bluuebunny/crossref_metadata_2025 huggingface dataset:
A flexible approach to modeling the storm time Region 2 and magnetopause currents
Authors: Ontiveros P. A. , Naehr S. M. , Toffoletto F. R. , Hill T. W.
Published: September 2006

We present flexible approaches to modeling the Region 2 (R2) Birkeland current system with the associated partial ring current (PRC) and the Chapman‐Ferraro currents for arbitrarily shaped magnetopauses. The R2 field‐aligned current sheet and the PRC are constructed with an array of overlapping conical diffuse current segments. The dawnside R2 current is connected to the duskside R2 current azimuthally in the equatorial plane, forming a spread‐out PRC. The Chapman‐Ferraro shielding field due to an arbitrary magnetopause shape (on the basis of empirical approximations) is derived as a linear combination of spherical harmonics and image dipoles by a least squares minimization. We generalize the Rice Field Model, a modular open field model, to include the effects of these current systems, which are important in the storm time magnetosphere. We demonstrate the feasibility and flexibility of these techniques by modeling a simple R2 Birkeland current and PRC system.
Active diagnostic of the eigenmode formation in the ion-cyclotron frequency range in the GAMMA10 central cell
Authors: Yamaguchi Y. , Ichimura M. , Higaki H. , Kakimoto S. , Nakagome K. , Nemoto K. , Katano M. , Nakajima H. , Fukuyama A. , Cho T.
Published: September 2006

A wide-band radio-frequency (rf) probe system was constructed for the active diagnostic of the eigenmode formations in the ion-cyclotron range of frequency (ICRF) in GAMMA10. An antenna was installed in the peripheral region in the central cell. The low power rf pulse with the frequency sweep is applied to the antenna. The waves excited in the plasma are detected with a magnetic probe. The excitation of eigenmodes is described by using the antenna-plasma-probe transfer function. The transfer function can be obtained from the antenna current signal and the magnetic probe signal. When the real and imaginary parts of the transfer function are plotted on the complex plane, the resultant curves are approximately circular, indicating an eigenmode formation. The results of the measurement show that several eigenmodes can be excited in the present experimental condition.
Measurement of plug potential bounce ion in the tandem mirror GAMMA 10
Authors: Miyata Y. , Ishii K. , Kojima A. , Fujimoto S. , Yamaguchi T. , Kaidou N. , Kakiuchi H. , Cho T.
Published: September 2006

The bounced ion by the plug potential is quite essential in the tandem mirror experiment. In order to directly measure the plug potential (PP) bounce ion, we have constructed the charge exchange bounce ion analyzer located near the inner mirror throat of the plug/barrier cell, by which both energy and pitch angle of the charge exchanged neutral particle caused by the PP bounce ion were simultaneously measured. The PP bounce ion was successfully assigned by selection of the pitch angle and the energy of the bounce ions during plugging. These data are useful for study of the radial diffusion of the bounce ion.
Data acquisition ATCA system for neutron and gamma-rays spectrometries
Authors: Pereira R. , Fernandes A. G. , Sousa J. , Varandas C. A. F.
Published: September 2006

Digital pulse processing (DPP) systems are known to have better performance than analog ones for neutron and/or gamma-ray pulses. DPP can synthesize almost any pulse response shape without the associated signal degradation which happens in a complex analog path. Measuring techniques involving detectors/spectrometers for fusion diagnostics rely on real-time algorithms, implemented in field programmable gate array (FPGA), for pulse height analysis, pulse shape discrimination, and pileup rejection of digitized pulses in real time for reduced data throughput, monitoring, and control. This article describes a data acquisition system for real-time pulse analysis based on ATCA and contains a 6 GFLPOS i×86-based control unit and a number of transient recorder (TR) modules interconnected through PCI Express links. Each TR module features (i) eight channels of 12bit resolution with accuracy equal or higher than 10bits, (ii) 200Msamples∕s of sampling rate achieving 400Msamples∕s in an interleaved architecture, (iii) 2 or 4Gbytes of local memory, and (iv) two field FPGAs able to perform real-time processing algorithms.
Progress on the motional Stark effect with laser-induced fluorescence diagnostic (invited)
Authors: Foley E. L. , Levinton F. M.
Published: September 2006

The motional Stark effect with laser-induced fluorescence (MSE-LIF) diagnostic is presently under development as a new technique for measuring magnetic field pitch angle and magnitude in plasmas in a wide range of conditions. The technique is based on the observation of LIF from the set of H-alpha transitions in a diagnostic hydrogen neutral beam. As the beam passes at a high velocity through a background magnetic field, the H-alpha emission is split and polarized in a way that is dependent on the magnetic field. The magnitude can be determined from the line splitting and the direction from the polarization orientation. This paper will describe the principle of the technique and report on the present status, including the successful measurement and interpretation of an LIF enhancement phenomenon. The LIF signal from a 30kV beam in a background of neutral gas was found to be enhanced, and the fine-structure line amplitudes were seen to vary significantly with an applied perpendicular magnetic field of 0–0.01T. MSE-LIF for plasmas in the intermediate field range of greater than 0.1T, and potential advantages of MSE-LIF will also be covered.
Fast collimated neutron flux measurement using stilbene scintillator and flashy analog-to-digital converter in JT-60U
Authors: Ishikawa M. , Itoga T. , Okuji T. , Nakhostin M. , Shinohara K. , Hayashi T. , Sukegawa A. , Baba M. , Nishitani T.
Published: September 2006

