Higher order peak algebras

Using the theory of noncommutative symmetric functions, we introduce the higher order peak algebras, a sequence of graded Hopf algebras which contain the descent algebra and the usual peak algebra as initial cases (N = 1 and N = 2). We compute their Hilbert series, introduce and study several combinatorial bases, and establish various algebraic identities related to the multisection of formal power series with noncommutative coefficients.Comment: 20 pages, AMS LaTe

Noncommutative symmetric functions V : A degenerate version of Uq(GlN )

["Special issue for the memory of M. Schutzenberger", J.E. Pin Ed.]Nous montrons que la théorie des fonctions symétriques non commutatives permet de rendre compte des représentations d'une version dégénérée de la version quantique de l'algèbre enveloppante de GlN

Molecular evolution of the crustacean hyperglycemic hormone family in ecdysozoans

<p>Abstract</p> <p>Background</p> <p>Crustacean Hyperglycemic Hormone (CHH) family peptides are neurohormones known to regulate several important functions in decapod crustaceans such as ionic and energetic metabolism, molting and reproduction. The structural conservation of these peptides, together with the variety of functions they display, led us to investigate their evolutionary history. CHH family peptides exist in insects (Ion Transport Peptides) and may be present in all ecdysozoans as well. In order to extend the evolutionary study to the entire family, CHH family peptides were thus searched in taxa outside decapods, where they have been, to date, poorly investigated.</p> <p>Results</p> <p>CHH family peptides were characterized by molecular cloning in a branchiopod crustacean, <it>Daphnia magna</it>, and in a collembolan, <it>Folsomia candida</it>. Genes encoding such peptides were also rebuilt <it>in silico </it>from genomic sequences of another branchiopod, a chelicerate and two nematodes. These sequences were included in updated datasets to build phylogenies of the CHH family in pancrustaceans. These phylogenies suggest that peptides found in Branchiopoda and Collembola are more closely related to insect ITPs than to crustacean CHHs. Datasets were also used to support a phylogenetic hypothesis about pancrustacean relationships, which, in addition to gene structures, allowed us to propose two evolutionary scenarios of this multigenic family in ecdysozoans.</p> <p>Conclusions</p> <p>Evolutionary scenarios suggest that CHH family genes of ecdysozoans originate from an ancestral two-exon gene, and genes of arthropods from a three-exon one. In malacostracans, the evolution of the CHH family has involved several duplication, insertion or deletion events, leading to neuropeptides with a wide variety of functions, as observed in decapods. This family could thus constitute a promising model to investigate the links between gene duplications and functional divergence.</p

Nanostructured materials with highly dispersed Au–Ce0.5Zr0.5O2 nanodomains: A route to temperature stable Au catalysts?

Our strategy to inhibit Au(0) growth with temperature involves the preparation of ultrafine Au clusters that are highly dispersed and strongly interacting with a thermally stable high-surface-area substrate. Temperature-stable Au-cluster-based catalysts were successfully prepared through the controlled synthesis of 3.5 nm Ce0.5Zr0.5O2 colloidal building blocks containing tailored strongly bound Au-cluster precursors. With the objective of stabilizing these Au clusters with temperature, grain growth of Ce0.5Zr0.5O2 nanodomains was inhibited by their dispersion through Al2O3 nanodomains. High surface area Au–Ce0.5Zr0.5O2–Al2O3 nanostructured composites were thus designed highlighting the drastic effect of Au cluster dispersion on Au(0) cluster growth. High thermal stability of our Au(0)-cluster-based catalysts was shown with the surprising catalytic activity for CO conversion observed on our nanostructured materials heated to temperatures as high as 800 C for 6 h

Deterministic End-to-End Delay Guarantees in a Heterogeneous Route Interference Environment

Some of the known results for delivering deterministic bounds on end-to-end queuing delay in networks with constant packet sizes and constant link rates rely on the concept of Route Interference. Namely, it is required to know the number of flows joining on any output link in the whole network. In this paper we extend the existing results for the more generic cases of connection-oriented networks consisting of links with different capacities, carrying different traffic classes and packets of different sizes

Provably Total Functions of Arithmetic with Basic Terms

A new characterization of provably recursive functions of first-order arithmetic is described. Its main feature is using only terms consisting of 0, the successor S and variables in the quantifier rules, namely, universal elimination and existential introduction.Comment: In Proceedings DICE 2011, arXiv:1201.034