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  • Open Access
    Authors: 
    Unkovski-Korica, Vladimir;
    Publisher: Informa UK Limited
    Country: United Kingdom

    This essay investigates the origins of the autonomous status of Vojvodina in post-war Serbia and Yugoslavia. It charts the formation of national and regional consciousness among Vojvodina’s Serbs, Germans and Hungarians, from Habsburg times to World War II. It then argues that Nazi Germany’s racial war radicalised national tensions in Vojvodina. Nazi defeat resulted in the brutal expulsion of Vojvodina’s Germans, making Serbs for the first time a majority. Consequently, the region’s claim to autonomous status after the war clashed with the national-territorial principle applied to federalism by the victorious Communist Party of Yugoslavia, causing frequent friction and instability.

  • Open Access
    Authors: 
    Falcone, Gioia;
    Country: United Kingdom

    No abstract available.

  • Open Access English
    Authors: 
    Geraint H. Jones; Matthew M. Knight; Karl Battams; Daniel C. Boice; John C. Brown; Silvio Giordano; John C. Raymond; Colin Snodgrass; Jordan K. Steckloff; Paul R. Weissman; +9 more
    Publisher: Springer Netherlands
    Countries: United States, United Kingdom, Italy, Norway, Italy, Norway, United States
    Project: NSF | Modeling Composition and ... (0908529), EC | ISANDAL (268421), NSF | Modeling Composition and ... (0908529), EC | ISANDAL (268421)

    Source at https://doi.org/10.1007/s11214-017-0446-5. This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics.

  • Open Access
    Authors: 
    Qiufang Deng; Junjie Xu; Lu Guo; Song Liang; Lianping Hou; Hongliang Zhu;
    Publisher: Institute of Electrical and Electronics Engineers (IEEE)
    Country: United Kingdom

    We report a dual-mode semiconductor laser that has two gratings with different periods below and above the active layer. A semiconductor optical amplifier (SOA), which is integrated with the dual-mode laser, plays an important role in balancing the optical power and reducing the linewidths of the emission modes. A stable two mode emission with the 13.92-nm spacing can be obtained over a wide range of distributed feedback and SOA injection currents. Compared with other types of dual-mode lasers, our device has the advantages of simple structure, compact size, and low fabrication cost.

  • Closed Access English
    Authors: 
    Simitev, Radostin D.; Kosovichev, Alexander G.; Busse, Friedrich H.;
    Publisher: IOP Publishing
    Country: United Kingdom

    Numerical MHD simulations play increasingly important role for understanding mechanisms of stellar magnetism. We present simulations of convection and dynamos in density-stratified rotating spherical fluid shells. We employ a new 3D simulation code for the solution of a physically consistent anelastic model of the process with a minimum number of parameters. The reported dynamo simulations extend into a "buoyancy-dominated" regime where the buoyancy forcing is dominant while the Coriolis force is no longer balanced by pressure gradients and strong anti-solar differential rotation develops as a result. We find that the self-generated magnetic fields, despite being relatively weak, are able to reverse the direction of differential rotation from anti-solar to solar-like. We also find that convection flows in this regime are significantly stronger in the polar regions than in the equatorial region, leading to non-oscillatory dipole-dominated dynamo solutions, and to concentration of magnetic field in the polar regions. We observe that convection has different morphology in the inner and at the outer part of the convection zone simultaneously such that organized geostrophic convection columns are hidden below a near-surface layer of well-mixed highly-chaotic convection. While we focus the attention on the buoyancy-dominated regime, we also demonstrate that conical differential rotation profiles and persistent regular dynamo oscillations can be obtained in the parameter space of the rotation-dominated regime even within this minimal model.

  • Open Access English
    Authors: 
    Papanatsiou, Maria; Amtmann, Anna; Blatt, Michael R.;
    Country: United Kingdom
    Project: UKRI | 14-PSIL MAGIC: a multi-ti... (BB/M01133X/1), UKRI | Stomatal-based systems an... (BB/L001276/1)

    Stomata enable gaseous exchange between the interior of the leaf and the atmosphere through the stomatal pore. Control of the pore aperture depends on osmotic solute accumulation by, and its loss from the guard cells surrounding the pore. Stomata in most plants are separated by at least one epidermal cell, and this spacing is thought to enhance stomatal function, although there are several genera that exhibit stomata in clusters. We made use of Arabidopsis (Arabidopsis thaliana) stomatal patterning mutants to explore the impact of clustering on guard cell dynamics, gas exchange, and ion transport of guard cells. These studies showed that stomatal clustering in the Arabidopsis too many mouths (tmm1) mutant suppressed stomatal movements and affected CO2 assimilation and transpiration differentially between dark and light conditions and were associated with alterations in K+ channel gating. These changes were consistent with the impaired dynamics of tmm1 stomata and were accompanied by a reduced accumulation of K+ ions in the guard cells. Our findings underline the significance of spacing for stomatal dynamics. While stomatal spacing may be important as a reservoir for K+ and other ions to facilitate stomatal movements, the effects on channel gating, and by inference on K+ accumulation, cannot be explained on the basis of a reduced number of epidermal cells facilitating ion supply to the guard cells.

