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Trapped electron turbulence is shown to have a significant inward particle flux component associated with nonlinear deviations of the density-potential cross correlation from the quasilinear value. The cross correlation is altered because the density advection nonlinearity mixes a linearly stable eigenmode with the eigenmode of the instability. The full nonlinear flux is evaluated by solving spectrum balance equations in a complete basis spanning the fluctuation space. An ordered expansion for small collisionality, perpendicular wave number, and temperature/density-gradient instability threshold parameter enables an analytic solution for a weakly driven regime. The solution quantifies the role of zonal modes on transport via their saturation of the turbulence under intensely anisotropic transfer. The inward transport is neither diffusive nor convective, but is driven by temperature gradient and enhanced by flat density gradients. It is slightly smaller than the outwardly directed flux associated with the growing eigenmode, making the flux a small fraction of the quasilinear value. [ABSTRACT FROM AUTHOR]

This study investigates the influence of national-cultures on the external information search behavior of travelers from the European Union (EU) member states existing at the time the data were collected. Statistical information from EUROBAROMETER 48 is examined. EUROBAROMETER 48 is a Standard Eurobarometer public opinion survey conducted on behalf of the European Commission at least two times a year in all member states of the EU. This document identifies the population of the respective nationality of EU members, aged 15 years and over, residing in each of the member states. Data were collected between 12 October 1997 and 16 November 1997. First, a series of Kruskal–Wallis tests are conducted to examine the impact of national-cultural on the use of information sources. After determining that the national culture significantly influences a traveler''s external information search behavior, a correspondence analysis is utilized to examine information search behavior of the residents and nationals of each EU state. This analysis identifies five distinct market segments based on respondents’ information search patterns. Findings suggest national culture is likely to influence a traveler''s information search behavior. [Copyright &y& Elsevier]

Objective: The purpose of this study was to evaluate the accuracy of algorithms for the assignment of gestational age with the use of the last menstrual period and early ultrasound information.Study Design: Gestational age estimates that are based on last menstrual period, ultrasound scanning, or their combination were compared among women who attended prenatal care clinics in central North Carolina (n = 3655) by an evaluation of digit preference in the last menstrual period dates and a comparison of mean gestational age, preterm and postterm categories with the use of kappa statistics, difference between actual and expected delivery date, and birth weight among subgroups with discrepant assignments.Results: Last menstrual period reports show digit preference, assign gestation 2.8 days longer on average than ultrasound scanning, yield substantially more postterm births (12.1% vs 3.4%), and predict delivery among term births less accurately. Misclassification of births as postterm was more common in younger women, those of nonoptimal prepregnancy body weight, cigarette smokers, and women who reported last menstrual period using preferred dates of the month.Conclusion: Last menstrual period estimates of the duration of gestation are subject to both random error and a systematic tendency to overstate the duration of gestation, most likely because of delayed ovulation. [ABSTRACT FROM AUTHOR]

The article focuses on the community problem solving program designed for middle level students. It was noted that participation in this kind of program enables the students to develop their skills, as well as self-respect. It also hones their perseverance, passion, care and sense of responsibility for others. The work done by children from the Hildebrand Intermediate School in Spring, Texas in alleviating boredom and depression prevalent in adolescent hospital patients was cited as an example. The kids develop kits that contained recreational and educational activities.

A kinetic theory for the anomalous heating of ions from energy stored in magnetic turbulence is presented. Imposing self-consistency through the constitutive relations between particle distributions and fields, a turbulent Kirchhoff's Law is derived that expresses a direct connection between rates of ion heating and electron thermal transport. This connection arises from the kinematics of electron motion along turbulent fields, which results in granular structures in the electron distribution. The drag exerted on these structures through emission into collective modes mediates an effective ambipolar constraint on transport. Resonant damping of the collective modes by ions produces the heating. In collisionless plasmas the rate of ion damping controls the rate of emission, and hence the ambipolar-constrained electron heat flux. The heating rate is calculated for both a resonant and nonresonant magnetic fluctuation spectrum and compared with observations. The theoretical heating rate is sufficient to account for the observed twofold rise in ion temperature during sawtooth events in experimental discharges. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

It is shown that ion temperature gradient driven turbulence supports fluctuations with broader radial scales than those inferred previously on the basis of mixing length arguments derived from the eigenfunction with lowest radial eigenmode number. These fluctuations of greater radial extent are more strongly excited and are shown to result in fluctuation levels and transport coefficients that can be considerably larger than those previously predicted. It is expected that transport of this nature would maintain ion temperature and density profiles near marginal stability in neutral beam heated and ion cyclotron resonance heated plasmas. [ABSTRACT FROM AUTHOR]

Kelvin–Helmholtz unstable flows are numerically investigated in the context of a sheared E×B flow profile and a sheared magnetic field in the collisional, electrostatic limit. In the extreme form of this limit, density fluctuations are small and the system is described by the nonlinear E×B vorticity dynamics. In order to focus on the role of magnetic shear localization, the computations are confined to two dimensions. For weak magnetic shear the fluctuations become turbulent and saturate by nonlinear cascade to small (dissipative) scales. In a strong magnetic shear regime near the linear stability boundary, nonlinear spatial broadening allows direct access to resistive shear dissipation, leading to saturation at small amplitude with nearly all the fluctuation energy in the longest-wavelength mode. This is in accordance with previous investigation using a statistical closure analysis [Phys. Fluids 29, 231 (1986)]. The amount of broadening is proportional to the linear growth rate. The fluctuation amplitude scaling with magnetic shear is found to agree closely with the theory. [ABSTRACT FROM AUTHOR]

