bluuebunny/crossref_metadata_2025 huggingface dataset:
Der Einfluss von Ergebnis- und Selbstwirksamkeitserwartungen auf die Ergebnisse einer Rehabilitation nach Hüftgelenkersatz
Authors: Dohnke Birte , Müller-Fahrnow Werner , Knäuper Bärbel
Published: February 2006

Zusammenfassung. In einer prospektiven Beobachtungsstudie wurde an 1065 Patienten der Einfluss von Reha-Motivationen (d.h. Ergebniserwartungen und Selbstwirksamkeitserwartungen) auf die Ergebnisse einer Rehabilitation nach Hüftgelenkersatz untersucht. Die Ergebnisse der Längsschnittanalysen bestätigten, dass Patienten umso bessere Reha-Ergebnisse (d.h. geringere Schmerzen, weniger eingeschränkte Aktivitäten des täglichen Lebens) am Reha-Ende hatten, je positiver ihre Ergebniserwartungen und je höher ihre Selbstwirksamkeitserwartungen zu Reha-Beginn waren. Hohe Selbstwirksamkeitserwartungen verstärkten die positive Wirkung der Ergebniserwartungen. In Querschnittsanalysen wurde der Einfluss des körperlichen Gesundheitszustands, des emotionalen Wohlbefindens und behandlungsbezogener Erfahrungen auf beide Erwartungstypen zu Reha-Beginn untersucht. Beide Erwartungstypen waren umso höher ausgeprägt, je besser der körperliche Gesundheitszustand war. Zudem waren Selbstwirksamkeitserwartungen umso höher, je geringer die Depressivitätswerte, und Ergebniserwartungen umso positiver, je höher die Selbstwirksamkeitserwartungen waren. Positive behandlungsbezogene Erfahrungen, in Form einer guten präoperativen Aufklärung, waren mit höherer Selbstwirksamkeit jedoch mit weniger positiven Ergebniserwartungen assoziiert. Ergebnis- und Selbstwirksamkeitserwartungen sollten künftig stärker in der Reha-Forschung sowie Reha-Praxis beachtet werden.
Inverse modeling estimates of the global nitrous oxide surface flux from 1998–2001
Authors: Hirsch A. I. , Michalak A. M. , Bruhwiler L. M. , Peters W. , Dlugokencky E. J. , Tans P. P.
Published: February 2006

Measurements of nitrous oxide in air samples from 48 sites in the Cooperative Global Air Sampling Network made by NOAA/ESRL GMD CCGG (the Carbon Cycle Greenhouse Gases group in the Global Monitoring Division at the NOAA Earth System Research Laboratory in Boulder, Colorado) and the three‐dimensional chemical transport model TM3 were used to infer global nitrous oxide fluxes and their uncertainties from 1998–2001. Results are presented for four semihemispherical regions (90°S–30°S, 30°S to equator, equator to 30°N, 30°N–90°N) and six broad “super regions” (Southern Land, Southern Oceans, Tropical Land, Tropical Oceans, Northern Land, and Northern Oceans). We found that compared to our a priori estimate (from the International Geosphere‐Biosphere Programme's Global Emissions Inventory Activity), the a posteriori flux was much lower from 90°S–30°S and substantially higher from equator to 30°N. Consistent with these results, the a posteriori flux from the Southern Oceans region was lower than the a priori estimate, while Tropical Land and Tropical Ocean estimates were higher. The ratio of Northern Hemisphere to Southern Hemisphere fluxes was found to range from 1.9 to 5.2 (depending on the model setup), which is higher than the a priori ratio (1.5) and at the high end of previous estimates. Globally, ocean emissions contributed 26–36% of the total flux (again depending on the model setup), consistent with the a priori estimate (29%), though somewhat higher than some other previous estimates.
Thermodynamic solutions for equilibrium beach profiles
Authors: Jenkins Scott A. , Inman Douglas L.
Published: February 2006

Solutions are developed for beach profiles using equilibrium principles of thermodynamics applied to simple representations of the nearshore fluid dynamics. Equilibrium beaches are posed as isothermal shorezone systems of constant volume that dissipate external work by incident waves into heat given up to the surroundings. By the maximum entropy production formulation of the second law of thermodynamics (the law of entropy increase), the shorezone system achieves equilibrium with profile shapes that maximize the rate of dissipative work performed by wave‐induced shear stresses. Dissipative work is assigned to two different shear stress mechanisms prevailing in separate regions of the shorezone system, an outer solution referred to as the shorerise and a bar‐berm inner solution. The equilibrium shorerise solution extends from closure depth (zero profile change) to the breakpoint, and maximizes dissipation due to the rate of working by bottom friction. In contrast, the equilibrium bar‐berm solution between the breakpoint and the berm crest maximizes dissipation due to work by internal stresses of a turbulent surf zone. Both shorerise and bar‐berm equilibria were found to have an exact general solution belonging to the class of elliptic cycloids. The elliptic cycloid allows all significant features of the equilibrium profile to be characterized by the eccentricity and the size of the ellipse axes. These basic ellipse parameters are evaluated by process‐based algorithms and empirically validated parameters for which an extensive literature already exists. The elliptic cycloid solutions displayed wave height, period and grain size dependence and demonstrate generally good predictive skill in point‐by‐point comparisons with measured profiles.
Duration‐ and fetch‐limited growth functions of wind‐generated waves parameterized with three different scaling wind velocities
Authors: Hwang Paul A.
Published: February 2006

