California's Safe Routes to School Program: Impacts on Walking,Bicycling, and Pedestrian Safety

This article evaluates California's pioneering Safe Routes to School (SR2S) program, which funds traffic improvement projects designed to improve safety for children's walking and bicycling to school and to increase the number of children who do so. Through surveys of parents and observations of vehicle and pedestrian traffic before and after project construction, we examined the impacts of 10 traffic improvement projects funded through the SR2S program. We measured changes in perceived safety and in safety-related behaviors associated with children's trips to school, and examined changes in the number of children walking and bicycling following these improvements. Five of the 10 traffic improvement projects we evaluated showed evidence of a successful impact. The findings have implications for California's SR2S program and for similar initiatives throughout the country.     

Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CN(x)-multi-wall carbon nanotube hybrid materials

In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.     

Screening of Toxic Inorganic Arsenic Species in Garlic (Allium sativum L.)

It has been evidenced that arsenic in garlic is present in the most toxic inorganic species As(III) and As(V). A non-chromatographic speciation method has been developed for the screening of inorganic toxic species of As in garlic samples by hydride generation atomic fluorescence spectrometry. The determination of As(III) and As(V) was based on the different efficiencies of hydride generation with NaBH₄ with and without a previous reduction with ascorbic acid and KI using a system of two proportional equations corresponding to these two different measurement conditions. The extraction efficiency of total arsenic and the stability of As(III) and As(V) in different extraction media (sulphuric acid, perchloric acid, and methanol/water) were evaluated. Based on the extraction yield and the stability of extracted species, 1.0 mol L⁻¹ H₂SO₄ was selected as the best extracting solution for speciation analysis. The methodology developed allows us a limit of detection of 0.8 and 0.6 ng g⁻¹ for As(III) and As(V), respectively. The relative standard deviation values were 4% for As(III) and 7% for As(V). This method was applied to determine As(III), As(V), and total As in different Spanish garlic samples. The arsenic (III) content varied from 17.1 to 22.1 ng g⁻¹ and As(V) from 54.7 to 67.6 ng g⁻¹. The accuracy of the method was confirmed by the analysis of a certified reference material of tomato leaves treated in the same way as the garlic samples.     

Composition and oxidative stability of soybean oil in mixtures with jojoba oil

Improvement of the oxidative stability of soybean oil (SBO) by blending with jojoba oil (JO) was investigated. SBO in the presence of 5, 10, 15 and 20 wt‐% of JO was subjected to accelerated storage at 60 °C. Peroxide values (PV), anisidine values (AV), UV absorption characteristics (K₂₃₂ and K₂₇₀ values), and headspace volatiles were determined to monitor the oxidative stability of oil samples. JO was effective in reducing the formation of hydroperoxides and volatile compounds in SBO. The effect was remarkable in SBO/JO blends containing 15 and 20% JO, which showed significant reductions in PV, AV and volatile content with respect to pure SBO. The increased oxidative stability of SBO/JO blends could not be attributed to JO tocopherols, since the addition of JO to SBO significantly reduced the tocopherol content of SBO. Besides the tocopherol content and unsaturation degree of SBO and JO, the effect of the JO ester structure on the oxidative stability of the blends is discussed. The enhanced chemical and flavor stabilities of SBO/JO blends with respect to pure SBO may make a significant contribution to improve the shelf life of SBO by reducing the deterioration reactions related to lipid peroxidation.     

Application of a Mixed Optimization Strategy in the Design of a Pharmaceutical Solid Formulation at Laboratory Scale

The objective of this work was to develop an optimization strategy for the design of pharmaceutical formulations. The mixed strategy was used to optimize a dry powder blend containing 500 mg of alpha methyl dopa to be filled into hard gelatin capsules. The experimental plan consisted of assessing blend flow and dissolution rate using formulations manufactured at small laboratory scale, selecting the optimum formulation, and confirming the data. Two optimization techniques were used in the solid pharmaceutical product design: a genetic algorithm (GA) and a downhill simplex technique. The genetic algorithm used in this work was implemented in an interactive form. Data for each generation of formulations were introduced to the computer with the corresponding values of a fitness function, which was determined in experimental form for each individual formulation. The fitness function used to evaluate product performance (capsule) was defined in terms of the dissolution rate multiplied by a weight function that penalizes those formulations with flow index outside a predefined range. The formulation design contained variable concentrations and types of lubricants/glidants. There were 64 combinations of seven agents with discrete ranges of concentrations codified into a 16-bit chromosome. Crossing and mutation operations were implemented with relatively high probabilities, for generations with a relatively small number of individuals, due to the restrictions imposed by the experimental cost. The mixed formulation strategy based on genetic algorithms and downhill simplex was used to obtain sequentially improved formulations based on two desired targets: in vitro dissolution rate and flow properties. The basic downhill simplex method was used to obtain an optimal formulation on the regression response surface obtained from the genetic algorithm data. The results obtained in this work clearly illustrate the potential of the proposed mixed optimization strategy to obtain optimal formulations.     

