899 research outputs found

    Production of organic seeds: Status, Challenges and Prospects

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    General article on the requirements of organic agriculture for seed production. Beside this the organic agricultural system has other demands for organic seed since it does not use chemical control measures and uses natural fertilizers instead of chemical fertilizers. Research can offer an important contribution in the production of seed without diseases

    Eindrapportage BARAWING project (EETK99033) : de ontwikkeling van een competitief proces voor het verlengen van de houdbaarheid van voedselproducten met behulp van ultra-hoge druk : openbare rapportage

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    Deze rapportage beschrijft de resultaten die geboekt zijn binnen het BaraWing project (EETK99033). Dit project had als doelstelling het ontwikkelen van een proces en een testpilotscale hogedruk-apparaat voor het kosten-effectief produceren van voedingsmiddelen met een verlengde houdbaarheid bij kamertemperatuur met behulp van hogedruktechnologie (HPP). Het project was op te delen in een drietal hoofdactiviteiten, te weten a) technologie, b) veiligheid (microbiologie) en c) productkwalitei

    SU(2) Flux Distributions on Finite Lattices

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    We studied SU(2) flux distributions on four dimensional euclidean lattices with one dimension very large. By choosing the time direction appropriately we can study physics in two cases: one is finite volume in the zero temperature limit, another is finite temperature in the the intermediate to large volume limit. We found that for cases of beta > beta crit there is no intrinsic string formation. Our lattices with beta > beta crit belong to intermediate volume region, and the string tension in this region is due to finite volume effects. In large volumes we found evidence for intrinsic string formation.Comment: 21 pages text, 12 pages of postscript figure

    Systematic review: Do patient expectations influence treatment outcomes in total knee and total hip arthroplasty?

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    <p>Abstract</p> <p>Objective</p> <p>This systematic review aims to summarise all the available evidence related to the association between pre-operative patient expectations (outcome expectations, process expectations and self efficacy expectations) and 5 different treatment outcomes (overall improvement, pain, function, stiffness and satisfaction) in patients with total knee or total hip arthroplasty at three different follow-op periods (>6 weeks; >6 weeks- ≤6 months; >6 months).</p> <p>Methods</p> <p>English and Dutch language articles were identified through PubMed, EMBASE.com, PsycINFO, CINAHL and The Cochrane Library from inception to September 2012. Articles assessing the association between pre-operative patient expectations and treatment outcomes for TKA/THA in either adjusted or unadjusted analysis were included. Two reviewers, working independently, determined eligibility, rated methodological quality and extracted data on study design, population, expectation measurements, outcome measurements and strength of the associations. Methodological quality was rated by the same reviewers on a 19 item scale. The scores on the quality assessment were taken into account when drawing final conclusions.</p> <p>Results</p> <p>The search strategy generated 2252 unique references, 18 articles met inclusion criteria. Scores on the methodological quality assessment ranged between 6% and 79%. Great variety was seen in definitions and measurement methods of expectations. No significant associations were found between patient expectations and overall improvement, satisfaction and stiffness. Both significant positive and non-significant associations were found for the association between expectations and pain and function.</p> <p>Conclusions</p> <p>There was no consistency in the association between patients’ pre-operative expectations and treatment outcomes for TKA and THA indentified in this systematic review. There exists a need for a sound theoretical framework underlying the construct of ‘patient expectations’ and consistent use of valid measurement instruments to measure that construct in order to facilitate future research synthesis.</p

    Fitting a sum of exponentials to lattice correlation functions using a non-uniform prior

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    Excited states are extracted from lattice correlation functions using a non-uniform prior on the model parameters. Models for both a single exponential and a sum of exponentials are considered, as well as an alternate model for the orthogonalization of the correlation functions. Results from an analysis of torelon and glueball operators indicate the Bayesian methodology compares well with the usual interpretation of effective mass tables produced by a variational procedure. Applications of the methodology are discussed.Comment: 12 pages, 8 figures, 8 tables, major revision, final versio

    Back-flow ripples in troughs downstream of unit bars: Formation, preservation and value for interpreting flow conditions

