bluuebunny/crossref_metadata_2025 huggingface dataset:
Stress before and after the 2002 Denali fault earthquake
Authors: Wesson Robert L. , Boyd Oliver S.
Published: April 2007

Spatially averaged, absolute deviatoric stress tensors along the faults ruptured during the 2002 Denali fault earthquake, both before and after the event, are derived, using a new method, from estimates of the orientations of the principal stresses and the stress change associated with the earthquake. Stresses are estimated in three regions along the Denali fault, one of which also includes the Susitna Glacier fault, and one region along the Totschunda fault. Estimates of the spatially averaged shear stress before the earthquake resolved onto the faults that ruptured during the event range from near 1 MPa to near 4 MPa. Shear stresses estimated along the faults in all these regions after the event are near zero (0 ± 1 MPa). These results suggest that deviatoric stresses averaged over a few tens of km along strike are low, and that the stress drop during the earthquake was complete or nearly so.
Climate change in Amazonia caused by soybean cropland expansion, as compared to caused by pastureland expansion
Authors: Costa Marcos H. , Yanagi Silvia N. M. , Souza Paulo J. O. P. , Ribeiro Aristides , Rocha Edson J. P.
Published: April 2007

In the last two decades, the strong increase of pasturelands over former rainforest areas has raised concerns about the climate change that such change in land cover might cause. In recent years, though, expansion of soybean croplands has been increasingly important in the agricultural growth in Amazonia. In this paper we use the climate model CCM3 to investigate whether the climate change due to soybean expansion in Amazonia would be any different from the one due to pastureland expansion. The land component of the model has been updated with new findings from the Large‐Scale Biosphere Experiment in Amazonia (LBA), and a new soybean micrometeorological experiment in Amazonia. Results show that the decrease in precipitation after a soybean extension is significantly higher when compared to the change after a pastureland extension, a consequence of the very high albedo of the soybean.
Drivers of greening trend across vertically distributed biomes in temperate arid Asia
Authors: Ren Ji , Liu Hongyan , Yin Yi , He Siyuan
Published: April 2007

This study investigates vegetation responses to climate changes by analyzing 19 years (1982–2000) of both climatic data and growing season Normalized Difference Vegetation Index (NDVI) for vertically distributed desert, steppe, forest and meadow, in the middle part of the northern slope of Tianshan Mountains. Vegetation activity exhibited greening trend in all biomes, owing mainly to reduction of water stress caused by increasing precipitation, although warming trend negated that effect because of temperature‐induced drought. Precipitation acted as a remarkable driving force of plant growth in each biome through the whole growing season (spring, summer, autumn), its effect could always persist into the next season, however, the sensitivity decreased across biomes with increasing precipitation. Warming‐induced snow melt played a positive role in boosting plant growth during spring in steppe, forest and meadow. Except that, warming produced negative effects.
Magnetic properties of nanoparticles of CoxFe(3−x)O4 (0.05⩽x⩽1.6) prepared by combustion reaction
Authors: Franco Júnior Adolfo , Zapf Vivien , Egan Paul
Published: April 2007

Nanoparticles of CoxFe(3−x)O4 with x ranging from 0.05 to 1.6 were synthesized by a combustion reaction method using iron nitrate, cobalt nitrate, and urea as fuel. X-ray diffraction patterns of all systems showed broad peaks consistent with the cubic inverse spinel structure of cobalt ferrite. The absence of extra reflections in the diffraction patterns of as-prepared materials, with x=0.6, 0.8, and 1.0, demonstrates the phase purity. Magnetization measurements show that the saturation magnetization (Ms), coercivity (Hc), and remanent magnetization (Mr) depend on the molar cobalt concentration and the temperature as well. At 4K, the reduced remanence, Mr∕Ms, are equal to 0.66 and 0.63 for x=0.8 and 1.0, respectively, indicating that cubic-type magnetic anisotropy is significant in these nanoparticles. These observations are discussed in terms of a model in which it is assumed that each crystallite consists of a ferromagnetic core surrounded by a magnetically disordered shell.
Permeability of submicron and nanometer ferromagnetic particle composites
Authors: Shimada Y. , Yamaguchi M. , Qin G. W. , Okamoto S. , Kitakami O.
Published: April 2007

Ferromagnetic particle composites which include submicron and nanometer particles with large size difference exhibit higher permeability than the assembly of the pure composite constituent. The particles are redistributed in a magnetic field to reduce the demagnetizing field in the process of composite formation by heating. In this report composites of Fe and Permalloy particles were studied. Permeability is appreciably enhanced for the composites in spite of very low permeability for Permalloy particles. Further improvement is expected by developing fabrication process of particles with higher dispersion and higher saturation magnetization.
Computer simulation on the collision-sticking dynamics of two colloidal particles in an optical trap
Authors: Xu Shenghua , Sun Zhiwei
Published: April 2007

Collisions of a particle pair induced by optical tweezers have been employed to study colloidal stability. In order to deepen insights regarding the collision-sticking dynamics of a particle pair in the optical trap that were observed in experimental approaches at the particle level, the authors carry out a Brownian dynamics simulation. In the simulation, various contributing factors, including the Derjaguin-Landau-Verwey-Overbeek interaction of particles, hydrodynamic interactions, optical trapping forces on the two particles, and the Brownian motion, were all taken into account. The simulation reproduces the tendencies of the accumulated sticking probability during the trapping duration for the trapped particle pair described in our previous study and provides an explanation for why the two entangled particles in the trap experience two different statuses.
Intermediate annealing temperature and the number of final {110} grains in 3% silicon steels
Authors: Jeong Y. H. , Kim S. B. , Myung S. H. , Heo N. H.
Published: April 2007

