bluuebunny/crossref_metadata_2025 huggingface dataset:
Lattice microbes: High‐performance stochastic simulation method for the reaction‐diffusion master equation
Authors: Roberts Elijah , Stone John E. , Luthey‐Schulten Zaida
Published: September 2012

Spatial stochastic simulation is a valuable technique for studying reactions in biological systems. With the availability of high‐performance computing (HPC), the method is poised to allow integration of data from structural, single‐molecule and biochemical studies into coherent computational models of cells. Here, we introduce the Lattice Microbes software package for simulating such cell models on HPC systems. The software performs either well‐stirred or spatially resolved stochastic simulations with approximated cytoplasmic crowding in a fast and efficient manner. Our new algorithm efficiently samples the reaction‐diffusion master equation using NVIDIA graphics processing units and is shown to be two orders of magnitude faster than exact sampling for large systems while maintaining an accuracy of ∼0.1%. Display of cell models and animation of reaction trajectories involving millions of molecules is facilitated using a plug‐in to the popular VMD visualization platform. The Lattice Microbes software is open source and available for download at http://www.scs.illinois.edu/schulten/lm © 2012 Wiley Periodicals, Inc.
Holocene and Lateglacial relative sea‐level change in north‐west England: implications for glacial isostatic adjustment models
Authors: Lloyd Jeremy M. , Zong Yongqiang , Fish Paul , Innes James B.
Published: September 2012

Relative sea‐level (RSL) change is reconstructed for central Cumbria, UK, based on litho‐ and biostratigraphical analysis from the Lateglacial to the late Holocene. The RSL curve is constrained using ten new radiocarbon‐dated sea‐level index points in addition to published data. The sea‐level curve identifies a clear Lateglacial sea‐level highstand approximately 2.3 m OD at c. 15–17 k cal a BP followed by rapid RSL fall to below −5 m OD. RSL then rose rapidly during the early Holocene culminating in a mid‐Holocene highstand of approximately 1 m OD at c. 6 k cal a BP followed by gradual fall to the present level. These new data provide an important test for the RSL predictions from glacial isostatic adjustment models, particularly for the Lateglacial where there are very little data from the UK. The new RSL curve shows similar broad‐scale trends in RSL movement predicted by the models. However, the more recent models fail to predict the Lateglacial sea level highstand above present reconstructed by the new data presented here. Future updates to the models are needed to reduce this mismatch. This study highlights the importance for further RSL data to constrain Lateglacial sea level from sites in northern Britain. Copyright © 2012 John Wiley & Sons, Ltd.
Issues relating to study design and risk of bias when including non‐randomized studies in systematic reviews on the effects of interventions
Authors: Higgins Julian PT , Ramsay Craig , Reeves Barnaby C , Deeks Jonathan J , Shea Beverley , Valentine Jeffrey C , Tugwell Peter , Wells George
Published: September 2012

Non‐randomized studies may provide valuable evidence on the effects of interventions. They are the main source of evidence on the intended effects of some types of interventions and often provide the only evidence about the effects of interventions on long‐term outcomes, rare events or adverse effects. Therefore, systematic reviews on the effects of interventions may include various types of non‐randomized studies. In this second paper in a series, we address how review authors might articulate the particular non‐randomized study designs they will include and how they might evaluate, in general terms, the extent to which a particular non‐randomized study is at risk of important biases. We offer guidance for describing and classifying different non‐randomized designs based on specific features of the studies in place of using non‐informative study design labels. We also suggest criteria to consider when deciding whether to include non‐randomized studies. We conclude that a taxonomy of study designs based on study design features is needed. Review authors need new tools specifically to assess the risk of bias for some non‐randomized designs that involve a different inferential logic compared with parallel group trials. Copyright © 2012 John Wiley & Sons, Ltd.
Efficacy of the retreatment of hepatitis C virus infections after liver transplantation: Role of an aggressive approach
Authors: Berenguer Marina , Roche Bruno , Aguilera Victoria , Duclos-Vallée Jean-Charles , Navarro Laia , Rubín Angel , Pons Jose-Antonio , de la Mata Manuel , Prieto Martín , Samuel Didier
Published: September 2012

