Crowdsourced integrity verification of election results

In this work, we describe an experiment for evaluating the integrity of election results, and improving transparency and voter participation in electronic elections. The idea was based on two aspects: distributed collection of poll tape pictures, taken by voters using mobile devices; and crowdsourced comparison of these pictures with the partial electronic results published by the electoral authority. The solution allowed voters to verify if results were correctly transmitted to the central tabulator without manipulation, with granularity of individual polling places. We present results, discuss limitations of the approach and future perspectives, considering the context of the previous Brazilian presidential elections of 2014, where the proposed solution was employed for the first time. In particular, with the aid of our project, voters were able to verify 1.6 % of the total poll tapes, amounting to 4.1 % of the total votes, which prompted the electoral authority to announce improved support for automated verification in the next elections. While the case study relies on the typical workflow of a paperless DRE-based election, the approach can be improved and adapted to other types of voting technology.     

OSNR model to consider physical layer impairments in transparent optical networks

We propose a model that considers several physical impairments in all-optical networks based on optical signal-to-noise degradation. Our model considers the gain saturation effect and amplified spontaneous emission depletion in optical amplifiers, coherent crosstalk in optical switches, and four-wave mixing in transmission fibers. We apply our model to investigate the impact of different physical impairments on the performance of all-optical networks. The simulation results show the impact of each impairment on network performance in terms of blocking probability as a function of device parameters. We also apply the model as a metric for impairment-constraint routing in all-optical networks. We show that our proposed routing and wavelength assignment algorithm outperforms two common approaches.

Peroxidase activity of the hemeoctapeptide N-acetylmicroperoxidase-8

The pH dependence of the peroxidase activity (guaiacol assay) of the ferric hemeoctapeptide N-acetylmicroperoxidase-8 (N-AcMP8) was studied under conditions where formation of the Compound I analogue of the peroxidase enzymes is rate limiting. The pH profile of the reaction rate is consistent with a mechanism where both H2O2 and HO2- can displace H2O coordinated trans to neutral His but where the hydroxo complex of the hemepeptide (OH- trans to His) is kinetically inert. At pH > 11, where the proximal His ligand of Fe(III) ionizes to form a histidinate, the hydroxo complex (OH- trans to His-) becomes kinetically labile. A comparison of DeltaH(double dagger) and DeltaS(double dagger) values for the reaction of H2O2 and HO2-, obtained from the temperature dependence of the rate constants, with values for CN- and cysteine reported previously, shows that the activation parameters depend on the identity of the incoming ligand. This suggests that ligand substitution at Fe(III) in N-AcMP8 proceeds through an interchange mechanism.     

Novel strategies for sparse regenerator placement in translucent optical networks

In this paper, we propose two strategies for sparse regenerator placement (RP) in translucent optical networks, named most used regenerator placement (MU-RP), and most simultaneous used regenerator placement (MSU-RP). Our proposals are compared to well known RP algorithms presented in literature for two different network topologies for different network loads, distribution of load along the networks and number of translucent nodes. MSU-RP presented remarkable results and outperformed all previous approaches in all cases, while MSU-RP obtained a slightly superior or similar performance when compared to previous approaches presented in the literature.     

Landsat-5 Thematic Mapper reflective-band radiometric stability

Four aspects of the radiometry of the Landsat-5 Thematic Mapper were characterized over the 20+ year mission lifetime for the six reflective bands: relative gain (the radiometric gain of each detector within a band relative to other detectors in that band), bias, performance of the Internal Calibrator (IC) system, and noise. Relative gain was found to be stable or slowly varying and could be described as a linear function of time for most detectors; the maximum change was approximately 0.5%/year. These relative gain characterizations provide an alternate source of destriping information that, in general, compares favorably with that obtained from currently used scene-specific methods. Much of the variability in instrument bias levels was found to be related to temperature effects; long-term changes in bias levels were less than 0.5 DN overall. The lamp-based IC system, though stable over the short term, showed both individual lamp phenomena and changes in overall behavior that complicated the ability to monitor the system's stability. Using the best behaved lamp and some assumptions about expected lamp behavior, characterization of response with a simple model was achieved through the year 2000. The model shows an initial 5% to 10% decay in response over the first three years of operation, depending on the band. Noise levels and signal-to-noise ratio in the instrument appear to be stable throughout the lifetime.     

Insights into porphyrin chemistry provided by the microperoxidases, the haempeptides derived from cytochrome c

The water-soluble haem-containing peptides obtained by proteolytic digestion of cytochrome c, the microperoxidases, have been used to explore aspects of the chemistry of iron porphyrins, and as mimics for some reactions catalysed by the haemoproteins, including the reactions catalysed by the peroxidases and the cytochromes P450. The preparation of the microperoxidases, their physical and chemical properties including their electronic structure, the kinetics and thermodynamics of their reactions with ligands, electrochemical studies and examples of their uses as haemoproteins mimics, is reviewed.     

