bluuebunny/crossref_metadata_2025 huggingface dataset:
Ohmic heated sheet for the Ca ion beam production
Authors: Efremov A. , Bogomolov S. , Kazarinov N. , Kochagov O. , Loginov V.
Published: January 2008

The production of intense accelerated Ca48 ion beams is the key problem in the experiments on the synthesis of new superheavy nuclei. For this purpose in the FLNR (JINR), an electron cyclotron resonance ion source is used at the U-400 cyclotron. The combination of a micro oven with a hot tantalum sheet inside the discharge chamber allowed the production of the intense Ca5+48 ion beam at the Ca48 consumption of about 0.5mg∕h. In this case, the tantalum sheet is heated by microwaves and plasma electrons. The microwave power of up to 500W is required to heat the sheet to the temperature of about 500°C. To decrease the required microwave power, a new sheet with a direct Ohmic heating was designed. The present paper describes the method, technique, and preliminary experimental results on the production of the Ca ion beam.
Microwave field distribution and electron cyclotron resonance heating process
Authors: Consoli F. , Celona L. , Ciavola G. , Gammino S. , Maimone F. , Barbarino S. , Catalano R. S. , Mascali D.
Published: January 2008

In an electron cyclotron resonance ion source, ions are produced from a plasma generated and sustained by microwaves with a proper frequency. Some experiments showed that the plasma formation, the consequent amount of particles extracted from the source, and the related beam shape strongly depend on the frequency of the electromagnetic wave feeding the cavity. In order to have a better understanding of these phenomena, in this work we deal with the description of the motion of a charged particle inside the plasma chamber model of the SERSE ion source operating at INFN-LNS in Catania, the analysis being applicable to any similar apparatus. The electromagnetic fields inside the vacuum filled chamber were determined theoretically and, together with proper simulations, their fundamental role on the particle motion, on their confinement, and on the energy transfer they are subjected to during their motion within the cavity is shown.
Quantum control mechanism analysis through field based Hamiltonian encoding: A laboratory implementable algorithm
Authors: Mitra Abhra , Rabitz Herschel
Published: January 2008

While closed-loop control of quantum dynamics in the laboratory is proving to be broadly successful, the control mechanisms induced by the fields are often left obscure. Hamiltonian encoding (HE) was originally introduced as a method for understanding mechanisms in quantum dynamics in the context of computational simulations, based on access to the system wavefunction. As a step towards laboratory implementation of HE, this paper addresses the issues raised by the use of observables rather than the wavefunction in HE. The goal of laboratory based HE is to obtain an understanding of control mechanism through a sequence of systematic control experiments, whose collective information can identify the underlying control mechanism defined as the set of significant amplitudes connecting the initial and final states. Mechanism is determined by means of observing the dynamics of special sequences of system Hamiltonians encoded through the control field. The proposed algorithm can handle complex systems, operates with no recourse to dynamical simulations, and functions with limited understanding of the system Hamiltonian. As with the closed-loop control experiments, the HE control mechanism identification algorithm performs a new experiment each time the dynamical outcome from an encoded Hamiltonian is called for. This paper presents the basic HE algorithm in the context of physical systems described by a finite dimensional Hilbert space. The method is simulated with simple models, and the extension to more complex systems is discussed.
Barrier-free proton transfer in the valence anion of 2′-deoxyadenosine-5′-monophosphate. II. A computational study
Authors: Kobyłecka Monika , Gu Jiande , Rak Janusz , Leszczynski Jerzy
Published: January 2008

The propensity of four representative conformations of 2′-deoxyadenosine-5′-monophosphate (5′-dAMPH) to bind an excess electron has been studied at the B3LYP∕6-31++G(d,p) level. While isolated canonical adenine does not support stable valence anions in the gas phase, all considered neutral conformations of 5′-dAMPH form adiabatically stable anions. The type of an anionic 5′-dAMPH state, i.e., the valence, dipole bound, or mixed (valence/dipole bound), depends on the internal hydrogen bond(s) pattern exhibited by a particular tautomer. The most stable anion results from an electron attachment to the neutral syn-south conformer. The formation of this anion is associated with a barrier-free proton transfer triggered by electron attachment and the internal rotation around the C4′–C5′ bond. The adiabatic electron affinity of the a̱south-syn anion is 1.19eV, while its vertical detachment energy is 1.89eV. Our results are compared with the photoelectron spectrum (PES) of 5′-dAMPH− measured recently by Stokes et al., [J. Chem. Phys. 128, 044314 (2008)]. The computational VDE obtained for the most stable anionic structure matches well with the experimental electron binding energy region of maximum intensity. A further understanding of DNA damage might require experimental and computational studies on the systems in which purine nucleotides are engaged in hydrogen bonding.
The structure and binding energies of the van der Waals complexes of Ar and N2 with phenol and its cation, studied by high level ab initio and density functional theory calculations
Authors: Vincent Mark A. , Hillier Ian H. , Morgado Claudio A. , Burton Neil A. , Shan Xiao
Published: January 2008

