bluuebunny/crossref_metadata_2025 huggingface dataset:
Chloroplast DnaJ-like proteins 3 and 4 (CDJ3/4) from Chlamydomonas reinhardtii contain redox-active Fe–S clusters and interact with stromal HSP70B
Authors: Dorn Karolin V. , Willmund Felix , Schwarz Christian , Henselmann Christine , Pohl Thomas , Hess Barbara , Veyel Daniel , Usadel Björn , Friedrich Thorsten , Nickelsen Jörg , Schroda Michael
Published: February 2010

In the present study we report on the identification and characterization of three novel chloroplast-targeted DnaJ-like proteins CDJ3–5, which in addition to their J-domains contain bacterial-type ferredoxin domains. In sequence databases we could identify homologues of CDJ3–5 in green algae, moss and higher plants, but not in cyanobacteria. Phylogenetic analyses allowed us to distinguish two clades containing CDJ3/4 and CDJ5 that must have diverged early in the ancestor of the ‘green lineage’ and have further diversified later on. Molecular and biochemical analysis of CDJ3 and CDJ4 from Chlamydomonas reinhardtii revealed that both proteins are weakly expressed and appear to be localized to the stroma and to thylakoid membranes respectively. The low transcript levels of the CDJ3 and CDJ4 genes declined even further in the initial phase of heat shock, but CDJ3 transcript levels strongly increased after a dark-to-light shift. Accordingly, the Arabidopsis orthologue of CDJ5 was also found to be light-inducible and to be under strong circadian control. CDJ3 and CDJ4 proteins could both be expressed in Escherichia coli and had redox-active Fe–S clusters. In vitro cross-linking studies demonstrated that CDJ3 and CDJ4 interact with chloroplast ATP-bound HSP70B (heat-shock protein 70B), presumably as dimers, and immunoprecipitation studies showed that CDJ3/4 were also in a complex with HSP70B in Chlamydomonas cell extracts. Finally, CDJ3 was found in complexes with apparent molecular masses of approx. 550–2800 kDa, which appeared to contain RNA. We speculate that the CDJ3–5 proteins might represent redox switches that act by recruiting HSP70B for the reorganization of regulatory protein complexes.
Characterization of the transition-metal-binding properties of hepcidin
Authors: Tselepis Chris , Ford Samuel J. , McKie Andrew T. , Vogel Wolfgang , Zoller Heinz , Simpson Robert J. , Diaz Castro Javier , Iqbal Tariq H. , Ward Douglas G.
Published: February 2010

Accumulating evidence suggests that hepcidin, a 25-residue peptide hormone, is the master regulator of iron metabolism. Further evidence suggests that the five N-terminal amino acids are crucial for mediating its biological function. With a histidine residue at position 3, this region also has the potential to bind bivalent metal ions. To characterize this hepcidin–metal interaction in detail, the present study utilizes electrospray MS to measure the binding of a range of metal ions to wild-type and mutant human and murine hepcidins. In addition, the biological effects of these point mutations were tested on Caco-2 and HEK-293T human cell lines and in mice. Our results show that hepcidin-25 can form complexes with copper, nickel and zinc; however, we failed to detect any hepcidin-25 binding to either ferric or ferrous ions. The greatest affinity observed was between hepcidin-25 and copper with a dissociation constant ≪1 μM. Substituting the histidine residue at position 3 in human hepcidin-25 and comparably the asparagine residue at position 3 in murine hepcidin-25 with an alanine residue markedly diminished the affinity for copper. The amino acid substitutions also decreased the biological activity of hepcidin-25; namely repression of ferroportin protein levels and hypoferraemia. In summary, the high affinity of hepcidin for copper suggests that hepcidin could bind copper in vivo and this may be of biological relevance.
Nonequilibrium, thermostats, and thermodynamic limit
Authors: Gallavotti G. , Presutti E.
Published: February 2010

The relation between thermostats of “isoenergetic” and “frictionless” kind is studied and their equivalence in the thermodynamic limit is proven in space dimension d=1,2 and for special geometries, d=3.
Space and time from translation symmetry
Authors: Schwarz A.
Published: February 2010

We show that the notions of space and time in algebraic quantum field theory arise from translation symmetry if we assume asymptotic commutativity. We argue that this construction can be applied to string theory.
Quasiperiodic motions in dynamical systems: Review of a renormalization group approach
Authors: Gentile Guido
Published: February 2010

Power series expansions naturally arise whenever solutions of ordinary differential equations are studied in the regime of perturbation theory. In the case of quasiperiodic solutions the issue of convergence of the series is bedeviled by the so-called small divisor problem. In this paper we review a method recently introduced to deal with such a problem, based on renormalization group ideas and multiscale techniques. Applications to both quasi-integrable Hamiltonian systems [Kolmogorov-Arnold-Moser (KAM) theory] and non-Hamiltonian dissipative systems are discussed. The method is also suited to situations in which the perturbation series diverges and a resummation procedure can be envisaged, leading to a solution which is not analytic in the perturbation parameter: we consider explicitly examples of solutions which are only C∞ in the perturbation parameter, or even defined on a Cantor set.
Capture of instantaneous temperature in oscillating flows: Use of constant-voltage anemometry to correct the thermal lag of cold wires operated by constant-current anemometry
Authors: Berson Arganthaël , Poignand Gaëlle , Blanc-Benon Philippe , Comte-Bellot Geneviève
Published: February 2010

