61 research outputs found

    Signatures of cosmic tau-neutrinos

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    The importance and signatures of cosmic tau--(anti)neutrinos have been studied for upward-- and downward--going μ−+μ+\mu^-+\mu^+ and hadronic shower event rates relevant for present and future underground water or ice detectors, utilizing the unique and reliable ultrasmall--xx predictions of the dynamical (radiative) parton model. The upward--going μ−+μ+\mu^- +\mu^+ event rates calculated just from cosmic νμ+νˉμ\nu_{\mu}+\bar{\nu}_{\mu} fluxes are sizeably enhanced by taking into account cosmic ντ+νˉτ\nu_{\tau}+ \bar{\nu}_{\tau} fluxes and their associated τ−+τ+\tau^- +\tau^+ fluxes as well. The coupled transport equations for the upward--going ν(−)τ\stackrel{(-)}{\nu}_{\tau} flux traversing the Earth imply an enhancement of the attenuated and regenerated ν(−)τ\stackrel{(-)}{\nu}_{\tau} flux typically around 104−10510^4-10^5 GeV with respect to the initial cosmic flux. This enhancement turns out to be smaller than obtained so far, in particular for flatter initial cosmic fluxes behaving like Eν−1E_{\nu}^{-1}. Downward--going μ−+μ+\mu^- +\mu^+ events and in particular the background--free and unique hadronic `double bang' and `lollipop' events allow to test downward--going cosmic ντ+νˉτ\nu_{\tau} +\bar{\nu}_{\tau} fluxes up to about 10910^9 GeV.Comment: 32 pages, 6 figures; Added reference

    How to identify groundwater-caused thermal anomalies in lakes based on multi-temporal satellite data in semi-arid regions

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    The deduction by conventional means of qualitative and quantitative information about groundwater discharge into lakes is complicated. Nevertheless, at least for semi-arid regions with limited surface water availability, this information is crucial to ensure future water availability for drinking and irrigation purposes. <br><br> Overcoming this lack of discharge information, we present a satellite-based multi-temporal sea-surface-temperature (SST) approach. It exploits the occurrence of thermal anomalies to outline groundwater discharge locations using the example of the Dead Sea. Based on a set of 19 Landsat Enhanced Thematic Mapper (ETM+) images 6.2 (high gain), recorded between 2000 and 2002, we developed a novel approach which includes (i) an objective exclusion of surface-runoff-influenced data which would otherwise lead to erroneous results and (ii) a temporal SST variability analysis based on six statistical measures amplifying thermal anomalies caused by groundwater. <br><br> After excluding data influenced by surface runoff, we concluded that spatial anomaly patterns of the standard deviation and range of the SST data series spatially fit best to in situ observed discharge locations and, hence, are most suitable for detecting groundwater discharge sites

    Intrinsic Superconductivity at 25 K in Highly Oriented Pyrolytic Graphite

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    High resolution magnetoresistance data in highly oriented pyrolytic graphite thin samples manifest non-homogenous superconductivity with critical temperature Tc∼25T_c \sim 25 K. These data exhibit: i) hysteretic loops of resistance versus magnetic field similar to Josephson-coupled grains, ii) quantum Andreev's resonances and iii) absence of the Schubnikov-de Haas oscillations. The results indicate that graphite is a system with non-percolative superconducting domains immersed in a semiconducting-like matrix. As possible origin of the superconductivity in graphite we discuss interior-gap superconductivity when two very different electronic masses are present.Comment: 5 pages, 3 figure

    Quantum Andreev Oscillations in normal-superconducting-normal nanostructures

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    We show that the voltage drop of specially prepared normal-superconducting-normal nanostructures show quantum Andreev oscillations as a function of magnetic field or input current. These oscillations are due to the interference of the electron wave function between the normal parts of the structure that act as reflective interfaces, i.e. our devices behave as a Fabry-Perot interferometer for conduction electrons. The observed oscillations and field periods are well explained by theory.Comment: 5 pages and 4 figure

