Politique publique et changement climatique : Une lecture par les coalitions de cause du Programme de Paiement pour Services Environnementaux au Costa Rica

Les politiques de Paiement pour services environnementaux sont considérés comme des dispositifs innovants pour affronter les enjeux de conservation et de changement climatique. Néanmoins, même si les expériences locales se multiplient, les expériences de programmes nationaux sont peu nombreuses ainsi que la compréhension de leur condition d'émergence et d'évolutions. Le Programme National de Paiement pour Service Environnementaux (PPSE), adopté dès 1996 au Costa Rica, constitue une innovation singulière en termes d'instrument de politique publique pour lutter contre déforestation. Ce document de travail analyse les conditions qui ont permis l'adoption rapide puis l'évolution de cet instrument de politique. Mobilisant un cadre d'analyse cognitif des politique publique sur la longue durée, le cadre d'analyse des coalitions de cause (Advocacy Coalition Framework - ACF) développé par Sabat ier et Jenkins (1993), nous montrons que 1) le PPSE constitue un changement cognitif de la vision de la foret, 2) son adoption correspond à un changement des coalitions de cause dominantes dans le système politiques de gestion des espaces ruraux forestiers et 3) que ce changement est induit par une redistribution des ressources résultantes de modifications des variables externes et internes au système. Cette analyse permet de discuter les hypothèses de changement des politiques publiques énoncés dans le cad re de l'ACF et de mettre en perspective les évolutions récentes du PPSE à l'aune des processus d'apprentissage et d'évolution des coalitions de cause au Costa Rica

Adapting Batch Scheduling to Workload Characteristics: What can we expect From Online Learning?

Despite the impressive growth and size of super-computers, the computational power they provide still cannot match the demand. Efficient and fair resource allocation is a critical task. Super-computers use Resource and Job Management Systems to schedule applications, which is generally done by relying on generic index policies such as First Come First Served and Shortest Processing time First in combination with Backfilling strategies. Unfortunately, such generic policies often fail to exploit specific characteristics of real workloads. In this work, we focus on improving the performance of online schedulers. We study mixed policies, which are created by combining multiple job characteristics in a weighted linear expression, as opposed to classical pure policies which use only a single characteristic. This larger class of scheduling policies aims at providing more flexibility and adaptability. We use space coverage and black-box optimization techniques to explore this new space of mixed policies and we study how can they adapt to the changes in the workload. We perform an extensive experimental campaign through which we show that (1) even the best pure policy is far from optimal and that (2) using a carefully tuned mixed policy would allow to significantly improve the performance of the system. (3) We also provide empirical evidence that there is no one size fits all policy, by showing that the rapid workload evolution seems to prevent classical online learning algorithms from being effective.Malgré la croissance impressionnante et la taille des super-ordinateurs, le la puissance de calcul qu’ils fournissent ne peut toujours pas correspondre à la demande. Une allocation efficace et juste des ressources est essentielle tâche. Les super-ordinateurs utilisent des systèmes de gestion des ressources et des tâches pour programmer les applications, ce qui est généralement fait en s?appuyant sur des politiques d’index telles que First Come First Served et Shortest Temps de traitement D’abord en combinaison avec les stratégies de remblayage. Malheureusement, ces politiques génériques échouent souvent exploiter les caractéristiques spécifiques des charges de travail réelles. Dans ce travail, nous nous concentrons sur l’amélioration des performances des ordonnanceurs en ligne. Nous étudions des stratégies mixtes, créées en combinant plusieurs tâches caractéristiques dans une expression linéaire pondérée, par opposition à les politiques pures classiques qui n’utilisent qu’une seule caractéristique. Ce une plus grande classe de politiques de planification vise à offrir plus de flexibilité et adaptabilité. Nous utilisons la couverture d’espace et l’optimisation de la boîtenoire techniques pour explorer ce nouvel espace de politiques mixtes et nous étudions Comment peuvent-ils s’adapter aux changements de la charge de travail? Nous réalisons une vaste campagne expérimentale à travers laquelle nous montrons que (1) même la meilleure politique pure est loin d?être optimale et que (2) l?utilisation d?une politique mixte soigneusement adaptée permettrait de améliorer de manière significative les performances du système. (3) nous aussi fournir des preuves empiriques qu’il n’y a pas de politique uniforme, en montrant que l’évolution rapide de la charge de travail semble empêcher algorithmes classiques d’apprentissage en ligne d’être efficaces

Expression of Nestin, Vimentin, and NCAM by Renal Interstitial Cells after Ischemic Tubular Injury

