A multi-pass one way method to include turning waves and multiples

Conventional one way migration methods exclude turning waves and multiples. We propose an algorithm that uses multiple passes to extend the one way method to efficiently include these wavepaths. A comparison of the images produced by the regular one way algorithm, RTM, and the new method, shows that this new method can significantly improve the image in regions of interest, and in certain situations may even provide more useful information than RTM. The runtime is demonstrated to be in between that of regular one way and RTM, while the physical memory required is considerably lower than that of RTM

Reverse Time Migration in the presence of known sharp interfaces

We propose using the forward propagated source wave to create synthetic receiver data on the surfaces of the computational domain where real receiver data is not available as a means of exploiting known information about reflector locations in Reverse Time Migration. The inclusion of synthetic boundary data can make true amplitude imaging possible, and reduce the artifacts associated with the inclusion of multiples. Here, we describe the new method, present synthetic examples, and propose an appropriate imaging condition

Efficient Use of Phosphorus in Temperate Grassland Systems

Phosphorus (P) fertilisers are important for high production in many grassland systems. However, there are increasing environmental, economic and strategic issues associated with using P, which is a non-renewable and “effectively finite” global resource. We review the P balance of temperate pastures to identify the factors that contribute to inefficient P use and discuss ways to improve P use efficiency. The most immediate gains can be made by ensuring that pastures are not over-fertilised. Plants with low critical P requirements, particularly as a result of better root foraging, will be important. Root traits such as fine roots (root diameter), branching, length and root hairs, and mycorrhizal associations all contribute to improved root foraging; some are amenable to plant breeding. Plants that can “mine” sparingly-available P in soils by producing organic anions and phosphatases are also needed; as are innovations in fertiliser technology. Soil microorganisms play a crucial role in P acquisition by pastures but are not particularly amenable to management. Selection of pasture species for root characteristics offers a more realistic approach to improving P efficiency but progress, to date, has been minimal. Traditional plant breeding, augmented by marker assisted selection and interspecific hybridisation, are likely to be necessary for progress. Inevitably, P efficient pastures will be achieved most effectively by a combination of plant genetic, fertiliser innovation and management responses. Success will bring economic and environmental benefits from reduced P fertiliser use, with consequent benefits for global resource and food security

Identification of scyllo-inositol phosphates in soil by solution phosphorus-31 nuclear magnetic resonance spectroscopy

A large proportion of the organic P in soils can occur as scyllo-inositol phosphates. These compounds are rarely detected elsewhere in nature and remain poorly understood, partly because conventional procedures for their determination are lengthy and erroneous. We report a straightforward procedure for the determination of scyllo-inositol phosphates in soil extracts using solution 31P nuclear magnetic resonance (NMR) spectroscopy. Solution 31P NMR chemical shifts of a range of synthetic scyllo-inositol phosphate esters were determined in alkaline solution. Of these, only the signal corresponding to scyllo-inositol hexakisphosphate at approximately 4.2 ppm was identified in soil NaOH–EDTA extracts, constituting between 6.5 and 9.8% of the NaOH–EDTA extracted P. This signal has been previously assigned to choline phosphate, but we confirmed it to be an inositol phosphate using hypobromite oxidation, a procedure that destroys all organic matter except inositol phosphates. Lower order scyllo-inositol phosphate esters were not identified in the extracts studied here, and literature reports suggest that they probably occur in insufficient concentrations to be detected by this procedure. The identification of scyllo-inositol hexakisphosphate in soils and other environmental samples will allow its quantification in a range of environments, and facilitate research into the origins and function of this enigmatic compound

Epidrug mediated re-expression of miRNA targeting the HMGA transcripts in pituitary cells

