bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuroprotective effect of riluzole in a primate model of Parkinson's disease: Behavioral and histological evidence
Authors: Obinu Maria C. , Reibaud Michel , Blanchard Véronique , Moussaoui Saliha , Imperato Assunta
Published: August 2002

Our study aimed to determine whether riluzole, which has shown efficacy as a disease‐modifying agent in amyotrophic lateral sclerosis (ALS), is neuroprotective in a marmoset model of Parkinson's disease (PD). Reduction of energy demand by riluzole could be a rational neuroprotective strategy with good tolerability. The efficacy of riluzole was evaluated in marmosets by testing its ability to reduce MPTP‐induced behavioral deficits and loss of dopaminergic nigral neurons. Marmosets were divided into two groups of four animals each: animals in Group 1 were injected twice with MPTP (2 mg/kg subcutaneous) and treated with riluzole (10 mg/kg per os b.i.d.), animals in Group 2 (controls) were injected with MPTP and with the vehicle of riluzole. A third group of marmosets which did not receive MPTP or riluzole drug was introduced for neurohistopathological studies (normal animals). Marmosets treated with riluzole preserved a better motor function and neurological performance through the 26 days of assessment when compared with the controls. Histologically, there was sparing of TH‐ and Nissl‐stained nigral neurons and of TH‐stained terminals in the striatum and the putamen in the group treated with riluzole compared to the controls. We conclude that riluzole protects dopaminergic neurons and reduces behavioral deficits in a marmoset model of PD. © 2001 Movement Disorder Society.
Bilateral subthalamic stimulation monotherapy in advanced Parkinson's disease: Long‐term follow‐up of patients
Authors: Valldeoriola Francesc , Pilleri Manuela , Tolosa Eduardo , Molinuevo José L. , Rumià Jordi , Ferrer Enric
Published: August 2002

Bilateral subthalamic nucleus stimulation (STN‐DBS) is used to improve parkinsonian symptoms and attenuate levodopa‐induced motor complications. In some patients, such clinical improvement allows antiparkinsonian medication (ApMed) withdrawal. We show the clinical outcome at the long‐term follow‐up of patients with advanced Parkinson's disease (PD) in which STN‐DBS was used in monotherapy, and compare the clinical results of patients without medication with those obtained in parkinsonian patients in which ApMed were reduced but could not be totally displaced after surgery. We analyzed clinical outcome of ten patients with PD in which all ApMed was withdrawn after bilateral subthalamic stimulation and 16 parkinsonian patients still taking antiparkinsonian medication after surgery. After 1.5 years, STN‐DBS monotherapy produced UPDRS motor scores similar to those observed in the on‐drug condition before surgery without the inconvenience of motor fluctuations and dyskinesias. No significant differences were seen in most of clinical outcome measures when comparing patients still taking ApMed with patients in STN‐DBS monotherapy but a few patients still taking ApMed presented mild dyskinesias and motor fluctuations and patients with STN‐DBS monotherapy did not. STN‐DBS is useful in the treatment of advanced PD and in some patients it is possible to maintain this therapy alone in the long term. The therapeutic effect of STN‐DBS on motor signs can be equipotent to that of levodopa with the additional benefit of avoiding motor fluctuations and dyskinesias. © 2001 Movement Disorder Society.
Modeling the 3D structure of GPCRs from sequence
Authors: Shacham Sharon , Topf Maya , Avisar Noa , Glaser Fabian , Marantz Yael , Bar‐Haim Shay , Noiman Silvia , Naor Zvi , Becker Oren M.
Published: August 2002

G‐protein‐coupled receptors (GPCRs) are a large and functionally diverse protein superfamily, which form a seven transmembrane (TM) helices bundle with alternating extra‐cellular and intracellular loops. GPCRs are considered to be one of the most important groups of drug targets because they are involved in a broad range of body functions and processes and are related to major diseases. In this paper we present a new technology, named PREDICT, for modeling the 3D structure of any GPCR from its amino acid sequence. This approach takes into account both internal protein properties (i.e., the amino acid sequence) and the properties of the membrane environment. Unlike competing approaches, the new technology does not rely on the single known structure of rhodopsin, and is thus capable of predicting novel GPCR conformations. We demonstrate the capabilities of PREDICT in reproducing the known experimental structure of rhodopsin. In principle, PREDICT‐generated models offer new opportunities for structure‐based drug discovery towards GPCR targets. © 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 5, 472–483, 2001
A reconstructed digit by transplantation of a second toe for control of an electromechanical prosthetic hand
Authors: Chen Zhong Wei , Hu Tian Pei
Published: August 2002

The treatment options for the loss of an entire human hand and part of the forearm are currently limited to the transplantation of toe(s) to the amputation stump or a Krukenberg's bifurcation hand, and using a cosmetic or functional prosthesis. The functional prosthetic hand, such as the prevailing myoelectrically controlled prosthetic hand, has an action accuracy that is affected by many factors. The acceptance rate of the three planes freedom myoelectronic hand by the patients was 46–90% because of poor function caused by the weakness of signal and strong external interference. In this report, the left second toe was transplanted to the patient's forearm amputation stump. Mandates from the brain are relayed by the action of this reconstructed digit, to control a special designed multidimension freedom electronic prosthetic hand. After rehabilitation and adaptation training, the correct recognition rate of the electronic prosthetic hand controlled by this reconstructed digit is a remarkable 100%. © 2002 Wiley‐Liss, Inc. MICROSURGERY 22:5–10, 2002 DOI 10.1002/micr.22002
Boundary stabilization for a non‐linear beam on elastic bearings
Authors: Fu Ma To
Published: August 2002

