formation in individual cells of either wild type or mutant (ATM or DNA‐PK) genetic background. Normal global phosphorylation kinetics is observed after irradiation in cells defective either in ATM or DNA‐PK alone, suggesting a complementary contribution to H2AX phosphorylation. This is further supported by the observation that initial H2AX phosphorylation is delayed when both kinases are inhibited by wortmannin, as well as when ATM is inhibited by caffeine in DNA‐PK deficient cells. However, robust residual global phosphorylation is detectable under all conditions of genetic or chemical inhibition suggesting the function of additional kinases, such as ATR. Treatment with wortmannin, caffeine, or UCN‐01 produces a strong DNA‐PK dependent late global hyperphosphorylation of H2AX, uncoupled from DNA DSB rejoining and compatible with an inhibition of late steps in DNA DSB processing. Evaluation of γ‐H2AX foci formation confirms the major conclusions made on the basis of global H2AX phosphorylation, but also points to differences particularly several hours after exposure to IR. The results in aggregate implicate DNA‐PK, ATM and possibly other kinases in H2AX phosphorylation. The functional significance and the mechanisms of coordination in space and time of these multiple inputs require further investigation. © 2004 Wiley‐Liss, Inc.
P253R fibroblast growth factor receptor‐2 mutation induces RUNX2 transcript variants and calvarial osteoblast differentiation
Authors: Baroni Tiziano , Carinci Paolo , Lilli Cinzia , Bellucci Catia , Aisa Maria Cristina , Scapoli Luca , Volinia Stefano , Carinci Francesco , Pezzetti Furio , Calvitti Mario , Farina Antonio , Conte Carmela , Bodo Maria
Published: August 2004

Unregulated fibroblast growth factor 2 (FGF2) signaling caused by mutations in the fibroblast growth factor receptor (FGFR2) leads to human craniosynostosis such as the Apert syndrome. In an in vitro control model of calvarial osteoblasts from Apert patients carrying the FGFR2 P253R mutation, we studied the changes in cellular phenotype and evaluated the effects of FGF2. Compared with wild‐type controls, osteocalcin mRNA was down‐regulated in Apert osteoblasts, Runt‐related transcription factor‐2 (RUNX2) mRNA was differentially spliced, and FGF2 secretion was greater. Total protein synthesis, fibronectin and type I collagen secretion were up‐regulated, while protease and glycosidase activities and matrix metalloproteinase‐13 (MMP‐13) transcription were decreased, suggesting an altered ECM turnover. Adding FGF2 increased protease and glycosidase activities and down‐regulated fibronectin and type I collagen secretion in Apert osteoblasts. High affinity FGF2 receptors were up‐regulated in Apert osteoblasts and analysis of signal transduction showed elevated levels of Grb2 tyrosine phosphorylation and the Grb2‐p85 beta association, which FGF2 stimulation strongly reduced. All together these findings suggest increased constitutive receptor activity in Apert mutant osteoblasts and an autocrine loop involving the FGF2 pathway in modulation of Apert osteoblast behavior. © 2004 Wiley‐Liss, Inc.
Pilot‐plant production of xylo‐oligosaccharides from corncob by steaming, enzymatic hydrolysis and nanofiltration
Authors: Yuan QP , Zhang H , Qian ZM , Yang XJ
Published: August 2004

This paper reports a pilot‐plant production process for xylo‐oligosaccharides (mainly xylobiose and xylotriose) from corncob meal by steaming treatment followed by enzymatic hydrolysis and nanofiltration. The effects of corncob meal pretreatment, steaming temperature and time were investigated in order to obtain maximum extraction of xylan and to minimize the autohydrolysis of xylan into xylose. The enzymatic reaction was carried out using Aspergillus niger AN‐1.15 endo‐xylanase at 55 °C and the optimum enzymatic hydrolysis time was 5 h. The conventional downstream processing for purification of xylo‐oligosaccharides was incorporated with nanofiltration technology, giving benefits of energy saving and removal of monosaccharides. The final product from 40 kg of corncob meal was 10 dm3 of xylo‐oligosaccharide syrup (800 g dm−3 total sugar), containing 74.5% xylobiose and xylotriose. Copyright © 2004 Society of Chemical Industry
A rapid one‐step radiosynthesis of the β‐amyloid imaging radiotracer N‐methyl‐[11C]2‐(4′‐methylaminophenyl)‐6‐hydroxybenzothiazole ([11C]‐6‐OH‐BTA‐1)
Authors: Wilson Alan A. , Garcia Armando , Chestakova Alexandra , Kung Hank , Houle Sylvain
Published: August 2004

