bluuebunny/crossref_metadata_2025 huggingface dataset:
Strain relaxation by 〈100〉 misfit dislocations in dilute nitride InxGa1–xAs1–yNy/GaAs quantum wells
Authors: Young E. C. , Koveshnikov A. N. , Tixier S. , Kavanagh K. L. , Tiedje T.
Published: November 2005

The effect of dilute N alloying and Bi surfactant growth on strain relaxation in highly strained InGaAs single quantum well (QWs) was investigated by using high resolution X‐ray diffraction (HRXRD) and transmission electron microscopy (TEM). Dilute nitride InxGa1–xAs0.99N0.01 QWs of varying thickness, constant lattice mismatch 1.7%, were grown by molecular beam epitaxy on oriented GaAs (001) substrates. Some samples were exposed to a flux of Bi surfactant during the growth procedure, which acts to enhance the N incorporation, increase the optical emission, and create smoother interfaces. The QWs were observed to relax through the formation of pure edge‐type, misfit dislocations aligned with in‐plane 〈100〉 directions. These were found to be directly associated with degradation in the optical emission, however, 1% N addition, with or without Bi surfactant, did not have a detectable effect on the critical thickness nor the rate of this relaxation mechanism. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphology, interface polarity and branching of electrochemically etched pores in InP
Authors: Spiecker E. , Rudel M. , Jäger W. , Leisner M. , Föll H.
Published: November 2005

The 3‐dimensional morphology of individual pores grown in InP(001) by electrochemical etching, their interface polarities and their branching behavior have been investigated by transmission electron microscopy (TEM) in various crystal lattice projections and by convergent‐beam electron diffraction (CBED). Pores start to grow irregularly shaped with preferential orientation perpendicular to the surface. Following this nucleation layer long straight pores with triangular cross‐section grow deep into the crystal along inclined 〈111〉B directions. Along the pore axis the pore diameter oscillates. The morphology of the pore tips can be described approximately by a chain of interconnected tetrahedrons bounded by {111}A‐facets. Some pores show additional {001} facets at the transition regions between the tetrahedrons. With increasing distance from the pore tips the mean pore diameters increase and the pores approach the shape of open prismatic channels with channel walls that are bounded, on the average, by {112}‐planes. Self‐assembling pore branching in all four 〈111〉B crystal directions leads to 3‐dimensional pore arrangements which are of considerable interest for the fabrication of photonic crystals. – We discuss the observed pore morphologies within the framework of a model that describes the pore formation as an interplay of dissolution and surface passivation with the surface passivation being affected by the crystal polarity of the material. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cathodoluminescence spectroscopy of single SnO2 nanowires and nanobelts
Authors: Salviati Giancarlo , Lazzarini Laura , Zha Ming Zheng , Grillo Vincenzo , Carlino Elvio
Published: November 2005

1D semiconducting SnO2 nanoribbons in form of nanowires and nanobelts with a lateral size ranging from 50 to 700 nm and length of several hundreds of micrometers are studied by Cathodoluminescence in the Scanning Electron Microscope and Transmission Electron Microscopy.

Experimental High Angle Annular Dark Field imaging suggests compositional modulations along the 〈100〉 direction in agreement with recent theoretical predictions. Single nanobelt and nanowire cathodoluminescence spectroscopy reveals the presence of a broad emission made of two sub‐bands centered at about 460 nm and 580 nm at room temperature. No near band edge emission is found. This result is assigned to a major role of surface effects with respect to bulk properties. CL spectroscopy carried out at different temperatures and Sn vapour pressure, before and after thermal treatments in Oxygen atmosphere and under electron beam irradiation show that the integrated intensity of the sole emission at 580 nm changes. A red and blue shift of about 20 nm are found respectively for the two bands by decreasing the temperature. A correlation between Oxygen vacancies and the cathodoluminescence emission peak at 580 nm is discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Types and origin of dislocations in large GaAs and InP bulk crystals with very low dislocation densities
Authors: Müller G. , Schwesig P. , Birkmann B. , Härtwig J. , Eichler S.
Published: November 2005

Bulk GaAs and InP crystals with diameter of 4″ or more can now be grown with very low dislocation densities (EPD considerably below 1000 cm–2) using the Vertical Gradient Freeze (VGF) growth technique and rigorous process optimization by the aid of numerical simulation. It turns out that the usually dominating 60°‐dislocations are no longer the dominating type if the dislocation density is in the range of EPD = 100 cm–2 or below. The goal of growing large dislocation‐free GaAs and InP crystals like Si can only be reached if the types of these “residual dislocations” are identified and their origin is fully understood. This paper therefore reviews the present knowledge about these residual dislocations in GaAs and InP for various dopants. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Partial dislocations in wurtzite GaN
Authors: Komninou Ph. , Kioseoglou J. , Dimitrakopulos G. P. , Kehagias Th. , Karakostas Th.
Published: November 2005

