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5,519 result(s) for "Francois, Jean Pierre"
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Holocene changes in the position and intensity of the southern westerly wind belt
Shifts in the position and intensity of the southern westerly winds recorded at single sites have been suggested to reflect uniform variation throughout the wind belt. Sedimentological analyses from the Andes suggest that changes in the intensity of the winds in the core and northern margin of the westerlies were antiphased during the Holocene epoch. The position and intensity of the southern westerly wind belt varies seasonally as a consequence of changes in sea surface temperature. During the austral winter, the belt expands northward and the wind intensity in the core decreases. Conversely, during the summer, the belt contracts, and the intensity within the core is strengthened. Reconstructions of the westerly winds since the last glacial maximum, however, have suggested that changes at a single site reflected shifts throughout the entire southern wind belt 1 , 2 , 3 , 4 . Here we use sedimentological and pollen records to reconstruct precipitation patterns over the past 12,500 yr from sites along the windward side of the Andes. Precipitation at the sites, located in the present core and northern margin of the westerlies, is driven almost entirely by the wind belt 5 , and can be used to reconstruct its intensity. Rather than varying coherently throughout the Holocene epoch, we find a distinct anti-phasing of wind strength between the core and northern margin over multi-millennial timescales. During the early Holocene, the core westerlies were strong whereas the northern margin westerlies were weak. We observe the opposite pattern in the late Holocene. As this variation resembles modern seasonal variability, we suggest that our observed changes in westerly wind strength can best be explained by variations in sea surface temperature in the eastern South Pacific Ocean.
Network-based repurposing identifies anti-alarmins as drug candidates to control severe lung inflammation in COVID-19
While establishing worldwide collective immunity with anti SARS-CoV-2 vaccines, COVID-19 remains a major health issue with dramatic ensuing economic consequences. In the transition, repurposing existing drugs remains the fastest cost-effective approach to alleviate the burden on health services, most particularly by reducing the incidence of the acute respiratory distress syndrome associated with severe COVID-19. We undertook a computational repurposing approach to identify candidate therapeutic drugs to control progression towards severe airways inflammation during COVID-19. Molecular profiling data were obtained from public sources regarding SARS-CoV-2 infected epithelial or endothelial cells, immune dysregulations associated with severe COVID-19 and lung inflammation induced by other respiratory viruses. From these data, we generated a protein-protein interactome modeling the evolution of lung inflammation during COVID-19 from inception to an established cytokine release syndrome. This predictive model assembling severe COVID-19-related proteins supports a role for known contributors to the cytokine storm such as IL1β, IL6, TNFα, JAK2, but also less prominent actors such as IL17, IL23 and C5a. Importantly our analysis points out to alarmins such as TSLP, IL33, members of the S100 family and their receptors (ST2, RAGE) as targets of major therapeutic interest. By evaluating the network-based distances between severe COVID-19-related proteins and known drug targets, network computing identified drugs which could be repurposed to prevent or slow down progression towards severe airways inflammation. This analysis confirmed the interest of dexamethasone, JAK2 inhibitors, estrogens and further identified various drugs either available or in development interacting with the aforementioned targets. We most particularly recommend considering various inhibitors of alarmins or their receptors, currently receiving little attention in this indication, as candidate treatments for severe COVID-19.
Effects of Drought and Fire Severity Interaction on Short-Term Post-Fire Recovery of the Mediterranean Forest of South America
Wildfires and drought stressors can significantly limit forest recovery in Mediterranean-type ecosystems. Since 2010, the region of central Chile has experienced a prolonged Mega Drought, which intensified into a Hyper Drought in 2019, characterized by record-low precipitation and high temperatures, further constraining forest recovery. This study evaluates short-term (5-year) post-fire vegetation recovery across drought gradients in two types of evergreen sclerophyllous forests and a thorny forest and shrubland, analyzing Landsat time series (1987–2022) from 42 wildfires. Using the LandTrendr algorithm, we assessed post-fire forest recovery based on NDVI changes between pre-fire values and subsequent years. The results reveal significant differences in recovery across drought gradients during the Hyper Drought period, among the three forest types studied. The xeric forest, dominated by Quillaja saponaria and Lithrea caustica, showed significant interaction effects between levels of drought and fire severity, while the thorny forest and shrubland displayed no significant interaction effects. The mesic forest, dominated by Cryptocarya alba and Peumus boldus, exhibited additional significant differences in recovery between the Hyper Drought and Mega Drought periods, along with significant interaction effects. These findings underscore the critical role of prolonged, severe drought in shaping forest recovery dynamics and highlight the need to understand these patterns to improve future forest resilience under increasingly arid conditions.
