668 research outputs found

    Nitrate Leaching in the Meadows of Western Lithuania with Different Liming and Fertilisation Levels

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    Investigations of recent decades in the Baltic region including Lithuania showed that intensive liming and mineral fertilisation are the main factors achieving maximum crop yield. However, this farming method had a negative effect on soil quality and nutrient leaching became more intensive. Grassland fertilisation with nitrogen (N) helps plants to assimilate P, K, Ca, Na, but it may increase leaching of nutrients (Niczyporuk & Jankowska, 1995). Nitrate leaching is usually low from grasslands, primarily due to their long growing season compared to arable crops (Korsaeth et.al., 2003). The objective of this research was to determine the effect of liming and N fertilisation on lysimeter water contamination by nitrate (NO3)

    Food Prices and the Multiplier Effect of Export Policy

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    This paper studies the relationship between export policy and food prices. We show that, when individuals are loss averse, food exporters may use trade policy to shield the domestic economy from large price shocks. This creates a complementarity between the price of food in international markets and export policy. Specifically, unilateral actions by exporting countries give rise to a "multiplier effect": when a shock in the international food market drives up (down) its price, governments respond by imposing export restrictions (subsidies), thus exacerbating the initial shock and soliciting further export activism. We test this theory with a new dataset that comprises monthly information on trade measures across 125 countries and 29 food products for the period 2008-10, finding evidence of a multiplier effect. Global restrictions in a product (i.e. the share of international trade covered by export restrictions) are positively correlated with the probability of imposing a new export restriction on that product, especially for staple foods. Large exporters are found to be more reactive to restrictive measures, suggesting that the multiplier effect is mostly driven by this group. Finally, we estimate that a 1 per cent surge in global restrictions increased international food prices by 1.1 per cent on average during 2008-10. These findings contribute to inform the broader debate on the proper regulation of export policy within the multilateral trading system

    QTLs for early vigor of tropical maize

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    A strong photosynthetic performance and rapid leaf development, are important indicators of vigorous early growth. The aim of this study was to (1) evaluate the tropical maize (Zea mays L.) inbred lines CML444 and SC-Malawi for their photosynthetic performance at different growth stages and (2) assess quantitative trait loci (QTL) of photosynthesis-related traits in their 236 recombinant inbred lines at the heterotrophic growth stage. CML444 had a higher leaf chlorophyll (SPAD) content than SC-Malawi. Ten QTLs were found for the quantum efficiency of photosystem II (ΊPSII; four), SPAD (three) and the specific leaf area (SLA; three). The relevance of seedling QTLs for ΊPSII, SPAD and SLA for yield formation is emphasized by seven collocations (bins 5.01, 7.03, 8.05) with QTLs for kernel number and grain yield under field conditions. QTLs for SPAD at the V2 and at the reproductive stage did not collocate, indicating differences in the genetic control of SPAD at different growth stages. Knowing which loci affect SLA, SPAD and ΊPSII simultaneously and which do not will help to optimize light harvest by the canop

    QTLs for the elongation of axile and lateral roots of maize in response to low water potential

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    Changes in root architecture and the maintenance of root growth in drying soil are key traits for the adaptation of maize (Zea mays L.) to drought environments. The goal of this study was to map quantitative trait loci (QTLs) for root growth and its response to dehydration in a population of 208 recombinant inbred lines from the International Maize and Wheat Improvement Center (CIMMYT). The parents, Ac7643 and Ac7729/TZSRW, are known to be drought-tolerant and drought-sensitive, respectively. Roots were grown in pouches under well-watered conditions or at low water potential induced by the osmolyte polyethylene glycol (PEG 8000). Axile root length (L Ax) increased linearly, while lateral root length (L Lat) increased exponentially over time. Thirteen QTLs were identified for six seedling traits: elongation rates of axile roots (ERAx), the rate constant of lateral root elongation (k Lat), the final respective lengths (L Ax and L Lat), and the ratios k Lat/ERAx and L Lat/L Ax. While QTLs for lateral root traits were constitutively expressed, most QTLs for axile root traits responded to water stress. For axile roots, common QTLs existed for ERAx and L Ax. Quantitative trait loci for the elongation rates of axile roots responded more clearly to water stress compared to root length. Two major QTLs were detected: a QTL for general vigor in bin 2.02, affecting most of the traits, and a QTL for the constitutive increase in k Lat and k Lat/ERAx in bins 6.04-6.05. The latter co-located with a major QTL for the anthesis-silking interval (ASI) reported in published field experiments, suggesting an involvement of root morphology in drought tolerance. Rapid seedling tests are feasible for elucidating the genetic response of root growth to low water potential. Some loci may even have pleiotropic effects on yield-related traits under drought stres

