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1 The egg-prepupal parasitoid Fopius arisanus (Hymenoptera: Braconidae) was evaluated in quarantine facilities as a potential biological control agent for the olive fruit fly Bactrocera oleae (Diptera: Tephritidae) in California, U.S.A. 2 Nontarget testing of two weed biological control agents confirmed that F. arisanus will not attack Tephritidae that feed in inflorescences or galls. It may, however, pose risks to native Tephritidae that feed in fruit. 3 Females preferentially oviposited in eggs, although first-instar B. oleae were also attacked. Low lifetime reproductive potential and high rates of direct mortality inflicted on host eggs indicate that rearing on B. oleae may prove difficult. 4 In multiparasitized B. oleae, F. arisanus prevailed in competition against two species of larval–pupal parasitoids, Diachasmimorpha kraussii and Psyttalia concolor (both Hymenoptera: Braconidae). 5 The broad host-range of F. arisanus with respect to fruit-feeding Tephritidae may preclude its introduction to California, as may its low fecundity and its intrinsic competitive superiority over larva l–pupal parasitoids, which include specialists on B. oleae that are currently being introduced to California. High rates of direct mortality, however, point to potential uses in augmentative biological control. Whether or not F. arisanus is released in California, its biology as a parasitoid of B. oleae has been little studied to date and the results herein may be applied in other regions worldwide where B. oleae is a problem. [ABSTRACT FROM AUTHOR]

Magnetic reconnection with various plasma β (the ratio of plasma pressure to the magnetic pressure) is studied numerically using a 2.5 dimensional Hall magnetohydrodynamics (MHD) code developed from a multistep implicit scheme. The initial state of the Hall MHD simulation is an equilibrium Harris sheet with Lc=0.5di (where Lc is the half-width of the equilibrium current layer and di is the ion inertial length) and a zero guide field (i.e., By0=0 at t=0). Driven by a constant boundary inflow a quasisteady fast reconnection occurs in the plasma with a low uniform resistivity. The out-of-plane magnetic field component By is then spontaneously generated and its quadrupolar structure is shown around the X point. It is demonstrated by the comparing studies that the reconnection dynamics is controlled by the Hall effect and the effect of scalar electron pressure gradient is negligible in the generalized Ohm’s law. It is also found that the openness of the magnetic separatrix angle and associated quadrupolar By structure is enlarged as β increases. When β>2.0 fine structures of By contours with reversed sign emerge. The numerical results indicate that the variations in electron velocity Ve are greater than those in ion velocity Vi and the decoupling of electron and ion occurs in larger scale lengths than di as β increases. Clearly, the reserve current, which is associated with the relative motion between electrons and ions, generates the fine structures of By contours in the outflow region. Then the corresponding profile of By component exhibits a static whistler wave signature. Enhanced wave activities observed during a Cluster crossing of the high-β exterior cusp region [Y. Khotyaintsev, A. Vaivads, Y. Ogawa, B. Popielawska, M. André, S. Buchert, P. Décréau, B. Lavraud, and H. Rème, Ann. Geophys. 22, 2403 (2004)] might be related to the Hall effects of magnetic reconnection shown in the present simulation. [ABSTRACT FROM AUTHOR]

The sensitivity of Cx45 channels to CO2, transjunctional voltage ( V(j)) and inhibition of calmodulin (CaM) expression was tested in oocytes by dual voltage clamp. Cx45 channels are very sensitive to V(j) and close with V(j) preferentially by the slow gate, likely to be the same as the chemical gate. With a CO2-induced drop in junctional conductance ( G(j)), both the speed of V(j)-dependent inactivation of junctional current ( I(j)) and V(j) sensitivity increased. With 40-mV V(j)-pulses, the tau of single exponential I(j) decay reversibly decreased by;40% during CO2 application, and G(j steady state)/G(j peak) decreased multiphasically, indicating that both kinetics and V(j) sensitivity of chemical/slow V(j) gating are altered by changes in [H(+)](i) and/or [Ca(2+)](i). CaM expression was inhibited with oligonucleotides antisense to CaM mRNA. With 15 min CO2, relative junctional conductance ( G(jt)/ G(jt0)) dropped to 0% in controls, but only by;17% in CaM-antisense oocytes. Similarly, V(j) sensitivity was significantly lessened in CaM-antisense oocytes. The data indicate that both the speed and sensitivity of V(j)-dependent inactivation of the junctional current of Cx45 channels are affected by CO2 application, and that CaM plays a key role in channel gating. [ABSTRACT FROM AUTHOR]

