Bajos niveles de variación isoenzimática en las poblaciones sureñas del arbusto endémico de Corea Sophora koreensis (Fabaceae): implicaciones para su conservación

We investigated allozyme variation of the rare shrub Sophora koreensis in Yanggu County (South Korea), at the southern margin of the species range. To gain insights into ecological processes at the landscape level, we studied two or three populations from four localities (in total, 10 populations) in a range of ca. 6 km. We found low levels of within-population genetic variation (%P = 13.6, A = 1.14, and He = 0.026) and a moderate degree of among-population genetic differentiation (FST = 0.203). The analysis of molecular variance (AMOVA) revealed a substantially higher percentage of variation among populations within localities (17%) than among localities (5%). There was no significant relationship between pairwise genetic divergence and logarithm of pairwise geographic distance (r = 0.032, P = 0.842). These results suggest limited gene flow between populations within localities, while indicating that the optimal strategy for the preservation of the genetic variation of S. koreensis is to conserve as many populations as possible.Se investigó la variación isoenzimática del arbusto raro Sophora koreensis en el condado de Yanggu (Corea del Sur), en el extremo sur de su área de distribución. Para obtener información sobre los procesos ecológicos a nivel del paisaje, se estudiaron dos o tres poblaciones para cada una de las cuatro localidades (en total, 10 poblaciones) en un radio de unos 6 km. Se encontraron bajos niveles de variación genética intra-poblacional (%P = 13,6, A = 1,14 y He = 0,026) y un grado moderado de diferenciación genética entre poblaciones (FST = 0,203). El análisis de la varianza molecular (AMOVA) reveló un porcentaje sustancialmente mayor de variación entre poblaciones dentro cada una de las localidades (17%) que entre localidades (5%). No hubo una relación significativa entre la divergencia genética y el logaritmo de la distancia geográfica entre pares de poblaciones (r = 0,032, P = 0,842). Estos resultados sugieren un flujo genético limitado entre poblaciones dentro de las localidades, además de indicar que la mejor estrategia para la preservación de la diversidad genética de S. koreensis es la conservación del máximo número de poblaciones posible

Improved determination of color-singlet nonrelativistic QCD matrix elements for S-wave charmonium

We present a new computation of S-wave color-singlet nonrelativistic QCD matrix elements for the J/psi and the eta_c. We compute the matrix elements of leading order in the heavy-quark velocity v and the matrix elements of relative order v^2. Our computation is based on the electromagnetic decay rates of the J/psi and the eta_c and on a potential model that employs the Cornell potential. We include relativistic corrections to the electromagnetic decay rates, resumming a class of corrections to all orders in v, and find that they significantly increase the values of the matrix elements of leading order in v. This increase could have important implications for theoretical predictions for a number of quarkonium decay and production processes. The values that we find for the matrix elements of relative order v^2 are somewhat smaller than the values that one obtains from estimates that are based on the velocity-scaling rules of nonrelativistic QCD.Comment: 31 pages, minor corrections, version published in Phys. Rev.

Aldosterone Antagonists in Addition to Renin Angiotensin System Antagonists for Preventing the Progression of CKD: Editorial Summary of a Cochrane Review

No abstract availabl

Detecting the Majorana fermion surface state of 3^3He-B through spin relaxation

The concept of the Majorana fermion has been postulated more than eighty years ago; however, this elusive particle has never been observed in nature. The non-local character of the Majorana fermion can be useful for topological quantum computation. Recently, it has been shown that the 3He-B phase is a time-reversal invariant topological superfluid, with a single component of gapless Majorana fermion state localized on the surface. Such a Majorana surface state contains half the degrees of freedom of the single Dirac surface state recently observed in topological insulators. We show here that the Majorana surface state can be detected through an electron spin relaxation experiment. The Majorana nature of the surface state can be revealed though the striking angular dependence of the relaxation time on the magnetic field direction, $1/T_1 \propto sin^2 \theta$ where $\theta$ is the angle between the magnetic field and the surface normal. The temperature dependence of the spin relaxation rate can reveal the gapless linear dispersion of the Majorana surface state. We propose a spin relaxation experiment setup where we inject an electron inside a nano-sized bubble below the helium liquid surface.Comment: 6 pages, 2 figures; reformatted with reference adde

Spin Dynamics of the Spin-1/2 Kagome Lattice Antiferromagnet ZnCu_3(OH)_6Cl_2

We have performed thermodynamic and neutron scattering measurements on the S=1/2 kagome lattice antiferromagnet Zn Cu_3 (OH)_6 Cl_2. The susceptibility indicates a Curie-Weiss temperature of ~ -300 K; however, no magnetic order is observed down to 50 mK. Inelastic neutron scattering reveals a spectrum of low energy spin excitations with no observable gap down to 0.1 meV. The specific heat at low-T follows a power law with exponent less than or equal to 1. These results suggest that an unusual spin-liquid state with essentially gapless excitations is realized in this kagome lattice system.Comment: 4 pages, 3 figures; v2: Updates to authors list and references; v3: Updated version; v4: Published versio