A new procedure for the instantaneous correction of the thermal inertia of cold wires operated by a constant-current anemometer is proposed for oscillating flows. The thermal inertia of cold wires depends both on the wire properties and on the instantaneous incident flow velocity. Its correction is challenging in oscillating flows because no relationship between flow velocity and heat transfer around the wire is available near flow reversal. The present correction procedure requires neither calibration data for velocity nor thermophysical or geometrical properties of the wires. The method relies on the splitting of the time lag of cold wires into two factors, which are obtained using a constant-voltage anemometer in the heated mode. The first factor, which is intrinsic to the wire, is deduced from time-constant measurements performed in a low-turbulence flow. The second factor, which depends on the instantaneous flow velocity, is acquired in situ. In oscillating flows, data acquisition can be synchronized with a reference signal so that the same wire is alternatively operated in the cold mode by a constant-current anemometer and in the heated mode by a constant-voltage anemometer. Validation experiments are conducted in an acoustic standing-wave resonator, for which the fluctuating temperature field along the resonator axis is known independently from acoustic pressure measurements, so that comparisons can be made with cold-wire measurements. It is shown that despite the fact that the wire experiences flow reversal, the new procedure recovers accurately the instantaneous temperature of the flow.
Developments in the theory of universality
Authors: Mastropietro Vieri
Published: February 2010

Recently, a rigorous foundation of several aspects of the theory of universality for statistical mechanics models with continuously varying exponents (among which are interacting planar Ising models, quantum spin chains, and one-dimensional Fermi systems) has been reached; it has its root in the mapping of such systems into fermionic interacting theories and uses the modern renormalization group methods developed in the context of constructive quantum field theory. No use of exact solutions is done and the analysis applies either to solvable or not solvable models. A review of such developments will be given here.
Almost commuting matrices, localized Wannier functions, and the quantum Hall effect
Authors: Hastings Matthew B. , Loring Terry A.
Published: February 2010

For models of noninteracting fermions moving within sites arranged on a surface in three-dimensional space, there can be obstructions to finding localized Wannier functions. We show that such obstructions are K-theoretic obstructions to approximating almost commuting, complex-valued matrices by commuting matrices, and we demonstrate numerically the presence of this obstruction for a lattice model of the quantum Hall effect in a spherical geometry. The numerical calculation of the obstruction is straightforward and does not require translational invariance or introduce a flux torus. We further show that there is a Z2 index obstruction to approximating almost commuting self-dual matrices by exactly commuting self-dual matrices and present additional conjectures regarding the approximation of almost commuting real and self-dual matrices by exactly commuting real and self-dual matrices. The motivation for considering this problem is the case of physical systems with additional antiunitary symmetries such as time-reversal or particle-hole conjugation. Finally, in the case of the sphere—mathematically speaking, three almost commuting Hermitians whose sum of square is near the identity—we give the first quantitative result, showing that this index is the only obstruction to finding commuting approximations. We review the known nonquantitative results for the torus.
Singularities of complex-valued solutions of the two-dimensional Burgers system
Authors: Li Dong , Sinai Yakov G.
Published: February 2010

We consider the two-dimensional viscous Burgers system without external forcing. For complex-valued solutions, due to the loss of maximum principle and energy estimates, smooth solutions can develop finite-time singularities. We construct an open set of six-parameter families of initial conditions such that the corresponding solutions exhibit blowups in finite time.
The principle of locality: Effectiveness, fate, and challenges
Authors: Doplicher Sergio
Published: February 2010

The special theory of relativity and quantum mechanics merge in the key principle of quantum field theory, the principle of locality. We review some examples of its “unreasonable effectiveness” in giving rise to most of the conceptual and structural frame of quantum field theory, especially in the absence of massless particles. This effectiveness shows up best in the formulation of quantum field theory in terms of operator algebras of local observables; this formulation is successful in digging out the roots of global gauge invariance, through the analysis of superselection structure and statistics, in the structure of the local observable quantities alone, at least for purely massive theories; but so far it seems unfit to cope with the principle of local gauge invariance. This problem emerges also if one attempts to figure out the fate of the principle of locality in theories describing the gravitational forces between elementary particles as well. An approach based on the need to keep an operational meaning, in terms of localization of events, of the notion of space-time, shows that, in the small, the latter must loose any meaning as a classical pseudo-Riemannian manifold, locally based on Minkowski space, but should acquire a quantum structure at the Planck scale. We review the geometry of a basic model of quantum space-time and some attempts to formulate interaction of quantum fields on quantum space-time. The principle of locality is necessarily lost at the Planck scale, and it is a crucial open problem to unravel a replacement in such theories which is equally mathematically sharp, namely, a principle where the general theory of relativity and quantum mechanics merge, which reduces to the principle of locality at larger scales. Besides exploring its fate, many challenges for the principle of locality remain; among them, the analysis of superselection structure and statistics also in the presence of massless particles, and to give a precise mathematical formulation to the measurement process in local and relativistic terms; for which we outline a qualitative scenario which avoids the Einstein, Podolski, and Rosen paradox.
Scaling properties of turbulence driven shear flow
Authors: Yan Z. , Tynan G. R. , Holland C. , Xu M. , Muller S. H. , Yu J. H.
Published: February 2010

