Snow spectral albedo at Summit, Greenland: measurements and numerical simulations based on physical and chemical properties of the snowpack

The broadband albedo of surface snow is determined both by the near-surface profile of the physical and chemical properties of the snowpack and by the spectral and angular characteristics of the incident solar radiation. Simultaneous measurements of the physical and chemical properties of snow were carried out at Summit Camp, Greenland (72°36´ N, 38°25´ W, 3210 m a.s.l.) in May and June 2011, along with spectral albedo measurements. One of the main objectives of the field campaign was to test our ability to predict snow spectral albedo by comparing the measured albedo to the albedo calculated with a radiative transfer model, using measured snow physical and chemical properties. To achieve this goal, we made daily measurements of the snow spectral albedo in the range 350–2200 nm and recorded snow stratigraphic information down to roughly 80 cm. The snow specific surface area (SSA) was measured using the DUFISSS instrument (DUal Frequency Integrating Sphere for Snow SSA measurement, Gallet et al., 2009). Samples were also collected for chemical analyses including black carbon (BC) and dust, to evaluate the impact of light absorbing particulate matter in snow. This is one of the most comprehensive albedo-related data sets combining chemical analysis, snow physical properties and spectral albedo measurements obtained in a polar environment. The surface albedo was calculated from density, SSA, BC and dust profiles using the DISORT model (DIScrete Ordinate Radiative Transfer, Stamnes et al., 1988) and compared to the measured values. Results indicate that the energy absorbed by the snowpack through the whole spectrum considered can be inferred within 1.10%. This accuracy is only slightly better than that which can be obtained considering pure snow, meaning that the impact of impurities on the snow albedo is small at Summit. In the near infrared, minor deviations in albedo up to 0.014 can be due to the accuracy of radiation and SSA measurements and to the surface roughness, whereas deviations up to 0.05 can be explained by the spatial heterogeneity of the snowpack at small scales, the assumption of spherical snow grains made for DISORT simulations and the vertical resolution of measurements of surface layer physical properties. At 1430 and around 1800 nm the discrepancies are larger and independent of the snow properties; we propose that they are due to errors in the ice refractive index at these wavelengths. This work contributes to the development of physically based albedo schemes in detailed snowpack models, and to the improvement of retrieval algorithms for estimating snow properties from remote sensing data

Fuel cell rejuvenation of hygrothermally aged Nafion

International audienceNafion ® membranes stored for long periods at 80 °C under elevated relative humidity up to 95%RH exhibit large modifications of their properties attributed to the sulfonic acid end-group condensation into sulfonic anhydrides. The present study is devoted to the membrane property rejuvenation, namely the hydrolysis of the sulfonic anhydrides under different experimental conditions. Aged membranes were exposed to pure water and to acid solutions or vapors in order to check the reversibility of the condensation reaction. Indeed, the hydrolysis process is slow in pure water and limited while it is fast and complete in the presence of acid or base. The native polymer chemical structure and the main membrane properties (mechanical properties, hydrophilicity, etc.) are completely restored. No evidence of hygrothermal aging was observed after fuel cell operation and it is shown that a membrane previously aged under ex situ conditions can be completely rejuvenated when operated in fuel cell

La nation de la minorité bruyante : idéologies de la droite radicale au Canada

Une montée de la droite radicale populiste a pu être observée dans les démocraties occidentales au cours des dernières années. Celle-ci s'est traduite au niveau électoral en Europe et même aux États-Unis. Si le Canada a relativement été épargné par la montée de celle-ci sur le plan électoral, il a tout de même été possible de noter une augmentation du nombre de groupes s'apparentant à cette mouvance de droite. Or, ces groupes et leurs idéologies ont peu été étudiés dans le contexte canadien. Le présent travail s'intéresse à la relation entre les deux idéologies principales de la droite radicale populiste, l'ethnonationalisme et le populisme, dans le discours de deux groupes canadiens : La Meute et le National Citizens Alliance. Une analyse du discours des groupes est effectuée à partir de leur documentation officielle et de leurs publications Facebook de 2019. Notre analyse, par le biais du cadre théorique utilisé, permet d'abord de confirmer que les idéologies de nos deux cas d'étude s'apparentent bel et bien à celles de la droite radicale populiste européenne. Elle permet aussi de comparer nos cas entre eux, montrant ainsi que malgré leurs grandes similitudes, les idéologies du deuxième groupe sont plus radicales. Il a d'ailleurs été possible de lier cette différence avec les contextes distincts dans lesquels s'inscrivent les discours des groupes. L'analyse plus détaillée de l'argumentaire des groupes permet de confirmer notre proposition selon laquelle le populisme découlerait de l'ethnonationalisme et que la première idéologie viendrait appuyer la seconde. Toutefois, notre analyse permet de comprendre plus en détail la nature de cette relation en montrant que le populisme a essentiellement un rôle de légitimation démocratique pour les revendications ethnonationalistes. Le travail parvient également à montrer que l'ethnonationalisme s'enracine plus largement dans une forme de conservatisme radical, apportant ainsi des pistes pour les recherches futures sur le sujet.A rise of the populist radical right has been observed in Western democracies in recent years. This was reflected at the electoral level in Europe and even in the United States. While Canada has been relatively spared by the rise of the latter on the electoral front, it has nonetheless been possible to see an increase in the number of groups resembling this right-wing movement. However, very few studies have been focusing on those groups and their ideologies in the Canadian context. This study examines the relationship between the two main ideologies of the radical right-wing populist, ethnonationalism and populism, in the discourse of two Canadian groups: La Meute and the National Citizens Alliance. An analysis of the groups' discourse is done from their official documentation and Facebook posts from 2019. Our analysis, through the theoretical framework used, first confirms that the ideologies of our two cases studied indeed resemble those of the European populist radical right. It also allows us to compare our cases with one another, showing that despite their great similarities, the ideologies of the second group are more radical. It was moreover possible to link this difference with the distinct contexts in which the discourse of the groups takes place. A more detailed analysis of the group's arguments confirms our proposition that populism stems from ethnonationalism and that the first ideology supports the second. However, our analysis allows us to understand in more details the nature of this relationship by showing that populism has essentially a role of democratic legitimization for ethno-nationalist claims. The work also succeeds in showing that ethnonationalism is rooted more broadly in a form of radical conservatism, thus providing avenues for future research on the subject

