bluuebunny/crossref_metadata_2025 huggingface dataset:
Genotypic dominance and novel recombinations in HBV genotype B and C co‐infected intravenous drug users
Authors: Chen Bing‐Fang , Kao Jia‐Horng , Liu Chun‐Jen , Chen Ding‐Shinn , Chen Pei‐Jer
Published: March 2004

Pathogenic differences among hepatitis B virus (HBV) genotypes have been documented. However, the interaction between different HBV genotypes remains unclear. Herein, we chose HBV genotypes B (HBV/B) and C (HBV/C) co‐infected intravenous drug users to study this issue. HBV genotype was determined in 40 HBsAg, anti‐HCV, and anti‐HDV co‐positive intravenous drug users by using genotype‐specific primers. The distribution of HBV genotype was as follows: HBV genotype B alone in 29 (72.5%); HBV genotype C alone in 4 (10.0%); and mixed HBV genotype B and HBV genotype C in 7 (17.5%). The interaction between HBV genotype B and HBV genotype C within the same individual was further studied in the seven intravenous drug users with HBV genotype B and HBV genotype C co‐infection. By direct sequencing of the pre‐S region, only HBV genotype B was detected. When 10–21 clones of the pre‐S region were propagated from each intravenous drug user and sequenced, most of the clones were HBV genotype B. Novel recombinations between HBV genotype B and HBV genotype C occurred in four clones (M7‐5, M1‐10, M1‐21, and M1‐24) from two intravenous drug users (M7 and M1). The recombination breakpoints were estimated at nucleotide 3120–3171 for M7‐5, at nucleotide 3060–3191 for M1‐10, and at nucleotide 2910–2950 for M1‐21 and M1‐24 by SimPlot program. The recombination sites of these HBV/pre‐S C‐B and B‐C recombinants may be within the pre‐S1 region. The results in this study suggest that HBV/B is the dominant strain in HBV genotypes B and C co‐infected intravenous drug users in Taiwan, and recombinations between different HBV genotype are not unusual. The impact of recombination on the evolution of HBV and their clinical significance remains to be studied. J. Med. Virol. 73:13–22, 2004. © 2004 Wiley‐Liss, Inc.
Solubility, immunogenicity and physical properties of the nucleocapsid protein of Nipah virus produced in Escherichia coli
Authors: Tan Wen Siang , Ong Swee Tin , Eshaghi Majid , Foo Sze‐Shir , Yusoff Khatijah
Published: March 2004

The nucleocapsid (N) protein of Nipah virus (NiV) can be produced in three Escherichia coli strains [TOP10, BL21(DE3) and SG935] under the control of trc promoter. However, most of the product existed in the form of insoluble inclusion bodies. There was no improvement in the solubility of the product when this protein was placed under the control of T7 promoter. However, the solubility of the N protein was significantly improved by lowering the growth temperature of E. coli BL21(DE3) cell cultures. Solubility analysis of N‐ and C‐terminally deleted mutants revealed that the full‐length N protein has the highest solubility. The soluble N protein could be purified efficiently by sucrose gradient centrifugation and nickel affinity chromatography. Electron microscopic analysis of the purified product revealed that the N protein assembled into herringbone‐like particles of different lengths. The C‐terminal end of the N protein contains the major antigenic region when probed with antisera from humans and pigs infected naturally. J. Med. Virol. 73:105–112, 2004. © 2004 Wiley‐Liss, Inc.
African links and hepatitis B virus genotypes in the Republic of Yemen
Authors: Sallam Talal A. , William Tong C.Y.
Published: March 2004

Hepatitis B virus (HBV) genotypes in three different communities in the Republic of Yemen with and without significant African links were studied. The subjects included indigenous Yemeni blood donors (n = 987), Africans who had settled down in Yemen for several generations (n = 97) and Soqotrans living on an island in the Indian Ocean close to the African coast (n = 99). Phylogenetic analysis of HBV surface region sequences showed the presence of two major genotypes; A and D: sequences from the blood donors were all genotype D (17/17); those from Africans residing in Yemen were predominantly genotype D (7/8) although one sequence was genotype A; whereas a mixture of genotype A and D was found among the Soqotrans (5/8 and 3/8 respectively). Genotype A sequences were associated with higher viral load, but the difference was not statistically significant. Human migration and international travel, may lead to an interaction between HBV genotypes. The Republic of Yemen is at a location where genotypes A and D meet. The results from this study suggest that genotype A is found only in communities with continuing African links and that genotype D remains the dominant genotype in settled populations. More studies are needed to examine possible long‐term changes in HBV genotypes in this region. J. Med. Virol. 73:23–28, 2004. © 2004 Wiley‐Liss, Inc.
Antigenic and molecular analysis of influenza A (H3N2) virus strains isolated from a localised influenza outbreak in South Africa in 2003
Authors: Besselaar Terry G. , Botha Lizelle , McAnerney Jo M. , Schoub Barry D.
Published: March 2004