Under steady wind forcing, wave development follows the duration‐ and fetch‐limited growth laws. These growth functions are used extensively to obtain the sea state information when only limited observations of the environmental variables are available. Validation and verification of wave models also employ numerical experiments of duration‐ and fetch‐limited wave growth as benchmark tests. The reference wind speed reported in most of the wave‐growth data is the equivalent neutral wind speed at 10 m elevation, U10. It is generally believed that a more suitable scaling wind speed is either the wind friction velocity, u*, or the wind speed at an elevation proportional to the wavelength of the ocean surface fluctuation, Uλ/2. The connection among the growth functions using different velocity scales is the drag coefficient of the ocean surface. In this paper, the similarity relation of the drag coefficient based on wavelength scaling is applied to the conversion of the wave growth functions from U10 to Uλ/2 and u* scaling. The results are in good agreement with field measurements that include direct u* measurements. Comparisons with numerical model output are also described.
Role of convection in global‐scale transport in the troposphere
Authors: Erukhimova Tatiana , Bowman Kenneth P.
Published: February 2006

The role of convection in global‐scale transport in the troposphere is studied by using climatological Green's functions of the mass conservation equation for a conserved, passive tracer. The Green's functions are calculated from long‐term atmospheric trajectory calculations based on three‐dimensional winds from a 19‐year simulation by Version 3 of the NCAR Community Climate Model (CCM3). Two trajectory calculations are compared: one that includes the effects of the model's parameterized convection and one that neglects the convective transport. The global transport properties of the two cases are qualitatively similar. The global troposphere can be divided into three parts: the tropics, and the Northern and Southern Hemisphere extratropics. Transport within each region is rapid, while the exchange of air between the regions is comparatively slow. Semipermeable barriers to transport exist in the subtropics in both cases. Convection slightly suppresses transport across the subtropical barriers. Convective transport enhances the vertical dispersion of air parcels, particularly in the rising branch of the Hadley circulation. Localized differences between the two runs can reach 50–80%. The differences are largest in the upper troposphere. Interannual transport variations related to the El Niño–Southern Oscillation (ENSO) phase can be detected in both cases, with the vertical transport being enhanced in the presence of convection.
Temperature trends at the surface and in the troposphere
Authors: Vinnikov Konstantin Y. , Grody Norman C. , Robock Alan , Stouffer Ronald J. , Jones Philip D. , Goldberg Mitchell D.
Published: February 2006

This paper incorporates the latest improvements in intersatellite calibration, along with a new statistical technique, to determine the diurnal and seasonal cycles and climatic trends of 1978–2004 tropospheric temperature using Microwave Sounding Unit measurements. We also compare the latitudinal distribution of temperature trends from the surface and troposphere with each other and with model simulations for the past 26 years. The observations at the surface and in the troposphere are consistent with climate model simulations. At middle and high latitudes in the Northern Hemisphere, the zonally averaged temperature at the surface increased faster than in the troposphere while at low latitudes of both hemispheres the temperature increased more slowly at the surface than in the troposphere. The resulting global averaged tropospheric trend is +0.20 K/10 yr, with a standard error of 0.05 K/10 yr, which compares very well with the trend obtained from surface reports.
Inhibition of apoptosis by survivin improves transplantation of pancreatic islets for treatment of diabetes in mice
Authors: Dohi Takehiko , Salz Whitney , Costa Marco , Ariyan Charlotte , Basadonna Giacomo P , Altieri Dario C
Published: February 2006

Survivin is a cancer gene implicated in inhibition of apoptosis and regulation of mitosis, but its function in normal cells has remained elusive. Here, we show that transgenic mice expressing survivin in pancreatic islet β‐cells show no changes in cell proliferation, as determined by islet size or islet number. Transplantation of survivin transgenic islets in diabetic recipient mice affords long‐term engraftment and stable correction of hyperglycaemia. This involves intrinsic inhibition of β‐cell apoptosis, in vivo, and global transcriptional changes in pancreatic islets with upregulation of stress response genes, antagonists of cytokine signalling and promoters of angiogenesis. These broad cytoprotective functions of survivin in vivo might be beneficial for gene therapy of diabetes.
Type A and B RNase P RNAs are interchangeable in vivo despite substantial biophysical differences
Authors: Wegscheid Barbara , Condon Ciarán , Hartmann Roland K
Published: February 2006

We show that structural type A and B bacterial ribonuclease P (RNase P) RNAs can fully replace each other in vivo despite the many reported differences in their biogenesis, biochemical/biophysical properties and enzyme function in vitro. Our findings suggest that many of the reported idiosyncrasies of type A and B enzymes either do not reflect the in vivo situation or are not crucial for RNase P function in vivo, at least under standard growth conditions. The discrimination of mature tRNA by RNase P, so far thought to prevent product inhibition of the enzyme in the presence of a large cellular excess of mature tRNA relative to the precursor form, is apparently not crucial for RNase P function in vivo.
Vibrational dynamics of N–H, C–D, and CO modes in formamide
Authors: Ha Jeong-Hyon , Kim Yung Sam , Hochstrasser Robin M.
Published: February 2006

