bluuebunny/crossref_metadata_2025 huggingface dataset:
Does stimulation of the GPi control dyskinesia by activating inhibitory axons?
Authors: Wu Y.R. , Levy R. , Ashby P. , Tasker R.R. , Dostrovsky J.O.
Published: August 2002

A 69‐year‐old woman with Parkinson's disease and levodopa‐induced dyskinesias had a deep brain stimulation (DBS) electrode inserted into the right globus pallidus internus (GPi). During the operation, the GPi was mapped with dual microelectrode recordings. Stimulation through one microelectrode in GPi inhibited the firing of GPi neurons recorded with another microelectrode 600–1,000 μm distant. The inhibition could be obtained with pulse widths of 150 μs and intensities as low as 10 μA. Single stimuli inhibited GPi neurons for ∼50 ms. Trains of 300 Hz stimuli inhibited GPi neuron firing almost completely. Postoperatively, stimulation through macroelectrode contacts located in the posterior ventral pallidum controlled the patient's dyskinesias. The effect could be obtained with pulse widths of 50 μs and frequencies as low as 70–80 Hz. We postulate stimulation of the ventral pallidum controls dyskinesias by activating large axons which inhibit GPi neurons. © 2001 Movement Disorder Society.
Combined pancreaticoduodenal‐kidney transplantation in rats
Authors: Yongping Gu , Jianyun Gu , Jieshou Li
Published: August 2002

The objective of this work was to establish a stable and simple simultaneous pancreaticoduodenal‐kidney transplantation model in rats. The methods involved harvesting a pancreaticoduodenal‐kidney (left) (PDK) and 1‐cm inferior vena cava (IVC) with a 0.5‐cm left and right iliac communis vein from donors and to “cuff” anastomose between portal vein and right iliac communis vein, left kidney vein, and left iliac communis vein, converging donor portal vein and left kidney vein into IVC together. Next, we performed an anastomosis of the donor arterial segment and recipient abdominal aorta and a “cuff” anastomosis between donor IVC and recipient left kidney vein. Of 67 transplanted rats in which diabetes was induced, 57 survived >7 days, 55 survived 1 month, 54 rats have survived >4 months. In 51 rats, nonfasting plasma glucose levels were euglycemic. We performed three “cuff” anastomoses to simplify the surgical procedure and to shorten the ischemia time of the graft; the recipient vein system has an integrated endovenous membrane to avoid venous thrombi in venous anastomosis sites. © 2001 Wiley‐Liss, Inc. MICROSURGERY 21:55–57 2001
Processed porcine collagen tubulization versus conventional suturing in peripheral nerve reconstruction: An experimental study in rabbits
Authors: Heijke Guda C.M. , Klopper Pieter J. , Van Doorn Ilona B.M. , Baljet Bob
Published: August 2002

In peripheral nerve reconstruction, various procedures are used. One of the procedures that received the most interest in the past decade is the tubulization technique for small nerve gaps. A disadvantage in the use of non‐biodegradable tubes is that the material often has to be removed owing to its mechanical properties. Some investigators, in exploring the use of collagen tubes, being a natural biodegradable material, found either allogenicity or xenogenicity and immune responses that may inhibit nerve regeneration. Processed porcine collagen (PPC) is a new inert and biodegradable material that has a favorable effect on wound healing, as demonstrated by experiments on other tissues. The aim of our study was to compare the healing of nerve sutures with PPC tubes with conventional end‐to‐end sutures. In our experiments, we reconstructed the saphenous nerves of 27 rabbits. In series 1 (n = 12) and 2 (n = 12), PPC tubes were slid over an end‐to‐end nerve suture without or with a 10‐mm nerve gap, respectively. In series 3 (n = 12), conventional suturing was performed in the collateral saphenous nerves of the animals of series 1. Epineurial suturing was performed. Three other non‐operated saphenous nerves served as controls. The healing was studied after 3, 6, and 12 months in sections stained by monoclonal antibodies and by conventional histologic staining. Morphometric analysis of the regenerating axons was done by using confocal scanning laser microscopy (CLSM). Data analysis was carried out using a software program especially developed for this purpose. All results were evaluated statistically. Our results showed that during the healing period in the distal nerve stump, the number of axons of the PPC procedure with a 10‐mm gap was significantly higher than that in the procedure without a gap. At 12 months, the mean number of axons of all procedures was significantly lower than in the non‐operated nerve, and the mean axon diameter in all distal stumps did not differ significantly from that of the non‐operated nerve. In the distal nerve stump, the ratio of total axon area to total fascicle area in the PPC procedure with a gap was significantly higher than that in the conventional suturing procedure. After 12 months, there was no significant difference between the percentages of axon outgrowth of the PPC procedure without a gap, the conventional suturing procedure, and the non‐operated nerve (100%). The percentage of axon outgrowth in PPC with a gap was significantly higher than in the other procedures. © 2001 Wiley‐Liss, Inc. Microsurgery 21:84–95 2001
In vivo measurement of oxygen‐derived free radicals during reperfusion injury
Authors: Büttemeyer Rolf , Philipp Andreas W. , Mall Julian W. , Ge Bixia , Scheller Frieder W. , Lisdat Fred
Published: August 2002

