bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and characterization of sulfonated polyimides containing aliphatic linkages in the main chain
Authors: Jang Wonbong , Kim Dowan , Choi Seunghyuk , Shul Yong Gun , Han Haksoo
Published: June 2006

A series of six‐membered sulfonated polyimides with aliphatic linkages (SPIAs) was successfully synthesized using 1,4,5,8‐naphthalenetetracarboxylic dianhydride (NTDA), 4,4′‐diaminobiphenyl 2,2′‐disulfonic acid (BDSA) as the sulfonated diamine, and aliphatic diamines H2N(CH2)nNH2 where n = 6, 8, 10, 12. These SPIAs were evaluated for thermal stability, ion exchange capacity (IEC), water uptake, proton conductivity, and hydrolytic stability. Proton conductivity and hydrolytic stability of the SPIAs were compared with the fully aromatic polyimide (MDA‐SPI) prepared from 4,4′‐methylenedianiline (MDA), BDSA, and NTDA. All the SPIAs exhibited high thermal stability. As the chain length of the aliphatic diamine decreased, the IEC and water uptake of the SPIAs increased. The SPIAs showed higher proton conductivity than commercially available membranes such as Nafion 117 at high temperatures and higher proton conductivity than MDA‐SPI at all temperatures. All SPIAs exhibited a hydrolytic stability more than twice as high as that of MDA‐SPI. Copyright © 2006 Society of Chemical Industry
Proteomic dissection of plant development
Authors: Hochholdinger Frank , Sauer Michaela , Dembinsky Diana , Hoecker Nadine , Muthreich Nils , Saleem Muhammad , Liu Yan
Published: June 2006

Plant development is controlled by complex endogenous genetic programs and responses to environmental cues. Proteome analyses have recently been introduced to plant biology to identify proteins instrumental in these developmental processes. To date most plant proteome studies have been employed to generate reference maps of the most abundant soluble proteins of plant organs at a defined developmental stage. However, proteomics is now also utilized for genetic studies comparing the proteomes of different plant genotypes, for physiological studies analyzing the influences of exogenous signals on a particular plant organ, and developmental studies investigating proteome changes during development. Technical advances are now beginning to allow a proteomic dissection of individual cell types, thus greatly increasing the information revealed by proteome analyses.
Determination of dihedral Ψ angles in large proteins by combining NHN/CαHα dipole/dipole cross‐correlation and chemical shifts
Authors: Loth Karine , Abergel Daniel , Pelupessy Philippe , Delarue Marc , Lopes Philippe , Ouazzani Jamal , Duclert‐Savatier Nathalie , Nilges Michael , Bodenhausen Geoffrey , Stoven Véronique
Published: June 2006

We propose a strategy based on the combination of experimental NHN/CαHα dipole/dipole cross‐correlated relaxation rates and chemical shift analysis for the determination of Ψ torsion angles in proteins. The method allows the determination of a dihedral angle that is not easily accessible by nuclear magnetic resonance (NMR). The measurement of dihedral angle restraints can be used for structure calculation, which is known to improve the quality of NMR structures. The method is of particular interest in the case of large proteins, for which spectral assignment of the nuclear Overhauser effect spectra, and therefore straightforward structural determination, is out of reach. One advantage of the method is that it is reasonably simple to implement, and could be used in association with other methods aiming at obtaining structural information on complex systems, such as residual dipolar coupling measurements. An illustrative example is analyzed in the case of the 30‐kDa protein 6‐phosphogluconolactonase. Proteins 2006. © 2006 Wiley‐Liss, Inc.
Multiagent reinforcement learning with the partly high‐dimensional state space
Authors: Fujita Kazuyuki , Matsuo Hiroshi
Published: June 2006

One method of designing a multiagent system is called multiagent reinforcement learning. In multiagent reinforcement learning, an agent also observes the other agents as part of the environment. As a result, as the number of agents increases, the state space increases exponentially (curse of dimensionality), and the learning speed decreases dramatically. The amount of memory required for learning also becomes enormous. Modular Q‐learning, which was proposed as a technique for solving this problem, has the disadvantage that the learning performance decreases due to the incompleteness of perception. In the current research, the authors propose the HMQL technique for improving the learning performance of Modular Q‐learning by using a method of partially increasing the dimensionality of the state space. © 2006 Wiley Periodicals, Inc. Syst Comp Jpn, 37(9): 22–31, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20526
A normalised scale for structural genomics target ranking: The OB‐Score
Authors: Overton Ian M. , Barton Geoffrey J.
Published: June 2006

Target selection and ranking is fundamental to structural genomics. We present a Z‐score scale, the “OB‐Score”, to rank potential targets by their predicted propensity to produce diffraction‐quality crystals. The OB‐Score is derived from a matrix of predicted isoelectric point and hydrophobicity values for nonredundant PDB entries solved to ⩽3.0 Å against a background of UniRef50. A highly significant difference was found between the OB‐Scores for TargetDB test datasets. A wide range of OB‐Scores was observed across 241 proteomes and within 7868 PfamA families; 73.4% of PfamA families contain ⩾1 member with a high OB‐Score, presenting favourable candidates for structural studies.
A World of Opportunity and Influence
Authors: Russo Mark F.
Published: June 2006