In this paper, we study the equation

under non‐linear boundary conditions which model the vibrations of a beam clamped at x=0 and supported by a non‐linear bearing at x=L. By adding only one damping mechanism at x=L, we prove the existence of a global solution and exponential decay of the energy. Copyright © 2001 John Wiley & Sons, Ltd.
Non‐linear initial boundary value problems of hyperbolic–parabolic type. A general investigation of admissible couplings between systems of higher order. Part 3: applications
Authors: Ebenfeld Stefan
Published: August 2002

This is the third part of an article that is devoted to the theory of non‐linear initial boundary value problems. We consider coupled systems where each system is of higher order and of hyperbolic or parabolic type.

Our goal is to characterize systematically all admissible couplings between systems of higher order and different type.

By an admissible coupling we mean a condition that guarantees the existence, uniqueness and regularity of solutions to the respective initial boundary value problem.

In part 1, we develop the underlying theory of linear hyperbolic and parabolic initial boundary value problems. Testing the PDEs with suitable functions we obtain a priori estimates for the respective solutions. In particular, we make use of the regularity theory for linear elliptic boundary value problems that was previously developed by the author. In part 2, we prove the local in time existence, uniqueness and regularity of solutions to quasilinear initial boundary value problems using the so‐called energy method. In the above sense the regularity assumptions about the coefficients and right‐hand sides define the admissible couplings. In part 3 at hand, we extend the results of part 2 to the nonlinear initial boundary value problem (4.2). In particular, assumptions (B8) and (B9) about the respective parameters correspond to the previous regularity assumptions and hence define the admissible couplings now. Moreover, we exploit assumptions (B8) and (B9) for the case of two coupled systems. Copyright © 2002 John Wiley & Sons, Ltd.
Potential splitting and numerical solution of the inverse scattering problem on the line
Authors: Aktosun Tuncay , Sacks Paul E.
Published: August 2002

The one‐dimensional Schrödinger equation is considered when the potential is real valued, integrable, has a finite first moment, and contains no bound states. From either of the two reflection coefficients of such a potential the right and left reflection coefficients are extracted corresponding to the left and right halves of the potential, respectively, and such half‐line potentials are readily constructed from the extracted reflection coefficients. A computational procedure is described for such extractions and the construction of the two halves of the potential, and some applications are considered such as a numerical solution of the initial value problem for the Korteweg–de Vries equation. The theory is illustrated with some explicit examples. Copyright © 2002 John Wiley & Sons, Ltd.
Domain sensitivity analysis of the acoustic far‐field pattern
Authors: Bochniak Marius , Cakoni Fioralba
Published: August 2002

We consider acoustic scattering problems described by the mixed boundary value problem for the scalar Helmholtz equation in the exterior of a 2D bounded domain or in the exterior of a crack. The boundary of the domain is assumed to have a finite set of corner points where the scattered wave may have singular behaviour. The paper is concerned with the sensitivity of the far‐field pattern with respect to small perturbations of the shape of the scatterer. Using a modification of the method of adjoint problems, we obtain an integral representation for the Gâteaux derivative which contains only boundary values of functions easily computable by standard BEM and which depends explicitly on the perturbation of the boundary. In some cases, we show the direct influence of the singularities of the solution on the sensitivity of the far‐field pattern. In this way, we generalize the domain sensitivity analysis developed earlier for smooth domains by Hettlich, Kirsch, Kress, Potthast and others. Finally, we show that the same approach can be applied to scattering from 3D domains with smooth edges. Copyright © 2002 John Wiley & Sons, Ltd.
A new design approach for an injection‐locked oscillator with an enhanced locking range
Authors: Jun Youngsang , Lee Moon‐Que , Lee Youngteak , Nam Sangwook
Published: August 2002

A new approach to the narrow locking range problems of an injection‐locked oscillator (ILO) has been investigated using a feedback signal into the active device and a fictitious internal source generated by nonlinearities of the active device. Through this analysis, a new design methodology for an ILO with an enhanced locking range is proposed. Measured results verified the enhanced locking range of the ILO. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 325–327, 2001.
A linearized power method for adaptive beamforming in a multipath fading CDMA environment
Authors: Ahn Sungsoo , Choi Seungwon , Sarkar Tapan K.
Published: August 2002

This paper discusses an adaptive procedure of a simplified power method for computing the eigenvector corresponding to the largest eigenvalue of an autocovariance matrix. The objective is to generate a suboptimal weight vector for an adaptive array operating in a multipath fading CDMA (code‐division multiple access) channel. The total computational load of the proposed procedure is about O(4N), including an autocovariance matrix update, where N is the number of weights. The performance of the proposed array system is shown in terms of the BER (bit‐error rate) and the allowable capacity in a modeled IS‐95 CDMA signal environment. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 361–365, 2001.
On the analysis of a weakly guiding doubly clad dielectric optical fiber with an annular core
Authors: Sarkar B. C. , Choudhury P. K. , Yoshino T.
Published: August 2002