By use of an optimized cytochrome c‐based biosensor, superoxide radical production was measured continuously in vivo. The aim of this study was the online detection of superoxide concentration during reperfusion after a variable time of ischemia. Measurements were performed by placing the detecting sensor into gastrocnemius muscle tissue. Ischemia was induced by clamping the vena and arteria femoralis. Current response of the sensor was recorded continuously as an equivalent for superoxide concentration. Ischemia times varied from 5 to 120 minutes. The minimum ischemia time to record superoxide production was 10 minutes. By inducing longer periods of ischemia, an increase in superoxide concentration reached its highest levels at 2 hours. Furthermore, the total time of superoxide production after reperfusion depended on the total time of ischemia. © 2002 Wiley‐Liss, Inc. MICROSURGERY 22:108–113 2002
Existence implies uniqueness for a class of singular anisotropic elliptic boundary value problems
Authors: Cîrstea Florica Şt. , Radulescu Vicenţiu D.
Published: August 2002

We consider a singular anisotropic quasilinear problem with Dirichlet boundary condition and we establish two sufficient conditions for the uniqueness of the solution, provided such a solution exists. The proofs use elementary tools and they are based on a general comparison lemma combined with the generalized mean value theorem. Copyright © 2001 John Wiley & Sons, Ltd.
The l.s.c. regularization of the Signorini problem in plasticity
Authors: Bojarski Jaroslaw L. , De Schepper Hennie
Published: August 2002

In this paper we study the problem of the lower semicontinuous (l.s.c.) regularization of the Signorini problem in Hencky plasticity for a special class of elastic‐perfectly plastic solids. We show that the relaxation given by Bojarski (Nonlinear Analysis, Theory, Methods & Applications 1997; 29(10) 1091) is the l.s.c. regularization of the Signorini problem in the case that the elastic‐perfectly plastic potential sastisfies a specific condition, which is a modification of the von Mises plastic principle. Moreover, we show the relation between the relaxation proposed by Suquet (Non‐smooth Mechanics and Applications. Springer Verlag: Wien, 1988) and the relaxation proposed by Kohn and Temam (Applied Mathematics and Optimization 1993; 10(1):1). Copyright © 2002 John Wiley & Sons, Ltd.
Design of polarization‐preserving circular waveguide filters with attenuation poles
Authors: Amari Smain , Bornemann Jens
Published: August 2002

Bandpass filters in circular waveguide technology are designed to have enhanced stopband responses. Highly dispersive coupling sections are introduced to replace regular circular irises. The resulting direct‐coupled resonator bandpass filters have the advantage of preserving the polarization of the incident excitation while providing sharp cutoff skirts. Attenuation poles at finite frequencies are generated on either side of the passband by using radial stubs, which also perform the role of inverters. In contrast to the pole‐extraction technique, or the classical technique of using stubs for the sole purpose of pole generation, the zero‐generating elements act as inverters, and are not necessarily the first elements at the input and/or output. A simple approximate design technique which provides adequate starting values for optimization‐based design is also introduced. Design examples are presented to show the validity of the approach and the performance of these filters. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 334–336, 2001.
Coplanar propagation on magnetic substrates
Authors: Hinojosa Juan
Published: August 2002

Analytical relationships and graphs are represented for the effective relative permeability, filling factors, and characteristic impedance of magnetic substrates for coplanar lines. The determination of these analytical relationships was obtained from Veyres' formulas for dielectric substrates and Pucel's duality relationship between magnetic and dielectric substrates. The graphs are discussed, and analytical relationships are validated. These analytical relationships represent a suitable set for the design of coplanar lines for hybrid and monolithic MICs (microwave integrated circuits). © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 365–368, 2001.
A planar inverted‐L patch antenna for 2.4/5.2 GHz dual‐band operation
Authors: Kuo Yen‐Liang , Wong Kin‐Lu
Published: August 2002

A new design of a dual‐band planar inverted‐L patch antenna suitable for applications in WLAN (2400–2484 MHz) and HIPERLAN (5150–5350 MHz) systems is proposed. By using an inverted‐L radiating patch, in which two additional narrow slits are inserted at the radiating edge to effectively control the excited patch surface current distributions, the proposed antenna can generate two operating frequencies at 2.4 and 5.2 GHz. In addition, wide impedance bandwidths are obtained. The proposed antenna has 10 dB return‐loss bandwidths of 7.5 and 8.1% in the 2.4 and 5.2 GHz bands, respectively, and the obtained peak antenna gain also reaches 5.7 and 6.4 dBi for operating frequencies within the 2.4 and 5.2 GHz bands, respectively. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 394–396, 2001.
Broadband hybrid microstrip couplers—Amplitude and phase
Authors: Queck Cham Kiong , Davis Lionel E.
Published: August 2002

Several designs for a 180° hybrid coupler are discussed. Using the stepped‐impedance method, the bandwidth of an 11 GHz hybrid coupler is increased to approximately 1.6 times the bandwidth of a conventional hybrid coupler. Comparisons are made between conventional and broadband hybrid couplers, as well as between circular and rectangular designs, and the phase behavior of each is compared for the first time. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 254–259, 2002.
Electromagnetic scattering from nonuniform magnetized ferrite cylinder
Authors: Hu B. J. , Yung E. K.‐N. , Sheng X. Q.
Published: August 2002