Fuel cell rejuvenation of hygrothermally aged Nafion

Nafion ® membranes stored for long periods at 80 °C under elevated relative humidity up to 95%RH exhibit large modifications of their properties attributed to the sulfonic acid end-group condensation into sulfonic anhydrides. The present study is devoted to the membrane property rejuvenation, namely the hydrolysis of the sulfonic anhydrides under different experimental conditions. Aged membranes were exposed to pure water and to acid solutions or vapors in order to check the reversibility of the condensation reaction. Indeed, the hydrolysis process is slow in pure water and limited while it is fast and complete in the presence of acid or base. The native polymer chemical structure and the main membrane properties (mechanical properties, hydrophilicity, etc.) are completely restored. No evidence of hygrothermal aging was observed after fuel cell operation and it is shown that a membrane previously aged under ex situ conditions can be completely rejuvenated when operated in fuel cell

Artificios pasados. Nociones del Derecho medieval

En la larga historia de Occidente, el derecho fue y sigue siendo el medio por excelencia para la construcción institucional. A partir de montajes hechos de palabras, proferidas por quien tiene el poder para hacerlo, el derecho tiene la singularidad de promover existencia a lo que ellas enuncian. Esta capacidad de artificio que contiene el discurso jurídico se remonta a la tradición latina, romana y medieval, que designaba al derecho como un arte, un saber sistemático y técnico que movilizaba su interpretación al servicio de la práctica. A partir de relevar la construcción técnica e histórica de ciertos artificios y operaciones jurídicas que tuvieron un lugar clave en el derecho europeo medieval y moderno y, que, en la actualidad, o bien ya no existen bajo forma jurídica o han cambiado radicalmente su sentido, proponemos una reflexión sobre la capacidad de intervención y producción de efectos del discurso jurídico. Focalizar en estos artificios del pasado nos ofrece una saludable distancia que hace más visibles las operaciones técnicas presentes en los textos a la vez que entrena la mirada para abordar las intervenciones del presente por fuera de todo efecto de naturalización.Entre el museo y el taller: recorriendo itinerarios jurídicos del pasado / Eleonora Dell’Elicine, Paola Miceli, Alejandro Morin (pp.11-17). -- Tyrannus. Usurpador y rey injusto en época visigoda / Céline Martin (pp. 19-36). -- Nota sobre la dignidad del hombre en el derecho romano medieval / Marta Madero (pp. 37-56). -- Las categorías doctrinales del proceso y la efectividad de la justicia penal en el tardomedioevo / Massimo Meccarelli (pp. 57-82). -- Atrocitas/Enormitas. Esbozo para una historia de la categoría de “enormidad” o “crimen enorme” de la Edad Media a la época moderna / Julien Théry (pp. 83-150). -- El eterno “renacer” de la costumbre / Paola Miceli (pp. 151-179). -- El nacimiento de la noción canónica de consanguinitas y su recepción en el derecho civil / Franck Roumy (pp. 181-208). -- Sicut cancer, amplius serperet in occulto. La herejía oculta en el derecho bajomedieval y tempranomoderno / Alejandro Morin (pp. 209-244). -- Propter vitandum scandalum. Historia de una categoría jurídica (siglos XII-XV) / Arnaud Fossier (pp. 245-307)

Prevention of Heart Failure in Rats by Trimetazidine Treatment: A Consequence of Accelerated Phospholipid Turnover?

