bluuebunny/crossref_metadata_2025 huggingface dataset:
Zur internationalen Verbreitung der Sozialpsychologie aus dem deutschsprachigen Bereich
Authors: Krampen Günter , Schui Gabriel , Montada Leo
Published: July 2004

Zusammenfassung: Unter Bezug auf die Internationalisierungsdebatte in der Psychologie wird die internationale Verbreitung der Sozialpsychologie aus dem deutschsprachigen Bereich mit dem Gesamt aller anderen psychologischen Teildisziplinen verglichen. Bibliometrische Untersuchungsbefunde belegen einen markanten Anstieg des Anteils englischsprachiger Publikationen aus der Sozialpsychologie seit 1980, der die entsprechenden Anteile aus dem Gesamt der anderen Teildisziplinen mit etwa dem Zweifachen deutlich übertrifft und in der sozialen Kognitionsforschung am ausgeprägtesten ist. Zitationsanalysen weisen darauf, dass Publikationen aus der Sozialpsychologie in englischen Fachzeitschriften im Durchschnitt häufiger zitiert werden als die Veröffentlichungen aus dem Gesamt der anderen Teildisziplinen. Nach den Befunden einer E-Mail-Befragung (N = 564) liegen die internationalen Stärken der Sozialpsychologie bei der Anzahl englischer Publikationen sowie internationalen “Peer-review”-Tätigkeiten, Verbandsmitgliedschaften, Gastaufenthalten und Forschungskooperationen.
Thermochemical structures within a spherical mantle: Superplumes or piles?
Authors: McNamara Allen K. , Zhong Shijie
Published: July 2004

Heterogeneous compositional mantle models are frequently invoked to explain some observations obtained from geochemistry and seismology. In particular, two regions in the Earth's lower mantle, under the Pacific and Africa, are often interpreted as being either piles or superplumes of dense material. We perform numerical modeling of thermochemical convection in a three‐dimensional spherical geometry to investigate whether the geometry can focus a dense chemical component into a small number of isolated, rounded piles or superplumes of material. We study the effect of temperature and compositionally dependent viscosity, and we find two different modes of dense layer deformation. Temperature‐dependent rheology leads to a low‐viscosity dense layer which is passively swept aside by downwellings into linear piles that are spread throughout the entire lower mantle. The addition of compositionally dependent rheology in which the dense layer is more viscous results in active deformation of the dense material, forming large, isolated superplumes. Our results indicate that piles and superplumes are separate features which, in general, do not occur together and, in order for isolated, rounded superplumes to form, an intrinsic compositional viscosity increase is required for the dense material.
A case study of stratosphere‐troposphere exchange during the 1996 North Atlantic Regional Experiment
Authors: McCaffery S. J. , McKeen S. A. , Hsie E.‐Y. , Parrish D. D. , Cooper O. R. , Holloway J. S. , Hübler G. , Fehsenfeld F. C. , Trainer M.
Published: July 2004

Passive tracers are employed in a relatively high spatial and temporal resolution three‐dimensional transport model to analyze a stratosphere‐troposphere exchange (STE) event over the eastern United States and western North Atlantic Ocean. The model is validated against measurements taken on board the National Oceanic and Atmospheric Administration WP‐3D Orion aircraft during the North Atlantic Regional Experiment study in the spring of 1996. Overall, the model reproduces the measurements well during the early part of the flight where there is indication of a small stratospheric intrusion. However, the very strong signatures of STE and mixing contained in the measurements later in the flight are not captured. Use of a finer horizontal resolution (20 km as opposed to 60 km) brings the model results closer to the aircraft measurements and yields higher values (50% at 7–8 km altitude) of ozone, O3, with a deeper penetration into the troposphere (20% at 80–120 ppbv levels).
A study of the global cycle of carbonaceous aerosols in the LMDZT general circulation model
Authors: Reddy M. Shekar , Boucher Olivier
Published: July 2004

The global atmospheric cycle of carbonaceous aerosols is simulated in the Laboratoire de Météorologie Dynamique general circulation model, and the subsequent aerosol optical depth is estimated for the period 1997 to 1999. The seasonal and interannual variability in the open biomass burning emissions has been improved by combining existing emission inventories and satellite measured fire counts. The model performance has been thoroughly evaluated against measured aerosol mass concentrations and optical depth in different regions of the globe. At a majority of locations, the modeled mass concentrations of black carbon (BC) at the surface are within a factor of two of observed values. The concentrations of organic carbon (OC) are generally underestimated in comparison to measurements. The discrepancies between model predicted values and measurements are attributable to the difference in time periods between the measurements and model simulations and/or a real underestimation of aerosol emissions in the model. The atmospheric residence times of both BC and OC aerosols are about a week. The hydrophilic fraction of carbonaceous aerosols accounts for about 90% of the total burden. Organic matter (OM) and associated water dominate the optical depth by carbonaceous aerosols with a 86% contribution (global mean of 0.031 at 0.55 μm). Different sensitivity experiments on the transformation time for conversion of hydrophobic to hydrophilic aerosols and emission partitioning show significant changes in the distribution of aerosol burdens and optical depth. The globally averaged burdens change by ±15% and residence times are shorter or longer by about 1 day in the various experiments as compared to the control simulation. In all of these experiments the largest sensitivity in aerosol concentrations is found in the remote regions and in the free troposphere (pressure range of 700–400 hPa). Emissions from biomass burning dominate the burden and optical depth of carbonaceous aerosols in the entire SH and NH tropics, while fossil fuel emissions dominate the NH extratropics. On the global scale biomass burning accounts for 78% of the total carbonaceous aerosol burden (BC + OM) followed by natural secondary organic aerosols (SOA)(14%) and fossil fuels (8%). The contributions to corresponding AOD are similar with the largest contribution from biomass burning (76%) followed by natural SOA (14%), and fossil fuels (10%).
Tectonic and lithologic controls on bedrock channel profiles and processes in coastal California
Authors: Duvall Alison , Kirby Eric , Burbank Douglas
Published: July 2004