We have investigated, using both ab initio and density functional theory methods, the minimum energy structures and corresponding binding energies of the van der Waals complexes between phenol and argon or the nitrogen molecule, and the corresponding complexes involving the phenol cation. Structures were obtained at the MP2 level using a large basis, and the corresponding energies were corrected for basis set superposition error (BSSE), higher order electron correlation effects, and for basis set size. The structures of the global minima were further refined for the effects of BSSE and the corresponding binding energies were evaluated. For each neutral species, we find only a single true minimum, π bonded for argon and OH bonded for nitrogen. For both cationic species, we find that the OH-bonded complex is preferred over other minima which we have identified as having Ar or N2 between exogeneous atoms. The ab initio calculations are generally in excellent agreement with experimental binding energies and rotational constants. We find that the B3LYP functional is particularly poor at describing these complexes, while a density functional theory (DFT) method with an empirical correction for dispersive interactions (DFT-D) is very successful, as are some of the new functionals proposed by Zhao and Truhlar [J. Phys. Chem. A 109, 5656 (2005); J. Chem. Theory Comput. 2, 1009 (2006); Phys. Chem. Chem. Phys. 7, 2701 (2005); J. Phys. Chem. A 108, 6908 (2004)]. Both the ab initio and DFT-D methods accurately predict the intermolecular vibrational modes.
Influence of R-ion size on spin state of Co and magnetic properties of RBaCo2O5.50 cobaltites
Authors: Frontera Carlos , García-Muñoz José Luis , Castaño Oscar
Published: January 2008

This work presents a comparative magnetic study of PrBaCo2O5.50 and YBaCo2O5.50. Samples studied have been carefully prepared, specially the PrBaCo2O5.50 one, to avoid the formation of oxygen vacancy disorder. High temperature magnetic measurements indicate different spin states of Co ions in both compounds. Neutron powder diffraction below RT indicate a different succession of magnetic arrangements.
Analysis on multiple cracking in film/substrate systems with residual stresses
Authors: Zhang X. C. , Xu B. S. , Xuan F. Z. , Tu S. T.
Published: January 2008

The multiple cracks might be initiated in the film on a substrate due to the presence of residual stress. In this paper, the multiple film cracking in the film/substrate systems with residual stress was analyzed. First, a relatively simplified model with the closed solutions considering the edge effect was developed to predict the residual stress within the film segment. Some obvious relationships between the material properties and the dimensions of the film and substrate and the stress distribution in the film could be reflected by using this model. By comparing the analytical results with those from the existing analytical models, finite element analysis, and the existing experimental measurements, it could be concluded that the present analytical model was very rigorous. Then, the energy criterion was adopted to perform the analysis on multiple film cracking on the basis of the knowledge on the residual stress distributions. The closed-form solution for the critical misfit strain for the crack initiation is obtained. When the misfit strain is higher than critical misfit strain, the effects of the thickness and elastic modulus of the film on the crack density in the film and the crack initiation strain were investigated.
Ru
+
oxide
interlayer for perpendicular magnetic recording media
Authors: Yuan Hua , Laughlin David E. , Zhu Xiaobin , Lu Bin
Published: January 2008

Ru + oxide composite thin films were studied as potential intermediate layers (interlayers) for perpendicular magnetic recording media for the purpose of grain size reduction. It was found that the orientation spread of the Ru grains increased from 3.7° to 4.6° when the oxide addition was increased to 50vol%, and the roughness of the thin films stayed constant. The grain size of the Ru layer was reduced as the oxide volume fraction increased. At lower doping levels, the oxide stayed at the Ru grain boundaries. However, when the oxide was higher than 30vol%, a “salt and pepper”-type microstructure was obtained, where both Ru and oxide grains are small and intermixed. It was found that the magnetic layer did not have a one to one grain growth on the Ru+oxide layer with the ‘‘salt and pepper’’-type microstructure. The coercivity (Hc) of the media decreased as the oxide volume fraction increased, while the squareness of the hysteresis loops stayed at unity until more than 30vol% of oxide was added. Oxide additions to the Ru interlayer seem to be a good process variable to further decrease the grain size for higher areal density magnetic recording.
Microstructure and magnetic properties of strained Fe3O4 films
Authors: Chen Y. Z. , Sun J. R. , Han Y. N. , Xie X. Y. , Shen J. , Rong C. B. , He S. L. , Shen B. G.
Published: January 2008

A comparable study of the microstructure and magnetic properties was performed for magnetite films deposited on (100)-oriented MgO and SrTiO3 (STO) substrates. The growth of strained high quality Fe3O4 films was confirmed by x-ray diffraction analysis and Raman spectroscopy measurements. The surface morphology and magnetic properties of the two films were found to be obviously different. Moreover, a stripelike magnetic domain structure was observed in the film on STO. Substrate-induced strain is believed to be responsible for these observations, which significantly affects the magnetic anisotropy and the magnetic coupling at the antiphase boundaries in the films.
High sensitivity imaging Thomson scattering for low temperature plasma
Authors: van der Meiden H. J. , Al R. S. , Barth C. J. , Donné A. J. H. , Engeln R. , Goedheer W. J. , de Groot B. , Kleyn A. W. , Koppers W. R. , Lopes Cardozo N. J. , van de Pol M. J. , Prins P. R. , Schram D. C. , Shumack A. E. , Smeets P. H. M. , Vijvers W. A. J. , Westerhout J. , Wright G. M. , van Rooij G. J.
Published: January 2008

