bluuebunny/crossref_metadata_2025 huggingface dataset:
Neuropsychological deficits in Parkinson's disease patients with visual hallucinations
Authors: Ramírez‐Ruiz Blanca , Junqué Carme , Martí María‐José , Valldeoriola Francesc , Tolosa Eduardo
Published: May 2006

Recent neuropathological and neuroimaging studies suggest the involvement of several temporal regions in Parkinson's disease (PD) patients with visual hallucinations (VH). We examined 24 nondemented PD patients with VH, 21 PD patients without VH, and 21 healthy controls using a battery of tests assessing different aspects of temporal lobe function. PD patients with VH showed poorer performance in language, verbal learning, semantic fluency, and visuoperceptive functions compared to controls and PD patients without VH. Differences in verbal learning and visuoperceptive functions were independent of general cognitive status, disease severity, and depression. We suggest that a wide range of neuropsychological deficits can contribute to the emergence of VH in PD. © 2006 Movement Disorder Society
Surface electromyography shows increased mirroring in Parkinson's disease patients without overt mirror movements
Authors: Cincotta Massimo , Giovannelli Fabio , Borgheresi Alessandra , Balestrieri Fabrizio , Vanni Paola , Ragazzoni Aldo , Zaccara Gaetano , Ziemann Ulf
Published: May 2006

Patients with Parkinson's disease (PD) may present mirror movements (MM). Transcranial magnetic stimulation data indicate that these movements reflect an abnormal enhancement of the “physiological mirroring” that can be observed in healthy adults during complex and effortful tasks. It was hypothesized that, in PD, enhanced mirroring is caused by a failure of basal ganglia output to support the cortical network that is responsible for the execution of strictly unimanual movements. If so, it is likely that subtle alterations of voluntary unimanual motor control are also present in PD patients without overt MM. We tested this hypothesis by using surface electromyographic (EMG) techniques in 12 mildly to moderately affected PD patients without overt MM, and in 2 control groups (12 age‐matched and 10 young healthy volunteers). Subjects performed unilateral phasic thumb abduction during a sustained tonic contraction of the opposite abductor pollicis brevis. All patients were tested on dopaminergic therapy. On a separate day, 7 of 12 patients were re‐tested after withdrawal of medication. During this task, involuntary mirror‐like increase in surface EMG of the tonically abducting thumb was significantly larger in PD patients than in age‐matched or young healthy volunteers. Off therapy, mirroring was slightly greater than on medication, although this difference was not significant. Our findings suggest that dysfunction of unimanual motor control is a general feature of PD. It is likely that this deficient movement lateralization contributes to an impairment of nonsymmetrical bimanual movements in PD. © 2006 Movement Disorder Society
Toward a better description of gallo‐phosphate materials in solid‐state NMR: 1D and 2D correlation studies
Authors: Montouillout Valérie , Morais Cláudia M. , Douy André , Fayon Franck , Massiot Dominique
Published: May 2006

We show that weak 2J(71GaO31P), typically ∼12 Hz in GaPO4, can be used to efficiently establish heteronuclear 31P71Ga correlation using a MAS HMQC experiment in gallo‐phosphate materials. The experiment demonstrated for cristobalite GaPO4 is then applied to Ga(PO3)3, where it allows the differentiation of the signature of three different Ga sites overlapping in the 1D spectrum. Copyright © 2006 John Wiley & Sons, Ltd.
Influence of ovarian hyperstimulation and ovulation induction on the cytoskeletal dynamics and developmental competence of oocytes
Authors: Lee Seung Tae , Han Ho Jae , Oh Seo Jin , Lee Eun Ju , Han Jae Yong , Lim Jeong M.
Published: May 2006

This study was undertaken to determine the effects of gonadotrophin on cytoskeletal dynamics and embryo development and its role in improving the retrieval of developmentally competent oocytes. Female golden hamsters were injected with human chorionic gonadotrophin (hCG; 5‐, 7.5‐ or 15‐IU) on the day 4 of estrus, pregnant mare serum gonadotrophin (PMSG; 5‐, 7.5‐ or 15‐IU) on the day 1 of estrus, or 15‐IU hCG at 56 hr post‐15‐IU PMSG injection in any cycle except estrus. Increasing the hCG dose decreased not only retrieval rate of 2‐cell embryo but development to blastocyst after subsequent in vitro culture. Whereas, although increasing the PMSG dose induced increasing the number of 2‐cell embryo and blastocyst, 15‐IU PMSG injection caused retardation of development to blastocyst. No 2‐cell embryos were retrieved by injecting both PMSG and hCG. The injections of 15‐IU hCG and 7.5‐ or 15‐IU PMSG inhibited the proliferation of trophectodermal and inner cell mass cells, respectively. Gonadotrophin injection didn't influence microtubular spindle formation, but 5‐ or 15‐IU hCG, 15‐IU PMSG, or PMSG and hCG injections induced aberrant cortical granule (CG) and microfilament distribution. After 15‐IU hCG or PMSG and hCG injections, fewer oocytes had enriched cortical actin domains, and the expression of α‐, β‐ and γ‐actin genes was greatly increased. In conclusion, a high dose of gonadotrophins alters the microfilament and CG distribution, which in turn reduces the developmental competence of oocytes. Injecting a reduced dose of PMSG to initiate ovarian hyperstimulation without triggering ovulation contributes to the efficient retrieval of developmentally competent oocytes. Mol. Reprod. Dev. 1022–1033, 2006. © 2006 Wiley‐Liss, Inc.
Value of repeated measures of nerve conduction and quantitative sensory testing in a diabetic neuropathy trial
Authors: Bird Shawn J. , Brown Mark J. , Spino Cathie , Watling Sharon , Foyt Howard L.
Published: May 2006