An analytical technique, called the scattering matrix method, is developed to analyze the scattering of a plane wave from a nonuniform ferrite cylinder. It is proved that the derived formulas for nonuniform ferrite cylinders can be degenerated to the formulas for uniform ferrite cylinders published in the literature. The characteristics of scattering by ferrite cylinders with a linear profile are investigated versus applied magnetic fields and wave frequencies. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 268–272, 2002.
BER analysis of synchronous fiber‐optic CDMA networks with suboptimal decision threshold
Authors: Kuo Ching‐Chih , Wu Jyh‐Horng
Published: August 2002

The bit‐error rate (BER) of synchronous optical CDMA networks with a fixed (suboptimal) decision threshold is derived. The strategy used offers the advantage that the network need not dynamically monitor the number of users. The numerical results are satisfactory when compared with previous literature based on an optimal threshold. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 293–296, 2002.
Fast computation of FET power gains
Authors: Paoloni Claudio
Published: August 2002

Power gain definitions are fundamental parameters in the design of FET small‐signal amplifiers. In this Letter, a simple and direct method to compute the various gain definitions of FET up to 60 GHz is demonstrated. A set of simple equations to compute the S parameters from the FET complete π model are used. The power gain definitions are calculated from the S‐parameter modules derived from these equations. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 104–106, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10235
Material imaging with the use of a microwave cavity perturbation technique
Authors: Zürcher J‐F.
Published: August 2002

A measurement method using a microwave cavity perturbation technique is described. It allows high‐quality imaging of various materials, ranging from metals to dielectrics and biological objects. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 106–112, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10246
Extraction of lumped‐element equivalent‐circuit models of microstrip discontinuities using the finite‐difference time‐domain method
Authors: Farahat Nader , Yu Wenhua , Mittra Raj
Published: August 2002

This Letter presents a method for extracting the lumped‐element equivalent‐circuit models of microstrip discontinuities by using the finite‐difference–time‐domain (FDTD) method. The cascading properties of the ABCD matrix are used to de‐embed the attachment lines, leading to the two‐port matrix of the discontinuity section alone. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 132–134, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10254
Statistical construction of accurate CAD models using measured data
Authors: Naishadham Krishna , Leiker William
Published: August 2002

Component models available in CAD software do not consider the statistical variation and the layout‐ or package‐specific parasitic effects of components. Because of the complexity of device packages, the well‐established EM simulation alternative can only be applied to relatively simple circuits. This Letter presents a methodology to construct statistically a representative component model from a measured database, and show how such a model can be used in a circuit simulator for effective circuit design. All the parasitic effects of the circuit components are incorporated through measurements. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 233–238, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10284
Fundamental study of a λ/4 wave absorber using FSS for two frequencies
Authors: Itou Akihiko , Wada Kouji , Hashimoto Osamu
Published: August 2002

The aim is to study basic characteristics of a frequency selective surface (FSS) for two frequencies and its application to the wave absorbers using the FSS for two frequencies, which are fabricated by two absorption films. In this study, the shielding characteristics with the frequency‐selection by FSS, absorption, and shielding characteristics of the proposed wave absorber using FSS are examined experimentally. Good performance of the FSS and the wave absorber using FSS were obtained, as expected. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 321–322, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10308
Component synthesis in optoelectronics modelling
Authors: Sewell P. , Vukovic A. , Benson T. M.
Published: August 2002

A CAD package was developed that accepts a functional design specification for a multilayered optical slab waveguide and returns a physical description of a structure in a form immediately suitable for fabrication. It is shown that the definition of a figure of merit for the design requires that the importance of the design criteria be suitably weighted. The implications of the present work for the synthesis of more general optoelectronic components and circuits are discussed. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 325–327, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10310
Novel model for the estimation of radiation emission from printed circuit boards with narrow ground pattern
Authors: Chen I‐Fong , Hsue Ching‐Wen
Published: August 2002

A circuit model, based on TEM assumption, is provided for estimating the radiation emission of a typical PCB geometry, namely, microstrip. We find that an imperfect ground trace will lead to an unbalanced circuit and radiate EM energy significantly. Measured data are presented to confirm the results of theoretical study. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 332–335, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10313
Frequency‐dependent expressions for inductance and resistance of microstrip line on silicon substrate
Authors: Ymeri H. , Nauwelaers B. , Maex Karen , De Roest D. , Vandenberghe S.
Published: August 2002

A new closed‐form expression to calculate frequency‐dependent distributed inductance and the associated distributed series resistance of microstrip lines on a lossy silicon substrate (CMOS technology) are presented. The proposed analytic model for series impedance is based on a self‐consistent field method and the vector magnetic potential equation. It is shown that the calculated frequency‐dependent distributed inductance and the associated resistance are in good agreement with the results obtained from rigorous full wave solutions and CAD‐oriented equivalent‐circuit modeling approach. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 349–352, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10318
New method of timing jitter measurement in soliton communication systems
Authors: Avagyan Razmik , Daryan Ara , Divanyan Edward , Hovhannisyan Davit , Kalayjian Zaven , Meghavoryan David , Stepanyan Komitas
Published: August 2002

A mathematical description of the spectral and temporal changes in a probe pulse occurring as a result of cross‐phase modulation interaction between the probe pulse and a soliton with a nonoverlapping spectrum and different delay copropagating in a single‐mode fiber was obtained. We show that information on the time delay between a soliton and a probe pulse can be extracted by analyzing the probe pulse spectral density distribution. This information can be used to measure timing jitter in a soliton communication systems. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 33: 361–365, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10322
Long‐wavelength strained‐layer InGaAs/GaAs quantum‐well lasers grown by molecular beam epitaxy
Authors: Piwoński T. , Sajewicz P. , Kubica J. M. , Zbroszczyk M. , Regiński K. , Mroziewicz B. , Bugajski M.
Published: August 2002