A Cross‐Cutting Approach for Relating Anthropocene, Environmental Injustice and Sacrifice Zones
The Anthropocene is an uneven phenomenon. Accelerated shifts in the functioning of the Earth System are mainly driven by the production and consumption of wealthy economies. Social, environmental and health costs of such industrialization, however, bear on low‐income communities inhabiting severely degraded territories by polluting activities (i.e., sacrifice zones). How global, national and local socio‐economic and governance processes have interacted in perpetuating socio‐environmental inequalities in these territories has been rarely explored. Here, we develop an historical quantitative approach integrating a novel chemostratigraphic record, data on policy making, and socio‐economic trends to evaluate the feedback relationship between environmental injustice and Anthropocene in sacrifice zones. We specifically outline a case study for the Puchuncaví valley ‐one of the most emblematic sacrifice zones from Chile‐. We verify an ever‐growing burden of heavy metals and metalloids over the past five decades paced by the staggering expansion of local industrial activities, which has ultimately been spurred by national and transnational market forces. Local poverty levels have declined concomitantly, but this path toward social equality is marginal as costs of pollution have grown through time. Indeed, national and international pollution control actions appear insufficient in mitigating the cumulative impact brought by highly toxic elements. Thus, our sub‐decadal reconstruction for pollution trends over the past 136 years from a sediment record, emerges as a science‐based tool for informing the discussion on Anthropocene governance. Furthermore, it helps to advance in the assessment of environmental inequality in societal models that prioritize economic growth to the detriment of socio‐environmental security. Plain Language Summary Costs of the sustained industrialization growth typically bear on low‐income communities (i.e., sacrifice zones). In this work, we designed a case study for the Puchuncaví sacrifice zone (Chile) to understand how socio‐economic and policymaking processes interact in perpetuating environmental inequality in these territories. Specifically, we integrate data obtained from a new sediment archive for historical pollution, socio‐economic trends and environmental policies to evaluate the relationship between environmental injustice and Anthropocene. We observe an ever‐growing load of heavy metals and metalloids over the past five decades paced by the staggering growth of local industrial activities, which has ultimately been spurred by national and transnational industrial and economic demands. Poverty levels in local communities declined concomitantly, but such reduction in social inequality is marginal and deceiving as effects of pollution have grown through time. Pollution control actions appear insufficient in mitigating cumulative and emergent impacts of highly toxic elements. Thus, our 136‐year reconstruction of the local pollution trajectory serves as a science‐based tool for informing the discussion on governance in the Anthropocene. Particularly, it helps to advance in the assessment of environmental inequality in societal models that prioritize economic growth to the detriment of the ecosystem and social security. Key Points Geochemical data provide a science‐based tool to inform the discussion on Anthropocene governance in severely degraded territories In our case study, socio‐environmental inequalities are linked to economic and governance processes operating from local to global scales Policies embracing local environmental rehabilitation are required as a just transition is not granted under a decarbonization scenario
Microbial Diversity of Soil in a Mediterranean Biodiversity Hotspot: Parque Nacional La Campana, Chile
Parque Nacional La Campana (PNLC) is recognized worldwide for its flora and fauna, rather than for its microbial richness. Our goal was to characterize the structure and composition of microbial communities (bacteria, archaea and fungi) and their relationship with the plant communities typical of PNLC, such as sclerophyllous forest, xerophytic shrubland, hygrophilous forest and dry sclerophyllous forest, distributed along topoclimatic variables, namely, exposure, elevation and slope. The plant ecosystems, the physical and chemical properties of organic matter and the soil microbial composition were characterized by massive sequencing (iTag-16S rRNA, V4 and ITS1-5F) from the DNA extracted from the soil surface (5 cm, n = 16). A contribution of environmental variables, particularly related to each location, is observed. Proteobacteria (35.43%), Actinobacteria (32.86%), Acidobacteria (10.07%), Ascomycota (76.11%) and Basidiomycota (15.62%) were the dominant phyla. The beta diversity (~80% in its axes) indicates that bacteria and archaea are linked to their plant categories, where the xerophytic shrub stands out with the most particular microbial community. More specifically, Crenarchaeote, Humicola and Mortierella were dominant in the sclerophyllous forest; Chloroflexi, Cyanobacteria and Alternaria in the xerophytic shrubland; Solicoccozyma in the dry sclerophyllous forest; and Cladophialophora in the hygrophilous forest. In conclusion, the structure and composition of the microbial consortia is characteristic of PNLC’s vegetation, related to its topoclimatic variables, which suggests a strong association within the soil microbiome.