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    Back-flow ripples are bedforms created within the lee-side eddy of a larger bedform with migration directions opposed or oblique to that of the host bedform. In the flume experiments described in this article, back-flow ripples formed in the trough downstream of a unit bar and changed with mean flow velocity; varying from small incipient back-flow ripples at low velocities, to well-formed back-flow ripples with greater velocity, to rapidly migrating transient back-flow ripples formed at the greatest velocities tested. In these experiments back-flow ripples formed at much lower mean back-flow velocities than predicted from previously published descriptions. This lower threshold mean back-flow velocity is attributed to the pattern of velocity variation within the lee-side eddy of the host bedform. The back-flow velocity variations are attributed to vortex shedding from the separation zone, wake flapping and increases in the size of, and turbulent intensity within, the flow separation eddy controlled by the passage of superimposed bedforms approaching the crest of the bar. Short duration high velocity packets, whatever their cause, may form back-flow ripples if they exceed the minimum bed shear stress for ripple generation for long enough or, if much faster, may wash them out. Variation in back-flow ripple cross-lamination has been observed in the rock record and, by comparison with flume observations, the preserved back-flow ripple morphology may be useful for interpreting formative flow and sediment transport dynamics

    Natuurlijke bosverjonging op moeilijke plekken; een kwestie van lange adem?

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    Bossen worden tegenwoordig hoofdzakelijk verjongd door gebruik te maken van natuurlijke bezaaiing. Bosbeheerders krijgen langzamerhand steeds meer ervaring met deze manier van werken. In het algemeen is redelijk bekend welke factoren van belang zijn voor het slagen of ontbreken van verjonging: licht (gatgrootte), bodem (type en opbouw), vegetatie (samenstelling en bedekking) en wilddruk. Maatregelen als lichting, grondbewerking en bescherming tegen wild kunnen in de regel dan ook voor voldoende verjonging zorgen. Toch komt het voor dat natuurlijke verjonging ontbreekt, zonder dat er een directe oorzaak is aan te wijzen. In een verkennend onderzoek keek Alterra wat hier aan de hand kan zijn

    Geochemical analysis of bulk marine sediment by Inductively Coupled Plasma–Atomic Emission Spectroscopy on board the JOIDES Resolution

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    Geochemical analyses on board the JOIDES Resolution have been enhanced with the addition of a Jobin-Yvon Ultrace inductively coupled plasma-atomic emission spectrometer (ICP-AES) as an upgrade from the previous X-ray fluorescence facility. During Leg 199, we sought to both challenge and utilize the capabilities of the ICP-AES in order to provide an extensive bulk-sediment geochemical database during the cruise. These near real-time analyses were then used to help characterize the recovered sedimentary sequences, calculate mass accumulation rates of the different sedimentary components, and assist with cruise and postcruise sampling requests. The general procedures, sample preparation techniques, and basic protocol for ICP-AES analyses on board ship are outlined by Murray et al. (2000) in Ocean Drilling Program Tech Note, 29. We expand on those concepts and offer suggestions for ICP-AES methodology, calibration by standard reference materials, data reduction procedures, and challenges that are specific to the analysis of bulk-sediment samples. During Leg 199, we employed an extensive bulk-sediment analytical program of ~600 samples of varying lithologies, thereby providing several opportunities for refinement of techniques. We also discuss some difficulties and challenges that were faced and suggest how to alleviate such occurrences for sedimentary chemical analyses during future legs

    Dynamic splitting of a Bose-Einstein Condensate

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    We study the dynamic process of splitting a condensate by raising a potential barrier in the center of a harmonic trap. We use a two-mode model to describe the phase coherence between the two halves of the condensate. Furthermore, we explicitly consider the spatial dependence of the mode funtions, which varies depending on the potential barrier. This allows to get the tunneling coupling between the two wells and the on-site energy as a function of the barrier height. Moreover we can get some insight on the collective modes which are excited by raising the barrier. We describe the internal and external degrees of freedom by variational ansatz. We distinguish the possible regimes as a function of the characteristic parameters of the problem and identify the adiabaticity conditions.Comment: 17 pages, 8 figure
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