198 research outputs found

    Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normal metal bilayers

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    Spin pumping is a mechanism that generates spin currents from ferromagnetic resonance (FMR) over macroscopic interfacial areas, thereby enabling sensitive detection of the inverse spin Hall effect that transforms spin into charge currents in non-magnetic conductors. Here we study the spin-pumping-induced voltages due to the inverse spin Hall effect in permalloy/normal metal bilayers integrated into coplanar waveguides for different normal metals and as a function of angle of the applied magnetic field direction, as well as microwave frequency and power. We find good agreement between experimental data and a theoretical model that includes contributions from anisotropic magnetoresistance (AMR) and inverse spin Hall effect (ISHE). The analysis provides consistent results over a wide range of experimental conditions as long as the precise magnetization trajectory is taken into account. The spin Hall angles for Pt, Pd, Au and Mo were determined with high precision to be 0.013±0.0020.013\pm0.002, 0.0064±0.0010.0064\pm0.001, 0.0035±0.00030.0035\pm0.0003 and 0.0005±0.0001-0.0005\pm0.0001, respectively.Comment: 11 page

    Quantitative lipidomic analysis of Ascaris suum

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    Ascaris is a soil-transmitted nematode that causes ascariasis, a neglected tropical disease affecting predominantly children and adolescents in the tropics and subtropics. Approximately 0.8 billion people are affected worldwide, equating to 0.86 million disability-adjusted life-years (DALYs). Exploring the molecular biology of Ascaris is important to gain a better understanding of the host-parasite interactions and disease processes, and supports the development of novel interventions. Although advances have been made in the genomics, transcriptomics and proteomics of Ascaris, its lipidome has received very limited attention. Lipidomics is an important sub-discipline of systems biology, focused on exploring lipids profiles in tissues and cells, and elucidating their biological and metabolic roles. Here, we characterised the lipidomes of key developmental stages and organ systems of Ascaris of porcine origin via high throughput LC-MS/MS. In total, > 500 lipid species belonging to 18 lipid classes within three lipid categories were identified and quantified-in precise molar amounts in relation to the dry weight of worm material-in different developmental stages/sexes and organ systems. The results showed substantial differences in the composition and abundance of lipids with key roles in cellular processes and functions (e.g. energy storage regulation and membrane structure) among distinct stages and among organ systems, likely reflecting differing demands for lipids, depending on stage of growth and development as well as the need to adapt to constantly changing environments within and outside of the host animal. This work provides the first step toward understanding the biology of lipids in Ascaris, with possibilities to work toward designing new interventions against ascariasis. Author summary Lipids are of vital importance in the biology of parasitic worms, particularly in relation to cellular membranes, energy storage, and intra- and intercellular signalling. However, very little is known about the biology of lipids in parasitic nematodes. Using a high-throughput LC-MS/MS approach, we characterised the first global lipidome for Ascaris. We investigated the lipid composition and abundance in key developmental stages/sexes as well as the organ systems of Ascaris. We observed substantial differences in lipid composition and abundance among these stages/sexes and among the organ systems studied. The findings provide a basis to start to understand lipid biology in Ascaris, with possible implications for developing new interventions against ascariasis

    Inter- and intraspecific variation in mangrove carbon fraction and wood specific gravity in Gazi Bay, Kenya

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    The tropical mangrove ecosystem harbors great potential for carbon offsetting schemes because of their exceptionally high carbon sequestration potential. These cannot only generate an income for local communities by financially compensating for the non‐exploitation of protected or replanted stands, but also simultaneously reduce emissions due to forest degradation and deforestation, thereby helping to counteract the global threat on these forests. As carbon is directly monetized through offsetting carbon emissions, accurate species‐specific estimation of carbon content in trees is essential and reduces the propagation of errors generated by accounting uncertainties. Accordingly, this study assessed variation in both carbon fraction and wood specific gravity among and within the 10 mangrove species occurring in Gazi Bay, Kenya. Significant interspecific differences were found with values ranging from 45.8% (Avicennia marina) to 49.8% (Ceriops tagal) for carbon fraction and from 0.58 (Sonneratia alba) to 0.93 (Pemphis acidula) for wood specific gravity. The influence of environmental factors (soil salinity, stand density, and elevation a.s.l. as a proxy for multiple interrelated conditions) was investigated, but only elevation a.s.l. appeared to have a species‐specific though moderate influence only on carbon fraction. Significant differences in carbon fraction and wood specific gravity were found between stem, aerial roots, and branches of Rhizophora mucronata. In contrast, no significant differences in carbon fraction were found among different stem tissues of A. marina, C. tagal and R. mucronata, the Bay's most abundant species. These results provide insight in carbon content variation, confirming the importance of considering species‐specific or even site‐specific values of carbon fraction and wood specific gravity, thereby rendering future carbon accounting more accurate

    Seasonally timed treatment programs for Ascaris lumbricoides to increase impact - an investigation using mathematical models

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    There is clear empirical evidence that environmental conditions can influence Ascaris spp. free-living stage development and host reinfection, but the impact of these differences on human infections, and interventions to control them, is variable. A new model framework reflecting four key stages of the A. lumbricoides life cycle, incorporating the effects of rainfall and temperature, is used to describe the level of infection in the human population alongside the environmental egg dynamics. Using data from South Korea and Nigeria, we conclude that settings with extreme fluctuations in rainfall or temperature could exhibit strong seasonal transmission patterns that may be partially masked by the longevity of A. lumbricoides infections in hosts; we go on to demonstrate how seasonally timed mass drug administration (MDA) could impact the outcomes of control strategies. For the South Korean setting the results predict a comparative decrease of 74.5% in mean worm days (the number of days the average individual spend infected with worms across a 12 month period) between the best and worst MDA timings after four years of annual treatment. The model found no significant seasonal effect on MDA in the Nigerian setting due to a narrower annual temperature range and no rainfall dependence. Our results suggest that seasonal variation in egg survival and maturation could be exploited to maximise the impact of MDA in certain settings
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