A line-integrated neutron emission profile is routinely measured using the radial neutron collimator system in JT-60U tokamak. Stilbene neuron detectors (SNDs), which combine a stilbene organic crystal scintillation detector (SD) with an analog neutron-gamma pulse shape discrimination (PSD) circuit, have been used to measure collimated neutron flux. Although the SND has many advantages as a neutron detector, the maximum count rate is limited up to ∼1×105counts∕s due to the analog PSD circuit. To overcome this issue, a digital signal processing system (DSPS) using a flash analog-to-digital converter (Acqiris DC252, 8GHz, 10bits) has been developed at Cyclotron and Radioisotope Center in Tohoku University. In this system anode signals from photomultiplier of the SD are directory stored and digitized. Then, the PSD between neutrons and gamma rays is performed using software. The DSPS has been installed in the vertical neutron collimator system in JT-60U and applied to deuterium experiments. It is confirmed that the PSD is sufficiently performed and collimated neutron flux is successfully measured with count rate up to ∼5×105counts∕s without the effect of pileup of detected pulses. The performance of the DSPS as a neutron detector, which supersedes the SND, is demonstrated.
Fabrication details, calibrations, and installation activities of magnetic diagnostics for Korea Superconducting Tokamak Advanced Research
Authors: Lee S. G. , Bak J. G.
Published: September 2006

Many magnetic diagnostics were fabricated and some of them were calibrated and installed in the Korea Superconducting Tokamak Advanced Research device. Fabrication details and results from the calibrations and installation activities are presented.
Diagnosis of ignition failure modes with 1MJ capsule-Hohlraum designs
Authors: Bradley P. A. , Wilson D. C. , Delamater N. D. , Douglas M. R.
Published: September 2006

At Los Alamos, we have been working on two-dimensional capsule-Hohlraum implosion calculations for the NIF that utilize a laser drive pulse that peaks at ∼300eV and uses about 1MJ of laser energy. We use a 0.3at.% uniformly Cu doped beryllium ablator capsule that has an inner ice radius of 753μm, inner ablator radius of 825μm, and an outer ablator radius of 1000μm. Our Hohlraum has a diameter of 5.02mm and a length of 8.56mm. We use a Hohlraum gas fill density of 1.3mg∕cm3 and obtain ignition with yields up to 9.8MJ, but we also have some failures due to bad shock timing or different pointing positions of the inner and outer laser cones. We describe the salient features of our implosions and show postprocessed diagnostic signatures from x-ray and neutron images, along with reaction history plots to show how we can diagnose “failures” and how to correct for them based on these diagnostics.
Complex morphology of laser-induced bulk damage in K2H(2−x)DxPO4 crystals
Authors: Carr C. W. , Feit M. D. , Johnson M. A. , Rubenchik A. M.
Published: September 2006

We present a detailed study of the morphology of laser-induced bulk damage in K2H(2−x)DxPO4 crystals. We see three distinct regions of the internal damage sites: a rubble filled core, a shell that has probably been melted and compacted, and a larger outer region of slightly modified shocked material. The nature of these regions is important for understanding the impact of laser-induced damage on light scattering, which can be significant for high-power laser operation. We propose a simple model to explain the morphology and light scattering we observe.
Capillary-based, high-pressure chamber for fluorescence microscopy imaging
Authors: Raber Erica C. , Dudley Jonathan A. , Salerno Michael , Urayama Paul
Published: September 2006

We present a high-pressure chamber suitable for the fluorescence microscopy imaging of cellular systems, consisting of a quartz capillary attached to high-pressure tubing with the capillary walls acting as the optical window and mechanical support. The chamber withstands pressures up to 1000atm, spanning most of the biosphere’s pressure range. We validate the chamber for high-pressure studies by using a pH-sensitive fluorophore to sense the pressure-induced acidification of a phosphate buffer. Next, because the capillary walls result in image aberrations, we demonstrate the ability to use spatial deconvolution to improve image resolution. Capillary wall thicknesses are less than 0.5mm, making the chamber compatible with high-numerical-aperture optics.
Measurement of global instability of compact torus by three-dimensional tomography
Authors: Kawamori E. , Sumikawa T. , Ono Y. , Balandin A.
Published: September 2006

The new three-dimensional tomography reconstruction system based on the novel scheme suggested by Balandin et al. [Eur. Phys. J. D 14, 97 (2001)] was developed for a powerful monitor of compact torus (CT) plasma using 16 two-dimensional (2D) projections of visible light. This system can obtain many (16) 2D projections with one detector (a framing camera) by use of light collecting optical probes and optical fiber bundles. Sixteen optical probes, which measure emission of plasmas, were installed on a sphere outside the separatrix of CT inside the vacuum vessel. Optical radiation was collected by the wide-angle lenses attached to the optical probes and transported by the fiber bundles to a high-speed framing camera. The line-integrated 2D images measured with this system were inverted to local emissivity using the software. The n=1 (n: toroidal mode number) tilt motion of field reversed configuration plasma was successfully measured.
Three-channel amplifier for high-sensitivity voltage noise measurements
Authors: Giusi Gino , Crupi Felice , Ciofi Carmine , Pace Calogero
Published: September 2006