Effects of intermediate annealing temperature on {110} texture development and magnetic induction after final annealing have been investigated in 100μm thick 3% silicon steel strips containing 6 or 18ppm sulfur. During heating at 1200°C, primary grain size decreased with decreasing intermediate annealing temperature. After final annealing at 1200°C, the total number of the {110} grains decreased and magnetic induction increased, as the intermediate annealing temperature of 750–850°C decreased and the bulk content of sulfur increased. This is attributed to the active selective growth of {100} and {111} grains at the expense of {110}⟨uvw⟩≠⟨001⟩, the subsequent decrease in total number of the {110} grains and the resultant sharp {110}⟨001⟩ texture.
Classification of generalized quantum statistics associated with the exceptional Lie (super)algebras
Authors: Stoilova N. I. , Van der Jeugt J.
Published: April 2007

Generalized quantum statistics (GQS) associated with a Lie algebra or Lie superalgebra extends the notion of para-Bose or para-Fermi statistics. Such GQS have been classified for all classical simple Lie algebras and basic classical Lie superalgebras. In the current paper we finalize this classification for all exceptional Lie algebras and superalgebras. Since the definition of GQS is closely related to a certain Z grading of the Lie (super)algebra G, our classification reproduces some known Z gradings of exceptional Lie algebras. For exceptional Lie superalgebras such a classification of Z gradings has not been given before.
Nonlinear laminar pipe flow of fluids with strongly temperature-dependent material properties
Authors: Giessler Cornelia , Lange Ulrich , Thess André
Published: April 2007

We study a one-dimensional model describing the laminar flow of a highly viscous fluid representing glass melt in a pipe. The flow is influenced by Lorentz force and gravity as well as temperature variation due to wall heat loss, electrical heating, advection, and heat diffusion. We take into account the full nonlinear temperature dependence of the viscosity and the electrical conductivity. For high and very low driving forces the mean velocity is found to be proportional to the forces as known from laminar pipe flow with constant material parameters. In between these two regimes, however, we identify a new flow regime. If there are no heat losses through the wall the mean velocity is proportional to the square root of the driving force. In the presence of wall heat loss the solution for the steady flow is even found to be nonunique, and to involve bifurcations for a wide range of parameters. This nonlinear behavior is shown to be a result of the closed-loop interaction between the velocity, temperature, and temperature-dependent material properties.
Continuum theory of polymer crystallization
Authors: Kundagrami Arindam , Muthukumar M.
Published: April 2007

We present a kinetic model of crystal growth of polymers of finite molecular weight. Experiments help to classify polymer crystallization broadly into two kinetic regimes. One is observed in melts or in high molar mass polymer solutions and is dominated by nucleation control with G∼exp(1∕TΔT), where G is the growth rate and ΔT is the supercooling. The other is observed in low molar mass solutions (as well as for small molecules) and is diffusion controlled with G∼ΔT, for small ΔT. Our model unifies these two regimes in a single formalism. The model accounts for the accumulation of polymer chains near the growth front and invokes an entropic barrier theory to recover both limits of nucleation and diffusion control. The basic theory applies to both melts and solutions, and we numerically calculate the growth details of a single crystal in a dilute solution. The effects of molecular weight and concentration are also determined considering conventional polymer dynamics. Our theory shows that entropic considerations, in addition to the traditional energetic arguments, can capture general trends of a vast range of phenomenology. Unifying ideas on crystallization from small molecules and from flexible polymer chains emerge from our theory.
Beat of sound generated by flow past three side-by-side square cylinders
Authors: Inoue Osamu , Suzuki Yuji
Published: April 2007

The sound generated by three square cylinders placed in a side-by-side arrangement in a uniform flow at low Mach numbers is studied by direct solution of the two-dimensional unsteady compressible Navier-Stokes equations. Special attention is paid to the effect of the spacing between the three cylinders on the generation mechanism of the sound. Results show that, as in the case of two side-by-side cylinders, sound pressure fields as well as flow fields show different features depending on the spacing; five different patterns (weakly interactive, symmetric biased, in-phase synchronized, flip-flopping, and single bluff-body patterns) are observed in this study. In the case of three cylinders, in contrast to the case of two cylinders, a beat of sound is observed when the spacing is relatively large and thus flow interference among the three cylinders is weak.
Structure, optical, and electrical properties of indium tin oxide thin films prepared by sputtering at room temperature and annealed in air or nitrogen
Authors: Guillén C. , Herrero J.
Published: April 2007

Indium tin oxide (ITO) thin films have been grown onto soda-lime glass substrates by sputtering at room temperature with various oxygen to argon partial pressure ratios. After deposition, the samples have been annealed at temperatures ranging from 100to500°C in nitrogen or in air. The structure, optical, and electrical characteristics of the ITO coatings have been analyzed as a function of the deposition and the annealing parameters by x-ray diffraction, spectrophotometry, and Hall effect measurements. It has been found that the as-grown amorphous layers crystallize in the cubic structure by heating above 200°C. Simultaneously, the visible optical transmittance increases and the electrical resistance decreases, in proportions that depend mainly on the sputtering conditions. The lowest resistivity values have been obtained by annealing at 400°C in nitrogen, where the highest carrier concentrations are achieved, related to oxygen vacancy creation. Some relationships between the analyzed properties have been established, showing the dependence of the cubic lattice distortion and the infrared optical characteristics on the carrier concentration.
The effect of front ZnO:Al surface texture and optical transparency on efficient light trapping in silicon thin-film solar cells
Authors: Berginski Michael , Hüpkes Jürgen , Schulte Melanie , Schöpe Gunnar , Stiebig Helmut , Rech Bernd , Wuttig Matthias
Published: April 2007

