A multispectral imaging technique to determine concentration profiles of myoglobin derivatives during meat oxygenation

We have designed a multispectral imaging acquisition system to measure the relative concentration values of myoglobin forms inside meat during oxygenation. Images at 474, 525, 572 and 610 nm are used to compute the concentration of reduced myoglobin, oxymyoglobin and metmyoglobin with a spatial resolution of 0.0125 mm/pixel. From these images, pigment concentration profiles as a function of oxygenation time and depth beneath the surface were obtained. A model describing the diffusion of oxygen and the consumption of reduced myoglobin is numerically tested versus the measured concentration profiles. The model accurately fits the data with a Mean Root Squared Error equal to 0.253%. Precise definitions for position and width of pigment layers based in concentration profiles are given. The results suggest that multispectral imaging techniques combined with precise control and measurement of sample temperature and oxygen partial pressure will permit detailed studies of the myoglobin chemistry during oxygenation.     

Power‐efficient analog design based on the class AB super source follower

A class AB version of the conventional super source follower (SSF) is described. The circuit greatly increases slew rate (SR) and current efficiency, maintaining the low distortion and low output resistance of the SSF. Class AB operation is achieved without extra power dissipation or supply requirements, and without bandwidth or noise degradation. The circuit can advantageously replace the SSF in a wide variety of analog systems, opening a new research line in analog design. To illustrate the widespread application of this cell, a class AB differential unity‐gain buffer, a class AB differential current mirror and two class AB differential transconductors are designed, fabricated in a 0.5µm CMOS technology and tested. Measurement results using a dual supply of ±1.65V show that the proposed class AB version of the SSF improves SR by a factor 21.5 and increases bandwidth by 10%, keeping noise level, input range, power consumption, and supply requirements unaltered. The fabricated class AB current mirror features a THD at 100 kHz of ? 62dB for signal currents 20 times larger than the bias current. The fabricated transconductors feature an IM3 at 1 MHz of ? 56.6dB for output currents more than 13 times larger than the bias currents. Copyright © 2011 John Wiley & Sons, Ltd.     

Interface between transparent isotropic and uniaxial absorbing dielectric media: equations for ray tracing and for the direction of propagation

In this work we analyze the propagation of a plane wave that passes from an isotropic transparent medium to a uniaxial absorbing medium. Detailed expressions that give the real directions of propagation of the wave and the energy of the reflected and refracted ordinary and extraordinary waves are obtained. These expressions are valid for every orientation of the optic axis of the uniaxial medium and for every direction of propagation of the incident wave. Expressions are tested in the case of an interface between a transparent and an absorbing isotropic media and for the air-rutile (TiO2) interface. The effect of absorption has been evaluated by comparing the results obtained in rutile with the results obtained in a transparent uniaxial medium with the same real refractive indices. Results are presented for different values of the angle of incidence and the orientation of the plane of incidence.     

Spatiotemporal methods for analysis of urban system dynamics: an application to Chile

This paper presents a methodological procedure to evaluate the influence of spatial proximity on evolution of cities to detect regional differences in their spatiotemporal dynamics. The six-step method based on a set of statistical methods can be computed with a new R package: estdaR. The first step consists of the usual characterization of the cross-sectional distribution of the urban areas by means of nonparametric estimations of density functions for a set of significant years. In the second and third steps, the growth process is modeled as a first-order stationary Markov chain to evaluate the effect of global and local spatial autocorrelation on the transition probabilities with a set of indices based on the spatial version of the standard Markov chain. The fourth, fifth, and sixth steps perform in-depth analysis to detect the existence and interaction of spatial regimes in the movement direction and ranking mobility of urban distribution. We apply this novel strategy for the period 1930–2002 to analyze the entire Chilean urban system—not only the Central Zone, in which most of the population and economic activities are concentrated, but also other urban zones in the country.     