A severe acute institutional influenza outbreak occurred in a police residential college in Pretoria amongst new recruits and staff members at the end of May 2003. The outbreak was characterised by marked illness which affected a total of 648 students, 26 of whom were admitted to hospital. Symptoms included pyrexia, severe headache, and myalgia. The attack rate per dormitory building ranged from 20 to 47%, with an overall attack rate of 34%. Throat swabs and bronchoalveolar lavage specimens were sent to the National Institute for Communicable Diseases (NICD) from 20 patients. All were positive for influenza A by multiplex PCR and/or indirect immunofluorescence, and were further identified as subtype H3N2. Additional specimens from sporadic influenza cases in Johannesburg and surrounding areas were collected through the NICD active viral surveillance programme for respiratory viral testing and were also positive for influenza A H3N2 viruses. Viruses isolated from patients from both the institutional outbreak as well as from sporadic cases were analysed both antigenically and at the molecular level to determine the characteristics of the influenza strain responsible for the epidemic. The results showed clearly that the outbreak was caused by the introduction in 2003 into South Africa of the novel A/Fujian/411/02‐like H3N2 influenza strain, which is antigenically distinct from the A/Panama/2007/99 vaccine strain. The rapid spread of these variant viruses to the southern hemisphere indicates that the H3N2 component of the influenza vaccine needs to be updated for the 2004 southern hemisphere winter. J. Med. Virol. 73:71–78, 2004. © 2004 Wiley‐Liss, Inc.
Spontaneous and stimulated Raman scattering and infrared spectra of benzil (C14H10O2) crystal: promoting modes of the stimulated effect, anharmonicity and scaling factors of fundamental vibrations
Authors: Hanuza J. , Sa̧siadek W. , Kucharska E. , Michalski J. , Ma̧czka M. , Kaminskii A. A. , Koronienko A. A. , Dunina E. B. , Klapper H. , Hulliger J. , Mohmed A. F. A.
Published: March 2004

Stimulated Raman scattering spectra of benzil (C14H10O2) crystal were measured using picosecond pumping at 300 K. Their lasing components are related to those of polarized IR and spontaneous Raman spectra of an oriented crystal. The nature and assignment of vibrational modes are discussed on the basis of quantum chemical calculations. The B3LYP and MPW1PW91 hybrid functionals that include a mixture of HF and DFT exchange correlation were applied. The results of the chemical quantum calculations were compared with those of normal coordinate analysis performed previously. The role of the anharmonic effects was analyzed and the scaling factors of the vibrational wavenumbers were determined. Copyright © 2004 John Wiley & Sons, Ltd.
Leading for customer service ingenuity
Authors: Bell Chip R. , Bell Bilijack R.
Published: March 2004

How to create value when resources are scarce.
The leader's role in growing new leaders
Authors: Kaye Beverly
Published: March 2004

How successful leaders support the learning and growth of their people.
Rethinking leadership competencies
Authors: Conger Jay A. , Ready Douglas A.
Published: March 2004

Despite their widespread use, leadership competency models are not flawless.
Nanostructured polymer gels
Authors: Hu Zhibing
Published: March 2004

A brief review of our recent work on polymer gel opals is given in memory of late Professor Tanaka. The central idea is to first synthesize monodisperse polymer gel nanoparticles, then self‐assemble them into a 3D network, and eventually covalently bond them. The covalent bonding contributes to the structural stability, while self‐assembly provides them with crystal structures that diffract light, resulting in colors. N‐isopropylacrylamide (NIPA) gel has been used as a model system for this study. The nanostructured NIPA gel, which contain up to 97 wt% water, displays a striking iridescence like precious opal but are soft and flexible like gelatin.
Structural and optical properties of poly(4‐vinyl pyridine)/pyridine gels
Authors: Vaganova Evgenia , Yitzchaik Shlomo
Published: March 2004

A study of photoinduced processes in pyridine‐based gels is presented. Poly(4‐vinyl pyridine) dissolved in pyridine with water addition forms a photosensitive material. Under irradiation at the main absorption at 250 nm, a new intense absorption at 360 nm and an emission at 515 nm appeared. Upon continuation of radiation, together with an increase in the intensity of the new absorption, a prolonged tail through the whole visible range is observed. A new far red‐shifted emission arises in correlation with the absorption spectrum changes. The presence of lower energy aggregates leads to polymer morphology changes. Short‐range aggregates enhance polymer‐polymer interactions. Long range aggregates have a tendency to crystallize. The photoinduced morphology changes was studied by transmission electron microscopy (TEM) of the polymer thin film and differential scanning calorimetry (DSC) of the gel. Phase separated species, micelles‐like forms with domain size over 200 nm, and nanocrystals with average size 20‐30 nm are demonstrated.
Image analysis of the spatial distribution of paramagnetic Pr3+ ions in a polymer gel by a 1H‐chemical shift NMR imaging method
Authors: Yokota Satomi , Sasaki Akitsugu , Hotta Yoshio , Yamane Yuji , Kimura Hideaki , Kuroki Shigeki , Ando Isao
Published: March 2004

1H‐chemical shift NMR imaging patterns of a poly(methacrylic acid) gel containing water with paramagnetic praseodymium ions(Pr3+) were successfully observed, in order to elucidate spatial distribution of Pr3+ ions in the gel. The 1H chemical shift of water associated with Pr3+ ions in the gel moves largely downfield. By analyzing these experimental results, the immersion process of Pr3+ ions into the network of the polymer gel was spatially clarified. Further, it is shown that the chemical shift NMR imaging method is a useful means for determining the spatial distribution of paramagnetic metal ions in polymer gels.
Water diffusion in methacrylate based copolymer hydrogels of 2‐hydroxyethyl methacrylate
Authors: Hill David J.T. , Chowdhury Mohammad , Ghi Phuong Y. , Moss Naomi G. , Whittaker Andrew K.
Published: March 2004

