Consistent alleviation of abiotic stress with silicon addition: a meta-analysis

1. Hundreds of single species studies have demonstrated the facility of silicon (Si) to alleviate diverse abiotic stresses in plants. Understanding of the mechanisms of Si-mediated stress alleviation is progressing, and several reviews have brought information together. A quantitative assessment of the alleviative capacity of Si, however, which could elucidate plant Si function more broadly, was lacking. 2. We combined the results of 145 experiments, predominantly on agricultural species, in a meta-analysis to statistically assess the responses of stressed plants to Si supply across multiple plant families and abiotic stresses. We interrogated our database to determine whether stressed plants increased in dry mass and net assimilation rate, oxidative stress markers were reduced, antioxidant responses were increased and whether element uptake showed consistent changes when supplied with Si. 3. We demonstrated that across plant families and stress types, Si increases dry weight, assimilation rate and chlorophyll biosynthesis and alleviates oxidative damage in stressed plants. In general, results indicated that plant family (as a proxy for accumulator type) and stress type had significant explanatory power for variation in responses. The consistent reduction in oxidative damage was not mirrored by consistent increases in antioxidant production, indicative of the several different stress alleviation mechanisms in which Si is involved. Silicon addition increased K in shoots, decreased As and Cd in roots and Na and Cd in shoots. Silicon addition did not affect Al, Ca or Mn concentration in shoots and roots of stressed plants. Plants had significantly lower concentrations of Si accumulated in shoots but not in roots when stressed. 4. Meta-analyses showed consistent alleviation by Si of oxidative damage caused by a range of abiotic stresses across diverse species. Our findings indicate that Si is likely to be a useful fertilizer for many crops facing a spectrum of abiotic stresses. Similarities in responses across families provide strong support for a role of Si in the alleviation of abiotic stress in natural systems, where it has barely been explored. We suggest this role may become more important under a changing climate and more experiments using non-agricultural species are now needed

Anisotropic transport in the two-dimensional electron gas in the presence of spin-orbit coupling

In a two-dimensional electron gas as realized by a semiconductor quantum well, the presence of spin-orbit coupling of both the Rashba and Dresselhaus type leads to anisotropic dispersion relations and Fermi contours. We study the effect of this anisotropy on the electrical conductivity in the presence of fixed impurity scatterers. The conductivity also shows in general an anisotropy which can be tuned by varying the Rashba coefficient. This effect provides a method of detecting and investigating spin-orbit coupling by measuring spin-unpolarized electrical currents in the diffusive regime. Our approach is based on an exact solution of the two-dimensional Boltzmann equation and provides also a natural framework for investigating other transport effects including the anomalous Hall effect.Comment: 10 pages, 1 figure included. Discussion of experimental impact enlarged; error in calculation of conductivity contribution corrected (cf. Eq. (A14)), no changes in qualitative results and physical consequence

Sub-barrier capture with quantum diffusion approach: actinide-based reactions

With the quantum diffusion approach the behavior of capture cross sections and mean-square angular momenta of captured systems are revealed in the reactions with deformed nuclei at subbarrier energies. The calculated results are in a good agreement with existing experimental data. With decreasing bombarding energy under the barrier the external turning point of the nucleusnucleus potential leaves the region of short-range nuclear interaction and action of friction. Because of this change of the regime of interaction, an unexpected enhancement of the capture cross section is expected at bombarding energies far below the Coulomb barrier. This effect is shown its worth in the dependence of mean-square angular momentum of captured system on the bombarding energy. From the comparison of calculated and experimental capture cross sections, the importance of quasifission near the entrance channel is shown for the actinide-based reactions leading to superheavy nuclei.Comment: 11 pages, 16 figures, Regular Articl

Search for Resonant B±→K±h→K±γγB^{\pm}\to K^{\pm} h \to K^{\pm} \gamma \gamma Decays at Belle

We report measurements and searches for resonant $B^{\pm} \to K^{\pm} h \to K^{\pm} \gamma \gamma$ decays where $h$ is a $\eta,\eta^{\prime},\eta_{c},\eta_{c}(2S),\chi_{c0},\chi_{c2},J/\psi$ meson or the X(3872) particle.Comment: accepted by Physics Letters

Search for Lepton-Flavor-Violating tau Decays into a Lepton and an f0(980) Meson

We search for lepton-flavor-violating tau decays into a lepton (electron or muon) and an f0(980) meson using 671 fb-1 of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. No events are observed and we set the following 90% C.L. upper limits on the branching fraction products: B(tau- -> e-f0(980))*B(f0(980)->pi+pi-) mu-f0(980))*B(f0(980) -> pi+pi-)<3.4x10^-8. This is the first search performed for these modes.Comment: 10 pages, 4 figures, submitted to Phys. Lett.

Observation of the ϕ(1680)\phi(1680) and the Y(2175) in e+e−→ϕπ+π−e^+ e^- \to \phi\pi^+\pi^-

The cross sections for $e^+ e^- \to \phi\pi^+\pi^-$ and e^+ e^- \to \phi \fzero are measured from threshold to $\sqrt{s}=3.0$ $\hbox{GeV}$ using initial state radiation. The analysis is based on a data sample of 673 fb$^{-1}$ collected on and below the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. First measurements are reported for the resonance parameters of the $\phi(1680)$ in the $\phi\pi^+\pi^-$ mode: $m=(1689\pm 7\pm 10)$ MeV/$c^2$ and $\Gamma=(211\pm 14\pm 19)$ MeV/$c^2$. A structure at $\sqrt{s}=2.1 \hbox{GeV}/c^2$, corresponding to the so called Y(2175), is observed; its mass and width are determined to be $2079\pm13^{+79}_{-28}$ MeV/$c^2$ and $192\pm23^{+25}_{-61} \hbox{MeV}/c^2$, respectively.Comment: 11 pages, 6 figures. Add one plot. Accepted by Phys.Rev.D(RC

Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S

Using 462/fb of e+e- annihilation data recorded by the Belle detector, we report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be (3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+ -> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table

Improved measurement of CP-violating parameters in rho+rho- decays

We present a measurement of the CP-violating asymmetry in rho+rho- decays using 535 million BBbar pairs collected with the Belle detector at the KEKB e+e- collider. We measure CP-violating coefficients A = 0.16 +- 0.21(stat) +- 0.07 (syst) and S = 0.19 +- 0.30(stat) +- 0.07 (syst}. These values are used to determine the unitarity triangle angle phi_2 using an isospin analysis; the solution consistent with Standard Model lies in the range 53 < phi_2 < 114 deg. at 90 C.L.Comment: 6 pages, 4 figures, presented at JPS/DPF 2006 (Added KEK, BELLE preprint numbers, submitted to PRD(RC)

Menus for Feeding Black Holes

Black holes are the ultimate prisons of the Universe, regions of spacetime where the enormous gravity prohibits matter or even light to escape to infinity. Yet, matter falling toward the black holes may shine spectacularly, generating the strongest source of radiation. These sources provide us with astrophysical laboratories of extreme physical conditions that cannot be realized on Earth. This chapter offers a review of the basic menus for feeding matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher