11,519 research outputs found
Monopole clusters and critical dynamics in four-dimensional U(1)
We investigate monopoles in four-dimensional compact U(1) with Wilson action.
We focus our attention on monopole clusters as they can be identified
unambiguously contrary to monopole loops. We locate the clusters and determine
their properties near the U(1) phase transition. The Coulomb phase is
characterized by several small clusters, whereas in the confined phase the
small clusters coalesce to one large cluster filling up the whole system. We
find that clusters winding around the periodic lattice are absent within both
phases and during the transition. However, within the confined phase, we
observe periodically closed monopole loops if cooling is applied.Comment: 3 pages, Wuppertal preprint WUB 93-3
Internet Peering as a Network of Relations
We apply results from recent theoretical work on networks of relations to analyze optimal peering strategies for asymmetric ISPs. It is shown that - from a network of relations perspective ā ISPsā asymmetry in bilateral peering agreements need not be a problem, since when these form a closed network, asymmetries are pooled and information transmission is faster. Both these effects reduce the incentives for opportunism in general, and interconnection quality degradation in particular. We also explain why bilateral monetary transfers between asymmetric ISPs (Bilateral Paid Peering), though potentially good for bilateral peering, may have rather negative effects on the sustainability of the overall peering network
Networks of Relations
We model networks of relational (or implicit) contracts, exploring how sanctioning power and equilibrium conditions change under different network configurations and information transmission technologies. In our model, relations are the links, and the value of the network lies in its ability to enforce cooperative agreements that could not be sustained if agents had no access to other network membersā sanctioning power and information. We identify conditions for network stability and in-network information transmission as well as conditions under which stable subnetworks inhibit more valuable larger networks
Ozone Measurements in the Mesosphere During a Solar Proton Event
Charged particle precipitation in the Earth's atmosphere produces odd nitrogen and odd hydrogen. These species take part in catalytic reactions which destroy atmospheric ozone in the stratosphere and mesosphere. Modeling efforts regarding the impact of these ionization events on the neutral atmosphere describe ozone depletions in good agreement with observations in the stratosphere and mesosphere. The photochemical effects of the solar proton event (SPE) of August 1972 are discussed, and calculations for higher altitudes (70 to 90 km) are presented that indicate after a brief reduction during and immediately following intense particle precipitation, ozone will later reach higher concentrations than those present before the event
First-Order Signals in Compact QED with Monopole Suppressed Boundaries
Pure gauge compact QED on hypercubic lattices is considered with periodically
closed monopole currents suppressed. We compute observables on sublattices
which are nested around the centre of the lattice in order to locate regions
where translation symmetry is approximately recovered. Our Monte Carlo
simulations on -lattices give indications for a first-order nature of the
U(1) phase transition.Comment: 3 pages, uuencoded Z-compressed .tar file, to appear in proceedings
of lattice 9
Moral Hazard and the Internal Organization of Joint Research
joint projects, internal organization, agency problems, synergies
Internet Peering as a Network of Relations
We apply results from recent theoretical work on networks of relations to analyze optimal peering strategies for asymmetric ISPs. It is shown that - from a network of relations perspective ā ISPsā asymmetry in bilateral peering agreements need not be a problem, since when these form a closed network, asymmetries are pooled and information transmission is faster. Both these effects reduce the incentives for opportunism in general, and interconnection quality degradation in particular. We also explain why bilateral monetary transfers between asymmetric ISPs (Bilateral Paid Peering), though potentially good for bilateral peering, may have rather negative effects on the sustainability of the overall peering network.
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