Spacelike hypersurfaces with negative total energy in de Sitter spacetime

De Sitter spacetime can be separated into two parts along two kinds of hypersurfaces and the half-de Sitter spacetimes are covered by the planar and hyperbolic coordinates respectively. Two positive energy theorems were proved previously for certain $\P$-asymptotically de Sitter and \H-asymptotically de Sitter initial data sets by the second author and collaborators. These initial data sets are asymptotic to time slices of the two kinds of half-de Sitter spacetimes respectively, and their mean curvatures are bounded from above by certain constants. While the mean curvatures violate these conditions, the spacelike hypersurfaces with negative total energy in the two kinds of half-de Sitter spacetimes are constructed in this short paper.Comment: 11 pages, final version, to appear in J. Math. Phy

Quantum correlation measure in arbitrary bipartite systems

A definition of quantum correlation is presented for an arbitrary bipartite quantum state based on the skew information. This definition not only inherits the good properties of skew information such as the contractivity and so on, but also is effective and almost analytically calculated for any bipartite quantum states. We also reveal the relation between our measure and quantum metrology. As applications, we give the exact expressions of quantum correlation for many states, which provides a direct support for our result.Comment: 6 pages, 2 figures. Comments are welcom

A study on the inhibitory effect of Solanum lyratum thumb extract on lewis lung carcinoma lines

The objective of this paper was to observe the effects of Solanum lyratum Thunb extract on tumour inhibition, immune function and survival time of tumour-bearing mice. Lung carcinoma-bearing mouse model was  established, the tumour-bearing mice were divided into model group, CTX group, Solanum lyratum Thunb extract high-dose group and low-dose group. By the examination of tumour inhibition rate of Solanum lyratum Thunb extract in Lewis lung carcinoma-bearing mice and determination of the number of NK cells and T cell subsets, the survival rate of tumour-bearing mice was observed. Solanum lyratum Thunb extract had some anti-tumour effect in Lewis tumour-bearing mice. The tumour inhibition rate of high-dose group reached 46.28%, and the tumour inhibition rate of low-dose group was 31.42%. Solanum lyratum Thunb extract can improve the NK cell activity of Lewis tumour-bearing mice, increase the number of CD4 cells in the tumour-bearing mice, and significantly increase the  survival rate of tumour-bearing mice. The study concluded that Solanum lyratum Thunb extract has some anti-tumour effect and can improve  immune function and survival rate of tumour-bearing mice.Keywords: Solanum lyratum Thunb; tumour-bearing mice; anti-tumour effec

Dimensional crossover of thermal conductance in graphene nanoribbons: A first-principles approach

First-principles density-functional calculations are performed to investigate the thermal transport properties in graphene nanoribbons (GNRs). The dimensional crossover of thermal conductance from one to two dimensions (2D) is clearly demonstrated with increasing ribbon width. The thermal conductance of GNRs in a few nanometer width already exhibits an approximate low-temperature dependence of $T^{1.5}$, like that of 2D graphene sheet which is attributed to the quadratic nature of dispersion relation for the out-of-plane acoustic phonon modes. Using a zone-folding method, we heuristically derive the dimensional crossover of thermal conductance with the increase of ribbon width. Combining our calculations with the experimental phonon mean-free path, some typical values of thermal conductivity at room temperature are estimated for GNRs and for 2D graphene sheet, respectively. Our findings clarify the issue of low-temperature dependence of thermal transport in GNRs and suggest a calibration range of thermal conductivity for experimental measurements in graphene-based materials.Comment: 18 pages, 4 figure

Positive mass theorems for asymptotically AdS spacetimes with arbitrary cosmological constant

We formulate and prove the Lorentzian version of the positive mass theorems with arbitrary negative cosmological constant for asymptotically AdS spacetimes. This work is the continuation of the second author's recent work on the positive mass theorem on asymptotically hyperbolic 3-manifolds.Comment: 17 pages, final version, to appear in International Journal of Mathematic

Optimal measurements to access classical correlations of two-qubit states

We analyze the optimal measurements accessing classical correlations in arbitrary two-qubit states. Two-qubit states can be transformed into the canonical forms via local unitary operations. For the canonical forms, we investigate the probability distribution of the optimal measurements. The probability distribution of the optimal measurement is found to be centralized in the vicinity of a specific von Neumann measurement, which we call the maximal-correlation-direction measurement (MCDM). We prove that for the states with zero-discord and maximally mixed marginals, the MCDM is the very optimal measurement. Furthermore, we give an upper bound of quantum discord based on the MCDM, and investigate its performance for approximating the quantum discord.Comment: 8 pages, 3 figures, version accepted by Phys. Rev.

Silencing effect of shRNA expression vectors with stem length of 21, 27 or 29 bp

In this study, shRNA vectors having different stem length were constructed and their silencing effect was tested in mouse embryonic fibroblast and in vivo. Interfering RNAs were designed with stems of 21, 27, and 29 bp. The enhanced green fluorescent protein gene was used as target gene. The synthesized single strands were annealed and cloned into psiSTRIKE. Then, the recombinant plasmids were transfected into mouse embryonic fibroblast with lipofection and injected into leg muscle of mouse. The mRNA expression level of the green fluorescent protein gene was checked by real-time quantitative polymerase chain reaction (RT-PCR). The silencing effect of the 29 bp shRNA vector was stronger than that of the 21 and 27 bp in cell, but there was no significant difference among them when injected in muscle. The findings in this study are of interest for selecting the best hairpins for mouse individuals.Key words: Gene silenging, shRNA, enhanced green fluorescent protein, mouse embryonic fibroblast