A uniform isotopic and chemical signature of dust exported from Patagonia: Rock sources and occurrence in southern environments

Patagonia is considered to be the most important source of dust from South America that is deposited in surrounding areas, and we present here a systematic Sr and Nd isotopic study of sediment currently being exported. Eolian and suspended riverine sediments from Patagonia have a homogeneous chemical and isotopic composition that results from the mixing of by-products from explosive Andean volcanism, derived from the extensive Jurassic silicic Province of Chon Aike and pyroclastic materials from the basic to intermediate southern Andean Quaternary arc, which are easily denudated and dispersed. The main Andean uplift and the glaciations that began in the Late Tertiary account for the extensive distribution of these sediments in the extra-Andean region. The present geochemical signature of Patagonian sediments was produced during the Pleistocene, along with the onset of the southern Andean explosive arc volcanism. Previously published compositions of sediments from other southern South American source regions, assumed to be representative of Patagonia, are distinct from our data. Considering the alleged importance of Patagonia as a dust source for different depositional environments in southern latitudes, it is surprising to verify that the chemical and isotopic signatures of Patagonian-sourced sediments are different from those of sediments from the Southern Ocean, the Pampean Region or the Antarctic ice. Sediments from these areas have a crustal-like geochemical signature reflecting a mixed origin with sediment from other southern South American sources, whereas Patagonian sediments likely represent the basic to intermediate end-member composition

Image registration algorithm for molecular tagging velocimetry applied to unsteady flow in Hele-Shaw cell

In order to develop velocimetry methods for confined geometries, we propose to combine image registration and volumetric reconstruction from a monocular video of the draining of a Hele-Shaw cell filled with water. The cell’s thickness is small compared to the other two dimensions (e.g. 1x400 x 800 mm3). We use a technique known as molecular tagging which consists in marking by photobleaching a pattern in the fluid and then tracking its deformations. The evolution of the pattern is filmed with a camera whose principal axis coincides with the cell’s gap. The velocity of the fluid along this direction is not constant. Consequently, tracking the pattern cannot be achieved with classical methods because what is observed is the integral of the marked molecules over the entire cell’s gap. The proposed approach is built on top of direct image registration that we extend to specifically model the volumetric image formation. It allows us to accurately measure the motion and the velocity profiles for the entire volume (including the cell’s gap) which is something usually hard to achieve. The results we obtained are consistent with the theoretical hydrodynamic behaviour for this flow which is known as the Poiseuille flow

Conception parasismique des contreventements concentriques pour les structures industrielles lourdes en acier

RÉSUMÉ Plusieurs grands complexes industriels au Canada sont localisés dans des zones sismiques importantes. Les structures doivent donc être conçues pour résister à de fortes secousses sismiques sans subir de dommages majeurs. La conception parasismique de ces structures est généralement effectuée de la même manière que pour les bâtiments standards alors que les propriétés dynamiques pour ces deux catégories de structures divergent grandement. Qui plus est, les règles de conception parasismique du Code national du bâtiment du Canada ont été développées principalement pour des structures régulières de bâtiments à vocations résidentielle, commerciale ou institutionnelle.----------ABSTRCT Several heavy industrial complexes in Canada are located in major seismic zones. These structures must be designed to withstand strong seismic forces without major damage. The seismic design of these structures is usually done in the same way as for standard buildings while the dynamic properties for these two categories of structure are greatly different. Also, the seismic design rules of the National Building Code of Canada have been developed primarily for standard structures of the residential, commercial or institutional category. In 2014, Annex M: Seismic Design of Industrial Steel Structures was created and incorporated into the CSA S16-14 standard with the aim of providing guidelines for the seismic design of heavy industrial structures

d13C tracing of dissolved inorganic carbon sources in Patagonian rivers (Argentina)

