2,611 research outputs found
Nash bargaining in ordinal environments
We analyze the implications of Nashâs (1950) axioms in ordinal bargaining environments; there, the scale invariance axiom needs to be strenghtened to take into account all order-preserving transformations of the agentsâ utilities. This axiom, called ordinal invariance, is a very demanding one. For two-agents, it is violated by every strongly individually rational bargaining rule. In general, no ordinally invariant bargaining rule satisfies the other three axioms of Nash. Parallel to Roth (1977), we introduce a weaker independence of irrelevant alternatives axiom that we argue is better suited for ordinally invariant bargaining rules. We show that the three-agent Shapley-Shubik bargaining rule uniquely satisfies ordinal invariance, Pareto optimality, symmetry, and this weaker independence of irrelevant alternatives axiom. We also analyze the implications of other independence axioms
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Combined<sup>147,146</sup>Sm-<sup>143,142</sup>Nd constraints on the longevity and residence time of early terrestrial crust
Primordial silicate differentiation controlled the composition of Earth's oldest crust. Inherited 142Nd anomalies in Archean rocks are vestiges of the mantle-crust differentiation before ca. 4300 Ma. Here we report new whole-rock 147,146Sm-143,142Nd data for the Acasta Gneiss Complex (AGC; Northwest Territories, Canada). Our 147Sm-143Nd data combined with literature data define an age of 3371â±â141 Ma (2 SD) and yield an initial Δ143Nd of â5.6â±â2.1. These results are at odds with the Acasta zircon U-Pb record, which comprises emplacement ages of 3920â3960 Ma. Ten of our thirteen samples show 142Nd deficits of â9.6â±â4.8 ppm (2 SD) relative to the modern Earth. The discrepancy between 142Nd anomalies and a mid-Archean 147Sm-143Nd age can be reconciled with Nd isotope reequilibration of the AGC during metamorphic perturbations at ca. 3400 Ma. A model age of ca. 4310 Ma is derived for the early enrichment of the Acasta source. Two compositional end-members can be identified: a felsic component with 142Nd/144Nd identical to the modern Earth and a mafic component with 142Nd/144Nd as low as â14.1 ppm. The ca. 4310 Ma AGC source is âŒ200 Myr younger than those estimated for Nuvvuagittuq (northern QuĂ©bec) and Isua (Itsaq Gneiss Complex, West Greenland). The AGC does not have the same decoupled Nd-Hf isotope systematics as these other two terranes, which have been attributed to the crystallization of an early magma ocean. The Acasta signature rather is ascribed to the formation of Hadean crust that was preserved for several hundred Myr. Its longevity can be linked to 142Nd evolution in the mantle and does not require slow mantle stirring times nor modification of its convective mode.This project was funded by an ETH internal grant to BB. We thank Colin Maden for maintenance of the mass spectrometer. SJM acknowledges support from the NASA Exobiology and Evolutionary Biology Program (Investigating the Hadean Earth) and the NASA Lunar Science Institute (Center for Lunar Origin and Evolution, CLOE). Additional support to SJM came from the Laboratoire de GĂ©ologie de Lyon, UniversitĂ© Claude Bernard Lyon 1, and a Distinguished Professorship awarded by the Hungarian Academy of Sciences. JBT received support from the French Agence Nationale de la Recherche (Grant ANR-10-BLAN-0603 M&Ms â Mantle Melting â Measurements, Models, Mechanisms).This is the version of record, which can also be found on the publisher's website at: http://onlinelibrary.wiley.com/doi/10.1002/2014GC005313/abstract © 2014. American Geophysical Union. All Rights Reserved
Bargaining over a finite set of alternatives
We analyze bilateral bargaining over a finite set of alternatives. We look for âgoodâ ordinal solutions to such problems and show that Unanimity Compromise and Rational Compromise are the only bargaining rules that satisfy a basic set of properties. We then extend our analysis to admit problems with countably infinite alternatives. We show that, on this class, no bargaining rule choosing finite subsets of alternatives can be neutral. When rephrased in the utility framework of Nash (1950), this implies that there is no ordinal bargaining rule that is finite-valued
Bilateral pyosalpinx in a peripubescent female with Hirschsprung's disease: a case report
This is a case report of bilateral pyosalpinx in a peripubescent female with a history of Hirschsprung's disease. Bilateral pyosalpinx is a rare condition in non-sexually active females. The presence of this disease in a patient with a history of Hirschsprung's disease is concerning for an association of the two processes
Sequential Deliberation for Social Choice
In large scale collective decision making, social choice is a normative study
of how one ought to design a protocol for reaching consensus. However, in
instances where the underlying decision space is too large or complex for
ordinal voting, standard voting methods of social choice may be impractical.
How then can we design a mechanism - preferably decentralized, simple,
scalable, and not requiring any special knowledge of the decision space - to
reach consensus? We propose sequential deliberation as a natural solution to
this problem. In this iterative method, successive pairs of agents bargain over
the decision space using the previous decision as a disagreement alternative.