The promising β‐amyloid PET imaging agent, [11C]‐6‐OH‐BTA‐1, has been radiolabelled in one step using [11C]‐methyl triflate. No protection of the 6‐hydroxy group is required, greatly simplifying the synthetic method. The reaction may be carried out in solution or by the captive solvent ‘loop’ method. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of 99mTc‐labelled biologically active molecules using borohydride exchange resin as a reducing agent for the preparation of radiopharmaceuticals
Authors: Park Sang Hyun , Gwon Hui Jeong , Park Kyung Bae
Published: August 2004

A novel and efficient method for preparing 99mTc‐complexes of radiopharmaceuticals has been developed by reacting [99mTc]pertechnetate with a ligand in the presence of borohydride exchange resin (BER) as a reducing agent. The latter is stable over a wide range of pH (2–11) and thus can be used with biologically active compounds without the formation of insoluble 99mTcO2 or SnO2 colloids. Since the radiolabelled complexes are produced with high radiochemical purity and labelling efficiency under milder conditions than those required for the conventional reducing agents, the latter can be replaced. The method is expected to be applicable to the preparation of 99mTc‐radiopharmaceuticals. Copyright © 2004 John Wiley & Sons, Ltd.
The use of quasi‐enantiomeric isotopomers as chiral probes for determining stereoisomeric purity
Authors: Eames Jason , Suggate Michael J.
Published: August 2004

This review discusses the use of chiral isotopomers, in particular the use of quasi‐enantiomeric isotopomers as novel chiral probes for determination of enantio‐ and diastereoisomeric purity. Copyright © 2004 John Wiley & Sons, Ltd.
Least squares spectral element method for 2D Maxwell equations in the frequency domain
Authors: Maggio F. , Mazzarella G. , Pitzianti C.
Published: August 2004

We propose a high order numerical method for the first order Maxwell equations in the frequency domain, defined in media with arbitrary complex shape. Our approach is based on the combination of the least squares approach with the spectral element method. The former frees the solution from spurious modes, that can be found sometimes in classical finite element simulations. Many examples of such non‐physical solutions exist in literature, and elimination of these spurious effects is a subject of great interest. Spectral elements are a numerical technique for solving partial differential equations which can be regarded as an extension of finite elements: they merge the flexibility of finite elements in dealing with complex geometries, and the better accuracy of spectral methods. Convergence to exact solution is improved by increasing (at run time) the polynomial degree, with no changes on the computational grid: this provides a significant advantage in respect to low order finite element, which necessarily have to resort to grid refinement. In the authors opinion this approach can be successfully used for the treatment of large scale electromagnetic problems or, alternatively, for applications where higher precision is required. We present a few numerical experiments which prove the capability of the method in object. Copyright © 2004 John Wiley & Sons, Ltd.
Exploring primary activities of the knowledge chain
Authors: Holsapple Clyde W. , Jones Kiku
Published: August 2004

It is often claimed that knowledge management (KM) is important, or even essential, as a basis for competitiveness. The knowledge chain model was recently advanced as a first step in understanding the linkage between KM and organizational performance. Based on a general ontology of KM, this model identifies five primary and four secondary activities as focal points for enhancing competitiveness. Both anecdotes and survey results support the model. Here we further explore the primary KM activities found in the knowledge chain model by treating each as a class involving several distinct types of activity. A literature review yielded over 200 variations of the five primary activities. We consolidate these into 32 distinct activity types and organize them into the five primary activity classes. Within each class a typology of activity types is developed. The result is a more in‐depth version of the knowledge chain model. It gives greater guidance to practitioners striving to incorporate KM into their organizations and their competitive strategies. It also suggests avenues for future research. Copyright © 2004 John Wiley & Sons, Ltd.
Technological utilization for knowledge management
Authors: Moffett Sandra , McAdam Rodney , Parkinson Stephen
Published: August 2004

The aim of this paper is to explore the role and contribution of new information communication technologies in the emerging field of knowledge management (KM). There is much confusion in the literature, and in organizations, as to what role technology has within the field of KM. This quandary has led to the danger that organizations could spend large amounts of time, money and other resources on inappropriate technology in support of their KM efforts. The paper presents the classification of KM technology tools under the headings of collaboration, content management and business intelligence. This paper also seeks to clarify how KM technologies have been applied in organizations in recent years. Overall, the paper presents an overview of current literature and practical technological adoption and application in the KM field. Copyright © 2004 John Wiley & Sons, Ltd.
Meta‐review of knowledge management and intellectual capital literature: citation impact and research productivity rankings
Authors: Serenko Alexander , Bontis Nick
Published: August 2004

The objective of this study is to conduct a meta‐review analysis of the knowledge management and intellectual capital literatures by investigating research productivity and conducting a citation analysis of individuals, institutions, and countries. The meta‐analysis focuses on the three leading peer‐reviewed, refereed journals in this area: Journal of Intellectual Capital, Journal of Knowledge Management, and Knowledge and Process Management. Results indicate that research productivity is exploding and that there are several leading authors and foundation publications that are referenced regularly. Copyright © 2004 John Wiley & Sons, Ltd.
Managing the transition from bricks‐and‐mortar to clicks‐and‐mortar: a business process perspective
Authors: Barnes David , Hinton Matthew , Mieczkowska Suzanne
Published: August 2004

