bluuebunny/crossref_metadata_2025 huggingface dataset:
A 77‐GHz Marchand balun for antenna applications in BiCMOS technology
Authors: Wang Guoan , Bavisi Amit , Woods Wayne , Ding Hanyi , Mina Essam
Published: January 2011

In this article, the design and measurement of a 77‐GHz Marchand balun matched to 50 Ω single‐ended and 100 Ω differential‐ends using multiple metal layers in silicon technology is discussed. The balun is measured with an insertion loss of 1.8 dB at 77 GHz, an amplitude imbalance of ±1.8 dB, and phase imbalance of ±1.5°. Also, this article presents the effect of parasitic reactance in the load terminations and dummy metal fills on balun's performance. It was found that the interlevel dummy metal fills and increase the insertion and also cause significant amplitude imbalance in the balun especially at frequencies above 50 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:664–666, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25756
Accurate GaN HEMT nonquasi‐static large‐signal model including dispersive effects
Authors: Crupi Giovanni , Raffo Antonio , Schreurs Dominique M. M.‐P. , Avolio Gustavo , Vadalà Valeria , Di Falco Sergio , Caddemi Alina , Vannini Giorgio
Published: January 2011

The purpose of this study is to present an advanced technique for accurately modeling the behavior of a GaN HEMT under realistic working conditions. Since this semiconductor transistor technology has demonstrated to be very well suited for high‐frequency (HF) high‐power applications, an equivalent circuit model is developed to account for the device nonlinearities at microwave frequencies. In particular, the proposed model includes bias dependence of both low‐frequency (LF) dispersive effects affecting GaN devices and HF nonquasi‐static effects, since these two types of frequency dependent phenomena play a crucial role under microwave large‐signal condition. The extraction procedure consists of two main steps. First, an accurate multibias small‐signal nonquasi‐static equivalent circuit is analytically extracted from scattering parameters measured under a wide range of bias points. Thereafter, this linear model is used as a cornerstone for building a nonlinear nonquasi‐static equivalent circuit, which is expanded to account for the LF dispersive phenomena by using an empirical formulation directly identified from the HF large‐signal measurements. The accuracy of the proposed modeling approach is completely and successfully verified by comparing model simulations with LF and HF large‐signal measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:692–697, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25757
Analysis and modeling of dual‐band ACMPA with asymmetric crossed slots
Authors: Lim Sang Ho , Jung Chae Hyun , Kim Se Young , Myung Noh Hoon
Published: January 2011

This article describes an accurate and efficient modeling of dual‐band aperture‐coupled microstrip patch antennas (ACMPAs) that have two types of asymmetric crossed slots.An asymmetric crossed slot ACMPA (ACS‐ACMPA) is initially studied, and an asymmetric H‐shaped crossed slot ACMPA (AHSCS‐ACMPA) is then proposed and modeled to reduce the back radiation from the slots. To verify the suggested modeling, antennas operating at 3 GHz and 5 GHz are designed and fabricated. The computed resonance frequencies from the suggested modeling show excellent agreement with the simulated and measured results (with an error of less than 1% for the ACS‐ACMPA and 1.34% for the AHSCS‐ACMPA). To confirm the reduction of the back radiation, we simulated and measured the radiation patterns of the antennas. By using H‐shaped slots, we obtained a front‐back ratio enhancement of 2.6 dB at 3 GHz and 1.9 dB at 5 GHz. Because of their accuracy and simplicity, the proposed modelings are useful for the analysis and design of an ACS‐ACMPA and an AHSCS‐ACMPA for dual‐band operation. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:679–686, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25761
Design of a decoupled MIMO antenna for LTE applications
Authors: Park Byeong‐Yong , Choi Jung‐Hwan , Park Seong‐Ook , Yang Tae‐Sik , Byun Joon‐Ho
Published: January 2011

A compact multiple‐input‐multiple‐output antenna array at 700 MHz has been proposed for long‐term evolution‐standardized handsets. A simple shunt element‐based decoupling technique has been used to realize high isolation between the strongly coupled antenna elements. The antennas with and without decoupling have been evaluated for envelope correlation coefficient, radiation efficiency, and channel capacity characteristics. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:582–586, 2011; View this article at wileyonlinelibrary.com. DOI 10.1002/mop.25766
Integrated heaters for the thermal tuning of Bragg grating filters on silicon‐on‐insulator rib waveguides
Authors: Raum Christopher R. , Gauthier Robert , Tait R. Niall
Published: January 2011

The thermal tuning of a Bragg grating filter on silicon‐on‐insulator rib waveguides has been demonstrated with integrated resistive heaters.The thermal sensitivity is 82 pm/×°C with an efficiency of 4.5 nm/W. A technique for indirectly measuring the temperature of the integrated heaters is also demonstrated. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:672–676, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25768
Compact circularly polarized microstrip array antenna
Authors: Hassan Ahmed , Elhefnawi Fatma , Elsherbeni Atef Z. , Hendi Moataza , Elramly Salwa
Published: January 2011