The partial dislocations in wurtzite‐structured GaN are reviewed and new results are presented. A multiplicity of partials is possible depending on stacking fault (SF) type, orientation, and interactions. The partials that delimit the I1 intrinsic basal SFs have 5/7, 8, or 12‐atom cores as more probable configurations. The core structures of 90° partial dislocations with 1/6〈20$ \bar 2 $3〉 Burgers vector were studied from high resolution transmission electron microscopy observations in comparison with simulated models obtained from energetic calculations. Two cases were distinguished with one structure involving a 5/7 or 12‐atom ring core and the other an 8‐atom ring core. Another type of partials, in particular dislocations accommodating mirror variants of basal SFs were also studied experimentally. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface orientation as a control parameter for the growth of non‐stoichiometric gallium arsenide
Authors: Marek T. , Schür C. , Kunsági‐Máté S.
Published: November 2005

In order to study the effect of the substrate orientation on the incorporation of excess arsenic into low temperature grown gallium arsenide, we examine molecular beam epitaxial layers grown at constant low substrate temperatures and constant III/V flux ratio on exactly (001) oriented substrates and on vicinal substrates tilted up to 10° towards the 〈111〉A and 〈111〉B directions. Our experiments show that the substrate orientation has a significant influence on the excess arsenic content and thus needs to be considered as an additional parameter to control low temperature growth of gallium arsenide. Respective ab‐initio calculations offer first models for the incorporation of excess arsenic into As antisite and As interstitial positions on misoriented as well as exactly oriented substrates. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room temperature photo‐CVD SiO2 layers on AlGaN and AlGaN/GaN MOS‐HFETs
Authors: Wang C. K. , Chang S. J. , Su Y. K. , Chiou Y. Z. , Lin T. K. , Wong C. C. , Liu H. L. , Chang S. P. , Tang J. J.
Published: November 2005

High quality SiO2 layers were successfully deposited onto AlGaN by photo‐chemical vapor deposition (photo‐CVD) using D2 lamp as the excitation source at room temperature. The resulting interface state density was only 8.86 × 1011 cm–2 eV–1. With a 2 µm gate, it was found that maximum drain–source current, maximum transconductance (gm,max) and gate voltage swing (GVS) of the fabricated nitride‐based metal–oxide–semiconductor heterostructure field effect transistors (MOS‐HFETs) were 225 mA/mm, 33 mS/mm and 6.5 V, respectively. Compared with metal‐semiconductor HFETs (MES‐HFETs), it was found that noise power density of MOS‐HFETs was lower and presented pure 1/f noise with smaller trapping effects. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐consistent calculations of phonon scattering rates in the GaAs transistor structure with one‐dimensional electron gas
Authors: Borzdov A. V. , Pozdnyakov D. V. , Galenchik V. O. , Borzdov V. M. , Komarov F. F.
Published: November 2005

Self‐consistent calculations of acoustic and polar optical phonon scattering rates in GaAs quantum wire transistor structures were carried out with account of collisional broadening. The influence of the gate bias on the scattering rates was examined, too. It was shown that in order to treat the scattering rates rigorously it is important to search for electron energy levels by means of the self‐consistent solution of Schrödinger and Poisson equations and to take into account the collisional broadening. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Electrophilicity Based Analysis of Toxicity of Aromatic Compounds Towards Tetrahymena Pyriformis
Authors: Roy D. R. , Parthasarathi R. , Subramanian V. , Chattaraj P. K.
Published: November 2005

Electrophilicity index is one of the important quantum chemical descriptors in describing toxicity or biological activities of the diverse classes of chemicals to bio‐systems in the context of development of Quantitative Structure Activity Relationship (QSAR). In this study a large number of selected 174 aromatic compounds containing phenols, nitrobenzenes and benzonitriles are chosen as the training set to verify their toxic potency to Tetrahymena pyriformis in the light of electrophilicity. A systematic analysis has been made to find out the electron donation/acceptance nature of these model compounds by comparing their electronegativity values with those of the NA bases/DNA base pairs. The training sets are classified into two groups, viz., the electron donor group comprising 97 phenol derivatives and the electron acceptor group consisting of 77 nitrobenzenes and benzonitriles grouped together. Regression analysis in terms of correlation coefficient ($\rm{ R}$), variance adjusted to degrees of freedom ($\rm{ R_{adj}^2 }$) and variance of leave‐one‐out cross‐validation ($\rm{ R_{CV}^2 }$) has been made for both the electron donor and acceptor aromatic groups to predict the toxicity values of these model compounds to Tetrahymena pyriformis. It is heartening to note that the global and local electrophilicity indices along with the total Hartree‐Fock energy can explain more than 80% of cross‐validation variance of data of those aromatic molecules.
N‐band Hubbard models. III. Boson–fermion and interaction–boson models for high‐Tc superconductivity
Authors: Yamaguchi K. , Nakano M. , Nagao H. , Okumura M. , Yamanaka S. , Kawakami T. , Yamada S. , Yamaki D. , Kitagawa Y. , Takeda R. , Nitta H.
Published: November 2005