By means of heterodyned two-dimensional IR photon echo experiments on liquid formamide and isotopomers the vibrational frequency dynamics of the N–H stretch mode, the C–D mode, and the CO mode were obtained. In each case the vibrational frequency correlation function is fitted to three exponentials representing ultrafast (few femtoseconds), intermediate (hundreds of femtoseconds), and slow (many picoseconds) correlation times. In the case of N–H there is a significant underdamped contribution to the correlation decay that was not seen in previous experiments and is attributed to hydrogen-bond librational modes. This underdamped motion is not seen in the C–D or CO correlation functions. The motions probed by the C–D bond are generally faster than those seen by N–H and CO, indicating that the environment of C–D interchanges more rapidly, consistent with a weaker C–D⋯OC bond. The correlation decays of N–H and CO are similar, consistent with both being involved in strong H bonding.
Molecular-dynamics study of photodissociation of water in crystalline and amorphous ices
Authors: Andersson Stefan , Al-Halabi Ayman , Kroes Geert-Jan , van Dishoeck Ewine F.
Published: February 2006

We present the results of classical dynamics calculations performed to study the photodissociation of water in crystalline and amorphous ice surfaces at a surface temperature of 10 K. A modified form of a recently developed potential model for the photodissociation of a water molecule in ice [S. Andersson et al., Chem. Phys. Lett. 408, 415 (2005)] is used. Dissociation in the top six monolayers is considered. Desorption of H2O has a low probability (less than 0.5% yield per absorbed photon) for both types of ice. The final outcome strongly depends on the original position of the photodissociated molecule. For molecules in the first bilayer of crystalline ice and the corresponding layers in amorphous ice, desorption of H atoms dominates. In the second bilayer H atom desorption, trapping of the H and OH fragments in the ice, and recombination of H and OH are of roughly equal importance. Deeper into the ice H atom desorption becomes less important and trapping and recombination dominate. Motion of the photofragments is somewhat more restricted in amorphous ice. The distribution of distances traveled by H atoms in the ice peaks at 6–7 Å with a tail going to about 60 Å for both types of ice. The mobility of OH radicals is low within the ice with most probable distances traveled of 2 and 1 Å for crystalline and amorphous ices, respectively. OH is, however, quite mobile on top of the surface, where it has been found to travel more than 80 Å. Simulated absorption spectra of crystalline ice, amorphous ice, and liquid water are found to be in very good agreement with the experiments. The outcomes of photodissociation in crystalline and amorphous ices are overall similar, but with some intriguing differences in detail. The probability of H atoms desorbing is 40% higher from amorphous than from crystalline ice and the kinetic-energy distribution of the H atoms is on average 30% hotter for amorphous ice. In contrast, the probability of desorption of OH radicals from crystalline ice is much higher than that from amorphous ice.
A realistic potential model for N–H vector diffusion in proteins
Authors: Ding Shangwu
Published: February 2006

A realistic model for the potential energy for the diffusion of N–H vectors in a protein is proposed, massively modifying the simplistic models currently used in the literature. In particular, a quantitative and analytical connection between the order parameter of the N–H vector diffusion in a protein and the number of potential minima is established, offering a significant insight into the longstanding question of how protein dynamics is affected by the potential-energy landscape. The largest number of potential minima in a protein is estimated to be no more than around 25. In addition, the conformational entropies derived from classical statistical mechanics and quantum statistical mechanics are proved to be identical. Based on the presented theoretical formula, the number of potential minima for each residue of five representative proteins is evaluated and shows a good correlation between local structural flexibility and the number of potential minima.
Gallium desorption kinetics on (0001) GaN surface during the growth of GaN by molecular-beam epitaxy
Authors: He L. , Moon Y. T. , Xie J. , Muñoz M. , Johnstone D. , Morkoç H.
Published: February 2006

Gallium (Ga) surface desorption behavior was investigated using reflection high-energy electron diffraction during the GaN growth. It was found that the desorption of Ga atoms from the (0001) GaN surfaces under different III-V ratio dependents on the coverage of adsorbed atoms. Doing so led to desorption energies of 2.76 eV for Ga droplets, 1.24–1.89 eV for Ga under Ga-rich growth conditions, and 0.82 eV – 0.94 eV for Ga under stoichiometric growth conditions. Moreover, the variation of the GaN surface morphology under different III-V ratios on porous templates supports the conclusion that Ga desorption energy depends on the coverage, and the III/V ratio dominates the growth mode.
Non-Born-Oppenheimer path in anti-Hermitian dynamics for nonadiabatic transitions
Authors: Takatsuka Kazuo
Published: February 2006

A serious difficulty in the semiclassical Ehrenfest theory for nonadiabatic transitions is that a path passing across the avoided crossing is forced to run on a potential averaged over comprising adiabatic potential surfaces that commit the avoided crossing. Therefore once a path passes through the crossing region, it immediately becomes incompatible with the standard view of “classical trajectory” running on an adiabatic surface. This casts a fundamntal question to the theoretical structure of chemical dynamics. In this paper, we propose a non-Born-Oppenheimer path that is generated by an anti-Hermitian Hamiltonian, whose complex-valued eigenenergies can cross in their real parts and avoid crossing in the imaginary parts in the vicinity of the nonadiabatic transition region. We discuss the properties of this non-Born-Oppenheimer path and thereby show its compatibility with the Born-Oppenheimer classical trajectories. This theory not only allows the geometrical branching of the paths but gives the nonadiabatic transition amplitudes and quantum phases along the generated paths.
Model of saturated lithium ammonia as a single-component liquid metal
Authors: Pinsook Udomsilp , Hannongbua Supot
Published: February 2006

