678 research outputs found

    Deriving soil hydraulic parameters in a high spatial resolution for a heterogeneous agricultural field-site

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    Providing information about the structure of the subsurface plays an important role for setting up soil hydraulic models, which are in turn an important prerequisite for ecosystem modelling approaches. Because soils often show a high within-field heterogeneity in terms of texture, stone content, and bulk density, they may also exhibit a wide range of hydraulic properties in the field. During water stress periods and especially on agricultural fields, which are characterized by uniform vegetation, the occurrence of a within-field heterogeneity in terms of soil hydraulic properties can be observed as it affects the different water status of the plants. The patterns of visible plant water stress and areas of low apparent electrical conductivities measured by electromagnetic induction measurements (EMI) often coincide, for e.g. within sugar beet cropped fields. Such observations have also been made beforehand at the current study site; an agricultural field (2.7 ha) that is situated in an area developed by fluvial processes. To account for this, the current approach included a sampling campaign on a field with 70 drilling locations for texture and organic carbon analyses. Furthermore, soil water retention functions and saturated hydraulic conductivity were determined at 20 sampling locations. Our approach for ecosystem modelling is based on 4 m² grid cells over the whole study site. To consider within-field heterogeneity in the ecosystem model, soil hydraulic parameters were predicted for each grid cell, whereby different approaches such as spatial interpolation, Miller-Miller scaling, and the use of pedotransfer functions were taken into account to identify the most appropriate approach

    Pollinator convergence and the nature of species' boundaries in sympatric Sardinian Ophrys (Orchidaceae)

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    Background and Aims In the sexually deceptive Ophrys genus, species isolation is generally considered ethological and occurs via different, specific pollinators, but there are cases in which Ophrys species can share a common pollinator and differ in pollen placement on the body of the insect. In that condition, species are expected to be reproductively isolated through a pre-mating mechanical barrier. Here, the relative contribution of pre- vs. post-mating barriers to gene flow among two Ophrys species that share a common pollinator and can occur in sympatry is studied. Methods A natural hybrid zone on Sardinia between O. iricolor and O. incubacea, sharing Andrena morio as pollinator, was investigated by analysing floral traits involved in pollinator attraction as odour extracts both for non-active and active compounds and for labellum morphology. The genetic architecture of the hybrid zone was also estimated with amplified fragment length polymorphism (AFLP) markers, and pollination fitness and seed set of both parental species and their hybrids in the sympatric zone were estimated by controlled crosses. Key Results Although hybrids were intermediate between parental species in labellum morphology and non-active odour compounds, both parental species and hybrids produced a similar odour bouquet for active compounds. However, hybrids produced significantly lower fruit and seed set than parental species, and the genetic architecture of the hybrid zone suggests that they were mostly first-generation hybrids. Conclusions The two parental species hybridize in sympatry as a consequence of pollinator overlap and weak mechanical isolation, but post-zygotic barriers reduce hybrid frequency and fitness, and prevent extensive introgression. These results highlight a significant contribution of late post-mating barriers, such as chromosomal divergence, for maintaining reproductive isolation, in an orchid group for which pre-mating barriers are often considered predominan

    Electrodeposition of adherent submicron to micron thick manganese dioxide films with optimized current collector interface for 3D Li-ion electrodes

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    Three-dimensional (3D) configuration of high-performance energy storage devices has been the subject of ongoing investigations targeting their integration in autonomous microelectronic systems. In this study we demonstrate a route toward the realization of high capacity cathode material for 3D thin-film lithium-ion (Li-ion) batteries. Electrolytic manganese dioxide (EMD) film can be applied as a Li-ion intercalation electrode upon its conversion to lithium manganese dioxide (LiMn2O4 or LMO) by solid-state reaction. The main challenges of depositing thicker EMD film directly on the current collector often lay in achieving a good film adhesion and preventing oxidation of non-noble current collectors such as TiN, Ni. To improve the adhesion of the EMD films we modify the surface of the current collector by means of thin-film or seed layer coatings, which also prevent the oxidation of the underlying current collector substrate during the anodic deposition process. As a result submicron to micron thick EMD films with good adhesion were deposited on various current collectors. The acidity of the electrolyte solutions was varied depending on the type of the surface coating or current collector used. The mechanism of the EMD film growth and morphology on different substrates was examined. Compatibility of the proposed current collector interface modification for the electrodeposition of conformal thick EMD films on high-aspect ratio microstructures was demonstrated. A method of EMD film conversion to LMO at low-temperature on different substrates was shown as the path toward their application in 3D Li-ion batteries

