bluuebunny/crossref_metadata_2025 huggingface dataset:
Decreased hepatosplanchnic antioxidant uptake during hepatic ischaemia/reperfusion in patients undergoing liver resection
Authors: van de POLL Marcel C. G. , Dejong Cornelis H. C. , Fischer Marc A. J. G. , Bast Aalt , Koek Ger H.
Published: March 2008

Oxidative stress mediates cell injury during ischaemia/reperfusion. On the other hand, experimental findings suggest that ROS (reactive oxygen species) induce processes leading to ischaemic preconditioning. The extent and source of oxidative stress and its effect on antioxidant status in the human liver during intermittent ischaemia and reperfusion remains ill-defined. Therefore the aim of the present study was to investigate the occurrence of oxidative stress in humans undergoing liver resection. Liver biopsies, and arterial and hepatic venous blood samples were taken from ten patients undergoing hepatectomy with an intermittent Pringle manoeuvre. Plasma MDA (malondialdehyde) and hepatic GSSG levels were measured as markers of oxidative stress and plasma uric acid as a marker of xanthine oxidase activity. In addition, changes in hepatosplanchnic consumption of plasma antioxidants and hepatic levels of carotenoids and glutathione (GSH) were measured. After ischaemia, hepatosplanchnic release of MDA and increased hepatic GSSG levels were found. This was accompanied by the release of uric acid, reflecting xanthine oxidase activity. During reperfusion, ongoing oxidative stress was observed by further increases in hepatic GSSG content and hepatosplanchnic MDA release. Uric acid release was minimal during reperfusion. A gradual decrease in plasma antioxidant capacity and net hepatosplanchnic antioxidant uptake was observed upon prolonged cumulative ischaemia. Oxidative stress occurs during hepatic ischaemia in man mainly due to xanthine oxidase activity. Interestingly, the gradual decline in plasma antioxidant capacity and net hepatosplanchnic antioxidant uptake during prolonged cumulative ischaemia, preserved both hydrophilic and lipophilic hepatic antioxidant levels. Decreasing plasma levels and net hepatosplanchnic uptake of plasma antioxidants may warrant antioxidant supplementation, although it should be clarified to what extent limitation of oxidative stress compromises ROS-dependent pathways of ischaemic preconditioning.
Killer cells in chronic obstructive pulmonary disease
Authors: Fairclough Lucy , Urbanowicz Richard A. , Corne Jonathan , Lamb Jonathan R.
Published: March 2008

COPD (chronic obstructive pulmonary disease) is a treatable and preventable disease state, characterized by progressive airflow limitation that is not fully reversible. It is a current and growing cause of mortality and morbidity worldwide, with the WHO (World Health Organization) projecting that total deaths attributed to COPD will increase by more than 30% in the next 10 years. The pathological hallmarks of COPD are destruction of the lung parenchyma (pulmonary emphysema), inflammation of the central airways (chronic bronchitis) and inflammation of the peripheral airways (respiratory bronchiolitis). The destructive changes and tissue remodelling observed in COPD are a result of complex interactions between cells of the innate and adaptive immune systems. The focus of the present review is directed towards the role of CD8+ T-lymphocytes, NK (natural killer) cells and NKT cells (NK T-cells). These three classes of killer cell could all play an important part in the pathogenesis of COPD. The observed damage to the pulmonary tissue could be caused in three ways: (i) direct cytotoxic effect against the lung epithelium mediated by the activities of perforin and granzymes, (ii) FasL (Fas ligand)-induced apoptosis and/or (iii) cytokine and chemokine release. The present review considers the role of these killer cells in COPD.
Is adipose tissue lipolysis always an adaptive response to starvation?: implications for non-alcoholic fatty liver disease
Authors: Gan Seng Khee , Watts Gerald F.
Published: March 2008

The physiological response to starvation involves increased muscle proteolysis and adipose tissue lipolysis that supply amino acids and non-esterified fatty acids (‘free fatty acids’) for gluconeogenesis, oxidation and ketogenesis. In the present issue of Clinical Science, Moller and co-workers show that, in humans, IHL (intrahepatic lipid) content, measured using 1H-magnetic resonance spectroscopy, increases following 36 h of fasting, with a direct association with plasma levels of 3-hydroxybutyrate. The observation raises interesting questions as to how IHL levels increase in a situation of increased mitochondrial fatty acid oxidation and ketogenesis. Possible mechanisms for increased IHLs include reduced apoB-100 (apolipoprotein B-100) production and hepatic lipid export, and/or impaired mitochondrial function resulting from increased oxidative stress, with diversion of fatty acids for esterification. The accumulation of IHL during prolonged fasting may, therefore, reflect a maladaptive response to increased non-esterified fatty acid delivery to the liver that unmasks a subtle defect in mitochondrial function. This could have implications for the pathogenesis of the common human disorder of non-alcoholic fatty liver disease. The accumulation of IHLs observed with prolonged fasting may also explain exacerbations of steatohepatitis seen sometimes with rapid weight loss, anorexia nervosa and parenteral nutrition. The findings also suggest caution against promoting excessive ketogenesis with weight-loss regimens.
Low temperature plasma channels generated in microcavity trenches with widths of 20–150μm and aspect ratios as large as 104:1
Authors: Lu M. , Park S.-J. , Cunningham B. T. , Eden J. G.
Published: March 2008