Conduct of a large, multicenter trial of the aldose reductase inhibitor zenarestat provided data on the reproducibility of multiple electrophysiologic (nerve conduction studies, NCS) and quantitative sensory (QST) tests. Baseline and 12‐month electrophysiologic data from approximately 1100 patients at multiple centers were available for analysis. Intersite variability contributed minimally to overall test variance. All NCS tests were highly reproducible. Cool thermal and vibration QST thresholds, as measured by CASE IV instrumentation, were also highly reproducible. Intersubject variance accounted for the majority of variance for all parameters measured. Repeating NCS and QST measures decreased sample sizes needed to show statistical significance. Consideration of these observations, particularly with regard to QST, should aid in the design of future clinical trials investigating neuropathy. Muscle Nerve, 2006
Minimum cost flow‐dependent communication networks
Authors: Thomas D.A. , Weng J.F.
Published: May 2006

In the construction of a communication network, the (Euclidean) length of the network is an important but not unique factor determining the cost of the network. Among many possible network models, Gilbert proposed a flow‐dependent model in which flow demands are assigned between each pair of points in a given point set A, and the cost per unit length of a link in the network is a function of the flow through the link. In this article we first investigate the properties of this Gilbert model: the concavity of the cost function, decomposition, local minimality, the number of Steiner points, and the maximum degree of Steiner points. Then we propose three heuristics for constructing minimum cost Gilbert networks. Two of them come from the fact that generally a minimum cost Gilbert network stands between two extremes: the complete network G(A) on A and the edge‐weighted Steiner minimal tree W(A) on A. The first heuristic starts with G(A) and reduces the cost by splitting angles; the second one starts with both G(A) and W(A), and reduces the cost by selecting low cost paths. As a generalization of the second heuristic, the third heuristic constructs a new Gilbert network of less cost by hybridizing known Gilbert networks. Finally, we discuss some considerations in practical applications. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 48(1), 39–46 2006
Three‐level BDDC in two dimensions
Authors: Tu Xuemin
Published: May 2006

Balancing Domain Decomposition by Constraints (BDDC) methods are non‐overlapping iterative substructuring domain decomposition methods for the solution of large sparse linear algebraic systems arising from discretization of elliptic boundary value problems. They are similar to the balancing Neumann–Neumann algorithm. However, in BDDC methods, a small number of continuity constraints are enforced across the interface, and these constraints form a new coarse, global component. An important advantage of using such constraints is that the Schur complements that arise in the computation will all be strictly positive definite. The matrix of the coarse problem is generated and factored by direct solvers at the beginning of the computation. However, this problem can ultimately become a bottleneck, if the number of subdomains is very large. In this paper, two three‐level BDDC methods are introduced for solving the coarse problem approximately in two‐dimensional space, while still maintaining a good convergence rate. Estimates of the condition numbers are provided for the two three‐level BDDC methods and numerical experiments are also discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Thermo‐mechanical analysis of periodic multiphase materials by a multiscale asymptotic homogenization approach
Authors: Zhang H. W. , Zhang S. , Bi J. Y. , Schrefler B. A.
Published: May 2006

A spatial and temporal multiscale asymptotic homogenization method used to simulate thermo‐dynamic wave propagation in periodic multiphase materials is systematically studied. A general field governing equation of thermo‐dynamic wave propagation is expressed in a unified form with both inertia and velocity terms. Amplified spatial and reduced temporal scales are, respectively, introduced to account for spatial and temporal fluctuations and non‐local effects in the homogenized solution due to material heterogeneity and diverse time scales. The model is derived from the higher‐order homogenization theory with multiple spatial and temporal scales. It is also shown that the modified higher‐order terms bring in a non‐local dispersion effect of the microstructure of multiphase materials. One‐dimensional non‐Fourier heat conduction and dynamic problems under a thermal shock are computed to demonstrate the efficiency and validity of the developed procedure. The results indicate the disadvantages of classical spatial homogenization. Copyright © 2006 John Wiley & Sons, Ltd.
The intrinsic XFEM: a method for arbitrary discontinuities without additional unknowns
Authors: Fries Thomas‐Peter , Belytschko Ted
Published: May 2006

A new method for treating arbitrary discontinuities in a finite element (FE) context is presented. Unlike the standard extended FE method (XFEM), no additional unknowns are introduced at the nodes whose supports are crossed by discontinuities. The method constructs an approximation space consisting of mesh‐based, enriched moving least‐squares (MLS) functions near discontinuities and standard FE shape functions elsewhere. There is only one shape function per node, and these functions are able to represent known characteristics of the solution such as discontinuities, singularities, etc. The MLS method constructs shape functions based on an intrinsic basis by minimizing a weighted error functional. Thereby, weight functions are involved, and special mesh‐based weight functions are proposed in this work. The enrichment is achieved through the intrinsic basis. The method is illustrated for linear elastic examples involving strong and weak discontinuities, and matches optimal rates of convergence even for crack‐tip applications. Copyright © 2006 John Wiley & Sons, Ltd.
Efficient optimization processes using kriging approximation models in electrical impedance tomography
Authors: Mera N. S.
Published: May 2006