Organic selenium (Se) supplementation from Se-enriched yeast (SY) has been advocated and approved for use in animal feeds by some nutritionists and researchers rather than inorganic Se from sodium selenite. However, there is little available safety data of SY in laying hens. A subchronic study was conducted to determine if high-dose SY affects the safety of hens. A total of 768, 30-wk-old, Hy-Line Brown hens were randomly assigned to 1 of 4 groups (192 laying hens per group) with 6 replicates of 32 birds each. After a 2-wk acclimation period, the birds were fed diets supplemented with 0, 0.3, 1.5, or 3.0 mg/kg Se from SY for 12 wk. Throughout the study period, clinical observations and laying performance were measured. The hematological and chemical parameters of blood samples and the Se concentration in eggs were examined after SY supplementation for 4, 8, and 12 wk, and the egg quality was measured after 12 wk. At the end of the study, full post-mortem examinations were conducted: breast Se concentrations were measured, visceral, and reproductive organs were weighed, and specified tissues were collected for subsequent histological examinations. Although the Se concentrations in the eggs and breast meat from hens fed 3.0 mg/kg of Se from SY were 1036.73% and 2127.93% higher (P < 0.001) than those from hens fed a basal diet after 12 wk, no treatment-related changes of toxicological significance were observed. Therefore, up to 3 mg/kg organic Se from SY can be used to supplement the diets for laying hens without adverse effects following 84-d administration. [ABSTRACT FROM AUTHOR]

Kinetic‐scale magnetic dips (KSMDs), with a significant depression in magnetic field strength, and scale length close to and less than one proton gyroradius, were reported in the turbulent plasmas both in recent observation and numerical simulation studies. These KSMDs likely play important roles in energy conversion and dissipation. In this study, we present observations of the KSMDs that are labeled whistler mode waves, electrostatic solitary waves, and electron cyclotron waves in the magnetosheath. The observations suggest that electron temperature anisotropy or beams within KSMD structures provide free energy to generate these waves. In addition, the occurrence rates of the waves are higher in the center of the magnetic dips than at their edges, implying that the KSMDs might be the origin of various kinds of waves. We suggest that the KSMDs could provide favorable conditions for the generation of waves and transfer energy to the waves in turbulent magnetosheath plasmas. Plain Language Summary: The Earth's magnetosheath is a turbulent plasma environment where energy conversion, particle acceleration, and mass and momentum transport take place. Many of these key processes involve kinetic‐scale physics. However, in‐depth studies from previous missions are limited by their lower spacecraft data resolution. The recent Magnetospheric Multiscale (MMS) mission provides us with a large amount of high‐temporal cadence data for studying kinetic‐scale physics in the magnetosheath. In this study, we report whistler mode waves, electrostatic solitary waves and electron cyclotron waves within kinetic‐scale magnetic dips (KSMDs) that can be generated in the turbulent magnetosheath. These waves could be excited by electron temperature anisotropy or beams. As is well known, plasma waves are important processes in converting energy, accelerating and scattering electrons and ions, and modifying the distributions of charged particles. If plasma instabilities develop within the KSMDs, the resulting waves could absorb free energy from plasma particles and may propagate out of the KSMDs. Thus, our discoveries could significantly advance the understanding of energy conversion and dissipation for kinetic‐scale turbulence. This study provides a new reference not only for observations in space physics but also for related basic plasma theories and numerical simulations. Key Points: MMS observations reveal KSMDs coupled with whistler mode waves, electrostatic solitary waves, and electron cyclotron wavesThese waves are excited by different plasma distributions, and the ESWs could affect the electron distributions in kinetic scaleStatistical results indicate that the KSMDs in the magnetosheath are a possible origin for various kinds of waves [ABSTRACT FROM AUTHOR]

In order to further clarify the relationship between the free volume and bending plasticity, the bending properties of Zr65Cu17.5Ni10Al7.5 bulk metallic glass (BMG) samples with different thicknesses corresponding to different solidification cooling rates were investigated. The results show that the bending plasticity of Zr65Cu17.5Ni10Al7.5 BMG decreases with the decrease of cooling rate, which is consistent with the evolution of shear bands density revealed by the investigation of microstructure. These phenomena are mainly attributed to the decrease of free volume content with the decrease of cooling rates in spite of the increase of nanocrystallization fraction, which further confirm that free volume plays a crucial role in the deformation process of the BMGs. [ABSTRACT FROM AUTHOR]

