bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of chiral liquid‐crystalline polyesters containing sugar‐based diols via melt polymerization
Authors: Lin Qin , Pasatta Jeremy , Long Timothy E.
Published: July 2003

Liquid‐crystalline (LC) polyesters based on hexanediol or butanediol, dimethyl 4,4′‐biphenyldicarboxylate, and a sugar‐based diol, isosorbide or isomanide, were prepared with conventional melt polymerization. 1H NMR spectroscopy confirmed that 50 mol % of the charged sugar diol was successfully incorporated into various copolyesters. Modest molecular weights were obtained, although they were typically lower than those of polyester analogues that did not contain sugar‐based diols. Thermogravimetric analysis demonstrated that the incorporation of isosorbide or isomanide units did not reduce the thermal stability in a nitrogen atmosphere. Melting points that ranged from 190 to 270 °C were achieved as a function of the copolyester composition. The lined focal conic fan textures, typical indications of a chiral smectic C LC phase, were observed upon the shearing of the LC melt under polarized light microscopy. Atomic force microscopy revealed that the twisted molecular orientation in the chiral LC phase induced periodically soft lamellar structures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2512–2520, 2003
The fast and the curious: High‐throughput experimentation in synthetic polymer chemistry
Authors: Hoogenboom Richard , Schubert Ulrich S.
Published: July 2003

The application of automated synthetic parallel methods in polymer chemistry is described. A brief overview of all different polymerization techniques that have been used is provided. Furthermore, the equipment and methodologies that were used in our approach for automated parallel polymerization reactions are discussed followed by detailed insight into recent developments on automated cationic ring‐opening polymerization, atom transfer radical polymerization, and emulsion polymerizations. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2425–2434, 2003
Diffusion coefficients of the monomer and oligomers in hydroxyethyl methacrylate
Authors: Strauch Jelica , McDonald James , Chapman Bogdan E. , Kuchel Philip W. , Hawkett Brian S. , Roberts G. Evan , Tonge Matthew P. , Gilbert Robert G.
Published: July 2003

The diffusion coefficients are reported of rubbery ternary systems consisting of the polymer, its monomer analogue (i.e., the saturated equivalent of the monomer), and trace quantities of oligomers (dimer, trimer, tetramer and hexamer) for 2‐hydroxyethyl methacrylate (HEMA). These have been obtained with pulsed‐field‐gradient NMR spectroscopy with a polymer weight fraction (fp) of 0 ≤fp≤ 0.4. The oligomers are macromonomers synthesized with a cobalt catalytic chain‐transfer agent. The diffusion coefficients are about an order of magnitude smaller than those for monomers such as methyl methacrylate; this effect is ascribed to hydrogen bonding in HEMA. The diffusion coefficientDiof ani‐meric oligomer has been fitted with moderate accuracy by an empirical universal scaling relation,Di(fp)/D1(fp) ≈i, previously found to provide an adequate fit to corresponding data for styrene and for methyl and butyl methacrylates. The approximate empirical scaling relation seems to hold for a remarkably wide range of types of monomer/polymer systems. These results are of use in modeling rates and molecular weight distributions in free‐radical polymerization, particularly for termination (which is chain‐length‐dependent and is controlled by the diffusion coefficient of chains of the low degrees of polymerization studied here). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2491–2501, 2003
13Carbon nuclear magnetic resonance of ethylene–propylene–1‐decene terpolymers
Authors: Escher Fernanda F. Nunes , Galland Griselda Barrera , Ferreira Márcio
Published: July 2003

Many studies have been reported on the 13C NMR characterization of ethylene–α‐olefin copolymers, but only a few have been reported on terpolymers. The incorporation of an α‐olefin into the polyethylene chain changes the structure and, consequently, the properties of the polymer obtained. Looking for new products, we obtained a series of ethylene–propylene–1‐decene terpolymers with the metallocenic system rac‐ethylene bisindenyl zirconium dichloride/methylaluminoxane. We performed a complete 13C NMR characterization of these terpolymers qualitatively and quantitatively. Here we present a detailed study of the 13C NMR chemical shifts, triad sequence distributions, monomer average sequence lengths, and reactivity ratios for these terpolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2531–2541, 2003
Graftlike interpolymer complexes from poly(2‐vinylpyridine) and end‐sulfonic acid polystyrene and polyisoprene: Intermediates to noncovalently bonded block copolymer‐like micelles
Authors: Orfanou Katerina , Topouza Dimitra , Sakellariou George , Pispas Stergios
Published: July 2003

The complexation between narrow molecular weight distribution poly(2‐vinylpyridine) (P2VP) and polystyrene (suPS) or polyisoprene (suPI) end‐functionalized with one sulfonic acid group was examined in tetrahydrofuran dilute solutions by a combination of static and dynamic laser light scattering. Both apparent weight‐average molecular weight (Mw,app) and hydrodynamic radius (Rh) of the complexes exhibited a maximum at a certain molar ratio of suPS chains to P2VP monomeric units. This indicated that the P2VP backbone may be saturated by the grafted end‐functionalized chains because of repulsion between the grafted chains. By changing the molar mass of P2VP from 100,000 to 30,000 g/mol, the values of Mw,app and Rh decreased. When suPI was used instead of suPS, similar trends were observed. In the latter case, it was possible to prepare block copolymer‐like micelles by transferring the P2VP/suPI blend solutions in decane, which is a selective solvent for PI. The non‐covalent‐bonded polymeric micelle characteristics were investigated as a function of sulfonic acid/2‐vinylpyridine units ratio as well as temperature. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2454–2461, 2003
Synthesis and characterization of phthalazinone containing poly(arylene ether)s via a novel N–C coupling reaction
Authors: Wang S. J. , Meng Y. Z. , Tjong S. C. , Hlil A. R. , Hay A. S.
Published: July 2003

