A General control mechanism of energy flow in the excited state of polyenic biochromophores.

Quantum dynamics in photobiology is a highly controversial subject of modern research. In particular, the role of low-frequency vibrational coherence of biochromophores has been intensely discussed. Coherent control of polyenic chromophores, like carotenoids and retinoids, has been showing that the manipulation of such low frequency coherences may play a crucial role in the evolution of excited population and therefore in the efficiency of photosynthesis. However, no precise control mechanism has been derived. In order to clarify this open question, we combined quantum dynamical modelling with a sensitive experimental technique, namely Pump-Degenerate Four Wave Mixing (Pump-DFWM). In this work we investigate in detail the internal conversion channel of β-carotene, an important polyenic chromophore, under multipulse excitation and focus on the role of the non-adiabatic coupling between excited-state potentials and the internal energy loss. Our control mechanism is based on the interference between wavepackets in the excited state, which leads to a transient evolution of the vibrational population dependent on the relative phase between excitation sub-pulses. Such a transient evolution can affect the branching ratio between competing channels in the excited state. Therefore, our results are able to rationalize pulse shapes found in a whole class of coherent control experiments involving polyenic biochromophores, like in light harvesting complexes and in bacteriorhodopsin

Global public-private partnerships against neglected diseases: building governance structures for effective outcomes

Focusing on the problem of pharmaceutical R&D for drugs and vaccines against neglected diseases in developing countries, this article argues that the effectiveness of global health partnerships potentially lies in their capacity to address the problem of dual market failures: on a first level they may tackle the poverty induced lack of effective demand for health products which impedes the creation of market-financed innovative products. On a second level, they may help overcoming hold-up problems and underinvestment induced by the complexity of neglected diseases R&D. Yet, organizing transactions within a partnership is not a panacea against these problems: a crucial determinant of success is proper ownership structures. They need to respond to (i) the degree to which the respective parties value the partnership outcome, (ii) the relative importance of the investment of the parties, and (iii) the nature of the partnership outcome. The argument developed in the analysis is built on an integrated framework combining insights from incomplete contracting theory and public goods economics. It is supported by a preliminary statistical analysis of 17 GHP

Impacto social e ambiental positivo com retorno financeiro

Com base em experiências pioneiras nas áreas de microfinanças, financiamento comunitário etecnologia verde, em 2007 foi criada a terminologia "investimento de impacto" para definir investimentos com o objetivo de gerar impacto social e/ou ambiental positivo, além de retorno financeiro. Por eacute;m, a construção deste campo demanda tempo, investimento e comprometimento, especialmente de indivíduos e instituições com capacidade financeira para apoiar o desenvolvimento de infraestrutura, empreendedores e intermediários especializados na área. A publicação traz uma boa reflexão sobre o assunto

How to turn trust into a competitive advantage

Business is facing an existential trust crisis, a recent article found. Companies from Boeing to Facebook are losing the public's faith by paying insufficient attention to trust as an important ingredient for answering their stakeholders' needs. But where there is a crisis, there is an opportunity, too. How can business leaders turn trust into a competitive advantage

Tissue composition and haemolymphatic metabolites during gonadal development in Aegla platensis (Crustacea, Decapoda) maintained in experimental culture

