bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characterization of reactive and stable glucose oxidase‐containing liposomes modulated with detergent
Authors: Yoshimoto Makoto , Wang Shaoqing , Fukunaga Kimitoshi , Walde Peter , Kuboi Ryoichi , Nakao Katsumi
Published: January 2003

Glucose oxidase‐containing liposomes (GOL) as well as detergent‐modulated glucose oxidase‐containing liposomes were prepared and characterized, focusing not only on the reactivity of the liposomes upon external addition of glucose but also on the leakage of the entrapped glucose oxidase (GO) from the liposomes with the aim of developing a reactive and stable liposomal GO system. The membranes of the GOL prepared were composed of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) and modulated with either Triton X‐100 or cholate. In the absence of added detergent, no GO leakage from the GOL was observed while its enzymatic activity was very low (low glucose permeability). As detergent‐modulated liposomes, mixed POPC/Triton X‐100 and mixed POPC/cholate liposomes (abbreviated as TL and CL, respectively) were prepared at different effective detergent/POPC molar ratios (Re) ranging from Re = 0 to Re = Resat (Resat is the critical value of Re at which the liposome membrane is saturated with detergent). The reactivity of GO‐loaded TL (abbreviated as GOTL) or GO‐loaded CL (GOCL) increased drastically with increase in the respective detergent content in the liposomes. In the case of GOTL, at Resat = 0.40, a high reactivity was measured with a simultaneous high extent of GO leakage, suggesting that the observed enzymatic reaction was catalyzed mainly by leaked GO, caused by the interaction of Triton X‐100 with the POPC membrane. On the other hand, GOCL prepared at Resat = 0.43 showed relatively high reactivity with only a small extent of GO leakage, suggesting that most of the enzyme reaction was limited by the glucose permeation across the bilayers of GOCL. The GO leakage from GOCL was found to occur mostly during the rearrangement of the liposomal membrane during the preparation of the GOCL (mixing the GOL and cholate). Fluorescence polarization measurements of membrane‐associated DPH (1,6‐diphenyl‐1,3,5‐hexatriene) indicated that CL prepared by modifying POPC with cholate did not lead to a drastic change in membrane fluidity, indicating that the interacting cholate molecules did not penetrate deeply into the POPC bilayers. In summary, it was clearly shown that the membrane permeability of GOL can be quite simply modulated by mixing it with a certain amount of cholate to form highly reactive and stable GOCL with minimal enzyme leakage. © 2003 Wiley Periodicals. Biotechnol Bioeng 81: 695–704, 2003.
Immobilization of D‐ribulose‐1,5‐bisphosphate carboxylase/oxygenase: A step toward carbon dioxide fixation bioprocess
Authors: Chakrabarti Subhra , Bhattacharya Sumana , Bhattacharya Sanjoy K.
Published: January 2003

Immobilization of D‐ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) from spinach leaves is described. This enzyme enables the fixation of carbon dioxide on a five‐carbon sugar D‐ribulose‐1,5‐bisphosphate (RuBP). Two different immobilization methods were employed: dicyclohexylcarbodiimide coupling on nylon membrane matrix and dimethylpimelimidate immobilization on protein A agarose. The reusability of immobilized enzymes, coupling efficiency, and temperature–activity relationship of soluble and immobilized Rubisco are presented. The immobilization imparted greater thermal and storage stability. The thermal deactivation rates of the immobilized enzymes were considerably lower than those of the soluble enzyme. © 2003 Wiley Periodicals. Biotechnol Bioeng 81: 705–711, 2003.
Propagation of viruses on micropatterned host cells
Authors: Endler Elizabeth E. , Duca Karen A. , Nealey Paul F. , Whitesides George M. , Yin John
Published: January 2003

We have developed a technique to characterize the in vitro propagation of viruses. Microcontact printing was used to generate linear arrays of alkanethiols on gold surfaces, which served as substrates for the patterned culture of baby hamster kidney (BHK‐21) cells. Vesicular stomatitis virus (VSV) was added to unpatterned cell reservoirs adjacent to the patterned cells and incubated, setting in motion a continuously advancing viral infection into the patterned cells. At different incubation times, multiple arrays were chemically fixed to stop the viral propagation. Viral propagation distances into the patterned cells were determined by indirect immunofluorescent labeling and visualization of the VSV surface glycoprotein (G). The infection spread at approximately 50 μm/h in the 140‐μm lines. Moreover, different temporal stages of the infection process were simultaneously visualized along individual lines. These stages included initiation of infection, based on G protein expression; cell–cell fusion, based on virus‐induced clustering of cell nuclei; and cytoskeletal degradation, based on localized release of cells from the surface. This work sets a foundation for parallel, high‐throughput characterization of viral and cellular processes. © 2003 Wiley Periodicals Inc. Biotechnol Bioeng 81: 719–725, 2003.
Stability of protein production from recombinant mammalian cells
Authors: Barnes Louise M. , Bentley Catherine M. , Dickson Alan J.
Published: January 2003