A fairly rigorous analytical treatment of an annular core dielectric optical fiber is presented, the core of the fiber lying between two concentric claddings with the outer cladding extended infinitely. For the theoretical approach, the approximation of the vanishing refractive‐index difference between the core and the cladding sections is implemented. The investigation is on the preliminary ground, and a numerical estimation of the modal cutoffs is presented for the said fiber. The effects of the core width as well as the inner core diameter on the propagation constants βc at field cutoffs are presented. Plots are also shown of the variation of βc with the change in the refractive‐index values. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 435–439, 2001.
A gain‐clamped erbium‐doped fiber amplifier (GC–EDFA) for WDM optical packet‐switching system
Authors: Yang C. R. , Hwang H. Y. , Hong H. H.
Published: August 2002

The use of a dual‐stage gain‐clamped erbium‐doped fiber amplifier (GC–EDFA) having a pump laser diode and 16‐channel wavelength‐division multiplexing (WDM) with 0.8 nm spacing in the C‐band of 1545–1560 nm wavelength was demonstrated in a burst packet‐mode optical switching system through an experimental setup. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 167–170, 2002.
Influence of XPM effect on IP traffic‐based WDM optical packet‐switching networks
Authors: Yongpeng Zhao , Peida Ye
Published: August 2002

Based on the analytical method, the influence of the cross‐phase modulation effect on WDM optical packet‐switching networks is investigated. We show that the input optical power, channel spacing, and traffic characteristics impact the XPM effect that eventually influences the network performance. The results are useful for designing optical packet networks. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 170–174, 2002.
A broadband low‐profile cylindrical monopole antenna top loaded with a shorted cross patch
Authors: Yeh Shih‐Huang , Wong Kin‐Lu
Published: August 2002

With the top loading of a shorted cross patch of equal arm lengths, a cylindrical monopole antenna can have a low profile (about 7.5% of the free‐space wavelength of the center operating frequencies) and broadband operation (larger than 23%). In addition, by comparing to the case of top loading a shorted rectangular patch, the obtained conical radiation patterns of the proposed low‐profile monopole antenna are much more uniform in all of the ϕ‐planes. Details of the proposed antenna and experimental results are presented. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 186–188, 2002.
A broadband and compact microstrip antenna for IMT‐2000, DECT, and bluetooth integrated handsets
Authors: Wang Ya Jun , Gan Yeow Beng , Lee Ching Kwang
Published: August 2002

A novel and broadband semidisk microstrip antenna suitable for a portable and compact terminal integrated with the 3G IMT‐2000 cellular system, DECT mobile system, and Bluetooth wireless technology is discussed both theoretically and experimentally. Using both bandwidth‐enhancement and size‐miniaturization methods, a broad impedance bandwidth (return loss ≤−10 dB) of 32.4% from 1.86 to 2.58 GHz is obtained. Typical characteristics of the proposed antenna are addressed and discussed. Good agreements are obtained in the measured and simulated results. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 204–207, 2002.
Millimeter‐wave down‐converter conversion gain performance enhancement
Authors: Brabetz T. , Fusco V. F.
Published: August 2002

The influence of via hole inductance on millimeter‐wave single‐ended pHEMT gate‐mixer down‐converter conversion gain is examined by a closed formula and by measurement. It is shown that feedback inductance acts as a voltage divider, reducing the conversion gain and increasing the LO power requirements. Analytical considerations presented in the paper predict that this effect can reduce the conversion gain by up to 9 dB. Additionally, a method to minimize the influence of via hole inductance on mixer performance is presented. Two circuits, one with and one without resonating stubs, have been manufactured and tested. The new circuit exhibits 3.5 dB more conversion gain than the classical topology, RF 65.3 GHz, nominal IF 1.3 GHz. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 399–400, 2002.
Fabrication of monoblock ceramic bandpass filters with attenuation poles
Authors: Weng Min‐Hung , Liang Tsorng‐Juu
Published: August 2002

Small size and rapid attenuation rate are two important factors in the selection of bandpass filters for practical applications. This paper describes a monoblock and modified Chebyshev‐type bandpass filter with an attenuation pole in the lower stopband. The equivalent circuit consists of resonators, and series capacitance is presented to predict the filter performance. The series capacitance is made directly by an appropriate choice of the electrode pattern. Since no additional lumped element is needed, the designed filter shows a simple structure. Also, a compact monoblock bandpass filter using high‐permittivity ceramics of (Ba,Sr)O–Sm2O3–4.7TiO2 is fabricated. Experimental results of the fabricated filter measured by an HP8510B network analyzer verify the expected effect. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 400–402, 2002.
Reflection characteristics of a metallic waveguide grating with rectangular grooves as a frequency‐selective reflector
Authors: Thumvongskul T. , Shiozawa T.
Published: August 2002

A proper duty cycle of the grating period which provides the maximum reflection for a metallic waveguide grating with rectangular grooves is found by the mode‐matching approach. For narrowband reflection characteristics, a grating with sufficient numbers of periods and adequately small corrugation is needed, with cutoff conditions taken into account. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 414–418, 2002.
Processing and analysis of transient resonant signal of buried object based on wavelet transform
Authors: Guangyou Fang
Published: August 2002