The operation in the 1020 nm wavelength range of strained‐layer InGaAs/GaAs separate‐confinement‐heterostucture lasers grown by molecular beam epitaxy is reported. The active region is formed by a single 80 Å thick InGaAs quantum well with an indium content of 25%, which is close to critical parameters. This paper provides the operating characteristics of broad‐area uncoated Fabry–Perot structures with cavities of 700 μm length measured in the pulsed regime. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 75–77, 2001.
Superconducting lumped‐element filter with spiral inductors
Authors: Barinov A. E. , Zhgoon S. A. , Sukhov V. A. , Su H. T. , Lancaster M. J. , Huang F.
Published: August 2002

This paper presents theoretical and experimental results for a novel three‐pole HTS lumped‐element narrowband filter with central frequency 1.7775 GHz and 0.84% fractional bandwidth. A high degree of miniaturization is reached by the use of planar coils as inductance elements. Good performance on YBCO devices has been achieved. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 94–95, 2001.
Pseudospectral time‐domain algorithm applied to electromagnetic scattering from electrically large objects
Authors: Fan Guo‐Xin , Liu Qing Huo
Published: August 2002

The pseudospectral time‐domain (PSTD) algorithm is extended to model the electromagnetic scattering from both 2‐D and 3‐D objects. The plane‐wave excitation and the time‐domain near–far field transforms in the stretched coordinates are efficiently incorporated into the scattered‐field PSTD algorithm. Numerical results demonstrate the effectiveness of the algorithm in wave‐scattering problems. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 123–125, 2001.
An analytical study of the cutoff conditions and dispersion curves of an optical fiber with a core slightly flattened on one side
Authors: Joshi M. , Singh Vivek , Prasad B. , Ojha S. P.
Published: August 2002

In this paper, we present a simple analytical method based on coordinate transformation for the calculation of the dispersion characteristics of an optical fiber which is slightly flattened on one side. We choose the new and appropriate orthogonal coordinates (ξ, η, z) for the proposed waveguide structure, and impose the boundary condition under a weak guidance condition to obtain the modal eigenvalue equation. Using this equation, we achieve numerical results in the form of dispersion curves and cutoff frequencies. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 136–139, 2001.
A new MESFET nonlinear model
Authors: Ooi B. L. , Ma J. Y. , Leong M. S.
Published: August 2002

In this paper, a new empirical model for the dc I–V characteristics of a GaAs MESFET transistor is presented. The conventional approach for modeling the dc I–V characteristics of a MESFET transistor adopts the hyperbolic‐tangent dependence on Vds through the observation of the Ids versus Vds curve. The derived model is capable of accurately modeling the device current–voltage behavior in different operation regions. The new model equations describe the device drain current as a polynomial of the effective gate–source voltage Veff, which is in turn a rational function of Vgs, and the parameters for the polynomial vary with Vds. Model parameter extraction is made for a 0.5 μm gate‐length MESFET device. Measured and modeled results are compared, and good agreement is obtained. A comparison among the proposed model, Curtice's and Chalmers' model, and Parker's model are also made in this paper. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 226–230, 2001.
Slot‐line‐excited equilateral‐triangular dielectric resonator antenna of very high permittivity
Authors: Lo H. Y. , Leung K. W. , Luk K. M.
Published: August 2002

A slot‐line‐excited equilateral‐triangular dielectric resonator antenna (DRA) of very high permittivity (εr=82) is investigated experimentally. The triangular DRA is operated at its fundamental broadside TM1, 0, −1‐mode. An improved bandwidth of ∼5%, which is 1.7 times higher than in the previous aperture‐coupled version, is obtained for the new configuration. The return loss, radiation patterns, and antenna gain of the new configuration are presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 230–231, 2001.
The forward–backward method with a novel spectral acceleration algorithm (FB/NSA) for the computation of scattering from two‐dimensional large‐scale impedance random rough surfaces
Authors: Torrungrueng D. , Johnson Joel T.
Published: August 2002

The forward–backward method with a novel spectral acceleration algorithm (FB/NSA) has been shown to be a very efficient 𝒪(Ntot) iterative method of moments, where Ntot is the total number of unknowns to be solved, for the computation of electromagnetic wave scattering from two‐dimensional (2‐D) perfectly conducting rough surfaces. In this paper, the method is extended to treat impedance rough surfaces. It is found that the 2‐D NSA algorithm for the impedance case is similar to the one for the perfectly conducting case. Comparisons of numerical results between the standard 2‐D FB and 2‐D FB/NSA methods show that the latter yields very accurate results with an appreciable reduction of CPU time. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 232–236, 2001.
Reduced‐sidelobe millimeter‐wave broadband antenna
Authors: Kumar Ashwani , Pal Ram , Sudhir H.
Published: August 2002