One of the most important criteria for successful generation of a therapeutic protein from a recombinant cell is to obtain a cell line that maintains stability of production. If this is not achieved it can generate problems for process yields, effective use of time and money, and for regulatory approval of products. However, selection of a cell line that sustains stability of production over the required time period may be difficult to achieve during development of a therapeutic protein. There are several studies in the literature that have reported on the instability of protein production from recombinant cell lines. The causes of instability of production are varied and, in many cases, the exact molecular mechanisms are unknown. The production of proteins by cells is modulated by molecular events at levels ranging from transcription, posttranscriptional processing, translation, posttranslational processing, to secretion. There is potential for regulation of stability of protein production at many or all of these stages. In this study we review published information on stability of protein production for three industrially important cell lines: hybridoma, Chinese hamster ovary (CHO), and nonsecreting (NS0) myeloma cell lines. We highlight the most likely molecular loci at which instability may be engendered and indicate other areas of protein production that may affect stability from mammalian cells. We also outline approaches that could help to overcome the problems associated with unpredictable expression levels and maximized production, and indicate the consequences these might have for stability of production. © 2003 Wiley Periodicals Inc. Biotechnol Bioeng 81: 631–639; 2003.
Application of a gratuitous induction system in Kluyveromyces lactis for the expression of intracellular and secreted proteins during fed‐batch culture
Authors: Panuwatsuk Wannana , Da Silva Nancy A.
Published: January 2003

A gratuitous induction system in the yeast Kluyveromyces lactis was evaluated for the expression of intracellular and extracellular products during fed‐batch culture. The Escherichia coli lacZ gene (β‐galactosidase; intracellular) and MFα1 leader‐BPTI cassette (bovine pancreatic trypsin inhibitor; extracellular) were placed under the control of the inducible K. lactis LAC4 promotor, inserted into partial‐pKD1 plasmids, and transformed into a ga1‐209 K. lactis strain. To obtain a high level of production, culture conditions for growth and expression were initially evaluated in tube cultures. A selective medium containing 5 g/L glucose (as carbon source) and 0.5 g/L galactose (as inducer) demonstrated the maximum activity of both β‐galactosidase and secreted BPTI. This level of expression had no significant effect on the growth of the recombinant cells; growth rate dropped by approximately 11%, whereas final biomass concentrations remained the same. In shake‐flask culture, biomass concentration, β‐galactosidase activity, and BPTI secreted activity were 4 g/L, 7664 U/g dry cell, and 0.32 mg/L, respectively. Fed‐batch culture (with a high glucose concentration and a low galactose [inducer] concentration feed) resulted in a 6.5‐fold increase in biomass, a 23‐fold increase in β‐galactosidase activity, and a 3‐fold increase in BPTI secreted activity. The results demonstrate the success of gratuitous induction during high‐cell‐density fed‐batch culture of K. lactis. A very low concentration of galactose feed was sufficient for a high production level. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 712–718, 2003.
Enzymatic hydrolysis of water‐soluble wheat arabinoxylan. 1. Synergy between α‐L‐arabinofuranosidases, endo‐1,4‐β‐xylanases, and β‐xylosidase activities
Authors: Sørensen Hanne R. , Meyer Anne S. , Pedersen Sven
Published: January 2003

Hydrolysis of arabinoxylan is an important prerequisite for improved utilization of wheat hemicellulose in the ethanol fermentation industry. This study investigates the individual and combined efficiencies of three commercial, cellulytic and hemicellulytic enzyme preparations, Celluclast 1.5 L, Ultraflo L, and Viscozyme L, in catalyzing the liberation of arabinose and xylose from water‐soluble wheat arabinoxylan. Ultraflo L was the best enzyme preparation for releasing arabinose, liberating 53 wt% of the theoretical maximum after 48 h of reaction (10 wt% enzyme/substrate ratio, 40°C, pH 6). Celluclast 1.5 L was superior to the other enzyme preparations in releasing xylose, liberating 26 wt% of the theoretical maximum after 48 h of reaction (10 wt% enzyme/substrate ratio, 50°C, pH 5). The 50:50 mixtures of the enzyme preparations showed no synergistic cooperation in arabinose release, but a synergistic interaction in xylose release was found between Ultraflo L and Celluclast 1.5 L. On the basis of high‐performance anion exchange chromatography (HPAEC) analysis of the hydrolysates after enzymatic reaction, we propose that the observed synergism between Celluclast 1.5 L and Ultraflo L is the result of positive interaction between α‐L‐arabinofuranosidase and endo‐1,4‐β‐xylanase activities present in Ultraflo L that released arabinose, xylobiose and xylotriose, and β‐xylosidase activities in Celluclast 1.5 L, capable of catalyzing the hydrolysis of xylobiose and xylotriose to xylose. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 726–731, 2003.
Transglutaminase‐catalyzed synthesis of trypsin–cyclodextrin conjugates: Kinetics and stability properties
Authors: Villalonga Reynaldo , Fernández Michael , Fragoso Alex , Cao Roberto , Di Pierro Prospero , Mariniello Loredana , Porta Raffaele
Published: January 2003

