Gateway diversity for a future high throughput satellite system

The continuous increase of traffic demands for satellite networks motivates the evolution of the telecommunication satellite technology towards wider channels and multiple beam operation with frequency re-use across the coverage. This is made possible by the use of higher frequency bands. Recent research projects 1,2 have investigated multi-beam coverages with more than 200 user beams operated in Ka band, to offer very large data throughputs over Europe. Since 2012, the European Commission project Broadband Access via integrated Terrestrial and Satellite systems (BATS) has explored a similar concept based on a dual satellite solution offering around 302 user beams over EU27 and Turkey, targeting 2020 timeframe, see Figure 1. In all these systems, so as to maximize the user link capacity, the whole civil band allocated to Fixed Satellite Services (FSS) in Ka band (20/30 GHz) is dedicated to the user links. The feeder links thus have to be operated in another band. An attractive option is to rely on Q/V bands (30/40 GHz) to provide the gateway-to-satellite links. Despite the large available bandwidths in Q/V band (5 GHz in each direction), the very large user aggregated bandwidths are required to implement several tens of gateways to provide the necessary capacity

Large area arrays of discrete single-molecule junctions derived from host-guest complexes.

The desire to continually reduce the lower limits of semiconductor integrated circuit (IC) fabrication methods continues to inspire interest in unimolecular electronics as a platform technology for the realization of future (opto)electronic devices. However, despite successes in developing methods for the construction and measurement of single-molecule and large-area molecular junctions, exercising control over the precise junction geometry remains a significant challenge. Here, host-guest complexes of the wire-like viologen derivative 1,1'-bis(4-(methylthio)-phenyl)-[4,4'-bipyridine]-1,1'-diium chloride ([1][Cl] ) and cucurbit[7]uril (CB[7]) have been self-assembled in a regular pattern over a gold substrate. Subsequently, ligandless gold nanoparticles (AuNPs) synthesized are deposited over the host-guest array. The agreement between the conductance of individual mono-molecular junctions, appropriately chosen as a function of the AuNP diameter, within this array determined by conductive probe atomic force microscope (c-AFM) and true single-molecule measurements for a closely similar host-guest complex within a scanning tunneling microscope break-junction (STM-BJ) indicates the formation of molecular junctions derived from these host-guest complexes without deleterious intermolecular coupling effects

Metrology for MRI Safety

. Magnetic Resonance Imaging (MRI) has become an indispensable medical imaging modality with about 30 million patient exams in the EU every year and an excellent history of safe use. Nevertheless, it is continuously evolving and recent technological developments such as ultrahigh magnetic fields, parallel transmission, or MRI guided radiotherapy promise to significantly enhance the quality and the range of applicability of MRI. A major reason why these technological developments are not yet used in the clinical practice are unresolved safety issues. If the patient risk cannot be quantified reliably, a ‘safety first’ attitude naturally prevails preventing the routine use of new technologies or the scanning of subjects at high risk, e.g. carriers of metallic medical implants. The EMRP joint research project HLT 06 "Metrology for MRI Safety" aimed at providing such risk assessments for certain new developments or applications in MRI. The project was concluded in 2015 and some key results will be presented here

Search for quark contact interactions and extra spatial dimensions using dijet angular distributions in proton-proton collisions at √s = 8 TeV

A search is presented for quark contact interactions and extra spatial dimensions in proton-proton collisions at s = 8 TeV using dijet angular distributions. The search is based on a data set corresponding to an integrated luminosity of 19.7 -1 collected by the CMS detector at the CERN LHC. Dijet angular distributions are found to be in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-to-leading order in QCD corrections are obtained. A benchmark model in which only left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 5.9 and 8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed-Dimopoulos-Dvali model of extra spatial dimensions

A logistic map approach to economic cycles I. The best adapted companies

A birth-death lattice gas model about the influence of an environment on the fitness and concentration evolution of economic entities is analytically examined. The model can be mapped onto a high order logistic map. The control parameter is a (scalar) "business plan". Conditions are searched for growth and decay processes, stable states, upper and lower bounds, bifurcations, periodic and chaotic solutions. The evolution equation of the economic population for the best fitted companies indicates "microscopic conditions" for cycling. The evolution of a dynamic exponent is shown as a function of the business plan parameters.Comment: 10 pages, 5 postscript figure