This article describes a method for voltage noise measurements with a sensitivity superior to that of conventional methods. This is obtained by resorting to an original three-channel amplifier configuration and by following a four-step measurement procedure. A comparative analysis of this method and the conventional cross-correlation technique is presented. SPICE simulations and noise measurements performed on a prototype circuit demonstrate the validity of the proposed approach.
Nonlinearity of resistive impurity effects on van der Pauw measurements
Authors: Koon D. W.
Published: September 2006

The dependence of van der Pauw resistivity measurements on local macroscopic inhomogeneities is shown to be nonlinear. A resistor grid network models a square laminar specimen, enabling the investigation of both positive and negative local perturbations in resistivity. The effect of inhomogeneity is measured both experimentally, for an 11×11 grid, and computationally, for both 11×11 and 101×101 grids. The maximum “shortlike” perturbation produces 3.1±0.2 times the effect predicted by the linear approximation, regardless of its position within the specimen, while all “openlike” perturbations produce a smaller effect than predicted. An empirical nonlinear correction for f(x,y) is presented which provides excellent fit over the entire range of both positive and negative perturbations for the entire specimen.
Development of mirror manipulator for hard-x-ray nanofocusing at sub-50-nm level
Authors: Matsuyama S. , Mimura H. , Yumoto H. , Hara H. , Yamamura K. , Sano Y. , Endo K. , Mori Y. , Yabashi M. , Nishino Y. , Tamasaku K. , Ishikawa T. , Yamauchi K.
Published: September 2006

X-ray focusing using Kirkpatrick-Baez (KB) mirrors is promising owing to their capability of highly efficient and energy-tunable focusing. We report the development of a mirror manipulator which enables KB mirror alignment with a high degree of accuracy. Mirror alignment tolerances were estimated using two types of simulators. On the basis of the simulation results, the mirror manipulator was developed to achieve an optimum KB mirror setup. As a result of focusing tests at BL29XUL of SPring-8, the beam size of 48×36nm2 (V×H) was achieved in the full width at half maximum at an x-ray energy of 15keV. Spatial resolution tests showed that a scanning x-ray microscope equipped with the KB focusing system could resolve line-and-space patterns of 80nm linewidth in a high visibility of 60%.
Semiconductor laser based, injection locking maintaining broad linewidth generated by a direct current modulation of a master laser
Authors: Sasaki Kohta , Yoneyama Toshio , Nakamura Takahiro , Sato Shunichi , Takeyama Akinori
Published: September 2006

Semiconductor laser based, injection locking was performed for efficient excitation of subjects. The linewidth of the master laser was extended to 380MHz by using a frequency modulation technique through a direct current modulation. By the injection locking technique with a broad-area semiconductor laser, the frequency modulated input was amplified to 610mW, faithfully maintaining the broadened linewidth and the spectral shape. This result means that a compact high power laser system is possible with broad linewidth that is precisely controllable.
Simple interferometer for space and time resolved density measurements of laser produced plasmas
Authors: Prasad Y. B. S. R. , Naik P. A. , Kumar A. , Gupta P. D.
Published: September 2006

A lateral shearing interferometer has been set up and coupled to an S-20 optical streak camera to obtain time resolved spatial electron density profiles of laser produced plasmas in a single shot. The electron density profiles are recorded with a temporal resolution of 70ps for a continuous time duration of 15ns. Performance of the system is demonstrated by recording temporal evolution of one dimensional density profiles of an expanding laser produced aluminum plasma. The system can be especially useful in characterization of expanding plasma for thin film deposition using laser ablated plumes.
Carrier mobility of organic thin films using lateral electrode structure with optical slits
Authors: Kuwahara Atsushi , Naka Shigeki , Okada Hiroyuki , Onnagawa Hiroyoshi
Published: September 2006

The authors have studied the carrier mobilities of organic thin films using a time-of-flight (TOF) technique with lateral electrode structures and optical slits. For a triphenylamine derivative (TPD), which is a typical hole transport material, the obtained mobility was similar to the results of the conventional TOF measurement using a sandwiched structure with a thick film. Moreover, they have succeeded in evaluating the carrier mobility of an iridium complex [Ir(ppy)3], which is a phosphorescent material, and hole mobility on the order of 10−3cm2∕Vs was obtained. This technique, which has the merits of free alignment of excitation light and no need for the preparation of a thick sample, is effective for the evaluation of carrier mobilities in thin organic materials.
Efficient and accurate solvation energy calculation from polarizable continuum models
Authors: Lin Shiang-Tai , Hsieh Chieh-Ming
Published: September 2006

A new approach is proposed to enhance the efficiency and accuracy for calculation of the long-range electrostatic interaction from implicit solvation models, i.e., the polarizable continuum model (PCM) and its variants, conductorlike PCM/conductorlike screening model and integral equation formalism PCM. In these methods the solvent electrostatics effects are represented by a set of discrete apparent charges distributed on tesserae of the molecular cavity surface embedding the solute. In principle, the accuracy of these methods is improved if the cavity surface is tessellated to finer tesserae; however, the computational time is increased rapidly. We show that such undesired dependency between accuracy and efficiency is a result of the inaccurate treatment of the apparent charge self-contribution to the potential and/or electric field. By taking into account the full effects due to the size and curvature of the segment occupied by each apparent charge, the error in calculated electrostatic solvation free energy is essentially zero for ions (point charge at the center of a sphere) regardless of the degree of tessellation used. For molecules where gradient of apparent charge density is nonzero at the cavity surface, we propose a multiple-sampling technique which significantly lowers the calculated error compared to the original PCM methods, especially when very few numbers of tesserae are used.
Measurements of nanofluid viscosity and its implications for thermal applications
Authors: Prasher Ravi , Song David , Wang Jinlin , Phelan Patrick
Published: September 2006

