New family of potentials with analytical twiston-like solutions

In this letter we present a new approach to find analytical twiston models. The effective two-field model was constructed by a non-trivial combination of two one field systems. In such an approach we successfully build analytical models which are satisfied by a combination of two defect-like solutions, where one is responsible to twist the molecular chain by $180^{\,0}$, while the other implies in a longitudinal movement. Such a longitudinal movement can be fitted to have the size of the distance between adjacent molecular groups. The procedure works nicely and can be used to describe the dynamics of several other molecular chains.Comment: 7 pages, 3 figure

Diel vertical migration of the prawn larvae of Macrobrachium amazonicum (HELLER, 1862) in a Central Amazonian floodplain lake, Careiro Island, Brazil

Prawn larvae of Macrobrachium amazonicum have been collected during six diel cycles in the epilimnion (surface and 2 m) from three different habitats of the Lago do Rei, Careiro Island. The larval distribution showed a significant increase in density at 22 hours regardless of season or habitat, which suggests a diel vertical migration pattern. The thermal stratification of the lake (mean differential of 0.5 °C between the surface and 2 m and 0.6 °C between 2 m and 4 m) suggests that this phenomena could be only partly related to a metabolic efficiency resulting from prawns residing at cooler depths during the day. In shallow tropical waters, predation by visually dependent planktivores can be a more important factor in the adaptative significance of the diel distribution of the macrozooplankton than a low thermal stratification. The diurnal feeding activity found in the predominant planktivores fish species of the Careiro lake reinforces this hypothesis

Immunological impact of induced acute physical activity reduction

[resumo][abstract

Compactness in the Thermal Evolution of Twin Stars

In this work, we study for the first time the thermal evolution of twin star pairs, i.e., stars that present the same mass but different radius and compactness. We collect available equations of state that give origin to a second branch of stable compact stars with quarks in their core. For each equation of state, we investigate the particle composition inside stars and how differently each twin evolves over time, which depends on the central density/pressure and consequent crossing of the threshold for the Urca cooling process. We find that, although the general stellar thermal evolution depends on mass and particle composition, withing one equation of state, only twin pairs that differ considerably on compactness can be clearly distinguished by how they cool down

Fishery potential of Macrobrachium amazonicum in Central Amazonia (Careiro Island): abundance and size variation

Abundance and body size variations of the prawn Macrobrachium amazonicum (HELLER, 1862) have been studied in a Central Amazonian floodplain lake, on Careiro Island. The highest number of captures and smallest sizes have been observed beneath floating macrophyte meadows. This suggests that these meadows serve a nursery habitats. The densities registered in the Amazon river were three times lower than in the lake. Maximum densities were recorded during low-water periods, while minimum densities were found during high water periods. These results point to a relationship between current force and catchability. In the floodplain lake, prawn abundance seems to be related to macrophyte expansion during the periods of rising water; the lowest captures were registered at high water, which is probably due to the spatial dispersion as the water volume increases. River prawn populations are characterized by larger sizes than the ones in the lake. They show a well-marked pattern of seasonal variation in size, with larger sizes found during periods of rising water and smaller sizes predominating during high-water periods. On the contrary, lagoonal prawns show maximum sizes during high-water, and smallest sizes during low-water periods. Despite its good fishing potential (up to 200 g/trap), the native prawn is not exploited in the Amazonas, but imported from the State of Pará. Artesanal prawn fishing in floodplain lakes, or extensive culture in ponds for carnivorous fish or human consumption, can be a commercially lucrative activity for sustainable regional economic development

Melhoria dos canais de comunicação da cadeia de suprimentos no setor de patrimônio e materiais (SPM) da Embrapa Florestas.

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