Alternating current (ac) electric-field-induced microstructures and electrohydrodynamic convection properties were studied for a guest-host liquid crystal (LC) system. The LC (MBBA) was doped with a newly synthesized azo-dye and filled in a LC cell. When the applied ac electric-field voltage was fixed at 13.5 V (Vrms), microstructures in the LC cell varied with the frequency (f) of the electric field. The probed He-Ne laser light displayed a hexagonal diffracted pattern when f=4.3 Hz, a square symmetry pattern when f=17.38 Hz, and a new hexagonal symmetry pattern when f=34.07 Hz. The first-order diffraction intensities along the x-axis direction (I1-x(t)) and y-axis direction (I1-y(t)) showed different time evolution tendency. At the same time, the phase shift (φ) between I1-x(t) and second-order diffraction intensity I2-x(t) was found to be dependent on the frequency. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the residual stress on the fatigue performance of a welded structure under multiaxial loading modes is studied. First, the local stress state at weld toe is modified via introduction of the residual stress, and a new fatigue life estimation model considering the effect of the residual stress is established by modifying our recently proposed critical plane method. Second, the basic theory and procedure of the finite element simulation on the calculation of the welding residual stress are presented. Finally, a numerical simulation of an aluminum alloy flange-to-tube welding process is conducted, and the calculated residual stress is verified with X-ray diffraction measurement. Furthermore, the performance of the proposed fatigue life estimation model is verified by the experimental data obtained in the fatigue test under different loading modes. It confirms that the consideration of the residual stress is important, especially under the out-of-phase loading mode. [ABSTRACT FROM AUTHOR]

Abstract: The sudden enhancements of magnetic strength, named magnetic peaks (MPs), are often observed in the magnetosheath of magnetized planets. They are usually identified as flux ropes (FRs) or magnetic mirror mode structures. Previous studies of MPs are mostly on the magnetohydrodynamics (MHD) scale. In this study, an electron scale MP is reported in the Earth magnetosheath. We present a typical case with a scale of ~7 electron gyroradii and a duration of ~0.18 s. A strong magnetic disturbance and associated electrical current are detected. Electron vortex is found perpendicular to the magnetic field line and is self‐consist with the peak. We use multipoint spacecraft techniques to determine the propagation velocity of the MP structure and find that the magnetic peak does propagate relative to the plasma (ion) flow. This is very different from the magnetic mirror mode that does not propagate relative to the plasma flow. Furthermore, we developed an efficient method that can effectively distinguish “magnetic bottle like” and “FRs like” structures. The MP presented in this study is identified as magnetic bottle like type. The mechanism to generate the electron scale magnetic bottle like structure is still unclear, suggesting that new theory needs to be developed to understand such small‐scale phenomena. [ABSTRACT FROM AUTHOR]

From February to October 2016, a total of 9,754 fish specimens were collected from the Yiluo River, a tributary of the Yellow River, China's second longest river. Based on these samples, length-weight relationships ( LWRs) and length-length relationships ( LLRs) were estimated for 26 species. Among these data, LWRs for 1 species, LLRs for 11 species, and maximum total lengths for six species were not previously recorded in FishBase. The a values of the LWRs varied between 0.0019 and 0.0116, and b values from 2.805 to 3.883. All regressions for LWRs and LLRs were highly significant ( p < .001). These results will be useful for sustainable management and conservation of the fish resources in the Yiluo River and the Yellow River ecosystem. [ABSTRACT FROM AUTHOR]

The generation of banded chorus by a two-component energetic electron distribution in a mirror-like inhomogeneous magnetic field is investigated in this work by a 1D hybrid code DAWN. A previous study by Liu et al. [Geophys. Res. Lett. 38, L14108 (2011)] suggested that banded chorus waves can be independently generated by two energetic electron populations. In this work, we first conduct a series of simulations to confirm that the starting frequency of chorus elements is close to the frequency of maximum linear growth rate. With carefully chosen simulation parameters, we then successfully generate banded chorus with a gap near half the electron gyrofrequency. By expanding the parameter range, however, we demonstrate that the gap can be located at frequencies other than the half electron gyrofrequency. We conclude that though the previous mechanism proposed by Liu et al. [Geophys. Res. Lett. 38, L14108 (2011)] can explain the relative independence of upper band and lower band chorus, further work is needed to explain why the linear properties of energetic electrons in the magnetosphere should produce a gap at 0.5Ωe0. [ABSTRACT FROM AUTHOR]