The diffusion of water into cylinders of polyHEMA and copolymers of HEMA with THFMA, BMA and CHMA were studied over a range of copolymer compositions. The diffusion of water into the polymers was found to follow a Fickian, or case I mechanism. The diffusion coefficients of water were determined from mass measurements and NMR imaging studies. They were found to vary from 1.7 ± 0.2 x 10−11 m2 s−1 for polyHEMA at 37°C to lower values for the copolymers. The mass of water absorbed at equilibrium relative to the mass of dry polymer varied from 52‐58 wt% for polyHEMA to lower values for the copolymers.
Ionic strength/temperature‐induced gelation of aqueous poly(N‐isopropylacrylamide‐co‐vinylimidazole) solution
Authors: Yi Jin Woo , Na Kun , Bae You Han
Published: March 2004

A high molecular weight copolymer of N‐isopropylacrylamide (NiPAAm) and vinyl imidazole (VI) was synthesized and its phase transition behavior in aqueous solutions (5 wt%) by simultaneous changes of ionic strength and temperature was investigated. At low ionic strengths, the copolymer solution showed two phases (clear and opaque solutions), which were freely mobile, as increasing temperatures up to 65°C due to repulsion interaction of positive charges developed by basic imidazole group on the polymer aggregates. However, at the physiological condition (I=0.15, T=37°C), four distinctive phases (clear solution, opaque solution, gel and shrunken gel) were observed because of charge shielding effect by added salts. The gel state was stable and maintained from 32°C to 55°C. In particular, the phase transition from opaque solution to gel rapidly occurred by the change in ionic strength (from ∼ 0 to 0.15) at 37°C. This characteristic can be utilized as a liquid embolic agent.
Bioconjugates of smart polymers and proteins: synthesis and applications
Authors: Hoffman Allan S. , Stayton Patrick S.
Published: March 2004

Over the past 20 years we have been deeply involved with the synthesis and applications of stimuli‐responsive polymer systems, especially polymer‐biomolecule conjugates. The work of Toyoichi Tanaka has been a constant inspiration for our work and this article is dedicated to him. This article summarizes the research that we have carried out along with many collaborators on polymer‐protein conjugates. We include conjugates prepared by random polymer conjugation to lysine amino groups, and also those prepared by site‐specific conjugation of the polymer to specific amino acid sites that are genetically‐engineered into the known amino acid sequence of the protein. We describe the preparation and properties of thermally‐sensitive, random conjugates to enzymes and several affinity recognition proteins. We have also prepared site‐specific conjugates to streptavidin. with temperature‐sensitive polymers, pH‐sensitive polymers, and light‐sensitive polymers. The preparation of these conjugates and their many fascinating applications are reviewed in this article.
Characterization of stimuli‐sensitive polymers for biomedical applications
Authors: Yoo Mi Kyong , Seok Won Kyung , Sung Yong Kiel
Published: March 2004

Stimuli‐sensitive polymers were synthesized by copolymerizing varying ratios of N‐isopropyl acrylamide(NIPAAm) and acrylic acid(AAc). The influence of polyelectrolytes on the lower critical solution temperatures(LCSTs) of these temperature/pH sensitive polymers was investigated in the pH range of 2‐12. Polyelectrolyte complexes were prepared by mixing poly(NIPAAm‐co‐AAc) as anionic polyelectrolyte with poly(allyl amine)(PAA) or poly(L‐lysine)(PLL) as cationic polyelectrolytes, respectively. Back titration was performed to determine the pKa values of PAAc in poly(NIPAAm‐co‐AAc) and to study the effect of comonomer ionization on the cloud point temperature. The effect of polyelectrolyte complex formation on the conformation of PLL was studied as a function of temperature by means of circular dichroism(CD). The swelling ratio of poly(NIPAAm‐co‐AAc) hydrogels as a function of pH at various temperature was obtained by measuring the weight of the hydrogels in buffer solutions. The LCSTs of the poly(NIPAAm‐co‐AAc) were strongly affected by pH, polyelectrolyte solutes, AAc content, and charge density. The influence of more hydrophobic PLL as a polyelectrolyte on the cloud point of PNIPAAm/water in the copolymer was stronger than that of poly(allyl amine)(PAA). Indomethacin was loaded into these hydrogels, and controlled release of this molecule from the hydrogel was determined under various temperature and pH conditions using UV/Vis spectrophotometry.
The use of hydrophobic spacers in the development of new temperature‐ and pH‐sensitive polymers
Authors: Licea‐Claveríe A. , Rogel‐Hernández E. , Salgado‐Rodríguez R. , López‐Sánchez J.A. , Castillo L.A. , Cornejo‐Bravo J.M. , Arndt K.‐F.
Published: March 2004

