11,021 research outputs found
Nonequilibrium dynamical mean-field theory for bosonic lattice models
We develop the nonequilibrium extension of bosonic dynamical mean field
theory (BDMFT) and a Nambu real-time strong-coupling perturbative impurity
solver. In contrast to Gutzwiller mean-field theory and strong coupling
perturbative approaches, nonequilibrium BDMFT captures not only dynamical
transitions, but also damping and thermalization effects at finite temperature.
We apply the formalism to quenches in the Bose-Hubbard model, starting both
from the normal and Bose-condensed phases. Depending on the parameter regime,
one observes qualitatively different dynamical properties, such as rapid
thermalization, trapping in metastable superfluid or normal states, as well as
long-lived or strongly damped amplitude oscillations. We summarize our results
in non-equilibrium "phase diagrams" which map out the different dynamical
regimes.Comment: 18 pages, 8 figure
Influence of electromagnetic Field Damping on the Vibration Stability of soft mounted Induction Motors with Sleeve Bearings, based on a Multibody Model
The paper shows an analytical vibration model for stability analysis of soft mounted induction motors with sleeve bearings, especially focusing on the influence of electromagnetic field damping on the limit of vibration stability. The model is a multibody model, considering the electromagnetic influence – including the electromagnetic field damping effect –, stiffness and internal material damping of the rotor structure, stiffness and damping of the bearing housings and end shields, stiffness and damping of the foundation elements and stiffness and damping of the oil film of the sleeve bearings. The aim of the paper is to unite all these influences in a model and to derive a procedure for calculating the limit of vibration stability, with considering the electromagnetic field damping effect. Additionally, a numerical example is presented, where the influence of electromagnetic field damping on the limit of vibration stability is shown, as well as the influence of the foundation elements and of the internal damping of the rotor. The procedure and conclusions can also be adopted into finite-element analysis
Glacier motion estimation using SAR offset-tracking procedures
Two image-to-image patch offset techniques for
estimating feature motion between satellite synthetic aperture radar (SAR) images are discussed. Intensity tracking, based on patch intensity cross-correlation optimization, and coherence tracking, based on patch coherence optimization, are used to estimate the movement of glacier surfaces between two SAR images in both slant-range and azimuth direction. The accuracy and application range of the two methods are examined in the case of the surge of Monacobreen in Northern Svalbard between
1992 and 1996. Offset-tracking procedures of SAR images are an alternative to differential SAR interferometry for the estimation of glacier motion when differential SAR interferometry is limited by loss of coherence, i.e., in the case of rapid and incoherent flow and of large acquisition time intervals between the two SAR images. In addition, an offset-tracking procedure in the azimuth
direction may be combined with differential SAR interferometry in the slant-range direction in order to retrieve a two-dimensional displacement map when SAR data of only one orbit configuration are available
Electro-Disintegration of Tensor Polarized Deuterium
A tensor polarized target in Hall A at Jefferson Lab would offer the possibility to measure the D(e, e\u27p)n cross section for the Ms = 0 and the Ms = ±1 states separately (the quantization axis is along the momentum transfer). These data would serve as a new, stringent test of our current understanding of the deuteron structure for missing momenta up to 450 MeV/c, a region where the deuteron wave function is dominated by the D-state. No data exist to date for missing momenta above 150 MeV/c. The technique to separate these cross sections, possible kinematic settings, and a rough estimate of the achievable precision is presented
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Multisite dependency of an E3 ligase controls monoubiquitylation-dependent cell fate decisions.
Metazoan development depends on tightly regulated gene expression programs that instruct progenitor cells to adopt specialized fates. Recent work found that posttranslational modifications, such as monoubiquitylation, can determine cell fate also independently of effects on transcription, yet how monoubiquitylation is implemented during development is poorly understood. Here, we have identified a regulatory circuit that controls monoubiquitylation-dependent neural crest specification by the E3 ligase CUL3 and its substrate adaptor KBTBD8. We found that CUL3KBTBD8 monoubiquitylates its essential targets only after these have been phosphorylated in multiple motifs by CK2, a kinase whose levels gradually increase during embryogenesis. Its dependency on multisite phosphorylation allows CUL3KBTBD8 to convert the slow rise in embryonic CK2 into decisive recognition of ubiquitylation substrates, which in turn is essential for neural crest specification. We conclude that multisite dependency of an E3 ligase provides a powerful mechanism for switch-like cell fate transitions controlled by monoubiquitylation
Analysis of Sedimentary Facies Using Bulk Mineralogic Characteristics in Cretaceous to Quaternary Sediments from the Kerguelen Plateau: Sites 737, 738, and 744
Carbonate-free portions of Upper Cretaceous to Holocene sediment samples from the Kerguelen Plateau in the
southern Indian Ocean were investigated by X-ray diffraction. Downhole variations in the content of opal-A, opal-CT,
quartz, feldspar, barite, and clinoptilolite were studied at Site 737 on the northern Kerguelen Plateau and at Sites 744
and 738 on the southern Kerguelen Plateau. The variation of these components reflects temporal changes in the depositional
history of the Kerguelen Plateau as well as major differences in the sedimentary evolution between the northern
plateau and the southern plateau.
Carbonate is the dominant component in the pelagic sediments on the Kerguelen Plateau. In addition, biogenic opal
sedimentation plays an important role throughout most of the sequence. A major increase in opal accumulation is documented
at all sites in late Miocene time, which is in accordance with the well-known increase in silica productivity
probably caused by a major cooling step. Because of its position near the Polar Frontal Zone, sediments from Site 737
show a more extensive opal deposition than at Sites 744 and 738. An earlier productivity pulse is documented at Site 744
on the southern plateau within the early Oligocene, following the initial phase of intense East Antarctic glaciation. This
cooling event resulted in higher amounts of ice-rafted terrigenous quartz and, to a lesser extent, feldspar. With the exception
of the Site 744 sediments, opal deposition in Paleogene and older sediments can be reconstructed only from the
diagenetic transformation products of opal-CT and probably clinoptilolite. In contrast to the southern sequence, on the
northern Kerguelen Plateau higher amounts of clinoptilolite and no opal-CT were found. These major differences in the
diagenetic environments may be due to extensive volcanism in the northern area. The volcanic influence at Site 737 is
well recorded by the higher feldspar content and higher amounts of volcanic glass shards
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