bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of ChREBP in hepatic steatosis and insulin resistance
Authors: Denechaud Pierre-Damien , Dentin Renaud , Girard Jean , Postic Catherine
Published: August 2007

Non‐alcoholic fatty liver disease is tightly associated with insulin resistance, type 2 diabetes and obesity, but the molecular links between hepatic fat accumulation and insulin resistance are not fully identified. Excessive accumulation of triglycerides (TG) is one the main characteristics of non‐alcoholic fatty liver disease and fatty acids utilized for the synthesis of TG in liver are available from the plasma non‐esterified fatty acid pool but also from fatty acids newly synthesized through hepatic de novo lipogenesis. Recently, the transcription factor ChREBP (carbohydrate responsive element binding protein) has emerged as a central determinant of lipid synthesis in liver through its transcriptional control of key genes of the lipogenic pathway, including fatty acid synthase and acetyl CoA carboxylase. In this mini‐review, we will focus on the importance of ChREBP in the physiopathology of hepatic steatosis and insulin resistance by discussing the physiological and metabolic consequences of ChREBP knockdown in liver of ob/ob mice.
Tumor necrosis factor‐α exerts pro‐myogenic action in C2C12 myoblasts via sphingosine kinase/S1P2 signaling
Authors: Donati Chiara , Nincheri Paola , Cencetti Francesca , Rapizzi Elena , Farnararo Marta , Bruni Paola
Published: August 2007

In this study, we report that low doses of tumor necrosis factor‐α (TNFα) promote myogenesis in C2C12 myoblasts. Moreover, the cytokine increased sphingosine kinase (SphK) activity and induced SphK1 translocation to membranes. The inhibition of SphK functionality by various approaches abrogated the pro‐myogenic effect of TNFα. Moreover, silencing of S1P2 impaired the positive action of TNFα on myogenesis. These results represent the first evidence that SphK/S1P2 axis is required for the regulation of myogenesis by TNFα. In view of the physiological role of TNFα in muscle regeneration, the present finding reinforces the notion that SphK/S1P2 signaling is critically implicated in myogenesis.
Cholesterol is more susceptible to oxidation than linoleates in cultured cells under oxidative stress induced by selenium deficiency and free radicals
Authors: Saito Yoshiro , Yoshida Yasukazu , Niki Etsuo
Published: August 2007

Polyunsaturated fatty acids and their esters are known to be susceptible to free‐radical mediated oxidation, while cholesterol is more resistant to oxidation. The present study focused on the relative susceptibilities of linoleates and cholesterol in Jurkat cells under oxidative stress induced by selenium deficiency and free radical insult, as assessed by total hydroxyoctadecadienoic acids (tHODE) and total 7‐hydroxycholesterol (t7‐OHCh) measured after reduction and saponification. It was observed that the levels of tHODE and t7‐OHCh significantly increased by both oxidative insults. The increased amounts of t7‐OHCh were higher than those of tHODE in both selenium‐deficient and free radical‐treated cells. These results suggest that, in contrast to plasma oxidation where cholesterol is much more resistant to oxidation than linoleates, cellular cholesterol is more susceptible to oxidation than cellular linoleates.
Modelling of road surface temperature from a geographical parameter database. Part 2: Numerical
Authors: Chapman Lee , Thornes John E , Bradley Andrew V
Published: August 2007

A new ice prediction strategy is presented based on the numerical modelling of surveyed geographical parameters. This approach enables the thermal projection of road surface temperatures across the road network entirely by model predictions and without the need for thermal maps. The influence of eight geographical parameters (latitude, altitude, sky‐view factor, screening, roughness length, road construction, traffic density and topography) is investigated by means of sensitivity analyses. The sky‐view factor is highlighted as the dominant control on road surface temperature, particularly at high levels of atmospheric stability. A numerical road weather model incorporating all eight parameters was run over 20 nights using forecast and retrospective meteorological data. The model has the ability to explain up to 72% of the variation in road surface temperature purely by thermally projecting surface temperature using geographical variables. Retrospective results produce an average r.m.s. error of $1\ ^{\circ}\hbox{C}$ which is comparable to existing UK road weather models. Copyright © 2001 Royal Meteorological Society
Road Climate in Cities:A Study of the Stockholm Area, South‐East Sweden
Authors: Gustavsson Torbjörn , Bogren Jörgen , Green Cecilia
Published: August 2007

The difference between air and road surface temperature in urban and rural areas is an important consideration when modelling the road climate. In this study the effect of the urban heat island in the Stockholm area on road climate is examined. Factors such as distance from the city centre, traffic and topography are analysed in order to assess their impact on the spatial variation of road and air temperature. Copyright © 2001 Royal Meteorological Society
Effects of clay content on the frictional strength and fluid transport property of faults
Authors: Takahashi Miki , Mizoguchi Kazuo , Kitamura Keigo , Masuda Koji
Published: August 2007