We use the single-component picture and the nearly-free-electron theory for describing collective excitations in the saturated Li-ammonia solution. The physical justification is discussed, and all predictions are compared with current experimental findings. The plasmon dispersion and the long-wavelength dielectric function of the solution can be explained within the homogeneous-electron-gas theory. The parameters rs=7.4a0 and ϵ∞=1.44 give a good description compared with inelastic x-ray scattering and optical data. The phonon spectrum of the solution is also examined. Within the scope of the empty core model with Rc=3.76a0, the phonon dispersion at low q is reproduced. The ratio B∕Bfree=1.34 is compared with 1.63 obtained from experiments.
Acceleration of Markov chain Monte Carlo simulations through sequential updating
Authors: Ren Ruichao , Orkoulas G.
Published: February 2006

Strict detailed balance is not necessary for Markov chain Monte Carlo simulations to converge to the correct equilibrium distribution. In this work, we propose a new algorithm which only satisfies the weaker balance condition, and it is shown analytically to have better mobility over the phase space than the Metropolis algorithm satisfying strict detailed balance. The new algorithm employs sequential updating and yields better sampling statistics than the Metropolis algorithm with random updating. We illustrate the efficiency of the new algorithm on the two-dimensional Ising model. The algorithm is shown to identify the correct equilibrium distribution and to converge faster than the Metropolis algorithm with strict detailed balance. The main advantages of the new algorithm are its simplicity and the feasibility of parallel implementation through domain decomposition.
Low erosion behavior of polystyrene films under erbium ion implantation
Authors: Bhattacharya M. , Sanyal M. K. , Chini T. K. , Chakraborty P.
Published: February 2006

Erbium ion implantation in polystyrene (PS) thin films has been performed with 40 and 60 keV ions to a dose range between 1×1014 and 1×1016ions∕cm2. The x-ray reflectivity technique was applied to determine the ion-induced eroded layer thickness and interestingly, the erosion rate is found to decrease with increasing ion doses exhibiting simple power law behavior of the form ∼(dose)−b. We propose the formation of a carbonaceous network at the top surface, which seems to prevent further erosion of the polymer with increasing the duration of implantation time. These findings may open up a possibility of loading a large amount of erbium in a polymer matrix by the implantation technique to make it suitable for various optoelectronic applications.
Orientational correlations in liquid acetone and dimethyl sulfoxide: A comparative study
Authors: McLain Sylvia E. , Soper Alan K. , Luzar Alenka
Published: February 2006

The structure of acetone and dimethyl sulfoxide in the liquid state is investigated using a combination of neutron diffraction measurements and empirical potential structure refinement (EPSR) modeling. By extracting the orientational correlations from the EPSR model, the alignment of dipoles in both fluids is identified. At short distances the dipoles or neighboring molecules are found to be in antiparallel configurations, but further out the molecules tend to be aligned predominately as head to tail in the manner of dipolar ordering. The distribution of these orientations in space around a central molecule is strongly influenced by the underlying symmetry of the central molecule. In both liquids there is evidence for weak methyl hydrogen to oxygen intermolecular contacts, though these probably do not constitute hydrogen bonds as such.
Extended Born-Oppenheimer equation for a three-state system
Authors: Sarkar Biplab , Adhikari Satrajit
Published: February 2006

We present explicit forms of nonadiabatic coupling (NAC) elements of nuclear Schrödinger equation (SE) for a coupled three-state electronic manifold in terms of mixing angles of real electronic basis functions. If the adiabatic-diabatic transformation (ADT) angles are the mixing angles of electronic bases, ADT matrix transforms away the NAC terms and brings diabatic form of SE. ADT and NAC matrices are shown to satisfy a curl condition with nonzero divergence. We have demonstrated that the formulation of extended Born-Oppenheimer (EBO) equation from any three-state BO system is possible only when there exists a coordinate-independent ratio of the gradients for each pair of mixing angles. On the contrary, since such relations among the mixing angles lead to zero curl, we explore its validity analytically around conical intersection(s) and support numerically considering two nuclear-coordinate-dependent three surface BO models. Numerical calculations are performed by using newly derived diabatic and EBO equations and expected transition probabilities are obtained.
Near-infrared electroluminescence based on perylenediimide-doped tris(8-quinolinolato) aluminum
Authors: Del Caño Teodosio , Hashimoto Keisuke , Kageyama Hiroshi , De Saja José Antonio , Aroca Ricardo , Ohmori Yutaka , Shirota Yasuhiko
Published: February 2006

For the purpose of exploring near-infrared emission, the photoluminescence (PL) and electro- luminescence (EL) of N,N′-bis(neopentyl)-3,4:9,10-perylenebis(dicarboximide) (BNPTCD): tris(8-quinolinolato)aluminum (Alq3) mixed films were investigated. It was found that BNPTCD:Alq3 mixed films exhibit PL in the near-infrared wavelength region and that organic light-emitting diodes using Alq3 highly doped with BNPTCD as an emitting layer exhibit near-infrared EL with a peak at 805 nm originating from BNPTCD aggregates.
Single [101]-oriented growth of La0.9Sr0.1MnO3 films on vicinal SrTiO3(001) substrates
Authors: Zhuo M. J. , Zhu Y. L. , Ma X. L. , Lu H. B.
Published: February 2006