A reduced model technique based on kriging approximations is developed in order to increase the rate of convergence of an evolution strategy (ES) when solving a non‐destructive evaluation problem. The inverse problem investigated consists of identifying the geometry of discontinuities in a conductive material from Cauchy data measurements taken on the boundary. In this study, we use kriging approximation models in order to increase the rate of convergence of the optimization algorithm and to efficiently detect, from a computational time point of view, a subsurface cavity, such as a circle. The algorithm developed by combining evolution strategies and kriging approximations is found to be a robust, fast and efficient method for detecting the size and location of subsurface cavities. Copyright © 2006 John Wiley & Sons, Ltd.
Vapour sorption studies of polymer‐solution thermodynamics using a piezoelectric quartz crystal microbalance
Authors: Price Gareth J , Haddon Dawn A , Bainbridge Anthony , Buley Jill M
Published: May 2006

A quartz crystal microbalance was used as the basis of a vapour sorption apparatus to measure thermodynamic interaction parameters of polystyrene, poly(4‐chlorostyrene) and poly(methyl methacrylate) with a number of solvents. The apparatus was shown to give rapid and reliable results by comparison with literature results for poly(dimethyl siloxane). Measurements of activity coefficients and Flory–Huggins interaction parameters were correlated with the solution behaviour of the components and revealed some hitherto unreported effects of the solution concentration in polar systems. Copyright © 2006 Society of Chemical Industry
Evaluation of solar energy potential and PV module performance in the Gobi Desert of Mongolia
Authors: Adiyabat Amarbayar , Kurokawa Kosuke , Otani Kenji , Enebish Namjil , Batsukh Garmaa , Battushig Mishiglunden , Ochirvaani Dorjsuren , Ganbat Bathuu
Published: May 2006

Here, we present the results of evaluation of solar energy potential and photovoltaic (PV) module performance from actual data measured over a period of more than 2 years in the Gobi Desert of Mongolia. To allow estimation of solar energy potentials and durability of PV systems in the Gobi Desert area, a data acquisition system, including crystalline silicon (c‐Si), polycrystalline silicon (p‐Si) modules, and two sets of precision pyranometers, thermometers, and anemometer, was installed at Sainshand City in October 2002. This system measures 23 parameters, including solar irradiation and meteorological parameters, every 10 min. High output gain was observed due to operation at extremely low ambient temperatures and the module performance ratios (PRs) were high (>1·0) in winter. In summary, the present study showed that a PV module with a high temperature coefficient, such as crystalline silicon, is advantageous for use in the Gobi Desert area. Copyright © 2006 John Wiley & Sons, Ltd.
Cyclolinear polysiloxanes. II. Crosslinking and characterization
Authors: Daum J. , Erdodi G. , Kennedy J. P.
Published: May 2006

The synthesis and characterization of two groups of novel networks prepared from cyclolinear polysiloxanes are described. The first group of networks from cyclolinear polysiloxanes (N‐CLPSs) was synthesized by the hydrosilation of vinyl‐terminated cyclolinear polyorganosiloxanes [prepared from diacetoxydiethyltetramethylcyclotetrasiloxane (D4Et2OAc2) or diacetoxytriethylpentamethylcyclopentasiloxane (D5Et3OAc2)] with a copolymer of dimethylsiloxane and methylhydrosiloxane as the crosslinking agent. Hydrosilation was effected with a platinum carbonyl catalyst with a cyclovinylsiloxane moderator. The second group of networks (N‐eCLPSs) was prepared similarly with extended cyclolinear polysiloxanes. The mechanical properties of the novel networks were comparable to those of polydimethylsiloxane networks (N‐PDMS). The oxygen permeabilities were similar to or slightly higher than that of N‐PDMS. The glass‐transition temperatures of D4Et2OAc2‐ and D5Et3OAc2‐based N‐CLPSs were −67.8 and −90.8 °C, respectively, whereas the incorporation of polydimethylsiloxane spacers into similar N‐eCLPSs lowered their glass‐transition temperatures to −109.7 and −115.0 °C. Upon heating to 800 °C in air, N‐CLPSs yielded more residue than N‐eCLPSs, which in turn yielded more residue than N‐PDMS. These results may have been due to the presence of T units in the cyclic siloxane units, which may have inhibited chain degradation or the formation of volatile products. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4053–4062, 2006
Cyclolinear polysiloxanes. I. Synthesis and characterization
Authors: Daum J. , Erdodi G. , Kennedy J. P.
Published: May 2006

