Suchergebnisse

The groups presently pursuing neutrino telescope projects in the Mediterranean Sea, ANTARES, NEMO, and NESTOR, have formed the new KM3NeT consortium to study the construction of a cubic kilometre-scale neutrino telescope for the Northern hemisphere. This challenging project will require the installation of thousands of photon detectors with their related electronics and calibration systems several kilometres below the sea level. The realization of this project will provide the scientific community with a very powerful instrument to study many astrophysical objects, including supernova explosions, active galactic nuclei, gamma-ray bursts and possibly also dark matter. Numerous instruments of different types (photon detectors, hydrophones, compasses, tilt-meters, etc.) will be connected through electro-optical cables to form a very large network of sensors operating in a difficult environment. The construction of this detector will require the solution of technological problems common to many deep submarine installations, and will help pave the way for other deep-sea research facilities. In April 2008 the KM3NeT consortium has reached the important milestone of the publication of the Conceptual Design Report (CDR) for the KM3NeT telescope. The European Union - funded 3 year Design Study phase has now passed its mid-way point and will culminate in 2009 with the writing of the KM3NeT Technical Design Report (TDR), detailing the most promising technologies and the expected physics performance of the future detector. Concurrent with the publication of the CDR an EU funded Preparatory Phase began which will lead to the telescope construction. Aspects of the KM3NeT project related to deep-sea infrastructure, deployment and operation are reviewed in this report. ; This work is supported through the EU-funded FP6 KM3NeT Design Study Contract No. 011937. The author acknowledges the financial support from CSIC, JAE-Doc research grant.

Using empirical case materials from the Philippines and referring to rich experiences from different countries historically, this book offers conceptual and practical conclusions that have far-reaching implications for land reform throughout the world. Examining land reform theory and practice, this book argues that conventional practices have excluded a significant portion of land-based production and distribution relationships, while they have inadvertently included land transfers that do not constitute real redistributive reform. By direct implication, this book is a critique of both mainstream market led agrarian reform and conventional state-led land reform. It offers an alternative perspective on how to move forward in theory and practice and opens new paths in land policy research.

This article belongs to a special issue: 43rd Annual UIA Symposium 23—25 April 2014 CSIC Madrid, Spain. Edited By Margaret Lucas and Enrique Riera ; [EN] Underwater ultrasonic transducers are commonly used for marine applications including communication and positioning systems. In this work, an ultrasonic transmitter transducer developed for the very large underwater neutrino telescope KM3NeT positioning is presented. The telescope infrastructure will have some degree of motion due to sea current; hence a positioning system is needed in order to monitor the position of the optical sensors. For this purpose, a reliable and affordable positioning based on acoustic systems is used. The ultrasound transmitter prototype developed as part of the positioning system is composed of a commercial FFR transducer and specifically designed electronics to optimize the system and fulfil the requirements of the KM3NeT infrastructure. The transmitter is able to generate high-power short signals with arbitrary waveform in a range of 20 kHz - 40 kHz and withstand high pressures. Signal processing techniques such as advanced cross-correlation methods and filtering as well as broad-band ultrasound signals are also applied for optimizing the acoustic emission and position detection. The work done for a precise laboratory testing and optimization of the system is described. The prototype has been integrated in the ANTARES neutrino telescope for testing its accuracy and the reach in situ. The test results obtained are also presented in this communication. ; This work has been supported by the Ministerio de Economía y Competitividad (Spanish Government), project ref. FPA2012-37528-C02-02, Multidark (CSD2009-00064) and the European 7th Framework Programme, Grant no. 212525. ; Saldaña Coscollar, M.; Adrián Martínez, S.; Bou Cabo, M.; Felis Enguix, I.; Larosa, G.; Llorens Alvarez, CD.; Martínez Mora, JA. (2015). Ultrasonic transmitter for positioning of the large underwater neutrino telescope KM3NeT. Physics Procedia. 63:195-200. ...