Low temperature plasma channels with widths as small as 20μm, cross-sectional areas of 400–12000μm2, and aspect ratios (channel length to width) of up to 104:1 have been generated on a steady state basis within sealed microcavity trenches fabricated by replica molding. With lengths up to 1m and volumes of 10−5–∼10−2cm3, these channels are situated in a dielectric barrier structure having a transverse, buried electrode geometry and are sustained by power loadings as high as ∼1.2kWcm−3. Current densities of ∼5–10Acm−2 and estimated electron densities of ∼1011–1013cm−3 are produced with a 20kHz sinusoidal voltage of Vrms=225–325V, rendering these channels of interest as on-chip plasma reactors or nonlinear optical conversion media. With the transversely excited, photolithographically defined microcavity structures reported here, plasma channels of at least several meters in length, and having an arbitrary, folded geometric pattern, can be generated.
Structure and magnetic properties of NdFeB powder surrounded with layer of rare-earth fluorides
Authors: Komuro Matahiro , Satsu Yuichi
Published: March 2008

The effect of a layer of rare-earth fluorides on the structure and magnetic properties of NdFeB powders was studied. Rare-earth fluorides such as REFx (RE: rare-earth element, x=2 or 3) were grown using fluoride liquid solutions in order to cover the surface of the NdFeB powders. For NdFx-coated NdFeB powder, NdF3 with a hexagonal structure was grown below 400°C. A structure change from NdF3 to cubic NdF2 was observed after annealing at the temperature of 400°C or more. Coercivity (iHc) for 3vol% NdFx-coated NdFeB powder decreased to 14.0 from 15.0kOe for noncoated NdFeB powder after annealing at 800°C. The rare-earth fluoride layers of LaFx-, TbFx-, and DyFx-coated NdFeB powders showed a iHc of 16.8, 16.6, and 16.4kOe, respectively, all of which were higher than that for noncoated NdFeB powder, indicating a diffusion of rare-earth atoms in the fluoride layer.
Properties of a class of vector hysteron models
Authors: Cardelli E. , Della Torre E. , Faba A.
Published: March 2008

In this paper we present a vector hysteron model, which is a generalization in three dimensions of the classical scalar Preisach model and an extension to the radial vector model previously published. We show that the vector model satisfies the second principle of thermodynamics. In addition the properties of the vector deletion and congruency are discussed. An example applied to a Si–Fe commercial steel is presented.
Approximations to Brillouin functions for analytic descriptions of ferromagnetism
Authors: Arrott A. S.
Published: March 2008

The statistical theory of magnetism leads to the magnetic field appearing in the two terms of the Brillouin function, both of which are transcendental, making it impossible to solve explicitly for the argument of that function. The replacement of the Brillouin function BJ(x) by a square root function yields simple algebraic expressions for mean field treatments of cooperative magnetic phenomena. This is useful in the teaching of ferromagnetism.
Electrical Curie temperature modulation in (Ga,Mn)As field-effect transistors with Mn composition from 0.027 to 0.200
Authors: Nishitani Y. , Chiba D. , Matsukura F. , Ohno H.
Published: March 2008

The authors have fabricated field-effect transistor structures with a ferromagnetic Ga1−xMnxAs channel having Mn composition of x=0.027–0.200. The samples with larger x have higher Curie temperature TC and hole concentration p, while the controllable range of TC by applying external electric field does not increase with x. x dependence of effective Mn composition is also described.
Vibrational ground state properties of H5+ and its isotopomers from diffusion Monte Carlo calculations
Authors: Acioli Paulo H. , Xie Zhen , Braams Bastiaan J. , Bowman Joel M.
Published: March 2008

Diffusion Monte Carlo computations, with and without importance sampling, of the zero-point properties of H5+ and its isotopomers using a recent high accuracy global potential energy surface are presented. The global minimum of the potential possesses C2v symmetry, but the calculations predict a D2d geometry for zero-point averaged structure of H5+ with one H atom “in the middle” between two HH diatoms. The predicted zero-point geometries of the deuterated forms have H in the middle preferred over D in the middle and for a nonsymmetric arrangement of D atoms the preferred arrangement is one which maximizes the number of D as the triatomic ion. We speculate on the consequences of these preferences in scattering of H2+H3+ and isotopomers at low energies, such as those in the interstellar medium.
MgO based picotesla field sensors
Authors: Chaves R. C. , Freitas P. P. , Ocker B. , Maass W.
Published: March 2008

MgO magnetic tunnel junctions with RA=150Ωμm2 and tunnel magnetic resistance=100% were patterned into pillars with different geometries with areas up to 2000μm2. Sensors were incorporated in 500nm thick Co94Zr3Nb4 flux guides with different shapes and free layer stabilization was achieved through internal (Co66Cr16Pt18 pads) and external longitudinal bias fields (3.5mT). Sensitivities of 870%∕mT were obtained in the center of the transfer curve. Noise levels of 97pT∕Hz0.5 at 10Hz, 51pT∕Hz0.5 at 30Hz, and 2pT∕Hz0.5 at 500kHz were measured in the linear region of the transfer curve.
Contractions of invariants of Lie algebras with applications to classical inhomogeneous Lie algebras
Authors: Weimar-Woods Evelyn
Published: March 2008