Recent theoretical models suggest that topographic characteristics of bedrock channels are products of interactions among tectonics, substrate resistance, and the climatically modulated erosive ability of the river. The degree to which these factors influence the form of channel profiles is poorly quantified at present. Here we investigate bedrock channels developed across the southern flank of the Santa Ynez Mountains, California. Uniform climate and systematic variations in lithology and rock uplift rate along the range allow comparison of channel morphology between (1) channels eroding rocks of uniform and nonuniform strength and (2) channels experiencing differences in tectonic forcing. We combine field observations, surveys, and analysis of digital data to determine topographic and hydraulic characteristics of bedrock channels. At a constant rock uplift rate, streams flowing from resistant to less resistant bedrock exhibit highly concave profiles and increased gradients along lower reaches relative to channels developed in uniform bedrock. These effects are interpreted as responses to (1) an increase in substrate resistance to channel incision in the upper reaches and (2) transport‐limited gradients along lower reaches. Comparisons of channels developed across uniform lithology but experiencing an approximately sevenfold difference in rock uplift rate reveal an approximately twofold increase in gradient and an approximately threefold decrease in width. In this landscape the combined channel adjustments of gradient and width are consistent with a fluvial incision model in which channel incision rate is linearly proportional to mean bed shear stress.
Observation of magnetospheric relativistic electrons accelerated by Pc‐5 ULF waves
Authors: Tan Lun C. , Fung Shing F. , Shao Xi
Published: July 2004

Magnetic field, electric field and energetic electron measurements from CRRES, GOES‐6 and ‐7 satellites are used to investigate the production of up to 2 MeV electron fluxes through a storm sudden commencement (SSC) event on August 27, 1991. Strong Pc‐5 oscillations, whose electric field is mainly along the radial direction, and up to an order‐of‐magnitude enhancement in relativistic electron fluxes occurred simultaneously in a two‐hour period. The enhanced electron fluxes are found to have a pancake‐like pitch angle distribution, which is consistent with the fluxes being accelerated near the equatorial plane. The electron acceleration is shown to result from drift‐resonant interactions with the toroidal‐mode Pc‐5 ULF waves having wave frequencies three times the electron drift frequency. In view of the L‐variation of ULF wave frequencies, electron acceleration to relativistic energies becomes more effective in the geosynchronous region.
Cross‐field energy transfer of a body Alfvén wave propagating along and across a pressure‐balanced structure
Authors: Vasquez Bernard J. , Hollweg Joseph V.
Published: July 2004

We conduct hybrid numerical simulations with particle protons and fluid electrons of a low‐frequency, planar (body) and shear Alfvén wave imbedded in a smoothly varying cross‐field pressure‐balanced structure which provides a wave‐speed gradient. We consider wave propagation directions starting at 90°, which resembles the case of a surface wave, and less than 90° with respect to the gradient direction. We find that the planar Alfvén wave undergoes resonant absorption. When the propagation direction is less than 90°, we show that there are resonant field lines which can actually lose wave energy to other neighboring resonant field lines, which is a situation that has not been encountered in previous work with surface waves. A consequence of this process is an overall faster development time for smaller scales perpendicular to the magnetic field through phase mixing and potentially faster dissipation of these generated scales in coronal and solar wind plasma.
Coherent variability of the Norwegian Atlantic Slope Current derived from TOPEX/ERS altimeter data
Authors: Skagseth Øystein , Orvik Kjell Arild , Furevik Tore
Published: July 2004

This study deals with large‐scale variability of the Norwegian Atlantic Current (NwAC) transporting warm and saline Atlantic water toward the Arctic Ocean. We concentrate on the eastern branch of the NwAC, the Norwegian Atlantic Slope Current (NwASC), an about 3500 km long, nearly barotropic shelf edge current. Comparison of variations of cross‐slope sea level gradient based on the CLS TOPEX/ERS altimeter data and the NwASC from direct current measurements 1995–2002 in the Svinøy section at about 63°N shows significant coherence for periods of 1 to 12 months. Motivated by this the analysis is extended to the entire NwASC using the local cross‐slope sea level gradient from the altimeter data as a proxy. The leading NwASC mode represents along‐slope current variations of similar sign from the Irish‐Scottish shelf to the Fram Strait that can be interpreted as a quasi‐steady, direct response to the large‐scale wind field.
Impact of a revised convective triggering mechanism on Community Atmosphere Model, Version 2, simulations: Results from short‐range weather forecasts
Authors: Xie Shaocheng , Zhang Minghua , Boyle James S. , Cederwall Richard T. , Potter Gerald L. , Lin Wuyin
Published: July 2004

