498 research outputs found
Comment on "Stable Quantum Computation of Unstable Classical Chaos"
I think the title and content of the recent Letter by Georgeot and
Shepelyanski [PRL 86, 5393 (2001), also quant-ph/0101004)] are not correct. As
long as the classical Arnold map is considered, the classical computational
algorithm can be made exactly equivalent with the quantum one. The claimed
advantage of the Letter's quantum algorithm disappears if we correctly restrict
the statistical analysis for the classical Arnold system.Comment: 1 page, PRL version + footnote [2] + refs.[3,5
On Conserved Current in Markovian Open Quantum Systems
We reexamine the markovian approximation of local current in open quantum
systems, discussed recently by Gebauer and Car. Our derivation is more
transparent, the proof of current conservation becomes explicit and easy.Comment: 3 page
Change point detection in high dimensional data with U-statistics
We consider the problem of detecting distributional changes in a sequence of
high dimensional data. Our proposed methods are nonparametric, suitable for
either continuous or discrete data, and are based on weighted cumulative sums
of U-statistics stemming from norms. We establish the asymptotic
distribution of our proposed test statistics separately in cases of weakly
dependent and strongly dependent coordinates as , where
denotes sample size and is the dimension, and also provide sufficient
conditions for consistency of the proposed test procedures under a general
fixed alternative with one change point. We further assess finite sample
performance of the test procedures through Monte Carlo studies, and conclude
with two applications to Twitter data concerning the mentions of U.S. Governors
and the frequency of tweets containing social justice keywords
Enhancement of laser-induced optical breakdown using metal/dendrimer nanocomposites
We demonstrate that dendrimer nanocomposites (DNC) can be used to remarkably change the laser-induced optical breakdown (LIOB) threshold of a material, owing to a large enhancement of the local electric field. We have implemented LIOB using femtosecond laser pulses in a gold/dendrimer hybrid nanocomposite as a model system. Third-harmonic generation measurements have been employed as a sensitive way for monitoring the LIOB in situ and in real time. The observed statistical behavior of the breakdown process is attributed to a laser-driven aggregation of individual DNC particles. The breakdown threshold value of the DNC has been found to be up to two orders of magnitude lower than that of pure dendrimers or normal tissues. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69960/2/APPLAB-80-10-1713-1.pd
Contribution of proline to the pre-structuring tendency of transient helical secondary structure elements in intrinsically disordered proteins
Background IDPs function without relying on three-dimensional structures. No clear rationale for such a behavior is available yet. PreSMos are transient secondary structures observed in the target-free IDPs and serve as the target-binding "active" motifs in IDPs. Prolines are frequently found in the flanking regions of PreSMos. Contribution of prolines to the conformational stability of the helical PreSMos in IDPs is investigated. Methods MD simulations are performed for several IDP segments containing a helical PreSMo and the flanking prolines. To measure the influence of flanking-prolines on the structural content of a helical PreSMo calculations were done for wild type as well as for mutant segments with Pro → Asp, His, Lys, or Ala. The change in the helicity due to removal of a proline was measured both for the PreSMo region and for the flanking regions. Results The α-helical content in ~ 70% of the helical PreSMos at the early stage of simulation decreases due to replacement of an N-terminal flanking proline by other residues whereas the helix content in nearly all PreSMos increases when the same replacements occur at the C-terminal flanking region. The helix destabilizing/terminating role of the C-terminal flanking prolines is more pronounced than the helix promoting effect of the N-terminal flanking prolines. General significance This work represents a novel example demonstrating that a proline is encoded in an IDP with a defined purpose. The helical PreSMos presage their target-bound conformations. As they most likely mediate IDP-target binding via conformational selection their helical content can be an important feature for IDP function. © 2013 Elsevier B.V
Oxidation and Release of Ruthenium from Short Fuel Rods above 1500oC