The identification of buried objects is one of the challenging and difficult topics in the ground‐penetrating radar (GPR) domain. In this paper, the transient resonant signals from buried perfectly electrical conductors (PECs) are measured by a kind of impulse GPR system. The relationship between the transient resonance and the natural poles of the buried PEC objects is studied. The wavelet transform (WT) method is used to denoise and calculate the instantaneous parameters. The instantaneous WT power and energy spectra of transient resonant signals are calculated and analyzed. The physical mechanism of the resonance of targets is also studied by the singularity expansion method (SEM) theory. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 427–431, 2002.
Dual‐frequency slot antennas fed by capacitively coplanar waveguide
Authors: Chen Jin‐Sen
Published: August 2002

A novel design of a dual‐frequency antenna capacitively fed by a coplanar waveguide is presented. The proposed antenna is constructed by a rectangular slot loop antenna and a rectangular slot antenna, both coupled to each other, and which have the same CPW feed. The two resonant frequencies of the proposed antenna are decided, respectively, by the dimensions of the two slot antennas. Designs of the proposed dual‐frequency slot antenna are described, and typical experimental results are demonstrated and discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 452–453, 2002.
A dual‐band multiwavelength erbium‐doped fiber laser source
Authors: Tong F. W. , Wang D. N. , Li Hong , Jin W.
Published: August 2002

A multiwavelength erbium‐doped fiber ring laser is proposed, which is based on two Mach–Zehnder interferometers in a cascade configuration. One of the interferometers acts as a wavelength filter, and the other, exhibiting a relatively small optical path difference, determines the number of lasing wavelengths. By the use of an optical switch, the operating wavelengths can be shifted between two wavelength bands, centered at 1555 and 1565 nm. A stable simultaneous ten‐wavelength lasing operation with amplitude fluctuations <5 dB, wavelength spacing ≈0.5 nm, and signal‐to‐noise ratio >25 dB over the whole operating wavelength region has been obtained. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 458–461, 2002.
A comparative study of different types of dielectric trapezoid optical waveguides under weak guidance approximation
Authors: Srivastava S. K. , Ojha S. P.
Published: August 2002

In this communication, we present a comparative study of different types of dielectric trapezoidal waveguides. Using a numerical method, we obtain the modal characteristic equations of these trapezoidal waveguides. The modal characteristic equations are obtained in this case by using a point‐matching method under the weak guidance approximation. Dispersion curves are also obtained. The modal characteristics of trapezoidal waveguides are compared with those of square waveguides in detail. Some important insights have been obtained, which are distortions of a square shape into a trapezoidal shape responsible for the slight increase in the lowest cutoff value (Vc); the distortion from a square shape to a trapezoidal shape is also responsible for the increase in the number of modes. This study can be viewed as a tolerance study of the waveguide with the square cross section under a trapezoidal distortion. ©2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 32: 461–464, 2002.
A dual‐band GPS microstrip antenna
Authors: Su Chih‐Ming , Wong Kin‐Lu
Published: August 2002

Design considerations and experimental results of a dual‐band circularly polarized stacked microstrip antenna for GPS operations at 1227 and 1575 MHz are presented. The antenna is achieved by stacking two corner‐truncated square microstrip patches. The obtained circular polarization (CP) bandwidths, determined from 3‐dB axial ratio, are about 15 MHz (about 1.2%) and 17 MHz (about 1.1%) at 1227 and 1575 MHz, respectively. Good CP radiation patterns and antenna gain have also been observed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 238–240, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10285
A novel primary feed antenna for plane sheet metallic reflectors for base stations
Authors: Ali M. , Stuchly S. S.
Published: August 2002

A new type of primary feed antenna for plane sheet metallic reflectors is introduced. Reflector dimension can be reduced by 46% compared to a half‐wave dipole feed when the directivity, beamwidth, and front‐to‐back ratio are fixed at 7.6 dBi, 100°, and 15.5 dB. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 407–408, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10336
Improving the coupled‐mode method by means of step functions: Application to partial‐height isotropic or anisotropic dielectric parallel‐plate waveguides
Authors: Gómez Álvaro , Ipiña Juan S. , Solano Miguel A. , Prieto Andrés , Vegas Ángel
Published: August 2002

The main drawback of the coupled‐mode method is the poor convergence and accuracy of the discontinuous field components. The greater the discontinuity, the worse these problems become. This Letter presents an improvement of the method, allowing this drawback to be minimized. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 408–414, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10337
On the propagation of electromagnetic waves through parabolic cylindrical chiroguides with small flare angles
Authors: Choudhury P. K.
Published: August 2002

With the use of Maxwell's field equations, an analytical investigation of the propagation of electromagnetic (EM) waves through a three‐layer parabolic cylindrical chirowaveguide is presented; different regions of the guide have different values of chirality admittance. The analytical approaches to derive the dispersion relations and the eigenvalue equations for cutoff are discussed under the assumption of small flare angles of the parabolic cylindrical boundaries. However, more emphasis is given on the modal field cutoffs. It is observed that the bunching tendency of field cutoffs, which is seen in the cases of parabolic cylindrical dielectric guides, is greatly affected in this case, which is attributed to the presence of chirality in the medium. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 414–419, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10338
On the measurement of the complex permittivity of layers embedded in a multilayered dielectric material with the use of a free‐space method
Authors: Garcia‐Ruiz Israel , Aviles‐Castro Carlos D. , Jardón‐Aguilar Hildeberto , Guerra‐Vargas Juan
Published: August 2002