This study implements a revised convective triggering condition in the National Center for Atmospheric Research (NCAR) Community Atmosphere Model, Version 2 (CAM2), model to reduce its excessive warm season daytime precipitation over land. The new triggering mechanism introduces a simple dynamic constraint on the initiation of convection that emulates the collective effects of lower level moistening and upward motion of the large‐scale circulation. It requires a positive contribution from the large‐scale advection of temperature and moisture to the existing positive convective available potential energy (CAPE) for model convection to start. In contrast, the original convection triggering function in CAM2 assumes that convection is triggered whenever there is positive CAPE, which results in too frequent warm season convection over land arising from strong diurnal variation of solar radiation. We examine the impact of the new trigger on CAM2 simulations by running the climate model in numerical weather prediction (NWP) mode so that more available observations and high‐frequency NWP analysis data can be used to evaluate model performance. We show that the modified triggering mechanism has led to considerable improvements in the simulation of precipitation, temperature, moisture, clouds, radiations, surface temperature, and surface sensible and latent heat fluxes when compared to the data collected from the Atmospheric Radiation Measurement (ARM) Program at its Southern Great Plains (SGP) site. Similar improvements are also seen over other parts of the globe. In particular, the surface precipitation simulation has been significantly improved over both the continental United States and around the globe; the overestimation of high clouds in the equatorial tropics has been substantially reduced; and the temperature, moisture, and zonal wind are more realistically simulated. Results from this study also show that some systematic errors in the CAM2 climate simulations can be detected in the early stage of model integration. Examples are the extremely overestimated high clouds in the tropics in the vicinity of Intertropical Convergence Zone and the spurious precipitation maximum to the east of the Rockies. This has important implications in studies of these model errors since running the climate model in NWP mode allows us to perform a more in‐depth analysis during a short time period where more observations are available and different model errors from various processes have not compensated for the systematic errors.
Cenozoic pelagic Sr/Ca records: Exploring a link to paleoproductivity
Authors: Billups K. , Rickaby R. E. M. , Schrag D. P.
Published: July 2004

Recent studies have revealed that Sr/Ca ratios of coccolithophores may be affected by productivity. Here we compile published Sr/Ca data from bulk carbonate, fine fraction sediment, and planktonic foraminiferal Sr/Ca records that span the past 60 Myr and attempt to place these records into a paleoceanographic framework. We account for changes in seawater Sr/Ca ratios using the curve of Lear et al. [2003] and discuss our observations with respect to changes in the partitioning coefficient of Sr through time. We discuss limitations associated with postburial processes, temporal changes in the coccolith/planktonic foraminiferal rain ratio, and the coccolith species composition of the sediment. Despite these caveats, we are able to show that in the bulk and fine fraction carbonate records there are two broad periods of enhanced partitioning of Sr relative to today, the Oligocene, and the middle to late Miocene/early Pliocene. Because these are two intervals for which we can cite evidence for a relatively productive ocean on the regional or global scale, we believe that the Sr/Ca ratios of bulk carbonate can be explained, at least in part, by the effects of oceanic nutrient levels on Sr uptake during calcification of coccoliths, which make up the vast majority of these sediments. Within the limits of the inferred seawater Sr/Ca record the results of this study contribute a geologic perspective to recent laboratory and field studies that have raised the possibility that Sr incorporation into biogenic calcite is controlled by biogeochemical processes.
Inverse problem of multicomponent reactive chemical transport in porous media: Formulation and applications
Authors: Dai Zhenxue , Samper Javier
Published: July 2004

A general methodology for solving the inverse problem of multicomponent reactive solute transport in porous media is presented in this paper. In addition to prior information on model parameters the methodology relies on hydraulic heads, aqueous and total concentrations, water fluxes and water contents. The formulation is based on minimizing a generalized least squares criterion by means of a Gauss‐Newton‐Levenberg‐Marquardt method. The methodology copes with the simultaneous estimation of flow, transport, and geochemical parameters as well as initial and boundary pH, pE, and concentrations. It overcomes the limitations of the trial‐and‐error method and should enlarge the capabilities of hydrogeologists and hydrochemists to understand the complexities of reactive groundwater systems. This paper presents a mathematical and numerical formulation of the forward and inverse problems and illustrates its application to a synthetic experiment dealing with cation exchange and kinetically controlled calcite dissolution in a column. Parameter estimates are accurate when data are free of errors. Accurate solutions cannot be found, however, when synthetic data are corrupted with large lognormally distributed random noise unless prior information on model parameters is considered. Estimation improves significantly when prior information is taken into account, demonstrating its relevance for obtaining reliable parameter estimates. Solutions of the inverse problem for a real case study are presented, in which a stepwise inversion is proposed for identifying geochemical structures and estimating model parameters. This case deals with reactive solute transport in a column experiment performed by Appelo et al. [1990] in which the cation exchange complex of a clay sediment from the Ketelmeer aquifer was flushed with a SrCl2 solution. The inverse methodology has been found to be useful in investigating the relevance of calcite dissolution/precipitation under both local equilibrium and kinetic conditions.
Spin interference and nonideal effects on electron-electron collisions in nonideal plasmas
Authors: Jung Young-Dae
Published: July 2004