The characteristics and scaling properties of the turbulence driven shear flow are investigated in a cylindrical laboratory plasma device. For a given plasma pressure, the density fluctuation amplitude and radial particle flux increase with the applied magnetic field. Strong flow shear is found to coexist at high magnetic fields (>700G) with ∼10kHz drift wave turbulence, but not at low magnetic fields (<700G). The absolute value of the divergence of the turbulent Reynolds stress at the shear layer is shown to increase with the magnetic field as well. For a fixed magnetic field, the shear flow is found to decrease as the discharge gas pressure is increased. The density fluctuation amplitude and divergence of the turbulent Reynolds stress also decrease with the plasma pressure. For both situations the cross phase between the radial and azimuthal components of the velocity is found to be a key factor to determine variations in the turbulent Reynolds stress at different magnetic fields and discharge pressures. The results show that the generation of the shear flow is related to the development of specific frequency components of the drift wave turbulence for a variety of plasma conditions. The linear stability analysis shows that the observed variation in the turbulence and shear flow with magnetic field is also consistent with a critical gradient behavior.
Algebraic complementarity in quantum theory
Authors: Petz Dénes
Published: February 2010

This paper is an overview of the concept of complementarity, the relation to state estimation, to Connes–Størmer conditional (or relative) entropy, and to uncertainty relation. Complementary Abelian and noncommutative subalgebras are analyzed. All the known results about complementary decompositions are described and several open questions are included. The paper contains only few proofs, typically references are given.
Twenty five years of two-dimensional rational conformal field theory
Authors: Fuchs Jürgen , Runkel Ingo , Schweigert Christoph
Published: February 2010

A review for the 50th anniversary of the Journal of Mathematical Physics.
Batalin–Vilkovisky integrals in finite dimensions
Authors: Albert C. , Bleile B. , Fröhlich J.
Published: February 2010

The Batalin–Vilkovisky (BV) method is the most powerful method to analyze functional integrals with (infinite-dimensional) gauge symmetries presently known. It has been invented to fix gauges associated with symmetries that do not close off-shell. Homological perturbation theory is introduced and used to develop the integration theory behind BV and to describe the BV quantization of a Lagrangian system with symmetries. Localization (illustrated in terms of Duistermaat–Heckman localization) as well as anomalous symmetries are discussed in the framework of BV.
Measurement of gas flow velocity: Anemometer with a vibrating hot wire
Authors: Kiełbasa Jan
Published: February 2010

I propose a new method to measure velocity of a gas flow, which utilizes the time derivative of the voltage observed on a vibrating hot-wire sensor. The wire vibrates with an amplitude a and a frequency f, and is kept perpendicular to the gas flow direction in the plane containing the flow velocity vector vg. When the parameters of vibrations are tuned, the number of zeros per vibration period of the hot-wire voltage function changes. I demonstrate that at the point of change, the unknown gas velocity is directly expressed by the parameters of vibrations vg=2πfa. Therefore, the velocity can be measured without any prior calibration of the hot-wire speed-voltage curve and the method can be used for gases of slowly changing temperature or composition.
Statics and dynamics of magnetic vortices and of Nielsen–Olesen (Nambu) strings
Authors: Gustafson S. , Sigal I. M. , Tzaneteas T.
Published: February 2010

We review recent works on statics and dynamics of magnetic vortices in the Ginzburg–Landau model of superconductivity and of Nielsen–Olesen (Nambu) strings in the Abelian–Higgs model of particle physics.
A novel merged beams apparatus to study anion-neutral reactions
Authors: Bruhns H. , Kreckel H. , Miller K. , Lestinsky M. , Seredyuk B. , Mitthumsiri W. , Schmitt B. L. , Schnell M. , Urbain X. , Rappaport M. L. , Havener C. C. , Savin D. W.
Published: February 2010

We have developed a novel laboratory instrument for studying gas phase, anion-neutral chemistry. To the best of our knowledge, this is the first such apparatus which uses fast merged beams to investigate anion-neutral chemical reactions. As proof-of-principle we have detected the associative detachment reaction H−+H→H2+e−. Here we describe the apparatus in detail and discuss related technical and experimental issues.
Polymer photodetector with voltage-adjustable photocurrent spectrum
Authors: Chen En-Chen , Chang Chia-Yu , Shieh Ji-Ting , Tseng Shin-Rong , Meng Hsin-Fei , Hsu Chain-Shu , Horng Sheng-Fu
Published: February 2010

