Geomorphology, Stratigraphy and 14C-Chronology of Ancient Tufas at Louie Creek, Northwest Queensland, Australia

Louie Creek is a karst spring-fed stream situated in the seasonally humid tropics of northwest Queensland, Australia. It rises as a series of small exsurgences along the eastern edge of the Barkly Tableland. As it enters the lowlands of the Carpentaria plain, the creek deposits tufa which produces a series of cascades. This modern tufa extends discontinuously for about 1.5 km. A series of ancient tufas, in places lying adjacent to sites of modern deposition, extends discontinously for about 8 km downstream. At least two ancient tufa units are preserved at one location, Little lndarri site. The older unit comprises a sequence of well-preserved barrages with an orientation transverse to present-day stream flow. In places, erosion has reduced these barrages to their calcrete substrate. The older tufa is overlain in places by sediment which has become cemented to form a second calcrete unit. This sediment is in turn succeeded by the younger ancient tufa. Subsequent river incision has removed part of the sediment from the older unit and exposed several contact points between the ancient tufa and calcrete units. Radiocarbon dating of the Little lndarri site tufas, as well as other ancient Louie Creek units, yielded apparent ages ranging from ~ 30 to ~ 14 ka BP, suggesting that conditions were sufficiently wet during the period immediately preceding and throughout the Last Glacial Maximum for tufa depostion to occur. However, ancient tufa formation occurred during a phase of net river aggradation. There is geomorphic evidence that such aggradation was a result of an increased sediment supply to the fluvial system, most likely in response to conditions drier than present. Results from studies elsewhere in the region support such a Late Pleistocene trend. Incision of Louie Creek, which postdates the youngest of the dated ancient tufas, is most likely to have resulted from a shift to wetter conditions during the early Holocene,Le Louie Creek est un ruisseau issue d'une source karstique dans les tropiques humides du nord-ouest du Queensland. En entrant dans la plaine de Carpentaria, Ie ruisseau dépose un tuf qui forme une série de cascades. Ce tuf moderne s'étend de façon discontinue sur environ 1,5 km. Une série de tufs anciens, parfois adjacents, s'étendent de façon discontinue sur environ 8 km en aval. Au moins deux unités de tuf ancien sont conservées à un endroit, le site de Little lndarri. L'unité la plus ancienne comprend une suite de barrages bien conservés dont l'orientation est transversale à l'écoulement actuel. Le tuf le plus ancien est parfois recouvert par un sédiment qui s'est cimenté pour former une deuxième unité d'encroûtement. Ce sédiment, à son tour, laisse place à un tuf ancien plus récent. L'encaissement subséquent du ruisseau a fait disparaître une partie du sédiment de l'unité plus ancienne. La datation au 14C des tufs de Little lndari ainsi que d'autres unités anciennes du Louie Creek a donné des âges entre ~ 30 et ~ 14 ka BP, indiquant que le climat était suffisamment humide au cours de la période précédente et tout au long du dernier maximum glaciaire pour permettre le dépôt de tuf. Toutefois, la formation du tuf ancien s'est produite pendant une phase d'alluvionnement important. Des indications géomorphologiques montrent qu'un tel alluvionnement était le résultat de l'accroissement de l'apport sédimentaire dans le réseau, tout probablement en réponse à un climat plus sec. Les résultats d'études entreprises ailleurs dans la région corrobore cette tendance au Pleistocene supérieur. L'encaissement du Louie Creek, survenu après la formation du plus récent des tufs anciens, résulte probablement d'un changement à des conditions plus humides survenu au cours de l'Holocène inférieur.Der Louie Creek ist ein im Frùhling genâhrtes Karst-FlùBchen in den saisonbedingt feuchten Tropen von Nordwest-Queensland. Er entspringt als eine Série von kleinen AusfluBstellen làngs des ôstlichen Randes des Barkley-Tafellandes. Sobald er in die Niederungen der Carpentaria-Ebene eintritt, lagert er Tuffe ab, welche eine Série von Wasserfâllen produzieren. Dieser moderne Tuff breitet sich diskontinuierlich ùber etwa 1,5 km aus. Eine Série von alten Tuffen, welche sich an Plâtzen neben der modernen Ablagerung befinden, erstreckt sich diskontinuierlich ùber etwa 8 km fluBabwàrts. Mindestens zwei alte Tuff-Einheiten sind an einer Stelle erhalten, am Platz von Little lndarri. Die altère Einheit umfaBt eine Folge von guterhaltenen Dâmmen, deren Orientierung quer zum heutigen Lauf liegt. Der altère Tuff ist an manchen Stellen von Sediment ùberlagert, das so verkittet ist, daB es eine zweite Verkrustungseinheit bildet. Auf dieses Sediment folgt wiederum ein alter Tuff neueren Datums. Die darauffolgende FlulB-Eindàmmung hat einen Teil des Sediments der âlteren Einheit ausgegraben. Radiokarbondatierung der Tuffe von Little lndarri sowie andere alte Louie Creek-Einheiten lieferten offensichtliche Alter zwischen -30 bis -14 ka v.u.Z. Sie lassen erkennen, daB das Klima wâhrend der Zeit unmittelbar vor und wâhrend des letzten glazialen Maximums feucht genug war, urn die Ablagerung von Tuff zu ermôglichen. Indessen geschah die alte Tuff-Bildung wâhrend einer Phase reiner FluBanschwemmung. Geomorphologische Belege zeigen, daB dièse Anschwemmung wegen einer verstârkten Sediment-Zufuhr zu dem FluB-System stattfand, hôchstwahrschein-lich als Reaktion auf trockenere klimatische Bedingungen als gegenwârtig. Die Eindâmmung des Louie Creek, welche nach der Bildung des jungsten der datierten alten Tuffe stattfand, ist wohl auf einen Wechsel zu feuchteren klimatischen Bedingungen wâhrend des frùheren Holozâns zurùckzufùhren