Limitations of radical thiol-ene reactions for polymer-polymer conjugation

In this work, we report our findings on the use of radical thiol-ene chemistry for polymer-polymer conjugation. The manuscript combines the results from the Preparative Macromolecular Chemistry group from the Karlsruhe Institute of Technology (KIT) and the Polymer Chemistry Research group from Ghent University (UGent), which allowed for an investigation over a very broad range of reaction conditions. In particular, thermal and UV initiation methods for the radical thiol-ene process were compared. In the KIT group, the process was studied as a tool for the synthesis of star polymers by coupling multifunctional thiol core molecules with poly(n-butyl acrylate) macromonomers (MM), employing thermally decomposing initiators. The product purity and thus reaction efficiency was assessed via electrospray ionization mass spectrometry. Although the reactions with 10 or 5 equivalents of thiol with respect to macromonomer were successful, the coupling reaction with a one-to-one ratio of MM to thiol yielded only a fraction of the targeted product, besides a number of side products. A systematic parameter study such as a variation of the concentration and nature of the initiator and the influence of thiol-to-ene ratio was carried out. Further experiments with poly(styrene) and poly(isobornyl acrylate) containing a vinylic end group confirmed that thermal thiol-ene conjugation is far from quantitative in terms of achieving macromolecular star formation. In parallel, the UGent group has been focusing on photo-initiated thiol-ene chemistry for the synthesis of functional polymers on one hand and block copolymers consisting of poly(styrene) (PS) and poly (vinyl acetate) (PVAc) on the other hand. Various functionalization reactions showed an overall efficient thiol-ene process for conjugation reactions of polymers with low molecular weight compounds (∼90% coupling yield). However, while SEC and FT-IR analysis of the conjugated PS-PVAc products indicated qualitative evidence for a successful polymer-polymer conjugation, 1H NMR and elemental analysis revealed a low conjugation efficiency of about 23% for a thiol-to-ene ratio equal to one. Blank reactions using typical thiol-ene conditions indicated that bimolecular termination reactions occur as competitive side reactions explaining why a molecular weight increase is observed even though the thiol-ene reaction was not successful. The extensive study of both research groups indicates that radical thiol-ene chemistry should not be proposed as a straightforward conjugation tool for polymer-polymer conjugation reactions. Head-to-head coupling is a major reaction pathway, which interrupts the propagation cycle of the thiol-ene process. © 2010 Wiley Periodicals, Inc

Total Directional Variation for Video Denoising

In this paper, we propose a variational approach for video denoising, based on a total directional variation (TDV) regulariser proposed in Parisotto et al. (2018), for image denoising and interpolation. In the TDV regulariser, the underlying image structure is encoded by means of weighted derivatives so as to enhance the anisotropic structures in images, e.g. stripes or curves with a dominant local directionality. For the extension of TDV to video denoising, the space-time structure is captured by the volumetric structure tensor guiding the smoothing process. We discuss this and present our whole video denoising work-flow. Our numerical results are compared with some state-of-the-art video denoising methods.SP acknowledges UK EPSRC grant EP/L016516/1 for the CCA DTC. CBS acknowledges support from Leverhulme Trust project on Breaking the non-convexity barrier, EPSRC grant Nr. EP/M00483X/1, the EPSRC Centre EP/N014588/1, the RISE projects CHiPS and NoMADS, the CCIMI and the Alan Turing Institute

SOWL QL: Querying Spatio - Temporal Ontologies in OWL

We introduce SOWL QL, a query language for spatio-temporal information in ontologies. Buildingupon SOWL (Spatio-Temporal OWL), an ontology for handling spatio-temporal information in OWL, SOWL QL supports querying over qualitative spatio-temporal information (expressed using natural language expressions such as “before”, “after”, “north of”, “south of”) rather than merely quantitative information (exact dates, times, locations). SOWL QL extends SPARQL with a powerful set of temporal and spatial operators, including temporal Allen topological, spatial directional and topological operations or combinations of the above. SOWL QL maintains simplicity of expression and also, upward and downward compatibility with SPARQL. Query translation in SOWL QL yields SPARQL queries implying that, querying spatio-temporal ontologies using SPARQL is still feasible but suffers from several drawbacks the most important of them being that, queries in SPARQL become particularly complicated and users must be familiar with the underlying spatio-temporal representation (the “N-ary relations” or the “4D-fluents” approach in this work). Finally, querying in SOWL QL is supported by the SOWL reasoner which is not part of the standard SPARQL translation. The run-time performance of SOWL QL has been assessed experimentally in a real data setting. A critical analysis of its performance is also presented