The preparation and characterization of two series of methacrylic acid derivative polymers is described. One series contains aliphatic spacers with one to ten methylene units, while the other series includes an aromatic ring with changes in the position of the acid, as spacer. Both series of polymers were obtained as methoxy‐ester protected acid polymers and as polymers containing free acid groups in different amounts. pH‐sensitive gels and temperature‐sensitive N‐isopropylacrylamide (NIPAAm) copolymers were prepared by using some of the monomeric structures described. The pH of the swelling transition of the gels changed from 3.5 up to 9.0 as a function of the spacer length and type. The lower critical solution temperature (LCST) of NIPAAm copolymers in water was lowered from 33.6°C to 6°C as a function of the co‐monomer content and type. The observed changes in the pH of the swelling transition of gels and in the LCST of NIPAAm copolymers can only be explained if hydrophobic‐hydrophobic and hydrogen‐bonding interactions are considered in connection with the specific chemical structure of the monomers used.
Novel swelling/shrinking behaviors of glucose‐binding hydrogels and their potential use in a microfluidic insulin delivery system
Authors: Siegel Ronald A. , Gu Yuandong , Baldi Antonio , Ziaie Babak
Published: March 2004

Hydrogels based on lightly crosslinked poly(methacrylamidophenylboronic acid‐co‐acylamide) swell monototically at pH 7.4 with exposure to increasing concentrations of glucose. At pH 10 these hydrogels first shrink and then reswell with increasing glucose concentration. A mechanism for these disctinct behaviors is proposed and preliminary results validating this mechanism are presented. A simple microfabricated glucose‐sensitive valve based on this hydrogel is described.
Noradrenaline levels rise significantly in rat arterial grafts at 6 hours postoperatively, and take 48 hours to come down
Authors: Penttilä Heikki , Huttunen Pirkko , Von Smitten Karl , Waris Timo , Ashammakhi Nureddin
Published: March 2004

The aim of this study was to investigate the rate of disappearance of noradrenaline in arterial grafts after their transplanation. Arterial grafts were harvested from AO/Ks:OC strain rats. In each rat, a graft was harvested from the femoral artery and transplanted into the common carotid artery. A contralateral unoperated femoral artery served as control. High‐performance liquid chromatography (HPLC) with electrochemical detection was used to determine the noradrenaline content in grafts and controls. Immediately after grafting, the noradrenaline content was 76% of control value, at 6 h 130% of control value, and at 48 h 4% of control value. The drop in graft noradrenaline content (from 0–48 h) was statistically significant (P = 0.005). The difference between 0‐h, 12‐h, and 24‐h groups was statistically insignificant. Compared to control specimens, grafts contained less noradrenaline after 12 h, and it disappeared almost completely from femoral arterial grafts in rats within 48 h. © 2004 Wiley‐Liss, Inc.
Concept of arteriovenous loupes in high‐risk free‐tissue transfer: history and clinical experiences
Authors: Brüner Simone , Bickert Berthold , Sauerbier Michael , Germann Günter
Published: March 2004

The present study describes the concepts of arteriovenous (A‐V) loupes prior to microsurgical free flap transfer in a selected high‐risk group of patients. A one‐stage concept was employed in 26 patients; 5 patients underwent two‐stage flap transfer. Seven thrombotic occlusions of the A‐V fistula or flap vessels were recorded; 6 patients underwent successful revision. Overall flap survival was 96.8% and compared favorably to reports in the literature. Defect coverage could be achieved in all but one case. It can be concluded from the data that in selected high‐risk patient groups, i.e., following radiation, compound trauma, chronic infection, or multiple comorbidities, the creation of an A‐V fistula prior to flap transfer may facilitate innovative reconstructive solutions. © 2004 Wiley‐Liss, Inc.
Versatility of rectus abdominis free flap for reconstruction of soft‐tissue defects in extremities
Authors: Xing‐Quan Zhang , Shao‐Dong Wang , Qing‐Yu Fan , Bao‐An Ma
Published: March 2004

Rectus abdominis flaps, whose blood supply is mainly provided by superior and deep inferior epigastric vessels, are suitable not only for local transfer but also as free flaps. Based on abundant anastomoses of deep inferior epigastric vessels with other vessels such as superior epigastric vessels, lower intercostal vessels, subcostal vessels, lumbar vessels, superficial epigastric vessels, and superficial and deep iliac circumflex vessels, the rectus abdominis flap may be designed as a vertical flap, transverse flap, or oblique flap. From September 1995–October 2002, 42 free rectus abdominis flaps were transferred to reconstruct a variety of soft‐tissue defects. The size of rectus abdominis flaps ranged from 6–25 cm in length and 5–12 cm in width. The overall success rate was 100% (42 of 42). The donor area was closed directly in 8–10‐cm‐wide flaps, leaving an inconspicuous scar. Larger flaps required skin grafting. After a mean 7‐month (range, 3 weeks–18 months) follow‐up, all flaps have healed uneventfully, and donor abdominal morbidity is minimal. © 2004 Wiley‐Liss, Inc.
Preoperative CT angiography for free fibula transfer
Authors: Karanas Yvonne L. , Antony Anuja , Rubin Geoffrey , Chang James
Published: March 2004