In this series of articles (I, II), N‐band Hubbard models have been considered for strongly correlated electron systems, which are realized in d–p, π–d, π–R, and σ–R conjugated systems. The magnetism and superconductivity of these systems have been elucidated in terms of effective exchange integrals (J), which are calculated by first‐principle methods. In part III of this series, the BCS–BEC crossover theory, has been introduced to elucidate the physical foundation of our J and JP model for the high‐Tc superconductivity (HTSC). The boson–fermion (BF) model for this theory is found useful for a reasonable explanation of the experimental phase diagrams of HTSC. The underlying physics of the BF model is different from that of the slave boson field‐theoretical model assuming spinon–holon condensations in the low dimension. The interaction boson model (IBM) for nuclear matter is also employed to describe the cooperative mechanisms of electron–phonon (EP), spin fluctuation (SF), charge fluctuation (CF), and many‐bands (MB) effects. This phenomenological model is useful for pictorial understanding and for the theoretical explanation of the cooperative mechanisms: (EP + SF), (SF + CF), (EP + SF + MB), etc. These are also investigated in analogy to BF model of fermionic gases, where the Feshbach resonance between boson and fermion is responsible for their coupling. The implications of these theoretical results are discussed in relation to recent ALPES and STM experiments for HTSC, which suggest the contributions of SF (J) and EP (P) interactions. The recently discovered superconductivity of boron‐doped diamond is examined as an example of two‐band sigma‐radical (σ–R) conjugated systems. Finally, the bipolaron model is briefly discussed in relation to boson–fermion model via EP interaction to superconductivity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Electronic structure of BeH2
Authors: Penotti Fabio E.
Published: November 2005

Nonorthogonal single‐configuration and multiconfiguration ab initio calculations are carried out on the BeH2 molecule in its equilibrium (D∞h) geometry, using a highly optimized even‐tempered Slater‐type orbital (STO) basis set. The results are used as a basis for a discussion of the electronic structure of the molecule in modern‐VB terms. A value of Re = 1.329 Å is obtained. Values are also obtained for the symmetric‐stretch harmonic frequency (2053 cm−1), electric quadrupole moment (−5.60 Buckingham), and nuclear quadrupole coupling constants (−3.59 MHz for 9Be and 0.0915 MHz for 2H). © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Ab initio calculations and analysis of chemical bonding in SrTiO3 and SrZrO3 cubic crystals
Authors: Evarestov R. A. , Tupitsyn I. I. , Bandura A. V. , Alexandrov V. E.
Published: November 2005

The possibility of the different first‐principles methods to describe the chemical bonding in SrTiO3 and SrZrO3 cubic crystals is investigated. The local properties of the electronic structure (atomic charges, bond orders, atomic delocalization indexes, and polarization fractions) were calculated with different methods: traditional Mulliken population analysis in LCAO calculations, two projection techniques in plane‐wave (PW) calculations, population analysis based on Wannier‐type atomic orbitals, and chemical bonding analysis based on the localized Wannier functions for occupied (valence band) LCAO states. All the techniques considered except the traditional Mulliken analysis demonstrate that the ionicity of chemical bonding in SrZrO3 is larger than in SrTiO3, in agreement with the Zr and Ti electronegativities relation and the relative bandgaps observed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Potential energy surface of thionylimide
Authors: Bharatam P. V. , Amita  , Kaur D. , Senthil Kumar P.
Published: November 2005

The potential energy surface (PES) of thionylimide has been searched using ab initio MO and density functional calculations. The electronic structures of the isomers of HNSO have been studied using the HF/6‐31+G*, MP2(full)/6‐31+G*, and B3LYP/6‐31+G* levels. Final energies of these molecules have been calculated at the high‐accuracy G2 and CBS‐Q levels. The probable pathways of isomerization of thionylimide to its isomers (e.g., thiocyanic acid, HONS, nitrosothiols) have been explored by studying the three‐ or four‐membered transition states. This study identified total eight possible isomers (1–8) of HNSO, of which four (1–4) have already been realized experimentally. Of the remaining four (5–8), at least two (5, 7) can be generated experimentally. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
An integrated strategy for identification and relative quantification of site‐specific protein phosphorylation using liquid chromatography coupled to MS2/MS3
Authors: Wolschin Florian , Lehmann Ute , Glinski Mirko , Weckwerth Wolfram
Published: November 2005

Reversible and differential multisite protein phosphorylation is an important mechanism controlling the activity of cellular proteins. Here we describe a robust and highly selective approach for the identification and relative quantification of site‐specific phosphorylation events. This integrated strategy has three major parts: visualisation of phosphorylated proteins using fluorescently stained polyacrylamide gels, determination of the phosphorylation site(s) using automatic MS3 triggered by the loss of phosphoric acid, and relative quantification of phosphorylation by integrating MS2‐ and MS3‐extracted ion traces using a fast‐scanning, linear ion trap mass spectrometer. As a test case, recombinant sucrose‐phosphate synthase (SPS) from Arabidopsis thaliana (At5g1110) was used for identification and quantification of site‐specific phosphorylation. The identified phosphorylation site of the actively expressed protein coincides with the major regulatory in vivo phosphorylation site in spinach SPS. Site‐specific differential in vitro phosphorylation of native protein was demonstrated after incubation of the recombinant protein with cold‐adapted plant leaf extracts from A. thaliana, suggesting regulatory phosphorylation events of this key enzyme under stress response. Copyright © 2005 John Wiley & Sons, Ltd.
Application of combined high‐performance thin‐layer chromatography immunostaining and nanoelectrospray ionization quadrupole time‐of‐flight tandem mass spectrometry to the structural characterization of high‐ and low‐affinity binding ligands of Shiga toxin 1
Authors: Meisen Iris , Friedrich Alexander W. , Karch Helge , Witting Ute , Peter‐Katalinić Jasna , Müthing Johannes
Published: November 2005