Thin films of orthorhombic La0.9Sr0.1MnO3, have been grown by computer-controlled laser molecular-beam epitaxy on SrTiO3(001) substrate and vicinal SrTiO3(001) substrates. Electron diffractions and high-resolution imaging reveal that the as-received thin films with thickness of 300 nm are epitaxially grown on the substrates. The microstructures in the film grown on SrTiO3(001) substrate are clarified in terms of the oriented microdomains, while the films on vicinal SrTiO3(001) substrates are predominated by a single [101]-oriented growth, which provides a useful routine for a design of preferred physical properties. Based on the minimization of surface energy, the mechanism of such a single domain formation is proposed.
Direct observation of pinning centers in ferroelectrics
Authors: Agronin Alex , Rosenwaks Yossi , Rosenman Gil
Published: February 2006

We present a direct observation of nanoscale ferroelectric domain pinning centers in lithium niobate crystals. A high-voltage atomic force microscope has been used to tailor nanodomain structures in LiNbO3 crystal with high defect concentration. Domain pinning and depinning events have been captured following thermally induced domain decay process. The pinning centers’ influence on the domain wall dynamics has been analyzed by comparing domain growth in stoichiometric and congruent LiNbO3 crystals.
Direct current bias effects on grain boundary Schottky barriers in CaCu3Ti4O12
Authors: Kim Il-Doo , Rothschild Avner , Tuller Harry L.
Published: February 2006

CaCu 3 Ti 4 O 12 exhibits an unusually high dielectric constant on the order of 105 and highly nonlinear I-V characteristics. Impedance spectroscopy measurements carried out in this work point to the crucial role played by grain boundary barriers in controlling the electrical properties of this material. Under dc bias, the grain boundary resistance decreases, followed by a precipitous breakdown at higher applied voltages. The barrier height is estimated to be ∼0.82eV. The grain conductivity shows a transition from a negative temperature coefficient of resistance with activation energy of ∼0.08eV to a positive temperature coefficient of resistance at 280 °C suggesting a transition from impurity ionization to scattering controlled mobility in the carrier saturation region.
Control of interfacial silicate between HfO2 and Si by high concentration ozone
Authors: Wang L. , Xue K. , Xu J. B. , Huang A. P. , Chu Paul K.
Published: February 2006

By high concentration ozone oxidation at low temperature, the Hf-silicate interfacial layer between HfO2 and silicon substrate is effectively controlled. This is evident by investigating the chemical shifts of the Hf4f and Si2p core-level spectra with depth by using x-ray photoelectron spectroscopy. The improved interfacial microstructure is further confirmed by high-resolution cross-sectional transmission electron microscopy. The capacitance-voltage curves, obtained from the metal-oxide-semiconductor capacitors using the ozone oxidized HfO2 as the gate dielectric, show a negligible hysteresis of about 5mV and a low fixed charge density.
Growth and characterization of AlGaNP on GaP(100) substrates
Authors: Odnoblyudov V. A. , Tu C. W.
Published: February 2006

We describe epitaxial growth of GaNP, AlNP, and AlGaNP with low nitrogen concentration (<5%) on GaP (100) substrates. Using a thermodynamic approach, we explain the difference between nitrogen incorporation into GaP and AlP. We demonstrate and explain peculiarities of AlGaNP quaternary alloy growth: Dependence of nitrogen concentration on Al composition and dependence of crystal quality on Al composition.
Characterization of thermally oxidized Ti∕SiO2 gate dielectric stacks on 4H–SiC substrate
Authors: Mahapatra R. , Poolamai N. , Chattopadhyay S. , Wright N. G. , Chakraborty Amit K. , Coleman Karl S. , Coleman P. G. , Burrows C. P.
Published: February 2006

The structural and electrical characteristics of thermally oxidized Ti∕SiO2 gate dielectric stacks on 4H–SiC substrates have been investigated. X-ray photoelectron spectroscopy shows a good stoichiometry of TiO2 films formed by thermal oxidation of evaporated Ti. No evidence of the formation of titanium silicide at the surface as well as in the interfacial layer was observed. Electrical measurements show, in particular, no signature of an increase in interface state density towards the conduction band edge of 4H–SiC. The improved leakage current with higher breakdown field of 11MV∕cm makes TiO2∕SiO2 stacks a potential gate insulator for high-power SiC devices.
Fabrication and characterization of vertical-type double-gate metal-oxide-semiconductor field-effect transistor with ultrathin Si channel and self-aligned source and drain
Authors: Masahara Meishoku , Liu Yongxun , Endo Kazuhiko , Matsukawa Takashi , Sakamoto Kunihiro , Ishii Kenichi , O’uchi Shinichi , Sugimata Etsuro , Yamauchi Hiromi , Suzuki Eiichi
Published: February 2006

A fabrication technique for a vertical double-gate metal-oxide-semiconductor field-effect transistor (DG MOSFET) with a standing-up ultrathin channel (UTC) and self-aligned source and drain (S/D) is proposed. A 20nm thick vertical UTC with low channel thickness fluctuation was formed on a (110)-oriented Si substrate using orientation-dependent wet etching. The top and bottom S/D were self-aligned to the DGs by using a combination of ion implantation and solid-phase diffusion. The fabricated vertical DG MOSFETs revealed that the channel thickness less influences the threshold voltage. Furthermore, a low sub-threshold slope of 68.8mV/decade was achieved with a channel thickness of 20nm.
Phase coexistence near the morphotropic phase boundary in lead zirconate titanate (PbZrO3-PbTiO3) solid solutions
Authors: Rossetti George A. , Zhang Wei , Khachaturyan Armen G.
Published: February 2006