We study in full generality the contraction of invariants of finite-dimensional Lie algebras and give some illustrative examples. Our applications show that the contraction method is not only quite flexible but also has the advantage over other methods that independent invariants can be contracted into independent ones and that they appear in compact tensorial form. For our applications of physical interest, we can restrict ourselves to polynomial invariants (Casimir operators) and generalized Inönü–Wigner contractions. We show how to get all invariants of the inhomogeneous Lie algebras iso(p,q),iu(p,q),isl(n,R), and isp(2n,R) from those of the homogeneous Lie algebras. These invariants are all known, but our results for isl(n,R) and isp(2n,R) appear in a much more desirable form.
Shock-bubble interactions: Features of divergent shock-refraction geometry observed in experiments and simulations
Authors: Ranjan Devesh , Niederhaus John H. J. , Oakley Jason G. , Anderson Mark H. , Bonazza Riccardo , Greenough Jeffrey A.
Published: March 2008

The interaction of a planar shock wave with a spherical bubble in divergent shock-refraction geometry is studied here using shock tube experiments and numerical simulations. The particular case of a helium bubble in ambient air or nitrogen (A≈−0.8) is considered, for 1.4<M<3.0. Experimental planar laser diagnostics and three-dimensional multifluid Eulerian simulations clearly resolve features arising as a consequence of divergent shock refraction, including the formation of a long-lived primary vortex ring, as well as counter-rotating secondary and tertiary upstream vortex rings that appear at late times for M⩾2. Remarkable correspondence between experimental and numerical results is observed, which improves with increasing M, and three-dimensional effects are found to be relatively insignificant. Shocked-bubble velocities, length scales, and circulations extracted from simulations and experiments are used successfully to evaluate the usefulness of various analytical models, and characteristic dimensionless time scales are developed that collapse temporal trends in these quantities. Those linked directly to baroclinicity tend to follow time scales based on shock wave speeds, while those linked to interface deformation and vortex- or shear-induced motion tend to follow a time scale based on the postshock flow speed, though no single time scale is found to be universally successful.
Role of oxide barrier in intergranular tunnel junctions: An enhanced magnetoresistance in SiO2 and ZnO coated Fe3O4 nanoparticle compacts
Authors: Mohan Kant K. , Sethupathi K. , Ramachandra Rao M. S.
Published: March 2008

A systematic study of oxide coated magnetic nanoparticles is carried out to understand and evaluate the effect of oxide tunnel barrier on the magnetoresistance (MR) of magnetite core-shell nanocompacts. SiO2 and ZnO coated Fe3O4 nanoparticles with a shell thickness of ∼2nm have been synthesized and characterized. Magnetic measurements on oxide coated Fe3O4 nanoparticles reveal blocking behavior and superparamagnetism below ∼200K. The magnitude of electrical resistivity at room temperature of SiO2 and ZnO coated Fe3O4 compacts is found to be two to five orders higher than that of pure nanocrystalline Fe3O4 compacts due to resulting insulating oxide layer between magnetite domains. For these nanocompacts, large low field magnetoresistances of −11.5% and −5.8% are achieved in an applied magnetic field of 1T at 100K that could have origins of spin-dependent tunnel MR across the nanometric granules of Fe3O4 safely embedded in insulating oxide matrix.
Solutions for a Schrödinger equation with a nonlocal term
Authors: Lenzi E. K. , de Oliveira B. F. , da Silva L. R. , Evangelista L. R.
Published: March 2008

We obtain time dependent solutions for a Schröndiger equation in the presence of a nonlocal term by using the Green function approach. These solutions are compared with recent results obtained for the fractional Schrödinger equation as well as for the usual one. The nonlocal term incorporated in the Schrödinger equation may also be related to the spatial and time fractional derivative and introduces different regimes of spreading of the solution with the time evolution.
Local biaxiality in cholesteric liquid crystals from the surface interaction model
Authors: Frezzato Diego , Moro Giorgio J.
Published: March 2008

The feature of local biaxiality of the orientational order in twisted nematics and cholesteric liquid-crystalline phases is faced by modeling the mean field orientational potential on the basis of the surface interaction model [A. Ferrarini, G. J. Moro, P. L. Nordio, and G. R. Luckhurst, Mol. Phys. 77, 1 (1992)]. Here we present a tool for the complete parameterization of the potential for general molecular structures and recover the long-pitch approximation usually invoked to model the molecular order in these phases. The method is applied to archetype molecular geometries (an ellipsoidal object, a conical object, a lath-shaped molecule, and the shape’s enantiomers of a propellerlike molecule) in order to evaluate the dependence of the second-rank orientational order parameters on the pitch of the phase. Special emphasis is given to the so-called biaxiality parameter B [Z. Yaniv, N. A. P. Vaz, G. Chidichimo, and J. W. Doane, Phys. Rev. Lett. 47, 46 (1981)], which can be experimentally determined by the analysis of time-averaged H2-NMR spectra of deuterated probes dissolved in the twisted phase. The model calculations show how probes with different geometries are sensitive to the local biaxiality.
Approximating a wavefunction as an unconstrained sum of Slater determinants
Authors: Beylkin Gregory , Mohlenkamp Martin J. , Pérez Fernando
Published: March 2008

