5,632 research outputs found
Applying Abstract Argumentation Theory to Cooperative Game Theory
We apply ideas from abstract argumentation theory to study cooperative game
theory. Building on Dung's results in his seminal paper, we further the
correspondence between Dung's four argumentation semantics and solution
concepts in cooperative game theory by showing that complete extensions (the
grounded extension) correspond to Roth's subsolutions (respectively, the
supercore). We then investigate the relationship between well-founded
argumentation frameworks and convex games, where in each case the semantics
(respectively, solution concepts) coincide; we prove that three-player convex
games do not in general have well-founded argumentation frameworks.Comment: 15 pages, 1 tabl
Dimensionality of social networks using motifs and eigenvalues
We consider the dimensionality of social networks, and develop experiments
aimed at predicting that dimension. We find that a social network model with
nodes and links sampled from an -dimensional metric space with power-law
distributed influence regions best fits samples from real-world networks when
scales logarithmically with the number of nodes of the network. This
supports a logarithmic dimension hypothesis, and we provide evidence with two
different social networks, Facebook and LinkedIn. Further, we employ two
different methods for confirming the hypothesis: the first uses the
distribution of motif counts, and the second exploits the eigenvalue
distribution.Comment: 26 page
The impact of glycaemic load on cognitive performance: A meta-analysis and guiding principles for future research
The effect of breakfast glycaemic load (GL) on cognition was systematically examined. Randomised and non-randomised controlled trials were identified using PubMed, Scopus, and Cochrane Library (up to May 2022). 15 studies involving adults (aged 20 â 80 years) were included. Studies had a low risk, or some concerns, of bias. A random-effects meta-analysis model revealed no effect of GL on cognition up to 119 min post-consumption. However, after 120 min, immediate episodic memory scores were better following a low-GL compared to a high-GL (SMD = 0.16, 95% confidence interval [CI] = â0.00 to 0.32, p = 0.05, I2 = 5%). Subgroup analyses indicated that the benefit was greater in younger adults (<35 years) and those with better GT. A qualitative synthesis of 16 studies involving children and adolescents (aged 5 â 17 years) suggested that a low-GL breakfast may also benefit episodic memory and attention after 120 min. Methodological practises were identified which could explain a failure to detect benefits in some studies. Consequently, guiding principles were developed to optimise future study design
Above and belowground community strategies respond to different global change drivers
Environmental changes alter the diversity and structure of communities. By shifting the range of species traits that will be successful under new conditions, environmental drivers can also dramatically impact ecosystem functioning and resilience. Above and belowground communities jointly regulate whole-ecosystem processes and responses to change, yet they are frequently studied separately. To determine whether these communities respond similarly to environmental changes, we measured taxonomic and trait-based responses of plant and soil microbial communities to four years of experimental warming and nitrogen deposition in a temperate grassland. Plant diversity responded strongly to N addition, whereas soil microbial communities responded primarily to warming, likely via an associated decrease in soil moisture. These above and belowground changes were associated with selection for more resource-conservative plant and microbe growth strategies, which reduced community functional diversity. Functional characteristics of plant and soil microbial communities were weakly correlated (Pâ=â0.07) under control conditions, but not when above or belowground communities were altered by either global change driver. These results highlight the potential for global change drivers operating simultaneously to have asynchronous impacts on above and belowground components of ecosystems. Assessment of a single ecosystem component may therefore greatly underestimate the whole-system impact of global environmental changes
Evolution of entanglement within classical light states
We investigate the evolution of quantum correlations over the lifetime of a
multi-photon state. Measurements reveal time-dependent oscillations of the
entanglement fidelity for photon pairs created by a single semiconductor
quantum dot. The oscillations are attributed to the phase acquired in the
intermediate, non-degenerate, exciton-photon state and are consistent with
simulations. We conclude that emission of photon pairs by a typical quantum dot
with finite polarisation splitting is in fact entangled in a time-evolving
state, and not classically correlated as previously regarded
Responsive Access Small Cargo Affordable Launch (RASCAL) Independent Performance Evaluation
13th International Space Planes and Hypersonics Systems and Technologies Conference
May 2005, Capua, ItalyRASCAL is a United States Defense Department initiative that stands for Responsive
Access, Small Cargo, Affordable Launch. The overall launch concept involves three stages.
The first stage will consist of a reusable aircraft similar to a large scale Air Force fighter.
The first stage will also utilize Mass Injection Pre-Compressor Cooling (MIPCC) turbojet
engines that will propel the stage to approximately two hundred thousand feet before
releasing the second and third rocket stages. The first stage will be similar to a large fighter
of the F-22 class, although the turbofans will be that of the more available F100 class. The
MIPCC system will be a plug-in addition to the engines to help high altitude performance.
This stage will act as a first stage in the RASCAL architecture and will contribute
significantly to the overall acceleration of the vehicle. The second and third stages of the
RASCAL concept consist of expendable rockets. Releasing the upper stages outside the
atmosphere will reduce the loads on the stages as well as the risk of staging. Also by relying
on the reusable portion for all atmospheric flight, the expendable stages can be designed
simpler and therefore cheaper.