We examined two effects of the presence of clay in brittle deformations: the reduction in frictional strength and the impediment of across‐fault fluid flow. Permeability was monitored during the sliding deformation of a gouge of various mixes of Na‐montmorillonite powder and granular quartz along a 30° precut surface of Berea sandstone under 80 MPa of normal stress, 5 MPa of pore water pressure, and room temperature. The decrease in the friction coefficient of a gouge with increasing clay content was not simple, but showed a sharp drop at 50 vol.% clay content. The reduction in permeability due to deformation increased with increasing clay content from 0 to 24 vol.%, and a dramatic reduction of ∼2.5 orders of magnitude occurred at 18 and 24 vol.% clay content. However, in a gouge with more than 29 vol.% clay content, deformation reduced the permeability by only 0.5 orders of magnitude. Thus the transitional clay contents at which the clay dominated the properties of fault strength and fluid transport were 50 and 29 vol.%, respectively. These values almost agree well with values obtained using a model with an equal‐sized clast (quartz) framework. The clay matrix can completely fill the pores sustained by a closest‐packed quartz framework when the clay content reaches 29 vol.%, whereas the content required to fill the pores of a framework that can barely sustain quartz‐quartz contact is 50 vol.%.
Characteristics of short‐period wavelike features near 87 km altitude from airglow and lidar observations over Maui
Authors: Hecht J. H. , Liu A. Z. , Walterscheid R. L. , Franke S. J. , Rudy R. J. , Taylor M. J. , Pautet P.‐D.
Published: August 2007

Small‐scale (less than 15 km horizontal wavelength) wavelike structures known as ripples are a common occurrence in OH airglow images. Recent case studies attribute their origin to the presence of either convective or dynamical instabilities. However, little is known about their frequency of occurrence and period. The Maui‐MALT Observatory, located at Mt. Haleakala, is instrumented with a Na wind/temperature lidar, which allows the determination of whether the atmosphere is dynamically or convectively unstable, and a fast OH airglow camera which takes images every 3 s with a sensitivity high enough to see the ripples. This study reports on 2 months of observations in October/November 2003 and in August 2004, eight nights of which also included Na lidar measurements. The imager results suggest that instability features occur in the 85‐ to 90‐km region of the atmosphere for around 20% of the time. The nominal observed period for the ripples is between 2 and 4 min. While there are clear night‐to‐night variations, the average observed period is similar for both the 2003 and 2004 observations. In addition, a few of the small‐scale structures are not ripples caused by instabilities but rather have features consistent with their being short horizontal wavelength evanescent waves. Their fractional intensity fluctuations are as large or larger than those of the ripple instabilities. Unlike the instabilities, the origin of the evanescent waves is not determined.
Reduction in northward incursions of the South Asian monsoon since ∼1400 AD inferred from a Mt. Everest ice core
Authors: Kaspari S. , Mayewski P. , Kang S. , Sneed S. , Hou S. , Hooke R. , Kreutz K. , Introne D. , Handley M. , Maasch K. , Qin D. , Ren J.
Published: August 2007

A highly resolved Mt. Everest ice core reveals a decrease in marine and increase in continental air masses related to relatively high summer surface pressure over Mongolia, and reduction in northward incursions of the summer South Asian monsoon since ∼1400 AD. Previously published proxy records from lower sites south of the Himalayas indicate strengthening of the monsoon since this time. These regional differences are consistent with a south–north seesaw in convective activity in the Asian monsoon region, and reflect a southward shift in the mean summer position of the monsoon trough since ∼1400 AD. The change in monsoonal circulation at 1400 AD is synchronous with a reduction in solar irradiance and the onset of the LIA. This demonstrates a hemispheric scale circulation reorganization at this time, and the potential for future large shifts in monsoonal circulation.
Thermal evolution of permeability and microstructure in sea ice
Authors: Golden K. M. , Eicken H. , Heaton A. L. , Miner J. , Pringle D. J. , Zhu J.
Published: August 2007

The fluid permeability k of sea ice constrains a broad range of processes, such as the growth and decay of seasonal ice, the evolution of summer ice albedo, and biomass build‐up. Such processes are critical to how sea ice and associated ecosystems respond to climate change. However, studies of k and its dependence on brine porosity ϕ and microstructure are sparse. Here we present a multifaceted theory for k(ϕ) which closely captures laboratory and field data. X‐ray computed tomography provides an unprecedented look at the brine phase and its connectivity. We find that sea ice displays universal transport properties remarkably similar to crustal rocks, yet over a much narrower temperature range. Our results yield simple parameterizations for fluid transport in terms of temperature and salinity, and permit more realistic representations of sea ice in global climate and biological models.
Production of conidia by Peronosclerospora sorghi on sorghum crops in Zimbabwe
Authors: Bock C. H. , Jeger M. J. , Mughogho L. K. , Mtisi E. , Cardwell K. F.
Published: August 2007

Factors affecting the production of conidia of Peronosclerospora sorghi, causing sorghum downy mildew (SDM), were investigated during 1993 and 1994 in Zimbabwe. In the field conidia were detected on nights when the minimum temperature was in the range 10–19°C. On 73% of nights when conidia were detected rain had fallen within the previous 72 h and on 64% of nights wind speed was < 2.0 m s−1. The time period over which conidia were detected was 2–9 h. Using incubated leaf material, conidia were produced in the temperature range 10–26°C. Local lesions and systemically infected leaf material produced 2.4–5.7 × 103 conidia per cm2. Under controlled conditions conidia were released from conidiophores for 2.5 h after maturation and were shown to be well adapted to wind dispersal, having a settling velocity of 1.5 × 10−4 m s−1. Conditions that are suitable for conidia production occur in Zimbabwe and other semi‐arid regions of southern Africa during the cropping season.
Contribution of phonon and vacancion excitations to the thermodynamic properties of solid helium
Authors: Vekhov Ye. O. , Grigor’ev V. N. , Maidanov V. A. , Mikhin N. P. , Rubanskiy V. Yu. , Rubets S. P. , Rudavskii E. Ya. , Rybalko A. S. , Syrnikov Ye. V. , Tikhiy V. A.
Published: August 2007