This paper reports from case study‐based research that investigates the impact of the transition from bricks‐and‐mortar to clicks‐and‐mortar businesses on the management of core internal business processes. It has two main aims: firstly, to identify the business models for the processes of order fulfilment and delivery used in clicks‐and‐mortar e‐businesses, and any organizational and environmental factors affecting these processes; secondly, to identify the main factors involved in the adoption and use of Internet‐based ICTs for e‐commerce in clicks‐and‐mortar e‐businesses, and any organizational and environmental factors affecting adoption and use. Results from eight UK‐based companies that have been changing from traditional bricks‐and‐mortar companies to clicks‐and‐mortar e‐businesses are reported. Five main conclusions are drawn from a cross‐case analysis: (1) increased integration in e‐commerce business processes is inhibited by both technological and business barriers; (2) organizations display various and often confused motives for adopting e‐commerce; (3) barriers to the increased adoption of e‐commerce are not just technological, but also sociological and economic; (4) the adoption of e‐commerce challenges existing supply network relationships; (5) the adoption of e‐commerce is tending to automate rather than redesign existing business processes. A three‐pronged approach to future research work in this under‐researched area is recommended. This encompasses undertaking longitudinal case study research to track e‐commerce developments over time, extending the range of cases to include other industry sectors (such as not for profits), and undertaking survey research across a large number of organizations, using quantitative methods, to test the generalizability of the findings from this research. Copyright © 2004 John Wiley & Sons, Ltd.
How middle managers integrate knowledge within projects
Authors: Janczak Sergio
Published: August 2004

This qualitative study explores the interwoven strategic and tactical processes that middle management uses to integrate knowledge in multidivisional organizations. I add to the management literature by not only examining the new roles of middle managers but also by explaining the dynamics of these middle managers' roles when pursuing projects. In summary, my research contributes to the process literature by focusing on middle management. These findings indicate that middle managers used three processes (analytic, intuitive and pragmatic) to create and integrate dispersed knowledge into organizational knowledge delivered to their clients. Copyright © 2004 John Wiley & Sons, Ltd.
Controlled Delivery Achieved with Bi‐Layer Matrix Devices Produced by Co‐Injection Moulding
Authors: Vaz Cláudia M. , van Doeveren Patrick F. N. M. , Dias Gustavo R. , Reis Rui L. , Cunha António M.
Published: August 2004

Summary: The aim of this study was to design new soy protein‐based bi‐layered co‐injection moulded matrix systems aimed to achieve controlled drug delivery. The devices consisted of a drug‐free outer layer (skin) and a drug‐containing core. The systems overcame the inherent disadvantage of non‐linear release associated with diffusion‐controlled single‐layer matrix devices by providing additional releasing area with time to compensate for the decreasing release rate. As expected, the bi‐layer devices presented a significant decrease in drug release rate when compared with a correspondent single layer matrix system. The skin thickness and the degree of crosslinking of the core appeared to be very important tools to tailor the release patterns. Furthermore, due to the amphoteric nature of the soy protein, the developed devices evidenced a pH‐dependent behaviour. The mechanisms of drug release were also elucidated at two different pH values: i) pH 5.0, near the isoelectric point of soy (low matrix solubility); and ii) pH 7.4, physiological pH (high matrix solubility). Consequently, changing the release medium from pH 5.0 to pH 7.4 after two hours, led to an abrupt increase in drug release and the devices presented a typical controlled drug delivery profile: slow release/fast release. These evidences may provide for the development of individual systems with different release onsets that in combination may exhibit drug releases at predetermined times in a pre‐programmed way. Another possibility is the production of three‐layer devices presenting bimodal release profiles (fast release/slow release/fast release) by similar technologies.

Scanning electron micrograph of a developed bi‐layer device.

magnified image

Scanning electron micrograph of a developed bi‐layer device.
Production and Characterization of Chitosan Fibers and 3‐D Fiber Mesh Scaffolds for Tissue Engineering Applications
Authors: Tuzlakoglu Kadriye , Alves Catarina M. , Mano Joao F. , Reis Rui L.
Published: August 2004

Summary: This study reports on the production of chitosan fibers and 3‐D fiber meshes for the use as tissue engineering scaffolds. Both structures were produced by means of a wet spinning technique. Maximum strain at break and tensile strength of the developed fibers were found to be 8.5% and 204.9 MPa, respectively. After 14 d of immersion in simulated body fluid (SBF), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and inductively coupled plasma emission (ICP) spectroscopy analyses showed that a bioactive Ca‐P layer was formed on the surface of the fibers, meaning that they exhibit a bioactive behavior. The samples showed around 120% max. swelling in physiological conditions. The pore sizes of 3‐D chitosan fiber mesh scaffolds were observed to be in the range of 100–500 μm by SEM. The equilibrium‐swelling ratio of the developed scaffolds was found to be around 170% (w/w) in NaCl solution at 37 °C. Besides that, the limit swelling strain was less than 30%, as obtained by mechanical spectroscopy measurements in the same conditions. The viscoelastic properties of the scaffolds were also evaluated by both creep and dynamic mechanical tests. By means of using short‐term MEM extraction test, both types of structures (fibers and scaffolds) were found to be non‐cytotoxic to fibroblasts. Furthermore, osteoblasts directly cultured over chitosan fiber mesh scaffolds presented good morphology and no inhibition of cell proliferation could be observed.

