Imputing Dairy Producers' Quota Discount Rate Using the Individual Export Milk Program in Quebec

Trade liberalization scenarios are often evaluated using sophisticated programming models that rely on a number of assumptions related to demand and supply parameters. One challenge researchers often encounter in the calibration of dairy trade liberalization models is to identify the supply response of producers under production quotas. The existence of production quotas in the Canadian dairy industry implies departures from standard marginal cost pricing. Under traditional net present value models, an assumption about the discount factors attached to production quotas must be made to infer the supply response of Canadian dairy producers following a change in the economic environment (e.g., import tariffs). The Individual Export Milk (IEM) program in Quebec generated an opportunity to estimate dairy producers’ discount factors for production quotas conditional on different assumptions about structural parameters such as producers’ risk preferences and cost efficiency.International Relations/Trade, Productivity Analysis,

Models, algorithms, and programs for phylogeny reconciliation

International audienceGene sequences contain a gold mine of phylogenetic information. But unfortunately for taxonomists this information does not only tell the story of the species from which it was collected. Genes have their own complex histories which record speciation events, of course, but also many other events. Among them, gene duplications, transfers and losses are especially important to identify. These events are crucial to account for when reconstructing the history of species, and they play a fundamental role in the evolution of genomes, the diversification of organisms and the emergence of new cellular functions. We review reconciliations between gene and species trees, which are rigorous approaches for identifying duplications, transfers and losses that mark the evolution of a gene family. Existing reconciliation models and algorithms are reviewed and difficulties in modeling gene transfers are discussed. We also compare different reconciliation programs along with their advantages and disadvantages

Inferring gene duplications, transfers and losses can be done in a discrete framework

UMR AGAP : équipe GE2popInternational audienceIn the field of phylogenetics, the evolutionary history of a set of organisms is commonly depicted by a species tree – whose internal nodes represent speciation events – while the evolutionary history of a gene family is depicted by a gene tree – whose internal nodes can also represent macro-evolutionary events such as gene duplications and transfers. As speciation events are only part of the events shaping a gene history, the topology of a gene tree can show incongruences with that of the corresponding species tree. These incongruences can be used to infer the macro-evolutionary events undergone by the gene family. This is done by embedding the gene tree inside the species tree and hence providing a reconciliation of those trees. In the past decade, several parsimony-based methods have been developed to infer such reconciliations, accounting for gene duplications (D), transfers (T) and losses (L). The main contribution of this paper is to formally prove an important assumption implicitly made by previous works on these reconciliations, namely that solving the (maximum) parsimony DTL reconciliation problem in the discrete framework is equivalent to finding a most parsimonious DTL scenario in the continuous framework. In the process, we also prove several intermediate results that are useful on their own and constitute a theoretical toolbox that will likely facilitate future theoretical contributions in the field

Un algorithme de parcimonie efficace pour la réconciliation d'arbres de gènes/espèces avec pertes, duplications et transferts

National audienceTree reconciliation is anapproach that explains the discrepancies between two evolutionary trees by a number of events such as speciations, duplications, transfers and losses. It has important applications in ecology, biogeography and genomics, for instance to decipher relationships between homologous sequences. (Results) We provide a fast and exact reconciliation algorithm according to a parsimony criterion that considers duplication, transfer and loss events. We also present experimental results that give first insights on the conditions under which parsimony is able to accurately infer evolutionary scenarios involving such events. Over all, parsimony performs well under realistic cases, as well as for relatively high duplication and transfer rates. As expected, transfers are in general less accurately recovered than duplications. Availability: www.lirmm.fr/phylariane

Exploitation des données prévisionnelles en aviation: une approche en ergonomie prospective

Cet article apporte un recensement de données prospectives qui permet d’avoir un aperçu de l’état présent et anticipé de trafic aérien (passagers et cargos) et personnels en aviation. Ce recensement identifie quatre organisations internationales (ACI, ATAG, OACI et IATA), une organisation de formation (CAE), un fabricant d'avions (Boeing) et deux entreprises d’analyse de données en aviation (CAPA et Cirium). Les données pointent vers une reprise graduelle de l'aviation d’ici 5 ans pour atteindre le niveau de 2019 et vers une augmentation du volume d’activités à long terme. Cette prospection nous permet donc d’anticiper des besoins à découvrir et à satisfaire en aviation dans les prochaines années. Étant donné la hausse de trafic aérien anticipée, il y aura un besoin futur de personnels compétents pour maintenir l’industrie et sa croissance. Ainsi, il y a un besoin d’interventions ergonomiques pour la création d’artefacts pour recruter, garder, former et certifier des personnels compétents présents et futurs

