Latitudinal clines of allelic frequencies in Mediterranean populations of Ceratitis capitata (Wiedemann)

International audienc

Bragg Polaritons: Strong Coupling and Amplification in an Unfolded Microcavity

Periodic incorporation of quantum wells inside a one--dimensional Bragg structure is shown to enhance coherent coupling of excitons to the electromagnetic Bloch waves. We demonstrate strong coupling of quantum well excitons to photonic crystal Bragg modes at the edge of the photonic bandgap, which gives rise to mixed Bragg polariton eigenstates. The resulting Bragg polariton branches are in good agreement with the theory and allow demonstration of Bragg polariton parametric amplification.Comment: 4 pages, 4 figure

Octamer binding proteins confer transcriptional activity in early mouse embryogenesis.

Oct4 and Oct5 are two mouse maternally expressed proteins binding to the octamer motif. Both are found in unfertilized oocytes and embryonic stem cells, whereas Oct4 is also found in primordial germ cells. In this study, the activity of the octamer motif was analysed in two embryonic stem cell lines containing Oct4 and Oct5, the teratocarcinoma-derived cell line F9 and the blastocyst-derived cell line D3. It is known that oligomerization of the octamer motif creates a powerful B-cell specific enhancer. As shown here, this oligomerized transcriptional element is also a very strong enhancer in F9 and D3 embryonic stem cells. After differentiation of the stem cells, both enhancer activity and the amount of the octamer binding proteins decrease. An intact octamer stimulates heterologous promoters in embryonic stem cells, whereas mutations in the octamer motif abolish transcriptional stimulation and binding of the octamer factors. The use of transgenic embryos demonstrates transcriptional activation in the inner cell mass but not in the trophoblast of blastocysts. The results indicate that Oct4 and Oct5 are active early in mouse development

A family of octamer-specific proteins present during mouse embryogenesis: Evidence for germline-specific expression of an Oct factor.

We have analysed various adult organs and different developmental stages of mouse embryos for the presence of octamer-binding proteins. A variety of new octamer-binding proteins were identified in addition to the previously described Oct1 and Oct2. Oct1 is ubiquitously present in murine tissues, in agreement with cell culture data. Although Oct2 has been described as a B-cell-specific protein, similar complexes were also found with extracts from brain, kidney, embryo and sperm. In embryo and brain at least two other proteins, Oct3 and Oct7, are present. A new microextraction procedure allowed the detection of two maternally expressed octamer-binding proteins, Oct4 and Oct5. Both proteins are present in unfertilized oocytes and embryonic stem cells, the latter containing an additional protein, Oct6. Whereas Oct4 was not found in sperm or testis, it is expressed in male and female primordial germ cells. Therefore Oct4 expression is specific for the female germline at later stages of germ cell development. Our results indicate that a family of octamer-binding proteins is present during mouse development and is differentially expressed during early embryogenesis. Protease clipping experiments of Oct4 and Oct1 suggest that both proteins contain similar DNA-binding domains

Quantifying preferential trading in the e-MID interbank market

Interbank markets allow credit institutions to exchange capital for purposes of liquidity management. These markets are among the most liquid markets in the financial system. However, liquidity of interbank markets dropped during the 2007-2008 financial crisis, and such a lack of liquidity influenced the entire economic system. In this paper, we analyze transaction data from the e-MID market which is the only electronic interbank market in the Euro Area and US, over a period of eleven years (1999-2009). We adapt a method developed to detect statistically validated links in a network, in order to reveal preferential trading in a directed network. Preferential trading between banks is detected by comparing empirically observed trading relationships with a null hypothesis that assumes random trading among banks doing a heterogeneous number of transactions. Preferential trading patterns are revealed at time windows of 3-maintenance periods. We show that preferential trading is observed throughout the whole period of analysis and that the number of preferential trading links does not show any significant trend in time, in spite of a decreasing trend in the number of pairs of banks making transactions. We observe that preferential trading connections typically involve large trading volumes. During the crisis, we also observe that transactions occurring between banks with a preferential connection occur at larger interest rates than the complement set - an effect that is not observed before the crisis

The prisoners dilemma on a stochastic non-growth network evolution model

We investigate the evolution of cooperation on a non - growth network model with death/birth dynamics. Nodes reproduce under selection for higher payoffs in a prisoners dilemma game played between network neighbours. The mean field characteristics of the model are explored and an attempt is made to understand the size dependent behaviour of the model in terms of fluctuations in the strategy densities. We also briefly comment on the role of strategy mutation in regulating the strategy densties.Comment: 8 pages, 8 figure