In this communication, we have carried out a detailed investigation of radiative recombination in n-GaAs homojunction far-infrared detector structures with multilayer emitter (n[sup +])-intrinsic (i) interfaces by temperature-dependent steady-state photoluminescence measurements. The observation of the emitter-layer luminescence structures has been identified from their luminescence characteristics, in combination with high density theoretical calculation. A photogenerated carrier transferring model has been proposed, which can well explain the dependencies of the luminescence intensities on the laser excitation intensity and temperature. Furthermore, the obtained radiative recombination behavior helps us to offer a proposal to improve the operating temperature of the detector. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A profile-evolving simulation of the Controlled Shear Decorrelation Experiment (CSDX) linear device is performed with our newly developed code. The simulation result shows an excellent agreement with the experimental observations of profiles and fluctuations of plasma density and electric potential in the B=1000 G standard discharges, suggesting the mechanism of their evolutions. According to our simulation, an avalanche of plasma density, featuring a rapid destruction of particle profile, is triggered every time the dominant instability transits from near adiabatic collisional drift wave to non-adiabatic Kelvin-Helmholtz instability. The avalanches always start at the point where the local vorticity is the maximum among the whole device. A critical vorticity is found for any avalanche to happen. The avalanches always lead to intermittent particle and heat convective structures outside the main plasma column, and these structures are ejected out as avaloids when zonal flow intensity at birth time is weak. [ABSTRACT FROM AUTHOR]

The temperature dependence of the ferroelectric and dielectric properties of PbZr[sub 0.5]Ti[sub 0.5]O[sub 3] thin films deposited on LaNiO[sub 3]-coated SrTiO[sub 3] substrate was investigated. The results showed that both the saturation polarization and remanent polarization increased with decreasing temperature from 300 to ∼50 K, and decreased as the temperature continued to decrease below 40 K. The capacitance of the PbZr[sub 0.5]Ti[sub 0.5]O[sub 3] ferroelectric thin film capacitor as a function of small ac field and temperature was measured, and the data were processed using Rayleigh law. It was demonstrated that both the reversible and irreversible contributions to the dielectric constant decreased with decreasing temperature; however, they showed an increase when the temperature dropped below 50 K. The anomalous behavior of the temperature dependence may be attributed to a phase transition in the PbZr[sub 0.5]Ti[sub 0.5]O[sub 3] thin film in the vicinity of 50 K. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This paper proposes a novel analysis method of stochastic crack trajectory based on a dimension reduction approach. The developed method allows efficiently estimating the statistical moments, probability density function and cumulative distribution function of the crack trajectory for cracked elastic structures considering the randomness of the loads, material properties and crack geometries. First, the traditional dimension reduction method is extended to calculate the first four moments of the crack trajectory, in which the responses are eigenvectors rather than scalars. Then the probability density function and cumulative distribution function of the crack trajectory can be obtained using the maximum entropy principle constrained by the calculated moments. Finally, the simulation of the crack propagation paths is realized by using the scaled boundary finite element method. The proposed method is well validated by four numerical examples performed on varied cracked structures. It is demonstrated that this method outperforms the Monte Carlo simulation in terms of computational efficiency, and in the meanwhile, it has an acceptable computational accuracy. [ABSTRACT FROM AUTHOR]

Ion acceleration from the interaction of two intersecting intense laser pulses with an overdense plasma is investigated using a three-dimensional particle-in-cell simulation. It is found that, comparing with the single-pulse case, the charge of the resulting energetic ion bunch can be increased by more than an order of magnitude without much loss of quality. Dependence of the ion charge on the interaction parameters, including separation distance and incidence angles of the lasers, is considered. It is shown that the charge of the accelerated ion bunch can be optimized by controlling the degree of laser overlapping. The improved performance can be attributed to the enhanced laser intensity as well as stochastic heating of the accelerated electrons. Since at present the intensity of readily available lasers is limited, the two pulse scheme should be useful for realizing higher laser intensity in order to achieve higher-energy target normal sheath acceleration ions. [ABSTRACT FROM AUTHOR]

