The Gravity Signature of a Large Quaternary Depocentre off Southeastern Canada

New bathymetry, gravity and Pliocene - Quaternary sediment isopach maps have been compiled and gridded for the Scotian margin. A large positive gravity anomaly exists over the Laurentian Fan, which is the major Pliocene - Quaternary depocentre on the Scotian margin. This gravity anomaly is not related to deep structure but can be largely explained by considering the Pliocene-Quaternary sediments as isostatically uncompensated. This implies that the underlying continental margin lithosphère has had considerable strength for at least 3 Ma. Some residual anomalies not accounted for by Pliocene-Quaternary sediment thickness may represent thicker Miocene depocentres, but improved seismic and stratigraphie data are required to assess this possibility. The technique of gravity identification of major sediment depocentres is a useful reconnaissance tool in certain circumstances, such as where there is a topographic expression and the deposit is thick and of major areal extent.On a procédé à la compilation des cartes bathymétrique, de gravité marine et des cartes isopaques des sédiments pliocènes/quaternaires de la marge continentale de Scotian. Il existe une importante anomalie gravimetrique au-dessus du cône Laurentien, principale zone d'accumulation pliocène/quaternaire de la marge continentale de Scotian. L'anomalie gravimetrique n'est pas reliée à la tectonique de fond, mais peut en bonne partie s'expliquer si l'on considère que les sédiments pliocenes/ quaternaires n'ont subi aucune compensation isostatique. Ceci implique que la lithosphère de la marge continentale sous-jacente offre une grande résistance depuis au moins 3 Ma. Certaines anomalies résiduelles non imputables à l'épaisseur de la couverture sédimentaire pliocène/quaternaire pourraient être attribuées aux épaisses zones d'accumulation du Miocène; de meilleures connaissances de la sismicité et de la stratigraphie sont nécessaires pour confirmer cette hypothèse. La technique permettant de déterminer la gravité des zones de grande accumulation est un bon outil de reconnaissance en certains cas, c'est-à-dire lorsqu'il y a un relief d'importance et que le dépôt est épais et d'une grande superficie.Neue Karten der Tiefseelotung, der Tiefsee-Schwere und "isopache" Karten der Pliozân/Quaternàr-Sedimente wurden fur den Konti-nentalsaum von Nova Scotia kompiliert. Eine breite, positive Schwereanomalie besteht ûber dem laurentidischen Fâcher, welcher die Hauptablagerungszone im Pliozân-Quaternâr am Kontinentalsaum von Nova Scotia ist. Dièse Schwereanomalie beruht nicht auf der Tiefenstruktur, sondern kann weitgehend dadurch erklàrt werden, daB die Pliozàn-Quatemàr-Sedimente isostatisch nicht kompensiert waren. Dies bedeutet, dafî die Erdkruste des darunterliegenden Kon-tinentalsaums seit mindestens 3 Ma eine betràchtliche Widerstandsfàhigkeit aufweist. Einige Rest-Anomalien, die nicht auf die Dicke des Pliozàn-Quaternâr-Sediments zurùckgefùhrt werden kônnen, kônnten mit dickeren Ablagerungszonen aus dem Miozân erklàrt werden; doch um dièse Môglichkeit zu bestàtigen, sind verbesserte seismische und stratigraphische Messungen nôtig. DieTechnik, die Schwere von bedeutenden Sedimentablagerungs zonen zu bestimmen, ist unter bestimmten Voraussetzungen ein nùtzliches Erkennungs instrument, wie z.B. wenn ein wichtiges Relief vorhanden ist, und die Ablagerung dick und von grôBeren AusmaBen ist

Eliciting and specifying requirements for highly interactive systems using activity theory

The processes of eliciting user requirements and formalising these into specifications are critical for the success of highly interactive systems. These processes are still poorly understood, partly because current methods are usually ad hoc and lack any theoretical basis. A number of researchers have used Activity Theory (AT) to refine these processes and have met with some success. To date, this approach has been more useful explaining the processes post hoc. This positional paper proposes an AT method for requirement elicitation and specification definition. The method is sufficiently prescriptive and well formed that it does not require any detailed understanding of AT

A set of dual promoter vectors for high throughput cloning, screening, and protein expression in eukaryotic and prokaryotic systems from a single plasmid

BACKGROUND: The ability to produce the same recombinant protein in both prokaryotic and eukaryotic cells offers many experimental opportunities. However, the cloning of the same gene into multiple plasmids is required, which is time consuming, laborious and still may not produce soluble, stable protein in sufficient quantities. We have developed a set of expression vectors that allows for ligation-independent cloning and rapid functional screening for protein expression in both E. coli and S. cerevisiae. RESULTS: A set of expression vectors was made that can express the same open reading frame in E. coli (via the T7 phage promoter) and in S. cerevisiae (via the CUP1 or MET25 promoter). These plasmids also contain the essential elements for replication and selection in both cell types and have several advantages: they allow for cloning of genes by homologous recombination in yeast, protein expression can be determined before plasmid isolation and sequencing, and a GST-fusion tag is added to aid in soluble expression and purification. We have also included a TEV recognition site that allows for the specific cleavage of the fusion proteins to yield native proteins. CONCLUSIONS: The dual promoter vectors can be used for rapid cloning, expression, and purification of target proteins from both prokaryotic and eukaryotic systems with the ability to study post-translation modifications

Use of Malaria Rapid Diagnostic Test to Identify Plasmodium knowlesi Infection

Reports of human infection with Plasmodium knowlesi, a monkey malaria, suggest that it and other nonhuman malaria species may be an emerging health problem. We report the use of a rapid test to supplement microscopic analysis in distinguishing the 5 malaria species that infect humans

Vps27-Hse1 and ESCRT-I complexes cooperate to increase efficiency of sorting ubiquitinated proteins at the endosome

Ubiquitin (Ub) attachment to cell surface proteins causes their lysosomal degradation by incorporating them into lumenal membranes of multivesicular bodies (MVBs). Two yeast endosomal protein complexes have been proposed as Ub-sorting “receptors,” the Vps27-Hse1 complex and the ESCRT-I complex. We used NMR spectroscopy and mutagenesis studies to map the Ub-binding surface for Vps27 and Vps23. Mutations in Ub that ablate only Vps27 binding or Vps23 binding blocked the ability of Ub to serve as an MVB sorting signal, supporting the idea that both the Vps27-Hse1 and ESCRT-I complexes interact with ubiquitinated cargo. Vps27 also bound Vps23 directly via two PSDP motifs present within the Vps27 COOH terminus. Loss of Vps27-Vps23 association led to less efficient sorting into the endosomal lumen. However, sorting of vacuolar proteases or the overall biogenesis of the MVB were not grossly affected. In contrast, disrupting interaction between Vps27 and Hse1 caused severe defects in carboxy peptidase Y sorting and MVB formation. These results indicate that both Ub-sorting complexes are coupled for efficient recognition of ubiquitinated cargo