This study describes the variation of tissue composition and haemolymphatic metabolites in the anomuran crab A. platensis, which was maintained for 90, 120, 150, and 180 days under laboratory conditions, and relates the data collected to reproductive aspects of this species. Individuals were collected during the winter from Mineiro Creek, in Rio Grande do Sul, Brazil. Some of the individuals were killed when collected and the remaining animals were maintained in a laboratory for different time periods using a commercial diet. Haemolymph, hepatopancreas and gonads were removed at different times of cultivation to determine their biochemical composition using spectrophotometric methods. Hepatosomatic and gonadosomatic indexes were determined. Statistical analysis revealed significant differences between the sexes in all metabolites except in the proteins levels in the haemolymph. We observed an increase of ovigerous females kept under the same culture conditions between 120 and 150 days and we found an increase in the gonadosomatic index and a decrease in the hepatosomatic index in both sexes for the same times. Results showed that the regular food supply caused an increase in the gonadosomatic index in both sexes during all the time periods when compared to the results of animals from the natural environment. We also observed that the females used part of their hepatopancreatic reserves for vitellogenesis and gametogenesis, but the nutrients obtained from the other tissues and the diet were very important for supporting reproduction. Males used the metabolic reserves for growth, gametogenesis, and reproductive behaviors. This study indicates that reproductive events depend on a regular food supply.(Composição tecidual e metabolitos hemolinfaticos durante o desenvolvimento gonadal de Aegla platensis (Crustacea, Decapoda) mantidas em cultura experimental). Este estudo descreve a variação da composição tecidual e metabólitos hemolinfáticos nos caranguejos anomuros A. platensis mantidos por 90, 120, 150 e 180 dias no laboratório, e relaciona esses dados com os aspectos reprodutivos. Os animais foram coletados no arroio do Mineiro, Rio Grande do Sul, Brasil durante o inverno. Parte dos animais foi sacrificado em campo, e os restantes animais foram mantidos em laboratório por diferentes períodos com uma dieta comercial. A hemolinfa, o hepatopâncreas e as gônadas foram retiradas em diferentes épocas de cultivo para determinar a sua composição bioquímica por métodos espectrofotométricos. Os índices hepatossomático e gonadossomático foram determinados. A análise estatística revelou diferenças significativas entre os sexos em todos os seus metabolitos, exceto nos níveis de proteínas na hemolinfa. Observamos um aumento de fêmeas ovígeras mantidas sob as condições de cultivo entre 120 e 150 dias e encontramos um aumento do índice gonadossomático e uma diminuição do índice hepatossomático em ambos os sexos no mesmo periodo. Os resultados mostraram que o fornecimento regular de alimentos provocou um aumento no índice gonadossomático em ambos os sexos durante todo o período, quando comparado com os resultados dos animais do ambiente natural. Também foi observado que as fêmeas utilizadas parte das suas reservas do hepatopâncreas para a vitelogênese e a gametogênese, mas os nutrientes obtidos a partir de outros tecidos e da dieta foram muito importantes para apoiar a reprodução. Os machos utilizaram a reserva metabólica para o crescimento, gametogênese e comportamentos reprodutivos. Este estudo indica que os eventos reprodutivos dependem de um fornecimento regular de alimentos

Mapping the ultrafast vibrational dynamics of all- trans and 13- cis retinal isomerization in Anabaena Sensory Rhodopsin

International audienceDiscrepancies in the isomerization dynamics and quantum yields of the trans and cis retinal protonated Schiff base is a well-known issue in the context of retinal photochemistry. Anabaena Sensory Rhodopsin (ASR) is a microbial retinal protein that comprises a retinal chromophore in two ground state (GS) conformations: all-trans, 15-anti (AT) and 13-cis, 15-syn (13C). In this work, we apply impulsive vibrational spectroscopic techniques (DFWM, pump-DFWM and pump-IVS) to ASR to shed more light on how the structural changes take place in the excited state within the same protein environment. Our findings point to distinct features in the ground state structural conformations as well as to drastically different evolutions in the excited state manifold. The ground state vibrational spectra show stronger Raman activity of the C14-H out-of-plane wag (at about 805 cm-1) for 13C than for AT isomer, which hints at a pre-distortion of the 13C in the ground state. Evolution of the Raman frequency after interaction with actinic pulse shows a blue shift for the C=C stretching and CH3 rocking mode for both isomers. For AT, however, the blue shift is not instantaneous as observed for the 13C isomer, rather it takes more than 200 fs to reach the maximum frequency shift. This frequency blue shift is rationalized by a decrease of the effective conjugation length during the isomerization reaction, which further confirms a slower formation of the twisted state for the AT isomer and corroborates the presence of a barrier in the excited state trajectory previously predicted by quantum chemical calculations

Coherent control of the efficiency of an artificial light-harvesting complex

Coherent control over the branching ratio between competing pathways for energy flow is realised for artificial light-harvesting complex. Direct insights to the mechanism featuring quantum interference of a low-frequency mode are presented.</p