The magnetic curvature effects on plasma interchange turbulence and transport in the Z-pinch and dipole-like systems are explored with two-fluid global simulations. By comparing the transport levels in the systems with a different magnetic curvature, we show that the interchange-mode driven transport strongly depends on the magnetic geometry. For the system with large magnetic curvature, the pressure and density profiles are strongly peaked in a marginally stable state and the nonlinear evolution of interchange modes produces the global convective cells in the azimuthal direction, which lead to the low level of turbulent convective transport. [ABSTRACT FROM AUTHOR]

Manipulating molecular assembly is significant for achieving materials with desirable performances. In this paper, two nonionic surfactants, Span 20 and Triton X-100, are used to tune the nucleation and fiber growth of a molecular gelator 2,3-di-n-decyloxyanthracene (DDOA). Confocal microscopic images show that Span 20 induces elongation of DDOA spherulites, and promotes fiber side branching. In contrast, Triton X-100 enhances the primary nucleation of DDOA leading to the formation of smaller DDOA spherulites, and promotes fiber tip branching. ¹H NMR investigation demonstrates strong interactions between the hydrophobic tails of the surfactants and the alkyl chains of DDOA molecules. The interactions significantly reduce the diffusion of DDOA molecules. The different effects of the two surfactants could be attributable to their different alkyl hydrophobic tails. The hydrophobic tail of Span 20 is similar to the alkyl chain of DDOA, which could promote the adsorption of Span 20 on the fiber side surface rich in alkyl chains of DDOA.While the benzene ring in the hydrophobic tail of Triton X-100 could facilitate the primary nucleation of DDOA and the adsorpion of Triton X-100 on the fiber tip surface rich in aromatic structure of DDOA. The observations of this work will help the development of a convenient approach to tune the fiber network structure of molecular gels. [ABSTRACT FROM AUTHOR]

Fluctuation-induced E × B shear flow and energy transfer for plasma interchange turbulence are examined in a flux-driven system with both closed and open magnetic field lines. The nonlinear evolution of interchange turbulence shows the presence of two confinement regimes characterized by low and high E × B flow shear. In the first regime, the large-scale turbulent convection is dominant and the mean E × B shear flow is at a relatively low level. By increasing the heat flux above a certain threshold, the increased turbulent intensity gives rise to the transfer of energy from fluctuations to mean E × B flows. As a result, a transition to the second regime occurs, in which a strong mean E × B shear flow is generated. [ABSTRACT FROM AUTHOR]

Electron injection into the wakefield of an intense short laser pulse by a weaker laser pulse propagating in the opposite direction is reconsidered using two-dimensional (2D) particle-in-cell simulations as well as analytical modeling. It is found that for linearly polarized lasers the injection efficiency and the quality of the wakefield accelerated electrons increase with the intensity of the injection laser only up to a certain level, and then decreases. Theory and simulation tracking test electrons originally in the beat region of the two laser pulses show that the reduction of the injection efficiency at high injection-laser intensities is caused by stochastic overheating of the affected electrons. [ABSTRACT FROM AUTHOR]

The collision of wake bubbles behind two counterpropagating laser pulses in rarefied plasma is investigated using particle-in-cell simulation. Special attention is paid to the highly nonlinear dynamics of the electrons in the interaction region. It is found that, as the two bubbles approach each other and collide, the electrons in the interaction region first oscillate in a periodic fashion, forming a quasistationary dense electron density ripple with fairly regular spatial structure. At longer times, the electron motion becomes chaotic, and the density grating is gradually smeared. The electrons escape in the transverse direction, and eventually the two bubbles merge to form a single one. The transition of the electron motion from regular to chaotic is confirmed by analytical modeling using test electrons moving in counterpropagating planar electromagnetic waves. The findings shed light on the dynamics of wake-bubble collisions and the complex behavior induced by multiple laser pulses in plasmas. [ABSTRACT FROM AUTHOR]

Three-dimensional fast magnetic reconnection driven by two ultraintense femtosecond laser pulses is investigated by relativistic particle-in-cell simulation, where the two paralleled incident laser beams are shot into a near-critical plasma layer to form a magnetic reconnection configuration in self-generated magnetic fields. A reconnection X point and out-of-plane quadrupole field structures associated with magnetic reconnection are formed. The reconnection rate is found to be faster than that found in previous two-dimensional Hall magnetohydrodynamic simulations and electrostatic turbulence contribution to the reconnection electric field plays an essential role. Both in-plane and out-of-plane electron and ion accelerations up to a few MeV due to the magnetic reconnection process are also obtained. [ABSTRACT FROM AUTHOR]