This article first presents a compact circularly polarized single patch antenna. The radiating structure consists of a square patch with embedding four bent slots to reduce the overall dimensions. Circular polarization is obtained by feeding the patch with 90° phase shift between two pins placed symmetrically on the two main axes. Wilkinson power divider is used to produce the λ/4 phase difference between the two feeding points and placed on the opposite side of the patch's ground plane. Then, a compact circularly polarized microstrip array antenna with four square patches is presented. The four patches are fed in phase quadrature such that a phase shift of 90° exists between each neighboring patches, thus providing circularly polarized pattern. The array feeding network is placed on the opposite side of the patches' ground plane and is designed using three Wilkinson power dividers having different output lengths that achieve the required phase shift between patches. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:604–609, 2011; View this article at wileyonlinelibrary.com. DOI 10.1002/mop.25772
A microstrip‐line‐fed isosceles‐trapezoidal dielectric resonator antenna with slotted ground plane for 2.4 GHz WLAN operation
Authors: Gopakumar C. , Mathew K. T.
Published: January 2011

A novel microstrip‐line‐fed isosceles trapezoidal dielectric resonator antenna (ITDRA) with a slotted ground plane is introduced. It is proved by simulation and experiment that the antenna's resonant frequency can be lowered, and the bandwidth can be increased considerably by introducing slots and optimizing their position and dimensions in the ground plane. The proposed antenna is a wideband antenna with a 2:1 VSWR bandwidth of 21.3% centered at 2.43 GHz and exhibits good radiation characteristics and moderate gain in the entire operating band. The antenna covers important application bands viz. ISM: Bluetooth/WLAN 2.4/Wibree (802.11 b/g/n)/ZigBee, WiBro, and DMB. Lowering of the antenna's fundamental resonant frequency can be easily tuned by varying the length of either the slots or strip line. Reduced antenna size (≈28% less) at a fixed frequency can thus be achieved for the proposed design. Details of the design along with experimental and simulation results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:553–557, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25773
High‐impedance surface‐based square loop antenna with RF‐absorber
Authors: Deo Prafulla , Mehta Amit , Mirshekar‐Syahkal Dariush , Massey Peter J. , Nakano Hisamatsu
Published: January 2011

A beam steerable square loop antenna is presented over a high impedance surface with RF‐absorber. For a test frequency of 5.0 GHz, the proposed antenna is 4.69‐mm thick and has an impedance bandwidth of 700 MHz and a gain of 7.93 dB. When compared with a recent published steerable square loop antenna over hybrid high impedance surface, the new antenna offers near equivalent performance but with a much simpler design and a cheaper fabrication process. The absorber's permittivity is found to control the antenna's beam tilt and sidelobe level. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:481–485, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25777
Design of aircraft on‐glass antennas for FM radio communications
Authors: Byun Gangil , Kang Woojoon , Kim Younggi , Choo Hosung
Published: January 2011

This letter proposes an on‐glass antenna for FM radio communications on the aircraft. We apply a multiloop structure to obtain a high‐radiation gain with broad matching characteristics. The proposed antenna is designed to imitate the shape of the window frame to minimize disruption to the pilot's visual field. The measurement shows an average bore‐sight gain of −13.4 dBi and a half‐power matching bandwidth of 52% in the FM radio band. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:588–590, 2011; View this article at wileyonlinelibrary.com. DOI 10.1002/mop.25779
Dual‐mode dual‐passband microstrip bandpass filter with a high selective performance
Authors: Wang Yunxiu
Published: January 2011

A dual‐mode bandpass filter with a high selective performance for dual‐band application is presented in this article.The filter is designed with square loop resonator with tree‐shaped patches attached to the four inner corners of the loop, which equivalents to load capacitors in the inner of loop resonator. This loading can reduce the size of filter. The input/output feed lines located along a straight line. Such a feed arrangement is physically suitable for certain microwave networks. A demonstrated filter with the dual‐band operating at 1.6 and 2.08 GHz was designed. Simulated and measured results indicate that a high selective dual‐mode dual‐band filter with wide harmonic responses has been achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:666–669, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25784
System model for characterizing and reducing the mutual coupling in multiple‐input multiple‐output antennas
Authors: Duroc Yvan , Najam Ali Imran , Siragusa Romain
Published: January 2011

A new approach for modeling the mutual coupling in multiple‐input multiple‐output antennas is introduced.The effects of the mutual coupling are described by a linear time invariant model. The introduced technique offers several advantages: first, an analytical model is achieved, and, from this description, a method for reducing the mutual coupling is proposed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:597–601, 2011; View this article at wileyonlinelibrary.com. DOI 10.1002/mop.25787
Planar compact inverted U‐shaped patch antenna with high‐gain operation for Wi‐Fi access point
Authors: Lu Jui‐Han , Hong Ruei‐Yun
Published: January 2011

A planar compact inverted U‐shaped patch antenna with high‐gain operation for Wi‐Fi system has been proposed and investigated.It provides relatively wider impedance bandwidth of 162 MHz covering the 2.45 GHz band (2400–2484 MHz). The proposed planar compact patch antenna also provides the directional radiation patterns with maximum peak antenna gain and efficiency of 7.5 dBi and 87% across the operating band, respectively. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:567–569, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25788
Twin‐core fiber fabrication for exciting and detecting signals easily
Authors: Fan Linyong , Jiang Weiwei , Zhao Ruifeng , Pei Li , Jian Shuisheng
Published: January 2011