Polymer photodetectors with voltage-adjustable photoresponse from visible to near infrared range are demonstrated. Poly(3-hexylthiophene) and (6,6)-phenyl-C61-butyric acid methyl ester (PCBM) blend is used as the active layer. The photoresponse can be continuously adjusted by the thickness of the active layer as well as the applied voltage bias. The thickness of the active layer is varied from 250 nm to 16.2 μm. The mechanism for the photoresponse adjusted by the thickness can be attributed to the absorption of the photons in the infrared range by thick PCBM layer. The mechanism for the photoresponse adjusted by the applied bias can be attributed to the carrier recombination reduction when the applied bias increases. The adjustable photodetector also has high operating speed up to 10 kHz.
Landau damping
Authors: Mouhot C. , Villani C.
Published: February 2010

In this note we present the main results from the recent work of Mouhot and Villani (“On the Landau damping,” arXiv:0904.2760), which for the first time establish Landau damping in a nonlinear context.
High energy electron fluxes in dc-augmented capacitively coupled plasmas I. Fundamental characteristics
Authors: Wang Mingmei , Kushner Mark J.
Published: February 2010

Power deposition from electrons in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary electrons through sheaths produced by ion, electron, or photon bombardment of electrodes. The sheath accelerated electrons can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy electrons interact with the wafer. To control the energy and increase the flux of the high energy electrons, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy electrons having a narrow angular spread (<1°) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as εmax=−Vdc+Vrf+Vrf0, for a voltage on the dc electrode of Vdc, rf voltage of Vrf, and dc bias on the rf electrode of Vrf0. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.
Cross-helicity dynamo effect in magnetohydrodynamic turbulent channel flow
Authors: Hamba Fujihiro , Tsuchiya Masataka
Published: February 2010

A large eddy simulation of magnetohydrodynamic (MHD) turbulent channel flow is carried out to investigate the dynamo mechanism. It is shown that the streamwise component of the mean magnetic field is generated and sustained due to the effect of the turbulent electromotive force. The Reynolds-averaged turbulence model for MHD flows is assessed; it is suggested that the cross-helicity dynamo effect contributes to the turbulent electromotive force; that is, the electromotive force parallel to the mean vorticity is generated due to the turbulent cross helicity. To verify the importance of the cross-helicity dynamo, the transport equation for the turbulent electromotive force is evaluated; it is confirmed that the term involving the cross helicity and the mean vorticity is the main production term for the turbulent electromotive force. The transport equations for the turbulent kinetic and magnetic energies are also examined to discuss the dynamo mechanism from the viewpoint of the energy transfer.
Vortex formation processes from an oscillating circular cylinder at high Keulegan–Carpenter numbers
Authors: Lam K. M. , Hu J. C. , Liu P.
Published: February 2010

Development of vortex patterns around a circular cylinder oscillating in quiescent water is investigated using time-resolved particle image velocimetry. Experiments are performed at Keulegan–Carpenter (KC) numbers between 8 and 36 with Reynolds number kept constant at 2400. Similar to previous studies, three modes of vortex patterns are identified and denoted as modes I, II, and III. The development of vortices in each mode at successive phases of cylinder oscillation is studied in details. The classification of modes is based on the development mechanism of shear layers around the cylinder, the number of vortices shed in each half cycle, and the characteristics of the vortex street. Modes I, II, and III are characterized by one, two, and three (or more) vortices generated, respectively, in each half cycle. The appropriate vortex formation length is applied to explain the dependence of number of vortices formed in each cylinder cycle on KC. Vortex shedding in mode I occurs only on one side of the line of cylinder motion. This mode, which occurs at KC between 8 and 16, is observed to have two submodes with different orientations of the vortex street to the line of cylinder motion. Mode II occurs at KC between 16 and 24. The vortex street extends to both sides of the line of cylinder motion and lies at about 45° to it. At KC>24, vortices are shed behind the moving cylinder similar to the case of a towed cylinder. The limited-length vortex street in this mode III pattern lies along the line of cylinder motion. Each vortex pattern is associated with a typical secondary flow stream, which affects distinct evolution stages of vortices around the cylinder and hence the unique vortex pattern. The development of vortices is found to involve complex vortex interaction involving migration, stretching, and splitting.
Low-order representations of irregular surface roughness and their impact on a turbulent boundary layer
Authors: Mejia-Alvarez R. , Christensen K. T.
Published: February 2010

