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

Horizontal pressures in cylindrical metal silos and comparison with different international standards

The focus of this research was to evaluate the horizontal pressures on a cylindrical metal silo of corrugated walls and flat bottom with 1.82m diameter and 5.4m high, and to compare the values with those obtained theoretically by the ISO 11697, EP 433 and AS 3774 standards. The silo was symmetrically filled and constant speed with wheat cv. soft red for two different height/diameter ratios (H/D) and was unloaded through three orifices with a diameter of 71.6mm, one concentric and two eccentrics. Horizontal pressures were measured on the walls of the silo at three positions using hydraulic type pressure cells. The results showed that shortly after the start of the unloading, there was a mass flow above the quota of H/D = 1.2, whereas below this quota funnel flow occurred. It can be said that the EP 433 standard was more appropriate to predict horizontal pressures in silos in H/D ratio = 1.0, with eccentric unloading. For the H/D ratio = 1.5, AS 3774 standard was the one that produced values closer to the experimental

Modeling disorder in graphene

We present a study of different models of local disorder in graphene. Our focus is on the main effects that vacancies -- random, compensated and uncompensated --, local impurities and substitutional impurities bring into the electronic structure of graphene. By exploring these types of disorder and their connections, we show that they introduce dramatic changes in the low energy spectrum of graphene, viz. localized zero modes, strong resonances, gap and pseudogap behavior, and non-dispersive midgap zero modes.Comment: 16 pages, lower resolution figure

Anemia and Iron Deficiency Diagnosis, Management and Treatment in Chronic Kidney Disease - Consensus and Agreement through a Delphi Panel

Background: Anemia is a common complication of Chronic Kidney Disease (CKD), in which iron deficiency’s (ID) role is frequently underrated. In CKD, anemia has been associated with higher morbidity and lower quality of life. Nonetheless, reported treatment rates of anemia in CKD are low and guidelines’ variability and/or absence for its management and treatment may be preventing patients from receiving optimal treatment. Within this context, we aimed to assess the agreement level on anemia and iron deficiency diagnosis, management, and treatment in CKD patients, by Portuguese physicians in Nephrology, through a Delphi Panel. Methods: A group of seven medical experts in Nephrology and Transfusion Medicine was assembled, and a focus group was conducted, in which 28 statements were agreed upon. Then, a two-round Delphi Panel using a Likert scale was conducted online, inviting Portuguese Society of Nephrology associates to participate. Results: Answers were collected from 76 participants in Round 1 and consensus level was obtained for 1 statement, 57 (75%) respondents fully disagreeing on transfusing all patients with hemoglobin below 9 g/dl, regardless of the clinical situation. The remaining 27 statements were used in Round 2, none obtaining consensus level and 14 statements being categorized as qualified majority: 4 on diagnosis, 3 on disease management, and 7 on treatment. Discussion: Our study showed a lack of consensus on diagnosis, management, and treatment of anemia in CKD patients among the nephrology community in Portugal. Overall, our results illustrated the heterogeneity of national clinical practices in: laboratory parameters’ choice; cutoff values defining anemia and/or ID; parameter-based therapeutic decisions. Nonetheless, it was shown clear that patient’s individual characteristics, clinical settings, and the physician’s “clinical sense” seem to be considered to a further extent than the available guidelines. Future studies should be considered to develop recommendations that can be widely accepted.info:eu-repo/semantics/publishedVersio

Crescimento inicial de genótipos de mamoneira com sementes submetidas ao envelhecimento acelerado.

Made available in DSpace on 2011-04-09T13:56:09Z (GMT). No. of bitstreams: 1 1222008002rbof12269792008.pdf: 776020 bytes, checksum: dd411769b7d3cb9a78de3d341283e527 (MD5) Previous issue date: 2009-03-3

One-Particle Spectral Properties of Mott-Hubbard Insulators

We use an exact holon and spinon Landau-liquid functional which describes the holon - spinon interactions at all scattering orders, to study correlation functions of integrable multicomponent many-particle problems showing both linear and non-linear energy bands. We consider specific cases when the dominant non-linear band terms are quadratic and apply our results to the evaluation of the 1D Hubbard model correlation functions beyond conformal-field theory.Comment: 10 Pages, Revte

Validating silicon polytrodes with paired juxtacellular recordings: method and dataset

Cross-validating new methods for recording neural activity is necessary to accurately interpret and compare the signals they measure. Here we describe a procedure for precisely aligning two probes for in vivo “paired-recordings” such that the spiking activity of a single neuron is monitored with both a dense extracellular silicon polytrode and a juxtacellular micropipette. Our new method allows for efficient, reliable, and automated guidance of both probes to the same neural structure with micrometer resolution. We also describe a new dataset of paired-recordings, which is available online. We propose that our novel targeting system, and ever expanding cross-validation dataset, will be vital to the development of new algorithms for automatically detecting/sorting single-units, characterizing new electrode materials/designs, and resolving nagging questions regarding the origin and nature of extracellular neural signals