6,181 research outputs found
FFT-LB modeling of thermal liquid-vapor systems
We further develop a thermal LB model for multiphase flows. In the improved
model, we propose to use the FFT scheme to calculate both the convection term
and external force term. The usage of FFT scheme is detailed and analyzed. By
using the FFT algorithm spatiotemporal discretization errors are decreased
dramatically and the conservation of total energy is much better preserved. A
direct consequence of the improvement is that the unphysical spurious
velocities at the interfacial regions can be damped to neglectable scale.
Together with the better conservation of total energy, the more accurate flow
velocities lead to the more accurate temperature field which determines the
dynamical and final states of the system. With the new model, the phase diagram
of the liquid-vapor system obtained from simulation is more consistent with
that from theoretical calculation. Very sharp interfaces can be achieved. The
accuracy of simulation results are also verified by the Laplace law. The FFT
scheme can be easily applied to other models for multiphase flows.Comment: 34 pages, 21 figure
Hamiltonian type Lie bialgebras
We first prove that, for any generalized Hamiltonian type Lie algebra ,
the first cohomology group is trivial. We then show that
all Lie bialgebra structures on are triangular.Comment: LaTeX, 16 page
the fire assay reloaded
The fire assay process is still the most accurate and precise method for measuring the gold content in gold alloys. Scanning electron microscopy and transmission electron microscopy have been applied to observe the change in microstructure of the samples undergoing the fire assay process. The performed observations reveal that the microstructure of the specimen is more complex than expected. Before the parting stage, the specimen is not a perfect gold–silver binary alloy but contains also copper–silver oxides and other residual compounds. The parting stage appears to be a dealloying process leading to a nanoporous gold nanostructure. What observed after partition explains the evolution of the shape and colour of the specimen and may allow for a better comprehension of the procedure and an improvement in the method
Integrative analyses of transcriptome sequencing identify novel functional lncRNAs in esophageal squamous cell carcinoma.
Long non-coding RNAs (lncRNAs) have a critical role in cancer initiation and progression, and thus may mediate oncogenic or tumor suppressing effects, as well as be a new class of cancer therapeutic targets. We performed high-throughput sequencing of RNA (RNA-seq) to investigate the expression level of lncRNAs and protein-coding genes in 30 esophageal samples, comprised of 15 esophageal squamous cell carcinoma (ESCC) samples and their 15 paired non-tumor tissues. We further developed an integrative bioinformatics method, denoted URW-LPE, to identify key functional lncRNAs that regulate expression of downstream protein-coding genes in ESCC. A number of known onco-lncRNA and many putative novel ones were effectively identified by URW-LPE. Importantly, we identified lncRNA625 as a novel regulator of ESCC cell proliferation, invasion and migration. ESCC patients with high lncRNA625 expression had significantly shorter survival time than those with low expression. LncRNA625 also showed specific prognostic value for patients with metastatic ESCC. Finally, we identified E1A-binding protein p300 (EP300) as a downstream executor of lncRNA625-induced transcriptional responses. These findings establish a catalog of novel cancer-associated functional lncRNAs, which will promote our understanding of lncRNA-mediated regulation in this malignancy
Block of NMDA receptor channels by endogenous neurosteroids: implications for the agonist induced conformational states of the channel vestibule
N-methyl-D-aspartate receptors (NMDARs) mediate synaptic plasticity, and their dysfunction is implicated in multiple brain disorders. NMDARs can be allosterically modulated by numerous compounds, including endogenous neurosteroid pregnanolone sulfate. Here, we identify the molecular basis of the use-dependent and voltage-independent inhibitory effect of neurosteroids on NMDAR responses. The site of action is located at the extracellular vestibule of the receptor's ion channel pore and is accessible after receptor activation. Mutations in the extracellular vestibule in the SYTANLAAF motif disrupt the inhibitory effect of negatively charged steroids. In contrast, positively charged steroids inhibit mutated NMDAR responses in a voltage-dependent manner. These results, in combination with molecular modeling, characterize structure details of the open configuration of the NMDAR channel. Our results provide a unique opportunity for the development of new therapeutic neurosteroid-based ligands to treat diseases associated with dysfunction of the glutamate system
1RXS J232953.9+062814: a New SU UMa Dwarf Nova below the Period Minimum
1RXS J232953.9+062814 was identified as a cataclysmic variable by Wei et al.
