Familiarity Breeds Tolerance: the Development of Social Stability in Flocking Siskins (Carduelis spin us)

Abstract Behavioural integration associated with the fusion of two flocks is analyzed in captive siskins (Curduelrs sptncts) by quantifying changes in social behaviour with time since joining. In general there was an increase in the incidence of tolerant behaviour, supplanting attacks and hopping withdrawals with time since fusion of the flocks. However, the number of displays and flights showed the opposite, negative, trend. Taking dominance status into account, the greatest change in behaviour with time since joining is an increase in tolerance by dominants of new flock companions. Factorial analysis of correspondences was used to study how different birds changed their behaviour with time since joining a flock. This analysis showed that the introduction of new birds did not disrupt relationships with familiar birds, and that residents are dominant in interactions with the incoming new flock companions. The analysis also demonstrated that relationships within the new flock had stabilized 20 days after the flocks had joined. The characteristics of the socially integrated group of siskins are quite similar to those described by ROI-IWER & EWALD (1981) in their shepherds hypothesis: dominants tolerate thew subordinates feeding in close proximity, offering them a profitable feeding area, but also supplant them to obtain food; both dominants and subordinates benefit from being in a flock. As a consequence, constant changes of membership in flocks is costly not only because birds lose dominance status, but also the advantages of clear dominant and subordinate roles

Membrane protein dynamics: limited lipid control

Correlation of lipid disorder with membrane protein dynamics has been studied with infrared spectroscopy, by combining data characterizing lipid phase, protein structure and, via hydrogen-deuterium (H/D) exchange, protein dynamics. The key element was a new measuring scheme, by which the combined effects of time and temperature on the H/D exchange could be separated. Cyanobacterial and plant thylakoid membranes, mammalian mitochondria membranes, and for comparison, lysozyme were investigated. In dissolved lysozyme, as a function of temperature, H/D exchange involved only reversible movements (the secondary structure did not change considerably); heat-denaturing was a separate event at much higher temperature. Around the low-temperature functioning limit of the biomembranes, lipids affected protein dynamics since changes in fatty acyl chain disorders and H/D exchange exhibited certain correlation. H/D exchange remained low in all membranes over physiological temperatures. Around the high-temperature functioning limit of the membranes, the exchange rates became higher. When temperature was further increased, H/D exchange rates went over a maximum and afterwards decreased (due to full H/D exchange and/or protein denaturing). Maximal H/D exchange rate temperatures correlated neither with the disorder nor with the unsaturation of lipids. In membrane proteins, in contrast to lysozyme, the onsets of sizable H/D exchange rates were the onsets of irreversible denaturing as well. Seemingly, at temperatures where protein self-dynamics allows large-scale H/D exchange, lipid-protein coupling is so weak that proteins prefer aggregating to limit the exposure of their hydrophobic surface regions to water. In all membranes studied, dynamics seemed to be governed by lipids around the low-temperature limit, and by proteins around the high-temperature limit of membrane functionality

Adesão à terapia antiretroviral para HIV/AIDS

A não-adesão à terapêutica antiretroviral altamente eficaz (HAART) é considerada, no plano individual, como um dos mais ameaçadores perigos para a efetividade do tratamento da pessoa com HIV/aids e para a disseminação de vírus-resistência, no plano coletivo. Assim, o objetivo deste estudo foi analisar, mediante revisão de literatura, os fatores de risco para não-adesão à HAART, além de agrupá-los e relacioná-los à pessoa em tratamento, à doença, ao tratamento e ao serviço de saúde e suporte social. A literatura aponta para a necessidade da realização de estudos que avaliem aspectos socioculturais, crenças, qualidade do serviço prestado, relações do cliente com a equipe multiprofissional e outros referentes à raça e aos efeitos colaterais dos anti-retrovirais. Estes estudos visam a favorecer o estabelecimento de estratégias que melhorem a adesão dos clientes à HAART, ao mesmo tempo em e que contribuem para a construção e exercício da cidadania

The crystal engineering of radiation-sensitive diacetylene cocrystals and salts

In this work we develop photoreactive cocrystals/salts of a commercially-important diacetylene, 10,12- pentacosadiynoic acid (PCDA, 1) and report the first X-ray crystal structures of PCDA based systems. The topochemical reactivity of the system is modified depending on the coformer used and correlates with the structural parameters. Crystallisation of 1 with 4,40 -azopyridine (2), 4,40 -bipyridyl (3), and trans-1,2- bis(4-pyridyl)ethylene (4) results in unreactive 2 : 1 cocrystals or a salt in the case of 4,40 -bipiperidine (5). However, salt formation with morpholine (6), diethylamine (7), and n-butylamine (8), results in highly photoreactive salts 12$7 and 1$8 whose reactivity can be explained using topochemical criteria. The salt 1$6 is also highly photoreactive and is compared to a model morpholinium butanoate salt. Resonance Raman spectroscopy reveals structural details of the photopolymer including its conformational disorder in comparison to less photoactive alkali metal salts and the extent of solid state conversion can be monitored by CP-MAS NMR spectroscopy. We also report an unusual catalysis in which amine evaporation from photopolymerised PCDA ammonium salts effectively acts as a catalyst for polymerisation of PCDA itself. The new photoreactive salts exhibit more reactivity but decreased conjugation compared to the commercial lithium salt and are of considerable practical potential in terms of tunable colours and greater range in UV, X-ray, and g-ray dosimetry applications