A twin‐core fiber (TCF) with noncircular cross section has been fabricated.The two cores of the TCF can be easily identified. It has been demonstrated that signals can be easily excited and detected in this TCF, by splicing a single‐mode fiber to either of the TCF cores. The splice loss below 1 dB has been repeatedly obtained. Mutual splicing of these TCFs with low splice loss, by using a commercial fusion splicer, has also been demonstrated. The splice loss below 1.5 dB has been repeatedly obtained. Optical devices based on this TCF may be easily inserted into a standard SMF. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:499–502, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25792
Near‐field slit probe incorporating a micromachined silicon chip for millimeter‐wave microscopy
Authors: Nozokido Tatsuo , Miyasaka Noriyuki , Bae Jongsuck
Published: January 2011

A novel type of slit probe incorporating a micromachined silicon (Si) chip for millimeter‐wave scanning near‐field microscopy is proposed.To improve the spatial resolution and image contrast attainable in millimeter‐wave microscopy, a metal‐coated Si chip with a microslit aperture fabricated using a bulk micromachining technique was attached to the tip of an ordinary slit‐type probe at the end of a tapered rectangular waveguide. The design and fabrication of the Si chip are described, and the results from experiments performed at U‐band (40–60 GHz) frequencies to demonstrate the feasibility of this new probe configuration are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:660–664, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25793
Waveguide endwall coupler‐fed microstrip patch array antenna
Authors: Choi Se‐Hwan , Lee Jae‐Young
Published: January 2011

In this letter, we present the 2 by 1 and 2 by 2 array microstrip patch antennas using the waveguide endwall coupler at 24 GHz. These antennas consist of a waveguide feed and two or four patches that are excited by the endwall coupler. As the measured results, the 2 by 2 array antenna has the gain of 10.7 dBi and the bandwidth of 1.3 GHz, and half power beamwidth is 31° on the E‐plane and 35° on the H‐plane. Because this transition technique is very simple and easy to fabricate, it can be used for low cost and high volume production for commercial millimeter‐wave applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:630–633, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25794
A compact hexagonal dual‐band substrate integrated waveguide filter based on extracted‐pole technique
Authors: Chen Jia , Wu Bian , Jiang Li‐wei , Liang Chang‐hong
Published: January 2011

In this article, a novel hexagon substrate integrated waveguide (SIW) dual‐band filter is presented.First, the formula for calculating the resonant frequency of the dominant mode in triangle SIW cavity is given, then the triangle SIW cavity is used to construct a novel hexagon filter, which reduces the size effectively. According to the extracted‐pole technique using a parallel resonant circuit at the input and output resonator, a dual‐band filter with two passbands at 9.6–9.85 and 10.15–10.4 GHz has been designed and fabricated. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:562–565, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25799
Orthogonal rectangular ring‐shaped monopole antenna with double step
Authors: Kim Byeong Hoon , Choi Hak Keun , Park Jae Hyun
Published: January 2011

In this article, a novel wideband crossed planar monopole antenna formed by two orthogonal rectangular rings with double step is studied. The antenna design parameters that achieve wideband property are experimentally investigated. Parametric studies have been performed to optimize the impedance bandwidth of the proposed antenna. From the obtained results, the proposed antenna provides a wide bandwidth with isotropic pattern in the H‐plane and directional pattern in the E‐plane. The measured −14 dB impedance bandwidth for return loss is 0.82–2.7 GHz, which can cover various kinds of wireless services such as Cellular (0.824–0.894 GHz), PCS (1.75–1.87 GHz), WCDMA (1.885–2.17 GHz), WiBro (2.3–2.39 GHz), and S‐DMB (2.605–2.655 GHz). © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:572–575, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25801
A miniature multibranch inverted‐F antenna to be embedded in the laptop computer for WWAN applications
Authors: Hu Chuan‐Ling , Liu Hsien‐Wen , Yang Chang‐Fa , Lin Shun‐Tian
Published: January 2011

A novel miniature multibranch inverted‐F antenna (IFA) suitable for penta‐band Wireless Wide Area Network (WWAN) applications is presented. The antenna is fabricated on a direct bond copper substrate and consists of multibranch strips, which occupies a very small size of 83(L)× 7(W) × 0.5(H) mm3 to be easily embedded inside the laptop computer as an internal antenna. By properly designing the antenna operated as an inverted‐F antenna, two frequency bands covering 813–993 and 1703–2196 MHz for the GSM850/900 and DCS/PCS/UMTS operations are achieved with good radiation efficiencies. Compared with other studies, the proposed antenna with a compact size is suitable to be installed in the laptop computer for the WWAN applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:547–550, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25802
Cross‐phase modulation impact on coherent optical 16 QAM–WDM transmission systems
Authors: Reis Jacklyn D. , Teixeira António L.
Published: January 2011

This article investigates the impact of fiber nonlinear crosstalk on ultradense 32 × 16 QAM–WDM with coherent detection using Volterra series.The method is validated using Error Vector Magnitude measures against Split‐Step Fourier simulations. The cross‐phase modulation crosstalk contribution is derived and compared to four‐wave mixing and the overall system performance. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:633–636, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25805
Wideband thick‐arm spiral antenna for ingestible capsules
Authors: Lee Sang Heun , Lee Jaebok , Yoon Young Joong
Published: January 2011

