17,508 research outputs found
Cluster induced quenching of galaxies in the massive cluster XMMXCSJ2215.9-1738 at z~1.5 traced by enhanced metallicities inside half R200
(Abridged) We explore the massive cluster XMMXCSJ2215.9-1738 at z~1.5 with
KMOS spectroscopy of Halpha and [NII] covering a region that corresponds to
about one virial radius. Using published spectroscopic redshifts of 108
galaxies in and around the cluster we computed the location of galaxies in the
projected velocity vs. position phase-space to separate our cluster sample into
a virialized region of objects accreted longer ago (roughly inside half R200)
and a region of infalling galaxies. We measured oxygen abundances for ten
cluster galaxies with detected [NII] lines in the individual galaxy spectra and
compared the MZR of the galaxies inside half R200 with the infalling galaxies
and a field sample at similar redshifts. We find that the oxygen abundances of
individual z~1.5 star-forming cluster galaxies inside half R200 are comparable,
at the respective stellar mass, to the higher local SDSS metallicity values. We
find that the [NII]/Halpha line ratios inside half R200 are higher by 0.2 dex
and that the resultant metallicities of the galaxies in the inner part of the
cluster are higher by about 0.1 dex, at a given mass, than the metallicities of
infalling galaxies and of field galaxies at z~1.5. The enhanced metallicities
of cluster galaxies at z~1.5 inside half R200 indicate that the density of the
ICM in this massive cluster becomes high enough toward the cluster center such
that the ram pressure exceeds the restoring pressure of the hot gas reservoir
of cluster galaxies. This can remove the gas reservoir initiating quenching;
although the galaxies continue to form stars, albeit at slightly lower rates,
using the available cold gas in the disk which is not stripped.Comment: Accepted for publication in A&
Dose-dependent new bone formation by extracorporeal shock wave application on the intact femur of rabbits
Background: Whereas various molecular working mechanisms of shock waves have been demonstrated, no study has assessed in detail the influence of varying energy flux densities (EFD) on new bone formation in vivo. Methods: Thirty Chinchilla bastard rabbits were randomly assigned to 5 groups (EFD 0.0, 0.35, 0.5, 0.9 and 1.2 mJ/mm(2)) and treated with extracorporeal shock waves at the distal femoral region (1,500 pulses; 1 Hz frequency). To investigate new bone formation, animals were injected with oxytetracycline at days 5-9 after shock wave application and sacrificed on day 10. Histological sections of all animals were examined using broad-band epifluorescent illumination, contact microradiography and Giemsa-Eosin staining. Results: Application of shock waves induced new bone formation beginning with 0.5 mJ/mm(2) EFD and increasing with 0.9 mJ/mm(2) and 1.2 mJ/mm(2). The latter EFD resulted in new bone formation also on the dorsal cortical bone; cortical fractures and periosteal detachment also occurred. Conclusion: Here, for the first time, a threshold level is presented for new bone formation after applying shock waves to intact bone in vivo. The findings of this study are of considerable significance for preventing unwanted side effects in new approaches in the clinical application of shock waves. Copyright (c) 2008 S. Karger AG, Basel
Globular Structures of a Helix-Coil Copolymer: Self-Consistent Treatment
A self-consistent field theory was developed in the grand-canonical ensemble
formulation to study transitions in a helix-coil multiblock globule. Helical
and coil parts are treated as stiff rods and self-avoiding walks of variable
lengths correspondingly. The resulting field-theory takes, in addition to the
conventional Zimm-Bragg (B.H. Zimm, I.K. Bragg, J. Chem. Phys. 31, 526 (1959))
parameters, also three-dimensional interaction terms into account. The
appropriate differential equations which determine the self-consistent fields
were solved numerically with finite element method. Three different phase
states are found: open chain, amorphous globule and nematic liquid-crystalline
(LC) globule. The LC-globule formation is driven by the interplay between the
hydrophobic helical segments attraction and the anisotropic globule surface
energy of an entropic nature. The full phase diagram of the helix-coil
copolymer was calculated and thoroughly discussed. The suggested theory shows a
clear interplay between secondary and tertiary structures in globular
homopolypeptides.Comment: 26 pages, 30 figures, corrected some typo
Systematic study of d-wave superconductivity in the 2D repulsive Hubbard model
The cluster size dependence of superconductivity in the conventional
two-dimensional Hubbard model, commonly believed to describe high-temperature
superconductors, is systematically studied using the Dynamical Cluster
Approximation and Quantum Monte Carlo simulations as cluster solver. Due to the
non-locality of the d-wave superconducting order parameter, the results on
small clusters show large size and geometry effects. In large enough clusters,
the results are independent of the cluster size and display a finite
temperature instability to d-wave superconductivity.Comment: 4 pages, 3 figures; updated with version published in PRL; added
values of Tc obtained from fit
Efficient calculation of the antiferromagnetic phase diagram of the 3D Hubbard model
The Dynamical Cluster Approximation with Betts clusters is used to calculate
the antiferromagnetic phase diagram of the 3D Hubbard model at half filling.
