Analog circuits optimization based on evolutionary computation techniques

This paper presents a new design automation tool, based on a modified genetic algorithm kernel, in order to improve efficiency on the analog IC design cycle. The proposed approach combines a robust optimization with corner analysis, machine learning techniques and distributed processing capability able to deal with multi-objective and constrained optimization problems. The resulting optimization tool and the improvement in design productivity is demonstrated for the design of CMOS operational amplifiers.     

Inhibition of α-amylase activity by condensed tannins

The ability of grape seed procyanidins to inhibit α-amylase activity was studied using a colorimetric method. This ability was found to be related with the average degree of polymerisation of the tested procyanidins. These interactions were further evaluated by fluorescence quenching, dynamic light scattering (DLS) and nephelometry, in order to understand the mechanisms by which they occur. A relationship between aggregate formation and enzymatic inhibition was observed. The interaction between procyanidins and enzyme involves a specific interaction as inferred from the calculated apparent bimolecular quenching constant in the fluorescence assays. Further experiments involved the determination of the effect of carbohydrates on the enzymatic inhibition observed. It was shown that pectin and arabic gum inhibited the formation of insoluble aggregates but were unable to restore fluorescence and activity to the enzyme. This suggests that these carbohydrates resulted in a decrease in turbidity due to the formation of a ternary complex with protein/polyphenol.     

Influence of anthocyanins and derivative pigments from blueberry (Vaccinium myrtillus) extracts on MPP intestinal uptake: A structure–activity approach

The aim of the present study was to investigate the influence of an anthocyanin extract (extract I), and two other derivative extracts (extracts II and III), which are being developed aiming to be further applied in the food industry, on intestinal uptake of organic cations. For this purpose, the effect of these compounds on ³H-MPP⁺ uptake was evaluated in Caco-2 cells (an enterocyte-like cell line derived from a human colonic adenocarcinoma).     

Thermal Characterization of Polyhydroxyalkanoates and Poly(lactic acid) Blends Obtained by Injection Molding

In this work we present the thermal characterization of the full scope of polyhydroxyalcanoate and poly(lactic acid) blends obtain by injection molding. Blends of polyhydroxyalcanoate and poly(lactic acid) (PHA/PLA) were prepared in different compositions ranging from 0–100% in steps of 10%. The blends were injection molded and then characterized by differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). The increment of PHA fraction increased the degree of crystallinity of the blend and the miscibility of the base polymers as verified by the Fox model. The WAXD analysis indicates that the presence of PHA hindered the PLA crystallization. The crystallization evolution trough PHA weight fraction (wf) shows a phase inversion around 50-60%. SEM analyses confirmed that the miscibility of PHA/PLA blends increased with the incorporation of PHA and became total for values of PHA higher that 50%.     

Mobility of Pb in salt marshes recorded by total content and stable isotopic signature

Total lead and its stable isotopes were analysed in sediment cores, leaves, stem and roots of Sacorconia fruticosa and Spartina maritima sampled from Tagus (contaminated site) and Guadiana (low anthropogenic pressure) salt marshes. Lead concentration in vegetated sediments from the Tagus marsh largely exceeded the levels in non-vegetated sediments. Depth profiles of (206)Pb/(207)Pb and (206)Pb/(208)Pb showed a decrease towards the surface ((206)Pb/(207)Pb=1.160-1.167) as a result of a higher proportion of pollutant Pb components. In contrast, sediments from Guadiana marsh exhibited low Pb concentrations and an uniform isotopic signature ((206)Pb/(207)Pb=1.172+/-0.003) with depth. This suggests a homogeneous mixing of mine-derived particles and pre-industrial sediments with minor inputs of anthropogenic Pb. Lead concentrations in roots of plants from the two marshes were higher than in leaves and stems, indicating limited transfer of Pb to aerial parts. A similar Pb isotopic signature was found in roots and in vegetated sediments, indicating that Pb uptake by plants reflects the input in sediments as determined by a significant anthropogenic contribution of Pb at Tagus and by mineralogical Pb phases at Guadiana. The accumulation in roots from Tagus marsh (max. 2870 microg g(-1) in S. fruticosa and max. 1755 microg g(-1) in S. maritima) clearly points to the dominant role of belowground biomass in the cycling of anthropogenic Pb. The fraction of anthropogenic Pb in belowground biomass was estimated based on the signature of anthropogenic Pb components in sediments ((206)Pb/(207)Pb=1.154). Since no differences exist between Pb signature in roots and upper sediments, the background and anthropogenic levels of Pb in roots were estimated. Interestingly, both background and anthropogenic Pb in roots exhibited a maximum at the same depth, although the proportion of anthropogenic Pb was relatively constant with depth (83+/-4% for S. fruticosa and 74+/-8% for S. maritima).     