In this article, a new antenna is introduced for ingestible capsule endoscope systems. As capsule endoscope systems are supposed to operate in the human body and they transmit internal image data with high resolution to external receivers, a wideband small antenna is required. To obtain these properties, the proposed antenna is designed in the form of thick‐arm spiral structure. The total height of the antenna is 5 mm and the diameter is 10 mm. The fractional bandwidth of the proposed antenna is 21% with VSWR < 2, which is wide enough for WBAN in body communication and it has the isotropic radiation pattern. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:529–532, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25808
Model‐based phase retrieval in two‐port microwave network measurements
Authors: Fang W. , McNamara D. A.
Published: January 2011

A method is proposed for the retrieval of phase‐related quantities from magnitude‐only measurements on microwave networks that are to be manufactured and tested in large quantities. A reduced‐order model is developed using the prototype of such a system and then used to retrieve the phase of nonprototype devices under test. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:495–499, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25809
Evaluations and measurements of indoor wireless systems with optical orthogonal frequency division multiplexing lines
Authors: Kim Ajung , Nahm S.
Published: January 2011

An indoor wireless millimeter wave system with an optical orthogonal frequency division multiplexing (OFDM) signal link was developed. Channel modeling for the multipath system was proposed, and the channels in a 60 GHz band were measured. Based on the model, system parameters were evaluated for various subcarrier modulations in OFDM systems. Link performance in a typical office environment under the line‐of‐sight channel condition and with a 30 km optical OFDM link was measured. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:491–495, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25810
Integrated, dual‐band three‐dipole‐antenna system for single‐radio, access‐point applications
Authors: Hong Tzi‐Chieh , Su Saou‐Wen
Published: January 2011

A printed, dual‐band three‐dipole‐antenna system suited to installation inside a wireless access point (AP) and integrated with the system circuit board as an efficient reflector for dipoles is presented.The multi‐antenna design comprises three dual‐wireless local area network (WLAN)‐band dipole antennas printed on the same layer of a FR4 substrate, and each antenna occupies a moderate area of 13.5 mm × 36.5 mm. The dipoles are set in a sequential, rotating arrangement on the antenna substrate with an equal inclination angle of 120° to form a symmetrical multi‐antenna structure. The three antennas are stacked above the system circuit board of the AP by a small distance. The design, in this case, integrates the system circuit board into an internal multi‐antenna solution. The results show that good port isolation can be obtained with high‐gain, directional radiation characteristics over the 2.4 and 5 GHz bands. Details of a design prototype are described and discussed in the article. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:688–692, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25811
A novel compact dual‐mode bandpass filter
Authors: Keshvari M. , Tayarani M.
Published: January 2011

Using slow‐wave transmission line ring resonator and square‐patch element, a novel compact dual‐mode microstrip bandpass filter is developed in this article. A filter having a 3% bandwidth at 2 GHz is designed, fabricated, and measured. The design procedure is given, and the mode‐splitting characteristic and impact of the patch element on the performance of the filter is investigated. The proposed filter has a smaller size compared with conventional dual‐mode bandpass filters at the same central frequency. This compactness is about 35% for the fabricated sample. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:656–659, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25812
Dynamic gain equalization for erbium doped fiber amplifiers based on optoceramic sinusoidal filter cascade
Authors: Nascimento Vitor V. , de Oliveira Júlio C. R. F. , Ribeiro Vitor B. , Bordonalli Aldário C.
Published: January 2011

This article presents an experimental demonstration and a systemic analysis of a dynamic gain equalizer for erbium doped fiber amplifier based on a cascade of sinusoidal optoceramic filters controlled by voltage with temperature control. A power imbalance reduction up to 86% is experimentally demonstrated and, based on simulations, optimal device allocation is analyzed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:623–626, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25813
Computationally efficient design optimization of wideband planar antennas using Cauchy approximation and space mapping
Authors: Koziel Slawomir , Ogurtsov Stanislav , Bakr Mohamed H.
Published: January 2011

Computationally efficient simulation‐driven design of ultra‐wideband planar antennas is presented using Cauchy‐based surrogate models of the coarsely‐discretized antenna electromagnetic models.Verification of the proposed methodology is performed with satisfactory designs obtained at a computational cost of a few evaluations of high‐fidelity antenna models. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:618–622, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25814
Improved diagnostic accuracy of breast MRI through combined apparent diffusion coefficients and dynamic contrast‐enhanced kinetics
Authors: Partridge S. C. , Rahbar H. , Murthy R. , Chai X. , Kurland B. F. , DeMartini W. B. , Lehman C. D.
Published: January 2011