Osteoblast‐like cells proliferating over chitosan based fibers after 7 d of culture.

magnified image

Osteoblast‐like cells proliferating over chitosan based fibers after 7 d of culture.
Fibers and 3D Mesh Scaffolds from Biodegradable Starch‐Based Blends: Production and Characterization
Authors: Pavlov Miroslav P. , Mano João F. , Neves Nuno M. , Reis Rui L.
Published: August 2004

Summary: The aim of this work is the production of fibers from biodegradable polymers to obtain 3D scaffolds for tissue engineering of hard tissues. The scaffolds required for this highly demanding application need to have, as well as the biological and mechanical characteristics, a high degree of porosity with suitable dimensions for cell seeding and proliferation. Furthermore, the open cell porosity should have adequate interconnectivity for a continuous flow of nutrients and outflow of cell metabolic residues as well as to allow cell growth into confluent layers. Blends of corn starch, a natural biodegradable polymer, with other synthetic polymers (poly(ethylene vinyl alcohol), poly(ε‐caprolactone), poly(lactic acid)) were selected for this work because of their good balance of properties, namely biocompatibility, processability and mechanical properties. Melt spinning was used to produce fibers from all the blends and 3D meshes from one of the starch‐poly(lactic acid) blends. The experimental characterization included the evaluation of the tensile mechanical properties and thermal properties of the fibers and the compression stiffness, porosity and degradation behavior of the 3D meshes.

Light microscopy picture of 3D meshes.

magnified image

Light microscopy picture of 3D meshes.
Self‐Assembly of Dendritic Macromolecules Based on the Ionic Interaction of Linear Chain Polyelectrolyte Cores with Oppositely Charged Focal Ionogenic Groups of Dendrons
Authors: Bilibin Alexander Y. , Moukhina Irina V. , Girbasova Nina V. , Egorova Galina G.
Published: August 2004

Summary: A new principle for the design of dendritic macromolecules – the ionic binding of linear chain polyelectrolyte with oppositely charged focal ionogenic groups of dendrons – has been developed. The majority of the dendritic ionic complexes (DICs) are prepared with poly(styrenesulfonic acid) (PSS) as a polymeric core and L‐aspartic acid dendrons of different generations. Two series of DICs were prepared using PSS and aspartic dendrons bearing terminal (located at the external periphery) methoxycarbonyl and hexyloxycarbonyl groups (C1‐n and C6‐n respectively where n is the generation number). Ionic binding of about 100% was found for dendrons of Generation 1–3. The solubility of the DICs was examined and the DICs prepared were studied by IR spectroscopy, 1H NMR and viscometry.

Dendritic ionic complexes prepared using poly(styrenesulfonic acid) acid and aspartic dendrons bearing terminal methoxycarbonyl and hexyloxycarbonyl groups.

magnified image

Dendritic ionic complexes prepared using poly(styrenesulfonic acid) acid and aspartic dendrons bearing terminal methoxycarbonyl and hexyloxycarbonyl groups.
Cover Picture: Macromol. Mater. Eng. 8/2004
Authors: Fortini Sophie , Lavanchy Frédéric , Meyer Thierry
Published: August 2004

Cover: Supercritical fluids (SCF) can be used as alternative to conventional solvents. The supercritical reaction calorimetry, developed to study chemical reactions in SCF, allows accessing thermodynamic and kinetic properties, hydrodynamic and transfer phenomena information as well as reaction monitoring.

Further details can be found in the Full Paper by S. Fortini, F. Lavanchy, and Th. Meyer* on page 757.
Neutral and Cationic Cyclopentadienyliron Macromolecules Containing Arylazo Chromophores
Authors: Abd‐El‐Aziz Alaa S. , Okasha Rawda M. , Shipman Patrick O. , Afifi Tarek H.
Published: August 2004

Summary: A new class of macromolecules containing neutral and cationic organoiron moieties with arylazo chromophores in their backbones has been prepared. Photolysis of these polymers resulted in the removal of the cationic iron moieties leading to new polyferrocenes with azo dyes in their backbones. UV‐vis studies showed λmax around 419 nm in DMF with a bathochromic shift to around 530 nm upon the addition of HCl.