A highly sensitive imaging Thomson scattering system was developed for low temperature (0.1–10eV) plasma applications at the Pilot-PSI linear plasma generator. The essential parts of the diagnostic are a neodymium doped yttrium aluminum garnet laser operating at the second harmonic (532nm), a laser beam line with a unique stray light suppression system and a detection branch consisting of a Littrow spectrometer equipped with an efficient detector based on a “Generation III” image intensifier combined with an intensified charged coupled device camera. The system is capable of measuring electron density and temperature profiles of a plasma column of 30mm in diameter with a spatial resolution of 0.6mm and an observational error of 3% in the electron density (ne) and 6% in the electron temperature (Te) at ne=4×1019m−3. This is achievable at an accumulated laser input energy of 11J (from 30 laser pulses at 10Hz repetition frequency). The stray light contribution is below 9×1017m−3 in electron density equivalents by the application of a unique stray light suppression system. The amount of laser energy that is required for a ne and Te measurement is 7×1020∕neJ, which means that single shot measurements are possible for ne>2×1021m−3.
Stability of frequency-multiplying harmonic gyroklystrons
Authors: Savilov A. V. , Nusinovich G. S.
Published: January 2008

In the present paper, frequency-multiplying three-cavity gyroklystrons are studied in detail. The analysis is focused on the possibility of realizing a high electron-bunching efficiency in the output cavity while simultaneously suppressing the excitation of parasitic backward waves resonant with lower cyclotron harmonics. The potential to minimize the effect of parasitic backward-wave excitation at the fundamental cyclotron resonance on the device operation by the proper choice of output cavity length is shown.
Dewetting of Ni and NiAg solid thin films and formation of nanowires on ripple patterned substrates
Authors: Petersen J. , Mayr S. G.
Published: January 2008

The solid state dewetting process of thin Ni films during thermal annealing on smooth and ripple patterned silicon dioxide was investigated. The ripple pattern was created by ion etching under oblique incidence and has a corrugation wavelength of about 40nm. Scanning electron microscopy images show a faster decrease of Ni surface coverage for the templated dewetting on the ripple pattern with increasing temperature indicating an additional driving force of curvature induced diffusion. The ridges act as diffusion barriers trapping Ni in the valleys. Finding adequate parameters for film thickness and annealing temperature leads to the formation of nanorods or nanowires. The kinetics of dewetting was analyzed by means of in situ electrical resistance measurements, whereas Ni surface diffusion on Ni(111) planes was determined to be the kinetically limiting process with an activation energy of 0.32±0.02eV. The addition of Ag to the Ni film switches the dewetting mechanism from the common capillarity driven growth mode of voids to the fractal-like growth mode and improves the nanowire formation by self-organization on the templates. Ag is immiscible in Ni and segregates to the surface acting as a kind of catalyst during the dewetting process.
A surface-enhanced Raman spectroscopy substrate for highly sensitive label-free immunoassay
Authors: Zhang Ming-Liang , Yi Chang-Qing , Fan Xia , Peng Kui-Qing , Wong Ning-Bew , Yang Meng-Su , Zhang Rui-Qin , Lee Shuit-Tong
Published: January 2008

Large-scale uniform silicon nanowires (SiNWs) array was fabricated by chemical etching on n-Si(111) wafer. Silver nanoparticles (AgNPs) were loaded on their surfaces. The AgNPs on SiNWs (AgNPs@SiNWs) array exhibit strong surface-enhanced Raman effect. On the substrate surfaces, characteristic Raman signals are generated with trace amount of mouse immunoglobulin G (mIgG), goat-anti-mouse immunoglobulin G (gamIgG), and immune complexes formed from 4ng each of mIgG and gamIgG. The shifted positions and changed intensities in Raman bands indicate the occurrence of immunoreactions. This AgNPs@SiNWs array is a unique substrate for surface-enhanced Raman spectroscopy to show the immune reagents and immunoreactions at higher sensitivity.
High-β, improved confinement reversed-field pinch plasmas at high density
Authors: Wyman M. D. , Chapman B. E. , Ahn J. W. , Almagri A. F. , Anderson J. K. , Bonomo F. , Brower D. L. , Combs S. K. , Craig D. , Den Hartog D. J. , Deng B. H. , Ding W. X. , Ebrahimi F. , Ennis D. A. , Fiksel G. , Foust C. R. , Franz P. , Gangadhara S. , Goetz J. A. , O'Connell R. , Oliva S. P. , Prager S. C. , Reusch J. A. , Sarff J. S. , Stephens H. D. , Yates T.
Published: January 2008

In Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] discharges where improved confinement is brought about by modification of the current profile, pellet injection has quadrupled the density, reaching ne=4×1019m−3. Without pellet injection, the achievable density in improved confinement discharges had been limited by edge-resonant tearing instability. With pellet injection, the total beta has been increased to 26%, and the energy confinement time is comparable to that at low density. Pressure-driven local interchange and global tearing are predicted to be linearly unstable. Interchange has not yet been observed experimentally, but there is possible evidence of pressure-driven tearing, an instability usually driven by the current gradient in the reversed-field pinch.
Blue emission from Eu2+-doped high silica glass by near-infrared femtosecond laser irradiation
Authors: Qiao Yanbo , Chen Danping , Ren Jinjun , Wu Botao , Qiu Jianrong , Akai Tomoko
Published: January 2008

