Stopping conflict minerals with the OECD guidance for responsible mineral supply chains: status quo in Europe

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New Constraints on Hidden Photons using Very High Energy Gamma-Rays from the Crab Nebula

Extensions of the standard model of particle physics, in particular those based on string theory, often predict a new U(1) gauge symmetry in a hidden sector. The corresponding gauge boson, called hidden photon, naturally interacts with the ordinary photon via gauge kinetic mixing, leading to photon - hidden photon oscillations. In this framework, one expects photon disappearance as a function of the mass of the hidden photon and the mixing angle, loosely constrained from theory. Several experiments have been carried out or are planned to constrain the mass-mixing plane. In this contribution we derive new constraints on the hidden photon parameters, using very high energy gamma-rays detected from the Crab Nebula, whose broad-band spectral characteristics are well understood. The very high energy gamma-ray observations offer the possibility to provide bounds in a broad mass range at a previously unexplored energy and distance scale. Using existing data that were taken with several Cherenkov telescopes, we discuss our results in the context of current constraints and consider the possibilities of using astrophysical data to search for hidden photon signatures.Comment: Proceedings of the "Heidelberg International Symposium on High Energy Gamma-Ray Astronomy", Heidelberg, Germany, July 7-11, 2008, submitted to AIP Conference Proceedings. 4 pages, 2 figures, 1 tabl

Exponential Trends in Flowback Chemistry From a Hydraulically Stimulated Deep Geothermal Borehole in Granite; Pohang, South Korea

Samples of flowback water from a 4.3 km deep geothermal borehole in granite (Pohang, South Korea) were collected following a period of hydraulic stimulation by injection of surface water. Electrical conductivity, temperature and water chemistry of the flowback water were measured. To a first approximation, the data conform closely to a simple ‘mixing tank’ model, with an exponential trend between two end members: an initial injected surface water to a more brackish ‘resident groundwater’ composition. Significant deviation from the ‘mixing tank’ trend would be an indication of significant recent water-rock interaction or other anomalous factors. Such a deviation can tentatively be seen in Na+/Cl- data, especially between 88 and 200 m3 flowback (2.8 to 8.8 hr)

Rapid water-rock interactions evidenced by hydrochemical evolution of flowback fluid during hydraulic stimulation of a deep geothermal borehole in granodiorite : Pohang, Korea

Flowback water from the 4215 m deep (True Vertical Depth) PX-1 borehole, following the August 2017 hydraulic stimulation of a granodiorite geothermal reservoir in Pohang, South Korea, was monitored for a suite of physicochemical, chemical and isotopic parameters. The results provide unique insights into mixing processes, fluid evolution and rapid water-rock interaction in a deep geothermal system. Injected water for stimulation was relatively fresh, oxidising surface water, with temperature 29.5 °C and pH c. 6.5. The flowback water showed an increasing content of most solutes, with the evolution conforming to an exponential ‘flushing’ model for conservative solutes such as chloride. Flowback water became progressively Na–Cl dominated, with a circumneutral pH (7.1) and negative oxidation-reduction potential (c. −180 mV). Some solutes (including, Na, K and Si) increased more rapidly than a flushing model would suggest, implying that these had been acquired by the flowback water due to mineral hydrolysis. Stable isotopes of O and H indicate that initially meteoric waters have undergone geothermal oxygen isotope exchange with minerals. Evolution of redox species in recovered water suggests progressively oxidising zonation around the injection borehole in an otherwise reducing reservoir. Rapidly increasing silica concentrations in flowback water suggests extensive quartz dissolution and indicated a reservoir temperature of up to 169 °C. This lends plausible, if equivocal support to the hypothesis that quartz dissolution by injection water may have contributed to triggering movement on the pre-stressed fault associated with the November 2017 Mw 5.5 Pohang earthquake

A Concept Study for Feature Extraction and Modeling for Grapevine Yield Prediction