    QUBE – Quantum Key Distribution with CubeSat

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    QUBE (Quantum Key Distribution with CubeSat) is one out of three pilot projects in the frame of the national German initiative QUTEGA to promote quantum technologies. The project is funded by the German Federal Ministry of Education and Research (BMBF) with co-funding of industry as preparation for the European flagship on Quantum Technology. With the current development pace in quantum computation, it has been predicted that in less than two decades quantum computers will be able to break encryption codes deployed today, which are currently based on mathematical problems difficult to solve with classical computation. This shows the urgent need for quantum-safe encryption that is resistant to attacks of both, quantum and classical, computers. A long term solution for quantumsafe encryption is the use of a completely random, so-called One-Time-Pad generated with true Random Number Generation (RNG) and distributed via Quantum Key Distribution (QKD). The QKD in fiber networks is limited to approx. 100 km due to damping within the carrier medium. For longer distances so far only satellite based techniques are able to transmit the keys. As a pathfinder, QUBE plans perform an in-orbit demonstration of the core technologies on a CubeSat platform

    New perspectives on interdisciplinary earth science at the Dead Sea: The DESERVE project

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    The Dead Sea region has faced substantial environmental challenges in recent decades, including water resource scarcity, ~ 1 m annual decreases in the water level, sinkhole development, ascending-brine freshwater pollution, and seismic disturbance risks. Natural processes are significantly affected by human interference as well as by climate change and tectonic developments over the long term. To get a deep understanding of processes and their interactions, innovative scientific approaches that integrate disciplinary research and education are required. The research project DESERVE (Helmholtz Virtual Institute Dead Sea Research Venue) addresses these challenges in an interdisciplinary approach that includes geophysics, hydrology, and meteorology. The project is implemented by a consortium of scientific institutions in neighboring countries of the Dead Sea (Israel, Jordan, Palestine Territories) and participating German Helmholtz Centres (KIT, GFZ, UFZ). A new monitoring network of meteorological, hydrological, and seismic/geodynamic stations has been established, and extensive field research and numerical simulations have been undertaken. For the first time, innovative measurement and modeling techniques have been applied to the extreme conditions of the Dead Sea and its surroundings. The preliminary results show the potential of these methods. First time ever performed eddy covariance measurements give insight into the governing factors of Dead Sea evaporation. High-resolution bathymetric investigations reveal a strong correlation between submarine springs and neo-tectonic patterns. Based on detailed studies of stratigraphy and borehole information, the extension of the subsurface drainage basin of the Dead Sea is now reliably estimated. Originality has been achieved in monitoring flash floods in an arid basin at its outlet and simultaneously in tributaries, supplemented by spatio-temporal rainfall data. Low-altitude, high resolution photogrammetry, allied to satellite image analysis and to geophysical surveys (e.g. shear-wave reflections) has enabled a more detailed characterization of sinkhole morphology and temporal development and the possible subsurface controls thereon. All the above listed efforts and scientific results take place with the interdisciplinary education of young scientists. They are invited to attend joint thematic workshops and winter schools as well as to participate in field experiments

    The Digital MIQE Guidelines Update: Minimum Information for Publication of Quantitative Digital PCR Experiments for 2020

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    Digital PCR (dPCR) has developed considerably since the publication of the Minimum Information for Publication of Digital PCR Experiments (dMIQE) guidelines in 2013, with advances in instrumentation, software, applications, and our understanding of its technological potential. Yet these developments also have associated challenges; data analysis steps, including threshold setting, can be difficult and preanalytical steps required to purify, concentrate, and modify nucleic acids can lead to measurement error. To assist independent corroboration of conclusions, comprehensive disclosure of all relevant experimental details is required. To support the community and reflect the growing use of dPCR, we present an update to dMIQE, dMIQE2020, including a simplified dMIQE table format to assist researchers in providing key experimental information and understanding of the associated experimental process. Adoption of dMIQE2020 by the scientific community will assist in standardizing experimental protocols, maximize efficient utilization of resources, and further enhance the impact of this powerful technology

    The ScaleX campaign: scale-crossing land-surface and boundary layer processes in the TERENO-preAlpine observatory

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    Augmenting long-term ecosystem-atmosphere observations with multidisciplinary intensive campaigns aims at closing gaps in spatial and temporal scales of observation for energy- and biogeochemical cycling, and at stimulating collaborative research. ScaleX is a collaborative measurement campaign, co-located with a long-term environmental observatory of the German TERENO (TERrestrial ENvironmental Observatories) network in mountainous terrain of the Bavarian Prealps, Germany. The aims of both TERENO and ScaleX include the measurement and modeling of land-surface atmosphere interactions of energy, water, and greenhouse gases. ScaleX is motivated by the recognition that long-term intensive observational research over years or decades must be based on well-proven, mostly automated measurement systems, concentrated on a small number of locations
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