The purpose of this project is to compare the published RASCAL numbers with those
computed using a design methodology currently used in the Space System Design
Laboratory (SSDL) at The Georgia Institute of Technology. When the initial Space Launch
Corporation design was evaluated using the SSDL methodology it was found to fall short of
the performance as well as the cost goals set by DARPA for the RASCAL program. The
baseline vehicle was found to only carry 52 lbs to the 270 nmi sun synchronous orbit. Several
alternatives were evaluated off of the baseline design. The best of these alternatives can
meet DARPAâs performance goals and reach the cost goals of $5,000 per pound of payload
with eight first stage vehicles flying 46 times per year for a total of 363 flights per year.
Different economic cases were also evaluated to try and meet the cost goals in a less
ambitious number of flights per year. It was found that if the DDT&E was paid for by
another party (NASA, DOD, etc.) the cost goals can be met with just three vehicles flying 42
times per year for a total of 125 flights per year
âDominant ethnicityâ and the âethnic-civicâ dichotomy in the work of A. D. Smith
This article considers the way in which the work of Anthony Smith has helped to structure debates surrounding the role of ethnicity in present-day nations. Two major lines of enquiry are evident here. First, the contemporary role of dominant ethnic groups within 'their' nations and second, the interplay between ethnic and civic elements in nationalist argument. The two processes are related, but maintain elements of distinctiveness. Smith's major contribution to the dominant ethnicity debate has been to disembed ethnicity from the ideologically-charged and/or anglo-centric discourse of ethnic relations and to place it in historical context, thereby opening up space for dominant group ethnicity to be considered as a distinct phenomenon. This said, Smith's work does not adequately account for the vicissitudes of dominant ethnicity in the contemporary West. Building on the classical works of Hans Kohn and Friedrich Meinecke, Anthony Smith has also made a seminal contribution to the debate on civic and ethnic forms of national identity and nationalist ideology. As well as freeing this debate from the strong normative overtones which it has often carried, he has continued to insist that the terms civic and ethnic should be treated as an ideal-typical distinction rather than a scheme of classification
A novel mechanism of autophagic cell death in dystrophic muscle regulated by P2RX7 receptor large-pore formation and HSP90
<div><p>P2RX7 is an ATP-gated ion channel, which can also exhibit an open state with a considerably wider permeation. However, the functional significance of the movement of molecules through the large pore (LP) and the intracellular signaling events involved are not known. Here, analyzing the consequences of P2RX7 activation in primary myoblasts and myotubes from the <i>Dmd<sup>mdx</sup></i> mouse model of Duchenne muscular dystrophy, we found ATP-induced P2RX7-dependent autophagic flux, leading to CASP3-CASP7-independent cell death. P2RX7-evoked autophagy was triggered by LP formation but not Ca<sup>2+</sup> influx or MAPK1-MAPK3 phosphorylation, 2 canonical P2RX7-evoked signals. Phosphoproteomics, protein expression inference and signaling pathway prediction analysis of P2RX7 signaling mediators pointed to HSPA2 and HSP90 proteins. Indeed, specific HSP90 inhibitors prevented LP formation, LC3-II accumulation, and cell death in myoblasts and myotubes but not in macrophages. Pharmacological blockade or genetic ablation of <i>p2rx7</i> also proved protective against ATP-induced death of muscle cells, as did inhibition of autophagy with 3-MA. The functional significance of the P2RX7 LP is one of the great unknowns of purinergic signaling. Our data demonstrate a novel outcomeâautophagyâand show that molecules entering through the LP can be targeted to phagophores. Moreover, we show that in muscles but not in macrophages, autophagy is needed for the formation of this LP. Given that P2RX7-dependent LP and HSP90 are critically interacting in the ATP-evoked autophagic death of dystrophic muscles, treatments targeting this axis could be of therapeutic benefit in this debilitating and incurable form of muscular dystrophy.</p></div
Sub-nanosecond signal propagation in anisotropy engineered nanomagnetic logic chains
Energy efficient nanomagnetic logic (NML) computing architectures propagate
and process binary information by relying on dipolar field coupling to reorient
closely-spaced nanoscale magnets. Signal propagation in nanomagnet chains of
various sizes, shapes, and magnetic orientations has been previously
characterized by static magnetic imaging experiments with low-speed adiabatic
operation; however the mechanisms which determine the final state and their
reproducibility over millions of cycles in high-speed operation (sub-ns time
scale) have yet to be experimentally investigated. Monitoring NML operation at
its ultimate intrinsic speed reveals features undetectable by conventional
static imaging including individual nanomagnetic switching events and
systematic error nucleation during signal propagation. Here, we present a new
study of NML operation in a high speed regime at fast repetition rates. We
perform direct imaging of digital signal propagation in permalloy nanomagnet
chains with varying degrees of shape-engineered biaxial anisotropy using
full-field magnetic soft x-ray transmission microscopy after applying single
nanosecond magnetic field pulses. Further, we use time-resolved magnetic
photo-emission electron microscopy to evaluate the sub-nanosecond dipolar
coupling signal propagation dynamics in optimized chains with 100 ps time
resolution as they are cycled with nanosecond field pulses at a rate of 3 MHz.
An intrinsic switching time of 100 ps per magnet is observed. These
experiments, and accompanying macro-spin and micromagnetic simulations, reveal
the underlying physics of NML architectures repetitively operated on nanosecond
timescales and identify relevant engineering parameters to optimize performance
and reliability.Comment: Main article (22 pages, 4 figures), Supplementary info (11 pages, 5
sections
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