Eu 2 + -doped high silica glass (HSG) is fabricated by sintering porous glass which is impregnated with europium ions. Eu2+-doped HSG is revealed to yield intense blue emission excited by ultraviolet (UV) light and near-infrared femtosecond laser. The emission profile obtained by UV excitation can be well traced by near-infrared femtosecond laser. The upconversion emission excited by 800 nm femtosecond laser is considered to be related to a two-photon absorption process from the relationship between the integrated intensity and the pump power. A tentative scheme of upconverted blue emission from Eu2+-doped HSG was also proposed. The HSG materials presented herein are expected to find applications in high density optical storage and three-dimensional color displays.
Rheological behavior probed by vibrating microcantilevers
Authors: Belmiloud Naser , Dufour Isabelle , Colin Annie , Nicu Liviu
Published: January 2008

The aim of this paper is to demonstrate that vibrating microcantilevers can be used to quantify fluid properties such as density and viscosity. Contrary to classical rheological measurements using microcantilevers, the development of the proposed microrheometer is based on the measurement of fluid properties over a range of vibration frequencies, without necessarily being restricted to resonant phenomena. To this end, an analytical model is implemented and, when combined with measurements, allows the determination of the viscosity as a function of frequency. The preliminary results are encouraging for the development of a useful microrheometer on a silicon chip for microfluidic applications.
Lateral-displacement influence on the levitation force in a superconducting system with translational symmetry
Authors: Del–Valle Nuria , Sanchez Alvaro , Navau Carles , Chen Du-Xing
Published: January 2008

The unique properties of superconductors make the design of levitation devices possible. In some of them, lateral displacements of the superconducting levitating part often result in a decrease in the levitation force, which can cause a critical malfunction of the system. In this work, the authors theoretically analyze the levitation force of a system consisting of an infinitely long superconductor over an infinitely long permanent-magnet guideway using a realistic model based on a magnetic-energy minimization procedure, from which they give the physical keys for understanding the levitation force reduction after lateral displacements and how to minimize these effects.
Fabrication and crystal line patterning of Li1.3Al0.3Ti1.7(PO4)3 ion conductive glass by Ni atom heat processing method
Authors: Pang Maolin , Suzuki Ryota , Saito Makoto , Machida Ken-ichi , Hanzawa Hiromasa , Nojiri Yoshihiro , Tanase Shigeo
Published: January 2008

Li 1.3 Al 0.3 Ti 1.7 ( P O 4 ) 3 conductive crystal lines composed of closely compacted fine particles were patterned on the surface of 13.9Li2O–8.9Al2O3–37.6TiO2–38.6P2O5–1NiO (mol %) precursor glass by a continuous wave Yb fiber laser irradiation (λ=1078nm) using the nickel atom heat processing method. Homogeneous and smooth crystal lines with a uniform width of 30μm were obtained with a laser power of 1.3W. The Li+ ion conductivity of the laser patterned glass was about two orders of magnitude higher than that of the glass matrix due to the formation of Li1.3Al0.3Ti1.7(PO4)3 conductive crystalline phase by Yb fiber laser irradiation.
Elastic response of the resurrection fern Polypodium polypodioides during rehydration
Authors: Helseth L. E.
Published: January 2008

The resurrection fern (Polypodium polypodioides) has a remarkable elastic reponse, where the fast water uptake of the fern upon rehydration is accompanied by a significant reduction in its Young’s modulus. In this letter, we discuss the fern’s elastic response and suggest that by mimicking its structure, one should be able to design materials exhibiting interesting elastic behavior.
High tensile strength reliability in a bulk metallic glass
Authors: Yao J. H. , Wang J. Q. , Lu L. , Li Y.
Published: January 2008

We report high strength reliability under tension of a bulk metallic glass (BMG), demonstrated by its high uniformity in strength found over a statistically significant number of specimens, despite the fact that the samples all showed no macroscopic plasticity. Weibull statistical analysis showed that the Weibull modulus of the material is 36.5, which is much higher than the values of more typical brittle materials, further confirming BMGs’ high reliability [Appl. Mech. Rev. 5, 449 (1952)].
High field sensitivity at room temperature in p-n junction based bilayered manganite devices
Authors: Vachhani P. S. , Markna J. H. , Kuberkar D. G. , Choudhary R. J. , Phase D. M.
Published: January 2008

The thickness dependent current-voltage (I-V) properties of the bilayered La0.6Pr0.2Sr0.2MnO3 (LPSMO)∕Nb-SrTiO3 (SNTO) p-n junction devices having two different thicknesses, grown using pulsed laser deposition (PLD) technique, have been studied. The I-V curves of these bilayered junctions show good rectifying behavior and also exhibit large positive magnetoresistance (MR) at room temperature. The p-n junction having LPSMO thickness of 200nm exhibits low saturation voltage (VC) and high positive MR as compared to junction with 100nm p-type LPSMO layer. Distinct feature such as large positive MR with respect to temperature can be understood in terms of thickness dependent modifications in the film-substrate interface.
Discretely guided electromagnetic effective medium
Authors: Kempa K. , Wang X. , Ren Z. F. , Naughton M. J.
Published: January 2008