Under the terms of the Creative Commons Attribution License 3.0 (CC-BY). ; The concept of thermophase refers to the appearance of a phase gradient inside a superconductor originating from the presence of an applied temperature bias across it. The resulting supercurrent flow may, in suitable conditions, fully counterbalance the temperature-bias-induced quasiparticle current therefore preventing the formation of any voltage drop, i.e., a thermovoltage, across the superconductor. Yet, the appearance of a thermophase is expected to occur in Josephson-coupled superconductors as well. Here, we theoretically investigate the thermoelectric response of a thermally biased Josephson junction based on a ferromagnetic insulator. In particular, we predict the occurrence of a very large thermophase that can reach π/2 across the contact for suitable temperatures and structure parameters; i.e., the quasiparticle thermal current can reach the critical current. Such a thermophase can be several orders of magnitude larger than that predicted to occur in conventional Josephson tunnel junctions. In order to assess experimentally the predicted very large thermophase, we propose a realistic setup realizable with state-of-the-art nanofabrication techniques and well-established materials, based on a superconducting quantum interference device. This effect could be of strong relevance in several low-temperature applications, for example, for revealing tiny temperature differences generated by coupling the electromagnetic radiation to one of the superconductors forming the junction. ; F. G. acknowledges the Marie Curie Initial Training Action (ITN) Q-NET 264034 and the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement No. 615187-COMANCHE for partial financial support. The work of F.S.B has been supported by the Spanish Ministry of Economy and Competitiveness under Project No. FIS2011-28851-C02-02, and the work of T. T. H. has been supported by the ERC (Grant No. 240362-Heattronics) and the Academy of Finland through its Center of Excellence program. ; Peer Reviewed

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AbstractWe study the detection and the reconstruction of a large very dense subgraph in a social graph with n nodes and m edges given as a stream of edges, when the graph follows a power law degree distribution, in the regime when
$m=O(n. \log n)$
. A subgraph S is very dense if it has
$\Omega(|S|^2)$
edges. We uniformly sample the edges with a Reservoir of size
$k=O(\sqrt{n}.\log n)$
. Our detection algorithm checks whether the Reservoir has a giant component. We show that if the graph contains a very dense subgraph of size
$\Omega(\sqrt{n})$
, then the detection algorithm is almost surely correct. On the other hand, a random graph that follows a power law degree distribution almost surely has no large very dense subgraph, and the detection algorithm is almost surely correct. We define a new model of random graphs which follow a power law degree distribution and have large very dense subgraphs. We then show that on this class of random graphs we can reconstruct a good approximation of the very dense subgraph with high probability. We generalize these results to dynamic graphs defined by sliding windows in a stream of edges.

International audience ; In order to stabilize the global climate the world's governments must make significant commitments to drastically reduce global greenhouse gas (GHG) emissions. One of the most promising methods of curbing GHG emissions is a world transition from fossil fuels to renewable sources of energy. Solar photovoltaic (PV) cells offer a technically sustainable solution to the projected enormous future energy demands. This article explores utilizing industrial symbiosis to obtain economies of scale and increased manufacturing efficiencies for solar photovoltaic cells in order for solar electricity to compete economically with fossil fuel-fired electricity. The state of PV manufacturing, the market and the effects of scale on both are reviewed. Government policies necessary to construct a multi-gigaWatt PV factory and complimentary policies to protect existing solar companies are outlined and the technical requirements for a symbiotic industrial system are explored to increase the manufacturing efficiency while improving the environmental impact of PV. The results of the analysis show that an 8-factory industrial symbiotic system can be viewed as a medium-term investment by any government, which will not only obtain direct financial return, but also an improved global environment. The technical concepts and policy limitations to this approach were analyzed and it was found that symbiotic growth will help to mitigate many of the limitations of PV and is likely to catalyze mass manufacturing of PV by transparently demonstrating that large scale PV manufacturing is technically feasible and reaches an enormous untapped market for PV with low costs.