Free‐space method approaches for obtaining the complex permittivity of dielectric layers embedded in a multilayer dielectric material are investigated. Solids, liquids, and granular materials have been tested; a description of the de‐embedding process is presented in detail, as are the measured permittivity values. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 422–426, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10340
Experimental investigation of a 4‐FBG TDM sensor array with a tunable laser source
Authors: Chan C. C. , Jin W. , Demokan M. S.
Published: August 2002

The performance of a time‐division‐multiplexed fiber Bragg grating sensor array that uses a tunable laser source has been investigated. It was found that the wavelength detection accuracy is affected by the extinction ratio of the optical pulse modulator used for input pulse generation. Experiments with a 4‐FBG sensor array demonstrated a strain resolution of 0.7 με with an optical pulse modulator of −24‐dB extinction ratio. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 435–437, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10343
Compact planar inverted‐F patch antenna for triple‐frequency operation
Authors: Hsiao Fu‐Ren , Wong Kin‐Lu
Published: August 2002

A novel compact planar inverted‐F patch antenna with two shorted branch strips for triple‐frequency operation at about 900, 1800, and 2450 MHz is presented. The antenna has compact dimensions of 5.5 mm in height and 7.5 × 24 mm2 in area. The two shorted branch strips are printed on an FR4 substrate, and supported above a ground plane by plastic posts. In addition, the longer branch strip, which controls the operations at about 900 and 1800 MHz, is printed on both sides of the FR4 substrate, leading to the reduction in antenna dimensions. On the other hand, the shorter branch strip, printed on one side of the FR4 substrate only, controls the operation at about 2450 MHz. Details of the antenna design and experimental results are presented and discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 459–462, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10350
Assessment of the effectiveness of a boundary value approach for the estimation of the electric field distribution in exposed phantoms
Authors: Caorsi Salvatore , Bermani Emanuela , Massa Andrea
Published: August 2002

In this Letter a new approach for the estimation of the electric field distribution in phantoms exposed to not completely specified or unknown electromagnetic source is proposed. Starting from the knowledge of the tangential component of the electric field on a surface around the object, the problem is recast in a boundary value problem numerically solved by means of a finite‐element procedure. Neither description nor modeling of the source is required. Numerical results concerning a two‐dimensional geometry are provided in order to assess the effectiveness of the proposed approach showing its capabilities and current limitations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 41–43, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10367
Extraction of equivalent‐circuit parameters of interconnection lines with the use of the finite‐difference time‐domain method
Authors: Farahat Nader , Mittra Raj
Published: August 2002

This Letter presents a simple technique for extracting the equivalent parameters of transmission‐line interconnects based on the finite‐difference–time‐domain (FDTD) method. The transmission line containing the discontinuity is divided into a set of uniform segments of short‐length line. Next, the parameters of each of these segments are extracted by substituting the FDTD solution into the telegrapher's equations. The accuracy of the method is comparing by the results with those derived via the method of moments (MoM). The equivalent circuit can be used in a SPICE simulator to predict the performance of interconnect with a view to enhancing the characterization and design of high‐speed digital circuits. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 34: 59–61, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10373
Reflectivity spectra evolution in grating structures with fractionally organized gaps
Authors: Hattori Haroldo T. , Schneider Vitor M. , Barbosa Carmen L. , Cazo Rogério M.
Published: August 2002

Gratings with quarter‐wavelength gaps separating subgratings have been analyzed extensively in the literature, where they have found applications for distributed feedback lasers, filters, etc. In these structures, the gaps always had quarter‐wavelength lengths. We modify these structures by starting with a quarter‐wavelength gap, but ordering the subsequent gaps following a scaling factor of 0.8. The subgratings are assumed to be uniform and to have equal lengths. The reflectivity spectra of these gratings are analyzed by using the transfer matrix method, with emphasis on the wavelength range near the central lobe. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 42–45, 2001.
Scanning properties of sequentially rotated linear arrays of circularly polarized patch radiators
Authors: García‐García Quiterio
Published: August 2002

This paper presents a theoretical analysis of the effect of beam scanning and amplitude tapering on the cross‐pol level of sequentially rotated linear arrays composed of circularly polarized patch antenna elements. Arrays of eight elements are considered to illustrate the analysis. Several sequential phase distributions are analyzed in terms of the cross‐pol level cancellation effect over the antenna field of view. These arrangements are analyzed in terms of the location of the maximum cross‐pol peak levels and their values. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 343–350, 2001.
Investigation of the performance of the resistive voltage source used for the FDTD analysis of microstrip circuits
Authors: Zhao An Ping , Alinikula Petteri
Published: August 2002