Bovine pancreatic trypsin was modified by the mono‐6‐amino‐6‐deoxy derivatives of α‐, β‐, and γ‐cyclodextrin through a transglutaminase‐catalyzed reaction. The trypsin–cyclodextrin conjugates, containing about 3 mol of oligosaccharide per mole of protein, were tested for their catalytic and stability properties. The specific esterolytic activity and the kinetics constants of trypsin were significantly improved following the transglutaminase‐induced structural modifications. Trypsin–cyclodextrin conjugates were also found markedly (sixfold) more resistant to autolytic degradation at alkaline pH, and their thermal stability profile was improved by about 16°C. Moreover, they were particularly resistant to heat inactivation when treated at different temperatures ranging from 45°C to 70°C for different periods of time. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 732–737, 2003.
Intracellular Ca2+ imaging for micropatterned cardiac myocytes
Authors: Kaji Hirokazu , Takoh Kimiyasu , Nishizawa Matsuhiko , Matsue Tomokazu
Published: January 2003

The patterning of cardiac myocytes on a micron scale (∼5 μm) was achieved by microcontact printing of fibronectin onto a hydrophobically pretreated glass substrate. The patterned cardiac myocytes conjugated with each other by forming a gap junction, as judged from the synchronized Ca2+ transition over the pattern, and thus simultaneously contracted. The dynamic change of the Ca2+ concentration within the patterned tissue was analyzed quantitatively during successive contraction and relaxation using a Nipkow‐type high‐speed confocal microscope. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 81: 748–751, 2003.
Protein phosphatase 2C is involved in the cAMP‐dependent ciliary control in Paramecium caudatum
Authors: Noguchi Munenori , Sasaki Jun‐Ya , Kamachi Hiroyuki , Inoue Hiroshi
Published: January 2003

Forward swimming of the Triton‐extracted model of Paramecium is stimulated by cAMP. Backward swimming of the model induced by Ca2+ is depressed by cAMP. Cyclic AMP and Ca2+ act antagonistically in setting the direction of the ciliary beat. Some ciliary axonemal proteins from Paramecium caudatum are phosphorylated in a cAMP‐dependent manner. In the presence of cAMP, axonemal 29‐ and 65‐kDa polypeptides were phosphorylated by endogenous A‐kinase in vitro. These phosphoproteins, however, were not dephosphorylated after in vitro phosphorylation, presumably because of the low endogenous phosphoprotein phosphatase activity associated with isolated axonemes. We purified the protein phosphatase that specifically dephosphorylated the 29‐ and 65‐kDa phosphoproteins from Paramecium caudatum. The molecular weight of the protein phosphatase was 33 kDa. The protein phosphatase had common characteristics as protein phosphatase 2C (PP2C). The characteristics of the protein phosphatase were the same as those of the PP2C from Paramecium tetraurelia (PtPP2C) [Grothe et al., 1998: J. Biol. Chem. 273:19167–19172]. We concluded that the phosphoprotein phosphatase is the PP2C from Paramecium caudatum (PcPP2C). The PcPP2C markedly accelerated the backward swimming of the Triton‐extracted model in the presence of Ca2+. On the other hand, the PcPP2C slightly depressed the forward swimming speed. This indicates that the PP2C plays a role in the cAMP‐dependent regulation of ciliary movement in Paramecium caudatum through dephosphorylation of 29‐ and/or 65‐kDa regulatory phosphoproteins by terminating the action of cAMP. Cell Motil. Cytoskeleton 54:95–104, 2003. © 2003 Wiley‐Liss, Inc.
Hemidesmosome protein dynamics in live epithelial cells
Authors: Tsuruta Daisuke , Hopkinson Susan B. , Jones Jonathan C.R.
Published: January 2003