Soil Microbial Communities Changes Along Depth and Contrasting Facing Slopes at the Parque Nacional La Campana, Chile
The Parque Nacional La Campana (PNLC) was recently recognized for its high soil surface microbial richness. Here, we explored the microbial community structure in soil profiles from contrasting facing slopes where sclerophyllous forest (SF) and xerophytic shrubland (XS) develop. Soil physicochemical conditions (dry density, pH, and organic matter C and N isotopic soil signatures) were determined at three depths (5, 10, and 15 cm depths). Amplicon sequencing (16S rRNA and ITS1-5F) and specific quantification (qPCR bacteria, archaea and ammonia-oxidizing archaea, fungi) were used to profile the microbial community. Our results indicate that opposite slopes, with different vegetation types and soil conditions studied potentially explained the spatial variability of the microbial community composition, especially between sites than through soil depth. Discriminative taxa were observed to vary between sites, such as, C. nitrososphaera (ammonia-oxidizing archaea) and Sphingomonas, and bacteria associated with Actinobacteria and Bacteroidetes were predominant in SF and XS, respectively. Fungi affiliated with Humicola and Preussia were more abundant in SF, while Cladosporium and Alternaria were in XS. Higher ASV richness was observed in SF compared to XS, for both prokaryotes and fungi. Furthermore, SF showed a higher number of shared ASVs, while XS showed a decrease in unique ASVs in deeper soil layers. In XS, the genus DA101 (Verrucomicrobia) increases with soil depth, reaching higher levels in SF, while Kaistobacter shows the opposite trend. PNLC soils were a reservoir of redundant microbial functions related to biogeochemical cycles, including symbiotic and phytopathogenic fungi. In conclusion, as with the predominant vegetation, the structure and potential function of microbial life in soil profiles were associated with the contrasting the effect of facing slopes as toposequence effects.
Distribution of greenhouse gases in hyper-arid and arid areas of northern Chile and the contribution of the high altitude wetland microbiome (Salar de Huasco, Chile)
Northern Chile harbors different bioclimatic zones including hyper-arid and arid ecosystems and hotspots of microbial life, such as high altitude wetlands, which may contribute differentially to greenhouse gases (GHG) such as carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). In this study, we explored ground level GHG distribution and the potential role of a wetland situated at 3800 m.a.s.l, and characterized by high solar radiation < 1600 W m−2, extreme temperature ranges (−12 to 24 °C) and wind stress (< 17 m s−1). The water source of the wetland is mainly groundwater springs, which generates streams and ponds surrounded by peatlands. These sites support a rich microbial aquatic life including diverse bacteria and archaea communities, which transiently form more complex structures, such as microbial mats. In this study, GHG were measured in the water and above ground level air at the wetland site and along an elevation gradient in different bioclimatic areas from arid to hyper-arid zones. The microbiome from the water and sediments was described by high-throughput sequencing 16S rRNA and rDNA genes. The results indicate that GHG at ground level were variable along the elevation gradient potentially associated with different bioclimatic zones, reaching high values at the high Andean steppe and variable but lower values in the Atacama Desert and at the wetland. The water areas of the wetland presented high concentrations of CH4 and CO2, particularly at the spring areas and in air bubbles below microbial mats. The microbial community was rich (> 40 phyla), including archaea and bacteria potentially active in the different matrices studied (water, sediments and mats). Functional microbial groups associated with GHG recycling were detected at low frequency, i.e., < 2.5% of total sequences. Our results indicate that hyper-arid and arid areas of northern Chile are sites of GHG exchange associated with various bioclimatic zones and particularly in aquatic areas of the wetland where this ecosystem could represent a net sink of N2O and a source for CH4 and CO2.
China and the Global Financial Crisis
This book examines China's response to the 2007-2008 global financial crisis, and the resulting new status acquired by China within the international economy. It considers the things China did to weather the crisis, discussing the stimulus package put in place by China and how China's banks coped, but above all examines the measures which countries outside China look to China to put in place in order to better encourage and secure world-wide economic recovery, measures such as currency revaluation, tax reform and greater stimulation of domestic demand. The book contrasts China's response to the crisis, and China's increasingly central role in the world economy, with the responses of the European Union. The book also assesses China's increasingly important regional role, in particular its dialogue with the new Japanese government, and China's positioning towards Southeast Asia, and also discusses the growth of Chinese foreign direct investment.
