Petrophysical characterization of the lacustrine sediment succession drilled in Lake El‘gygytgyn, Far East Russian Arctic

Seismic profiles of Far East Russian Lake El’gygytgyn which was formed by a meteorite impact some 3.6 million years ago show a stratified sediment succession that can be separated into Subunits Ia and Ib at approximately 167 m below lake floor (= ∼3.17 Ma). The former is well-stratified, while the latter is acoustically more massive. The sediments are intercalated with frequent mass movement deposits mainly in the proximal parts, while the distal part is almost free of such deposits at least in the upper part. In spring 2009, a long core drilled in the lake center within the framework of the International Continental Scientific Drilling Program (ICDP) penetrated the entire lacustrine sediment succession down to ~320 m below lake floor and about 200 m further into the meteorite-impact related bedrock. Downhole logging data down to 390 m below lake floor show that the bedrock and the lacustrine part of the core differ largely in their petrophysical characteristics. The contact between the bedrock and the lacustrine sediments is not abrupt, but rather transitional with a mixture of impact-altered bedrock clasts in a lacustrine matrix with varying percentages. Physical and chemical proxies measured on the cores can be used to divide the lacustrine part into five different clusters. These can be plotted in a redox-condition vs. input type diagram with total organic carbon content and magnetic susceptibility values indicating anoxic or oxic conditions and with the Si/Ti ratio representing more clastic or more biogenic input. Plotting the clusters in this diagram allows identifying clusters that represent glacial phases (Cluster I), super interglacials (Cluster II), and interglacial phases (Clusters III and IV)

Aligning and synchronization of MIS5 proxy records from Lake Ohrid (FYROM) with independently dated Mediterranean archives: implications for DEEP core chronology

The DEEP site sediment sequence obtained during the ICDP SCOPSCO project at Lake Ohrid was dated using tephrostratigraphic information, cyclostratigraphy, and orbital tuning through the marine isotope stages (MIS) 15-1. Although this approach is suitable for the generation of a general chronological framework of the long succession, it is insufficient to resolve more detailed palaeoclimatological questions, such as leads and lags of climate events between marine and terrestrial records or between different regions. Here, we demonstrate how the use of different tie points can affect cyclostratigraphy and orbital tuning for the period between ca. 140 and 70 ka and how the results can be correlated with directly/indirectly radiometrically dated Mediterranean marine and continental proxy records. The alternative age model presented here shows consistent differences with that initially proposed by Francke et al. (2015) for the same interval, in particular at the level of the MIS6-5e transition. According to this new age model, different proxies from the DEEP site sediment record support an increase of temperatures between glacial to interglacial conditions, which is almost synchronous with a rapid increase in sea surface temperature observed in the western Mediterranean. The results show how a detailed study of independent chronological tie points is important to align different records and to highlight asynchronisms of climate events. Moreover, Francke et al. (2016) have incorporated the new chronology proposed for tephra OH-DP-0499 in the final DEEP age model. This has reduced substantially the chronological discrepancies between the DEEP site age model and the model proposed here for the last glacial-interglacial transition

LSST Science Book, Version 2.0

A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of the exciting science opportunities of the next decade. The Large Synoptic Survey Telescope (LSST) will have an effective aperture of 6.7 meters and an imaging camera with field of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over 20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a total point-source depth of r~27.5. The LSST Science Book describes the basic parameters of the LSST hardware, software, and observing plans. The book discusses educational and outreach opportunities, then goes on to describe a broad range of science that LSST will revolutionize: mapping the inner and outer Solar System, stellar populations in the Milky Way and nearby galaxies, the structure of the Milky Way disk and halo and other objects in the Local Volume, transient and variable objects both at low and high redshift, and the properties of normal and active galaxies at low and high redshift. It then turns to far-field cosmological topics, exploring properties of supernovae to z~1, strong and weak lensing, the large-scale distribution of galaxies and baryon oscillations, and how these different probes may be combined to constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at http://www.lsst.org/lsst/sciboo

Novel observations of East Asian Summer Monsoon evolution during Glacial Termination II from Lake Suigetsu, Japan

The dataset includes n-alkane and n-alkanoic acid concentrations, n-alkane index values and stable hydrogen isotope analysis values of n-alkanoic acids from the Lake Suigetsu sediment cores. The dataset spans from ~125 – 133 ka BP and samples were taken and analysed contiguously to each represent ~58-year (n=56) or ~112 years (n=4) of integrated time. These results were used to reconstruct catchment evolution and East Asian Summer Monsoon behaviour across Glacial Termination II

Plasma Urate in REM Sleep Behavior Disorder

Artículo de publicación ISIBackground: Rapid eye movement (REM) sleep behavior disorder (RBD) is associated with a high risk of developing Parkinson’s disease (PD). Higher urate levels are associated with a lower risk of PD. We conducted a study to evaluate plasma urate levels in patients with RBD and their role in the development of PD. Methods: We evaluated plasma urate levels in a cohort of 24 patients with idiopathic RBD. Patients were divided into 2 groups according to the presence or absence of PD. Other known markers of the risk of developing PD, such as olfaction testing, and substantia nigra (SN) hyperechogenicity, were evaluated in the 2 groups. Results: No differences were observed regarding age, years of evolution of the RBD, SN hyperechogenicity, or plasma urate levels between the 2 groups. In patients without PD, there was a positive correlation between years of evolution of RBD and the levels of uric acid (R250.88). Patients without PD and those who had more than 5 years of RBD exhibited higher levels of uric acid than patients with PD (P50.02). Conclusions: Higher levels of plasma urate were associated with a longer duration of RBD without converting to PD. Future prospective studies would be needed to confirm this finding. Disorder Society