A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram

An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmology-independent way. Since objects at the same redshift should have the same luminosity distance and since the distance moduli of Type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a GRB at a given redshift by interpolating from the Hubble diagram of SNe Ia. Then we calibrate seven GRB relations without assuming a particular cosmological model and construct a GRB Hubble diagram to constrain cosmological parameters. From the 42 GRBs at $1.4<z\le6.6$, we obtain $\Omega_{\rm M}=0.25_{-0.05}^{+0.04}$, $\Omega_{\Lambda}=0.75_{-0.04}^{+0.05}$ for the flat $\Lambda$CDM model, and for the dark energy model with a constant equation of state $w_0=-1.05_{-0.40}^{+0.27}$, which is consistent with the concordance model in a 1-$\sigma$ confidence region.Comment: 7 pages, 3 figures, 1 table, now matches the editorially revised version; accepted for publication in ApJ (vol 685)

Pyrosequencing based analysis of soil bacterial communities under long-term soil tillage and crop residue management in semiarid environments

Non-Peer Reviewe

Expression of bgt gene in transgenic birch (Betula platyphylla Suk.)

Study on the characteristics of integration and expression is the basis of genetic stability of foreign genes in transgenic trees. To obtain insight into the relationship of transgene copy number and expression level, we screened 22 transgenic birch lines. Southern blot analysis of the transgenic birch plants indicated that the copy number of bgt varies from one to four, of which 18.2% were single copy. Copy number of bgt and gus was different in 68% of transgenic birch plants, indicating that rearrangement or partial deletion appeared in the process of T-DNA integration. Transcriptional expression of bgt gene in transgenic birch plants was analyzed by Northern blot. TGS has been found in two transgenic lines with one and four copies of bgt. The ELISA result showed that the BGT protein expression level in the transgenic birch plants ranged from 0.000 to 0.283% of total soluble protein. In contrary to most studies, this research showed no significant correlation was found between copy number and expression level of bgt gene. Effective resistance of transgenic plants against Lymantria dispar was verified in feeding bioassays with the insects. Bioassays results were mostly consistent with the expression level of BGT insecticidal protein detected by ELISA and Western blot in transgenic birch. The paper showed transgenic birch had the high lethal effect on gypsy moth larvae (L. dispar). The practicality of this work will benefit not only the birch producers, but also the environment worldwide

Chaos control in random Boolean networks by reducing mean damage percolation rate

Chaos control in Random Boolean networks is implemented by freezing part of the network to drive it from chaotic to ordered phase. However, controlled nodes are only viewed as passive blocks to prevent perturbation spread. This paper proposes a new control method in which controlled nodes can exert an active impact on the network. Controlled nodes and frozen values are deliberately selected according to the information of connection and Boolean functions. Simulation results show that the number of nodes needed to achieve control is largely reduced compared to previous method. Theoretical analysis is also given to estimate the least fraction of nodes needed to achieve control.Comment: 10 pages, 2 figure

Emerging materials for spin-charge interconversion

International audienc

Puzzles in BB physics

I discuss some puzzles observed in exclusive $B$ meson decays, concentrating on the large difference between the direct CP asymmetries in the $B^0\to \pi^\mp K^\pm$ and $B^\pm\to \pi^0 K^\pm$ modes, the large $B^0\to\pi^0\pi^0$ branching ratio, and the large deviation of the mixing-induced CP asymmetries in the $b\to sq\bar q$ penguins from those in the $b\to c\bar c s$ trees.Comment: 6 pages, 1 figure, talk presented at the 9th Workshop on High Energy Physics Phenomenology, Bhubaneswar, Orissa, India, Jan. 3-14, 2006; reference adde

Phase Change Observed in Ultrathin Ba0.5Sr0.5TiO3 Films by in-situ Resonant Photoemission Spectroscopy

Epitaxial Ba0.5Sr0.5TiO3 thin films were prepared on Nb-doped SrTiO3 (100)substrates by the pulsed laser deposition technique, and were studied by measuring the Ti 2p - 3d resonant photoemission spectra in the valence-band region as a function of film thickness, both at room temperature and low temperature. Our results demonstrated an abrupt variation in the spectral structures between 2.8 nm (~7 monolayers) and 2.0 nm (~5 monolayers) Ba0.5Sr0.5TiO3 films, suggesting that there exists a critical thickness for phase change in the range of 2.0 nm to 2.8 nm. This may be ascribed mainly to the intrinsic size effects.Comment: 13 pages, 4 figure