Betts clusters are a set of periodic clusters which best reflect the properties
of the lattice in the thermodynamic limit and provide an optimal finite-size
scaling as a function of cluster size. Using a systematic finite-size scaling
as a function of cluster space-time dimensions, we calculate the
antiferromagnetic phase diagram. Our results are qualitatively consistent with
the results of Staudt et al. [Eur. Phys. J. B 17 411 (2000)], but require the
use of much smaller clusters: 48 compared to 1000
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Integration with Ontologies
One of today’s hottest IT topics is integration, as bringing together information from different sources and structures is not completely solved. The approach outlined here wants to illustrate how ontologies [Gr93] could help to support the integration process
Combined density-functional and dynamical cluster quantum Monte Carlo calculations for three-band Hubbard models for hole-doped cuprate superconductors
Using a combined local density functional theory (LDA-DFT) and quantum Monte
Carlo (QMC) dynamic cluster approximation approach, the parameter dependence of
the superconducting transition temperature Tc of several single-layer
hole-doped cuprate superconductors with experimentally very different Tcmax is
investigated. The parameters of two different three-band Hubbard models are
obtained using the LDA and the downfolding Nth-order muffin-tin orbital
technique with N=0 and 1 respectively. QMC calculations on 4-site clusters show
that the d-wave transition temperature Tc depends sensitively on the
parameters. While the N=1 MTO basis set which reproduces all three
bands leads to a d-wave transition, the N=0 set which merely reproduces the LDA
Fermi surface and velocities does not
Construct, Merge, Solve and Adapt: Application to the repetition-free longest common subsequence problem
In this paper we present the application of a recently proposed, general, algorithm for combinatorial optimization to the repetition-free longest common subsequence problem. The applied algorithm, which is labelled Construct, Merge, Solve & Adapt, generates sub-instances based on merging the solution components found in randomly constructed solutions. These sub-instances are subsequently solved by means of an exact solver. Moreover, the considered sub-instances are dynamically changing due to adding new solution components at each iteration, and removing existing solution components on the basis of indicators about their usefulness. The results of applying this algorithm to the repetition-free longest common subsequence problem show that the algorithm generally outperforms competing approaches from the literature. Moreover, they show that the algorithm is competitive with CPLEX for small and medium size problem instances, whereas it outperforms CPLEX for larger problem instances.Peer ReviewedPostprint (author's final draft
EIT ground-state cooling of long ion strings
Electromagnetically-induced-transparency (EIT) cooling is a ground-state
cooling technique for trapped particles. EIT offers a broader cooling range in
frequency space compared to more established methods. In this work, we
experimentally investigate EIT cooling in strings of trapped atomic ions. In
strings of up to 18 ions, we demonstrate simultaneous ground state cooling of
all radial modes in under 1 ms. This is a particularly important capability in
view of emerging quantum simulation experiments with large numbers of trapped
ions. Our analysis of the EIT cooling dynamics is based on a novel technique
enabling single-shot measurements of phonon numbers, by rapid adiabatic passage
on a vibrational sideband of a narrow transition
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