Experimental results on the viscosity of alumina-based nanofluids are reported for various shear rates, temperature, nanoparticle diameter, and nanoparticle volume fraction. From the data it seems that the increase in the nanofluid viscosity is higher than the enhancement in the thermal conductivity as reported in the literature. It is shown, however, that the viscosity has to be increased by more than a factor of 4—relative to the increase in thermal conductivity—to make the nanofluid thermal performance worse than that of the base fluid.
Magnetic properties of layered nanorings
Authors: Escrig J. , Landeros P. , Altbir D. , Bahiana M. , d’Albuquerque e Castro J.
Published: September 2006

The magnetic structure of nanorings consisting of alternate layers of magnetic and nonmagnetic materials is investigated as a function of their geometry. Phase diagrams giving the relative stability of characteristic internal magnetic configurations of the rings are obtained. Attention is focused on the condition for occurrence of the vortex configurations, in which case the layered structure might be used to produce magnetoresistive random access memories.
Optically induced linear electro-optic effects in ytterbium-doped strontium yttrium borate Sr3Y(BO3)3:Yb nanocrystallites incorporated into polymer matrices
Authors: Ebothé J. , Kityk I. V. , Kisielewski J. , Lukasiewicz T. , Diduszko R. , Majchrowski A.
Published: September 2006

Yb-doped Sr3Y(BO3)3 nanocrystallites incorporated into polymethyl methacrylate matrices (4.5% by weight) were optically treated by coherent picosecond laser pulses at 1.34 and 0.67μm. This composite exhibits a large effective electro-optic coefficient (up to 6.2pm∕V at 1040nm wavelength). Decrease of the nanocrystallite size and increase of the Yb content lead to substantial enhancement of the effective electro-optic coefficient. For nanocrystallite sizes equal to about 5nm, the coefficient increases from 2.2pm∕V (8% of Yb) up to 6.2pm∕V (20% of Yb). This material appears thus promising in application for the optically operated modulators.
Effects of metal penetration into organic semiconductors on the electrical properties of organic thin film transistors
Authors: Cho Jeong Ho , Kim Do Hwan , Jang Yunseok , Lee Wi Hyoung , Ihm Kyuwook , Han Jin-Hee , Chung Sukmin , Cho Kilwon
Published: September 2006

To investigate the effects of metal penetration into organic semiconductors on the electrical properties of organic thin film transistors, gold was deposited onto pentacene films at various deposition rates. The sharp interface between the gold electrode and the pentacene film that results from a fast deposition rate was found to produce lower contact resistance and an increase in the field-effect mobility.
Pockel’s coefficient enhancement of poled electro-optic polymers with a hybrid organic-inorganic sol-gel cladding layer
Authors: DeRose Christopher T. , Enami Y. , Loychik C. , Norwood R. A. , Mathine D. , Fallahi M. , Peyghambarian N. , Luo J. D. , Jen A. K.-Y. , Kathaperumal M. , Yamamoto M.
Published: September 2006

Ultraefficient poling of electro-optic polymers is reported using an organically modified sol-gel cladding layer. This poling technique has resulted in a Pockel’s coefficient enhancement of up to a factor of 2.5, going from 26pm∕V when poled without a sol-gel cladding to 65pm∕V when optimally poled with a sol-gel cladding. The poling process directly applies to a previously reported hybrid electro-optic polymer/sol-gel waveguide modulator and may have applications in other poled polymer based devices.
Tuning of the electronic properties of self-assembled InAs∕InP(001) quantum dots using grown-in defect mediated intermixing
Authors: Dion C. , Poole P. J. , Raymond S. , Desjardins P. , Schiettekatte F.
Published: September 2006

This paper examines the influence of rapid thermal annealing on the photoluminescence spectra of self-assembled InAs∕InP(001) quantum dots capped with 760nm InP deposited at a reduced temperature. The capping layer contained a large concentration of point defects that can promote interdiffusion upon annealing. The onset temperature for measurable blueshift in the emission spectra was found to be ∼600°C whereas shifts of 270meV were obtained after annealing at 750°C for 300s. Gradual etching of the InP capping layer enabled to progressively quench energy shifts upon annealing, a promising result for spatially selective emission tuning.
Low temperature refrigeration by electron emission in a crossed-field gap
Authors: Wu L. , Ang L. K.
Published: September 2006

A method of refrigeration using thermal-field electron emission from nanoscale emitters of arbitrary work function in a vacuum crossed-field gap is proposed. With an external crossed magnetic field, an additional potential barrier near the anode is created to restrict the tunneling of low-energy electrons (below the Fermi energy) and thus provids a versatile cooling capability from 300 down to 10K. Optimal conditions are determined numerically and analytically, which give local cooling power densities (per emitter) of about 600kW∕cm2 (at 300K), 2.7kW∕cm2 (at 50K), and 20W∕cm2 (at 10K).
In situ observation of amorphous-amorphous apparently first-order phase transition in zeolites
Authors: Ovsyuk Nikolay , Goryainov Sergei
Published: September 2006