Shiga toxin 1 (Stx1) represents an AB5 toxin produced by enterohemorrhagic Escherichia coli, which cause gastrointestinal diseases in humans that are often followed by potentially fatal systemic complications, such as acute encephalopathy and hemolytic uremic syndrome. The expression of the preferential Stx1 receptor, Gb3Cer/CD77 (Galα1‐4Galβ1‐4Glcβ1‐1Cer), is one of the primary determinants of susceptibility to tissue injury. Due to the clinical importance of this life‐threatening toxin, a combined strategy of preparative high‐performance thin‐layer chromatography (HPTLC) overlay assay and mass spectrometry was developed for the detection and structural characterization of Stx1‐binding glycosphingolipids (GSLs). A preparation of neutral GSLs from human erythrocytes, comprising 21.4% and 59.1% of the high‐ and low‐affinity Stx1‐binding ligands Gb3Cer/CD77 and Gb4Cer, respectively, was separated on silica gel precoated HPTLC plates and probed for the presence of Stx1 receptors. Stx1 positive on the one hand and anti‐Gb3Cer/CD77 and anti‐Gb4Cer antibody positive bands from parallel reference runs on the other hand were extracted with chloroform/methanol/water (30/60/8, v/v/v). These crude extracts were used without any further purification for a detailed structural analysis by nanoelectrospray ionization quadrupole time‐of‐flight mass spectrometry (nanoESI‐QTOF‐MS) in the negative ion mode. In all extracts investigated, neutral GSLs were detected as singly charged deprotonated molecular ions, [M–H]−, and neither buffer‐derived salt adducts nor coextracted contaminants from the overlay assay procedure or the silica gel layer were observed. For the structural characterization of Stx1‐ and antibody‐binding GSLs low‐energy collision‐induced dissociation (CID) was applied to high and low abundant receptor species of the crude extracts. All MS/MS spectra obtained contained full series of Y‐type ions, B‐type ions and additional ions generated by ring cleavages of the sugar moiety. Only analytical quantities in the microgram scale of a single GSL species within the complex GSL mixture were required for the structural MS characterization of Stx1 ligands as Gb3Cer/CD77 and Gb4Cer. This effective combined HPTLC/MS procedure offers a broad range of applications, not only for toxins of bacterial origin, but also for any GSL‐binding agents such as plant‐derived lectins or human proteins with yet unknown binding specificities. Copyright © 2005 John Wiley & Sons, Ltd.
A technical challenge for robot‐assisted minimally invasive surgery: precision surgery on soft tissue
Authors: Stallkamp J , Schraft R D
Published: November 2005

In minimally invasive surgery, a higher degree of accuracy is required by surgeons both for current and for future applications. This could be achieved using either a manipulator or a robot which would undertake selected tasks during surgery. However, a manually‐controlled manipulator cannot fully exploit the maximum accuracy and feasibility of three‐dimensional motion sequences. Therefore, apart from being used to perform simple positioning tasks, manipulators will probably be replaced by robot systems more and more in the future. However, in order to use a robot, accurate, up‐to‐date and extensive data is required which cannot yet be acquired by typical sensors such as CT, MRI, US or common x‐ray machines. This paper deals with a new sensor and a concept for its application in robot‐assisted minimally invasive surgery on soft tissue which could be a solution for data acquisition in future. Copyright © 2005 Robotic Publications Ltd.
MBARS: mini bone‐attached robotic system for joint arthroplasty
Authors: Wolf A , Jaramaz B , Lisien B , DiGioia A M
Published: November 2005

A report on a new active, miniature bone‐attached, robotic system including its design, high level and low level control, is given together with a description of the system implementation and first experimental use. The system is capable of preparing the bone cavity for an implant during joint arthroplasty procedures. Without loss of generality, the report describes the implementation of the system for a Patellofemoral Joint Replacement procedure. The system is image‐free and all planning is performed intra‐operatively in the robot coordinate system, eliminating the need for external tracking systems in the operating room. Experiments were conducted using the first robot prototype and the results supported the feasibility of the concept. The methodology which is presented can be modified to other orthopaedic procedures and could improve the results in terms of accuracy and operational time. Moreover, it enables minimally invasive procedures and use of the next generation of more anatomically shaped implants. Copyright © 2005 Robotic Publications Ltd.
Mechanisms of action of ribavirin against distinct viruses
Authors: Graci Jason D. , Cameron Craig E.
Published: November 2005

The nucleoside analogue ribavirin has antiviral activity against many distinct viruses both in vitro and in vivo. Five distinct mechanisms have been proposed to explain the antiviral properties of ribavirin. These include both indirect mechanisms (inosine monophosphate dehydrogenase inhibition, immunomodulatory effects) and direct mechanisms (interference with RNA capping, polymerase inhibition, lethal mutagenesis). Recent concerns about bioterrorism have renewed interest in exploring the antiviral activity of ribavirin against unique viruses. In this paper, we review the proposed mechanisms of action with emphasis on recent discoveries, as well as the implications of ribavirin resistance. Evidence exists to support each of the five proposed mechanisms of action, and distinct virus/host combinations may preferentially favour one or more of these mechanisms during antiviral therapy. Copyright © 2005 John Wiley & Sons, Ltd.
Acquisition of human cytomegalovirus infection in infants via breast milk: natural immunization or cause for concern?
Authors: Schleiss Mark R.
Published: November 2005

