4,016 research outputs found

    High Multiplicity Scheduling with Switching Costs for few Products

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    We study a variant of the single machine capacitated lot-sizing problem with sequence-dependent setup costs and product-dependent inventory costs. We are given a single machine and a set of products associated with a constant demand rate, maximum loading rate and holding costs per time unit. Switching production from one product to another incurs sequencing costs based on the two products. In this work, we show that by considering the high multiplicity setting and switching costs, even trivial cases of the corresponding "normal" counterparts become non-trivial in terms of size and complexity. We present solutions for one and two products.Comment: 10 pages (4 appendix), to be published in Operations Research Proceedings 201

    The Role of CDCA7 in Akt-mediated Myc-Dependent Apoptosis and Proliferation

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    CDCA7, or cell division cycle associated protein A7, was described in 2001 by Prescott and colleagues as a target of Myc-dependent transcriptional regulation (Prescott et al., 2001). We have identified CDCA7 as associating with the transcription factor Myc and is the target of phosphorylation by the prosurvival serine/threonine kinase Akt. Phosphorylation by Akt at threonine 163 disrupts CDCA7 association with Myc, promotes binding to 14-3-3 and sequestration in the cytoplasm. Coexpression of CDCA7 and Myc in fibroblasts potentiates Myc-dependent apoptosis upon serum withdrawal. In contrast, knockdown of CDCA7 by shRNA abrogated Myc-dependent apoptosis. Myc induced transformation of fibroblasts was reduced in the presence of CDCA7 and significantly inhibited by the expression of the non-Myc binding mutant (156-187) CDCA7. We have shown that CDCA7 enhances the activation of an E-box in a Myc-binding dependent manner. CDCA7 increases Myc occupancy of the proapoptotic BAX promoter, elevates BAX and Cyclin B1 mRNA levels while reducing p15INK4B mRNA levels. This data points to a novel mechanism which implicates Akt phosphorylation of CDCA7 as participating in the dual signal model of Myc of function and thus affecting Myc-dependent growth and transformation. In this study, we have also shown that expression of CDCA7 reduces proliferation rates and shifts cell cycle distribution towards G2/M phase and that phosphorylation of CDCA7 at T163 occurs strictly in G2/M. CDCA7 phosphorylated at threonine 163 colocalizes with the centrosomal protein marker -Tubulin and activated Akt (phospho-serine 473) in mitotic cells. Finally, we have shown that CDCA7 co-associates with monomers of itself which is dependent on amino acids 187-234, adding to the possible mechanisms by which CDCA7 function may be regulated

    Testing the Finch Hypothesis on Green OA Mandate Ineffectiveness

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    We have now tested the Finch Committee's Hypothesis that Green Open Access Mandates are ineffective in generating deposits in institutional repositories. With data from ROARMAP on institutional Green OA mandates and data from ROAR on institutional repositories, we show that deposit number and rate is significantly correlated with mandate strength (classified as 1-12): The stronger the mandate, the more the deposits. The strongest mandates generate deposit rates of 70%+ within 2 years of adoption, compared to the un-mandated deposit rate of 20%. The effect is already detectable at the national level, where the UK, which has the largest proportion of Green OA mandates, has a national OA rate of 35%, compared to the global baseline of 25%. The conclusion is that, contrary to the Finch Hypothesis, Green Open Access Mandates do have a major effect, and the stronger the mandate, the stronger the effect (the Liege ID/OA mandate, linked to research performance evaluation, being the strongest mandate model). RCUK (as well as all universities, research institutions and research funders worldwide) would be well advised to adopt the strongest Green OA mandates and to integrate institutional and funder mandates.Comment: 6 pages, 1 table, 4 figure

    Marking Drosophila suzukii (Diptera : Drosophilidae) with fluorescent dusts

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    The marking of Drosophila suzukii can be an important instrument for studying the ecology and behaviour of this economically important fruit pest, aiding the development of new Integrated Pest Management (IPM) tools or strategies. There is, however, a need for a cost-effective methodology that provides an easily detectable and stable mark. Whereas fluorescent pigment powders are often used in entomological research, the pigments (series, dyes), application techniques, or doses need to be evaluated for each studied species in terms of their efficacy and possible adverse effects on the performance of the insect. The effectiveness of different application techniques and dyes (RadGlo® TP-series) and their effect on the survival of adult D. suzukii were investigated in the laboratory. Furthermore, the influence of the marking on the behaviour of the flies was examined in laboratory trap assays (olfaction) and a field recapture study (general orientation). The persistence and detectability of the marks was evaluated both on living flies (for different application techniques) and dead flies under trapping/storage conditions. The use of fluorescent powders to mark D. suzukii flies yielded a clearly detectable and highly persistent mark, without any adverse effects on the survival and behaviour of the flies

    Systematic reviews of occupational therapy interventions: summarizing research evidence and highlighting the gaps