“ALA is proud of JALA's online affiliations, and pleased with the pace of growth it continues to experience within each of them.”
Source authoring for multilingual generation of personalised object descriptions
Authors: ANDROUTSOPOULOS I. , OBERLANDER J. , KARKALETSIS V.
Published: June 2006

We present the source authoring facilities of a natural language generation system that produces personalised descriptions of objects in multiple natural languages starting from language-independent symbolic information in ontologies and databases as well as pieces of canned text. The system has been tested in applications ranging from museum exhibitions to presentations of computer equipment for sale. We discuss the architecture of the overall system, the resources that the authors manipulate, the functionality of the authoring facilities, the system's personalisation mechanisms, and how they relate to source authoring. A usability evaluation of the authoring facilities is also presented, followed by more recent work on reusing information extracted from existing databases and documents, and supporting the OWL ontology specification language.
Presciently translucent in Yokohama, 1891
Authors: Guedes Pedro
Published: June 2006

A house built by physician Willem van der Heyden in 1891 was a remarkable precursor of contemporary building services and construction technologies, and of Modern architecture.
Towards a new cathedral: mechanolatry and metaphysics in the milieu of Colin St John Wilson
Authors: Kite Stephen , Menin Sarah
Published: June 2006

Architectural debates of the 1950s – particularly between ‘empirical’ and ‘formal’ strands of Modernism – are highlighted by a study of the architectural projects, biography and milieu of Colin St John Wilson.
Three‐dimensional shear wave structure beneath the Philippine Sea from land and ocean bottom broadband seismograms
Authors: Isse Takehi , Yoshizawa Kazunori , Shiobara Hajime , Shinohara Masanao , Nakahigashi Kazuo , Mochizuki Kimihiro , Sugioka Hiroko , Suetsugu Daisuke , Oki Satoko , Kanazawa Toshihiko , Suyehiro Kiyoshi , Fukao Yoshio
Published: June 2006

We obtained three‐dimensional (3‐D) shear wave speed structure beneath the Philippine Sea and the surrounding region from seismograms recorded by land‐based and long‐term broadband ocean bottom seismographic stations. The ocean bottom data gave us a better station coverage to obtain a higher spatial resolution (about 300–400 km) in the Philippine Sea than in previous studies. We employed a new technique of surface wave tomography, in which multimode phase speeds are measured and inverted for a 3‐D shear wave speed structure by incorporating the effects of finite frequency and ray bending. There is a sharp speed contrast along the Izu‐Bonin‐Mariana trench, across which the Philippine Sea side has a significantly slower upper mantle than the Pacific Ocean side. In the upper 120 km, the shear wave speed structure is well correlated with the age of the provinces. At depths greater than 160 km, the pattern is dominated by fast anomalies of the subducted slabs of the Pacific plate and two slow anomalies to the south of the Daito ridge and in the southernmost part of the Philippine Sea.
Revisiting multifractality of high‐resolution temporal rainfall using a wavelet‐based formalism
Authors: Venugopal V. , Roux Stéphane G. , Foufoula‐Georgiou Efi , Arneodo Alain
Published: June 2006

We reexamine the scaling structure of temporal rainfall using wavelet‐based methodologies which, as we demonstrate, offer important advantages compared to the more traditional multifractal approaches such as box counting and structure function techniques. In particular, we explore two methods based on the Continuous Wavelet Transform (CWT) and the Wavelet Transform Modulus Maxima (WTMM): the partition function method and the newer and more efficient magnitude cumulant analysis method. We also report the results of a two‐point magnitude correlation analysis which is able to infer the presence or absence of multiplicativity as the underlying mechanism of scaling. The diagnostic power of these methodologies for small samples, signals with short ranges of scaling, and signals for which high‐frequency fluctuations are superimposed on a low‐frequency component (all common attributes of geophysical signals) is carefully documented. Application of these methodologies to several midwestern convective storms sampled every 5 s over several hours provides new insights. They reveal the presence of a very intermittent multifractal structure (a wide spectrum of singularities) in rainfall fluctuations between the scales of 5 min and the storm pulse duration (of the order of 1–2 hours for the analyzed storms). The two‐point magnitude statistical analysis suggests that this structure is consistent with a multiplicative cascading mechanism which however is local in nature; that is, it applies only within each storm pulse but not over the whole storm duration.
Psychobiography and the Psychology of Science: Understanding Relations between the Life and Work of Individual Psychologists
Authors: Runyan William McKinley
Published: June 2006

This paper presents initial interpretive hypotheses about connections between the life and work of a number of eminent psychologists: Sigmund Freud, Karen Horney, Henry Murray, B. F. Skinner, and Paul Meehl. Each of these interpretations can be critically evaluated, revised and improved, leading to incrementally more adequate understanding of individual lives, interacting with advances in psychological theory and research. Psychobiographical studies of individual scientists are a valuable complement to experimental and correlational lines of research in the psychology of science. In the “Science Wars” of the 1990s, there was an apparent conflict between scientists and those in social studies of science. The psychology of science can contribute to this debate, exploring the ways in which scientific inquiry, social-political worlds, and personal-experiential processes construct each other over time.
How Development and Personality Influence Scientific Thought, Interest, and Achievement
Authors: Feist Gregory J.
Published: June 2006