High‐molecular‐weight poly(phthalazinone)s with very high glass‐transition temperatures (Tg's) were synthesized via a novel N–C coupling reaction. New bisphthalazinone monomers (7a–e) were synthesized from 2‐(4‐chlorobenzoyl) phthalic acid in two steps. Poly(phthalazinone)s, having inherent viscosities in the range of 0.34–0.91 dL/g, were prepared by the reaction of the bis(phthalazinone) monomers with an activated aryl halide in a dipolar aprotic solvent in the presence of potassium carbonate. The poly(phthalazinone)s exhibited Tg's greater than 230 °C. polymer 8b synthesized from diphenyl biphenol and bis(4‐flurophenyl) sulfone demonstrated the highest Tg of 297 °C. Thermal stabilities of the poly(phthalazinone)s were determined by thermogravimetric analysis. All the poly(phthalazinone)s showed a similar pattern of decomposition with no weight loss below 450 °C in nitrogen. The temperatures of 5% weight loss were observed to be about 500 °C. The poly(phthalazinone)s containing 4,4′‐isopropylidenediphenol and 4,4′‐(hexafluoroisopropylidene) diphenol and diphenyl ether linkage were soluble in chlorinated solvents such as chloroform. Other poly‐(phthalazinone)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(phthalazinone)s can be cast as flexible films from solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2481–2490, 2003
Synthesis of conjugated copolymers containing phenothiazinylene vinylene moieties and their electrooptic properties
Authors: Han Yoon Soo , Kim Sang Dae , Park Lee Soon , Kim Dong Uk , Kwon Younghwan
Published: July 2003

Four different types of conjugated copolymers, consisting of alternating structures of phenothiazinylene vinylene and phenylene vinylene derivatives such as phenylene vinylene, 1,1′‐biphenyl‐4,4′‐ylene vinylene, 2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene, and 9,10‐anthrylene vinylene, were prepared by Horner–Emmons condensation between appropriate diphosphonates and dialdehydes. Single‐layer and double‐layer light‐emitting diodes were fabricated with the synthesized conjugated polymers, and their electroluminescent properties were investigated. Poly(N‐2‐ethylhexyl‐3,6‐phenothiazinylene vinylene‐alt‐9,10‐anthrylene vinylene), containing phenothiazinylene vinylene and anthrylene vinylene as repeat units, emitted a reddish‐orange color with Commission Internationale de l'Eclairage coordinates of x = 0.6173 and y = 0.3814 that was very similar to the National Television System Committee standard red, and it showed a bipolar carrier‐injection/transporting capability caused by electron‐withdrawing anthracene and electron‐donating amino groups. Poly[N‐2‐ethylhexyl‐3,6‐phenothiazinylene vinylene‐alt‐2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylene vinylene], containing phenothiazinylene vinylene and dialkoxy phenylene vinylene moieties, showed excellent hole‐injection/transporting capability. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2502–2511, 2003
Liquid‐crystalline thermosets by the curing of dimeric liquid‐crystalline epoxyimine monomers with 2,4‐toluene diisocyanate
Authors: Ribera David , Serra Angels , Mantecón Ana
Published: July 2003

We studied the curing processes of several series of dimeric liquid‐crystalline epoxyimine monomers with 2,4‐toluene diisocyanate (TDI) alone or with added catalytic proportions of 4‐(N,N‐dimethylamino)pyridine. We obtained isotropic materials or liquid‐crystalline thermosets with different degrees of order, which depended on the structures of the monomers. To fix ordered networks, we had to do the curing in two steps when TDI was used alone as the curing agent. However, when a tertiary amine was added in catalytic proportions, the ordered networks were fixed in just one step. In this way, we were able to fix both nematic and smectic mesophases. The significance of the polarization of the mesogen for obtaining liquid‐crystalline thermosets was demonstrated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2521–2530, 2003
Synthesis and characterization of crosslinked uniform polymeric microspheres containing a polyimide prepolymer by a new emulsification process
Authors: Ma Guang‐Hui , Fujiwara Junichiro , Su Zhi‐Guo , Omi Shinzo
Published: July 2003

A highly crosslinked poly(styrene–divinyl benzene–trimethyolpropane trimethacrylate) microsphere containing a polyimide prepolymer (PIP) was prepared by a new emulsification method, Shirasu porous glass (SPG) membrane emulsification, and a subsequent radical suspension polymerization. That is, a mixture of styrene, divinyl benzene, trimethyol propane trimethacrylate (TMPTMA), and PIP containing an initiator was permeated through the uniform pores of the SPG membrane into a continuous phase containing a stabilizer to form uniform droplets. Then, the suspension polymerization was carried out at 65 °C for 24 h. The trifunctional crosslinker TMPTMA was added to enhance the destructive strength of the microsphere, and PIP was incorporated into the microsphere to provide an adhesion force by a known self‐curing reaction at 220 °C. The effects of the feed amounts of TMPTMA and PIP on the monomer conversion, size distribution, and destructive strength of the microsphere were investigated. The monomer conversion increased with an increase in TMPTMA. The particle size distribution became narrower as the TMPTMA feed amount increased, but it became broader with an increase in PIP. The destructive strength increased with increases in TMPTMA and PIP. After a heat treatment at 220 °C, the destructive strength decreased because of the heat degradation of the polymer. The addition of TMPTMA suppressed the heat degradation, and PIP could undergo self‐curing at 220 °C. The obtained highly crosslinked uniform microsphere containing PIP has potential applications in liquid‐crystal displays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2588–2598, 2003
Self‐curable polyester by a reaction of glycidol with maleic anhydride
Authors: Bicak Niyazi , Karagoz Bunyamin , Tunca Umit
Published: July 2003

