1,104 research outputs found
Altered carbon cycling and trace-metal enrichment during the late Valanginian and early Hauterivian
Abstract.: Carbonates of Valanginian age deposited in the Tethys and Atlantic Oceans show a distinct positive δ13C excursion (Δ δ13C = 1.5‰-2‰) in sections of the neritic, hemipelagic, and pelagic environment. This excursion records a major climate-induced perturbation of the global carbon system. The δ13C excursion is accompanied by enrichments in manganese (Mn) and iron (Fe). The correlation of the δ13C excursion with trends in Mn and Fe contents reflects changes in Valanginian paleoceanography and climate. Fe enrichment occurs mainly in terrestrial, platform, and shelf regions. In a basinal direction the Fe content decreases, whereas the Mn/Fe ratio increases. An increase in sedimentary Mn and Fe concentrations is related to elevated continental weathering rates and to widespread dys- or anoxia that favored metal deposition in Valanginian sediments. Various oceanographic changes (e.g., expansion of oxygen-minimum zones) resulting from increased continental runoff led to a strong remobilization and focused reprecipitation of metals in the oceans of the Valanginian stag
Structure and dynamics of the fast lithium ion conductor "li 7La3Zr2O12"
The solid lithium-ion electrolyte "Li7La3Zr 2O12" (LLZO) with a garnet-type structure has been prepared in the cubic and tetragonal modification following conventional ceramic syntheses routes. Without aluminium doping tetragonal LLZO was obtained, which shows a two orders of magnitude lower room temperature conductivity than the cubic modification. Small concentrations of Al in the order of 1 wt% were sufficient to stabilize the cubic phase, which is known as a fast lithium-ion conductor. The structure and ion dynamics of Al-doped cubic LLZO were studied by impedance spectroscopy, dc conductivity measurements, 6Li and 7Li NMR, XRD, neutron powder diffraction, and TEM precession electron diffraction. From the results we conclude that aluminium is incorporated in the garnet lattice on the tetrahedral 24d Li site, thus stabilizing the cubic LLZO modification. Simulations based on diffraction data show that even at the low temperature of 4 K the Li ions are blurred over various crystallographic sites. This strong Li ion disorder in cubic Al-stabilized LLZO contributes to the high conductivity observed. The Li jump rates and the activation energy probed by NMR are in very good agreement with the transport parameters obtained from electrical conductivity measurements. The activation energy Ea characterizing long-range ion transport in the Al-stabilized cubic LLZO amounts to 0.34 eV. Total electric conductivities determined by ac impedance and a four point dc technique also agree very well and range from 1 × 10-4 Scm-1 to 4 × 10-4 Scm-1 depending on the Al content of the samples. The room temperature conductivity of Al-free tetragonal LLZO is about two orders of magnitude lower (2 × 10 -6 Scm-1, Ea = 0.49 eV activation energy). The electronic partial conductivity of cubic LLZO was measured using the Hebb-Wagner polarization technique. The electronic transference number te- is of the order of 10-7. Thus, cubic LLZO is an almost exclusive lithium ion conductor at ambient temperature. © the Owner Societies 2011
The Adaptive Gain Integrating Pixel Detector at the European XFEL
The Adaptive Gain Integrating Pixel Detector (AGIPD) is an x-ray imager,
custom designed for the European x-ray Free-Electron Laser (XFEL). It is a
fast, low noise integrating detector, with an adaptive gain amplifier per
pixel. This has an equivalent noise of less than 1 keV when detecting single
photons and, when switched into another gain state, a dynamic range of more
than 10 photons of 12 keV. In burst mode the system is able to store 352
images while running at up to 6.5 MHz, which is compatible with the 4.5 MHz
frame rate at the European XFEL. The AGIPD system was installed and
commissioned in August 2017, and successfully used for the first experiments at
the Single Particles, Clusters and Biomolecules (SPB) experimental station at
the European XFEL since September 2017. This paper describes the principal
components and performance parameters of the system.Comment: revised version after peer revie
Retrospective cohort study to devise a treatment decision score predicting adverse 24-month radiological activity in early multiple sclerosis
Background:
Multiple sclerosis (MS) is a chronic neuroinflammatory disease affecting about 2.8 million people worldwide. Disease course after the most common diagnoses of relapsing-remitting multiple sclerosis (RRMS) and clinically isolated syndrome (CIS) is highly variable and cannot be reliably predicted. This impairs early personalized treatment decisions.
