Less rain, more water in ponds: a remote sensing study of the dynamics of surface waters from 1950 to present in pastoral Sahel (Gourma region, Mali)

Changes in the flooded area of ponds in the Gourma region from 1950 to present are studied by remote sensing, in the general context of the current multi-decennial Sahel drought. The seasonal and interannual variations of the areas covered by surface water are assessed using multi-date and multi-sensor satellite images (SPOT, FORMOSAT, LANDSAT-MSS, –TM, and -ETM, CORONA, and MODIS) and aerial photographs (IGN). Water body classification is adapted to each type of spectral resolution, with or without a middle-infrared band, and each spatial resolution, using linear unmixing for mixed pixels of MODIS data. The high-frequency MODIS data document the seasonal cycle of flooded areas, with an abrupt rise early in wet season and a progressive decrease in the dry season. They also provide a base to study the inter-annual variability of the flooded areas, with sharp contrasts between dry years such as 2004 (low and early maximal area) and wetter years such as 2001 and 2002 (respectively high and late maximal area).The highest flooded area reached annually greatly depends on the volume, intensity and timing of rain events. However, the overall reduction by 20% of annual rains during the last 40 years is concomitant with an apparently paradoxical large increase in the area of surface water, starting from the 1970's and accelerating in the mid 1980's. Spectacular for the two study cases of Agoufou and Ebang Mallam, for which time series covering the 1954 to present period exist, this increase is also diagnosed at the regional scale from LANDSAT data spanning 1972–2007. It reaches 108% between September 1975 and 2002 for 91 ponds identified in central Gourma. Ponds with turbid waters and no aquatic vegetation are mostly responsible for this increase, more pronounced in the centre and north of the study zone. Possible causes of the differential changes in flooded areas are discussed in relation with the specifics in topography, soil texture and vegetation cover over the watersheds that feed each of the ponds. Changes in rain pattern and in ponds sedimentation are ruled out, and the impact of changes in land use, limited in the area, is found secondary, as opposed to what has often been advocated for in southern Sahel. Instead, major responsibility is attributed to increased runoff triggered by the lasting impact of the 1970–1980's droughts on the vegetation and on the runoff system over the shallow soils prevailing over a third of the landscape

Gender, migration and the ambiguous enterprise of professionalizing domestic service: the case of vocational training for the unemployed in France

Drawing on ethnographic data concerning migrant male domestic workers, this article examines the gendered dimensions of the process of racialization in Italy and France. First, it shows that specific racialized constructions of masculinity are mobilized by the employers as well as by training and recruitment agencies. These constructions of masculinity are related to different forms of organization of the sector in each country and to different ideologies about the integration of migrants. Second, the data presented reveal the strategies used by migrant male domestic workers to reaffirm their masculinity in a traditionally feminized sector. In doing so, this article intends to explore the connections between international migration and the gendering of occupations, with regard to the construction and management of masculinities in domestic service. Finally, by examining men’s experiences, this article aims to contribute to a more complex definition of the international division of care work

Most diverse, most neglected: weevils (Coleoptera: Curculionoidea) are ubiquitous specialized brood-site pollinators of tropical flora

In tropical environments, and especially tropical rainforests, a major part of pollination services is provided by diverse insect lineages. Unbeknownst to most, beetles, and more specifically hyperdiverse weevils (Coleoptera: Curculionoidea), play a substantial role there as specialized mutualist brood pollinators. The latter contrasts with a common view where they are only regarded as plant antagonists. This study aims to provide a comprehensive understanding of what is known about plant-weevil brood-site mutualistic interactions, through a review of the known behavioral, morphological and physiological features found in these systems, and the identification of potential knowledge gaps. To date, plant-weevil associations have been described or indicated in no less than 600 instances. Representatives of major plant lineages are involved in these interactions, which have emerged independently at least a dozen times. Strikingly, these mutualistic interactions are associated with a range of convergent traits in plants and weevils. Plants engaged in weevil-mediated pollination are generally of typical cantharophilous type exhibiting large, white and fragrant flowers or inflorescences and they also show specific structures to host the larval stages of their specialist pollinators. Another characteristic feature is that flowers often perform thermogenesis and exhibit a range of strategies to separate sexual phases, either spatially or temporally. Conversely, lineages of brood-site weevil pollinators present numerous shared behavioral and physiological traits, and often form multispecific assemblages of closely related species on a single host; recent studies also revealed that they generally display a high degree of phylogenetic niche conservatism. This pollination mutualism occurs in all tropical regions, and the contrasts between the known and expected diversity of these systems suggests that a wide range of interactions remain to be described globally. Our early estimates of the species richness of the corresponding weevil clades and the marked pattern of phylogenetic niche conservatism of host use further suggest that weevil-based pollination far exceeds the diversity of other brood-site mutualistic systems, which are generally restricted to one or a few groups of plants. As such, weevil pollinators constitute a relevant model to explore the emergence and evolution of specialized brood-site pollination systems in the tropics

