bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic resonance imaging of tissue and vascular layers in the cat retina
Authors: Shen Qiang , Cheng Haiying , Pardue Machelle T. , Chang Thomas F. , Nair Govind , Vo Van Toi , Shonat Ross D. , Duong Timothy Q.
Published: March 2006

Purpose

To report the visual resolution of multiple cell and vascular “layers” in the cat retina using MRI.

Materials and Methods

T2‐ and diffusion‐weighted MRI at 4.7 Tesla was performed. Layer‐specific thickness, T2, spin density, apparent diffusion coefficient perpendicular (ADC⟂) and parallel (ADC∥) to the retinal surface were tabulated. T1‐weighted MRI was acquired before and after intravenous administration of Gd‐DTPA and subtraction images were obtained. Histology was performed for validation.

Results

Three distinct “layers” were observed. The inner strip nearest to the vitreous (exhibiting large T2, ADC, spin density with Gd‐DTPA enhancement) overlapped the ganglion cell layer, bipolar cell layer, and the embedded retinal vascular layer. The middle strip (exhibiting small T2, ADC, spin density without Gd‐DTPA enhancement) overlapped the photoreceptor cell layer and the inner and outer segments. The outer strip (exhibiting large T2, ADC, spin density with Gd‐DTPA enhancement) overlapped the tapetum and choroidal vascular layer. T2, spin density, ADC⟂ and ADC∥ of different “layers” were tabulated. The inner strip was slightly thicker than the other two strips. The total thickness, including neural and nonneural retina, was 358 ± 13μm (N = 6) by MRI and 319 ± 77 μm (N = 5) by histology.

Conclusion

MRI provides a noninvasive tool to study the retina with laminar specificity without depth limitation. J. Magn. Reson. Imaging 2006. Published 2006 Wiley‐Liss, Inc.
Influence of caloric restriction on motor behavior, longevity, and brain lipid composition in Sandhoff disease mice
Authors: Denny Christine A. , Kasperzyk Julie L. , Gorham Kristen N. , Bronson Roderick T. , Seyfried Thomas N.
Published: March 2006

Caloric restriction (CR), which improves health and increases longevity, was studied as a therapy in a hexosaminidase β knockout mouse model of Sandhoff disease (SD), an incurable neurodegenerative disease involving accumulation of brain ganglioside GM2 and asialo‐GM2 (GA2). Adult mice were fed a rodent chow diet either ad libitum (AL) or restricted to reduce body weight by 15–18% (CR). Although GM2 and GA2 were elevated, no significant differences were seen between the Hexb−/− and the Hexb+/− mice for most brain phospholipids and cholesterol. Cerebrosides and sulfatides were reduced in the Hexb−/− mice. In addition, rotorod performance was significantly worse in the Hexb−/− mice than in the Hexb+/− mice. CR, which decreased circulating glucose and elevated ketone bodies, significantly improved rotorod performance and extended longevity in the Hexb−/− mice but had no significant effect on brain lipid composition or on cytoplasmic neuronal vacuoles. The expression of CD68 and F4/80 was significantly less in the CR‐fed than in the AL‐fed Hexb−/− mice. We suggest that the CR delays disease progression in SD and possibly in other ganglioside storage diseases through anti‐inflammatory mechanisms. © 2006 Wiley‐Liss, Inc.
Interferon‐γ is up‐regulated in the hippocampus in response to intermittent fasting and protects hippocampal neurons against excitotoxicity
Authors: Lee Jaewon , Kim So Jung , Son Tae Gen , Chan Sic L. , Mattson Mark P.
Published: March 2006

Dietary restriction (DR) increases the life span of many different organisms, and recent findings have demonstrated neuroprotective effects of DR in rodent and nonhuman primate models of neurodegenerative disorders. The neuroprotective mechanism of action of DR is unknown, but it may result from a mild cellular stress response involving increased production of neurotrophic factors. Because several different cytokines are known to be up‐regulated in brain cells in response to stress, we determined whether DR affected cytokine expression in the rat brain. Levels of expression of interferon‐γ (IFN‐γ) and its receptor were significantly increased in the hippocampus of rats that had been maintained on an intermittent fasting DR regimen compared with rats on the ad libitum control diet. Pretreatment of embryonic rat hippocampal cell cultures with IFN‐γ protected neurons against glutamate‐induced death. IFN‐γ‐mediated neuroprotection was associated with an enhanced recovery of intracellular Ca2+ concentrations following exposure to glutamate. Our data show that intermittent fasting DR stimulates IFN‐γ‐mediated neuroprotective signaling in the hippocampus, suggesting a role for this cytokine in the previously reported ability of DR to protect neurons in animal models of severe epileptic seizures, stroke, and neurodegenerative disorders. © 2006 Wiley‐Liss, Inc.
Rac/Rho pathway regulates actin depolymerization induced by aminoglycoside antibiotics
Authors: Jiang Hongyan , Sha Su‐Hua , Schacht Jochen
Published: March 2006

