Riverine transfer of heavy metals from Patagonia to the southwestern Atlantic Ocean

The occurrence and geochemical behaviour of Fe, Mn, Pb, Cu, Ni, Cr, Zn and Co are studied in riverine detrital materials transported by Patagonian rivers. Their riverine inputs have been estimated and the nature of these inputs to the Atlantic Ocean is discussed. Most of the metals are transported to the ocean via the suspended load; there is evidence that Fe oxides and organic matter are important phases controlling their distribution in the detrital non-residual fraction. Most heavy metal concentrations found in bed sediments, in suspended matter, and in the dissolved load of Patagonian rivers were comparable to those reported for non-polluted rivers. There is indication that human activity is altering riverine metal inputs to the ocean. In the northern basins – and indicatinganthropogenic effects – heavy metals distribution in the suspended load is very different from that found in bed sediments. The use of pesticides in the Negro River valley seems correlated with increased riverine input of Cu, mostly bound to the suspended load. The Deseado and Chico Rivers exhibit increased specific yield of metals as a consequence of extended erosion within their respective basins. The Santa Cruz is the drainage basin least affected by human activity and its metal-exporting capacity should be taken as an example of a relatively unaffected large hydrological system. In contrast, coal mining modifies the transport pattern of heavy metals in the Gallegos River, inasmuch as they are exported to the coastal zone mainly as dissolved load

Conceptualizing human resilience in the face of the global epidemiology of cyber attacks

Computer security is a complex global phenomenon where different populations interact, and the infection of one person creates risk for another. Given the dynamics and scope of cyber campaigns, studies of local resilience without reference to global populations are inadequate. In this paper we describe a set of minimal requirements for implementing a global epidemiological infrastructure to understand and respond to large-scale computer security outbreaks. We enumerate the relevant dimensions, the applicable measurement tools, and define a systematic approach to evaluate cyber security resilience. From the experience in conceptualizing and designing a cross-national coordinated phishing resilience evaluation we describe the cultural, logistic, and regulatory challenges to this proposed public health approach to global computer assault resilience. We conclude that mechanisms for systematic evaluations of global attacks and the resilience against those attacks exist. Coordinated global science is needed to address organised global ecrime

From adoption potential to transformative learning around Conservation Agriculture in Burkina Faso

Despite the substantial support of donors and development agencies, Conservation Agriculture (CA) has not moved from an invention to an innovation stage in sub-Saharan Africa. The results of the common strategy to transfer the technology from science through donors to farms in a top down manner have been disappointing (with Burkina Faso being a typical case). To make things worse, assessing the actual levels of adoption has been problematic due to the biases and weaknesses of the applied methods - including the Qualitative expert Assessment Tool for CA adoption in Africa (QAToCA). However, to promote sustainable farming pathways such as CA, we still see a need for methods that help to understand and foster transitions in agricultural practices. The purpose of this work is thus to design an approach that combines current insights in learning theory and practice. The starting point of the process is an assessment of the agro-ecosystem health of the farming system of interest, by exploring the social, economic and ecological characteristics of the system. Second, to create space for social learning, we apply participatory stakeholder mapping to make the roles, values, interests, and capabilities of the different stakeholders explicit. Third, the stakeholders jointly work on a historical timeline of CA promotion to identify key events, drivers and constraints of the innovation process. Then, to support individual experience, dialogue and different ways of learning, the stakeholders together create non-scripted, non-edited videos of their perspectives on challenges in the farming system. These videos are then screened in a multi-stakeholder meeting to stimulate the discussion on the innovation potential of CA. Discussions are structured by the framework of QAToCA. The results of all exercises feed into a proposal for an improved promotion of CA. We tested the approach in a farming community in Koumbia, Burkina Faso. The described learning elements helped to moderate the expert bias and rigidity of QAToCA. As a learning outcome, the results underlined that CA uptake will depend on the adaptation to the local conditions (e.g. competition over crop residue exacerbated by free-grazing) in order become a viable agricultural system

Controlling state explosion during automatic verification of delay-insensitive and delay-constrained VLSI systems using the POM verifier

Delay-insensitive VLSI systems have a certain appeal on the ground due to difficulties with clocks; they are even more attractive in space. We answer the question, is it possible to control state explosion arising from various sources during automatic verification (model checking) of delay-insensitive systems? State explosion due to concurrency is handled by introducing a partial-order representation for systems, and defining system correctness as a simple relation between two partial orders on the same set of system events (a graph problem). State explosion due to nondeterminism (chiefly arbitration) is handled when the system to be verified has a clean, finite recurrence structure. Backwards branching is a further optimization. The heart of this approach is the ability, during model checking, to discover a compact finite presentation of the verified system without prior composition of system components. The fully-implemented POM verification system has polynomial space and time performance on traditional asynchronous-circuit benchmarks that are exponential in space and time for other verification systems. We also sketch the generalization of this approach to handle delay-constrained VLSI systems