Precision measurements of the temperature dependence of the pressure are made on high-quality crystals of He4 and He3–He4 solutions grown at a constant volume. The phonon and vacancion contributions to the pressure are separated on the basis of the Debye model for the phonons and the model of wide-band vacancion excitations. This approach is also used to analyze all the other available thermodynamic data for the solid pure isotopes of helium and their solutions. This yields information about the Debye temperature and vacancy activation energy, and a universal dependence of these parameters on the molar volume is found for He3, He4, and He3–He4 solutions. The values found for the corresponding Grüneisen parameters turn out to be independent of the molar volume.
The electromagnetic response of a superconducting ferromagnet
Authors: Leviev G. I. , Tsindlekht M. I. , Sonin E. B. , Felner I.
Published: August 2007

The electromagnetic response of the superconducting ferromagnets RuSr2Gd1.5Ce0.5Cu2O10 (Ru–1222Gd) in an ac magnetic field of finite amplitude is investigated. Taking into account weak links between granules and magnetization of the magnetic sublattice, it is shown that the response of a sample in a superconducting state at the fundamental frequency and at the frequency of the third harmonic can be described by a nonlinear equation for the macroscopic field. Generation of the harmonic at temperatures above the superconducting transition corresponds to Rayleigh’s mechanism. For various regimes of sample cooling, the internal magnetic field determined by the magnetic sublattice is measured. This is direct evidence of the coexistence of ferromagnetic and superconductive order parameters in high-Tc ruthenocuprates.
Rabi oscillations and quantum beats in a qubit in a distorted magnetic field
Authors: Ivanchenko E. A. , Tolstoluzhsky A. P.
Published: August 2007

The time-periodic modulation of the magnetic field stabilizing the magnetic resonance position in a two-level system is investigated. It is shown that the fundamental resonance is stable against a harmonized variation of the longitudinal and transverse magnetic fields. The time dependence of the Rabi oscillations and quantum beats of the spin-flip probability is investigated numerically in different parameter regimes, taking into account dissipation and decoherence in the Lindblad form. The present study may be useful in the analysis of interference experiments and for manipulation of quantum bits.
Effect of the redistribution of labile oxygen on the pseudogap state in untwinned single crystal YBa2Cu3O7−x
Authors: Vovk R. V. , Obolenskiĭ M. A. , Zavgorodniĭ A. A. , Bondarenko A. V. , Gulatis I. L. , Chebotaev N. N.
Published: August 2007

The influence of room-temperature annealing on the excess conductivity of untwinned single crystal YBa2Cu3O7−x with a small deviation of from oxygen stoichiometry is investigated. It is found that the range of existence of the pseudogap regime undergoes a relative expansion of the range of existence of the pseudogap regime during a four-day period of annealing. The absolute magnitude of the pseudogap decreases by approximately 10%.
Line and boundary tensions on approach to the wetting transition
Authors: Koga K. , Widom B.
Published: August 2007

A mean-field density-functional model often used in the past in the study of line and boundary tensions at wetting and prewetting transitions is reanalyzed by extensive numerical calculations, approaching the wetting transition much more closely than had previously been possible. The results are what are now believed to be definitive for the model. They include strong numerical evidence for the presence of the logarithmic factors predicted by theory both in the mode of approach of the prewetting line to the triple-point line at the point of the first-order wetting transition and in the line tension itself on approach to that point. It is also demonstrated with convincing numerical precision that the boundary tension on the prewetting line and the line tension on the triple-point line have a common limiting value at the wetting transition, again as predicted by theory. As a by product of the calculations, in the model’s symmetric three-phase state, far from wetting, it is found that certain properties of the model’s line tension and densities are almost surely given by simple numbers arising from the symmetries, but proving that these are exact for the model remains a challenge to analytical theory.
Dynamics of trehalose molecules in confined solutions
Authors: Lelong Gérald , Price David L. , Brady John W. , Saboungi Marie-Louise
Published: August 2007

The dynamics of trehalose molecules in aqueous solutions confined in silica gel have been studied by quasielastic neutron scattering (QENS). Small-angle neutron scattering measurements confirmed the absence of both sugar clustering and matrix deformation of the gels, indicating that the results obtained are representative of homogeneous trehalose solutions confined in a uniform matrix. The pore size in the gel is estimated to be 18nm, comparable to the distances in cell membranes. For the QENS measurements, the gel was prepared from D2O in order to accentuate the scattering from the trehalose. Values for the translational diffusion constant and effective jump distance were derived from model fits to the scattering function. Comparison with QENS and NMR results in the literature for bulk trehalose shows that confinement on a length scale of 18nm has no significant effect on the translational diffusion of trehalose molecules.
Regarding convergence curve of virial expansion for the Lennard-Jones system
Authors: Apfelbaum E. M. , Vorob’ev V. S. , Martynov G. A.
Published: August 2007