Organoiron macromolecules containing azo dye moieties prepared in this study.

image

Organoiron macromolecules containing azo dye moieties prepared in this study.
Development and validation of the Unified Multiple System Atrophy Rating Scale (UMSARS)
Authors: Wenning Gregor K. , Tison Franc̨ois , Seppi Klaus , Sampaio Cristina , Diem Anja , Yekhlef Farid , Ghorayeb Imad , Ory Fabienne , Galitzky Monique , Scaravilli Tommaso , Bozi Maria , Colosimo Carlo , Gilman Sid , Shults Clifford W. , Quinn Niall P. , Rascol Olivier , Poewe Werner ,   and the Multiple System Atrophy Study Group
Published: August 2004

We aimed to develop and validate a novel rating scale for multiple system atrophy (Unified Multiple System Atrophy Rating Scale ‐ UMSARS). The scale comprises the following components: Part I, historical, 12 items; Part II, motor examination, 14 items; Part III, autonomic examination; and Part IV, global disability scale. For validation purposes, 40 MSA patients were assessed in four centers by 4 raters per center (2 senior and 2 junior raters). The raters applied the UMSARS, as well as a range of other scales, including the Unified Parkinson's Disease Rating Scale (UPDRS) and the International Cooperative Ataxia Rating Scale (ICARS). Internal consistency was high for both UMSARS‐I (Crohnbach's alpha = 0.84) and UMSARS‐II (Crohnbach's alpha = 0.90) sections. The interrater reliability of most of the UMSARS‐I and ‐II items as well as of total UMSARS‐I and ‐II subscores was substantial (k (w) = 0.6–0.8) to excellent (k (w) > 0.8). UMSARS‐II correlated well with UPDRS‐III and ICARS (rs > 0.8). Depending on the degree of the patient's disability, completion of the entire UMSARS took 30 to 45 minutes. Based on our findings, the UMSARS appears to be a multidimensional, reliable, and valid scale for semiquantitative clinical assessments of MSA patients. © 2004 Movement Disorder Society
Validity of separating group‐velocity dispersion of photonic‐crystal fibers into material and waveguide components
Authors: Haldar M. K. , Coetzee J. C. , Gabriel Aw S. F.
Published: August 2004

Based on the effective index model of an endlessly single‐mode photonic‐crystal fiber, the analysis of group‐velocity dispersion (GVD) can be separated into material and waveguide components. In this paper, the validity of this approach is examined. The separation is shown to be valid only at small air‐hole diameters, where the variation of the effective index of the cladding closely follows that of the core. We illustrate the fact that more accurate results of the GVD can be obtained by using a numerical method which avoids separation into the above components, and taking into account the wavelength‐dependent behavior of the refractive index of silica. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 91–93, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20385
Wideband and low‐loss triangular patch dual‐mode bandpass filter using quasi‐fork recessed tapped I/O
Authors: Chen Han‐Jan , Weng Min‐Hung , Horng Jui‐Hong , Houng Mau‐Phou , Wang Yeong‐Her
Published: August 2004

A microstrip triangular‐patch dual‐mode filter using quasi‐fork recessed tapped I/O is designed and fabricated. The proposed filter uses quasi‐fork recessed tapped I/O for enhanced coupling and dual‐mode excitation. The filter characteristics, which are influenced by the recessed depth and gap size between the feed line and the triangular‐patch resonator, is studied. The central frequency of 4.19 GHz, insertion loss S21 of −1.26 dB, and 3‐dB bandwidth of 26.5% are measured, and the three attenuation poles have deep insertion losses of −36.8 dB at 2.72 GHz, −44.6 dB at 3.06 GHz, and −49 dB at 5.56 GHz, respectively. The proposed filters demonstrate good agreement between the experiment and simulation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 99–101, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20388
Fabry–Perot‐based approach for the measurement of complex permittivity of samples inserted in resonant cavities
Authors: André P. S. , Costa L. C. , Devesa S.
Published: August 2004

A new approach to measure the complex dielectric permittivity of materials placed inside a microwave resonant cavity is presented. We exploit the similarity between the microwave cavity and an optical cavity to develop a new measurement technique, which is used to obtain the complex permittivity of a polybutylene terephtalate (PBT). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 106–108, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20390
Lossy transmission line metamaterials
Authors: Caloz Christophe , Itoh Tatsuo
Published: August 2004

Lossy purely LH and generalized CRLH TL metamaterials are analyzed using both an ideal approach, assuming perfectly homogeneous media, and a lumped‐element approach, taking into account the real periodic LC configuration of artificial metastructures. The effects of losses are identified and discussed. A CRLH TL metamaterial with small losses is shown to exhibit propagation characteristics identical to that of a lossless metamaterial. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 112–114, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20392
A compact very‐high‐permittivity dielectric‐eye resonator antenna for multiband wireless applications
Authors: Paul Binu , Mridula S. , Mohanan P. , Bijumon P. V. , Sebastian M. T.
Published: August 2004