The present effort explores the relative impact of various topographical scales present within irregular surface roughness on a turbulent boundary layer under both developing- and developed-flow conditions. Low-order representations of highly irregular surface roughness replicated from a turbine-blade damaged by deposition of foreign materials were generated using singular value decomposition to decompose the complex topography into a set of topographical basis functions of decreasing importance to the original (“full”) surface character. The low-order surface models were then formed by truncating the full set of basis functions at the first 5 and 16 modes (containing approximately 71% and 95% of the full surface content, respectively) so that only the most dominant and large-scale topographical features were included in the models, while the finer-scale surface details are excluded. Physical replications of the full surface and the two low-order models were created using rapid prototyping methods to generate short and long streamwise fetches of roughness, and particle-image velocimetry was used to acquire ensembles of instantaneous velocity fields in the streamwise–wall-normal plane for developing- and developed-flow conditions at moderate Reynolds number. Comparison of both single- and multipoint statistics (mean velocity and Reynolds normal and shear stresses) as well as quadrant analysis of the instantaneous events contributing to the mean Reynolds shear stress indicates that a 16-mode model of the full surface faithfully reproduces the characteristics of flow over the full surface for both developing- and developed-flow conditions. For the latter scenario, both the 5- and 16-mode models reproduce the outer-layer characteristics for flow over the full surface in accordance with Townsend’s wall similarity hypothesis. However, neither low-order surface representation fully reproduces important details of the Reynolds-shear-stress-producing events within the roughness sublayer, particularly the contributions of the most intense ejection and sweep events.
Anodically bonded submicron microfluidic chambers
Authors: Dimov S. , Bennett R. G. , Córcoles A. , Levitin L. V. , Ilic B. , Verbridge S. S. , Saunders J. , Casey A. , Parpia J. M.
Published: February 2010

We demonstrate the use of anodic bonding to fabricate cells with characteristic size as large as 7×10 mm2, with height of ≈640 nm, and without any internal support structure. The cells were fabricated from Hoya SD-2 glass and silicon wafers, each with 3 mm thickness to maintain dimensional stability under internal pressure. Bonding was carried out at 350 °C and 450 V with an electrode structure that excluded the electric field from the open region. We detail fabrication and characterization steps and also discuss the design of the fill line for access to the cavity.
Ionization oscillations in Hall accelerators
Authors: Barral S. , Peradzyński Z.
Published: February 2010

The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.
A compact model for polycrystalline pentacene thin-film transistor
Authors: Li Ling , Debucquoy Maarten , Genoe Jan , Heremans Paul
Published: February 2010

A compact physical model for the operation of polycrystalline pentacene thin-film transistors is presented here, valid in both linear and saturation regimes by including the Gaussian energy distribution of the grain-boundary traps. The effect of the temperature is also taken into account. The proposed model has been verified by comparing the simulated results with the experimental data.
Direct measurement of graphene adhesion on silicon surface by intercalation of nanoparticles
Authors: Zong Zong , Chen Chia-Ling , Dokmeci Mehmet R. , Wan Kai-tak
Published: February 2010

We report a technique to characterize adhesion of monolayered/multilayered graphene sheets on silicon wafer. Nanoparticles trapped at graphene-silicon interface act as point wedges to support axisymmetric blisters. Local adhesion strength is found by measuring the particle height and blister radius using a scanning electron microscope. Adhesion energy of the typical graphene-silicon interface is measured to be 151±28 mJ/m2. The proposed method and our measurements provide insights in fabrication and reliability of microelectromechanical/nanoelectromechanical systems.
Different origins of the yellow luminescence in as-grown high-resistance GaN and unintentional-doped GaN films
Authors: Xu F. J. , Shen B. , Lu L. , Miao Z. L. , Song J. , Yang Z. J. , Zhang G. Y. , Hao X. P. , Wang B. Y. , Shen X. Q. , Okumura H.
Published: February 2010

The yellow luminescence (YL) in as-grown high-resistance (HR) and unintentional-doped (UID) GaN films grown by metal organic chemical vapor deposition has been investigated by means of photoluminescence and monoenergetic positron annihilation spectroscopy. It is found there is stronger YL in UID-GaN with higher concentration of gallium vacancy (VGa), suggesting that VGa-involved defects are the origin responsible for the YL in UID-GaN. Contrastly, there is much stronger YL in HR-GaN that is nearly free from VGa, suggesting that there is another origin for the YL in HR-GaN, which is thought as the carbon-involved defects. Furthermore, it is found that the HR-GaN film with shorter positron diffusion length Ld exhibits stronger YL. It is suggested that the increased wave function overlap of electrons and holes induced by the extremely strong space localization effect of holes deduced from the short Ld is the vital factor to enhance the YL efficiency in HR-GaN.
Analysis of mass transport in an atmospheric pressure remote plasma-enhanced chemical vapor deposition process
Authors: Cardoso R. P. , Belmonte T. , Henrion G. , Gries T. , Tixhon E.
Published: February 2010

In remote microwave plasma enhanced chemical vapor deposition processes operated at atmospheric pressure, high deposition rates are associated with the localization of precursors on the treated surface. We show that mass transport can be advantageously ensured by convection for the heavier precursor, the lighter being driven by turbulent diffusion toward the surface. Transport by laminar diffusion is negligible. The use of high flow rates is mandatory to have a good mixing of species. The use of an injection nozzle with micrometer-sized hole enables us to define accurately the reaction area between the reactive species. The localization of the flow leads to high deposition rates by confining the reactive species over a small area, the deposition yield being therefore very high. Increasing the temperature modifies nonlinearly the deposition rates and the coating properties.
Probing porosity at buried interfaces using soft x-ray resonant reflectivity
Authors: Nayak Maheswar , Lodha G. S. , Prasad T. T. , Nageswararao P. , Sinha A. K.
Published: February 2010