Stress stimuli can lead to remodeling of the actin cytoskeleton and subsequent alteration of cell adhesion and permeation as well as cell functions and cell fate. We investigated redox‐dependent Rho GTPase‐linked pathways controlling the actin cytoskeleton in the inner ear of the CBA mouse, by using aminoglycoside antibiotics as a noxious stimulus that causes loss of sensory cells via the formation of reactive oxygen species. Kanamycin treatment in vivo interfered with the formation of F‐actin, disturbed the arrangement of β‐actin in the stereocilia of outer hair cells, and altered the intermittent adherens junction/tight junction complexes between outer hair cells and supporting cells. The drug treatment also activated Rac1 and promoted the formation of the complex of Rac1 and p67phox while decreasing the activity of RhoA and reducing the formation of the RhoA/p140mDia complex. In inner‐ear‐derived cell lines, expression of mutated Rac1 changed the structural arrangement of F‐actin and diminished the immunoreactivity of p140mDia. These findings suggest that actin depolymerization induced by kanamycin is mediated by Rac1 activation, followed by the formation of superoxide by NADPH oxidase. These changes will ultimately contribute to aminoglycoside‐induced loss of hair cells. © 2006 Wiley‐Liss, Inc.
The Early Pleistocene Praetiglian and Ludhamian pollen stages in the North Sea Basin and their relationship to the marine isotope record
Authors: Meijer T. , Cleveringa P. , Munsterman D. K. , Verreussel R. M. C. H.
Published: February 2006

In this paper, the currently accepted correlation of the Early Pleistocene Ludhamian stage of England with the Tiglian‐A sub‐stage of the Netherlands is challenged. Recent investigations of Early Pleistocene marine North Sea deposits from a borehole near Noordwijk (the Netherlands) yielded evidence from molluscs, dinoflagellate cysts and sporomorphs for an alternation of warm‐temperate and arctic intervals within the Praetiglian and Tiglian stages. Marine equivalents of the terrestrial‐based pollen sub‐stages Tiglian A and B have been recognised in the upper part of the sequence. A Praetiglian age can be assigned to the lower part of the sequence on the basis of mollusc analysis. Within the Praetiglian, an alternation of warm and cold phases has been recognised from both the dinoflagellate cyst and molluscan records. Three cold phases within the Praetiglian are tentatively correlated with marine isotope stages (MIS) 96–100. The molluscan assemblages provide evidence for climate forcing of the sea level: highest sea levels are reached in the warm‐temperate intervals. Within the Praetiglian, an interval with an acme zone of the dinoflagellate cyst Impagidinium multiplexum, is correlated with the Ludhamian and tentatively linked to MIS 97 and/or MIS 96. The cold molluscan assemblages from the Noordwijk borehole include an acme zone of Megayoldia thraciaeformis, the first and only occurrence of this North Pacific bivalve in the North Sea Basin. Copyright © 2006 John Wiley & Sons, Ltd.
Late Quaternary upwelling off tropical NW Africa: new micropalaeontological evidence from ODP Hole 658C
Authors: Haslett Simon K. , Smart Christopher W.
Published: February 2006

Planktonic foraminifera and radiolaria have been analysed in a Late Quaternary (40–0 ka) sediment sequence from Ocean Drilling Program (ODP) Hole 658C located under a coastal upwelling system near Cap Blanc, offshore northwest Africa, in order to document the palaeoceanographic history of the area. Temporal variations in species abundance and faunal assemblage analysis reveal a tripartite phased sequence of palaeoceanographic change through the Late Quaternary. Phase 1 spans 40–14.5 ka and is characterised by moderate upwelling, but Heinrich event 2 is distinguished as a brief episode of strengthened upwelling. Phase 2 begins with a change in a number of variables at ca. 14.5 ka and extends to ca. 5.5 ka. This phase is characterised by a general strengthening of upwelling, but may be subdivided into three minor phases including (a) the recognition of the Younger Dryas, marked by a temporary reduction in upwelling strength, followed by (b) an intensification of upwelling, and (c) upwelling and high productivity between 8 and 5.5 ka. This phase of upwelling corresponds with maximum Holocene cooling, possibly triggered by the collapse of the Laurentide ice sheet. Phase 3 extends from 5.5 to 0 ka and is characterised by weak upwelling and significant calcite dissolution. These phases are related to climatic events, particularly the African Humid Period (AHP), which is coincident with Phase 2. The AHP is characterised by increased precipitation, linked to an intensification of the African monsoon that enhances North East Trade Wind‐driven coastal upwelling and is associated with the expansion of continental vegetation across North Africa. Copyright © 2006 John Wiley & Sons, Ltd.
Simple Fabrication of Full Color Colloidal Crystal Films with Tough Mechanical Strength
Authors: Wang Jingxia , Wen Yongqiang , Ge Hongli , Sun Zhongwei , Zheng Yongmei , Song Yanlin , Jiang Lei
Published: March 2006

Summary: Colloidal crystal films with a special FCC structure and tough mechanical strength were simply fabricated using latex spheres with a hard PS core and an elastometric PMMA/PAA shell. The monodispersed latex spheres were prepared in one step without any further purification procedure. Distinguished from conventional colloidal crystal films by a bicontinuous FCC structure, the film was fully dense with separate air space, which can greatly improve the mechanical strength of the film. Furthermore, films with brilliant and monochromatic colors covering the entire visible region were fabricated by controlling the diameters of the assembled latex spheres (see Figure). Such a simple method for fabricating PBG tunable colloidal crystal films with tough mechanical strength would have wide applications in many fields, such as optical devices and decorative materials.

