40 research outputs found
Geometry-dependent scattering through quantum billiards: Experiment and theory
We present experimental studies of the geometry-specific quantum scattering
in microwave billiards of a given shape. We perform full quantum mechanical
scattering calculations and find an excellent agreement with the experimental
results. We also carry out the semiclassical calculations where the conductance
is given as a sum of all classical trajectories between the leads, each of them
carrying the quantum-mechanical phase. We unambiguously demonstrate that the
characteristic frequencies of the oscillations in the transmission and
reflection amplitudes are related to the length distribution of the classical
trajectories between the leads, whereas the frequencies of the probabilities
can be understood in terms of the length difference distribution in the pairs
of classical trajectories. We also discuss the effect of non-classical "ghost"
trajectories that include classically forbidden reflection off the lead mouths.Comment: 4 pages, 4 figure
Secondary metabolite profiling, growth profiles and other tools for species recognition and important Aspergillus mycotoxins
Species in the genus Aspergillus have been classified primarily
based on morphological features. Sequencing of house-hold genes has also been
used in Aspergillus taxonomy and phylogeny, while extrolites and
physiological features have been used less frequently. Three independent ways
of classifying and identifying aspergilli appear to be applicable: Morphology
combined with physiology and nutritional features, secondary metabolite
profiling and DNA sequencing. These three ways of identifying
Aspergillus species often point to the same species. This consensus
approach can be used initially, but if consensus is achieved it is recommended
to combine at least two of these independent ways of characterising aspergilli
in a polyphasic taxonomy. The chemical combination of secondary metabolites
and DNA sequence features has not been explored in taxonomy yet, however.
Examples of these different taxonomic approaches will be given for
Aspergillus section Nigri
Recommended from our members
Solidus and liquidus temperatures in the uranium-plutonium-zirconium system
Renewed interest in metallic fuel for nuclear reactors has prompted study of the solidus and liquidus for the uranium-plutonium-zirconium system. These temperatures are of importance in assessing the possibility of fuel melting during abnormal reactor conditions. Data obtained in previous work in this area were found to be inadequate for the needs of the current reactor development effort. A dual effort was undertaken to provide the needed data. These were (1) thermodynamic phase diagram analysis and calculation of the ternary solidus and liquidus surfaces and (2) experimental determination of solidus and liquidus temperatures for selected alloys. The methods used and results obtained are described
Shot noise and transport in small quantum cavities with large openings .
We present a dynamical analysis of the transport through small quantum cavities with large openings. The systematic suppression of shot noise is used to distinguish direct, deterministic from indirect, indeterministic transport processes. The analysis is based on quantum mechanical calculations of S matrices and their poles for quantum billiards with convex boundaries of different shape and two open channels in each of the two attached leads. Direct processes are supported when special states couple strongly to the leads, and can result in deterministic transport as signified by a striking system-specific suppression of shot noise