18,384 research outputs found

    Assessing the poverty impacts of remittances with alternative counterfactual income estimates

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    We estimate the impacts of remittances on poverty with survey data from Tonga, a poor Pacific island country highly dependent on international migrants’ remittances. The sensitivity of poverty impacts to estimation method is tested using two methods to estimate migrants’ counterfactual incomes; bootstrap prediction with self-selection testing and propensity score matching. We find consistency between the two methods, both showing a substantial reduction in the incidence and depth of poverty with migration and remittances. With further robustness checks there is strong evidence that the poorest households benefit from migrants’ remittances, and that increased migration opportunities can contribute to poverty alleviation.

    Rejuvenation and Memory in model Spin Glasses in 3 and 4 dimensions

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    We numerically study aging for the Edwards-Anderson Model in 3 and 4 dimensions using different temperature-change protocols. In D=3, time scales a thousand times larger than in previous work are reached with the SUE machine. Deviations from cumulative aging are observed in the non monotonic time behavior of the coherence length. Memory and rejuvenation effects are found in a temperature-cycle protocol, revealed by vanishing effective waiting times. Similar effects are reported for the D=3$site-diluted ferromagnetic Ising model (without chaos). However, rejuvenation is reduced if off-equilibrium corrections to the fluctuation-dissipation theorem are considered. Memory and rejuvenation are quantitatively describable in terms of the growth regime of the spin-glass coherence length.Comment: Extended protocols. Accepted in Phys. Rev. B. 10 postscript figure

    Role of growth factors in the pathogenesis of tissue fibrosis in systemic sclerosis.

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    The most severe clinical and pathologic manifestations of systemic sclerosis (SSc) are the result of a fibrotic process characterized by the excessive and often progressive deposition of collagen and other connective tissue macromolecules in skin and numerous internal organs. The mechanisms involved in the initiation and progression of the remarkable fibrotic process in SSc remain largely unknown. Extensive recent studies have indicated that a variety of polypeptide growth factors play a crucial role in this process. The most commonly implicated growth factors include transforming growth factor beta (TGF-β), connective tissue growth factor (CTGF), platelet derived growth factor (PDGF), and vascular endothelial growth factor (VEGF). Here, the experimental evidence supporting the participation of various growth factors in the pathogenesis of the fibrotic process in SSc and the molecular mechanisms involved will be reviewed

    Dividing the Ontology Alignment Task with Semantic Embeddings and Logic-based Modules

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    Large ontologies still pose serious challenges to state-of-the-art ontology alignment systems. In this paper we present an approach that combines a neural embedding model and logic-based modules to accurately divide an input ontology matching task into smaller and more tractable matching (sub)tasks. We have conducted a comprehensive evaluation using the datasets of the Ontology Alignment Evaluation Initiative. The results are encouraging and suggest that the proposed method is adequate in practice and can be integrated within the workflow of systems unable to cope with very large ontologies

    A Mixed-Motives Model of Private Transfers with Subjectively-Assessed Recipient Need: Evidence from a Poor, Transfer-Dependent Economy

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    We extend the mixed-motives model of transfer derivatives developed by Cox et al (2004) introducing subjectively-assessed recipient need in place of an absolute income threshold at which the donor’s dominant motive switches from altruism to exchange. This refinement provides a theoretically justifiable threshold amenable to empirical measurement. We test the extended model with customized survey data from Tonga and find evidence consistent with Cox et al in support of altruism for households below the threshold, but, we also find a positive, exchange-motivated relationship for those above the threshold. We conclude that either crowding-out or crowding-in of private transfers can occur when the recipient’s welfare improves, depending on the household’s pre-transfer welfare level. This also has implications for the distributional impact of private transfers and could explain why poverty reduction can be accompanied by increased income inequality.

    Assembling Di- and Multiatomic Si Clusters in Graphene via Electron Beam Manipulation

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    We demonstrate assembly of di-, tri- and tetrameric Si clusters on the graphene surface using sub-atomically focused electron beam of a scanning transmission electron microscope. Here, an electron beam is used to introduce Si substitutional defects and defect clusters in graphene with spatial control of a few nanometers, and enable controlled motion of Si atoms. The Si substitutional defects are then further manipulated to form dimers, trimers and more complex structures. The dynamics of a beam induced atomic scale chemical process is captured in a time-series of images at atomic resolution. These studies suggest that control of the e-beam induced local processes offers the next step toward atom-by-atom nanofabrication and provides an enabling tool for study of atomic scale chemistry in 2D materials

    Helicopter Wake Encounters in the Context of RECAT-EU

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    This work presents a first attempt to apply the RECAT-EU (European Wake Turbulence Categorisation and Separation Minima) methodology of fixed-wing aircraft separation to helicopters. The approach is based on a classification of helicopters in categories using their rotor diameter and weight combined with wake comparisons between different classes of fixed-wing aircraft and helicopters. Where necessary the upset caused by a wake encounter to a simple helicopter model is used to establish safe separation distances. The work is based on a very limited amount of data for wake strengths but shows that the principles of the RECAT-EU methodology are directly applicable to helicopters at least for landing and take-off. This research calls for further measurements of helicopter wakes with modern methods so that the suggested separation distances can be further ascertained and ultimately refined allowing for better and safer integration of fixed and rotary-wing traffic at airports
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