In the present article, I review and summarize two subdisciplines of the psychology of science, namely development and personality. In the first section concerning developmental psychology of science, I review three major developmental topics: 1) the literature on the developmental and familial influences behind scientific interest and scientific talent (e.g., birth-order and theory acceptance, immigrant status and scientific talent); 2) gender and scientific interest and talent; and lastly, 3) age and scientific interest and productivity. In the second section concerning personality psychology of science, I organize the review around four major topics: 1) which traits make scientific interest in general more likely; 2) which traits make interest in specific domains of science more likely (especially social and physical science); 3) which traits make different theoretical orientations more likely; and finally, 4) which traits make scientific achievement and creativity more likely. From the empirical evidence reviewed, it is quite clear that developmental and personality factors impact directly and indirectly scientific thought, interest, and achievement.
Microstructure of relaxed InN quantum dots grown on GaN buffer layers by molecular-beam epitaxy
Authors: Zhou Lin , Xu Tao , Smith David J. , Moustakas T. D.
Published: June 2006

Electron microscopy has been used to characterize the microstructure of InN quantum dots (QDs) grown by molecular-beam epitaxy on GaN(0001)/AlN(0001)/sapphire substrates at 425°C under slightly group III-rich conditions. Observations in plan-view and cross-section geometries established that the large majority of the InN QDs were invariably associated with threading dislocations in the underlying GaN buffer layer having edge components. Periodic, primarily hexagonal, arrays of misfit dislocations separated by ∼2.8nm were observed at the InN QD/GaN interface, indicating that the QDs were almost completely relaxed. No evidence for an InN wetting layer was obtained either in situ by reflection high-energy electron diffraction or ex situ by transmission electron microscopy.
Observation and analysis of percolation behavior in carbon microcoils/silicone-rubber composite sheets
Authors: Katsuno T. , Chen X. , Yang S. , Motojima S. , Homma M. , Maeno T. , Konyo M.
Published: June 2006

The electrical properties of carbon microcoils (CMCs)/ silicone-rubber composites were studied on the changes in the values of the electrical parameters (impedance, phase angle, resistance, and capacitance) as a function of the CMC content in the matrix, using an impedance analyzer in the frequency range from 40to200kHz. Percolation paths were observed at a 3wt% CMC content in the matrix. The properties of the composites were separated at the percolation threshold. The capacitance with a small value was dominant at CMC content less than 3wt%, and the resistance was dominant at CMC content higher than 3wt%.
Materials contrast in piezoresponse force microscopy
Authors: Kalinin Sergei V. , Eliseev Eugene A. , Morozovska Anna N.
Published: June 2006

Piezoresponse force microscopy (PFM) contrast in transversally isotropic material corresponding to the case of c+-c− domains in tetragonal ferroelectrics is analyzed using Green’s function theory by Felten et al. [J. Appl. Phys. 96, 563 (2004)]. A simplified expression for PFM signal as a linear combination of relevant piezoelectric constant is obtained. This analysis is extended to piezoelectric material of arbitrary symmetry with weak elastic and dielectric anisotropies. These results provide a framework for interpretation of PFM signals for systems with unknown or poorly known local elastic and dielectric properties, including nanocrystalline materials, ferroelectric polymers, and biopolymers.
One-dimensional Schottky contact between ErSi2 nanowire and Si(001)
Authors: Kubo O. , Shingaya Y. , Aono M. , Nakayama T.
Published: June 2006

We have measured the electric properties of nanosized Schottky contacts formed between ErSi2 nanowires (NWs) and a Si(001) substrate. Current vs voltage (I-V) measurement was performed by touching a scanning tunneling microscope tip to the NWs. The current density (J) through the ErSi2∕Si(001) interface increased as the width of the NWs decreased, while no significant changes were observed upon changing the length of the NWs. The ideality factor was estimated by fitting the standard Schottky equation to the obtained J-V curves. Our results suggest that the tunneling component increases as the width of the NWs becomes smaller.
Thermal stability and energy-band alignment of nitrogen-incorporated ZrO2 films on Si(100)
Authors: Zhu L. Q. , Zhang L. D. , Li G. H. , He G. , Liu M. , Fang Q.
Published: June 2006

Thermal stability and energy-band alignment of ZrOxNy films on Si are investigated using x-ray photoelectron spectroscopy and spectroscopy elliposometry (SE). The results show that the Zr–N bonds in as-oxidized ZrOxNy films are thermally unstable, while the N–O bonds in ZrOxNy matrix are stable even at high annealing temperature of 900°C. Optical properties are also analyzed based on the SE fitting results. The slight blueshift in the absorption edge indicates the increased band gap from 3.9to5.1eV after the additional annealing. Based on the valence-band spectrum results, zero-field energy-band alignments for ZrOxNy∕Si and ZrOxNy∕SiO2∕Si stacks are extracted.
Evanescent field on the surface of a negative-index planar lens
Authors: Liu Cheng , Yan Changchun , Chen Hao , Liu Ying , Gao Shumei
Published: June 2006

The propagation of the evanescent waves in an imaging system formed by left-handed material (LHM) slab is studied with finite difference time domain method. It was found that four energy-stream loops were formed on the slab interfaces, and the evanescent waves circulated within these loops instead of propagating away along the interfaces, accordingly, they could sustain for remarkably long time after the light source was turned off. Thus, for lossless LHM slab under continuing illumination, the energy of evanescent waves on its interfaces would accumulate with the time, leading to the evanescent wave amplification. This result reveals the back physics of the evanescent wave resonance and amplification, which were used to explain the superimaging with LHM slab, and has the potential to explain some of the contradictories existing in related researches.
Collector breakdown in the heterojunction bipolar transistor laser
Authors: Walter G. , James A. , Holonyak N. , Feng M. , Chan R.
Published: June 2006