This study addresses the material properties of magnetron-sputtered aluminum-doped zinc oxide (ZnO:Al) films and their application as front contacts in silicon thin-film solar cells. Optimized films exhibit high conductivity and transparency, as well as a surface topography with adapted light-scattering properties to induce efficient light trapping in silicon thin-film solar cells. We investigated the influence on the ZnO:Al properties of the amount of alumina in the target as well as the substrate temperature during sputter deposition. The alumina content in the target influences the carrier concentration leading to different conductivity and free carrier absorption in the near infrared. Additionally, a distinct influence on the film growth of the ZnO:Al layer was found. The latter affects the surface topography which develops during wet-chemical etching in diluted hydrochloric acid. Depending on alumina content in the target and heater temperature, three different regimes of etching behavior have been identified. Low amounts of target doping and low heater temperatures result in small and irregular features in the postetching surface topography, which does not scatter the light efficiently. At higher substrate temperatures and target doping levels, more regularly distributed craters evolve with mean opening angles between 120° and 135° and lateral sizes of 1–3μm. These layers are very effective in light scattering. In the third regime—at very high substrate temperatures and high doping levels—the postetching surface is rather flat and almost no light scattering is observed. We applied the ZnO:Al films as front contacts in thin-film silicon solar cells to study their light-trapping ability. While high transparency is a prerequisite, light trapping was improved by using front contacts with a surface topography consisting of relatively uniformly dispersed craters. We have identified a low amount of target doping (0.5–1wt%) and relatively high substrate temperatures (about 350–450°C as sputter parameters enabling short-circuit current densities as high as 26.8mA∕cm2 in μc-Si:H pin cells with an i-layer thickness of 1.9μm. Limitations on further improvements of light-trapping ability are discussed in comparison with the theoretical limitations and Monte Carlo simulations presented in the literature.
Heating of ions by low-frequency Alfven waves
Authors: Lu Quanming , Li Xing
Published: April 2007

This paper reports a new physical mechanism that enables the heating of ions by a low-frequency parallel propagating Alfven wave of finite amplitude in a low beta plasma. The heating does not rely on ion cyclotron resonance. The process has two stages: First, ions, whose initial average velocity is zero, are picked up in the transverse direction by the Alfven wave and obtain an average transverse velocity. Second, at a given location the parallel thermal motions of ions produce phase differences (randomization) between ions leading to the heating of ions. The randomization (or heating) process saturates when phase differences are sufficiently large. The time scale over which ions are significantly heated is ∼π∕(kvth) (vth is the initial ion thermal speed and k is the wave number). The heating is dominant in the perpendicular (to the background magnetic field) direction. Subsequently, a large ion temperature anisotropy is produced. During the heating process, ions are also accelerated in the parallel direction and obtain a bulk flow speed along the background magnetic field.
Long wavelength propagation of elastic waves in three-dimensional periodic solid-solid media
Authors: Ni Qing , Cheng Jianchun
Published: April 2007

We present an approach for efficient, accurate calculations of the elastic wave properties of three-dimensional periodic solid-solid media with cubic lattice structures based on the principle that the elastic wave should be uniform when averaged over length scales much larger than the size of the scatterers. Utilizing the fact that the media has the same pure mode properties as natural crystal with the corresponding lattice structure, we derive formulas for effective velocities propagating along and normal to the lattice axis, from which three independent effective elastic moduli are calculated, respectively. Effective velocities propagating along any directions can be calculated with this method, which captures the multiple scattering and the structure of the periodic medium. The results agree well with those calculated directly from the slope of the corresponding bands near the Γ point of the first Brillouin zone and are in good agreement with previous isotropic theory at high-symmetry directions.
Nonthermal atmospheric rf plasma in one-dimensional spherical coordinates: Asymmetric sheath structure and the discharge mechanism
Authors: Sakiyama Yukinori , Graves David B.
Published: April 2007

We present one-dimensional simulations of atmospheric pressure rf-excited plasma with two concentric spherical electrodes and the inner electrode powered. The gas used is helium with 0.1% nitrogen addition. The gap distance between the inner and outer electrodes is 1mm. The coupled continuity equations and electron energy equation are solved with Poisson’s equation using the finite element method. A mode transition is observed in the discharge power-voltage curve between 1 and 1000mW. In the low power mode, ionization rate peaks only near the inner electrode. The electron-impact excitation and ionization rates peak in the local cathodic phase. In the high power mode, the rate of ionization peaks near the outer electrode as well as the inner electrode. The inner sheath significantly shrinks and the direct electron-impact ionization is the primary ionization reaction near the inner electrode. The ionization rate near the outer electrode is due to Ohmic sheath oscillation heating of electrons, resulting in a peak in metastable helium creation. Penning ionization is the major ionization reaction near the outer electrode. Thus, two different ionization mechanisms coexist near the inner and outer electrodes. Electron heating near the outer electrode may have implications for surface processing in atmospheric pressure microdischarges. The local field approximation (LFA) in high power mode fails to predict the ionization rate peak near the outer electrode due to its inability to properly account for electron diffusion in the presence of both a strong electric field and electron density gradient. However, use of the LFA is adequate to model the low power mode and it correctly predicts the existence of the mode transition.
Photodissociation dynamics of the 2-propyl radical, C3H7
Authors: Noller Bastian , Fischer Ingo
Published: April 2007