A material comprised of an array of subwavelength coaxial waveguides decomposes incident electromagnetic waves into spatially discrete wave components, propagates these components without frequency cutoff, and reassembles them on the far side of the material. The propagation of these wave components is fully controlled by the physical properties of the waveguides and their geometrical distribution in the array. This allows for an exceptional degree of control over the electromagnetic response of this effective medium, with numerous potential applications. With the development of nanoscale subwavelength coaxial waveguides, these applications (including metamaterial functionality) can be enabled in the visible frequency range.
First-principles calculations of the dielectric properties of silicon nanostructures
Authors: Hamel S. , Williamson A. J. , Wilson H. F. , Gygi F. , Galli G. , Ratner E. , Wack D.
Published: January 2008

We have investigated the static dielectric properties of silicon rods and slabs below 10nm, in the long wavelength limit, by using first-principles density functional theory calculations. Surface structure is found to be the most important factor affecting the changes of the dielectric response at the nanoscale, compared to that of bulk Si, with significant differences observed between slabs and finite rods of similar lateral dimensions.
The myocardin-related transcription factor, MASTR, cooperates with MyoD to activate skeletal muscle gene expression
Authors: Meadows Stryder M. , Warkman Andrew S. , Salanga Matthew C. , Small Eric M. , Krieg Paul A.
Published: January 2008

The myocardin family proteins (myocardin, MRTF-A, and MRTF-B) are serum response factor (SRF) cofactors and potent transcription activators. Gene-ablation studies have indicated important developmental functions for myocardin family proteins primarily in regulation of cardiac and smooth muscle development. Using
Xenopus
genome and cDNA databases, we identified a myocardin-related transcription factor expressed specifically in the skeletal muscle lineage. Synteny and sequence alignments indicate that this gene is the frog orthologue of mouse
MASTR
[Creemers EE, Sutherland LB, Oh J, Barbosa AC, Olson EN (2006) Coactivation of MEF2 by the SAP domain proteins myocardin and MASTR.
Mol Cell
23:83–96]. Inhibition of MASTR function in the
Xenopus
embryo by using dominant-negative constructions or morpholino knockdown results in a dramatic reduction in expression of skeletal muscle marker genes. Overexpression of MASTR in whole embryos or embryonic tissue explants induces ectopic expression of muscle marker genes. Furthermore, MASTR cooperates with the myogenic regulatory factors MyoD and Myf5 to activate transcription of skeletal muscle genes. An essential function for MASTR in regulation of myogenic development in the vertebrate embryo has not been previously indicated.
Folding domain B of protein A on a dynamically partitioned free energy landscape
Authors: Nelson Erik D. , Grishin Nick V.
Published: January 2008

The B domain of staphylococcal protein A (BdpA) is a small helical protein that has been studied intensively in kinetics experiments and detailed computer simulations that include explicit water. The simulations indicate that BdpA needs to reorganize in crossing the transition barrier to facilitate folding its C-terminal helix (H3) onto the nucleus formed from helices H1 and H2. This process suggests frustration between two partially ordered forms of the protein, but recent φ value measurements indicate that the transition structure is relatively constant over a broad range of temperatures. Here we develop a simplistic model to investigate the folding transition in which properties of the free energy landscape can be quantitatively compared with experimental data. The model is a continuation of the Muñoz–Eaton model to include the intermittency of contacts between structured parts of the protein, and the results compare variations in the landscape with denaturant and temperature to φ value measurements and chevron plots of the kinetic rates. The topography of the model landscape (in particular, the feature of frustration) is consistent with detailed simulations even though variations in the φ values are close to measured values. The transition barrier is smaller than indicated by the chevron data, but it agrees in order of magnitude with a similar α-carbon type of model. Discrepancies with the chevron plots are investigated from the point of view of solvent effects, and an approach is suggested to account for solvent participation in the model.
Genetics of P450 oxidoreductase: Sequence variation in 842 individuals of four ethnicities and activities of 15 missense mutations
Authors: Huang Ningwu , Agrawal Vishal , Giacomini Kathleen M. , Miller Walter L.
Published: January 2008

P450 oxidoreductase (POR) is an electron-donating flavoprotein required for the activity of all microsomal cytochrome P450 enzymes. We sequenced 5,655 bp of the POR gene in a representative population of 842 healthy unrelated individuals in four ethnic groups: 218 African Americans, 260 Caucasian Americans, 179 Chinese Americans, and 185 Mexican Americans. One hundred forty SNPs were detected, of which 43 were found in ≥1% of alleles. Twelve SNPs were in the POR promoter region. Fifteen of 32 exonic variations altered the POR amino acid sequence; 13 of these 15 are previously undescribed missense variations. We found eight indels, only one of which was in the coding region. A previously described variant, A503V, was found on 27.9% of all alleles with some ethnic predilection (19.1% in African Americans, 26.4% in Caucasian Americans, 36.7% Chinese Americans, and 31.0% in Mexican Americans). We built cDNA expression vectors for the 13 previously undescribed missense variants, expressed each protein lacking 27 N-terminal residues in
Escherichia coli
, and assayed the apparent
K
m
and
V
max
of each in four assays: reduction of cytochrome
c
, oxidation of NADPH, 17α-hydroxylase activity of P450c17, and 17,20 lyase activity of P450c17. The catalytic activities of several missense mutants differed substantially in these assays, indicating that each POR mutant must be assayed separately with each potential target P450 enzyme. The activity of A503V was reduced to a modest but statistically significant degree in all four assays, suggesting that it may play an important role in interindividual variation in drug response.
Capsazepine, a synthetic vanilloid that converts the Na,K-ATPase to Na-ATPase
Authors: Mahmmoud Yasser A.
Published: January 2008