In this paper, the performance of the resistive voltage source (RVS) model used for the FDTD analysis of microstrip circuits is evaluated. It is found that, when the actual physical impedance of a microstrip line is used for assigning a constant value of Rs into the corresponding electric nodes in the RVS region, the model often induces quite large reflections. Detailed numerical investigations indicate that the performance of the RVS model can be greatly enhanced when the effective impedance (which is determined by examining the maximum value of the calculated voltage between the strip line and the ground plane), instead of the physical impedance, of the microstrip line is used for the RVS model. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 378–381, 2001.
Irradiators for the study of microwave sterilization effects
Authors: Posadas V. Vicente González , Marco R. , Rodríguez Martín José María , Frias Carlos Rueda , Jiménez Martín José Luis , Martín Pascual Carlos
Published: August 2002

We show, in this paper, the results obtained in the sterilization process by using different irradiating structures. Starting from our earlier findings of the existence of an important synergy on the killing effect caused by the simultaneous application of oxidant agents such as hydrogen peroxide and microwave irradiation, we have now extended the work to identify the power threshold and the optimum frequency range for the effect. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 404–406, 2001.
Simulation of a high‐speed radio link under OPNET
Authors: Carsenat D. , Mathieu S. , Besse O. , Guedira R. , Vaudon P. , Monediere T. , Jecko B.
Published: August 2002

A high‐speed radio link, such as the LMDS (local multipoint distribution system), proves to be quite complex to simulate under OPNET modeler radio from the electromagnetic propagation point of view. This paper describes the introduction of a 3‐D radiation diagram in the simulation and integration of software computing the electromagnetic propagation, taking note of the multipath. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 24–27, 2001.
Radiation parameter extraction for transmission‐line interconnects by using method‐of‐moments solutions
Authors: Liu Y. W. , Hong J. S. , Liu W. M. , Mei K. K.
Published: August 2002

In this paper, an extraction technique of radiation sources for nonuniform transmission lines is proposed for the first time. The technique, based on solutions of the method of moments (MoM), can numerically determine the coefficients of nonuniform transmission‐line equations, in which radiation parameters are included. Numerical examples show that the radiation effect of a right‐angle microstrip‐line bend is indeed stronger than that of a corresponding 45° mitered bend at high frequency. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 37–39, 2001.
Compact L‐strip capacitively coupled patch antenna with a folded radiating patch for a DCS base station
Authors: Chang Fa‐Shian , Wong Kin‐Lu
Published: August 2002

With the use of a folded radiating patch and an L‐strip capacitively coupled feed, a novel compact patch antenna suitable for a DCS (1710–1880 MHz) cellular system base‐station application is presented. Owing to the folded radiating patch used, the patch length in the excitation direction can be greatly reduced by more than 30% compared to the case with a conventional radiating patch. Many prototypes have been constructed, and the experimental results are presented. The effects of the folded radiating patch on the antenna's radiation characteristics are also discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 60–62, 2001.
Pharmacokinetics of doxorubicin in children with acute lymphoblastic leukemia: Multi‐institutional collaborative study
Authors: Frost B.‐M. , Eksborg S. , Björk O. , Abrahamsson J. , Behrendtz M. , Castor A. , Forestier E. , Lönnerholm G.
Published: August 2002

Background

In adults, it has been shown that the pharmacokinetics of doxorubicin are highly variable, despite standardization of the dose based on body surface area (BSA). The purpose of this study was to determine the plasma concentrations of doxorubicin and its active metabolite doxorubicinol in children treated for acute lymphoblastic leukemia (ALL).

Procedure

Children, 107 in number, aged 1.3–17.3 years, were studied at Day 1 of induction therapy according to the current Nordic protocol. Five infants, 3–9 months old, were also included. Plasma samples were drawn 23 hr after the start of a 24‐hr infusion of doxorubicin 40 mg/m2, and analyzed by reversed‐phase liquid chromatography.

Results

There was a more than 10‐fold difference between patients in dose normalized plasma concentration of doxorubicin, median 62.8 ng/ml, range 22.6–334 ng/ml. The doxorubicin concentrations differed significantly between age groups (P = 0.003). Children aged 4–6 years had the highest doxorubicin concentrations, median 77.9 ng/ml, followed by 2–4‐year‐old children, median 64.3 ng/ml. Both younger and older children had median values of about 50 ng/ml. Patients with white blood cell (WBC) count > 50 × 109/L at diagnosis had significantly lower doxorubicin concentrations, median 55.3 ng/ml, than those with WBC count < 10 × 109/L, median 64.4 ng/ml (P = 0.015). There was no difference in doxorubicin concentration between boys and girls. No correlation was found between doxorubicin levels and serum aminotransferases or serum creatinine. The concentration of doxorubicinol was 13% (median value) of that of doxorubicin. Four infants, 7–9 months old, had plasma clearance between 350–431 ml/min/m2, which is in the same range as in older children. A 3‐month‐old infant had a clearance of 181 ml/min/m2.