We calculate the convergence curve of the virial expansion for a Lennard-Jones system in the density-temperature plane using the approximate method based on the density expansion of the Ornstein-Zernike equation and the condition of thermodynamic consistency [J. Chem. Phys. 106, 6095 (1997)]. At subcritical temperatures, this curve is close to the binodal. At supercritical temperatures, the curve does not coincide with the freezing curve. In the latter case, the densities along the convergence line are distinctly smaller than the densities corresponding to the condensed state.
Fourier transform infrared observation of the ν1(σ) mode of linear CoC3 trapped in solid Ar
Authors: Bates S. A. , Rhodes J. A. , Rittby C. M. L. , Graham W. R. M.
Published: August 2007

Fourier transform infrared (FTIR) and density functional theory (DFT) isotopic studies on cobalt-carbon species have resulted in the detection of linear CoC3. Dual laser ablation of carbon and cobalt rods, followed by trapping the products in solid Ar at ∼10K, produced the CoC3 chain. FTIR measurements of C13 isotopic shifts are in good agreement with the predictions of DFT calculations using the B3LYP and BPW91 functionals and the 6-311+G(3df) basis set, confirming the assignment of the ν1(σ) fundamental of linear CoC3 at 1918.2cm−1.
Rapid sampling of reactive Langevin trajectories via noise-space Monte Carlo
Authors: Dickson B. M.
Published: August 2007

A noise-space Monte Carlo approach to sampling reactive Langevin trajectories is introduced and compared to a configuration based approach. The noise sampling is shown to overcome the slow relaxation of the configuration based method. Furthermore, the noise sampling is shown to sample multiple pathways with the correct probabilities without any additional work being required formally or algorithmically. The path sampling proceeds without any introduction of fictitious interactions and includes only the parameters appearing in Langevin’s equation.
Elastic stability of a dual coated optical fiber with a stripped off coating at its end
Authors: Suhir E.
Published: August 2007

The coating system in a dual coated optical fiber should be designed in such a way that, at low temperature conditions, the fiber does not experience microbending, i.e., does not buckle within the low modulus primary coating. In some optical fiber structures, such as, e.g., optical connectors, the end portions of dual coated fibers are stripped off, and the free ends of the fibers might experience appreciable mechanical compression. Accordingly, in this analysis we evaluate the critical (Euler) force for a dual coated optical fiber with a stripped off end portion. We establish the level of the external (“mechanical”) compression that, when added to the “intrinsic” thermally induced compression in the coated portion of the fiber, leads to its buckling. In addition, we establish the length of the “free” (stripped off) portion of the fiber, for which the critical force is equal to the critical force for the coated portion. We idealize the dual coated optical fiber as an infinitely long beam lying on a continuous elastic foundation, which is provided by the coating system. The general concepts are illustrated by a numerical example. We found in this example that the free portion of the fiber should not be longer than 0.45mm to remain straight (elastically stable) under the action of the external compression of the magnitude of about 0.85kgf. This is the predicted critical force for the coated portion of the fiber, which is subjected to both thermally induced and mechanical loading. The obtained results can be helpful in the physical design of dual coated optical fibers with stripped off coatings at the ends.
Substrate biasing effect on the electrical properties of magnetron-sputtered high-k titanium silicate thin films
Authors: Brassard D. , El Khakani M. A. , Ouellet L.
Published: August 2007

We report on the effect of substrate biasing on the properties of high-dielectric constant (high-k) titanium silicate (TixSi1−xO2) thin films deposited with a room-temperature magnetron-sputtering process. The composition, microstructure, and electrical properties of the TixSi1−xO2 films were systematically characterized, as a function of the substrate bias voltage (VS), by means of various complementary techniques, including x-ray photoelectron spectroscopy, x-ray reflectivity, Rutherford backscattering spectrometry, and appropriate electrical characterizations. We show, in particular, that depositing the TixSi1−xO2 films with a relatively small biasing voltage (VS≈−15 V) leads not only to a significant reduction of their porosity but more interestingly to a marked improvement of their electrical properties. A further increase of the negative bias voltage (from 20 to 110 V) was, however, found to increase progressively the leakage current through the TixSi1−xO2 films. Such a degradation of the electrical properties at high VS values is shown to be associated with some resputtering and defects generation caused by the rather energetic bombardment conditions. In contrast, the “soft hammering” induced by the relatively low-energy ion bombardment densifies the films and improves their properties. Under the optimal substrate biasing conditions (VS∼−15 V), the room-temperature deposited titanium silicate films are shown to exhibit a highly attractive combination of electrical properties, namely a k value as high as ∼17, a dissipation factor <0.01, a leakage current as low as 5×10−9 A∕cm2 at 1 MV/cm, and a breakdown field higher than 4 MV/cm.
Electrical characterization of SnO2:Sb ultrathin films obtained by controlled thickness deposition
Authors: Giraldi Tania R. , Lanfredi Alexandre J. C. , Leite Edson R. , Escote Marcia T. , Longo Elson , Varela José A. , Ribeiro Caue , Chiquito Adenilson J.
Published: August 2007