The wavefunction for the multiparticle Schrödinger equation is a function of many variables and satisfies an antisymmetry condition, so it is natural to approximate it as a sum of Slater determinants. Many current methods do so, but they impose additional structural constraints on the determinants, such as orthogonality between orbitals or an excitation pattern. We present a method without any such constraints, by which we hope to obtain much more efficient expansions and insight into the inherent structure of the wavefunction. We use an integral formulation of the problem, a Green’s function iteration, and a fitting procedure based on the computational paradigm of separated representations. The core procedure is the construction and solution of a matrix-integral system derived from antisymmetric inner products involving the potential operators. We show how to construct and solve this system with computational complexity competitive with current methods.
Nanocrystalline diamond embedded in hydrogenated fullerenelike carbon films
Authors: Wang Chengbing , Wang Qi , Wang Zhou , Yang Shengrong , Zhang Junyan
Published: March 2008

Diamond particles, with size of about 100nm, embedded in a fullerenelike carbon matrix film prepared at low substrate temperature (300°C) are observed by high-resolution transmission electron microscopy. The diamond formation and growth mechanism were proposed to be the consequence of the converting of fullerenelike sp2 carbon to sp3 bonded amorphous carbon clusters. The continuous hydrogenation of the curved fullerenelike network caused the clustering of sp3 bonded carbon, and the successive impingement of atomic hydrogen or activated molecular on the sp3 cluster are responsible for the nucleation of diamond.
COBRA-STAR, a five frame point-projection x-ray imaging system for 1MA scale wire-array Z pinches
Authors: Douglass J. D. , Hammer D. A.
Published: March 2008

A new imaging system for 1MA scale wire-array Z-pinch experiments that produces up to five high-resolution x-ray images per experimental pulse has been developed. Calibrated areal density measurements of the Z-pinch plasma can be obtained from each pulse. The system substitutes five molybdenum (Mo) X pinches for the normal copper return-current conductors to provide point sources of x-rays for point-projection radiography. Each backlighting X pinch consists of four Mo wires, the x-ray burst timing of which was controlled by varying the wire diameter (mass) from 10.2to30μm in the five X pinches. Typical images have a 16×8mm2 field of view at the wire array and a magnification of about 6.5:1 on the x-ray-sensitive film. Titanium (Ti) filters in front of the films transmit continuum radiation in the spectral range of 3–5keV. Inclusion on the Ti of a step wedge having known thickness increments of the same material as the wires enables the calibrated areal density measurements to be made of the exploding wire plasmas. Here, we used tungsten (W) step wedges with step thicknesses ranging from 0.015to1.1μm to obtain accurate (±10%) areal density measurements of W plasmas from the spatial profile of film exposure. When imaging arrays that produce intense radiation pulses, a plastic monofilament “quencher” is placed on axis to avoid film saturation. Images have subnanosecond temporal resolution and about 7μm spatial resolution.
Breaking a chaotic secure communication scheme
Authors: JinFeng Hu , JingBo Guo
Published: March 2008

The chaotic direct sequence spread spectrum (CD3S) has been extensively studied and accepted as an approach of chaotic secure communication. However, we find that CD3S is insecure and present the results of breaking CD3S. A modified unscented-Kalman-filter chaos fitting method is proposed. With the proposed method, an intruder can use a different chaotic system to fit the transmitter’s chaotic system and break the CD3S scheme without any knowledge of the chaotic transmitter’s structure, parameters or initial value, even under the following conditions: (A) the chaotic spreading sequence is complex and generated by two chaotic maps; (B) there exists noise in the CD3S signal; (C) the CD3S signal is constructed in frames. Simulation results verify the method.
Numerical Calabi–Yau metrics
Authors: Douglas Michael R. , Karp Robert L. , Lukic Sergio , Reinbacher René
Published: March 2008

We develop numerical methods for approximating Ricci flat metrics on Calabi–Yau hypersurfaces in projective spaces. Our approach is based on finding balanced metrics and builds on recent theoretical work by Donaldson. We illustrate our methods in detail for a one parameter family of quintics. We also suggest several ways to extend our results.
Separation of band-gap overlap in a coaxial Bragg structure operating in higher-order mode at Terahertz frequency
Authors: Lai Ying-Xin , Zhang Shi-Chang
Published: March 2008

Band-gap overlap always occurs when an overmoded coaxial Bragg structure operates in the Terahertz frequency spectrum, which may cause serious competition of undesired modes with the operating mode at the operating frequency. In the present paper it is revealed that band-gap overlap of modes can be efficiently separated by setting the phase difference between the outer- and inner-conductor corrugations to be π. Moreover, the residual side-lobes interaction of the involved modes in a coaxial Bragg structure can be entirely eliminated by applying Hamming-window distribution to both the outer-conductor and inner-rod corrugations. These peculiarities provide potential advantage in constructing a coaxial Bragg cavity with high quality factor for single higher-order-mode operation of a high-power free-electron maser in the Terahertz frequency range.
Target electron collision effects on energy loss straggling of protons in an electron gas at any degeneracy
Authors: Barriga-Carrasco Manuel D.
Published: March 2008