Hemidesmosomes mediate stable anchorage of epithelial cells to laminin‐5 in the basement membrane zone and have been likened to spot‐welds. Indeed, it has been assumed that hemidesmosomes are not dynamic, at least when compared to other matrix adhesion sites including focal contacts. We tested this notion by monitoring the fate of green fluorescent protein (GFP)‐tagged human integrin β4 subunit (GFP‐hβ4) and GFP‐tagged 180‐kD human bullous pemphigoid (BP) autoantigen (GFP‐BP180) in live cultures of 804G cells that assemble numerous mature hemidesmosomes. In subconfluent 804G cells, both GFP‐hβ4 and GFP‐BP180 protein clusters are not stable but assemble into and disassemble out of cat paw–like arrays at a relatively rapid rate. In confluent populations of 804G cells, although some cat paw–like clusters of both GFP‐hβ4 and GFP‐BP180 are stable over periods of >60 min, other GFP‐hβ4 and GFP‐BP180 protein arrays form and/or disappear during the same time period. Moreover, individual labeled particles show considerable motility in the plane of the membrane. Fluorescence recovery after photobleaching analyses provide a further indication of the dynamics of hemidesmosome proteins. In particular, bleached GFP‐hβ4 protein clusters in confluent cells recover signal within about 30 min, indicating that there is a relatively rapid turnover of hemidesmosome components in protein arrays clustered along the substratum attached surface of a cell. The rate of recovery is dependent on an intact microfilament system. In sharp contrast, bleached GFP‐BP180 protein clusters in confluent cells fail to recover signal even when observed for longer than 60 min. To evaluate hemidesmosome protein dynamics in motile cells, we monitored GFP‐hβ4 and GFP‐BP180 in 804G cells populating scrape wound sites in vitro. In these migratory cells, which lack mature hemidesmosomes, integrin β4 subunit and BP180 protein clusters progressively assemble and disassemble into linear and cat‐paw arrays. In summary, hemidesmosome protein clusters, like their counterparts in focal contacts, are dynamic. We discuss these results in relation to hemidesmosome functions. Cell Motil. Cytoskeleton 54:122–134, 2003. © 2003 Wiley‐Liss, Inc.
Linked regulation of motility and integrin function in activated migrating neutrophils revealed by interference in remodelling of the cytoskeleton
Authors: Anderson Stephen I. , Behrendt Barbara , Machesky Laura M. , Insall Robert H. , Nash Gerard B.
Published: January 2003

Neutrophils migrate rapidly by co‐ordinating regulation of their β2‐integrin adhesion with turnover of filamentous F‐actin. The seven‐protein Arp2/3 complex regulates actin polymerisation upon activation by proteins of the WASP‐family. To investigate links between actin polymerisation, adhesion, and migration, we used a novel osmotic‐shock method to load neutrophils with peptides: (1) WASP‐WA and Scar‐WA (which incorporate the actin‐ and Arp2/3‐binding regions of WASP and Scar1), to compete with endogenous WASP‐family members; (2) proline rich motifs (PRM) from the ActA protein of L. monocytogenes or from vinculin, which bind vasodilator‐stimulated phosphoprotein (VASP), a regulator of cytoskeleton assembly. In a flow system, rolling‐adherent neutrophils were stimulated with formyl tri‐peptide. This caused rapid immobilisation, followed by migration with increasing velocity, supported by activated β2‐integrin CD11b/CD18. Loading ActA PRM (but not vinculin PRM) caused concentration‐dependent reduction in migration velocity. At the highest concentration, unstimulated neutrophils had elevated F‐actin and were rigid, but could not change their F‐actin content or shape upon stimulation. Scar‐WA also caused marked reduction in migration rate, but WASP‐WA had a lesser effect. Scar‐WA did not modify activation‐dependent formation of F‐actin or change in shape. However, a reduction in rate of downregulation of integrin adhesion appeared to contribute to impaired migration. These studies show that interference in cytoskeletal reorganisation that follows activation in neutrophils, can impair regulation of integrin function as well as motility. They also suggest a role of the Arp2/3 complex and WASP‐family in co‐ordinating actin polymerisation and integrin function in migrating neutrophils. Cell Motil. Cytoskeleton 54:135–146, 2003. © 2003 Wiley‐Liss, Inc.
A study on millimeter‐wave absorber coating for V band and W band
Authors: Soh Tetsu , Hashimoto Osamu
Published: January 2003

In order to realize a coating‐type millimeter wave absorber superior in weather resistance for outside use, the absorption characteristics at 50 to 110 GHz are studied for titanium dioxide and epoxy resin containing carbon particles. It is found that the frequency dependence of the complex relative permittivity of the material doped with 32 phr of titanium dioxide and 1 phr of carbon particles varies almost in parallel with the reflectionless curve and that both the real and imaginary parts tend to decrease as the frequency is increased. It is shown theoretically and experimentally that coating‐type millimeter wave absorbers made to have absorption characteristics of more than 23 dB at the maximum can be obtained at an arbitrary frequency in the 50 to 110 GHz range by simply changing the thickness, and that the frequency range with an absorption of more than 20 dB exceeds 5 GHz. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 52–58, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10017
Transmission performance of reservation ALOHA access schemes with variable length packets
Authors: Umeda Hiroyuki , Tanabe Hidehiko , Hayano Mitsuru
Published: January 2003

