LIBOPT - An environment for testing solvers on heterogeneous collections of problems - Version 1.0

The Libopt environment is both a methodology and a set of tools that can be used for testing, comparing, and profiling solvers on problems belonging to various collections. These collections can be heterogeneous in the sense that their problems can have common features that differ from one collection to the other. Libopt brings a unified view on this composite world by offering, for example, the possibility to run any solver on any problem compatible with it, using the same Unix/Linux command. The environment also provides tools for comparing the results obtained by solvers on a specified set of problems. Most of the scripts going with the Libopt environment have been written in Perl

Crop production and global food security in relation to climate variation: an empirical analysis

The challenge of meeting increasing global food demand is amplified by climate change. Crop yield is vulnerable to extreme conditions, including heatwaves, droughts and downpours, leading to widespread concern about negative effects of climate change on food security. This thesis describes a novel empirical analysis of total production, yields and harvested area data for three major crops (wheat, maize and soybean), using a unique, global, gridded agricultural time-series data set. Trend analysis is applied to changes in production, yield and harvested area of these three crops. Machine learning is used to quantify their responses to climate. A new methodology is introduced to identify “shocks”. Results show a more complex dynamics of agricultural production than is suggested by current liter- ature. Large changes in regional production, driven by harvested area rather than yield, have been driven by policy shifts. A large “killing degree-day” sum depresses yields for some regions and crops, but enhances them in others. Heat deficits can be as deleterious as heatwaves. Shocks can be negative or positive. Production variability has increased, but major negative shocks have been few, and have not become more frequent. Production shocks have been caused as often by changes in harvested area as in yield. These findings do not support a universal negative effect of climate change on crop production. More- over, stable global food supplies will not be assured by maximizing yields. It is equally important that farmers in different countries and environments grow a variety of crops. Climate-related risk is currently concentrated in the most productive baskets, exposing the global food supply to avoidably high risk. Increasing frequencies of climate extremes in the main producing areas only make such shocks more likely. Various measures that are not directly related to climate would help to make global food supplies more resilient.Open Acces

Generalized Voltage-based State-Space Modelling of Modular Multilevel Converters with Constant Equilibrium in Steady-State

This paper demonstrates that the sum and difference of the upper and lower arm voltages are suitable variables for deriving a generalized state-space model of an MMC which settles at a constant equilibrium in steady-state operation, while including the internal voltage and current dynamics. The presented modelling approach allows for separating the multiple frequency components appearing within the MMC as a first step of the model derivation, to avoid variables containing multiple frequency components in steady-state. On this basis, it is shown that Park transformations at three different frequencies ($+\omega$, $-2\omega$ and $+3\omega$) can be applied for deriving a model formulation where all state-variables will settle at constant values in steady-state, corresponding to an equilibrium point of the model. The resulting model is accurately capturing the internal current and voltage dynamics of a three-phase MMC, independently from how the control system is implemented. The main advantage of this model formulation is that it can be linearised, allowing for eigenvalue-based analysis of the MMC dynamics. Furthermore, the model can be utilized for control system design by multi-variable methods requiring any stable equilibrium to be defined by a fixed operating point. Time-domain simulations in comparison to an established average model of the MMC, as well as results from a detailed simulation model of an MMC with 400 sub-modules per arm, are presented as verification of the validity and accuracy of the developed model

Antibiotic resistance : from pig to meat

Pork meat is in high demand worldwide and this is expected to increase. Pork is often raised in intensive conditions, which is conducive to the spread of infectious diseases. Vaccines, antibiotics, and other biosafety measures help mitigate the impact of infectious diseases. However, bacterial strains resistant to antibiotics are more and more frequently found in pig farms, animals, and the environment. It is now recognized that a holistic perspective is needed to sustainably fight antibiotic resistance, and that an integrated One Health approach is essential. With this in mind, this review tackles antibiotic resistance throughout the pork raising process, including their microbiome; many factors of their environment (agricultural workers, farms, rivers, etc.); and an overview of the impact of antibiotic resistance on pork meat, which is the end product available to consumers. Antibiotic resistance, while a natural process, is a public health concern. If we react, and act, collectively, it is expected to be, at least partially, reversible with judicious antibiotic usage and the development of innovative strategies and tools to foster animal health

Stabilization of swine fecal samples influences taxonomic and functional results in microbiome analyses

Studies on the microbiome of different species are on the rise, due to a growing interest in animal health and the safety of food products of animal origin. A challenge with studying animals’ microbiomes is to find methods that obtain a good representation of the microbial community of interest. Good unbiased sampling protocols are the basis for a solid experimental design, but may need to be done in environments where sample preservation could be difficult. In this study, we evaluate by shotgun sequencing the impact of stabilizing swine faeces samples using a commercial stabilizer (PERFORMAbiome • GUT | PB-200, DNA Genotek). Using stabilizer makes it possible to obtain DNA that is significantly less degraded than when the samples are not stabilized. Also, the results on the taxonomy and on the bacterial functions encoded in the microbiome are impacted by whether or not the samples are stabilized. Finally, the stabilization of samples that had already been frozen and stored at -80 °C led to extraction and DNA quality results similar to those obtained from samples that were stabilized before freezing

Saint-Sylvain-d’Anjou – La Haie Joulain

Des travaux de curage de la douve de l’ancienne maison forte à la Haie-Joulain (xive-xve s.) ont permis de réaliser une coupe stratigraphique dans laquelle s’observaient les vestiges d’un mur. L’inorganisation de cette structure laisse plutôt penser à une zone d’épandage de matériaux de démolition, en association avec la destruction de la maison forte, déjà entièrement ruinée au début du xixe s

Chênehutte-Trèves-Cunault – L’Île Gauthier, La Loire

G. Boisbouvier a profité des basses eaux de la Loire pour effectuer des relevés d’une structure immergée, reliant l’île Gauthier à la rive gauche de la Loire. Les dégagements ponctuels ont permis de préciser l’appartenance de ces vestiges à un ouvrage de franchissement, dont la datation n’est pas encore connue

A Survey of UV Bright Sources Behind the Halo of M31

We have performed a wide-area ultraviolet (UV) imaging survey using the GALaxy Evolution eXplorer (GALEX) to search for bright, point-like UV sources behind M31's extended halo. Our survey consisted of 46 pointings covering an effective area of ~50 deg^2, in both the far-UV and near-UV channels. We combined these data with optical R-band observations acquired with the WIYN Mosaic-1 imager on the Kitt Peak National Observatory 0.9m WIYN telescope. An analysis of the brightness and colors of sources matched between our photometric catalogs yielded ~100 UV-bright quasar candidates. We have obtained discovery spectra for 76 of these targets with the Kast spectrometer on the Lick 3m telescope and confirm 30 active galactic nuclei and quasars, 29 galaxies at z > 0.02 including several early-type systems, 16 Galactic stars (hot main-sequence stars), and one featureless source previously identified as a BL Lac object. Future UV spectroscopy of the brightest targets with the Cosmic Origins Spectrograph on the Hubble Space Telescope will enable a systematic search for diffuse gas in the extended halo of M31.Comment: 10 pages, 10 figures. Accepted to MNRA

Phytoglycogen nanoparticles : nature-derived superlubricants

Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak- to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10–3. In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10–2. Analysis of the water content and energy dissipation in the confined NP film reveals that the lubrication is governed by synergistic contributions of unbound and bound water molecules, with the former contributing to lubrication properties in the weak- to moderate-confinement regime and the latter being responsible for the lubrication in the strong-confinement regime. These results unravel mechanistic insights that are essential for the design of lubricating systems based on strongly hydrated NPs