This study investigated the relationship between apparent diffusion coefficient (ADC) measures and dynamic contrast‐enhanced magnetic resonance imaging (MRI) kinetics in breast lesions and evaluated the relative diagnostic value of each quantitative parameter. Seventy‐seven women with 100 breast lesions (27 malignant and 73 benign) underwent both dynamic contrast‐enhanced MRI and diffusion weighted MRI. Dynamic contrast‐enhanced MRI kinetic parameters included peak initial enhancement, predominant delayed kinetic curve type (persistent, plateau, or washout), and worst delayed kinetic curve type (washout > plateau > persistent). Associations between ADC and dynamic contrast‐enhanced MRI kinetic parameters and predictions of malignancy were evaluated. Results showed that ADC was significantly associated with predominant curve type (ADC was higher for lesions exhibiting predominantly persistent enhancement compared with those exhibiting predominantly washout or plateau, P = 0.006), but was not significantly associated with peak initial enhancement or worst curve type (P > 0.05). Univariate analysis showed significant differences between benign and malignant lesions in both ADC (P < 0.001) and worst curve (P = 0.003). In multivariate analysis, worst curve type and ADC were significant independent predictors of benign versus malignant outcome and in combination produced the highest area under the receiver operating characteristic curve (0.85 and 0.78 with 5‐fold cross validation). Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
3D GRASE PROPELLER: Improved image acquisition technique for arterial spin labeling perfusion imaging
Authors: Tan Huan , Hoge W. Scott , Hamilton Craig A. , Günther Matthias , Kraft Robert A.
Published: January 2011

Arterial spin labeling is a noninvasive technique that can quantitatively measure cerebral blood flow. While traditionally arterial spin labeling employs 2D echo planar imaging or spiral acquisition trajectories, single‐shot 3D gradient echo and spin echo (GRASE) is gaining popularity in arterial spin labeling due to inherent signal‐to‐noise ratio advantage and spatial coverage. However, a major limitation of 3D GRASE is through‐plane blurring caused by T2 decay. A novel technique combining 3D GRASE and a periodically rotated overlapping parallel lines with enhanced reconstruction trajectory (PROPELLER) is presented to minimize through‐plane blurring without sacrificing perfusion sensitivity or increasing total scan time. Full brain perfusion images were acquired at a 3 × 3 × 5 mm3 nominal voxel size with pulsed arterial spin labeling preparation sequence. Data from five healthy subjects was acquired on a GE 1.5T scanner in less than 4 minutes per subject. While showing good agreement in cerebral blood flow quantification with 3D gradient echo and spin echo, 3D GRASE PROPELLER demonstrated reduced through‐plane blurring, improved anatomical details, high repeatability and robustness against motion, making it suitable for routine clinical use. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
In vivo detection of MRI‐PARACEST agents in mouse brain tumors at 9.4 T
Authors: Li Alex X. , Suchy Mojmir , Li Chunhui , Gati Joseph S. , Meakin Susan , Hudson Robert H. E. , Menon Ravi S. , Bartha Robert
Published: January 2011

Paramagnetic chemical exchange saturation transfer (PARACEST) contrast agents are under development for biological target identification by magnetic resonance imaging. Image contrast associated with PARACEST agents can be generated by radiofrequency irradiation of the chemically shifted protons bound to a PARACEST contrast agent molecule or by direct irradiation of the on‐resonance bulk water protons. The observed signal change in a magnetic resonance image after the administration of a PARACEST contrast agent is due to both altered relaxation time constants and the CEST effect. Despite high sensitivity in vitro, PARACEST agents have had limited success in vivo where sensitivity is reduced by the magnetization transfer effect from endogenous macromolecules. The purpose of this study was to demonstrate the in vivo detection of a PARACEST contrast agent using the on‐resonance paramagnetic chemical exchange effect (OPARACHEE) in a mouse glioblastoma multiforme tumor model and to isolate the OPARACHEE effect from the changes in relaxation induced by the PARACEST agent. Three mice with tumors were imaged on a 9.4 T MRI scanner following tail vein injection of 150 μL 50 mM Tm3+‐DOTAM‐glycine‐lysine. A fast low angle shot pulse sequence with a low power radiofrequency pulse train (WALTZ‐16) as the preparation pulse was used to generate OPARACHEE contrast. To study the dynamics of agent uptake, reference images (without the preparation pulse) and OPARACHEE images were acquired continuously in an alternating fashion before, during and after agent injection. Signal intensity decreased by more than 10% in tumor in the control images after agent administration. Despite these changes, a clear OPARACHEE contrast of 1–5% was also observed in brain tumors after contrast agent injection and maintained in the hour following injection. This result is the first in vivo observation of OPARACHEE contrast in brain tumors with correction of T1 and T2 relaxation effects. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
Quantitative analysis of intravenously administered contrast media reveals changes in vascular barrier functions in a murine colitis model
Authors: Aychek Tegest , Vandoorne Katrien , Brenner Ori , Jung Steffen , Neeman Michal
Published: January 2011