    A Methodology for the Diagnostic of Aircraft Engine Based on Indicators Aggregation

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    Aircraft engine manufacturers collect large amount of engine related data during flights. These data are used to detect anomalies in the engines in order to help companies optimize their maintenance costs. This article introduces and studies a generic methodology that allows one to build automatic early signs of anomaly detection in a way that is understandable by human operators who make the final maintenance decision. The main idea of the method is to generate a very large number of binary indicators based on parametric anomaly scores designed by experts, complemented by simple aggregations of those scores. The best indicators are selected via a classical forward scheme, leading to a much reduced number of indicators that are tuned to a data set. We illustrate the interest of the method on simulated data which contain realistic early signs of anomalies.Comment: Proceedings of the 14th Industrial Conference, ICDM 2014, St. Petersburg : Russian Federation (2014

    Discrete and continuous models of linear elasticity: history and connections

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    This paper tracks the development of lattice models that aim to describe linear elasticity of solids and the field equations of which converge asymptotically toward those of isotropic continua, thus showing the connection between discrete and continuum. In 1759, Lagrange used lattice strings/rod dynamics to show the link between the mixed differential-difference equation of a one-dimensional (1D) lattice and the partial differential equation of the associated continuum. A consistent three-dimensional (3D) generalization of this model was given much later: Poincaré and Voigt reconciled the molecular and the continuum approaches at the end of the nineteenth century, but only in 1912 Born and von Kármán presented the mixed differential- difference equations of discrete isotropic elasticity. Their model is a 3D generalization of Lagrange’s 1D lattice and considers longitudinal, diagonal and shear elastic springs among particles, so the associated continuum is characterized by three elastic constants. Born and von Kármán proved that the lattice equations converge to Navier’s partial differential ones asymptotically, thus being a formulation of continuous elasticity in terms of spatial finite differences, as for Lagrange’s 1D lattice. Neglecting shear springs in Born–Kármán’s lattice equals to Navier’s assumption of pure central forces among molecules: in the limit, the lattice behaves as a one-parameter isotropic solid (“rari-constant” theory: equal Lamé parameters, or, equivalently, Poisson’s ratio υ = 1/4). Hrennikoff and McHenry revisited the lattice approach with pure central interactions using a plane truss; the equivalent Born–Kármán’s lattice in plane stress in the limit tends to a continuum with Poisson’s ratio υ = 1/3. Contrary to McHenry–Hrennikoff’s truss, Born–Kármán’s lattice leads to a “free” Poisson’s ratio bounded by its “limit’ bound (υ = 1/4 for plane strain or 3D elasticity; υ = 1/3 for plane stress elasticity). Unfortunately, Born–Kármán’s lattice model does not comply with rotational invariance principle, for non-central forces. The consistent generalization of Lagrange’s lattice in 3D was achieved only by Gazis et al. considering an elastic energy that depends on changes in both lengths and angles of the lattice. An alternative consistent three-parameter elastic lattice is the Hrennikoff’s, with additional structure in the cell. We also discuss the capability of nonlocal continuous models to bridge the gap between continuum isotropic elasticity at low frequencies and lattice anisotropic elasticity at high frequencies

    Differential expression and co-expression gene networks reveal candidate biomarkers of boar taint in non-castrated pigs

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    Abstract Boar taint (BT) is an offensive odour or taste observed in pork from a proportion of non-castrated male pigs. Surgical castration is effective in avoiding BT, but animal welfare issues have created an incentive for alternatives such as genomic selection. In order to find candidate biomarkers, gene expression profiles were analysed from tissues of non-castrated pigs grouped by their genetic merit of BT. Differential expression analysis revealed substantial changes with log-transformed fold changes of liver and testis from −3.39 to 2.96 and −7.51 to 3.53, respectively. Co-expression network analysis revealed one module with a correlation of −0.27 in liver and three modules with correlations of 0.31, −0.44 and −0.49 in testis. Differential expression and co-expression analysis revealed candidate biomarkers with varying biological functions: phase I (COQ3, COX6C, CYP2J2, CYP2B6, ACOX2) and phase II metabolism (GSTO1, GSR, FMO3) of skatole and androstenone in liver to steroidgenesis (HSD17B7, HSD17B8, CYP27A1), regulation of steroidgenesis (STARD10, CYB5R3) and GnRH signalling (MAPK3, MAP2K2, MAP3K2) in testis. Overrepresented pathways included “Ribosome”, “Protein export” and “Oxidative phosphorylation” in liver and “Steroid hormone biosynthesis” and “Gap junction” in testis. Future work should evaluate the biomarkers in large populations to ensure their usefulness in genomic selection programs