A sustained virological response (SVR) is achieved by 30% of naive liver transplantation (LT) recipients treated with pegylated interferon (PEG-IFN) and ribavirin (RBV). Almost no data are available about retreatment. The aim of this study was to assess the efficacy, tolerability, and SVR predictors of retreatment. Data were collected from 4 centers on the retreatment of prior nonresponders to standard therapy or PEG-IFN (with or without RBV) and relapsers. Seventy-nine of 301 treatment-experienced LT patients (26%), who had a median age of 59 years (range = 35-77 years) and were mostly male (72%) and infected with genotype 1 (87%), were retreated with PEG-IFN and RBV at a median of 6.9 years after LT. During the first course of therapy, 35% were treated with interferon, 49% received tacrolimus, 52% received steroids, and 49.5% were relapsers. Retreatment was started at a median of 1.9 years (range = 45 days to 8.2 years) after the end of the first course. The proportion of patients with cirrhosis increased from 10% to 37% (P < 0.001). In addition, in retreated patients, full initial RBV doses (P = 0.03), growth factors [erythropoietin (P < 0.001) and granulocyte colony-stimulating factor (P = 0.048)], and transfusions (P = 0.03) were used more frequently, and the treatment duration was longer (P = 0.03). An end-of-treatment response was achieved in 61%, whereas SVR, which was associated with improved survival, occurred in 28 (35%). The variables predicting SVR were age (P = 0.04), disease severity [fibrosis (50% with F0-F2 versus 26% with F3-4), P = 0.03; bilirubin, P = 0.006; platelet count, P = 0.03], adherence, and viral kinetics. None of the patients without an early virological response achieved SVR. There was a trend of prior relapsers achieving higher SVR rates than prior nonresponders. In conclusion, SVR, which was achieved by approximately one-third of the retreated patients, can be predicted with the same variables used for naive LT recipients (age, disease severity, adherence, and viral kinetics) and is associated with enhanced survival. Liver Transpl 19:69–77, 2013. © 2012 AASLD.
A Green Route for the Preparation of Aliphatic Polyesters via Lipase‐catalyzed Prepolymerization and Low‐temperature Postpolymerization
Authors: Vouyiouka Stamatina N. , Topakas Evangelos , Katsini Adamantia , Papaspyrides Constantine D. , Christakopoulos Paul
Published: September 2012

Lipase‐catalyzed polycondensation of two biobased diacids, 1,12‐dodecanedioic acid and 1,14‐tetradecanedioic acid, with 1,8‐octanediol was achieved using immobilized Lipase B from Candida antarctica. The procedure resulted in partially renewable prepolymers, while poly(octylene adipate) from petroleum‐based adipic acid was also synthesized for comparison reasons, revealing a dependence of the enzymatic polymerization degree on monomer composition. The prepolymers were further submitted to bulk postpolymerization at temperatures in the vicinity of their melting point under flowing nitrogen. The intrinsic viscosity increase was found up to 12%, with no significant impact on the polyesters thermal properties.

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Effect of Clay Modification on the Mechanism of Local Deformations in PA6 Nanocomposites
Authors: Dominkovics Zita , Naveau Elodie , Jérôme Christine , Hári József , Renner Károly , Móczó János , Alexandre Michaël , Pukánszky Béla
Published: September 2012

PA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties of the composites reveal that several micromechanical deformation processes occur in the PA/MMT composites. The matrix cavitates at relatively small stress. Processes related to non‐exfoliated clay structural units are initiated at larger stresses. Sound is emitted mainly by the fracture of particles, but debonding may also occur. The plastic deformation of the matrix dominates at larger stresses and deformations. The various local deformations are independent of each other and composite properties are not determined by silicate related processes but by the deformation of the matrix.

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An Investigation of the Relationship Between Molecular Topology and CYP3A4 Inhibition for Drug‐like Compounds
Authors: Oka Rurika , Engkvist Ola , Chen Hongming
Published: September 2012

Earlier studies have shown that CYP3A4 inhibition is influenced by lipophilicity, size and fMF, where fMF is the size of the molecular framework divided by the total size of the molecule. Other previous studies have shown that there is an enrichment of compounds with only one ring system among drugs in comparison to clinical candidates and general bioactive compounds as well as enrichment among natural products and human metabolites compared to general bioactive compounds. Thus a logical extension of the earlier investigations would be to study how ring systems influence CYP3A4 inhibition. It is shown here that compounds with only one ring system have lower CYP3A4 inhibition compared to compounds with several ring systems. The reason therefore is that they are both smaller and have smaller fMF values compared to compounds with several ring systems. The investigation provides additional insights into how a molecule should be constituted to have low CYP3A4 inhibition and may influence library design and compound acquisitions.
A revisit to the validity of born approximation in high frequency scattering problems
Authors: Wang Wei , Li Jianbing , Niu Fengliang
Published: September 2012

The Born approximation is a widely used technique in (inverse) scattering problems to alleviate the difficulty of solving the Lippmann–Schwinger integral equation, but its validity is not well defined, in particular for high frequency cases. Based on applying the stationary phase method and operator theory to the Lippmann–Schwinger integral equation, the high order scattered fields ignored by the Born approximation are well estimated, and then a new validity criterion for the Born approximation is proposed. Compared to conventional criteria, the new one excels in its less restriction and better prediction of the relative error for the approximate technique, especially when a nonuniform scatterer is under consideration. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2792–2797, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27161
A Tai‐Ji shaped circularly polarized antenna with wide axial ratio bandwidth
Authors: Li Biao , Yin Yingzeng , Ding Yang , Xie Jiaojiao
Published: September 2012