Objectives:
The main objective of this study was to algorithmically support clinical decision-making regarding the options of early platform medication or no immediate treatment of patients with early RRMS and CIS.
Design:
Retrospective monocentric cohort study within the Data Integration for Future Medicine (DIFUTURE) Consortium.
Methods:
Multiple data sources of routine clinical, imaging and laboratory data derived from a large and deeply characterized cohort of patients with MS were integrated to conduct a retrospective study to create and internally validate a treatment decision score [Multiple Sclerosis Treatment Decision Score (MS-TDS)] through model-based random forests (RFs). The MS-TDS predicts the probability of no new or enlarging lesions in cerebral magnetic resonance images (cMRIs) between 6 and 24 months after the first cMRI.
Results:
Data from 65 predictors collected for 475 patients between 2008 and 2017 were included. No medication and platform medication were administered to 277 (58.3%) and 198 (41.7%) patients. The MS-TDS predicted individual outcomes with a cross-validated area under the receiver operating characteristics curve (AUROC) of 0.624. The respective RF prediction model provides patient-specific MS-TDS and probabilities of treatment success. The latter may increase by 5–20% for half of the patients if the treatment considered superior by the MS-TDS is used.
Conclusion:
Routine clinical data from multiple sources can be successfully integrated to build prediction models to support treatment decision-making. In this study, the resulting MS-TDS estimates individualized treatment success probabilities that can identify patients who benefit from early platform medication. External validation of the MS-TDS is required, and a prospective study is currently being conducted. In addition, the clinical relevance of the MS-TDS needs to be established
Klimawandel und Teichwirtschaft: Auswirkungen des Klimawandels auf die Perspektiven in der sächsischen Teichwirtschaft
Die Veröffentlichung enthält differenzierte Analysen für die Entwicklung von Temperatur, Niederschlag und Sonnenscheindauer sowie deren Schwankungen für die sieben Gebiete in Sachsen, in denen sich die meisten Karpfenteichwirtschaften befinden. Dabei werden sowohl die Vergangenheit als auch die mögliche zukünftige Klimaentwicklung betrachtet.
Die Broschüre richtet sich an Teichwirte, Fach- und Förderverwaltungen, Planer, Naturschutz-, Heimatschutz- und Tourismusverbände sowie die interessierte Öffentlichkeit
Megapixels @ Megahertz -- The AGIPD High-Speed Cameras for the European XFEL
The European XFEL is an extremely brilliant Free Electron Laser Source with a
very demanding pulse structure: trains of 2700 X-Ray pulses are repeated at 10
Hz. The pulses inside the train are spaced by 220 ns and each one contains up
to photons of 12.4 keV, while being fs in length. AGIPD,
the Adaptive Gain Integrating Pixel Detector, is a hybrid pixel detector
developed by DESY, PSI, and the Universities of Bonn and Hamburg to cope with
these properties. It is a fast, low noise integrating detector, with single
photon sensitivity (for keV) and a large dynamic
range, up to photons at 12.4 keV. This is achieved with a charge
sensitive amplifier with 3 adaptively selected gains per pixel. 352 images can
be recorded at up to 6.5 MHz and stored in the in-pixel analogue memory and
read out between pulse trains. The core component of this detector is the AGIPD
ASIC, which consists of pixels of . Control of the ASIC's image acquisition and analogue readout is
via a command based interface. FPGA based electronic boards, controlling ASIC
operation, image digitisation and 10 GE data transmission interface AGIPD
detectors to DAQ and control systems. An AGIPD 1 Mpixel detector has been
installed at the SPB experimental station in August 2017, while a second one is
currently commissioned for the MID endstation. A larger (4 Mpixel) AGIPD
detector and one to employ Hi-Z sensor material to efficiently register photons
up to keV are currently under construction.Comment: submitted to the proceedings of the ULITIMA 2018 conference, to be
published in NIM
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