A broad frequency‐band millimeter‐wave antenna working over 18–40 GHz has been designed and developed to realize low‐sidelobe fan‐beam radiation patterns. The antenna system consists of a cylindrical parabolic reflector fed by an offset double‐ridged horn antenna feed. This type of antenna finds extensive use as a rotary direction‐finding (RDF) system in electronic warfare applications. The design approach and measured results for the antenna over 18–40 GHz have been presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 245–248, 2001.
Synthesis and design of N‐order filters with N‐transmission zeros by means of source–load direct coupling
Authors: Montejo‐Garai José R. , Rebollar Jesús M.
Published: August 2002

An extension is made to the synthesis of microwave filters with cross couplings between nonadjacent cavities to the case where there is a direct coupling between the input and output ports, i.e., the source and the load of the device. This coupling extends to N‐order filters the possibility to accomplish responses with N finite transmission zeros. In addition, symmetric and asymmetric rejection slopes out of band and equalized group delay can be obtained simultaneously. Several examples of filter synthesis are presented to validate the proposed synthesis procedure. Finally, to show the applicability of the load–source direct coupling, a second‐order Ku‐band filter with two transmission zeros has been designed using three physical structures: two different rectangular waveguide E‐plane configurations and one H‐plane. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 248–252, 2001.
Gain calculations in erbium‐doped fibers using field approximations
Authors: Sunanda  , Jain Geetika , Sharma Enakshi Khular
Published: August 2002

In this paper, we compare the use of various field approximations of modal fields for gain calculations in erbium‐doped fibers. Our results show that the use of an appropriately chosen rectangular approximation leads to simple analytical expressions for the gain characteristics, and still retains sufficient accuracy. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 256–259, 2001.
Interference reduction in synchronous fiber‐optic PPM–CDMA systems
Authors: Lee T. S. , Shalaby H. M. H. , Ghafouri‐Shiraz H.
Published: August 2002

A pulse‐position modulation (PPM) optical CDMA system with interference estimation and cancellation is proposed. Multiuser interference is estimated with the aid of modified prime code sequence properties. A comparison between the bit‐error rate (BER) of both the proposed system and the system without cancellation reveals that the former system improves the BER performance significantly. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 202–205, 2001.
Light guiding in optical fibers with Kerr‐like nonlinearity
Authors: Romanova Elena A. , Melnikov Leonid A. , Bekker Ella V.
Published: August 2002

Guiding properties of optical fiber with Kerr‐like nonlinearity are studied numerically using the finite‐difference beam‐propagation method to solve the scalar‐wave equation. The nonlinear fiber is shown to support fields with longitudinally invariant radial distributions having a mean‐squared beam width less than that of the linear fiber mode. The double‐mode propagation is shown to be unstable, and tends to convert into single‐mode propagation after some distance from the input endface of the fiber. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 212–216, 2001.
Three‐dimensional optical tomography of incomplete data
Authors: Zhengdong Wang , Zhixing Wang , Zhenhua Li , Anzhi He
Published: August 2002

In this paper, three‐dimensional optical computerized tomography in the case of severely incomplete projection data is discussed theoretically and experimentally. An orthogonal projection method has been proposed for optical tomography in the case of severely incomplete data. Some comparative numerical simulations and experimental results of traditional sampling method and the new method are given. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 57–59, 2001.
Bias correction and yield optimization of MMICs with external digital control
Authors: Scotti Giuseppe , Tommasino Pasquale , Trifiletti Alessandro
Published: August 2002

A new methodology for yield optimization of integrated circuits is presented. We propose a dc external control scheme which performs on‐line estimation of the active device model parameters and proper correction of the bias point. Design of a 2.5 Gbit/s front‐end amplifier has been performed, and a strong yield improvement has been found. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 134–137, 2001.
Study of the experimental performance of AR‐based data‐extrapolation algorithms for high‐resolution radar imaging
Authors: Kim Kyung‐Tae , Bae Ji‐Hoon , Seo Dong‐Kyu , Kim Hyo‐Tae
Published: August 2002

In this letter, we compare the experimental performance of data‐extrapolation algorithms for high‐resolution radar imaging. The three methods considered in this paper are based on the autoregressive (AR) model, including the Burg method, the modified covariance method, and the modified covariance method, coupled with singular value decomposition. The performance of each algorithm in terms of extrapolation accuracy is compared using the radar cross‐section (RCS) data of an F117 model measured in the compact range facility. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 151–156, 2001.
A demographic study of the clinical significance of minimal residual disease in children with acute lymphoblastic leukemia
Authors: Levett D. , Middleton P. , Cole M. , Reid M.M.
Published: August 2002

Background

Minimal residual disease (MRD) detected during remission might predict outcome in children with acute lymphoblastic leukemia. No population‐based studies have been carried out. We studied all children with ALL presenting over 5 years within a defined population to determine its clinical importance.

Procedure

Patients were investigated for the presence of unique clonal rearrangements of IgH and T‐cell receptor genes. Unique patient specific probes were used to detect, by polymerase chain reaction, the presence of clonal markers indicating MRD in mononuclear cells obtained from marrow samples at 1, 3, 5, and 24 months. The effect of MRD on event‐free survival was determined.

Results

Seventy‐seven of 120 children with ALL had informative markers and samples of remission marrow suitable for testing. Presence or absence of MRD did not significantly affect outcome. Gender (P < 0.04) and white cell count (P < 0.04) were independent prognostic factors. Analysis of only those cases with detectable MRD showed that cases with one blast per 100 mononuclear cells, or more, 28 days after starting treatment did worse than those with lower levels (hazard ratio 7.77, P < 0.02).

