5,589 research outputs found
Symbolic Dynamics Analysis of the Lorenz Equations
Recent progress of symbolic dynamics of one- and especially two-dimensional
maps has enabled us to construct symbolic dynamics for systems of ordinary
differential equations (ODEs). Numerical study under the guidance of symbolic
dynamics is capable to yield global results on chaotic and periodic regimes in
systems of dissipative ODEs which cannot be obtained neither by purely
analytical means nor by numerical work alone. By constructing symbolic dynamics
of 1D and 2D maps from the Poincare sections all unstable periodic orbits up to
a given length at a fixed parameter set may be located and all stable periodic
orbits up to a given length may be found in a wide parameter range. This
knowledge, in turn, tells much about the nature of the chaotic limits. Applied
to the Lorenz equations, this approach has led to a nomenclature, i.e.,
absolute periods and symbolic names, of stable and unstable periodic orbits for
an autonomous system. Symmetry breakings and restorations as well as
coexistence of different regimes are also analyzed by using symbolic dynamics.Comment: 35 pages, LaTeX, 13 Postscript figures, uses psfig.tex. The revision
concerns a bug at the end of hlzfig12.ps which prevented the printing of the
whole .ps file from page 2
Global Weak Solutions to a General Liquid Crystals System
We prove the global existence of finite energy weak solutions to the general
liquid crystals system. The problem is studied in bounded domain of with
Dirichlet boundary conditions and the whole space
O ser-autor: deslocamentos entre a escrita científica e a escritura de si ( The being-author: shifts between scientific writing and self-writing)
Este artigo propõe uma reflexão, sustentada na teoria da Análise de Discurso, sobre a escrita científica e o seu imaginário de objetividade, a fim de pensar se há um espaço para o singular do pesquisador-autor na produção científica. A partir disso, discute-se a possibilidade de tomar a escrita científica como uma escritura de si, mostrando os elementos que estão em jogo no processo de escritura e suas relações com a subjetividade e com a constituição do ser-autor.PALAVRAS-CHAVE: Escrita Científica. Escrita de Si. Autoria. Análise de Discurso.
ABSTRACT This article proposes a reflection, sustained on the theory of Discourse Analysis, on scientific writing and its objectivity imaginary in order to think if there is a space for the singularity of the researcher-author in scientific production. From this, we discuss the possibility of taking scientific writing as self-writing, showing the elements that are at play in the writing process and its relation to subjectivity and to the constitution of the being-author.KEYWORDS: Scientific Writing. Self-Writing. Authorship. Discourse Analysis.This article proposes a reflection, sustained on the theory of Discourse Analysis, on scientific writing and its objectivity imaginary in order to think if there is a space for the singularity of the researcher-author in scientific production. From this, we discuss the possibility of taking scientific writing as self-writing, showing the elements that are at play in the writing process and its relation to subjectivity and to the constitution of the being-author.KEYWORDS: Scientific Writing. Self-Writing. Authorship. Discourse Analysis
Effective electro-optical modulation with high extinction ratio by a graphene-silicon microring resonator
Graphene opens up for novel optoelectronic applications thanks to its high
carrier mobility, ultra-large absorption bandwidth, and extremely fast material
response. In particular, the opportunity to control optoelectronic properties
through tuning of Fermi level enables electro-optical modulation,
optical-optical switching, and other optoelectronics applications. However,
achieving a high modulation depth remains a challenge because of the modest
graphene-light interaction in the graphene-silicon devices, typically,
utilizing only a monolayer or few layers of graphene. Here, we comprehensively
study the interaction between graphene and a microring resonator, and its
influence on the optical modulation depth. We demonstrate graphene-silicon
microring devices showing a high modulation depth of 12.5 dB with a relatively
low bias voltage of 8.8 V. On-off electro-optical switching with an extinction
ratio of 3.8 dB is successfully demonstrated by applying a square-waveform with
a 4 V peak-to-peak voltage.Comment: 12 pages, including 7 figure
Estimating Mass of Sigma-Meson and Study on Application of the Linear Sigma-Model
Whether the () exists as a real particle is a
long-standing problem in both particle physics and nuclear physics. In this
work, we analyze the deuteron binding energy in the linear model and
by fitting the data, we are able to determine the range of and
also investigate applicability of the linear model for the interaction
between hadrons in the energy region of MeV's. Our result shows that the best
fit to the data of the deuteron binding energy and other experimental data
about deuteron advocates a narrow range for the meson mass as MeV and the concrete values depend on the input parameters
such as the couplings. Inversely fitting the experimental data, our results set
constraints on the couplings. The other relevant phenomenological parameters in
the model are simultaneously obtained.Comment: 12 page
Observation and study of the decay
We report the observation and study of the decay
using events
collected with the BESIII detector. Its branching fraction, including all
possible intermediate states, is measured to be
. We also report evidence for a structure,
denoted as , in the mass spectrum in the GeV/
region. Using two decay modes of the meson ( and
), a simultaneous fit to the mass spectra is
performed. Assuming the quantum numbers of the to be , its
significance is found to be 4.4, with a mass and width of MeV/ and MeV, respectively, and a
product branching fraction
. Alternatively, assuming , the
significance is 3.8, with a mass and width of MeV/ and MeV, respectively, and a product
branching fraction
. The angular distribution of
is studied and the two assumptions of the
cannot be clearly distinguished due to the limited statistics. In all
measurements the first uncertainties are statistical and the second systematic.Comment: 10 pages, 6 figures and 4 table
Observation of a charged charmoniumlike structure in at GeV
We study the process at a
center-of-mass energy of 4.26GeV using a 827pb data sample obtained with
the BESIII detector at the Beijing Electron Positron Collider. Based on a
partial reconstruction technique, the Born cross section is measured to be
pb. We observe a structure near the
threshold in the recoil mass spectrum, which we denote as the
. The measured mass and width of the structure are
MeV/c and MeV, respectively. Its
production ratio is determined to be . The first uncertainties
are statistical and the second are systematic.Comment: 7 pages, 4 figures, 1 table; version accepted to be published in PR
Observation of an anomalous line shape of the mass spectrum near the mass threshold in
Using events collected by the BESIII experiment
in 2012, we study the
process and observe a significant abrupt change in the slope of the
invariant mass distribution at the
proton-antiproton () mass threshold. We use two models to
characterize the line shape around
: one which explicitly incorporates the opening of a
decay threshold in the mass spectrum (Flatt\'{e} formula), and another which is
the coherent sum of two resonant amplitudes. Both fits show almost equally good
agreement with data, and suggest the existence of either a broad state around
with strong couplings to final states or a
narrow state just below the mass threshold. Although we cannot
distinguish between the fits, either one supports the existence of a
molecule-like state or bound state with greater than significance
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