An equilibrium phase diagram satisfying the Gibbs phase rule is computed for the PbZrO3-PbTiO3 (PZT) system from a low-order Landau expansion in the approximation of the theory of regular solutions. We show that in the equilibrium phase diagram, miscibility gaps replace the morphotropic phase boundary and the paraelectric to ferroelectric transition lines of the “diffusionless” phase diagram. The decomposition occurs by a peritectoid reaction and the miscibility gaps expand significantly with increasing positive values of the atomic exchange interaction parameter. Diffusional processes are estimated to be sufficiently fast to achieve two-phase equilibria at normal rates of cooling used to process PZT materials.
Magnetoresistance of n-type quantum dot solids
Authors: Yu Dong , Wehrenberg Brian L. , Yang Inseok , Kang Woowon , Guyot-Sionnest Philippe
Published: February 2006

Solid films of n-type Mn2+∕CdSe colloidal quantum dots show a positive magnetoresistance. At 0.3K the film resistance is increased by up to 150% at 10T. The variable range hopping model quantitatively accounts for the magnetoresistance at low field.
Low-temperature solvothermal route to 2H–SiC nanoflakes
Authors: Zou Guifu , Dong Chao , Xiong Kan , Li Hui , Jiang Changlong , Qian Yitai
Published: February 2006

Silicon carbide nanoflakes have been synthesized through a one-step solvothermal route involving reaction of SiCl4 and CaC2 at 180°C for the first time. According to x-ray powder diffraction, infrared, and Raman spectra analysis, the obtained nanoflakes possess a crystalline structure of 2H–SiC. Electron microscopy investigations show that the nanoflakes have typical diameters of 200–500nm, thickness of ∼15nm, and grow along the [001] direction. The nanoflakes exhibit a new photoluminescence peak at ∼314nm, which is ascribed to defects in the SiOx. The possible growth mechanism of the nanoflakes is discussed.
Moisture-absorption-induced permittivity deterioration and surface roughness enhancement of lanthanum oxide films on silicon
Authors: Zhao Yi , Toyama Masahiro , Kita Koji , Kyuno Kentaro , Toriumi Akira
Published: February 2006

Effects of moisture absorption on permittivity and surface roughness of lanthanum oxide (La2O3) films were investigated. It was found that the moisture absorption deteriorates the permittivity (k) of La2O3 films on silicon because of the formation of hexagonal La(OH)3 with a low permittivity after films were exposed to the air. Therefore, the moisture absorption should be a very possible reason for the permittivity variation of La2O3 film in literatures reported, so far. Furthermore, a roughness enhancement was also observed after La2O3 films were exposed to the air for several hours. This observation should be another concern of hygroscopic La2O3 film application.
Third-harmonic generation in a one-dimensional photonic-crystal-based amorphous nanocavity
Authors: Wang F. , Zhu S. N. , Li K. F. , Cheah K. W.
Published: February 2006

We report a large enhancement of third-harmonic generation in the one-dimensional dielectric photonic-crystal-based amorphous nanocavity. The enhancement took place at the frequency of defect mode and was a pure χ(3) nonlinear process. A great increase of third-harmonic intensity up to approximately five orders of magnitude was demonstrated, which was attributed to field localization in the range of nanocavity.
The New Mobilities Paradigm
Authors: Sheller Mimi , Urry John
Published: February 2006

It seems that a new paradigm is being formed within the social sciences, the ‘new mobilities’ paradigm. Some recent contributions to forming and stabilising this new paradigm include work from anthropology, cultural studies, geography, migration studies, science and technology studies, tourism and transport studies, and sociology. In this paper we draw out some characteristics, properties, and implications of this emergent paradigm, especially documenting some novel mobile theories and methods. We reflect on how far this paradigm has developed and thereby to extend and develop the ‘mobility turn’ within the social sciences.
Pioneering Mobilities: New Patterns of Movement and Motility in a Mobile World
Authors: Kesselring Sven
Published: February 2006

The paper presents empirical data from a research project on mobility pioneers. It shows new mobility patterns and constellations of mobility and immobility, movement and motility (mobility potential). The author raises the question as to whether the reported subject-oriented strategies for coping with the modern ‘mobility imperative’ open up a perspective on a structural change in the modern concept of mobility and mobility practice. The theory of reflexive modernization is used to discuss this question and to help to understand the relevance of the empirical findings. In concluding, the paper focuses on further mobility research and introduces a distinction between ‘transit spaces’ and ‘connectivity spaces’ as relevant issues for research on new configurations of spatial, social, and virtual mobility.
A voltage-driven switch for ion-independent signaling by
ether-à-go-go
K
+
channels
Authors: Hegle Andrew P. , Marble Daniel D. , Wilson Gisela F.
Published: February 2006

