107 research outputs found

    The effect of tegaserod in patients with distal intestinal obstruction syndrome

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    Clumped isotope thermometry in earthworm carbonates

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    Earthworm-secreted calcium carbonate can store carbon derived from the soil-atmosphere interface on geological timescales [1]. The mechanism of calcification [2,3,4] is well understood based on multiple years of research conducted both under controlled and natural conditions. We analysed carbonate granules produced by the earthworm Lumbricus terrestris cultured in variable pH and temperature for δ18O to establish thermometry [2]. The governing equation proposed for the thermometry differed from the inorganic calcite precipitation relationship, capturing the signature of kinetic processes during carbonate growth. We have now analysed the granules for clumped isotope thermometry. This provides an opportunity to understand the role of kinetic processes in governing the relationship of clumped isotope in the carbonate system. The clumped isotopic composition of these carbonates yields the following relationship with varying temperature: The linear regression relationship obtained in this study has a similar slope as seen in case of inorganic calcite [5] and otolith carbonate [6]. However, the intercept of the governing equation varied significantly denoting carbonate growth rate. The study presented here provides the first experimental results of clumped isotope composition on carbonates precipitated under monitored disequilibrium conditions and thus, enables quantification of growth rate dependency on clumping. The intercept of the linear regression relationship differs from the line proposed for inorganic calcite precipitation and thus introduces a new parameter to quantify the kinetic process. In this study replicate experiments were performed on carbonate granules generated at controlled temperature and with a knowledge of water isotopic compositio

    Mental Health Changes Over Time: a Longitudinal Perspective: Summary Report: Mental Health and Wellbeing Transition Study

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    Bryant, R., Lawrence-Wood, E., Baur, J., McFarlane, A., Hodson, S., Sadler, N., Benassi, H., Howell, S., Abraham, M., Iannos, M., Hansen, C., Searle, A., Van Hooff, M

    Mental Health Changes Over Time: a Longitudinal Perspective: Mental Health and Wellbeing Transition Study

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    Bryant, R., Lawrence-Wood, E., Baur, J., McFarlane, A., Hodson, S., Sadler, N., Benassi, H., Howell, S., Abraham, M., Iannos, M., Hansen, C., Searle, A., Van Hooff, M

    Effects of mineralogy, chemistry and physical properties of basalts on carbon capture potential and plant-nutrient element release via enhanced weathering

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    Mafic igneous rocks, such as basalt, are composed of abundant calcium- and magnesium-rich silicate minerals widely proposed to be suitable for scalable carbon dioxide removal (CDR) by enhanced rock weathering (ERW). Here, we report a detailed characterization of the mineralogy, chemistry, particle size and surface area of six mined basalts being used in large-scale ERW field trials. We use 1-D reactive transport modelling (RTM) of soil profile processes to simulate inorganic CDR potential via cation flux (Mg2+, Ca2+, K+ and Na+) and assess the release of the essential plant nutrients phosphorus (P) and potassium (K) for a typical clay-loam agricultural soil. The basalts are primarily composed of pyroxene and plagioclase feldspar (up to 71 wt%), with accessory olivine, quartz, glass and alkali feldspar. Mean crushed particle size varies by a factor of 10, owing to differences in the mining operations and grinding processes. RTM simulations, based on measured mineral composition and N2-gas BET specific surface area (SSA), yielded potential CDR values of between c. 1.3 and 8.5 t CO2 ha−1 after 15 years following a baseline application of 50 t ha−1 basalt. The RTM results are comparative for the range of inputs that are described and should be considered illustrative for an agricultural soil. Nevertheless, they indicate that increasing the surface area for slow-weathering basalts through energy intensive grinding prior to field application in an ERW context may not be warranted in terms of additional CDR gains. We developed a function to convert CDR based on widely available and easily measured rock chemistry measures to more realistic determinations based on mineralogy. When applied to a chemistry dataset for >1300 basalt analyses from 25 large igneous provinces, we simulated cumulative CDR potentials of up to c. 8.5 t CO2 ha−1 after 30 years of weathering, assuming a single application of basalt with a SSA of 1 m2 g−1. Our RTM simulations suggest that ERW with basalt releases sufficient phosphorus (P) to substitute for typical arable crop P-fertiliser usage in Europe and the USA offering potential to reduce demand for expensive rock-derived P

    New approaches using mass spectrometry to investigate changes to cytokinin and abscisic acid (ABA) concentrations in soil

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    Phytohormones such as cytokinins, abscisic acid (ABA) and auxins play a vital role in plant development and regulatory processes. Their role within the plant is a focus for much research, with studies using recent advances in mass spectrometry performance allowing the quantification of low levels of phytohormones extracted from plant tissues. Despite these advances, external factors influencing the production of phytohormones are less well studied. Here, a new approach is presented for the extraction of a range of phytohormones from plant growth media (soil and hydroponic solution), their identification using high mass accuracy mass spectrometry and subsequent quantification using multiple reaction monitoring (MRM). The ability to detect phytohormones in matrices other than plant tissue presents the opportunity to study further the influence of factors such as below ground organisms and soil bacteria on phytohormone production. This novel approach was therefore applied to the plant growth media from a series of experiments comparing plant growth in the presence and absence of earthworms. A small but significant increase in ABA concentration was observed in the presence of earthworms, increasing even further when plants were also present. This finding suggests that earthworms could stimulate plant ABA production. This experiment and its outcomes demonstrate the value of studying phytohormones outside plant tissue, and the potential value of further research in this area

    Multiple introductions and environmental factors affecting the establishment of invasive species on a volcanic island

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    Invasive species pose significant challenges to local biodiversity and ecosystem function, especially on islands. Understanding the factors affecting the establishment of invasive species and how these relate to their genetic background is crucial to improve our ability to manage biological invasions. Here, we performed a phylogeographic study of two cosmopolitan megascolecid earthworms of Asian origin: Amynthas gracilis and Amynthas corticis at 38 localities on S~ao Miguel Island in the Azores archipelago (Portugal). Samples from putative source populations in China, Taiwan, Malaysia, as well as ‘outlier’ populations in USA, Mexico, Brazil and Spain were also included, resulting in a total of 565 earthworms genotyped at the mitochondrial cytochrome oxidase I (COI) and 16S ribosomal RNA genes. Soils were characterised for elemental composition, water holding capacity, organic matter content, texture and pH, and some habitat features were recorded. Both species showed a wide distribution across S~ao Miguel and their abundances were negatively associated, suggesting spatial segregation/competition, with the parthenogenetic A. corticis being relatively more successful. The presence of multiple mitochondrial lineages within each species, one of them found exclusively in the Azores, suggests a complex invasion history. Environmental factors affected the establishment of the different lineages, with metal concentrations, topographical elevation and the degree of human influence being differently linked to their abundances. Lineage diversity was negatively correlated with metal concentrations. These results emphasise the importance of genetically characterising invasive species to better understand their invasion patterns
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