bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for positive selection in the extracellular domain of human cytomegalovirus encoded G protein‐coupled receptor US28
Authors: Gong Xiaoyan , Padhi Abinash
Published: April 2011

The human cytomegalovirus (HCMV)‐encoded chemokine receptor US28 is also a seven‐transmembrane G‐protein coupled receptor, whose signaling pathway is known for its involvement in host immune system evasion. HCMV infection can result in serious disease in immunocompromised individuals and is also linked to atherosclerosis and cardiovascular disease. Identifying amino acid residues that play a crucial role in successful viral adaptation in response to the host's immune defense is critical for effective drug design. In this study maximum likelihood‐based codon substitution analyses were carried out to determine whether any codon of US28 has evolved adaptively. If the rate of nonsynonymous (dn) to the rate of synonymous (ds) nucleotide substitutions (ω = dn/ds) is greater than one, the codon is said to be under positive selection, indicating adaptive evolution. Although the overall ω for US28 gene was 0.154, indicating that most codon sites were subject to strong purifying selection, five codon sites are under strong positive selection. Three (E18D/L, D19A/E/G, and R267K/Q) of these positively selected sites are located in extracellular domains, the domains that play a crucial role for successful viral adaptation in response to the host's immune defense. The C‐terminal (R329Q/W) and the fifth transmembrane domain (V190I), each have one positively selected site. These results suggest that relative to the extracellular domains, amino acid residues present in intracellular domains are more selectively constrained. A few amino acid residues in extracellular domains of US28 evolved more rapidly, presumably due to positive selection pressure resulting from ligand‐binding and pathogen interactions of extracellular domains. J. Med. Virol. 83:1255–1261, 2011. © 2011 Wiley‐Liss, Inc.
Characterization of woodchuck apolipoprotein A‐I: A new tool for drug delivery and identification of altered isoforms in the woodchuck chronic hepatitis model
Authors: Fioravanti Jessica , Gomar Celia , Medina‐Echeverz José , Otano Itziar , Benito Alberto , Prieto Jesús , González‐Aseguinolaza Gloria , Berraondo Pedro
Published: April 2011

Apolipoprotein A‐I (ApoA‐I) is the major protein component of high density lipoprotein (HDL) particles in serum, and participates in the reverse transport of cholesterol from tissues to the liver for excretion. The natural HDL tropism to the liver and cancer cells has been used extensively to target encapsulated drugs. The alteration of the plasmatic isoforms of ApoA‐I is a hallmark of chronic hepatitis and hepatocarcinoma in mice and humans. Woodchucks infected with the woodchuck hepatitis virus (WHV) represent the best animal model for the study of chronic viral hepatitis B and viral induced hepatocarcinoma (HCC). WHV‐infected woodchuck represents a clinically relevant animal model under which new treatment strategies can be evaluated and optimized. Therapeutic efficacy in this model is likely to be translated into a successful therapy for patients infected with HBV. The present study describes, for the first time, the cloning and characterization of woodchuck ApoA‐I. The open reading frame (ORF) of the woodchuck ApoA‐I is 795 bp long, coding for 264 amino acids. Unexpectedly, phylogenetic analysis revealed that the closest sequences are those of human and macaque. Woodchuck HDLs were isolated successfully from sera by density gradient ultracentrifugation. A commercial antibody that recognized the woodchuck ApoA‐I was also identified. Finally, taking advantage of the techniques and tools developed in this study, two potential applications of woodchuck HDLs are illustrated: drug delivery to a woodchuck hepatocarcinoma cell line and the use of isoelectrofocusing to identify ApoA‐I isoforms. J. Med. Virol. 83:1221–1229, 2011. © 2011 Wiley‐Liss, Inc.
Short‐term responses of birds to prescribed fire in fire‐suppressed forests of California
Authors: Bagne Karen E. , Purcell Kathryn L.
Published: April 2011

Prescribed fire is one tool for restoring fire‐suppressed forests, but application of fire during spring coincides with breeding and arrival of migrant birds. We examined effects of low‐severity prescribed fires on counts of birds in a managed forest in the Sierra Nevada of California immediately, 1 year, and 3–6 years after fire was applied in spring. Of 26 species analyzed, counts of 3 species increased after fire (Pacific‐slope flycatcher [Empidonax difficilis], brown creeper [Certhia americana], and American robin [Turdus migratorius]), and 6 species decreased after fire (Anna's hummingbird [Calypte anna], Hutton's vireo [Vireo huttoni], warbling vireo [Vireo gilvus], golden‐crowned kinglet [Regulus satrapa], Nashville warbler [Vermivora ruficapilla], hermit warbler [Dendroica occidentalis]). Black‐throated gray warbler (Dendroica nigrescens) increased in the first year following fire but decreased 3–6 years after fire. When grouped into guilds, habitat association and foraging guild best explained responses to fire, with the greatest changes occurring for oak‐associated species (negative), riparian‐associated species (positive), aerial foragers (positive), and bark foragers (positive). Lastly, when we compared our counts to those collected during the 1910s, changes were consistent with those predicted from fire suppression and species' affinity for burned forests, suggesting that results from contemporary fire studies should be interpreted within an ecological context that includes effects of fire suppression. We found that low‐severity prescribed fires applied in spring served to drive the bird community towards pre‐suppression conditions. © 2011 The Wildlife Society.
Broccoli‐derived phytochemicals indole‐3‐carbinol and 3,3′‐diindolylmethane exerts concentration‐dependent pleiotropic effects on prostate cancer cells: Comparison with other cancer preventive phytochemicals
Authors: Wang Thomas T.Y. , Schoene Norberta W. , Milner John A. , Kim Young S.
Published: April 2011