Validation of an LC method to determine skin retention profile of genistein from nanoemulsions incorporated in hydrogels

Recent studies have shown the effect of soy isoflavones in preventing skin photoaging and photocarcinogenesis, especially for genistein (GEN). Nanoemulsions have been proposed as a delivery system for GEN administration due to the low water solubility of this isoflavone. This article describes the validation of an isocratic liquid chromatography method to determine GEN in porcine ear skin layers from nanoemulsions before and after incorporation into hydrogels. The analyses are performed on a reversed-phase C18 column using a mobile phase composed of methanol-water (70:30, v/v) under acid conditions (at pH 3.0) and UV detection at 270 nm. The method is linear in the range of 0.1-10 μg/mL (r(2) > 0.999) in the presence of skin extracts. The low limit of quantitation is estimated as 0.1 μg/mL. No interferences from formulation excipients or skin layer compounds are detected. The RSD values for intra- and inter-day precision are lower than 15%. Recovery ranged from approximately 90% to 110%. The method is applied to estimate GEN retention in the skin from formulations using Franz diffusion cells. The highest amount of GEN is detected in the epidermis (185 μg/cm(2)). In conclusion, the method proved to be specific, precise, and accurate in determining GEN amounts from formulations in skin retention studies.     

Landsat-4/5 Band 6 relative radiometry

Relative radiometric responses for the thematic mapper (TM) band 6 data from Landsat-4 and Landsat-5 were analyzed, and an algorithm has been developed that significantly reduces the striping in Band 6 images due to detector mismatch. The TM internal calibration system as originally designed includes a DC restore circuit, which acts as a feedback system designed to keep detector bias at a constant value. There is a strong indication that the DC restore circuitry implemented in Band 6 does not function as it had been designed to. It operates as designed only during a portion of the calibration interval and not at all during acquisition of scene data. This renders the data acquired during the calibration shutter interval period virtually useless for correction of the individual responses of the four detectors in Band 6. It was observed and statistically quantified that the relative response of each of the detectors to the band average is stable over the dynamic range and throughout the lifetime of the instrument. This allows an alternate approach to relative radiometric correction of TM Band 6 images     

Assessment of novel regenerator assignment strategies in dynamic translucent elastic optical networks

Photonic Network Communications - The problem of regenerator assignment (RA) in translucent optical networks consists in segmenting a lightpath into several transparent segments, each of...     

Heme-Peptide Models for Hemoproteins. 1. Solution Chemistry of N-Acetylmicroperoxidase-8

An improved method for the preparation of the heme octapeptide acetyl-MP8, obtained by proteolysis of horse heart cytochrome c, is described. AcMP8 obeys Beer's law at pH 7.0 in aqueous solution up to a concentration of 3 x 10(-)(5) M. The self-association constant measured at 25 degrees C (log K(D) = 4.04) is an order of magnitude lower than that for MP8, reflecting the role of the N-acetyl protecting group in abolishing intermolecular coordination. However, AcMP8 does form pi-stacked dimers in aqueous solution with increasing ionic strength. A more weakly packed pi-pi dimer reaches a maximum abundance at approximately 3 M ionic strength, but a more tightly packed dimer is favored at &mgr; > 3 M. An equilibrium model based on charge neutralization by specific binding of Na(+) ions gives a total molecular charge of 3- for AcMP8 at pH 7.0 and a self-association constant log K(D) = 4.20. AcMP8 exhibits six spectroscopically active pH-dependent transitions. The Glu-21 c-terminal carboxylate binds to the heme iron at low pH (pK(a) = 2.1) but is substituted by His-18 (pK(a) = 3.12) as the pH increases. The two heme propanoic acid substituents ionize with pK(a)'s of 4.95 and 6.1. This is followed by ionization of iron-bound water with a pK(a) = 9.59, DeltaH = 48 +/- 1 kJ mol(-)(1), and DeltaS = -22 +/- 3 J K(-)(1) mol(-)(1). The electronic spectra indicate that AcMP8 is predominantly in the S = (5)/(2) state at pH 7.0, while the hydroxo complex at pH 10.5 corresponds to an equilibrium mixture of S = (5)/(2) and S = (1)/(2) states at 25 degrees C. In the final transition, His-18 ionizes to form the S = (1)/(2) histidinate complex with a pK(a) of 12.71. AcMP8 is relatively stable under alkaline conditions, dimerizing slowly at high pH (k = 2.59 +/- 0.14 M(-)(1) s(-)(1)) to form a high-spin &mgr;-oxo-bridged species. The pH-dependent behavior of AcMP8 in the presence of excess 3-cyanopyridine, however, is markedly different. At low pH, AcMP8 simultaneously binds the exogenous ligand and the Glu-21 c-terminal carboxylate with a pK(a) < 2. His-18 replaces the carboxylate ligand at higher pH (pK(a) = 2.60), and both heme propanoic acid groups ionize with a mean pK(a) = 5.10. Unlike AcMP8.OH(-), the axial histidine of the 3-CNPy complex ionizes at near neutral pH (pK(a) = 7.83), prior to being replaced by OH(-) (pK(a) = 10.13). The sixth transition in the AcMP8/3-CNPy system produces the bis(hydroxo) complex (pK(a) > 13).