We propose a hybrid reservation ALOHA access scheme as an efficient transmission access scheme for variable length packets. A packet group having an integral packet length distribution from 1 to m, where m = 2k for a positive integer k, is divided into a group of m/2‐long fixed length packets and a group of 1 to m/2‐long packets. The fixed length packets become the reservation packets. The remaining packets are transmitted by the ALOHA access scheme. The maximum throughput in this scheme reaches about 0.39. Furthermore, the 2‐multiplexed hybrid ALOHA reservation scheme divides the packet group of packets having packet lengths from 1 to m/2 into m/4‐long fixed length packets and a packet group having packets of lengths of m/4 or less, and transmits the m/4‐long fixed length packets in the second reservation slot and the packets having the remaining lengths in the ALOHA slot to reach a maximum throughput of 0.57. These throughput values are used to study the suitability from the two perspectives of a theoretical analysis and a simulation. Finally, we try to improve the delay performance by assigning a number to the ALOHA slot and efficiently retransmitting the collision packets according to the number table. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 42–51, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10019
A beam pattern selection diversity technique using adaptive array antenna for DS/CDMA cellular systems
Authors: Watanabe Katsumi , Sampei Seiichi , Morinaga Norihiko
Published: January 2003

This paper proposes a beam pattern selection diversity technique using an adaptive array antenna. In the system using an adaptive array antenna, beam control in the uplink is carried out for all terminals in the cell. Hence, it is necessary to determine the antenna weights for all terminals at the base station, so that the amount of computation is increased and the base station configuration becomes complex in a cellular system that seeks to be capable of handling as many terminals as possible. In this paper, the beam patterns are generated only for a limited number of terminals in the cell, while other terminals share the generated radiation patterns, so that the amount of computation can be reduced substantially. In general, in a system using an adaptive array antenna, the interference suppression capability is significantly affected by the angle of arrival of the propagation channel. In this paper, the angle of arrival of the channel is modeled by a normal distribution and the proposed system is investigated in a micro‐cell environment. As a result of numerical simulation, it is found that the proposed method can reduce the processing effort by 20% in the micro‐cell environment, while the characteristics are sufficiently competitive with the results obtained when optimum radiation patterns are generated for all terminals. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 32–41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10020
An influence on radiation characteristics by FSS on a beam‐waveguide feed with FSS
Authors: Miyahara Norio , Mizuno Tomohiro , Matsumoto Soichi , Deguchi Hiroyuki , Urasaki Shuji
Published: January 2003

Dual reflector antennas fed with a beam waveguide are widely used for base stations of satellite communication and for radio astronomy. When the antenna is used at several frequencies, it is effective to carry out diplexing with a frequency selective surface (FSS) in the beam waveguide. Traditionally, when an antenna containing an FSS on the reflector surface is designed, or its radiation characteristics are evaluated, it is assumed that the FSS is ideal and it is modeled by a metal plate or a transparent plate in order to derive the radiation characteristics of the antenna at the frequency range in which the FSS is used for transmission or reflection. Next, the return loss or transmission loss of the FSS alone is derived. This loss has been considered as gain reduction of the radiation characteristics of the antenna with an ideal FSS. However, since the reflection and transmission characteristics of the FSS differ depending on the angle of incidence and polarization angle of the wave incident on the FSS, the radiation pattern of the entire antenna system and that of the wave that is incident on the focusing reflector connected to the FSS are different from those obtained when using a focusing reflector modeled by an ideal FSS. Hence, for accurate design and evaluation of a dual reflector antenna fed by a beam waveguide using an FSS, the effect of the reflection and transmission characteristics of the FSS on the radiation characteristics must be considered in addition to the loss caused by the FSS. This paper studies the effect of the FSS on the radiation characteristics when a dual reflector fed by a beam waveguide with an FSS partially installed is excited by the fundamental mode (EH11) of the primary radiator. For calculation of the electromagnetic field in the beam‐waveguide feed, the beam mode expansion method is used, so that the wave effect is taken into account. For calculation of the reflection and transmission characteristics of the FSS, a simple method is used in which the electromagnetic field scattered by the FSS is expanded in terms of Floquet modes and the electric field on the FSS is determined by the method of moments. Further, in order to reduce the effect on the radiation characteristics resulting from the difference in reflection phase at the metal part and at the FSS, the location of installation of the FSS is offset so that the phase difference of the reflected waves from two regions is compensated. This proposed method is found effective. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 21–31, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10041
Calculation of electric far field radiated from transmission line attached to a ferrite core above a ground plane
Authors: Maekawa Tetsuya , Fujiwara Osamu
Published: January 2003