The photodissociation of 2-propyl leading to propene+H was investigated with nanosecond time resolution. A supersonic beam of isolated 2-propyl radicals was produced by pyrolysis of 2-bromopopane. The kinetic energy release of the H-atom photofragment was monitored as a function of excitation wavelength by photofragment Doppler spectroscopy via the Lyman-α transition. The loss of hydrogen atoms after excitation proceeds in α position to the radical center with a rate constant of 5.8×107s−1 at 254nm. Approximately 20% of the excess energy is deposited as translation in the H-atom photofragment. In contrast 1-propyl does not lose H atoms to a significant extent. The experimental results are compared to simple Rice-Ramsperger-Kassel-Marcus calculations. The possible reaction pathways are examined in hybrid density functional theory calculations.
Irradiation of cryogenic temperature sensors by gamma dose of 1MGy
Authors: Filippov Yu. P. , Miklayev V. M. , Sukhanova A. K.
Published: April 2007

This article presents results of investigations of the cryogenic thermometers which can operate under high radiation environment. To clarify the temperature shifts due to gamma irradiation up to 1MGy, the platinum (two types), carbon-glass, and TVO temperature sensors have been tested. Before the irradiation run, the selected sensors were calibrated and a series of experiments was carried out under irradiation of the sensors at 77.3 and 293K when their readings were taken in situ. Afterwards, the postirradiation evolution (short and long time) of the sensors was measured at 4.2, 77.3, and 293K. The results, depending on the type of the sensor, can be optimistic or pessimistic. Some comparisons with analogous data for fast neutron treatment have also been made.
Environmental chamber for an atomic force microscope
Authors: Lievonen J. , Ranttila K. , Ahlskog M.
Published: April 2007

A commercial atomic force microscope (AFM), originally designed for operation in ambient conditions, was placed inside a compact aluminum chamber, which can be pumped down to high vacuum levels or filled with a desired gaseous atmosphere, including humidity, up to normal pressure. The design of this environmental AFM is such that minimal intrusion is made to the original setup, which can be restored easily. The performance inside the environmental chamber is similar to the original version.
Influence of deposition rate on the formation of growth twins in sputter-deposited 330 austenitic stainless steel films
Authors: Zhang X. , Anderoglu O. , Misra A. , Wang H.
Published: April 2007

The authors have studied the influence of deposition rate on the formation of growth twins in sputter-deposited 330 austenitic stainless steel thin films. Transmission electron microscopy shows that the volume fraction of twinned grains increases with increasing deposition rate, whereas the average columnar grain size and twin spacing stay approximately unchanged. These experimental results agree qualitatively with their analytical model that predicts deposition rate dependent formation of growth twins. The film hardness increases monotonically with increasing volume fraction of twinned grains.
Quantum random number generator based on photonic emission in semiconductors
Authors: Stipčević M. , Rogina B. Medved
Published: April 2007

We report upon the realization of a novel fast nondeterministic random number generator whose randomness relies on the intrinsic randomness of the quantum physical processes of photonic emission in semiconductors and subsequent detection by the photoelectric effect. Timing information of detected photons is used to generate binary random digits-bits. The bit extraction method based on the restartable clock method theoretically eliminates both bias and autocorrelation while reaching efficiency of almost 0.5 bits per random event. A prototype has been built and statistically tested.
Fabrication and ferroelectric properties of highly dense lead-free piezoelectric (K0.5Na0.5)NbO3 thick films by aerosol deposition
Authors: Ryu Jungho , Choi Jong-Jin , Hahn Byung-Dong , Park Dong-Soo , Yoon Woon-Ha , Kim Ki-Hoon
Published: April 2007

Lead-free piezoelectric thick films of (K0.5Na0.5)NbO3 were fabricated by aerosol-deposition method. The thickness of KNN film was 7.1μm and fully dense films were obtained. The dielectric constants ε3T∕ε0 of the as-deposited and annealed films at 1kHz were 116 and 545, respectively, which are higher than any previously reported values for lead-free piezoelectric thin/thick films, either without or with heat treatment. The ferroelectric properties were improved after annealing and the maximum values of Pr=8.1μC∕cm3 and Ec=100kV∕cm were achieved. These values are markedly superior to those of sintered KNN ceramic counterparts.
Layer-by-layer photonic crystal fabricated by low-temperature atomic layer deposition
Authors: Lee Jae-Hwang , Leung Wai , Ahn Jinho , Lee Taeho , Park In-Sung , Constant Kristen , Ho Kai-Ming
Published: April 2007

Layer-by-layer three-dimensional photonic crystals are fabricated by low-temperature atomic layer deposition of titanium dioxide on a polymer template created by soft lithography. With a highly conformal layer of titanium dioxide, a significantly enhanced photonic band gap effect appears at 3.1μm in transmittance and reflectance. From optical investigations of systematically shifted structures, the robust nature of the photonic band gap with respect to structural fluctuations is confirmed experimentally. With angle-resolved Fourier-transform spectroscopy, the authors also demonstrate that the fabricated photonic crystal can be a diffraction-free device as the photonic band gap exists over the diffracting regime.
Suitability of lithium doped electron injection layers for organic semiconductor lasers
Authors: Rabe T. , Hamwi S. , Meyer J. , Görrn P. , Riedl T. , Johannes H.-H. , Kowalsky W.
Published: April 2007