The synthesis and characterization of two novel cyclic siloxanes, diacetoxydiethyltetramethylcyclotetrasiloxane and diacetoxytriethylpentamethylcyclopentasiloxane, and cyclolinear polymers synthesized from these monomers are presented. The cyclic siloxanes were synthesized from tetramethylcyclotetrasiloxane and pentamethylcyclopentasiloxane, respectively, by acetylation followed by ethylation. The cyclic monomers were characterized with 1H NMR spectroscopy. Subsequently, the cyclic siloxanes were self‐condensed into cyclolinear polysiloxanes and cocondensed (extended) with silanol‐terminated polydimethylsiloxane into high‐molecular‐weight polymers containing cyclic units withlinearpolydimethylsiloxane spacers (extended cyclolinear polysiloxanes). The molecular weights of both the cyclolinear polysiloxanes and extended cyclolinear polysiloxanes were determined. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4039‒4052, 2006
Synthesis, photochemical and phase behavior of linear and hyperbranched photoactive benzylidene liquid‐crystalline polyesters
Authors: Murali M. , Samui A. B.
Published: May 2006

Photoactive hyperbranched benzylidene liquid‐crystalline polyester (PAHBP) and photoactive linear benzylidene liquid‐crystalline polyester (PALBP) were synthesized by solution polycondensation with pyridine as an acid acceptor. PAHBP and PALBP were thoroughly characterized with Fourier transform infrared, 1H and 13C NMR, ultraviolet–visible spectrophotometry, fluorescent spectrophotometry, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, and polarized optical microscopy. Both polymers exhibited nematic mesophase. The glass‐transition temperature and liquid‐crystalline isotropic temperature of PAHBP were higher than those of PALBP. During photolysis under ultraviolet light, both polymers underwent an intermolecular photocycloaddition reaction, and the photoactivity of PAHBP was faster than that of PALBP; this was further confirmed by photoviscosity studies. PALBP and PAHBP were fluorescent in nature. An increase in the fluorescence intensity with the time of ultraviolet‐light irradiation was observed for both PAHBP and PALBP. The rate of increase in the fluorescence intensity of the linear analogue (PALBP) was higher than that of the hyperbranched polymer (PAHBP). This behavior could be attributed to the attainment of better planarity in the case of the linear one but not in the case of PAHBP because of the rapid crosslinking of PAHBP leading to an irregular architecture. This behavior was further confirmed by the calculation of the steric energy from corresponding model compounds. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3986–3994, 2006
Blue‐light‐emitting and anodically electrochromic materials of new wholly aromatic polyamides derived from the high‐efficiency chromophore 4,4′‐dicarboxy‐4″‐methyltriphenylamine
Authors: Liou Guey‐Sheng , Huang Nan‐Kun , Yang Yi‐Lung
Published: May 2006

A series of organosoluble, aromatic polyamides were synthesized from a 4‐methyl‐substituted, triphenylamine‐containing, aromatic diacid monomer, 4,4′‐dicarboxy‐4″‐methyltriphenylamine, which is a blue‐light (454‐nm) emitter with a fluorescence quantum efficiency of 46%. These triphenylamine‐based, high‐performance polymers had strong fluorescence emissions in the blue region with high quantum yields up to 64% and one reversible oxidation redox couple around 1.20 V versus Ag/AgCl in acetonitrile solutions. They exhibited good thermal stability, with 10% weight loss temperatures above 480 °C under a nitrogen atmosphere and with relatively high glass‐transition temperatures (252–309 °C). All the polyamides revealed excellent stability of electrochromic characteristics, changing color from the original pale yellow to blue. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4095–4107, 2006
A statistical framework to discover true associations from multiprotein complex pull‐down proteomics data sets
Authors: Shen Changyu , Li Lang , Chen Jake Yue
Published: May 2006

Experimental processes to collect and process proteomics data are increasingly complex, and the computational methods to assess the quality and significance of these data remain unsophisticated. These challenges have led to many biological oversights and computational misconceptions. We developed an empirical Bayes model to analyze multiprotein complex (MPC) proteomics data derived from peptide mass spectrometry detections of purified protein complex pull‐down experiments. Using our model and two yeast proteomics data sets, we estimated that there should be an average of about 20 true associations per MPC, almost 10 times as high as was previously estimated. For data sets generated to mimic a real proteome, our model achieved on average 80% sensitivity in detecting true associations, as compared with the 3% sensitivity in previous work, while maintaining a comparable false discovery rate of 0.3%. Cross‐examination of our results with protein complexes confirmed by various experimental techniques demonstrates that many true associations that cannot be identified by previous approach are identified by our method. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Three‐dimensional modeling of cytomegalovirus DNA polymerase and preliminary analysis of drug resistance
Authors: Shi Rong , Azzi Arezki , Gilbert Christian , Boivin Guy , Lin Sheng‐Xiang
Published: May 2006

Cytomegalovirus (CMV) is the leading cause of congenital infection and a frequent opportunistic agent in immunocompromised hosts such as transplant recipients and AIDS patients. CMV DNA polymerase, a member of the polymerase B family, is the primary target of all available antivirals (ganciclovir, cidofovir, and foscarnet) and certain variations of this enzyme could lead to drug resistance. However, understanding the drug resistance mechanisms at the atomic level is hampered by the lack of its three‐dimensional (3D) structure. In the present work, 3D models of two different conformations (closed and open) for CMV DNA polymerase have been built based on the crystal structures of bacteriophage RB69 DNA polymerase (a member of the polymerase B family) by using the 3D‐Jury Meta server and the program MODELLER. Most of the variations on CMV DNA polymerase pertinent to ganciclovir/cidofovir and foscarnet resistance can be explained well based on the open and closed conformation models, respectively. These results constitute a first step towards facilitating our understanding of drug resistance mechanisms for CMV and the interpretation of novel viral mutations. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Roles of conserved basic amino acid residues and activation mechanism of the hyperthermophilic aspartate racemase at high temperature
Authors: Yoshida Takumitsu , Seko Tomohiro , Okada Okimasa , Iwata Kousuke , Liu Lijun , Miki Kunio , Yohda Masafumi
Published: May 2006