Genetic and chemical assessment of Arbequina olive cultivar grown in Córdoba province,Argentina

BACKGROUND: Thirty‐eight accessions of olive (Olea europaea L.) originating from Córdoba province (Argentina) and preliminarily identified as belonging to the Arbequina variety were genotyped using AFLP (amplified fragment length polymorphism) DNA markers. Also, the oil chemical composition was studied during three consecutive crop years. The objectives of the work were (a) to investigate genetic intra‐cultivar diversity and (b) to evaluate the oil chemical composition and compare it with that of Arbequina oil produced in Spain. RESULTS: The 19 primer combinations employed to perform the AFLP analysis produced 98 polymorphic bands. A reduced genetic heterogeneity was obtained, confirming that (a) the selected accessions belong to the Arbequina variety and (b) the traditional vegetative propagation practice has caused low genetic erosion in this variety cultivated in Córdoba. The main features that characterise the Argentinian Arbequina oils studied are the lower content of oleic acid and higher levels of phenolics and high‐molecular‐weight volatile compounds compared with those found in Spanish Arbequina oils. CONCLUSION: In spite of the small proportion of intra‐cultivar variability, the Arbequina variety grown in Argentina produces oils with different chemical traits from those obtained in the original Spanish growing region. These differences can be attributed mainly to the particular environmental conditions of the olive‐growing areas in these countries. Copyright © 2008 Society of Chemical Industry     

Limit theorems for sequences of random trees

We consider a random tree and introduce a metric in the space of trees to define the “mean tree” as the tree minimizing the average distance to the random tree. When the resulting metric space is compact we have laws of large numbers and central limit theorems for sequence of independent identically distributed random trees. As application we propose tests to check if two samples of random trees have the same law.     

Oxidative stress in the hydrophilic medium of algae and invertebrates

The harmful effects of the reactive species may be due to the increase in their steady state concentration either by the enhancement of their production rates and/or the decrease of their consumption rate by antioxidant activity. The ascorbyl radical (A^• ) can be considered as a final product of radical oxidative transformations of ascorbate (AH^-). The ratio A^• content/AH^- content (A^• /AH^-) has been widely used as an interesting tool to estimate mild to moderate oxidative transformations, providing a quick and simple method of diagnosis of stress in the hydrophilic cellular medium. The aim of this work was to summarize studies on the cellular oxidative condition in algae and invertebrates by assessing the A^• /AH^- ratio under environmentally changing conditions. The use of indices of oxidative stress increasingly sensitive and, somewhat more specific, can bring a new light to the still unknown world of oxidative responses in marine organisms     

Using Rasch measurement to investigate the cross-form equivalence and clinical utility of Spanish and English versions of a diabetes questionnaire: a pilot study

The purpose of this research was to use Rasch measurement to study the psychometric properties of data obtained from a newly developed Diabetes Questionnaire designed to measure diabetes knowledge, attitudes, and self-care. Specifically, a methodology using principles of Rasch measurement for investigating the cross-form equivalence of English and Spanish versions of the Diabetes Questionnaire was employed. A total of fifty diabetes patients responded to the questionnaire, with 26 participants completing the English version. Analyses detected problems with the attitude items. We attributed the scaling problems to the use of negatively worded items with participants having generally low educational backgrounds. Analysis of the knowledge and self-care items yielded unidimensional variables with clinically meaningful item hierarchies that may have relevance to treatment protocols. Furthermore, the knowledge and the self-care items from the two versions of the Diabetes Questionnaire met our criteria for establishing cross-form equivalence and thus allow quantitative comparisons of person measures across versions. Limitations of the study and suggested refinements of the Diabetes Questionnaire are discussed.