A very‐high‐permittivity (εr = 100) multiband dielectric‐eye resonator antenna is presented. The compact antenna, excited by a microstrip line, resonates at two frequencies centered around the 1.9‐GHz and 2.4‐GHz bands with identical polarization. The behavior of the antenna at different positions along the feed line is studied and optimized. Multiple resonances with the same polarization and broad radiation patterns suggest the suitability of the antenna for multiband wireless applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 118–121, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20394
A broadband slope‐strip‐fed microstrip patch antenna
Authors: Wang Wei , Chen Sheng‐Bing , Zhong Shun‐Shi
Published: August 2004

A novel slope‐strip feeding technique for a microstrip antenna is presented in order to achieve a broad bandwidth. The experimental results show that the optimal bandwidth attained is 53.4% for less than −10‐dB return loss. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 121–123, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20395
An improved substrate‐loss model to determine MOSFET drain, source and substrate elements
Authors: Torres‐Torres Reydezel , Murphy‐Arteaga Roberto , Torres‐Jacome Alfonso
Published: August 2004

An improved model to account for the substrate‐loss effects in RF‐MOSFETs, which includes its associated parameter extraction, is presented in this paper. This model considers the source‐to‐bulk capacitance, which allows the proper modeling of MOSFETs output admittance at high frequencies, thus obtaining an excellent agreement between simulated and experimental data up to 21 GHz. The proposed model also allows the determination of the source and drain resistances at a given gate bias, independent of frequency. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 126–130, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20397
One‐dimensional reconstruction of a defect profile based on millimeter‐wave nondestructive techniques
Authors: Maazi M. , Glay D. , Lasri T.
Published: August 2004

This paper describes a procedure for the characterization of defects inside dielectric materials. This nondestructive technique is supported by the development of a system that operates at 35 GHz. The reconstruction of the defect profile is performed by considering that the measured data are the result of a convolution of the true data with a point‐spread function (PSF). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 133–138, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20399
Numerical validation of dispersion relations using a cylindrical wave for 2D FDTD methods
Authors: Sun Guilin , Trueman Christopher W.
Published: August 2004

The numerical dispersion of a proposed new FDTD scheme is often evaluated and compared with that of well‐established FDTD methods. Because there may be a theoretical deficiency in the dispersion analysis, numerical experimentation is often used to validate the dispersion relation. This paper describes the “matching method” for validation using a cylindrical wave in the two‐dimensional (2D) case. The matching method is demonstrated by evaluating the numerical dispersion of Yee's FDTD and ADI‐FDTD. The result is compared with the analytical numerical dispersion relation, and excellent agreement is obtained. The difference between the theoretical value for the numerical dispersion and that from numerical experiments using the matching method is 10−5 for Yee's FDTD and 10−4–10−5 for ADI‐FDTD. The numerical velocity obtained from the matching method satisfies the theoretical dispersion relation with residual errors to the order of 10−6. Such accuracy is sufficient to conclude that a numerical dispersion relation is correct. Although the matching method uses a cylindrical wave to test the numerical dispersion relation, the cylindrical wave is not a solution of the difference equations, thus it cannot be used to derive a theoretical dispersion relation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 138–142, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20400
Novel compact photonic band‐gap structures using rectangular increasing‐distance spiral slots
Authors: Fuqi Shan , Baoxin Gao
Published: August 2004

A novel, compact, rectangular increasing‐distance spiral‐slot (RIDSS) structure is proposed for photonic band‐gap (PBG) applications. The dimension of the RIDSS structure is only about 1/8λ at the cutoff frequency. Only three cells of the RIDSS‐PBG are sufficient for the measured beyond the 20‐dB stopband from 1470 to 2034 MHz, thus rendering the whole structure super‐compact. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 144–146, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20402
A broadband CPW‐fed nonuniform folded‐slot antenna with a pair of matching slots
Authors: Deng S. M. , Chiu C. W. , Lai T. M. , Chen T. W.
Published: August 2004

In this paper, we describe a variation of a folded slot antenna that is formed by a nonuniform‐width slot. The antenna is fed by a coplanar waveguide on which a pair of small slits are located on both sides for broadband matching. The simulated results and measured data reveal that it enjoys a relatively wide bandwidth of 37.4%. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 147–148, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20403
High‐performance bulk and thin‐film microstrip transmission lines on VLSI‐standard Si substrates
Authors: Chen C. C. , Hung B. F. , Chin Albert , McAlister S. P.
Published: August 2004