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Microfabricated devices: A new sample introduction approach to mass spectrometry
Authors: Lazar Iulia M. , Grym Jakub , Foret Frantisek
Published: February 2006

Instrument miniaturization is one way of addressing the issues of sensitivity, speed, throughput, and cost of analysis in DNA diagnostics, proteomics, and related biotechnology areas. Microfluidics is of special interest for handling very small sample amounts, with minimal concerns related to sample loss and cross‐contamination, problems typical for standard fluidic manipulations. Furthermore, the small footprint of these microfabricated structures leads to instrument designs suitable for high‐density, parallel sample processing, and high‐throughput analyses. In addition to miniaturized systems designed with optical or electrochemical detection, microfluidic devices interfaced to mass spectrometry have also been demonstrated. Instruments for automated sample infusion analysis are now commercially available, and microdevices utilizing chromatographic or capillary electrophoresis separation techniques are under development. This review aims at documenting the technologies and applications of microfluidic mass spectrometry for the analysis of proteomic samples. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 25:573–594, 2006
Mass spectrometric characterization of high‐valent metal‐oxo, ‐peroxo and ‐peroxy intermediates of relevance in oxidation processes
Authors: Bortolini Olga , Conte Valeria
Published: March 2006

The coupling of mass spectrometry with ionization techniques like electrospray ionization (ESI) or matrix‐assisted matrix‐assisted laser desorption‐ionization (MALDI) offers many advantages over other well‐established spectroscopic techniques employed for the investigation of intermediates or short‐lived species in condensed‐phase. In this review we describe some of the applications of mass spectrometry, in particular of ESI‐MS to the detection and characterization of high‐valent metal‐oxo, ‐peroxo and ‐peroxy derivatives, crucial intermediates in the oxyfunctionalization of organic substrates. In addition, by utilizing gas‐phase ion‐molecule reactions and MS/MS experiments, information on the intrinsic reactivity of the short‐lived intermediates may be obtained. The combined use of ESI‐MS in association with other spectroscopic techniques and theoretical calculations is discussed as well. © 2006 Wiley Periodicals, Inc.
Green tea polyphenol (−)‐epigallocatechin‐3‐gallate inhibits cyclooxygenase‐2 expression in colon carcinogenesis
Authors: Peng Guang , Dixon Dan A. , Muga Stephanie J. , Smith Theresa J. , Wargovich Michael J.
Published: February 2006

Tea, one of the most widely consumed beverages worldwide, has been shown to have anti‐cancer activity in various cancers including colon cancer. It has been demonstrated that overexpression of the inducible isoform of cyclooxygenase (COX‐2) occurs during colon tumorigenesis and inhibition of COX‐2 by non‐steroidal anti‐inflammatory drugs (NSAIDs) is chemopreventive. To determine whether the anti‐cancer effect associated with green tea impacted COX‐2 expression levels, human colorectal cancer cell lines HT‐29 and HCA‐7, were treated with (−)‐epigallocatechin‐3‐gallate (EGCG), the most abundant and effective polyphenol of green tea. EGCG significantly inhibited constitutive COX‐2 mRNA and protein overexpression. The inhibitory effects of EGCG on signaling pathways controlling COX‐2 expression were examined. We observed that EGCG downregulated the ERK1/2 and Akt pathways in colon cancer cells. The effect of EGCG on COX‐2 expression resulted in decreased COX‐2 promoter activity via inhibition of nuclear factor κB (NF‐κB) activation. EGCG also promoted rapid mRNA decay mediated through the COX‐2 3′untranslated region (3′UTR). In conclusion, these data suggest that inhibition of COX‐2 is a mechanism for the anti‐proliferative effect of green tea and emphasizes the role that dietary factors have as anti‐cancer agents. © 2006 Wiley‐Liss, Inc.
Germin‐like protein Cit s 1 and profilin Cit s 2 are major allergens in orange (Citrus sinensis) fruits
Authors: Crespo Jesus F. , Retzek Mechthild , Foetisch Kay , Sierra‐Maestro Elena , Cid‐Sanchez Ana B. , Pascual Cristina Y. , Conti Amedeo , Feliu Angelica , Rodriguez Julia , Vieths Stefan , Scheurer Stephan
Published: March 2006

