Cosmological scenarios from multiquintessence

In this work we derive and analyse cosmological scenarios coming from multi-component scalar field models. We consider a direct sum of a sine-Gordon with a Z2 model, and also a combination of those with a BNRT model. Moreover, we work with a modified version of the BNRT model, which breaks the Z2 x Z2 symmetry of the original BNRT potential, coupled with the sine-Gordon and with the standard Z2 models. We show that our approach can be straightforwardly elevated to $N$ fields. All the computations are made analytically and some parameters restriction is put forward in order to get in touch with complete and realistic cosmological scenarios

Caracterização e manejo de pastagens nativas da Amazônia.

bitstream/item/28954/1/Pubvet-Costa882.pd

Translocation of cyanogenic glycosides in rubber tree crown clones resistant to South American leaf blight.

Abstract – The objective of this work was to assess the possible transport of cyanogenic glycosides from leaves of rubber tree crown clones (Hevea spp.) resistant to South American leaf blight to the trunk of the panel clones in which they are grafted. The cyanogenic potential (HCNp) of the crown clones was determined in the trunk bark, at different distances from the cambium, and its gradient was evaluated along the trunk. The correlation between the HCNp of the crown leaves and that of the trunk bark was also evaluated. HCNp determined in leaves showed a wide range variation in the species studied as crown clones, with the lowest values registered in H. nitida clones, and the highest ones in H. rigidifolia. In the trunk bark, the tissue layer nearer the cambium showed higher HCNp values. A positive basipetal gradient was observed along the trunk, i.e., there was an increase in HCNp from the apex toward the base. Although the grafted crowns influence the cyanogenic potential of the trunk bark of panel clones, the absence of correlation between the HCNp of the leaves and trunk bark indicates that the crown is not the main source of the cyanogenic glycosides found in the trunk. Resumo – O objetivo deste trabalho foi avaliar o possível transporte de glicosídeos cianogênicos de folhas de clones de copa de seringueira (Hevea spp.) resistentes ao mal?das?folhas para o tronco dos clones de painel em que estão enxertados. O potencial cianogênico (HCNp) dos clones de copa foi determinado na casca do tronco, a diferentes distâncias do câmbio, e o seu gradiente foi avaliado ao longo do tronco. Avaliou-se, também, a correlação entre o HCNp das folhas das copas e o da casca do tronco. O HCNp determinado nas folhas apresentou ampla faixa de variação nas espécies estudadas como clones de copa, com os menores valores registrados em clones de H. nitida e os maiores em H. rigidifolia. Na casca do tronco, a camada de tecido mais próxima ao câmbio apresentou valores mais elevados de HCNp. Um gradiente basípeto positivo foi observado ao longo do tronco, ou seja, houve aumento do HCNp do ápice para a base. Apesar de os clones de copa influenciarem o potencial cianogênico na casca do tronco dos clones de painel, a ausência de correlação entre o HCNp das folhas e o do tronco indica que a copa não é a fonte principal dos glicosídeos cianogênicos encontrados no tronco