This work explores the distribution of various markers expressed by interstitial cells in rat kidneys after ischemic injury (35 minutes) during regeneration of S3 tubules of outer stripe of outer medulla (OSOM). Groups of experimental animals (n = 4) were sacrificed every two hours during the first 24 hours post-ischemia as well as 2, 3, 7, 14 days post-ischemia. The occurrence of lineage markers was analyzed on kidney sections by immunohistochemistry and morphometry during the process of tubular regeneration. In postischemic kidneys, interstitial cell proliferation, assessed by 5-bromo-2′-deoxyuridine (BrdU) and Proliferating Cell Nuclear Antigen (PCNA) labeling, was prominent in outer medulla and reach a maximum between 24 and 72 hours after reperfusion. This population was characterized by the coexpression of vimentin and nestin. The density of -Neural Cell Adhesion Molecule (NCAM) positive interstitial cells increased transiently (18–72 hours) in the vicinity of altered tubules. We have also localized a small population of α-Smooth Muscle Actin (SMA)-positive cells confined to chronically altered areas and characterized by a small proliferative index. In conclusion, we observed in the postischemic kidney a marked proliferation of interstitial cells that underwent transient phenotypical modifications. These interstitial cells could be implicated in processes leading to renal fibrosis

Non linéarité de l’essaim de Quito de 1998-1999 associé à l’activité du volcan Guagua Pichincha, Équateur

Les variations temporelles des dimensions multi-fractales spatiales de l’essaim de séismes tectoniques de Quito (Équateur) sont corrélées à l’activité du volcan Guagua Pichincha. Les dimensions multi-fractales diminuent avant les 5 pics d’énergie. Ces valeurs réaugmentent avant ou juste après le pic d’énergie. L’essaim de Quito est également caractérisé par de fortes valeurs du facteur b (variant de 1,12 +/- 0,05 à 1,43 +/- 0,28). Une rupture dans la courbe de la loi de Gutenberg-Richter est observée qui implique la présence de deux valeurs du facteur b. Nous supposons qu’il puisse s’agir d’un comportement catastrophique, où une bifurcation se produit et conduit à deux scenari volcaniques différents : un épisode éruptif ou un épisode de calme du Guagua Pichincha. Ce comportement peut dépendre de petites variations de conditions internes, telles que des variations du champ de contraintes et/ou de pression de pores associées à des mouvements de fluides (gaz, eau souterraine et/ou magma).Las variaciones temporales de las dimensiones espaciales multi-fractales del enjambre de sismos tectónicos de Quito (Ecuador) son correlacionadas con la actividad del volcán Guagua Pichincha. Las dimensiones multi-fractales disminuyen antes de los 5 picos de energía sísmica. Estos valores incrementan antes o justo después del pico de energía. El enjambre de Quito está también caracterizado por altos valores del factor b (variando de 1,12 +/- 0,05 hasta 1,43 +/- 0,28). Una ruptura en la curva de la ley de Gutenberg-Richter occurió que implica la presencia de dos valores del factor b. Suponemos que puede ser un comportamiento catastrófico donde una bifurcación puede conducir a 2 escenarios diferentes  : un episodio eruptivo o un episodio de calma en el volcán Guagua Pichincha. Este comportamiento puede depender de pequeños cambios de condiciones internas, tal como variaciones del tensor de esfuerzos y/o de presión de poro asociadas a movimientos de fluidos (gas, agua subterránea y/o magma).Temporal variations of multi-fractal spatial dimensions of tectonic earthquakes of Quito swarm (Ecuador) are correlated to Guagua Pichincha volcano activity. Multi-fractal dimensions decrease before the 5 seismic energy peaks. These values increase before or just after the energy peak. Quito swarm is also characterized by high b-values (from 1,12 +/- 0,05 to 1,43 +/- 0,28). A break in the curve of the Gutenberg-Richter law occurred which implies the presence of two b-values. We suppose it may be a catastrophic behavior where a bifurcation may conduce to two different volcanic scenari : one eruptive period or one period of quiescence of Guagua Pichincha. This behavior may depend on small internal condition changes such as stress field and/or pore pressure variations associated to movement of fluids (gas, groundwater and/or magma)

Improving the Performance of Batch Schedulers Using Online Job Size Classification

Job scheduling in high-performance computing platforms is a hard problem that involves uncertainties on both the job arrival process and their execution time. Users typically provide a loose upper bound estimate for job execution times that are hardly useful. Previous studies attempted to improve these estimates using regression techniques. Although these attempts provide reasonable predictions, they require a long period of training data. Furthermore, aiming for perfect prediction may be of limited use for scheduling purposes. In this work, we propose a simpler approach by classifying jobs as small or large and prioritizing the execution of small jobs over large ones. Indeed, small jobs are the most impacted by queuing delays but they typically represent a light load and incur a small burden on the other jobs. The classifier operates online and learns by using data collected over the previous weeks, facilitating its deployment and enabling fast adaptations to changes in workload characteristics. We evaluate our approach using four scheduling policies on six HPC platform workload traces. We show that: (i) incorporating such classification reduces the average bounded slowdown of jobs in all scenarios, and (ii) the obtained improvements are comparable, in most scenarios, to the ideal hypothetical situation where the scheduler would know the exact running time of jobs in advance

Temporal variations of non-volcanic tremor (NVT) locations in the Mexican subduction zone: Finding the NVT sweet spot.

