25 research outputs found
Bioevaluation of the nutritional status of rice (Oriza sativa L. cv. IAC-165) and bean (Phaseolus vulgaris L. cv. carioca) plants using 15N and 32P
Arroz e feijão foram cultivados em soluções nutritivas em presença de três níveis de N, P e K. O método da bioavaliação do estado nutricional em que raízes destacadas absorvem elementos marcados, no caso presente 15N e 32P, foi comparado com o de diagnose foliar. Foram tiradas duas conclusões principais: 1) os bioensaios mostraram ser um procedimento rápido e útil para o diagnóstico do estado nutricional das duas espécies, visto haver correlação significativa negativa entre absorção e produção de matéria seca; 2) a absorção de dois isótopos pelas raízes da planta previamente submetida a níveis diferentes de N e de P na solução foi inversamente proporcional aos teores foliares desses elementos.Rice and bean plants were grown in nutrient solution in the presence of three levels of N, P and K. The method of the bioevaluation of the nutricional status, in which excised roots are allowed to take up tagged elements, in this case 15N and 32P, was compared with foliar analysis. Two main conclusions were drawn: 1) the bioevaluation proved to be an useful and rapid procedure for the diagnosis of the nutricional status of both species, since there was a significant negative correlation between absorption of N and P and dry matter yield; 2) the uptake of the tagged ions with either element by the roots of plants grown under deficient levels of N and P in the nutrient solution was inversely proportional to the leaf concentration of both nutrients
Semi-empirical catalog of early-type galaxy-halo systems: dark matter density profiles, halo contraction and dark matter annihilation strength
With SDSS galaxy data and halo data from up-to-date N-body simulations we
construct a semi-empirical catalog (SEC) of early-type systems by making a
self-consistent bivariate statistical match of stellar mass (M_star) and
velocity dispersion (sigma) with halo virial mass (M_vir). We then assign
stellar mass profile and velocity dispersion profile parameters to each system
in the SEC using their observed correlations with M_star and sigma.
Simultaneously, we solve for dark matter density profile of each halo using the
spherical Jeans equation. The resulting dark matter density profiles deviate in
general from the dissipationless profile of NFW or Einasto and their mean inner
density slope and concentration vary systematically with M_vir. Statistical
tests of the distribution of profiles at fixed M_vir rule out the null
hypothesis that it follows the distribution predicted by N-body simulations for
M_vir ~< 10^{13.5-14.5} M_solar. These dark matter profiles imply that dark
matter density is, on average, enhanced significantly in the inner region of
halos with M_vir ~< 10^{13.5-14.5} M_solar supporting halo contraction. The
main characteristics of halo contraction are: (1) the mean dark matter density
within the effective radius has increased by a factor varying systematically up
to ~ 3-4 at M_vir = 10^{12} M_solar, and (2) the inner density slope has a mean
of ~ 1.3 with rho(r) ~ r^{-alpha} and a halo-to-halo rms scatter of
rms(alpha) ~ 0.4-0.5 for 10^{12} M_solar ~< M_vir ~< 10^{13-14} M_solar steeper
than the NFW profile (alpha=1). Based on our results we predict that halos of
nearby elliptical and lenticular galaxies can, in principle, be promising
targets for gamma-ray emission from dark matter annihilation.Comment: 43 pages, 20 figures, JCAP, revised and accepted versio