bluuebunny/crossref_metadata_2025 huggingface dataset:
Alterations in the spatiotemporal expression pattern and function of N‐Cadherin inhibit cellular condensation and chondrogenesis of limb mesenchymal cells in vitro
Authors: DeLise Anthony M. , Tuan Rocky S.
Published: October 2002

Cartilage formation in the embryonic limb is presaged by a cellular condensation phase that is mediated by both cell–cell and cell–matrix interactions. N‐Cadherin, a Ca2+‐dependent cell–cell adhesion molecule, is expressed at higher levels in the condensing mesenchyme, followed by down‐regulation upon chondrogenic differentiation, strongly suggesting a functional role in the cellular condensation process. To further examine the role of N‐cadherin, we have generated expression constructs of wild type and two deletion mutants (extracellular and intracellular) of N‐cadherin in the avian replication‐competent, RCAS retrovirus, and transfected primary chick limb mesenchymal cell cultures with these constructs. The effects of altered, sustained expression of N‐cadherin and its mutant forms on cellular condensation, on the basis of peanut agglutinin (DNA) staining, and chondrogenesis, based on expression of chondrocyte phenotypic markers, were characterized. Cellular condensation was relatively unchanged in cultures overexpressing wild type N‐cadherin, compared to controls on all days in culture. However, expression of either of the deletion mutant forms of N‐cadherin resulted in decreased condensation, with the extracellular deletion mutant demonstrating the most severe inhibition, suggesting a requirement for N‐cadherin mediated cell–cell adhesion and signaling in cellular condensation. Subsequent chondrogenic differentiation was also affected in all cultures overexpressing the N‐cadherin constructs, on the basis of metabolic sulfate incorporation, the presence of the cartilage matrix proteins collagen type II and cartilage proteoglycan link protein, and alcian blue staining of the matrix. The characteristics of the cultures suggest that the N‐cadherin mutants disrupt proper cellular condensation and subsequent chondrogenesis, while the cultures overexpressing wild type N‐cadherin appear to condense normally, but are unable to proceed toward differentiation, possibly due to the prolonged maintenance of increased cell‐cell adhesiveness. Thus, spatiotemporally regulated N‐cadherin expression and function, at the level of both homotypic binding and linkage to the cytoskeleton, is required for chondrogenesis of limb mesenchymal cells. J. Cell. Biochem. 87: 342–359, 2002. Published 2002 Wiley‐Liss, Inc.
Osteogenic protein‐1 (OP‐1, BMP‐7) induces osteoblastic cell differentiation of the pluripotent mesenchymal cell line C2C12
Authors: Yeh Lee‐Chuan C. , Tsai Alicia D. , Lee John C.
Published: October 2002

The effects of Osteogenic Protein‐1 (OP‐1, BMP‐7) on the differentiation of the pluripotent mesenchymal cell line, C2C12, were examined. OP‐1 at 50 ng/ml partially inhibited myotube formation in C2C12 cells, while OP‐1 at 200 ng/ml completely inhibited myotube formation and induced the formation of cells displaying osteoblastic morphology. High concentrations of OP‐1 elevated the alkaline phosphatase (AP) activity dramatically, both as a function of time and OP‐1 concentration. Osteocalcin (OC) mRNA expression was detected as early as 8 days in OP‐1‐treated cultures and subsequently increased considerably. Expression of bone sialoprotein (BSP) mRNA was low in control cultures and stimulated by OP‐1. Collagen type I mRNA expression was enhanced by OP‐1 during the early days in culture, but gradually decreased thereafter. MyoD mRNA expression, high in control cultures, was suppressed by OP‐1 in a dose‐ and time‐dependent manner. OP‐1 enhanced ActR‐I mRNA expression and significantly elevated the mRNA expressions of BMP‐1, BMP‐4, BMP‐5, GDF‐6, and GDF‐8. The present results indicate that OP‐1 is a potent inducer of C2C12 differentiation into osteoblastic cells. J. Cell. Biochem. 87: 292–304, 2002. © 2002 Wiley‐Liss, Inc.
Development of bow‐tie antenna with an orthogonal feed
Authors: Teo P. T. , Lee K. S. , Gan Y. B. , Lee C. K.
Published: October 2002

A bow‐tie element with an orthogonal feed arrangement has been developed to conform to the shape of a handheld device. An improved method to feed the bow‐tie antenna was realised, which includes modification to the printed Roberts balun with stubs to provide an exact feed location and broadening of the sharp edges at the feed positions of the bow‐tie elements. A wideband antenna (maximum bandwidth of 22.8%) with dual band characteristics will be shown. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 255–257, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10575
A comparison of the performance properties of the Hilbert curve fractal and meander line monopole antennas
Authors: Best Steven R.
Published: October 2002

In this paper, the performance properties of the Hilbert curve fractal monopole are compared with those of simple meander line monopoles. It is demonstrated that small meander line monopoles of the same size and wire length as the Hilbert fractal exhibit similar behavior and performance independent of the difference in their respective geometries. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 258–262, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10576
Effect of mutual coupling in adaptive arrays
Authors: Ali Maha A. , Wahid Parveen
Published: October 2002