Voltage-gated channels maintain cellular resting potentials and generate neuronal action potentials by regulating ion flux. Here, we show that Ether-à-go-go (EAG) K
+
channels also regulate intracellular signaling pathways by a mechanism that is independent of ion flux and depends on the position of the voltage sensor. Regulation of intracellular signaling was initially inferred from changes in proliferation. Specifically, transfection of NIH 3T3 fibroblasts or C2C12 myoblasts with either wild-type or nonconducting (F456A)
eag
resulted in dramatic increases in cell density and BrdUrd incorporation over vector- and
Shaker
-transfected controls. The effect of EAG was independent of serum and unaffected by changes in extracellular calcium. Inhibitors of p38 mitogen-activated protein (MAP) kinases, but not p44/42 MAP kinases (extracellular signal-regulated kinases), blocked the proliferation induced by nonconducting EAG in serum-free media, and EAG increased p38 MAP kinase activity. Importantly, mutations that increased the proportion of channels in the open state inhibited EAG-induced proliferation, and this effect could not be explained by changes in the surface expression of EAG. These results indicate that channel conformation is a switch for the signaling activity of EAG and suggest an alternative mechanism for linking channel activity to the activity of intracellular messengers, a role that previously has been ascribed only to channels that regulate calcium influx.
The chromatoid body of male germ cells: Similarity with processing bodies and presence of Dicer and microRNA pathway components
Authors: Kotaja Noora , Bhattacharyya Suvendra N. , Jaskiewicz Lukasz , Kimmins Sarah , Parvinen Martti , Filipowicz Witold , Sassone-Corsi Paolo
Published: February 2006

The chromatoid body is a perinuclear, cytoplasmic cloud-like structure in male germ cells whose function has remained elusive. Here we show that the chromatoid body is related to the RNA-processing body of somatic cells. Dicer and components of microRNP complexes (including Ago proteins and microRNAs) are highly concentrated in chromatoid bodies. Furthermore, we show that Dicer interacts with a germ cell-specific chromatoid body component, the RNA helicase MVH (mouse VASA homolog). Thus, chromatoid bodies seem to operate as intracellular nerve centers of the microRNA pathway. Our findings underscore the importance of posttranscriptional gene regulation and of the microRNA pathway in the control of postmeiotic male germ cell differentiation.
The U
L
41 protein of herpes simplex virus 1 degrades RNA by endonucleolytic cleavage in absence of other cellular or viral proteins
Authors: Taddeo Brunella , Zhang Weiran , Roizman Bernard
Published: February 2006

The herpes simplex virus 1 ORF U
L
41 encodes a protein (virion host shutoff or
vhs
) associated with selective degradation of mRNA early in infection. Some mRNAs, exemplified by GAPDH or β-actin mRNAs, are degraded rapidly. Others, for example IEX-1 mRNA, are degraded in two stages: whereas the 3′ domain disappears rapidly, a large 5′ domain fragment of the mRNA lingers for several hours. Still a third, exemplified by tristetraprolin mRNA, is not degraded, allowing its protein product to accumulate in infected cells. Here we report the following: (
i
) a GST-
vhs
protein produced in
Escherichia coli
, solubilized and purified to homogeneity acts as bona fide endoribonuclease when tested on
in vitro
transcribed IEX-1 probes. A GST-
vhs
protein in which three key
vhs
amino acids were replaced with alanines, solubilized and purified by the same protocol, had no enzymatic activity. (
ii
) The number of fragments generated by cleavage of a truncated IEX-1 RNA by
vhs
appears to be small; the cleavage sites are centered at or near the AU-rich elements located at the 3′ untranslated region of the mRNA. A truncated RNA containing only the IEX-1 coding domain was cleaved numerous times. (
iii
) In cells infected at high multiplicity and exposed to a large number of particles per cell, the
vhs
protein accumulated within 3 h after infection, in small uniform cytoplasmic granules raising the possibility that
vhs
colocalizes with tristerapolin, a protein induced after infection, in structures involved in degradation of RNA.
Negative regulation of activation-induced cytidine deaminase in B cells
Authors: Muto Taro , Okazaki Il-mi , Yamada Shuichi , Tanaka Yoshimasa , Kinoshita Kazuo , Muramatsu Masamichi , Nagaoka Hitoshi , Honjo Tasuku
Published: February 2006

Both class switch recombination (CSR) and somatic hypermutation (SHM) of the Ig genes require the activity of activation-induced cytidine deaminase (AID). Expression of AID is restricted to B cells in the germinal centers of the lymphoid organs, where activated B cells undergo CSR and SHM. We previously showed that constitutive and systemic expression of AID leads to tumorigenesis in T cells and lung epithelium, but not in B cells. This finding led us to suspect that transgenic AID may be inactivated at least in part in B cells. To address this issue, we generated conditional AID-transgenic mice that constitutively express AID only in B cells. Studies on the cross between the AID-transgenic and AID-deficient mice showed that abundant AID protein accumulated by constitutive expression is inactivated in B cells, possibly providing an explanation for the absence of deregulation of CSR and SHM in AID-transgenic B cells.
Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments on the Pacific Ocean Margin
Authors: Inagaki Fumio , Nunoura Takuro , Nakagawa Satoshi , Teske Andreas , Lever Mark , Lauer Antje , Suzuki Masae , Takai Ken , Delwiche Mark , Colwell Frederick S. , Nealson Kenneth H. , Horikoshi Koki , D’Hondt Steven , Jørgensen Bo B.
Published: February 2006