The controlled reaction of equimolar quantities of maleic anhydride and glycidol in dimethoxyethane gives soluble polyesters with one hydroxyl group in each repeating unit. The reaction proceeds with stepwise ring opening of the components and gives highly viscous clear solutions in relatively short periods. In the first step, monomaleate ester formation takes place around 80 °C. The ring opening of the oxirane group is the second step, and it occurs at 120 °C. The overall reaction is the formation of soluble polyesters with moderate molecular weights (6000–18,000), without the elimination of water. The soluble polyesters can be crosslinked tightly by direct heating at 190 °C without additional vinyl monomer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2549–2555, 2003
Synthesis of miktoarm star and miktoarm star block copolymers via a combination of atom transfer radical polymerization and stable free‐radical polymerization
Authors: Celik Cigdem , Hizal Gurkan , Tunca Umit
Published: July 2003

A trifunctional initiator, 2‐phenyl‐2‐[(2,2,6,6‐tetramethyl)‐1‐piperidinyloxy] ethyl 2,2‐bis[methyl(2‐bromopropionato)] propionate, was synthesized and used for the synthesis of miktoarm star AB2 and miktoarm star block AB2C2 copolymers via a combination of stable free‐radical polymerization (SFRP) and atom transfer radical polymerization (ATRP) in a two‐step or three‐step reaction sequence, respectively. In the first step, a polystyrene (PSt) macroinitiator with dual ω‐bromo functionality was obtained by SFRP of styrene (St) in bulk at 125 °C. Next, this PSt precursor was used as a macroinitiator for ATRP of tert‐butyl acrylate (tBA) in the presence of Cu(I)Br and pentamethyldiethylenetriamine at 80 °C, affording miktoarm star (PSt)(PtBA)2 [where PtBA is poly(tert‐butyl acrylate)]. In the third step, the obtained St(tBA)2 macroinitiator with two terminal bromine groups was further polymerized with methyl methacrylate by ATRP, and this resulted in (PSt)(PtBA)2(PMMA)2‐type miktoarm star block copolymer [where PMMA is poly(methyl methacrylate)] with a controlled molecular weight and a moderate polydispersity (weight‐average molecular weight/number‐average molecular weight < 1.38). All polymers were characterized by gel permeation chromatography and 1H NMR. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2542–2548, 2003
Photoinduced and thermally induced cationic polymerizations using S,S‐dialkyl‐S‐(3,5‐dimethylhydroxyphenyl)sulfonium salts
Authors: Crivello James V. , Ahn Jinseo
Published: July 2003

A study of the photoinitiated and thermally initiated cationic polymerizations of several monomer systems with S,S‐dialkyl‐S‐(3,5‐dimethylhydroxyphenyl)sulfonium salt (HPS) photoinitiators bearing different lengths of alkyl chains on the positively charged sulfur atom has been conducted. HPS photoinitiators are capable of photoinitiating the cationic polymerization of a wide variety of epoxy and vinyl ether monomers directly on irradiation with short‐wavelength UV light. Aryl ketone photosensitizers are effective in extending the spectral response of these photoinitiators into the long‐wavelength UV region. Kinetic studies with real‐time infrared spectroscopy show that HPS photoinitiators exhibit good efficiency in the polymerization of epoxide and vinyl ether monomers. Comparative studies also demonstrate that S,S‐dimethyl‐S‐(3,5‐dimethyl‐2‐hydroxyphenyl)sulfonium salts are more active photoinitiators than their isomeric S,S‐dimethyl‐S‐(3,5‐dimethyl‐4‐hydroxyphenyl)sulfonium salt counterparts. Both types of HPS photoinitiators display reversible photolysis as a result of facile termination reactions that take place between the growing chains ends with the photogenerated sulfur ylides. Preliminary studies have shown that HPS photoinitiators can also be employed as thermal initiators for the cationic ring‐opening polymerization of epoxides at moderate temperatures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2570–2587, 2003
Synthesis and characterization of second‐generation S,S‐dialkyl‐S‐(dimethylhydroxyphenyl)sulfonium salt photoinitiators
Authors: Crivello James V. , Ahn Jinseo
Published: July 2003

