12,993 research outputs found
Progressive managerial bonuses in a spatial Bertrand duopoly
The relationship of managerial bonuses and profit maximization is interesting both from an economic and a managerial viewpoint. Our contribution to this literature is showing that progressive managerial bonuses can increase profits in a spatial Bertrand competition, and furthermore they can help collusion
Anomalous temperature evolution of the internal magnetic field distribution in the charge-ordered triangular antiferromagnet AgNiO2
Zero-field muon-spin relaxation measurements of the frustrated triangular
quantum magnet AgNiO2 are consistent with a model of charge disproportionation
that has been advanced to explain the structural and magnetic properties of
this compound. Below an ordering temperature of T_N=19.9(2) K we observe six
distinct muon precession frequencies, due to the magnetic order, which can be
accounted for with a model describing the probable muon sites. The precession
frequencies show an unusual temperature evolution which is suggestive of the
separate evolution of two opposing magnetic sublattices.Comment: 4 pages, 3 figure
Improved Fixed-Budget Results via Drift Analysis
Fixed-budget theory is concerned with computing or bounding the fitness value
achievable by randomized search heuristics within a given budget of fitness
function evaluations. Despite recent progress in fixed-budget theory, there is
a lack of general tools to derive such results. We transfer drift theory, the
key tool to derive expected optimization times, to the fixed-budged
perspective. A first and easy-to-use statement concerned with iterating drift
in so-called greed-admitting scenarios immediately translates into bounds on
the expected function value. Afterwards, we consider a more general tool based
on the well-known variable drift theorem. Applications of this technique to the
LeadingOnes benchmark function yield statements that are more precise than the
previous state of the art.Comment: 25 pages. An extended abstract of this paper will be published in the
proceedings of PPSN 202
Two-Dimensional Spectroscopy of Extended Molecular Systems: Applications to Energy Transport and Relaxation in an α-Helix
A simulation study of the coupled dynamics of amide I and amide II vibrations in an α-helix dissolved in water shows that two-dimensional (2D) infrared spectroscopy may be used to disentangle the energy transport along the helix through each of these modes from the energy relaxation between them. Time scales for both types of processes are obtained. Using polarization-dependent 2D spectroscopy is an important ingredient in the method we propose. The method may also be applied to other two-band systems, both in the infrared (collective vibrations) and the visible (excitons) parts of the spectrum.
Structure of the lightest tin isotopes
We link the structure of nuclei around Sn, the heaviest doubly magic
nucleus with equal neutron and proton numbers (), to nucleon-nucleon
() and three-nucleon () forces constrained by data of few-nucleon
systems. Our results indicate that Sn is doubly magic, and we predict
its quadrupole collectivity. We present precise computations of Sn
based on three-particle--two-hole excitations of Sn, and reproduce the
small splitting between the lowest and states. Our
results are consistent with the sparse available data.Comment: 8 pages, 4 figure
A theoretical investigation of ferromagnetic tunnel junctions with 4-valued conductances
In considering a novel function in ferromagnetic tunnel junctions consisting
of ferromagnet(FM)/barrier/FM junctions, we theoretically investigate multiple
valued (or multi-level) cell property, which is in principle realized by
sensing conductances of four states recorded with magnetization configurations
of two FMs; that is, (up,up), (up,down), (down,up), (down,down). To obtain such
4-valued conductances, we propose FM1/spin-polarized barrier/FM2 junctions,
where the FM1 and FM2 are different ferromagnets, and the barrier has spin
dependence. The proposed idea is applied to the case of the barrier having
localized spins. Assuming that all the localized spins are pinned parallel to
magnetization axes of the FM1 and FM2, 4-valued conductances are explicitly
obtained for the case of many localized spins. Furthermore, objectives for an
ideal spin-polarized barrier are discussed.Comment: 9 pages, 3 figures, accepted for publication in J. Phys.: Condens.
Matte
Magnetotransport and the upper critical magnetic field in MgB2
Magnetotransport measurements are presented on polycrystalline MgB2 samples.
The resistive upper critical magnetic field reveals a temperature dependence
with a positive curvature from Tc = 39.3 K down to about 20 K, then changes to
a slightly negative curvature reaching 25 T at 1.5 K. The 25- Tesla upper
critical field is much higher than what is known so far on polycrystals of MgB2
but it is in agreement with recent data obtained on epitaxial MgB2 films. The
deviation of Bc2(T) from standard BCS might be due to the proposed two-gap
superconductivity in this compound. The observed quadratic normal-state
magnetoresistance with validity of Kohler's rule can be ascribed to classical
trajectory effects in the low-field limit.Comment: 6 pages, incl. 3 figure
Discrepancy between experimental and theoretical -decay rates resolved from first principles
-decay, a process that changes a neutron into a proton (and vice
versa), is the dominant decay mode of atomic nuclei. This decay offers a unique
window to physics beyond the standard model, and is at the heart of
microphysical processes in stellar explosions and the synthesis of the elements
in the Universe. For 50 years, a central puzzle has been that observed
-decay rates are systematically smaller than theoretical predictions.
This was attributed to an apparent quenching of the fundamental coupling
constant 1.27 in the nucleus by a factor of about 0.75 compared
to the -decay of a free neutron. The origin of this quenching is
controversial and has so far eluded a first-principles theoretical
understanding. Here we address this puzzle and show that this quenching arises
to a large extent from the coupling of the weak force to two nucleons as well
as from strong correlations in the nucleus. We present state-of-the-art
computations of -decays from light to heavy nuclei. Our results are
consistent with experimental data, including the pioneering measurement for
Sn. These theoretical advances are enabled by systematic effective
field theories of the strong and weak interactions combined with powerful
quantum many-body techniques. This work paves the way for systematic
theoretical predictions for fundamental physics problems. These include the
synthesis of heavy elements in neutron star mergers and the search for
neutrino-less double--decay, where an analogous quenching puzzle is a
major source of uncertainty in extracting the neutrino mass scale.Comment: 20 pages, 18 figure
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