Conclusions

The age groups who had the highest doxorubicin concentrations, (2‐) 4–6‐year‐old children, are known to make up a large proportion of standard risk ALL cases with good prognosis. The correlation between doxorubicin plasma levels and clinical effect needs further study. The influence of age, body composition, and tumor burden on the pharmacokinetics of antineoplastic drugs should also be further explored, aiming at improvements in the current dosing regimen based on BSA. Med. Pediatr. Oncol. 2002;38:329–337. © 2002 Wiley‐Liss, Inc.
In vitro drug resistance profile of Philadelphia positive acute lymphoblastic leukemia is heterogeneous and related to age: A report of the Dutch and German Leukemia Study Groups
Authors: Woerden N.L. Ramakers‐van , Pieters R. , Hoelzer D. , Slater R.M. , den Boer M.L. , Loonen A.H. , Harbott J. , Janka‐Schaub G.E. , Ludwig W‐D , Ossenkoppele G.J. , van Wering E.R. , Veerman A.J.P.
Published: August 2002

Background

The t(9;22)(q34;q11) translocation leading to the Philadelphia (Ph) chromosome resulting in BCR‐ABL gene fusion is associated with a poor prognosis in acute lymphoblastic leukemia (ALL).

Procedure

We studied the relation between t(9;22), determined by karyotype, fluorescence in situ hybridization (FISH) or polymerase chain reaction (PCR), and in vitro drug resistance, measured by the MTT assay, in precursor B‐cell ALL at diagnosis. The findings in twenty‐one Ph‐0positive (Ph+) childhood common/precursorB (c/preB) cases were compared with 254 Ph‐negative (Ph−) ALL cases.

Results

A large range of LC50 values was found within the Ph+ patients. Moreover, LC50 values did not differ significantly between Ph+ and Ph− samples for prednisolone, dexamethasone, L‐asparaginase, vincristine, anthracyclines, thiopurines, epipodophyllotoxins, and 4H00‐ifosfamide, even after matching for important prognostic features (age, white blood cell count (WBC), and immunophenotype). Adult Ph+ (n = 12) ALL was more resistant to prednisolone (> 270‐fold, P = 0.030), and displayed an overall tendency to resistance when compared to matched cases of Ph− (n = 15) adult precursor B‐cell ALL. Within Ph+ ALL, in vitro prednisolone resistance increased significantly with age (P = 0.006). The expression of lung resistance protein (LRP), but not P‐glycoprotein (P‐gp) or multidrug resistance protein (MRP), was significantly higher in all Ph+ patients.

Conclusions

Both childhood and adult Ph+ precursor B‐cell ALL samples display a heterogeneous in vitro resistance profile, with relatively sensitive and resistant cases. The adult Ph+ samples, however, are generally more resistant compared to matched Ph− controls, reaching significance for prednisolone. The correlation of prednisolone resistance with age within the Ph+ cases might help explain the poorer prognosis of adult Ph+ ALL. Med Pediatr Oncol 2002;38:379–386. © 2002 Wiley‐Liss, Inc.
Gene rearrangements in radiation‐induced thyroid carcinogenesis*
Authors: Rabes Hartmut M.
Published: August 2002

Background

Radiation is an accepted risk factor for thyroid carcinogenesis in children. Recent observations in large cohorts of children and young adults who developed papillary thyroid carcinomas (PTC) related to accidental radiation exposure after the Chernobyl reactor accident revealed typical genetic aberrations shedding light on genetic determinants and mechanisms of radiation‐induced carcinogenesis.

Procedure

A molecular genetic analysis was performed on 191 post‐Chernobyl PTC by RT‐PCR, multiplex PCR, DNA sequencing, and in some cases 5'RACE. Determination of point mutations was by means of PCR and either allele‐specific oligonucleotide hybridiziation or SSCP and DNA sequencing.

Results

In various sporadic thyroid tumor types of adults structural genetic aberrations have been found involving mutations of RAS (codon 12, 13, 61), p53 (exons 5 to 8), Gsα (codon 201 and 227), and, at a low prevalence, the receptor tyrosine kinases RET or NTRK1. In contrast, in radiation‐induced PTC of children RET rearrangements are by far the most prevalent genetic aberrations. In these RET rearrangements, the transmembrane and extracellular domains of RET are lost, and are replaced by parts of other genes at the 5′ end. These genes always contain coiled‐coil domains with dimerization potential and lead to constitutive, ligand‐independent activation of the ret tyrosine kinase domain at the 3′ end of the fusion product. The most frequent radiation‐induced RET gene fusions involve the ELE1 (ARA70) gene, a transcription coactivator of the androgen receptor (PTC3), and H4, a gene of unknown function (PTC1). Both rearrangements originate from DNA double strand breaks with repair by intrachromosomal balanced paracentric inversion and recombination by illegitimate DNA endjoining at small stretches of homologous nucleotide sequences and direct or inverted repeats, without significant breakpoint clusters in the involved introns. In addition, five different RET‐fused genes, RIα, GOLGA5, HTIF, RFG7 and RFG8, have been detected leading to the PTC2, 5, 6, 7 and 8 types of RET rearrangements, respectively. Each fusion leads, in principle, to the same effect: The ret tyrosine kinase is uncoupled from its stringent physiological regulation by replacement of its 5′ end and is aberrantly activated by the 5′ parts of fused genes in thyrocytes that do not normally express ret tyrosine kinase. Ectopic ret expression, clonal expansion and early invasion are peculiar to the affected cells. The RET‐fused gene is obviously decisive for modulating tumor development: ELE1/RET rearrangements lead to most rapid tumor progression and are related to the solid variant of PTC, in contrast to H4/RET rearrangements connected with papillary or follicular variants of PTC.