The fission product ruthenium is radiotoxic and in oxidized form as ruthenium-tetroxide
(RuO4) also chemical toxic. During fuel element change or in case of a leakage in fuel storages, air flows in the containment or fuel storage. If the circulation pump fails, the fuel elements are heated-up, and at high temperatures gaseous ruthenium oxides are formed and rapidly released from the fuel. Due to the significant higher volatility of RuO4 in the Chernobyl Catastrophe the measured concentration of the Ru-isotopes in the fall-outs was comparable to those of iodine and caesium. In order to get more insight in the chemical and physical behaviour of this fission product under severe accident conditions, the Ruthenium release was studied in a series of Separate Effect Tests (RUSET). In the test short fuel rod segments were used and exposed to air and steam atmosphere at high temperatures. The experiments in air atmosphere showed, that the partial pressures of the released Ru-oxides was two orders of magnitudes lower compared to those measured in previous tests with Ru-powder diluted in a ZrO2 matrix. It was found that ruthenium was not released in steam atmosphere in
the examined temperature range. Furthermore, the temperature dependence of the deposition was detected by XRF analysis.JRC.F.4-Nuclear design safet
Statistical measures of transcriptional diversity capture genomic heterogeneity of cancer
International audienceMolecular heterogeneity of tumors suggests the presence of multiple different subclones that may limit response to targeted therapies and contribute to acquisition of drug resistance, but its quantification has remained challenging
Crossover of texture and morphology in (Ti1 − xAlx)1 − yYyN alloy films and the pathway of structure evolution
In our earlier published work, we have shown that there is a composition range of the (Ti 1 − x Al x ) 1 − y Y y N alloy
films (0.72 b Ti/Al b 0.88) deposited at oblique vapour beam incidence and 500 °C (corresponding to zone T) in
which mixed cubic TiN (c-TiN) and wurtzite AlN (w-AlN) structures were formed together with an unusual
complex texture. The texture of c-TiN phase changed from 〈001〉 to b111N at a certain thickness forming a definite
crossover. Moreover the c-TiNb111N and the w-AlN〈0001〉 crystals were epitaxially related with axes tilted to the
direction of the vapour beam.
Based on a comprehensive transmission electron microscopy (TEM) and diffraction (XRD and selected area
electron diffraction (SAED)) structure and morphology analysis, we discovered the details of this exotic structure
making it possible to construct the complex pathway of structure evolution including the formation of the w-AlN
phase and the change of the dominating texture of c-TiN phase with thickness in dependence of the Ti/Al ratio
and the deposition parameters. This pathway could be deduced from the fundamental phenomena of structure
formation and may be generalised for multi-component thin film systems. A composition structure zone
model has been also proposed for the (Ti 1 − x Al x ) 1 − y Y y N thin film system in the 0 b x b 1 composition range
Crossover of texture and morphology in (Ti 1 − x Al x ) 1 − y Y y N alloy films and the pathway of structure evolution
In our earlier published work, we have shown that there is a composition range of the (Ti 1 − x Al x ) 1 − y Y y N alloy
films (0.72 b Ti/Al b 0.88) deposited at oblique vapour beam incidence and 500 °C (corresponding to zone T) in
which mixed cubic TiN (c-TiN) and wurtzite AlN (w-AlN) structures were formed together with an unusual
complex texture. The texture of c-TiN phase changed from 〈001〉 to b111N at a certain thickness forming a definite
crossover. Moreover the c-TiNb111N and the w-AlN〈0001〉 crystals were epitaxially related with axes tilted to the
direction of the vapour beam.
Based on a comprehensive transmission electron microscopy (TEM) and diffraction (XRD and selected area
electron diffraction (SAED)) structure and morphology analysis, we discovered the details of this exotic structure
making it possible to construct the complex pathway of structure evolution including the formation of the w-AlN
phase and the change of the dominating texture of c-TiN phase with thickness in dependence of the Ti/Al ratio
and the deposition parameters. This pathway could be deduced from the fundamental phenomena of structure
formation and may be generalised for multi-component thin film systems. A composition structure zone
model has been also proposed for the (Ti 1 − x Al x ) 1 − y Y y N thin film system in the 0 b x b 1 composition range
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