In this letter, the authors present the observation of the phase transition between low-density amorphous (LDA) and high-density amorphous (HDA) zeolites using a high pressure Raman spectroscopy. It is found that this transition is apparently of the first order and occurs with a silicon coordination rise. It is shown that the Raman spectra of the LDA-HDA phase transitions in zeolites and in silicon are almost identical, suggesting a generality of amorphous-amorphous transformations both in simple substances and in complex polyatomic materials with tetrahedral configurations.
Terahertz parametric gain in semiconductor superlattices in the absence of electric domains
Authors: Hyart Timo , Alexeeva Natalia V. , Leppänen Ahti , Alekseev Kirill N.
Published: September 2006

The authors theoretically show that conditions for terahertz gain and conditions for formation of destructive electric domains in semiconductor superlattices are fairly different in the case of parametric generation and amplification. Action of an unbiased high-frequency electric field on a superlattice causes a periodic variation of energy and effective mass of miniband electrons. This parametric effect can result in a significant gain at some even harmonic of the pump frequency without the formation of electric domains and corruption from pump harmonics.
Superellipsoids: A unified analytical description of the geometry of nanoscale second-phase particles of any shape
Authors: Sobchenko Ihor , Pesicka Josef , Baither Dietmar , Reichelt Rudolf , Nembach Eckhard
Published: September 2006

An equation for the analytical description of the geometry of nanoscale second-phase particles of any shape (spheres, cubes, plates, cylinders, and fibers) is presented: they are elegantly described as superellipsoids. The respective equation involves four parameters, which can be experimentally derived from just one micrograph.
Terahertz transmission characteristics of high-mobility GaAs and InAs two-dimensional-electron-gas systems
Authors: Kabir N. A. , Yoon Y. , Knab J. R. , Chen J.-Y. , Markelz A. G. , Reno J. L. , Sadofyev Y. , Johnson S. , Zhang Y.-H. , Bird J. P.
Published: September 2006

Frequency-dependent complex conductivity of high-mobility GaAs and InAs two-dimensional-electron-gas (2DEG) systems is studied by terahertz time domain spectroscopy. Determining the momentum relaxation time from a Drude model, the authors find a lower value than that from dc measurements, particularly at high frequencies/low temperatures. These deviations are consistent with the ratio τt∕τq, where τq is the full scattering time. This suggests that small-angle scattering leads to weaker heating of 2DEGs at low temperatures than expected from dc mobility.
Stretching of long DNA molecules in the microvortex induced by laser and ac electric field
Authors: Nakano Michihiko , Kurita Hirofumi , Komatsu Jun , Mizuno Akira , Katsura Shinji
Published: September 2006

A microvortex is generated around an infrared laser focus where an intense ac electric field is applied. The authors used this optoelectrostatic microvortex for stretching individual long DNAs. When λ-or T4-phage DNA molecules were introduced into the optoelectrostatic microvortex, they were stretched around the laser focus. In addition, especially for longer T4 DNA molecules, it was possible to keep it in stretching form for more than 30s. Using this method, length of DNA molecules can be measured without fixing to a substrate. This method can be applied to DNA molecules longer than about 10μm.
Interplay between s-d exchange interaction and Rashba effect: Spin-polarized transport
Authors: Yang W. , Chang Kai , Wu X. G. , Zheng H. Z. , Peeters F. M.
Published: September 2006

The authors investigate the spin-polarized transport properties of a two-dimensional electron gas in a n-type diluted magnetic narrow gap semiconductor quantum well subjected to perpendicular magnetic and electric fields. Interesting beating patterns in the magnetoresistance are found which can be tuned significantly by varying the electric field. A resonant enhancement of spin-polarized current is found which is induced by the competition between the s-d exchange interaction and the Rashba effect [Y. A. Bychkov and E. I. Rashba, J. Phys. C 17, 6039 (1984)].
In situ electric field simulation in metal/insulator/metal capacitors
Authors: Gaillard Nicolas , Pinzelli Luc , Gros-Jean Mickael , Bsiesy Ahmad
Published: September 2006

The authors report in this letter the effect of interface topography on metal/insulator/metal (MIM) capacitor electrical properties. This analysis was carried out by numerical simulations of the electric field established in a MIM structure with a 45nm thick Ta2O5 film. The metal/insulator interface profiles have been extracted from transmission electron microscopy micrographs of a fully integrated device. This in situ approach allows direct comparison between electrical properties and numerical simulations performed on the same device. Results show that the bottom electrode’s surface roughness induces a large electric field increase at the interface which could explain MIM capacitor’s asymmetrical electrical behavior.
The Influence of a Horizontal Wall on the Motion of a Falling Oil Drop
Authors: Hoper VD , Grant AM
Published: September 2006

A study has been made of the effect of a horizontal wall on the motion of oil drops of radii ranging from 5 µ to 15 µ falling in air. The following conclusions were reached.
Provided that z/a, the ratio of the distance z of the oil drop from the wall to its radius a, is greater than 20, the resistance W to its motion is satisfied by the formula given by Lorentz, namely :
W = 6πηav (1 + 9/8 a/z).
For z/a ranging from 2 to 500, the coefficient of a/z may be expressed empirically
in the form
f(z/a) = k1 + k2 a/z
where k1 = 1.08 ± 0.05 and k2 = 1.4 ± 1.0.
Atmospheric Pressure Changes: The Importance of Deviations from the Balanced (Gradient) Wind
Authors: Priestley CHB
Published: September 2006