Conclusions

Mere presence or absence of MRD is probably too crude a measure to be useful and worse than other standard prognostic indicators. A threshold of 10−2 blasts at 28 days might be discriminatory, but should not be over‐interpreted. The number of patients available for this analysis (31) was small, the threshold and sampling points were arbitrary and any effects could be treatment regimen‐specific. Large prospective studies are needed. Med. Pediatr. Oncol. 36:365–371, 2001. © 2001 Wiley‐Liss, Inc.
Echocardiographic evaluation of patients cured of childhood cancer: A single center study of 117 subjects who received anthracyclines
Authors: Bossi Grazia , Lanzarini Luca , Laudisa Maria Luisa , Klersy Catherine , Raisaro Arturo , Aricò Maurizio
Published: August 2002

Background

The risk of cardiomyopathy following exposure to anthracycline in asymptomatic long‐term survivors of childhood cancer is still hard to predict and precisely quantify. To identify the impact of different cumulative doses, even within a non‐high dose range, and the echocardiographic parameters suitable for evaluating cardiac function, we studied diastolic and systolic echocardiographic parameters in a cohort of patients followed in a single center.

Procedure

A total of 117 subjects were studied at a median time of 7 years after treatment completion. A complete M‐mode, two‐dimensional and Doppler echocardiographic study was obtained at rest in all patients according to the standard recommendations of the American Society of Echocardiography.

Results

Ninety‐nine patients (85%) had completely normal cardiac function, while 18 had abnormal echocardiographic findings: 12 had one abnormal value, 5 had two, and 1 had three abnormal values. All the changes were in left ventricular dimensions, wall thickness or indices of systolic function; no alterations in left ventricular diastolic function parameters were found. None of the echocardiographic parameters correlated significantly with the cumulative dose of anthracyclines administered either at univariate analysis or after adjusting for sex, body surface area or considered risk factors.

Conclusions

Subjects exposed to a median cumulative dose of 214 mg/m2 had no echographic abnormalities a median of 7 years later. We did not find any correlation between cumulative anthracycline dose and the echocardiographic parameters tested. We now offer echocardiographic follow‐up to patients with mildly reduced fractional shortening and/or ejection fraction to rule out late onset dysfunction. Med. Pediatr. Oncol. 36:593–600, 2001. © 2001 Wiley‐Liss, Inc.
RB1 genetic testing as a clinical service: A follow‐up study
Authors: Cohen Jennifer G. , Dryja Thaddeus P. , Davis Katherine B. , Diller Lisa R. , Li Frederick P.
Published: August 2002

Background

Genetic testing for inherited predisposition to diverse cancers has recently become available as a clinical service. We conducted a follow‐up study of the initial series of US families who underwent RB1 genetic testing to evaluate long‐term effects of the service.

Procedure

We enrolled 52 of 71 eligible families who responded to a follow‐up study questionnaire administered 3–10 years after receipt of their RB1 results. Each family had one proband with unilateral, non‐familial retinoblastoma, which is associated with a 12% pre‐test probability of hereditary retinoblastoma. RB1 testing identified germline RB1 mutations in five patients, lowered the carrier probability to 2% in 21 patients, and did not substantially modify the carrier probability in the remaining 26.

Results

Diverse medical specialists offered and arranged for RB1 testing, and their recommendation was the most influential factor in the decision to be tested. Pre‐test counseling was provided by ophthalmologists (30), oncologists (11), and geneticists and genetic counselors (11). Most respondents, regardless of test result, were satisfied and perceived gains from their genetic testing. Based on small numbers, families with reduced likelihood of hereditary retinoblastoma reported more positive outcomes. Parents of RB1 carriers were more likely to seek medical services, worry, and decide against having more children.

Conclusions

This study demonstrates the feasibility of follow‐up studies of families who had genetic testing. Results from our small series suggest that genetic information and counseling are important components of RB1 clinical genetic testing, and long‐term adverse effects of testing are uncommon. Med Pediatr Oncol 2001;37:372–378. © 2001 Wiley‐Liss, Inc.
A phase I study of cranial radiation therapy with concomitant continuous infusion paclitaxel in children with brain tumors
Authors: Liu Li , Vapiwala Neha , Munoz Louis K. , Winick Naomi J. , Weitman Steven , Strauss Lewis C. , Frankel Lawrence S. , Rosenthal David I.
Published: August 2002

Background

The prognosis of children with high‐grade astrocytomas of the central nervous system is grim and has not been substantially improved by conventional chemoradiotherapy. We performed a multi‐institutional phase I study to determine the toxicities and tolerance of concurrent external beam radiation of the brain and a unique dose‐schedule of paclitaxel as a radiation sensitizer.

Procedure

Paclitaxel was delivered intravenously as a continuous 24 h/day, 7 days/week infusion during the entire 6‐week course of fixed schedule standard radiation therapy. The dose of paclitaxel was escalated in patient cohorts in standard phase I design.

Results

Eleven patients (eight brain stem gliomas, one glioblastoma multiforme, and two gliomatosis cerebri) were treated. Dose‐limiting toxicity was encountered in the two patients treated at 6 mg/(m2/24 h), both of whom developed severe obstipation requiring prolonged hospitalization.