In this paper, the effect of mutual coupling on adaptive array antenna is investigated. Through an example of a two‐element dipole array, it is shown that the effect of the mutual coupling is detrimental on adaptive array and can not be neglected. A method proposed in the literature to compensate for the effect of mutual coupling is tested and applied successfully. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 270–274, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10579
Dual‐frequency small‐chip meander antenna
Authors: Kim Hyun Jun , Kwon Sewoong , Sim Sung Hun , Yoon Young Joong , Kim Huyn Jai , Yoon Seok Ji , Kang Chong‐Yun
Published: October 2002

In this paper, a small‐chip meander antenna for dual‐frequency operation is presented. This novel compact dual‐frequency antenna uses a meander patch with increased capacity to adjust dual operating frequencies with small size and frequency ratio. The proposed antennas are fabricated by the LTCC‐MLC process. The characteristics of return losses, radiation patterns, and gains are discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 274–277, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10580
Modeling and prediction of the wireless vector channel encountered by smart antenna systems
Authors: Dandekar Kapil R. , Arredondo Alberto , Ling Hao , Xu Guanghan
Published: October 2002

In this paper, a Kalman‐filter‐based, vector autoregressive (VAR) model is used to forecast mobile user uplink spatial signatures and improve downlink signal‐to‐interference ratio in time‐division duplex (TDD) systems. Results are presented from computational electromagnetic (CEM) simulations of a smart antenna system operating at 1.8 GHz in an urban microcellular environment. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 281–283, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10582
Addendum to: Picosecond pulse generation for visible semiconductor laser operating at 650‐NM wavelength with the use of the gain‐switching technique
Authors: Oh Kwang H. , Hwang N. , Koh J. S. , Kim Dug Y.
Published: October 2002

Originally published Microwave Opt Technol Lett 35: 65–67, 2002. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 342–342, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10584
Impedance formulas of RF patch resonators and antennas of cavity model using fringe extensions of patches from DC capacitors
Authors: Sun Y. X. , Chow Y. L. , Fang D. G.
Published: October 2002

Fringe field effect is equivalent to an extension in size of an RF patch, either as resonator or as antenna. A CAD formula for this extension is derived from DC capacitor and is shown to be applicable for all practical thickness and permittivity εr of the substrate. For example, for patch resonators of large εr and for patch antennas on thick substrate (h/λ0 < 0.23), the maximum errors in resonant frequencies are only 0.2% and 3%, respectively. The fringe extension through DC is understandable in physics from the point of view of the frequency invariance of fringe field with thin substrate asymptotically. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 293–297, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10587
Dielectric properties of urinary stones at microwave frequencies
Authors: Paul Issac , Varghese George , Ittyachen M. A. , Mathew K. T. , Lonappan Anil , Jacob Joe , Kumar S. Biju
Published: October 2002

Microwaves play a vital role in the diagnosis and treatment of diseases caused by the abnormal mineralization of biological fluids in human body. First hand information regarding the dielectric behavior of these minerals facilitates to detect these crystals. This paper attempts a comparative study of the dielectric properties of urinary crystals grown in vitro by gel technique with natural stones procured from patients who had undergone stone removal surgery. Cavity perturbation technique was employed and measurements were made in the S band. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 297–299, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10588
Dual‐band slot antenna for 2.4/5.2 GHz WLAN operation
Authors: Su Chih‐Ming , Chen Hong‐Twu , Chang Fa‐Shian , Wong Kin‐Lu
Published: October 2002

A dual‐band slot antenna comprising two narrow linear slots for wireless local area network (WLAN) operations in the 2.4 GHz (2.4–2.484 GHz) and 5.2 GHz (5.15–5.35 GHz) bands is presented. The two linear slots are arranged to be close and in parallel to each other, and are easily fed by using a single 50 Ω coaxial cable to achieve two desired operating modes at about 2.4 GHz and 5.2 GHz. A prototype of the proposed antenna with a narrow width of 10 mm suitable to be placed along the perimeter of the display of a notebook computer is constructed and studied. Experimental results of the constructed prototype are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 306–308, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10591
On the resonant behavior of the small Koch fractal monopole antenna
Authors: Best Steven R.
Published: October 2002

The resonant behavior of the Koch fractal monopole is considered as a function of its geometry, height and wire length. It is demonstrated that the resonant behavior of the Koch fractal is not uniquely determined by its geometry and that optimum resonant performance is exhibited by the simple Euclidean monopole. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 311–315, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10593
A circular planar inverted‐L antenna with a vertical ground plane
Authors: Chen Zhi Ning , Chia M. Y. W.
Published: October 2002