Data are presented on a quantum-well (QW)-based InGaP∕GaAs∕InGaAs (QW) heterojunction bipolar transistor laser modified with external (increased) mirror reflection yielding lower threshold current (IB=23→19mA) and higher collector breakdown voltage (⩾2.5V). Increased breakdown at lower currents is observed on the collector I-V characteristics, at constant base current IB, as a slope change, a corner, and a narrow-line to broadband spectral shift from stimulated (high coherent optical field) to spontaneous (lower incoherent field) operation, a consequence of quenching or reducing photon-assisted tunneling (Franz-Keldysh effect) under the constraint IE+IB+IC=0 as α→1(α≡ΔIC∕ΔIE).
Raman scattering on silicon nanowires: The thermal conductivity of the environment determines the optical phonon frequency
Authors: Scheel H. , Reich S. , Ferrari A. C. , Cantoro M. , Colli A. , Thomsen C.
Published: June 2006

We studied the Raman spectra of silicon nanowires as a function of excitation power for various ambient gases. For a given excitation power, we find that the gas thermal conductivity determines the wire temperature, which can be detected by a change in phonon frequency. This shows that the redshift of the optical phonon in silicon nanowires compared to bulk silicon is mainly due to the lower thermal conductivity of nanowires and an increase in laser heating. The spectra of nanowires allow distinguishing gases on the basis of their thermal conductivity.
Electronic transport properties in SrTiO3–LaAlO3 solid-solution films
Authors: Ohtomo A. , Nishimura J. , Murakami Y. , Kawasaki M.
Published: June 2006

We report on the structural and electronic properties of solid-solution films consisting of perovskite band insulators, SrTiO3 and LaAlO3, with a chemical formula of Sr1−xLaxTi1−xAlxO3−δ. Single crystalline films grown by pulsed-laser deposition are fairly insulating below 300K when having x⩾0.6, while x<0.6 films exhibit electronic conduction accountable with a variable-range hopping. Room temperature conductivity has a maximum value of 20Ω−1cm−1 at x∼0.2. Hall measurements reveal that the density of the carriers varies as x(1−x) per Ti site up to x∼0.35, apparently indicating that La3+ donates one electron to a remaining Ti site. The results are discussed in comparison with the electronic properties of LaySr1−yTiO3 films in terms of different carrier localization mechanisms.
Crystal plasticity in Cu damascene interconnect lines undergoing electromigration as revealed by synchrotron x-ray microdiffraction
Authors: Budiman A. S. , Nix W. D. , Tamura N. , Valek B. C. , Gadre K. , Maiz J. , Spolenak R. , Patel J. R.
Published: June 2006

Plastic deformation was observed in damascene Cu interconnect test structures during an in situ electromigration experiment and before the onset of visible microstructural damage (voiding, hillock formation). We show here, using a synchrotron technique of white beam x-ray microdiffraction, that the extent of this electromigration-induced plasticity is dependent on the linewidth. In wide lines, plastic deformation manifests itself as grain bending and the formation of subgrain structures, while only grain rotation is observed in the narrower lines. The deformation geometry leads us to conclude that dislocations introduced by plastic flow lie predominantly in the direction of electron flow and may provide additional easy paths for the transport of point defects. Since these findings occur long before any observable voids or hillocks are formed, they may have direct bearing on the final failure stages of electromigration.
Tunable and frequency-stabilized diode laser using temperature-dependent energy pooling fluorescence
Authors: Xiao Liantuan , Huang Tao , Wang Lirong , Zhao Jianming , Jia Suotang
Published: June 2006

We have demonstrated a robust method of tuning and stabilizing a diode laser frequency to the fluorescence peaks of the energy pooling occurred at thermal cesium vapor-glass interface. This technique is based on temperature-dependent shift of the two off-core fluorescence peaks caused by 6P3∕2+6P3∕2→7P(3∕2,1∕2)∕8S1∕2+6S1∕2 energy pooling collisions. We achieved laser linewidth of 1.1MHz and continuous tunability over ±200–600MHz within a temperature range of 360–420K by applying the wavelength modulation technology. Tunable frequency locking in such a wide range was constructed inexpensively with low laser power. It can also be extended to other wavelengths by using different atomic species.
Effects of wiggler and axial guide fields on the relativistic high-frequency waves in a cylindrical plasma waveguide
Authors: Farokhi B. , Abdykian A.
Published: June 2006

An analysis of the azimuthally symmetrical, high frequency eigenmodes of a cylindrical metallic waveguide completely filled with a one-dimensional helical wiggler and relativistic magnetized plasma is presented. A relativistic nonlinear wave equation is derived in a form including the coupling of EH and HE modes due to the finite axial and wiggler magnetic fields. This treatment shows that the dispersion curves are dependent on dγ∕dt and Bw, ignored in previous works. The difference between relativistic modes with effects of wiggler field and nonrelativistic cases is shown. This study is benefiting to improve the devices for generation of high-power electromagnetic radiation, charged particle acceleration, and other applications of plasma waveguide.
Effect of active layer thickness on bias stress effect in pentacene thin-film transistors
Authors: Chang Josephine B. , Subramanian Vivek
Published: June 2006