A representative study is reported on the electrical properties of SnO2:Sb ultrathin films (thickness of 40–70 nm) produced by a deposition method based on aqueous colloidal suspensions of 3–5 nm crystalline oxides. The results revealed the films’ electrical behavior in a range of 10–300 K, showing a strong dependence on dopant incorporation, with minimum resistivity values in 10 mol % of Sb content. All the samples displayed semiconductor behavior, but the transport mechanism showed a strong dependence on thickness, making it difficult to fit it to well-known models. In thicker films, the mechanism proved to be an intermediary system, with thermally activated and hopping features. Electron hopping was estimated in the range of 0.4–1.9 nm, i.e., in the same order as the particle size.
Observation of second-harmonic generation in an oriented glassy nematic phase of a closo-decaborane derivative
Authors: Miniewicz Andrzej , Samoc Anna , Samoc Marek , Kaszynski Piotr
Published: August 2007

The optical second-harmonic generation (SHG) and the linear optical properties were investigated in a planar cell containing aligned nonchiral nematic derivative of B10H102−: 1-(4-heptyloxypyridin-1-yl)-10-(4-pentyl-1-thiacyclohexyl)-closo-decaborane (HPTD) as a function of temperature. The compound showed a low level of the SHG signal in the polycrystalline state, and no nonlinear optical effect was detected in the fluid nematic state (N) either in the presence or absence of an orienting electric field. When frozen, the resulting thermodynamically unstable nematic glassy phase (glassy N) unexpectedly exhibited the second-order nonlinear optical properties, implying a partial polar order in the arrangement of the in-plane-aligned molecules in a liquid-crystal cell. The efficiency of the SHG was analyzed for two polarization configurations yielding the main component of the second-order nonlinear susceptibility χxxx(2)=2.3±0.3pmV−1 along the nematic director x. A comparison of the experimental susceptibility with a hypothetical one estimated from the vectorial component of the molecular hyperpolarizability showed a relatively low degree of the spontaneous polar order. The dispersion of the principal refractive indices in the glassy state of HPTD was derived from dichroic absorption spectra using an interference fringe method and fitted with a Sellmeier-type equation. At 527nm the birefringence of HPTD is Δn=0.31.
Nanostructured FeZrCuB alloys prepared by mechanosynthesis
Authors: Pereira R. D. , Passamani E. C. , Larica C. , Freitas J. C. C. , Takeuchi A. Y.
Published: August 2007

Nanostructured Fe84Zr9B6Cu1 alloys were prepared by the mechanosynthesis method, following two alternative routes. In the first procedure, the alloy was directly obtained from the milling of the powder mixture of all elemental components. The resulting alloy was partially nanocrystalline, with dispersion of nanograins in an amorphous matrix. In the second route, Cu and B elemental powders were progressively added to a previously milled Fe90Zr10 alloy. A nearly single amorphous phase was consequently obtained. The dispersion of nanograins was easily recovered in this case, after annealing the milled alloy. The hyperfine magnetic properties of the amorphous phase prepared by milling were comparable to those found in similar melt-spun alloys. The crystallization temperatures and activation energies, associated with the first and second crystallization stages, were found to be lower for the milled alloy when compared with the corresponding melt-spun alloy, an effect associated with the larger number of defects induced by the mechanosynthesis process.
Self-absorption correction for solid-state photoluminescence quantum yields obtained from integrating sphere measurements
Authors: Ahn Tai-Sang , Al-Kaysi Rabih O. , Müller Astrid M. , Wentz Katherine M. , Bardeen Christopher J.
Published: August 2007

A new method is presented for analyzing the effects of self-absorption on photoluminescence integrating sphere quantum yield measurements. Both the observed quantum yield and luminescence spectrum are used to determine the self-absorption probability, taking into account both the initial emission and subsequent absorption and reemission processes. The analysis is experimentally validated using the model system of the laser dye perylene red dispersed in a polymer film. This approach represents an improvement over previous methods that tend to overestimate the true quantum yield, especially in cases with high sample absorbance or quantum yield values.
Simulation of twin boundary effect on characteristics of single grain-silicon thin film transistors
Authors: Yan F. , Migliorato P. , Ishihara R.
Published: August 2007

The influence of twin boundaries on the characteristics of single grain-silicon thin film transistors has been analyzed by three-dimensional simulation. The simulations show that the orientation and the location of a twin boundary could affect the field-effect mobility and the leakage current of a device. The field-effect mobility increases with the increase of the angle between the normal direction of the twin boundary and the channel direction. A single twin boundary in contact with the drain can lead to higher leakage current because electron-hole generation is greatly enhanced by the trap states in the twin boundary.
Low-temperature ordering of (001) granular FePt films by inserting ultrathin SiO2 layers
Authors: Wu Yun-Chung , Wang Liang-Wei , Lai Chih-Huang
Published: August 2007

L 1 0 granular FePt–SiO2 films with a (001) preferred orientation and well-separated grains of 5.14nm were obtained by depositing atomic-scale Fe∕Pt∕SiO2 multilayers (MLs) on glass substrates and subsequently annealing MLs at a temperature of 350°C. Large out-of-plane coercivity of 7700Oe and a high ordering factor of 0.83 were achieved. Alternate atomic-scale depositions promoted the formation of (001) textures. Furthermore, because of the low surface energy of SiO2 layers, SiO2 tended to diffuse into grain boundaries of FePt during annealing, which may accelerate diffusion of Fe and Pt atoms, resulting in the low-temperature ordering.
Point-contact spectrum of the electron-phonon interaction in mercury
Authors: Khotkevich A. V. , Konopatskiĭ B. L. , Khotkevich V. V. , Morlok S. V.
Published: August 2007