X‐ray crystallography has revealed two similar α/β domains of the aspartate racemase from the hyperthermophilic archaeon, Pyrococcus horikoshii OT3. The active site is located in the cleft between the two domains where two cysteine residues face each other. This arrangement allows the substrate to enter the cleft and enables the two cysteine residues to act synergistically. However, the distance between their thiolates was estimated to be 9.6 Å, which is beyond the distance for cooperative action of them. We examined the molecular mechanism for the racemization reaction of this hyperthermophilic aspartate racemase by mutational analyses and molecular dynamics simulations. The mutational analyses revealed that Arg48 and Lys164 were essential for catalysis in addition to the putative catalytic cysteine residues. The molecular dynamics simulations revealed that the distance between the two active γ‐sulfur atoms of cysteine residues oscillate to periodically become shorter than the predicted cooperative distance at high temperature. In addition, the conformation of Tyr160, which is located at the entrance of the cleft and inhibits the entry of a substrate, changes periodically to open the entrance at 375 K. The opening of the gate is likely to be induced by the motion of the adjacent amino acid, Lys164. The entrance of an aspartate molecule was observed by molecular dynamics (MD) simulations driven by the force of the electrostatic interaction with Arg48, Lys164, and also Asp47. These results provide insights into the roles of amino acid residues at the catalytic site and also the activation mechanism of a hyperthermophilic aspartate racemase at high temperature. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Eu3+ location in Eu doped GaN thin films and quantum dots
Authors: Andreev Thomas , Liem Nguyen Quang , Hori Yuji , Tanaka Mitsuhiro , Oda Osamu , Dang Daniel Le Si , Daudin Bruno
Published: May 2006

We report on a comparative optical study of molecular beam epitaxy grown GaN:Eu quantum dots (QDs) and GaN:Eu layer. In the GaN:Eu layer the narrow emission lines of the 5D0‐7F2 transition allow to identify two different Eu locations corresponding to near the sample surface and lying deeper in the bulk. Eu3+ emission from QDs has been found to be at the same spectral position than that assigned to Eu3+ ions located in the bulk of the GaN:Eu layer. Eu emission in the temperature range 4‐300 K is thermally stable in doped QDs, but exhibits a strong thermal quenching in the doped layer, particularly for Eu3+ ions located near the surface. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of In‐polar and N‐polar InN nanocolumns on GaN templates by molecular beam epitaxy
Authors: Wang Xinqiang , Che Song‐Bek , Ishitani Yoshihiro , Yoshikawa Akihiko
Published: May 2006

In‐polar and N‐polar InN nanocolumns were grown on Ga‐polar and N‐polar GaN templates by molecular beam epitaxy, respectively. High N/In flux ratio was preferred for successful growth of the InN nanocolumns in both polarities. The maximum growth temperature of N‐polar InN columns was about 100 °C higher than that of In‐polar ones. The density and diameter of columns could be controlled by varying the growth temperature. The InN columns in different polarities showed different morphologies. In comparison to InN film, the InN nanocolumns showed higher growth rate and stronger photoluminescence. XRD results indicated that InN nanocolumns were in good crystal quality with small tilt. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of leakage current in AlGaN Schottky interfaces by an ultrathin Al layer
Authors: Kaneko Masamitsu , Hashizume Tamotsu
Published: May 2006

A surface control process which suppresses leakage currents in Ni Schottky interfaces fabricated on Al‐GaN/GaN heterostructures has been suggested. XPS results showed that oxygen impurities which were preferentially incorporated in AlGaN, could be removed by formation of ultrathin aluminumoxide through aluminum deposition and in‐situ annealing at 700 °C. From the detailed analysis of current–voltage characteristics, it is found that the leakage currents depend on the tunneling transport through Ni/AlGaN Schottky interfaces. Ni/AlGaN Schottky contacts with surface control process exhibit the suppression of reverse leakage current by three orders of magnitude as compared to those without surface control process. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel buffer layer for the growth of GaN on c‐sapphire
Authors: Lee Wookhyun , Lee Seogwoo , Goto Hiroki , Ko Hyunchul , Cho Meoungwhan , Yao Takafumi
Published: May 2006