The bias stress effect in pentacene thin-film transistors is characterized for different active layer thicknesses. We show that the shift in threshold voltage under applied bias is accelerated as the pentacene semiconductor layer thickness is increased from 10to80nm, and that this trend is not correlated with current, initial threshold voltage, or turn-on voltage. This study sheds light on the role of active material above the conductive channel in thin-film devices and describes effects that are important to consider when optimizing the structure of organic thin-film transistors.
High sensitivity nanoscale mapping of elastic moduli
Authors: Ganor Yaniv , Shilo Doron
Published: June 2006

Recently, a new technique has been developed, which allows quantitative nanoscale mapping of elastic moduli by means of a hybrid nanoindentation and force modulation instrument. We introduce a procedure for finding the experimental parameters that provide an optimal modulus contrast. An application of the procedure on a BaTiO3 single crystal reveals a clear contrast between domains that have different orientations of the tetragonal unit cell. The obtained results are in good agreement with reported bulk elastic moduli and show that the elastic modulus sensitivity is 5%. Thus, the improved modulus mapping procedure can be applied not only to composite materials but also to many multiphase and multidomain material systems.
Low-temperature ordering and enhanced coercivity of L1-FePt thin film promoted by a Bi underlayer
Authors: Feng Chun , Li Bao-He , Han Gang , Teng Jiao , Jiang Yong , Liu Quan-Lin , Yu Guang-Hua
Published: June 2006

We have studied L10-FePt thin films with a Bi underlayer. Experimental results show that the ordering temperature of the L10-FePt film can be lowered down to 300–350°C and the in-plane coercivity HC of the film is obviously enhanced by introduction of a Bi underlayer. After annealing at 400°C for 20min, a Bi∕FePt film realizes a HC of 13.5kOe and the ratio of the remnant magnetization Mr to the saturation one MS of as high as 0.93. The reduction of the ordering temperature and the enhanced magnetic properties of L10-FePt films can be understood by considering the large diffusivities of Fe and Pt associated with Bi diffusion.
Theoretical investigation of electromagnetic waves in a dielectric loaded coaxial plasma waveguide
Authors: Aghamir F. M. , Zandieh M. N.
Published: June 2006

A theoretical study of high frequency eigenmodes of a dielectric loaded coaxial waveguide in the presence of an annular plasma column is presented. A uniform axial magnetic field is applied to maintain the plasma position inside the waveguide. The dispersion equation is derived through the application of the appropriate boundary conditions which results in an eighth order determinant. The eigenmodes are determined by equating this determinant to zero. In the presence of the dielectric layer on the conducting surfaces, the azimuthally symmetric modes have been identified as HE, EH, cyclotron, and space charge modes for the coaxial waveguide. A comparison of the numerical analyses of this study with the results of the previous investigations indicates that there is a considerable rise in the frequencies of the waveguide modes.
Influence of thermal conductivity on the glass-forming ability of Ni-based and Cu-based alloys
Authors: Louzguine-Luzgin Dmitri V. , Setyawan Albertus Deny , Kato Hidemi , Inoue Akihisa
Published: June 2006

In the present letter we compare the thermal conductivities of Cu- and Ni-based alloys in relation with their cooling rates and glass-forming abilities. The cooling rates obtained for Cu- and Ni-based bulk glass-forming alloys are found to scale with the thermal conductivities of the base elements. Relatively low thermal conductivity of Ni-based alloy compared to the Cu-based one explains its lower glass-forming ability. The results also indicate that the thermal conductivity of the molten alloy should be also used as an indicator of the glass-forming ability among the other factors.
Solid phase crystallization of amorphous Fe–Si layers synthesized by ion implantation
Authors: Naito Muneyuki , Ishimaru Manabu , Hirotsu Yoshihiko , Valdez James A. , Sickafus Kurt E.
Published: June 2006

Microstructural changes of ion-beam-synthesized amorphous Fe–Si layers on thermal annealing were investigated using transmission electron microscopy. Single crystal Si(111) substrates were irradiated with 120keV Fe+ ions at cryogenic temperature to a fluence of 4.0×1017cm−2, followed by thermal annealing at 200–700°C. The amorphous Fe–Si layer in the as-implanted sample crystallized to polycrystalline ε-FeSi and β-FeSi2 layers after annealing at 500°C for 2h.ε-FeSi transformed into β-FeSi2 and the β-FeSi2 region extended with increasing annealing temperature. Excess Fe atoms from ε-to-β phase transformation migrate toward the Si substrate via β-FeSi2 grain boundaries. We discuss the recrystallization process of amorphous Fe–Si thin layers and the growth mechanism of β-FeSi2 thin layers formed in high-dose Fe ion-implanted Si.
A new polarized neutron reflectometer at Dhruva for specular and off-specular neutron reflectivity studies
Authors: Basu S. , Singh S.
Published: June 2006

A polarized neutron reflectometer for vertical sample geometry has been installed in the guide tube laboratory of Dhruva reactor at Trombay, India. The instrument uses a monochromatic neutron beam of 2.5 Å in a step scan mode with a linear position sensitive detector for data collection. This allows one to collect off-specular or diffuse neutron reflectivity (DNR) data quite easily besides specular reflectivity data. The design aspects of this instrument have been presented. The instrument can easily switch between unpolarized and polarized mode, since the beam to the sample is prepared by reflection from a polarizing supermirror or a non-polarizing supermirror. Specular reflectivity studies in unpolarized and polarized mode, for chemical and magnetic structure of thin film samples have been presented. DNR data has been collected from a Ni film. Interface morphology at the air-film interface has been obtained from this data.
GumTree—a Java based GUI framework for beamline experiments
Authors: Lam T. , Götz A. , Franceschini F. , Hauser N.
Published: June 2006