A new, simplified method has been developed for the synthesis of S,S‐dialkyl‐S‐(dimethylhydroxyphenyl)sulfonium salt cationic photoinitiators. This novel method has successfully been used for the preparation of S,S‐dialkyl‐S‐(3,5‐dimethyl‐4‐hydroxyphenyl)sulfonium and S,S‐dialkyl‐S‐(3,5‐dimethyl‐2‐hydroxyphenyl)sulfonium salts showing a wide variation in the length and structure of the alkyl chains on the positively charged sulfur atom. These photoinitiators can also be prepared with a wide variety of different anions. The manipulation of the lengths of the alkyl chains permits the design of compatible photoinitiators for highly nonpolar monomers and oligomers such as epoxy‐functional silicones, epoxidized polybutadiene, and epoxidized vegetable oils. This article describes the synthesis and characterization of these photoinitiators. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2556–2569, 2003
Automatic recognition of wild flowers
Authors: Saitoh Takeshi , Kaneko Toyohisa
Published: July 2003

In this paper we propose an automatic recognition system for wild flowers. Two photos, one of the flower and one of the leaves taken from directly above or at a close angle of a single wild flower, were used as a single set. The objective (flower, leaf) is extracted from each image using a clustering method, then recognition is performed using a piecewise linear discriminant function after finding 10 features in the picture of a flower and 11 features in the picture of a leaf. We performed experiments on 20 sets of 34 species of wild flowers that grow around our university campus in the spring and early summer. The results of the experiment showed a recognition rate of 96.0% when all of the features (21) were used. Next we performed an experiment to select the features particularly useful for recognition. These results showed that six features for the pictures of flowers and two features for the pictures of leaves were the most effective, and with them a recognition rate of 96.8% could be reached. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 90–101, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10099
Fast line extraction from digital images using line segments
Authors: Kim Euijin , Haseyama Miki , Kitajima Hideo
Published: July 2003

This paper presents a fast line extraction method using the line segments found in digital images. A digital line can be decomposed into line segments, which consist of continuous edge pixels, in four directions. The directions of the line segments are varied and limited by the relationship between the line segments and the slopes of analog lines. The proposed method attains high speed and accuracy by tracking each line segment in the same direction which comes from the relationship. Experimental results are included to show that the proposed method can achieve high accuracy with a large reduction in the computation time and has robustness in the presence of noise. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 76–89, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10124
Time series prediction by a neural network model based on bi‐directional computation style: A study on generalization performance with the computer‐generated time series “Data Set D”
Authors: Wakuya Hiroshi , Shida Katsunori
Published: July 2003

The principal goal of time series prediction is the enhancement of prediction accuracy. To achieve this goal, most previous investigations have adopted the so‐called uni‐directional computation style, focusing only on the forward‐time direction (present→future). This paper adopts a different approach, the bi‐directional computation style, and applies it to real‐time series prediction tasks. The objective of this style is to improve the accuracy of time series prediction by means of interaction between the forward‐time direction processing system, which only predicts the future, and a separate backward‐time processing system. Good results have previously been obtained on sunspot data, but since these involve time series that are short, there has been insufficient investigation of generalization performance. We therefore apply the proposed technique to different time series data in order to investigate further the generalization performance with untraining data. The time series data called “Data Set D” used here were artificially generated by a computer and are distinguished by their great length, consisting of 100,000 points. Computer simulations indicate that on average, an improvement in dealing with untraining data equal to that for training data is achievable. In addition, better prediction accuracy is achieved in areas where the conventional method is weak. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 64–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10264
Knowledge from the time series of quasar radio‐wave flux density
Authors: Tanizuka Noboru , Rahman Khan Md. Mostafizur
Published: July 2003

Time series of radio waves attributable to synchrotron radiation from quasars, that is, extragalactic systems at cosmological distances, were analyzed in an attempt to find an informational structure expressing the evolution and self‐organization of the quasar system. The methods we used were power law analysis of the time series and phase space map analysis of the reconstructed time series.

From the power law analysis we found that the dynamical structure of the system is likely to have evolved over the cosmic time scale. From the reconstructed phase space map analysis we obtained patterns similar to attractors in three‐dimensional phase space, which may reflect the system's dynamical structure, and by applying the GP algorithm with the correlation integral we inferred that the dynamical system is of system dimension. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 56–63, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10366
Development of 3D graphics and VRML libraries for Web3D platform by using Java
Authors: Chen Bing‐Yu , Nishita Tomoyuki
Published: July 2003

This paper proposes a new 3D graphics programming environment for Web3D on the Internet. To develop 3D graphics programs on the Internet is not easy because there is no popular 3D graphics library like OpenGL. For this purpose, we developed a 3D graphics library called jGL by using Java exclusively. jGL is a general‐purpose 3D graphics library, and its API (Application Programming Interface) is defined in a manner quite similar to that of OpenGL. Since jGL offers the same functionalities as OpenGL, programmers can use it easily. Furthermore, since people have recently been able to use simple Java programs on cellular phones, migration experimentation toward i‐αppli is also described in this paper. Moreover, VRML (Virtual Reality Modeling Language) is a standard file format for describing 3D models on the Internet. To display a 3D model on the Internet, people may like to use the VRML file format. Therefore, we also developed a VRML library called jVL by using Java exclusively as an extension of jGL. In this paper, the results and some detailed descriptions are updated compared with those in Ref. 3. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 47–55, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10393
A visualization system for making choice of electronic bulletin board system
Authors: Abe Michiko , Sato Kiwamu , Ogasawara Naohito , Nunokawa Hiroshi , Noguchi Shoichi
Published: July 2003

