Late- to post-Variscan extensional tectonics in south Cornwall

Faults which post-date Variscan contractional deformation are ubiquitous in south Cornwall. Three broad geometric/kinematic types can be defined. The first type comprises low angle (dip <45°) extensional faults which exhibit listric or ramp and flat geometries and may display complex arrangements of secondary faults and folds in their hangingwalls. In some instances they host elvans and "mainstage" magmatic-hydrothermal lodes (more rarely lamprophyres). The second type are moderate to high angle (dip >45°) extensional faults which generally offset earlier low-angle faults; they frequently host elvans and "mainstage" magmatichydrothermal lodes. The third type are high-angle faults which usually exhibit dominant strike-slip displacement, offset all previous faults and are often associated with base metal mineralization. Collectively these structures exerted a strong control on granite emplacement, mineralization and the development of offshore sedimentary basins. The approximately coeval association of potassic volcanicity, granite magmatism, extensional faulting and sedimentary basin development was probably a consequence of late Carboniferous to early Permian collapse of previously thickened lithosphere

Exploring accumulative query expansion for relevance feedback

For the participation of Dublin City University (DCU) in the Relevance Feedback (RF) track of INEX 2010, we investigated the relation between the length of relevant text passages and the number of RF terms. In our experiments, relevant passages are segmented into non-overlapping windows of xed length which are sorted by similarity with the query. In each retrieval iteration, we extend the current query with the most frequent terms extracted from these word windows. The number of feedback terms corresponds to a constant number, a number proportional to the length of relevant passages, and a number inversely proportional to the length of relevant passages, respectively. Retrieval experiments show a signicant increase in MAP for INEX 2008 training data and improved precisions at early recall levels for the 2010 topics as compared to the baseline Rocchio feedback

Lubricant degradation, transport and the effect of extended oil drain intervals on piston assembly tribology

There are ever increasing demands on lubricant manufacturers to meet governmental legislation and customer needs by improving fuel economy, engine durability and exhaust system compatibility as shown by the introduction of GF4 and move towards GF5 specification oils. This has created an ever increasing need to understand how oil degrades in an engine and how this degraded oil affects piston assembly tribology. This review conference paper will give an overview of a collaborative project that has been undertaken to further enhance the understanding of how lubricant degrades in an operating engine, its transport through the engine and effect upon piston assembly tribology

Extraction and tribological investigation of top piston ring zone oil from a gasoline engine

With tightening emission regulations, increased expected fuel economy, and longer drain intervals impacting on lubricant formulation, greater understanding of how oil degrades in an automotive engine is becoming ever more important. Equally significant is the effect that this degraded lubricant has on the tribological operation of the engine, particularly its overall internal friction and component wear. In a previous paper, four tests to degrade oil in a single cylinder engine were reported [1]. These tests were set up such that the lubricating oil was degraded in the ring pack before returning to the sump, where it was sampled and chemical and rheological analysis undertaken. This paper reports the extension of this work using the same Hydra engine and describes how oil has additionally been extracted from the rear of the top piston ring during engine operation. This extracted oil has then been subjected to similar analysis as the sump oil samples in the previous tests, along with additional analysis to look at the tribological properties of the oil using tribometers. The results clearly show significant differences in the rheological, tribological, and chemical properties of the fresh oil and used sump oil samples when compared with the top ring zone (TRZ) oil samples, particularly the effect of load on the levels of volatiles present in the TRZ samples and their effect on traction and friction coefficient values during tribological testing

The role of post-Variscan extensional tectonics and mantle melting in the generation of the Lower Permian granites and the giant W-As-Sn-Cu-Zn-Pb orefield of SW England