Oranges are clinically relevant allergenic foods. To date, orange allergens have not been characterized in detail. The study is aimed at analyzing the sensitization profile in orange‐sensitized subjects with and without clinical allergy, and to identify orange allergens. Fifty‐six sensitized subjects with self‐reported reactions to orange were grouped into reactors (anaphylaxis or multiple episodes of immediate reactions and/or positive challenge tests) and non‐reactors (negative open food challenge tests). Allergens were characterized by IgE immunoblotting, N‐terminal sequencing, IgE‐inhibition assays, and mediator release assays were performed to determine the allergenic potency of orange profilin. Of 56 subjects, 23 were classified as orange allergic showing mainly an oral allergy syndrome. Of 23 subjects classified as orange allergic, 22 were sensitized to profilin, Cit s 2. In patients with mono‐sensitization to profilin in vitro histamine releases up to 75% from basophils were induced using orange extract and purified plant profilins. Of the allergic patients 78% were sensitized to germin‐like protein, Cit s 1. Both allergens showed retained IgE reactivity in heat‐processed orange juice. Interestingly, subjects with and without clinical allergy showed a comparable sensitization profile. Profilin and germin‐like proteins are major orange allergens. The potential clinical relevance of orange profilin was indicated by its strong capacity to release histamine from basophils. However, a predominant sensitization to both allergens in subjects without symptoms also indicates a high frequency of clinically insignificant sensitization.
Resonances of 2D MESA periodic structures in integrated optics by unit cell structure design
Authors: Massaro Alessandro , Pierantoni Luca , Rozzi Tullio
Published: February 2006

We present a theoretical approach in view to design a 2D MESA periodic structure. The model is based on Floquet's theory under the hypotheses of (i) low dielectric contrast and (ii) absence of corner diffraction, and derives the characteristics equations by the wavenumber conservation. The theory is validated by using a standard FEM simulator, which confirms the location of resonances and gives insight about the electromagnetic field behavior. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 629–632, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21428
Stability of a hybrid FDTD‐circuit model for on‐chip power‐grid switching analysis
Authors: Ihm Jae‐Yong , Cangellaris Andreas C.
Published: February 2006

A circuit model for the package‐to‐chip power grid interface is presented for use in conjunction with the finite‐difference time‐domain (FDTD) simulation of on‐chip power‐grid switching. A numerical scheme is proposed for the integration of the hybrid circuit/FDTD model, the stability of which is dictated by the CFL condition for the FDTD grid and thus is independent of the specific values of the circuit elements in the lumped model. Numerical experiments are performed to demonstrate the numerical stability of the model and its accuracy. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 644–649, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21433
Separated treatment of time and spatial refinement using the FDTD‐3D method
Authors: Denanot Francis , Guiffaut Christophe , Reineix Alain
Published: February 2006

This paper deals with spatial and time refinement using the FDTD‐3D method. An original methodology is presented in which time refinement and spatial refinement with a ratio of two are performed in two separated stage. It aims to simplify algorithms of refinement schemes and to better control the stability and reflection. In particular, a simple time‐refinement scheme is proposed with stability over a long time. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 649–655, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21434
Design of microstrip‐fed proximity‐coupled conducting‐polymer patch antenna
Authors: Rmili Hatem , Miane Jean‐Louis , Zangar Habib , Olinga Thomas
Published: February 2006

A conducting‐polymer patch antenna is fabricated using a screen‐printing technique. Polyaniline (Pani) film of conductivity 6000 S/m, permittivity 6000, and thickness 100 μm is used as a radiating patch to realize a microstrip‐fed proximity‐coupled Pani‐patch antenna operating at around 10 GHz. Ansoft‐HFSS was used as a design tool to validate the experimental measurements of the antenna. The measured and simulated results of the resonant frequency, return loss, gain, bandwidth, and radiation patterns are presented. The simulations and measurements are performed on both copper‐ and Pani‐antennas for comparison. Details of the design considerations and the simulation and experimental results are presented and discussed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 48: 655–660, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21435
Method for measuring target cross sections in the optical band
Authors: Wilfert* Otakar , Kolka Zdenĕk
Published: February 2006

This paper presents the results of measuring relative local target cross sections. The method for calculating the target cross section in the optical band (OCS) on the basis of an experimentally obtained data of a real target is clarified. As an example, the calculation of the OCS of T‐72 tank illuminated by laser beam with a divergence of 1 mrad and a wavelength of 1060 nm is shown. The values of the OCS were calculated for various range levels so that the range dependence of OCS could be presented graphically. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 664–667, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21437
Anisotropic metamaterials as antenna substrate to enhance directivity
Authors: Wu Bae‐Ian , Wang Weijen , Pacheco Joe , Chen Xudong , Lu Jie , Grzegorczyk Tomasz M. , Kong Jin Au , Kao Peter , Theophelakes Paul A. , Hogan Michael J.
Published: February 2006

Simulations have been carried out on metamaterials in the microwave regime. S‐parameters obtained from waveguide simulations of a unit cell are used to retrieve the effective permittivity and permeability with which we compute the far‐field radiation of a monopole embedded in a metamaterial substrate using an analytic method. We find that the analytic method is able to predict features of the experimental results, implying that within a certain frequency range, we can treat the metamaterial as being anisotropically homogeneous. Based on the methodology, a structure is optimized for the application of metamaterials as antenna substrate to enhance directivity by minimizing its refractive index. The experimental results are presented and compared with the analytic calculations. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 680–683, 2006; Pubished online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21441
Computation of antenna directivity from cylindrical near‐field measurements
Authors: Ferrara F. , Gennarelli C. , Guerriero R. , Riccio G. , Savarese C.
Published: February 2006

