329 research outputs found
Comparison between the in situ and laboratory water retention curves for a silty sand
After an extreme rainfall event in May 2002 a series of landslides occurred in Ruedlingen in Canton Schaffhausen, North Switzerland. A 38° steep slope has been chosen in this area beside the river Rhine to carry out an artificial rainfall experiment to investigate the dependence between rainfall, suction, saturation and shear resistance. Two sprinkling experiments were conducted to represent an extreme rainfall event, the second of which resulted in failure of 130 m 3 of the slope. Several cycles of wetting and drying were applied to the soil and suction and volumetric water content were measured at different depths in three locations of the slope, by which in-situ Water Retention Curves (WRC) can be derived. The WRC of an undisturbed sample was also determined from laboratory test. The in situ and laboratory WRCs are compared in this paper and the differences will be discussed
Mountain Risks: two case histories of landslides induced by artificial rainfall on steep slopes
Mountainous areas tend to be exposed to an enhanced risk of damage caused by natural hazards; most often exacerbated by the topography (leading to gravitational mass movements such as avalanches, landslides, mud and debris flows). This contribution compares landslides induced by artificial rainfall on two different areas located in Switzerland. One field test site was located on slopes above Saas Balen (Gruben glacier, Canton Wallis, Switzerland) and was instrumented. Artificial rainfall tests were carried out in the summers of 1999 and 2000 to investigate hydro-mechanical mechanisms of instability (Teysseire et al., 2000). Shallow failure occurred in the steeper instrumented slope in 2000. The second test field is located near Ruedlingen (Canton Schaffhausen, Switzerland). A landslide triggering experiment was carried out there in autumn 2008 and spring 2009 to replicate the effects of a heavy rainfall event of May 2002, in which 100 mm rain fell in 40 minutes, causing 42 superficial landslides. The slope was subjected to extreme rainfall by artificial means in October 2008 and in March 2009, triggering about 130 m3 of debris. Infiltration of rainfall has led to surface instability slopes in an alpine moraine (Gruben) and in silty sand (Ruedlingen). Both slopes were steeper than the internal angle of friction, having different initial degrees of saturation and suction. The hydromechanical behaviour of these two field full scale landslides will be compared, trying to expose a deeper understanding of the rainfall induced failure mechanisms
An ion trap built with photonic crystal fibre technology
We demonstrate a surface-electrode ion trap fabricated using techniques
transferred from the manufacture of photonic-crystal fibres. This provides a
relatively straightforward route for realizing traps with an electrode
structure on the 100 micron scale with high optical access. We demonstrate the
basic functionality of the trap by cooling a single ion to the quantum ground
state, allowing us to measure a heating rate from the ground state of 787(24)
quanta/s. Variation of the fabrication procedure used here may provide access
to traps in this geometry with trap scales between 100 um and 10 um.Comment: 6 pages, 4 figure
Trapping and ground-state cooling of
We demonstrate co-trapping and sideband cooling of a ion
pair in a cryogenic Paul trap. We study the chemical lifetime of and
its dependence on the apparatus temperature, achieving lifetimes of up to
at 10 K. We demonstrate cooling of translational motion to an
average phonon number of 0.07(1), corresponding to a temperature of . Our results provide a basis for quantum logic spectroscopy experiments of
, as well as other light ions such as , , and
Can consumption predict advertising expenditures? The advertising-consumption relation before and after the dot-com crisis in Germany
Two contradictory schools of thought—the activists and the determinists—predict that either diffusion of knowledge (e.g., through advertising) leads to economic growth or that economic growth increases marketing and advertising activities. This study assesses the causal relation between corporate advertising expenditures and private consumption applying vector autoregressive (VAR) models to aggregate German quarterly data from 1991 to 2009. Results indicate a break in the advertising-consumption relation after the dot-com crisis. Hence, the macroeconomic advertising-consumption relation is not stable over time. Since 2001, consumption has Granger-caused advertising expenditures. This change suggests a higher relevance of consumer behavior for advertising budgeting decisions
Streaming Support for Data Intensive Cloud-Based Sequence Analysis
