8,001 research outputs found
Direct Hopf Bifurcation in Parametric Resonance of Hybridized Waves
We study parametric resonance of interacting waves having the same wave
vector and frequency. In addition to the well-known period-doubling instability
we show that under certain conditions the instability is caused by a Hopf
bifurcation leading to quasiperiodic traveling waves. It occurs, for example,
if the group velocities of both waves have different signs and the damping is
weak. The dynamics above the threshold is briefly discussed. Examples
concerning ferromagnetic spin waves and surface waves of ferro fluids are
discussed.Comment: Appears in Phys. Rev. Lett., RevTeX file and three postscript
figures. Packaged using the 'uufiles' utility, 33 k
Brownian motion with dry friction: Fokker-Planck approach
We solve a Langevin equation, first studied by de Gennes, in which there is a
solid-solid or dry friction force acting on a Brownian particle in addition to
the viscous friction usually considered in the study of Brownian motion. We
obtain both the time-dependent propagator of this equation and the velocity
correlation function by solving the associated time-dependent Fokker-Planck
equation. Exact results are found for the case where only dry friction acts on
the particle. For the case where both dry and viscous friction forces are
present, series representations of the propagator and correlation function are
obtained in terms of parabolic cylinder functions. Similar series
representations are also obtained for the case where an external constant force
is added to the Langevin equation.Comment: 18 pages, 13 figures (in color
Resonant steps and spatiotemporal dynamics in the damped dc-driven Frenkel-Kontorova chain
Kink dynamics of the damped Frenkel-Kontorova (discrete sine-Gordon) chain
driven by a constant external force are investigated. Resonant steplike
transitions of the average velocity occur due to the competitions between the
moving kinks and their radiated phasonlike modes. A mean-field consideration is
introduced to give a precise prediction of the resonant steps. Slip-stick
motion and spatiotemporal dynamics on those resonant steps are discussed. Our
results can be applied to studies of the fluxon dynamics of 1D
Josephson-junction arrays and ladders, dislocations, tribology and other
fields.Comment: 20 Plain Latex pages, 10 Eps figures, to appear in Phys. Rev.
Climate change affecting oil palm agronomy, and oil palm cultivation increasing climate change, require amelioration
Palm oil is used in various valued commodities and is a large global industry worth over US$ 50 billion annually. Oil palms (OP) are grown commercially in Indonesia and Malaysia and other countries within Latin America and Africa. The large-scale land-use change has high ecological, economic, and social impacts. Tropical countries in particular are affected negatively by climate change (CC) which also has a detrimental impact on OP agronomy, whereas the cultivation of OP increases CC. Amelioration of both is required. The reduced ability to grow OP will reduce CC, which may allow more cultivation tending to increase CC, in a decreasing cycle. OP could be increasingly grown in more suitable regions occurring under CC. Enhancing the soil fauna may compensate for the effect of CC on OP agriculture to some extent. The effect of OP cultivation on CC may be reduced by employing reduced emissions from deforestation and forest degradation plans, for example, by avoiding illegal fire land clearing. Other ameliorating methods are reported herein. More research is required involving good management practices that can offset the increases in CC by OP plantations. Overall, OP-growing countries should support the Paris convention on reducing CC as the most feasible scheme for reducing CC.Portuguese Foundation for Science and
Technology (FCT), Grant/Award Number: UID/
BIO/04469/2013, COMPETE 2020 (POCI01-0145-FEDER-006684)
and BioTecNorte
operation (NORTE-01-0145-FEDER-000004);
European Regional Development Fund
through Norte2020—Programa Operacional
Regional do Norteinfo:eu-repo/semantics/publishedVersio
On the driven Frenkel-Kontorova model: I. Uniform sliding states and dynamical domains of different particle densities
The dynamical behavior of a harmonic chain in a spatially periodic potential
(Frenkel-Kontorova model, discrete sine-Gordon equation) under the influence of
an external force and a velocity proportional damping is investigated. We do
this at zero temperature for long chains in a regime where inertia and damping
as well as the nearest-neighbor interaction and the potential are of the same
order. There are two types of regular sliding states: Uniform sliding states,
which are periodic solutions where all particles perform the same motion
shifted in time, and nonuniform sliding states, which are quasi-periodic
solutions where the system forms patterns of domains of different uniform
sliding states. We discuss the properties of this kind of pattern formation and
derive equations of motion for the slowly varying average particle density and
velocity. To observe these dynamical domains we suggest experiments with a
discrete ring of at least fifty Josephson junctions.Comment: Written in RevTeX, 9 figures in PostScrip
Training and Onboarding initiatives in High Energy Physics experiments
In this paper we document the current analysis software training and
onboarding activities in several High Energy Physics (HEP) experiments: ATLAS,
CMS, LHCb, Belle II and DUNE. Fast and efficient onboarding of new
collaboration members is increasingly important for HEP experiments as analyses
and the related software become ever more complex with growing datasets. A
meeting series was held by the HEP Software Foundation (HSF) in 2022 for
experiments to showcase their initiatives. Here we document and analyse these
in an attempt to determine a set of key considerations for future experiments
Chronicles of Oklahoma
Notes and Documents, Chronicles of Oklahoma, Volume 43, Number 2, Summer 1965. It includes documents about the annual tour of the Oklahoma Historical Society, historical notes about Old Fort Washita, description of the Quapaw Pow Wow, a report on the history of the first Boy Scout troops in Oklahoma, and a report about the beginnings of the OHS
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