To post questions or opinions to an electronic bulletin board system on the Internet, it is important for a contributor to find the most appropriate electronic bulletin board system. Posting a contribution to an irrelevant electronic bulletin board system may cause such problems as “no accurate answer arrives” or “follow‐up contributions cannot be easily attached.” However, since the Internet contains massive electronic bulletin board systems that include enormous numbers of diverse kinds of articles, it is extremely difficult to find the most appropriate electronic bulletin board system. Therefore, the aim of this research is to construct a system that extracts and visualizes information related to articles that are posted to an electronic bulletin board system and information related to contributors so that a user can easily and intuitively solve this kind of problem. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 36–46, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10408
Face recognition with Zernike moments
Authors: Ono Atsushi
Published: July 2003

In recent years, considerable research has been performed on technology for verifying individual identity using human biometrics. In particular, verification technology using facial images has been extensively researched. This is because special input devices are not needed, and there is little of the psychological resistance that is found with fingerprint input. In this paper, the author proposes a method for recognition using the subspace method, and using the Zernike moment, a moment that is invariable during rotation, as a feature vector. The validity of the method is then shown. In addition, the author confirms through experiments the relationship between the circle width of the circular Zernike moment and the recognition rate, as well as between the order of the Zernike moment and the recognition rate. Furthermore, the recognition capacity of each circle is described, and experiments are performed on variations in the recognition rate when the circle with the lowest recognition capacity is eliminated. Finally, experiments comparing the author's approach to other methods are performed. The author shows that equivalent recognition results can be obtained using the Zernike moment as a feature vector whose order is far lower than other feature vectors. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 26–35, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10414
Relaxed conditions of exchange on mechanism for exchanging parts of executed program
Authors: Yamamoto Atsushi , Taniguchi Hideo
Published: July 2003

We proposed a control method for exchanging parts of an executing program. By applying this exchange method to a shared library that is linked dynamically, the contents of library functions that constitute the program can be changed without stopping processes that are providing services. In other words, maintenance tasks can be dynamically performed without suspending the services that are being provided. However, the program parts that are exchanged according to the proposed exchange method must satisfy strict exchange conditions, making it difficult to create program parts that are to be exchanged. Therefore, in this paper, we describe an exchange method in which the exchange conditions have been relaxed. Also, we point out a problem in which relaxing the exchange conditions causes the exchanging time to be significantly increased when exchanging parts for a program that is mainly a CPU‐bound program compared with a program that is mainly an I/O‐bound program. Then, to deal with this problem, we propose methods of devising process scheduling mechanisms to shorten the exchanging time. Specifically, we show a mechanism that temporarily suspends exchangeable processes early and a mechanism that preferentially executes unexchangeable processes. In addition, we implement and evaluate both of these mechanisms and show the effectiveness of each mechanism. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 13–25, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10423
A study on iterative video coding rate–distortion optimization and its rate control
Authors: Takamura Seishi , Kobayashi Naoki
Published: July 2003

Encoding a video clip with as large a compression ratio as possible within a framework of established standards is a key technology for digital TV broadcasting, content creation, distribution, and storage. Optimization, encoding a video clip at the highest possible quality within a given bit rate, is expected to become increasingly important in the future. As this process repeats encoding many times, rate control should converge quickly. This paper proposes an iterative encoding (N‐pass) optimization strategy based on the Lagrange multiplier method. It focuses on local coding units and knowledge about optimal multipliers within an MPEG‐2 framework. We also propose and demonstrate an affiliated accurate rate control algorithm. Simulation results show the PSNR gain for this optimization method is 1.0 to 1.9 dB higher than that offered by the TM5 method, and is significantly higher than the 0.03 to 0.7 dB gain improvement over TM5 we achieved with quantization‐parameter‐based optimization. The rate control framework is highly accurate; the error is less than 1% within one or two rate control iterations. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 1–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10455
Construction of a real‐time music delivery system for IMT‐2000 using twin VQ
Authors: Mori Takeshi , Kaneko Takao , Iwakami Naoki , Moriya Takehiro , Ikeda Kazunaga
Published: July 2003

This paper describes the error‐protected Twin VQ coding method, which can be applied to the IMT‐2000 mobile communications system. A real‐time music delivery system based on this method is reported. The Twin VQ coding method, which includes error detection and error suppression measures, is used to reduce the audio distortion of decoding resulting from the coding error of wireless transmission. Real‐time encoding and decoding under the proposed method are also described. Computer simulations of IMT‐2000 are used to evaluate the subjective quality of the delivered music. The possibility of a high‐quality real‐time music delivery system using IMT‐2000 is demonstrated. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(10): 102–110, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1214
Effects of adrenalectomy on CART expression in the rat arcuate nucleus
Authors: Balkan Burcu , Koylu Ersin , Pogun Sakire , Kuhar Michael J.
Published: July 2003

In order to test for glucocorticoid regulation of CART in the arcuate nucleus, adrenalectomies (ADX) and hormone replacements (HRs) were carried out in groups of rats. CART mRNA levels were determined by in situ hybridization and CART peptide levels by immunocytochemistry. ADX caused a lowering of CART mRNA and peptides levels in the arcuate and this was reversed by HR. These results indicate a glucocorticoid regulation of CART in the arcuate. The regulation could be direct through an action of glucocorticoid receptors or indirectly through ADX‐induced changes in leptin levels. These findings suggest a role for CART in the stress response. Synapse 50:14–19, 2003. © 2003 Wiley‐Liss, Inc.
Anesthetics inhibit high‐affinity states of dopamine D2 and other G‐linked receptors
Authors: Seeman Philip , Kapur Shitij
Published: July 2003