The spin interference and nonideal effects on electron-electron collisions are investigated in nonideal plasmas. An effective pseudopotential model taking into account the screening and nonideal effects is applied to describe the electron-electron interaction potential in nonideal plasmas. The total spin states of the collision system are considered to obtain high-energy electron-electron collision cross sections. The results show that the differential collision cross section is found to decrease with increasing nonideality plasma parameter γ in the region 0<γ<2 and, however, it increases in the region 2<γ<4. It is found that the spin interference and nonideal screening effects are especially important at the scattering angle θL=π/4. It should also be noted that the differential cross sections have minima near γ=2 and the nonideal effect is found to be more significant at the minima.
Response to “Comment on ‘Modified Zakharov equations in dusty plasmas with variable charges on dust particles’ ” [Phys. Plasmas 11, 4151 (2004)]
Authors: Tribeche Mouloud , Zerguini Taha Houssine
Published: July 2004

The comments [R. Annou, Phys. Plasmas 11, 4151 (2004)] are unfounded and are shown to be based on the complete misunderstanding of our article by the author. The claim of an incorrect analysis is strongly refuted and firmly rejected.
Particle flows in dusty plasmas of the tokamak edge
Authors: Tsypin V. S. , Vladimirov S. V. , Galvão R. M. O. , Nascimento I. C. , Tendler M. , Kuznetsov Y. K.
Published: July 2004

In this Brief Communication the plasma flows and ambipolar electric field induced due to the temperature stresses on ions are estimated. These flows are similar to the plasma “residual” rotations in tokamaks, but are related to dust contamination of tokamak plasmas. The induced electric field might be very important for creating transport barriers in tokamaks.
Oscillonic Mach cones in a dusty magnetoplasma
Authors: Shukla P. K. , Mamun A. A. , Eliasson B. , Morfill G. E.
Published: July 2004

The possibility for the formation of Mach cones in a dusty magnetoplasma containing elongated charged dust grains has been examined theoretically. It is predicted that the Mach cones can be formed by dipole oscillons (wave modes associated with the oscillations of dust dipoles around their mean positions) in a laboratory plasma containing elongated (rodlike) negatively charged dust grains. An experiment in radio-frequency dusty plasma discharges should be conducted for verifying the theoretical prediction that has been made here.
Tree-code simulations of proton acceleration from laser-irradiated wire targets
Authors: Gibbon P. , Beg F. N. , Clark E. L. , Evans R. G. , Zepf M.
Published: July 2004

Recent experiments using Terawatt lasers to accelerate protons deposited on thin wire targets are modeled with a new type of gridless plasma simulation code. In contrast to conventional mesh-based methods, this technique offers a unique capability in emulating the complex geometry and open-ended boundary conditions characteristic of contemporary experimental conditions. Comparisons of ion acceleration are made between the tree code and standard particle-in-cell simulations for a typical collisionless “hole boring” scenario in slab geometry. The utility of the gridless approach is emphasized by a series of simulations in “wire” geometry, in which electrons are permitted to circulate around the target at arbitrary distances from the focal region. The simulations reveal a number of features in common with recent experimental observations, including a disclike emission pattern of the MeV protons accelerated away from the wire.
Measurements and modeling of ion and neutral distribution functions in a partially ionized magnetically confined argon plasma
Authors: Michael C. A. , Howard J. , Blackwell B. D.
Published: July 2004

The influence of ion-neutral collisions on the ion and neutral distribution functions is studied in low field (<0.15 T) rf heated argon discharges of the H-1 Heliac [S. M. Hamberger, B. D. Blackwell, L. E. Sharp, and D. B. Shenton, Fusion Technol. 17, 123 (1990)], both experimentally and theoretically. The distribution function measurements are based on the Doppler broadening of plasma ion and neutral spectral lines using a novel coherence imaging camera. Measurements show that neutrals are abundant throughout the plasma. The neutral temperature is found to be in the range 1–2 eV, which, when compared with ion temperatures of the order of 10 eV, suggests that neutrals are being heated substantially through ion-neutral collisions. Measurements of the ion distribution function reveal a substantially elevated fraction of low energy particles (whose energy is similar to the neutral temperature), associated with charge exchange and ionization. In order to understand the origin of the high neutral temperature and distorted ion distribution function, the ion and neutral distribution functions are modeled using the Boltzmann equation including collision operators for ion-ion and ion-neutral collisions, ionization, heating, and particle loss. The simulation results compare well with the experimental results.
Improved confinement induced by tangential injection of compact torus into the Saskatchewan Torus-Modified (STOR-M) tokamak
Authors: Xiao C. , Hirose A. , Sen S.
Published: July 2004

Compact torus injection into the Saskatchewan Torus-Modified [Phys. Fluids B 4, 3277 (1992)] tokamak discharges has triggered improved confinement characterized by an increase in the electron density by more than twofold, 30% reduction in the Hα radiation level, significant suppression of floating potential fluctuations and m=2 Mirnov oscillations. In this paper, we present detailed experimental setup and results, as well as an extended theory explaining the mechanism for triggering improved confinement in a tokamak by compact torus injection.
Collisionless magnetic reconnection in the presence of a guide field
Authors: Ricci Paolo , Brackbill J. U. , Daughton W. , Lapenta Giovanni
Published: July 2004