In the present studies, we utilized prostate cancer cell culture models to elucidate the mechanisms of action of broccoli‐derived phytochemicals 3,3′‐diindolylmethane (DIM) and indole‐3‐carbinol (I3C). We found DIM and I3C at 1–5 µM inhibited androgen and estrogen‐mediated pathways and induced xenobiotic metabolism pathway. By contrast, DIM and I3C induced cyclin inhibitors, indicators of stress/DNA damage, only at ≥25 µM. We also demonstrated that an inhibitory effect of DIM and I3C on cell growth involves inhibition of insulin‐like growth factor‐1 receptor expression. More importantly, we showed that differences in efficacies and mechanisms existed between DIM and I3C. These included differences in effective concentrations, a differential effect on androgen receptor binding, and a differential effect on xenobiotic metabolic pathway through aryl hydrocarbon receptor‐dependent and ‐independent mechanism. Furthermore we determined that several other diet‐derived cancer protective compounds, similar to DIM and I3C, exhibited pleiotrophic effects on signaling pathways that included proliferation, cell cycle, and nuclear receptors‐mediated pathways. However, the efficacies and mechanisms of these compounds vary. We also showed that some cellular pathways are not likely to be affected by DIM or I3C when circulating concentration of orally ingested DIM or I3C is considered. Based on our results, a model for cancer protective effects of DIM and I3C was proposed. © 2011 Wiley Periodicals, Inc.
Rhodiola rosea extracts and salidroside decrease the growth of bladder cancer cell lines via inhibition of the mTOR pathway and induction of autophagy
Authors: Liu Zhongbo , Li Xuesen , Simoneau Anne R. , Jafari Mahtab , Zi Xiaolin
Published: April 2011

The incidence of human urinary bladder cancer increases markedly with age, suggesting a mechanistic connection between aging and bladder carcinogenesis and a potential use of anti‐aging agents in bladder cancer chemoprevention. Rhodiola rosea, growing in high altitude or cold regions of the world, has been reported to have anti‐aging effects in Drosophila. We demonstrated that a R. rosea extract and one of its bioactive components, salidroside, inhibited the growth of bladder cancer cell lines with a minimal effect on nonmalignant bladder epithelial cells TEU‐2. Interestingly, the R. rosea extract and salidroside component exhibited a selective ability to inhibit the growth of p53 knockout primary mouse embryo fibroblasts (p53−/− MEFs) compared to their wild‐type counterparts. The growth inhibitory effects of the R. rosea extract and salidroside were, however, attenuated in TSC2 and p53 double knock MEFs (TSC2−/−, p53−/− MEFs), suggesting that TSC2 protein is, at least in part, required for the growth inhibitory effects of the R. rosea extract and salidroside. The R. rosea extract and salidroside treatment of UMUC3 cells resulted in an increase of AMP‐activated protein kinase (AMPK)‐α phosphorylation and a decrease of 4E‐BP1 phosphorylation, leading to increased binding of 4E‐BP1 to m7 GTP. These results indicate that the R. rosea extract and salidroside inhibit translation initiation. Furthermore, both the R. rosea extract and salidroside treatment of UMUC3 cells caused a significant percentage of cells undergoing autophagy. Therefore, the R. rosea extract and salidroside deserve further study as novel agents for chemoprevention of bladder carcinogenesis. © 2011 Wiley Periodicals, Inc.
Efficacy and safety of incobotulinumtoxinA (NT 201, Xeomin) in the treatment of blepharospasm—A randomized trial
Authors: Jankovic Joseph , Comella Cynthia , Hanschmann Angelika , Grafe Susanne
Published: April 2011

