183 research outputs found

    Neutrinos from active black holes, sources of ultra high energy cosmic rays

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    A correlation between the highest energy Cosmic Rays (above ~ EeV) and the distribution of active galactic nuclei (AGN) gives rise to a prediction of neutrino production in the same sources. In this paper, we present a detailed AGN model, predicting neutrino production near the foot of the jet, where the photon fields from the disk and synchrotron radiation from the jet itself create high optical depths for proton-photon interactions. The protons escape from later shocks where the emission region is optically thin for proton-photon interactions. Consequently, Cosmic Rays are predicted to come from FR-I galaxies, independent of the orientation of the source. Neutrinos, on the other hand, are only observable from sources directing their jet towards Earth, i.e. flat spectrum radio sources and in particular BL Lac type objects, due to the strongly boosted neutrino emission.Comment: Accepted for publication in Astroparticle Physics; 30 pages, 8 figure

    Translating Human Rights in Education

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    The 2006 United Nations Convention on the Rights of Persons with Disabilities (UN CRPD) is the first human rights treaty to explicitly acknowledge the right to education for persons with disabilities. In order to realize this right, the convention’s Article 24 mandates state parties to ensure inclusive education systems that overcome outright exclusion as well as segregation in special education settings. Despite this major global policy change to tackle the discriminations persons with disabilities face in education, this has yet to take effect in most school systems worldwide. Focusing on the factors undermining the realization of disability rights in education, Julia Biermann probes current meanings of inclusive education in two contrasting yet equally challenged state parties to the UN CRPD: Nigeria, whose school system overtly excludes disabled children, and Germany, where this group primarily learns in special schools. In both countries, policy actors aim to realize the right to inclusive education by segregating students with disabilities into special education settings. In Nigeria, this demand arises from the glaring lack of such a system. In Germany, conversely, from its extraordinary long-term institutionalization. This act of diverting from the principles embodied in Article 24 is based on the steadfast and shared belief that school systems, which place students into special education, have an innate advantage in realizing the right to education for persons with disabilities. Accordingly, inclusion emerges to be an evolutionary and linear process of educational expansion that depends on institutionalized special education, not a right of persons with disabilities to be realized in local schools on an equal basis with others. This book proposes a refined human rights model of disability in education that shifts the analytical focus toward the global politics of formal mass schooling as a space where discrimination is sustained

    The diffuse neutrino flux from FR-II radio galaxies and blazars: A source property based estimate

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    Water and ice Cherenkov telescopes of the present and future aim for the detection of a neutrino signal from extraterrestrial sources at energies E>PeV. Some of the most promising extragalactic sources are Active Galactic Nuclei (AGN). In this paper, the neutrino flux from two kinds of AGN sources will be estimated assuming photohadronic interactions in the jet of the AGN. The first analyzed sample contains FR-II radio galaxies while the second AGN type examined are blazars. The result is highly dependent on the proton's index of the energy spectrum. To normalize the spectrum, the connection between neutrino and disk luminosity will be used by applying the jet-disk symbiosis model from Falcke and Biermann (1995). The maximum proton energy and thus, also the maximum neutrino energy of the source is connected to its disk luminosity, which was shown by Lovelace (1976) and was confirmed by Falcke et al. (1995).Comment: 24 pages, 14 figures, to be published in Astroparticle Physic

    Layered Architecture Consistency for MANETs: Introducing New Team Members

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    In this paper we extend our results concerning the layered architecture for modeling workflows in Mobile Ad-Hoc networks (MANETs) using algebraic higher order nets. MANETs are networks of mobile devices that communicate with each other via wireless links without relying on an underlying infrastructure. Workflows in \manets can be adequately modeled using a layered architecture, where the overall workflow, the team members' activities and the mobility issues are separated into three different layers, namely the workflow layer, the mobility layer and the team layer. In fromer papers a formal notion of layer consistency was suggested, that we now extend to allow changes of the interfaces of the gluing of the workflow and the mobility layer

    Neutrinos from photo-hadronic interactions in Pks2155-304

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    The high-peaked BL Lac object Pks2155-304 shows high variability at multiwavelengths, i.e. from optical up to TeV energies. A giant flare of around 1 hour at X-ray and TeV energies was observed in 2006. In this context, it is essential to understand the physical processes in terms of the primary spectrum and the radiation emitted, since high-energy emission can arise in both leptonic and hadronic processes. In this contribution, we investigate the possibility of neutrino production in photo-hadronic interactions. In particular, we predict a direct correlation between optical and TeV energies at sufficiently high optical radiation fields. We show that in the blazar Pks2155-304, the optical emission in the low-state is sufficient to lead to photo-hadronic interactions and therefore to the production of high-energy photons.Comment: contribution to RICAP 2009 and ICRC 2009 - both papers are combined in one draft. 11 pages, 3 figure

    Cosmic ray transport and anisotropies

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    We show that the large-scale cosmic ray anisotropy at ~10 TeV can be explained by a modified Compton-Getting effect in the magnetized flow field of old supernova remnants. This approach suggests an optimum energy scale for detecting the anisotropy. Two key assumptions are that propagation is based on turbulence following a Kolmogorov law and that cosmic ray interactions are dominated by transport through stellar winds of the exploding stars. A prediction is that the amplitude is smaller at lower energies due to incomplete sampling of the velocity field and also smaller at larger energies due to smearing.Comment: 6 pages, 1 figur

    On the detectability of primordial black holes in the Galaxy

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    In the mass range of 1e15 g up to 1e26 g, primordial black holes (PBHs) as a possible contribution to the dark matter are still unexplored. In this contribution, we investigate the possibility of an electromagnetic signal from PBH interactions with astrophysical objects in the Galaxy. We find that a signal from passages cannot be observed, since, depending on the mass, either the interaction probability or the energy loss is too small. Further, we discuss possible effects from high-mass PBHs at masses >1e26 g, where PBHs can still contribute to the dark matter at the order of ~10%. Here, we find that a significant fraction of PBHs can be captured in the Hubble time. These captures could therefore lead to detectable effects.Comment: 10 pages, 3 figures, paper to be presented at ICRC 200
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