A tunable vacuum ultraviolet xenon laser

Imperial Users onl

Rice Tungro Spherical Virus Polyprotein Processing: Identification of a Virus-Encoded Protease and Mutational Analysis of Putative Cleavage Sites

AbstractRice tungro spherical virus encodes a large polyprotein containing motifs with sequence similarity to viral serine-like proteases and RNA polymerases. Polyclonal antisera raised against domains of the putative protease and polymerase in fusion with glutathioneS-transferase detected a protein of about 35 kDa and, in very low amounts, a protein of about 70 kDa, respectively, in extracts from infected plants. Inin vitrotranscription/translation systems and inEscherichia coliwe demonstrated a proteolytic activity in the C-terminal region of the polyprotein. This protease rapidly cleaved its polyprotein precursorsin vitro.Mutating a potential cleavage site located N-terminal to the protease domain, Gln2526-Asp2527, diminished processing. The transversion mutation at the putative C-terminal cleavage site of the protease, at Gln2852-Ala2853, led to a delayed and partial processing

Improving habitat heterogenity on coastal defence structures

Sea level rise and higher storm frequency is increasing the need for hard coastal defences worldwide. The majority of these structures lack optimal habitats for intertidal species, resulting in low diversity. Here, we evaluate low-cost enhancement techniques which increase habitat heterogeneity and surface texture on different rock types. Arrays of holes and grooves inspired by ‘blast features’ produced during the quarrying process were created on both granite rock armour and limestone rock groynes in two locations in England. After 12 months the treatments were successful at attracting new species to the defence structures and increasing the overall diversity and abundance of organisms. Mobile fauna including crabs and fish were recorded utilising the holes and grooves. Non -native species were recorded in grooves at one site but in no greater abundance than control areas. At the southern site, species known to be spreading in response to climate changes were found in both treatments but not in controls. The cost of these treatments was low in relation to that of the defence scheme and could be easily replicated either during or after construction. Through evaluatio n of the use of these ecological enhancement techniques on coastal structures, we suggest that they have considerable potential to enhance local patterns of biodiversity when used within large -scale defence projects

Bridging the Gap: Connecting Authors to Museum and Archival Collections

This project improves the ability of multimedia authors to interact with the digital collections of museums, archives, and libaries, thereby enhancing experimentation in new forms of humanities scholarship. The project envisions development of an open sources bridge between a widely used digital asset management system (CONTENTdm) and applications that support the Open Knowledge Initiative's standard for interoperability, including open source, multimedia authoring tools. In a collaborative scholarly endeavor, we will use this software bridge to develop a multimedia presentation on the Pacific Northwest Artist Carl Hall (1921-1996) that directly incorporates images and audio from museum and archival digital collections

Plant virus gene expression strategies

Plant viruses can cause serious losses to most, if not all, major crops upon which depend for food. Many viruses are endemic, causing moderate losses each year. Others, such as those causing rice tungro, give periodic severe epidemics. There are no fully collated figures for world-wide losses due to viruses but some examples has been listed, i.e., rice tungro in SE ASIA and african cassava mosaic in Africa with 1,500 and 2,000 millions dollars per year in losses respectively. However, in recent years the understanding of the genome organisation of plant viruses has increased in parallel with development of molecular biological techniques. The ability to obtain nucleotide sequences of complete viral genomes has also permitted the elucidation and understanding of expression strategies used by many different plant viruses. This review is aimed to summarise some aspects of the main strategies used by plant viruses to express their genomes

Integration of Banana Streak Badnavirus into theMusaGenome: Molecular and Cytogenetic Evidence

AbstractBreeding and tissue culture of certain cultivars of bananas (Musa) have led to high levels of banana streak badnavirus (BSV) infection in progeny from symptomless parents. BSV DNA hybridized to genomic DNA of one such parent, Obino l'Ewai, suggesting integration of viral sequences. Sequencing of clones of Obino l'Ewai genomic DNA revealed an interface between BSV andMusasequences and a complex BSV integrant.In situhybridization revealed two different BSV sequence locations in Obino l'Ewai chromosomes and a complex arrangement of BSV andMusasequences was shown by probing stretched DNA fibers. This is the first report of integrated sequences that possibly lead to a plant pararetrovirus episomal infection by a mechanism differing markedly from animal retroviral systems

Systematic Design of Attitude Control Systems for a Satellite in a Circular Orbit with Guaranteed Performance and Stability

In this paper two nonlinear control techniques are developed and compared for the satellite attitude control problem. The first technique is a robust recursive nonlinear method using Euler angle formulation. This method is related to integrator backstepping as well as feedback linearization techniques. However, in this paper a different formulation is presented which overcomes some of the previous difficulties in applying backstepping to this problem by treating the three axis satellite system as a fully coupled set of second order systems. The technique produces a robustly stable controller, which meets desired performance, accounts for system nonlinear behavior, and is easily implementable in a set of feedback equations that can be computed in real time. The second technique is a learning control that updates the control input iteratively in order to enhance the transient performance of systems that are repeatedly executed over a fixed finite duration. It updates the control input by learning laws without the computation of system parameters and inverse dynamics of systems. The advantage of utilizing learning control schemes for attitude control systems is the enhancement of transient performance from trial to trial by taking advantage of the periodicity of the repeated system operation. By learning unknown parameters or time functions, the learning control can compensate nonlinear dynamics so that the desired performance can be achieved. The performance of both techniques is demonstrated for a satellite attitude tracking maneuver which represents a satellite in a circular orbit maintaining one face toward the earth while tracking simultaneous sinusoidal pointing commands in the other two axes. It is shown that the recursive controller provides the desired tracking performance with reasonable control effort, and that the learning control technique can be used to compensate for periodic external disturbances

Dispersion of Magnetic Fields in Molecular Clouds. IV - Analysis of Interferometry Data

We expand on the dispersion analysis of polarimetry maps toward applications to interferometry data. We show how the filtering of low spatial frequencies can be accounted for within the idealized Gaussian turbulence model, initially introduced for single-dish data analysis, to recover reliable estimates for correlation lengths of magnetized turbulence, as well as magnetic field strengths (plane-of-the-sky component) using the Davis–Chandrasekhar–Fermi method. We apply our updated technique to TADPOL/CARMA data obtained on W3(OH), W3 Main, and DR21(OH). For W3(OH), our analysis yields a turbulence correlation length δ ≃ 19 mpc, a ratio of turbulent-to-total magnetic energy 〈B〉_^2_t/〈B^2〉 ≃ 0.58, and a magnetic field strength B_0 ~ 1.1 mG for W3 Main δ ≃ 22mpc, 〈B_t^2〉/〈B^2〉 ≃ 0.74, and B_0 ~ 0.7 mG while for DR21(OH) δ ≃ 12 mpc, 〈B_t^2〉/〈B^2〉 ≃ 0.70, and B_0 ~ 1.2 mG