The optical constants of electron beam evaporated boron carbide are measured near boron K-absorption edge. Near the edge, the dispersion part of refractive index shows a sign reversal. Simulated reflectivity profiles near the absorption edge of boron are used to show the utility of soft x-ray resonant reflectivity as a sensitive tool for probing selected buried interfaces. This is due to high and tunable scattering contrast. The simulated resonant reflectivity profiles are sensitive to porosity and position of the porous layer containing the resonating atom. This is experimentally demonstrated through soft x-ray resonant reflectivity measurements of B4C-on-Fe bilayer structure.
Controllable far-infrared electromagnetic radiation from plasmas applied by dc or ac bias electric fields
Authors: Wang Wei-Min , Sheng Zheng-Ming , Dong X.-G. , Du H.-W. , Li Y.-T. , Zhang J.
Published: February 2010

It is shown theoretically and numerically that a dc/ac bias field applied over tenuous plasma can be converted efficiently into electromagnetic (EM) waves at the plasma frequency ωp, with the amplitude and polarization determined by the bias. The initial phase of the EM waves can be controlled by the triggering time of the bias and therefore circularly/elliptically polarized EM waves can be obtained by applying two bias fields perpendicular to each other. When the bias frequency is near ωp, the resonance appears and the EM waves are generated with the intensity enhanced considerably as compared with the dc-bias case. This approach provides a potential way to produce tunable far-infrared EM waves such as terahertz waves. Limits of this approach by available parameters of plasmas and bias are also discussed.
Controlling blue-violet electroluminescence of Ge-rich Er-doped SiO2 layers by millisecond annealing using flash lamps
Authors: Kanjilal A. , Rebohle L. , Voelskow M. , Helm M. , Skorupa W.
Published: February 2010

Systematic evolution of the 400 nm electroluminescence (EL) with increasing flash lamp annealing (FLA) temperature from 800 to 1100 °C in an Er-doped Ge-rich metal-oxide semiconductor structure is presented. No significant change in the 1535 nm Er EL is observed with increasing FLA temperature. Enhancement of the 400 nm EL decay time with rising FLA temperature is found to be associated with recrystallization of the damaged Ge clusters in the absence of Ge outdiffusion. The 400 nm EL quenching with continuous charge injection process is also discussed within the device operation time.
Improvement of the computation of Fourier integrals using the complex plane: Application to acoustic fields
Authors: Gatignol Philippe , Potel Catherine , Bedrici Nacera
Published: February 2010

This letter aims at showing the interest in using an integration path in the complex plane in order to calculate Fourier integrals, instead of using a real path, as needed for the fast Fourier transform algorithm as follows: fastness, accuracy, avoiding of singularities, or even aliasing phenomenon. The method is applied to the calculation of the acoustic field emitted by a transducer or a loudspeaker; for the same number of sampling points, the calculation of the spatial Fourier integrals is more accurate using a complex path than using a real path.
Eddy current induced magnetoelectricity in a piezoelectric unimorph bender
Authors: Guiffard B. , Guyomar D. , Garbuio L. , Belouadah R. , Zhang J. , Cottinet P. J.
Published: February 2010

Here, we report on a magnetoelectric (ME) coupling in a simple piezoelectric unimorph bender induced by the eddy currents within the silver electrodes of the piezoelectric ceramic Pb(Zr,Ti)O3 (PZT) subjected to ac magnetic flux. Eddy currents and the applied magnetic field generate Lorentz forces in the metal electrode acting on the PZT. A magnetically induced piezoelectric current linear versus dc magnetic biases is obtained at the ceramic electrodes. ME coupling is finally achieved with only one piezoelectric bender: (i) no magnetic phase is required, (ii) no ac current supply is necessary, eddy currents in electrodes are sufficient to generate Lorentz forces.
Tunable optical gratings based on buckled nanoscale thin films on transparent elastomeric substrates
Authors: Yu Cunjiang , O’Brien Kevin , Zhang Yong-Hang , Yu Hongbin , Jiang Hanqing
Published: February 2010

This letter reports a tunable optical grating based on buckled thin film with periodic sinusoidal patterns on a transparent elastomeric substrate. Submicron scale sinusoidal gratings have been fabricated with nanometer thick Gold/Palladium film coated on 30% pretensioned polydimethylsiloxane substrates. Due to competition between the soft elastomeric substrates and relatively stiff films, periodic wavy profiles are created upon releasing the pretension. The buckling profiles can be easily tuned by mechanically stretching or compressing. Optical transmittance diffraction testing has been conducted, and 85 nm peak wavelength shifts of the first order diffraction have been achieved by stretching the grating up to 30% of its original length.
Brownian particles in an external field: Asymptotic distribution functions and mean square displacement
Authors: Ferrari Leonardo
Published: February 2010

