620 research outputs found
`The dragon breathes smoke': cigarette counterfeiting in the People's Republic of China
This article aims at providing an account of the social organization of the cigarette counterfeiting business in the People's Republic of China—a business that has been feeding the cigarette black markets around the globe. Specifically, we aim to exhibit the scale and nature of cigarette counterfeiting in mainland China, describe the practices and actors in the different phases of the trade, and examine the role of corruption and violence in the particular business. We argue that cigarette counterfeiting is one of the side effects of China's reform and ‘opening up’ policy, and a feature of the country's economic development process
Stability of Simple Periodic Orbits and Chaos in a Fermi -- Pasta -- Ulam Lattice
We investigate the connection between local and global dynamics in the Fermi
-- Pasta -- Ulam (FPU) -- model from the point of view of stability of
its simplest periodic orbits (SPOs). In particular, we show that there is a
relatively high mode of the linear lattice, having one
particle fixed every two oppositely moving ones (called SPO2 here), which can
be exactly continued to the nonlinear case for and whose
first destabilization, , as the energy (or ) increases for {\it
any} fixed , practically {\it coincides} with the onset of a ``weak'' form
of chaos preceding the break down of FPU recurrences, as predicted recently in
a similar study of the continuation of a very low () mode of the
corresponding linear chain. This energy threshold per particle behaves like
. We also follow exactly the properties of
another SPO (with ) in which fixed and moving particles are
interchanged (called SPO1 here) and which destabilizes at higher energies than
SPO2, since . We find that, immediately after
their first destabilization, these SPOs have different (positive) Lyapunov
spectra in their vicinity. However, as the energy increases further (at fixed
), these spectra converge to {\it the same} exponentially decreasing
function, thus providing strong evidence that the chaotic regions around SPO1
and SPO2 have ``merged'' and large scale chaos has spread throughout the
lattice.Comment: Physical Review E, 18 pages, 6 figure
Scaling similarities of multiple fracturing of solid materials
It has recently reported that electromagnetic flashes of low-energy <IMG WIDTH='12' HEIGHT='29' ALIGN='MIDDLE' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img1.gif' ALT=''>-rays emitted during multi-fracturing on a neutron star, and electromagnetic pulses emitted in the laboratory by a disordered material subjected to an increasing external load, share distinctive statistical properties with earthquakes, such as power-law energy distributions (Cheng et al., 1996; Kossobokov et al., 2000; Rabinovitch et al., 2001; Sornette and Helmstetter, 2002). The neutron starquakes may release strain energies up to <IMG WIDTH='32' HEIGHT='16' ALIGN='BOTTOM' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img2.gif' ALT=''>erg, while, the fractures in laboratory samples release strain energies approximately a fraction of an erg. An earthquake fault region can build up strain energy up to approximately <IMG WIDTH='32' HEIGHT='16' ALIGN='BOTTOM' BORDER='0' src='http://www.nonlin-processes-geophys.net/11/137/2004/npg-11-137-img3.gif' ALT=''>erg for the strongest earthquakes. Clear sequences of kilohertz-megahertz electromagnetic avalanches have been detected from a few days up to a few hours prior to recent destructive earthquakes in Greece. A question that arises effortlessly is if the pre-seismic electromagnetic fluctuations also share the same statistical properties. Our study justifies a positive answer. Our analysis also reveals 'symptoms' of a transition to the main rupture common with earthquake sequences and acoustic emission pulses observed during laboratory experiments (Maes et al., 1998)
Time--Evolving Statistics of Chaotic Orbits of Conservative Maps in the Context of the Central Limit Theorem
We study chaotic orbits of conservative low--dimensional maps and present
numerical results showing that the probability density functions (pdfs) of the
sum of iterates in the large limit exhibit very interesting
time-evolving statistics. In some cases where the chaotic layers are thin and
the (positive) maximal Lyapunov exponent is small, long--lasting
quasi--stationary states (QSS) are found, whose pdfs appear to converge to
--Gaussians associated with nonextensive statistical mechanics. More
generally, however, as increases, the pdfs describe a sequence of QSS that