An effective technique is proposed in this paper for evaluating the directivity of an antenna under test from near‐field measurements on a cylinder. It employs a closed‐form formula for computing the total radiated power from the knowledge of the radiation intensity samples on the far‐field sphere. These samples are determined via a probe‐compensated near‐field–far‐field transformation and result to be even in number on each parallel. The effectiveness of such a procedure is assessed through numerical tests. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 686–691, 2006; Pubished online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21443
An octave‐band smooth‐wall pyramidal horn
Authors: Selvan Krishnasamy T. , Sreenivasan M.
Published: February 2006

A smooth‐wall pyramidal horn offering satisfactory performance over an octave bandwidth (in the frequency range 4–8 GHz) is reported. While the VSWR is 1.5 or better, the pattern and gain characteristics are also acceptable. The experimental results are presented and compared with those obtained by simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 691–693, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21444
Novel compact lowpass filter with CMRC based on defected ground structure
Authors: Chen Ya‐Jun
Published: February 2006

In this paper, we propose a novel defected ground structure (DGS) for lowpass filter applications. The basic resonant element of the proposed DGS unit shows the elliptic characteristics, and two transmission zeros can be realized to extend the stopband. Incorporating compact microstrip resonant cell (CMRC) in microstrip line above the DGS unit improves the rejection level of stopband. The theoretical and measured results are presented and show good agreement. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 695–697, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21446
Influence of losses and dispersion of the reference line of LRM on the parasitic and intrinsic element values of on‐wafer transistors
Authors: Reynoso‐Hernández J. Apolinar , Maya‐Sánchez Ma. Carmen , Zúñiga‐Juárez J. E.
Published: February 2006

In this paper, the parasitic and intrinsic elements of the coplanar PHEMTs are determined from S‐parameter measurements corrected using the classical LRM calibration technique and the improved LRM with a reference line of arbitrary length. For the first time to our knowledge, it is demonstrated that the classical LRM calibration technique overestimates the parasitic inductances. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 701–705, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21448
Optical microphone based on a reflective micromirror diaphragm
Authors: Song Ju‐Han , Gu Hyun‐Mo , Park Hyun‐Jung , Lee Sang‐Shin
Published: February 2006

An optical microphone incorporating a reflective diaphragm and a fiber‐optic head is demonstrated. The diaphragm is made of a micromirror membrane which is suspended by a silicon bar connected to a frame, allowing for displacement induced by acoustic waves. A compact and simple optical head is implemented by exploiting a single multimode fiber. For the assembled microphone, the static characteristics are investigated in order to find the operation point, defined as the optimum distance between the head and the diaphragm, and a flat frequency response with a variation of ∼2 dB for the range of 0.1 to 2 kHz is accomplished. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 707–709, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21450.
Negative phase velocity in isotropic dielectric‐magnetic media via homogenization: Part II
Authors: Lakhtakia Akhlesh , Mackay Tom G.
Published: February 2006

The scope for negative‐phase‐velocity (NPV) propagation in a particulate composite material, based upon isotropic dielectric‐magnetic constituent material phases which do not themselves support NPV propagation, is examined using the extended Bruggeman homogenization formalism. Unlike the conventional Bruggeman formalism, the extended formalism takes into account the dimensions of the constituent particles. Representative calculations show that increasing the particulate dimensions diminishes the scope for NPV propagation in the composite material. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 709–712, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21451.
Frequency‐response simulation analysis of InGaAs/InP SAM‐APD devices
Authors: Pereira Jorge Manuel Torres
Published: February 2006

The frequency response of separate absorption multiplication avalanche photodiodes is investigated with regard to the effect of the absorption‐ and multiplication‐layer widths, the wavelength of the light, and the direction from which the light is injected into the absorption region. The results apply to multilayer structures with an absorption layer of In0.53Ga0.47As and an avalanche layer of InP. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 712–717, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21452.
Compact planar monopole antenna with ground branch for GSM/DCS/PCS/IMT2000 operation
Authors: Sun Peng , Feng Zhenghe
Published: February 2006

A novel compact antenna operating at GSM, DCS, PCS and IMT2000 bands is presented. With a loosely coupled ground branch, the antenna covers all 2‐G and 3‐G wireless communication bands of GSM(890–960 MHz), DCS(1710–1880 MHz), PCS(1850–1990 MHz), IMT2000 (1920–2170 MHz). © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 719–721, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21454.
Gain‐clamped Raman fiber amplifier in a counter‐lasing ring‐cavity using a pair of circulators
Authors: Ahmad A. , Md Ali M. I. , Zamzuri A. K. , Mohamad R. , Mahdi M. A.
Published: February 2006