A new broadband planar inverted‐L antenna (PILA) with a vertical ground plane (VGN) is experimentally presented. With the electromagnetic coupling between the radiator and VGN, the 2:1 VSWR impedance bandwidth of > 45% has been attained. The radiation patterns similar to those of conventional planar inverted‐ L or F antennas are applicable for land mobile communication systems. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 315–317, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10594
Application of FFT to light scattering from one‐dimensional fractal rough surface
Authors: Lixin Guo , Zhensen Wu
Published: October 2002

The problem of light scattering from a one‐dimensional dielectric fractal rough surface is investigated using Fourier transform within the limitation of the Kirchhoff approximation. A numerical formula for the scattering coefficient is obtained by theoretical derivation. The scattering coefficient is calculated and compared to both the FFT method and the classical Kirchhoff approximation integral solution. This FFT method solves the problem of edge effect that is neglected in the numerical study by the conventional Kirchhoff approximation. The dependence of the distribution of the scattering coefficient on the patch size, the fundamental spatial wave number, and the fractal dimension of the surface are discussed in detail. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 317–322, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10595
Improved equivalent circuit model of practical coupled‐cavity slow‐wave structures for TWTs
Authors: Christie V. Latha , Kumar Lalit , Balakrishnan N.
Published: October 2002

The existing equivalent circuit model of space‐harmonic coupled‐cavity slow‐wave structures was extended to model structures with double slots and tapered or step‐tapered ferrules. This model was validated by comparing its results for dispersion and total impedance characteristics of typical slow‐wave structures operating in S‐band, with those obtained by computer simulation using the 3D Maxwell equation solver MAFIA.* This model was also validated with the experimental results of a particular double‐slot structure at S‐band. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 322–326, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10596
Transient response of wavelength‐switchable Erbium‐doped fiber lasers with linear coupled cavities
Authors: Mao Qinghe , Lit John W. Y.
Published: October 2002

The transient characteristics of an erbium‐doped fiber (EDF) laser, which can switch between wavelengths, are investigated. The laser has a set of coupled linear cavities. The slow gain dynamics of EDFs and the cross‐gain saturation in the coupled cavities give rise to delayed switching responses and relaxation oscillations, which are respectively measured to be 1 ms and 3.5 ms for the worst case, and which may be decreased by increasing the pump power. Thus, the switching speed of the laser may be higher than 100 Hz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 330–333, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10598
A novel algorithm to simulate DWDM transmission systems amplified by backward multi‐pumped fiber Raman amplifiers
Authors: Tong Zhi , Wei Huai , Jian Shuisheng
Published: October 2002

We propose a new and efficient numerical algorithm to simulate DWDM transmission systems amplified by backward multi‐wavelength‐pumped Raman amplifiers. In this model, system impacts caused by dispersion, nonlinearity, and ASE are considered, and calculated results have satisfying accuracy. As an application, we model a 64 × 10 Gb/s Raman broadband multi‐span system, and arrive at some useful conclusions. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 333–337, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10599
Modulation of THz radiation by semiconductor nanostructures
Authors: Kleine‐Ostmann T. , Koch M. , Dawson P.
Published: October 2002

In this paper we discuss the possibility of an electrically controlled THz modulator based on a gated two‐dimensional electron gas structure. To investigate the modulation capabilities of such a structure, we performed calculations based on the Drude model. Results caused by the change in intensity and phase of transmitted THz radiation induced by changes in the confined electron density are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 343–345, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10601
Group delay measurement of WDM components using photonic microwave technique
Authors: Yi Xiaoke , Wei Fang , Wang Yixin , Lu Chao , De Zhong Wen
Published: October 2002

In this paper we propose a new method for the measurement of the relative group delay of WDM components, based on photonic microwave technique using a low frequency (below 1.3 GHz) scalar network analyzer. Experimental results demonstrate that this technique has the advantages of low cost, simplicity, and high accuracy (less than ±1 ps). © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 346–348, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10602
A continuous hybrid approach to the FET modelling for the maximum transducer power gain
Authors: Günel Tayfun
Published: October 2002

In this work, a continuous hybrid approach (CHA) to the determination of the FET model elements for the maximum transducer power gain in a frequency band is presented. The CHA is based on a continuous parameter genetic algorithm and a controlled random search algorithm. The result obtained from the CHA are compared with the results obtained from the different types of genetic algorithm. The CHA gives better design than the others. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 348–351, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10603
Envelope full‐wave 3D finite element time domain method
Authors: Frasson A. M. F. , Hernández‐Figueroa H. E.
Published: October 2002

A three‐dimensional finite‐element time domain scheme based on the envelope approach is presented for the first time. In this approach the fast wave component or carrier is removed from the field and the envelope is solved instead. This strategy permits longer time steps than when the carrier is included, for the same spatial refinement. The unconditionally stable and second‐order accurate Newmark scheme, in conjunction with tetrahedron edge elements and absorbing boundary condition (ABC) method was adopted. Key numerical results validate and show the efficiency and usefulness of the present algorithm. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 351–354, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10604
An optical receiver circuit for on‐line fiber‐optic characteristics monitoring
Authors: Cheng Wen‐Ming , Tsao Shyh‐Lin
Published: October 2002