The role of preoperative imaging prior to free fibula flap harvest remains controversial. The standard method of preoperative imaging has been arteriography. However, arteriography is associated with known risks and potential complications to the patient. Alternatives to traditional angiography have been sought to attempt to reduce these risks. CT angiography is a noninvasive imaging modality that can accurately assess the arterial and venous circulation, while providing images equal to those of traditional angiography. CT angiography was used in 7 patients prior to free fibula flap harvest. There were no complications from the CT angiogram or the fibula harvest. We describe our use of CT angiography for vascular imaging of the lower extremity prior to free fibula harvest. © 2004 Wiley‐Liss, Inc.
Comparative experimental study on treatment outcome of nerve transfer, using selective C7 nerve root vs. phrenic nerve
Authors: Xu Jian‐Guang , Gu Yu‐Dong , Wang Huan , Hu Shao‐Nan , Yong Chen Zheng
Published: March 2004

The treatment outcome of nerve transfer using the C7 nerve root or phrenic nerve was compared in a rat experiment. One hundred and twenty SD rats were divided into two groups, one undergoing phrenic nerve transfer to the musculocutaneous nerve, and the other partial ipsilateral C7 (anteriolateral fascicles of the anterior division) to the musculocutaneous nerve. Neurotization outcomes of the two groups were evaluated by comparing the electrophysiologic, histologic, and myophysiologic changes of the biceps muscle. No significant differences were found between parameters from the phrenic nerve transfer group and those from the ipsilateral C7 nerve transfer group. This indicates that the treatment outcome of selective ipsilateral C7 transfer is comparable to that of phrenic nerve transfer. It is the surgery of choice in treating brachial plexus upper‐trunk avulsion accompanied by phrenic nerve injury. © 2004 Wiley‐Liss, Inc.
Infinite phase velocity as the boundary between positive and negative phase velocities
Authors: Lakhtakia Akhlesh , Mackay Tom G.
Published: March 2004

The concept of infinite‐phase velocity (IPV) is shown as the boundary between positive‐ and negative‐phase velocities (PPVs and NPVs). As materials displaying PPV and NPV are physically realizable, we conjecture that this applies IPV materials as well. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 165–166, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20081
A printed high‐gain monopole antenna for indoor wireless LANs
Authors: Luk K. M. , Wong Sai Hoi
Published: March 2004

A printed high‐gain monopole antenna for wireless LAN applications is designed and tested. The meandering line is employed to compress the λ/2 element with phase that is opposite to that of the other constructive elements. The chokes on both sides are employed for reduction of the side lobes. An impedance bandwidth of 4.8 (VSWR ≤ 1.5) and average gain of 4dBi is achieved. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 177–180, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20085
Fixed‐wavelength conversion for contention resolution in optical packet switches
Authors: Li Yi , Xiao Gaoxi , Ghafouri‐Shiraz H.
Published: March 2004

Wavelength conversion (WC) is highly useful for contention resolution in optical packet switches (OPS). However, the immature technology and the high cost of full‐range tunable‐wavelength converters (FTWCs) remain big challenges. We propose a new scheme in OPS where fixed‐wavelength converters (FWCs) instead of FTWCs are used in contention resolution. This scheme is cost‐effective and easier to implement. The performance of the FWC is compared with that of the FTWC. Our simulation results under different scenarios clearly show that the new scheme can achieve a performance comparable to that of the FTWC case, at significantly lower complexity and cost. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 185–187, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20087
Design of an ultra‐low‐noise 1.75‐GHz VCO using InGaP/GaAs HBT technology
Authors: Jeon Sungwon , Lee Sangseol
Published: March 2004

An integrated voltage‐controlled oscillator (VCO) operating at 1.75 GHz is designed using the InGaP/GaAs HBT process. The proposed noise‐removal circuit and FR‐4 substrate structure in this paper show an improved characteristic of phase noise and a smaller VCO dimension, respectively. The frequency‐tuning range of the VCO is about 200 MHz and the phase noise at 120‐KHz offset is −119.3 dBc/Hz. The power consumption of the VCO core is 11.2 mW at 2.8‐V supply voltage and the output power is −2 dBm. The calculated figure of merit (FOM) is 191.7, which shows the best performance, as compared with the previous FET or HBT VCOs. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 196–198, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20090
Improved tunable coplanar waveguide (CPW) bandstop filter
Authors: Her Man‐Long , Wang Yu‐Zhen , Lin Kun‐Ying , Chen Yu‐Wei
Published: March 2004

An improved tunable coplanar waveguide (CPW) bandstop filter, which exhibits good performance, is proposed in this paper. A novel tunable open stub and a useful formula for frequency shift and impedances are also presented. Further, air bridges and a special method of step compensation in the angle bends are employed to overcome differences in the radiation effects as much as possible. From the measured results, a 33% narrower rejection bandwidth with sharper roll‐off was achieved, particularly in comparison to that of the bent filter. An enormous size reduction of 53% was obtained, compared to the conventional open‐stub structure. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 198–200, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20091
Shorted T‐shaped monopole antenna for 2.4/5 GHz WLAN operation
Authors: Su Chih‐Ming , Chen Wen‐Shyang , Cheng Yuan‐Tung , Wong Kin‐Lu
Published: March 2004

A novel dual‐frequency shorted T‐shaped monopole antenna is proposed. The T‐shaped monopole is comprised of two horizontal arms of different lengths, which generate two separate resonant modes for the desired dual‐frequency operation, and one vertical arm is short‐circuited to a ground plane through an inverted‐L strip for good impedance matching. A prototype suited for WLAN operation in the 2.4‐ and 5‐GHz bands for a laptop as an internal antenna is constructed and tested. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 202–203, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20093
Vectorial finite‐element BPM scheme applied to the analysis of optical‐fiber couplers
Authors: da Silva J. P. , Brandão M. L.
Published: March 2004