An all‐optical gain‐clamped Raman fiber amplifier (RFA) based on the ring‐lasing technique using a pair of circulators is demonstrated experimentally. The RFA is powered using a pair of 1465‐nm pump laser diodes, which provide a peak gain at around 1565 nm. The analyses of the gain and the noise figure are carried out using different lasing wavelengths between 1550 and 1565 nm. The gain and noise figure variations are 0.4 and 0.5 dB in the gain‐clamping range, respectively. We observe a strong influence of pump‐signal relative‐intensity noise transfer, which results in a noise‐figure penalty at the signal. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 721–724, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21455
Microstripline‐fed half‐cylindrical dielectric resonator antenna for 2.4‐GHz WLAN application
Authors: Praveen Kumar A. V. , Hamsakutty V. , Yohannan Jaimon , Mathew K. T.
Published: February 2006

A compact half‐cylindrical dielectric resonator antenna (DRA) made from a high‐permittivity (εr = 69) ceramic material is investigated. A microstrip transmission line excites the DRA. The DRA shows broad and stable radiation characteristics across a matching band of 2.32 to 2.5 GHz with peak gains of 5.5 dBi in the elevation plane and 3.6 dBi in the azimuth plane. The results lead us to propose this DRA for 2.4‐GHz WLAN (2.4 to 2.484 GHz) application. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 724–726, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21456
Accurate modeling of the cylindrical wire kernel
Authors: Mohan Anuraag , Weile Daniel S.
Published: February 2006

Many existing numerical techniques used to analyze wire antennas assume the current distribution on the wire to be one‐dimensional (1D). This assumption imposes geometric constraints on the ratio of the wire radius to the discretized antenna segment length. Moreover, many kernel approximations are so inaccurate that higher‐order basis functions for wire modeling are unthinkable. More accurate kernel models are possible, but generally result in infinite series or require complicated integration rules. This work presents a new generalized approach to the modelling of cylindrical wire antennas. The method is not plagued by the aforementioned geometric restrictions and can be extended to model the higher‐order behavior of wires. The numerical results show the method to be both stable and robust. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 740–744, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21461
Modified pulse shaper design with picosecond duration and wideband response for UWB applications
Authors: Liu Ji‐Chyun , Lu Shuh‐Tai , Wu Ching‐Yang , Liu Chin‐Yen , Chiang Ming‐Hsun
Published: February 2006

A simple, compact pulse shaper of inverse Gaussian monocycle with picosecond duration and wideband response is proposed in this paper. By modifying the conventional pulse shaping circuit, the pulse shaper utilizes the RC differentiator and Schottky diode to construct the clamping circuit, and form an inverse Gaussian monocycle pulse. In addition, the short‐stub is used for constructing the resistive matching network as well as adjusting the shape of inverse Gaussian monocycle pulse. In applications, an ultra‐short inverse Gaussian monocycle pulse with duration of 600 ps, symmetry of 100%, and ring level of 5.8% has been obtained. Meanwhile, the frequency response presents the characteristic of wideband spectrum with a −3‐dB BW of 141.7%. Both the measured and simulated results are in good agreement with the time and frequency responses. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 744–749, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21462
A microstrip‐fed printed crossed dipole for wireless applications
Authors: Leon Lerma F. , Ruvio G. , Ammann M. J.
Published: February 2006

A crossed‐dipole antenna with good directivity and good isolation between ports over a wide impedance bandwidth is presented. This antenna offers polarization diversity and employs an optimized shape for the dipole wing, which yields the wide bandwidth. A quarter‐wave balun is used for matching and improved isolation. Patterns are also presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 751–753, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21464
Design and analysis of on‐package dual‐mode band pass filters for highly integrated wireless transceivers
Authors: Tong Ming‐Sze , Chen Yinchao , Cao Qunsheng , Yang Mingwu , Sauleau Ronan
Published: February 2006

In this paper, various planar printed microwave bandpass filters (BPFs) are designed and analyzed by applying a nonuniform finite‐difference time‐domain (NU‐FDTD) method. These filters, referred to as integrated‐circuit package filters (ICPFs), are designed in such a way that they operate in dual mode (DM), that is, at TM and TM, to ensure a good electric performance at the center frequency. They operate at 2.4 and 5.25 GHz, which are the frequencies allocated to wireless local area networks (WLANs). The frequency characteristics in terms of the scattering parameters are taken for analysis, and the results are compared to the measurements as well as the computed results using High‐Frequency Structure Simulator (HFSS) software. The results show excellent agreement between the numerical and experimental data, and the proposed DM‐ICPF structures can be applied to on‐package highly integrated wireless transceiver systems. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 756–760, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21466
Nonsingular boundary integral equation for two‐dimensional electromagnetic scattering problems
Authors: Young D. L. , Chiu C. L. , Fan C. M.
Published: February 2006

This paper is concerned with the application of the nonsingular boundary integral equation (NSBIE) for 2D electromagnetic scattering problems in the frequency domain. In the proposed NSBIE, the conventional treatment of the singular integral for the boundary integral equation is circumvented by employing the Gauss flux theorem and the concept of equipotential. Then the NSBIE for the Helmholtz equation is used to predict the scattering of plane wave by a perfectly electric conducting circular cylinder of infinite length at normal incidence. Based on the good results, as compared with solutions of the analytical and boundary‐element methods, it is verified that the NSBIE is a highly simple and efficient numerical scheme for 2D electromagnetic scattering simulations. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 760–765, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21467
Very compact ortho‐mode transducers with double septum configuration
Authors: Ruiz‐Cruz Jorge A. , Montejo‐Garai José R. , Rebollar Jesús M. , Montesano Carlos E. , Martín María J.
Published: February 2006