Copyright © 2003 Maney Publishin

Tectonic evolution of the Plymouth Bay Basin

A synthesis of offshore seismic data in the Plymouth Bay and Western Approaches, and onshore basement structures and mineralisation history has allowed new constraints to be placed on the structural evolution of the late Carboniferous- Triassic Plymouth Bay Basin. These data have been combined to produce a model for the late- and post- Variscan tectonics of the Plymouth Bay area. Additional controls on the timing and magnitude of Variscan uplift and late-Variscan low-angle extensional deformation onshore are used to infer a late Carboniferous age for the earliest basin fill. These sediments were accommodated in a northeast — south-west oriented basin formed during late-orogenic extension. A change in the orientation of the depocentre in the early Permian signalled a switch to a north-west — south-east, strike-slip dominated tectonic environment

The role of endothelial cilia in post-embryonic vascular development

BACKGROUND: Cilia are essential for morphogenesis and maintenance of many tissues. Loss-of-function of cilia in early zebrafish development causes a range of vascular defects including cerebral haemorrhage and reduced arterial vascular mural cell coverage. In contrast, loss of endothelial cilia in mice has little effect on vascular development. We therefore used a conditional rescue approach to induce endothelial cilia ablation after early embryonic development and examined the effect on vascular development and mural cell development in post-embryonic, juvenile and adult zebrafish. RESULTS: ift54(elipsa) mutant zebrafish are unable to form cilia. We rescued cilia formation and ameliorated the phenotype of ift54 mutants using a novel Tg(ubi:loxP-ift54-loxP-myr-mcherry,myl7:EGFP)sh488 transgene expressing wildtype ift54 flanked by recombinase sites, then used a Tg(kdrl:cre)s898 transgene to induce endothelial-specific inactivation of ift54 at post-embryonic ages. Fish without endothelial ift54 function could survive to adulthood and exhibited no vascular defects. Endothelial inactivation of ift54 did not affect development of tagln-positive vascular mural cells around either the aorta or the caudal fin vessels, nor formation of vessels after tailfin resection in adult animals. CONCLUSIONS: Endothelial cilia are not essential for development and remodelling of the vasculature in juvenile and adult zebrafish when inactivated after embryogenesis

The 8Li Calibration Source for the Sudbury Neutrino Obervatory

A calibration source employing 8Li (t_1/2 = 0.838s) has been developed for use with the Sudbury Neutrino Observatory (SNO). This source creates a spectrum of beta particles with an energy range similar to that of the SNO 8B solar neutrino signal. The source is used to test the SNO detector's energy response, position reconstruction and data reduction algorithms. The 8Li isotope is created using a deuterium-tritium neutron generator in conjunction with a 11B target, and is carried to a decay chamber using a gas/aerosol transport system. The decay chamber detects prompt alpha particles by gas scintillation in coincidence with the beta particles which exit through a thin stainless steel wall. A description is given of the production, transport, and tagging techniques along with a discussion of the performance and application of the source.Comment: 11 pages plus 9 figures, Sumbitted to Nuclear Instruments and Methods

A comparison of terrestrial laser scanning and structure-from-motion photogrammetry as methods for digital outcrop acquisition

Terrestrial laser scanning (TLS) has been used extensively in Earth Science for acquisition of digital outcrop data over the past decade. Structure-from-­motion (SfM) photogrammetry has recently emerged as an alternative and competing technology. The real-world performance of these technologies for ground-based digital outcrop acquisition is assessed using outcrops from North East England and the United Arab Emirates. Both TLS and SfM are via­ble methods, although no single technology is universally best suited to all situations. There are a range of practical considerations and operating conditions where each method has clear advantages. In comparison to TLS, SfM benefits from being lighter, more compact, cheaper, more easily replaced and repaired, with lower power requirements. TLS in comparison to SfM provides intrinsically validated data and more robust data acquisition in a wide range of operating conditions. Data post-processing is also swifter. The SfM data sets were found to contain systematic inaccuracies when compared to their TLS counterparts. These inaccuracies are related to the triangulation approach of the SfM, which is distinct from the time-of-flight principle employed by TLS. An elaborate approach is required for SfM to produce comparable results to TLS under most circumstances