We propose a rocksalt (RS) structured chromium nitride (CrN) layer as a novel buffer for the growth of gallium nitride (GaN) films on c‐sapphire substrate. A RS‐CrN buffer has good advantages for growing GaN films on c‐sapphire from the viewpoints of lattice mismatch and thermal expansion coefficient. The RS‐CrN layer has mid value of both the lattice constant and the thermal expansion coefficient of GaN and c‐sapphire. It is verified that the lattice mismatch between CrN and c‐sapphire of 6.2–6.7%, which is experimentally estimated from reflection high‐energy electron diffraction (RHEED) characterization, about 6.2–6.7%, agree well with the calculated value of 6.6%. By these advantages, N‐polarity GaN epilayers grown on RS‐CrN buffer layer show remarkably improved crystal quality when compared with those of grown on conventional low temperature (LT) GaN buffer using molecular beam epitaxy (MBE). For a further improvement of GaN crystallinity, we performed the surface treatment of Ga‐exposure on CrN buffer layer. The Ga‐exposure treatment on the RS‐CrN buffer layer drastically improved the crystal quality of upper GaN epilayer, which was identified by measuring structural and optical properties using X‐ray diffraction (XRD) and Photoluminescence (PL), respectively. The improved crystallinity is resulted not from the polarity conversion but from the stress relaxation effect by a metallic Ga interlayer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Preparation and characterisation of tantalum carbide as an optional crucible material for bulk aluminium nitride crystal growth via physical vapour transport
Authors: Hartmann C. , Wollweber J. , Albrecht M. , Rasin I.
Published: May 2006

This paper reports experimental measured and calculated phase distributions of carburised Ta sheets. Electron back scatter diffraction (EBSD) maps of carburised Ta samples have shown the progress of carburisation in respect of the annealing procedure. The initial stage is characterised by grain boundary and surface carburisation at lower temperatures (T = 2000 °C). At elevated annealing temperatures (T = 2200 °C) grain boundaries play a negligible role in the transformation of Ta to TaC. Sharply bounded phase layers of TaC1–x and Ta2C are observed in this case. Fast grain coarsening below the carburisation temperature was found. A diffusion controlled phase formation model was introduced. The calculated concentrations of C are in good agreement with the measured phase widths. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
[2,3]‐sigmatropic rearrangements of hydrogen and alkyl 3‐propenyl sulfoxides: A computational study
Authors: Freeman Fillmore , Bathala Radha M. , Cavillo Jessica E. , Huang Angela C. , Jackson Tara K. , Lopez‐Mercado Angelica Zavala , Phung Sandy , Suh Jenny , Valencia Diego O.
Published: May 2006

The [2,3]‐sigmatropic rearrangements of hydrogen and alkyl 3‐propenyl sulfoxides (R = H, CH3, CF3, CCl3) to the corresponding 3‐propenyl sulfenates have been examined computationally using HF, MP2, and B3LYP with the 6‐31G(d), 6‐31+G(d,p), 6‐311+G(d,p), 6‐311+G(2d,2p), 6‐311+G(3d,2p), and cc‐pVTZ basis sets. The relative energies (Erel) of the respective isomeric sulfoxides and sulfenates are sensitive to the level of theory and to electron correlation. The sulfenate is more stable in the gas phase, and the more polar sulfoxide is more stable in aqueous medium. The rearrangements are concerted, and the endo and exo five‐membered transition states are very close in energy (ΔE = <1 kcal/mol). MP2/6‐311+G(3d,2p) predicted the activation barriers for the sulfoxide–sulfenate rearrangements to be [kcal/mol, (R)] 19.0 (H), 21.4 (CH3), 19.3 (CF3), and 21.8 (CCl3), respectively. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
High‐ and low‐resolution mass spectrometry coupled to liquid chromatography as confirmatory methods of anabolic residues in crude meat and infant foods
Authors: Gentili Alessandra , Sergi Manuel , Perret Daniela , Marchese Stefano , Curini Roberta , Lisandrin Sabrina
Published: May 2006

Within the European Union the use of anabolic steroids for promoting growth and improving meat‐to‐fat ratio in food‐producing animals has been banned since 1988. For the unequivocal identification of hormone residues in a complex matrix such as meat we have developed a rapid, specific and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method, in combination with a simple extraction procedure based on the matrix solid‐phase dispersion (MSPD). The performances of a triple quadrupole (QqQ) and a quadrupole/time‐of‐flight (QqTOF) were compared: the QqQ mass spectrometer was found to be more sensitive for almost all studied analytes, but the selectivity was superior using the QqTOF system; the full‐scan spectra (acquired without losing sensitivity), mass accuracy and resolution of the hybrid instrument enabled a more probatory analyte identification than that obtained selecting two multiple‐reaction monitoring (MRM) transitions with a QqQ. Average recoveries ranged from 80 to 100%, and the detection capabilities (CCβs) were less than 1.06 ppb with the QqQ instrument and less than 5.20 ppb with the QqTOF instrument for the bovine meat, which proved to be the most complex matrix. Copyright © 2006 John Wiley & Sons, Ltd.
Dynamic wide‐area scene visualization using an active camera
Authors: Tokai Shogo , Yumiba Ryo , Wu Xiaojun , Matsuyama Takashi
Published: May 2006

This paper will discuss a method for presenting a surveillance image captured by an active camera such as one that actively tracks a moving subject as an image that is easily understood by an observer. Active camera surveillance images generally have a narrow field of view, and changes in the line‐of‐sight direction of an automatic camera make it difficult for an observer to intuitively understand the scene. However, enhancement of the observer's ability to comprehend the scene can be anticipated by adding a wide‐angle panoramic image to the periphery of the narrow‐field observed image and presenting it as an image that has a wider field of view. In order for an observer to understand conditions in a remote location, the observed image and the panoramic image must be integrated with geometric/photometric consistency. The present paper will discuss a method of geometric integration using a fixed‐viewpoint camera, and a method of photometric integration by modeling of brightness variation by eigenimage analysis. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(8): 101–112, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10160
A digital watermarking scheme that preserves image quality and is applicable to watermark sequences from a variety of distributions
Authors: Tachibana Takashi , Fujiyoshi Masaaki , Kiya Hitoshi
Published: May 2006