Conclusions

We have shown in this first study of its kind that paclitaxel can be administered safely to children as a 6‐week continuous infusion concurrent with cranial irradiation. The maximally tolerated and recommended phase II dose is 4 mg/(m2/day). The benefits of taxanes as clinical radiation sensitizers for children with high‐grade gliomas, if any, remain to be determined. Med Pediatr Oncol 2001;37:390–392. © 2001 Wiley‐Liss, Inc.
13C Chemical‐shift tensors in an analogous series of heterosubstituted polycyclic aromatic compounds
Authors: Barich Dewey H. , Facelli Julio C. , Hu Jian Zhi , Alderman D. W. , Wang Wei , Pugmire Ronald J. , Grant David M.
Published: August 2002

The 13C principal values of the chemical‐shift tensor for fluorene, carbazole, dibenzofuran and dibenzothiophene were determined with the FIREMAT and PHORMAT experiments. Theoretical calculations (DFT) of the tensors were used as an aid to spectral assignment of the tensors, particularly in some positions in which the isotropic chemical shifts were accidentally degenerate. The principal values are discussed in terms of the effects of the heterosubstitutions. Copyright © 2001 John Wiley & Sons, Ltd.
Investigation of seeds with high‐resolution solid‐state 13C NMR
Authors: Bardet Michel , Foray Marie Françoise , Bourguignon Jacques , Krajewski Piotr
Published: August 2002

Magic angle spinning (MAS) 13C NMR was employed to investigate seeds. By combining single pulse excitation (SP) and cross‐polarization (CP) experiments, we showed that both liquid and solid domains of plant seeds (Arabidopsis thaliana, Lactuca sativa and Pisum sativum) can be characterized. Sharp signals in the CP/MAS spectra of seeds were attributed to triacylglycerols (TAG) belonging to the mobile phase by the use of a non‐quaternary suppression (NQS) experiment. Using the CP/MAS probe designed for solid‐state NMR, we demonstrated that the liquid domain of seeds could be readily analyzed under MAS conditions with classical multi‐pulse experiments normally devoted to liquid‐phase NMR. Such a non‐destructive approach should be useful to monitor the transformation of metabolites during physiological processes and the effects of chemical molecules on seeds and other similar biological systems. Copyright © 2001 John Wiley & Sons, Ltd.
mdr1a deficiency corrects sterility in Niemann–Pick C1 protein deficient female mice
Authors: Erickson Robert P. , Kiela Monica , Devine Patrick J. , Hoyer Patricia B. , Heidenreich Randall A.
Published: August 2002

Niemann–Pick type C disease is a progressive neurological disease with cholesterol storage in liver, and npc1−/− mice share these features and are sterile. We have searched for the cause of sterility and found normal folliculogenesis and progesterone levels but lack of implantation. Multiple drug resistance (MDR) P‐glycoproteins are plasma membrane proteins implicated in the movement of drugs and lipids across membranes. Their functions are inhibited by progesterone, which has been shown to alter cellular cholesterol homeostasis and has implicated P‐glycoproteins in the movement of cholesterol to the endoplasmic reticulum. We have introduced the mdr1a knockout into the npc1 mutant line. While the neurological disease continues at its usual rate, preventing the females from taking care of their litters, npc1−/−, mdr1a−/− females became fertile. Although the mdr1a P‐glycoprotein co‐localizes with caveolae, neither caveolin‐1 nor npc1 levels were significantly altered in the livers of double homozygotes. The absence of mdr1a was confirmed by immunoblotting, but npc1 deficiency was not associated with consistent changes in cerebellar mdr1a in mdr1a+/+ mice. The results show that a mdr1a mutation is an in vivo suppressor of female sterility in npc1 deficient mice. Mol. Reprod. Dev. 62: 167–173, 2002. © 2002 Wiley‐Liss, Inc.
Effect of elevated Ca2+ concentration in fusion/activation medium on the fusion and development of porcine fetal fibroblast nuclear transfer embryos
Authors: Cheong Hee‐Tae , Park Kwang‐Wook , Im Gi‐Sun , Lai Liangxue , Sun Qing‐Yuan , Day Billy N. , Prather Randall S.
Published: August 2002

The present study examined the effect of elevated Ca2+ concentration in fusion/activation medium on the fusion and development of fetal fibroblast nuclear transfer (NT) porcine embryos. Frozen‐thawed and serum starved fetal fibroblasts were transferred into the perivitelline space of enucleated oocytes. Cell fusion and activation were induced simultaneously with electric pulses in 0.3 M mannitol‐based medium containing 0.1 or 1.0 mM CaCl2. Some fused embryos were further activated 1 hr after the fusion treatment by exposure to an electric pulse. The NT embryos were cultured in vitro for 6 days. Fusion and blastocyst formation rates were significantly (P < 0.05) increased by increasing the Ca2+ concentration from 0.1 mM (67.1 and 6.3%) to 1.0 mM (84.7 and 15.8%). However, no difference in the number of cells in blastocysts was observed between the two groups. A higher percentage of blastocyst was also observed when control oocytes were parthenogenetically activated in the presence of elevated Ca2+ (19.3% vs. 32.4%, P < 0.05). When the reconstituted oocytes were fused in the medium containing 1.0 mM CaCl2, increasing the number of pulses from 2 to 3 or an additional activation treatment did not enhance the blastocyst formation rate or cell number in blastocysts. These results demonstrate that increasing the Ca2+ concentration in the fusion/activation medium can enhance the fusion and blastocyst formation rates of fetal fibroblast NT porcine embryos without an additional activation treatment. Mol. Reprod. Dev. 61:488–492, 2002. © 2002 Wiley‐Liss, Inc.
Subtilisin proprotein convertase‐6 expression in the mouse uterus during implantation and artificially induced decidualization
Authors: Wong Becky S.Y. , Liu Shiying , Schultz Gilbert A. , Rancourt Derrick E.
Published: August 2002