    A new version of the HBSC Family Affluence Scale - FAS III: Scottish qualitative findings from the International FAS Development Study

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    A critical review of the Family Affluence Scale (FAS) concluded that FAS II was no longer discriminatory within very rich or very poor countries, where a very high or a very low proportion of children were categorised as high FAS or low FAS respectively (Currie et al. 2008). The review concluded that a new version of FAS - FAS III - should be developed to take into account current trends in family consumption patterns across the European region, the US and Canada. In 2012, the FAS Development and Validation Study was conducted in eight countries - Denmark, Greenland, Italy, Norway, Poland, Romania, Slovakia and Scotland. This paper describes the Scottish qualitative findings from this study. The Scottish qualitative fieldwork comprising cognitive interviews and focus groups sampled from 11, 13 and 15 year-old participants from 18 of the most- and least- economically deprived schools. These qualitative results were used to inform the final FAS III recommendations.Publisher PDFPeer reviewe

    Internal Insulation of Historic Buildings: A Stochastic Approach to Life Cycle Costing Within RIBuild EU Project

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    The application of internal insulation is a widespread and effective solution for energy renovation of historic buildings.However, it entails quite high installation costs and a certain risk of failure due to moisture-related problems. A probabilistic risk assessment of both hygrothermal performance and life cycle costs can be used to address internal insulation issue, in order to support riskmanagement and decisionmaking. This paper presents the application of a probabilistic approach to Life Cycle Costing developed within the EU project RIBuild (Robust Internal Thermal Insulation of Historic Buildings), to five internal insulations solutions widely used in Italy. The method provides estimates of the range and likelihood of global costs and payback periods, also considering alternative energy and future economic scenarios. The impact of insulation systems service life on global costs is also addressed, in order to highlight the possible connection of the method to a stochastic estimation of insulation systems durability based on hygrothermal and damage assessments

    biochemical bases for a widespread tolerance of cyanobacteria to the phosphonate herbicide glyphosate

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    Possible non-target effects of the widely used, non-selective herbicide glyphosate were examined in six cyanobacterial strains, and the basis of their resistance was investigated. All cyanobacteria showed a remarkable tolerance to the herbicide up to millimolar levels. Two of them were found to possess an insensitive form of glyphosate target, the shikimate pathway enzyme 5-enol-pyruvyl-shikimate-3-phosphate synthase. Four strains were able to use the phosphonate as the only phosphorus source. Low uptake rates were measured only under phosphorus deprivation. Experimental evidence for glyphosate metabolism was also obtained in strains apparently unable to use the phosphonate. Results suggest that various mechanisms may concur in providing cyanobacterial strains with herbicide tolerance. The data also account for their widespread ability to metabolize the phosphonate. However, such a capability seems limited by low cell permeability to glyphosate, and is rapidly repressed when inorganic phosphate is available

    Efficacy of OptiphosTM phytase on mineral digestibility in diets for breeding sows: effect during pregnancy an lactation