The use of magnetic materials has drawn attention as a method of simultaneously realizing suppression of electromagnetic (EM) noise radiated from information devices and improvement of the immunity of such equipment against the EM noise from these devices. Suppression effect of the electromagnetic noise radiated from printed circuit boards (PCB) traces and cables by ferrite cores and sheets has been studied. However, little is known about the relationship between the mounting location of the ferrite materials and the noise suppression effect. In this paper, a transmission line on the ground plane for the transverse electromagnetic mode is treated. The radiated field at a sufficient distance relative to the transmission line length is analyzed. It is shown that the field level in this case is proportional to the spatial average value of the current distribution on the transmission line in the length direction and hence that reduction of the field level is possible by suppressing the average value of the current. Next, a computational formula is derived for the field level from the ferrite core‐attached transmission line. Using this formula, the suppression effect of the field level by core attachment is numerically studied. It is found that a suppression effect is recognizable if the ferrite core is installed at the near end of the transmission line. On the other hand, the field level actually increases if the ferrite core is installed at the far end. These numerical results are confirmed to agree well with experimental results obtained in a six‐surface anechoic chamber. Hence, the formula derived in this paper is valid. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 12–20, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.10050
Performance of the delay profile information channel based subcarrier transmit power control technique for OFDM/FDD systems
Authors: Maeda Noriyuki , Sampei Seiichi , Morinaga Norihiko
Published: January 2003

The convolutionally encoded OFDM (Orthogonal Frequency Division Multiplexing) scheme, is an effective approach that is superior in its robustness to frequency‐selective fading and in assuring high transmission quality in a broadband wireless transmission system. However, since the burst length becomes shorter as the transmission speed becomes higher, there are problems of reduced coding gain due to lack of interleaving effect and of increased transmission power with increased bandwidth. These problems are particularly significant in the application to indoor environments in which the demand for high‐speed transmission is high and the Doppler frequency is small. Hence, further improvement of receiver sensitivity and reduction of transmit power are indispensable. In this paper, a subcarrier transmit power control technique is proposed in which the delay profile information estimated using a pilot channel is reported to the message sender and the transmit power is controlled to make the receiving condition for each subcarrier constant based on the obtained delay profile information, so that the receiver sensitivity is improved by transmit power control. Further, the use of PNPA (Partial Non‐Power Allocation), which suppresses excessive transmit power caused by the application of the subcarrier transmit power control, is considered. When the transmission characteristics of the proposed scheme are evaluated by computer simulation, it is confirmed that the error correcting capability can be improved drastically by the proposed scheme and that the transmit power can be reduced substantially. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 72–80, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1163
Performance enhancement and compensation of carrier frequency offset using CRA‐AA for uplink in SDMA system
Authors: Kishiyama Yoshihisa , Nishimura Toshihiko , Ohgane Takeo , Ogawa Yasutaka , Doi Yoshiharu
Published: January 2003

Recently, the Space Division Multiple Access (SDMA) scheme has been proposed to improve channel utilization efficiency. SDMA requires separation and detection schemes in the base station because serious interference develops among all of the users accommodated by the same channel. In this paper, we propose the Channel Response Assisted Adaptive Array (CRA‐AA) that estimates the channel response in the uplink and uses this result to indirectly control the directivity, and compare its performance to those of MMSE adaptive array and joint detection. We also study a scheme to compensate for the carrier frequency offsets generated at each user. We found that CRA‐AA had superior performance in the presence of both fast fading and carrier frequency offsets. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 81–91, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1164
Performance evaluation of all‐optical network with limited‐range wavelength conversion: The case of multiple fibers on a link
Authors: Miyamoto Kentaro , Harai Hiroaki , Murata Masayuki , Miyahara Hideo
Published: January 2003

Network performance is improved by performing wavelength conversions in an all‐optical network. However, performing wavelength conversions entirely by current wavelength conversion techniques is difficult. Although the network performance is improved by having multiple optical fibers on each link, the network cost is inevitably increased. In this paper we propose a layered graph method which can simply describe a routing/wavelength assigning problem of a network with a limited‐range wavelength conversion capability in which a link has multiple fibers, together with an algorithm for routing/wavelength assignment using a hierarchical graph. In addition, the effects of wavelength conversions and multiple fibers and the performance from the cost point of view are studied by simulation. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(5): 92–101, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.1165
Full‐vector finite‐element beam propagation method for three‐dimensional nonlinear optical waveguides
Authors: Fujisawa Takeshi , Koshiba Masanori
Published: January 2003