pass from a --Gaussian to an exponential shape and ultimately tend to a true
Gaussian, as orbits diffuse to larger chaotic domains and the phase space
dynamics becomes more uniformly ergodic.Comment: 15 pages, 14 figures, accepted for publication as a Regular Paper in
the International Journal of Bifurcation and Chaos, on Jun 21, 201
Unified approach to catastrophic events: from the normal state to geological or biological shock in terms of spectral fractal and nonlinear analysis
An important question in geophysics is whether earthquakes (EQs) can be anticipated prior to their occurrence. Pre-seismic electromagnetic (EM) emissions provide a promising window through which the dynamics of EQ preparation can be investigated. However, the existence of precursory features in pre-seismic EM emissions is still debatable: in principle, it is difficult to prove associations between events separated in time, such as EQs and their EM precursors. The scope of this paper is the investigation of the pre-seismic EM activity in terms of complexity. A basic reason for our interest in complexity is the striking similarity in behavior close to irreversible phase transitions among systems that are otherwise quite different in nature. Interestingly, theoretical studies (Hopfield, 1994; Herz and Hopfield 1995; Rundle et al., 1995; Corral et al., 1997) suggest that the EQ dynamics at the final stage and neural seizure dynamics should have many similar features and can be analyzed within similar mathematical frameworks. Motivated by this hypothesis, we evaluate the capability of linear and non-linear techniques to extract common features from brain electrical activities and pre-seismic EM emissions predictive of epileptic seizures and EQs respectively. The results suggest that a unified theory may exist for the ways in which firing neurons and opening cracks organize themselves to produce a large crisis, while the preparation of an epileptic shock or a large EQ can be studied in terms of ''Intermittent Criticality''
Engineering of composite metallic microfibers towards development of plasmonic devices for sensing applications
The paper discusses the analysis of tapered hybrid composite microfibers based on a metal-core and dielectric-cladding composite material system. Its advantages over the pure metal tips conventionally used, are the inherent enhanced environmental robustness due to inert borosilicate cladding and the capability of multiple excitation of the tapered nanowire through the length of the fiber due to the enabled total internal reflection at the borosilicate/air interface. Simulations through finite element method (FEM) have demonstrated an improved field enhancement at the tapered region of such microfibers. Furthermore, experimental results on tapering in copper based microfibers together with light coupling and propagation studies will be demonstrated revealing the potential for the development of plasmonic devices for sensing applications
Case series and a systematic review concerning the level of the aortic bifurcation
Background: The aim of this study is to present the level of aortic bifurcation in a sample of Greek origin (case series) and to perform an up-to-date systematic review in the existing literature. Materials and methods: Seventy-six formalin-fixed adult cadavers were dissected and studied in order to research the level of aortic bifurcation. Additionally, PubMed and Google Scholar databases were searched for eligible articles concerning the level of aortic bifurcation for the period up to February 2020. Results: The mean level of aortic bifurcation according to our case series was the lower third of the L4 vertebral body (21/76, 27.6%). The level of aortic bifurcation ranged between the lower third of the L3 vertebral body and the lower third of the L5 body. No statistically significant correlation was found between the two sexes. The systematic review of the literature revealed 31 articles which were considered eligible and a total number of 3537 specimens were retracted. According to the recorded findings the most common mean level of aortic bifurcation was the body of L4 vertebra (1495/3537 cases, 42.2%), while the range of aortic bifurcation was described to occur from upper third of L3 vertebrae to the upper third of the S1 vertebrae in the 52.8% of the cases (1866/3537). Conclusions: The mean level of AA corresponds to the body of L4 and presents a great range (form L3U to S1U). Knowledge of the mean level of aortic bifurcation and its probable ranges is of great significance for interventional radiologists and especially vascular surgeons that deal with aneurism proximal to the aortic bifurcation
- …