Fire, Fuel, and Climate Interactions in Temperate Climates
Temperate regions around the world are experiencing longer fire weather seasons, yet trends in burned area have been inconsistent between regions. Reasons for differences in fire patterns can be difficult to determine due to variable vegetation types, land use patterns, fuel conditions, and human influences on fire ignition and suppression. This study compares burned areas to climate and fuel conditions in three temperate regions: the desert, shrub, and forest ecoregions of western North America, west‐central Europe, and southwestern South America. In each region the mean annual aridity index (AI, precipitation over potential evapotranspiration) spans arid to humid climates. We examined how the fraction of area burned from 2001 to 2021 varied with mean annual AI, mean aboveground biomass, and land cover type distributions. All three regions had low fractions of area burned for the driest climate zones (AI < 0.5), a sign of fuel limitation to burned area. Fraction of area burned increased with mean aboveground biomass for these dry zones. Fraction of area burned peaked at intermediate AI (0.7–1.5) for all regions and declined again in the wettest climate zones (AI > 1.5), a sign of climate limitation to burned area. Of the three regions, western North America had the highest burned area, fraction of area burned, and fire sizes. Fragmentation of vegetation patches by the high Andes Mountains in southwestern South America and by intensive land use changes in west‐central Europe likely limited fire sizes. All three regions are at risk for future wildfires, particularly in areas where fire is currently climate limited. Plain Language Summary Warmer temperatures around the world are lengthening fire seasons, leading to large wildfires. We compared the burned areas in three regions that have large variations in climate and vegetation: western North America, west‐central Europe, and southwestern South America. We found that in the driest parts of each region, very little area burned because the vegetation is sparse, limiting the spread of fire. The area burned was also low in the wettest parts of these regions because the weather conditions were often not conducive to fire. The percent of area burned was highest in the intermediate climates, which have both enough vegetation for fire to spread and dry enough weather for wildfire. Among the three regions, the burned areas have been largest in western North America, which has the largest continuous extents of vegetation to burn. In southwestern South America, the forests and shrublands are broken up by the high Andes Mountains, and in west‐central Europe, extensive land use has limited the size of burnable areas. All three regions are at risk for large wildfires in the future, especially in the wettest areas where climate warming will make fire weather more likely. Key Points Evaluated burned area, climate, and fuel relationships in temperate desert, shrub, and forest ecoregions in N. & S. America and Europe All regions have different patterns of burned areas between the dry fuel‐limited and wet climate‐limited conditions Sizes of individual fires, total burned area, and fraction of area burned have been highest in western N. America and smallest in Europe
Effect of turbulence on the energetics of foraging in Atlantic cod Gadus morhua larvae
A net energy gain (NEG) model was used to assess the effects of turbulence on the energy budget of Atlantic cod Gadus morhua larvae, feeding on copepod nauplii at different concentrations. The geometry of their prey search space was parameterised as either a sphere, hemisphere (the most commonly applied in analogous studies), or wedge. Observed distributions in behaviour (e.g. move duration, pause duration, turn angles) were used as model input, and 2 facets of this behaviour (move duration and move speed) were varied to examine how parameterised changes in foraging behaviour can affect the NEG of the predator. At a prey concentration of 100 l-1, and in static water, NEG is an order of magnitude higher for a hemispherical shape relative to a wedge-shaped search volume. This difference decreases with increasing prey concentration (600 l-1), but always remains considerable. When parameterised turbulence was added, prey capture rates for a larva with a hemispherical search space increases 3 times as much as for a larva with a wedge-shaped search space (typically a 50% increase using the hemisphere vs 15% using a wedge). Thus, when this one key assumption (the search volume shape) of current turbulence-effects models is more realistically parameterised, the theorized advantage of turbulence is greatly reduced (at the level of the animal’s prey capture and NEG). This result demonstrates the need to carefully reassess the underlying assumptions of current turbulence-effects models and, therefore, the conclusions that have been based upon those models. Our NEG model also demonstrates the energetic benefits of certain changes in larval behaviour—such as shorter move durations—which lead to a more thorough and cost-effective search of the surrounding water for larvae with a wedge-shaped search volume. This latter effect is not observed for predators with spherical or hemispherical search volumes. These results indicate that it would be prudent to reconsider the conclusions of any previous study that was based upon over-simplified search space geometries.