GumTree is a highly integrated multi-platform graphical user interface (GUI) for performing neutron and X-ray scattering experiments. This open source project is built upon the foundation of the Eclipse Rich Client Platform, using the Java programming language. The GumTree Project at ANSTO consists of a general application framework (GumTree Platform) and a set of specific components for the OPAL reactor Neutron Beam Instruments Project (NBIP). The GumTree Platform provides the essential GUI components for common beamline operations via an application programming interface (API) and Eclipse’s extension mechanism. GumTree is being adapted to several instrument control server systems, providing an easy-to-use front-end for users and simple-to-extend model for software developers.
Monte Carlo simulations of a powder diffractometer installed on a long pulse target station using wavelength frame multiplication
Authors: Lieutenant K. , Mezei F.
Published: June 2006

MC simulations of neutron diffractometer have been performed using the VITESS software package to check the feasibility of the frame multiplication concept and to compare a powder instrument installed on a long pulse target station (LPTS) with an equivalent instrument installed on a decoupled poisoned moderator of a short pulse target station (SPTS) of the same power. The simulations show that frame multiplication can be realised, if five choppers are used to determine the frame. For the same FWHM peak width, the LPTS yields comparable peak intensities for wavelengths of about 1 Å, much higher intensities than the SPTS for long wavelengths, and a quite symmetric peak shape for all wavelengths. Therefore, a combination of high-energy LPTS and pulse shaping choppers can be used instead of a decoupled poisoned moderator of a SPTS to run a TOF powder diffractometer. It is the better choice (than the SPTS solution), because it matches the performance of SPTS in the case most favourable for SPTS: highest resolution offered by the poisoned moderator, has the capability of easily increasing the intensity by its variable resolution and gives superior intensity for longer neutron wavelengths.
Anomalous neutron Compton scattering: comparison of the convolution approximation with a model-free approach
Authors: Krzystyniak M. , Chatzidimitriou-Dreismann C.A.
Published: June 2006

A shortfall of the scattering intensity from protons has been observed in liquids (water, benzene, etc.) and solids (metal hydrogen systems, organic polymers, etc.) using neutron Compton scattering (NCS). The conventional NCS data reduction scheme, used to obtain the scattering intensities, is based on the convolution approximation (CA) of the nuclear momentum distribution with the instrument resolution function. This scheme has been severely criticized. It was claimed that it is the way the energy resolution function is incorporated in the CA data processing that leads to an underestimation of the scattering intensity. In the present work, the CA data reduction scheme is compared to a model-free approach newly proposed by Dorner. This new scheme is independent of the form of the momentum distribution and the resolution function. Specifically, the ratios of the scattering cross section densities of H to C are presented for a measurement on a polyethylene (PE) sample. The new data reduction scheme is shown to lead to the same results as for the experimental data published earlier and treated with the CA approximation thus refuting the aforementioned criticisms.
Using Misbehavior to Analyze Strategic versus Aggregate Energy Minimization in Wireless Sensor Networks
Authors: Kannan Rajgopal , Wei Shuangqing , Chakravarthy Vasu
Published: June 2006

We present a novel formulation of the problem of energy misbehavior and develop an analytical framework for quantifying its impact on other nodes. Specifically, we formulate two versions of the power control problem for wireless sensor networks with latency constraints arising from duty cycle allocations. In the first version, strategic power optimization, nodes are modeled as rational agents in a power game, who strategically adjust their powers to minimize their own energy. In the other version, joint power optimization, sensor nodes adjust their transmission powers to minimize the aggregate energy expenditure. Our analysis of these models yields insight into the different energy outcomes of strategic versus joint power optimization. We show that while joint power optimization fits the accepted paradigm of cooperation among sensor nodes (for example large number of sensor nodes cooperating for a task such as target tracking), it comes with both advantages and disadvantages when energy misbehavior is taken into account. One advantage is that it can (sometimes) be energy-dominant, i.e., the optimal energy cost for each node under joint energy minimization is lower than its strategically optimal energy cost. We then develop a model for characterizing energy misbehavior and show that joint optimization is disadvantageous because it is impossible to prevent misbehavior under any channel quality and load constraints, whereas strategic optimization is more resilient. We prove that it is impossible for a node to unilaterally and undetectably follow a different energy optimization strategy than the other nodes and hence the only threat to the network is misbehavior through false advertisement. We then provide sufficient conditions under which misbehavior through false advertisement can be prevented under a strategic optimization regime. Our analytical results reveal optimal strategies for attacking nodes in an enemy network through energy depletion and help develop effective defense mechanisms for protecting our own wireless network against energy attacks by an intelligent adversary.
A State Machine Sensor Network for Ephemeral Stream Detection
Authors: Murphy Michael A. , Post Christopher J.
Published: June 2006