A new design of a circularly polarized antenna is presented.The proposed antenna consists of two nonsymmetrical arc arms printed on the opposite side of the substrate. Axial ratio (AR) bandwidth can be significantly enhanced by etching a pair of nonsymmetrical arc slots. The antenna has been fabricated and measured. Experimental results show that the antenna possesses an impedance bandwidth of about 17.9% and a 3‐dB AR bandwidth of 22% relative to the centre frequency of 5.6 GHz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2790–2792, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27162
K‐band CMOS VCO using a wide tuning range varactor
Authors: Chang Ho‐Jun , Choi SeungWoon , Yun Tae‐Yeoul
Published: September 2012

This article presents a K‐band CMOS voltage controlled oscillator (VCO) using a wide tuning range MOSFET varactor. The proposed varactor consists of a MOSFET in which the source and drain are connected to each other through a large resistor, the body is grounded through another large resistor, and the gate and source are connected through a capacitor. The newly proposed varactor improves the tuning range of the capacitance compared to that in a conventional MOSFET varactor and a resistors‐added varactor because two large resistors partially cancels the parasitic capacitances of the MOSFET in the depletion mode, and the external capacitor supplements additional capacitance in the inversion mode. The proposed varactor achieves a capacitance tuning range of ±64.5%. The voltage controlled oscillator using the proposed varactor features a wide tuning range characteristic of 11.7% in the K‐Band and shows a good figure‐of‐merit of −186.5 dBc/Hz. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2751–2754, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27164
Nonlinear embedding and de‐embedding techniques for large‐signal fet measurements
Authors: Vadalà Valeria , Avolio Gustavo , Raffo Antonio , Schreurs Dominique M.M.‐P. , Vannini Giorgio
Published: September 2012

The manuscript presents a comparison between two nonlinear procedures oriented to the investigation of the intrinsic I/V dynamic characteristics at a transistor's current‐generator plane. These approaches, without the need of modeling device trapping and thermal effects, allow to obtain information at the current‐generator reference plane that is more strictly linked to the device performance in terms of output power and efficiency. Experiments carried out on a 800‐μm GaN HEMT are reported. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2835–2838, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27169
A novel bias circuit with temperature and process compensation for RFIC
Authors: Lee Jeong‐Cheol , Kim Young‐Woong , Shin Jin‐Ho , Kim Bumman
Published: September 2012

Temperature and process variations have become key issues in design of integrated circuits using deep submicron technologies.In the RF front‐end circuitry, these characteristics must be compensated to maintain acceptable performance across all process corners and throughout the temperature variations. This article proposes a new bias circuit technique to compensate the variations by adding a single NMOS to the normally bias circuit. A 2.4GHz and 5.2GHz LNAs with the proposed bias circuit have the power gain variation (S21) of only 0.3 dB for the −40 to 85°C temperature range in a 65nm RF CMOS process. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2694–2697, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27170
Full wave and asymptotic computation of coupling loss between antennas on aircraft
Authors: Legendre Jean‐Francois , Bréluzeau C.
Published: September 2012

This article presents how to compute the coupling loss between a transmitter and a receiver with full‐wave electromagnetic software.An analytical method based on asymptotic spherical diffraction is proposed, and results of coupling loss between antennas on an un‐named aerial vehicle are compared. Extension to other aircraft sizes is discussed. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2874–2878, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27171
Dual wideband and low cross‐polarization printed dipole antenna with h‐slot for WLAN applications
Authors: Li Xin , Wang Ya‐Fang , Shi Xiao‐Wei
Published: September 2012

A novel dual wideband and low cross‐polarization printed dipole antenna for wireless local area network applications is proposed in this article.Two H‐slots are etched symmetrically on the radiating arms which produce the dual band characteristic. By using the tapered U‐shaped structures, good wide band impendence matching can be achieved without additional matching circuit, and then dual wideband can be obtained conveniently. Based on this concept, a prototype of this antenna has been designed, fabricated, and measured. The experimental results show that the proposed antenna yields two operating bands of 2.17–2.95 GHz and 5.05–6.46 GHz with −10 dB return loss, which can cover all the wireless local area network operating bands. Moreover, the radiation patterns are almost omnidirectional in the H‐plane and low cross‐polarization levels are observed in both the E‐ and H‐plane. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2846–2848, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27173
Novel dual‐band bandpass filters using stub‐loaded short‐ended resonators
Authors: Gao Li , Zhang Xiu Yin
Published: September 2012

This article presents two dual‐band bandpass filters (BPFs) using short‐ended resonators with high selectivity.The properties of the proposed stub‐loaded short‐ended microstrip resonators are analyzed theoretically. In case of uniform short or open stubs, the first two resonant frequencies can be easily controlled within a wide frequency range. Thus, they can be utilized to design dual‐band BPFs with flexible passband frequencies. For demonstration, two dual‐band BPFs have been implemented. Comparisons of the measured and simulated results are presented to verify the theoretical predications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2771–2774, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27177
A novel tri‐band multiple input multiple output antenna with improved bandwidth and isolation
Authors: Babu K. Jagadeesh , Krishna K. Sri Rama , Reddy L. Pratap
Published: September 2012

