19,029 research outputs found

    Intrapulse x-ray parametric amplification in high-order-harmonic generation

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    We demonstrate strong-field-driven impulsive XUV-x-ray parametric amplification (IXPA) processes in high-order harmonic generation at the single-atom level by using ab initio calculations. We consider the example of Li+ ions exposed simultaneously to an intense IR pulse and a weak 200-as XUV-x-ray pulse with central photon energies varying from 90 to 400 eV. We determine optimal parameter ranges and the precise delays between the IR and the XUV-x-ray pulses for IXPA to occur. The present results might be a guide to achieve exponential growth of the XUV-x-ray signal in tabletop XUV-x-ray lasers.Peer ReviewedPostprint (author's final draft

    The effects of bicarbonate and mineral surfaces on uranium immobilization under anaerobic conditions

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    For four decades, from 1940 through 1980, the U.S. Department of Energy (DoE) extensively mined and processed uranium at various sites. As a result, widespread uranium contamination exists in subsurface sediments and aquifers. In subsurface environments, uranium primarily exists as U(VI) or U(IV), oxidized and reduced species, respectively. U(VI) is highly soluble and toxic, U(IV), while relatively toxic, is insoluble which greatly reduces its exposure pathways. We seek to examine the role of ferric iron on U(VI) reduction by adsorbing U(VI) onto ferric and non-ferric mineral surfaces in the presence of a reductant. Further, we seek to understand the role that NaHCO3, a natural groundwater buffer, has in the reductive geochemical transformations of U(VI) adsorbed on ferric and non-ferric mineral surfaces. Bench top studies were performed using 100 uM U(VI) and the reductant AHQDS, in the presence and absence of Fe-Gel (amorphous ferric oxyhydroxide) and gamma-Al2O3. In the presence of a HEPES buffer at pH 8, results demonstrate direct homogeneous reduction in several hours in the absence of Fe-Gel or gamma-Al2O3, and reduction within a 48-hour period in the presence Fe-Gel or gamma-Al2O3. While adsorbed to both ferric and non-ferric mineral surfaces, U(VI) reduction is inhibited. U(VI) reduction in the presence of NaHCO3 buffer also inhibits U(VI) reduction

    From Government to Governance: Small and Medium Enterprise Policy Development in New Zealand 1978 to 2008 : A thesis presented in partial fulfillment of the requirements of the degree of Doctor of Philosophy in Management at Massey University Wellington, New Zealand

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    Widespread recognition of the importance of SMEs and their contribution to the economy means that successive New Zealand governments, between 1978 and 2008, placed increasing emphasis on SME policy. SME policy developed over time from being an incidental outcome of general economic policy to targeting particular SME sectors and engaging stakeholders and SMEs themselves in this process. Few studies have examined how this policy process evolved, and this research addresses the deficit by providing a critical overview of New Zealand SME policy development between 1978 and 2008. It examines how SME policy in New Zealand developed over the thirty-year period, identifying the main influences (or inputs) in SME policy development, and what policy outputs were set in place. The approach draws on business history methods and utilises primary sources, such as archival documentation, media reports, contemporary SME research and interviews with participants who played key roles in the development of SME policy. Historical analysis facilitates the examination of the range and diversity of SME policies used over the period under review. The research provides an overview of the external domestic and international influences that shaped and informed SME policymaking processes, and the challenges of meeting the often contradictory nature of government objectives in the socio-economic domain. It shows how over time the social cohesion policy objective, although still underplayed, became more pronounced. Principal inputs into SME policy are found to be the economic and stakeholder contexts, both set in an overall institutional environment. Whereas in the early period the economic context was the primary input into SME policy, by 2008 the input of stakeholders (researchers, academics, industry associations, chambers of commerce, among others) was more significant. The research concludes that, as attitudes and economic thinking changed, so too did SME policy and the way policy developed. A shift to the entrepreneurship paradigm contributed to a fundamental recalibration of approaches – from direct SME support such as the Small Business Agency, to predominantly indirect contextual support. SMEs were no longer considered ‘little big businesses’ but complex and heterogeneous enterprises and the role of stakeholders became more noticeable. Understanding how SME policy has altered over three decades assists researchers, policymakers and other SME stakeholders by contextualizing the evolution of thinking and approaches. As an outcome of this study, stakeholders will have additional clarity to help them contribute to the ongoing development of New Zealand SME policy