  • Open Access
    Authors: 
    Peveler, William J.; Noimark, Sacha; Al-Azawi, Hassan; Hwang, Gi Byoung; Crick, Colin R.; Allan, Elaine; Edel, Joshua B.; Ivanov, Aleksandar P.; MacRobert, Alexander J.; Parkin, Ivan P.;
    Country: United Kingdom
    Project: UKRI | DTA - University College ... (EP/M506448/1), EC | NanoPD (724300)

    The development of photoactivated antimicrobial surfaces that kill pathogens through the production of singlet oxygen has proved very effective in recent years, with applications in medical devices and hospital touch surfaces, to improve patient safety and well being. However, many of these surfaces require a swell-encapsulation-shrink strategy to incorporate the photoactive agents in a polymer matrix, and this is resource intensive, given that only the surface fraction of the agent is active against bacteria. Furthermore, there is a risk that the agent will leach from the polymer and thus raises issues of biocompatibility and patient safety. Here, we describe a more efficient method of fabricating a silicone material with a covalently attached monolayer of photoactivating agent that uses heavy-atom triplet sensitization for improved singlet oxygen generation and corresponding antimicrobial activity. We use boron-dipyrromethane with a reactive end group and incorporated Br atoms, covalently attached to poly(dimethylsiloxane). We demonstrate the efficacy of this material in producing singlet oxygen and killing Staphylococcus aureus and suggest how it might be easily modifiable for future antimicrobial surface development.

  • Open Access
    Authors: 
    Morgan Jouanneau; Karunakar Reddy Bonepally; Alan Jeuken; Aurélien Tap; Régis Guillot; Janick Ardisson; Jean-Pierre Férézou; Joëlle Prunet;
    Publisher: American Chemical Society (ACS)
    Country: United Kingdom

    A new and flexible approach toward the synthesis of 6,12-guaianolide anticancer drugs such as trilobolides or thapsigargin has been developed that could be applied to the preparation of analogues with a modified ring system. The synthesis starts from commercial 2-methylcyclopentane-1,3-dione, only relying on diastereoselective reactions for the construction of the stereogenic centers at C1, C3, C6, and C10 and features a high-yielding ring-closing enyne metathesis (RCEYM) step for the formation of the [5,7] bicyclic core.

  • Publication . Article . 2018
    Open Access
    Authors: 
    Robbie, Jill;
    Publisher: Edinburgh University Press
    Country: United Kingdom

    No abstract available.

  • Open Access English
    Authors: 
    Aaij, R.; Adeva, B.; Adinolfi, M.; Affolder, A.; Ajaltouni, Z.; Akar, S.; Albrecht, J.; Alessio, F.; Alexander, M; Ali, S.; +191 more
    Countries: United Kingdom, Italy

    A measurement of the production cross-section for Z bosons that decay to\ud muons is presented. The data were recorded by the LHCb detector during pp collisions at a\ud centre-of-mass energy of 7 TeV, and correspond to an integrated luminosity of 1.0 fb−1\ud . The\ud cross-section is measured for muons in the pseudorapidity range 2.0 < η < 4.5 with transverse\ud momenta pT <20 GeV/c. The dimuon mass is restricted to 60 < Mµ+µ− < 120 GeV/c2\ud .\ud The measured cross-section is\ud σZ→µ+µ− = (76.0 ± 0.3 ± 0.5 ± 1.0 ± 1.3) pb\ud where the uncertainties are due to the sample size, systematic effects, the beam energy\ud and the luminosity. This result is in good agreement with theoretical predictions at nextto-next-to-leading\ud order in perturbative quantum chromodynamics. The cross-section is\ud also measured differentially as a function of kinematic variables of the Z boson. Ratios\ud of the production cross-sections of electroweak bosons are presented using updated LHCb\ud measurements of W boson production. A precise test of the Standard Model is provided\ud by the measurement of the ratio\ud σW+→µ+νµ + σW−→µ−ν¯µ\ud σZ→µ+µ−\ud = 20.63 ± 0.09 ± 0.12 ± 0.05,\ud where the uncertainty due to luminosity cancels.

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