Radiative hydrodynamic modeling of the Bastille-Day flare (14 July, 2000). I, Numerical simulations

A 1D loop radiative hydrodynamic model that incorporates the effects of gravitational stratification, heat conduction, radiative losses, external heat input, presence of helium, and Braginskii viscosity is used to simulate elementary flare loops. The physical parameters for the input are taken from observations of the Bastille-Day flare of 2000 July 14. The present analysis shows that: a) the obtained maximum values of the electron density can be considerably higher (4.2 × 10 11 cm −3 or more) in the case of footpoint heating than in the case of apex heating (2.5 × 10 11 cm −3); b) the average cooling time after the flare peak takes less time in the case of footpoint heating than in the case of apex heating; c) the peak apex temperatures are significantly lower (by about 10 MK) for the case of footpoint heating than for apex heating (for the same average loop temperature of about 30 MK). This characteristic would allow to discriminate between different heating positioning; d) in both cases (of apex and footpoint heating), the maximum obtained apex temperature T max is practically independent of the heating duration σ t , but scales directly with the heating rate E H0 ; e) the maximum obtained densities at the loop apex, n max e, increase with the heating rate E H0 and heating duration σ t for both footpoint and apex heating. In Paper II we will use the outputs of these hydrodynamic simulations, which cover a wide range of the parameter space of heating rates and durations, as an input for forward-fitting of the multi-loop arcade of the Bastille-day flare

Piezoelectricity: Quantized Charge Transport Driven by Adiabatic Deformations

We study the (zero temperature) quantum piezoelectric response of Harper-like models with broken inversion symmetry. The charge transport in these models is related to topological invariants (Chern numbers). We show that there are arbitrarily small periodic modulations of the atomic positions that lead to nonzero charge transport for the electrons.Comment: Latex, letter. Replaced version with minor change in style. 1 fi

Review of Coronal Oscillations - An Observer's View

Recent observations show a variety of oscillation modes in the corona. Early non-imaging observations in radio wavelengths showed a number of fast-period oscillations in the order of seconds, which have been interpreted as fast sausage mode oscillations. TRACE observations from 1998 have for the first time revealed the lateral displacements of fast kink mode oscillations, with periods of ~3-5 minutes, apparently triggered by nearby flares and destabilizing filaments. Recently, SUMER discovered with Doppler shift measurements loop oscillations with longer periods (10-30 minutes) and relatively short damping times in hot (7 MK) loops, which seem to correspond to longitudinal slow magnetoacoustic waves. In addition, propagating longitudinal waves have also been detected with EIT and TRACE in the lowest density scale height of loops near sunspots. All these new observations seem to confirm the theoretically predicted oscillation modes and can now be used as a powerful tool for ``coronal seismology'' diagnostic.Comment: 5 Figure

The greatest management principle in the world/ LeBoef

143 hal.; 21 cm

The greatest management principle in the world/ LeBoef

143 hal.; 21 cm

Development of a Web-Based Mass Transfer Processes Laboratory: System Development and Implementation

A web-based environment is utilized as a means to introduce advanced mass transfer processes concepts in environmental engineering and science courses. System development and implementation is presented, including detailed descriptions of the techniques employed to link software written in high level computer languages such as C++ and FORTRAN to an internet-based, user-friendly graphical user interface for both program input and output

Extending a biologically inspired model of choice: multi-alternatives, nonlinearity and value-based multidimensional choice

The leaky competing accumulator (LCA) is a biologically inspired model of choice. It describes the processes of leaky accumulation and competition observed in neuronal populations during choice tasks and it accounts for reaction time distributions observed in psychophysical experiments. This paper discusses recent analyses and extensions of the LCA model. First, it reviews the dynamics and examines the conditions that make the model achieve optimal performance. Second, it shows that nonlinearities of the type present in biological neurons improve performance when the number of choice alternatives increases. Third, the model is extended to value-based choice, where it is shown that nonlinearities in the value function explain risk aversion in risky choice and preference reversals in choice between alternatives characterized across multiple dimensions