A simple procedure is proposed by which the long-time form of the distribution of large (or heavy) ions in a fluid, in a time-varying electric field, is obtained as asymptotic solution of the Fokker–Planck (or Klein–Kramers) equation. In this way, it is shown that, when the initial ion distribution is the product of a delta function in position space times a shifted Maxwellian in velocity space, the asymptotic ion distribution, at sufficiently large times, coincides with the asymptotic form of the corresponding fundamental solution of the Fokker–Planck equation. Moreover, it is shown that a simplified (even if incorrect) form of the ion distribution can successfully be used to obtain correct values of a large class of average quantities. In this connection, the proper, asymptotic formula for the ion mean square displacement in time-varying electric fields is widely discussed and compared to the corresponding result following from the appropriate diffusion equation.
Form birefringence metal and its plasmonic anisotropy
Authors: Feng Liang , Liu Zhaowei , Lomakin Vitaliy , Fainman Yeshaiahu
Published: February 2010

We constructed a uniaxial “form birefringence” metal that exhibits different dielectric polarizabilities along different optical axes as well as its supported optical anisotropy of surface plasmon polariton waves. The generated plasmonic index ellipsoid that exists in reciprocal space has been directly mapped and characterized in our experiment. The discovery of this anisotropic plasmonic metamaterial further completes analogy between artificial plasmonic metamaterials and conventional optical crystals, thereby providing opportunities to miniaturize myriad existing optical devices on-a-chip with plasmonics into nanometers scale.
High figure-of-merit ultrathin metal transparent electrodes incorporating a conductive grid
Authors: Ghosh D. S. , Chen T. L. , Pruneri V.
Published: February 2010

It is known that ultrathin (<10 nm) metal films (UTMFs) can achieve high level of optical transparency at the expense of the electrical sheet resistance. In this letter, we propose a design, the incorporation of an ad hoc conductive grid, which can significantly reduce the sheet resistance of UTMF based transparent electrodes, leaving practically unchanged their transparency. The calculated highest figure-of-merit corresponds to a filling factor and a grid spacing-to-linewidth ratio of 0.025 and 39, respectively. To demonstrate the capability of the proposed method the sheet resistance of a continuous 2 nm Ni film (>950 Ω/◻) is reduced to ∼6.5 Ω/◻ when a 100 nm thick Cu grid is deposited on it. The transparency is instead maintained at values exceeding 75%. These results, which can be further improved by making thicker grids, already demonstrate the potential in applications, such as photovoltaic cells, optical detectors and displays.
Electrical characteristics of an organic bistable device using an Al/Alq3/nanostructured MoO3/Alq3/p+-Si structure
Authors: Chang Tzu-Yueh , Cheng You-Wei , Lee Po-Tsung
Published: February 2010

The electrical properties of a device with an Al/Alq3/nanostructured MoO3/Alq3/p+-Si structure were investigated for organic resistance switching memories. The conductance of the device can be electrically switched to either high conductance or low conductance. The bistable switching of the device is attributed to the MoO3 nanoclusterlike layer interposed between the Alq3 thin films. When the device was switched to high conductance, a space-charge field dominated carrier transportation of the device. The space-charge field was resulted from charges trapped in the MoO3 nanoclusterlike layer. Both retention measurement and write-read-erase-read cycles of the device are also provided.
Fokker–Planck analysis of separation dependent potentials and diffusion coefficients in simulated microscopy experiments
Authors: Beltran-Villegas Daniel J. , Sehgal Ray M. , Maroudas Dimitrios , Ford David M. , Bevan Michael A.
Published: February 2010

Total internal reflection microscopy (TIRM) and video microscopy (VM) are methods for nonintrusively measuring weak colloidal interactions important to many existing and emerging applications. Existing analyses of TIRM measured single particle trajectories can be used to extract particle-surface potentials and average particle diffusion coefficients. Here we develop a Fokker–Planck (FP) formalism to simultaneously extract both particle-surface interaction potentials and position dependent diffusion coefficients. The FP analysis offers several advantages including capabilities to measure separation dependent hydrodynamic interactions and nonequilibrium states that are not possible with existing analyses. The FP analysis is implemented to analyze Brownian dynamic simulations of single particle TIRM and VM experiments in several configurations. Relative effects of spatial and temporal sampling on the correct interpretation of both conservative and dissipative forces are explored and show a broad range of applicability for accessible experimental systems. Our results demonstrate the ability to extract both static and dynamic information from microscopy measurements of isolated particles near surfaces, which provides a foundation for further investigation of particle ensembles and nonequilibrium systems.
Universal and reconfigurable logic gates in a compact three-terminal resonant tunneling diode
Authors: Worschech L. , Hartmann F. , Kim T. Y. , Höfling S. , Kamp M. , Forchel A. , Ahopelto J. , Neri I. , Dari A. , Gammaitoni L.
Published: February 2010