The resistivity fluctuation correlation function and electrostatic potential spectrum of resistivity-gradient-driven turbulence are calculated analytically and compared to the results of three-dimensional numerical calculations. Resistivity-gradient-driven turbulence is characterized by effective Reynolds’ numbers of order unity. Steady-state solution of the renormalized spectrum equation yields an electrostatic potential spectrum <[lowercase_phi_synonym]2>ky ∼k-3.25y . Agreement of the analytically calculated potential spectrum and mean-square radial velocity with the results of multiple helicity numerical calculations is good. This comparison constitutes a quantitative test of the analytical turbulence theory used. The spectrum of magnetic fluctuations is also calculated and agrees well with that obtained from the numerical computations. [ABSTRACT FROM AUTHOR]

Turbulence associated with sheared radial electric fields such as those arising in tokamak edge plasmas is investigated analytically. Two driving mechanisms are considered: in the region of maximum vorticity (maximum electric field shear), the electric field is the dominant driving mechanism. Away from the maximum, turbulence is driven by the density gradient. In the latter case, previous work is extended to include the effects of the electric field on the spatial scales of density correlation in the frequency-Doppler-shifted, density-gradient-driven turbulence. For radial-electric-field-driven turbulence, the effects of magnetic shear on linear instability and on fully developed turbulence are examined. In the case of weak magnetic shear, saturation occurs through an enstrophy cascade process which couples regions of driving and dissipation in wavenumber space. For stronger magnetic shear, such that the width of the dissipation region resulting from parallel resistivity is comparable to the radial electric field scale length, saturation occurs through nonlinear broadening of the mode structure, which pushes enstrophy into the region of dissipation. Estimates of mode widths, fluctuation levels, and scalings are obtained for both mechanisms. Comparison is made with the results of fluctuation measurements in the TEXT tokamak [Phys. Fluids 27, 2956 (1984)]. [ABSTRACT FROM AUTHOR]

A theory of resistive, density-gradient-driven turbulence is presented and compared with tokamak edge fluctuation measurements. In addition to linear driving, the theory accounts for relaxation of the density gradient through a nonlinear process associated with emission from localized density fluctuation elements. From a fluid model for isothermal electrons in toroidal geometry, equations are obtained and solved analytically, retaining both coherent and incoherent contributions. The effect of collisions on the density blobs is treated. A Reynolds number parameterizes the magnitude of the turbulent scattering relative to the collisional viscous diffusion. The analytic results indicate that the spectrum is characterized by linewidths which increase as a function of the Reynolds number and may reach Δω/ω>=1. Energy lies predominantly in the small wavenumbers (k⊥ ρs∼0.1). For larger wavenumbers and frequency, the spectrum decays as k-17/6 and ω-2. The fluctuation level scales as 1/k⊥Ln and may reach -30% for parameters typical of the pretext edge. Particle diffusion is Bohm-like in magnitude but does not follow Bohm scaling, going instead as n2/3T1/6e. The density fluctuations exhibit nonadiabatic character caused by the incoherent mode coupling. An expression for the departure from adiabaticity is given. [ABSTRACT FROM AUTHOR]

The normative and policy implications of introducing video technologies into the courtroom are analyzed in this work. Examining video misdemeanor arraignments conducted in Miami's Eleventh Judicial Circuit, reveals a disruption of normative expectations within the courtroom, especially on the part of public defenders. Such latent consequences suggest that some defendants may not be getting the full benefit of constitutionally guaranteed due process protections. They also suggest an increased depersonalization of courtroom interactions and the possibility of negatively altered perceptions upon the part of courtroom actors and public onlookers. Because these perceptions affect the legitimacy with which courtroom procedures are held, the policy implications of introducing video technologies, along the lines of this study's findings, require careful consideration. [ABSTRACT FROM AUTHOR]

A novel theory for the nonlinear evolution of the trapped-ion-temperature-gradient-driven mode, based on the turbulent trapping of resonant ions in the electrostatic potential of the waves, is proposed. A statistical description is adopted whereby the self-consistent evolution of the two-point correlation function of the trapped-particle distribution function is followed in phase space. Threshold-dependent, non-steady-state turbulence (nonlinear instability) is shown to develop when the decay of the correlation function is overcome by a source term that derives its free energy from the relaxation of the average distribution function. This nonlinear instability leads to anomalous thermal and particle transport that in turn reconfigure the equilibrium temperature and density profiles in such a way as to return the system toward its marginal point. Expressions for the nonlinear dispersion relation and threshold, as well as estimates of the thermal and particle transport level, are derived. The estimated flux levels are sufficiently high as to make any significant departure away from marginality unlikely. The scenario outlined serves to underscore the desirability for pellet injection in experimental devices such as the Compact Ignition Tokamak [Bull. Am. Phys. Soc. 32, 1921 (1987)] that operate in the very low ion collisionality regime where this mode would be expected to become relevant. As with a number of recent theories, the present work further reinforces the notion that unfavorably drifting trapped particles pose a serious menace to confinement and suggests inboard, off-axis radio-frequency heating as one means of reducing the size of this population, at least for the case of those energetic trapped particles created during auxiliary heating. [ABSTRACT FROM AUTHOR]