A novel multislot patch antenna operating from 3.5–5.9 GHz is proposed for a two element multiple input multiple output (MIMO) system. The developed system resonates at the tri‐band of frequencies 2 GHz, 4.2 GHz, and 5.5 GHz, giving an impedance bandwidth of 51% at 10 dB return loss and a reduced mutual coupling less than −50 dB. The enhancement of the bandwidth and the reduction of the mutual coupling are achieved using the reduced ground plane and unique symmetric slot structure. The proposed MIMO system can be used for high speed wireless computer local area networks and WiMAX applications. The measured results are found in good agreement with the simulation results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2766–2770, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27178
Printed circularly polarized wire antennas with DC grounded stub
Authors: Wang Song , Mak Ka Ming , Lai Hau Wah , So Kwok Kan , Xue Quan , Liao Guisheng
Published: September 2012

Two new printed circuit board types double‐folded inverted‐L antennas (DFILAs), which are the horizontal printed DFILA and the vertical printed DFILA, have been proposed.By taking advantage of the printed circuit technologies, the manufacturing processes of the DFILAs can be simplified. The proposed antennas are low profile, lightweight, and simple in structure. Both antennas perform right‐hand circular polarization with center frequency of 2.4 GHz. Both antennas have impedance bandwidths of over 7% (S11<−10dB) and axial ratios of 2.5% (< 3dB). The gains of the two antennas are higher than 6.4 dBi. One of the designs has a simple feeding network with a DC grounded stub, which can improve the impedance matching and provide static discharges for the DFILA. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2719–2725, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27181
Modeling a SIW filter with IRIS windows using equivalent circuits
Authors: Tlaxcalteco‐Matus Miguel Angel , Torres‐Torres Reydezel
Published: September 2012

A model and parameter extraction method for a substrate integrated waveguide (SIW) filter is presented. The proposed approach is derived from an analysis of full‐wave simulations, allowing to obtain the equivalent circuit parameters for the iris. The accuracy of the method is demonstrated through a careful model–experiment correlation, allowing the correct representation of the SIW filter over the complete useful bandwidth. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2865–2868, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27183
Broadband bandpass filter using open complementary split ring resonator based on metamaterial unit‐cell concept
Authors: Afrooz Kambiz , Abdipour Abdolali , Martín Ferran
Published: September 2012

In this article, a compact, wideband, and sharp rejection response bandpass filter based on metamaterial unit‐cell concept is proposed. A series LC resonator using an interdigital capacitor and two meanders is designed, and an open complementary split ring resonator is used to realize the parallel LC resonator. Due to parasitic elements, achieving a pure series LC resonator has some difficulty. However, these parasitic elements can add two resonances more than conventional filters based on the metamaterial unit‐cell. A design procedure based on a simple equivalent circuit is introduced. A compact bandpass filter at 1.475 GHz, with 94% fractional bandwidth, and an attenuation slope with 85.98 and 35.628 dB/GHz in the lower and upper transition bands, respectively, is designed and fabricated. The measured results are in good agreement with the full‐wave electromagnetic simulations inferred by means of Agilent Momentum. The filter has very small size, that is, 0.341λg × 0.1033λg, where λg is the guided wavelength at the filter central frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2832–2835, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27185
Reduced microstrip slot multiband antenna with A U‐shaped resonator for wlan applications
Authors: Flores‐Leal R. , Jardon‐Aguilar H. , Tirado‐Mendez A. , Acevo‐Herrera R.
Published: September 2012

The development of two reduced microstrip slot antennas with a U‐shaped resonant configuration is presented. The additional resonator is located inside the slot and is designed to perform dual band operation, covering the 2.4 GHz and 5.8 GHz WLAN frequency bands. The main goal of the antenna design is to get the optimum size reduction without significant degradation of electrical characteristics compared to a similar antenna reported in literature. The antenna implementation was done using low cost substrates. A size reduction of 84% was got by using a dielectric constant substrate of 10. Simulation and experimental results are presented for both antennas, showing close convergence. Their radiation patterns have quasi‐omnidirectional behavior useful for WLAN applications. Both antennas have small size suitable for mobile applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2684–2689, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27187
Double channel triple band MIMO antenna with high isolation performance and pattern diversity for wireless applications
Authors: Rezaeieh Sasan Ahdi , Pouyanfar Negin
Published: September 2012

A miniaturized monopole antenna with filtering properties is presented.An S‐shape double channel compact multi‐input multi‐output antenna with high isolation performance for DSC‐1800, PCS‐1900, WiMax 3.5 GHz, and WLAN applications is presented in this letter. A total impedance matching bandwidth of larger than 40% for three operating bands is attained through measurements. S‐shape structure has been introduced to reduce the overall width of the diversity configuration to 50 mm. The isolation between the two ports is greater than 24 dB and the envelope correlation is less than 0.0058 over all three bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2689–2691, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27189
Transmitter front‐end with a new wideband active balun in 65‐nm CMOS technology
Authors: Lin Kuan‐Ting , Chen Hsien‐Ku , Wang Tao , Lu Shey‐Shi
Published: September 2012

