The adaptation and validation of the food security scale in a community of Caracas, Venezuela

This paper describes the process of modifying and validating a hunger index developed in the United States by Wehler et al (1992). It is part of a research whose main objective is to develop and validate a simple method that measures both quantitative (food sufficiency) and qualitative (female self-perception) dimensions of household food insecurity. In a pilot study, the original instrument was modified from a 2 point 8 item to a 4 point 12 item scale. Precision measured with Alpha Chronbach's coefficient was high (0.871) suggesting consistency in the scale's items. The instrument was applied to a sample of 238 poor and very poor households in a peri-urban barrio of Caracas. To determine overall internal validity of the scale the relationship between possible economic, social and behavioral determinants and food security level measured with the scale, was analyzed. Construct validity of the scale was established with factor and principal components analysis. Finally, with multiple regression analysis evidence is presented for overall validity of the scale. Four determinants: predictors of food sufficiency score, monthly income per capita, social class, and number of children in the household predict in the expected direction self-perceived food security level (R2 = 0.343). Results suggest that this instrument, together with an abbreviated measure of food sufficiency, based on strategic foods may be a valid, precise, and simple method for identifying and monitoring households that suffer from some degree of food insecurity in poor urban communities.     

Comparative proximal and mineral analysis of iguana,poultry and beef meats

Raw meat samples from iguana, poultry and beef cattle specimens were used to compare proximal (g/100 g) and mineral (mg/100 g) composition. Iguana meat was obtained by dissecting whole specimens (Iguana iguana) captured at a ranch (n = 20). Thighs and breasts were separated from broiler (either chilled or frozen) carcasses (n = 20), and deboned to represent chicken meat samples, whereas 2.5-cm-thick longissimus (ribeyes) steaks were removed from carcasses and frozen to represent beef of several breed types (n = 20). The one-way analysis of variance performed by the least squares method (LS Means) showed specie affected significantly (p > 0.05) all composition variables under study. Moisture content did not differ between iguana and chicken meats (74.7 y 74.9%, respectively) whereas beef samples had the lowest water content (73%) (p < 0.01). LS means for protein content showed beef samples (22.3%) were highest (p < 0.05) in this nutrient, iguana meat being intermediate (20.8%). Chicken meat presented the highest amount of total lipids (7.75 +/- 0.20 g/100 g) (p < 0.01) followed by iguana (3.49 +/- 0.12 g/100 g) and beef (2.57 +/- 0.20 g/100 g). Ash and most individual minerals were more concentrated in iguana meat, except for K and Zn that were more abundant in beef samples. Non-significant differences in Mg, Na, Cu or Mn contents were detected between chicken and beef samples. It was concluded that iguana meat could be an alternate source of protein and minerals as compared to those of traditional meat species.     

High-pressure pulse radiolysis as a tool in the study of transition metal reaction mechanisms

The unique combination of high-pressure and pulse radiolysis kinetic techniques enables detailed mechanistic insight for a large variety of chemical processes to be gained. Typical examples for transition metal reactions are presented. These include ligand substitution, electron transfer, reactions of complexes with uncommon oxidation states, and reactions with radicals, including the formation and decomposition reactions of complexes with metal-carbon sigma bonds. The volumes of activation and volume profiles obtained form the basis of a critical analysis of different plausible reaction mechanisms.     

Blood speed imaging with an intraluminal array

In applications in which Doppler processing is not possible, such as side-looking intravascular imaging systems, decorrelation methods can be used to estimate blood speed. Here, a method is presented measuring relative blood speed using an FIR filter bank to estimate temporal decorrelation rates. It can be implemented in a modern commercially available ultrasound imaging system with no additional hardware. Both simulations and experiments using an intraluminal scanner appropriate for coronary artery applications have tested the system. In this study, the FIR filter bank is contrasted with previous methods, and its utility is further demonstrated with real-time color flow images from a pig model.     

An integrated 16/spl times/16 PVDF pyroelectric sensor array

This paper presents a fully integrated PVDF-on-silicon pyroelectric sensor array. The pyroelectric sensor has two main features: a subpixel low noise charge amplifier and a self-absorbing layered structure. The integrated low noise charge amplifier is implemented in a standard CMOS process technology. It is located directly under the sensing structure, maximizing the pixel fill factor. The self-absorbing pyroelectric sensor is a three-layer stack, consisting of a conductive polymer as an absorber layer and front electrode, a thin PVDF film as the pyroelectric material, and a rear metal layer acting as a reflector layer and rear electrode. The manufacture of the pyroelectric sensor array requires five maskless post-CMOS processing steps and is compatible with any n-well, double metal, double polysilicon, CMOS process. The array has an average pixel voltage sensitivity of 2200 V/W at 100 Hz, an NEP of 2.4/spl times/10/sup -11/ W//spl radic/Hz at 100 Hz, and a specific detectivity of 4.4/spl times/10/sup 8/ cm /spl radic/Hz/W at 100 Hz.     