The purpose of the present paper is to describe the effects of target electron collisions on proton energy loss straggling in plasmas at any degeneracy. Targets are considered fully ionized so electronic energy loss is only due to the free electrons. The analysis is focused on targets with electronic density around solid values ne≃1023cm−3 and with temperature around T≃10eV; these targets are in the limit of weakly coupled electron gases. These types of plasma targets have not been studied extensively, though they are very important for inertial confinement fusion. The energy loss straggling is obtained from an exact quantum-mechanical evaluation, which takes into account the degeneracy of the target plasma, and later it is compared with common classical and degenerate approximations. Then electron collisions in the exact quantum-mechanical straggling calculation are considered. Now the energy loss straggling is enhanced for energies smaller than the energy before the maximum, then decreases around this maximum, and finally tends to the same values with respect to noncollisional calculation. Differences with the same results but not taking into account these collisions are as far as 17% in the cases analyzed. As an example, proton range distributions have been calculated to show the importance of an accurate energy straggling calculation.
Dispersive effects on wave-current interaction and vorticity transport in nearshore flows
Authors: Terrile E. , Brocchini M. , Christensen K. H. , Kirby J. T.
Published: March 2008

Frequency dispersive effects on the interaction of waves and currents in a nearshore circulation system are analyzed. By means of both analytical and numerical calculations, we find that dispersive effects are important in the description of the correct amount of the wave forcing, represented, within the generalized-Lagrangian-mean-like approach, by the pseudomomentum p. They are particularly important when describing the flow using depth-averaged velocities. For some configurations, the depth-averaged current is forced not only by the nondispersive terms but also, with the same intensity, by the dispersive forcing terms. In such terms is included a vortex-force dispersive contribution, usually negligible in a small-wave amplitude approximation, which arises because of the presence of dissipative terms.
The stability of a salt-free colloidal dispersion
Authors: Liu Bo-Tau , Hsu Jyh-Ping
Published: March 2008

The electrical potential for the case of two identical, planar parallel particles immersed in a salt-free medium, where the ionic species in the counterions come solely from those that dissociated from the surfaces, is evaluated. Analytical expressions for the electrical potential, the concentration of counterions, and the electrical energy are derived. We show that in a salt-free dispersion, if the separation distance between two particles is sufficiently far, the electrical repulsive force dominates, that is, the total energy is positive and does not have a secondary minimum, which is not the case for a dispersion where both coions and counterions are present. Also, the conditions used to calculate the critical coagulation concentration in the classic Derjaguin–Landau–Verwey–Overbeek theory become inappropriate and the Derjaguin approximation is inapplicable. We show that if the surface charge density exceeds ∼0.04C∕m2, the stability of a salt-free dispersion remains essentially the same. If the surface charge density is sufficiently high, the maximum separation distance between two particles below which coagulation occurs is in the ranges of [0,1nm] and [1,7nm] for the cases where the Hamaker constant is 10−20 and 10−19J, respectively.
Collision and average velocity effects on the ratchet pinch
Authors: Vlad M. , Spineanu F. , Benkadda S.
Published: March 2008

A ratchet-type average velocity VR appears for test particles moving in a stochastic potential and a magnetic field that is space dependent. This model is developed by including particle collisions and an average velocity. We show that these components of the motion can destroy the ratchet velocity but they also can produce significant increase of VR, depending on the parameters. The amplification of the ratchet pinch is a nonlinear effect that appears in the presence of trajectory eddying.
Direct observations for the superprism effect in photonic crystals utilizing negative refraction
Authors: Yang S. Y. , Wu J. Y. , Horng H. E. , Hong Chin-Yih , Yang H. C.
Published: March 2008

In this work, we experimentally explored the negative-refraction superprism effect in photonic crystals by investigating the frequency-dependent negative refractive index of photonic crystals at microwave frequencies from 8.2to8.4GHz. By detecting the spatially distributed intensity of a transmitted microwave whose incident angle is well controlled, we determined the propagating path, the refractive angle, and the refractive index of the transmitted microwave. The highly dispersive relationship between the negative refractive index and the frequency of microwave observed indicates potential applicability of this method for being used in a microwave wavelength demultiplexer by utilizing the negative-refraction superprism effect in photonic crystals.
Spin diode based on a single-walled carbon nanotube
Authors: Weymann I. , Barnaś J.
Published: March 2008

Electronic transport through a single-walled, metallic carbon nanotube weakly coupled to one ferromagnetic and one nonmagnetic lead is analyzed in the sequential tunneling limit. It is shown that both the spin and charge currents flowing through such systems are highly asymmetric with respect to the bias reversal. As a consequence, nanotubes coupled to one nonmagnetic and one ferromagnetic lead can be effectively used as spin diodes whose functionality can be additionally controlled by a gate voltage.
A complex plasma device of large surface area
Authors: Nakamura Y. , Ishihara O.
Published: March 2008

A novel complex plasma device (YCOPEX) to create two-dimensional monolayer plasma crystals of a large surface area of 15×90cm2 is described. The YCOPEX, in which a plasma is produced by a rf discharge of argon gas, is designed to utilize gravitational force to study fundamental physics of complex plasmas. The device may be used for observation of spatial change of a phase state, propagation of waves, and collisions of flowing dust particles with an obstacle. As an example of experiments, neutral drag forces on microspheres are measured using the gravitational force on those particles. The obtained neutral drag force agrees reasonably with the values estimated from Epstein’s formula.
Diffraction of shear waves by a nanosized spherical cavity
Authors: Wang G. F.
Published: March 2008