Lithium doped 2,2′,2″-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) as electron injection layer in organic laser diodes is investigated. The optical material absorption of optimum doped Li:TPBi is as low as 300cm−1 at λ=600nm. Kelvin probe analysis demonstrates that thin layers (5nm) of Li:TPBi already enable efficient electron injection from low optical loss transparent conducting oxide contacts. Moreover, stable current densities of about 100A∕cm2 can be injected. The waveguide losses added due to these Li:TPBi layers can be as low as 3cm−1. These results present a major step towards electrically contacted, low-loss organic laser structures.
Buckling modes of elastic thin films on elastic substrates
Authors: Mei Haixia , Huang Rui , Chung Jun Young , Stafford Christopher M. , Yu Hong-Hui
Published: April 2007

Two buckling modes have been observed in thin films: buckle delamination and wrinkling. This letter identifies the conditions for selecting the favored buckling modes for elastic films on elastic substrates. Transition from one buckling mode to another is predicted as the stiffness ratio between the substrate and the film or is predicted for variation of the stiffness ratio between the substrate and the film or variation of theinterfacial defect size. The theoretical results are demonstrated experimentally by observing the coexistence of both buckling modes and mode transition in one film-substrate system.
In
Ga
As
∕
Al
As
Sb
∕
In
P
strain compensated quantum cascade lasers
Authors: Revin D. G. , Cockburn J. W. , Steer M. J. , Airey R. J. , Hopkinson M. , Krysa A. B. , Wilson L. R. , Menzel S.
Published: April 2007

The authors demonstrate the feasibility of strain compensated InGaAs∕AlAsSb∕InP quantum cascade lasers (QCLs). Three QCL structures have been investigated, having identical design but with different indium fractions in InxGa1−xAs quantum wells: 0.53 (lattice matched reference device), 0.6, and 0.7. All lasers display similar operating characteristics at λ≈4.1μm with no degradation of performance for the strain compensated devices. This strain compensated system is of interest for QCLs at λ<∼3.5μm. It provides increased energy separation between the Γ and X conduction band minima in the quantum wells, thus decreasing carrier leakage from the upper laser levels by intervalley scattering.
Enhancement by electric field of high-speed photoconductivity in AlGaN∕GaN heterostructures
Authors: Danilchenko B. A. , Zelensky S. E. , Drok E. A. , Belyaev A. E. , Kochelap V. A. , Lüth H. , Vitusevich S. A.
Published: April 2007

The authors report a large response in the conductivity of AlGaN∕GaN heterostructures to a 10ns UV laser pulses. The dynamics of the conductivity response follows the time evolution of the laser pulse. This fast photoconductivity component shows a remarkable enhancement in high electric fields. For the field ≈15kV∕cm, it increases by at least one order of magnitude at temperatures of 4.2 and 300K. This photoconductivity enhancement is found to be related to the hot electron effect. The authors propose an explanation for the observed phenomena. The mechanism of the photoconductivity enhancement involves nonequilibrium LO phonons generated by hot carriers.
Recombination current and series resistance imaging of solar cells by combined luminescence and lock-in thermography
Authors: Ramspeck K. , Bothe K. , Hinken D. , Fischer B. , Schmidt J. , Brendel R.
Published: April 2007

We perform recombination current and series resistance imaging on large-area crystalline silicon solar cells using a combined analysis of camera-based dark lock-in thermography (DLIT) and electroluminescence (EL) imaging. The solar cells are imaged both by DLIT and EL under identical operating conditions. The quantitative analysis of the DLIT measurement produces an image of the local heating power and the EL picture results in an image of the local cell voltage. Combining the two images pixel by pixel allows us to calculate images of the local recombination current and the local series resistance of the solar cell.
Differences in emission spectra of Si- and C-core partial dislocations
Authors: Liu Kendrick X. , Stahlbush Robert E. , Maximenko Serguei I. , Caldwell Joshua D.
Published: April 2007

The spectra for individual Si- and C-core partial dislocations were obtained using optical emission microscopy. Both electroluminescence and photoluminescence revealed similar spectra. The Si-core spectra peaked at 700nm, consistent with the reported spectra from collection of dislocations. For the C core, a dominant IR band starting at 850nm was revealed for injections around 0.1A∕cm2. For an injection at 1A∕cm2, this band saturated and a band at 700nm dominated. This C-core band at 700nm was broader, and its intensity peak was lower than the Si core. Results are discussed along with existing theoretical models of deep levels.
Thermodynamic equilibrium model of pyroelectric polycrystalline thin films
Authors: Hu Wencheng , Yang Chuanren , Zhang Wanli , Liao Xiyi
Published: April 2007

This study deals with the thermodynamic equilibrium theory of pyroelectric polycrystalline thin films. The unit cell of pyroelectric polycrystalline thin films in the ferroelectric phase to be considered is assumed as a dipole and is a nondipole at its paraelectric phase. The phase transition between ferroelectric and paraelectric phases is hypothesized as an equilibrium of the dipoles and the nondipole. Based on the thermodynamic equilibrium theory, an expression formula about the spontaneous polarization and temperature is suggested. Considering the sandwich structure of pyroelectric polycrystalline thin films, an equation about the relations between pyroelectric coefficient and temperature was established.
Integrated high-TC radio frequency superconducting quantum interference device using SrTiO3 bicrystal substrate resonators
Authors: Chen Ji-Cheng , Chen Kuen-Lin , Yang Hong-Chang , Wu Chiu-Hsien , Horng Herng-Er
Published: April 2007