A low‐cost optical receiver circuit, which includes a photodiode preamplifier, an active band‐pass filter, and an instrumental amplifier is experimentally achieved. Using the proposed circuit for measurement and on‐line automatic monitoring in this paper, the efficiency of fiber‐optic characteristics monitoring can be enhanced and on‐line noise interference can be suppressed. The transfer functions and frequency response of the optical receiver are derived. The signal‐to‐noise ratio of the on‐line fiber‐optic characteristics monitoring system can be improved using this low‐cost optical receiver. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 354–357, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10605
Model device parameters for a 10‐Gb/s HEMT modulator driver IC
Authors: Jianjun Gao , Baoxin Gao , Bo Pan , Chunguang Liang
Published: October 2002

This paper presents research on device parameters for a 2.5–10‐Gb/s high electron mobility transistor (HEMT) modulator driver IC. The effect of DC and capacitance parameters on the driver IC is discussed, and their ability to meet the requirements of the driver IC are calculated. The results shown agree with experimental data. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 357–360, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10606
Multi‐band operation of a compact H‐shaped microstrip antenna
Authors: Sheta Abdel Fattah , Mohra Ashraf , Mahmoud Samir F.
Published: October 2002

In this paper, a multi‐band compact H‐shaped microstrip antenna is studied. The resonant modes of the H‐shaped structure are analyzed using the concept of electric and magnetic walls at the planes of symmetry. A flexible design approach that allows the pre‐selection of the resonant frequencies of the antenna is described. Approximate design equations and curves are introduced and validated by simulated and experimental results. An H‐shaped antenna is designed to support modes with resonance at 2.2, 2.8, 3, and 5 GHz. It is shown that dual‐, triple‐, or quad‐band operation is possible by the proper location of a coaxial feed. Such antennas are implemented on duroid dielectric substrate with εr = 2.2 and h = 1.57 mm. The designed antennas are simulated by IE3D software and a good agreement with experimental results is demonstrated. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 363–367, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10608
On the multiband behavior of the Koch fractal monopole antenna
Authors: Best Steven R.
Published: October 2002

In this paper, the multiband behavior of the Koch fractal monopole is considered as a function of its self‐similar geometry, height, and wire length. It is demonstrated that the outline shape and wire compression of its self‐similar geometry are primary factors in determining its multiband behavior. However, this behavior is not unique to the geometric details of the self‐similar fractal geometry. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 371–374, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10610
2D generalized transmission‐line equations for a microstrip cross
Authors: Hong J. S. , Liu Y. W. , Wang B.‐Z. , Yan S. H. , Mei K. K.
Published: October 2002

In this paper, a rigorous analysis for a microstrip cross is presented by using 2D generalized transmission‐line equations. The 2D generalized transmission‐line equation is developed from the 1D generalized transmission‐line equation in [1], which was derived from circuit theory, while the equation coefficients are determined from full‐wave numerical solutions. Although 1D generalized transmission‐line equation can well model many microstrip structures, such as discontinuities and low‐pass filters, it is confined to be used for those structures which can be regarded as 1D finite‐length nonuniform transmission‐line. For a microstrip cross, the novel 2D generalized transmission‐line equation whose coefficients are determined by dynamic numerical methods can have broadband frequency characteristics. For the investigated microstrip cross, the S parameters for a frequency band from 4 GHz to 24 GHz can be calculated by using only one group of the 2D generalized equation at frequency of 14 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 378–380, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10613
An efficient method to optimize gain spectra of fiber Raman amplifiers pumped by multiple laser diodes
Authors: Tong Zhi , Wei Huai , Jian Shuisheng
Published: October 2002

We propose a new and efficient method to optimize the output gain profile based on the characteristics of a WDM pumped Raman gain spectra and the fact that different wavelength pumps have different impacts on the gain tilt. As an application, we optimize a 10 wavelength pumped fiber Raman amplifier in a short time, and a 80 nm flat gain band with less than 0.4 dB ripple has been derived. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 381–383, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10614
Wavelet‐based sparse approximate inverse preconditioned CG algorithm for fast analysis of microstrip circuits
Authors: Chen R. S. , Tsang K. F. , Mo Lei
Published: October 2002

In this paper, the wavelet transform technique is used to transform dense matrix equations from the mixed potential integral equation (MPIE) to obtain sparse matrix equations, after dropping elements smaller than the threshold. The multifrontal method is employed to solve the resultant sparse approximate‐inverse preconditioning equation for the preconditioned conjugate gradient (CG) algorithm, in order to enhance its computational efficiency. Our numerical calculations show that the preconditioned CG algorithm, with this wavelet‐based sparse approximate inverse as preconditioner, can converge 23.43 times faster than the conventional one for 2048 unknowns. Some typical microstrip discontinuities are analyzed and the good results achieved demonstrate the validity of the proposed algorithm. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 383–389, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10615
Irradiating micro‐organisms on floors with a focalised structure composed of two patch antennas
Authors: González‐Posadas V. , Rodríguez Martín J. M. , Segovia‐Vargas D. , Rajo‐Iglesias E. , Vázquez‐Roy J. L. , Martín‐Pascual C.
Published: October 2002