Submicron-sized mesas of resonant tunneling diodes (RTDs) with split drain contacts have been realized and the current-voltage characteristics have been studied in the bistable regime at room temperature. Dynamically biased, the RTDs show noise-triggered firing of spikelike signals and can act as reconfigurable universal logic gates for small voltage changes of a few millivolt at the input branches. These observations are interpreted in terms of a stochastic nonlinear processes. The logic gate operation shows gain for the fired-signal bursts with transconductance slopes exceeding the thermal limit. The RTD junction can be easily integrated to arrays of multiple inputs and have thus the potential to mimic neurons in nanoelectronic circuits.
Communications: Comparison of activation barriers for the Johari–Goldstein and alpha relaxations and its implications
Authors: Goldstein Martin
Published: February 2010

The range of activation barrier heights for the Johari–Goldstein (JG) relaxation in glasses is shown to overlap the range for the main (alpha) relaxation, but to be on the average somewhat lower. This suggests the JG relaxation, like the alpha, involve transitions between megabasins in the energy landscape, and that the original conjecture by Johari and this author that the JG relaxation is an intrabasin one cannot be correct. A further possibility is that there is a closer connection of the JG relaxation to the phenomenon of dynamic heterogeneity in supercooled liquids than so far assumed.
Retaining HIV-Infected Patients in Care: Where Are We? Where Do We Go from Here?
Authors: Horstmann Elizabeth , Brown Jillian , Islam Fareesa , Buck Johanna , Agins Bruce D.
Published: February 2010

Retaining human immunodeficiency virus (HIV)–infected patients in medical care at regular intervals has been shown to be linked to positive health outcomes. This article examines the available literature and research on retention and engagement in care of HIV-infected patients. We identify the extent of the problem of keeping patients engaged in care, as well as analyze which groups of patients are likely to be lost to follow-up. A review of different ways to measure patient retention is considered, as well as some preliminary data that suggest successful ways to re-engage patients in care. The need to ensure that HIV-infected patients are retained in care is a pressing public health issue and one that affects multiple populations. Further research and exchange of information are needed to keep patients in continuous care and to ensure that all patients are provided with regular, high-quality care that achieves both desired patient and population health outcomes.
Association between Severe Pandemic 2009 Influenza A (H1N1) Virus Infection and Immunoglobulin G2 Subclass Deficiency
Authors: Gordon C.L. , Johnson P.D.R. , Permezel M. , Holmes N.E. , Gutteridge G. , McDonald C.F. , Eisen D.P. , Stewardson A.J. , Edington J. , Charles P.G.P. , Crinis N. , Black M.J. , Torresi J. , Grayson M.L.
Published: February 2010

Severe H1N1 infection appears to be associated with immunoglobulin G2 subclass deficiency in both nonpregnant and pregnant patients. Healthy pregnant women were mildly deficient in immunoglobulin G2, but pregnant women with severe H1N1 infection had lower levels. Immunoglobulin G2 deficiency persisted after recovery in the majority (73%) of cases.

Background . Severe pandemic 2009 influenza A virus (H1N1) infection is associated with risk factors that include pregnancy, obesity, and immunosuppression. After identification of immunoglobulin G2 (IgG2) deficiency in 1 severe case, we assessed IgG subclass levels in a cohort of patients with H1N1 infection.

Methods . Patient features, including levels of serum IgG and IgG subclasses, were assessed in patients with acute severe H1N1 infection (defined as infection requiring respiratory support in an intensive care unit), patients with moderate H1N1 infection (defined as inpatients not hospitalized in an intensive care unit), and a random sample of healthy pregnant women.

Results . Among the 39 patients with H1N1 infection (19 with severe infection, 7 of whom were pregnant; 20 with moderate infection, 2 of whom were pregnant), hypoabuminemia (P<.001), anemia (P<.001), and low levels of total IgG (P=.01), IgG1 (P=.022), and IgG2 (15 of 19 vs 5 of 20; P=.001; mean value ± standard deviation [SD], 1.8±1.7 g/L vs 3.4±1.4 g/L; P=.003) were all statistically significantly associated with severe H1N1 infection, but only hypoalbuminemia (P=.02) and low mean IgG2 levels (P=.043) remained significant after multivariate analysis. Follow-up of 15 (79%) surviving IgG2-deficient patients at a mean (±SD) of 90±23 days (R, 38–126) after the initial acute specimen was obtained found that hypoalbuminemia had resolved in most cases, but 11 (73%) of 15 patients remained IgG2 deficient. Among 17 healthy pregnant control subjects, mildly low IgG1 and/or IgG2 levels were noted in 10, but pregnant patients with H1N1 infection had significantly lower levels of IgG2 (P=.001).

Conclusions . Severe H1N1 infection is associated with IgG2 deficiency, which appears to persist in a majority of patients. Pregnancy-related reductions in IgG2 level may explain the increased severity of H1N1 infection in some but not all pregnant patients. The role of IgG2 deficiency in the pathogenesis of H1N1 infection requires further investigation, because it may have therapeutic implications.