IncobotulinumtoxinA (NT 201, Xeomin) is a highly purified botulinum neurotoxin type A formulation, free from complexing proteins. A randomized, placebo‐controlled, double‐blind trial of efficacy and safety compared incobotulinumtoxinA (up to 50 U per eye) to placebo administered in a single treatment session to patients with blepharospasm. All patients had documented satisfactory response to 2 previous treatments with botulinum neurotoxin type A other than incobotulinumtoxinA and had Jankovic Rating Scale severity subscores ≥ 2. Patients (n = 109) were randomized in a 2:1 ratio to incobotulinumtoxinA or placebo and followed up to 20 weeks; 94% completed the study. A significant difference was observed in the primary efficacy variable (change in Jankovic Rating Scale severity subscore rated by an independent rater 6 weeks following treatment), favoring incobotulinumtoxinA by 1.0 point (95% CI [0.5–1.4]; P < .001). Functional impairment, as measured by the Blepharospasm Disability Index, improved by 0.5 points (95% CI [0.2–0.7]; P = .002) compared with placebo. There was a strong correlation between the 2 scale scores. In addition, all secondary outcome measures favored incobotulinumtoxinA. Patients rated the mean therapeutic effect of incobotulinumtoxinA significantly better than placebo (P < .001). Adverse events were reported in 70.3% of incobotulinumtoxinA patients and 58.8% of placebo patients. Eyelid ptosis (18.9% vs 5.9%), dry eye (18.9% vs 11.8%), and dry mouth (14.9% vs 2.9%) occurred most frequently. Tolerability was rated good/very good by 91.9% of incobotulinumtoxinA versus in 85.2% of placebo patients. In conclusion, incobotulinumtoxinA was well tolerated and was associated with statistically significant and clinically relevant reductions in blepharospasm severity and functional impairment. © 2011 Movement Disorder Society
A mechanism to electrically enlarge the ground plane of handset antennas: A bandwidth enhancement technique
Authors: Anguera Jaume , Andújar Aurora , Puente Carles
Published: April 2011

There is a need of developing new techniques for enhancing the bandwidth of handset antennas without increasing the antenna volume in order to incorporate more frequency bands into the cell phones. The technique to enhance the bandwidth proposed herein consists in adding a conductive strip connected to the ground plane at the opposite edge of the handset antenna location. Conductive strip tunes the ground plane mode to effectively improve the bandwidth at the low frequency region (∼900 MHz) while keeping the same antenna volume. An electrical model is used to give an insight into the behavior concluding that the conductive strip is a useful mechanism to improve the bandwidth. The model demonstrates that the length of the conductive strip can be reduced by inductive or dielectric loading, as well as by reducing its height. Simulations and measurements show how the conductive strip excites the resonance of the ground plane mode improving the bandwidth and validating the electrical model predictions. The proposed technique is applied to a dual‐band (900–1800 MHz) planar inverted F‐antenna providing a measured bandwidth enhancement of 1.6 times when using the strip at the low frequency region while keeping the same performance at the high frequency region (∼1800 MHz). © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26027
CMOS 45‐nm 3D metal‐oxide‐metal capacitors for millimeter wave applications
Authors: Quémerais Thomas , Moquillon Laurence , Benech Philippe , Fournier Jean‐Michel , Pruvost Sébastien
Published: April 2011

Novel 3D metal‐oxide‐metal capacitors for 60 GHz applications in a CMOS 45 nm process are proposed. Relatively high capacitances density of 3 fF/μm2 and quality factors from 3.2 to 10.2 at 60 GHz are measured. The study is validated up to 110 GHz for different capacitance values. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26029
A novel X‐band broadband bandstop filter with sharp cut‐off frequency using EBG dual‐ear structures
Authors: Huang J.‐M. , Zhu H. Z. , Han K. , Guo H.
Published: April 2011

A novel X‐band broadband bandstop filter (BSF) with sharp cut off frequency is presented, using novel design of periodic electromagnetic bandgap (EBG) dual‐ear (DE) structures on coplanar waveguide (CPW) transmission line. An equivalent lumped circuit is introduced to model the BSF with EBG‐DE structures. The stopband of this filter is ranged within X‐band to have sharp selectivity and deep attenuation levels. The 3‐dB bandwidth of the BSF is 4.2 GHz, from 8.6 to 12.8 GHz and the center frequency is 11.5 GHz. The 20‐dB bandwidth is 2 GHz, from 9.9 to 11.9 GHz. In 20‐dB stop‐band range, the ripple of return loss is less than 0.05 dB.The proposal BSF is fabricated using the surface micromachining, and the measurement and simulation results coincided well. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26031
A compact class‐F/class‐C Doherty amplifier
Authors: Eccleston K. W. , Smith K. J. I. , Gough P. T.
Published: April 2011

A Doherty amplifier is described in which odd harmonics from the class‐C peaking amplifier flow to the main amplifier to achieve class‐F operation, without the need for complicated space consuming harmonic control circuits. The measured efficiency exceeded 50% above the 6 dB back‐off. The measured second and third harmonic levels were below −19 dBc. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26035
A beam switching array antenna for direction‐of‐arrival applications
Authors: Liao Wen‐Jiao , Chang Shih‐Hsun , Liu Hsin‐Chin , Li Lung‐Kun , Hsieh Chih‐Yao , Yao Chia‐Chi
Published: April 2011

In this article, a beam‐switching array antenna system is devised to estimate the direction‐of‐arrival (DOA) of radio frequency (RF) signals.The array contains 16 patch antennas arranged as a uniform circular array. In operation, four adjacent antenna elements are connected to RF tuners via RF switches to create a directive beam. By reconfiguring the switch setups, a rotating beam is produced to cover the azimuth plane. The angle of an incoming RF signal is estimated by processing the received signal strengths from the 16 beam setups via the curve‐fitting technique. Through measurements, the error in incident angle is found less than 3° with a simple estimation method. As the array antenna system is implemented with a receiver made of software‐defined radio, DOA estimation with more accuracy and multiple source monitoring are possible with more complicated signal processing techniques. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26036
Frequency reconfigurable circularly polarized slot antennas with wide tuning range
Authors: Lee Tsung‐Yu , Row Jeen‐Sheen
Published: April 2011

