10,959 research outputs found
Bis[2-(1H-1,2,4-triazol-1-yl-κN 2)-1,10-phenanthroline-κ2 N,N′]zinc(II) bisÂ(perchlorate)
In the title complex, [Zn(C14H9N5)2](ClO4)2, 2-(1H-1,2,4-triazol-1-yl)-1,10-phenanthroline functions as a tridentate ligand and the ZnII ion assumes a distorted octaÂhedral ZnN6 coordination geometry. There is a weak π–π stacking interÂaction between symmetry-related triazolyl rings with a centroid–centroid distance of 3.802 (4) Å and a perpendicular distance of 3.413 Å between the rings
Fidelity, dynamic structure factor, and susceptibility in critical phenomena
Motivated by the growing importance of fidelity in quantum critical
phenomena, we establish a general relation between fidelity and structure
factor of the driving term in a Hamiltonian through a newly introduced concept:
fidelity susceptibility. Our discovery, as shown by some examples, facilitates
the evaluation of fidelity in terms of susceptibility using well developed
techniques such as density matrix renormalization group for the ground state,
or Monte Carlo simulations for the states in thermal equilibrium.Comment: 4 pages, 2 figures, final version accepted by PR
Constrain on possible pairing symmetry in a two-orbital model of FeAs-based superconductors
In this work, we establish a few exact identities through commutation of
intra-orbital and inter-orbital on-site pairings with a two-orbital model
describing newly discovered FeAs-based superconductors. Applying the conclusion
drawn from rigorous relation and physical interpretation, we give constraints
on the possible symmetries of the superconducting pairing of the model. Hence
the favorable pairings in newly discovered high-temperature oxypnictide
superconductors are proposed.Comment: 5 pages, 2 figure
Diagnostic value of two dimensional shear wave elastography combined with texture analysis in early liver fibrosis.
BACKGROUND: Staging diagnosis of liver fibrosis is a prerequisite for timely diagnosis and therapy in patients with chronic hepatitis B. In recent years, ultrasound elastography has become an important method for clinical noninvasive assessment of liver fibrosis stage, but its diagnostic value for early liver fibrosis still needs to be further improved. In this study, the texture analysis was carried out on the basis of two dimensional shear wave elastography (2D-SWE), and the feasibility of 2D-SWE plus texture analysis in the diagnosis of early liver fibrosis was discussed.
AIM: To assess the diagnostic value of 2D-SWE combined with textural analysis in liver fibrosis staging.
METHODS: This study recruited 46 patients with chronic hepatitis B. Patients underwent 2D-SWE and texture analysis; Young\u27s modulus values and textural patterns were obtained, respectively. Textural pattern was analyzed with regard to contrast, correlation, angular second moment (ASM), and homogeneity. Pathological results of biopsy specimens were the gold standard; comparison and assessment of the diagnosis efficiency were conducted for 2D-SWE, texture analysis and their combination.
RESULTS: 2D-SWE displayed diagnosis efficiency in early fibrosis, significant fibrosis, severe fibrosis, and early cirrhosis (AUC \u3e 0.7, P \u3c 0.05) with respective AUC values of 0.823 (0.678-0.921), 0.808 (0.662-0.911), 0.920 (0.798-0.980), and 0.855 (0.716-0.943). Contrast and homogeneity displayed independent diagnosis efficiency in liver fibrosis stage (AUC \u3e 0.7, P \u3c 0.05), whereas correlation and ASM showed limited values. AUC of contrast and homogeneity were respectively 0.906 (0.779-0.973), 0.835 (0.693-0.930), 0.807 (0.660-0.910) and 0.925 (0.805-0.983), 0.789 (0.639-0.897), 0.736 (0.582-0.858), 0.705 (0.549-0.883) and 0.798 (0.650-0.904) in four liver fibrosis stages, which exhibited equivalence to 2D-SWE in diagnostic efficiency (P \u3e 0.05). Combined diagnosis (PRE) displayed diagnostic efficiency (AUC \u3e 0.7, P \u3c 0.01) for all fibrosis stages with respective AUC of 0.952 (0.841-0.994), 0.896 (0.766-0.967), 0.978 (0.881-0.999), 0.947 (0.835-0.992). The combined diagnosis showed higher diagnosis efficiency over 2D-SWE in early liver fibrosis (P \u3c 0.05), whereas no significant differences were observed in other comparisons (P \u3e 0.05).
CONCLUSION: Texture analysis was capable of diagnosing liver fibrosis stage, combined diagnosis had obvious advantages in early liver fibrosis, liver fibrosis stage might be related to the hepatic tissue hardness distribution
Uplift, Climate and Biotic Changes at the Eocene-Oligocene Transition in Southeast Tibet
The uplift history of southeastern Tibet is crucial to understanding processes driving the tectonic evolution of the Tibetan Plateau and surrounding areas. Underpinning existing palaeoaltimetric studies has been regional mapping based in large part on biostratigraphy that assumes a Neogene modernisation of the highly diverse, but threatened, Asian biota. Here, with new radiometric dating and newly-collected plant fossil archives, we quantify the surface height of part of Tibet’s southeastern margin of Tibet in the latest Eocene (~34 Ma) to be ~3 km and rising, possibly attaining its present elevation (3.9 km) in the early Oligocene. We also find that the Eocene-Oligocene transition in southeastern Tibet witnessed leaf size diminution and a floral composition change from sub-tropical/warm temperate to cool temperate, likely reflective of both uplift and secular climate change, and that by the latest Eocene floral modernization on Tibet had already taken place implying modernization was deeply-rooted in the Paleogene
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