A lithospheric instability origin for Columbia River flood basalts and Wallowa Mountains uplift in northeast Oregon

Flood basalts appear to form during the initiation of hotspot magmatism. The Columbia River basalts (CRB) represent the largest volume of flood basalts associated with the Yellowstone hotspot, yet their source appears to be in the vicinity of the Wallowa Mountains, about 500 km north of the projected hotspot track. These mountains are composed of a large granitic pluton intruded into a region of oceanic lithosphere affinity. The elevation of the interface between Columbia River basalts and other geological formations indicates that mild pre-eruptive subsidence took place in the Wallowa Mountains, followed by syn-eruptive uplift of several hundred metres and a long-term uplift of about 2 km. The mapped surface uplift mimics regional topography, with the Wallowa Mountains in the centre of a 'bull's eye' pattern of valleys and low-elevation mountains. Here we present the seismic velocity structure of the mantle underlying this region and erosion-corrected elevation maps of lava flows, and show that an area of reduced mantle melt content coincides with the 200-km-wide topographic uplift. We conclude that convective downwelling and detachment of a compositionally dense plutonic root can explain the timing and magnitude of Columbia River basalt magmatism, as well as the surface uplift and existence of the observed melt-depleted mantle.     

Evolution of genes and genomes on the Drosophila phylogeny

Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.     

Comparative pharmacopsychological study of the effects produced by psychopharmaceuticals on verbal interaction in a group of students

Zusammenfassung In einer pharmakopsychologischen Gruppenuntersuchung wurde das Problem der Wirkung von pharmakologisch und klinisch unterschiedlichen Psychopharmaka auf die verbalen Interaktionen in einer Gruppe von gesunden Probanden angegangen. Mittelpunkt der Untersuchung war die Frage, ob Thioridazin (Melleril®), Desipramin (Pertofran ®) und Placebo unterschiedlich auf Quantität und Qualität der verbalen Interaktionen der Gruppenteilnehmer wirkten. Von dieser Fragestellung wurde ein Beitrag zum Verständnis der Wirkungsweise von Psychopharmaka hinsichtlich ihrer sozialen Wirkkomponente erwartet. Der Versuch diente in erster Linie methodischen Abklärungen im Hinblick auf eine spätere Anwendung dieser Versuchsanordnung an Patientenkollektiven.Dem Versuch lag die Struktur des Lateinischen Quadrats (6 Probanden, 6 Versuchstage, 2×3=6 Präparate) zugrunde. Die statistische Auswertung ergab keine Unterschiede zwischen den Präparaten untereinander und gegenüber Placebo hinsichtlich der untersuchten Parameter der verbalen Interaktionen. Hingegen fanden sich signifikante Differenzen zwischen den einzelnen Probanden in Bezug auf ihre verbale Aktivität. Die Gründe für dieses Resultat werden diskutiert. Eine Wiederholung des Versuchs an gesunden Probanden mit entsprechenden Änderungen im Procedere ist angezeigt, bevor die Versuchsanordnung bei Patientengruppen angewendet wird.     

Arc-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua

Resolving flow geometry in the mantle wedge is central to understanding the thermal and chemical structure of subduction zones, subducting plate dehydration, and melting that leads to arc volcanism, which can threaten large populations and alter climate through gas and particle emission. Here we show that isotope geochemistry and seismic velocity anisotropy provide strong evidence for trench-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua. This finding contradicts classical models, which predict trench-normal flow owing to the overlying wedge mantle being dragged downwards by the subducting plate. The isotopic signature of central Costa Rican volcanic rocks is not consistent with its derivation from the mantle wedge or eroded fore-arc complexes but instead from seamounts of the Galapagos hotspot track on the subducting Cocos plate. This isotopic signature decreases continuously from central Costa Rica to northwestern Nicaragua. As the age of the isotopic signature beneath Costa Rica can be constrained and its transport distance is known, minimum northwestward flow rates can be estimated (63-190 mm yr(-1)) and are comparable to the magnitude of subducting Cocos plate motion (approximately 85 mm yr(-1)). Trench-parallel flow needs to be taken into account in models evaluating thermal and chemical structure and melt generation in subduction zones.