Yield prediction in viticulture is an especially challenging research direction within the field of yield prediction. The characteristics that determine annual grapevine yields are plentiful, difficult to obtain, and must be captured multiple times throughout the year. The processes currently used in grapevine yield prediction are based mainly on manually captured data and rigid statistical measures derived from historical insights. Experts for data acquisition are scarce, and statistical models cannot meet the requirements of a changing environment, especially in times of climate change. This paper contributes a concept on how to overcome those drawbacks, by (1) proposing a deep learning driven approach for feature recognition and (2) explaining how Extreme Gradient Boosting (XGBoost) can be utilized for yield prediction based on those features, while being explainable and computationally inexpensive. The methods developed will be influential for the future of yield prediction in viticulture

Efficient 2D filtering for cone-beam VOI reconstruction

Abstract—In some clinical applications, e.g., examination of deployed stents or coils during the intervention, only a small portion of the patient may be of diagnostic interest. For the sake of dose reduction to the patient, it is practicable to deploy a collimator to block radiation dose outside volume of interest (VOI). The resulting truncation, however, particularly in lateral direction, poses a challenge to the conventional reconstruction methods. The Approximated Truncation Robust Algorithm for Computed Tomography (ATRACT) is able to reconstruct images without the use of any explicit extrapolation schemes, even for highly truncated data. It is based on a decomposition of the standard ramp-filter into a local and a non-local filtering step, where the local step coincides with the two-dimensional (2D) Laplace operator and the non-local step is a 2D Radon-based filtering. In a practical implementation, the Radon-based filtering is not computationally efficient. In this paper, we present an improvement of the original ATRACT algorithm. The 2D Radon-based filtering step in the original algorithm is replaced by an analytical 2D convolution, resulting in a significant improvement in computational performance while retaining the image quality benefits of the VOI algorithm. Index Terms—Image reconstruction, volume of interest, trun-cation correction, dose reduction I

Stolniceni – Excavation results from the 2017 campaign

During extensive field work, different aspects of the large Tripolye settlement Stolniceni I in northwest Moldova were investigated by an international team. These investigations allow a reassessment of these population agglomerations from the first half of the 4th millennium BCE in Moldova and their comparison with more eastern Tripolye sites. The investigations carried out in 2017 included the completion of the archaeo-magnetic survey of the settlement and the targeted archaeological excavations of various types of contexts. Besides the investigation of a ditch enclosing the site and test trenches in different parts of the settlement, the excavations focused mainly on two areas in the north of the settlement: On the one hand, excavations were carried out in a pottery production complex, including the uncovering of a pottery kiln, several pits and a dwelling. On the other hand, one specific ‘ash-mound-like’ anomaly was investigated which are arranged in regular intervals at the periphery of the settlement. The archaeological excavations were accompanied by comprehensive archaeobotanical analyses, which provide an insight into the subsistence and wood selection in the settlement, as well as permitting environmental reconstructions. A larger series of 14C-datings proves the occupation of the settlement Stolniceni I over a longer period between about 3925 and 3700 BCE

Induced seismicity risk analysis of the hydraulic stimulation of a geothermal well on Geldinganes, Iceland

The rapid increase in energy demand in the city of Reykjavik has posed the need for an additional supply of deep geothermal energy. The deep-hydraulic (re-)stimulation of well RV-43 on the peninsula of Geldinganes (north of Reykjavik) is an essential component of the plan implemented by Reykjavik Energy to meet this energy target. Hydraulic stimulation is often associated with fluid-induced seismicity, most of which is not felt on the surface but which, in rare cases, can be a nuisance to the population and even damage the nearby building stock. This study presents a first-of-its-kind pre-drilling probabilistic induced seismic hazard and risk analysis for the site of interest. Specifically, we provide probabilistic estimates of peak ground acceleration, European microseismicity intensity, probability of light damage (damage risk), and individual risk. The results of the risk assessment indicate that the individual risk within a radius of 2 km around the injection point is below 0.1 micromorts, and damage risk is below 10−2, for the total duration of the project. However, these results are affected by several orders of magnitude of variability due to the deep uncertainties present at all levels of the analysis, indicating a critical need in updating this risk assessment with in situ data collected during the stimulation. Therefore, it is important to stress that this a priori study represents a baseline model and starting point to be updated and refined after the start of the project