Since the recognition in the 1960s that human cytomegalovirus (HCMV) infections could be transmitted by breast milk, there has been relatively little attention paid to the potential medical consequences of such infections. Indeed, since HCMV infections acquired by healthy newborn infants appear to be largely asymptomatic in nature, there has been no real incentive to develop or implement strategies to prevent transmission by this route. However, recent studies have identified a significant risk for low‐birth weight, premature infants for the development of HCMV disease following acquisition of infection via breast milk. Such infections may cause considerable short‐term morbidity and, in some cases, severe, life‐threatening illness. There is little consensus amongst neonatologists on the approach to prevention and management of such infections. This review summarises the epidemiology and natural history of HCMV infections acquired via breast milk, and outlines available strategies for prevention and management of such infections, as well as opportunities for future clinical research on this understudied topic. Copyright © 2005 John Wiley & Sons, Ltd.
Exploring optimal solution to hardware/software partitioning for synchronous model
Authors: He Jifeng , Hung Dang Van , Pu Geguang , Qiu Zongyan , Yi Wang
Published: November 2005

Computer aided hardware/software partitioning is one of the key challenges in hardware/software co-design. This paper describes a new approach to hardware/software partitioning for a synchronous communication model including multiple hardware devices. We transform the partitioning into a reachability problem of timed automata. By means of an optimal reachability algorithm, the optimal solution can be obtained with limited resources in hardware. To relax the initial condition of the partitioning for optimization, two algorithms are designed to explore the dependency relations among processes in the sequential specification. Moreover, we propose a scheduling algorithm to improve the synchronous communication efficiency further after partitioning stage. Some experiments are conducted with the model checker UPPAAL to show our approach is both effective and efficient.
Expansion of the geographical distribution of an exotic ladybird beetle,Adalia bipunctata(Coleoptera: Coccinellidae), and its interspecific relationships with native ladybird beetles in Japan
Authors: Toda Yuko , Sakuratani Yasuyuki
Published: November 2005

The first record of the exotic ladybird beetle,Adalia bipunctata(Coleoptera; Coccinellidae), in Japan was in 1993 at Osaka Nanko Central Park. Since that time, studies on the life history and geographical distribution ofA. bipunctatahave been ongoing, and its establishment in the Osaka Nanko area has been confirmed.A. bipunctatais a predacious ladybird beetle and a member of a guild that overlaps in habitat and prey with that of native ladybird beetles such asHarmonia axyridisandMenochilas sexmaculatus. We investigated the distribution ofA. bipunctataand its interspecific relationships with native predacious ladybird beetles. In some areas,A. bipunctatawas dominant in interspecific relationships with native ladybird beetles. For the first 10 years afterA. bipunctatawas discovered, it occurred only in the Osaka Nanko area, but the present geographical distribution indicates that it has expanded its range. Though the population density of this species was highest at the area recorded first, and tended to decrease in inverse proportion to the distance from Osaka Nanko Central Park, a satellite occurrence was observed in a remote area. The numbers of aphid and tree species (leaf shelter for aestivation and over‐wintering) utilized byA. bipunctatahave recently increased. Such increases will cause the rate of distribution ofA. bipunctatato accelerate. Interspecific competition betweenH. axyridisandA. bipunctata, which occurs earlier thanH. axyridis, may be avoided by desynchronization of the occurrence seasons, and another common predacious ladybird beetle,Coccinella septempunctata, may escape interspecific competition by habitat segregation.
Measuring spiritual belief: development and standardization of a Beliefs and Values Scale
Authors: KING MICHAEL , JONES LOUISE , BARNES KELLY , LOW JOSEPH , WALKER CARL , WILKINSON SUSIE , MASON CHRISTINA , SUTHERLAND JULIETTE , TOOKMAN ADRIAN
Published: November 2005

Background. Higher levels of religious involvement are modestly associated with better health, after taking account of other influences, such as age, sex and social support. However, little account is taken of spiritual beliefs that are not tied to personal or public religious practice. Our objective was to develop a standardized measure of spirituality for use in clinical research.

Method. We characterized the core components of spirituality using narrative data from a purposive sample of people, some of whom were near the end of their lives. These data were developed into statements in a scale to measure strength of spiritual beliefs and its reliability, validity and factor structure were evaluated in order to reach a final version.

Results. Thirty-nine people took part in the qualitative study to define the nature of spirituality in their lives. These data were used to construct a 47-item instrument that was evaluated in 372 people recruited in medical and non-medical settings. Analysis of these statements led to a 24-item version that was evaluated in a further sample of 284 people recruited in similar settings. The final 20-item questionnaire performed with high test–retest and internal reliability and measures spirituality across a broad religious and non-religious perspective.