Cloud computing provides a promising solution to the genomics data deluge problem resulting from the advent of next-generation sequencing (NGS) technology. Based on the concepts of “resources-on-demand” and “pay-as-you-go”, scientists with no or limited infrastructure can have access to scalable and cost-effective computational resources. However, the large size of NGS data causes a significant data transfer latency from the client's site to the cloud, which presents a bottleneck for using cloud computing services. In this paper, we provide a streaming-based scheme to overcome this problem, where the NGS data is processed while being transferred to the cloud. Our scheme targets the wide class of NGS data analysis tasks, where the NGS sequences can be processed independently from one another. We also provide the elastream package that supports the use of this scheme with individual analysis programs or with workflow systems. Experiments presented in this paper show that our solution mitigates the effect of data transfer latency and saves both time and cost of computation
Review of the flood risk management system in Germany after the major flood in 2013
Widespread flooding in June 2013 caused damage costs of €6 to 8 billion in Germany, and awoke many memories of the floods in August 2002, which resulted in total damage of €11.6 billion and hence was the most expensive natural hazard event in Germany up to now. The event of 2002 does, however, also mark a reorientation toward an integrated flood risk management system in Germany. Therefore, the flood of 2013 offered the opportunity to review how the measures that politics, administration, and civil society have implemented since 2002 helped to cope with the flood and what still needs to be done to achieve effective and more integrated flood risk management. The review highlights considerable improvements on many levels, in particular (1) an increased consideration of flood hazards in spatial planning and urban development, (2) comprehensive property-level mitigation and preparedness measures, (3) more effective flood warnings and improved coordination of disaster response, and (4) a more targeted maintenance of flood defense systems. In 2013, this led to more effective flood management and to a reduction of damage. Nevertheless, important aspects remain unclear and need to be clarified. This particularly holds for balanced and coordinated strategies for reducing and overcoming the impacts of flooding in large catchments, cross-border and interdisciplinary cooperation, the role of the general public in the different phases of flood risk management, as well as a transparent risk transfer system. Recurring flood events reveal that flood risk management is a continuous task. Hence, risk drivers, such as climate change, land-use changes, economic developments, or demographic change and the resultant risks must be investigated at regular intervals, and risk reduction strategies and processes must be reassessed as well as adapted and implemented in a dialogue with all stakeholders
Restoration of Visual Function by Expression of a Light-Gated Mammalian Ion Channel in Retinal Ganglion Cells or ON-Bipolar Cells
Most inherited forms of blindness are caused by mutations that lead to photoreceptor cell death but spare second- and third-order retinal neurons. Expression of the light-gated excitatory mammalian ion channel light-gated ionotropic glutamate receptor (LiGluR) in retinal ganglion cells (RGCs) of the retina degeneration (rd1) mouse model of blindness was previously shown to restore some visual functions when stimulated by UV light. Here, we report restored retinal function in visible light in rodent and canine models of blindness through the use of a second-generation photoswitch for LiGluR, maleimide-azobenzene-glutamate 0 with peak efficiency at 460 nm (MAG0460). In the blind rd1 mouse, multielectrode array recordings of retinal explants revealed robust and uniform light-evoked firing when LiGluR-MAG0460 was targeted to RGCs and robust but diverse activity patterns in RGCs when LiGluR-MAG0460 was targeted to ON-bipolar cells (ON-BCs). LiGluR-MAG0460 in either RGCs or ON-BCs of the rd1 mouse reinstated innate light-avoidance behavior and enabled mice to distinguish between different temporal patterns of light in an associative learning task. In the rod-cone dystrophy dog model of blindness, LiGluR-MAG0460 in RGCs restored robust light responses to retinal explants and intravitreal delivery of LiGluR and MAG0460 was well tolerated in vivo. The results in both large and small animal models of photoreceptor degeneration provide a path to clinical translation
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Ten years of research on synergisms and antagonisms in chemical mixtures: A systematic review and quantitative reappraisal of mixture studies
Background
Several reviews of synergisms and antagonisms in chemical mixtures have concluded that synergisms are relatively rare. However, these reviews focused on mixtures composed of specific groups of chemicals, such as pesticides or metals and on toxicity endpoints mostly relevant to ecotoxicology. Doubts remain whether these findings can be generalised. A systematic review not restricted to specific chemical mixtures and including mammalian and human toxicity endpoints is missing.
