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We develop a novel Hybrid High-Order method for the incompressible Navier–Stokes problem robust for large irrotational body forces. The key ingredients of the method are discrete versions of the body force and convective contributions in the momentum equation formulated in terms of a globally divergence-free velocity reconstruction. Two key properties are mimicked at the discrete level, namely the invariance of the velocity with respect to irrotational body forces and the non-dissipativity of the convective term. A full convergence analysis is carried out, showing optimal orders of convergence under a smallness condition involving only the solenoidal part of the body force. The performance of the method is illustrated by a complete panel of numerical tests, including comparisons that highlight the benefits with respect to more standard formulations. [ABSTRACT FROM AUTHOR]

A series of thermoresponsive copolymers based on chitosan- g -poly( N -vinylcaprolactam) were synthesized by amidation reaction using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride as coupling reagent. The effect of molecular architecture on the thermoresponsive properties of the graft copolymers solutions was studied by varying the chain length of the grafted poly( N -vinylcaprolactam), PVCL, (in the range from 4 to 26 kDa) and the spacing between grafted chains onto the chitosan backbone. The most interesting characteristic of these copolymers is their solubility in water at temperatures below their lower critical solution temperature (LCST). These solutions presented a LCST between 36 and 44 °C, which decreases with the spacing and length of grafted PVCL chains onto the chitosan backbone, in contrast with the limited decrease of the LCST of PVCL above a critical M ¯ n value around 18 kDa. This behavior offers tangible possibilities for the preparation and application of sensitive bioactive formulations and “smart” drug delivery systems. [ABSTRACT FROM AUTHOR]

A chronological database of 398 dates (247 14 C dates, 148 thermoluminescence dates, and 3 obsidian hydration dates), covering the early peopling period up to the present, is presented for Southern Chile. This information is used to assess both the paleodemography, understood as human population dynamics in the past; and the “archaeo-demography”, understood as the research dynamics of archaeologists in the present, of that region. From the early peopling up to the Late Archaic, information is geographically and chronologically scarce and scattered, the exception being the coast. For this latter area, it is possible to posit the existence of an occupation hiatus extending from at least around 3400 cal BP to around 2350 cal BP. After this latter date, a regional incremental trend is evident, along with the earliest presence of ceramics, as well as evidence of probable horticultural practices. On the other hand, the coast, compared to the valley and cordillera, has been the most active area for archaeological research and dating since the 1990s. This database as a whole helps to expose research biases and current gaps, in order to improve and expand our knowledge of the long history of Southern Chile's human occupation. [ABSTRACT FROM AUTHOR]

For a graph G = (V , E) and positive integer p , the exact distance- p graph G [ ♮ p ] is the graph with vertex set V and with an edge between vertices x and y if and only if x and y have distance p. Recently, there has been an effort to obtain bounds on the chromatic number χ (G [ ♮ p ] ) of exact distance- p graphs for G from certain classes of graphs. In particular, if a graph G has tree-width t , it has been shown that χ (G [ ♮ p ] ) ∈ O (p t − 1) for odd p , and χ (G [ ♮ p ] ) ∈ O (p t Δ (G)) for even p. We show that if G is chordal and has tree-width t , then χ (G [ ♮ p ] ) ∈ O (p t 2) for odd p , and χ (G [ ♮ p ] ) ∈ O (p t 2 Δ (G)) for even p. If we could show that for every graph H of tree-width t there is a chordal graph G of tree-width t which contains H as an isometric subgraph (i.e., a distance preserving subgraph), then our results would extend to all graphs of tree-width t. While we cannot do this, we show that for every graph H of genus g there is a graph G which is a triangulation of genus g and contains H as an isometric subgraph. [ABSTRACT FROM AUTHOR]

In recent decades, cobalt catalyst has represented a powerful strategy for developing common organic reactions. This review includes the most recent efforts of Co catalysts applications in selective organic reactions such as C–H & C—X activation, hydrogenation & dehydrogenation, and cycloaddition. The contribution of cobalt salt or earth-abundant cobalt complexes usually accomplishes these reactions. It mainly involves different fundamental reaction paths, such as the concerted metalation-deprotonation (CMD) path associated with non-oxidative C–H activation and the intermolecular single-electron transfer (SET) path. Here, we summarize the advances of Co catalyst applications in three main sections: (i) C–H & C—X activation, (ii) hydrogenation-dehydrogenation, and (iii) cycloaddition. The characteristics of each catalyst are discussed according to parameters such as efficiency, recyclability, catalyst life, lack of catalyst nanoparticles agglomeration, and required time of catalyst effects on the reactions. [Display omitted] [ABSTRACT FROM AUTHOR]