Conclusions. A measure of spiritual belief that is not limited to religious thought, may contribute to research in psychiatry and medicine.
Impedance control of a two degree-of-freedom planar flexible link manipulator using singular perturbation theory
Authors: Vossoughi G. R. , Karimzadeh A.
Published: November 2005

In this article, impedance control of a two link flexible link manipulators is addressed. The concept of impedance control of flexible link robots is rather new and is being addressed for the first time by the authors. Impedance Control provides a universal approach to the control of flexible robots, in both constrained and unconstrained maneuvers. The initial part of the paper concerns the use of Hamilton's principle to derive the mathematical equations governing the dynamics of joint angles, vibration of the flexible links and the constraining forces. The approximate elastic deformations are then derived by means of the Assumed-Mode-Method (AMM). Using the singular perturbation method, the dynamic of the manipulator is decomposed into fast and slow subsystems. The slow dynamic corresponds to the rigid manipulator and the fast dynamic is due to vibrations of flexible links. The sliding mode control (SMC) theory has been used as the means to achieve the 2nd order target impedance for the slow dynamics. A controller based on state feedback is also designed to stabilize the fast dynamics. The composite controller is constructed by using the slow and fast controllers. Simulation results for a 2-DOF robot in which only the 2nd link is flexible confirm that the controller performs remarkably well under various simulation conditions.
Optimal kinematic design of a three translational DoFs parallel manipulator
Authors: Liu Xin-Jun
Published: November 2005

In this paper, an optimal kinematic design method of a three translational DoFs parallel manipulator is presented. The design is based on the concept of performance chart, which can show the relationship between a criterion and design parameters graphically and globally. The normalization on the design parameters of the studied manipulator makes it possible that the design space, which is made up of the normalized parameters, is limited. The design space includes of all possible basic similarity manipulators (BSMs). As any one of the BSMs represents all of its similarity manipulators (SMs) in terms of performances, if one BSM is optimal, its SMs are optimized as well. The said optimal BSM is from the optimum region, which is the intersecting result of involved performance charts. In this paper, the related performance criteria are good-conditioning workspace (GCW), global conditioning index (GCI) and global stiffness index (GSI). As an applying example, a design result of the parallel manipulator with a desired task workspace is presented. The results of the paper are very useful for the design and application of a parallel manipulator.
Emergence of a dynamic pattern in wall-bouncing juggling: self-organized timing selection for rhythmic movement
Authors: Hirai Hiroaki , Miyazaki Fumio
Published: November 2005

This paper describes a hierarchical architecture for rhythmic movement generation, which suits a juggling-like task involving sensory-motor coordination. Our approach, which is interpreted as a “bidirectional weak coupling” to the environment, does not require a continuous monitoring of the environment, but can adapt a robot to a change in the environment, owing to the interaction between the robot and the environment at the ball contact. The proposed architecture contains two passive-control mechanisms, the “entrainment mechanism” and the “open-loop stable mechanism,” that lead to the emergence of a self-organized temporal order in the whole system. This dynamic temporal pattern enables a robot to perform a stable rhythmic movement. We demonstrate a robot which juggles two balls rebounding off the wall and confirm the effectiveness of our approach.
Analysis of robot collision characteristics using the concept of the collision map
Authors: Park Seung Hwan , Lee Beom Hee
Published: November 2005

Robot collision characteristics are analyzed by using the idea of the collision map. This analysis consists of the translations of the collision region on the collision map and they correspond to parallel movements of the original robot path. These translations are investigated in several cases and applied to general situations in which two robots are moving or working in a common workspace. Also, the collision characteristics are analyzed for a few special situations where the analysis of collision characteristics is crucial and the resultant solution for collision avoidance can be obtained.
Detection of intra-familial transmission of shigella infection using conventional serotyping and pulsed-field gel electrophoresis
Authors: KHAN A. I. , TALUKDER K. A. , HUQ S. , MONDAL D. , MALEK M. A. , DUTTA D. K. , NAIR G. B. , FARUQUE A. S. G.
Published: November 2005

Pulsed-field gel electrophoresis (PFGE) is commonly used in molecular epidemiology. However, this technique has never been used in studying intra-family spread of enteric diseases in Bangladesh. Our objective was to evaluate the intra-familial transmission of shigella infection using PFGE. Children of either sex, less than 10 years old, who were family contacts of shigella-infected index cases were the study population. PFGE was applied if the same serotypes/sub-serotypes of shigella were isolated from both the index case and the family contact children. In total, 227 index cases were studied. Shigella was isolated from 61 (27%) contact children on day 1 of enrolment, among which Shigella flexneri (41%) and S. boydii (41%) were dominant, followed by S. dysenteriae (10%), S. sonnei (3%), and shigella-like organisms (5%). Seventeen (28%) of the asymptomatic infections in contact children were caused by the same serotype of shigella as that found in the index case. The intra-familial shigella transmission rate was 8% (17/227). Of the 227 contact children, eight (4%) developed diarrhoea during a 10-day follow-up and shigella was isolated from five (2%) of these children, and three of them (S. flexneri 3a, 1b, and 3a) were identical to the strains from their respective index cases. Compared to children without asymptomatic carriage of shigella (2/166), the risk (odds ratio) of developing diarrhoea for the children with asymptomatic carriage of shigella identical to their cases (3/17) was 9·0 (95% CI 1·5–49·0, P=0·01). The attributable risk for symptomatic shigella infection by intra-familial transmission was 50%. Results of this study demonstrated that intra-familial transmission of shigella carries a higher risk for diarrhoea.
Changes in the epidemiology of epiglottitis following introduction of Haemophilus influenzae type b (Hib) conjugate vaccines in England: a comparison of two data sources
Authors: McVERNON J. , SLACK M. P. E. , RAMSAY M. E.
Published: November 2005