A full‐vector beam propagation method based on the finite‐element method (VFE‐BPM) for analysis of a three‐dimensional nonlinear optical waveguide is newly developed with all slowly varying electric field components as unknown variables. The derived electric field can be used directly for evaluation of the nonlinear refractive index, so that a nonlinear refractive index directly corresponding to the electric field can be obtained. Various methods are included for improving the performance of the VFE‐BPM such as the edge/nodal hybrid elements for suppressing generation of spurious solutions, the anisotropic perfectly matched layer for prevention of spurious reflection from the analysis domain edges, and an iteration method to relax the step width in the propagation direction. Further, a beam propagation analysis is carried out for spatial soliton emission phenomena in a three‐dimensional nonlinear optical waveguide for performance evaluation of the VFE‐BPM developed here. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 19–27, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10079
Calculation of radiation pattern from nonperiodic dielectric waveguide and synthesis of conical beams
Authors: Kubo Hiroshi , Fukuoka Yasuhiko , Awai Ikuo
Published: January 2003

Synthesis of radiation patterns is carried out by installing many shape variations on the surface of a dielectric rod waveguide. First, an approximate analysis method using a four‐port circuit is presented for calculating the radiation characteristics in a short time. This method for calculation is combined into a genetic algorithm to derive the configuration of the shape variations. Several modifications are used in the genetic reconstruction method in order to adapt the problem to a synthesis of the radiation patterns by the configuration of the shape variations. Synthesis of conical beams with different radiating angles and beam widths is carried out. The radiation characteristics are compared with those by the periodic waveguide structure. In regard to the radiation pattern of a dielectric rod antenna with derived shape configuration, the results by the approximate method and the FDTD (finite difference time domain) method agree well. This is confirmed by experiment. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 9–18, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10084
A 50% duty‐cycle correction circuit for PLL output
Authors: Ogawa Toru , Taniguchi Kenji
Published: January 2003

We proposed a circuit for correcting the fluctuations in the duty cycle caused by the increase in the device fluctuations due to the miniaturization of MOS devices and faster operating speeds. This correction circuit uses feedback control consisting of duty‐cycle detection and correction to correct the fluctuations in the duty cycle of a phase‐locked loop (PLL) circuit produced during the manufacturing process. A prototype of the proposed circuit having a 5‐V power supply voltage was fabricated using a 0.6‐µm process and measured. The variations in the duty cycle of the output voltage for an input signal having 20% to 80% duty cycle fluctuations could be suppressed to 0.21%, which is a 1/300 suppression of the input signal duty cycle fluctuations. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 1–8, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10085
Model‐based speaker normalization methods for speech recognition
Authors: Naito Masaki , Deng Li , Sagisaka Yoshinori
Published: January 2003

A speaker normalization method using a speech generation model is proposed in order to achieve high‐performance speaker adaptation with a small amount of adaptation data. The speaker‐ and phoneme‐dependent vocal tract area function is approximated by the corresponding area function produced by the articulatory model of a standard speaker, combined with phoneme‐independent feature quantities of the vocal‐tract shape of the normalized target speaker as estimated from the formant frequencies of two vowels. The frequency warping functions are determined from the formant frequencies of speech calculated from the vocal‐tract area functions thus obtained, and normalization of the uttered speech is performed by stretching the speech spectrum in the frequency‐axis direction. Continuous phoneme recognition experiments using phoneme connection rules show that the recognition error using a gender‐dependent model is reduced by about 30% in the proposed method and that recognition performance superior to that of vocal‐tract length normalization is obtained. The recognition performance of the proposed method is also equivalent to that of speaker adaptation by moving vector field smoothing (VFS) using 10 phonetically balanced sentences, showing that high‐performance speaker adaptation using a small amount of adaptation data can be achieved by the proposed method. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 45–56, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10119
A DFT method for BIST of RTL data paths based on single‐control testability
Authors: Izutsu Minoru , Wada Hiroki , Masuzawa Toshimitsu , Fujiwara Hideo
Published: January 2003

In this paper, as a built‐in self‐test (BIST) scheme for register transfer level data paths, we will propose a BIST of the test per clock scheme based on hierarchical testing. In this technique, test pattern generators and response analyzers are added only to primary inputs and primary outputs of circuit under test; and for the respective combinational circuit elements, the test patterns and corresponding responses are propagated by using paths on a data path. In this paper, as a data path capable of BIST based on this hierarchical testing, we will define a single‐control testable data path, and propose a design for testability method for changing the design from a given data path to a single‐control testable data path. Moreover, the evaluation of the proposed technique is performed using benchmark circuits. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 84–93, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.10122
Use of a percolation model to analyze the characteristics of a novel scheme for fabricating silicon‐based visible light‐emitting layers by photochemical etching
Authors: Yamamoto Naokatsu , Takai Hiroshi
Published: January 2003

