6,501 research outputs found
Multi-q Pattern Classification of Polarization Curves
Several experimental measurements are expressed in the form of
one-dimensional profiles, for which there is a scarcity of methodologies able
to classify the pertinence of a given result to a specific group. The
polarization curves that evaluate the corrosion kinetics of electrodes in
corrosive media are an application where the behavior is chiefly analyzed from
profiles. Polarization curves are indeed a classic method to determine the
global kinetics of metallic electrodes, but the strong nonlinearity from
different metals and alloys can overlap and the discrimination becomes a
challenging problem. Moreover, even finding a typical curve from replicated
tests requires subjective judgement. In this paper we used the so-called
multi-q approach based on the Tsallis statistics in a classification engine to
separate multiple polarization curve profiles of two stainless steels. We
collected 48 experimental polarization curves in aqueous chloride medium of two
stainless steel types, with different resistance against localized corrosion.
Multi-q pattern analysis was then carried out on a wide potential range, from
cathodic up to anodic regions. An excellent classification rate was obtained,
at a success rate of 90%, 80%, and 83% for low (cathodic), high (anodic), and
both potential ranges, respectively, using only 2% of the original profile
data. These results show the potential of the proposed approach towards
efficient, robust, systematic and automatic classification of highly non-linear
profile curves.Comment: 12 pages, 7 figure
Efficient Likelihood Evaluation of State-Space Representations
We develop a numerical procedure that facilitates efficient likelihood evaluation in applications involving non-linear and non-Gaussian state-space models. The procedure employs continuous approximations of filtering densities, and delivers unconditionally optimal global approximations of targeted integrands to achieve likelihood approximation. Optimized approximations of targeted integrands are constructed via efficient importance sampling. Resulting likelihood approximations are continuous functions of model parameters, greatly enhancing parameter estimation. We illustrate our procedure in applications to dynamic stochastic general equilibrium models.Adaption, dynamic stochastic general equilibrium model, efficient importance sampling, kernel density approximation, particle filter.
3,7-Bis(dialkylamino)phenothiazin-5-ium derivatives: biomedical applications and biological activity
The light-induced reactions of 3,7-bis(dialkylamino)phenothiazin-5-ium
compounds with biological substrates are briefly discussed. Their biomedical
applications, in particular those related with biological staining, interaction with proteins
and antiviral, antibacterial and antitumour activity are reviewed.info:eu-repo/semantics/publishedVersio
On Dirac-like Monopoles in a Lorentz- and CPT-violating Electrodynamics
We study magnetic monopoles in a Lorentz- and CPT-odd electrodynamical
framework in (3+1) dimensions. This is the standard Maxwell model extended by
means of a Chern-Simons-like term, (
constant), which respects gauge invariance but violates both Lorentz and CPT
symmetries (as a consequence, duality is also lost). Our main interest concerns
the analysis of the model in the presence of Dirac monopoles, so that the
Bianchi identity no longer holds, which naively yields the non-conservation of
electric charge. Since gauge symmetry is respected, the issue of charge
conservation is more involved. Actually, the inconsistency may be circumvented,
if we assume that the appearance of a monopole induces an extra electric
current. The reduction of the model to (2+1) dimensions in the presence of both
the magnetic sources and Lorentz-violating terms is presented. There, a
quantization condition involving the scalar remnant of , say, the mass
parameter, is obtained. We also point out that the breaking of duality may be
associated with an asymmetry between electric and magnetic sources in this
background, so that the electromagnetic force experienced by a magnetic pole is
supplemented by an extra term proportional to , whenever compared to the
one acting on an electric charge.Comment: 10 pages, no figures, typed in te
Sustainable forest management of miombo woodlands in Niassa National Reserve, northern Mozambique: a multidisciplinary approach of fire resistance analysis.
Poster presented at XIII World Forestry Congress. Buenos Aires (Argentina). 18 - 23 Oct 2009
How hole defects modify vortex dynamics in ferromagnetic nanodisks
Defects introduced in ferromagnetic nanodisks may deeply affect the structure
and dynamics of stable vortex-like magnetization. Here, analytical techniques
are used for studying, among other dynamical aspects, how a small cylindrical
cavity modify the oscillatory modes of the vortex. For instance, we have
realized that if the vortex is nucleated out from the hole its gyrotropic
frequencies are shifted below. Modifications become even more pronounced when
the vortex core is partially or completely captured by the hole. In these
cases, the gyrovector can be partially or completely suppressed, so that the
associated frequencies increase considerably, say, from some times to several
powers. Possible relevance of our results for understanding other aspects of
vortex dynamics in the presence of cavities and/or structural defects are also
discussed.Comment: 9 pages, 4 page
The influence of metabolic profile of obese men on the severity of erectile dysfunction: Are metabolically healthy obese individuals protected?
Objective: To determine the prevalence of erectile dysfunction (ED) in metabolically healthy obese (MHO) individuals, and to compare ED severity and hypogonadism prevalence in MHO, metabolically unhealthy obese (MUO) and metabolically healthy non-obese individuals.Material and methods: ED patients (n=460) were evaluated by standardized protocol, that included clinical evaluation, abridged 5-item version of the International Index of Erectile Function (IIEF-5) questionnaire survey, and Penile Duplex Doppler Ultrasound (PDDU) exam. Patients were classified as obese [body mass index (BMI) =30.0 kg/m2] and non-obese (BMI <30.0 kg/m2), and metabolic health status was defined by National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII) criteria. Statistical analysis was performed and statistical significance was considered at p-level <0.05.Results: The mean age of the subjects was 56.2±10.5 years. MHO was present in 40% of obese individuals (n=37). MUO had lower mean peak systolic velocity (mPSV) compared to MHO (28.1 cm/s vs. 36.9 cm/s; p=0.005), and IIEF-5 scores were also lower in MUO compared to MHO patients (10.2 vs. 13.1; p=0.018). No statistical differences in IIEF-5 score, mPSV and hypogonadism prevalence between MHO and metabolically healthy non-obese (MHNO) patients were observed.Conclusion: Our results lead us to conclude that healthy metabolic profile protects obese individuals from severity of ED. The strong association between obesity and ED may be otherwise attributed to metabolic abnormalities present in the obese
Bloch-like oscillations in a one-dimensional lattice with long-range correlated disorder
We study the dynamics of an electron subjected to a uniform electric field
within a tight-binding model with long-range-correlated diagonal disorder. The
random distribution of site energies is assumed to have a power spectrum with . Moura and Lyra [Phys. Rev. Lett. {\bf
81}, 3735 (1998)] predicted that this model supports a phase of delocalized
states at the band center, separated from localized states by two mobility
edges, provided . We find clear signatures of Bloch-like
oscillations of an initial Gaussian wave packet between the two mobility edges
and determine the bandwidth of extended states, in perfect agreement with the
zero-field prediction.Comment: 4 pages, 5 figure
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