Frequency tunable annular‐ring slot antennas with circularly polarization (CP) operation are studied in this article. The annular‐ring slot antenna operates at one full‐wavelength resonant mode and it is excited by an L‐shaped coupling strip with a reactive loading. It is found that the operating frequency of the slot antenna can be tuned by varying the capacitance values of four capacitors, which are symmetrically placed along the circumference of the ring slot. Moreover, for each operating frequency in the tunable range, good CP performance can be obtained as long as the reactance of the loading is properly adjusted. Both measured and simulated results indicate the CP operating frequency of the proposed design can be tuned between 1.58 and 2.59 GHz. A prototype integrating with two varactor diodes is also implemented so that the CP operating frequency can be switched by controlling dc biases. Details of the antenna designs and measured results are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26041
Compact ultra‐wideband bandpass filter based on novel defected ground structure and folded coupled lines
Authors: Mou Jinchao , Yu Weihua , Lv Xin
Published: April 2011

A compact ultra‐wideband bandpass filter is presented. The proposed UWB filter consists of a couple of folded parallel lines and a low‐pass filter based on defected ground structure. Good bandpass performance and wide rejection characteristics can be achieved by this new structure. One prototype is fabricated to demonstrate the validity of the proposed strategies. The simulated and measured results indicated that the insertion loss is less than 1.5 dB between the 3.1 and 10.5 GHz with a sharp falling edge of 35 dB/GHz and its group delay is less than 0.5 ns in the pass band. The rejection is better than 20 dB from 12.5 to 25 GHz. The total size of the UWB BPF is 0.78 λg × 0.23 λg where λg is the guided wavelength at the center frequency of 7.4 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26045
Heterogeneous breast phantom for ultra wideband microwave imaging
Authors: Bakar Aslina Abu , Abbosh Amin , Sharpe Philip , Bialkowski M.E. , Wang Yifan
Published: April 2011

With the growing interest in the microwave imaging for early breast cancer detection, there is a need to develop an advance artificial breast phantom to emulate the interactions of electromagnetic waves with biological tissues. In this article, details of a realistically shaped heterogeneous breast phantom manufactured for the use in an ultra wideband microwave imaging system are presented. The developed phantom has electrical characteristics which are in good agreement with those of real breasts. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26046
Low phase‐noise planar oscillators using high‐Q SIW bandpass filter
Authors: Zhao Shiwei , Tang Zongxi , Dai Wei , Bao Lifen
Published: April 2011

A low phase‐noise planar X‐band oscillator using high‐Q substrate integrated waveguide (SIW) bandpass filter within its feedback loop is presented.The SIW filter as a frequency stabilization element is used in planar oscillator, and the phase noise of oscillator is significantly reduced by the group‐delay peaks formed at the passband edges of the high‐Q SIW filter. A 9‐GHz oscillator using the optimized high‐Q SIW filter in the feedback loop is designed and tested. The measured phase noise of planar oscillator is 115.3 dBc/Hz at 100‐KHz offset frequency with 9.97‐dBm as output power. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26047
Design and fabrication of period interlaced ULPG that inhibit specific resonance peaks
Authors: Fan HongJian , Zhang WeiGang , Li XiaoLan , Wei ShiLei , Yan AiDong , Wang Kai
Published: April 2011

We present and realized a novel structure of ultra‐long‐period fiber gratings (ULPG), which can inhibit specific resonance peak selectively while the wavelength of other peaks rarely change. This compounded ULPG is similar in form to two uniform ULPG interlaced through parallel moving. Owing to the ratio moved equivalent, the peaks caused by 2nd, 3rd or 4th diffraction order will be intentionally inhibited. Experimental results has verified this novel structure and the transmission spectrum observed in experiment shows accordance with the theoretical analysis. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26048
Broadband UHF RFID tag antenna with parasitic patches for metallic objects
Authors: Lai MingYin , Li RongLin
Published: April 2011

A novel low‐profile broadband UHF RFID tag antenna with two parasitic patches is proposed.The tag antenna's bandwidth can be greatly enhanced by adding parasitic patches which are gap coupled to the driven patch for the excitation of additional resonant modes. The half‐power bandwidth of the proposed antenna covers all the UHF RFID frequency bands, and the power reflection coefficient is lower than −7dB in the UHF RFID frequency bands (840–960 MHz). The proposed antenna can be easily fabricated at low cost by etching at a thin inexpensive FR4 substrate. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26049
Polymer waveguide delay device using right‐angle X junctions
Authors: Yi Yunji , Chen Changming , Zhao Pengcheng , Ma Chunsheng , Wang Fei , Zhang Daming
Published: April 2011