Inflammatory bowel disease is a chronic inflammatory disorder of the gastrointestinal tract associated with alterations and dysfunction of the intestinal microvasculature. The goal of this work was to develop a preclinical protocol for quantitative functional characterization of the colonic microvasculature in a murine colitis model. Experimental colitis was induced in mice by addition of dextran sodium sulfate to the drinking water. Histopathologic analysis revealed severe multifocal colitis. Dynamics of intravenously injected macromolecular dextran‐FITC and biotin‐BSA‐GdDTPA in the colonic microvasculature were imaged using fluorescent confocal endomicroscopy and MRI (9.4 T), respectively. Both MRI and fluorescent confocal endomicroscopy revealed a substantial increase in the permeability of the colonic microvasculature associated with colitis, resulting in extravascular accumulation of the macromolecular contrast agent in the lumen of the colon. MRI data were validated by immunohistochemical staining of the contrast agent and leakage of fluorescently labeled BSA‐FAM coinjected with the MRI contrast agent. Leakage of plasma proteins and deposition of a provisional matrix can support inflammation and stimulate remodeling of the colonic vasculature. Thus, the plasma protein leakage from the colonic microvasculature at the focal inflammatory patches could be quantified by MRI, providing a biomarker for assessment of disease progression. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.
The somatosensory blink reflex in upper and lower brainstem lesions
Authors: León Lucía , Casanova‐Molla Jordi , Lauria Giuseppe , Valls‐Solé Josep
Published: January 2011

The brainstem pathways that mediate the somatosensory blink reflex (SBR) are not completely understood. We hypothesized that the circuits of the SBR might be affected separately from those of the trigeminal blink reflex (TBR). We examined 7 patients with mesencephalic lesions and 8 patients with medullary lesions. The SBR was elicited by median nerve stimulation. The TBR was elicited by supraorbital nerve stimulation. In patients with upper brainstem lesions, the TBR was normal, whereas the SBR was generally abnormal. The SBR was either absent or small and was significantly delayed with respect to control subjects. The opposite was the rule in patients with lower brainstem lesions who had delayed or absent TBR and no abnormal findings in the SBR. The SBR is mediated through circuits in the upper brainstem. Study of the SBR can be helpful in the neurophysiological assessment of patients with mesencephalic lesions. Muscle Nerve 43: 196–202, 2011
Effects of resistance training on force steadiness and common drive
Authors: Beck Travis W. , DeFreitas Jason M. , Stock Matt S. , Dillon Michael A.
Published: January 2011

The purpose of this study was to investigate the influence of an 8‐week resistance training program on force steadiness and common drive for the vastus lateralis muscle. Eight untrained men performed a resistance training program. Before the program and at the end of each week, the subjects performed a trapezoid isometric muscle action of the leg extensors, and bipolar surface electromyographic signals were recorded from the vastus lateralis. The signals were decomposed into action potential trains that were cross‐correlated to measure common drive. Force steadiness was quantified as the standard deviation of force during the constant‐force portion of the trapezoid muscle action. The training program did not consistently affect force steadiness or common drive for any of the subjects. Although future studies are needed with different muscles and training programs, changes in the overall motor control scheme are not likely with resistance training. Muscle Nerve 43: 245–250, 2011
An early diagnostic tool for diabetic neuropathy: Conduction velocity distribution
Authors: Tuncer Seckin , Dalkilic Nizamettin , Esen Haci Hasan , Avunduk Mustafa Cihat
Published: January 2011

Diabetes is a metabolic disorder that affects much of the human population. As a secondary complication, diabetic neuropathy causes time‐dependent damage to peripheral nerves. In this study, experimental diabetes was induced by streptozotocin (STZ; 50 mg/kg intraperitoneally) in rats. Diabetic animals were grouped into those with 2 or 4 weeks of diabetes, whereas a control group received only the STZ vehicle (0.1 M citrate). Sciatic nerves were dissected, and compound action potentials (CAPs) were recorded. Results deduced by conventional calculation carried less information when compared with conduction velocity distribution (CVD) obtained by a computer‐based mathematical model. Using the conventional approach, statistically significant changes were first seen in the fourth week of diabetes, whereas results deduced by CVD measurement could be seen in the second week. Consequently, the CVD calculation provides more information for the early diagnosis of neuropathies compared with classical conduction velocity measurements. Muscle Nerve 43: 237–244, 2011
Repeated courses of granulocyte colony‐stimulating factor in amyotrophic lateral sclerosis: Clinical and biological results from a prospective multicenter study
Authors: Chiò Adriano , Mora Gabriele , Bella Vincenzo La , Caponnetto Claudia , Mancardi Gianluigi , Sabatelli Mario , Siciliano Gabriele , Silani Vincenzo , Corbo Massimo , Moglia Cristina , Calvo Andrea , Mutani Roberto , Rutella Sergio , Gualandi Francesca , Melazzini Mario , Scimè Rosanna , Petrini Mario , Bondesan Paola , Garbelli Silvia , Mantovani Stefania , Bendotti Caterina , Tarella Corrado ,   and the STEMALS Study Group
Published: January 2011

