83 research outputs found
Nonzero-sum stochastic differential games between an impulse controller and a stopper
We study a two-player nonzero-sum stochastic differential game, where one player controls the state variable via additive impulses, while the other player can stop the game at any time. The main goal of this work is to characterize Nash equilibria through a verification theorem, which identifies a new system of quasivariational inequalities, whose solution gives equilibrium payoffs with the correspondent strategies. Moreover, we apply the verification theorem to a game with a one-dimensional state variable, evolving as a scaled Brownian motion, and with linear payoff and costs for both players. Two types of Nash equilibrium are fully characterized, i.e. semi-explicit expressions for the equilibrium strategies and associated payoffs are provided. Both equilibria are of threshold type: in one equilibrium playersâ intervention are not simultaneous, while in the other one the first player induces her competitor to stop the game. Finally, we provide some numerical results describing the qualitative properties of both types of equilibrium
Effect of moir\'e superlattice reconstruction in the electronic excitation spectrum of graphene-metal heterostructures
We have studied the electronic excitation spectrum in periodically rippled
graphene on Ru(0001) and flat, commensurate graphene on Ni(111) by means of
high-resolution electron energy loss spectroscopy and a combination of density
functional theory and tight-binding approaches. We show that the periodic
moir\'e superlattice originated by the lattice mismatch in graphene/Ru(0001)
induces the emergence of an extra mode, which is not present in
graphene/Ni(111). Contrary to the ordinary intra-band plasmon of doped
graphene, the extra mode is robust in charge-neutral graphene/metal contacts,
having its origin in electron-hole inter-band transitions between van Hove
singularities that emerge in the reconstructed band structure, due to the
moir\'e pattern superlattice.Comment: Supplemental materials available at
http://www.theorphys.science.ru.nl/people/yuan
Oversampling errors in multimodal medical imaging are due to the Gibbs effect
To analyse multimodal 3-dimensional medical images, interpolation is required
for resampling which - unavoidably - introduces an interpolation error. In this
work we consider three segmented 3-dimensional images resampled with three
different neuroimaging software tools for comparing undersampling and
oversampling strategies and to identify where the oversampling error lies. The
results indicate that undersampling to the lowest image size is advantageous in
terms of mean value per segment errors and that the oversampling error is
larger where the gradient is steeper, showing a Gibbs effect
2-D materials for ultra-scaled field-effect transistors: hundred candidates under the ab initio microscope
Thanks to their unique properties single-layer 2-D materials appear as
excellent candidates to extend Moore's scaling law beyond the currently
manufactured silicon FinFETs. However, the known 2-D semiconducting components,
essentially transition metal dichalcogenides, are still far from delivering the
expected performance. Based on a recent theoretical study that predicts the
existence of more than 1,800 exfoliable 2-D materials, we investigate here the
100 most promising contenders for logic applications. Their "current vs.
voltage" characteristics are simulated from first-principles, combining
density-functional theory and advanced quantum transport calculations. Both n-
and p-type configurations are considered, with gate lengths ranging from 15
down to 5 nm. From this unprecedented collection of electronic materials, we
identify 13 compounds with electron and hole currents potentially much higher
than in future Si FinFETs. The resulting database widely expands the design
space of 2-D transistors and provides original guidelines to the materials and
device engineering community
Possible Fano resonance for high-T-c multi-gap superconductivity in p-Terphenyl doped by K at the Lifshitz transition
Recent experiments have reported the emergence of high temperature
superconductivity with critical temperature between 43K and 123K in a
potassium doped aromatic hydrocarbon para-Terphenyl or p-Terphenyl. This
achievement provides the record for the highest Tc in an organic superconductor
overcoming the previous record of Tc=38 K in Cs3C60 fulleride. Here we propose
that the driving mechanism is the quantum resonance between superconducting
gaps near a Lifshitz transition which belongs to the class of Fano resonances
called shape resonances. For the case of p-Terphenyl our numerical solutions of
the multi gap equation shows that high Tc is driven by tuning the chemical
potential by K doping and it appears only in a narrow energy range near a
Lifshitz transition. At the maximum critical temperature, Tc=123K, the
condensate in the appearing new small Fermi surface pocket is in the BCS-BEC
crossover while the Tc drops below 0.3 K where it is in the BEC regime. Finally
we predict the experimental results which can support or falsify our proposed
mechanism: a) the variation of the isotope coefficient as a function of the
critical temperature and b) the variation of the gaps and their ratios
2Delta/Tc as a function of Tc.Comment: 7 pages, 7 figure
ANATOMICAL LANDMARKS AND SURGICAL TEMPLATES OF LYMPHNODE DISSECTION FOR UPPER TRACT UROTHELIAL CARCINOMA: A SYSTEMATIC REVIEW OFTHE LITERATURE
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