Error-field penetration in reversed magnetic shear (RMS) configurations is numerically investigated by using a two-dimensional resistive magnetohydrodynamic model in slab geometry. To explore different dynamic processes in locked modes, three equilibrium states are adopted. Stable, marginal, and unstable current profiles for double tearing modes are designed by varying the current intensity between two resonant surfaces separated by a certain distance. Further, the dynamic characteristics of locked modes in the three RMS states are identified, and the relevant physics mechanisms are elucidated. The scaling behavior of critical perturbation value with initial plasma velocity is numerically obtained, which obeys previously established relevant analytical theory in the viscoresistive regime. [ABSTRACT FROM AUTHOR]

Cs2.5H0.5PW12O40 supported on palygorskite (CsHPW/Pa) were synthesized and characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy. CsHPW inside CsHPW/Pa was retained intact Keggin anion and highly and uniformly supported on the fiber of Pa, which performed stable catalytic activity for esterification of oleic acid with ethanol. Under optimum conditions, the following amounts were reached: 20%CsHPW/Pa catalyst, 80°C, 8 h, molar ratio (ethanol to oleic acid) 10:1, catalyst amount 8 wt% (in relation to the oleic acid mass), removal water agents amount 50 g/mol (basis on the oleic acid molar), and the conversion of oleic acid reached 73%. [ABSTRACT FROM PUBLISHER]

Esterification of oleic acid with methanol was investigated using tungstophosphoric acid (H3PW12O40) immobilized on the 3-aminopropyltriethoxysilane (H2N(CH2)3Si(OC2H5)3) functionalized palygorskite. Among different loading catalysts, 15% (w/w) H3PW12O40 immobilized onto functionalized palygorskite showed stable and substantially high activity with about 90% oleic acid conversion. Immobilized catalysts were characterized by X-ray photoelectron spectroscopy, X-ray diffraction, and temperature programmed desorption of NH3 for their surface element compositions and chemical states, crystallization, and acid strength, respectively. Characterization results indicated that H3PW12O40 was chemically and uniformly dispersed on modified palygorskite. [ABSTRACT FROM PUBLISHER]

The location of magnetic reconnection in the midtail during a substorm was studied in many researches. Here we present multi-point THEMIS observations of a reconnection event in the near-Earth magnetotail during substorm. In this event, THEMIS probes stayed in the near-Earth and midtail region aligning along the magnetotail. This allows reconnection evolution to be probed simultaneously from about -10RE to -23RE down tail. The Hall current related electron streams were observed at the same time by two probes far away from the reconnection site. Before near-Earth reconnection involved the tail lobe magnetic field, the reconnection site was restricted in earthward -23RE. When reconnection involved into the tail lobe region, the reconnection site started to retreat gradually. [ABSTRACT FROM AUTHOR]

A model of turbulence intensity spreading with self-consistent nonlinear noise is derived systematically for the simple dynamical model of resistivity gradient driven turbulence. Local effective drive, thermal conduction damping, nonlinear coupling, and spatial scattering effects are included. As a consequence of nonlinear mode coupling processes (i.e., triad mode interactions), turbulence energy can be spatially scattered, leading to turbulence propagation and spreading. However, the range of any nonlinear mode interactions of the background with a test mode is restricted to within a few mode scale widths from the test mode rational surface. The speed of a turbulent spreading front is calculated. This front speed is effectively constant on macroscopic scales. We show that the effect of self-consistent nonlinear noise on the intensity front speed is modest, as a consequence of the ordering Δc

Guiding of laser pulse in uniform plasmas and preformed plasma channels is investigated. The self-guiding mechanisms for these two cases are quite different. It is found that an intense laser pulse can be steadily self-guided in underdense plasmas with nearly a constant spot size if the self-consistently generated electron cavity has a sufficiently steep density gradient at the edge. In a preformed plasma channel, however, laser guiding is maintained mainly by the balance between the light diffraction and focusing. The latter is induced by the wall plasmas which greatly reduce the local dielectric constant. It is shown that the self-guiding of a laser pulse in uniform plasmas requires tens of terawatts power, but those that are in preformed channels can be realized with only a terawatt power. [ABSTRACT FROM AUTHOR]