The high‐affinity states of dopamine D2 and D3 receptors, serotonin 5HT‐2A receptors, beta‐2‐adrenoceptors, alpha‐1 and alpha‐2 adrenoceptors, opiate receptors, and muscarinic receptors were inhibited by clinical concentrations of anesthetics, including isoflurane, halothane, chloral hydrate, ketamine, and ethanol. The inhibition occurred not only in vitro, but also in vivo in rats anesthetized with isoflurane, with the high‐affinity states recovering at different rates. Because the high‐affinity states of G‐protein‐linked receptors are physiologically functional, their general inhibition by clinical concentrations of anesthetics may underlie general anesthesia and may explain some of the side effects of anesthetics. Subanesthetic concentrations of the anesthetics, including ketamine, stimulated the incorporation of GTP into the cloned dopamine D2 receptors. It is possible that the classical stage 2 excitement phase which occurs with subanesthetic concentrations of general anesthetics and ketamine may be associated with this general stimulation of a variety of G‐protein‐linked receptors, as found in the present study, while the stage 3 level of surgical anesthesia may be associated with the inhibition of the high‐affinity states of several receptors. Synapse 50:35–40, 2003. © 2003 Wiley‐Liss, Inc.
Schizophrenia hippocampus has elevated expression of chondrex glycoprotein gene
Authors: Chung Carmen , Tallerico Teresa , Seeman Philip
Published: July 2003

To identify genes associated with schizophrenia, DNA microarray chips were used to compare schizophrenia and control hippocampus tissues, revealing four genes with elevated expression, chondrex (or YKL‐40), histamine‐releasing factor, HERC2, and heat‐shock 70. However, using the quantitative real‐time polymerase chain reaction method, only the expression of the chondrex gene, an extracellular matrix glycoprotein involved in cell growth and migration, was found to be significantly elevated, by 1.8‐fold. Real‐time PCR found that the expression of the histamine‐releasing factor gene, known to be associated with cognitive deficits in Alzheimer's disease, was significantly reduced by 19%. The expression of the HERC2 and heat‐shock 70 genes, as measured by real‐time PCR, were not significantly altered in the schizophrenia hippocampus. The altered gene expression of chondrex suggests that disruption in neuronal migration may be involved in schizophrenia. The change in expression of the histamine‐releasing factor gene suggests that this gene may be associated with the negative symptoms of impaired learning and memory in schizophrenia. Synapse 50:29–34, 2003. © 2003 Wiley‐Liss, Inc.
Baclofen antagonizes nicotine‐, cocaine‐, and morphine‐induced dopamine release in the nucleus accumbens of rat
Authors: Fadda Paola , Scherma Maria , Fresu Alessandra , Collu Maria , Fratta Walter
Published: July 2003

Evidence recently provided has suggested a specific involvement of the GABAergic system in modulating positive reinforcing properties of several drugs of abuse through an action on mesolimbic dopaminergic neurons. The GABAB receptor agonist baclofen has been proposed as a potential therapeutic agent for the clinical treatment of several forms of drug addiction. In the present study, using the in vivo microdialysis technique, we investigated the effect of baclofen on nicotine, cocaine, and morphine‐induced increase in extracellular dopamine (DA) levels in the shell of the nucleus accumbens, a brain area supposedly involved in the modulation of the central effects of several drugs of abuse, of freely moving rats. As expected, nicotine (0.6 mg/kg s.c.), morphine (5 mg/kg s.c.), and cocaine (7.5 mg/kg i.p.) administration in rats induced a marked increase in extracellular DA concentrations in the nucleus accumbens, reaching a maximum value of +205 ± 8.4%, +300 ± 22.2%, and +370 ± 30.7%, respectively. Pretreatment with baclofen (1.25 and 2.5 mg/kg i.p.) dose‐dependently reduced the nicotine‐, morphine‐, and cocaine‐evoked DA release in the shell of the nucleus accumbens. Furthermore, baclofen alone did not elicit changes in basal DA extracellular levels up to 180 min. Taken together, our data are in line with previous reports demonstrating the ability of baclofen to modulate the mesolimbic DAergic transmission and indicate baclofen as a putative candidate in the pharmacotherapy of polydrug abuse. Synapse 50:1–6, 2003. © 2003 Wiley‐Liss, Inc.
D‐deprenyl protects nigrostriatal neurons against 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐induced dopaminergic neurotoxicity
Authors: Muralikrishnan Dhanasekharan , Samantaray Supriti , Mohanakumar Kochupurackal P.
Published: July 2003