Granulocyte colony‐stimulating factor (G‐CSF) induces a transient mobilization of hematopoietic progenitor cells from bone marrow to peripheral blood. Our aim was to evaluate safety of repeated courses of G‐CSF in patients with amyotrophic lateral sclerosis (ALS), assessing disease progression and changes in chemokine and cytokine levels in serum and cerebrospinal fluid (CSF). Twenty‐four ALS patients entered an open‐label, multicenter trial in which four courses of G‐CSF and mannitol were administered at 3‐month intervals. Levels of G‐CSF were increased after treatment in the serum and CSF. Few and transitory adverse events were observed. No significant reduction of the mean monthly decrease in ALSFRS‐R score and forced vital capacity was observed. A significant reduction in CSF levels of monocyte chemoattractant protein‐1 (MCP‐1) and interleukin‐17 (IL‐17) was observed. G‐CSF treatment was safe and feasible in a multicenter series of ALS patients. A decrease in the CSF levels of proinflammatory cytokines MCP‐1 and IL‐17 was found, indicating a G‐CSF–induced central anti‐inflammatory response. Muscle Nerve 43: 189–195, 2011
Effects of formoterol on protein metabolism in myotubes during hyperthermia
Authors: Ametller Elisabet , Busquets Sílvia , Fuster Gemma , Figueras Maria T. , Oliveira Cibely Cristine Fontes De , Toledo Míriam , Korzeniewska Katarzyna , Argilés Josep M. , López‐Soriano Francisco J.
Published: January 2011

Proteolysis in skeletal muscle is mainly carried out by the activity of the ubiquitin‐dependent proteolytic system. For the study of protein degradation through the ubiquitin–proteasome pathway, we used a model of hyperthermia in murine myotubes. In C2C12 cells, hyperthermia (41°C) induced a significant increase in both the rate of protein synthesis (18%) and degradation (51%). Interestingly, the addition of the β2‐adrenoceptor agonist formoterol resulted in a significant decrease in protein degradation (21%) without affecting protein synthesis. The decrease in proteolytic rate was associated with decreases in gene expression of the different components of the ubiquitin‐dependent proteolytic system. The effects of the β2‐agonist on protein degradation were dependent exclusively on cAMP formation, because inhibition of adenylyl cyclase completely abolished the effects of formoterol on protein degradation. It can be concluded that hyperthermia is a suitable model for studying the anti‐proteolytic potential of drugs used in the treatment of muscle wasting. Muscle Nerve 43: 268–273, 2011
Pediatric sciatic neuropathy associated with neoplasms
Authors: Mcmillan Hugh J. , Srinivasan Jayashri , Darras Basil T. , Ryan Monique M. , Davis James , Lidov Hart G. , Gill Deepak , Jones H. Royden
Published: January 2011

Seven children with sciatic neuropathy associated with an underlying neoplasm are reported. Clinical presentation, electrophysiological data, imaging, pathology, and/or autopsy results are described. Pain and weakness, primarily foot drop, were the most common presenting symptoms. The mechanism of sciatic neuropathy was varied and included: nerve infiltration by the adjacent neoplasm (neuroblastoma, rhabdomyosarcoma, and leukemic or lymphomatous infiltration); an expanding, intrinsic neurogenic tumor (perineurioma); or intraoperative stretch injury (osteosarcoma resection). The prognosis for sciatic nerve recovery was good among children who survived their associated cancer. Three children died from the cancer or complications of treatment. One child with perineurioma remained clinically stable, and two children improved after treatment of their neoplasm. Muscle Nerve 43: 183–188, 2011
Immune trigeminal sensory neuropathy with esophageal achalasia: Improvement with long‐term immunotherapy
Authors: Figueroa Juan J. , Engelstad Janean K. , Spinner Robert J. , Dyck P. James B.
Published: January 2011

We report a patient who developed subacute facial‐predominant numbness and anhidrosis, oral incoordination, and esophageal achalasia with resultant cachexia. Great auricular nerve biopsy showed extensive epineurial perivascular inflammatory infiltrates. Sensation, sweating, and swallowing improved with pulse intravenous methylprednisolone given over 5 years. We suggest that the patient's deficits, including achalasia, were due to an immune‐mediated sensory and autonomic neuropathy and that, in such cases, pathologic studies of the great auricular nerve may be diagnostically informative. Muscle Nerve 43: 289–293, 2011
The biochemistry of living tissues: Examination by MRS
Authors: Ross Brian D.
Published: January 2011

MRS defines the molecular state of water, the chemical environment of cells and tissues and the qualitative and quantitative state of intermediary metabolism. Because cancer has disordered physiology, obvious differences in MR spectra can be observed. However, the detailed understanding of the biochemistry of cancer will also emerge from careful, quantitative multinuclear MR. The intermediary metabolism of ATP, the Krebs cycle, creatine, cholines and lipids, is discussed. Finally, the biochemical challenge posed by oncogenes may be amenable to MR analyses.
Practical applications of chemical shift imaging
Authors: Brown Truman R.
Published: January 2011

Methods of spectral localization are briefly reviewed and divided into two classes: those using phase encoding and those using frequency selective RF pulses in a constant gradient. A potentially troubling artifact in the latter case is the spatial misregistration of different compounds which causes serious errors in 31P spectra from smaller regions. Chemical shift imaging (CSI) is presented as a typical example of phase encoding techniques. An analytical expression for the relationship of the signal observed to the true signal (the point spread function) is derived. Examples of CSI in one, two, and three dimensions are used to illustrate the principles of this type of localization.
The contribution made by cell death and oxygenation to 31P MRS observations of tumour energy metabolism
Authors: Tozer G. M. , Griffiths J. R.
Published: January 2011