During implantation, a balance of factors regulates the invasive properties of the embryo and the anti‐invasive properties of uterine decidua. Although antiproteinases such as the metalloproteinase inhibitor TIMP‐3 are thought to play critical roles in preventing the overaggressive invasion of trophoblasts, the mechanism of antiproteinase regulation is unknown. Recently, the prohormone convertase SPC‐6 has been found to be co‐expressed in embryo‐proximal decidua in association with TIMP‐3. As members of this serine proteinase family are known to activate latent TGFβ family members which regulate decidual TIMP‐3 levels, we sought to characterize the expression of SPC‐6 during pregnancy and artificial decidualization. In this study, we demonstrate that the zone of SPC‐6 gene expression exhibits a great degree of temporal and spatial overlap with TIMP‐3 gene expression in uterine decidua from E5.5 through to E8.5. Like TIMP‐3, we demonstrate that SPC‐6 expression is induced during the decidual cell response using an in vivo model of artificial decidualization. Both the secreted and membrane bound forms of SPC‐6 are expressed throughout the period of decidualization, suggesting that SPC‐6 may play multiple roles during this developmental period. This is confirmed by our observation of the movement of SPC‐6 expression to the presumptive placental region, as TIMP‐3 expression regresses at the implantation site. Mol. Reprod. Dev. 61:453–459, 2002. © 2002 Wiley‐Liss, Inc.
Lipid dynamics in the plasma membrane of ram and bull spermatozoa after washing and exposure to macromolecules BSA and PVP
Authors: Wolfe Caroline A. , James Peter S. , Gunning A. Patrick , Ladha Shab , Christova Yonka , Jones Roy
Published: August 2002

Seminal plasma proteins and macromolecules in the external medium have a major influence on the functionality of sperm plasma membranes. In this investigation we have examined their effects on lipid diffusion in the surface membrane of ram and bull spermatozoa as measured by fluorescence recovery after photobleaching (FRAP). Results show that progressive removal of seminal plasma from ram spermatozoa by repeated centrifugation and resuspension in media ± 4% bovine serum albumin (BSA) or 0.4% polyvinlypyrrolidone (PVP) causes a reduction in lipid diffusion in all regions of the membrane. By contrast, bull sperm membranes respond with an increase in diffusion in all regions. Repeated washing of bull spermatozoa whose membranes were previously immobile (i.e., showed no recovery after FRAP) restored lipid diffusion suggesting an inhibitory effect of seminal plasma proteins. Further analysis by atomic force microscopy revealed a close association between BSA and the plasma membrane. It is concluded that diffusion of lipids in the plasma membrane of ejaculated ram and bull spermatozoa is influenced by seminal plasma proteins and the composition of the suspending medium. Mol. Reprod. Dev. 59:306–313, 2001. © 2001 Wiley‐Liss, Inc.
Rabbit cloning: Improved fusion rates using cytochalasin B in the fusion buffer
Authors: Li Guang‐Peng , Chen Da‐Yuan , Lian Li , Han Zhi‐Ming , Zhu Zi‐Yu , Seidel George E.
Published: August 2002

This study investigated the possibility of producing rabbits from embryos obtained by transfer of somatic cell nuclei; Muscle biopsies were taken from the upper part of the hind limb of fetuses at 24 days of gestation. Fetal fibroblasts were cultured in Dulbecco's Modified Eagle's medium (DMEM) supplemented with 10% FCS at 38°C in 5% CO2 in air. Cells were passaged at least three times; for 5 days prior to nuclear transfer, cells were cultured in 0.5% FCS medium to induce them into G0. These cells then were placed into the perivitelline space of enucleated rabbit MII stage oocytes. Fusion media were Ca/Mg‐containing 0.3 M mannitol (Buffer 1) or 0.3 M mannitol plus 7.5 μg/ml cytochalasin B (CB) (Buffer 2). Fusion was studied with 6 protocols: culture of donor cell‐cytoplast complexes (CCCs) in TCM199 for 0, 30, or 60 min after micromaniupulation and electrical stimulation in Buffer 1 or Buffer 2. Fusion rates were 57.4, 42.9 and 52.8%, respectively, in groups 0 + B1, 30 + B1, and 60 + B1, significantly lower than the rates in groups 0 + B2, 30 + B2 and 60 + B2 (75.9, 75.7, and 76.4%, respectively) (P < 0.05). Thus, CB in electrical fusion buffer improved the fusion rate. The percentages of blastocyst formation were 40% in 0 + B2 and 37.1% in 0 + B1 groups, significantly higher (P < 0.05) than those in 30 + B1 (20%), 30 + B2 (15.6%), 60 + B1 (13%) and 60 + B2 (8.3%). A total of 653 cloned embryos were at 1‐cell, 2–4‐cell, or morula/blastocyst stages were transferred to 44 mated or non‐mated synchronized recipients. No cloned embryos developed to term. Mol. Reprod. Dev. 61: 187–191, 2002. © 2002 Wiley‐Liss, Inc.