Surface effects become important in the mechanical performances of nanostructured devices and materials, owing to the increasing ratio of surface to bulk volume. In the present paper, the diffraction of shear waves (S-wave) by a nanosized spherical cavity is studied theoretically based on the surface elasticity theory. It is found that when the cavity size reduces to nanometers, surface effects play a significant role in the diffraction of elastic waves. As an example, the surface effects on the dynamic stress concentration around the spherical cavity are discussed in detail.
Dopant dependent band gap tailoring of hydrothermally prepared cubic SrTixM1−xO3 (M=Ru,Rh,Ir,Pt,Pd) nanoparticles as visible light photocatalysts
Authors: Bae Sang Won , Borse Pramod H. , Lee Jae Sung
Published: March 2008

Nanostructured cubic SrTiO3 particles were hydrothermally synthesized and studied experimentally/theoretically for photoreduction of water. The particles were doped with metal atoms (M=Ru,Rh,Ir,Pt,Pd), which acquired high cyrstallinity after thermal treatment. SrTiO3:Rh showed the highest rate of H2 evolution under λ>420nm photons. The density functional theory calculations of SrTixM1−xO3 (M=Ru,Rh,Ir,Pt) implied that the photocatalytic activity of SrTixRh1−xO3 was due to its suitable band energetics, and the induced hybridized Ti∕Rh orbitals in the bandgap of SrTiO3.
Low voltage performance of epitaxial BiFeO3 films on Si substrates through lanthanum substitution
Authors: Chu Y. H. , Zhan Q. , Yang C.-H. , Cruz M. P. , Martin L. W. , Zhao T. , Yu P. , Ramesh R. , Joseph P. T. , Lin I. N. , Tian W. , Schlom D. G.
Published: March 2008

We have probed the role of La substitution on the ferroelectric properties of epitaxial BiFeO3 films on SrTiO3-templated Si. This provides a mechanism to engineer the rhombohedral distortion in the crystal and, thus, control domain structure and switching. With a 10% La substitution, the (Bi0.9La0.1)FeO3 film showed well-saturated ferroelectric hysteresis loops with a remanent polarization of 45μC∕cm2, a converse piezoelectric coefficient d33 of 45pm∕V, and a dielectric constant of 140. Over this range of La substitution, the coercive field systematically decreases such that a coercive voltage of 1V can been obtained in a 100nm thick film. These results show promise for the ultimate implementation of this lead-free multiferroic operating at voltages in the range of 2–3V.
Modulated optical phase conjugation in rhodamine 110 doped boric acid glass saturable absorber thin films
Authors: Sharma Ramesh C. , Waigh Thomas A. , Singh Jagdish P.
Published: March 2008

The optical phase conjugation signal in nearly nondegenerate four wave mixing was studied using a rhodamine 110 doped boric acid glass saturable absorber nonlinear medium. We have demonstrated a narrow band optical filter (2.56±0.15Hz) using an optical phase conjugation signal in the frequency modulation of a weak probe beam in the presence of two strong counterpropagating pump beams in rhodamine 110 doped boric acid glass thin films (10−4m). Both the pump beams and the probe beam are at a wavelength of 488nm (continuous-wave Ar+ laser). The probe beam frequency was detuned with a ramp signal using a piezoelectric transducer mirror.
Cantilever based optical interfacial force microscope
Authors: Bonander Jeremy R. , Kim Byung I.
Published: March 2008

We developed a cantilever based optical interfacial force microscopy (COIFM) that employs a microactuated silicon cantilever and optical detection method to establish the measurement of the single molecular interactions using the force feedback technique. Through the direct measurement of the COIFM force-distance curves, we have demonstrated that the COIFM is capable of unveiling structural and mechanical information on interfacial water at the single molecular level over all distances between two hydrophilic surfaces.
Transposition of a reconstructed
Harbinger
element in human cells and functional homology with two transposon-derived cellular genes
Authors: Sinzelle Ludivine , Kapitonov Vladimir V. , Grzela Dawid P. , Jursch Tobias , Jurka Jerzy , Izsvák Zsuzsanna , Ivics Zoltán
Published: March 2008

Ancient, inactive copies of transposable elements of the
PIF
/
Harbinger
superfamily have been described in vertebrates. We reconstructed components of the
Harbinger3_DR
transposon in zebrafish, including a transposase and a second, transposon-encoded protein that has a Myb-like trihelix domain. The reconstructed
Harbinger
transposon shows efficient cut-and-paste transposition in human cells and preferentially inserts into a 15-bp consensus target sequence. The Myb-like protein is required for transposition and physically interacts with the N-terminal region of the transposase via its C-terminal domain. The Myb-like protein enables transposition in part by promoting nuclear import of the transposase, by directly binding to subterminal regions of the transposon, and by recruiting the transposase to the transposon ends. We investigated the functions of two transposon-derived human proteins: HARBI1, a domesticated transposase-derived protein, and NAIF1, which contains a trihelix motif similar to that described in the Myb-like protein. Physical interaction, subcellular localization, and DNA-binding activities of HARBI1 and NAIF1 suggest strong functional homologies between the
Harbinger3_DR
system and their related, host-encoded counterparts. The
Harbinger
transposon will serve as a useful experimental system for transposon biology and for investigating the enzymatic functions of domesticated, transposon-derived cellular genes.
Genetic royal cheats in leaf-cutting ant societies
Authors: Hughes William O. H. , Boomsma Jacobus J.
Published: March 2008