The paper comprises a discussion of the effect of deviations from the instantaneously balanced, or gradient, wind on the translation and development of the surface pressure field. The deviation is shown to consist primarily of two components, which are associated respectively with vertical motion and horizontal acceleration in the air trajectory.
With certain types of pressure system, the first of the above components makes a contribution towards translation of the system. But its major role is in maintenance of the system against the dissipating effect of surface friction. The part played by this component in the intensification of anticyclones, end the formation of secondary depressions and cold pools is discussed : in particular, these common types of development are linked with vertical motion at the tropopause and in the stratosphere. The level just below the tropopause is shown to be crucial in the study of anticyclogenesis. The collapse of an anticyclone under excessive surface heating, the formation of "heat lows", and the pressure rise associated with convectional squalls are also attributed to this deviation.
By means of the deviation associated with horizontal acceleration, the changes in pressure force experienced by a moving element give rise to compensating flows which restrict any rapid local changes in surface pressure. In conjunction with the control exercised by the balanced wind(l), this accounts for the remarkable conservatism of surface pressure in face of the large convergence or divergence which atmospheriic motion appears to imply.
Apart from its controlling influence, the contribution from the horizontal acceleration increases with increasing asymmetry of the system. The eastward thrust of sharp ridges of high pressure is attributable to this deviation.
Studies on the Lignin of Eucalyptus regnans I. Thiolignin
Authors: Lahey FN , Merewether JWT
Published: September 2006

By pulping Eucalyptus regnans by the kraft process, acidifying the black liquor, and fractionating the product, a thiolignin has been prepared in a pure state.
Thiolignin reacts with diazomethane to yield a trimethyl derivative, and with dimethyl sulphate to yield a hexamethyl derivative.
Thiolignin, trimethylthiolignin, and hexamethylthiolignin react with acetic anhydride in pyridine to yield respectively hepta-, tetra-, and mono-acetyl derivatives.
The data obtained are consistent with the formula C52H35O10.(OCH3)9.C(CH3)OH.(CHOH)3.CH = C(OH).OH.SH.
Temperature Dependence of the Dielectric Properties of Long-Chain Aliphatic Alcohols in the Solid State
Authors: Dryden JS
Published: September 2006

The dielectric properties of three primary
and three secondary long-chain aliphatic alcohols have been investigated within
the temperature range of -20 to 70 �C. The experimental results are discussed
in relation to the theory of Sack on dielectric absorption in linear polar
chains and to the conclusions reached in earlier papers on the dielectric
properties of these compounds. The apparent activation energies in the primary
alcohols are approximately three times those in the secondary alcohols. This indicates
either different mechanisms of absorption in the two types of alcohols or, if
the mechanisms are the same, significant differences in the energy barriers
involved.
Dielectric Absorption and D.C. Conductivity in n-primary Alcohols
Authors: Hamon BV , Meakins RJ
Published: September 2006

A previous publication described some
electrical properties of crystalline n-primary alcohols of 16 to 26 carbon
atoms. The present paper deals with an extension of the work to the lower
homologues down to n-octyl alcohol, and includes the results of measurements on
both the liquid and crystalline materials. To enable their more extensive
investigation, the frequency range of measurement has been extended down to 10-4
c/s. by the use of D.C. methods.The
alcohols of the present series resemble the higher homologues in giving two
regions of dielectric absorption which overlap to an increasing extent with
decreasing molecular weight. The absorption region at lower frequencies merges
with the loss due to D.C. conductivity, the latter being much larger than for
other long-chain compounds so far investigated.A
feature of the results is the variation in the electrical properties of
different samples of the same alcohol. This may be due to variations in the
relative proportions of α- and β- crystalline modifications present
in different samples.The
results suggest that the absorption and the D.C. conductivity both depend on
the presence in the crystals of hydrogen-bond chains. The high frequency
absorption appears to be related to that in secondary alcohols and is probably
associated with reversal of the hydrogen-bond chains by cooperative rotation of
the hydroxyl group about the C-O bonds. The latter mechanism, together with
proton transition, could lead to migration of the protons, and this may account
for the D.C. conductivity. The absorption at low frequencies is attributed to a
Maxwell-Wagner type of mechanism resulting from the situation of the conducting
hydrogen-bond chains in a non-conducting matrix.
Studies on the Lignin of Eucalyptus regnans F. Muell. V. Ethanol Lignin
Authors: Merewether JWT
Published: September 2006

Lignin has been isolated from Eucalyptus
regnans F. Muell. by refluxing with ethanolic hydrogen chloride, and the
product separated into an ether-insoluble ethanol lignin-A and an ether-soluble
ethanol lignin-B. Ethanol lignin-A has an equivalent weight of 1400 and, on the
assumption that the molecular weight is of this order, contains two ethoxyl and
nine methoxyl groups. Acetic anhydride and benzoyl chloride in pyridine yield
respectively a hepta-acetate and heptabenzoate, while benzoyl chloride in aqueous
alkali yields a pentabenzoate. Diazomethane yields a dimethyl derivative which
gives a penta-acetate on acetylation. Schotten-Baumann benzoylation of this
dimethyl derivative yields a dibenzoate. Two carbonyl groups are present, as
shorn by the formation of a bisphenylhydrazone and a
bis-p-nitrophenylhydrazone. The data are consistent with the formula C59H38O10(OC2H5)2(OCH3)9(OH)7.
Alkaloids of Australian Strychnos species. I. Constituents of S. lucida R.Br. and S. psilosperma F.Muell
Authors: Anet FAL , Hughes GK , Ritchie E
Published: September 2006

