2,381 research outputs found
Transient Rayleigh-Benard-Marangoni Convection due to Evaporation : a Linear Non-normal Stability Analysis
The convective instability in a plane liquid layer with time-dependent
temperature profile is investigated by means of a general method suitable for
linear stability analysis of an unsteady basic flow. The method is based on a
non-normal approach, and predicts the onset of instability, critical wave
number and time. The method is applied to transient Rayleigh-Benard-Marangoni
convection due to cooling by evaporation. Numerical results as well as
theoretical scalings for the critical parameters as function of the Biot number
are presented for the limiting cases of purely buoyancy-driven and purely
surface-tension-driven convection. Critical parameters from calculations are in
good agreement with those from experiments on drying polymer solutions, where
the surface cooling is induced by solvent evaporation.Comment: 31 pages, 8 figure
Peruvian scallop Argopecten purpuratus : from a key aquaculture species to a promising biondicator species
Low-Prandtl-number B\'enard-Marangoni convection in a vertical magnetic field
The effect of a homogeneous magnetic field on surface-tension-driven
B\'{e}nard convection is studied by means of direct numerical simulations. The
flow is computed in a rectangular domain with periodic horizontal boundary
conditions and the free-slip condition on the bottom wall using a
pseudospectral Fourier-Chebyshev discretization. Deformations of the free
surface are neglected. Two- and three-dimensional flows are computed for either
vanishing or small Prandtl number, which are typical of liquid metals. The main
focus of the paper is on a qualitative comparison of the flow states with the
non-magnetic case, and on the effects associated with the possible
near-cancellation of the nonlinear and pressure terms in the momentum equations
for two-dimensional rolls. In the three-dimensional case, the transition from a
stationary hexagonal pattern at the onset of convection to three-dimensional
time-dependent convection is explored by a series of simulations at zero
Prandtl number.Comment: 26 pages, 9 figure
The effect of salinity on the acute toxicity of copper and cadmium in European sea bass <i>Dicentrarchus labrax</i> L.
Use of Nebulized Amphotericin B in the Treatment of Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis
Background. Systemic steroids and adjunctive antifungal therapy are the cornerstone in treating allergic bronchopulmonary aspergillosis (ABPA) in the context of CF. Aim. Evaluate the use of inhaled amphotericin B (iAMB) as antifungal agent in this context. Methods. Report of 7 CF patients with recurrent or difficult to treat ABPA and failure to taper systemic corticosteroids treated with AMB deoxycholate (AMB-d) (Fungizone 25 mg 3× a week) or AMB lipid complex (ABLC) (Abelcet 50 mg twice weekly). Successful therapy was defined as steroid withdrawal without ABPA relapse within 12 months. Results. Therapy was successful in 6 of 7 patients treated with iAMB. In 5/6, lung function improved. The patient with treatment failure has concomitant MAC lung infection. Conclusion. Inhaled AMB may be an alternative to commonly used adjunctive antifungal therapy in the treatment of ABPA. More data are needed on safety and efficacy
Role of semicore states in the electronic structure of group-III nitrides: An exact exchange study
The bandstructure of the zinc-blende phase of AlN, GaN, InN is calculated
employing the exact-exchange (EXX) Kohn-Sham density-functional theory and a
pseudopotential plane-wave approach. The cation semicore d electrons are
treated both as valence and as core states. The EXX bandgaps of AlN and GaN
(obtained with the Ga 3d electrons included as core states) are in excellent
agreement with previous EXX results, GW calculations and experiment. Inclusion
of the semicore d electrons as valence states leads to a large reduction in the
EXX bandgaps of GaN and InN. Contrary to common belief, the removal of the
self-interaction, by the EXX approach, does not account for the large
disagreement for the position of the semicore d electrons between the LDA
results and experiment.Comment: 10 pages including 3 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.htm
Non-Volatile Memory Characteristics of Submicrometre Hall Structures Fabricated in Epitaxial Ferromagnetic MnAl Films on GaAs
Hall-effect structures with submicrometre linewidths (<0.3pm) have been fabricated in ferromagnetic thin films of Mn[sub 0.60]Al[sub 0.40] which are epitaxially grown on a GaAs substrate. The MnAl thin films exhibit a perpendicular remanent magnetisation and an extraordinary Hall effect with square hysteretic behaviour. The presence of two distinct stable readout states demonstrates the potential of using ultrasmall ferromagnetic volumes for electrically addressable, nonvolatile storage of digital information
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