Microstrip transmission lines with very low power loss of 0.4 dB/mm at 50 GHz have been fabricated on Si substrates using an optimized ion‐implantation process. These devices have the inherent advantages of smaller chip size and better power performance than CPW lines. Using the same approach, high‐performance thin‐film microstrip lines are also developed, showing a loss of 0.9 dB/mm at 20 GHz. This approach is compatible with existing VLSI backend layout technology. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 148–151, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20404
Characterization of resistive‐loaded wire loop in UWB (impulse) radio
Authors: Li Hui Feng , Chen Zhi Ning , Li Le‐Wei
Published: August 2004

This paper discusses the applicability of loaded circular‐loop antennas for impulse radio systems using a time‐domain integral‐equation (TDIE) method. The circular loops loaded with lumped and distributed resistances are characterized for pulse radiation and reception. The effects of the loads on the current distributions are investigated. The performance of the system comprising two identical loop antennas is examined and validated by measurement for ultra‐wideband applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 151–156, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20405
Some properties of an open‐ended circular waveguide with one‐ and two‐sided ideal hard walls
Authors: Skobelev Sergei , Kildal Per‐Simon
Published: August 2004

The problem of radiation from a hard open‐ended circular waveguide excited in the dominant TEM mode is solved. The cases of one‐sided and two‐sided hard‐wall surfaces are considered. The rigorous solution obtained shows that the reflected TEM mode field in the latter case, unlike that in the former case, is completely concentrated at the surface outside the waveguide. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 160–164, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20407
A compact hairpin bandpass filter on high‐permittivity dielectrics using a tape‐casting technique
Authors: Chen Lih‐Shan , Weng Min‐Hung , Huang Tsung‐Hui , Chen Han‐Jan , Hsi Yi‐Chang , Houng Mau‐Phon
Published: August 2004

By using high‐permittivity dielectrics, bandpass filters can be miniaturized. A hairpin‐line filter based on high‐permittivity dielectrics is proposed in this study. Ba2Ti9O20, with high dielectric constant, low loss, and stable temperature is available for the dielectric resonator and is adopted as a material in the fabrication of high‐permittivity ceramic substrates. A tape‐casting technique is employed to produce thin and flat Ba2Ti9O20‐based ceramic substrates. The center frequency of the fabricated bandpass filter is 5.75 GHz and the bandwidth is 742 MHz. The measured insertion and return losses of the filter are −1.34 and −12 dB, respectively. The measured response of the fabricated filter is in agreement with the simulated results. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 164–166, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20408
Gain clamped double‐pass L‐band EDFA with incorporation of FBG at the input end of the optical amplifier
Authors: Harun S. W. , Ahmad H.
Published: August 2004

A gain‐clamping technique in two‐stage double‐pass L‐band EDFA is demonstrated using a single fiber Bragg grating (FBG). Two types of FBGs, broadband and narrowband, have been used in the gain‐clamped system. The gain is clamped at 18.7 and 17.5 dB for the design with narrowband and broadband FBGs, respectively. The measured gain variation in both designs is below ±0.15 dB. The maximum input‐signal‐power level for which the gain remains clamped for the narrowband and broadband FBG systems is about −15 and −10 dBm, respectively. However, the existence of a strong laser in the cavity severely reduces the population inversion at the input part of the amplifiers. This causes the noise figure of both designs to increase by 6.4 dB and 3.5 dB for narrowband and broadband FBG system, compared to that of unclamped amplifier, at small signal power. These results show that gain clamping can be achieved in a double‐pass amplifier by simply adding a single FBG, whereby the broadband system shows a better performance than the narrowband system in terms of input‐signal‐power dynamics range and noise figure. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 166–168, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20409
A dual‐mode bandpass filter with a wide stopband
Authors: Weng Min‐Hung , Yang Ru‐Yuan , Hung Cheng‐Yuan , Wu Hung‐Wei , Chen Wu‐Nan , Houng Mau‐Phon
Published: August 2004

A novel dual‐mode band‐pass filter with a cross‐shaped resonator and three ring resonators has been designed and implemented. The proposed structure is different from the conventional dual‐mode band‐pass filter. The designed dual‐mode band‐pass filter has a very sharp attenuation rate by two transmission zeros, and high spurious suppression by the band‐stop effect of the three ring resonators. The experiments show good agreement with the simulations. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 177–179, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20412
Clinical features and pathophysiological basis of sensory neuronopathies (ganglionopathies)
Authors: Kuntzer Thierry , Antoine Jean‐Christophe , Steck Andreas J.
Published: August 2004