Régler les confl its territoriaux au Somaliland

John Drysdale montre comment les SIG aident d'anciens réfugiés à faire valoir leurs droits sur leurs terres

Evolutionary history of the ADRB2 gene in humans

No abstract available

Identification of a selective G1-phase benzimidazolone inhibitor by a senescence-targeted virtual screen using artificial neural networks

Cellular senescence is a barrier to tumorigenesis in normal cells and tumour cells undergo senescence responses to genotoxic stimuli, which is a potential target phenotype for cancer therapy. However, in this setting, mixed-mode responses are common with apoptosis the dominant effect. Hence, more selective senescence inducers are required. Here we report a machine learning-based in silico screen to identify potential senescence agonists. We built profiles of differentially affected biological process networks from expression data obtained under induced telomere dysfunction conditions in colorectal cancer cells and matched these to a panel of 17 protein targets with confirmatory screening data in PubChem. We trained a neural network using 3517 compounds identified as active or inactive against these targets. The resulting classification model was used to screen a virtual library of ~2M lead-like compounds. 147 virtual hits were acquired for validation in growth inhibition and senescence-associated β-galactosidase (SA-β-gal) assays. Among the found hits a benzimidazolone compound, CB-20903630, had low micromolar IC50 for growth inhibition of HCT116 cells and selectively induced SA-β-gal activity in the entire treated cell population without cytotoxicity or apoptosis induction. Growth suppression was mediated by G1 blockade involving increased p21 expression and suppressed cyclin B1, CDK1 and CDC25C. Additionally, the compound inhibited growth of multicellular spheroids and caused severe retardation of population kinetics in long term treatments. Preliminary structure-activity and structure clustering analyses are reported and expression analysis of CB-20903630 against other cell cycle suppressor compounds suggested a PI3K/AKT-inhibitor-like profile in normal cells, with different pathways affected in cancer cells

Seeking cyclonic activity records in speleothems from central Pacific: preliminary sample screening

PosterInternational audienceIdeal cyclone-sensitive speleothems would have the following properties: active at the time of sampling and recording the past few millenia, with fast growth rate, made of clean primary calcite, precipitated without kinetic fractionation, and fed by water with a short residence time allowing for the isotopic signal of short events like cyclones to be transferred but long enough for the drip water to be supersaturated. The screening for this type of speleothem is still in progress and the results presented here are very preliminary. U-Th dating: low U concentration (9-40ng/g; host rock is reef limestone) ; significant detrital content, involving large corrections and large final age uncertainties. Growth rate is highly variable, from ~0.12 mm/yr to ~0.03mm/yr. Tau12A: δ 18 O profile shows some quite large variations (~3‰), with several abrupt events that we will try to identify in other archives. δ 13 C signal amplitude is very large (~-4 to ~-14‰) suggesting the effect of prior calcite precipitation. The δ 18 O signal gets heavier when the δ 13 C does, which could reflect the rainfall amount in this context. Var12C: δ 18 O profile shows values between-3.1 and-6.3‰, with decadal or centennial fluctuations, superimposed on a general trend which is consistent with the one of the δ 13 C profile without being correlated, which implies that calcite precipitation could occur in conditions close to isotopic equilibrium. Once properly dated, this record should provide interesting information about past rainfall regimes on the island

