Exceptional preservation of palaeozoic steroids in a diagenetic continuum

The occurrence of intact sterols has been restricted to immature Cretaceous (~125 Ma) sediments with one report from the Late Jurassic (~165 Ma). Here we report the oldest occurrence of intact sterols in a Crustacean fossil preserved for ca. 380 Ma within a Devonian concretion. The exceptional preservation of the biomass is attributed to microbially induced carbonate encapsulation, preventing full decomposition and transformation thus extending sterol occurrences in the geosphere by 250 Ma. A suite of diagenetic transformation products of sterols was also identified in the concretion, demonstrating the remarkable coexistence of biomolecules and geomolecules in the same sample. Most importantly the original biolipids were found to be the most abundant steroids in the sample. We attribute the coexistence of steroids in a diagenetic continuum-ranging from stenols to triaromatic steroids-to microbially mediated eogenetic processes

Holocene land cover dynamics in the Curuai Floodplain inferred from lacustrine biomarkers

This study on Curuai Floodplain (Central Amazonia) sediments (last 5600 cal yr BP) focused in Rock-Eval [RE; hydrogen (HI) and oxygen (OI) indices, Tmax, S2 curve and TpS2], organic petrography and molecular biomarkers [n-alkanes, hopanes, pentacyclic triterpene methyl ethers (PTMEs) and derivatives of pentacyclic triterpenes such as des-A-lupane and aromatic derivatives] analyses. Between 5600 and 5100 cal yr BP, the environment was waterlogged and dominated by emersed plants (Paq 0.27-0.38). The influence of the Amazon River was low. Terrestrial vs aquatic ratio (T/A, similar to 0.8), CPI values (3-4) and high contents of PTME (0.22-1.54 mu g/g sed) and aromatics (21-53 mu g/g sed) indicated a strong contribution of terrestrial material and anoxic OM deposition conditions. Between 5100 and 5000 cal yr BP more humid conditions due to heavier rainfalls were observed. Early in this period, terrestrial biomarker contents (253 mu g/g sed of aromatics, Paq similar to 0.17) increased due to input of watershed erosion material. This provoked a rapid burial and good preservation of terrestrial OM (CPI 3-4.5). From 5000 cal yr BP a strong sedimentation of carbonate minerals (OI similar to 1600 mg CO2.g(-1)) masked the OM signal and affecting RE parameters. Paq (similar to 0.18), T/A ratio (similar to 0.4) and the decrease of C-31 alpha beta/C-31 beta beta hopanes (1.18) indicate increasing aquatic conditions up to 2700 cal yr BP. CPI ratio (similar to 1.2) and degraded phytoclasts suggest intense degradation during transport to the sedimentation location. The PTMEs results showed that, from 3000 yr cal BP, the Poaceae genera were different from those found at the bottom (middle-Holocene), suggesting a change of vegetation. The last 600 cal yr BP were marked by the seasonal influence of the Amazon River; during periods of low water level, the organic petrography and CPI values (similar to 1.0) evidenced OM degradation and the return of rather drier conditions

ENVIRONMENTAL AND ANTHROPIC CONTROLS ON SEDIMENTS AND BIOMARKER DEPOSITION IN A DECANTATION TANK (ORLEANS, FRANCE)

International audienceIntroductionHuman activities are being registered by an unprecedented variety and concentration of markers in the sedimentary record. This is the founding concept of the Anthropocene for which a lower boundary was set at 1945 (Zalasiewicz et al., 2016) and a Global Boundary Stratotype Section and Point (GSSP) is currently under examination (Waters et al., 2018). Within the Golden Spike project (BIOHEFECT-EC2CO, CNRS-INSU) we propose that sedimentary archives deposited in sewer networks of urban areas constitute targets for Anthropocene GSSP because they are susceptible of recording a high diversity of concentrated matters, elements, biomarkers and isotopes of human origin through time. Before exploring such sediments, we investigate their potential as archives, i.e. the factors affecting their deposition processes, the availability of pertinent tracers and the controls on their archivability

Paleohydrological and paleoenvironmental changes recorded in terrestrial sediments of the Paleocene-Eocene boundary (Normandy, France)

The Paleocene-Eocene boundary (55.8. Ma) is associated with the Paleocene-Eocene Thermal Maximum (PETM), which is characterized by a negative Carbon Isotope Excursion (CIE), reflecting a major perturbation of the carbon cycle, and by an extreme and rapid global warming. The Cap d'Ailly area (Upper Normandy, France), in which previous studies have revealed the Paleocene-Eocene transition, is a reference locality for organic-rich terrestrial and lagoonal deposits of the "Sparnacian" stage, widespread in Northwestern Europe. In this study, we focus on the organic matter content of the Vasterival section. Organic data (Rock-Eval, palynofacies, biomarker analyses and compound specific isotope analyses) were acquired in order to constrain the paleoenvironmental and paleohydrological changes that occurred at the Paleocene-Eocene boundary. Stable carbon isotope compositions of higher plant leaf wax n-alkanes reveal a CIE of - 4.5‰, extending throughout the second half of the studied section. Palynofacies observations reveal: (i) an abrupt shift from a closed, quiescent marsh pond to an open eutrophic swamp subjected to algal blooms, concomitant with the onset of the CIE; and (ii) the evolution from a swamp to a tidal flat due to the marine transgression that occurred during the PETM. Higher plant biomarkers and their hydrogen isotopic composition compared to nitrogen analyses suggest: (i) dry episodes just before the PETM that may help to understand the triggering of this hyperthermal event; and (ii) a moister climate associated with a stronger seasonality during the early PETM.© 2013 ElsevierB.V