This paper describes the analysis and design results of a very compact ortho‐mode transducer (OMT) for dual‐polarization communication systems. The presented configuration introduces an additional double septum in the conventional structure, not reported previously, which provides a number of advantages for some of the usual requirements of this type of OMTs. Specifically, the double‐septum configuration enhances the performance of the OMT in two interrelated aspects: (i) it contributes to reduce the size of the axial branch of the OMT preventing the power transfer between horizontal modes at the axial and common ports; (ii) it facilitates the matching of the horizontal polarization between the lateral and common ports. The presented design leads to a very interesting structure for coping with competitive specifications. The proposed structure is validated using a prototype onboard the Hispasat 1D satellite. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 765–767, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21468
A broadband internal planar monopole antenna for mobile phone
Authors: Shen Chao‐An , Lin Ken‐Huang
Published: February 2006

In this paper, we design and fabricate a broadband interior‐type planar monopole with an omnidirectional radiation pattern over a wide operation band using a slanted feeding shape. It has a measured 10‐dB impedance bandwidth of about 670 MHz (1585–2255 MHz) covering the DCS (digital cordless system, 1710–1880 MHz), PCS (personal communication system, 1850–1990 MHz), and UMTS (universal mobile telecommunication system, 1920–2170 MHz) bands. The slanted feeding shape can obtain the compensation of the input reactance and reduce the antenna height. This planar monopole antenna has a height of only 15 mm and can provide more space for the system ground plane in mobile handsets. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 768–769, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21469
A novel V‐band 90° hybrid using surface micromachining technology
Authors: Chun Young‐Hoon , Moon Ju‐Young , Ko Baek‐Seok , Baek Tae‐Jong , Kim Sung‐Chan , Lim Byoung‐Ok , Rhee Jin‐Koo , Shin Dong‐Hoon
Published: February 2006

A novel 90° hybrid at the V‐band using surface micromachining technology is designed and measured. It employs a uniplanar structure which is composed of parallel coupled microstrip lines and delay lines. Compared with the conventional hybrids, cascaded parallel coupled lines with delay lines can make the coupling tighter as the number of coupled lines grows. The measured insertion loss is less than 2 dB and the phase imbalance is less than ±5° at 60 GHz. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 770–771, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21470
Comparison of possible implementations of nonmechanical optical beam steering using phased arrays of vertical cavity lasers and amplifiers
Authors: Xing Cheng , Mankondo O.L.M. , Avrutin E.A.
Published: February 2006

We theoretically study the far‐field pattern of vertical‐cavity semiconductor laser (VCSEL) arrays and vertical cavity amplifier/modulator arrays. A comparison is made between the laser and amplifier array for the purpose of nonmechanical optical beam steering. The amplifier/modulator array shows superior potential over the laser arrays. The realisation of practical devices depends on the fabrication technology. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 772–775, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21471
A modified HICUM model for GaInP/GaAs HBT devices
Authors: Tseng S.‐C. , Meng C. C. , Chen W.‐Y. , Su J.‐Y.
Published: February 2006

A compact physics‐based transit‐time model is established for the GaInP/GaAs HBT device. The VBIC model fails to describe the transit‐time frequency versus bias (IC, VCE), especially at low‐ and medium‐current regimes. Starting with the HICUM model, we introduce a new time constant to describe the transit‐time frequency versus bias (IC, VCE) more precisely. This model has obvious advantages over the VBIC model for showing the relation of ft versus bias (IC, VCE) in the low and medium current regimes for GaInP/GaAs HBT devices. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 780–783, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21474
Nonoverlapping domain decomposition method for the capacitance extraction of multilayered multiconductor transmission lines
Authors: Zhu Hanqing , Liu Shujing , Hong Wei
Published: February 2006

In this paper, the nonoverlapping domain decomposition methd (NDDM) is used to compute the capacitance matrix of multiconductor transmission lines in multilayer dielectric media. The subdomains with pure dielectric layers are analyzed using the method of lines (MoL), and fast Fourier transform (FFT) is introduced to reduce the computing time, while the subdomains with conductors are analyzed using the finite‐difference method. The numerical results show that the algorithm is efficient, and the computing time and memory needs are unrelated to the thickness of the pure dielectric layers. In addition, the effect of the uneven dielectric division on the electromagnetic parameter is also investigated. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 794–798, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21478
Controlling the scattered field in a reflectarray element using a novel technique
Authors: Cabria L. , Garcia J. A. , Mediavilla A.
Published: February 2006

In this paper, a novel gain/phase adjustment unit to be employed as the cell of an active reflectarray is proposed. Based on accurate control of PHEMT behaviour in normal and inverse operation, a dual‐device variable‐gain biphase amplifier (VGBPA) has been designed for each branch of such an IQ modulator. Its proper integration in a dual‐feed aperture‐coupled square patch allows the use of orthogonal polarizations for retransmitting the received signal after selecting the desired amplitude and phase for the scattered field. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 808–810, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21481
A compact‐sized microstrip antenna for GPS applications
Authors: Chou Hsi‐Tseng , Chiu Yi‐Ling
Published: February 2006