Paediatric cases of epiglottitis declined markedly in England following the introduction of safe effective immunization against Haemophilus influenzae type b (Hib). With the recently described resurgence in Hib infections, a corresponding rise in the number of presentations of clinical epiglottitis in children was observed, although numbers were still well below those reported prior to vaccine availability. This was seen both in microbiology reports and hospital admissions data for England. In keeping with the more diverse aetiology of epiglottitis in adults, Hib vaccination had minimal impact on hospital presentations with upper airway infections in those aged 15 years and over, which showed an overall increasing trend over 10 years. The need for a high index of suspicion to allow early diagnosis of this life-threatening clinical presentation is reinforced.
Risk factors for typhoid fever among adult patients in Diyarbakir, Turkey
Authors: HOSOGLU S. , CELEN M. K. , GEYIK M. F. , AKALIN S. , AYAZ C. , ACEMOGLU H. , LOEB MARK
Published: November 2005

We conducted a case-control study to assess risk factors for typhoid fever in Diyarbakir, Turkey, a region where transmission of Salmonella typhi is endemic. We prospectively identified febrile patients from Diyarbakir and the surrounding area who were admitted to hospital. Cases were defined as patients who had S. typhi isolated from at least one blood culture. Sixty-four cases with blood culture-confirmed S. typhi were identified between May 2001 and May 2003. In total, 128 age- and sex-matched controls selected from neighbourhoods as cases were enrolled. We hypothesized that consumption of raw vegetables contaminated with sewage would be associated with an increased risk of typhoid fever. Conditional logistic regression modelling revealed that living in a crowded household (OR 3·31, 95% CI 1·58–6·92, P=0·002), eating cig kofte (a traditional raw food) (OR 5·29, 95% CI 2·20–12·69, P=0·000) and lettuce salad (OR 3·55, 95% CI 1·52–8·28, P=0·003) in the 15 days prior to symptoms onset was independently associated with typhoid fever. We conclude that living in a crowded household and consumption of raw vegetables outside the home increase the risk of typhoid fever in this region.
Estrogen and hippocampal synaptic plasticity
Authors: FOY MICHAEL , BAUDRY MICHEL , THOMPSON RICHARD
Published: November 2005

During the past several years, there has been increasing interest in the effects of estrogen on neural function. This enthusiasm is driven, in part, by the results of early clinical studies suggesting that estrogen therapy given after menopause may prevent, or at least delay, the onset of Alzheimer's disease in older women. However, later clinical trials of women with probable Alzheimer's disease had contrary results. Much of the current research related to estrogen and brain function is focused in two directions. One involves clinical studies that examine the potential of estrogen in protecting against cognitive decline during normal aging and against Alzheimer's disease (neuroprotection). The other direction, which is the primary focus of this review, involves laboratory studies that examine the mechanisms by which estrogen can modify the structure of nerve cells and alter the way neurons communicate with other cells in the brain (neuroplasticity). In this review, we examine recent evidence from experimental and clinical research on the rapid effects of estrogen on several mechanisms that involve synaptic plasticity in the nervous system, including hippocampal excitability, long-term potentiation and depression related to sex and aging differences, cellular neuroprotection and probable molecular mechanisms of the action of estrogen in brain tissue.
Neurotrophin signaling among neurons and glia during formation of tripartite synapses
Authors: ELMARIAH SARINA B. , HUGHES ETHAN G. , OH EUN JOO , BALICE-GORDON RITA J.
Published: November 2005

Synapse formation in the CNS is a complex process that involves the dynamic interplay of numerous signals exchanged between pre- and postsynaptic neurons as well as perisynaptic glia. Members of the neurotrophin family, which are widely expressed in the developing and mature CNS and are well-known for their roles in promoting neuronal survival and differentiation, have emerged as key synaptic modulators. However, the mechanisms by which neurotrophins modulate synapse formation and function are poorly understood. Here, we summarize our work on the role of neurotrophins in synaptogenesis in the CNS, in particular the role of these signaling molecules and their receptors, the Trks, in the development of excitatory and inhibitory hippocampal synapses. We discuss our results that demonstrate that postsynaptic TrkB signaling plays an important role in modulating the formation and maintenance of NMDA and GABAA receptor clusters at central synapses, and suggest that neurotrophin signaling coordinately modulates these receptors as part of mechanism that promotes the balance between excitation and inhibition in developing circuits. We also discuss our results that demonstrate that astrocytes promote the formation of GABAergic synapses in vitro by differentially regulating the development of inhibitory presynaptic terminals and postsynaptic GABAA receptor clusters, and suggest that glial modulation of inhibitory synaptogenesis is mediated by neurotrophin-dependent and -independent signaling. Together, these findings extend our understanding of how neuron–glia communication modulates synapse formation, maintenance and function, and set the stage for defining the cellular and molecular mechanisms by which neurotrophins and other cell–cell signals direct synaptogenesis in the developing brain.
Astrocyte activation of presynaptic metabotropic glutamate receptors modulates hippocampal inhibitory synaptic transmission
Authors: LIU QING-SONG , XU QIWU , KANG JIAN , NEDERGAARD MAIKEN
Published: November 2005