The main Patagonian rivers (Colorado, Negro, Chubut, Deseado, Coyle, Chico, Santa Cruz and Gallegos) were sampled between September 1995 and November 1998 to determine their chemical and isotopic compositions, the origins of the suspended and dissolved river loads and their inputs to the South Atlantic Ocean. This paper focuses on the dissolved inorganic carbon (DIC) transport and its υ13C isotopic signature. The υ13CDIC values vary between 12Ð8 and 1Ð8‰ and allow one to distinguish two river groups: (i) the Colorado, Negro, Chubut and Santa Cruz, which display the highest values and the lowest seasonal variations; (ii) the Deseado, Coyle, Chico and Gallegos, which show the lowest values and the highest seasonal variations. For the first group, υ13CDIC is mainly controlled by important exchanges between the river waters and atmospheric CO2, due to the presence of lakes and dams. For the second group, υ13CDIC also appears to be controlled by the oxidation of organic carbon, showing a negative relationship between υ13CDIC and the dissolved organic carbon. These biogeochemical processes interfere with the contribution of carbonate and silicate weathering to the riverine DIC and do not allow use of υ13CDIC alone to distinguish these contributions. The annual DIC flux exported by Patagonian Rivers to the South Atlantic Ocean averages 621 ð 109 g. of C, i.e. a specific yield of 2Ð7 g m2 year1. The mean υ13CDIC can be estimated to 4Ð9‰, which is high compared with other rivers of the world

Rôle des facteurs physico-chimiques du micro-environnement intestinal et des boucles inter-hélicales du Domaine I dans l’activité de la toxine insecticide Cry9Ca du bacille de Thuringe

Une fois ingérées par un insecte sensible, les toxines insecticides du bacille de Thuringe doivent être activées par les protéases intestinales de cet insecte. Leur premier domaine, un ensemble de sept hélices-α amphipathiques, est responsable de leur insertion dans la membrane luminale de certaines cellules de l’intestin médian, ce qui crée des pores peu sélectifs. La toxicité et la capacité à former des pores d’une telle toxine, la Cry9Ca, de ses mutants simples R164A et R164K et d’un fragment de 55 kDa résultant d’un clivage protéolytique au niveau de son résidu 164 ont été étudiées à l’aide d’une combinaison de modélisation par homologie, de bioessais, d’expériences de gonflement osmotique avec des vésicules de membrane en bordure en brosse de larves de sphinx du tabac et de mesures électrophysiologiques sur des intestins isolés. Ni les mutations simples ni le clivage protéolytique n’ont altéré la toxicité de la Cry9Ca. Dans une solution à faible force ionique, toutefois, la formation des pores dépend fortement du pH : une augmentation de celui-ci de 6,5 à 10,5 a entraîné une baisse irrégulière et par étapes successives de la perméabilité membranaire. Les quatre préparations de toxine ont néanmoins dépolarisé la membrane apicale d’intestins médians fraîchement isolés baignant dans une solution contenant 122 mM de KCl à pH 10,5. L’activité de la Cry9Ca, et des mutants R164A et R164K, a été grandement stimulée lorsque les expériences ont été effectuées en présence de suc intestinal, de lipides extraits d’un volume équivalent de suc intestinal ou d’un cocktail d’inhibiteurs de protéases solubles dans l’eau. De plus, le rôle des boucles inter-hélicales du Domaine I lors de l’insertion dans la membrane a été étudié avec des mutants doubles de la Cry9Ca dont les mutations introduisaient, neutralisaient ou renversaient une charge électrique. À l’exception de trois d’entres eux, tous ces mutants ont conservé une toxicité et une capacité à former des pores comparables à celles de la toxine parentale. L’ensemble de ces résultats suggère que le micro-environnement de l’intestin médian contribue à minimiser l’influence des charges de surface portées par les résidus des boucles inter-hélicales du Domaine I sur la capacité des toxines du bacille de Thuringe à former des pores. Il indique aussi que, d’une part, selon le site de clivage et les conditions expérimentales utilisées, des protéolyses supplémentaires de la toxine Cry9Ca activée peuvent soit stimuler, soit nuire à son activité et que, d’autre part, le suc intestinal du sphinx du tabac contient probablement un inhibiteur de protéases qui pourrait jouer un rôle important dans l’activité des toxines du bacille de Thuringe.Once ingested by susceptible insects, Bacillus thuringiensis insecticidal toxins must be activated by the insect’s intestinal proteases. Their first domain, a bundle of seven amphipathic -helices, is responsible for their insertion into the luminal membrane of midgut cells, thereby creating poorly selective pores. The toxicity and pore-forming ability of one such toxin, Cry9Ca, its single-site mutants, R164A and R164K, and of the 55-kDa fragment resulting from its proteolytic cleavage at residue 164 were investigated using a combination of homology modeling, bioassays, osmotic swelling experiments with Manduca sexta larval midgut brush border membrane vesicles and electrophysiological measurements on isolated midguts. Neither the single mutations nor the proteolytic cleavage altered Cry9Ca toxicity. In low ionic strength solutions however, pore formation was highly dependent on pH: increasing pH from 6.5 to 10.5 resulted in an irregular step-wise decrease in membrane permeabilization. All four toxin preparations nevertheless depolarized the apical membrane of freshly isolated midguts bathing in a solution containing 122 mM KCl at pH 10.5. The activity of Cry9Ca, R164A and R164K was greatly enhanced when the experiments were conducted in the presence of midgut juice, the lipids extracted from an equivalent volume of midgut juice or a cocktail of water-soluble protease inhibitors. Additionally, the role of the interhelical loops of Domain I in membrane insertion was investigated with Cry9Ca double mutants with mutations that either introduced, neutralized or reversed an electrical charge. All but three mutants retained a toxicity and a pore-forming ability that were comparable to those of their parental toxin. Overall, the results suggest that the midgut microenvironment contributes to minimizing the influence of surface charges carried by Domain I interhelical loop residues on B. thuringiensis toxins pore-forming ability. They also indicate that, depending on the cleavage site and on the experimental conditions used, further proteolysis of the activated Cry9Ca toxin can either stimulate or be detrimental to its activity and that M. sexta midgut juice probably contains protease inhibitors that could play a major role in the activity of B. thuringiensis toxins in the insect midgut