    Growth Models, Development Planning, and Implementation in the Philippines

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    Has Philippine development planning benefited from the wisdom, if any, of economic growth theory? In this article, the author discusses the key question of whether development planning in the Philippines has worked in delivering growth. He investigates the theoretical foundations of national development plans since independence in 1946 for indications and reflections of economic theories of growth prevailing at the time, the quality of the plans themselves and their impact.economic growth models, economic growth theory, development planning

    Growth Models, Development Planning, and Implementation in the Philippines

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    Has Philippine development planning benefited from the wisdom, if any, of economic growth theory? In this article, the author discusses the key question of whether development planning in the Philippines has worked in delivering growth. He investigates the theoretical foundations of national development plans since independence in 1946 for indications and reflections of economic theories of growth prevailing at the time, the quality of the plans themselves and their impact.economic growth models, economic growth theory, development planning

    Differentiation Between Ripening Stages of Iberian Dry-Cured Ham According to the Free Amino Acids Content

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    In this paper, the differentiation of three ripening stages, postsalting, drying, and cellar, of Iberian dry-cured ham has been carried out according to their free amino acids contents. Eighteen L-amino acids, alanine, 2-aminobutanoic acid, aspartic acid, cysteine, glutamine, glycine, histidine, hydroxyproline, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tyrosine, and valine have been determined by gas chromatography with derivatization with N,O-bis(trimethylsilyl)-trifluoroacetamide. Gas chromatography-mass spectrometry was used to confirm the presence of the eighteen amino acids in the ham samples, and gas chromatography using a DB-17HT column and flame ionization detector was used for quantitative determination. Extraction with a mixture methanol-acetonitrile has been carried out, achieving recoveries in the range 52-164%. Methimazole was used as internal standard. Limits of detection ranged between 7.0 and 611.7 mg·kg-1. Free amino acids have been used as chemical descriptors to differentiate between the ripening stages. Principal component analysis and linear discriminant analysis have been used as chemometric techniques, achieving complete differentiation between the ripening stages. Alanine, tyrosine, glutamine, proline, 2-aminobutanoic acid, cysteine, and valine were the most differentiating amino acids.Junta de Andalucía the project P09-AGR-0478

    The duration of the outdoor rearing period of pigs influences Iberian ham characteristics

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    peer-reviewedThe effect of outdoor rearing duration (75 v 50 days) and rearing system (outdoor v indoor based systems) of Iberian pigs on the chemical composition (fatty acid composition of fat and intramuscular fat, moisture, salt, pigment concentrations and water activity of lean meat), the instrumental colour (CIEL*a*b* system) and the sensory characteristics (descriptive analysis) of dry-cured hams were investigated. The fatty acid composition of subcutaneous fat was weakly affected by outdoor rearing duration, but greatly affected by rearing system with the indoor hams showing larger proportion of saturated fatty acids than outdoor rearing. Rearing system also affected L* of subcut aneous fat (the indoor hams were lighter than the outdoor ones). The instrumental colour of lean was only affected by outdoor rearing duration (scores for a* and its derived variables were larger in the long-outdoor group than in the short-outdoor one). The effect of outdoor rearing duration on the sensory characteristics of Iberian hams was marked, 13 sensory characteristics being affected. Among them, odour intensity, flavour intensity, and flavour persistence were greater in the long-outdoor hams than in the short-outdoor ones, whereas these characteristics were not affected by rearing system. However, rearing system also had a large effect influencing 12 sensory characteristics
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