2,236 research outputs found
The study of s-process nucleosynthesis based on barium stars, CEMP-s and CEMP-r/s stars
In order to get a broader view of the s-process nucleosynthesis we study the
abundance distribution of heavy elements of 35 barium stars and 24 CEMP-stars,
including nine CEMP-s stars and 15 CEMP-r/s stars. The similar distribution of
[Pb/hs] between CEMP-s and CEMP-r/s stars indicate that the s-process material
of both CEMP-s and CEMP-r/s stars should have a uniform origin, i.e. mass
transfer from their predominant AGB companions. For the CEMP-r/s stars, we
found that the r-process should provide similar proportional contributes to the
second s-peak and the third s-peak elements, and also be responsible for the
higher overabundance of heavy elements than those in CEMP-s stars. Which hints
that the r-process origin of CEMP-r/s stars should be closely linked to the
main r-process. The fact that some small values exist for both barium and
CEMP-s stars, implies that the single exposure event of the s-process
nucleosynthesis should be general in a wide metallicity range of our Galaxy.
Based on the relation between and , we suggest that the origin
of r-elements for CEMP-r/s stars have more sources. A common scenario is that
the formation of the binary system was triggered by only one or a few
supernova. In addition, accretion-induced collapse(AIC) or SN 1.5 should be the
supplementary scenario, especially for these whose pre-AGB companion with
higher mass and smaller orbit radius, which support the higher values of both
and .Comment: 21 pages, 12 figures, accepted publication in APS
Is There a Long-Run Trade-Off between Inflation and Unemployment?
How are inflation and unemployment related in the long run? Are they negatively correlated, as in the so-called naive Phillips curve theories or uncorrelated, 'as in the neo-liberals' view or are they positively correlated as Friedman suggested in his Nobel lecture? In this paper inflation is introduced into a general equilibrium search unemployment model. We show that it is possible to get either a negatively or a positively sloping long-run Phillips curve, all depending on the source of inflation
Threshold for the Outbreak of Cascading Failures in Degree-degree Uncorrelated Networks
In complex networks, the failure of one or very few nodes may cause cascading
failures. When this dynamical process stops in steady state, the size of the
giant component formed by remaining un-failed nodes can be used to measure the
severity of cascading failures, which is critically important for estimating
the robustness of networks. In this paper, we provide a cascade of overload
failure model with local load sharing mechanism, and then explore the threshold
of node capacity when the large-scale cascading failures happen and un-failed
nodes in steady state cannot connect to each other to form a large connected
sub-network. We get the theoretical derivation of this threshold in
degree-degree uncorrelated networks, and validate the effectiveness of this
method in simulation. This threshold provide us a guidance to improve the
network robustness under the premise of limited capacity resource when creating
a network and assigning load. Therefore, this threshold is useful and important
to analyze the robustness of networks.Comment: 11 pages, 4 figure
Non-commutative Solitons in Finite Quantum Mechanics
We construct the unitary evolution operators that realize the quantization of
linear maps of SL(2,R) over phase spaces of arbitrary integer discretization N
and show the non-trivial dependence on the arithmetic nature of N. We discuss
the corresponding uncertainty principle and construct the corresponding
coherent states, that may be interpreted as non-commutative solitons.Comment: 3 pages LaTeX. Uses espcrc2.sty and amssymb.sty. Contribution to
Lattice 2002(theoretical
Chitinolytic Bacteria-Assisted Conversion of Squid Pen and Its Effect on Dyes and Pigments Adsorption
[[abstract]]The aim of this work was to produce chitosanase by fermenting from squid pen, and recover the fermented squid pen for dye removal by adsorption. One chitosanase induced from squid pen powder (SPP)-containing medium by Bacillus cereus TKU034 was purified in high purification fold (441) and high yield of activity recovery (51%) by ammonium sulfate precipitation and combined column chromatography. The SDS-PAGE results showed its molecular mass to be around 43 kDa. The TKU034 chitosanase used for the chitooligomers preparation was studied. The enzyme products revealed that the chitosanase could degrade chitosan with various degrees of polymerization, ranging from 3 to 9, as well as the chitosanase in an endolytic manner. Besides, the fermented SPP was recovered and displayed a better adsorption rate (up to 99.5%) for the disperse dyes (red, yellow, blue, and black) than the water-soluble food colorants, Allura Red AC (R40) and Tartrazine (Y4). The adsorbed R40 on the unfermented SPP and the fermented SPP was eluted by distilled water and 1 M NaOH to confirm the dye adsorption mechanism. The fermented SPP had a slightly higher adsorption capacity than the unfermented, and elution of the dye from the fermented SPP was easier than from the unfermented. The main dye adsorption mechanism of fermented SPP was physical adsorption, while the adsorption mechanism of unfermented SPP was chemical adsorption.[[notice]]補正完
Exploring a structural protein-drug interactome for new therapeutics in lung cancer
The pharmacology of drugs is often defined by more than one protein target. This property can be exploited to use approved drugs to uncover new targets and signaling pathways in cancer. Towards enabling a rational approach to uncover new targets, we expand a structural protein-ligand interactome () by scoring the interaction among 1000 FDA-approved drugs docked to 2500 pockets on protein structures of the human genome. This afforded a drug-target network whose properties compared favorably with previous networks constructed using experimental data. Among drugs with the highest degree and betweenness two are cancer drugs and one is currently used for treatment of lung cancer. Comparison of predicted cancer and non-cancer targets reveals that the most cancer-specific compounds were also the most selective compounds. Analysis of compound flexibility, hydrophobicity, and size showed that the most selective compounds were low molecular weight fragment-like heterocycles. We use a previously-developed screening approach using the cancer drug erlotinib as a template to screen other approved drugs that mimic its properties. Among the top 12 ranking candidates, four are cancer drugs, two of them kinase inhibitors (like erlotinib). Cellular studies using non-small cell lung cancer (NSCLC) cells revealed that several drugs inhibited lung cancer cell proliferation. We mined patient records at the Regenstrief Medical Record System to explore the possible association of exposure to three of these drugs with occurrence of lung cancer. Preliminary in vivo studies using the non-small cell lung cancer (NCLSC) xenograft model showed that losartan- and astemizole-treated mice had tumors that weighed 50 (p < 0.01) and 15 (p < 0.01) percent less than the treated controls. These results set the stage for further exploration of these drugs and to uncover new drugs for lung cancer therapy
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