Social groups are vulnerable to cheating because the reproductive interests of group members are rarely identical. All cooperative systems are therefore predicted to involve a mix of cooperative and cheating genotypes, with the frequency of the latter being constrained by the suppressive abilities of the former. The most significant potential conflict in social insect colonies is over which individuals become reproductive queens rather than sterile workers. This reproductive division of labor is a defining characteristic of eusocial societies, but individual larvae will maximize their fitness by becoming queens whereas their nestmates will generally maximize fitness by forcing larvae to become workers. However, evolutionary constraints are thought to prevent cheating by removing genetic variation in caste propensity. Here, we show that one-fifth of leaf-cutting ant patrilines cheat their nestmates by biasing their larval development toward becoming queens rather than workers. Two distinct mechanisms appear to be involved, one most probably involving a general tendency to become a larger adult and the other relating specifically to the queen–worker developmental switch. Just as evolutionary theory predicts, these “royal” genotypes are rare both in the population and within individual colonies. The rarity of royal cheats is best explained as an evolutionary strategy to avoid suppression by cooperative genotypes, the efficiency of which is frequency-dependent. The results demonstrate that cheating can be widespread in even the most cooperative of societies and illustrate that identical principles govern social evolution in highly diverse systems.
Role of the Akt pathway in mRNA translation of interferon-stimulated genes
Authors: Kaur Surinder , Sassano Antonella , Dolniak Blazej , Joshi Sonali , Majchrzak-Kita Beata , Baker Darren P. , Hay Nissim , Fish Eleanor N. , Platanias Leonidas C.
Published: March 2008

Multiple signaling pathways are engaged by the type I and II IFN receptors, but their specific roles and possible coordination in the generation of IFN-mediated biological responses remain unknown. We provide evidence that activation of Akt kinases is required for IFN-inducible engagement of the mTOR/p70 S6 kinase pathway. Our data establish that Akt activity is essential for up-regulation of key IFN-α- and IFN-γ-inducible proteins, which have important functional consequences in the induction of IFN responses. Such effects of the Akt pathway are unrelated to regulatory activities on IFN-dependent STAT phosphorylation/activation or transcriptional regulation. By contrast, they reflect regulatory activities on mRNA translation via direct control of the mTOR pathway. In studies using Akt1 and Akt2 double knockout cells, we found that the absence of Akt kinases results in dramatic reduction in IFN-induced antiviral responses, establishing a critical role of the Akt pathway in IFN signaling. Thus, activation of the Akt pathway by the IFN receptors complements the function of IFN-activated JAK–STAT pathways, by allowing mRNA translation of IFN-stimulated genes and, ultimately, the induction of the biological effects of IFNs.
Herbivory-induced changes in the small-RNA transcriptome and phytohormone signaling in
Nicotiana attenuata
Authors: Pandey Shree P. , Shahi Priyanka , Gase Klaus , Baldwin Ian T.
Published: March 2008

Phytohormones mediate the perception of insect-specific signals and the elicitation of defenses during insect attack. Large-scale changes in a plant's transcriptome ensue, but how these changes are regulated remains unknown. Silencing of RNA-directed RNA polymerase 1 (
RdR1
) makes
Nicotiana attenuata
highly susceptible to insect herbivores, suggesting that defense elicitation is under the direct control of small-RNAs (smRNAs). Using 454-sequencing, we characterized
N. attenuata
's smRNA transcriptome before and after insect-specific elicitation in wild-type (WT) and
RdR1
-silenced (irRdR1) plants. We predicted the targets of
N. attenuata
smRNAs in the genes related to phytohormone signaling (jasmonic acid, JA-Ile, and ethylene) known to mediate resistance responses, and we measured the elicited dynamics of phytohormone biosynthetic transcripts and phytohormone levels in time-course experiments with field- and glasshouse-grown plants.
RdR1
silencing severely altered the induced transcript accumulation of 8 of the 10 genes, reduced JA, and enhanced ethylene levels after elicitation. Adding JA completely restored the insect resistance of irRdR1 plants. irRdR1 plants had photosynthetic rates, growth, and reproductive output indistinguishable from that of WT plants, suggesting unaltered primary metabolism. We conclude that the susceptibility of irRdR1 plants to herbivores is due to altered phytohormone signaling and that smRNAs play a central role in coordinating the large-scale transcriptional changes that occur after herbivore attack. Given the diversity of smRNAs that are elicited after insect attack and the recent demonstration of the ability of ingested smRNAs to silence transcript accumulation in lepidopteran larvae midguts, the smRNA responses of plants may also function as direct defenses.
Quality Challenge in Iran's Higher Education: A Historical Review
Authors: Farasatkhah Maghsood , Ghazi Mahmood , Bazargan Abbas
Published: March 2008