Research focusing on efforts to create visible light‐emitting materials starting with silicon is important to the development of future silicon‐based optoelectronic devices. In this paper, we describe a novel process based on surface photochemical reactions, that is, “photochemical etching,” for fabricating silicon‐based visible light‐emitting materials. We studied the characteristics of visible‐light emission from the photochemically etched layers by observing the photoluminescence excited by a He‐Cd laser, and the structural characteristics of these layers by monitoring their hydrogen content using the method of hydrogen forward scattering. We found that the photochemically etched layers exhibited strong photoluminescence, which could easily be detected by the naked eye in bright ambient light. In this paper we also attempt to qualitatively describe the etching process, using what we refer to as the “inverse percolation model.” This model allowed us to correlate the emission characteristics of the photochemically etched layer with its structural characteristics. By using this percolation‐based model, we were able to investigate the photochemical etching method theoretically, from which we concluded that it can be the basis for an important process that will lead to the fabrication of silicon‐based materials capable of emitting visible light with high emission intensity. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 86(2): 36–44, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.1117
Signal recognition by input‐output correlation in associative neural networks
Authors: Nishimura Haruhiko , Doho Hirotaka , Katada Naofumi
Published: January 2003

Instead of the conventional static memory model based on an associative memory neural network, this paper proposes a dynamic memory model that is extended to the input‐output system in order to allow interaction with external information. Based on the time correlation between the input signal and the network output, we analyze and investigate the network response to stored, nonstored, and mixed stored pattern signals, and the parameter dependencies inherent in the model. The possibility of a new mechanism, the chaotic dynamic model, which discriminates and identifies pattern signal information by combining the dynamic memory model with its extension is shown to be possible. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 54–64, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10022
Numerical verification of nonexistence of solutions for separable nonlinear equations and its application to all solutions algorithm
Authors: Nakaya Yusuke , Oishi Shin'ichi , Kashiwagi Masahide , Kanzawa Yuchi
Published: January 2003

In this paper, the objective is to derive with guaranteed accuracy all solutions of a finite‐dimensional nonlinear equation within a certain range. In order to derive all solutions, it is important to extract efficiently the regions in which no solution exists. A new method is proposed in which nonexistence of solutions in a given region is judged with guaranteed accuracy. By solving specific numerical examples, the effectiveness of the proposed method is verified. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 45–53, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10023
A nonlinear recursive least squares algorithm for crosstalk‐resistant noise canceler
Authors: Umayahara Masaaki , Iiguni Youji , Maeda Hajime
Published: January 2003

In this paper, a method of updating filter coefficients is proposed in which the RLS (Recursive Least Squares) algorithm is applied to a noise canceler with a filter for crosstalk removal. The RLS algorithm has an advantage over the Least Mean Square algorithm by virtue of better convergence. When the filter coefficients are updated including the filter for crosstalk removal, the error signal becomes nonlinear in terms of filter coefficients. Hence, a nonlinear RLS algorithm is derived in which such nonlinearity is taken into account. It is shown that the convergence is further improved in comparison with the conventional RLS algorithm. Finally, a method is proposed to reduce the noise contained in the transmitted voice signals of telephone by means of the present noise canceler and its effectiveness is evaluated. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 36–44, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10039
Watermarking schemes using the addition property among DCT coefficients
Authors: Kuribayashi Minoru , Tanaka Hatsukazu
Published: January 2003

In general, a signal embedded in the low‐frequency components of an image is less likely to be affected by attack. However, there is a problem of substantial degradation of image quality. In particular, if each divided block is processed, the blocking effects generated between adjacent blocks is more easily perceived. In this paper, an embedding method without blocking effects is proposed, making effective use of the superposition of the low‐frequency components in the two‐dimensional DCT basis images. Due to the effect of superposition of the two‐dimensional DCT bases, the watermark information is not detected directly from the block with embedding, but extraction is performed from the subblocks in the block. In the proposed method, in order to provide robustness against geometrical transformation, the synchronization is recovered prior to extracting the watermark information. The robustness can be further enhanced by means of error correcting code. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 11–23, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10048
Vehicle recognition system in infrared images using IMAP parallel vision board
Authors: Kagesawa Masataka , Ueno Shinichi , Ikeuchi Katsushi , Kashiwagi Hiroshi
Published: January 2003

Recently, research on Intelligent Transportation Systems (ITS) has advanced, and its practical application has expanded to the image applications of measuring the traffic flow and detecting unusual events. In this paper, we describe a more advanced vehicle model identification technology, that is, a technology for detecting a particular model (model B of company A). This method does not read license plates or involve communication between the vehicle and the road, but identifies the vehicle model by using only roadside equipment. This algorithm recognizes the model by voting based on the arrangement of local features and has the following characteristics: (1) Detection is possible even if the target vehicle is occluded; (2) There is no dependence on the traveling position of the target vehicle; and (3) The vehicle region does not have to be extracted from the input image. First, we verify the above advantages in outdoor experiments by confirming the ability of the method called the eigenwindow method to recognize a specific model in the traffic flow. Next, we report on the successful improvement in the processing speed without a drop in the recognition accuracy by slightly modifying the implementation and using an image processing board. © 2003 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(5): 1–10, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10065