Carbon fiber post adhesion to resin luting cement in the restoration of endodontically treated teeth

Carbon fiber posts (CFP) are widely used in the restoration of endodontically treated teeth to enhance the mechanical behavior in spite of metallic posts and to prevent vertical fractures of the tooth under chewing loads. The post is cemented inside the canal lumen using polymer resins with Young's modulus lower than Dentine. In this conditions the stress concentration is located at the post-cement interface and in the cement bulk itself, preserving radicular Dentine from dangerous stress accumulation. The mechanical resistance of CFP posts cemented in human Dentine was evaluated by the means of mechanical pull-out tests assisted by the finite element analysis. The average bond strength and the critical stress values of the CHP-cement interface were 25 MPa and 50 MPa respectively. ©2000 Kluwer Academic Publishers     

Quantification of polycyclic aromatic hydrocarbons in the NIST standard reference material (SRM1649A) urban dust using thermal desorption GC/MS

A thermal desorption GC/MS technique has been developed for the quantification of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter using the NIST Standard Reference Material (SRM1649a) Urban Dust. The technique was developed using standard linearity tests in order to establish optimum sample weights and optimum desorption and chromatographic parameters. This direct analysis technique eliminates the use of solvents in the sample preparation (reducing volatile component losses) and also significantly reduces the sample preparation time (no extraction procedure). The technique has been shown to give linearity in terms of the overall TIC response as well as for a prominent series of n-alkanes (C20-C33) and 10 NIST priority PAHs, 8 of which have been quantified. The technique is reported to be uniquely sensitive (PAH concentrations 2-6 mg kg(-1)) and reproducible (MW = 178-228 SD < or =0.228 mg kg(-1), < or =7%; MW = 252 SD < or =0.922 mg kg(-1), < or =33%) over the range of sample weights (1-5 mg). Such sample weights illustrate that the technique can be equally applied to the analysis of airborne particulate samples collected over short time periods (24-48 h) using only commonly used low-volume collection devices.     

Temperature sensitivity of passive holographic wavelength-division multiplexers-demultiplexers

We derive a set of concise formulas to characterize the temperature sensitivity of holographic wavelength-division multiplexers-demultiplexers (H-MUX's-H-DMUX's). The normalized parameters such as dispersion abilities, central wavelength shift rate, and variations of insertion loss hold for general grating-based wavelength-division multiplexing-demultiplexing (WDM-WDDM) structures. The results are applicable to both wide-WDM-WDDM and dense ones working in 800-, 1300-, and 1550-nm optical wavelength windows, regardless of whether their input-output ports are single-mode or multimode fibers. Detailed analysis and experiments are carried out on a fully packaged four-channel H-MUX-H-DMUX. The experimental results at temperatures from 25 to 80 degrees C fit nicely with the theoretical prediction. We conclude that passive grating-based H-MUX's-H-DMUX's are promising for meeting the requirements on temperature sensitivity in optical data communications and telecommunications. Most of the analysis can be applied to other types of Bragg-grating-based WDM-WDDM.     

Fabrication of thin-film micropolarizer arrays for visible imaging polarimetry

We describe a microfabrication process for fabricating micropolarizer devices with polarization thin film. The polarization film is less than a 0.5 mum thick and can have a polarization extinction ratio of ~330 in the visible wavelength range. A single-state micropolarizer array with polarizing pixels as small as 5 mum x 5 mum has been fabricated. A multilayer spatially multiplexed three-state micropolarizer line array with a 14.4-mum resolution has also been fabricated for visible imaging polarimetry application.     

Superresolution of binary images with a nonlinear interpolative neural network

Superresolution is the process by which the bandwidth of a diffraction-limited spectrum is extended beyond the optical passband. Many algorithms exist that are capable of superresolution; however, most are iterative methods, which are ill suited for real-time operation. One approach that has been virtually ignored is the neural-network approach. We consider the feedforward architecture known as a multilayer perceptron and present results on simulated binary images blurred by a diffraction-limited, circular-aperture optical transfer function and sampled at the Nyquist rate. To avoid aliasing, the network performs as a nonlinear spatial interpolator while simultaneously extrapolating in the frequency domain.