The results of kinetic simulations of magnetic reconnection in Harris current sheets are analyzed. A range of guide fields is considered to study reconnection in plasmas characterized by different β values, β>me/mi. Both an implicit particle-in-cell (PIC) simulation method and a parallel explicit PIC code are used. Simulations with mass ratios up to the physical value are performed. The simulations show that the reconnection rate decreases with the guide field and depends weakly on the mass ratio. The off-diagonal components of the electron pressure tensor break the frozen-in condition, even in low β plasmas. In high β plasmas, evidence is presented that whistler waves play a key role in the fast reconnection physics, while in low β plasmas the kinetic Alfvén waves are important. The in-plane and the out-of-plane ion and electron motion are also considered, showing that they are influenced by the mass ratio and the plasma β.
Study on wall locking of multiple tearing modes in reversed field pinch plasmas
Authors: Guo S. C. , Chu M. S.
Published: July 2004

The nonlinear interactions between multiple unstable tearing modes and the resistive wall in reversed field pinch plasmas are studied. The nonlinear interactions include the nonlinear electromagnetic interaction between multiple modes, the effect of the eddy currents induced in the resistive wall by the magnetic perturbations of the multiple modes, and the effect of the angular momentum transport due to the viscous diffusion in the plasma. A set of fully time-dependent equations describing the dynamics of the three tearing modes (dynamo modes) has been employed and solved numerically by using the finite element method. Both the time-dependent and the steady state solutions are obtained. It is found that the multiple modes enhance the braking effect of the resistive wall. The “locking threshold” predicted in the case of multiple modes is much smaller than that of the case of the single mode (as far as the same mode is concerned). The formation of the “slinky mode” is clearly demonstrated. The relation of two existing thresholds: “wall locking” and “phase locking” is also discussed. Comparison is made between the time-dependent solution and the steady state solution for two examples, in which the mode amplitudes grow linearly with time. The validity of the steady state assumption, in particular, for the calculation of the viscous torque is discussed. Numerical analysis is applied to the reversed field experiment [F. Gnesotto, P. Sonato, W. R. Baker et al., Fusion Eng. Des. 25, 335 (1995)].
Small amplitude Bernstein–Greene–Kruskal solitary waves in a thermal charge-varying dusty plasma
Authors: Tribeche Mouloud , Zerguini Taha Houssine
Published: July 2004

Small amplitude electrostatic solitary Bernstein–Greene–Kruskal (BGK) waves are investigated in an unmagnetized thermal charge-varying dusty plasma. The well-known pseudopotential analysis is used. It is found that under certain conditions spatially localized structures, the height and nature of which depend sensitively on the plasma parameters, can exist. The effects of ion temperature, equilibrium dust charge, dust dynamics, and dust size on the properties of these solitary waves are discussed. This investigation may be taken as a prerequisite for the understanding of the solitary dust BGK waves that may occur in space and laboratory plasmas.
Two-dimensional simulation of pellet ablation with atomic processes
Authors: Ishizaki R. , Parks P. B. , Nakajima N. , Okamoto M.
Published: July 2004

A two-dimensional hydrodynamic simulation code CAP has been developed in order to investigate the dynamics of hydrogenic pellet ablation in magnetized plasmas throughout their temporal evolution. One of the properties of the code is that it treats the solid-to-gas phase change at the pellet surface without imposing artificial boundary conditions there, as done in previous ablation models. The simulation includes multispecies atomic processes, mainly molecular dissociation and thermal ionization in the ablation flow beyond the pellet, with a kinetic heat flux model. It was found that ionization causes the formation of a quasistationary shock front in the supersonic region of the ablation flow, followed by a “second” sonic surface farther out. Anisotropic heating, due to the directionality of the magnetic field, contributes to a nonuniform ablation (recoil) pressure distribution over the pellet surface. Since the shear stress can exceed the yield strength of the solid for a sufficiently high heat flux, the solid pellet can be fluidized and flattened into a “pancake” shape while the pellet is ablating and losing mass. The effect of pellet deformation can shorten the pellet lifetime almost 3× from that assuming the pellet remains rigid and stationary during ablation.
Comment on “Instability of the Shukla mode in a dusty plasma containing equilibrium density and magnetic field inhomogeneities” [Phys. Plasmas 11, 1732 (2004)] and “New resonance and cut-off for low-frequency electromagnetic waves in dusty magnetoplasmas” [Phys. Plasmas 11, 2307 (2004)]
Authors: Rudakov Leonid
Published: July 2004

It is shown that the oscillation named by Shukla as the “Shukla mode” is well known in the plasma physics literature as the magnetic drift wave. In addition, the instability of these modes in a cold plasma as claimed by Shukla et al. [Phys. Plasmas 11, 1732 (2004)] does not exist and is due to a mathematical error in their analysis. Also the “new” resonance and new cutoff frequencies claimed by Shukla et al. and Mamum et al. [Phys. Plasmas 11, 2307 (2004)] have been known in the published literature for decades.
Response to “Comment on ‘Instability of the Shukla mode in a dusty plasma containing equilibrium density and magnetic field inhomogeneities’ and ‘New resonance and cutoff for low-frequency electromagnetic waves in dusty magnetoplasmas’ ” [Phys. Plasmas 11, 4154 (2004)]
Authors: Shukla P. K. , Bharuthram R. , Mamun A. A. , Morfill G. E. , Schlickeiser R. , Stenflo L.
Published: July 2004

