107 research outputs found
Team-maxmin equilibrium: Efficiency bounds and algorithms
The Team-maxmin equilibrium prescribes the optimal strategies for a team of rational players sharing the same goal and without the capability of correlating their strategies in strategic games against an adversary. This solution concept can capture situations in which an agent controls multiple resources-corresponding to the team members-that cannot communicate. It is known that such equilibrium always exists and it is unique (except degenerate cases) and these properties make it a credible solution concept to be used in real-world applications, especially in security scenarios. Nevertheless, to the best of our knowledge, the Team-maxmin equilibrium is almost completely unexplored in the literature. In this paper, we investigate bounds of (in) efficiency of the Team-maxmin equilibrium w.r.t. the Nash equilibria and w.r.t. the Maxmin equilibrium when the team members can play correlated strategies. Furthermore, we study a number of algorithms to find and/or approximate an equilibrium, discussing their theoretical guarantees and evaluating their performance by using a standard testbed of game instances
Applications of Magnetic PsiDO Techniques to Space-adiabatic Perturbation Theory
In this review, we show how advances in the theory of magnetic
pseudodifferential operators (magnetic DO) can be put to good use in
space-adiabatic perturbation theory (SAPT). As a particular example, we extend
results of [PST03] to a more general class of magnetic fields: we consider a
single particle moving in a periodic potential which is subjectd to a weak and
slowly-varying electromagnetic field. In addition to the semiclassical
parameter \eps \ll 1 which quantifies the separation of spatial scales, we
explore the influence of additional parameters that allow us to selectively
switch off the magnetic field.
We find that even in the case of magnetic fields with components in
, e. g. for constant magnetic fields, the results of
Panati, Spohn and Teufel hold, i.e. to each isolated family of Bloch bands,
there exists an associated almost invariant subspace of and an
effective hamiltonian which generates the dynamics within this almost invariant
subspace. In case of an isolated non-degenerate Bloch band, the full quantum
dynamics can be approximated by the hamiltonian flow associated to the
semiclassical equations of motion found in [PST03].Comment: 32 page
HDAC6 mediates the acetylation of TRIM50
The E3 Ubiquitin ligase TRIM50 promotes the formation and clearance of aggresome-associated polyubiquitinated proteins through HDAC6 interaction, a tubulin specific deacetylase that regulates microtubule-dependent aggresome formation. In this report we showed that TRIM50 is a target of HDAC6 with Lys-372 as a critical residue for acetylation. We identified p300 and PCAF as two TRIM50 acetyltransferases and we further showed that a balance between ubiquitination and acetylation regulates TRIM50 degradatio
Gauge-theoretic invariants for topological insulators: A bridge between Berry, Wess-Zumino, and Fu-Kane-Mele
We establish a connection between two recently-proposed approaches to the
understanding of the geometric origin of the Fu-Kane-Mele invariant
, arising in the context of 2-dimensional
time-reversal symmetric topological insulators. On the one hand, the
invariant can be formulated in terms of the Berry connection and
the Berry curvature of the Bloch bundle of occupied states over the Brillouin
torus. On the other, using techniques from the theory of bundle gerbes it is
possible to provide an expression for containing the square root
of the Wess-Zumino amplitude for a certain -valued field over the
Brillouin torus.
We link the two formulas by showing directly the equality between the above
mentioned Wess-Zumino amplitude and the Berry phase, as well as between their
square roots. An essential tool of independent interest is an equivariant
version of the adjoint Polyakov-Wiegmann formula for fields , of which we provide a proof employing only basic homotopy theory and
circumventing the language of bundle gerbes.Comment: 23 pages, 1 figure. To appear in Letters in Mathematical Physic
Semi- and Non-relativistic Limit of the Dirac Dynamics with External Fields
We show how to approximate Dirac dynamics for electronic initial states by
semi- and non-relativistic dynamics. To leading order, these are generated by
the semi- and non-relativistic Pauli hamiltonian where the kinetic energy is
related to and , respectively. Higher-order
corrections can in principle be computed to any order in the small parameter
v/c which is the ratio of typical speeds to the speed of light. Our results
imply the dynamics for electronic and positronic states decouple to any order
in v/c << 1.
To decide whether to get semi- or non-relativistic effective dynamics, one
needs to choose a scaling for the kinetic momentum operator. Then the effective
dynamics are derived using space-adiabatic perturbation theory by Panati et. al
with the novel input of a magnetic pseudodifferential calculus adapted to
either the semi- or non-relativistic scaling.Comment: 42 page
Semiclassical approximations for Hamiltonians with operator-valued symbols
We consider the semiclassical limit of quantum systems with a Hamiltonian
given by the Weyl quantization of an operator valued symbol. Systems composed
of slow and fast degrees of freedom are of this form. Typically a small
dimensionless parameter controls the separation of time
scales and the limit corresponds to an adiabatic limit, in
which the slow and fast degrees of freedom decouple. At the same time
is the semiclassical limit for the slow degrees of freedom.