This paper presents an open radiating structure composed of two patch antennas in their main radiation mode working in the near‐field or Rayleigh region. We describe how the structure was built and our simulations and measurements have proven the performance of the irradiator. The radiating structure must radiate uniformly on a planar surface to ease the radiation of biological samples. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 389–393, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10616
An improved formula for the fundamental TM‐mode cutoff wavenumber of arbitrary waveguides
Authors: Zhou Xingling
Published: October 2002

This paper presents an improved formula for the fundamental TM‐mode cutoff wavenumber of an arbitrary waveguide based on two independent isoperimetric inequalities and the introduction of a new global integral geometry quantity p. A lot of classic examples show its accuracy and validity for computer‐aided design (CAD). The maximum relative error is less than 1% in most cases and less than 2% even for extreme cases. Note that the mathematical techniques employed here are elementary. Some basic observations about the method are discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 393–396, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10617
Numerical implementation of exact analytical solution for oblique propagation in a cholesteric liquid crystal
Authors: Polo John A. , Lakhtakia Akhlesh
Published: October 2002

An exact matrix polynomial series solution for oblique propagation in a cholesteric liquid crystal, reported in this journal some years ago, was numerically implemented. After a slight reformulation, it was found that numerical results can be accurately and quickly obtained with a simple desktop computer. With the high accuracy available, boundary value problems can be solved very easily. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 397–400, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10618
Reflection coefficient of a flanged rectangular waveguide radiating into a dielectric slab
Authors: Park Mi Y. , Eom Hyo J.
Published: October 2002

In this paper, the reflection coefficient of a flanged rectangular waveguide radiating into a dielectric slab is rigorously studied with the Fourier transform and mode‐matching technique. Residue calculus is used to convert the reflection coefficient into rapidly convergent series. Computations are performed to illustrate the numerical efficiency of the reflection coefficient. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 401–404, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10619
Radiation pattern control by subreflector shaping in a dual‐reflector antenna
Authors: Bergmann J. R. , Pereira L. C. Palma
Published: October 2002

Dual‐shaped reflector antennas have applications in satellite communications systems in which the highest antenna gain and stringent specifications on cross‐polarization are required. For antennas fed by a single feed, the radiation pattern control is obtained either by shaping one of the reflectors or by simultaneously shaping both reflector surfaces. In this paper, we explore the design of Gregorian configurations where the main reflector is an offset paraboloid and the subreflector is shaped so as to attain the coverage specifications. By considering the specifications for a high‐efficiency ground‐station antenna and a contoured beam antenna, two design examples are presented. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 408–412, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10621
A new planar‐type GaAs dielectric resonator for mm‐wave‐band applications
Authors: Lim Junyoul , Yim Jounghyun , Kwon Woosung , Ryu Seonghan , Kim Bumman
Published: October 2002

A new planar‐type dielectric resonator (PDR) with a high Q has been developed. The PDR is fabricated by eching the GaAs substrate with an air gap around resonator and one side ground plane to reduce metal loss and facilitate integration. The realized PDR showed a good performance at 32 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 414–416, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10623
Signal propagation effects on high‐speed interconnection lines using time‐domain numerical technique
Authors: Li Erping , Yuan Weiliang , Wang Sheng
Published: October 2002

With advancements in microelectronics, interest in electromagnetic interference and compatibility in high‐speed circuits has greatly increased in the engineering community, and application of computational electromagnetics to electromagnetic interference and compatibility (EMI/EMC) engineering has become an emerging technology. Termination, via, and crosstalk on interconnection lines raises EMI problems in high‐speed circuits and requires attention during design phases for signal integrity. This paper analyzes signal propagation effects among different parts of high‐speed interconnection lines using the finite‐difference time‐domain (FDTD) method. The mechanism and the effectiveness of control measures are examined, which can be applied to high‐speed circuit designs. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 416–420, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10624
Mitochondrial abnormalities in muscle and other aging cells: Classification, causes, and effects
Authors: DiMauro Salvatore , Tanji Kurenai , Bonilla Eduardo , Pallotti Francesco , Schon Eric A.
Published: October 2002

The involvement of mitochondria and of mitochondrial DNA (mtDNA) in the aging process has generated much interest and even more controversy. The mitochondrial theory of aging considers a vicious circle consisting of: (1) accumulation of somatic mtDNA mutations; (2) impairment of respiratory chain function; (3) increased production of reactive oxygen species (ROS) in mitochondria; and (4) further damage to mtDNA. We review the evidence for and against the belief that these steps occur in aging muscle and brain, considering separately morphological, biochemical, and molecular data. The relationship between mitochondrial aging and late‐onset neurodegenerative diseases is briefly reviewed. We conclude that mitochondrial dysfunction does play a crucial role in the aging process of both muscle and brain, but it remains unclear whether mitochondria are the culprits or mere accomplices. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 000–000,
Dejerine–Sottas disease and hereditary demyelinating polyneuropathy of infancy
Authors: Plante‐Bordeneuve Violaine , Said Gérard
Published: October 2002