In contrast to the previous high-TC radio frequency (rf) superconducting quantum interference device (SQUID) magnetometer, in which the rf SQUID is placed face to face with the substrate resonator, a simple integrated washer-type rf SQUID magnetometer based on a single SrTiO3 bicrystal substrate resonator is designed and fabricated in this work. The magnetometer combines the rf SQUID, flux focusing, and resonator into a single chip. This integrated washer-type rf SQUID magnetometer offers a superior advantage in integrating the device to a scanning SQUID detection system in which the distance between the sample and SQUID can be minimized.
Deficiency in the LIM-only protein Fhl2 impairs skin wound healing
Authors: Wixler Viktor , Hirner Stephanie , Müller Judith M. , Gullotti Lucia , Will Carola , Kirfel Jutta , Günther Thomas , Schneider Holm , Bosserhoff Anja , Schorle Hubert , Park Jung , Schüle Roland , Buettner Reinhard
Published: April 2007

After skin wounding, the repair process is initiated by the release of growth factors, cytokines, and bioactive lipids from injured vessels and coagulated platelets. These signal molecules induce synthesis and deposition of a provisional extracellular matrix, as well as fibroblast invasion into and contraction of the wounded area. We previously showed that sphingosine-1-phosphate (S1P) triggers a signal transduction cascade mediating nuclear translocation of the LIM-only protein Fhl2 in response to activation of the RhoA GTPase (Muller, J.M., U. Isele, E. Metzger, A. Rempel, M. Moser, A. Pscherer, T. Breyer, C. Holubarsch, R. Buettner, and R. Schule. 2000. EMBO J. 19:359–369; Muller, J.M., E. Metzger, H. Greschik, A.K. Bosserhoff, L. Mercep, R. Buettner, and R. Schule. 2002. EMBO J. 21:736–748.). We demonstrate impaired cutaneous wound healing in Fhl2-deficient mice rescued by transgenic expression of Fhl2. Furthermore, collagen contraction and cell migration are severely impaired in Fhl2-deficient cells. Consequently, we show that the expression of α-smooth muscle actin, which is regulated by Fhl2, is reduced and delayed in wounds of Fhl2-deficient mice and that the expression of p130Cas, which is essential for cell migration, is reduced in Fhl2-deficient cells. In summary, our data demonstrate a function of Fhl2 as a lipid-triggered signaling molecule in mesenchymal cells regulating their migration and contraction during cutaneous wound healing.
Adherens junction remodeling by the Notch pathway in Drosophila melanogaster oogenesis
Authors: Grammont Muriel
Published: April 2007

Identifying genes involved in the control of adherens junction (AJ) remodeling is essential to understanding epithelial morphogenesis. During follicular epithelium development in Drosophila melanogaster, the main body follicular cells (MBFCs) are displaced toward the oocyte and become columnar. Concomitantly, the stretched cells (StCs) become squamous and flatten around the nurse cells. By monitoring the expression of epithelial cadherin and Armadillo, I have discovered that the rate of AJ disassembly between the StCs is affected in follicles with somatic clones mutant for fringe or Delta and Serrate. This results in abnormal StC flattening and delayed MBFC displacement. Additionally, accumulation of the myosin II heavy chain Zipper is delayed at the AJs that require disassembly. Together, my results demonstrate that the Notch pathway controls AJ remodeling between the StCs and that this role is crucial for the timing of MBFC displacement and StC flattening. This provides new evidence that Notch, besides playing a key role in cell differentiation, also controls cell morphogenesis.
Grd19/Snx3p functions as a cargo-specific adapter for retromer-dependent endocytic recycling
Authors: Strochlic Todd I. , Setty Thanuja Gangi , Sitaram Anand , Burd Christopher G.
Published: April 2007

Amajor function of the endocytic system is the sorting of cargo to various organelles. Endocytic sorting of the yeast reductive iron transporter, which is composed of the Fet3 and Ftr1 proteins, is regulated by available iron. When iron is provided to iron-starved cells, Fet3p–Ftr1p is targeted to the lysosome-like vacuole and degraded. In contrast, when iron is not available, Fet3p–Ftr1p is maintained on the plasma membrane via an endocytic recycling pathway requiring the sorting nexin Grd19/Snx3p, the pentameric retromer complex, and the Ypt6p Golgi Rab GTPase module. A recycling signal in Ftr1p was identified and found to bind directly to Grd19/Snx3p. Retromer and Grd19/Snx3p partially colocalize to tubular endosomes, where they are physically associated. After export from the endosome, Fet3p–Ftr1p transits through the Golgi apparatus for resecretion. Thus, Grd19/Snx3p, functions as a cargo-specific adapter for the retromer complex, establishing a precedent for a mechanism by which sorting nexins expand the repertoire of retromer-dependent cargos.
Rhetoric, Induction, and the Free Speech Dilemma
Authors: Zamora Bonilla Jesús P.
Published: April 2007

Scientists can choose different claims as interpretations of the results of their research. Scientific rhetoric is understood as the attempt to make those claims most beneficial for the scientists’ interests. A rational choice, game-theoretic model is developed to analyze how this choice can be made and to assess it from a normative point of view. The main conclusion is that ‘social’ interests (pursuit of recognition) may conflict with ‘cognitive’ ones when no constraints are put on the choices of the authors of scientific papers, as in an ‘ideal free speech situation’. Scientific institutions may help to solve this conflict. Lastly, some empirical predictions are offered that can inspire future social research of the refereeing process.
The Proper Ends of Science: Philip Kitcher, Science, and the Good
Authors: Simon Jeremy
Published: April 2007