(1999). Four low-resolution spectra of 1RXS J232953.9+062814 were obtained by
using the 2.16-m telescope of the National Astronomical Observatories, in which
two of them were at outburst, and the other two were at quiescence. The system
is about 16.8 B and 16.5 V at quiescence, and 12.6 B and 12.6 V at outburst.
The quiescent spectra were dominated by double-peaked Balmer emissions, which
indicates a hydrogen-rich system with a high-inclination accretion disc. MgH
and TiO absorption bands appeared in the quiescent spectrum imply a companion
with a spectral type of early M dwarf. If we take it as a M0 dwarf, the system
is located at a distance of 350 pc with a proper motion velocity 150 km
s. The superhump period of 0.046311 days (Uemura et al. 2001) was
confirmed by our V photometry. The short period and the hydrogen-rich nature
reveal that this system is another SU Ursae Majoris-type dwarf nova below the
period minimum after V485 Centauri. 1RXS J232953.9+062814 is one of the most
important systems for studying the evolutionary scenario of cataclysmic
variables since it is much brighter than V485 Cen.Comment: 4 pages, 2 figures, accepted by Chin. J. Astron. Astrophy
Hierarchical information clustering by means of topologically embedded graphs
We introduce a graph-theoretic approach to extract clusters and hierarchies
in complex data-sets in an unsupervised and deterministic manner, without the
use of any prior information. This is achieved by building topologically
embedded networks containing the subset of most significant links and analyzing
the network structure. For a planar embedding, this method provides both the
intra-cluster hierarchy, which describes the way clusters are composed, and the
inter-cluster hierarchy which describes how clusters gather together. We
discuss performance, robustness and reliability of this method by first
investigating several artificial data-sets, finding that it can outperform
significantly other established approaches. Then we show that our method can
successfully differentiate meaningful clusters and hierarchies in a variety of
real data-sets. In particular, we find that the application to gene expression
patterns of lymphoma samples uncovers biologically significant groups of genes
which play key-roles in diagnosis, prognosis and treatment of some of the most
relevant human lymphoid malignancies.Comment: 33 Pages, 18 Figures, 5 Table
Full coherent control of nuclear spins in an optically pumped single quantum dot
Highly polarized nuclear spins within a semiconductor quantum dot (QD) induce
effective magnetic (Overhauser) fields of up to several Tesla acting on the
electron spin or up to a few hundred mT for the hole spin. Recently this has
been recognized as a resource for intrinsic control of QD-based spin quantum
bits. However, only static long-lived Overhauser fields could be used. Here we
demonstrate fast redirection on the microsecond time-scale of Overhauser fields
of the order of 0.5 T experienced by a single electron spin in an optically
pumped GaAs quantum dot. This has been achieved using full coherent control of
an ensemble of 10^3-10^4 optically polarized nuclear spins by sequences of
short radio-frequency (rf) pulses. These results open the way to a new class of
experiments using rf techniques to achieve highly-correlated nuclear spins in
quantum dots, such as adiabatic demagnetization in the rotating frame leading
to sub-micro K nuclear spin temperatures, rapid adiabatic passage, and spin
squeezing
The Mitochondrial Ca(2+) Uniporter: Structure, Function, and Pharmacology.
Mitochondrial Ca(2+) uptake is crucial for an array of cellular functions while an imbalance can elicit cell death. In this chapter, we briefly reviewed the various modes of mitochondrial Ca(2+) uptake and our current understanding of mitochondrial Ca(2+) homeostasis in regards to cell physiology and pathophysiology. Further, this chapter focuses on the molecular identities, intracellular regulators as well as the pharmacology of mitochondrial Ca(2+) uniporter complex
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