RLE Edit Distance in Near Optimal Time

We show that the edit distance between two run-length encoded strings of compressed lengths m and n respectively, can be computed in O(mn log(mn)) time. This improves the previous record by a factor of O(n/log(mn)). The running time of our algorithm is within subpolynomial factors of being optimal, subject to the standard SETH-hardness assumption. This effectively closes a line of algorithmic research first started in 1993

Broadcasting on Large Scale Heterogeneous Platforms with connectivity artifacts under the Bounded Multi-Port Model

International audienceWe consider the classical problem of broadcasting a large message at an optimal rate in a large scale distributed network. The main novelty of our approach is that we consider that the set of participating nodes can be split into two parts: "green" nodes that stay in the open-Internet and "red" nodes that lie behind firewalls or NATs. Two red nodes cannot communicate directly, but rather need to use a green node as a gateway for transmitting a message. In this context, we are interested in both maximizing the throughput (\ie the rate at which nodes receive the message) and minimizing the degree at the participating nodes, \ie the number of TCP connections they must handle simultaneously. We both consider cyclic and acyclic solutions for the flow graph. In the cyclic case, our main contributions are a closed form formula for the optimal cyclic throughput and the proof that the optimal solution may require arbitrarily large degrees. In the acyclic case, we prove that it is possible to achieve the optimal throughput with low degree. Then, we prove a worst case ratio between the optimal acyclic and cyclic throughput and show through simulations that this ratio is on average very close to 1, which makes acyclic solutions efficient both in terms of the throughput and the number of connections

What are the evolutionary constraints on larval growth in a trophically transmitted parasite?

For organisms with a complex life cycle, a large larval size is generally beneficial, but it may come at the expense of prolonged development. Individuals that grow fast may avoid this tradeoff and switch habitats at both a larger size and younger age. A fast growth rate itself can be costly, however, as it requires greater resource intake. For parasites, fast larval growth is assumed to increase the likelihood of host death before transmission to the next host occurs. Using the tapeworm Schistocephalus solidus in its copepod first intermediate host, I investigated potential constraints in the parasite’s larval life history. Fast-growing parasites developed infectivity earlier, indicating there is no functional tradeoff between size and developmental time. There was significant growth variation among full-sib worm families, but fast-growing sibships were not characterized by lower host survival or more predation-risky host behavior. Parental investment also had little effect on larval growth rates. The commonly assumed constraints on larval growth and development were not observed in this system, so it remains unclear what prevents worms from exploiting their intermediate hosts more aggressively

Broadcasting on Large Scale Heterogeneous Platforms with Connectivity Artifacts under the Bounded Multi-port Model

International audienceWe consider the classical problem of broadcasting a large message at an optimal rate in a large scale distributed network. The main novelty of our approach is that we consider that the set of participating nodes can be split into two parts: "green" nodes that stay in the open-Internet and "red" nodes that lie behind firewalls or NATs. Two red nodes cannot communicate directly, but rather need to use a green node as a gateway for transmitting a message. In this context, we are interested in both maximizing the throughput (\ie the rate at which nodes receive the message) and minimizing the degree at the participating nodes, \ie the number of TCP connections they must handle simultaneously. We both consider cyclic and acyclic solutions for the flow graph. In the cyclic case, our main contributions are a closed form formula for the optimal cyclic throughput and the proof that the optimal solution may require arbitrarily large degrees. In the acyclic case, we prove that it is possible to achieve the optimal throughput with low degree. Then, we prove a worst case ratio between the optimal acyclic and cyclic throughput and show through simulations that this ratio is on average very close to 1, which makes acyclic solutions efficient both in terms of the throughput and the number of connections

Substituent and Solvent effects on the Nature of the Transitions of Pyrenol and Pyranine. Identification of an Intermediate in the Excited-State proton-Transfer Reaction

A comparative study of pyrenol and its trisulfonated derivative, pyranine, is undertaken to provide new clues for the understanding of the excited-state proton-transfer reaction (ESPT) of hydroxyarenes (ArOH*). A particular goal is to elucidate the nature of a transient intermediate involved in a three step mechanism of ESPT, as recently revealed in a dynamical study of excited pyranine in water. The present focus is on the reactant side, before the proton transfer occurs, and particular attention is given to the analysis of the nature of the electronic transitions and to the solute-solvent interactions in the ground and excited states of the ArOHs. Using both quantum chemical calculations and solvatochromism analyses, both (a) the role of electron-withdrawing substituents and H-bond interaction with the solvent in stabilizing the two lowest excited states, 1Lb and 1La, and (b) their relevance to the inversion of these two states are studied. The results allow the identification of the intermediate species in the three step mechanism of the ESPT of excited pyranine in water as a 1La state acid form, with appreciable charge-transfer character, as distinct from the 1Lb acid form reached in absorption. The results, which differ from more standard pictures of ESPT, are discussed within the perspective of a three valence bond form model for the ESPT process