4,782 research outputs found
Inequality and Network Formation Games
This paper addresses the matter of inequality in network formation games. We
employ a quantity that we are calling the Nash Inequality Ratio (NIR), defined
as the maximal ratio between the highest and lowest costs incurred to
individual agents in a Nash equilibrium strategy, to characterize the extent to
which inequality is possible in equilibrium. We give tight upper bounds on the
NIR for the network formation games of Fabrikant et al. (PODC '03) and Ehsani
et al. (SPAA '11). With respect to the relationship between equality and social
efficiency, we show that, contrary to common expectations, efficiency does not
necessarily come at the expense of increased inequality.Comment: 27 pages. 4 figures. Accepted to Internet Mathematics (2014
Algorithm Instance Games
This paper introduces algorithm instance games (AIGs) as a conceptual
classification applying to games in which outcomes are resolved from joint
strategies algorithmically. For such games, a fundamental question asks: How do
the details of the algorithm's description influence agents' strategic
behavior?
We analyze two versions of an AIG based on the set-cover optimization
problem. In these games, joint strategies correspond to instances of the
set-cover problem, with each subset (of a given universe of elements)
representing the strategy of a single agent. Outcomes are covers computed from
the joint strategies by a set-cover algorithm. In one variant of this game,
outcomes are computed by a deterministic greedy algorithm, and the other
variant utilizes a non-deterministic form of the greedy algorithm. We
characterize Nash equilibrium strategies for both versions of the game, finding
that agents' strategies can vary considerably between the two settings. In
particular, we find that the version of the game based on the deterministic
algorithm only admits Nash equilibrium in which agents choose strategies (i.e.,
subsets) containing at most one element, with no two agents picking the same
element. On the other hand, in the version of the game based on the
non-deterministic algorithm, Nash equilibrium strategies can include agents
with zero, one, or every element, and the same element can appear in the
strategies of multiple agents.Comment: 14 page
Catastrophic failure: How COVID-19 was relayed from the media to the public
This research utilizes content analysis and mixed methods as a way of understanding how COVID-19 related information was relayed from the media to the public during crucial times in U.S. history. The information analyzed entails news media broadcasts that occurred from June 26 to October 2, 2020, when the pandemic was on the rise in terms of cases and deaths. In addition to analyzing specific broadcasts, a comparative analysis was conducted between MSNBC vs. Fox News, in an effort to highlight key events that took place during the battle against COVID-19. This research utilizes agenda setting and framing principles to foster a deeper understanding of what was said by each news broadcast. Results shows that there was a strong divergence of coverage between the two networks. This divergence also highlights how each network chose to talk about cases and deaths in vastly different ways. Supplemental evidence points to Fox News dismissing its COVID-19 mentions, or in some cases ignoring the cases and deaths all together, as the pandemic climbed passed the 200 thousand death count nationally
From neurons to epidemics: How trophic coherence affects spreading processes
Trophic coherence, a measure of the extent to which the nodes of a directed
network are organised in levels, has recently been shown to be closely related
to many structural and dynamical aspects of complex systems, including graph
eigenspectra, the prevalence or absence of feed-back cycles, and linear
stability. Furthermore, non-trivial trophic structures have been observed in
networks of neurons, species, genes, metabolites, cellular signalling,
concatenated words, P2P users, and world trade. Here we consider two simple yet
apparently quite different dynamical models -- one a
Susceptible-Infected-Susceptible (SIS) epidemic model adapted to include
complex contagion, the other an Amari-Hopfield neural network -- and show that
in both cases the related spreading processes are modulated in similar ways by
the trophic coherence of the underlying networks. To do this, we propose a
network assembly model which can generate structures with tunable trophic
coherence, limiting in either perfectly stratified networks or random graphs.
We find that trophic coherence can exert a qualitative change in spreading
behaviour, determining whether a pulse of activity will percolate through the
entire network or remain confined to a subset of nodes, and whether such
activity will quickly die out or endure indefinitely. These results could be
important for our understanding of phenomena such as epidemics, rumours, shocks
to ecosystems, neuronal avalanches, and many other spreading processes
Use of high resolution bathymetry and backscatter for mapping depositional environments on the New Hampshire continental shelf
The New Hampshire continental shelf is extremely heterogeneous and includes extensive bedrock outcrops, sand and gravel deposits and muddy basins. Many of the depositional features are glacial in origin and have been significantly modified by marine processes as sea level fluctuated since the end of the last major glaciation. Recent high resolution multibeam echosounder (MBES) bathymetric and backscatter surveys by the National Ocean Survey and University of New Hampshire Center for Coastal and Ocean Mapping/Joint Hydrographic Center has revealed features of the seafloor in exceptional detail that had not been previously described. Synthesis of the MBES bathymetry and backscatter, coupled with an extensive archived database consisting of subbottom seismics, bottom sediment grain size data and vibracores, is being used to develop new surficial geology maps and significantly improve our knowledge of the character and origin of the major depositional features of the New Hampshire shelf and vicinity (with support from the Bureau of Ocean Energy Management). Included are a number of large glacial features (e.g., drumlins) covering the bedrock that have been modified by marine processes (waves and currents). Some of the larger features were previously mapped (Birch, F.S. 1984. A geophysical survey of sedimentary deposits on the inner continental shelf of New Hampshire. Northeastern Geology 6:207-221), but the lack of high resolution bathymetry limited their characterization and interpretation. The new high resolution bathymetry and backscatter has resolved this limitation. Some of these deposits may represent significant sand and gravel deposits on the New Hampshire continental shelf that have the potential for future use for beach nourishment and other efforts to build coastal resiliency
dPV: An End-to-End Differentiable Solar-Cell Simulator
We introduce dPV, an end-to-end differentiable photovoltaic (PV) cell
simulator based on the drift-diffusion model and Beer-Lambert law for optical
absorption. dPV is programmed in Python using JAX, an automatic differentiation
(AD) library for scientific computing. Using AD coupled with the implicit
function theorem, dPV computes the power conversion efficiency (PCE) of an
input PV design as well as the derivative of the PCE with respect to any input
parameters, all within comparable time of solving the forward problem. We show
an example of perovskite solar-cell optimization and multi-parameter discovery,
and compare results with random search and finite differences. The simulator
can be integrated with optimization algorithms and neural networks, opening up
possibilities for data-efficient optimization and parameter discovery
Method and device for determining bond separation strength using induction heating
An induction heating device includes an induction heating gun which includes a housing, a U-shaped pole piece having two spaced apart opposite ends defining a gap there between, the U-shaped pole piece being mounted in one end of the housing, and a tank circuit including an induction coil wrapped around the pole piece and a capacitor connected to the induction coil. A power source is connected to the tank circuit. A pull test machine is provided having a stationary chuck and a movable chuck, the two chucks holding two test pieces bonded together at a bond region. The heating gun is mounted on the pull test machine in close proximity to the bond region of the two test pieces, whereby when the tank circuit is energized, the two test pieces are heated by induction heating while a tension load is applied to the two test pieces by the pull test machine to determine separation strength of the bond region
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