This review discusses the relationship between tumour oxygenation status, tumour cell death and the 31P MRS parameters associated with cellular energy metabolism (phosphocreatine, nucleoside triphosphates and P1). The presence of cells dying by apoptosis, and during mitosis would be unlikely to affect the 31P spectrum directly since they represent only a small fraction of tumour cells and remain energized until phagocytosed. Histologically necrotic cells also probably contribute nothing to the 31P spectrum. Instead, the spectrum appears to reflect the degree of hypoxia of the remaining viable cells, and the metabolic alterations required to sustain ATP synthesis as the oxygen supply diminishes. The biochemical theory developed to account for the 31P spectra of acutely hypoxic tissues does not apply to chronically hypoxic tumours. The concentrations of free ADP and P1 have major roles in the control of oxidative phosphorylation and glycolysis, as in normal tissues, but the precise relationships are still obscure. Cell‐killing following therapy may indirectly affect 31P MRS parameters via changes in oxygen concentration brought about by an improvement in tumour blood flow and alterations in oxygen consumption rates and diffusion distances.
Measurement of tumor blood flow by deuterium NMR and the effects of modifiers
Authors: Evelhoch Jeffrey L.
Published: January 2011

Tumor metabolism is directly coupled to tumor blood flow (TBF) and both metabolism and blood flow may be determinants of tumor response to treatment. Since NMR has been used extensively to monitor tumor metabolism noninvasively, development of NMR‐based methods for TBF measurement was motivated by the desire to examine the roles tumor metabolism and blood flow may play as determinants of therapeutic response. The concept of using deuterated water as an NMR‐detectable, flow‐limited tracer for the measurement of tissue blood flow (or capillary perfusion) was introduced in 1987 by Ackerman and coworkers (Proc. Natl., Acad. Sci., USA84, 4099–4102 (1987)). Since that time, methods have been devised using both spectroscopic and imaging detection for TBF measurement based on either clearance or uptake of deuterated water. In general, the clearance methods are more straightforward to implement, while the uptake methods are less invasive to the tumor. When used with appropriate caution, both approaches yield reliable results. To date, these methods have been applied in a relatively limited number of animal tumors. However, their use is increasing and some of these methods ultimately should be applicable in human tumors.
Clinical experimentation in magnetic resonance spectroscopy: A perspective from the national cancer institute
Authors: Shtern Faina
Published: January 2011

This paper describes the National Cancer Institute activities in clinical MRS, including a recent international conference organized by the Diagnostic Imaging Research Branch, a research agenda developed by the conference faculty members and one of the research programs proposed by the author.
Anthropological analysis of the phenomenon of atlas occipitalisation exemplified by a skull from twardogóra (17th c.)—southern Poland
Authors: Senator M. , Gronkiewicz S.
Published: January 2011

Occipitalisation of the atlas is one of the most frequent osseous anomalies of the atlas. It is characterised by the adhesion of the first cervical vertebra with the basilar part of the occipital bone. The most probable cause of the occipitalisation is a congenital disorder. The atlanto‐occipital fusion may lead to narrowing of the space for medulla oblongata, spinal cord and vertebral artery. This in turn may lead to many physiological symptoms. The skull from Twardogóra, Southern Poland, showed partial atlanto‐occipital fusion and presented an asymmetry in structure and shape of apertures for the vessels and nerves around the foramen magnum. Copyright © 2011 John Wiley & Sons, Ltd.
New trends of public affairs management at the EU level
Authors: van Schendelen Rinus
Published: January 2011

Public affairs management at the level of the European Union (EU) undergoes rapid changes, due to a combination of: (1) recent transformations of the EU playing‐field; (2) new ways and forms of playing by interest groups that want to influence the EU; and (3) a more professional preparation for this playing. Before we shall focus on the rising new trends, their main causes and major effects on PAM, we present to the non‐specialist first the general basics of EU decision‐making. Copyright © 2011 John Wiley & Sons, Ltd.
Impact of caring for a child with cancer on single parents compared with parents from two‐parent families
Authors: Klassen Anne F. , Dix David , Papsdorf Michael , Klaassen Robert J. , Yanofsky Rochelle , Sung Lillian
Published: January 2011

Background

It is currently unknown how the intensive and often prolonged treatment of childhood cancer impacts on the lives of single parents. Our aims were to determine whether single parents differ from parents from two‐parent families in terms of caregiver demand (the time and effort involved in caregiving), and health‐related quality of life (HRQL).

Procedures

Forty single parents and 275 parents from two‐parent families were recruited between November 2004 and February 2007 from five pediatric oncology centers in Canada. Parents were asked to complete a questionnaire booklet composed of items and scales to measure caregiver demand and HRQL (SF‐36). The booklet also measured the following constructs: background and context factors, child factors, caregiving strain, intrapsychic factors, and coping factors.

Results

Single parents did not differ from parents from two‐parent families in caregiving demand and physical and psychosocial HRQL. Compared with Canadian population norms for the SF‐36, both groups reported clinically important differences (i.e., worse health) in psychosocial HRQL (effect size ≥ −2.00), while scores for physical HRQL were within one standard deviation of population norms.

Conclusion

Our findings suggest that the impact of caregiving on single parents, in terms of caregiving demand and HRQL is similar to that of parents from two‐parent families. Pediatr Blood Cancer 2012; 58: 74–79. © 2011 Wiley Periodicals, Inc.