Combining exclusive semi-leptonic and hadronic B decays to measure |V_ub|

The Cabibbo-Kobayashi-Maskawa matrix element |V_ub| can be extracted from the rate for the semi-leptonic decay B -> pi + l + antineutrino_l, with little theoretical uncertainty, provided the hadronic form factor for the B -> pi transition can be measured from some other B decay. In here, we suggest using the decay B -> pi J\psi. This is a color suppressed decay, and it cannot be properly described within the usual factorization approximation; we use instead a simple and very general phenomenological model for the b d J\psi vertex. In order to relate the hadronic form factors in the B -> pi J\psi and B -> pi + l + antineutrino_l decays, we use form factor relations that hold for heavy-to-light transitions at large recoil.Comment: Latex, 7 pages, no figure

A multi-metal risk assessment strategy for natural freshwater ecosystems based on the additive inhibitory free metal ion concentration index

Scientifically sound risk assessment strategies and derivations of environmental quality standards for metals present in freshwater environments are currently hampered by insufficient chronic toxicity data collected from natural ecosystems, as well as inadequate information on metal speciation. Thus, the aim of the present study was to evaluate the impact of freshwater containing multiple metals (Cd, Cr, Cu, Ni, Pb and Zn) on the chronic toxicity (72h) to the alga Pseudokirchneriella subcapitata and compare the observed toxicity results to the total and free metal concentration of the samples. Based on the information obtained herein, an additive inhibitory free multi-metal ion concentration index, calculated as the sum of the equivalent toxicities to the free metal ion concentration of each sample, was developed. The proposed index was well correlated to the observed chronic toxicity results, indicating that the concentration addition, when expressed as the free-ion activity, can be considered a reliable indicator for the evaluation of ecological risk assessments for natural waters containing multiple metals.This work was performed in the framework of the financing with references LAQV (UID/QUI/50006/2013 - POCI/01/0145/FEDER/007265) and UID/BIO/04469/2013 - POCI-01-0145-FEDER-006684 with financial support from FCT/MEC through national funds and co-financed by FEDER, under the Partnership Agreement PT2020 and Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462)

Interferência da taxa de recirculação na remoção de carbono e nitrogênio pelo processo Modified Ludzak-Ettinger (MLE).

Projeto: 02.07.06.007

Cohomological characterisation of Steiner bundles

A vector bundle E on a smooth irreducible algebraic variety X is called a Steiner bundle of type (F0, F1) if it is defined by an exact sequence of the form where s, t ≥ 1 and (F0, F1) is a strongly exceptional pair of vector bundles on X such that is generated by global sections. Let X be a smooth irreducible projective variety of dimension n with an n-block collection , of locally free sheaves on X which generate D b(X-mod). We give a cohomological characterisation of Steiner bundles of type on X, where 0 ≤ a < b ≤ n and 1 ≤ i 0 ≤ ?a, 1 ≤ j0 ≤ ?b