Exploiting Forward-Looking Data in Prospective Ergonomics: The Case of Aviation

n this study, we investigated different sources of forward-looking data in the domain of aviation and pilot training that are of interest to human factors researchers and practitioners involved in the creation of future artefacts. We show how trends that are emerging for the future as well as unforeseen short-term events, such as the COVID-19 pandemic, impact decisions made on the design of future artefacts in aviation. In this respect, the case of anticipating pilot shortage is examined in relation with the design of a new form of training program: evidence-based training (EBT)

Cerebral functional networks during sleep in young and older individuals

ABSTRACT: Even though sleep modification is a hallmark of the aging process, age-related changes in functional connectivity using functional Magnetic Resonance Imaging (fMRI) during sleep, remain unknown. Here, we combined electroencephalography and fMRI to examine functional connectivity differences between wakefulness and light sleep stages (N1 and N2 stages) in 16 young (23.1 ± 3.3y; 7 women), and 14 older individuals (59.6 ± 5.7y; 8 women). Results revealed extended, distributed (inter-between) and local (intra-within) decreases in network connectivity during sleep both in young and older individuals. However, compared to the young participants, older individuals showed lower decreases in connectivity or even increases in connectivity between thalamus/basal ganglia and several cerebral regions as well as between frontal regions of various networks. These findings reflect a reduced ability of the older brain to disconnect during sleep that may impede optimal disengagement for loss of responsiveness, enhanced lighter and fragmented sleep, and contribute to age effects on sleep-dependent brain plasticity

A combinatorial approach to create artificial homing endonucleases cleaving chosen sequences

Meganucleases, or homing endonucleases (HEs) are sequence-specific endonucleases with large (>14 bp) cleavage sites that can be used to induce efficient homologous gene targeting in cultured cells and plants. These findings have opened novel perspectives for genome engineering in a wide range of fields, including gene therapy. However, the number of identified HEs does not match the diversity of genomic sequences, and the probability of finding a homing site in a chosen gene is extremely low. Therefore, the design of artificial endonucleases with chosen specificities is under intense investigation. In this report, we describe the first artificial HEs whose specificity has been entirely redesigned to cleave a naturally occurring sequence. First, hundreds of novel endonucleases with locally altered substrate specificity were derived from I-CreI, a Chlamydomonas reinhardti protein belonging to the LAGLIDADG family of HEs. Second, distinct DNA-binding subdomains were identified within the protein. Third, we used these findings to assemble four sets of mutations into heterodimeric endonucleases cleaving a model target or a sequence from the human RAG1 gene. These results demonstrate that the plasticity of LAGLIDADG endonucleases allows extensive engineering, and provide a general method to create novel endonucleases with tailored specificities

Regulation of Septin Dynamics by the Saccharomyces cerevisiae Lysine Acetyltransferase NuA4

In the budding yeast Saccharomyces cerevisiae, the lysine acetyltransferase NuA4 has been linked to a host of cellular processes through the acetylation of histone and non-histone targets. To discover proteins regulated by NuA4-dependent acetylation, we performed genome-wide synthetic dosage lethal screens to identify genes whose overexpression is toxic to non-essential NuA4 deletion mutants. The resulting genetic network identified a novel link between NuA4 and septin proteins, a group of highly conserved GTP-binding proteins that function in cytokinesis. We show that acetyltransferase-deficient NuA4 mutants have defects in septin collar formation resulting in the development of elongated buds through the Swe1-dependent morphogenesis checkpoint. We have discovered multiple sites of acetylation on four of the five yeast mitotic septins, Cdc3, Cdc10, Cdc12 and Shs1, and determined that NuA4 can acetylate three of the four in vitro. In vivo we find that acetylation levels of both Shs1 and Cdc10 are reduced in a catalytically inactive esa1 mutant. Finally, we determine that cells expressing a Shs1 protein with decreased acetylation in vivo have defects in septin localization that are similar to those observed in NuA4 mutants. These findings provide the first evidence that yeast septin proteins are acetylated and that NuA4 impacts septin dynamics