From the fruits of Strychnos lucida R.Br,
were isolated loganin (1.1 per cent.) which appears to be confined to the pulp,
strychnine (0.1 per cent.), brucine (1.3 per cent.), and an unresolved glassy
alkaloidal mixture (0.5 per cent.). " Lucidine-S " could not be
separated. The leaves of 8. psilosperma F. Muell. contain about 1.1 per cent.
total alkaloid from which two new alkaloids, strychnospermine and
spermostrychnine, were isolated. Structural formulae for these are suggested on
biogenetic grounds. The triterpene alcohol, germanicol, was also isolated from
S. psilosperma leaves.
The Chemistry of 5-Oxodihydroisoxazoles. XVI. A New Synthesis of Pyrroles, Furans, Thiophens and Their Benzo Analogues
Authors: Prager RH , Williams CM
Published: September 2006

Ethyl 5-oxo-2-phenyl-2,5-dihydroisoxazole-4-carboxylate (2) was photolysed at 300 nm in the presence of phenols, enols, anilines, enamines , aryl thiols and thioenols affording enamines. Treatment of these enamines with Lewis or protic acids gives the respective benzo and five- membered ring systems.
Hormonal activity of AIMP1/p43 for glucose homeostasis
Authors: Park Sang Gyu , Kang Young Sun , Kim Jin Young , Lee Chang Seok , Ko Young Gyu , Lee Woo Je , Lee Ki-Up , Yeom Young Il , Kim Sunghoon
Published: September 2006

AIMP1/p43 is known as a cytokine working in the control of angiogenesis, inflammation, and wound healing. Here we report its enrichment in pancreatic α cells and glucagon-like hormonal activity. AIMP1 is secreted from the pancreas upon glucose starvation. Exogenous infusion of AIMP1 increased plasma levels of glucose, glucagon, and fatty acid, and AIMP1-deficient mice showed reduced plasma glucose levels compared with the wild-type mice under fasting conditions. Thus, AIMP1 plays a glucagon-like role in glucose homeostasis.
Legume genome evolution viewed through the
Medicago truncatula
and
Lotus japonicus
genomes
Authors: Cannon Steven B. , Sterck Lieven , Rombauts Stephane , Sato Shusei , Cheung Foo , Gouzy Jérôme , Wang Xiaohong , Mudge Joann , Vasdewani Jayprakash , Schiex Thomas , Spannagl Manuel , Monaghan Erin , Nicholson Christine , Humphray Sean J. , Schoof Heiko , Mayer Klaus F. X. , Rogers Jane , Quétier Francis , Oldroyd Giles E. , Debellé Frédéric , Cook Douglas R. , Retzel Ernest F. , Roe Bruce A. , Town Christopher D. , Tabata Satoshi , Van de Peer Yves , Young Nevin D.
Published: September 2006

Genome sequencing of the model legumes,
Medicago truncatula
and
Lotus japonicus
, provides an opportunity for large-scale sequence-based comparison of two genomes in the same plant family. Here we report synteny comparisons between these species, including details about chromosome relationships, large-scale synteny blocks, microsynteny within blocks, and genome regions lacking clear correspondence. The
Lotus
and
Medicago
genomes share a minimum of 10 large-scale synteny blocks, each with substantial collinearity and frequently extending the length of whole chromosome arms. The proportion of genes syntenic and collinear within each synteny block is relatively homogeneous.
Medicago–Lotus
comparisons also indicate similar and largely homogeneous gene densities, although gene-containing regions in
Mt
occupy 20–30% more space than
Lj
counterparts, primarily because of larger numbers of
Mt
retrotransposons. Because the interpretation of genome comparisons is complicated by large-scale genome duplications, we describe synteny, synonymous substitutions and phylogenetic analyses to identify and date a probable whole-genome duplication event. There is no direct evidence for any recent large-scale genome duplication in either
Medicago
or
Lotus
but instead a duplication predating speciation. Phylogenetic comparisons place this duplication within the Rosid I clade, clearly after the split between legumes and Salicaceae (poplar).
Measurement of the mechanical properties of isolated tectorial membrane using atomic force microscopy
Authors: Gueta Rachel , Barlam David , Shneck Roni Z. , Rousso Itay
Published: September 2006

The tectorial membrane (TM) is an extracellular matrix situated over the sensory cells of the cochlea. Its strategic location, together with the results of recent TM-specific mutation studies, suggests that it has an important role in the mechanism by which the cochlea transduces mechanical energy into neural excitation. A detailed characterization of TM mechanical properties is fundamental to understanding its role in cochlear mechanics. In this work, the mechanical properties of the TM are characterized in the radial and longitudinal directions using nano- and microindentation experiments conducted by using atomic force spectroscopy. We find that the stiffness in the main body region and in the spiral limbus attachment zone does not change significantly along the length of the cochlea. The main body of the TM is the softest region, whereas the spiral limbus attachment zone is stiffer, with the two areas having averaged Young's modulus values of 37 ± 3 and 135 ± 14 kPa, respectively. By contrast, we find that the stiffness of the TM in the region above the outer hair cells (OHCs) increases by one order of magnitude in the longitudinal direction, from 24 ± 4 kPa in the apical region to 210 ± 15 kPa at the basilar end of the TM. Scanning electron microscopy analysis shows differences in the collagen fiber arrangements in the OHC zone of the TM that correspond to the observed variations in mechanical properties. The longitudinal increase in TM stiffness is similar to that found for the OHC stereocilia, which supports the existence of mechanical coupling between these two structures.
The ferroelectric and cubic phases in BaTiO
3
ferroelectrics are also antiferroelectric
Authors: Zhang Qingsong , Cagin Tahir , Goddard William A.
Published: September 2006