Transgenic mice overexpressing the high mobility group A (HMGA) genes, Hmga1 or Hmga2 develop pituitary tumours and their overexpression is also a frequent finding in human pituitary adenomas. In some cases, increased expression of HMGA2 but not that of HMGA1 is consequent to genetic perturbations. However, recent studies show that down-regulation of microRNA (miRNA), that contemporaneously target the HMGA1 and HMGA2 transcripts, are associated with their overexpression. In a cohort of primary pituitary adenoma we determine the impact of epigenetic modifications on the expression of HMGA-targeting miRNA. For these miRNAs, chromatin immunoprecipitations showed that transcript down-regulation is correlated with histone tail modifications associated with condensed silenced genes. The functional impact of epigenetic modification on miRNA expression was determined in the rodent pituitary cell line, GH3. In these cells, histone tail, miRNA-associated, modifications were similar to those apparent in human adenoma and likely account for their repression. Indeed, challenge of GH3 cells with the epidrugs, zebularine and TSA, led to enrichment of the histone modification, H3K9Ac, associated with active genes, and depletion of the modification, H3K27me3, associated with silent genes and re-expression of HMGA-targeting miRNA. Moreover, epidrugs challenges were also associated with a concomitant decrease in hmga1 transcript and protein levels and concurrent increase in bmp-4 expression. These findings show that the inverse relationship between HMGA expression and targeting miRNA is reversible through epidrug interventions. In addition to showing a mechanistic link between epigenetic modifications and miRNA expression these findings underscore their potential as therapeutic targets in this and other diseases

Autologous chondrocyte implantation for cartilage repair: monitoring its success by magnetic resonance imaging and histology

Autologous chondrocyte implantation is being used increasingly for the treatment of cartilage defects. In spite of this, there has been a paucity of objective, standardised assessment of the outcome and quality of repair tissue formed. We have investigated patients treated with autologous chondrocyte implantation (ACI), some in conjunction with mosaicplasty, and developed objective, semiquantitative scoring schemes to monitor the repair tissue using MRI and histology. Results indicate repair tissue to be on average 2.5 mm thick. It was of varying morphology ranging from predominantly hyaline in 22% of biopsy specimens, mixed in 48%, through to predominantly fibrocartilage, in 30%, apparently improving with increasing time postgraft. Repair tissue was well integrated with the host tissue in all aspects viewed. MRI scans provide a useful assessment of properties of the whole graft area and adjacent tissue and is a noninvasive technique for long-term follow-up. It correlated with histology (P = 0.02) in patients treated with ACI alone

HvALMT1 from barley is involved in the transport of organic anions

Members of the ALMT gene family contribute to the Al3+ resistance of several plant species by facilitating malate efflux from root cells. The first member of this family to be cloned and characterized, TaALMT1, is responsible for most of the natural variation of Al3+ resistance in wheat. The current study describes the isolation and characterization of HvALMT1, the barley gene with the greatest sequence similarity to TaALMT1. HvALMT1 is located on chromosome 2H which has not been associated with Al3+ resistance in barley. The relatively low levels of HvALMT1 expression detected in root and shoot tissues were independent of external aluminium or phosphorus supply. Transgenic barley plants transformed with the HvALMT1 promoter fused to the green fluorescent protein (GFP) indicated that expression of HvALMT1 was relatively high in stomatal guard cells and in root tissues containing expanding cells. GFP fused to the C-terminus of the full HvALMT1 protein localized to the plasma membrane and motile vesicles within the cytoplasm. HvALMT1 conferred both inward and outward currents when expressed in Xenopus laevis oocytes that were bathed in a range of anions including malate. Both malate uptake and efflux were confirmed in oocyte assays using [14C]malate as a radiotracer. It is suggested that HvALMT1 functions as an anion channel to facilitate organic anion transport in stomatal function and expanding cells

Archaeal ammonia oxidizers respond to soil factors at smaller spatial scales than the overall archaeal community does in a high Arctic polar oasis

Archaea are ubiquitous and highly abundant in Arctic soils. Because of their oligotrophic nature, archaea play an important role in biogeochemical processes in nutrient-limited Arctic soils. With the existing knowledge of high archaeal abundance and functional potential in Arctic soils, this study employed terminal restriction fragment length polymorphism (t-RFLP) profiling and geostatistical analysis to explore spatial dependency and edaphic determinants of the overall archaeal (ARC) and ammonia-oxidizing archaeal (AOA) communities in a high Arctic polar oasis soil. ARC communities were spatially dependent at the 2–5 m scale (P < 0.05), whereas AOA communities were dependent at the �1 m scale (P < 0.0001). Soil moisture, pH, and total carbon content were key edaphic factors driving both the ARC and AOA community structure. However, AOA evenness had simultaneous correlations with dissolved organic nitrogen and mineral nitrogen, indicating a possible niche differentiation for AOA in which dry mineral and wet organic soil microsites support different AOA genotypes. Richness, evenness, and diversity indices of both ARC and AOA communities showed high spatial dependency along the landscape and resembled scaling of edaphic factors. The spatial link between archaeal community structure and soil resources found in this study has implications for predictive understanding of archaea-driven processes in polar oases