Dejerine–Sottas disease (DSD) was originally described as a hypertrophic polyneuropathy characterized by onset in infancy or early childhood in patients born to unaffected parents. The clinical features included distal sensory changes with ataxia; pes cavus, at times with kyphoscoliosis; motor deficit and atrophy predominating in the distal lower limbs and progressing toward the proximal limbs following a length‐dependent pattern; palpable nerve hypertrophy; and Argyll–Robertson pupils. The morphological hallmark was the extensive nerve and root hypertrophy associated with demyelination–remyelination of surviving, originally myelinated axons and profuse Schwann‐cell proliferation forming onion bulbs. Wide variations in clinical manifestations of chronic demyelinating polyneuropathies of early onset in children born to unaffected parents have now been reported, with only some of the characteristics required in the original study, and at least seven genes encoding the myelin proteins P0, PMP22, the transcriptional factor EGR2, and others have been implicated. Thus, DSD is now a component of the hereditary demyelinating polyneuropathies of infancy that also include subsets of the recently individualized CMT4 neuropathies. The presumed recessive transmission of patients with DSD should be confirmed by molecular genetic analysis, which is still negative in a significant proportion of patients. The nerve biopsy can be useful in patients in whom genealogical or DNA abnormalities in favor of a genetic disorder are missing, because in a few patients with a progressive or relapsing course the diagnosis of early‐onset chronic inflammatory demyelinating polyneuropathy must be considered. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 608–621, 2002
Anti‐heparan sulfate antibodies in neurological disease
Authors: Briani Chiara , Ruggero Susanna , Alaedini Armin , Nardelli Ettore , Ferrari Sergio , Wirguin Itzhak , Zara Gabriella , Battistin Leontino , Latov Norman
Published: October 2002

Antibodies to heparan sulfate (HS) have previously been found in association with peripheral neuropathy. We tested sera from patients with neuropathies and with other neurological diseases for antibodies to HS using an avidin‐biotin enzyme‐linked immunosorbent assay (ELISA) system. Increased titers of anti‐HS antibodies were found in 3.4% of patients with neuropathy, and in 3% of patients with other neurological diseases. In all cases, however, an inflammatory disease was present, including chronic inflammatory neuropathy, cerebral vasculitis, or multiple sclerosis. Antibodies to HS appear not to be specific for neuropathy, as they occur in several inflammatory diseases. They might contribute to the associated breakdown of the blood–brain or blood–nerve barrier. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 713–715, 2002
Physiological characterization of neuropathy in Fabry's disease
Authors: Luciano Carlos A. , Russell James W. , Banerjee Tapas K. , Quirk Jane M. , Scott Leland J.C. , Dambrosia James M. , Barton Norman W. , Schiffmann Raphael
Published: October 2002

Fabry's disease is commonly associated with a painful, debilitating neuropathy. Characterization of the physiological abnormalities is an important step in evaluating response to specific therapies. Twenty‐two patients with Fabry's disease, and with relatively preserved renal function, underwent conventional and near‐nerve conduction studies, electromyography, sympathetic skin responses, and quantitative sensory testing (QST). Nerve conduction studies were mostly normal except for an increased frequency of median nerve entrapment at the wrist in 6 (27%) patients. Sympathetic skin responses were preserved in 19 of 20 (95%) of the patients. The QST showed increased or immeasurable cold and warm detection thresholds in patients, significantly different from controls (n = 28) in the hand (P < 0.001, P = 0.04, respectively) and foot (P < 0.001 for both). Cold thresholds were more often abnormal than were warm thresholds. Vibration thresholds were normal in the feet and, in some patients, elevated in the hand only, probably due to frequent median nerve entrapment at the wrist. Our findings suggest that the neuropathy of Fabry's disease is characterized by an increased prevalence of median nerve entrapment at the wrist and by thermal afferent fiber dysfunction in a length‐dependent fashion, with greater impairment of cold than warm sensation. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 622–629, 2002
Within‐train neuromuscular propagation varies with torque in paralyzed human muscle
Authors: Chang Ya‐Ju , Shields Richard K.
Published: October 2002

Electromyographic (EMG) recordings may serve an important role in predicting torque during repetitive activation of paralyzed muscle. We compared the initial M‐wave to the subsequent M‐waves of the same train under fatigued and recovered conditions in the paralyzed human soleus muscle. Sixteen individuals with chronic (n = 13) or acute paralysis (n = 3) had the tibial nerve activated before and after a repetitive supramaximal stimulation protocol. The mean within‐train M‐wave amplitude and median frequency increased ∼20%, whereas the duration decreased ∼15% compared with the initial M‐wave of each train. During fatigue, there was a linear decrease in the difference between the initial M‐wave amplitude and subsequent train (∼20% to 8%). Following fatigue, this difference recovered to ∼12%. The difference between the M‐wave train average and the initial M‐wave for amplitude, duration, and median frequency closely followed torque (Pearson correlations = 0.99, 0.94, and 0.98, respectively) during fatigue. We conclude that the difference between the later‐occurring M‐waves (average of the train) and initial M‐wave is large when muscle torque is high and less when torque is low and, therefore, predicts torque during activation of paralyzed muscle. This difference in the within‐train M‐wave amplitude, duration, and median frequency may reflect a mechanical change, such as muscle shortening and increased muscle cross‐sectional area during isometric contractions. Electromyographic feedback may assist in the optimization of neuromuscular electrical stimulation of paralyzed muscle. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 673–680, 2002
Fibronectin receptor reduction in skin and fibroblasts of patients with Ullrich's disease
Authors: Hu Jing , Higuchi Itsuro , Shiraishi Tadafumi , Suehara Masahito , Niiyama Takahito , Horikiri Takashi , Uchida Yuichi , Saito Akiko , Osame Mitsuhiro
Published: October 2002

Ullrich's disease is a congenital muscular dystrophy characterized clinically by generalized muscle weakness, multiple contractures of the proximal joints, and hyperextensibility of the distal joints. Recent studies have demonstrated that collagen VI is deficient in the muscles of patients with Ullrich's disease, and some cases result from recessive mutations of the collagen VIα2 gene (COL6A2). Fibronectin is one of the main components of the extracellular matrix (ECM) and associates with a variety of other matrix molecules including collagen. The behavior of fibronectin on cells is mediated by fibronectin receptors, members of the integrin family. We studied the expression of fibronectin receptors and fibronectin in patients with Ullrich's disease, and found a marked reduction of fibronectin receptors in the ECM of skin and cultured fibroblasts of these patients. These results suggest that collagen VI deficiency may lead to the reduction of fibronectin receptors and that an abnormality of cell adhesion may be involved in the pathogenesis of Ullrich's disease. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 696–701, 2002
Cardiovascular autonomic function and sympathetic skin response in chronic inflammatory demyelinating polyradiculoneuropathy
Authors: Lyu Rong‐Kuo , Tang Lok‐Ming , Wu Yih‐Ru , Chen Sien‐Tsong
Published: October 2002

Quantitative cardiovascular autonomic function tests (AFTs) and sympathetic skin response (SSR) were performed in 12 patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Parasympathetic autonomic function was examined by Valsalva ratio and R‐R interval variation during rest and deep breathing. Sympathetic autonomic function was evaluated by blood pressure responses to sustained handgrip and active standing. Using quantitative AFTs, subclinical autonomic dysfunction was demonstrated in three (25%) patients. Abnormal SSR was seen in six (50%) patients. Thus, mild autonomic dysfunction is present in many CIDP patients. The autonomic abnormalities involve parasympathetic or sympathetic components; in the sympathetic nervous system, both vasomotor and sudomotor fibers may be involved. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 669–672, 2002
Surface EMG crosstalk between knee extensor muscles: Experimental and model results
Authors: Farina Dario , Merletti Roberto , Indino Barbara , Nazzaro Marisa , Pozzo Marco
Published: October 2002

Surface electromyographic (EMG) crosstalk between vastus lateralis, vastus medialis, and rectus femoris muscles was evaluated by selective electrical stimulation of one muscle and recording from the stimulated and another muscle with linear surface arrays of eight electrodes. The ratio between the amplitude of the signals recorded over nonstimulated and stimulated muscles and their correlation coefficient were used as indices to quantify crosstalk. Single‐differential and double‐differential detection systems were used with interelectrode distances in the range 10–40 mm. The multichannel EMG signals clearly showed that crosstalk is largely due to nonpropagating potentials that correspond in time to the end of the propagation of the action potentials generated by the stimulated muscle. The crosstalk signal increased with increasing interelectrode distance and was statistically higher for single‐ than for double‐differential recordings. The correlation‐based indices of crosstalk were poorly correlated with the amplitude‐based indices. Moreover, the characteristic spectral frequencies of the signals detected over the nonstimulated muscles were statistically higher than those from the stimulated muscles. A mathematical model of signal generation was used to explain the experimental findings. This study clarifies many controversial findings of past investigations and creates the basis for crosstalk interpretation, simulation, and reduction. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 681–695, 2002
Inhibition of dystroglycan binding to laminin disrupts the PI3K/AKT pathway and survival signaling in muscle cells
Authors: Langenbach K.J. , Rando T.A.
Published: October 2002