Using quantum mechanics (QM, Density Functional Theory) we show that all four phases of barium titanate (BaTiO
3
) have local Ti distortions toward 〈111〉 (an octahedral face). The stable rhombohedral phase has all distortions in phase (ferroelectric, FE), whereas higher temperature phases have antiferroelectric coupling (AFE) in one, two, or three dimensions (orthorhombic, tetragonal, cubic). This FE–AFE model from QM explains such puzzling aspects of these systems as the allowed Raman excitation observed for the cubic phase, the distortions toward 〈111〉 observed in the cubic phase using x-ray fine structure, the small transition entropies, the heavily damped soft phonon modes, and the strong diffuse x-ray scattering in all but the rhombohedral phase. In addition, we expect to see additional weak Bragg peaks at the face centers of the reciprocal lattice for the cubic phase. Similar FE–AFE descriptions are expected to occur for other FE materials. Accounting for this FE–AFE nature of these phases is expected to be important in accurately simulating the domain wall structures, energetics, and dynamics, which in turn may lead to the design of improved materials.
A Leishmania amazonensis ZIP family iron transporter is essential for parasite replication within macrophage phagolysosomes
Authors: Huynh Chau , Sacks David L. , Andrews Norma W.
Published: September 2006

Infection of mammalian hosts with Leishmania amazonensis depends on the remarkable ability of these parasites to replicate within macrophage phagolysosomes. A critical adaptation for survival in this harsh environment is an efficient mechanism for gaining access to iron. In this study, we identify and characterize LIT1, a novel L. amazonensis membrane protein with extensive similarity to IRT1, a ZIP family ferrous iron transporter from Arabidopsis thaliana. The ability of LIT1 to promote iron transport was demonstrated after expression in yeast and in L. amazonensis LIT1-null amastigotes. Endogenous LIT1 was only detectable in amastigotes replicating intracellularly, and its intracellular expression was accelerated under conditions predicted to result in iron deprivation. Although L. amazonensis lacking LIT1 grew normally in axenic culture and had no defects differentiating into infective forms, replication within macrophages was abolished. Consistent with an essential role for LIT1 in intracellular growth as amastigotes, Δlit1 parasites were avirulent. After inoculation into highly susceptible mice, no lesions were detected, even after extensive periods of time. Despite the absence of pathology, viable Δlit1 parasites were recovered from the original sites of inoculation, indicating that L. amazonensis can persist in vivo independently of the ability to grow in macrophages. Our findings highlight the essential role played by intracellular iron acquisition in Leishmania virulence and identify this pathway as a promising target for therapeutic intervention.
Characterization of the defective interaction between a subset of natural killer cells and dendritic cells in HIV-1 infection
Authors: Mavilio Domenico , Lombardo Gabriella , Kinter Audrey , Fogli Manuela , La Sala Andrea , Ortolano Saida , Farschi Annahita , Follmann Dean , Gregg Roby , Kovacs Colin , Marcenaro Emanuela , Pende Daniela , Moretta Alessandro , Fauci Anthony S.
Published: September 2006

In this study, we demonstrate that the in vitro interactions between a CD56neg/CD16pos (CD56neg) subset of natural killer (NK) cells and autologous dendritic cells (DCs) from HIV-1–infected viremic but not aviremic individuals are markedly impaired and likely interfere with the development of an effective immune response. Among the defective interactions are abnormalities in the process of reciprocal NK–DC activation and maturation as well as a defect in the NK cell–mediated editing or elimination of immature DCs (iDCs). Notably, the lysis of mature DCs (mDCs) by autologous NK cells was highly impaired even after the complete masking of major histocompatibility complex I molecules, suggesting that the defective elimination of autologous iDCs is at the level of activating NK cell receptors. In this regard, the markedly impaired expression/secretion and function of NKp30 and TNF-related apoptosis-inducing ligand, particularly among the CD56neg NK cell subset, largely accounts for the highly defective NK cell–mediated lysis of autologous iDCs. Moreover, mDCs generated from HIV-1 viremic but not aviremic patients are substantially impaired in their ability to secrete interleukin (IL)-10 and -12 and to prime the proliferation of neighboring autologous NK cells, which, in turn, fail to secrete adequate amounts of interferon-γ.
Chewing the fat on natural killer T cell development
Authors: Godfrey Dale I. , McConville Malcolm J. , Pellicci Daniel G.
Published: September 2006

Natural killer T cells (NKT cells) are selected in the thymus by self-glycolipid antigens presented by CD1d molecules. It is currently thought that one specific component of the lysosomal processing pathway, which leads to the production of isoglobotrihexosylceramide (iGb3), is essential for normal NKT cell development. New evidence now shows that NKT cell development can be disrupted by a diverse range of mutations that interfere with different elements of the lysosomal processing and degradation of glycolipids. This suggests that lysosomal storage diseases (LSDs) in general, rather than one specific defect, can disrupt CD1d antigen presentation, leading to impaired development of NKT cells.