Capsazepine (CPZ), a synthetic capsaicin analogue, inhibits ATP hydrolysis by Na,K-ATPase in the presence but not in the absence of K+. Studies with purified membranes revealed that CPZ reduced Na+-dependent phosphorylation by interference with Na+binding from the intracellular side of the membrane. Kinetic analyses showed that CPZ stabilized an enzyme species that constitutively occluded K+. Low-affinity ATP interaction with the enzyme was strongly reduced after CPZ treatment; in contrast, indirectly measured interaction with ADP was much increased, which suggests that composite regulatory communication with nucleotides takes place during turnover. Studies with lipid vesicles revealed that CPZ reduced ATP-dependent digitoxigenin-sensitive22Na+influx into K+-loaded vesicles only at saturating ATP concentrations. The drug apparently abolishes the regulatory effect of ATP on the pump. Drawing on previous homology modeling studies of Na,K-ATPase to atomic models of sarcoplasmic reticulum Ca-ATPase and on kinetic data, we propose that CPZ uncouples an Na+cycle from an Na+/K+cycle in the pump. The Na+cycle possibly involves transport through the recently characterized Na+-specific site. A shift to such an uncoupled mode is believed to produce pumps mediating uncoupled Na+efflux by modifying the transport stoichiometry of single pump units.
Risk and protective factors for delinquency among male adolescent immigrants at different stages of the acculturation process
Authors: Titzmann Peter F. , Raabe Tobias , Silbereisen Rainer K.
Published: January 2008

This cross‐sectional study investigated a model of risk and protective factors of the family, school, and peer environment that predict adolescent delinquent behaviour. Three social groups were compared: newcomer ethnic German adolescent immigrants, experienced ethnic German adolescent immigrants, and native adolescents. Based on theoretical assumptions about processes of acculturation, it was hypothesized that the strength of associations between the variables in the theoretical model would vary between newcomer immigrants and native adolescents and also between newcomer and experienced immigrants, but would be similar for experienced immigrants and native adolescents; these hypotheses were supported. Findings suggest that certain risk factors, such as parental violence and involvement with delinquent peers, are more strongly related to delinquency among newcomer immigrants than among experienced immigrants and native adolescents, whereas certain protective factors, such as parental knowledge and school bonding, seem to be relevant for experienced immigrants and native adolescents only. Results seem to indicate that migration can be seen as phase transition with a stronger impact of risk factors on the development of delinquency among newcomer immigrant adolescents. This has implications for studying acculturation processes in immigrant groups as well as for group‐specific intervention programmes.
Fluid features of the stochastic layer transport in LHD
Authors: Feng Y. , Kobayashi M. , Morisaki T. , Masuzaki S. , Miyazawa J. , Peterson B.J. , Morita S. , Shoji M. , Ida K. , Yamada I. , Narihara K. , Ashikawa N. , Yamada H. , Ohyabu N. , Komori A. , Motojima O. , Sardei F. , Reiter D.
Published: January 2008

The stochastic scrape-off layer (SOL) of the helical divertor configuration in LHD exhibits a rather complex field topology where remnant magnetic islands, thin edge surfaces and stochastic field lines coexist. Using the three-dimensional edge transport code package, EMC3-EIRENE, the paper presents a numerical study of the stochastic layer transport, aimed, first of all, at clarifying to what extent the plasma as a fluid is influenced by the stochastic behaviour of the magnetic field lines. Revealed and analysed are the individual roles of different regions of the stochastic layer for plasma, impurity and neutral transport. Topics addressed and discussed are island flattening effects, flow patterns and flow damping, recycling flux suppression, rollover of divertor flux, detachment and Marfe formation and dynamics. Comparisons with experimental results are also presented.
Nanomechanical evaluation of nickel–titanium surface properties after alkali and electrochemical treatments
Authors: Chrzanowski Wojciech , Neel Ensanya Ali Abou , Armitage David Andrew , Lee Kevin , Walke Witold , Knowles Jonathan Campbell
Published: January 2008

In this paper, the suitability of alkali treatment followed by heat treatment at 600°C, and spark oxidation for nickel–titanium, intended for medical applications such as pins, wires and clamps, was evaluated on the basis of nanomechanical and wear testing. In addition, the chemical composition and topography of the surface layer, wetting ability, corrosion resistance and influence of the heat treatment on structure of the alloy were also investigated. The results showed that the highest hardness was observed for alkali-treated samples, and this could be correlated with the structure of the sample that contained martensite and a higher phase transformation temperature. This treatment caused a very large increase of nickel in the top layer and decreased resistance in pitting corrosion. These results disqualified the treatment to be considered as useful for medical applications. On the other hand, the hardness of the oxidized samples was at the same level as that obtained for ground reference samples. Moreover, the oxide layer was enriched with phosphorus, and it was predominantly composed of TiO
2
and phosphorus oxides. This 3.1 μm thick layer had good adhesion to the substrate as indicated by scratch testing and wear resistant in nanowear testing. However, the oxidation did not significantly increase the corrosion resistance of the alloy compared with reference samples.
Two arms are better than one: parasite variation leads to combined inducible and constitutive innate immune responses
Authors: Hamilton Ruth , Siva-Jothy Mike , Boots Mike
Published: January 2008