Identifying local determinants of destination choices of international immigrants to the Madrid metropolitan area

We examine the local determinants of destination choices of foreign immigrants to the Madrid metro area using data for 2005 and 2009 from the Spanish annual municipal‐level registers of inhabitants. Taking advantage of the equivalence relation between conditional logit and Poisson, we estimate a location‐choice model using the Poisson fixed‐effects estimator. Origin‐destination fixed effects are incorporated to account for the persistent spatial structure of the immigrants' settlement patterns and to control for potential violations of the independence of irrelevant alternatives (IIA) assumption. The Poisson regression model is estimated for seven different groups of immigrants according to world regions or countries of origin. Our modelling strategy has important empirical implications, with magnitudes and/or signs of the estimated coefficients changing in the expected directions. It is found that newly arriving immigrants tend to settle in low‐to‐middle‐income locations in the suburban reaches of the Madrid metro area. Moreover, the effects of the size of local communities of established immigrants are found to be insignificant and even negative in several instances, reflecting hetero‐local settlement preferences and/or the saturation of local networks causing in‐group job rivalry, respectively.     

汽车设计面临测量的挑战

新测试设备可地协助汽车技术人员测试和诊断复杂的汽车电子电路。电子机械系统、子系统和零件复杂性的增加向汽车维修技术人员提出严重的挑战。因为今日的汽车的电子部分与机械部分一样复杂,这要求技术人员必须能够快速准确地进行故障寻迹与排除,识别出并解决电子电路问题。要帮助这些技术人员解决困难的电子和电子机械问题,就必须给他们更灵巧的测试设备。     

High open circuit voltage in efficient thiophene-based small molecule solution processed organic solar cells

We have synthesized and fully characterized an oligothiophene small organic molecule for its use as electron donor moiety in solution processed bulk-heterojunction organic solar cells. Our results show that device solvent annealing process of the conjugated oligothiophene molecule leads to a light-to-energy conversion efficiency of 3.75% under standard illumination conditions. The solar cell presents open-circuit voltage and fill factors as high as 1.01 V and 63.05% respectively, which are among the highest values obtained for small molecule solution processed organic solar cells.     

Measurement of the colour of white and rosé wines in visual tasting conditions

We have designed a colour measurement method that reproduces the conditions found during visual colour assessment of wines. In particular the illumination, background, wine sampler and the relative positions of sampler, illumination and observer have been controlled. Using this method, the colour of 33 white wines and 33 rosé wines was measured and expressed in terms of the CIELAB colour coordinates. Colour of wine samples was also assessed by expert wine tasters. White wines were classified into three colour categories: Straw-yellow, Yellow-gold and Yellow-green. Rosé wines were classified into four colour categories: Raspberry, Strawberry, Redcurrant and Salmon. The performance of CIELAB colour coordinates to reproduce the observed classification has been established using discriminant analysis. The central region of the wine surface gives the best results having lower measurement errors and higher classification performance. For white wines a*, b* and h _ab are the relevant colour coordinates scoring 84.8% of correctly classified samples. In rosé wines L*, a* and h _ab in the central region correctly classify 100% of the samples. This study demonstrates that colour of white and rosé wines can be measured in the same conditions that are found in the visual colour assessment when precise information on the visual colour appearance of wines is required.     

Color removal in groundwater through the enhanced softening process

The source of water for Miami-Dade County, Florida is groundwater derived from the Biscayne aquifer. The raw water is rich in natural organic material producing correspondingly high color levels. Currently, breakpoint chlorination is used at the water treatment plant to control the color problem. However, this results in the formation of disinfection by-products. Proposed alternatives to reduce color and avoid by-product formation include the addition of coagulants such as ferric chloride and organic polymers, and the operation of the existing lime softening process at a higher pH. This study uses jar tests to evaluate the relative effectiveness of the proposed alternatives. Results indicate that significant color reduction is achieved using the existing lime softening process with activated silica coagulant by increasing the softening pH to 11 or more. Elevated pH also produced a > 30% reduction in total organic carbon. In the presence of higher raw water color (> or = 80 units), the addition of ferric chloride as coagulant at dosages of 80 mg/L is recommended.