Sensor networks based on the de facto standard Berkeley TinyOS platform are changing the way environmental information is collected in the field. One such network has been designed, deployed, and tested in order to determine where ephemeral streams (small, temporary channels of runoff) form during precipitation events. This small, proof-of-concept test network was designed around a generic nondeterministic finite state machine component, which was built to be re-used in later environmental sensor network applications. A simplistic broadcast mechanism was devised to provide collective sampling interval changes to adapt to environmental conditions. In this paper, the design and testing of the ephemeral stream detection network are discussed, along with design features that can be re-used in later applications. Improvements for a later deployment of a larger, operational ephemeral stream detection network are also described.
Ultrastructural study of the temporomandibular joint after unilateral meniscectomy in Wistar rats
Authors: MARTINI D. T. , DE CAMPOS BOLDRINI S. , DE VASCONCELLOS FONTES R. B. , LIBERTI E. A.
Published: June 2006

summary  Meniscectomy of the temporomandibular joint (TMJ) was frequently performed until a few years ago but now is seldom employed. This procedure induces important articular modifications but the complete extent of ultrastructural changes is still unknown. Twenty‐one Wistar rats were submitted to unilateral meniscectomy. Animals were randomly divided into three groups and followed for 15, 35 or 60 days. After killing both meniscectomized and contralateral TMJ specimens were sectioned sagittally and prepared for light and scanning electron microscopy studies. Normal TMJs are characterized by glenoid fossa and condylar process with distinct conjunctive layers in which regularly arranged type 1 collagen fibres predominate. Meniscectomized animals initially exhibit a different tissue covering the eroded articular surface of the condyle with the prevalence of type 3 collagen fibres but type 1 fibres predominate in the late postoperative period. Subchondral cysts are clearly visible. A complex remodelling process of the TMJ after meniscectomy is evident with important ultrastructural modifications that may correlate to unsatisfactory clinical results. The dynamic nature of this process is also observed when specimens from different postoperative periods are compared. Surgeons should always bear in mind these alterations when indicating this procedure.
Effects of temperature of adults and eggs on the induction of embryonic diapause in the band‐legged ground cricket, Dianemobius nigrofasciatus
Authors: FUKUMOTO EIJI , NUMATA HIDEHARU , SHIGA SAKIKO
Published: June 2006

Abstract Eggs laid by adult female Dianemobius nigrofasciatus, reared under long‐day (LD 16 : 8 h, 25 °C) or short‐day (LD 12 : 12 h, 25 °C) conditions from the nymphal stage, are kept at several constant temperatures. At 22.5–30.0 °C, eggs laid by long‐day adults show lower incidences of diapause than those laid by short‐day adults. In both eggs laid by adults under long‐day conditions and those under short‐day conditions, the higher the temperature at which the eggs are kept, the lower the incidence of diapause. When eggs of long‐day adults are exposed to a low‐temperature pulse (10 °C, 24 h) on the day of deposition (day 0), the incidence of diapause increases. The low‐temperature pulse on day 1 does not increase the incidence of diapause. By contrast, when the eggs of short‐day adults are exposed to a high‐temperature pulse (35 °C, 24 h) on day 0 or day 1, the incidence of diapause decreases. The temperature pulses on day 0 are more effective at diapause prevention. Staining of diapause eggs by the Feulgen–Rossenbeck method shows that the eggs enter diapause at the blastoderm stage, which is on day 1 or day 2 at 25 °C. The exposure of adults to long days and higher temperatures prevents the eggs from entering diapause. In D. nigrofasciatus, embryonic diapause is controlled by maternal effects, adult photoperiod and temperature, and egg temperature before or at diapause.
Dynamic amino acid increases in the basolateral amygdala during acquisition and expression of conditioned fear
Authors: Venton B. Jill , Robinson Terry E. , Kennedy Robert T. , Maren Stephen
Published: June 2006

Glutamate and γ‐aminobutyric acid (GABA) release in the amygdala are thought to be crucial for the acquisition and expression of fear memories, but the time course of amino acid changes during conditioning is unknown. We used rapid‐sampling microdialysis with 14 s temporal resolution to address this issue. During auditory fear conditioning, large, rapid and transient increases in glutamate and GABA were detected, but only during the first noise–shock pairing. In contrast, rats receiving unsignaled shocks during contextual fear conditioning showed no changes in GABA and less glutamate release for the initial shock, but increased glutamate release during later shocks. Expression of conditioned fear to either a white noise or the context previously paired with shock produced similar rapid and transient increases in many amino acids in the amygdala. These experiments demonstrate glutamate and GABA levels in the amygdala are differentially modulated during auditory and contextual fear learning, and are transiently increased during the expression of fear memories.
Neuronal circuitry and synaptic organization of trigeminal proprioceptive afferents mediating tongue movement and jaw–tongue coordination via hypoglossal premotor neurons
Authors: Luo Pifu , Zhang Jingdong , Yang Regina , Pendlebury William
Published: June 2006