An efficient finite‐element formulation for dielectric media with transverse anisotropy is applied to the analysis of optical‐fiber couplers. The fibers' cores are curved in parabolic shapes, and between the cores there are index‐matching liquid layers whose refractive index and width are taken as variable parameters. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 204–206, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20094
A low‐conversion‐loss ring‐hybrid mixer using TS‐CMRC circuitry
Authors: Chiu L. , Yum T. Y. , Xue Q. , Chan C. H.
Published: March 2004

This paper presents a new fundamental single‐balanced ring mixer incorporating T‐shaped compact microstrip resonant cells (TS‐CMRCs). The measured minimum single side‐band (SSB) down‐conversion loss of 3.3 dB is achieved for a 10.4‐GHz RF signal and is better than 6 dB from 9.6–11.5 GHz with a 0.1‐GHz IF. In addition, our working prototype demonstrates an excellent linearity response, in which the third‐order intercept point (IP3) is 17 dBm with a spurious free‐dynamic range of more than 55 dB. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 206–209, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20095
MMIC's characterization by very near‐field technique
Authors: Nativel L. , Marchetti M. , Falgayrettes P. , Castagné M. , Gasquet D. , Gall‐Borrut P. , Castel M.
Published: March 2004

This paper shows a method to characterize microwave circuits using a near‐field scanning microscope. Applied on various samples, it shows good resolution and weak disturbance for ICs operating with very common microwave components. Here, it is applied in an industrial surrounding to characterize the Bluetooth CMOS power amplifier. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 209–213, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20096
Theory of polychromatic microwave photons
Authors: Ishii T. Koryu
Published: March 2004

In this paper, the possibility of superluminal speed of polychromatic microwave photons is analytically shown. The analytical results are correlated with previous experimental data. In this theoretical analysis, a generic‐wave equation is used as the basis and the Maxwellian phase‐velocity concept of monochromatic microwave photons is applied to microwave spectra of polychromatic photons. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 213–218, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20097
Broadband frequency filtering and mode matching using finline technology
Authors: Decoopman T. , Mélique X. , Vanbésien O. , Lippens D.
Published: March 2004

Broadband frequency filtering and mode‐matching transition using finline technology for high‐frequency nonlinear electronic applications is proposed. Based on homemade code and full‐wave three‐dimensional electromagnetic simulations, the validity of the concepts are assessed on a prototype aimed at operation between 18 and 26 GHz. Results show that very good performance (less than −0.5 dB for the insertion loss of the taper, as well as a rejection higher than −20 dB for the filtering action) can be maintained over the 30% bandwidth required for future space applications. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 234–237, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20103
Tunable and self‐probed wavelength conversion in an SOA‐based fiber‐ring laser
Authors: Xinliang Zhang , Fan Xu , Junqiang Sun , Deming Liu , Dexiu Huang
Published: March 2004

Tunable all‐optical wavelength converters have been regarded as key opto‐electronic devices in intelligent next‐generation optical networks. A novel scheme for tunable wavelength conversion, based on cross‐gain modulation (XGM) in a semiconductor optical amplifier (SOA)‐based fiber‐ring laser, is proposed. Then, theoretical model for this novel scheme is established. Conversion output characteristics are calculated theoretically and measured experimentally under different conditions. The experimental results coincide with the theoretical results. Tunable wavelength conversion at 2.5 and 10 Gb/s with a 40‐nm tuning range are demonstrated experimentally. Experimental and theoretical studies show that this novel scheme is worthy of further investigation. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 237–241, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20104
Autocrine and paracrine mechanisms regulating primordial germ cell proliferation
Authors: Kawase Eihachiro , Hashimoto Koichiro , Pedersen Roger A.
Published: March 2004

Although several mitogens and survival factors have been previously shown to act on primordial germ cells (PGCs) in culture, it is not clear whether they are responsible for controlling proliferation of PGCs in the embryo. We show here that during their migratory phase, PGCs do not express FGF‐4, FGF‐8, or FGF‐17, but these FGFs are expressed by neighboring cells. Thus, any FGF action on migrating PGCs would appear to be through a paracrine mechanism. We found that after entering into the gonads, PGCs start to express FGF‐4 and FGF‐8. On this basis, we hypothesize that FGF signaling is involved in both a paracrine manner in initiating PGC proliferation during their migration and an autocrine manner in sustaining PGC proliferation after their arrival in the gonads. We then studied the role of soluble stem cell factor (SCF), which acts as a survival factor or a mitogen in culture, to determine whether it interacts with FGFs. We found that SCF has a complex effect on PGC proliferation. On one hand, soluble SCF promoted PGC proliferation synergistically with FGF in the absence of membrane‐bound SCF. Conversely, soluble SCF inhibited FGF‐stimulated proliferation of PGCs in the presence of membrane‐bound SCF. We account for these findings in a model involving regulation of PGC proliferation, in which SCF modulates the response to FGFs. Mol. Reprod. Dev. 68: 5–16, 2004. © 2004 Wiley‐Liss, Inc.
Factors affecting fertilization of porcine oocytes following intracytoplasmic injection of sperm
Authors: Lee Jang‐Won , Yang Xiangzhong
Published: March 2004