Parasites represent a major threat to all organisms which has led to the evolution of an array of complex and effective defence mechanisms. Common to both vertebrates and invertebrates are innate immune mechanisms that can be either constitutively expressed or induced on exposure to infection. In nature, we find that a combination of both induced and constitutive responses are employed by vertebrates, invertebrates and, to an extent, plants when they are exposed to a parasite. Here we use a simple within-host model motivated by the insect immune system, consisting of both constitutive and induced responses, to address the question of why both types of response are maintained so ubiquitously. Generally, induced responses are thought to be advantageous because they are only used when required but are too costly to maintain constantly, while constitutive responses are advantageous because they are always ready to act. However, using a simple cost function but with no
a priori
assumptions about relative costs, we show that variability in parasite growth rates selects for a strategy that combines both constitutive and induced defences. Differential costs are therefore not necessary to explain the adoption of both forms of defence. Clearly, hosts are likely to be challenged by variable parasites in nature and this is sufficient to explain why it is optimal to deploy both arms of the innate immune system.
Tetrachromacy in a butterfly that has eight varieties of spectral receptors
Authors: Koshitaka Hisaharu , Kinoshita Michiyo , Vorobyev Misha , Arikawa Kentaro
Published: January 2008

This paper presents the first evidence of tetrachromacy among invertebrates. The Japanese yellow swallowtail butterfly,Papilio xuthus, uses colour vision when foraging. The retina ofPapiliois furnished with eight varieties of spectral receptors of six classes that are the ultraviolet (UV), violet, blue (narrow-band and wide-band), green (single-peaked and double-peaked), red and broad-band classes. We investigated whether all of the spectral receptors are involved in colour vision by measuring the wavelength discrimination ability of foragingPapilio. We trainedPapilioto take nectar while seeing a certain monochromatic light. We then let the trainedPapiliochoose between two lights of different wavelengths and determined the minimum discriminable wavelength difference Δλ. The Δλfunction ofPapiliohas three minima at approximately 430, 480 and 560 nm, where the Δλvalues approximately 1 nm. This is the smallest value found for wavelength discrimination so far, including that of humans. The profile of the Δλfunction ofPapiliocan be best reproduced by postulating that the UV, blue (narrow-band and wide-band), green (double-peaked) and red classes are involved in foraging.Papiliocolour vision is therefore tetrachromatic.
The Anna's hummingbird chirps with its tail: a new mechanism of sonation in birds
Authors: Clark Christopher James , Feo Teresa J
Published: January 2008

A diverse array of birds apparently make mechanical sounds (called sonations) with their feathers. Few studies have established that these sounds are non-vocal, and the mechanics of how these sounds are produced remains poorly studied. The loud, high-frequencychirpemitted by a male Anna's hummingbird (Calypte anna) during his display dive is a debated example. Production of the sound was originally attributed to the tail, but a more recent study argued that the sound is vocal. Here, we use high-speed video of diving birds, experimental manipulations on wild birds and laboratory experiments on individual feathers to show that the dive sound is made by tail feathers. High-speed video shows that fluttering of the trailing vane of the outermost tail feathers produces the sound. The mechanism is not a whistle, and we propose a flag model to explain the feather's fluttering and accompanying sound. The flag hypothesis predicts that subtle changes in feather shape will tune the frequency of sound produced by feathers. Many kinds of birds are reported to create aerodynamic sounds with their wings or tail, and this model may explain a wide diversity of non-vocal sounds produced by birds.
STAR family RNA-binding protein ASD-2 regulates developmental switching of mutually exclusive alternative splicing in vivo
Authors: Ohno Genta , Hagiwara Masatoshi , Kuroyanagi Hidehito
Published: January 2008

Alternative splicing of pre-mRNAs greatly contributes to the spatiotemporal diversity of gene expression in metazoans. However, the molecular basis of developmental regulation and the precise sequence of alternative pre-mRNA processing in vivo are poorly understood. In the present study, we focus on the developmental switching of the mutually exclusive alternative splicing of the let-2 gene of Caenorhabditis elegans from the exon 9 form in embryos to the exon 10 form in adults. By visualizing the usage of the let-2 mutually exclusive exons through differential expression of green fluorescent protein (GFP) and red fluorescent protein (RFP), we isolated several switching-defective mutants and identified the alternative splicing defective-2 (asd-2) gene, encoding a novel member of the evolutionarily conserved STAR (signal transduction activators of RNA) family of RNA-binding proteins. Comparison of the amounts of partially spliced let-2 RNAs in synchronized wild-type and asd-2 mutant worms suggested that either of the introns downstream from the let-2 mutually exclusive exons is removed prior to the removal of the upstream ones, and that asd-2 promotes biased excision of intron 10 in the late larval stages. We propose that the developmental switching between alternative sequences of intron removal determines the ratio between the mature let-2 mRNA isoforms.
Phosphorylation of ERK/MAP kinase is required for long-term potentiation in anatomically restricted regions of the lateral amygdala in vivo
Authors: Schafe Glenn E. , Swank Michael W. , Rodrigues Sarina M. , Dȩbiec Jacek , Doyère Valérie
Published: January 2008

