55 research outputs found
Interactions and star formation activity in Wolf-Rayet galaxies
We present the main results of the PhD Thesis carried out by
L\'opez-S\'anchez (2006), in which a detailed morphological, photometrical and
spectroscopical analysis of a sample of 20 Wolf-Rayet (WR) galaxies was
realized. The main aims are the study of the star formation and O and WR
stellar populations in these galaxies and the role that interactions between
low surface companion objects have in the triggering of the bursts. We analyze
the morphology, stellar populations, physical conditions, chemical abundances
and kinematics of the ionized gas, as well as the star-formation activity of
each system.Comment: 16 pages, 15 figure
Hybridizing the electromagnetism-like algorithm with descent search for solving engineering design problems
In this paper, we present a new stochastic hybrid technique for constrained global optimization. It is a combination of the electromagnetism-like (EM) mechanism with a random local search, which is a
derivative-free procedure with high ability of producing a descent direction. Since the original EM algorithm is specifically designed for solving bound constrained problems, the approach herein adopted for handling
the inequality constraints of the problem relies on selective conditions that impose a sufficient reduction either in the constraints violation or in the objective function value, when comparing two points at a time.
The hybrid EM method is tested on a set of benchmark engineering design problems and the numerical results demonstrate the effectiveness of the proposed approach. A comparison with results from other
stochastic methods is also included
Estudos sobre a nutrição mineral do arroz: XV. absorção radicular e foliar do radiofosforo pelas variedades IAC-47 e IAC-435
Foram estudados os efeitos do tempo e da concentração iônica externa na absorção do radiofósforo por raízes destacadas e por plantas inteiras de arroz das variedades IAC-47 (sequeiro) e IAC-435 (irrigado). No intervalo de 30 a 180 min. houve linearidade na absorção. O valor de km para as duas variedades foi o mesmo sendo, porém, menor quando se empregaram raízes destacadas. Não se encontrou diferença significativa na absorção foliar do fosfato monoamônico ou diamônico em ausência ou em presença de uréia.Root uptake either by excised roots or by intact young plants (3-4 week old) showed linearity in the period from 30 to 180 minutes of contact with the solution. Km values were the same for both varieties being, however, slightly lower in the case of excised roots. Foliar uptake was affect neither by source (monoammonium against diammonium phosphate) nor by the presence of urea in the same solution
- …