Pressure control for managing and optimizing adjacent subsurface operations in large scale CCS

Injecting CO2 in to the subsurface for safe storage of CO2 the pressure propagates far away from the injection point and this can be a potential problem if the overpressure extents to neighbouring subsurface activities or potential leakage pathways. For structural closure trap configurations the CO2 plume is captured within the local structural closure but the pressure footprint is on a more regional scale. This rise the question on, how large the storage complex needs to be for any individual storage operations and how large an area monitoring activities have to cover. The EC CCS guidance document addresses the issues with statements on competitions between subsurface operations but returns no absolute values. Pressure modelling of CO2 injection process with state of the art reservoir simulation tools is challenges by use of realistic model boundary conditions in order to model a realistic pressure level. Combined use of models on a site scale and on a regional scale can instruct how boundary conditions are set-up for a site scale model. Pressure management through pressure release wells could be an option to mitigate undesirable over-pressure developments. For local structural closures the pressure release wells can be placed outside the closure hereby mitigate the overpressure without introducing a potential leakage by drilling inside the trap. The paper addresses the issue of selecting model boundary conditions and modelling mitigation of pressure development by use of a large regional model with local structural traps in the Bunter Sandstone Formation in the UK Southern North Sea

Speleothem growth intervals reflect New Zealand montane vegetation response to temperature change over the last glacial cycle

Flowstone speleothem growth beneath Mount Arthur, New Zealand shows a clear relationship to vegetation density and soil development on the surface above. Flowstone does not currently form beneath sub-alpine Nothofagus forest above ca. 1000–1100 m altitude but U-Th dating shows it has formed there during past intervals of warmer-than-present conditions including an early–mid Holocene optimum and the last interglacial from ca. 131–119 ka. Some flowstones growing beneath ca. 600 m surface altitude, currently mantled with dense broadleaf-podocarp forest, grew during full glacial conditions, indicating that local tree line was never below this altitude. This implies that Last Glacial Maximum annual temperature was no more than ca. 4 °C cooler than today. Flowstone growth appears to be a robust indicator of dense surface vegetation and well-developed soil cover in this setting, and indicates that past interglacial climates of MIS 7e, 5e, the early–mid Holocene and possibly MIS 5a were more conducive to growth of trees than was the late Holocene, reflecting regional temperature changes similar in timing to Antarctic temperature changes. Here, flowstone speleothem growth is a sensitive indicator of vegetation density at high altitude, but may respond to other factors at lower altitudes

Drosophila tan Encodes a Novel Hydrolase Required in Pigmentation and Vision

Many proteins are used repeatedly in development, but usually the function of the protein is similar in the different contexts. Here we report that the classical Drosophila melanogaster locus tan encodes a novel enzyme required for two very different cellular functions: hydrolysis of N-β-alanyl dopamine (NBAD) to dopamine during cuticular melanization, and hydrolysis of carcinine to histamine in the metabolism of photoreceptor neurotransmitter. We characterized two tan-like P-element insertions that failed to complement classical tan mutations. Both are inserted in the 5′ untranslated region of the previously uncharacterized gene CG12120, a putative homolog of fungal isopenicillin-N N-acyltransferase (EC 2.3.1.164). Both P insertions showed abnormally low transcription of the CG12120 mRNA. Ectopic CG12120 expression rescued tan mutant pigmentation phenotypes and caused the production of striking black melanin patterns. Electroretinogram and head histamine assays indicated that CG12120 is required for hydrolysis of carcinine to histamine, which is required for histaminergic neurotransmission. Recombinant CG12120 protein efficiently hydrolyzed both NBAD to dopamine and carcinine to histamine. We conclude that D. melanogaster CG12120 corresponds to tan. This is, to our knowledge, the first molecular genetic characterization of NBAD hydrolase and carcinine hydrolase activity in any organism and is central to the understanding of pigmentation and photoreceptor function