A 2.4 GHz transmitter front‐end with a wideband active balun is proposed.The wideband active balun is able to work ideally by adopting a resistive compensation technique, which balances the gain of the differential input. In addition, a variable‐gain preamplifier driver with a dynamic range of 18 dB is utilized for the autogain loop control feature. The proposed wideband active balun only occupies 15 × 27 μm2, which is profoundly small compared with conventional baluns and is promising in the differential to single signal conversion in wideband applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2868–2871, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27190
Coplanar waveguide fed monopole antenna with dual‐band operations using square‐shaped slot on conductor‐backed plane
Authors: Moosazadeh Mahdi , Esmati Zahra
Published: September 2012

A compact and simple coplanar waveguide fed (CPW‐fed) monopole antenna with dual‐band applications is proposed. The main features of the proposed antenna are the compact dimensions and band‐operating characteristics that are obtained without modifying the radiator or the ground plane. The antenna consists of a square patch as radiator, a partial CPW‐ground plane, and a slotted conductor‐backed plane. Impedance matching for dual‐band operations is achieved by a pair of mirror square‐shaped slots at the conductor‐backed plane. The proposed antenna has a small size of 15 × 15 × 0.8 mm3, and measured to cover the bandwidth for 5.2 GHz (5150–5350 MHz) and 5.8 GHz (5725–5825 MHz) bands for IEEE 802.11a and also X‐band (8–12 GHz) and provides suitable radiation pattern and antenna gains for the operating bands. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2838–2841, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27191
A clear‐cut understanding of the current‐gain peak in HEMTs: Theory and experiments
Authors: Crupi Giovanni , Raffo Antonio , Schreurs Dominique M. M.‐P. , Avolio Gustavo , Caddemi Alina , Vannini Giorgio
Published: September 2012

The aim of this article is to provide a clear‐cut understanding of the origin of the current‐gain peak (CGP) affecting the microwave behavior of high electron mobility transistors (HEMTs). This effect consists of a sudden increase of the magnitude of the short circuit current‐gain at a given value of the frequency. The present study demonstrates that the CGP can be attributed to the resonance associated to the transition from a capacitive to an inductive behavior of the open circuit output impedance, as confirmed through an extensive experimental analysis. In particular, the CGP is analyzed in HEMT devices based on both GaAs and GaN technologies and its appearance is investigated with respect to the gate width, bias condition, and ambient temperature. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2801–2806, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27192
A multiband film type inverted F‐antenna for GSM, DCS, PCS, USPCS, and WCDMA bands
Authors: Park Sung‐Il , Lee Jahyeon
Published: September 2012

A novel and simple design of a film type inverted F‐antenna for global system for mobile (GSM), digital cellular system (DCS), personal communication system (PCS), US personal communication system (USPCS), and wideband code division multiple access (WCDMA) bands is proposed. The obtained impedance bandwidths reached 87 (880–967) MHz and 451 (1710–2162) MHz in the GSM, DCS, PCS, USPCS, and WCDMA bands. For multiband operation, a modified meander line structure with L‐shaped short pin was used. The measured peak antenna gains for the operating frequencies were 3.18–4.24 dBi. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2757–2762, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27195
Jitter in analog optical links using a quadrature‐biased Mach–Zehnder modulator
Authors: Shin Jong‐Dug , Yoon Young‐Min , Park Jaehee , Chen Ray T.
Published: September 2012

Characteristics of jitter have been investigated in a 10‐GHz analog optical link using a quadrature‐biased Mach–Zehnder modulator followed by an erbium‐doped fiber amplifier (EDFA) and a PIN photodiode. For the case of low optical input power, jitter varies inversely with input power, indicating the thermal noise limited characteristic. For high input optical power, jitter saturates at a minimum for different RF power levels for the configuration without EDFA. For the configuration using EDFA, jitter is also inversely proportional to EDFA gain but shows different minima for different input optical power with output power fixed by adjusting EDFA gain because of amplified spontaneous noise noise. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2725–2727, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27196
A small printed GPS/GLONASS antenna for mobile phones using coupling strips
Authors: Ahn Jungho , Kim Seunghwan , Lee Jaeho , Kim Austin S. , Kim Youngsik
Published: September 2012

This letter presents a small printed PCB‐embedded antenna for a mobile phone with GPS/GLONASS satellite navigation systems. The proposed antenna consists of a feeding strip, two coupling strips, and two chip capacitors. One end of each of the coupling strips is terminated with a chip capacitor and the other end is connected to the ground. The antenna measures 5 mm × 9 mm, and it is placed at the corner of the ground, which measures 40 mm × 70 mm. The bandwidth with a VSWR of 3:1 covers the GPS/GLONASS operation band. The radiation patterns are similar to those of a dipole antenna. The measured peak gain is 0.2 dBi at the GPS/GLONASS frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2736–2736, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27197
Small circular‐shaped UWB antenna for wireless communication applications
Authors: Naser‐Moghadasi M. , Hafezifard R. , Sadeghzadeh R. A. , Seyyedhatami H. , Torkamani M.
Published: September 2012