Leveraging private investment to expand renewable power generation: Evidence on financial additionality and productivity gains from Uganda

Effectively mitigating climate change entails a quick upscaling and redirection of electricity infrastructure investment. Given that the bulk of greenhouse gas emissions increases until 2050 will come from low- and middle-income countries, finding cost-effective ways to mitigate climate change while meeting development targets is essential. However, recent research has shown some of the limitations of broad financing mechanisms, such as the Clean Development Mechanism (CDM) and existing carbon markets. This has resulted in a growing interest in designing novel investment support schemes, such as modifications of targeted feed-in-tariffs (FiTs) that may be more cost effective and better targeted towards particular outcomes when compared to traditional deployment subsidies or broad financing mechanisms. We evaluate the design and outcomes of one such novel support schemes: the GET FiT (Global Energy Transfer Feed-in Tariff) investment support scheme in Uganda, which has attracted ~ 453 million USD in private sector investment for 17 small-scale renewable energy projects (solar, hydro, bagasse) in only three years. Using financial modelling on detailed project-level data, we find that the majority of projects were additional and would therefore not have been built without the subsidy. In addition, using firm-level panel data, we show that power outages hamper manufacturing performance in Uganda. In the absence of reliable outage-data for the entire Ugandan territory, we use nightlight variations to proxy changes in outages. We show that outages have declined substantially since the introduction of GET FiT. Yet, our analysis also demonstrates that programmes to incentivise additional renewable generation in developing countries funded internationally or domestically should liaise closely with grid authorities to ensure that supply does not outstrip demand.European Union’s Horizon 2020 INNOPATHS project (Grant agreement no. 730403) The Department of Land Economy and the School of Humanities and Social Sciences, University of Cambridge Heinrich Böll Foundation

Comb-calibrated solar spectroscopy through a multiplexed single-mode fiber channel

We investigate a new scheme for astronomical spectrograph calibration using the laser frequency comb at the Solar Vacuum Tower Telescope on Tenerife. Our concept is based upon a single-mode fiber channel, that simultaneously feeds the spectrograph with comb light and sunlight. This yields nearly perfect spatial mode matching between the two sources. In combination with the absolute calibration provided by the frequency comb, this method enables extremely robust and accurate spectroscopic measurements. The performance of this scheme is compared to a sequence of alternating comb and sunlight, and to absorption lines from Earth's atmosphere. We also show how the method can be used for radial-velocity detection by measuring the well-explored 5-minute oscillations averaged over the full solar disk. Our method is currently restricted to solar spectroscopy, but with further evolving fiber-injection techniques it could become an option even for faint astronomical targets.Comment: 21 pages, 11 figures. A video abstract for this paper is available on youtube. For watching the video, please follow https://www.youtube.com/watch?v=oshdZgrt89I . The video abstract is also available for streaming and download on the related article website of New Journal of Physic

The Luminosity Function of Lyman alpha Emitters at Redshift z=7.7

Lyman alpha (Lya) emission lines should be attenuated in a neutral intergalactic medium (IGM). Therefore the visibility of Lya emitters at high redshifts can serve as a valuable probe of reionization at about the 50% level. We present an imaging search for z=7.7 Lya emitting galaxies using an ultra-narrowband filter (filter width= 9A) on the NEWFIRM imager at the Kitt Peak National Observatory. We found four candidate Lya emitters in a survey volume of 1.4 x 10^4 Mpc^3, with a line flux brighter than 6x10^-18 erg/cm^2/s (5 sigma in 2" aperture). We also performed a detailed Monte-Carlo simulation incorporating the instrumental effects to estimate the expected number of Lya emitters in our survey, and found that we should expect to detect one Lya emitter, assuming a non-evolving Lya luminosity function (LF) between z=6.5 and z=7.7. Even if one of the present candidates is spectroscopically confirmed as a z~8 Lya emitter, it would indicate that there is no significant evolution of the Lya LF from z=3.1 to z~8. While firm conclusions would need both spectroscopic confirmations and larger surveys to boost the number counts of galaxies, we successfully demonstrate the feasibility of sensitive near-infrared (1.06 um) narrow-band searches using custom filters designed to avoid the OH emission lines that make up most of the sky background.Comment: Published in ApJ, 3 figure