Higher education at Iran's state-run universities is not supported by a deeply-rooted tradition of quality assessment. For several decades, Iranian universities have not been able to monitor themselves and develop efficient, internal structures of quality assurance. The academics' attempts at internal monitoring have failed, giving way to a system of bureaucratic supervision and control. Recent changes in Iran have given rise to new concepts, including the principle of universities' self-evaluation, based on academic autonomy and scientific freedom. But the dominant tendency in Iran's political structure and administration is still toward external, bureaucratic control. The conflict between more or less advanced texts and typically solid structures is a reflection of inconsistencies within the Iranian society, pursuing its transitional stage.
Iran and the United States: Reconcilable Differences?
Authors: Bahgat Gawdat
Published: March 2008

Hostility between Iran and the United States has intensified since the mid-2000s. America's allegations regarding Iran's nuclear program and its association with terrorist organizations are the main drive for this rising tension. This study focuses on the latter. Specifically, it examines Tehran's ties to militant groups in Iraq, Hezbollah in Lebanon, and Hamas in the Palestinian Territories. I argue that although American and Iranian interests in the region are very different, they are not necessarily mutually exclusive.
Aqa Najafi, Haj Aqa Nurullah, and the Emergence of Islamism in Isfahan 1889–1908
Authors: Martin Vanessa
Published: March 2008

Alongside the burgeoning secular ideas on people and state during the Constitutional Revolution, a movement seeking a modern Islamic state, governed according to the shari'a, also emerged. This article studies the evolution of that movement in Isfahan, first by contrasting the experience of two brothers of very different ages, Aqa Najafi Isfahani and Haj Aqa Nurullah Isfahani, and examining the way the younger became receptive to the Pan-Islamic ideas then current in the Middle East. Second, the article considers in particular the political theory of Aqa Nurullah, which was influenced by his practical experience of institutional innovation in Isfahan. He argued that constitutionalism was implicit to Islam and saw it as generating wealth for Muslims. He also advocated many of the features of later Islamism, including the desire for a strong army.
Nation Building, Democratization and Globalization as Competing Priorities in Ukraine's Education System*
Authors: Janmaat Jan Germen
Published: March 2008

One of the greatest challenges currently facing the new states in Central and Eastern Europe is educational reform. After obtaining independence in the early 1990s, these states were confronted with the immense task of transforming an outdated centralized education system, which was aimed at delivering a loyal communist workforce, into a modern system that would be much more responsive to consumer demands and would recognize and further individual talent. The immensity of the undertaking lies in the fact that three discourses make simultaneous demands on the education system: nation building, democratization and globalization.
State as Transgressor: Šilingas versus the State—A Case Study
Authors: Worthington Svaja Vansauskas
Published: March 2008

The usually cheerful Insight Travel Guide to the Baltic States offers this synopsis of the Baltic situation:

Their independence was sentenced to death by the Nazi–Soviet Pact [the secret 1939 Molotov–Ribbentrop Non-Aggression Pact] just before World War II. The pact envisaged the Baltic States would be parceled out between them, but it was overtaken by events with Hitler's invasion of the Soviet Union. The three states were incorporated into the Soviet Union in 1940 … Among few other people did the Soviet mill grind finer than in Estonia, Latvia and Lithuania … The final injustice was the permanent imposition of Soviet rule and Stalinist terror. Anyone a visitor meets today in the Baltics is likely to have a relation who was sent to Siberia or simply shot.
Sport and the Local Economy: The Effects of Stadia Development on the Commercial Property Market
Authors: Davies Larissa E.
Published: March 2008

The use of sports stadia for economic development and regeneration has gained increasingly credibility in recent years, both academically and in terms of UK urban policy. However, evidence to support the effectiveness of stadia for these purposes is highly variable. This paper uses a comparative case study of the Millennium Stadium and the City of Manchester Stadium to examine the effects of stadia development on the commercial property market, an area of research that has received little attention in the literature. It uses the expert opinion of professionals working in real estate, together with the experience of key stakeholders in Manchester and Cardiff to provide empirical evidence that stadia can create tangible and intangible impacts on the commercial property market, but that these are variable between different sectors. It concludes by arguing the need for further research on the role of stadia in the regeneration process if the impacts of these developments are to be maximised in the future.
Beyond ‘Access’: Internet Use and Take-up of Online Services by Adults Living in Disadvantaged Areas in England
Authors: Devins David , Darlow Alison , Webber Don
Published: March 2008

Much discussion of the ‘digital divide’ has focused around the issue of access to technology and how this plays out in relation to different groups from disadvantaged neighbourhoods. This paper draws on survey data from a national evaluation project to investigate the likelihood of further digital divides emerging as we look beyond ‘access’ to the consumption of e-services. Logit multiple regression is used to test the extent to which a variety of socio-economic characteristics influence the use of e-services including both commercial services and information. The analysis suggests that women, those from a minority ethnic background and people living in less affluent areas are less likely to access commercial services such as online banking and shopping. Gender differences are particularly noticeable in terms of accessing online information, with women significantly less likely to use the Internet to obtain information that may help support their social and economic inclusion.
Cross-borough Business Improvement Districts: Waterloo's Attempt to Become the First Town Centre BID to Cross a Local Authority Boundary
Authors: Santer Helen
Published: March 2008

Waterloo Quarter Business Alliance (WQBA) is a Business Improvement District (BID) operating in the complicated regeneration landscape of the Waterloo area. With a small budget, diverse membership and intentions to become the fist cross-borough BID in a town centre area, this is a challenging but exciting time for local businesses.