Pedro J.N. Silva

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The codon bias in Escherichia coli for all two-fold degenerate amino acids was studied as dependent on the context from the six bases in the nearest surrounding codons. By comparing the results in genes at different expression levels, effects that are due to differences in mutation rates can be distinguished from those that are due to selection. Selective(More)
In this article we derive the full interacting effective actions for supersym-metric D-branes in arbitrary bosonic type II supergravity backgrounds. The actions are presented in terms of component fields up to second order in fermions. As one expects, the actions are built from the supercovariant derivative operator and the κ-symmetry projector. The results(More)
In this letter, using the effective action of non-BPS tachyonic D-branes, we construct the kink D1-brane super D-helix solution and its T-dual the D2-brane supertube. In the limit of zero angular momentum, both types of solutions collapse to zero radius, giving rise respectively to a degenerate string configuration corresponding to a particle travelling(More)
The genome of Pyrococcus furiosus contains the putative mbhABCDEFGHIJKLMN operon for a 14-subunit transmembrane complex associated with a Ni-Fe hydrogenase. Ten ORFs (mbhA-I and mbhM) encode hydrophobic, membrane-spanning subunits. Four ORFs (mbhJKL and mbhN) encode putative soluble proteins. Two of these correspond to the canonical small and large subunit(More)
The consecutive structural genes for the iron-sulfur flavoenzyme sulfide dehydrogenase, sudB and sudA, have been identified in the genome of Pyrococcus furiosus. The translated sequences encode a heterodimeric protein with an alpha-subunit, SudA, of 52598 Da and a beta-subunit, SudB, of 30686 Da. The alpha-subunit carries a FAD, a putative nucleotide(More)
We find the effective action for any D-brane in a general bosonic background of supergravity. The results are explicit in component fields up to second order in the fermions and are obtained in a covariant manner. No interaction terms between fermions and the field f = b + F , characteristic of the bosonic actions, are considered. These are reserved for(More)
In this article we study giant gravitons in the framework of AdS/CFT correspondence. First, we show how to describe these configurations in the CFT side using a matrix model. In this picture, giant gravitons are realized as single excitations high above a Fermi sea, or as deep holes into it. Then, we give a prescription to define quasi-classical states and(More)
We propose replacing the traditional tree depth limit in Genetic Programming by a single limit on the amount of resources available to the whole population, where resources are the tree nodes. The resource-limited technique removes the disadvantages of using depth limits at the individual level, while introducing automatic population resizing, a natural(More)