Investigating the effect of tunnelling on existing tunnels

A major research project investigating the effect of tunnelling on existing tunnels has been completed at Imperial College London. This subject is always of great concern during the planning and execution of underground tunnelling works in the urban environment. Many cities already have extensive existing tunnel networks and so it is necessary to construct new tunnels at a level beneath them. The associated deformations that take place during tunnelling have to be carefully assessed and their impact on the existing tunnels estimated. Of particular concern is the serviceability of tunnels used for underground trains where the kinematic envelope must not be impinged upon. The new Crossrail transport line under construction in London passes beneath numerous tunnels including a number of those forming part of the London Underground networ

Purification and functional characterisation of rhiminopeptidase A, a novel aminopeptidase from the venom of Bitis gabonica rhinoceros

This study describes the discovery and characterisation of a novel aminopeptidase A from the venom of B. g. rhinoceros and highlights its potential biological importance. Similar to mammalian aminopeptidases, rhiminopeptidase A might be capable of playing roles in altering the blood pressure and brain function of victims. Furthermore, it could have additional effects on the biological functions of other host proteins by cleaving their N-terminal amino acids. This study points towards the importance of complete analysis of individual components of snake venom in order to develop effective therapies for snake bites

Lateral Gene Transfer (LGT) between Archaea and Escherichia coli is a contributor to the emergence of novel infectious disease

BACKGROUND: Lateral gene transfer is the major mechanism for acquisition of new virulence genes in pathogens. Recent whole genome analyses have suggested massive gene transfer between widely divergent organisms. PRESENTATION OF THE HYPOTHESIS: Archeal-like genes acting as virulence genes are present in several pathogens and genomes contain a number of archaeal-like genes of unknown function. Archaea, by virtue of their very different evolutionary history and different environment, provide a pool of potential virulence genes to bacterial pathogens. TESTING THE HYPOTHESIS: We can test this hypothesis by 1)identifying genes likely to have been transferred (directly or indirectly) to E. coli O157:H7 from archaea; 2)investigating the distribution of similar genes in pathogens and non-pathogens and 3)performing rigorous phylogenetic analyses on putative transfers. IMPLICATIONS OF THE HYPOTHESIS: Although this hypothesis focuses on archaea and E. coli, it will serve as a model having broad applicability to a number of pathogenic systems. Since no archaea are known vertebrate pathogens, archaeal-like transferred genes that are associated with virulence in bacteria represent a clear model for the emergence of virulence genes

The genome sequence of E. coli W (ATCC 9637): comparative genome analysis and an improved genome-scale reconstruction of E. coli

Background: Escherichia coli is a model prokaryote, an important pathogen, and a key organism for industrial biotechnology. E. coli W (ATCC 9637), one of four strains designated as safe for laboratory purposes, has not been sequenced. E. coli W is a fast-growing strain and is the only safe strain that can utilize sucrose as a carbon source. Lifecycle analysis has demonstrated that sucrose from sugarcane is a preferred carbon source for industrial bioprocesses

Measured short-term ground surface response to EPBM tunnelling in London Clay

Earth-pressure-balance machines (EPBMs) were used for the construction of Crossrail tunnels in London, providing opportunities for field investigation of consequent ground response. Analysed results from an instrumented research site in Hyde Park with extensive surface and subsurface monitoring arrays are presented and discussed. The Crossrail tunnels at the site are 34·5 m below ground, deeper than those in most case histories of tunnelling in stiff clay in the UK. This paper characterises the tunnelling-induced ground response, both ‘greenfield’ and in the proximity of the existing Central Line tunnels, dealing with measurements at the ground surface. A companion paper covers the subsurface ground response. Vertical and horizontal ground surface displacements were obtained from manual precise levelling and micrometer stick measurements. Several key findings will benefit future tunnelling projects involving EPBMs. Volume loss values measured at the instrumented site were low, being less than 0·8% and 1·4% for the first and second tunnel drives respectively, higher values being associated with ground softening from the first tunnel construction. Smaller volume losses were recorded in the vicinity of the existing Central Line tunnels, compared with the greenfield location, suggesting that their presence inhibited the development of ground movements. Asymmetric settlement troughs developed due to either the nearby pre-existing tunnels or the construction of the first tunnel. Marginally smaller values of trough width parameter, Ky, were determined for these deeper tunnels compared with previous greenfield ground case histories. Resultant vectors of ground surface displacement were directed to well-defined point-sinks above the tunnel axis level

Measured short-term subsurface ground displacements from EPBM tunnelling in London Clay

Subsurface ground displacements from the construction of the twin-bore Crossrail tunnels in London Clay by earth pressure balance machines (EPBMs) are presented and discussed, complementing a companion paper by the authors that focused on the surface response. Both papers report vertical and horizontal displacements, in this case measured using comprehensive arrays of instruments installed within boreholes in Hyde Park, London. The Crossrail tunnels are deeper than those cited in most UK case histories concerning tunnelling in stiff clay. Clear insights were gained into subsurface displacement mechanisms: an ‘inward’ displacement field was observed around the Crossrail tunnel construction, in contrast to the ‘outward’ displacement field that developed around the shallower Channel Tunnel Rail Link tunnels constructed east of London using similar EPBMs in London Clay. This has important implications when estimating subsurface displacements using currently available empirical methods. Appraisal of the EPBM operational variables suggests that the relative magnitude of face and tail grout pressures to overburden stress is the key factor contributing to the opposing senses of the observed displacement fields. Earlier tunnelling-induced strain softening of the London Clay is evident from greater subsurface incremental volume losses and settlement trough width parameters relating to subsequent tunnel construction

Carotenoid interactions in peridinin chlorophyll-a proteins from dinoflagellates. Evidence for optical excitons and triplet migration.

Optical and magnetic resonance spectroscopy has been used to investigate two peridinin-chlorophyll alpha-protein (PCP) complexes constituting the peripheral antenna of the photosystem of two dinoflagellate species. One protein contains a cluster of four peridinins and one chlorophyll molecule, the other contains two such clusters in a 'quasi' dimer of the former. Evidence of intra-cluster excitonic interactions between peridinins is provided by low-temperature absorption and circular dichroism spectra. Peridinin triplets are detected in zero-field magnetic resonance spectroscopy by both optical emission and absorption. Interaction among peridinin molecules causes a fast intra-cluster and a slow inter-cluster triplet migration. The origin of the interactions is discussed by correlating optical and magnetic spectroscopic data