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    Phosphorus in most diets for breeding sows is digested for 20 to 40%, thus leading to a relatively high amount of P in the manure. To enhance the P digestibility in diets for both lactating and gestating sows, two separate experiments were carried out to study the efficacy of OptiphosTM phytase derived from E. coli and produced by the yeast Pichia pastoris. Thirty crossbred gestating sows and 36 lactating sows were used in these studies. Five treatments were imposed on the gestating sows: 1) a negative control treatment, based on a low-P diet without added feed phosphate and microbial phytase. Diets in Treatments 2, 3 and 4 were the same as the negative control diet, except that an amount of Optiphos phytase of 125, 250 and 1,000 U.kg-1 of diet, respectively, was added. Treatment 5 was the positive control diet, based on the same diet with 1.0 g of added digestible P.kg-1 of diet from monocalcium phosphate. The lactating sows of Treatments 1 to 6 received a negative control diet, the same diet with an amount of OptiphosTM phytase of 125, 250, 500 and 1000 U.kg-1 of diet and a positive control diet supplemented with 1.5 g of digestible P.kg-1, respectively. The negative control diets were different in ingredient composition because of the different nutrient requirements between lactating and gestating sows. The ratio between Ca and digestible P was kept at 2.8:1 and 3.3:1 for the lactating and gestating diets, respectively, with a minimum of 5.0 g Ca.kg-1. Feeding level of the sows was according to Dutch recommendations. Six sows per treatment were used. The lactating sows received the diets from 2 weeks before farrowing until weaning of the piglets at 4 weeks of age and the gestating sows from day 49 to day 100 of pregnancy. Faecal samples of the sows were collected by rectal stimulation on days 14 and 21 post-farrowing, and on days 70 and 100 of pregnancy. Digestibility coefficients of dry matter, organic matter, ash and the minerals under investigation were calculated using Cr2O3 as an indigestible marker. In addition, several performance characteristics were registered. Phosphorus digestibility was clearly enhanced by the addition of microbial phytase to the lactating sow diets, as was the digestibility of ash, Ca, Na, K, Cu, and Zn. In the gestating sows only digestibility of P was significantly enhanced by microbial phytase. In both gestating and lactating sows the lowest level of phytase addition (125 U.kg-1 of diet) already resulted in the highest response in P digestibility without further improvement at higher phytase inclusion levels. The additional amount of digestible P absorbed with a phytase supplement of 125 or more U.kg-1 in lactating sows was on average 0.90 g/kg. An average amount of 0.36 and 0.67 g digestible P.kg-1 was generated in gestating sows at day 70 and day 100 of pregnancy by this phytase inclusion, respectively. No signs of any adverse effect of phytase on sow or piglet health and performance were observed. OptiphosTM phytase was already highly effective at a dose of 125 U.kg-1 of diet. Possible reasons for the lack of further improvement of P digestibility at higher doses of phytase are discussed. If feed phosphates are (partly) replaced by 125 U phytase.kg-1 of diet, then P excretion can be reduced by 0.85 kg.sow-1.year-1

    Multiscale entropy-based analyses of soil transect data

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    A deeper understanding of the spatial variability of soil properties and the relationships between them is needed to scale up measured soil properties and to model soil processes. The object of this study was to describe the spatial scaling properties of a set of soil physical properties measured on a common 1024-m transect across arable fields at Silsoe in Bedfordshire, east-central England. Properties studied were volumetric water content ({theta}), total porosity ({pi}), pH, and N2O flux. We applied entropy as a means of quantifying the scaling behavior of each transect. Finally, we examined the spatial intrascaling behavior of the correlations between {theta} and the other soil variables. Relative entropies and increments in relative entropy calculated for {theta}, {pi}, and pH showed maximum structure at the 128-m scale, while N2O flux presented a more complex scale dependency at large and small scales. The intrascale-dependent correlation between {theta} and {pi} was negative at small scales up to 8 m. The rest of the intrascale-dependent correlation functions between {theta} with N2O fluxes and pH were in agreement with previous studies. These techniques allow research on scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scale

    Prediction of Anisotropic Single-Dirac-Cones in Bi1−x{}_{1-x}Sbx{}_{x} Thin Films

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    The electronic band structures of Bi1−x{}_{1-x}Sbx{}_{x} thin films can be varied as a function of temperature, pressure, stoichiometry, film thickness and growth orientation. We here show how different anisotropic single-Dirac-cones can be constructed in a Bi1−x{}_{1-x}Sbx{}_{x} thin film for different applications or research purposes. For predicting anisotropic single-Dirac-cones, we have developed an iterative-two-dimensional-two-band model to get a consistent inverse-effective-mass-tensor and band-gap, which can be used in a general two-dimensional system that has a non-parabolic dispersion relation as in a Bi1−x{}_{1-x}Sbx{}_{x} thin film system
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