We describe the general method and analyze the quality of its outcome when the
space of preferences define a median graph. We show that sequential
deliberation finds a 1.208- approximation to the optimal social cost on such
graphs, coming very close to this value with only a small constant number of
agents sampled from the population. We also show lower bounds on simpler
classes of mechanisms to justify our design choices. We further show that
sequential deliberation is ex-post Pareto efficient and has truthful reporting
as an equilibrium of the induced extensive form game. We finally show that for
general metric spaces, the second moment of of the distribution of social cost
of the outcomes produced by sequential deliberation is also bounded
Design and fabrication of plasmonic cavities for magneto-optical sensing (article)
This is the author accepted manuscript. The final version is available from AIP Publishing via the DOI in this record.The dataset associated with this article is located in ORE at: http://hdl.handle.net/10871/32604The design and fabrication of a novel plasmonic cavity, intended to allow far-field recovery of signals arising from near field magneto-optical interactions, is presented. Finite element modeling is used to describe the interaction between a gold film, containing cross-shaped cavities, with a nearby magnetic under-layer. The modeling revealed strong electric field confinement near the center of the cross structure for certain optical wavelengths, which may be tuned by varying the length of the cross through a range that is compatible with available fabrication techniques. Furthermore, the magneto optical Kerr effect (MOKE) response of the composite structure can be enhanced with respect to that of the bare magnetic film. To confirm these findings, cavities were milled within gold films deposited upon a soluble film, allowing relocation to a ferromagnetic film using a float transfer technique. Cross cavity arrays were fabricated and characterized by optical transmission spectroscopy prior to floating, revealing resonances at optical wavelengths in good agreement with the finite element modeling. Following transfer to the magnetic film, circular test apertures within the gold film yielded clear magneto-optical signals even for diameters within the sub-wavelength regime. However, no magneto-optical signal was observed for the cross cavity arrays, since the FIB milling process was found to produce nanotube structures within the soluble under-layer that adhered to the gold. Further optimization of the fabrication process should allow recovery of magneto-optical signal from cross cavity structures.Financial support from the UK Engineering and Physical Science Research Council (EPSRC) grants EP/1038470/I and EP/1038411/1 is gratefully acknowledged. We also acknowledge the support of Seagate Technology (Ireland) under SOW 00077300.0. RMB contribution to project was supported by the Royal Academy of Engineering under the Research Chairs and Senior Research Fellowships Scheme
Specific immune priming in the invasive ctenophore Mnemiopsis leidyi
Specific immune priming enables an induced immune response upon repeated pathogen encounter. As a functional analogue to vertebrate immune memory, such adaptive plasticity has been described, for instance, in insects and crustaceans. However, towards the base of the metazoan tree our knowledge about the existence of specific immune priming becomes scattered. Here, we exposed the invasive ctenophore Mnemiopsis leidyi repeatedly to two different bacterial epitopes (Gram-positive or -negative) and measured gene expression. Ctenophores experienced either the same bacterial epitope twice (homologous treatments) or different bacterial epitopes (heterologous treatments). Our results demonstrate that immune gene expression depends on earlier bacterial exposure. We detected significantly different expression upon heterologous compared with homologous bacterial treatment at three immune activator and effector genes. This is the first experimental evidence for specific immune priming in Ctenophora and generally in non-bilaterian animals, hereby adding to our growing notion of plasticity in innate immune systems across all animal phyla
Light and electron microscopic detection of (3 Gal ÎČ 1,4 GlcNAc ÎČ 1) sequences in asparagine-linked oligosaccharides with the Datura stramonium lectin
The Datura stramonium lectin recognizes with high affinity the disaccharide N -acetyllactosamine (Gal ÎČ 1,4 GlcNAc). We have developed a highly specific cytochemical affinity technique in which an ovomucoid-gold complex serves as second step reagent for the visualization of this lectin bound to reactive sequences present in tissue sections. The lectin binding sites were detected in semithin and ultrathin sections of aldehyde-fixed and low temperature Lowicryl K4M embedded tissues. For light microscopical labeling the photochemical silver reaction for signal amplification was required. The application of this technique for the detection of N -acetyllactosamine containing asparagine-linked oligosaccharides in various intracellular organelles and the plasma membrane is demonstrated.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47409/1/418_2004_Article_BF00524763.pd
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Turbulent flow at 190 m height above London during 2006-2008: A climatology and the applicability of similarity theory
Flow and turbulence above urban terrain is more complex than above rural terrain, due to the different momentum and heat transfer characteristics that are affected by the presence of buildings (e.g. pressure variations around buildings). The applicability of similarity theory (as developed over rural terrain) is tested using observations of flow from a sonic anemometer located at 190.3 m height in London, U.K. using about 6500 h of data. Turbulence statisticsâdimensionless wind speed and temperature, standard deviations and correlation coefficients for momentum and heat transferâwere analysed in three ways. First, turbulence statistics were plotted as a function only of a local stability parameter z/Î (where Î is the local Obukhov length and z is the height above ground); the Ï_i/u_* values (i = u, v, w) for neutral conditions are 2.3, 1.85 and 1.35 respectively, similar to canonical values. Second, analysis of urban mixed-layer formulations during daytime convective conditions over London was undertaken, showing that atmospheric turbulence at high altitude over large cities might not behave dissimilarly from that over rural terrain. Third, correlation coefficients for heat and momentum were analyzed with respect to local stability. The results give confidence in using the framework of local similarity for turbulence measured over London, and perhaps other cities. However, the following caveats for our data are worth noting: (i) the terrain is reasonably flat, (ii) building heights vary little over a large area, and (iii) the sensor height is above the mean roughness sublayer depth
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