International audienceEpicentral locations of non-volcanic tremors (NVT) in the Mexican subduction zone are determined from the peak of the energy spatial distribution and examined over time. NVT is found to occur persistently at a distance of ∼215 km from the trench, which we term the "Sweet Spot" because this region probably has the proper conditions (i.e., temperature, pressure, and fluid content) for the NVT to occur with minimum shear slip. High-energy NVT episodes are also observed every few months, extending ∼190 km to ∼220 km from the trench with durations of a few weeks. During the 2006 slow slip event (SSE) the duration and the recurrence rate of the NVT episodes increased. Low-energy episodes were also observed, independent from the high-energy episodes, ∼150 km to ∼190 km from the trench during the 2006 SSE. Both the high and low energy episodes were made up of many individual NVT's that had a range of energy-release-rates. However, the highest energy-release-rates of the high-energy episodes were consistently double those of the low-energy episodes and the persistent activity at the Sweet Spot. We suggest that all of the high-energy episodes are evidence of small, short repeat interval SSE. Given this model, the increased recurrence rate of the high-energy NVT episodes during the 2006 long-term SSE implies that short-term SSE's also increase during the SSE and are therefore triggered by the SSE

Breathing and Coughing: The Extraordinarily High Degassing of Popocatépetl Volcano Investigated With an SO2 Camera

How do lava domes release volcanic gases? Studying this problem is crucial to understand, and potentially anticipate, the generation of the sudden and dangerous explosive eruptions that frequently accompany dome extrusions. Since its awakening in 1994, Popocatépetl volcano has produced more than 50 lava domes and has been consistently among the strongest permanent emitters of volcanic gases. In this work, we have characterized the passive and explosive degassing between 2013 and 2016 at a high time resolution using an SO2 camera, to achieve a better understanding of the conduit processes. Our 4-year average SO2 flux is 45 kg/s, in line with the long-term average of the whole current eruptive period. We show that Popocatépetl volcano is essentially an open system and that passive degassing, i.e., degassing with no associated emission of lava or ash, dominates >95% of the time. This passive degassing is continuous and sustained, whether the crater contains a lava dome or not. It shows most of the time a strong periodic component, with a pseudo-period of ~5 min, and amplitudes of 30 to 60% of the average value. We could distinguish two types of explosions based on their SO2 flux patterns. The first type (E1) occurs in the middle of the normal passive degassing and is followed by a rapid return of the SO2 flux down to its pre-explosive level. The second type (E2), which corresponds to the strongest events, is anticipated by a rapid decrease of the SO2 flux to abnormally low values and is followed by a return to its normal values. The E2 explosions are probably caused by the accumulation of gas below a rapidly compacting permeable dome. We suggest that transient episodes of gravitational compaction of the usually permeable dome and the upper conduit is the only mechanism that is fast enough to explain the sharp decrease of the SO2 flux that anticipates the E2 explosions. Our model is potentially applicable to a large number of andesitic volcanoes that undergo passive degassing interspersed with short-lived explosions

Inflammatory Properties and Adjuvant Potential of Synthetic Glycolipids Homologous to Mycolate Esters of the Cell Wall of Mycobacterium tuberculosis

&lt;p&gt;The cell wall of mycobacteria is characterised by glycolipids composed of different classes of mycolic acids (MAs; alpha-, keto-, and methoxy-) and sugars (trehalose, glucose, and arabinose). Studies using mutant Mtb strains have shown that the structure of MAs influences the inflammatory potential of these glycolipids. As mutant Mtb strains possess a complex mixture of glycolipids, we analysed the inflammatory potential of single classes of mycolate esters of the Mtb cell wall using 38 different synthetic analogues. Our results show that synthetic trehalose dimycolate (TDM) and trehalose, glucose, and arabinose monomycolates (TMM, GMM, and AraMM) activate bone marrow-derived dendritic cells in terms of the production of pro-inflammatory cytokines (IL-6 and TNF-&amp;alpha;) and reactive oxygen species, upregulation of costimulatory molecules, and activation of NLRP3 inflammasome by a mechanism dependent on Mincle. These findings demonstrate that Mincle receptor can also recognise pentose esters and seem to contradict the hypothesis that production of GMM is an escape mechanism used by pathogenic mycobacteria to avoid recognition by the innate immune system. Finally, our experiments indicate that TMM and GMM, as well as TDM, can promote Th1 and Th17 responses in mice in an OVA immunisation model, and that further analysis of their potential as novel adjuvants for subunit vaccines is warranted.&lt;/p&gt;</p