The objective of this study was to optimize intracytoplasmic sperm injection (ICSI), and to assess the effects of membrane‐damaged sperm on development of porcine oocytes following ICSI. For optimization of development following the ICSI process, sperm injected oocytes were activated 0.5–1.0 hr after ICSI with 1 × 30 μs pulse of 1.2, 1.7, 2.2, and 2.7 kV/cm DC in experiment 1. After 7‐days of culture ICSI oocytes activated with [×1]2.2 kV/cm produced more blastocyts ([×2]34.4%, P < 0.05) than other treatment groups. In experiment 2, oocytes were activated with 1 × 30 μs pulse of 2.2 kV/cm at either 0, 1.5, 3, or 6 hr after ICSI. Oocytes activated 1.5 hr after [×3]ICSI yielded more blastocysts (27.6%)[M4] than in other treatments. In experiment 3, sperm were briefly exposed to 0.1% Triton X‐100 to induce membrane damage. Live‐dead staining of Percoll‐sorted untreated spermatozoa (frozen‐thawed) used in this study showed that over 96% were “alive” whereas none were “alive” after Triton X‐100 treatment. The rate of development to blastocyst of oocytes injected with Triton X‐100 treated sperm combined with electrical activation (EA) at 1 × 30 μs pulse of 2.2 kV/cm (EA, 40.0%) was the best, when compared with those injected with untreated sperm plus EA (P < 0.05). In experiment 4, the development rate of oocytes to the blastocyst stage ([×5]32.1%) following injection of a sperm head only was not significantly different from that of oocytes injected with whole sperm (31.0%). In conclusion, we found that an intact membrane and tail structures of pig spermatozoa are not essential for embryo development by ICSI, and furthermore, dead porcine spermatozoa, at an early stage of necrosis caused by plasma membrane damage, support better embryo development than do live non‐damaged sperm. Mol. Reprod. Dev. 68: 96–102, 2004. © 2004 Wiley‐Liss, Inc.
A critical state model for sands dependent on stress and density
Authors: Yao Y.P. , Sun D.A. , Luo T.
Published: March 2004

An elastoplastic model for sands is presented in this paper, which can describe stress–strain behaviour dependent on mean effective stress level and void ratio. The main features of the proposed model are: (a) a new state parameter, which is dependent on the initial void ratio and initial mean stress, is proposed and applied to the yield function in order to predict the plastic deformation for very loose sands; and (b) another new state parameter, which is used to determine the peak strength and describe the critical state behaviour of sands during shearing, is proposed in order to predict simply negative/positive dilatancy and the hardening/softening behaviour of medium or dense sands. In addition, the proposed model can also predict the stress–strain behaviour of sands under three‐dimensional stress conditions by using a transformed stress tensor instead of ordinary stress tensor. Copyright © 2004 John Wiley & Sons, Ltd.
Poroplastic modelling of the excavation and ventilation of a deep cavity
Authors: Hoxha D. , Giraud A. , Blaisonneau A. , Homand F. , Chavant C.
Published: March 2004

A plastic deviatoric model with hardening is developed on the basis of geomechanical tests performed in the saturated case on low permeable porous material such as argillite. This model is a generalized Mohr–Coulomb plastic criterion combined with a Drucker–Prager plastic potential and the hardening parameter is the plastic distortion. Three different hardening functions have been introduced on the basis of triaxial tests: an increase of friction angle, a decrease of cohesion after a threshold and a contractancy to dilatancy transition for volumetric plastic strain. This plastic model has been adapted to the partially saturated case. The effective stress is expressed thanks to the equivalent interstitial pressure π. Numerical results are presented for the excavation and monotonous ventilation of a deep cylindrical cavity. A first plastification due to excavation is followed by a second one due to desaturation. The extent of the non‐saturated zone provokes an extent of a plastic zone in the rock mass. Analysis shows that the origin of the plastification can be found in the deviatoric stresses because mean effective stresses are compressive during drying. Copyright © 2004 John Wiley & Sons, Ltd.
A hybrid multicommodity routing algorithm for traffic engineering
Authors: Ouaja Wided , Richards Barry
Published: March 2004

Traffic engineering seeks to route traffic demands in data networks to guarantee certain quality of service (QoS) parameters while efficiently utilizing network resources. MPLS, for example, provides the essential capabilities to achieve this with explicit routing. Finding paths for all the demands which meet QoS requirements is a nontrivial task. Indeed, guaranteeing just bandwidth is known to be 𝒩𝒫‐hard. In this paper, we propose a new complete (exact) algorithm for solving this problem, which is a hybrid that tightly integrates Lagrangian optimization and Constraint Programming search. We evaluate its performance on a set of benchmark tests, based on a large well‐provisioned commercial backbone. The tests involve demand sets of varying size, mostly between 100 and 600 demands. We compare the results with those achieved by several other well‐known algorithms, some complete and some heuristic. This reveals that the hybrid algorithm typically yields the most informative results in the most effective way. It resolves most of the test cases either by finding a solution or by proving infeasibility, each taking only a few seconds. Moreover, the solutions found for solvable problems are provably near‐optimal. The results show, perhaps surprisingly, that the routing task can be difficult even in a very well‐provisioned network. © 2004 Wiley Periodicals, Inc.
Bisectored unit disk graphs
Authors: Nolan John
Published: March 2004