A four‐channels polymer waveguide delay device is demonstrated and fabricated using direct ultra‐violet photolithography process. The device is composed of right‐angle junctions and bending waveguide. The optimized structural properties of the device and fabrication procedures are demonstrated. The loss of bending waveguides and right‐angle X junction is calculated. The near‐infrared field guided‐mode patterns of the devices are obtained. Each incoming radio‐frequency signal can be independently received. Measured delays are 0, 60.9, 121.9, and 182.9 ps. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26050
Quadruple‐mode broadband BPF with sharp skirt and wide upper‐stopband performance
Authors: Deng Hong‐Wei , Zhao Yong‐Jiu , Zhang Lu , Zhang Xue‐Shun , Qiang Li
Published: April 2011

In this article, a broadband bandpass filter (BPF) with sharp skirt and wide upper‐stopband performance is proposed using the quadruple‐mode stub‐loaded resonator.The resonator formed by attaching three stepped‐impedance open stubs to high impedance microstrip line can generate two even‐mode resonant frequencies fm1 and fm3 and two odd‐mode ones fm2 and fm4 in the desired band. The fm2 can be approximately determined by the high impedance microstrip line. The open stub at the center plane can only control the even‐modes and two identical open stubs are mainly applied to adjust the resonant frequencies fm3 and fm4. Two transmission zeros are created near the cutoff frequencies by the open stub at the center plane and two interdigital coupling feeding lines, leading to sharp shirt. Two additional transmission zeros are generated in the upper‐stopband by two identical open stubs and two interdigital coupling feeding lines to suppress two main high harmonic resonant frequencies. A broadband filter prototype is simulated, fabricated, and measured. The measured results agree well with the electromagnetics (EM) simulations. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26051
Suppression of multiple mode instabilities in an erbium‐doped fiber laser by inserting a highly nonlinear photonic crystal fiber
Authors: Zhang Ailing
Published: April 2011

Multiple mode instabilities in erbium‐doped fiber laser are undesirable due to the large amplitude noise in the laser. One scheme is proposed to suppress this kind of instabilities by inserting a highly nonlinear photonic crystal fiber in the ring cavity. The results show that the nonlinear effect not only eliminates the laser instability but also suppresses the noise in the laser. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26053
Band‐notched ultra‐wideband planar monopole antenna using shunt open‐circuited stub
Authors: Pan Chien‐Yuan , Chiu Kuo‐Yung , Duan Jhih‐Hao , Jan Jen‐Yea
Published: April 2011

This article presents an ultra‐wideband planar monopole antenna with band‐notched characteristics.The proposed antenna consists of a sector monopole and a microstrip feedline with a quarter‐wavelength open‐circuited transmission line (a stub). The open‐circuited stub is connected in parallel with the microstrip feedline in order to achieve band‐notched performance. The measured impedance bandwidth for voltage standing wave ratio (VSWR) ≤ 2 is from 3.01 to 11 GHz, except the notched band of 5.08 to 5.96 GHz for the WLAN system. This design technique is very suitable to develop other planar antennas for band‐notched applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26054
Band‐notched UWB planar antenna with parasitic spiral strips
Authors: Xia Tengfei , Yang Shiwen , Nie Zaiping
Published: April 2011

A novel band‐notched ultra‐wideband (UWB) planar antenna with a pair of parasitic spiral strips is proposed in this article. The antenna composed of a planar monopole and a plane in the same shape of half circle achieves UWB properties, whereas a pair of parasitic spiral strips with small sizes at the monopole plane can be used to reject certain frequency band. The center frequency and bandwidth of the rejected band are both adjustable by partially changing the shape of the parasitic spiral strips. Numerical examples for the cases without rejection, narrow band or wide band rejection are presented for comparison. Simulated and measured results show that the proposed UWB planar antenna with parasitic spiral strips can be used to obtain band‐notched properties at the desired band. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26055
Wideband rectangular ring patch antenna with a three‐pointed‐star strip for WLAN/WiMAX applications
Authors: Ren Xueshi , Yin Yingzeng , Zheng Shufeng
Published: April 2011

In this article, a novel wideband rectangular ring patch antenna for WLAN and WiMAX applications is presented. The antenna is composed of a rectangular ring with microstrip feed line, a three‐pointed‐star strip and a partial ground plane. With the three‐pointed‐star strip, the rectangular ring patch antenna can realize wide impedance bandwidth (return loss ≥ 10 dB) of 4162 MHz (2.384–6.546 GHz), which make it easy to cover the required bandwidths for WLAN bands (2.4–2.483, 5.15–5.35, and 5.725–5.825 GHz) and WiMAX bands (2.4–2.6, 3.3–3.8 and 5.25–5.85 GHz) applications. Details of the proposed wideband antenna design are presented and discussed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26061
Analysis of ground layout effect in CMOS concurrent dual‐band LNA
Authors: Liu Yang , Kim Hyeongdong
Published: April 2011