A method is proposed for creating mercury point-contacts for point-contact spectroscopy. In this method point-contacts are produced at low temperature between mercury-coated metal substrate electrodes. The coatings are produced by exposing the electrodes to mercury at room temperature. The nonlinear part of the normal-state resistance of the contacts is studied experimentally, after which the point-contact electron-phonon interaction function is reconstructed. The experimental results are in good agreement with existing data on the tunneling effect in superconductors. Specifically, good agreement obtains for the positions of the main peak of the electron-phonon interaction function, the maximum phonon frequency, and the numerical values of the average and rms phonon frequencies.
Nanoscale thermoelastic probing of megahertz thermal diffusion
Authors: Tomoda Motonobu , Wright Oliver B. , Li Voti Roberto
Published: August 2007

The authors demonstrate a method to probe thermal diffusion at megahertz frequencies with nanometer lateral resolution in a thin opaque film on a transparent substrate. They map photothermally induced megahertz surface vibrations in an atomic force microscope using tightly focused optical illumination from the substrate side. By comparison with a theoretical model of the surface displacement field, the authors derive the thermal diffusivity of a thin chromium film on a silica substrate.
Nonvolatile memory effect of capacitance in polycrystalline spinel vanadate
Authors: Takei H. , Suzuki T. , Katsufuji T.
Published: August 2007

The authors found that capacitance of polycrystalline spinel FeV2O4 exhibits a magnetic-field dependence with hysteresis and takes two values at zero field depending on the direction of a small magnetic field (∼1000G) applied prior to measurement. This behavior can be potentially used as a nonvolatile memory device in which the data are stored as a difference of capacitance through the change of magnetic-field directions.
Broadband all-optical ultrasound transducers
Authors: Hou Yang , Kim Jin-Sung , Ashkenazi Shai , Huang Sheng-Wen , Guo L. Jay , O’Donnell Matthew
Published: August 2007

A broadband all-optical ultrasound transducer has been designed, fabricated, and tested for high-resolution ultrasound imaging. It consists of a two-dimensional gold nanostructure on a glass substrate, followed by a 3μm polydimethylsiloxane layer and a 30nm gold layer. The signal to noise ratio of a pulse-echo signal is over 10dB in the far field of the transducer, where the center frequency is 40MHz with −6dB bandwidth of 57MHz. The potential for high-frequency ultrasound arrays using this technology is demonstrated using multiple measurements from the transducer to image a 25μm diameter wire.
Stabilization of higher-κ tetragonal HfO2 by SiO2 admixture enabling thermally stable metal-insulator-metal capacitors
Authors: Böscke T. S. , Govindarajan S. , Kirsch P. D. , Hung P. Y. , Krug C. , Lee B. H. , Heitmann J. , Schröder U. , Pant G. , Gnade B. E. , Krautschneider W. H.
Published: August 2007

The authors report the relationship between HfO2 crystalline phase and the resulting electrical properties. Crystallization of amorphous HfO2 into the monoclinic phase led to a significant increase in leakage current and formation of local defects. Admixture of 10% SiO2 avoided formation of these defects by stabilization of the tetragonal phase, and concurrently increased the permittivity to 35. This understanding enabled fabrication of crystalline HfO2 based metal-insulator-metal capacitors able to withstand a thermal budget of 1000°C while optimizing capacitance equivalent thickness (<1.3nm) at low leakage [J(1V)<10−7A∕cm2].
Stoichiometry, mobility, and performance in bulk heterojunction solar cells
Authors: Andersson L. Mattias , Zhang Fengling , Inganäs Olle
Published: August 2007

Bipolar transport in blends of a copolymer of fluorene, thiophene and electron accepting groups, and the substituted fullerene [6,6]-phenyl-C61-butyric acid methylester have been studied through charge extraction by linearly increasing voltage on solar cells and with field effect transistors. Between 10% and 90% polymer has been used and the results show a clear correlation to solar cell performance. Optimal solar cells comprise 20% polymer and have a power conversion efficiency of 3.5%. The electron mobility is increasing strongly with fullerene content, but is always lower than the hole mobility, thus explaining the low amount of polymer in optimized devices.
Hydration free energies of monovalent ions in transferable intermolecular potential four point fluctuating charge water: An assessment of simulation methodology and force field performance and transferability
Authors: Lee Warren G. , Patel Sandeep
Published: August 2007

Hydration free energies of nonpolarizable monovalent atomic ions in transferable intermolecular potential four point fluctuating charge (TIP4P-FQ) are computed using several commonly employed ion-water force fields including two complete model sets recently developed for use with the simple water model with four sites and Drude polarizability and TIP4P water models. A simulation methodology is presented which incorporates a number of finite-system free energy corrections within the context of constant pressure molecular dynamics simulations employing the Ewald method and periodic boundary conditions. The agreement of the computed free energies and solvation structures with previously reported results for these models in finite droplet systems indicates good transferability of ion force fields from these water models to TIP4Q-FQ even when ion polarizability is neglected. To assess the performance of the ion models in TIP4P-FQ, we compare with consensus values for single-ion hydration free energies arising from recently improved cluster-pair estimates and a reevaluation of commonly cited, experimentally derived single-ion hydration free energies; we couple the observed consistency of these energies with a justification of the cluster-pair approximation in assigning single-ion hydration free energies to advocate the use of these consensus energies as a benchmark set in the parametrization of future ion force fields.
Variations in behavior and condition of a Southern Ocean top predator in relation to
in situ
oceanographic conditions
Authors: Biuw M. , Boehme L. , Guinet C. , Hindell M. , Costa D. , Charrassin J.-B. , Roquet F. , Bailleul F. , Meredith M. , Thorpe S. , Tremblay Y. , McDonald B. , Park Y.-H. , Rintoul S. R. , Bindoff N. , Goebel M. , Crocker D. , Lovell P. , Nicholson J. , Monks F. , Fedak M. A.
Published: August 2007

