13,266 research outputs found
The Formation of Networks with Transfers among Players
We examine the formation of networks among a set of players whose payoffs depend on the structure of the network. We focus on games where players may bargain by promising or demanding transfer payments when forming links. We examine several variations of the transfer/bargaining aspect of link formation. One aspect is whether players can only make and receive transfers to other players to whom they are directly linked, or whether they can also subsidize links that they are not directly involved in. Another aspect is whether or not transfers related to a given link can be made contingent on the full resulting network or only on the link itself. A final aspect is whether or not players can pay other players to refrain from forming links. We characterize the networks that are supported under these variations and show how each of the above aspects is related either to accounting for a specific type of externality, or to dealing with the combinatorial nature of network payoffs.Networks, Network games, Network formation, Game theory, Efficient networks, Side payments, Transfers, Bargaining, Externalities
Spending time with money: from shared values to social connectivity
This article has been made available through the Brunel Open Access Publishing Fund.There is a rapidly growing momentum driving the development of mobile payment systems for co-present interactions, using near-field communication on smartphones and contactless payment systems. The design (and marketing) imperative for this is to enable faster, simpler, effortless and secure transactions, yet our evidence shows that this focus on reducing transactional friction may ignore other important features around making payments. We draw from empirical data to consider user interactions around financial exchanges made on mobile phones. Our findings examine how the practices around making payments support people in making connections, to other people, to their communities, to the places they move through, to their environment, and to what they consume. While these social and community bonds shape the kinds of interactions that become possible, they also shape how users feel about, and act on, the values that they hold with their co-users. We draw implications for future payment systems that make use of community connections, build trust, leverage transactional latency, and generate opportunities for rich social interactions
Overlap Dirac operator at nonzero chemical potential and random matrix theory
We show how to introduce a quark chemical potential in the overlap Dirac
operator. The resulting operator satisfies a Ginsparg-Wilson relation and has
exact zero modes. It is no longer gamma_5-hermitian, but its nonreal
eigenvalues still occur in pairs. We compute the spectral density of the
operator on the lattice and show that, for small eigenvalues, the data agree
with analytical predictions of nonhermitian chiral random matrix theory for
both trivial and nontrivial topology.Comment: 4 pages, 2 figure
Interaction induced fractional Bloch and tunneling oscillations
We study the dynamics of few interacting bosons in a one-dimensional lattice
with dc bias. In the absence of interactions the system displays single
particle Bloch oscillations. For strong interaction the Bloch oscillation
regime reemerges with fractional Bloch periods which are inversely proportional
to the number of bosons clustered into a bound state. The interaction strength
is affecting the oscillation amplitude. Excellent agreement is found between
numerical data and a composite particle dynamics approach. For specific values
of the interaction strength a particle will tunnel from the interacting cloud
to a well defined distant lattice location.Comment: 4 pages, 4 figure
The Formation of Networks with Transfers Among Players
We examine the formation of networks among a set of players whose payoffs depend on the structure of the network. We focus on games where players may bargain by promising or demanding transfer payments when forming links. We examine several variations of the transfer/bargaining aspect of link formation. One aspect is whether players can only make and receive transfers to other players to whom they are directly linked, or whether they can also subsidize links that they are not directly involved in. Another aspect is whether or not transfers related to a given link can be made contingent on the full resulting network or only on the link itself. A final aspect is whether or not players can pay other players to refrain from forming links. We characterize the networks that are supported under these variations and show how each of the above aspects is related
either to accounting for a specific type of externality, or to dealing with the combinatorial nature of network payoffs
Spanning forest polynomials and the transcendental weight of Feynman graphs
We give combinatorial criteria for predicting the transcendental weight of
Feynman integrals of certain graphs in theory. By studying spanning
forest polynomials, we obtain operations on graphs which are weight-preserving,
and a list of subgraphs which induce a drop in the transcendental weight.Comment: 30 page
Adiabatic loading of a Bose-Einstein condensate in a 3D optical lattice
We experimentally investigate the adiabatic loading of a Bose-Einstein
condensate into an optical lattice potential. The generation of excitations
during the ramp is detected by a corresponding decrease in the visibility of
the interference pattern observed after free expansion of the cloud. We focus
on the superfluid regime, where we show that the limiting time scale is related
to the redistribution of atoms across the lattice by single-particle tunneling
On one example and one counterexample in counting rational points on graph hypersurfaces
In this paper we present a concrete counterexample to the conjecture of
Kontsevich about the polynomial countability of graph hypersurfaces. In
contrast to this, we show that the "wheel with spokes" graphs are
polynomially countable
Streptozotocin and Alloxan-based Selection Improves Toxin Resistance of Insulin-Producing RINm Cells
The aim of our study was to develop a method for
selection of subpopulations of insulin producing
RINm cells with higher resistance to beta cell toxins.
Cells, resistant to streptozotocin (RINmS) and
alloxan (RINmA), were obtained by repeated exposure
of parental RINm cells to these two toxins,
while the defense capacity, was estimated by the
MTT colorimetric method, and [3H]-thymidine incorporation
assay. We found that RINmS and
RINmA displayed higher resistance to both streptozotocin
(STZ) and alloxan (AL) when compared to
the parental RINm cells. In contrast, no differences
in sensitivity to hydrogen peroxide were found
between toxin selected and parental cells. Partial
protection from the toxic effect of STZ and AL was
obtained only in the parental RINm cells after
preincubation of cells with the unmetabolizable 3-
O-methyl-glucose. The possibility that GLUT-2 is
involved in cell sensitivity to toxins was confirmed
by Western blot analysis, which showed higher
expression of GLUT-2 in parental RINm compared
to RINmS and RINmA cells. In addition to the
higher cell defense property evidenced in the
selected cells, we also found higher insulin content
and insulin secretion in both RINmS and RINmA
cells when compared to the parental RINm cells. In
conclusion, STZ and AL treatment can be used for
selection of cell sub-populations with higher cell defense properties and hormone production. The
different GLUT-2 expression in parental and re
sistant cells suggest involvement of GLUT-2 in
mechanisms of cell response to different toxins
Phase-matched four wave mixing and quantum beam splitting of matter waves in a periodic potential
We show that the dispersion properties imposed by an external periodic
potential ensure both energy and quasi-momentum conservation such that
correlated pairs of atoms can be generated by four wave mixing from a
Bose-Einstein condensate moving in an optical lattice potential. In our
numerical solution of the Gross-Pitaevskii equation, a condensate with initial
quasi-momentum k_0 is transferred almost completely (>95%) into a pair of
correlated atomic components with quasi-momenta k_1 and k_2, if the system is
seeded with a smaller number of atoms with the appropriate quasi-momentum k_1.Comment: 4 pages, 4 figures, version accepted for publication in Phys. Rev. A,
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