Ground planes are often used on the integrated circuits.An improperly designed ground plane can be a major source of noise and attenuation to affect the circuit performances. Using a full‐wave simulator HFSS, this article analyzes a ground plane effect in layout of a CMOS concurrent dual‐band low‐noise amplifier (LNA). The concurrent dual‐band LNA that operates at 2.4 and 5.2 GHz is fabricated using 180‐nm CMOS technology. Comparing with the circuit simulation result, the measured result shows a 7‐dB gain reduction at 5.2 GHz. In an attempt to find the cause and solve the problem, a full‐wave simulation that can analyze the layout effects is carried out. On the basis of the full‐wave analysis, we determine that the ground plane potentially produces a parasitic inductive component which deteriorates the gain performance at the higher operating frequency band. A modified ground plane layout for reducing the parasitic inductance is proposed, and the LNA achieves the improved gain and noise performances similar to the circuit simulation. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26062
Experimental study of the optical waveguides by scanning near‐field optical microscopy (NSOM)
Authors: Yan Chunsheng
Published: April 2011

In this article, the ordinary optical waveguides are investigated by the near field optical microscopy (NSOM). Three kinds of experimental systems are set up and the corresponding operation modes of NSOM (illumination mode, illumination‐collection mode and collection mode) are realized and analyzed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26068
A broadband suspended substrate stripline filter using dual‐mode resonator
Authors: Kim Jin‐Sup , Lee Kyu‐Bok , Lee Jae‐Young , Shin Hyunchol
Published: April 2011

A broadband suspended substrate filter is proposed and implemented using dual‐mode resonator aiming at transmitting the signals in the passband of 10–18 GHz. It is composed of two quarter‐wavelength resonators and inductor. The inductor is a short‐circuited stub. After optimization of this filter, a good bandpass behavior with 10 transmission poles is theoretically realized and experimentally confirmed. Within the whole BPF passband, the return loss is found better than 10 dB, and the insertion loss is less than 1.9 dB. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26070
Enhancement of power and frequency in Planar Gunn diodes by introducing extra delta‐doping layers
Authors: Li Chong , Khalid Ata , Caldwell Sonia H.Paluchowski , Pilgrim Neil J. , Holland Martin C. , Dunn Geoffrey M. , Cumming David R. S.
Published: April 2011

Planar Gunn diodes operating above 100 GHz fabricated in GaAs/AlGaAs heterojunction structures with single and double δ‐doping layers on each side of GaAs channel are numerically studied and experimentally demonstrated. The results show enhanced RF power and oscillation frequency when double δ‐doping technique was used. By using a two‐dimensional numerical simulation tool, the conduction band profile, electron concentration in the epitaxy layers and current‐voltage characteristics are investigated. Simulation results indicate that extra δ‐doping layers increase electron confinement in the conducting channel, therefore higher current levels are obtained. Simulated current‐voltage characteristics in both cases agree well with experimental results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26071
Dual‐band push‐push OSC using CRLH transmission line and tunable negative resistance based on pin diode
Authors: Kim Yang‐Hyun , Choi Jaewon , Seo Chulhun
Published: April 2011

In this article, the dual‐band oscillator (OSC) using the composite right/left‐handed (CRLH) transmission ‐line (TL) and the tunable negative resistance based on the pin diode is presented. It is demonstrated that the CRLH TL can lead to metamaterial transmission line with the dual‐band tuning. The dual‐band push‐push oscillator design approach demonstrated in this work enables higher OSC frequency operation, lower noise performance, and smaller size, which is attractive for military radar frequency source applications. The phase noise of OSC is from −110.12 to −111.27 dBc/Hz @ 100 kHz in the tuning range, 4.05–4.11 GHz for the forward bias of the pin diode, whereas that of OSC is from 112.26 to −113.13 dBc/Hz @ 100 kHz in the tuning range, 9.97–10.17 GHz for the reverse bias of the pin diode. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26072
A miniature CMOS VCO with symmetric trace differential stacked spiral inductor
Authors: Kim Joonchul , Lee Jaeseok , Nam Byungjae , Kim Hyeongdong
Published: April 2011

In this study, a miniature silicon‐based symmetric trace differential stacked spiral inductor (SDSSI) was used in the design of a voltage controlled oscillator (VCO) using standard 0.18 μm CMOS technology. The SDSSI has a high self‐resonance frequency (fsr) and quality factor (Q) in spite of using the stacking technique, because the parasitic capacitance between the layers is reduced by alternatively locating traces at different positions in each layer. The output power spectrum and phase noise of the designed VCO is −0.79 dBm and 114 dBc/Hz at 1‐MHz offset frequency, respectively. The oscillation frequencies cover from 1.84 GHz to 2.38 GHz with a tuning range of 26%, while the occupied on‐chip area of the VCO is only 350 × 450 μm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26073
Dual‐band transformer‐coupled quadrature injection‐locked frequency dividers
Authors: Jang Sheng‐Lyang , Yang Ren‐Kai , Chang Chia‐Wei , Juang Miin‐Horng , Liu Cheng‐Chen
Published: April 2011

This letter proposes a dual‐band divide‐by‐2 transformer‐coupled quadrature injection‐locked frequency divider (QILFD).The QILFD is composed of a transformer‐coupled quadrature voltage controlled oscillator and two injection MOSFETs. The CMOS QILFD has been implemented with the Taiwan Semiconductor Manufacture Company (TSMC) 0.18 μm CMOS technology, and the core power consumption is 3.997 mW at the supply voltage of 0.7 V. The tank impedance of the QILFD shows a dual resonance behavior, which leads to a dual‐band locking range at a fixed bias condition. At the injection input power of 3 dBm, the low‐band and high‐band divide‐by‐2 locking ranges are from 6.90 to 8.56 GHz and 9.52 to 12.10 GHz, respectively. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26074
Electrically coupled tapered slot ultra wideband antenna with tunable notch
Authors: Yang Xiao Dong , Rahman A. , Abbasi Qammer H. , Hao Y.
Published: April 2011