ABSTRACT Heart failure is known for alteration of cardiac catecholamine responsiveness involving adrenergic receptor (AR) down-regulation. Trimetazidine, a metabolically active anti-ischemic drug, accelerates the turnover of phospholipids. The present study evaluated the consequences of trimetazidine treatment (supposed to increase phospholipid synthesis) on AR in heart failure in rats. In control rats, trimetazidine (7.5 mg/day supplied in the diet) induced after 8 weeks a significant increase in both ␤-(ϩ54%) and ␣-AR (ϩ30%) density, although after 12 weeks, the receptor density was normalized. Heart failure was obtained by ascending aortic banding. These heart failure rats developed a severe cardiac hypertrophy, mainly affecting the left ventricle, which was significantly reduced in the trimetazidine-treated group. The plasma level of brain natriuretic peptide (BNP), a marker of heart failure severity, was significantly increased in the heart failure group as compared with the sham group (900 and 1200% after 8 and 12 weeks, respectively). In the trimetazidine-treated group, the plasma BNP increase was significantly lower. The development of heart failure was associated with a decrease in ␤-and ␣-AR sites (Ϫ23 and Ϫ36% versus sham, respectively) after 8 weeks and continued to decrease after 12 weeks (Ϫ37 and Ϫ48% versus sham, respectively). This down-regulation was prevented by trimetazidine without alteration in affinity. These results suggest that trimetazidine prevents AR desensitization and cardiac hypertrophy, in a pressure-overload model of heart failure. This cytoprotection suggests that membrane homeostasis preservation may be considered as a therapeutic target in the treatment of heart failure

Electroencephalography microstates imbalance across the spectrum of early psychosis, autism, and mood disorders

Abstract Background Electroencephalography (EEG) microstates translate resting-state temporal dynamics of neuronal networks throughout the brain and could constitute possible markers of psychiatric disorders. We tested the hypothesis of an increased imbalance between a predominant self-referential mode (microstate C) and a decreased attentional mode (microstate D) in psychosis, mood, and autism spectrum disorders. Methods We retrospectively included 135 subjects from an early psychosis outpatient unit, with available eyes-closed resting-state 19 electrodes EEG. Individual-level then group-level modified K-means clustering in controls provided four microstate maps that were then backfitted to all groups. Differences between microstate parameters (occurrence, coverage, and mean duration) were computed between controls and each group, and between disease groups. Results Microstate class D parameters were systematically decreased in disease groups compared with controls, with an effect size increasing along the psychosis spectrum, but also in autism. There was no difference in class C. C/D ratios of mean duration were increased only in SCZ compared with controls. Conclusions The decrease in microstate class D may be a marker of stage of psychosis, but it is not specific to it and may rather reflect a shared dimension along the schizophrenia-autism spectrum. C/D microstate imbalance may be more specific to schizophrenia

Périgord black truffle genome uncovers evolutionary origins and mechanisms of symbiosis

LetterInternational audienceThe Périgord black truffle ($Tuber\ melanosporum$ Vittad.) and the Piedmont white truffle dominate today's truffle market. The hypogeous fruiting body of $T.\ melanosporum$ is a gastronomic delicacy produced by an ectomycorrhizal symbiont endemic to calcareous soils in southern Europe. The worldwide demand for this truffle has fuelled intense efforts at cultivation. Identification of processes that condition and trigger fruit body and symbiosis formation, ultimately leading to efficient crop production, will be facilitated by a thorough analysis of truffle genomic traits. In the ectomycorrhizal $Laccaria\ bicolor$, the expansion of gene families may have acted as a 'symbiosis toolbox'. This feature may however reflect evolution of this particular taxon and not a general trait shared by all ectomycorrhizal species. To get a better understanding of the biology and evolution of the ectomycorrhizal symbiosis, we report here the sequence of the haploid genome of $T.\ melanosporum$, which at $\sim$125 megabases is the largest and most complex fungal genome sequenced so far. This expansion results from a proliferation of transposable elements accounting for $\sim$58% of the genome. In contrast, this genome only contains $\sim$7,500 protein-coding genes with very rare multigene families. It lacks large sets of carbohydrate cleaving enzymes, but a few of them involved in degradation of plant cell walls are induced in symbiotic tissues. The latter feature and the upregulation of genes encoding for lipases and multicopper oxidases suggest that $T.\ melanosporum$ degrades its host cell walls during colonization. Symbiosis induces an increased expression of carbohydrate and amino acid transporters in both $L.\ bicolor$ and $T.\ melanosporum$, but the comparison of genomic traits in the two ectomycorrhizal fungi showed that genetic predispositions for symbiosis $-$'the symbiosis toolbox'$-$ evolved along different ways in ascomycetes and basidiomycete