Terrestrial and fluvial carbon fluxes in a tropical watershed: Nyong basin, Cameroon

The Nyong watershed, with an area of 27 800 km2 and a mean annual discharge of 390 m3 s−1, is the second largest river in Cameroon. The Nyong watershed serves as an outstanding study area for the examination of carbon fluxes in humid tropical environments because of its limited anthropogenic impact and homogeneous silicate bedrock. Between April 2005 and April 2007, we sampled water at seven stations, from the small watershed of the Mengong (0.6 km2) to the Nyong at Edea (24 500 km2), and monitored temperature, pH, dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) contents, as well as the isotopic composition of DIC (δ13CDIC)andDOC(δ13CDOC).We estimated terrestrial net ecosystemproductivity in theNyong River watershed and measured fluvial fluxes of carbon to the ocean and the atmosphere. The Nyong River basin sequesters significant amounts of carbon on an annual basis: ~7 920 000t C year−1 (300 g C m−2 year−1). The combined dissolved organic, dissolved inorganic and atmospheric fluxes of carbon from the Nyong River only export 3% of this flux fromthe basin on an annual basis. This includes a minimumCO2 outgassing of 1487 g Cm−2 year−1, comparable to 115% of the annual flux of DOC and four times greater than the flux of DIC

Vélocimétrie 3D par marquage moléculaire et recalage d’image pour le passage d’une bulle isolée en cellule de Hele-Shaw

Cet article décrit l’application de techniques de vision par ordinateur à la mesure de vitesse pour deux écoulements générés en Cellule de Hele-Shaw (CH). Un Écoulement Laminaire de Poiseuille (ELP) est généré par la vidange de la CH remplie d’un liquide préalablement au repos. La figure 1 donne un aperçu de la configuration expérimentale. Nous proposons un nouvel algorithme combinant le Recalage d’Image Direct (RID) et une reconstruction volumique en vision monoculaire permettant de suivre le mouvement d’un motif marquant le liquide au niveau moléculaire. La méthode nous permet d’obtenir une mesure expérimentale de l’ELP dans des géométries à accès optique limité. Précédemment, des mesures de vitesse de cet écoulement académique ont principalement été obtenues pour des régions d’intérêt restreintes (1 mm3 par µPIV (Sinton [2004])) ou sans prise en compte directe du mouvement dans la profondeur de la CH (par PIV classique (Roudet et al. [2011])). Par comparaison, notre approche nous permet de mesurer le développement de l’ELP pour un volume conséquent en milieu confiné (ici 147×147×1 mm3). Dans un deuxième temps, nous nous intéresserons à la mesure de vitesse en amont d’une bulle en ascension dans une CH à partir d’images générées numériquement. Les phénomènes observés sont de nature déformable et nous cherchons à faire une mesure tridimensionnelle à partir d’observations 2D uniquement. Nous proposons donc une méthode reposant sur deux éléments : d’une part, une modélisation 3D du liquide et de son mouvement en CH et, d’autre part, des contraintes physiques générales et souples. Garbe et al. [2008] proposent une variante d’estimation classique par flot optique en intégrant un modèle volumique pour un écoulement gazeux en micro-canal. Cependant, dans Garbe et al. [2008], le modèle d’ELP est utilisé comme un « a priori » très fort. L’article est organisé de la manière suivante. Nous décrivons le dispositif expérimental et le marquage moléculaire par photobleaching en §2. Notre algorithme de suivi et de reconstruction est détaillé en §3. Les résultats sont présentés en §4. En §5, nous concluons et discutons des applications potentielles de notre travail