A microstrip antenna structure is proposed for global positioning system (GPS) applications. This structure is intended to reduce the antenna size at low cost in order to fulfill the increasing needs of mobile devices with GPS functions. Thus, dielectric slabs with low relative permittivity, which can be commonly available on the market at a low cost, are employed. The size reduction is achieved by cutting slits and L‐slots on the surface of the microstrip metal patch in order to lower the resonance frequency of the structure. The numerical and experimental results verify that the antenna design can improve the wide‐angle axial ratio in addition to size the reduction with insignificant reduction of the operation‐frequency bandwidth (still fully sufficient to cover the GPS frequency band). © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 810–814, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21482
A novel multiband and broadband fractal patch antenna
Authors: Huang Jingjing , Shan Fuqi , She Jingzhao , Feng Zhenghe
Published: February 2006

A novel multiband and broadband fractal patch antenna is presented in this paper. The proposed antenna is compact and simple to design and fabricate. The impedance bandwidth can reach 18%, which is rarely reported for single‐layer and single‐patch antennas. Multiband characteristics are also observed and analyzed. All the results are proved by simulation and experiment. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 814–817, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21483
Multiband multiport direct conversion receiver: Design, implementation, and demodulation results
Authors: Tatu Serioja O. , Wu Ke , Denidni Tayeb A.
Published: February 2006

An experimental receiver prototype operating over the S‐, C‐, and X‐bands, based on a MHMIC multiport, is designed, fabricated, and measured. Comparative simulation and measurement results for 8PSK modulated signals are presented and discussed. The RF input power sweep and the DC offset of the proposed multiport demodulator are particularly analyzed. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 817–822, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21484
Implementation of a trapezoidal‐rule microwave integrator
Authors: Hsue Ching‐Wen , Tsai Lin‐Chuan , Kan Shih‐Tsung
Published: February 2006

The bilinear transformation is employed to represent the trapezoidal‐rule integrator in the Z domain. This formulation, in conjunction with the representations of transmission‐line elements in the Z domain, leads to the transmission‐line configuration that is eligible for a microwave integrator. A microstrip circuit is implemented to verify the feasibility of the technique. Except for the lower‐frequency band, the experimental results are in good agreement with the theoretical values of the trapezoidal‐rule integrator. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 822–825, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21485
Capacitance of axially slotted coaxial cable
Authors: Kim Dong H. , Eom Hyo J.
Published: February 2006

The electrostatic potential problem of an axially slotted coaxial cable is solved. A mode‐matching technique is used to obtain a set of simultaneous equations for the modal coefficients. The behavior of electrostatic potential distribution and capacitance is presented in terms of slotted coaxial cable geometries. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 825–827, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21486
Acute inflammatory demyelinating polyneuropathy: Contribution of a dispersed distal compound muscle action potential to electrodiagnosis
Authors: Cleland James C. , Malik Khizar , Thaisetthawatkul Pariwat , Herrmann David N. , Logigian Eric L.
Published: March 2006

Prolonged duration of the distal compound muscle action potential (DCMAP) (“DCMAP dispersion”) is useful in the electrodiagnosis of chronic inflammatory demyelinating polyneuropathy (CIDP) with good specificity in distinguishing CIDP from amyotrophic lateral sclerosis (ALS) and diabetic polyneuropathy, but its role in the electrodiagnosis of acute inflammatory demyelinating polyneuropathy (AIDP) is unclear. This study addresses this issue by determining the optimal cutoff for DCMAP duration using receiver operating characteristic (ROC) analysis in 207 motor nerves from 53 clinically defined AIDP patients compared to 148 motor nerves from 55 ALS patients. We also determined whether the presence of DCMAP dispersion improves the sensitivity of four of the most sensitive published sets of electrodiagnostic criteria for AIDP. Using the ROC‐derived optimal DCMAP duration cutoff of 8.5 ms, DCMAP dispersion was found in at least one motor nerve in 66% of subjects with AIDP compared to 9% of subjects with ALS. DCMAP dispersion improved the sensitivity of the four tested criteria sets to 76%–87% from 43%–77%. Moreover, of 13 AIDP patients who met none of the four published criteria sets, 5 (38%) had at least one dispersed DCMAP. These findings indicate that the presence of DCMAP dispersion adds electrodiagnostic sensitivity to the currently published criteria sets, while maintaining reasonably high specificity against a prototypical disorder of the primary motor neuron with axon loss. Muscle Nerve, 2006
Spectrum policy issues for state and local government
Authors: Jesuale Nancy
Published: March 2006

This paper describes challenges in the United States faced by local and state governments in providing advanced technical infrastructure for efficient delivery of public services, under current and proposed federal spectrum and telecommunications policy. The potential impact of new wireless communications technologies, particularly cognitive radio and broadband convergence, is discussed. Within this context, the U.S. spectrum policy issues important to state and local governments are highlighted. Copyright © 2006 John Wiley & Sons, Ltd.