In Science, Truth, and Democracy, Philip Kitcher challenges the view that science has a single, context-independent, goal, and that the pursuit of this goal is essentially immune from moral critique. He substitutes a context-dependent account of science's goal, and shows that this account subjects science to moral evaluation. I argue that Kitcher's approach must be modified, as his account of science ultimately must be explicated in terms of moral concepts. I attempt, therefore, to give an account of science's goal that is free of direct moral entanglements but still makes this goal context-dependent and leaves the choice of which projects to pursue subject to moral scrutiny.
Essay Review: Debunking Adapting Minds
Authors: Machery Edouard , Barrett H. Clark
Published: April 2007

David Buller's recent book, Adapting Minds, is a philosophical critique of the field of evolutionary psychology. Buller argues that evolutionary psychology is utterly bankrupt from both a theoretical and an empirical point of view. Although Adapting Minds has been well received in both the academic press and the popular media, we argue that Buller's critique of evolutionary psychology fails.
CROSS RATIO GRAPHS
Authors: GARDINER A. , PRAEGER CHERYL E. , ZHOU SANMING
Published: April 2007

A family of arc-transitive graphs is studied. The vertices of these graphs are ordered pairs of distinct
points from a finite projective line, and adjacency is defined in terms of the cross ratio. A uniform
description of the graphs is given, their automorphism groups are determined, the problem of isomorphism
between graphs in the family is solved, some combinatorial properties are explored, and the graphs are
characterised as a certain class of arc-transitive graphs. Some of these graphs have arisen as examples in
studies of arc-transitive graphs with complete quotients and arc-transitive graphs which ‘almost cover’ a
2-arc transitive graph.
JORDAN SUPERALGEBRAS DEFINED BY BRACKETS
Authors: MARTÍNEZ CONSUELO , SHESTAKOV IVAN , ZELMANOV EFIM
Published: April 2007

Jordan superalgebras defined by brackets on associative commutative superalgebras are studied. It is
proved that any such superalgebra is imbedded into a superalgebra defined by Poisson brackets. In
particular, all Jordan superalgebras of brackets are i-special. The speciality of these superalgebras is also
examined, and it is proved, in particular, that the Cheng–Kac superalgebra is special.
CLASSES MINIMALES DE RÉSEAUX ET RÉTRACTIONS
GÉOMÉTRIQUES ÉQUIVARIANTES DANS LES ESPACES
SYMÉTRIQUES
Authors: BAVARD CHRISTOPHE
Published: April 2007

Equivariant and cocompact retractions of certain symmetric spaces are constructed. These retractions
are defined using the natural geometry of symmetric spaces and in relation to the theory of lattices
of euclidean space. The following cases are considered: the symmetric space corresponding to lattices
endowed with a finite group action, from which is obtained some information relating to the classification problem of
these lattices, and the Siegel space Sp2g(R)/Ug,
for which a natural Sp2g(Z)-equivariant cocompact retract of codimension 1
is obtained.
THE BOGOMOLOV–MIYAOKA–YAU INEQUALITY FOR LOG CANONICAL SURFACES
Authors: LANGER ADRIAN
Published: April 2007

Let X be a smooth projective surface of non-negative Kodaira dimension. Bogomolov
[1, Theorem 5] proved that c21 [les ] 4c2.
This was improved to c21 [les ] 3c2 by
Miyaoka [12, Theorem 4] and Yau [19, Theorem 4]. Equality
c21 [les ] 3c2 is attained,
for example, if the universal cover of X is a ball (if κ(X) = 2 then this is the only
possibility). Further generalizations of inequalities for Chern classes for some singular
surfaces with (fractional) boundary were obtained by Sakai [16, Theorem 7.6],
Miyaoka [13, Theorem 1.1], Kobayashi [6, Theorem 2; 7, Theorem 12],
Wahl [18, Main Theorem] and Megyesi [10, Theorem 10.14; 11, Theorem 0.1].

In [8] we introduced Chern classes of reflexive sheaves, using Wahl's local Chern
classes of vector bundles on resolutions of surface singularities. Here we apply them
to obtain the following generalization of the Bogomolov–Miyaoka–Yau inequality.
PRIME POWER DEGREE REPRESENTATIONS OF THE SYMMETRIC AND ALTERNATING GROUPS
Authors: BALOG ANTAL , BESSENRODT CHRISTINE , OLSSON JØRN B. , ONO KEN
Published: April 2007

In 1998, the second author of this paper raised the problem of classifying the
irreducible characters of Sn of prime power degree. Zalesskii proposed the analogous
problem for quasi-simple groups, and he has, in joint work with Malle, made
substantial progress on this latter problem. With the exception of the alternating
groups and their double covers, their work provides a complete solution. In this
article we first classify all the irreducible characters of Sn of prime power degree
(Theorem 2.4), and then we deduce the corresponding classification for the alternating
groups (Theorem 5.1), thus providing the answer for one of the two remaining
families in Zalesskii's problem. This classification has another application in group
theory. With it, we are able to answer, for alternating groups, a question of Huppert:
which simple groups G have the property that there is a prime p for which G has
an irreducible character of p-power degree > 1 and all of the irreducible characters
of G have degrees that are relatively prime to p or are powers of p?