Highly Variable Rates of Genome Rearrangements between Hemiascomycetous Yeast Lineages

Hemiascomycete yeasts cover an evolutionary span comparable to that of the entire phylum of chordates. Since this group currently contains the largest number of complete genome sequences it presents unique opportunities to understand the evolution of genome organization in eukaryotes. We inferred rates of genome instability on all branches of a phylogenetic tree for 11 species and calculated species-specific rates of genome rearrangements. We characterized all inversion events that occurred within synteny blocks between six representatives of the different lineages. We show that the rates of macro- and microrearrangements of gene order are correlated within individual lineages but are highly variable across different lineages. The most unstable genomes correspond to the pathogenic yeasts Candida albicans and Candida glabrata. Chromosomal maps have been intensively shuffled by numerous interchromosomal rearrangements, even between species that have retained a very high physical fraction of their genomes within small synteny blocks. Despite this intensive reshuffling of gene positions, essential genes, which cluster in low recombination regions in the genome of Saccharomyces cerevisiae, tend to remain syntenic during evolution. This work reveals that the high plasticity of eukaryotic genomes results from rearrangement rates that vary between lineages but also at different evolutionary times of a given lineage

Automated Generation of Shuttling Sequences for a Linear Segmented Ion Trap Quantum Computer

A promising approach for scaling-up trapped-ion quantum computer platforms is by storing multiple trapped-ion qubit sets ('ion crystals') in segmented microchip traps and to interconnect these via physical movement of the ions ('shuttling'). Already for realizing quantum circuits with moderate complexity, the design of suitable qubit assignments and shuttling schedules require automation. Here, we describe and test algorithms which address exactly these tasks. We describe an algorithm for fully automated generation of shuttling schedules, complying to constraints imposed by a given trap structure. Furthermore, we introduce different methods for initial qubit assignment and compare these for random circuit (of up to 20 qubits) and quantum Fourier transform-like circuits, and generalized Toffoli gates of up to 40 qubits each. We find that for quantum circuits which contain a fixed structure, advanced assignment algorithms can serve to reduce the shuttling overhead

The fate of the duplicated androgen receptor in fishes: a late neofunctionalization event?

<p>Abstract</p> <p>Background</p> <p>Based on the observation of an increased number of paralogous genes in teleost fishes compared with other vertebrates and on the conserved synteny between duplicated copies, it has been shown that a whole genome duplication (WGD) occurred during the evolution of Actinopterygian fish. Comparative phylogenetic dating of this duplication event suggests that it occurred early on, specifically in teleosts. It has been proposed that this event might have facilitated the evolutionary radiation and the phenotypic diversification of the teleost fish, notably by allowing the sub- or neo-functionalization of many duplicated genes.</p> <p>Results</p> <p>In this paper, we studied in a wide range of Actinopterygians the duplication and fate of the androgen receptor (AR, NR3C4), a nuclear receptor known to play a key role in sex-determination in vertebrates. The pattern of AR gene duplication is consistent with an early WGD event: it has been duplicated into two genes AR-A and AR-B after the split of the Acipenseriformes from the lineage leading to teleost fish but before the divergence of Osteoglossiformes. Genomic and syntenic analyses in addition to lack of PCR amplification show that one of the duplicated copies, AR-B, was lost in several basal Clupeocephala such as Cypriniformes (including the model species zebrafish), Siluriformes, Characiformes and Salmoniformes. Interestingly, we also found that, in basal teleost fish (Osteoglossiformes and Anguilliformes), the two copies remain very similar, whereas, specifically in Percomorphs, one of the copies, AR-B, has accumulated substitutions in both the ligand binding domain (LBD) and the DNA binding domain (DBD).</p> <p>Conclusion</p> <p>The comparison of the mutations present in these divergent AR-B with those known in human to be implicated in complete, partial or mild androgen insensitivity syndrome suggests that the existence of two distinct AR duplicates may be correlated to specific functional differences that may be connected to the well-known plasticity of sex determination in fish. This suggests that three specific events have shaped the present diversity of ARs in Actinopterygians: (i) early WGD, (ii) parallel loss of one duplicate in several lineages and (iii) putative neofunctionalization of the same duplicate in percomorphs, which occurred a long time after the WGD.</p