51,193 research outputs found
Correlations among superconductivity, structural instability, and band filling in Nb1-xB2 at the critical point x=0.2
We performed an extensive investigation on the correlations among
superconductivity, structural instability and band filling in Nb1-xB2
materials. Structural measurements reveal that a notable phase transformation
occurs at x=0.2, corresponding to the Fermi level (EF) in the pseudogap with
the minimum total density of states (DOS) as demonstrated by the
first-principles calculations. Superconductivity in Nb1-xB2 generally becomes
visible in the Nb-deficient materials with x=0.2. Electron energy-loss
spectroscopy (EELS) measurements on B K-edge directly demonstrated the presence
of a chemical shift arising from the structural transformation. Our
systematical experimental results in combination with theoretical analysis
suggest that the emergence of hole states in the sigma-bands plays an important
role for understanding the superconductivity and structural transition in
Nb1-xB2.Comment: 16 pages, 4 figure
Probing Quantum Hall Pseudospin Ferromagnet by Resistively Detected NMR
Resistively Detected Nuclear Magnetic Resonance (RD-NMR) has been used to
investigate a two-subband electron system in a regime where quantum Hall
pseudo-spin ferromagnetic (QHPF) states are prominently developed. It reveals
that the easy-axis QHPF state around the total filling factor can be
detected by the RD-NMR measurement. Approaching one of the Landau level (LL)
crossing points, the RD-NMR signal strength and the nuclear spin relaxation
rate enhance significantly, a signature of low energy spin
excitations. However, the RD-NMR signal at another identical LL crossing point
is surprisingly missing which presents a puzzle
Application of Volcano Plots in Analyses of mRNA Differential Expressions with Microarrays
Volcano plot displays unstandardized signal (e.g. log-fold-change) against
noise-adjusted/standardized signal (e.g. t-statistic or -log10(p-value) from
the t test). We review the basic and an interactive use of the volcano plot,
and its crucial role in understanding the regularized t-statistic. The joint
filtering gene selection criterion based on regularized statistics has a curved
discriminant line in the volcano plot, as compared to the two perpendicular
lines for the "double filtering" criterion. This review attempts to provide an
unifying framework for discussions on alternative measures of differential
expression, improved methods for estimating variance, and visual display of a
microarray analysis result. We also discuss the possibility to apply volcano
plots to other fields beyond microarray.Comment: 8 figure
Influence of aggregation and linker proteins on chromophore structure in allophycocyanin (Mastigocladus laminosus).
A time-domain recursive method to analyse transient wave propagation across rock joints
The present investigation is concerned with transient wave propagation in a rock mass with a set of parallel joints by using a recursive method. According to the displacement field of a rock mass with a set of parallel joints, the interaction between four plane waves (two longitudinal-waves and two transverse-waves) and a joint is analysed first. With the displacement discontinuity model and the time shifting function, the wave propagation equation based on the recursive method in time domain for obliquely longitudinal-(P) or transverse-(S) waves across a set of parallel joints is established. The joints are assumed linearly elastic. The analytical solution obtained by the proposed method is compared with the existing results for some special cases, including oblique incidence across a single joint and normal incidence across a set of parallel joints. By verification, it is found that the solutions by the proposed method match very well with the existing methods. The applicability and limitations of the new method are then discussed for incident waves with different properties
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