Responses by marine top predators to environmental variability have previously been almost impossible to observe directly. By using animal-mounted instruments simultaneously recording movements, diving behavior, and
in situ
oceanographic properties, we studied the behavioral and physiological responses of southern elephant seals to spatial environmental variability throughout their circumpolar range. Improved body condition of seals in the Atlantic sector was associated with Circumpolar Deep Water upwelling regions within the Antarctic Circumpolar Current, whereas High-Salinity Shelf Waters or temperature/salinity gradients under winter pack ice were important in the Indian and Pacific sectors. Energetic consequences of these variations could help explain recently observed population trends, showing the usefulness of this approach in examining the sensitivity of top predators to global and regional-scale climate variability.
Structural basis of action for a human ether-a-go-go-related gene 1 potassium channel activator
Authors: Perry Matthew , Sachse Frank B. , Sanguinetti Michael C.
Published: August 2007

Activation of human ether-a-go-go-related gene 1 (hERG1) K
+
channels mediates cardiac action potential repolarization. Drugs that activate hERG1 channels represent a mechanism-based approach for the treatment of long QT syndrome, a disorder of cardiac repolarization associated with ventricular arrhythmia and sudden death. Here, we characterize the mechanisms of action and the molecular determinants for binding of RPR260243 [(3
R
,4
R
)-4-[3-(6-methoxy-quinolin-4-yl)-3-oxo-propyl]-1-[3-(2,3,5-trifluoro-phenyl)-prop-2-ynyl]-piperidine-3-carboxylic acid] (RPR), a recently discovered hERG1 channel activator. Channels were heterologously expressed in
Xenopus laevis
oocytes, and currents were measured by using the two-microelectrode voltage-clamp technique. RPR induced a concentration-dependent slowing in the rate of channel deactivation and enhanced current magnitude by shifting the voltage dependence of inactivation to more positive potentials. This mechanism was confirmed by demonstrating that RPR slowed the rate of deactivation, but did not increase current magnitude of inactivation-deficient mutant channels. The effects of RPR on hERG1 kinetics and magnitude could be simulated by reducing three rate constants in a Markov model of channel gating. Point mutations of specific residues located in the S4–S5 linker or cytoplasmic ends of the S5 and S6 domains greatly attenuated or ablated the effects of 3 μM RPR on deactivation (five residues), inactivation (one residue), or both gating mechanisms (four residues). These findings define a putative binding site for RPR and confirm the importance of an interaction between the S4–S5 linker and the S6 domain in electromechanical coupling of voltage-gated K
+
channels.
Estrogen receptor β is essential for sprouting of nociceptive primary afferents and for morphogenesis and maintenance of the dorsal horn interneurons
Authors: Fan Xiaotang , Kim Hyun-Jin , Warner Margaret , Gustafsson Jan-Åke
Published: August 2007

Estrogen is known to influence pain, but the specific roles of the two estrogen receptors (ERs) in the spinal cord are unknown. In the present study, we have examined the expression of ERα and ERβ in the spinal cord and have looked for defects in pain pathways in ERβ knockout (ERβ
−/−
) mice. In the spinal cords of 10-month-old WT mice, ERβ-positive cells were localized in lamina II, whereas ERα-positive cells were mainly localized in lamina I. In ERβ
−/−
mice, there were higher levels of calcitonin gene-regulated peptide and substance P in spinal cord dorsal horn and isolectin B4 in the dorsal root ganglion. In the superficial layers of the spinal cord, there was a decrease in the number of calretinin (CR)-positive neurons, and in the outer layer II, there was a loss of calbindin-positive interneurons. During embryogenesis, ERβ was first detectable in the spinal cord at embryonic day 13.5 (E13.5), and ERα was first detectable at E15.5. During middle and later embryonic stages, ERβ was abundantly expressed in the superficial layers of the dorsal horn. ERα was also expressed in the dorsal horn but was limited to fewer neurons. Double staining for ERβ and CR showed that, in the superficial dorsal horn of WT neonates [postnatal day 0 (P0)], most CR neurons also expressed ERβ. At this stage, few CR-positive cells were detected in the dorsal horn of ERβ
−/−
mice. Taken together, these findings suggest that, early in embryogenesis, ERβ is involved in dorsal horn morphogenesis and in sensory afferent fiber projections to the dorsal horn and that ERβ is essential for survival of dorsal horn interneurons throughout life.
A pathogenicity island replicon in
Staphylococcus aureus
replicates as an unstable plasmid
Authors: Úbeda Carles , Barry Peter , Penadés José R. , Novick Richard P.
Published: August 2007