An effective method is designed and miniaturized for ultra‐wideband (UWB) antenna in the form of planar monopole of circular shape. The antenna includes of a radiation path and an incomplete ground plane to achieve an UWB impedance matching and improve the high frequency radiation performances. Measured return loss of the printed antenna with this technique is less −10 dB from 3–11 GHz which covers the UWB range usable for multiband orthogonal frequency division multiplexing. Also this antenna has an omnidirectional radiation pattern and very good pattern stability over the operating band. The satisfactory results with such a simple plane and small size make this antenna a practical and profitable candidate for UWB wireless communications applications. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2885–2888, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27201
A modular approach to design a full three‐way 8 to 18 GHz MMIC active circulator
Authors: Lim Hong Yi , Ng Geok Ing , Ang Kian Sen , Leong Yoke Choy
Published: September 2012

A modular approach to design full three‐way active circulator is presented. Derived S‐parameters for the modular design approach illustrates that broadband performance can be achieved with broadband performance modules. A full three‐way 8 to 18 GHz MMIC active circulator was designed and fabricated with broadband feedback amplifiers and broadband 180° hybrids. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2858–2861, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27202
Guiding terahertz wave within a line defect of photonic crystal slab
Authors: Rao Lei , Yang Dongxiao , Hong Zhi
Published: September 2012

A terahertz line‐defect waveguide in photonic crystal with a triangular lattice array of cylindrical air holes was fabricated on a silicon slab. Terahertz transmission spectra through this sample were measured and the waveguide with high transmittance exceeding 80% near 0.26 THz was experimentally obtained. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2856–2858, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27203
A 1‐V 1.2‐mW CMOS medradio receiver for biomedical applications
Authors: Cha Hyouk‐Kyu , Yan Dan Lei , Raja M.Kumarasamy , Je Minkyu
Published: September 2012

An ultra‐low‐power low‐voltage 401–406 MHz Medical Device Radiocommunications Service (MedRadio) receiver for continuous wireless communication in biomedical applications is demonstrated using 0.18‐μm CMOS technology. Although using a low‐IF architecture, careful consideration is done for individual block‐level circuit design to minimize the overall power consumption. The receiver chain consists of a complementary current‐reuse LNA, an in‐phase/quadrature folded mixer, an eighth‐order complex bandpass filter, a limiting amplifier chain with RSSI, and a frequency synthesizer with a quadrature VCO. The proposed receiver achieves a gain of over 80 dB, noise figure of 14 dB, image rejection of 32 dB, and phase noise of −106 dBc/Hz at 100 kHz offset while consuming less than 1.2 mW from a 1‐V supply voltage with 1.8 mm2 of core die area. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2821–2825, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27205
Broadband waveguide‐to‐microstrip transition with coupled tuning elements
Authors: Gruszczynski Slawomir , Wincza Krzysztof , Staszek Kamil
Published: September 2012

A broadband planar microstrip to rectangular waveguide transition has been proposed. The transition features simple structure which consists of a planar printed circuit inserted into the shorted waveguide. In the proposed design, a wide bandwidth is achieved with the use of additional tuning elements coupled to the exciting printed probe. The proposed concept of the transition has been investigated numerically and verified by measurements of the fabricated element in the X‐band. Further, a successful design of similar transition has been made in millimeter frequency range operating in W‐band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2787–2789, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27206
Dual band‐notch square monopole antenna with a modified ground plane for UWB applications
Authors: Ojaroudi Nasser , Ojaroudi Mohammad
Published: September 2012

This paper presents a novel small square monopole antenna for UWB applications with dual band‐notch function. By cutting an S‐shaped slot in the ground plane, additional resonance is excited and hence, much wider impedance bandwidth can be produced, especially at the higher band that provides a wide usable fractional bandwidth of more than 120% (2.98–12.25 GHz). To generate a single frequency band‐stop performance, we add a pair of C‐shaped parasitic structures in the ground plane, and also in order to create the second notch frequency, we insert a horizontal rectangular strip in the center of two C‐shaped parasitic structure in the ground plane. The measured results reveal that the presented dual band‐notch monopole antenna offers a wide bandwidth with two notched bands, covering all the 5.2/5.8 GHz wireless local area network, 3.5/5.5 GHz WiMAX, and 4 GHz C bands. Good and radiation behavior within the UWB frequency range have also been obtained. The antenna has a small dimension of 12 × 18 mm2. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2743–2747, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27209
An absorptive bandpass‐integrated p‐i‐n diode T/R switch for 2.5 GHz WiMAX high power terminals
Authors: Phudpong Ravipat , Youngthanisara Narit , Kukieattikool Pratana , Kitjaroen Matanee , Siwamogsatham Siwaruk
Published: September 2012