Selegiline (L‐deprenyl) is believed to render protection against l‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐neurotoxicity to a significant extent via a free radical scavenging mechanism, which is independent of its ability to inhibit monoamine oxidase‐B (MAO‐B) in the brain. We investigated the hydroxyl radical (.OH) scavenging action and neuroprotective effect of D‐deprenyl, its less active isomer, in MPTP‐induced dopaminergic neurotoxicity in mice to test whether the chemical structure of the molecule or its biological effects contribute to this property. To achieve this goal we studied the effects of D‐deprenyl on: (1) .OH production in a Fenton reaction; (2) MPTP‐induced .OH generation and dopamine (DA) depletion in vivo, employing a sensitive HPLC‐electrochemical procedure; and (3) formation of MPP+ in vivo in the striatum following systemic administration of MPTP, employing an HPLC‐photodiode array detection system. D‐deprenyl inhibited ferrous citrate‐induced .OH in vitro (0.45 μM) and MPTP‐induced .OH in vivo in substantia nigra (SN) and in the striatum (1.0 mg/kg, i.p.). D‐deprenyl did not, but L‐deprenyl (0.5 mg/kg dose) did significantly inhibit formation of MPP+ in the striatum 90 min following systemic MPTP injection. It failed to affect MAO‐B activity at 0.5 mg/kg in the striatum, but effectively blocked MPTP‐induced striatal DA depletion. The potency of D‐deprenyl to scavenge MPTP‐induced .OH in vivo and to render protection against the dopaminergic neurotoxicity without affecting dopamine turnover, MAO‐B activity, or formation of MPP+ in the brain indicates a direct involvement of .OH in the neurotoxic action of MPTP and antioxidant effect in the neuroprotective action of deprenyl. Synapse 50:7–13, 2003. © 2003 Wiley‐Liss, Inc.
Reciprocal synapses between inner hair cell spines and afferent dendrites in the organ of corti of the mouse
Authors: Sobkowicz Hanna M. , Slapnick Susan M. , August Benjamin K.
Published: July 2003

We provide, for the first time, ultrastructural evidence for the differentiation of reciprocal synapses between afferent dendrites of spiral ganglion neurons and inner hair cells. Cochlear synaptogenesis of inner hair cells in the mouse occurs in two phases: before and after the onset of hearing at 9–10 postnatal (PN) days. In the first phase, inner hair cells acquire afferent innervation (1–5 PN). Reciprocal synapses form around 9–10 PN on spinous processes emitted by inner hair cells into the dendritic terminals, predominantly in conjunction with ribbon afferent synapses. During the second phase, which lasts up to 14 PN, synaptogenesis is led by the olivocochlear fibers of the lateral bundle, which induce the formation of compound and spinous synapses. The afferent dendrites themselves also develop recurrent presynaptic spines or form mounds of synaptic vesicles apposed directly across inner hair cell ribbon synapses. Thus, in the adult 2‐month mouse, afferent dendrites of spiral ganglion neurons are not only postsynaptic but also presynaptic to inner hair cells, providing a synaptic loop for an immediate feedback response. Reciprocal synapses, together with triadic, converging, and serial synapses, are an integral part of the afferent ribbon synapse complex. We define the neuronal circuitry of the inner hair cell and propose that these minicircuits form synaptic trains that provide the neurological basis for local cochlear encoding of the initial acoustic signals. Synapse 50:53–66, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of the effects of bupropion on the reinforcing properties of nicotine and food in rats
Authors: Bruijnzeel Adrie W. , Markou Athina
Published: July 2003

Bupropion is an atypical antidepressant drug that is the only nonnicotine‐based prescription medicine approved for smoking cessation by the Food and Drug Administration. The aim of the present experiments was to investigate the effects of bupropion (5–40 mg/kg) on the reinforcing properties of nicotine and food in rats. The effects of bupropion were studied under two schedules of reinforcement: a fixed ratio 5 time‐out 20‐sec (FR5 TO20 s) and a progressive ratio (PR). Rats were trained to respond for nicotine (0.01 or 0.03 mg/kg/infusion, free base) or food under the FR5 TO20 s schedule. Pretreatment with the highest dose of bupropion (40 mg/kg) resulted in a significant reduction (∼50%) of nicotine intake in rats self‐administering 0.03 mg/kg/infusion of nicotine. The same dose of bupropion also decreased (∼40%) the self‐administration of 0.01 mg/kg/infusion of nicotine, but this effect did not reach statistical significance. Pretreatment with bupropion slightly (∼15%) reduced responding for food under the FR5 TO20 s schedule. Finally, pretreatment with bupropion did not affect the self‐administration of nicotine (0.03 mg/kg/infusion) under a PR schedule, but dose‐dependently increased responding for food under the same PR schedule. These findings indicate that a high dose of bupropion decreases the reinforcing properties of nicotine as measured under an FR schedule, while having no apparent effects on breaking points for nicotine under a PR schedule that reflects both the reinforcing properties and the motivation to obtain nicotine. Synapse 50:20–28, 2003. © 2003 Wiley‐Liss, Inc.
Differences in multiple forms of short‐term plasticity between excitatory and inhibitory hippocampal neurons in culture
Authors: Kaplan Michael P. , Wilcox Karen S. , Dichter Marc A.
Published: July 2003

Synaptic transmission is highly dynamic, especially during periods of repetitive activity. This short‐term synaptic plasticity, elicited by either pairs or short trains of action potentials at moderate frequencies (1–10 Hz), may give rise to either depression or facilitation of synaptic transmission. We analyzed these processes in isolated, synaptically coupled pairs of inhibitory or excitatory neurons grown in low‐density cultures of hippocampal neurons. Most inhibitory and excitatory synapses in these cultures displayed paired pulse depression, although the responses of excitatory synapses were more variable and occasionally facilitation was seen. With tetanic stimuli, inhibitory synapses showed depression, but excitatory synapses showed a much richer repertoire of behaviors, including depression and facilitation. While many inhibitory synapses showed posttetanic depression following short trains of action potentials, excitatory synapses instead showed posttetanic facilitation. This facilitation is accompanied by an increase in paired pulse ratio, suggesting that it is the result of presynaptic mechanisms. Finally, excitatory synapses often displayed paired pulse and tetanic facilitation of asynchronous release, a process not seen in inhibitory synapses in these cultures. These similarities and differences in short‐term plasticity exhibited by inhibitory and excitatory cells are likely to be critical for information processing and the control of neuronal excitability, under both normal and pathological conditions, such as epilepsy. Synapse 50:41–52, 2003. © 2003 Wiley‐Liss, Inc.
Regulation of the release of serotonin in the dorsal raphe nucleus by α1 and α2 adrenoceptors
Authors: Pudovkina Olga L. , Cremers Thomas I.F.H. , Westerink Ben H.C.
Published: July 2003

