8,261 research outputs found
A general resonance theory based on Mourre's inequality
We study the perturbation of bound states embedded in the continuous spectrum
which are unstable by the Fermi Golden Rule. The approach to resonance theory
based on spectral deformation is extended to a more general class of quantum
systems characterized by Mourre's inequality and smoothness of the resolvent.
Within the framework of perturbation theory it is still possible to give a
definite meaning to the notion of complex resonance energies and of
corresponding metastable states. The main result is a quasi-exponential decay
estimate up to a controlled error of higher order in perturbation theory.Comment: 17 page
High-pressure Debye-Waller and Grueneisen parameters of Au and Cu
The lattice vibrations are determined in the quasi-harmonic approximation for
elemental Au and Cu to twice their normal density by first-principles
electronic band-structure calculations. It is found for these materials that
the important moments of the phonon density of states can be obtained to high
accuracy from short-ranged force constant models. We discuss the implications
for the Grueneisen parameters on the basis of calculated phonon moments and
their approximations by using bulk moduli and Debye-Waller factors.Comment: 4 pages, 2 figures to appear in the proceedings of the 13th APS
Topical Conference on Shock Compression of Condensed Matter (scheduled for
April 2004
An algebraic formula for the index of a vector field on an isolated complete intersection singularity
Let (V,0) be a germ of a complete intersection variety in \CC^{n+k}, n>0,
having an isolated singularity at 0 and X be the germ of a holomorphic vector
field on \CC^{n+k} tangent to V and having on V an isolated zero at 0. We show
that in this case the homological index and the GSV-index coincide. In the case
when the zero of X is also isolated in the ambient space \CC^{n+k} we give a
formula for the homological index in terms of local linear algebra.Comment: 18 pages; added an example which is not quasi homogeneous. A script
calculating this example can be found at
http://www.iag.uni-hannover.de/~bothmer/gobelin/ or at the and of the source
file of this articl
EPICA ice core Dronning Maud Land: first results from stable isotope measurements back to the LGM
Recommended from our members
Motion adaptation and attention: A critical review and meta-analysis
The motion aftereffect (MAE) provides a behavioural probe into the mechanisms underlying motion perception, and has been used to study the effects of attention on motion processing. Visual attention can enhance detection and discrimination of selected visual signals. However, the relationship between attention and motion processing remains contentious: not all studies find that attention increases MAEs. Our meta-analysis reveals several factors that explain superficially discrepant findings. Across studies (37 independent samples, 76 effects) motion adaptation was significantly and substantially enhanced by attention (Cohen's d = 1.12, p < .0001). The effect more than doubled when adapting to translating (vs. expanding or rotating) motion. Other factors affecting the attention-MAE relationship included stimulus size, eccentricity and speed. By considering these behavioural analyses alongside neurophysiological work, we conclude that feature-based (rather than spatial, or object-based) attention is the biggest driver of sensory adaptation. Comparisons between naïve and non-naïve observers, different response paradigms, and assessment of 'file-drawer effects' indicate that neither response bias nor publication bias are likely to have significantly inflated the estimated effect of attention
Determination of the wind response of Saturn 5 by statistical methods, volume 1
Statistical analysis of Saturn 5 launch vehicle wind response - Vol.
Functional requirements for onboard management of space shuttle consumables, volume 1
A study was conducted to determine the functional requirements for onboard management of space shuttle consumables. A generalized consumable management concept was developed for application to advanced spacecraft. The subsystems and related consumables selected for inclusion in the consumables management system are: (1) propulsion, (2) power generation, and (3) environmental and life support
- …