Field-induced water electrolysis switches an oxide semiconductor from an insulator to a metal

Here we demonstrate that water-infiltrated nanoporous glass electrically switches an oxide semiconductor from an insulator to metal. We fabricated the field effect transistor structure on an oxide semiconductor, SrTiO3, using 100%-water-infiltrated nanoporous glass - amorphous 12CaO*7Al2O3 - as the gate insulator. For positive gate voltage, electron accumulation, water electrolysis and electrochemical reduction occur successively on the SrTiO3 surface at room temperature, leading to the formation of a thin (~3 nm) metal layer with an extremely high electron concentration of 10^15-10^16 cm^-2, which exhibits exotic thermoelectric behaviour.Comment: 21 pages, 12 figure

Genetic data from the extinct giant rat from Tenerife (Canary Islands) points to a recent divergence from mainland relatives

Evolution of vertebrate endemics in oceanic islands follows a predictable pattern, known as the island rule, according to which gigantism arises in originally small-sized species and dwarfism in large ones. Species of extinct insular giant rodents are known from all over the world. In the Canary Islands, two examples of giant rats, †Canariomys bravoi and †Canariomys tamarani, endemic to Tenerife and Gran Canaria, respectively, disappeared soon after human settlement. The highly derived morphological features of these insular endemic rodents hamper the reconstruction of their evolutionary histories. We have retrieved partial nuclear and mitochondrial data from †C. bravoi and used this information to explore its evolutionary affinities. The resulting dated phylogeny confidently places †C. bravoi within the African grass rat clade (Arvicanthis niloticus). The estimated divergence time, 650 000 years ago (95% higher posterior densities: 373 000-944 000), points toward an island colonization during the Günz-Mindel interglacial stage. †Canariomys bravoi ancestors would have reached the island via passive rafting and then underwent a yearly increase of mean body mass calculated between 0.0015 g and 0.0023 g; this corresponds to fast evolutionary rates (in darwins (d), ranging from 7.09 d to 2.78 d) that are well above those observed for non-insular mammals.For technical support, we thank the research service facilities of IJC and IGTP, the Crystallization Facility of the Max Planck Institute of Biochemistry, the ICTS NMR facility from the Scientific and Technological Centres of the University of Barcelona and Biophysics Core Facility of BMC-LMU. I.G. was a fellow of the Marie Skłodowska Curie Training network ‘ChroMe’ (H2020-MSCA-ITN-2015-675610, awarded to M.B. and A.G.L.). The project was further supported by national grants (nos. RTI2018-094005-B-I00 and BFU2015-66559-P from FEDER/Ministerio de Ciencia e Innovación—Agencia Estatal de Investigación to M.B.). Research in the participating labs was further supported by the following grants: the Marie Skłodowska Curie Training network ‘INTERCEPT-MDS’ no. H2020-MSCA-ITN-2020-953407 (to M.B.), MINECO-ISCIII no. PIE16/00011 (to M.B.); the Deutsche José Carreras Leukämie Stiftung DJCLS (no. 14R/2018 to M.B.), AGAUR (no. 2017-SGR-305 to M.B.), Fundació La Marató de TV3 (no. 257/C/2019 to M.B.), German Research Foundation Project (ID 213249687—SFB 1064 and Project ID 325871075—SFB 1309 to A.G.L.), the Spanish Ministry of Science (PID2019-110183RB-C21 to A.R.M.), Community of Madrid (P2018/BAA-4343-ALIBIRD2020-CM to A.R.M), Ramón Areces Foundation (to A.R.M.), National Science Foundation (EF-1921402 to J.M.E.L.), 2015 International Doctoral Fellowship La Caixa-Severo Ochoa (to M.F.V.), Marie Skłodowska-Curie Individual Fellowship (no. 747789 to M.M.L.), Juan de la Cierva-Incorporación (IJC2018-036657-I to M.M.L., ERC-2012-CoG-616960 to I.R.T.), MINECO (BFU2017-90114-P to I.R.T.), AGAUR (2017-SGR-324 to X.S.) and MINECO (BIO2015-70092-R and ERC-2014-CoG-648201 to X.S.). Research at the IJC is supported by the ‘La Caixa’ Foundation, Fundació Internacional Josep Carreras, Celgene Spain and the CERCA Programme/Generalitat de Catalunya