TIMING OF MILLET DIFFUSION IN THE ALPS FROM MILIACIN OCCURRENCE IN LAKE SEDIMENTS

International audienceBroomcorn millet (Panicum miliaceum) is considered as staple food for Europeans during prehistory. As a matter of fact, the Bronze Age was called Millet Golden Age by Marinval (1995). This cereal is distinct from those domesticated in the Fertile Crescent since its domestication was probably realised in Central Asia or China, and then its cultivation diffused towards the west thanks to population migrations or trades. The exact timing and routes of this diffusion, although documented by a large number of archaeological findings, remain to be precised. This would provide a more detailed picture of trading routes and migration pathways and pace of exchanges, with eventual relationships to climate changes.We have analysed miliacin, a molecular biomarker of millet (Jacob et al., 2008), in sediments from lakes Ledro (Utaly), Le Bourget, Paladru, Aiguebelette and La Thuile (France) in order to precise the timing of millet diffusion during the Neolithic and Bronze Age. The first occurrence of miliacin in Ledro is dated back to 2400 BC. In Le Bourget, Paladru, Aiguebelette and La Thuile, the date of first miliacin appearance is remarkably synchronous around 1500 BC. Miliacin was also detected at low levels in all older sediments in La Thuile. This could result either from laboratory contamination or from the presence of an alternative miliacin source in the catchment. Indeed miliacin is found in low amounts in several other Poaceae (Bossard et al., 2013). In Aiguebelette, a single sample dated back to the Neolithic (~2300 BC) shows significant miliacin concentrations. Because this date is close to that found in Ledro, it could attest to an early attempt of millet cultivation, but would imply a rapid diffusion from the East.Finally, the evolution of millet concentration in sediments of Le Bourget, La Thuile and Aiguebelette allows us making several assumptions on the development of alpine populations during the Bronze Age, Iron Age and Antiquity in the region, potentially linked to climate changes that affected the region at those times. ReferencesJacob et al., 2008. Millet cultivation history in the French Alps as evidenced by a sedimentary molecule. Journal of Archaeological Science 35, 814–820.Marinval, 1995. Données carpologiques françaises sur les millets (Panicum miliaceum L. et Setaria italica L. Beauc.) de la Protohistoire au Moyen Age. In Hörrandner, E., editor, Millet. Actes du Congrès d'Aizenay (1990). Peter Lang, 31-61.Bossard et al., 2013. Distribution of miliacin (olean-18-en-3β-ol methyl ether) in broomcorn millet (Panicum miliaceum), and other reputed potential sources. Consequences on the use of sedimentary miliacin as a tracer of millet. Organic Geochemistry 63, 48-55

En Konfigurerbar og Fleksibel Arkitektur for Laveffekt, Energieffektiv Maskinvareakselerasjon av Nevrale Nettverk basert på Foldning

Nevrale nettverk basert på foldning (CNNs) har blitt essensielle i dagens Kunstig-Intelligensog Maskinlærings-anvendelser. Dette gjelder særlig bildegjenkjenning. Denne masteroppgaven presenterer en konfigurerbar, allsidig og fleksibel arkitektur for maskinvareakselerasjon av CNNs som er basert på å lagre og akkumulere hele feature maps i lokalt minne inne i akseleratoren. Dette har blitt gjort med et mål om å være i stand til å prosessere enhver type CNN med så lavt effektforbruk og så høy energieffektivitet som mulig. Energieffektivitet viser til antall operasjoner per energienhet (målt i antall multiplikasjon-akkumulasjon-operasjoner per energienhet, MACs/s/W eller MACs/J). Flere ulike utgaver av arkitekturen har blitt syntetisert og testet med ulike konfigurasjoner. Sammenliknet med dagens beste akseleratorer preseterer den godt, den oppnår en energieffektivitetøkning med faktor større enn 5 for utvalgte CNN-lag. Den mest energieffektive konfigurasjonen oppnår 175 MACs/s/W med et effektforbruk på 2.3 mW og et arealforbruk på 585 KGEs (Kilo Gate Equivalents) med 1V forsyningsspenning og en klokkefrekvens på 100 MHz. Dette er en betydelig forbedring over Eyeriss [YuH17b] (en av dagens beste akseleratorer) som har en maksimal energieffektivitet på 122.8 MACs/s/W