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    As services are commissioned based on effectiveness, occupational therapists are under pressure to demonstrate the efficacy of their interventions. Occupational therapists also need to know that the interventions they are providing are effective. Robertson et al (2013) demonstrated that the occupational therapy literature is important for clinicians and is an essential part of their practice. However, as more research is published, it can be increasingly time-consuming and confusing for clinicians to keep abreast of the current literature. Occupational therapy-related research may be published in different forms, in a range of locations, and be of varying methodological quality. Furthermore, readily available published studies that investigate occupational therapy efficacy may not be sufficiently powered, or may lack external validity, when applied to different clinical settings. When well conducted, systematic reviews provide a useful way of synthesizing and evaluating the evidence on a particular topic and, to some extent, provide a solution to this problem. This paper focuses upon reviews of randomized controlled trials, as these provide the highest quality of evidence on the question of a particular intervention’s effectiveness. The merits of reviews of qualitative studies are also considered, together with the possibility of combining more than one type of review

    Self-selected or mandated, open access increases citation impact for higher quality research

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    Articles whose authors make them Open Access (OA) by self-archiving them online are cited significantly more than articles accessible only to subscribers. Some have suggested that this "OA Advantage" may not be causal but just a self-selection bias, because authors preferentially make higher-quality articles OA. To test this we compared self-selective self-archiving with mandatory self-archiving for a sample of 27,197 articles published 2002-2006 in 1,984 journals. The OA Advantage proved just as high for both. Logistic regression showed that the advantage is independent of other correlates of citations (article age; journal impact factor; number of co-authors, references or pages; field; article type; country or institution) and greatest for the most highly cited articles. The OA Advantage is real, independent and causal, but skewed. Its size is indeed correlated with quality, just as citations themselves are (the top 20% of articles receive about 80% of all citations). The advantage is greater for the more citeable articles, not because of a quality bias from authors self-selecting what to make OA, but because of a quality advantage, from users self-selecting what to use and cite, freed by OA from the constraints of selective accessibility to subscribers only. [See accompanying RTF file for responses to feedback. Four PDF files provide Supplementary Analysis.

    Understanding Climate Change with Statistical Downscaling and Machine Learning

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    Machine learning methods have recently created high expectations in the climate modelling context in view of addressing climate change, but they are often considered as non-physics-based ‘black boxes’ that may not provide any understanding. However, in many ways, understanding seems indispensable to appropriately evaluate climate models and to build confidence in climate projections. Relying on two case studies, we compare how machine learning and standard statistical techniques affect our ability to understand the climate system. For that purpose, we put five evaluative criteria of understanding to work: intelligibility, representational accuracy, empirical accuracy, coherence with background knowledge, and assessment of the domain of validity. We argue that the two families of methods are part of the same continuum where these various criteria of understanding come in degrees, and that therefore machine learning methods do not necessarily constitute a radical departure from standard statistical tools, as far as understanding is concerned

    Jet-edge interaction tones

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    Motivated by the problem of jet-flap interaction noise, we study the tonal dynamics that occur when a sharp edge is placed in the hydrodynamic nearfield of an isothermal turbulent jet. We perform hydrodynamic and acoustic pressure measurements in order to characterise the tones as a function of Mach number and streamwise edge position. The distribution of spectral peaks observed, as a function of Mach number, cannot be explained using the usual edge-tone scenario, in which resonance is underpinned by coupling between downstream-travelling Kelvin-Helmholtz wavepackets and upstream-travelling sound waves. We show, rather, that the strongest tones are due to coupling between the former and upstream-travelling jet modes recently studied by Towne et al. (2017) and Schmidt et al. (2017). We also study the band-limited nature of the resonance, showing a high-frequency cut-off to be due to the frequency dependence of the upstream-travelling waves. At high Mach number these become evanescent above a certain frequency, whereas at low Mach number they become progressively trapped with increasing frequency, a consequence of which is their not being reflected in the nozzle plane. Additionally, a weaker, low-frequency, forced-resonance regime is identified that involves the same upstream travelling jet modes but that couple, in this instance, with downstream-travelling sound waves. It is suggested that the existence of two resonance regimes may be due to the non-modal nature of wavepacket dynamics at low-frequency.Comment: 21 pages, 15 figure

    Experimental study of the ageing of building stones exposed to sulfurous and nitric acid atmospheres

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    During the last few decades, due to remediation procedures, SO2 emissions in the atmosphere have decreased, unlike NOx. Air pollution has changed. Indeed, the aim of this research is to assess the effect of NOx and their interactions with SO2 on stones, particularly on limestones used in Champagne-Ardenne (France) during the restoration processes. Three French building limestones (Courville, Dom and Savonnières) and one reconstituted stone were exposed during 28 days to four strong acid atmospheres i.e. two H2SO3 solutions with different concentrations and two mixed atmospheres with different proportions of HNO3 and H2SO3. These tests produced an intensive acid attack on the stone, allowing the observation of short-term salt precipitation and the evolution of stone properties. Each day, one sample was removed from the acid atmosphere to measure the concentration of SO4(2-) and NO3(-) by ion-chromatography. The surface changes were assessed before and after the tests by 3D scanning and observations with electron microscopy. X-ray microtomography has been performed in the Centre for X-ray Tomography (UGCT) and the Department of Geology at Ghent University (Belgium) in order to observe the penetration of salts and the consequences in stones porosity. First observations showed that exposure to acid atmosphere, led to gypsum efflorescences. Obvious colour changes occurred in all tests. Salt crystallization entailed a change in the porous system, which was evidenced by 3D, mercury porosimetry and X-ray microtomography. Difference between weathered and fresh stone was highlighted by Ion chromatography analyses
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