High-precision U–Pb dating of complex zircon from the Lewisian Gneiss Complex of Scotland using an incremental CA-ID-TIMS approach

A novel approach of thermally annealing and sequentially partially dissolving single zircon grains prior to highprecision Isotope Dilution Thermal Ionization Mass Spectrometry (ID-TIMS) is presented. This technique is applied to complex zircon from the Precambrian Lewisian Gneiss Complex of Scotland. Up to six partial dissolutions were conducted at incrementally higher temperatures and analysed at each successive step. ID-TIMS analyses reveal the portions of zircon affected by the lowest temperature partial dissolution step have suffered Pb-loss. Successively higher temperature partial dissolution steps yield a series of analyses fromthe younger domains, followed by mixing trajectories with older components, presumably fromthe inner domains. Specifically, for a partially retrogressed granulite tonalite gneiss from the central block (Assynt), high-grade metamorphic zircon ages of c. 2500 Ma and c. 2700Ma are resolved with a protolith age of c. 2860Ma also recognised. This unequivocally demonstrates two separate episodes of high-grade metamorphism affected rocks from this region. The c. 2700Ma age provides aminimumage constraint on the highest pressure event known fromArchean crustal rocks. Using this technique of pseudo-spatial resolution coupled with high-precision analysis it is possible to recognise discrete Pb-loss andmultiple stages of zircon growth or isotopic resettingwithin single grains towithin 0.1–0.2% error (2σ) on individual 207Pb/206Pb ages. This method has relevance to U–Pb zircon geochronology where conventional micro-beam techniques are unable to resolve between separate ages within single grains

Reverse Engineering User Interfaces for Interactive Database Conceptual Analysis

Acceptance rate: 15%, Rank (CORE): AInternational audienceThe first step of most database design methodologies consists in eliciting part of the user requirements from various sources such as user interviews and corporate documents. These requirements formalize into a conceptual schema of the application domain, that has proved to be difficult to validate, especially since the visual representation of the ER model has shown understandability limitations from the end-users standpoint. In contrast, we claim that prototypical user interfaces can be used as a two-way channel to efficiently express, capture and validate data requirements. Considering these interfaces as a possibly populated physical view on the database to be developed, reverse engineering techniques can be applied to derive their underlying conceptual schema. We present an interactive tool-supported approach to derive data requirements from user interfaces. This approach, based on an intensive user involvement, addresses a significant subset of data requirements, especially when combined with other requirement elicitation techniques

Colonic Dendritic Cells, Intestinal Inflammation, and T Cell-Mediated Bone Destruction Are Modulated by Recombinant Osteoprotegerin

AbstractAutoimmune associated bone disease and intestinal inflammation are closely linked with deregulation and hyperactivation of autoreactive CD4 T cells. How these T cells are activated and mediate disease is not clear. Here we show that in the Interleukin 2-deficient mouse model of autoimmunity spontaneous osteopenia and colitis are caused by increased production of the ligand for receptor activator of NFκB (RANKL). RANKL acting via its receptor, receptor activator of NFκB (RANK), increases bone turnover and promotes intestinal dendritic cell (DC) survival in vivo. Modulation of RANKL-RANK interactions with exogenous recombinant osteoprotegerin (Fc-OPG) reverses skeletal abnormalities and reduces colitis by decreasing colonic DC numbers. This study identifies a common causal link between bone disease and intestinal inflammation and establishes the importance of DC in mediating colonic inflammation in vivo