The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their phylogenetic diversities in deeply buried marine sediments of the Pacific Ocean Margins. During the Ocean Drilling Program Legs 201 and 204, we obtained sediment cores from the Peru and Cascadia Margins that varied with respect to the presence of dissolved methane and methane hydrate. To examine differences in prokaryotic distribution patterns in sediments with or without methane hydrates, we studied >2,800 clones possessing partial sequences (400–500 bp) of the 16S rRNA gene and 348 representative clone sequences (≈1 kbp) from the two geographically separated subseafloor environments. Archaea of the uncultivated Deep-Sea Archaeal Group were consistently the dominant phylotype in sediments associated with methane hydrate. Sediment cores lacking methane hydrates displayed few or no Deep-Sea Archaeal Group phylotypes. Bacterial communities in the methane hydrate-bearing sediments were dominated by members of the JS1 group, Planctomycetes, and Chloroflexi. Results from cluster and principal component analyses, which include previously reported data from the West and East Pacific Margins, suggest that, for these locations in the Pacific Ocean, prokaryotic communities from methane hydrate-bearing sediment cores are distinct from those in hydrate-free cores. The recognition of which microbial groups prevail under distinctive subseafloor environments is a significant step toward determining the role these communities play in Earth’s essential biogeochemical processes.
An ordered, nonredundant library of
Pseudomonas aeruginosa
strain PA14 transposon insertion mutants
Authors: Liberati Nicole T. , Urbach Jonathan M. , Miyata Sachiko , Lee Daniel G. , Drenkard Eliana , Wu Gang , Villanueva Jacinto , Wei Tao , Ausubel Frederick M.
Published: February 2006

Random transposon insertion libraries have proven invaluable in studying bacterial genomes. Libraries that approach saturation must be large, with multiple insertions per gene, making comprehensive genome-wide scanning difficult. To facilitate genome-scale study of the opportunistic human pathogen
Pseudomonas aeruginosa
strain PA14, we constructed a nonredundant library of PA14 transposon mutants (the PA14NR Set) in which nonessential PA14 genes are represented by a single transposon insertion chosen from a comprehensive library of insertion mutants. The parental library of PA14 transposon insertion mutants was generated by using
MAR2xT7
, a transposon compatible with transposon-site hybridization and based on
mariner
. The transposon-site hybridization genetic footprinting feature broadens the utility of the library by allowing pooled
MAR2xT7
mutants to be individually tracked under different experimental conditions. A public, internet-accessible database (the PA14 Transposon Insertion Mutant Database,
http://ausubellab.mgh.harvard.edu/cgi-bin/pa14/home.cgi
) was developed to facilitate construction, distribution, and use of the PA14NR Set. The usefulness of the PA14NR Set in genome-wide scanning for phenotypic mutants was validated in a screen for attachment to abiotic surfaces. Comparison of the genes disrupted in the PA14 transposon insertion library with an independently constructed insertion library in
P. aeruginosa
strain PAO1 provides an estimate of the number of
P. aeruginosa
essential genes.
An enzymatic ruler modulates Lewis antigen glycosylation of
Helicobacter pylori
LPS during persistent infection
Authors: Nilsson Christina , Skoglund Anna , Moran Anthony P. , Annuk Heidi , Engstrand Lars , Normark Staffan
Published: February 2006

Helicobacter pylori
persistently colonizes about half the human population and contributes to the development of peptic ulcer disease and gastric cancer. This organism has evolved means to structurally alter its surface characteristics to evade innate and adaptive immune responses.
H. pylori
produces LPS O-antigen units that can be posttranslationally fucosylated to generate Lewis antigens, structures also found on human epithelial cells. We demonstrate an extensive diversity of Lewis x and Lewis y expression in LPS O-antigen units, occurring over time and in different regions of the human stomach. Lewis expression patterns were correlated with the on/off status of the three fucosyltransferases (FucT), FutA, FutB, and FutC, which are regulated via slipped-strand mispairing in intragenic polyC tract regions of the corresponding genes. The α1,3-FucT, FutA and FutB, each contain a C-terminal heptad repeat region, consisting of a variable number of DD/NLRV/INY tandem repeats. Variations in the number of heptad repeats correlated to the sizes of O-antigen polymers to become decorated by fucose residues. Our data support a molecular ruler mechanism for how
H. pylori
varies its LPS fucosylation pattern, where one heptad repeat in the enzyme corresponds to one
N
-acetyl-β-lactosamine unit in the O-antigen polysaccharide.
Increased production of reactive oxygen species in hyperglycemic conditions requires dynamic change of mitochondrial morphology
Authors: Yu Tianzheng , Robotham James L. , Yoon Yisang
Published: February 2006

Increased production of mitochondrial reactive oxygen species (ROS) by hyperglycemia is recognized as a major cause of the clinical complications associated with diabetes and obesity [Brownlee, M. (2001)
Nature
414, 813–820]. We observed that dynamic changes in mitochondrial morphology are associated with high glucose-induced overproduction of ROS. Mitochondria undergo rapid fragmentation with a concomitant increase in ROS formation after exposure to high glucose concentrations. Neither ROS increase nor mitochondrial fragmentation was observed after incubation of cells with the nonmetabolizable stereoisomer
l
-glucose. However, inhibition of mitochondrial pyruvate uptake that blocked ROS increase did not prevent mitochondrial fragmentation in high glucose conditions. Importantly, we found that mitochondrial fragmentation mediated by the fission process is a necessary component for high glucose-induced respiration increase and ROS overproduction. Extended exposure to high glucose conditions, which may mimic untreated diabetic conditions, provoked a periodic and prolonged increase in ROS production concomitant with mitochondrial morphology change. Inhibition of mitochondrial fission prevented periodic fluctuation of ROS production during high glucose exposure. These results indicate that the dynamic change of mitochondrial morphology in high glucose conditions contributes to ROS overproduction and that mitochondrial fission/fusion machinery can be a previously unrecognized target to control acute and chronic production of ROS in hyperglycemia-associated disorders.