A new vinylpyranoanthocyanin pigment occurring in aged red wine

A new pyranoanthocyanin–vinylphenol pigment was detected in an aged Port red wine. The UV–Vis spectrum of this pigment was found to have a λ_max of 538 nm that is bathochromically shifted from that of original anthocyanins, exhibiting a more purple hue in acidic solution. This newly formed pigment was synthesized in model solution through the reaction between malvidin 3-O-glucoside–pyruvic acid adduct and vinylphenol and its structure was assigned by NMR and mass spectrometry. This pigment is reported herein for the first time.     

Generalized Stauffer�CGrimson background subtraction for dynamic scenes

We propose an adaptive model for backgrounds containing significant stochastic motion (e.g. water). The new model is based on a generalization of the Stauffer–Grimson background model, where each mixture component is modeled as a dynamic texture. We derive an online K-means algorithm for updating the parameters using a set of sufficient statistics of the model. Finally, we report on experimental results, which show that the proposed background model both quantitatively and qualitatively outperforms state-of-the-art methods in scenes containing significant background motions.     

Chemical composition and nutritional value of raw and fried allis shad (Alosa alosa)

The main objective of this study was to compare the proximate chemical composition and fatty acid profile of migrating allis shad (MS) and resident allis shad (RS) and to evaluate the nutritional value of fried migrating allis shad. No significant differences in the proximate chemical composition between males and females of each stock were obtained. However, MS fish had a significantly higher fat content than RS fish. The monounsaturated fatty acids group was the dominant in MS fish and oleic acid presented the highest percentage. Docosahexaenoic acid followed by eicosapentaenoic acid were the main PUFA in fish from both stocks. However, RS fish had higher total ω6 than MS fish due to its higher percentage of linoleic acid and arachidonic acid. Frying resulted in a significant reduction in water content and affected significantly the proximate chemical composition and the fatty acid profile, particularly the palmitic, oleic and linoleic acid.     

Creep behavior of pultruded GFRP elements – Part 2: Analytical study

This paper presents an analytical study about the viscoelastic time-dependent (creep) behavior of pultruded GFRP elements made of polyester and E-glass fibers. Experimental results reported in Part 1 are firstly used for material characterization by means of empirical and phenomenological formulations – a good general agreement is obtained using the following analytical models: (i) Findley’s power law, (ii) Bruger–Kelvin model and (iii) Prony–Dirichlet series. Based on accelerated characterization methodology – Time-Stress Superposition Principle (TSSP) coupled with Findley’s law, for a reference stress of 20% of the material ultimate stress, an elastic deformation increase of 30% is obtained after 50,000 h. The creep parameters and deformation estimated by using the Findley’s model derivations indicate a consistent prediction of time-dependent deformation and viscoelastic properties of the two types of elements analysed – laminates and beam. A straightforward formulation to predict the time-dependent elastic modulus is applied, showing that the flexural stiffness should be reduced by 25% of its initial value after 1-year and as much as 50% after 50-years. Similarly, the power law coupled to Euler’s classical beam theory suggests a reasonable adaptability to the creep phenomenon in the linear regime and proved to provide accurate predictions for deflections under flexural loading up to 40% of the ultimate strength. After 50 years, under normal service load level (1/3 of the failure load), the total creep deflection will attain almost twice the initial deflection. If taking into account the shear deformation (Timoshenko’s postulated) of the full-size element with “effective” stiffness properties such estimate is reduced nearly 25%.     

Nexus 2010: Relationships between Architecture and Mathematics

The eighth edition of the international, interdisciplinary Nexus conference on architecture and mathematics took place from Sunday 13 June through Tuesday 15 June 2010, in Porto, Portugal.