To investigate the modulation of serotonin release in the dorsal raphe nucleus (DRN) by α1 and α2 adrenoceptors, dual‐probe microdialysis was performed in conscious rats. The specific α1 and α2 adrenoceptor agonists and antagonists were locally infused into the DRN via retrograde microdialysis. The release of serotonin was simultaneously sampled from the DRN and prefrontal cortex (PFC). Infusion of the α1 adrenoceptor agonist cirazoline into the DRN (100 μM) produced an increase in the release of serotonin in the DRN to 200% of the basal levels, but no effect was seen in the PFC. After infusion of the α1 adrenoceptor antagonist prazosin into the DRN (100 μm) the release of serotonin decreased in the DRN and PFC to about 40% and 65% of the basal levels, respectively. Infusion of the α2 adrenoceptor agonist clonidine into the DRN (100 μm) slightly but significantly decreased the level of serotonin in the DRN as well as in the PFC to about 70% of the basal levels. Infusion of the α2A adrenoceptor antagonist BRL 44408 into the DRN (100 μm) caused an increase of serotonin release in the DRN to 270% of the basal levels, but at the same time no changes were seen in the extracellular levels of serotonin in the PFC. The present study demonstrates that α1 as well as α2 adrenoceptors in the DRN modulate the release of serotonin in the DRN, and that α1 adrenoceptors in the DRN are maximally stimulated during resting conditions. Synapse 50:77–82, 2003. © 2003 Wiley‐Liss, Inc.
Chronic opioid antagonist treatment selectively regulates trafficking and signaling proteins in mouse spinal cord
Authors: Patel Chintan N. , Rajashekara Vikram , Patel Kaushal , Purohit Vishal , Yoburn Byron C.
Published: July 2003

Chronic opioid antagonist treatment produces functional supersensitivity and μ‐opioid receptor (μOR) upregulation. Studies suggest a role for G‐protein receptor kinases (GRKs) and dynamin (DYN), but not signaling proteins (e.g., Giα2), in regulation of μOR density following opioid treatment. Therefore, this study examined μOR density, agonist potency, and the abundance and gene expression of GRK‐2, DYN‐2, and Giα2 in mouse spinal cord after opioid antagonist treatment. Mice were implanted with a 15 mg naltrexone (NTX) or placebo pellet and 8 days later pellets were removed. At 24 and 192 h following NTX treatment, mice were tested for spinal DAMGO analgesia. Other mice were sacrificed at 0 or 192 h following NTX treatment and Giα2, GRK‐2, and DYN‐2 protein and mRNA levels determined. [3H] DAMGO binding studies were also conducted. Immediately following NTX treatment (0 h), μOR density was increased (+ ≈135%), while 192 h following NTX treatment μOR density was unchanged. NTX increased DAMGO analgesic potency (3.1‐fold) 24 h following NTX treatment, while there was no effect at 192 h. NTX decreased protein and mRNA abundance of GRK‐2 (−32%; −48%) and DYN‐2 (−25%; −29%) in spinal cord at 0 h. At 192 h following 8‐day NTX treatment, GRK‐2 protein and mRNA were at control levels, while DYN‐2 protein remained decreased (–31%) even though DYN‐2 mRNA had returned to control levels. Giα2 was unaffected by NTX treatment. These data suggest that opioid antagonist‐induced μ‐receptor upregulation is mediated by changes in abundance and gene expression of proteins implicated in receptor trafficking, which may decrease constitutive receptor cycling. Synapse 50:67–76, 2003. © 2003 Wiley‐Liss, Inc.
Characterization of vps33+, a gene required for vacuolar biogenesis and protein sorting in Schizosaccharomyces pombe
Authors: Iwaki Tomoko , Osawa Fumi , Onishi Masayuki , Koga Takako , Fujita Yasuko , Hosomi Akira , Tanaka Naotaka , Fukui Yasuhisa , Takegawa Kaoru
Published: July 2003

From the fission yeast Schizosaccharomyces pombe we have identified and deleted vps33, a gene encoding a homologue of VPS33, which is required for vacuolar biogenesis in S. cerevisiae cells. When the vps33+ gene is disrupted, Sz. pombe strains are temperature‐sensitive for growth and contain numerous small vesicular structures stained with FM4–64 in the cells. Deletion of the Sz. pombe vps33+ gene results in pleiotropic phenotypes consistent with the absence of normal vacuoles, including missorting of vacuolar carboxypeptidase Y, various ion‐ and drug‐sensitivities, and sporulation defects. These results are consistent with Vps33p being necessary for the morphogenesis of vacuoles and subsequent expression of vacuolar functions in Sz. pombe cells. Copyright © 2003 John Wiley & Sons, Ltd.