A cylindrical magnetohydrodynamic model including plasma pressure and longitudinal flow has been employed for the study of resistive wall mode (RWM) in reversed field pinch (RFP) plasmas. In order to validate the model, a careful comparison with the experimental measurements in RFX-mod [P. Sonato et al., Fusion Eng. Des. 66–68, 161 (2003)] on the mode growth rates has been made by well matching the equilibrium parameters F, Θ, and βp. The RWM instability spectrum, which varies with the equilibrium parameters, is also calculated for comparison. The sensitivity of the mode growth rate to the equilibrium parameters is studied in details. It is concluded that the model can provide consistent accuracy in studies of RWM in RFP plasmas. The analysis based on the balance of the potential energy components has been carried out in order to obtain the physical understanding on the mode behavior. [ABSTRACT FROM AUTHOR]

As a method of post-transcriptional gene silencing (PTGS), virus-induced gene silencing (VIGS) became a powerful tool for the study of gene function in plants. Current researches are focused on unraveling the mechanisms of PTGS, finding novel viral vectors and new infection methods in order to broaden the host species spectrum, and establishing the new reporter gene system of VIGS to demonstrate gene silencing, as well as developing the high-throughput silencing for genomic scale research. The aim of this review is to bring together recent advances of VIGS, an attractive method, for understanding it in the study of plants. [ABSTRACT FROM AUTHOR]

Nonlinear characteristics including spatial chaos and patterns associated with relativistically intense laser-plasma interaction are studied theoretically and numerically using a model relativistic nonlinear Schrödinger equation. It is shown that in the phase space irregular homoclinic orbit crossings exist. The latter are verified and investigated numerically. The spatial chaos and complex patterns of the laser wave field can be attributed to the relativistic electron mass variation as well as the ponderomotive-force driven electron-density modulation. The formation of complex patterns results from stochastic partition of energy in the Fourier modes. [ABSTRACT FROM AUTHOR]

Based on the word-lift technique of symbolic dynamics of one-dimensional unimodal maps, we investigate the relation between chaotic kneading sequences and linear maximum-length shift-register sequences. Theoretical and numerical evidence that the set of the maximum-length shift-register sequences is a subset of the set of the universal sequence of one-dimensional chaotic unimodal maps is given. By stabilizing unstable periodic orbits on superstable periodic orbits, we also develop techniques to control the generation of long binary sequences. [ABSTRACT FROM AUTHOR]

Both the poloidal magnetic field (Bp) and radial electric field (Er) are significant in magnetic confinement devices. In this paper, a new method was proposed to diagnose both Bp and Er at the same time, which was named Laser-accelerated Ion-beam Trace Probe (LITP). This method based on the laser-accelerated ion beam, which has three properties: large energy spread, short pulse lengths, and multiple charge states. LITP can provide the 1D profiles, or 2D images of both Bp and Er. In this paper, we present the basic principle and some preliminary theoretical results. [ABSTRACT FROM AUTHOR]

A new concept of Heavy Ion Beam Probe (HIBP) diagnostic has been proposed, of which the key is to replace the electrostatic accelerator of traditional HIBP by a laser-driven ion accelerator. Due to the large energy spread of ions, the laser-accelerated HIBP can measure the two-dimensional (2D) electron density profile of tokamak plasma. In a preliminary simulation, a 2D density profile was reconstructed with a spatial resolution of about 2 cm, and with the error below 15% in the core region. Diagnostics of 2D density fluctuation is also discussed. [ABSTRACT FROM AUTHOR]

In the present Letter, efficient organic light-emitting diodes (OLEDs) with tris(8-hydroxyquinolino) aluminum (Alq3) as a single-active layer have been prepared by using a series of fluoropolymer buffer layers. The OLEDs with a 10-nm-thick poly(tetrafluroethylene-perfluoroalkylvinylethers) (PFA) buffer layer had a current efficiency of 4.46 cd/A at a current density of 2000 A/m2, whereas conventional double-layer OLEDs with N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (NPB) and Alq3 showed a current efficiency of only 3.81 cd/A at the same condition in our experiment. The effect of the insulating fluoropolymer buffer layers could be interpreted to enhance hole injection and improve carrier balance. [ABSTRACT FROM AUTHOR]