This article presents a new technique for a transmit/receive (T/R) switch, which originally consists of p‐i‐n diodes and quarterwave lines. By using a reverse‐biased capacitance of the p‐i‐n diodes and additional inductive components, the conventional T/R switch can be made to incorporate a function of a bandpass filter. The filter response can be theoretically designed by configuring the inductance and capacitance values. In this article, an absorptive bandpass‐integrated p‐i‐n diode T/R switch is presented. It achieves a bandpass response at 2.5 GHz with a bandwidth of 450 MHz and an insertion loss of 2.3 dB. It offers high return loss and high isolation, 20 and 50 dB, respectively, and can tolerate power up to 20 W. This filter‐integrated switch could be used as a T/R switch for high power time division duplex systems such as WiMAX in the 2.3–2.7 GHz frequency band. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2705–2708, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27210
Analysis of a novel prime code in IP transmission and routing over FSK‐OCDMA in an optical network unit
Authors: Zoualfaghari M. H. , Ghafouri‐Shiraz H.
Published: September 2012

In this letter, we have analyzed the Internet protocol transmission and routing over frequency‐shift keying optical code division multiple access based on a novel optical code.This code enhances the system bit error rate, packet error rate, number of simultaneous subscribers, and security, as compared to the other prime codes. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2852–2856, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27213
Design of low voltage, low power CMOS low noise amplifier for 2.4 GHz wireless communications
Authors: Huang Chien‐Chang , Ku Kai‐Wei
Published: September 2012

In this letter, design of a low voltage, low power CMOS low noise amplifier (LNA) for 2.4 GHz wireless communications is presented by using TSMC 0.18‐μm technology. The current reused architecture is adapted to reduce the consumed current, while the supply voltage is set to 0.6 V to meet the low voltage requirement as well. To simplify the bias network designs under low voltage operations, NMOS and PMOS devices are used with three‐stage configuration to enhance the gain performance. The measured results of the designed LNA show 17.7 dB in gain and 3.9 dB in noise figure with 0.86 mW of power consumption. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2849–2852, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27214
Microwave oscillator design using folded T‐type slot resonator for X‐band applications
Authors: Shrestha Bhanu , Krishna Maharjan Ram , Kim Nam‐Young
Published: September 2012

In this article, Microwave oscillator was designed, fabricated, and characterized using the folded T‐type slot resonator for X‐band applications. The miniaturized resonator was designed by terminating the slot lines at both ends of the T‐structure. The simulation and experimental results were compared and found a closed agreement between them. The oscillator using the folded T‐type slot resonator showed phase noise performances of −105.54 dBc/Hz at a 100 kHz offset from the carrier frequency of 8.5 GHz with an output power of 14.06 dBm. The oscillator exhibited better phase noise characteristic due to the high unloaded Q value of the folded T‐type slot resonator, which is considerably higher than that of miniaturized spurline resonators. The figure of merit of the oscillator achieved a −183.34 dBc/Hz. The feasibility of integrating that slot resonator in various monolithic microwave integrated circuit technologies can also be expected. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2817–2821, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27215
A simple and efficient finite difference frequency domain method for the analysis and design of leaky‐wave antennas
Authors: Xu Feng
Published: September 2012

The finite difference frequency domain method for the analysis of periodic structures will lead to a large‐scale nonsymmetrical generalized eigenvalue problem, especially when the open periodic structures are analyzed.In this article, the method is greatly simplified, because the large‐scale sparse matrix technique and the shift‐and‐invert Arnoldi technique, which must be applied to significantly reduce the memory need and increase simulation speed, are implemented by means of some existed codes, for example, matlab codes. Besides, the difference equations of this method are much simpler than those of the previous method, because the longitudinal field components do not have to be eliminated to approximately transform the generalized eigenvalue problem to a standard eigenvalue problem. As a result, the method proposed here is quite simple and efficient for the analysis of leaky‐wave antenna, because a leaky‐wave antenna can be regarded as direct geometrical evolution from a guided‐wave structure that permits to leak energy along its longitudinal direction. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2814–2817, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27216
Dual‐band/dual‐polarized microstrip patch antenna for dual‐band heterodyne retrodirective array
Authors: Jung Dong‐Jin , Hansen Jonathan N. , Chang Kai
Published: September 2012

This article presents a dual‐band/dual‐polarized microstrip patch antenna.For a dual‐band retrodirective array system, the dual‐band/dual‐polarized microstrip patch antenna operating at 11 and 12.2 GHz is designed and tested. The antenna consists of one rectangular microstrip patch and a square ring outside of the patch. Two different feeding locations are used for vertical and horizontal polarizations. The vertical polarization is used for a receiving mode and the horizontal polarization for a transmitting mode. The antenna shows a measured gain of 5.2 and 6.8 dBi at 10.9 and 12.2 GHz. The isolation between the two feeding ports is measured to be greater than 15 dB at each center frequency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:2781–2784, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27217
A simple method for the determination of the partitioning of nitroxide probes in microheterogeneous media
Authors: Aliaga Carolina , Torres Paulina , Silva Fernanda
Published: September 2012