The neural framework and synaptic organization of trigeminal proprioceptive afferent‐mediated jaw–tongue coordination were studied in rats using multiple electrophysiological and neuroanatomical approaches. Electrostimulation of the masseter nerve evoked short‐latency responses (5.86 ± 2.59 ms) in hypoglossal premotor pools including the parvocellular (PCRt) and intermediate (IRt) reticular nuclei and the dorsomedial part of the spinal trigeminal nucleus oralis (Vodm) and interpolaris (Vidm). Biocytin‐labelled axon terminals from these areas traveled into the hypoglossal nucleus (XII) and contacted motoneurons. Double labelling of biotinylated dextran amine (BDA) tracing and cholera toxin B (CTB) transport demonstrated that labelled axons and terminals from the mesencephalic trigeminal nucleus (Vme) overlapped with XII premotor neurons in the alpha division and in PCRt, IRt, Vodm and Vidm. Confocal microscopic observations revealed that Vme terminals closely contacted XII premotor neurons. Dual labelling of intracellular neurobiotin staining of jaw‐muscle spindle afferents (JMSAs) combined with horseradish peroxidase (HRP) retrograde transport revealed that 498 JMSA boutons apposed to 146 HRP‐labelled premotor neurons. Electron microscopic observations demonstrated that 127 JMSA boutons made both axodendritic (68%) and axosomatic (32%) synapses with XII premotor neurons. Eighty‐three per cent of synapses were asymmetric and the rest (17%) were symmetric. Thirty‐nine per cent of JMSA boutons received presynaptic contacts from P‐type terminals. Varieties of synaptic organizations were found. These results provide evidence that trigeminal proprioceptive afferents mediate jaw–tongue coordination through XII premotor neurons. Ultrastructural findings demonstrated that synapses between JMSA boutons and XII premotor neurons are predominantly excitatory, and synaptic transmission to XII motoneurons is modified on XII premotor neurons by presynaptic mechanisms. These frameworks and synaptic organizations are most probably the neural substrate for trigeminal proprioceptive afferent‐mediated jaw–tongue coordination.
In vitro tracheal hyperresponsiveness to muscarinic receptor stimulation by carbachol in a rat model of bleomycin‐induced pulmonary fibrosis
Authors: Barrio J. , Cortijo J. , Milara J. , Mata M. , Guijarro R. , Blasco P. , Morcillo E. J.
Published: June 2006

1 Bleomycin‐induced lung injury is widely used as an experimental model to investigate the pathophysiology of pulmonary fibrosis but the alterations in the pharmacological responsiveness of airways isolated from bleomycin‐exposed animals has been scarcely investigated. The aim of this study was to examine the in vitro tracheal responses to muscarinic receptor stimulation with carbachol in a rat bleomycin model.

2 Concentration–response curves to carbachol (10 nm to 0.1 mm) were obtained in tracheal rings isolated from Sprague–Dawley rats 14 days after endotracheal bleomycin or saline. The intracellular calcium signal in response to carbachol (10 μm) was measured by epifluorescence microscopy using fura‐2 in primary cultures of tracheal smooth muscle cells from bleomycin‐ and saline‐exposed rats. Circulating plasma tumour necrosis factor (TNF)‐α/interleukin (IL)‐1β levels were measured by enzyme‐linked immunosorbent assay.

3 Maximal contraction in response to carbachol was significantly greater in tracheal rings from bleomycin‐exposed rats compared with controls (15.8 ± 1.3 mN vs. 11.8 ± 1.4 mN; n = 19, P < 0.05).

4 Carbachol (10 μm) elicited a transient increase of intracellular calcium with greater increment in tracheal smooth muscle cells from bleomycin‐exposed rats compared with controls (372 ± 42 nmvs. 176 ± 20 nm; n = 7, P < 0.01).

5 Circulating plasma levels of TNF‐α/IL‐1β were augmented in bleomycin‐exposed rats compared with controls. Tissue incubation with TNF‐α (100 ng ml−1)/IL‐1β (10 ng ml−1) increased in vitro tracheal responsiveness to carbachol.

6 In conclusion, tracheal contraction in response to muscarinic receptor stimulation with carbachol was increased in bleomycin‐exposed rats. This in vitro cholinergic hyperresponsiveness may be related to the augmented levels of inflammatory cytokines in bleomycin‐exposed rats.
Nasal symptoms, airway obstruction and disease severity in chronic obstructive pulmonary disease
Authors: Hurst John R. , Kuchai Romana , Michael Philip , Perera Wayomi R. , Wilkinson Tom M.A. , Wedzicha Jadwiga A.
Published: June 2006

Background:  Chronic obstructive pulmonary disease (COPD) is characterized by inflammation of the lung in association with airflow obstruction. There is increasing evidence of upper airway involvement in COPD and we have reported that this nasal inflammation is proportional to that in the lung. Given recognized relationships between lower airway inflammation and spirometric indices such as the Forced Expiratory Volume in one second (FEV1), we hypothesized that there may be a relationship between nasal obstruction and FEV1 in COPD. We also sought to investigate relationships between nasal symptoms and nasal patency in COPD.

Methods:  We assessed the nasal and pulmonary airways, using acoustic rhinometry and spirometry respectively, in 51 patients with COPD.

Results:  The presence of chronic nasal symptoms in COPD was associated with reduced nasal patency (6·04 cm2 symptoms vs. 9·55 cm2 no symptoms, at the second minimum cross‐sectional area, P = 0·049). Nasal patency in COPD was inversely proportional to pulmonary airflow obstruction, and therefore to COPD disease severity (e.g. FEV1% predicted vs. second minimum cross‐sectional area, r = 0·36, P = 0·009).

Conclusions:  The degree of nasal airway obstruction in COPD reflects the impairment to pulmonary airflow, and is greater in the presence of chronic nasal symptoms. This study provides further evidence of pan‐airway involvement in COPD.