We propose a method for performing digital watermarking that can preserve image quality by enabling the degradation of image quality to be automatically constrained when the objective is to embed a watermark within a moving image sequence in real time. The proposed method is always able to create a watermarked image with the desired level of image quality (peak to signal noise ratio; PSNR). In addition, the method is a nonreference digital watermarking scheme in that it does not require the original image for the watermark to be extracted after embedding in an image. Existing digital watermarking methods guaranteeing image quality are restricted in their application to watermark components consisting of real‐valued terms that form a normalized distribution. Our method, on the other hand, removes such constraints and can be applied to watermark sequences from a variety of distributions. In addition, with the proposed method it is possible to remove the embedded watermark without explicitly extracting the watermark sequence and it is also possible to improve the image quality as a result. In simulations where we embed a binary sequence from a uniform distribution as a watermark into images, we confirm that image quality is preserved and that image quality can be improved when the watermark is removed. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(8): 90–100, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20257
Outdoor environment recognition system on Robotic Communication Terminals supporting mobility of elderly and disabled people
Authors: Kayama Kentaro , Yairi Ikuko Eguchi , Igi Seiji
Published: May 2006

We are developing Robotic Communication Terminals (RCTs), which are an integrated mobility support system to assist elderly or disabled people who suffer from impaired mobility. In this paper we describe two elements of the system: environment‐embedded terminals (EETs) and a user‐carrying mobile terminal. The EETs are designed to detect and track all moving objects on the road and sidewalk in a residential area. We are also developing an Intelligent City Walker (ICW) as a user‐carrying mobile terminal. The ICW helps the user avoid collisions using its own resources or alerts from EETs. It also displays various information obtained from all RCT terminals. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(8): 56–67, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20479
Social summarization method for feedback comments in online auction
Authors: Ohno Hanako , Kusumura Yukitaka , Hijikata Yoshinori , Nishida Shogo
Published: May 2006

Online auctions provide feedback comments for sellers written by buyers. Users select which seller to buy a product from by making reference to these comments. However, these feedback comments include a lot of courtesies in addition to being vast in quantity, and so comparing several sellers represents a lot of work for users. To address this problem, in this research the authors propose a method (the Social Summarization method) to summarize seller feedback comments by using social relationships in online auctions. In this method the authors focus one by one on buyers who wrote feedback comments for sellers in order to eliminate courtesy phrases that are not useful for representing the character of a seller. They then compare the feedback comments that a buyer writes for other sellers with the feedback comments that that buyer writes for the target seller. The authors investigate to what extent phrases summarized using their proposed method and using a general method that performs summarization without attention to sellers are different by using the feedback comments from a real online auction. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(8): 38–55, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20502
Basic mechanism of elastic server groups—Dynamic adaptation to load fluctuation
Authors: Agetsuma Masakuni , Kono Kenji , Iwasaki Hideya , Masuda Takashi
Published: May 2006

Various services have been deployed on the Internet, and the role of Internet services as a societal infrastructure is becoming increasingly important. As demand for services on the Internet increases, the burdens placed on servers that provide those services increase, which leads to reductions in the quality of services, such as service delays, or temporary stoppage of services in the worst case. Methods of distributing the demand for a service among multiple computers by preparing multiple computers that are capable of providing the same service is commonly employed as a way of minimizing reduction in the quality of service. However, since the demand for a service on the Internet continually fluctuates, it is difficult to predict the demand in order to have computing resources in place ahead of time. In this paper, a basis is therefore proposed for automatically adjusting the total amount of computing resources for providing a service according to the variation in demand for the service. The server group formed according to this basis is referred to as an elastic server group. In an elastic server group, several computers are working that communicate with each other using a Peer‐to‐Peer system, and the number of computers for providing the service is increased or decreased. In this paper, an elastic server group and a basic mechanism for increasing or decreasing the number of computers for providing a server in the elastic server group are proposed, and the effectiveness of this approach is verified using a simulation. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(8): 24–37, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20520
Thin film growth of TiO2 and Ti2O3 by the new method of liquid injection CVD investigated using optical interferometry, XRD and AFM
Authors: Simcock M. N.
Published: May 2006

The method of liquid injection chemical vapour deposition (LICVD) is a new technique, which is being developed for its potential to allow new material compositions and simpler and more flexible deposition schemes. The potential advantage of this technique is that it is possible to fix the precursor composition(s) in the injection solvent, permitting a simpler injection scheme compared to the current need for bubblers or gaseous precursors in CVD. In our system the precursor solution is rapidly volatilised into a carrier gas stream, which is then passed over the heated substrate. In this initial study we use the single component titanium tetraisopropoxide (TTIP) dissolved in THF for the injection solution, and investigate the behaviour of the deposition with in situ optical reflectometry and ex situ XRD and AFM. The data gained gives information on the growth rate, morphology and crystalline properties of the films. The characteristics of our deposition system are that we find a flux controlled growth mode, changes in the rate of deposition as a function of thickness, which are related to the surface morphology and the growth of Ti2O3 at temperatures above 450 °C. Copyright © 2006 John Wiley & Sons, Ltd.
Testing the equality of two survival functions with right truncated data
Authors: Chi Yunchan , Tsai Wei‐Yann , Chiang Chia‐Ling
Published: May 2006

