2,903 research outputs found

    Modeling Weather Vulnerability Dynamically: Applications of Multiple Linear Regression to Weather Index Microinsurance

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    This paper offers a broad overview of the philanthropic goals of microinsurance — namely, to provide vulnerable populations with more self-sufficient and sustainable methods of coping with risk — and through this lens, analyses the applications of multiple linear regression in developing dynamic models for microinsurance. We explain the foundations of MLR (multiple linear regression), and then give two examples for how a simple multiple linear regression model can be adapted with a novel outcome variable (famine) and dependent variables (climate change related costs). Overall, a better understanding of MLR can lend to a better understanding of how microinsurance can scale its practices to new regions. Since this is an overview of the general practice of microinsurance, and not on any particular region or case study, we draw some insights on the practice of microinsurance modeling from some specific regions, such as the Bihar region of India, and illustrate generally how these insights can be used to improve microinsurance broadly

    A Kuramoto Model Approach to Predicting Chaotic Systems with Echo State Networks

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    An Echo State Network (ESN) with an activation function based on the Kuramoto model (Kuramoto ESN) is implemented, which can successfully predict the logistic map for a non-trivial number of time steps. The reservoir in the prediction stage exhibits binary dynamics when a good prediction is made, but the oscillators in the reservoir display a larger variability in states as the ESN’s prediction becomes worse. Analytical approaches to quantify how the Kuramoto ESN’s dynamics relate to its prediction are explored, as well as how the dynamics of the Kuramoto ESN relate to another widely studied physical model, the Ising model

    How are teachers using primary sources to meet Common Core literacy standards in English/Language Arts, Social Studies, and Science?

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    The implementation of Common Core standards has affected the instructional strategies of many teachers. Among other things, the standards require active student engagement, learning along a progressive sequence of higher proficiency, and heavy use of informational texts, especially primary sources. This study evaluates the impact that Common Core literacy standards have had on the proven primary source-based strategies and practices of five teachers

    Capitalisation et réutilisation avec des patrons dans un cadre d'Ingénierie Système Basée sur les Modèles (ISBM)

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    International audienceIn order to promote capitalization and reuse within a Model-Based System Engineering (MBSE) framework, this paper proposes a methodological approach that relies on the concept of pattern in order to encapsulate the know-how to be capitalized and reused. Indeed, formalizing and maintaining know-how within a company is essential in order to have a common base of "good practices" available to all engineering teams. To do this, it is necessary to undertake a capitalization process in order to encapsulate these practices. However, it is equally important to make this know-how available and to facilitate its reuse so that engineers can adapt it to their needs. The flexibility of patterns during reuse is an advantage that will contribute to the efficiency of MBSE and where engineering teams are able to rely on the company's know-how

    Influence of ionospheric perturbations in GPS time and frequency transfer

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    The stability of GPS time and frequency transfer is limited by the fact that GPS signals travel through the ionosphere. In high precision geodetic time transfer (i.e. based on precise modeling of code and carrier phase GPS data), the so-called ionosphere-free combination of the code and carrier phase measurements made on the two frequencies is used to remove the first-order ionospheric effect. In this paper, we investigate the impact of residual second- and third-order ionospheric effects on geodetic time transfer solutions i.e. remote atomic clock comparisons based on GPS measurements, using the ATOMIUM software developed at the Royal Observatory of Belgium (ROB). The impact of third-order ionospheric effects was shown to be negligible, while for second-order effects, the tests performed on different time links and at different epochs show a small impact of the order of some picoseconds, on a quiet day, and up to more than 10 picoseconds in case of high ionospheric activity. The geomagnetic storm of the 30th October 2003 is used to illustrate how space weather products are relevant to understand perturbations in geodetic time and frequency transfer.Comment: 25 pages, 10 eps figures, 1 table, accepted in Journal of Advances in Space Research, Special Issue "Recent advances in space weather monitoring, modelling and forecasting

    Enhanced sensitivity to ALDH1A3-dependent ferroptosis in TMZ-resistant glioblastoma cells

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    Temozolomide (TMZ) is standard treatment for glioblastoma (GBM); nonetheless, resistance and tumor recurrence are still major problems. In addition to its association with recurrent GBM and TMZ resistance, ALDH1A3 has a role in autophagy-dependent ferroptosis activation. In this study, we treated TMZ-resistant LN229 human GBM cells with the ferroptosis inducer RSL3. Remarkably, TMZ-resistant LN229 clones were also resistant to ferroptosis induction, although lipid peroxidation was induced by RSL3. By using Western blotting, we were able to determine that ALDH1A3 was down-regulated in TMZ-resistant LN229 cells. Most intriguingly, the cell viability results showed that only those clones that up-regulated ALDH1A3 after TMZ withdrawal became re-sensitized to ferroptosis induction. The recovery of ALDH1A3 expression appeared to be regulated by EGFR-dependent PI3K pathway activation since Akt was activated only in ALDH1A3 high clones. Blocking the EGFR signaling pathway with the EGFR inhibitor AG1498 decreased the expression of ALDH1A3. These findings shed light on the potential application of RSL3 in the treatment of glioblastoma relapse

    Random graph matching at Otter's threshold via counting chandeliers

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    We propose an efficient algorithm for graph matching based on similarity scores constructed from counting a certain family of weighted trees rooted at each vertex. For two Erd\H{o}s-R\'enyi graphs G(n,q)\mathcal{G}(n,q) whose edges are correlated through a latent vertex correspondence, we show that this algorithm correctly matches all but a vanishing fraction of the vertices with high probability, provided that nqnq\to\infty and the edge correlation coefficient ρ\rho satisfies ρ2>α0.338\rho^2>\alpha \approx 0.338, where α\alpha is Otter's tree-counting constant. Moreover, this almost exact matching can be made exact under an extra condition that is information-theoretically necessary. This is the first polynomial-time graph matching algorithm that succeeds at an explicit constant correlation and applies to both sparse and dense graphs. In comparison, previous methods either require ρ=1o(1)\rho=1-o(1) or are restricted to sparse graphs. The crux of the algorithm is a carefully curated family of rooted trees called chandeliers, which allows effective extraction of the graph correlation from the counts of the same tree while suppressing the undesirable correlation between those of different trees
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