11-oxygenated cytotoxic 8,9-secokauranes from a New Zealand liverwort, Lepidolaena taylorii

Four new cytotoxic 8,9-secokauranes have been identified from the liverwort Lepidolaena taylorii. The 11-oxygenation found in three of these has not been encountered in the 8,9-secokauranes known from higher plants. NMR studies were combined with molecular modelling to determine the preferred conformations. Six structurally related kauren-15-ones were also found, including three new compounds. Some of these compounds showed differential cytotoxic activity against human tumor cell lines. The probable mode of cytotoxic action was supported by Michael addition of a thiol. Two 8,9-secokauranes were the main cytotoxins in another New Zealand liverwort. L. palpebrifolia.     

Executing medical guidelines on the web: Towards next generation healthcare

There is still a lack of full integration between current Electronic Health Records (EHRs) and medical guidelines that encapsulate evidence-based medicine. Thus, general practitioners (GPs) and specialised physicians still have to read document-based medical guidelines and decide among various options for managing common non-life-threatening conditions where the selection of the most appropriate therapeutic option for each individual patient can be a difficult task. This paper presents a simulation framework and computational test-bed, called V.A.F. Framework, for supporting simulations of clinical situations that boosted the integration between Health Level Seven (HL7) and Semantic Web technologies (OWL, SWRL, and OWL-S) to achieve content layer interoperability between online clinical cases and medical guidelines, and therefore, it proves that higher integration between EHRs and evidence-based medicine can be accomplished which could lead to a next generation of healthcare systems that provide more support to physicians and increase patients’ safety.     

Effect of breed type,housing and feeding system on performance of growing pigs managed under organic conditions

BACKGROUND: There is a need for information on the performance and carcass quality of pigs under different organic management systems. This study compared Duroc‐sired progeny from three maternal breed types when kept either at pasture or in housing with an outdoor run and offered ad libitum concentrate either alone or with fodder beet or grass/clover silage as additional forage. RESULTS: Liveweight gain, feed intake and the proportion of forages consumed did not differ between genotypes. Carcass fatness of progeny was lowest for a ‘modern’ genotype (Camborough 12) and highest for a ‘traditional’ purebred genotype (Saddleback), with a ‘crossbred traditional’ genotype (Saddleback × Duroc) being intermediate (11.4, 14.3 and 13.4 mm P₂ respectively, standard error of mean (SEM) 0.27, P < 0.001). With a cereal‐based concentrate available ad libitum, intake of forages was low (<2% of dry matter intake). Although growth rate did not differ between housing systems, daily feed intake was greater at pasture (2.47 vs 2.22 kg meal equivalent, SEM 0.05, P < 0.001), giving poorer feed efficiency (P < 0.01). Pastured animals consumed less additional forage and had a higher killing‐out % but similar carcass fatness. CONCLUSION: For organic pig production to be financially sustainable, disadvantages arising from the genotype and/or rearing system chosen need to be offset by a market premium for the pigs produced. Copyright © 2007 Society of Chemical Industry     

The eutrophication of Lake Champlain's northeastern arm: Insights from paleolimnological analyses

The trophic history of Lake Champlain's northeastern arm was assessed using a multi-proxy paleolimnological approach to provide sub-basin specific information for restoration planning. Sediment cores collected from Missisquoi Bay, St. Albans Bay, and the central Northeast Arm (Inland Sea) were analyzed for nutrients, organic carbon, carbon stable isotopes, biogenic silica, pigments, diatoms and soft algae microfossils. Results indicate that this arm of Lake Champlain was oligotrophic when Europeans arrived in 1609, and that clearance of > 70% of catchment forest cover had minor impact on algal production. Instead, eutrophication of St. Albans Bay was concurrent with sewer installation and expansion in early 20th century, and again with urban development in the 1960–70s. In contrast, less urbanized Missisquoi Bay remained mesotrophic until agriculture intensified after 1970. Interpretation of central Northeast Arm trophic history is complicated because road and railroad causeways built in 19th century reduced sediment input to this basin for several decades. Nevertheless, high surface-sediment concentrations of nutrients, pigments and organic matter along with replacement of Cyclotella bodanica with more eutrophic Fragilaria crotonensis suggest substantial eutrophication in deep as well as shallow water after 1970. We conclude that effective restoration of the northeastern arm is possible, but will require stringent control of animal and human wastes and reduced use of crop fertilizers.     

Tuning the electronic properties of graphene by hydrogenation in a plasma enhanced chemical vapor deposition reactor

Graphene films grown by chemical vapor deposition on copper foils were hydrogenated using commercially viable methods. Parameters such as plasma power, plasma frequency, and sample temperature were varied to determine the maximum possible hydrogenation without etching the film. The kinetic energy of the ions inside the plasma is critical, in that higher kinetic energy ions tend to etch the film while lower kinetic energy ions participate in the hydrogenation process. The film sheet resistance was shown to increase, while the hole mobility was shown to decrease with increasing hydrogenation. Variable temperature measurements demonstrate a transition from semi-metallic behavior for graphene to semiconducting behavior for hydrogenated graphene. Sheet resistance measurements as a function of temperature also suggest the emergence of a bandgap in the hydrogenated graphene films.     

Nature inspired quantile estimates of the Nakagami distribution

Telecommunication Systems - Nakagami-m distribution is utilized heavily in modelling multipath interferences in wireless networks. However, the closed form of the quantile function of the...     

Developments in Drag Bit Cutting of Rocks for Energy Infrastructure

The ground in which conduits are buried for transport of energy fluids such as oil and gas, as well as electric cables vary from loose soil to rocks of various mineralogies and degrees of cementation. A fraction of these terrains comprise hard but brittle rocky and require the application of innovative techniques in chamber and trench excavation. Drag bits, which could be conical or wedge-shaped, are usually attached to booms or cutting wheels of mechanical excavators at penetration angles (angle of attack) ranging from 48 to 54 degrees, and used as the primary force transfer mechanism to rocks. This paper is an analysis and summary of findings on parameters such as bit geometry, bit arrangement and forces, as well as rock resistance that impact upon energy expenditure on the excavation of trenches and chambers in rock.