A band notch characteristic using a unequi‐arm H‐shaped conductor element is used for designing a Tapered‐Slot ultra wideband (UWB) antenna that can be useful in rejection of the higher band assigned for wireless local area network, with a targeted application in UWB wireless body area network. Based on the simulation and measurement results, a band notched tapered slot UWB antenna using a unequi‐arm H‐shaped conductor proves to be effective in rejecting unwanted frequency in terms of its selectivity and small real estate. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26075
Experimental investigations on line‐of‐sight multiple‐input‐multiple‐output channel characteristics with multi‐polarization antenna arrays
Authors: Zhang Nianzu , Li Linsheng , Hong Wei
Published: April 2011

In this article, the line‐of‐sight (LOS) multiple‐input‐multiple‐output (MIMO) channel characteristics with multiple polarized antenna arrays are experimentally investigated. The channel transmission matrices under different combinations of up to six kinds of antenna polarizations are measured, and then the matrix condition number and channel capacity are studied. It is concluded from the results that we can achieve lower matrix condition number and higher capacity with proper combination and configuration of antenna polarization in LOS environment. Furthermore, the relationship between channel capacity and channel matrix condition number is also analyzed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26078
A compact planar bandpass filter with wide out‐of‐band rejection implemented by substrate‐integrated waveguide and complementary split‐ring resonator
Authors: Deng Kuan , Guo Zengxu , Li Chao , Che Wenquan
Published: April 2011

A compact planar bandpass filter is presented in this letter, which is implemented by the combination of three different electromagnetic structures, saying, substrate‐integrated waveguide (SIW), square complementary split‐ring resonators (CSRRs) and dumbbells slot.The resonator is formed by a SIW cavity loaded with some complementary split‐ring resonators (CSRRs) on its top metal plane, causing a stopband with a very sharp rejection. Meanwhile, several dumbbells are etched on the bottom plane of SIW just below each CSRR to enhance the coupling. Double‐sided parallel strip line (DSPSL) is also used to excite the SIW and guarantee good propagation between these two different structures. An X‐band prototype is designed and fabricated for demonstration, good agreement is observed between simulation and measurement, indicating a very wide rejection band ranging from 11 GHz to 23 GHz and quite strong suppression to spurious modes. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26079
Analysis of losses in a double‐negative metamaterial composed of magnetodielectric spheres embedded in a matrix
Authors: Liu Jin , Bowler Nicola
Published: April 2011

A simple‐cubic lattice of identical, magnetodielectric spheres exhibiting double‐negative (DNG) behavior is analyzed.An analytic expression for the threshold loss angle δth of the spheres, above which DNG behavior is extinguished, is derived by utilizing the Möbius transformation. The formula is valid for either dielectric or magnetic loss exhibited by the particles, and is derived based on the dipole approximation of Mie's theory of scattering by a sphere. For spheres with equal real relative permittivity and permeability, it is shown that δth increases as particle volume fraction increases. It is also shown that the loss angle of the effective medium can be controlled by appropriate choice of frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26081
Direct modulation of multimode fiber Bragg grating external cavity lasers
Authors: Xu Qing‐Yang , Yan Minhui , Xu Chang‐Qing , Li Xun
Published: April 2011

Direct modulation characteristics have been investigated for a Fabry‐Perot laser diode coupled with a multimode fiber Bragg grating.Large signal modulation at 2.5 Gb/s with none‐return‐to‐zero format has been demonstrated for the 2‐cm long multimode fiber Bragg grating external cavity laser. By using a short external cavity of about 7.5 mm, small‐signal frequency responses larger than 8 GHz are achieved. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26083
Step index holey fiber design by genetic algorithm for chromatic dispersion compensation
Authors: da Silva José Patrocínio , Bezerra Diego Souza , Hernández‐Figueroa H.E.
Published: April 2011

A new approach to obtain ultra‐flattened‐chromatic‐dispersion‐optical‐fibers by introducing a small airhole at the core of a conventional step‐index‐optical‐fiber is presented. The proposed structure exhibits a simple geometry and has been analyzed through a vectorial finite element method in conjunction with genetic algorithm. The structure parameters are optimized using genetic algorithm to obtain ultra wideband residual dispersion compensation. Numerical results show that the optimized model exhibits flattened negative dispersion over E + S + C + L + U wavelength bands with an average dispersion of −253 ps km−1 nm−1. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26084
A compact and small printed monopole antenna for WLAN applications
Authors: Chen Wen‐Shan , Lee Bau‐Yi , Chang Po‐Yuan
Published: April 2011

This article proposes a compact and small printed monopole antenna for wireless local area network (WLAN) applications.The substrate used in this design is an FR4 substrate with a permittivity of 4.4, which is an inexpensive and widely used printed circuit board (PCB). The overall dimensions of the proposed antenna (25 × 20 × 1.6 mm3) can be easily applied in todays portable wireless products. The low‐frequency band centered at 2.4 GHz is resonated by the coupling between the U‐liked ground plane and 50‐ohm microstrip feed‐line. When the rectangular patch A is added on the ground plane, the high‐frequency band centered at 5.48 GHz is obtained. Because of the different polarization direction, the radiation patterns of low‐frequency band in X‐Z plane are similar to that of high‐frequency band in Y‐Z plane. The 10‐dB impedance bandwidths (2.39–2.52 and 4.97–6.07 GHz) meet the WLAN application bands. With the advantages of dimension, cost, and performance, the proposed antenna appears to be a promising candidate for WLAN applications. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26089
Compact CPW‐FED printed monopole antenna with super‐wideband performance
Authors: Akbari Mohammad , Koohestani Mohsen , Ghobadi Changiz. , Nourinia Javad
Published: April 2011

This letter presents a new printed monopole antenna with super‐wideband performance useful for various ultra wideband communication applications. The antenna has a compact structure, and the total size is 24 × 24 × 1.6 mm3. The antenna structure consists of a hexagonal patch radiator with a modified 50 Ω coplanar waveguide line for excitation. By using a trident shaped feed line structure the super wide bandwidth is obtained. Measurement results show that the impedance bandwidth for S11 ≤ −10 dB is enhanced largely to more than 174%. Radiation patterns are given at 4, 6, and 9.5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26090
A simple U‐shaped printed ultra‐wideband antenna with WLAN band rejection
Authors: Mishra Sanjeev Kumar , Gupta Rajiv Kumar , Mukherjee Jayanta
Published: April 2011

In this article, a novel printed ultra‐wideband (UWB) antenna with band stop characteristics is proposed. The proposed antenna is a simple U‐shaped monopole structure where a rectangular strip is placed on both sides at the top of semi annular ring monopole structure. The band rejection characteristic is achieved by introducing a pair of L‐shaped slots in the ground plane to prevent interference due to wireless local area network (WLAN) systems operating within ultra‐wideband. To achieve the desired UWB response with WLAN band notched characteristics, the dimensions of rectangular strip, L‐shaped slot, symmetrical step slot on the both edge of ground plane, a single slot in the center of the ground plane and the gap between the ground plane and the radiating structure are optimized. Frequency rejection characteristics depend on the dimension of L‐shaped slot and can be fine controlled using other parameters. The antenna structure is designed, fabricated and tested. The simulation and measurement results show that the return loss = −10 dB from 3.09 to 10.6 GHz with band stop characteristics in 5.11–6.14 GHz frequency band. The radiation characteristics show its suitability for indoor wireless communication. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26091
Erratum: A novel reconfigurable multiband slot antenna fed by a coplanar waveguide using radio frequency microelectromechanical system switches
Authors: Bemani M. , Nikmehr S.
Published: April 2011

Originally published Microwave Opt Technol Lett 53: 751–757, 2011. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 1685, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26162

(Original article DOI 10.1002/mop.25828)
Approaching What We Hope for and Avoiding What We Fear: A Study of Women's Concern with Visible Signs of Skin Aging
Authors: Sobh Rana
Published: April 2011

This paper proposes to examine how priming approach and avoidance goal orientations moderates consumer goal-directed preferences for products and services. These effects are studied in the context of women's concern with visible signs of facial skin aging and the products, services and activities used to deal with it. Seven hundred female participants from Auckland were randomly assigned to one of the two conditions by receiving one of the two versions of a survey. The final sample was 203 (103 in the approach condition, 100 in the avoidance condition). MANOVA analyses indicated that women are likely to consider different means to deal with aging based on whether they are striving to prevent feared possible selves or to attain hoped-for selves. Underlying mechanisms, implications and future research directions are discussed.
Female genital mutilation in Upper Egypt in the new millennium
Authors: Rasheed Salah M. , Abd‐Ellah Ahmed H. , Yousef Fouad M.
Published: April 2011

Objective

To estimate the influence of the 2007 criminalization law on the prevalence and yearly incidence of female genital mutilation (FGM) in Upper Egypt and assess the attitudes of both the population and their health providers toward FGM.

Methods

Between September 15, 2008, and September 15, 2010, all girls and young women presenting at the Departments of Gynecology and Obstetrics or Pediatrics of Sohag and Qena University Hospitals were invited to answer a questionnaire, which was also presented to their parents. Another questionnaire was presented to all nurses, young physicians, and senior physicians working at either hospital.

Results

The prevalence of FGM was 89.2%. The incidence was 9.6% in 2000, began to decrease in 2006, and had reached 7.7% at the end of the study period in 2009 (P = 0.05). In their vast majority, the procedures were performed by general practitioners. In total, 88.2%, 34.3% and 14.9% of nurses, young physicians, and senior physicians, respectively, approved the practice.

Conclusion

The incidence of FGM is still very high in Upper Egypt in spite of the criminalization law. While general practitioners perform most procedures, most nurses are in favor of preserving the practice.