Dystroglycan is a component of the dystrophin–glycoprotein complex (DGC) in muscle and a cell surface receptor for laminin. Numerous muscular dystrophies are the result of disruption of proteins comprising the DGC, but the underlying pathogenetic mechanisms are unknown. Because apoptosis is an early feature of muscular dystrophy in vivo, and perturbation of cell–extracellular matrix associations is known to induce apoptosis, we investigated the role of dystroglycan–laminin interactions in the propagation and maintenance of cell survival signals in muscle cells. We found that disrupting the interaction between α‐dystroglycan and the extracellular matrix protein laminin induces apoptosis in muscle cells. This increase in apoptosis is mediated in part by caspase activation and can be blocked by a caspase‐3 inhibitor. We demonstrate a role for the phosphoinositide 3‐kinase (PI3K)/protein kinase B (AKT) pathway in muscle cell–survival signaling using a pharmacological inhibitor of PI3K. Treatment with this inhibitor resulted in decreased phosphorylation of AKT and its downstream effector glycogen synthase kinase (GSK)‐3β and induced apoptosis in muscle cell cultures. Disruption of dystroglycan–laminin interactions resulted in decreased phosphorylation of AKT and GSK‐3β. Furthermore, activation of AKT prior to the disruption of dystroglycan–laminin protected the muscle cells from the induction of apoptosis. These results support a role for the PI3K/AKT pathway in the propagation of cell‐survival signals mediated by the DGC and provide new insight into the molecular pathogenesis associated with the development of muscular dystrophies. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 644–653, 2002
Wave properties of action potentials from fast and slow motor units of rats
Authors: Wakeling James M. , Syme Douglas A.
Published: October 2002

The purpose of this study was to identify the frequency, conduction velocity, and wavelength of fast and slow motor unit action potentials (MUAPs) from mixed mammalian muscle. Stimulation and blocking pulses to the sciatic nerve produced varying recruitment patterns (confirmed by force measurements) of fast and slow motor units of the medial gastrocnemius of six rats. Myoelectric signals from the muscle were resolved into their intensity in time and frequency space. Slow MUAPs had a mean frequency (± SEM) of 183 ± 8 Hz, conduction velocity of 3.5 ± 0.6 m s−1, and wavelength of 19 mm. Fast MUAPs had a mean frequency of 369 ± 11 Hz, conduction velocity of 6.7 ± 0.5 m s−1, and wavelength of 18 mm. Frequency and conduction velocity, but not wavelength, were significantly different between the fast and slow MUAPs. The distinct wave properties of fast and slow MUAPs can thus be used to distinguish action potentials from these motor units, and could be used to determine patterns of motor unit recruitment during locomotion. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 659–668, 2002
Ion channel and striational antibodies define a continuum of autoimmune neuromuscular hyperexcitability
Authors: Vernino Steven , Lennon Vanda A.
Published: October 2002

Neuromuscular hyperexcitability is a characteristic of Isaacs' syndrome. Autoantibodies specific for voltage‐gated potassium channels (VGKC) or ganglionic nicotinic acetylcholine receptors (AChR) are markers of this disorder. To determine the frequency of these ion channel antibodies and of related neuron‐ and muscle‐specific antibodies in patients with acquired neuromuscular hyperexcitability, we tested serum specimens from 77 affected patients (35 neuromyotonia, 32 cramp‐fasciculation syndrome, 5 rippling muscle syndrome, and 5 focal neuromuscular hyperexcitability) and 85 control subjects. Among study patients, 14% had coexisting myasthenia gravis, and 16% had an associated neoplasm. We found that 35% had VGKC antibodies, 12% ganglionic AChR antibodies, 16% muscle AChR antibodies, and 10% striational antibodies. Overall, 55% had serological evidence of neurological autoimmunity compared to 2% of control subjects. Patients with neuromyotonia were more frequently seropositive (71%) than patients with cramp‐fasciculation syndrome (31%). We conclude that acquired neuromuscular hyperexcitability consists of a continuum of clinical disorders with a common autoimmune pathogenesis. © 2002 Wiley Periodicals, Inc. Muscle Nerve 26: 702–707, 2002
Direct, partitioned and projected solution to finite element consolidation models
Authors: Gambolati Giuseppe , Pini Giorgio , Ferronato Massimiliano
Published: October 2002

Direct, partitioned, and projected (conjugate gradient‐like) solution approaches are compared on unsymmetric indefinite systems arising from the finite element integration of coupled consolidation equations. The direct method is used in its most recent and computationally efficient implementations of the Harwell Software Library. The partitioned approach designed for coupled problems is especially attractive as it addresses two separate positive definite problems of a smaller size that can be solved by symmetric conjugate gradients. However, it may stagnate and when converging it does not prove competitive with a global projection method such as Bi‐CGSTAB, which may take full advantage of its flexibility in working on scaled and reordered equations, and thus may greatly improve its computational performance in terms of both robustness and convergence rate. The Bi‐CGSTAB superiority to the other approaches is discussed and demonstrated with a few representative examples in two‐dimensional (2‐D) and three‐dimensional (3‐D) coupled consolidation problems. Copyright © 2002 John Wiley & Sons, Ltd.