Isolation and characterization of the full-length cDNA encoding a member of a novel cytochrome p450 family (CYP320A1) from the tropical freshwater snail, Biomphalaria glabrata, intermediate host for Schistosoma mansoni

Cytochrome p450s (cyp450s) are a family of structurally related proteins, with diverse functions, including steroid synthesis and breakdown of toxins. This paper reports the full-length sequence of a novel cyp450 gene, the first to be isolated from the tropical freshwater snail Biomphalaria glabrata, an important intermediate host of Schistosoma mansoni. The nucleotide sequence is 2291 bp with a predicted amino acid sequence of 584aa. The sequence demonstrates conserved cyp450 structural motifs, but is sufficiently different from previously reported cyp450 sequences to be given a new classification, CYP320A1. Initially identified as down-regulated in partially resistant snails in response to S. mansoni infection, amplification of this gene using RT-PCR in both totally resistant or susceptible snail lines when exposed to infection, and all tissues examined, suggests ubiquitous expression. Characterization of the first cyp450 from B. glabrata is significant in understanding the evolution of these metabolically important proteins

Investigating the factors that influence the use of digital learning resources in the K-12 educational context

Australian and New Zealand governments have made a significant investment in the establishment of an on-line repository that will make digital learning resources, also called learning objects, available to teachers in the K-12 sector. The focus of this, and similar learning object initiatives around the world, has been on content development and delivery. Much of the current learning object research has been concerned with resolving the technical issues to support these processes, with little attention paid to pedagogical and practical issues that might influence learning object use. This paper argues for research to address this gap and reports on a study investigating the factors that influence the use of digital learning resources in the K-12 educational context. The findings of the study are relevant to understanding how learning object approaches can be best conceived of and supported

Experiential Learning Through the Transformational Incubation Programme: A Case Study from Accra, Ghana

This topical new book provides an illuminating overview of enterprise education, and poses the question as to whether current establishments have adequate systems in place to prepare students for the world of work

Stretched exponential relaxation in the mode-coupling theory for the Kardar-Parisi-Zhang equation

We study the mode-coupling theory for the Kardar-Parisi-Zhang equation in the strong-coupling regime, focusing on the long time properties. By a saddle point analysis of the mode-coupling equations, we derive exact results for the correlation function in the long time limit - a limit which is hard to study using simulations. The correlation function at wavevector k in dimension d is found to behave asymptotically at time t as C(k,t)\simeq 1/k^{d+4-2z} (Btk^z)^{\gamma/z} e^{-(Btk^z)^{1/z}}, with \gamma=(d-1)/2, A a determined constant and B a scale factor.Comment: RevTex, 4 pages, 1 figur

Transmission through optically generated inductive grid arrays

A technique is developed for generating pseudometallic plasma inductive grid arrays within a semiconductor wafer. The induced plasma elements are defined by a surface impedance which is discussed. Results of an investigation into the transmission properties of a variety of array designs between 16 and 40 GHz are presented. Measurements are performed on a silicon wafer illuminated by an external optical source via a negative image mas

A comparison of systems for measuring methane emissions from sheep

Two experiments were conducted, at ADAS Drayton in the autumn and winter 1996/1997, to compare methane (CH4) emissions from sheep housed either in a polytunnel system or in open-circuit respiration chambers. In each system, the sheep received maintenance levels of either cut grass or high temperature dried grass pellets (HTDG). All experiments in the tunnel were conducted on concrete to avoid any interactions of the CH4 with the soil/plant environment. The results suggested that CH4 production from the open-circuit chambers was greater than from the tunnel system (26·9±0·46 v. 31·7±0·35 l/kg dry matter intake (±S.E.) for open circuit respiration chambers and tunnel, respectively). Recovery tests gave similar results for both systems (95·5–97·9% for tunnels and 89·2–96·7% for chambers), and confirmed that both methods give good quantitative recovery of added CH4, and can therefore be assumed to provide reliable estimates of emissions from animals. There is no technical explanation, therefore, for the different estimates of emissions provided by the two systems. Further studies are required to understand the reasons for the differences and in particular, the possible links between animal behaviour induced by the two systems and CH4 emission rates

Close coupled resonant aperture inserts for waveguide filtering applications

A two-layer frequency selective surface (FSS) is used as a very compact and lightweight transverse waveguide filter element. A narrow-band transmission response is produced from two layers, which, otherwise, in isolation would exhibit a broadband response. Measured results are compared with theoretical data obtained from a Transmission Line Matrix (TLM) based modeling method. Reduction in the passband bandwidth of a factor of four has been achieved using the proposed structure

Experimental measurements of thermal barrier coating interfacial fracture toughness as a function of mode-mix

Mechanism-based lifetime assessment models of thermal barrier coating (TBC) systems for gas turbine engines rely on accurate knowledge of the experimentally measured interfacial fracture toughness over a range of mode mix and especially at mode-II. Previously no reliable test method had been employed to evaluate these properties under pure mode-II conditions, which are most representative of critical TBC spall delamination upon turbine engine cool down. A newly developed compression edge-delamination (CED) test, based off of theoretical considerations by John Hutchinson, has been employed to measure the strain energy release rate (Gc) associated with delamination between the bond coat and top coat layers under a nearly pure mode-II loading condition. Utilizing modified 4-point bend experiments and the CED methodology, has allowed for direct measurement of coating interfacial toughness as a function of mode mix. The material system examined was provided by collaborators at GE and consists of an Electron-Beam Physical Vapor Deposited (EBPVD) 7% Yttria-Stabilized Zirconia (YSZ) top coat, which is deposited on a Pt-modified diffusion aluminide β-(Ni,Pt)Al bond coat on a single crystal René N5 substrate. Using the CED test, a 50% reduction in mode-II interfacial toughness was associated with thermal cycling. Results for as-deposited samples tested using a modified 4-point bend technique matches previously reported data, and a mode-mix dependent toughness function for the as-deposited interfacial toughness has also been discovered using results from this study and from previously reported values. Specimen design and preparation and the use of starter cracks to assure proper delamination are discussed. Crack face friction is shown to play a significant role in calculation of the interfacial toughness and details regarding the experimental characterization of the interfacial friction coefficient and implementation into the finite element model used to extract the interfacial toughness are examined. Details regarding the use of Digital Image Correlation (DIC) to calculate the critical stress for crack growth in the CED test are also be discussed. Results from the both the CED and the modified 4-point bend experiments are examined and analyzed along with microstructural and chemical observations of degradation of the coating interfaces as a result of thermal cycling

The Nuclear Receptors of Biomphalaria glabrata and Lottia gigantea : Implications for Developing New Model Organisms

Funding: This work was funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research, Grant Ref:G0900802 to CSJ, LRN, SJ & EJR [www.nc3rs.org.uk]. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD