Games with Delays. A Frankenstein Approach

We investigate infinite games on finite graphs where the information flow is perturbed by nondeterministic signalling delays. It is known that such perturbations make synthesis problems virtually unsolvable, in the general case. On the classical model where signals are attached to states, tractable cases are rare and difficult to identify. Here, we propose a model where signals are detached from control states, and we identify a subclass on which equilibrium outcomes can be preserved, even if signals are delivered with a delay that is finitely bounded. To offset the perturbation, our solution procedure combines responses from a collection of virtual plays following an equilibrium strategy in the instant- signalling game to synthesise, in a Frankenstein manner, an equivalent equilibrium strategy for the delayed-signalling game

KALMAR - „Kurile-Kamchatka and Aleutean Marginal Sea-Island Arc Systems: Geodynamic and Climate Interaction in Space and Time” – an integrated science approach between Russia and Germany

EGU2010-2934 The exploration of the arctic seas require an integrated approach applying different infrastructures. In Fall 2009 German and Russian scientists performed a geo marine cruise off Kamchatka and in the western Bering Sea within the frame of the KALMAR-Project. Two main research subjects formed the scientific backbone of the cruise: The first objective focuses on the geodynamic and volcanological magmatic development of the Kuril-Kamchatka island arc system and the Kamchatka Aleutean Islands Triple-Junction. Very little is known about the composition of the mantle and the oceanic crust as well as of the seamounts including their ages. The best studied site is the Volcanologist’s Massif located between the Bering- and the Alpha Fracture Zone (Tsvetkov 1990, Volynets et al. 1992, Yogodzinsky et al. 1994), which structurally belongs to the Komandorsky Basin. The oldest rocks of the Volcanologist´s Massif show very similar trace element and isotope signatures like those rocks cropping out in the volcanoes on Kamchatka in the prolongation of the Alpha Fracture Zone (Portnyagin et al. 2005a), indicating similar conditions of magma formation. The top of the Volcanologist´s Massif is characterized by the young ( 85 Ma. The only existing basement rocks from this seamount were gained during DSDP Leg 19. These are basalts with MORB like trace element and isotope signatures (Keller et al. 2000, Regelous et al. 2003). These data indicate that the Hawaii-Hotspot was at a MOR in Cretaceous time and that large volumes of depleted mantle material played a´role during the magma formation. The second objective focuses on paleo-oceanographic investigations concentrating on the sediments along the eastern continental slope of Kamchatka, in the Komandorsky Basin, and on the Shirshov Ridge in order to explore paleoclimate archives to better understand the subpolar water mass transfer and the oceanographic and climatic development in the subarctic NW-Pacific. Comparisons of Late Pleistocene and Holocene temperature changes within the near surface water masses between the NW-Pacific and the N-Atlantic resulted in a new hypothesis, the "Atlantic-Pacific seesaw" (Kiefer et al. 2001, Kim et al. 2004, Kiefer and Kienast, 2005). This Atlantic-Pacific pattern of opposite temperature variations dominates the last 60ka on millennial timescales. Modelling results of Saenko et al. (2004) support the hypothesis of the "Atlantic-Pacific seesaw" and they postulate a mechanistic connection between the two regions driven by salinity variations, which couples both regions through the thermohaline circulation. A different model relates the Holocene Atlantic-Pacific dipole to the atmospheric tele-connection between the Arctic Oscillation/N-Atlantic Oscillation and the Pacific N-American Oscillation (Kim et al. 2004). http://kalmar.ifm-geomar.d

KALMAR: "Kurile-Kamchatka and Aleutean Marginal Sea-Island Arc Systems: Geodynamic and Climate Interaction in Space and Time“ : an integrated Polar science approach between Russia and Germany

EGU2011-4204-1 The Russian German Cooperation in polar marine science has a long tradition. Since the last decade of the last century, there is a continous joint effort for geoscientific studies in the arctic and subarctic Far East. The new initiative of KALMAR II will concentrate on the complex geosystem of the Kurile-Kamchatka-Aleutean arc including the adjacent regions of the arctic Bering Sea and the NW Pacific. This giant and unique natural laboratory will allow the study of interactions and fluxes between the asthenosphere, the lithosphere, the hydrosphere, the cryosphere, and the atmosphere in order to provide detailed insights into natural risks (volcanic eruptions, tsunamis) and regional dynamics of the climate impacting on the global system. The envisaged integrated investigation will built upon the existing network of scientists from both countries who studied geodynamic and volcanologic as well paleoceanographic and paleoclimatic issues successfully in the past in the Far East. Two main research foci, ocean and climate dynamics as well as volcanisms and geodynamics, form the scientific backbone of the new KALMAR II initiative which will comprise in total five interlinked subprojects: Two subprojects will focus on the paleoclimatic and paleoceanographic evolution of this arctic region in relation to the development of the NW Pacific on millennial and decadal as well as seasonal times scales. This approach will test existing hypothesis with respect to water mass structure and water mass exchange through the Bering Strait, intermediate water mass formation, which, until know, is still not understood, marine productivity and their impact on the CO2 cycle, the glaciation history of Kamchatka and the continental oceanic (arctic) teleconnection between Atlantic and Pacific. The closely linked terrestrial subproject will study the marine influenced arctic region of Northern Kamchatka focusing on the geomorphologic and paleoclimatic evolution within the context of the northern hemisphere climate. One subproject within the volcanic and geodynamic focus will study experimentally petrologic and magmatic processes to better understand the evolution of magma and their volatiles in this volcanic arc system and how eruptions impact on the regional and global climate. Extremely linked to this subproject is the second one, which concentrates on the differentiation and alteration of volcanic rocks and their related volatile production. Special emphasis will be laid on fluid rock interactions in order to provide information about the input of fluids into the atmosphere and the hydrosphere. In a third aspect we envisage to study the origin of the volcanism within the western segment of the Aleutean Arc. This young volcanic activity ranging from Attu Island to Kamchatka was recently discovered from KALMAR scientists. The investigation of these volcanic rocks may reveal the transition from intraplate volcanism (North Kamchatka) to island arc volcanism (Attu Island) and may also shed light on the influence of the inclination of the subducting plate on the composition and intensity of the volcanic activity. All three magmatic and volcanological subprojects will use off shore as well as on shore material. To investigate the influence of major volcanic eruptions on the atmosphere and ocean, climate models will be employed

Northwestern Central American Volcanic Arc: Increased contribution of enriched lithosphere to lavas along the volcanic front from Nicaragua to Guatemala and behind the volcanic front

The Central American Volcanic Arc (CAVA) has been subject of intensive research over the past decades, leading to a large variety of different models for the origin of CAVA lavas with various source components. Based on a comprehensive new geochemical data set (i.e. major and trace elements and Sr-Nd-Pb-Hf-O isotope ratios) of mafic volcanic front (VF), behind the volcanic front (BVF) and back-arc (BA) lava and tephra samples from NW CAVA (Nicaragua to Guatemala), we present a new model for the NW Central American Volcanic Arc volcanism. Additional potential source component sample data from subducting Cocos Plate sediments, igneous oceanic crust and Guatemalan granitic and metamorphic continental basement further contributes to our new model. We find systematically increasing Pb isotope ratios and decreasing Nd and Hf isotope ratios along the arc from NW Nicaragua to Guatemala. BVF lavas generally have more radiogenic Pb and less radiogenic Nd and Hf isotopic compositions than related VF lavas, similar to what is observed for trace element ratios going northwards along the VF. Combined isotope and trace element data indicate the presence of three endmembers for the volcanism in NW Central America: (1) NW Nicaraguan VF samples with very high Ba/(La, Th) and U/Th, low La/Yb, relatively radiogenic Sr, Nd and Hf but unradiogenic Pb, (2) NW Guatemalan VF and Guatemalan and Honduran BVF samples with low Ba/(La, Th) and U/Th, high La/Yb, radiogenic Sr and Pb but unradiogenic Nd and Hf, and elevated d18O, and (3) Honduran and Nicaraguan BVF samples with low Ba/(La, Th) and U/Th, high La/Yb, unradiogenic Sr but radiogenic Nd, Hf and Pb. We interpret the NW Nicaragua VF endmember to be dominated by a largely serpentinite-derived fluid flux from the subducting slab, possibly with small amounts (<1 wt. %) of sediment melts, to a depleted N-MORB type of mantle wedge, resulting in large degrees of melting of primarily peridotitic material. Based on combined Hf and Nd and Hf and Pb isotope systematics, the isotopically enriched Guatemala VF and BVF endmember cannot be explained by the addition of subducted pelagic sediments to the source. Instead this endmember could be derived from pyroxenitic cumulates in the lithospheric mantle (and possibly lower crust) that were derived from parental magmas for plutonic rocks in NW Central America, which were melted during the Quaternary subduction-related volcanism. The isotopically depleted Honduras and Caribbean BA endmember could be derived from melting of young, recycled, oceanic crust in the asthenosphere upwelling in the back-arc, based on the OIB-like major and trace element but relatively depleted isotopic compositions of these samples. Mixing between these three endmember types of magmas can explain the observed systematic geochemical variations along and across the NW Central American Arc

The Act of State Doctrine after \u3cem\u3eSabbatino\u3c/em\u3e

The United States Supreme Court recently decided, in Banco Nacional de Cuba v. Sabbatino, that American courts must enforce a recognized foreign government\u27s expropriation decree even though the decree violates international law. The Court, contrary to the views of respected international lawyers, found this result dictated by the act of state doctrine, which bars American courts from reviewing the validity of another nation\u27s official acts. The decision, amid frequent revolutionary confiscations and national programs of expropriation, seriously draws into question the wisdom of further investments in developing countries. This is unfortunate because American foreign investments benefit the receiving country as well as the investor and ultimately contribute to international cooperation and world peace. This comment explores the meaning and scope of the act of state doctrine, as the Supreme Court applied it in Sabbatino

On the interplay between search behavior and collections in digital libraries and archives

Log analysis is an unobtrusive technique used to better understand search behavior and evaluate search systems. However, in contrast with open web search, in a vertical search system such as a digital library or media archive the collection is known and central to its purpose. This drives different, more collection-oriented questions when studying the logs. For example, whether users need different support in different parts of the collection.In a digital library, the collection is categorized using professionally curated metadata. We conjecture that using this metadata can improve and extend the methods and techniques for log analysis. We investigate how to identify different types of search behavior using the metadata explicitly, how to explain and predict user interactions for the different types of behavior found, and finally how to communicate our research results to domain experts.</p