Sensory ganglionopathies have a frequent association with neoplastic disorders (paraneoplastic subacute sensory neuronopathy, or SSN) or dysimmune disorders (Sjögren's syndrome, SS; Miller Fisher syndrome; and Bickerstaff's brainstem encephalitis, BBE), with drugs, such as cisplatin or pyridoxine, and with inherited disorders with degeneration of dorsal root ganglion cells. Unsteady gait and pseudoathetoid movements of the hand are the distinctive signs encountered in these disorders. The chronic disorders are characterized by non–length‐dependent abnormalities of sensory nerve action potentials (SNAPs) and differ from other sensory neuropathies in showing a global, rather than distal, decrease in SNAP amplitudes. This review focuses on recent advances in defining the mechanisms involved in sensory ganglionopathies. Specific topics include a summary of their clinical features, pathological findings, and immunopathology. In SSN, early diagnosis by the detection of anti‐Hu antibodies and early treatment of the cancer gives the best chance of stabilizing the disorder. In SS sensory ganglionitis, response to treatment has been disappointing, but immunomodulating treatments are emerging. The immunological profile common to BBE and Fisher syndrome supports a common pathogenesis. In toxic sensory neuronopathy, no treatment is available. The differential diagnosis involves separating sensory ganglionopathies from other ataxic polyneuropathies, such as infectious neuropathies, sensory neuropathies with various autoantibodies, and the neuropathies seen in celiac disease. Muscle Nerve 30:255–268, 2004
Porphyric neuropathy
Authors: Albers James W. , Fink John K.
Published: August 2004

The hepatic porphyrias are a group of rare metabolic disorders characterized by enzymatic defects in the biosynthesis of heme, a metalloporphyrin that is the principal product of porphyrin metabolism. The hepatic porphyrias are genetically transmitted as autosomal‐dominant disorders with variable expression that produce a particularly severe form of neuropathy. Most medical students readily recognize acute attacks of porphyria when the classic triad of abdominal pain, psychosis, and neuropathy is present. Yet, porphyric neuropathy is a source of confusion in practice, and patients with porphyria rarely receive the correct diagnosis early in the course of the illness. Porphyric neuropathy is manifest by symptoms, signs, and cerebrospinal fluid abnormalities resembling acute Guillain–Barré syndrome. However, accompanying psychological features, a proximal predilection of asymmetric weakness, and electrodiagnostic findings indicative of an axonal polyradiculopathy or neuronopathy all suggest the diagnosis of porphyria. Confirmation of the diagnosis depends on use of appropriate laboratory studies. The underlying pathophysiology of porphyric neuropathy has not been established, but it may be related to direct neurotoxicity of elevated levels of δ‐aminolevulinic acid. The severity of the neuropathy and the availability of potential treatments, including avoidance of provocative factors, make identification important. Muscle Nerve 30: 410–422, 2004
A mesh‐free approach to solving the axisymmetric Poisson's equation
Authors: Chen C. S. , Muleshkov A. S. , Golberg M. A. , Mattheij R. M. M.
Published: August 2004

In this article, we extend previous work of Karageorghis and Fairweather (Int J Numer Methods Engng 44 (199), 1653–1669) on the method of fundamental solutions (MFS) for solving Laplace's equation in axisymmetric geometry to the case of Poisson's equation. When the boundary condition and source term are axisymmetric, the problem reduces to solving the Poisson's equation in cylindrical coordinates in the two‐dimensional (r, z) region of the original three‐dimensional domainS.Hence, the original boundary value problem is reduced to a two‐dimensional one. To make use of the MFS, it is necessary to calculate a particular solution, which can be subtracted off, so that the MFS can be used to solve the resulting Laplace problem. This presents a novel problem, since the axisymmetric Poisson operator does not have constant coefficients, so previous methods based on radial basis functions cannot be used. To overcome this, the source term is approximated by a two‐dimensional polynomial inrandzas in Goldberg et al. (Numer Methods Partial Differential Eq 19 (2003), 112–133). One can then obtain polynomial particular solutions by the method of undetermined coefficients. The resulting Laplace equation is then solved by the axisymmetric MFS. Numerical results are given to show the accuracy and efficiency of the proposed numerical method. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
On the structure and growth rate of unstable modes to the Rossby‐Haurwitz wave
Authors: Skiba Yuri N. , Pérez‐García Ismael
Published: August 2004

The normal mode instability study of a steady Rossby‐Haurwitz wave is considered both theoretically and numerically. This wave is exact solution of the nonlinear barotropic vorticity equation describing the dynamics of an ideal fluid on a rotating sphere, as well as the large‐scale barotropic dynamics of the atmosphere. In this connection, the stability of the Rossby‐Haurwitz wave is of considerable mathematical and meteorological interest. The structure of the spectrum of the linearized operator in case of an ideal fluid is studied. A conservation law for perturbations to the Rossby‐Haurwitz wave is obtained and used to get a necessary condition for its exponential instability. The maximum growth rate of unstable modes is estimated. The orthogonality of the amplitude of a non‐neutral or non‐stationary mode to the Rossby‐Haurwitz wave is shown in two different inner products. The analytical results obtained are used to test and discuss the accuracy of a numerical spectral method used for the normal mode stability study of arbitrary flow on a sphere. The comparison of the numerical and theoretical results shows that the numerical instability study method works well in case of such smooth solutions as the zonal flows and Rossby‐Haurwitz waves. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005