We have previously shown that the extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/ MAPK) is transiently activated in anatomically restricted regions of the lateral amygdala (LA) following Pavlovian fear conditioning and that blockade of ERK/MAPK activation in the LA impairs both fear memory consolidation and long-term potentiation (LTP) in the amygdala, in vitro. The present experiments evaluated the role of the ERK/MAPK signaling cascade in LTP at thalamo-LA input synapses, in vivo. We first show that ERK/MAPK is transiently activated/phosphorylated in the LA at 5 min, but not 15 or 60 min, after high-frequency, but not low-frequency, stimulation of the auditory thalamus. ERK activation induced by LTP-inducing stimulation was anatomically restricted to the same regions of the LA previously shown to exhibit ERK regulation following fear conditioning. We next show that intra-LA infusion of U0126, an inhibitor of ERK/MAPK activation, impairs LTP at thalamo-LA input synapses. Collectively, results demonstrate that ERK/MAPK activation is necessary for synaptic plasticity in anatomically defined regions of the LA, in vivo.
Distinct single but not necessarily repeated tetanization is required to induce hippocampal late-LTP in the rat CA1: Figure 1.
Authors: Sajikumar Sreedharan , Navakkode Sheeja , Frey Julietta U.
Published: January 2008

The protein synthesis-dependent form of hippocampal long-term potentiation (late-LTP) is thought to underlie memory. Its induction requires a distinct stimulation strength, and the common opinion is that only repeated tetani result in late-LTP whereas as single tetanus only reveals a transient early-LTP. Properties of LTP induction were compared to learning processes where repetition is often the prerequisite for a long-lasting memory. However, also single events can lead to manifested memory. If LTP subserves processes of learning, similar results should be detectable for LTP. Here we show that a single tetanus is sufficient to induce late-LTP requiring dopaminergic co-transmission during induction.
Reconsolidation of appetitive memories for both natural and drug reinforcement is dependent on β-adrenergic receptors
Authors: Milton Amy L. , Lee Jonathan L.C. , Everitt Barry J.
Published: January 2008

We have investigated the neurochemical mechanisms of memory reconsolidation and, in particular, the functional requirement for intracellular mechanisms initiated by β-adrenergic signaling. We show that propranolol, given in conjunction with a memory reactivation session, can specifically disrupt the conditioned reinforcing properties of a previously appetitively reinforced conditioned stimulus (CS), whether the stimulus had been associated with self-administered cocaine or with sucrose. These data show that memories for both drug and nondrug CS–US associations are dependent on β-adrenergic receptor-mediated signaling for their reconsolidation, with implications for the potential development of a novel treatment for drug addiction and some forms of obesity.
Liming upland grassland: the effects on earthworm communities and the chemical characteristics of carbon in casts
Authors: Bishop H. O. , Grieve I. C. , Chudek J. A. , Hopkins D. W.
Published: January 2008

Different earthworm species have different tolerances of acid soil conditions, and the application of lime to upland grassland to improve the grazing quality may therefore alter the size and diversity of the earthworm community. Altering soil properties may also affect the chemical characteristics of organic C in earthworm casts. We surveyed the earthworm community of an upland grassland in southern Scotland at the outset of annual lime applications, and after 3 years, and used 13C nuclear magnetic resonance (NMR) spectroscopy to assess the distribution of C between different functional groups in the organic matter. In addition, soil was incubated for 8 weeks with several earthworm species in the presence or absence of lime, and the earthworm casts were subsequently analysed by 13C NMR spectroscopy. Liming did not significantly affect earthworm abundance or species diversity, but it did affect the chemical composition of the casts. Casts from earthworms incubated in unlimed soil had greater ratios of alkyl‐C to O−alkyl‐C, indicative of more decomposed, recalcitrant C, and spectra from litter‐feeding species had the greatest intensities of O−alkyl‐C signals. In limed soil, the largest O−alkyl‐C signal intensities were not restricted to litter‐feeding species, indicating an increase in the quality of organic matter ingested by geophagous species.
A method for spatial freshwater conservation prioritization
Authors: MOILANEN ATTE , LEATHWICK JOHN , ELITH JANE
Published: January 2008

1. Freshwater ecosystems are amongst the most threatened and poorly protected globally. They continue to be degraded through habitat loss, pollution and invading species and conservation measures are urgently needed to halt declining trends in their biodiversity and integrity.

2. During the past decade a suite of decision support tools and computational approaches have been developed for efficient and targeted conservation action in terrestrial or marine ecosystems. These methods may be poorly suited for planning in freshwater systems because connectivity in terrestrial and marine systems is typically modelled in a way unsuitable for rivers, where connectivity has a strong directional component.

3. We modify the conservation prioritization method and software,zonation, to account for connectivity in a manner better suited to freshwater ecosystems. Prioritization was performed using subcatchment/catchment‐based planning units and connectivity was modified to have directional upstream and downstream components consistent with the ecology of our target species.

4. We demonstrate this modified method for rivers and streams in the southern North Island of New Zealand. Data included predicted occupancy from boosted regression tree models of species distributions for 18 fish species. The study area covered 2.1 million hectares and included 394 first‐ to fourth order catchment or subcatchment planning units.

5. Realistic modelling of connectivity had a major influence on the areas proposed for conservation. If connectivity was ignored, recommended conservation areas were very fragmented. By contrast, when connectivity was modelled, high priority conservation targets consisted of entire river basins or headwater subcatchments.

6. The proposed method serves as a starting point for the implementation of reserve selection methods in river ecosystems.