It is shown that the Comment of Rudakov on the papers by Shukla et al. and Mamun et al. is misleading.
Periodic structures on plasma surface
Authors: Lan Y. , Yu M. Y.
Published: July 2004

Smooth as well as cusped oscillating periodic structures on plasma-vacuum interface are shown to exist.
Suppression of the standing wave effect in high frequency capacitive discharges using a shaped electrode and a dielectric lens: Self-consistent approach
Authors: Chabert P. , Raimbault J.-L. , Rax J.-M. , Perret A.
Published: July 2004

The standing wave effect causes nonuniform plasma excitation in high frequencies capacitive discharges when the electrode size is not considerably smaller than the excitation wavelength. A shaped electrode was proposed by Sansonnens and Schmitt [Appl. Phys. Lett. 82, 182 (2003)] to suppress this unwanted effect. The shape of the electrode was calculated in the vacuum approximation (no plasma was present between the electrodes), and was found to be Gaussian. The authors postulated that the presence of plasma would not significantly modify the solution. However, it was shown [Chabert et al., Phys. Plasmas 11, 1775 (2004)] using a self-consistent nonlinear transmission line model that the presence of plasma significantly shortens the wavelength for a system composed of two parallel plate electrodes. It was therefore legitimate to expect the optimized shape of the electrode and lens to be different when a plasma is present. Here it is shown that to suppress the standing wave effect the current flowing in the electrodes must be proportional to the discharge radius. This condition is independent of the medium present between the plates and indeed requires a Gaussian electrode.
A theoretical analysis of the effects of radio frequency waves on interchange stability in mirror plasmas
Authors: Kim S. S. , Jhang Hogun
Published: July 2004

A theoretical study is made of the effects of radio frequency (rf) waves in the range of ion cyclotron frequency on interchange modes in mirror plasmas. A two-fluid cold plasma model including particle collisions is utilized for the investigation. Both the equilibrium ponderomotive force produced by the gradient of rf wave amplitude and the sideband wave coupling mechanism originated from the nonlinear beating between high frequency waves are taken into account. A tractable form of the dispersion relation for the interchange mode is obtained and applied to carrying out a parametric study. Key parameters affecting the stability boundary are identified and the consequences of the parameter variation on the stability boundary change are analyzed near ion cyclotron resonance region.
Simulation of plasma transport by coherent structures in scrape-off-layer tokamak plasmas
Authors: Bisai Nirmal , Das Amita , Deshpande Shishir , Jha Ratneshwar , Kaw Predhiman , Sen Abhijit , Singh Raghvendra
Published: July 2004

The formation of coherent structures by two-dimensional interchange turbulence in the scrape-off layer (SOL) of tokamak plasmas and their subsequent contribution to anomalous plasma transport has been studied in recent years using electron continuity and current balance equations. In this paper, it is demonstrated that the inclusion of electron energy equation in the simulations changes the nature of coherent structures in a significant manner and gives results which are in better agreement with experiments. Specifically, it is observed that radial potential gradients are established which give a poloidal elongation and movement to the structures. Only during the radial transport events do the structures get significantly extended in the radial direction giving radial velocities of order 1 km/s. Sometimes detachment of density structures from the main plasma is observed. These detached structures either decay into the background plasma or are transported out from the SOL. The simulated particle flux and its statistical properties also are discussed.
Factors affecting energy deposition and expansion in single wire low current experiments
Authors: Duselis Peter U. , Vaughan Jeffrey A. , Kusse Bruce R.
Published: July 2004

Single wire experiments were performed on a low current pulse generator at Cornell University. A 220 nF capacitor charged to 15–25 kV was used to drive single wire experiments. The capacitor and wire holder were connected in series through an external variable inductor to control the current rise rate. This external series inductance was adjustable from 0.2 to 2 μH. When coupled with the range of charging voltages this results in current rise rates from 5 to 50 A/ns. The current heated the wire through liquid and vapor phases until plasma formed around the wire. Energy deposition and expansion rates were measured as functions of the current rise rate. These results indicated better energy deposition and higher expansion rates with faster current rise rates. Effects of the wire-electrode connection method and wire polarity were also studied.
On the Shukla–Nambu–Salimullah potential in a streaming dusty magnetoplasma
Authors: Salimullah M. , Rizwan A. M. , Nitta H. , Nambu M. , Shukla P. K.
Published: July 2004

Detailed properties of a recently found effective potential have been examined in a streaming and uniform dusty magnetoplasma. The modification of the symmetric Debye–Hückel potential in the presence of the static magnetic field may lead to the manipulation of the robust dust crystal parameters in laboratory experiments.
Effects of viscosity and mass diffusion in hydrodynamically unstable plasma flows
Authors: Robey H. F.
Published: July 2004