Conclusions

Typical genetic aberrations are produced by radioiodine uptake in the juvenile thyroid gland. They act as determinants of phenotype, biology, and clinical course of radiation‐induced papillary thyroid carcinomas. Med. Pediatr. Oncol. 36:574–582, 2001. © 2001 Wiley‐Liss, Inc.
Thyroidal uptake and radiation dose after repetitive I‐131‐MIBG treatments: Influence of potassium iodide for thyroid blocking
Authors: Brans Boudewija , Monsieurs Myriam , Laureys Genevieve , Kaufman Jean‐Marie , Thierens Hubert , Dierckx Rudi A.
Published: August 2002

Background

In I‐131‐MIBG therapy, I‐131‐iodide can be released from the I‐131‐MIBG molecule. Hypothyroidism might result from the undesirable irradiation of the thyroid gland. To prevent this, stable iodide such as potassium iodide (KI) is given to oversaturate the thyroid before I‐131‐MIBG is administered.

Procedure

In the present study, the incidence of hypothyroidism (elevated TSH) was correlated with the thyroidal uptake of I‐131 and dose (MIRD dosimetry) after 35 individual treatments in ten patients. Iodine‐131‐MIBG therapy was performed using a modified dosage of 1.9–11.1 GBq (50–300 mCi) IV. Premedication with KI was done as recommended with a dose of 100 mg KI orally from 2 days before until 4 weeks after I‐131‐MIBG.

Results

The absorbed thyroidal dose amounted to a very variable range of 0.2 (patient # 1) up to 30.0 (patient 3) Gy with 7.1 ± 7.9 Gy per treatment and 24.1 ± 19.2 Gy per patient (mean ± SD), despite the same and compliantly taken KI premedication protocol. Up to now, 4/10 or 40% of patients have developed hypothyroidism after a mean follow‐up period of 11 months and a mean total administered dose of 18.7 GBq (505 mCi). A trend towards higher thyroidal doses was seen in the hypothyroid patients.

Conclusions

This study observes a general high inter‐ and intra‐individual variability in radio‐iodide uptake in the thyroid after I‐131‐MIBG therapy despite KI premedication, as well as possible occurrence of hypothyroidism. A dose‐response relationship needs confirmation on a larger cohort of patients to reach statistical value. An alternative thyroid cytoprotection strategy for possible long‐term survivors may be considered. Med Pediatr Oncol 2002;38:41–46. © 2002 Wiley‐Liss, Inc.
Comparison of manual and computer‐generated customized blocks for whole brain fields used in the treatment of medulloblastoma
Authors: Liu M. , Carrie C. , Parker W. , Freeman C.R.
Published: August 2002

Background

By using CT simulation and three‐dimensional planning, we have developed a simple but accurate method of producing customized blocks for the cranial fields in the treatment of medulloblastoma. We compare here the margins and the volume of normal tissues included in the treatment volume with those obtained using blocks generated manually.

Procedure

Customized blocks for the whole brain field are generated using CT planning and autoblock function. The clinical target volume (CTV) is defined as the whole cerebrospinal fluid pathway, and the whole brain and spinal cord are contoured. A margin of 1.1 cm is generated using the autoblock function to account for set‐up errors (3–5 mm) and penumbra (approximately 7 mm). A separate set of blocks was generated manually without the knowledge of the ones generated by the CT‐simulator. These 2 sets of blocks were compared for a cohort of 7 consecutive patients.

Results

Overall, the manual blocks and the computer‐generated blocks were quite similar. Those generated manually had more variations; they were always tighter (median of 6 mm tighter; range: 3–7 mm) at the level of the cribriform plate and in 5/7 patients were more generous (median of 6 mm more generous, range: 0–6 mm) at the temporal lobes. Dosimetric analysis showed that both methods provide adequate coverage of the CTV, with 100% of the CTV receiving > 95% of the prescribed dose for both.

Conclusions

The customized block method for whole brain fields is simple to use and ensures adequate coverage of the target volume. Med Pediatr Oncol 2002;38:55–57. © 2002 Wiley‐Liss, Inc.
A tutorial comparison of the NMRIT and LAOCOON approaches for analyses of complex solution‐phase nuclear magnetic resonance spectra
Authors: Manatt Stanley L.
Published: August 2002

For spin ½ nuclei the two most frequently used iterative approaches for determinations of NMR chemical shifts (hi) and coupling constants (Ji), NMRIT and LAOCOON, are discussed. When multiple pulse techniques for extraction of these parameters fail or lead to complicated spectra in the cases of very strongly coupled spin systems and systems involving magnetically nonequivalent, chemical shift equivalent nuclei, recourse to these iterative methods is necessary. The former approach employs the energy levels derived from the observed transition frequencies, whereas the latter approach uses the observed transition frequencies. Derivations of the general iterative equations for both approaches are given, along with the specific equations for the ABC spin system. The matrix nature of the derivation of these equations is stressed. Also discussed is the modified NMRIT program, NMRENIT, which has major advantages over the former in cases with symmetry and in cases where not enough lines can be assigned to link all the energy levels. The advantages of the latter program over LAOCOON in certain cases are discussed. Some general advice on the use of both approaches is presented. The Hoffman energy level approach is also discussed and it is shown that it yields the same iterative equations as the LAOCOON approach. Copyright © 2002 John Wiley & Sons, Ltd.