The case of the double covers of the symmetric and alternating groups will be dealt
with in a forthcoming paper; in particular, this completes the answer to Zalesskii's
problem.

The paper is organized as follows. In Section 2, some results on hook lengths in
partitions are proved. These results lead to an algorithm which allows us to show
that every irreducible representation of Sn with prime power degree is labelled by
a partition having a large hook. In Section 3, we obtain a new result concerning
the prime factors of consecutive integers (Theorem 3.4). In Section 4 we prove
Theorem 2.4, the main result. To do so, we combine the algorithm above with
Theorem 3.4 and work of Rasala on minimal degrees. This implies Theorem 2.4 for
large n. To complete the proof, we check that the algorithm terminates appropriately
for small n (that is, those n [les ] 9.25 · 108)
with the aid of a computer. In the last section we derive the classification of irreducible characters of
An of prime power
degree, and we solve Huppert's question for alternating groups.
THE CONVERGENCE OF A CLASS OF QUASIMONOTONE REACTION–DIFFUSION SYSTEMS
Authors: WANG YI , JIANG JIFA
Published: April 2007

It is proved that every solution of the Neumann initial-boundary problem

[formula here]

converges to some equilibrium, if the system satisfies
(i) ∂Fi/∂uj [ges ] 0 for all
1 [les ] i ≠ j [les ] n,
(ii) F(u * g(s)) [ges ] h(s) [midast ] F(u)
whenever u ∈ ℝn+ and 0 [les ] s [les ] 1, where x * y
= (x1y1, …, xnyn)
and g, h : [0, 1] → [0, 1]n are
continuous functions satisfying gi(0)
= hi(0) = 0, gi(1) = hi(1)
= 1, 0 < gi(s); hi(s) < 1
for all s ∈ (0, 1) and i = 1, 2, …, n, and
(iii) the solution of the corresponding ordinary differential equation system is bounded in
ℝn+. We also study the convergence of the solution of the Lotka–Volterra system

[formula here]

where ri > 0, α [ges ] 0, and
aij [ges ] 0 for i ≠ j.
THE CUBIC CONGRUENCE x3 + Ax2 + Bx + C ≡ 0

(mod p) AND BINARY QUADRATIC FORMS II
Authors: SPEARMAN BLAIR K. , WILLIAMS KENNETH S.
Published: April 2007

It is shown that the splitting modulo a prime p of a given monic, integral, irreducible cubic with non-square discriminant is equivalent to p being represented by forms in a certain subgroup of index 3 in the

form class group of discriminant equal to the discriminant of the field defined by the cubic.
UNIQUENESS OF THE TOPOLOGY ON SPACES OF VECTOR-VALUED FUNCTIONS
Authors: VILLENA A. R.
Published: April 2007

Let Ω be a topological space without isolated points, let E be a topological linear space which is
continuously embedded into a product of countably boundedly generated topological linear spaces, and
let X be a linear subspace of C(Ω, E). If a ∈ C(Ω)
is not constant on any open subset of Ω and aX ⊂ X,
then it is shown that there is at most one F-space topology on X that makes the multiplication by
a continuous. Furthermore, if [Ufr ] is a subset of C(Ω) which separates strongly the points
of Ω and [Ufr ]X ⊂ X, then it is proved that there is at most one F-space
topology on X that makes the multiplication by a continuous for each a ∈ [Ufr ].

These results are applied to the study of the uniqueness of the F-space topology and the continuity of
translation invariant operators on the Banach space L1(G, E) for a noncompact locally compact group G
and a Banach space E. Furthermore, the problems of the uniqueness of the F-algebra topology and the
continuity of epimorphisms and derivations on F-algebras and some algebras of vector-valued functions
are considered.
ANALYTIC TRIDIAGONAL REPRODUCING KERNELS
Authors: ADAMS GREGORY T. , MCGUIRE PAUL J.
Published: April 2007

The paper characterizes the reproducing kernel Hilbert spaces with orthonormal bases of the form
{(an,0+an,1z+…+an,JzJ)zn, n [ges ] 0}. The primary focus is on the tridiagonal case where J = 1, and
on how it compares with the diagonal case where J = 0. The question of when multiplication by z is a
bounded operator is investigated, and aspects of this operator are discussed. In the diagonal case, Mz is
a weighted unilateral shift. It is shown that in the tridiagonal case, this need not be so, and an example
is given in which the commutant of Mz on a tridiagonal space is strikingly different from that on any
diagonal space.
HOMOLOGY DECOMPOSITIONS FOR CLASSIFYING SPACES OF FINITE GROUPS ASSOCIATED TO MODULAR REPRESENTATIONS
Authors: NOTBOHM D.
Published: April 2007

For a prime p, a homology decomposition of the classifying space BG of a finite group G
consist of a functor F : D → spaces from a small category into the category of spaces
and a map hocolim F → BG from the homotopy colimit to BG that induces an isomorphism
in mod-p homology. Associated to a modular representation
G → Gl(n; [ ]p), a family of subgroups is constructed that is
closed under conjugation, which gives rise to three different homology decompositions, the so-called
subgroup, centralizer and normalizer decompositions. For an action of G on an [ ]p-vector
space V, this collection consists of all subgroups of G with nontrivial p-Sylow subgroup
which fix nontrivial (proper) subspaces of V pointwise. These decomposition formulas connect the modular
representation theory of G with the homotopy theory of BG.