Search results for "ddc:"
showing 10 items of 3080 documents
Environmental impact of early Basque mining and smelting recorded in a high ash minerogenic peat deposit.
2004
International audience; More than four metres of core, covering almost 5000 years of deposition, were collected in a high ash minerogenic peat deposit located in the High Aldudes valley (Basque country), an area well known for its mineral abundance, exploited from Roman Times at least.Although minerogenic peatlands are not generally considered as the best archives to reconstruct past atmospheric metal deposition history, lead isotopic geochemistry demonstrates the integrity of the Pb record at least within the three upper meters; that is to say over the last four millennia.Zn, Cd and Cumay have been widely redistributed either by biological cycling, advective groundwater movements, or diffu…
Overview: On the transport and transformation of pollutants in the outflow of major population centres - Observational data from the EMeRGe European …
2022
Megacities and other major population centres (MPCs) worldwide are major sources of air pollution, both locally as well as downwind. The overall assessment and prediction of the impact of MPC pollution on tropospheric chemistry are challenging. The present work provides an overview of the highlights of a major new contribution to the understanding of this issue based on the data and analysis of the EMeRGe (Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales) international project. EMeRGe focuses on atmospheric chemistry, dynamics, and transport of local and regional pollution originating in MPCs. Airborne measurements, taking advantage of …
Sensitivity of low-level clouds and precipitation to anthropogenic aerosol emission in southern West Africa: a DACCIWA case study
2021
Abstract. During the West African summer monsoon, pollutants emitted in urbanized coastal areas modify cloud cover and precipitation patterns. The Dynamics-Aerosol-Chemistry-Cloud-Interactions in West Africa (DACCIWA) field campaign provided numerous aircraft-based and ground-based observations, which are used here to evaluate two experiments made with the coupled WRF-CHIMERE model, integrating both the direct and indirect aerosol effect on meteorology. During one well-documented week (1–7 July 2016), the impacts of anthropogenic aerosols on the diurnal cycle of low-level clouds and precipitation are analyzed in detail using high and moderate intensity of anthropogenic emissions in the expe…
Diffusion of single molecular and macromolecular probes during the free radical bulk polymerization of MMA : towards a better understanding of the Tr…
2016
Free radical bulk polymerizations exhibit complex kinetics due to the viscosity increase during the polymerization process. Especially the termination rate constant can be strongly influenced by the mobility of polymer chains in the polymerization mixture. As a consequence an autoacceleration period, the so-called Trommsdorff effect, can be observed often. In order to investigate this behaviour on a nanoscopic scale, we directly visualized the mobility of molecules and macromolecules in polymerizing MMA solutions using a combination of highly sensitive fluorescence correlation spectroscopy and widefield fluorescence microscopy. For this purpose, rather monodisperse PMMA chains were synthesi…
Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface
2008
Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data a…
Relaxation and charge transport in mixtures of zwitterionic polymers and inorganic salts
2009
Dielectric spectroscopy is employed to analyze the molecular dynamics and the charge transport in mixtures of zwitterionic polymers of the type poly(3-[N-(omega-methacryloyloxyalkyl)-N, N-dimethylammonio]propanesulfonate) with sodium iodide in the frequency range of 10(2) Hz-10(7) Hz and in the temperature range of 110 K-400 K. The amount of inorganic salt added varies from 0-200 mol-% relative to the number of zwitterionic groups present in the polymer, contributing strongly to the conductivity. One relaxation process is observed whose relaxation rate depends strongly on the length of the aliphatic spacer between the polymethacrylate main chain and the zwitterionic group. Exhibiting an Arr…
Efficient size control of copper nanoparticles generated in irradiated aqueous solutions of star-shaped polyelectrolyte containers
2015
Physical chemistry, chemical physics 17(17), 11490-11498(2015). doi:10.1039/C5CP00269A
Control of dataset bias in combined Affymetrix cohorts of triple negative breast cancer
2014
AbstractHeterogenous subtypes of breast cancer need to be analyzed separately. Pooling of datasets can provide reasonable sample sizes but dataset bias is an important concern. We assembled a combined dataset of 579 Affymetrix microarrays from triple negative breast cancer (TNBC) in Gene Expression Omnibus (GEO) series GSE31519. We developed a method for selecting comparable datasets and to control for the amount of dataset bias of individual probesets.
Heterogeneous contributions of change in population distribution of body mass index to change in obesity and underweight
2021
From 1985 to 2016, the prevalence of underweight decreased, and that of obesity and severe obesity increased, in most regions, with significant variation in the magnitude of these changes across regions. We investigated how much change in mean body mass index (BMI) explains changes in the prevalence of underweight, obesity, and severe obesity in different regions using data from 2896 population-based studies with 187 million participants. Changes in the prevalence of underweight and total obesity, and to a lesser extent severe obesity, are largely driven by shifts in the distribution of BMI, with smaller contributions from changes in the shape of the distribution. In East and Southeast Asia…
Intricate decision making : ambivalences and barriers when fulfilling an advance directive
2016
Lars Schröder,1 Gerhard Homme,1,2 Stephan Sahm3,4 1Department of Gynecology and Obstetrics, Center of Integrated Oncology, University Hospital Bonn, Bonn, 2Institute of Medical Biometry, Epidemiology and Informatics, Johannes Gutenberg University, Mainz, 3Department of Gastroenterology and Oncology, Ketteler Hospital, Offenbach, 4Institute for Ethics and History of Medicine, Johann Wolfgang Goethe University, Frankfurt, Germany Background: Despite a recent statutory ruling stating the binding nature of advance directives (ADs), only a minority of the population has signed one. Yet, a majority deem it of utmost importance to ensure their wishes are followed through in case they are …