We examine the influence of noise and Alfvén wave turbulence on magnetic reconnection in a reduced magnetohydrodynamics model. We focus on the dynamics of magnetic helicity density. Helicity conservation is then used to calculate the global reconnection rate in terms of the helicity density flux. Two specific scenarios are explored—noisy reconnection and Alfvén wave turbulent reconnection. For noisy reconnection, the current sheet is assumed to sit in a noisy state, marginal to plasmoid formation instability. The scaling of the reconnection rate in the presence of noise is proportional to (S20/VAL2)1/11, where S20/VAL2 is the relative amplitude of the noise. We obtain this prediction using a symmetry analysis of the helicity density flux. For Alfvén wave turbulent reconnection, a mean field closure scheme is applied. A reconnection rate proportional to is obtained, where and 〈 B〉 are the relative energy of Alfvén wave turbulence and the reconnecting field. The constraint on reconnection rate enforced mean-square magnetic potential conservation is reexamined. A critical magnetic Reynolds number Rm, c is identified. For Rm ≫ Rm, c, the reconnection rate becomes independent of Spitzer resistivity and thus can be higher than the Sweet-Parker model prediction. Both cases exhibit a weak dependence of the reconnection rate on the amplitude of the turbulence. Therefore, even noise or weak turbulence can trigger fast reconnection if the system is marginally stable. The important distinction between turbulent reconnection and turbulent dissipation of magnetic energy is also discussed. [ABSTRACT FROM AUTHOR]

We have used proton-implantation-induced intermixing and a passivation effect to enhance the light-emission efficiency in multilayer InAs/GaAs quantum dots (QDs). Photoluminescence (PL) spectroscopy is used to study both the intermixing and passivation effects. Besides the blueshift of the luminescence peak due to the intermixing-induced energy band variation, a six times higher PL intensity increase is observed, relative to that of as-grown QDs, with a proton implantation dose of 5 × 10[SUP13] cm[SUP-2] followed by rapid thermal annealing at 700°C. These effects are beneficial to both the quantum efficiency and the wavelength tuning of optoelectronic devices. [ABSTRACT FROM AUTHOR]

The electronic states in PbSe/Pb[sub 0.934]Sr[sub 0.066]Se multiple-quantum-well structures (MQWs) grown by molecular-beam epitaxy have been investigated both theoretically and experimentally for the midinfrared laser applications. With the aid of combined temperature-dependent photoluminescence and absorption measurements on a Pb[sub 0.934]Sr[sub 0.066]Se thin film for the effective masses and temperature-dependent band gaps, we find that the PbSe/PbSrSe MQWs have type-I band alignment and the conduction band offset ratio is Q[sub c]=0.82±0.03. The calculation, taking into account the strain, carrier confinements, and the multivalley band structure, can well explain both the observed luminescence peak energies and the temperature coefficient of the luminescence peaks as a function of well thickness. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Transition dynamics and mean shear flow generation in plasma interchange turbulence are explored in a flux-driven system that resembles the plasma edge region. The nonlinear evolution of the interchange mode shows two confinement regimes with different transport levels. Large amplitude oscillations in the phase space of turbulence intensity and mean flow energy are observed and investigated. Both clockwise and counterclockwise oscillations occur during the transition between the two regimes. The Reynolds stress gradients are shown to play a critical role in the generation of mean sheared flows in the edge region. Both the forward and back transitions are simulated self-consistently and a significant hysteresis is found. [ABSTRACT FROM AUTHOR]

The dynamics of magnetic reconnection (MR) in the high-energy-density (HED) regime, where the plasma inflow is strongly driven and the thermal pressure is larger than the magnetic pressure (β>1), is reexamined theoretically and by particle-in-cell simulations. Interactions of two colliding laser-produced plasma bubbles with self-generated poloidal magnetic fields of, respectively, antiparallel and parallel field lines are considered. Through comparison, it is found that the quadrupole magnetic field, bipolar poloidal electric field, plasma heating, and even the out-of-plane electric field can appear in both cases due to the mere plasma bubble collision, which may not be individually recognized as evidences of MR in the HED regime separately. The Lorentz-invariant scalar quantity De≃γej·(E+ve×B) {γe = [1−(ve/c)2]−1/2}in the electron dissipation region is proposed as the key sign of MR occurrence in this regime. [ABSTRACT FROM AUTHOR]