In this paper we show that the -dependent classical flow for the
slow degrees of freedom first discovered by Littlejohn and Flynn, coming from
an \epsi-dependent classical Hamilton function and an -dependent
symplectic form, has a concrete mathematical and physical meaning: Based on
this flow we prove a formula for equilibrium expectations, an Egorov theorem
and transport of Wigner functions, thereby approximating properties of the
quantum system up to errors of order . In the context of Bloch
electrons formal use of this classical system has triggered considerable
progress in solid state physics. Hence we discuss in some detail the
application of the general results to the Hofstadter model, which describes a
two-dimensional gas of non-interacting electrons in a constant magnetic field
in the tight-binding approximation.Comment: Final version to appear in Commun. Math. Phys. Results have been
strengthened with only minor changes to the proofs. A section on the
Hofstadter model as an application of the general theory was added and the
previous section on other applications was remove
A relocatable ocean model in support of environmental emergencies
During the Costa Concordia emergency case, regional, subregional, and relocatable ocean models have been used together with the oil spill model, MEDSLIK-II, to provide ocean currents forecasts, possible oil spill scenarios, and drifters trajectories simulations. The models results together with the evaluation of their performances are presented in this paper. In particular, we focused this work on the implementation of the Interactive Relocatable Nested Ocean Model (IRENOM), based on the Harvard Ocean Prediction System (HOPS), for the Costa Concordia emergency and on its validation using drifters released in the area of the accident. It is shown that thanks to the capability of improving easily and quickly its configuration, the IRENOM results are of greater accuracy than the results achieved using regional or subregional model products. The model topography, and to the initialization procedures, and the horizontal resolution are the key model settings to be configured. Furthermore, the IRENOM currents and the MEDSLIK-II simulated trajectories showed to be sensitive to the spatial resolution of the meteorological fields used, providing higher prediction skills with higher resolution wind forcing.MEDESS4MS Project; TESSA Project; MyOcean2 Projectinfo:eu-repo/semantics/publishedVersio
Inhibition of G-protein signalling in cardiac dysfunction of intellectual developmental disorder with cardiac arrhythmia (IDDCA) syndrome
BACKGROUND: Pathogenic variants of GNB5 encoding the β5 subunit of the guanine nucleotide-binding protein cause IDDCA syndrome, an autosomal recessive neurodevelopmental disorder associated with cognitive disability and cardiac arrhythmia, particularly severe bradycardia. METHODS: We used echocardiography and telemetric ECG recordings to investigate consequences of Gnb5 loss in mouse. RESULTS: We delineated a key role of Gnb5 in heart sinus conduction and showed that Gnb5-inhibitory signalling is essential for parasympathetic control of heart rate (HR) and maintenance of the sympathovagal balance. Gnb5-/- mice were smaller and had a smaller heart than Gnb5+/+ and Gnb5+/- , but exhibited better cardiac function. Lower autonomic nervous system modulation through diminished parasympathetic control and greater sympathetic regulation resulted in a higher baseline HR in Gnb5-/- mice. In contrast, Gnb5-/- mice exhibited profound bradycardia on treatment with carbachol, while sympathetic modulation of the cardiac stimulation was not altered. Concordantly, transcriptome study pinpointed altered expression of genes involved in cardiac muscle contractility in atria and ventricles of knocked-out mice. Homozygous Gnb5 loss resulted in significantly higher frequencies of sinus arrhythmias. Moreover, we described 13 affected individuals, increasing the IDDCA cohort to 44 patients. CONCLUSIONS: Our data demonstrate that loss of negative regulation of the inhibitory G-protein signalling causes HR perturbations in Gnb5-/- mice, an effect mainly driven by impaired parasympathetic activity. We anticipate that unravelling the mechanism of Gnb5 signalling in the autonomic control of the heart will pave the way for future drug screening
Topological Photonics
Topology is revolutionizing photonics, bringing with it new theoretical
discoveries and a wealth of potential applications. This field was inspired by
the discovery of topological insulators, in which interfacial electrons
transport without dissipation even in the presence of impurities. Similarly,
new optical mirrors of different wave-vector space topologies have been
constructed to support new states of light propagating at their interfaces.
These novel waveguides allow light to flow around large imperfections without
back-reflection. The present review explains the underlying principles and
highlights the major findings in photonic crystals, coupled resonators,
metamaterials and quasicrystals.Comment: progress and review of an emerging field, 12 pages, 6 figures and 1
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