2,099 research outputs found
Unquenched quark propagator in Landau gauge
We present an unquenched calculation of the quark propagator in Landau gauge
with 2+1 flavors of dynamical quarks. We use configurations generated with an
improved staggered (``Asqtad'') action by the MILC collaboration. This quark
action has been seen to have excellent rotational symmetry and scaling
properties in the quenched quark propagator. Quenched and dynamical
calculations are performed on a lattice with a nominal lattice
spacing of fm. The matched quenched and dynamical lattices allow us
to investigate the relatively subtle sea quark effects, and even in the
quenched case the physical volume of these lattices gives access to lower
momenta than our previous study. We calculate the quark mass function and
renormalization function for a variety of valence and sea quark masses.Comment: 7 pages, 6 figure
Virtualization for a Network Processor Runtime System
The continuing ossification of the Internet is slowing the pace of network innovation. Network diversification presents one solution to this problem, by virtualizing the network at multiple layers. Diversified networks consist of a shared physical substrate, virtual routers (metarouters), and virtual links (metalinks). Virtualizing routers enables smooth and incremental upgrades to new network services. Our current priority for a diversified router prototype is to enable reserved slices of the network for researchers to perform repeatable, high-speed network experiments. General-purpose processors have well established techniques for virtualization, but do not scale efficiently to multi-gigabit speeds. To achieve these speeds, we employ network processors (NPs), typically consisting of multicore, multi-threaded processors with asymmetric, heterogeneous memories. The complexity and lack of hardware thread isolation in NP’s, combined with a lack of simple programming models, creates numerous challenges for effective sharing between metarouters. In this paper, we detail strategies for enabling NP virtualization at the link, memory, and processor levels, to better enable a research infrastructure for network innovation
Quark propagator from an improved staggered action in Laplacian and Landau gauges
Studies of gauge dependent quantities are afflicted with Gribov copies, but
Laplacian gauge fixing provides one possible solution to this problem. We
present results for the lattice quark propagator in both Landau and Laplacian
gauges using standard and improved staggered quark actions. The standard
Kogut-Susskind action has errors of \oa{2} while the improved ``Asqtad'' action
has \oa{4}, \oag{2}{2} errors and this improvement is seen in the quark
propagator. We demonstrate the application of tree-level corrections to these
actions and see that Landau and Laplacian gauges produce very similar results.
In addition, we test an ansatz for the quark mass function, with promising
results. In the chiral limit, the infrared quark mass, is found to
be MeV.Comment: 5 pages, 8 figs., Talk given at LHP workshop, Cairn
Pretty Woman Meets the Man Who Wears the Star: Fair Use After Campbell v. Acuff-Rose Music and American Geophysical Union v. Texaco
New Producer Contract Terms and Uncertainty: Lessons From the Recent Past
The petroleum industry is volatile, and governments in “new producer” countries have operated at a significant information disadvantage when negotiating with international oil companies. This challenge is growing today; new producer countries face intensifying questions around whether to offer fiscal incentives to maintain investment in the face of 1) the pandemic-induced volatility in oil prices and 2) long-term questions about the future of the industry in the face of the climate crisis and the global energy transition.
This confluence of short-term and long-term uncertainty is prompting a reexamination of the narrative that once took hold in many new producer countries. The traditional story was one of linear progression from being non-producers to small levels of production to ultimately having oil and gas become a major economic contributor over the long term.
This notion of progression was associated with a commonly held theory: After a country’s first major discovery, the geological risk that wells will be dry was expected to decrease. Countries could therefore shift from a position of having to grant tax breaks (and other concessions) to international investors, to taking a tougher stance in laws and negotiations for new projects going forward.
In this paper, co-authored with NRGI we examine whether this theory has been borne out in practice and make recommendations to support new producers in their navigation of the uncertainty associated with the energy transition
Update
Allmählich wird sichtbar, wie radikal sich das Web, und insbesondere die Konzepte des sogenannten Web 2.0, auf die Arbeit von Bibliotheken und Informationseinrichtungen auswirkt. Wir möchten in unserem Vortrag auf die Frage eingehen, wie sich die Bibliotheken positiv auf die neue Medienwelt, neues Benutzerverhalten und neue Kommunikationsformen einstellen können, wie also das Upgrade zur Bibliothek 2.0 gelingt. Unsere These lautet: Der Bibliothekar selbst ist die Schlüsselressource der Bibliothek 2.0. Demzufolge ist es entscheidend, sich den neuen Möglichkeiten zu öffnen, sich selbst aus erster Hand mit den neuen Werkzeugen und Konzepten vertraut zu machen, und letztlich die eigenen professionellen Fertigkeiten und Werte mit dem Neuen zu verknüpfen. Doch wie genau sieht dieser Weg zum "Bibliothekar 2.0" aus, welche sozialen und technischen Fähigkeiten sind erforderlich, und wie können diese Fähigkeiten individuell, institutionalisiert und/oder gemeinschaftlich erworben werden
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