To compare the survival functions based on right‐truncated data, Lagakoset al.proposed a weighted logrank test based on a reverse time scale. This is in contrast to Bilker and Wang, who suggested a semi‐parametric version of the Mann–Whitney test by assuming that the distribution of truncation times is known or can be estimated parametrically. The approach of Lagakoset al.is simple and elegant, but the weight function in their method depends on the underlying cumulative hazard functions even under proportional hazards models. On the other hand, a semi‐parametric test may have better efficiency, but it may be sensitive to misspecification of the distribution of truncation times. Therefore, this paper proposes a non‐parametric test statistic based on the integrated weighted difference between two estimated survival functions in forward time. The comparative results from a simulation study are presented and the implementation of these methods to a real data set is demonstrated. Copyright © 2006 John Wiley & Sons, Ltd.
Inferences on standardized mean difference: the generalized variable approach
Authors: Tian Lili
Published: May 2006

The standardized mean difference has been widely used as the most common index of effect magnitude in many applied fields. In this paper, we propose a novel approach using the concept of generalized variable for the confidence interval estimation and hypothesis testing of standardized mean difference. Furthermore, we extend this approach to compare standardized mean differences between two studies or between two strata. Simulation results demonstrate that the proposed approach can provide confidence intervals with excellent coverage properties and can perform hypothesis testing with satisfactory type‐I error control. Copyright © 2006 John Wiley & Sons, Ltd.
A singleton failures semantics for Communicating Sequential Processes
Authors: Bolton Christie , Davies Jim
Published: May 2006

This paper defines a new denotational semantics for the language of Communicating Sequential Processes (CSP). The semantics lies between the existing traces and failures models of CSP, providing a treatment of non-determinism in terms of
singleton failures
. Although the semantics does not represent a congruence upon the full language, it is adequate for sequential tests of non-deterministic processes. This semantics corresponds exactly to a commonly used notion of data refinement in Z and Object-Z: an abstract data type is refined when the corresponding process is refined in terms of singleton failures. The semantics is used to explore the relationship between data refinement and process refinement, and to derive a rule for data refinement that is both sound and complete.
Alkaline Reflux Gastritis: Early and Late Results of Surgery
Authors: Zobolas Basile , Sakorafas George H. , Kouroukli Irene , Glynatsis Mikes , Peros George , Bramis John
Published: May 2006

Background

Alkaline gastritis is caused by excessive reflux of alkaline duodenal content into the stomach or gastric remnant following procedures that resect or defunctionalize/deviate the pyloric sphincter. The symptoms may be intractable and surgery may be required in a selected subgroup of patients. The goal of this study was to present our experience regarding surgical management of alkaline reflux gastritis.

Materials and Methods

During a 15‐year period, 26 patients underwent surgery for the management of refractory alkaline reflux gastritis. Preoperative evaluation included a detailed history, endoscopy, and histology; alkaline reflux gastritis was characterized as mild, moderate, or severe based on the results of this evaluation. The patients underwent remedial gastric surgery when conservative management was ineffective and the patient’s symptoms—despite medical treatment—persisted for at least 2 years and affected quality of life. Most patients had previously undergone subtotal gastrectomy/gastrojejunostomy (the Billroth II procedure) (22/26, 84.6%); three patients (11.5%) had vagotomy and gastrojejunostomy, and 1 patient (3.9%) had vagotomy and pyloroplasty. In most patients (14/26, 54%), symptoms appeared 1–3 years after initial gastric surgery. Epigastric pain and bilious vomiting were reported by all (26/26, 100%) and by 25/26 (96%) of patients, respectively, while anemia and weight loss were observed in 11/26 (42.3%) and 18/26 (69.2%), respectively. Severe, moderate, and mild gastritis was present in 12, 9, and 5 patients, respectively. Most patients (18/26, 69%) were treated by Roux‐en‐Y anastomosis, and 8 (31%) by the Tanner (Roux‐19) procedure. Long‐term follow‐up was completed in 23 patients (mean: 7.3 years), by clinical assessment (n = 18), or by questionnaire (n = 5). Results were assessed by using the Visick grading.

Results

One patient died from massive pulmonary embolism (mortality: 3.8%). Morbidity was 57%, with the Roux stasis syndrome being the most frequent complication (n = 9). Both procedures achieved good early results, particularly regarding pain relief and absence of vomiting (84% and 96%, respectively). Endoscopic findings were ameliorated 6 months following surgery, whereas histological changes remained relatively unchanged. Eleven patients (47.8%) reported excellent (Visick I), 9 (39.2%) good, and 3 (13%) unsatisfactory late results.

Conclusions

Remedial gastric surgery was effective and achieved symptom relief in a significant percentage (87%) of our patients. The Roux stasis syndrome is a frequent complication following Roux‐en‐Y reconstruction, but quality of life is significantly improved. Careful patient selection is essential to achieve satisfactory results.