In the CNS, fine processes of astrocytes often wrap around dendrites, axons and synapses, which provides an interface where neurons and astrocytes might interact. We have reported previously that selective Ca2+ elevation in astrocytes, by photolysis of caged Ca2+ by o-nitrophenyl-EGTA (NP-EGTA), causes a kainite receptor-dependent increase in the frequency of spontaneous inhibitory post-synaptic potentials (sIPSCs) in neighboring interneurons in hippocampal slices. However, tetrodotoxin (TTX), which blocks action potentials, reduces the frequency of miniature IPSCs (mIPSCs) in interneurons during Ca2+ uncaging by an unknown presynaptic mechanism. In this study we investigate the mechanism underlying the presynaptic inhibition. We show that Ca2+ uncaging in astrocytes is accompanied by a decrease in the amplitude of evoked IPSCs (eIPSCs) in neighboring interneurons. The decreases in eIPSC amplitude and mIPSC frequency are prevented by CPPG, a group II/III metabotropic glutamate receptor (mGluR) antagonist, but not by the AMPA/kainate and NMDA receptor antagonists CNQX/CPP. Application of either the group II mGluR agonist DCG IV or the group III mGluR agonist L-AP4 decreased the amplitude of eIPSCs by a presynaptic mechanism, and both effects are blocked by CPPG. Thus, activation of mGluRs mediates the effects of Ca2+ uncaging on mIPSCs and eIPSCs. Our results indicate that Ca2+-dependent release of glutamate from astrocytes can activate distinct classes of glutamate receptors and differentially modulate inhibitory synaptic transmission in hippocampal interneurons.
The glial antioxidant network and neuronal ascorbate: protective yet permissive for H2O2 signaling
Authors: AVSHALUMOV MARAT V. , MACGREGOR DUNCAN G. , SEHGAL LILLY M. , RICE MARGARET E.
Published: November 2005

Increasing evidence implicates reactive oxygen species, particularly hydrogen peroxide (H2O2), as intracellular and intercellular messengers in the brain. This raises the question of how the antioxidant network in the brain can be sufficiently permissive to allow messages to be conveyed yet, at the same time, provide adequate protection against oxidative damage. Here we present evidence that this is accomplished in part by differential antioxidant compartmentalization between glia and neurons. Based on the rationale that the glia-to-neuron ratio is higher in guinea-pig brain than in rat brain, we examined the neuroprotective role of the glial antioxidant network by comparing the consequences of H2O2 elevation in slices of guinea-pig and rat brain. The effects of exogenously applied H2O2 on evoked population spikes in hippocampal slices and on edema formation in forebrain slices were assessed. In contrast to the epileptiform activity observed in rat hippocampal slices after H2O2 exposure, no pathophysiology was seen in guinea-pig hippocampal slices. Similarly, elevated H2O2 caused edema in rat brain slices but not in guinea-pig brain tissue. The resistance of guinea-pig brain tissue to H2O2 challenge was lost, however, when glutathione (GSH) synthesis was inhibited (by buthionine sulfoximine), GSH peroxidase activity was inhibited (by mercaptosuccinate) or catalase was inhibited (by 3-amino-1, 2, 4, -triazole). Strikingly, exogenously applied ascorbate, a predominantly neuronal antioxidant, could compensate for the loss of any other single component of the antioxidant network. Together, these data imply significant roles for glial antioxidants and neuronal ascorbate in the prevention of pathophysiological consequences of the endogenous neuromodulator H2O2.
Three‐dimensional numerical simulations of mantle flow beneath mid‐ocean ridges
Authors: Morency C. , Doin M.‐P. , Dumoulin C.
Published: November 2005

We perform three‐dimensional (3‐D) numerical simulations of an oceanic lithosphere cooling above a convective mantle to investigate mantle flow geometry and its associated lithospheric features. A constant horizontal velocity (half spreading velocity) of 2 (or 4) cm/yr is applied at the box surface to mimic plate motion. In all cases, because of the temperature‐dependent viscosity, a rigid conductive lithosphere cools progressively beneath the two plates separated by the ridge. After 16–40 Ma, cold downgoing instabilities develop at the base of the lithosphere. Small‐scale convection is then superimposed on the large‐scale circulation. It produces, and then interacts with, a slowly evolving short‐wavelength isotherms topography at the base of the lithosphere. The influence of the imposed ridge geometry on the mantle flow appears by comparison of simulations with case A, a linear ridge perpendicular to the plate motion; case B, a linear ridge strongly oblique to the plate motion; and case C, a ridge with transform faults along the spreading center with a mean orientation strongly oblique to the plate motion. All simulations reveal complex interaction between the isotherm topography within the base of the lithosphere, the small‐scale flow generated at or just below the base of the lithosphere, and the large‐scale flow dominating in the mantle below. The large‐scale flow appears always controlled by the mean ridge axis direction and thus may be oblique to the imposed plate motion direction. It is enhanced by the instabilities development. We argue that the large‐scale flow orientation results from the interaction with the small‐scale velocity field which flows down the isotherm topography at the base of the lithosphere. The latter is either inherited (lithospheric cooling, transform faults) or develops as boundary layer instabilities.