737 research outputs found

    When more does not necessarily mean better: Health-related illfare comparisons with non-monotone wellbeing relationships

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    Most welfare studies assume that wellbeing is monotonically related to the variables used for the analysis. While this assumption is reasonable for many dimensions of wellbeing like income, education, or empowerment, there are some cases where it is definitively not relevant, in particular with respect to health. For instance, health status is often proxied using the Body Mass Index (BMI). Low BMI values can capture undernutrition or the incidence of severe illness, yet a high BMI is neither desirable as it indicates obesity. Usual illfare indices derived from poverty measurement are then not appropriate. This paper proposes illfare indices that are consistent with some situations of non-monotonic wellbeing relationships and examines the partial orderings of different distributions derived from various classes of illfare indices. An illustration is provided for child health as proxied by a weight-for-age indicator using DHS data for Bangladesh, Colombia and Egypt during the last few decades

    Leaf segmentation and tracking using probabilistic parametric active contours

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    Active contours or snakes are widely used for segmentation and tracking. These techniques require the minimization of an energy function, which is generally a linear combination of a data fit term and a regularization term. This energy function can be adjusted to exploit the intrinsic object and image features. This can be done by changing the weighting parameters of the data fit and regularization term. There is, however, no rule to set these parameters optimally for a given application. This results in trial and error parameter estimation. In this paper, we propose a new active contour framework defined using probability theory. With this new technique there is no need for ad hoc parameter setting, since it uses probability distributions, which can be learned from a given training dataset

    Fresnel diffraction in an interferometer: application to MATISSE

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    While doing optical study in an instrument similar to the interferometers dedicated to the Very Large Telescope (VLT), we have to take care of the pupil and focus conjugations. Modules with artificial sources are designed to simulate the stellar beams, in terms of collimation and pupil location. They constitute alignment and calibration tools. In this paper, we present such a module in which the pupil mask is not located in a collimated beam thus introducing Fresnel diffraction. We study the instrumental contrast taking into account the spatial coherence of the source, and the pupil diffraction. The considered example is MATISSE, but this study can apply to any other instrument concerned with Fresnel diffraction.Comment: 8 pages- to appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 201

    Vehicle Trajectories from Unlabeled Data through Iterative Plane Registration

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    One of the most complex aspects of autonomous driving concerns understanding the surrounding environment. In particular, the interest falls on detecting which agents are populating it and how they are moving. The capacity to predict how these may act in the near future would allow an autonomous vehicle to safely plan its trajectory, minimizing the risks for itself and others. In this work we propose an automatic trajectory annotation method exploiting an Iterative Plane Registration algorithm based on homographies and semantic segmentations. The output of our technique is a set of holistic trajectories (past-present-future) paired with a single image context, useful to train a predictive model

    Dynamic Group Diffie-Hellman Key Exchange under Standard Assumptions

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    Authenticated Diffie-Hellman key exchange allows two principals communicating over a public network, and each holding public /private keys, to agree on a shared secret value. In this paper we study the natural extension of this cryptographic problem to a group of principals. We begin from existing formal security models and refine them to incorporate major missing details (e.g., strong-corruption and concurrent sessions). Within this model we define the execution of a protocol for authenticated dynamic group Diffie-Hellman and show that it is provably secure under the decisional Diffie-Hellman assumption. Our security result holds in the standard model and thus provides better security guarantees than previously published results in the random oracle model

    Yeast Ssd1 is a non-enzymatic member of the RNase II family with an alternative RNA recognition interface

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    Ssd1, a conserved fungal RNA-binding protein, is important in stress responses, cell division and virulence. Ssd1 is closely related to Dis3L2 of the RNase II family of nucleases, but lacks catalytic activity and likely suppresses translation of bound mRNAs. Previous studies identified RNA motifs enriched in Ssd1-associated transcripts, yet the sequence requirements for Ssd1 binding are not defined. Here, we identify precise binding sites of Ssd1 on RNA using in vivo cross-linking and cDNA analysis. These sites are enriched in 5′ untranslated regions of a subset of mRNAs encoding cell wall proteins. We identified a conserved bipartite motif that binds Ssd1 with high affinity in vitro. Active RNase II enzymes have a characteristic, internal RNA binding path; the Ssd1 crystal structure at 1.9 Å resolution shows that remnants of regulatory sequences block this path. Instead, RNA binding activity has relocated to a conserved patch on the surface of the protein. Structure-guided mutations of this surface prevent Ssd1 from binding RNA in vitro and phenocopy Ssd1 deletion in vivo. These studies provide a new framework for understanding the function of a pleiotropic post-transcriptional regulator of gene expression and give insights into the evolution of regulatory and binding elements in the RNase II family

    First AMBER/VLTI observations of hot massive stars

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    AMBER is the first near infrared focal instrument of the VLTI. It combines three telescopes and produces spectrally resolved interferometric measures. This paper discusses some preliminary results of the first scientific observations of AMBER with three Unit Telescopes at medium (1500) and high (12000) spectral resolution. We derive a first set of constraints on the structure of the circumstellar material around the Wolf Rayet Gamma2 Velorum and the LBV Eta Carinae
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