Objectives
We conducted a systematic review and quantitative reappraisal of 10 years’ of experimental mixture studies to investigate the frequency and reliability of evaluations of mixture effects as synergistic or antagonistic. Unlike previous reviews, we did not limit our efforts to certain groups of chemicals or specific toxicity outcomes and covered mixture studies relevant to ecotoxicology and human/mammalian toxicology published between 2007 and 2017.
Data sources, eligibility criteria
We undertook searches for peer-reviewed articles in PubMed, Web of Science, Scopus, GreenFile, ScienceDirect and Toxline and included studies of controlled exposures of environmental chemical pollutants, defined as unintentional exposures leading to unintended effects. Studies with viruses, prions or therapeutic agents were excluded, as were records with missing details on chemicals’ identities, toxicities, doses, or concentrations.
Study appraisal and synthesis methods
To examine the internal validity of studies we developed a risk-of-bias tool tailored to mixture toxicology. For a subset of 388 entries that claimed synergisms or antagonisms, we conducted a quantitative reappraisal of authors’ evaluations by deriving ratios of predicted and observed effective mixture doses (concentrations).
Results
Our searches produced an inventory of 1220 mixture experiments which we subjected to subgroup analyses. Approximately two thirds of studies did not incorporate more than 2 components. Most experiments relied on low-cost assays with readily quantifiable endpoints. Important toxicity outcomes of relevance for human risk assessment (e.g. carcinogenicity, genotoxicity, reproductive toxicity, immunotoxicity, neurotoxicity) were rarely addressed. The proportion of studies that declared additivity, synergism or antagonisms was approximately equal (one quarter each); the remaining quarter arrived at different evaluations. About half of the 1220 entries were rated as “definitely” or “probably” low risk of bias. Strikingly, relatively few claims of synergistic or antagonistic effects stood up to scrutiny in terms of deviations from expected additivity that exceed the boundaries of acceptable between-study variability. In most cases, the observed mixture doses were not more than two-fold higher or lower than the predicted additive doses. Twenty percent of the entries (N = 78) reported synergisms in excess of that degree of deviation. Our efforts of pinpointing specific factors that predispose to synergistic interactions confirmed previous concerns about the synergistic potential of combinations of triazine, azole and pyrethroid pesticides at environmentally relevant doses. New evidence of synergisms with endocrine disrupting chemicals and metal compounds such as chromium (VI) and nickel in combination with cadmium has emerged.
Conclusions, limitations and implications
These specific cases of synergisms apart, our results confirm the utility of default application of the dose (concentration) addition concept for predictive assessments of simultaneous exposures to multiple chemicals. However, this strategy must be complemented by an awareness of the synergistic potential of specific classes of chemicals. Our conclusions only apply to the chemical space captured in published mixture studies which is biased towards relatively well-researched chemicals.European Commission, Directorate-General Joint Research Centre, Service Contract CCR.F.933992.X
The flood of June 2013 in Germany: how much do we know about its impacts?
In June 2013, widespread flooding and consequent damage and losses occurred
in Central Europe, especially in Germany. This paper explores what data are
available to investigate the adverse impacts of the event, what kind of
information can be retrieved from these data and how well data and
information fulfil requirements that were recently proposed for disaster
reporting on the European and international levels. In accordance with the
European Floods Directive (2007/60/EC), impacts on human health, economic
activities (and assets), cultural heritage and the environment are described
on the national and sub-national scale. Information from governmental reports
is complemented by communications on traffic disruptions and surveys of
flood-affected residents and companies.
Overall, the impacts of the flood event in 2013 were manifold. The study
reveals that flood-affected residents suffered from a large range of impacts,
among which mental health and supply problems were perceived more seriously
than financial losses. The most frequent damage type among affected companies
was business interruption. This demonstrates that the current scientific
focus on direct (financial) damage is insufficient to describe the overall
impacts and severity of flood events.
The case further demonstrates that procedures and standards for impact data
collection in Germany are widely missing. Present impact data in Germany are
fragmentary, heterogeneous, incomplete and difficult to access. In order to
fulfil, for example, the monitoring and reporting requirements of the Sendai
Framework for Disaster Risk Reduction 2015–2030 that was adopted in March
2015 in Sendai, Japan, more efforts on impact data collection are needed
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