Hydrodynamically unstable plasma flows driven by intense laser radiation are described in which an interface between two materials of dissimilar densities is subjected to a very strong shock and then decelerated over a longer time scale. Preimposed perturbations on this interface are unstable to a combination of the Richtmyer–Meshkov (RM) and Rayleigh-Taylor (RT) instabilities. Overall target dimensions for these experiments are of the order of 1 mm, and length scales of the unstable perturbations of interest can be as small as a few microns. At such small spatial scales, the effects of dissipative processes such as viscosity, thermal conductivity, and mass diffusion begin to affect instability growth rates. In this article, estimates are presented of the spatial scale at which viscosity and mass diffusion begin to affect the growth of a perturbation due to the RM and RT instabilities. Time dependent values for the plasma kinematic viscosity and interfacial binary mass diffusivity are estimated for the conditions occurring in laser-driven instability experiments recently conducted on the Omega laser. These are used together with several models in the literature for estimating the reduction in the growth rate dispersion curves of the Rayleigh–Taylor and Richtmyer–Meshkov instabilities due to the presence of these small-scale dissipative effects.
Study of a chaotic mixing system for DNA chip hybridization chambers
Authors: Raynal Florence , Plaza Frédéric , Beuf Aurélien , Carrière Philippe , Souteyrand Eliane , Martin Jean-René , Cloarec Jean-Pierre , Cabrera Michel
Published: July 2004

Numerical simulations of a micromixing system based on chaotic advection for improved deoxyribonucleic acid (DNA) chip hybridization are presented. To attain best chip performance, homogeneous dispersion of DNA molecules throughout the chamber in which the chip is placed is of primary importance. Poincaré sections of a simple time-periodic flow, based on numerical simulations of the flow, are compared with visualizations in a scaled-up experiment, with good agreement. The influence on mixing efficiency of varying the period of the flow at fixed volume flow rate is studied and a trade off is found between the absence of regular islands and a small enough total sample volume. The results illustrate the potential for optimization of such devices based on numerical flow simulations.
Beads-on-string phenomena in wormlike micellar fluids
Authors: Sostarecz Michael C. , Belmonte Andrew
Published: July 2004

We present experimental results on the dynamics of wormlike micellar filaments surrounded by an immiscible viscous bulk fluid. For certain concentrations, these filaments develop a beads-on-string structure previously observed only in polymer jets and filaments surrounded by air. By taking advantage of the longer time scales present in this experiment, we are able to quantify the evolution of individual beads. We also investigate the stability of these filaments and the robustness of the beads-on-string structure by stretching the filament within a rotating flow.
Biological activity of nitric oxide in the plasmatic compartment
Authors: Wang Xunde , Tanus-Santos Jose E. , Reiter Christopher D. , Dejam Andre , Shiva Sruti , Smith Reginald D. , Hogg Neil , Gladwin Mark T.
Published: July 2004

There exist reaction products of nitric oxide (NO) with blood that conserve its bioactivity and transduce an endocrine vasomotor function under certain conditions. Although S-nitrosated albumin has been considered the major species subserving this activity, recent data suggest that additional NO species, such as nitrite, nitrated lipids,
N
-nitrosamine, and iron-nitrosyl complexes, may contribute. We therefore examined the end products of NO reactions in plasma and blood
in vitro
and
in vivo
by using reductive chemiluminescent assays and electron paramagnetic resonance spectroscopy. We found that NO complexes in plasma previously considered to be S-nitrosated albumin were <10 nM after elimination of nitrite and were mercury-stable, consistent with iron-nitrosyl or
N
-nitrosamine complex. During clinical NO gas inhalation protocols or
in vitro
NO donor treatment of human plasma,
S
-nitroso-albumin did not form with NO exposure <2 μM, but plasma methemoglobin was detectable by paramagnetic resonance spectroscopy. Consistent with this formation of methemoglobin, human plasma was found to consume ≈2 μM NO at a rate equivalent to that of hemoglobin. This NO consumption was mediated by the reaction of NO with plasma haptoglobin-hemoglobin complexes and limited slower reaction pathways required for S-nitrosation. These data suggest that high-affinity, metal-based reactions in plasma with the haptoglobin-hemoglobin complex modulate plasmatic NO reaction products and limit S-nitrosation at low NO flux. The studies further suggest that alternative NO reaction end products in plasma, such as nitrite,
N
-nitrosamines, iron-nitrosyls, and nitrated lipids, should be evaluated in blood NO transport along the vasculature.
Kinetic Gravity Separation
Authors: van Kooy Laurens , Mooij Marieke , Rem Peter
Published: July 2004

Separations by density, such as the separation of non‐ferrous scrap into light and heavy alloys, are often realized by means of heavy media. In principle, kinetic gravity separations in water can be faster and cheaper, because they do not rely on suspensions or salt solutions of which the density must be tightly controlled. Test results of a prototype kinetic gravity separator in combination with suitable size classification techniques show promising results for particle sizes between 2 and 10 mm.
Discs large (Dlg1) complexes in lymphocyte activation
Authors: Xavier Ramnik , Rabizadeh Shahrooz , Ishiguro Kazuhiro , Andre Niko , Ortiz J. Bernabe , Wachtel Heather , Morris David G. , Lopez-Ilasaca Marco , Shaw Albert C. , Swat Wojciech , Seed Brian
Published: July 2004

T cell antigen recognition involves the formation of a structured interface between antigen-presenting and T cells that facilitates the specific transmission of activating and desensitizing stimuli. The molecular machinery that organizes the signaling molecules and controls their disposition in response to activation remains poorly understood. We show here that in T cells Discs large (Dlg1), a PDZ domain-containing protein, is recruited upon activation to cortical actin and forms complexes with early participants in T cell activation. Transient overexpression of Dlg1 attenuates basal and Vav1-induced NFAT reporter activation. Reduction of Dlg1 expression by RNA interference enhances both CD3- and superantigen-mediated NFAT activation. Attenuation of antigen receptor signaling appears to be a complex, highly orchestrated event that involves the mutual segregation of important elements of the early signaling complex.
Bcl-2 functionally interacts with inositol 1,4,5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1,4,5-trisphosphate
Authors: Chen Rui , Valencia Ignacio , Zhong Fei , McColl Karen S. , Roderick H. Llewelyn , Bootman Martin D. , Berridge Michael J. , Conway Stuart J. , Holmes Andrew B. , Mignery Gregory A. , Velez Patricio , Distelhorst Clark W.
Published: July 2004

Inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are channels responsible for calcium release from the endoplasmic reticulum (ER). We show that the anti-apoptotic protein Bcl-2 (either wild type or selectively localized to the ER) significantly inhibited InsP3-mediated calcium release and elevation of cytosolic calcium in WEHI7.2 T cells. This inhibition was due to an effect of Bcl-2 at the level of InsP3Rs because responses to both anti-CD3 antibody and a cell-permeant InsP3 ester were decreased. Bcl-2 inhibited the extent of calcium release from the ER of permeabilized WEHI7.2 cells, even at saturating concentrations of InsP3, without decreasing luminal calcium concentration. Furthermore, Bcl-2 reduced the open probability of purified InsP3Rs reconstituted into lipid bilayers. Bcl-2 and InsP3Rs were detected together in macromolecular complexes by coimmunoprecipitation and blue native gel electrophoresis. We suggest that this functional interaction of Bcl-2 with InsP3Rs inhibits InsP3R activation and thereby regulates InsP3-induced calcium release from the ER.
Roles played by a subset of integrin signaling molecules in cadherin-based cell–cell adhesion
Authors: Yano Hajime , Mazaki Yuichi , Kurokawa Kazuo , Hanks Steven K. , Matsuda Michiyuki , Sabe Hisataka
Published: July 2004

Integrins can intercommunicate with cadherins. Here, we examined their possible relationship by use of small interfering RNA–mediated protein knockdown in HeLa cells. We found that a subset of integrin signaling molecules, namely Fak and paxillin, but not p130 Crk-associated substrate or proline-rich tyrosine kinase 2, participate in processes regulating N-cadherin–based cell–cell adhesion. Paxillin was found to be required primarily for the recruitment of Fak to robust focal adhesions. Our results suggest that at least some signals involving Fak are linked to a mechanism down-regulating Rac1 activity at the cell periphery, which appears to be important for the formation of N-cadherin–based adhesions in motile cells. Our analyses simultaneously exemplified the essential role of Fak in the maintenance of cell–cell adhesions in collective cell migration, a type of migration occurring in embryonic development and carcinoma invasion.
Synaptotagmins are trafficked to distinct subcellular domains including the postsynaptic compartment
Authors: Adolfsen Bill , Saraswati Sudipta , Yoshihara Motojiro , Littleton J. Troy
Published: July 2004

The synaptotagmin family has been implicated in calcium-dependent neurotransmitter release, although Synaptotagmin 1 is the only isoform demonstrated to control synaptic vesicle fusion. Here, we report the characterization of the six remaining synaptotagmin isoforms encoded in the Drosophila genome, including homologues of mammalian Synaptotagmins 4, 7, 12, and 14. Like Synaptotagmin 1, Synaptotagmin 4 is ubiquitously present at synapses, but localizes to the postsynaptic compartment. The remaining isoforms were not found at synapses (Synaptotagmin 7), expressed at very low levels (Synaptotagmins 12 and 14), or in subsets of putative neurosecretory cells (Synaptotagmins α and β). Consistent with their distinct localizations, overexpression of Synaptotagmin 4 or 7 cannot functionally substitute for the loss of Synaptotagmin 1 in synaptic transmission. Our results indicate that synaptotagmins are differentially distributed to unique subcellular compartments. In addition, the identification of a postsynaptic synaptotagmin suggests calcium-dependent membrane-trafficking functions on both sides of the synapse.
Novel signaling pathways mediating reciprocal control of keratinocyte migration and wound epithelialization through M3 and M4 muscarinic receptors
Authors: Chernyavsky Alex I. , Arredondo Juan , Wess Jürgen , Karlsson Evert , Grando Sergei A.
Published: July 2004

To test the hypothesis that keratinocyte (KC) migration is modulated by distinct muscarinic acetylcholine (ACh) receptor subtypes, we inactivated signaling through specific receptors in in vitro and in vivo models of reepithelialization by subtype-selective antagonists, small interfering RNA, and gene knockout in mice. KC migration and wound reepithelialization were facilitated by M4 and inhibited by M3. Additional studies showed that M4 increases expression of “migratory” integrins α5β1, αVβ5, and αVβ6, whereas M3 up-regulates “sedentary” integrins α2β1 and α3β1. Inhibition of migration by M3 was mediated through Ca2+-dependent guanylyl cyclase–cyclic GMP–protein kinase G signaling pathway. The M4 effects resulted from inhibition of the inhibitory pathway involving the adenylyl cyclase–cyclic AMP–protein kinase A pathway. Both signaling pathways intersected at Rho, indicating that Rho kinase provides a common effector for M3 and M4 regulation of cell migration. These findings offer novel insights into the mechanisms of ACh-mediated modulation of KC migration and wound reepithelialization, and may aid the development of novel methods to promote wound healing.