    The radiation of cynodonts and the ground plan of mammalian morphological diversity

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    Cynodont therapsids diversified extensively after the Permo-Triassic mass extinction event, and gave rise to mammals in the Jurassic. We use an enlarged and revised dataset of discrete skeletal characters to build a new phylogeny for all main cynodont clades from the Late Permian to the Early Jurassic, and we analyse models of morphological diversification in the group. Basal taxa and epicynodonts are paraphyletic relative to eucynodonts, and the latter are divided into cynognathians and probainognathians, with tritylodonts and mammals forming sister groups. Disparity analyses reveal a heterogeneous distribution of cynodonts in a morphospace derived from cladistic characters. Pairwise morphological distances are weakly correlated with phylogenetic distances. Comparisons of disparity by groups and through time are non-significant, especially after the data are rarefied. A disparity peak occurs in the Early/Middle Triassic, after which period the mean disparity fluctuates little. Cynognathians were characterized by high evolutionary rates and high diversity early in their history, whereas probainognathian rates were low. Community structure may have been instrumental in imposing different rates on the two clades

    Exploring the Quality of Life of People in North Eastern and Southern Thailand.

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    The assumption that development brings not only material prosperity but also a better overall quality of life lies at the heart of the development project. Against this, critics assert that development can undermine social cohesion and threaten cultural integrity. Rarely, however, is the impact of development on wellbeing rigourously analysed using empirical data. This is what the Wellbeing in Developing Countries Group at the University of Bath aims to do drawing on fieldwork carried out in four developing countries, which addresses the themes of resources, needs, agency and structure, and subjective Quality of life (QoL). The first phase of the QoL research in Thailand aimed to explore the categories and components of quality of life for people from different backgrounds and locations with the aim of developing methods for QoL assessment in the third phase of the WeD QoL research. The study presents data obtained from rural and peri-urban sites in Southern and Northeastern Thailand (two villages in Songkhla and three in Khon Kaen, Mukdaharn, and Roi-et). Participants were divided into six groups by gender and age, and were divided again by religion (Buddhist and Muslim) and wealth status in the South. Data collection was conducted between October and December 2004 using focus group discussions, semi-structured interviews, and the Person Generated Index. Content analysis was used for data analysis. The use of a qualitative approach enabled the gathering of empirical data that reflects the sources of difficulty and happiness in the lives of participants. Respondents identified 26 aspects to their quality of life, including family relations, health and longevity, income and having money, jobs, housing, education, debt, and so on. The results reveal clear similarities and differences in the role of traditions, religious beliefs, and values in the lives of people living in remote rural or peri-urban areas in Northeastern and Southern Thailand. These results, together with the findings from Peru, Ethiopia, and Bangladesh, will inform the rest of the WeD research and be used to develop measures to assess the quality of life of people living in developing countries

    Fabricating a Structured Single-Atom Catalyst via High-Resolution Photopolymerization 3D Printing

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    This study introduces a novel solution to the design of structured catalysts, integrating single-piece 3D printing with single-atom catalysis. Structured catalysts are widely employed in industrial processes, as they provide optimal mass and heat transfer, leading to a more efficient use of catalytic materials. They are conventionally prepared using ceramic or metallic bodies, which are then washcoated and impregnated with catalytically active layers. However, this approach may lead to adhesion issues of the latter. By employing photopolymerization printing, a stable and active single-atom catalyst is directly shaped into a stand-alone, single-piece structured material. The battery of characterization methods employed in the present study confirms the uniform distribution of catalytically active species and the structural integrity of the material. Computational fluid dynamics simulations are applied to demonstrate enhanced momentum transfer and light distribution within the structured body. The materials are finally evaluated in the continuous-flow photocatalytic oxidation of benzyl alcohol to benzaldehyde, a relevant reaction to prepare biomass-derived building blocks. The innovative approach reported herein to manufacture a structured single-atom catalyst circumvents the complexities of traditional synthetic methods, offering scalability and efficiency improvements, and highlights the transformative role of 3D printing in catalysis engineering to revolutionize catalysts’ design
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