The use of the ESR g‐factor of spin labels for the easy and clean assessment of their partitioning in microheterogeneous media is described. The method constitutes a valuable alternative in those cases where the classical Benesi–Hildebrand treatment, based on UV–visible measurements, is difficult or not feasible. Copyright © 2012 John Wiley & Sons, Ltd.
Patterns of Interobserver Error in the Scoring of Entheseal Changes
Authors: Davis C. B. , Shuler K. A. , Danforth M. E. , Herndon K. E.
Published: September 2012

Although the interpretation of entheses has undergone considerable discussion recently, the role of interobserver error, especially in comparative contexts, has been only sporadically addressed. Using standards developed by Hawkey and Merbs, currently the most widely used system, rates of reproducibility were evaluated in two prehistoric North American skeletal series. Eight observers of varying experience levels scored 17 long bone entheses, representing both fibrous and fibrocartilaginous attachment types, on 58 individuals. Results showed rates of reproducibility to be only marginally higher than what would be expected by chance alone.

Observer experience level did not appear to be a factor nor was attachment type. As might be predicted, those entheses enjoying the highest rates of reproducibility exhibited relatively smooth attachment morphology and/or less defined boundaries whereas those with the lowest rates displayed the greatest range of surface morphology expression. Possible explanations for the levels of interobserver error observed include difficulties in reducing the highly variable enthesis morphology to a few discrete categories, categories that encompass too many criteria, and use of vague terminology in describing morphological features. Consequently, comparison of data across studies by different observers, especially those not trained by the developer of a given scoring method, must be undertaken with great caution. Copyright © 2012 John Wiley & Sons, Ltd.
Exploring the actions of Government Affairs Managers during economic and financial crises—an exploratory study in the European Union
Authors: Barron Andrew
Published: September 2012

This paper is a response to the paucity of theoretical and empirical research into the political actions undertaken by organisations to influence policymakers' responses to economic and financial crises. By using original, primary data gathered from semi‐structured interviews conducted with Brussels‐based Government Affairs Managers of multi‐national enterprises, it reports the results of inductive, exploratory research into corporate political activity during the 2007–2011 financial crisis. Results suggest that not all firms are in favour of increased regulatory intervention during times of economic upheaval. They also imply that, during recessions, firms are more likely to seek long‐term as opposed to short‐term relationships with policymakers, they also have a greater propensity to engage in collective political action than individual political action and they use information strategies more frequently than constituency‐building and financial‐incentive strategies. These results are subsequently used as the basis for a conceptual framework that draws on numerous theoretical traditions to capture the antecedents of firms' political behaviours during economic crises. Given the absence of theoretical and empirical work that actively engages with this issue, the research makes important contributions to the existing literature on corporate political activity. It also has practical implications for corporate political strategists and policymakers. Copyright © 2012 John Wiley & Sons, Ltd.
Optimal cut‐offs for down syndrome contingent screening in a population of 10 156 pregnant women
Authors: Guanciali‐Franchi Paolo , Iezzi Irene , Soranno Alessandra , de Volo Chiara Palka‐Bayard , Alfonsi Melissa , Calabrese Giuseppe , Benn Peter
Published: September 2012

Study design

A population of 10 156 pregnant women with singleton pregnancies were screened by the integrated test. Risks were retrospectively recalculated for contingent test strategies with first step intermediate risk groups defined by first trimester upper cut‐offs of 1 : 10, 1 : 30, 1 : 50, and 1 : 70 and lower cut‐offs 1 : 1500, 1 : 1200, 1 : 1100, and 1 : 900. The second trimester high risk group was based on a single cut‐off of 1 : 250.

Results

In the first trimester, the detection rate (DR) ranged from 21% (6/29) to 52% (15/29) as the high risk first trimester cut‐off was changed from 1 : 10 to 1 : 70. The corresponding first trimester false positive rate (FPR) increased from 0.2% to 1.4%. In the second trimester, an additional 21/29 (72%) to 12/29 (41%) affected pregnancies could be detected with an additional 1.6% to 2.7% false positives when lower first trimester cut‐offs of 1 : 900 to 1 : 1500 were used. The best results were obtained with the upper first trimester cut‐off of 1 : 30 and lower first trimester cut‐off of 1 : 900, which yielded a rate of women requiring a second trimester test of only 12%, with overall DR and FPR of 93% and 2.8%, respectively.

Conclusions

Although the study population was relatively small, the results confirm the advantage of using contingent screening and suggest optimal first trimester cut‐offs of 1 : 30 (lower cut‐off) and 1 : 900 (upper cut‐off). © 2012 John Wiley & Sons, Ltd.