Unit disk graphs form a natural model for cellular radio channel assignment problems under the assumption of equally powerful, omnidirectional transmitters located on a uniform, flat plane. Here, we introduce and give motivation for an extension of this model, namely, sectorization at transmitter sites. We define and analyze properties of one case of sectorization, bisectored unit disk graphs, in particular, investigating properties concerning their chromatic number. Finally, we provide some experimental evidence to draw comparisons between graphs of this model and other classes of graphs. © 2004 Wiley Periodicals, Inc.
Dynamic selection effects in means‐tested, urban school voucher programs
Authors: Howell William G.
Published: March 2004

Much of the controversy surrounding school vouchers, and privatization schemes generally, stems from concerns
about social stratification. This paper identifies the form and magnitude of selection effects in a
means‐tested New York City voucher program. It compares students who applied for vouchers, with the
eligible population of public‐school students; those who initially used vouchers, with those who
declined them; and those who remained in private schools, with those who eventually returned to public
schools. Differences along the lines of ethnicity, residential mobility, mother's education, and income are
observed. In addition, specific aspects of a child's education—parental satisfaction, school uniform
requirements, and larger class sizes—all increased the length of time voucher students remained in private
schools. Throughout the program's life span, however, the largest and most consistent effects revolved around
families' religious identity and practices. © 2004 by the Association for Public Policy Analysis and
Management.
Changes in living arrangements during the late 1990s: Do welfare policies matter?
Authors: Acs Gregory , Nelson Sandi
Published: March 2004

Using data from the 1997 and 1999 National Surveys of America's Families, the authors examine the
consequences of state welfare policies and practices on the living arrangements of low‐income families with
children. Results from a multivariate difference‐in‐difference‐in‐differences model
suggest that more effective collection of child support and family cap policies are correlated with declines in
single parenting and increases in dual parenting. Other policies such as sanctions and special restrictions that
apply to two‐parent families have no clear, consistent association with living arrangements. © 2004 by
the Association for Public Policy Analysis and Management.
Relationship between nucleophilicity/electrophilicity indices and reaction mechanisms for the nucleophilic substitution reactions of carbonyl compounds
Authors: Campodonico Paola , Santos José G. , Andres Juan , Contreras Renato
Published: March 2004

Theoretical electrophilicity and nucleophilicity scales, defined in terms of electronic reactivity indices, were tested for the reaction of a series of carbonates with neutral and charged reagents of varying nucleophilicity. The electrophilicity and nucleophilicity scales were used to rationalize some mechanistic aspects developed by these reacting systems: the greater the electrophilicity/nucleophilicity difference, the more concerted the reaction mechanism will be. Conversely, a small electrophilicity/nucleophilicty gap will in general be associated with a stepwise reaction mechanism. Copyright © 2004 John Wiley & Sons, Ltd.
Mutual relationships between magnetic aromaticity indices of heterocyclic compounds
Authors: Sadlej‐Sosnowska Nina
Published: March 2004

For three sets of aromatic compounds, namely various five‐membered heterocycles, derivatives of 2H‐tetrazole and six‐membered heterocycles, a number of the aromaticity indices, especially magnetic ones, were calculated. The tables of correlation coefficients between the individual indices revealed that mutual relationships between them depend on their composition in the set and that some magnetic characteristics themselves may be orthogonal to others. Copyright © 2004 John Wiley & Sons, Ltd.
Concave reagents: Part 40—The copper(II) complex of a concave reagent as a selective catalyst for ester methanolysis
Authors: Cacciapaglia Roberta , Di Stefano Stefano , Fahrenkrug Frank , Lüning Ulrich , Mandolini Luigi
Published: March 2004

We have shown that the CuII complexes of the concave ligand 1 and its model compound 2 are efficient catalysts of ester methanolysis under conditions close to neutrality. Turnover catalysis without product inhibition was demonstrated by the clean first‐order release of a greater than stoichiometric amount of product. Compared with background methanolysis, the metal catalysts give greater rate accelerations for methyl acetate methanolysis than for the p‐nitrophenyl acetate methanolysis.

Analysis of electronic and steric effects on rates of metal‐mediated vs metal‐free methoxide addition to the esters has provided compelling evidence that transfer of methoxide from the metal to the carbonyl carbon is accompanied by extensive Lewis acid activation of the carbonyl via a four‐membered chelate transition state that includes the metal ion. Copyright © 2004 John Wiley & Sons, Ltd.
Microscopic entropy
Authors: Karpov E. , Ordonez G. , Petrosky T. , Prigogine I.
Published: March 2004

We have obtained a microscopic expression for entropy in terms of ℋ︁ function based on nonunitary Λ transformation that leads from the time evolution as a unitary group to a Markovian dynamics and unifies the reversible and irreversible aspects of quantum mechanics. This requires a new representation outside the Hilbert space. In terms of ℋ︁, we show the entropy production and the entropy flow during the emission and absorption of radiation by an atom. Analyzing the time inversion experiment we emphasize the importance of precollisional and postcollisional correlations, which break the symmetry between incoming and outgoing waves. We consider the influence of spatial configuration of the system on the initial correlations in terms of the ℋ︁ function in a three‐dimensional situation. In a subsequent paper we discuss a model including virtual transitions. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004