The SaPIs are 14- to 17-kb mobile pathogenicity islands in staphylococci that carry genes for superantigen toxins and other virulence factors and are responsible for the toxic shock syndrome and other superantigen-related diseases. They reside at specific chromosomal sites and are induced by certain bacteriophages to initiate an excision-replication-packaging program, resulting in their incorporation into small infective phage-like particles. These are responsible for very high transfer frequencies that often equal and sometimes exceed the plaque-forming titer of the inducing phage. The ability of the SaPIs to replicate autonomously defines them as individual replicons and, like other prokaryotic replicons, they possess replicon-specific initiation functions. In this paper, we report identification of the SaPI replication origin (
ori
) and replication initiation protein (Rep), which has helicase as well as initiation activity. The SaPI
oris
are binding sites for the respective Rep proteins and consist of multiple oligonucleotide repeats in two sets, flanking an AT-rich region that may be the site of initial melting. Plasmids containing the
rep-ori
complex plus an additional gene,
pri
, can replicate autonomously in
Staphylococcus aureus
but are very unstable, probably because of defective segregation.
Integrative genomic and functional analyses reveal neuronal subtype differentiation bias in human embryonic stem cell lines
Authors: Wu Hao , Xu Jun , Pang Zhiping P. , Ge Weihong , Kim Kevin J. , Blanchi Bruno , Chen Caifu , Südhof Thomas C. , Sun Yi E.
Published: August 2007

The self-renewal and differentiation potential of human embryonic stem cells (hESCs) suggests that hESCs could be used for regenerative medicine, especially for restoring neuronal functions in brain diseases. However, the functional properties of neurons derived from hESC are largely unknown. Moreover, because hESCs were derived under diverse conditions, the possibility arises that neurons derived from different hESC lines exhibit distinct properties, but this possibility remains unexplored. To address these issues, we developed a protocol that allows stepwise generation from hESCs of cultures composed of ≈70–80% human neurons that exhibit spontaneous synaptic network activity. Comparison of neurons derived from the well characterized HSF1 and HSF6 hESC lines revealed that HSF1- but not HSF6-derived neurons exhibit forebrain properties. Accordingly, HSF1-derived neurons initially form primarily GABAergic synaptic networks, whereas HSF6-derived neurons initially form glutamatergic networks. microRNA profiling revealed significant expression differences between the two hESC lines, suggesting that microRNAs may influence their distinct differentiation properties. These observations indicate that although both HSF1 and HSF6 hESCs differentiate into functional neurons, the two hESC lines exhibit distinct differentiation potentials, suggesting that they are preprogrammed. Information on hESC line-specific differentiation biases is crucial for neural stem cell therapy and establishment of novel disease models using hESCs.
Economic Science Wars
Authors: Weintraub E. Roy
Published: August 2007

It is not news that the history of economics is disesteemed by most economists. There have been almost annual discussions at professional meetings about the institutional role of the history of economics. Indeed, a conference in 2001 documented the precarious state of the field in North America, and its even more perilous position in the United Kingdom and the Antipodes (Weintraub 2002b). With the exception of Duke University there are no longer any regularly scheduled graduate courses, let alone programs, in the history of economics at any “top” university in North America (Gayer 2002).
How, and for How Long, Did Keynes maintain theTreatiseTheory?
Authors: Hirai Toshiaki
Published: August 2007

Many historians of economic theory have studied how John Maynard Keynes developed his theory fromA Tract on Monetary ReformthroughA Treatise on Money(hereafter theTreatise) toThe General TheoryofEmployment, Interest and Money(hereafter theGeneral TheoryorGT). After the pioneering studies by Moggridge (1973) and Patinkin (1976, 1982), there followed Dimand (1988), Amdeo (1989), Clarke (1988, 1998), Meltzer (1988), Moggridge (1992), Skidelsky (1992), Laidler (1999), and others. This is no wonder, for the Keynesian Revolution remains the most singular phenomenon that economic theory and policy have ever seen. Although the objective of our entire project has been to shed new light on this important and interesting phenomenon, examining and analyzing the processes of theory-building and rebuilding which constitute Keynes's intellectual journey (see Hirai 1997–99), the present paper focuses solely on one chapter in the long story of the transition through his three major works. The very fact of addressing the questions, “How did Keynes maintain the theory developed in theTreatiseafter its publication (October 1930), and for how long?” narrows the period under study to approximately two years which span roughly from October 1930 through October 1932. Our scrutiny will range over the original texts and primary material such as manuscripts, lecture notes, and correspondence produced over this period, and our findings will rest on the meticulous analysis of material of crucial importance for a clear understanding of Keynes's theoretical situation. We will also offer our comments on the earlier efforts insofar as they relate to the period in question.
Transcribing the Tableau Économique: Input-Output Analysis à la Quesnay
Authors: Steenge Albert E. , van den Berg Richard
Published: August 2007

Since its publication in 1955, Almarin Phillips' article “The Tableau Économique as a Simple Leontief Model” has inspired an interesting line of interpretation of the arithmetical schemes presented two centuries earlier by François Quesnay. Subsequent attempts to represent the Tableaux économiques in the form of Input-Output transcriptions by Shlomo Maital (1972), Bernhard Korte (1972), Tibor Barna (1975), and Paul Samuelson (1986), among others, have underlined the brilliance of the French doctor's formal conception of the economy as a reproductive system.