Modeling crash outcome probabilities at rural intersections: application of hierarchical binomial logistic models

It is important to examine the nature of the relationships between roadway, environmental, and traffic factors and motor vehicle crashes, with the aim to improve the collective understanding of causal mechanisms involved in crashes and to better predict their occurrence. Statistical models of motor vehicle crashes are one path of inquiry often used to gain these initial insights. Recent efforts have focused on the estimation of negative binomial and Poisson regression models (and related deviants) due to their relatively good fit to crash data. Of course analysts constantly seek methods that offer greater consistency with the data generating mechanism (motor vehicle crashes in this case), provide better statistical fit, and provide insight into data structure that was previously unavailable. One such opportunity exists with some types of crash data, in particular crash-level data that are collected across roadway segments, intersections, etc. It is argued in this paper that some crash data possess hierarchical structure that has not routinely been exploited. This paper describes the application of binomial multilevel models of crash types using 548 motor vehicle crashes collected from 91 two-lane rural intersections in the state of Georgia. Crash prediction models are estimated for angle, rear-end, and sideswipe (both same direction and opposite direction) crashes. The contributions of the paper are the realization of hierarchical data structure and the application of a theoretically appealing and suitable analysis approach for multilevel data, yielding insights into intersection-related crashes by crash type.     

Further notes on the application of zero-inflated models in highway safety

The intent of this note is to succinctly articulate additional points that were not provided in the original paper (Lord et al., 2005) and to help clarify a collective reluctance to adopt zero-inflated (ZI) models for modeling highway safety data. A dialogue on this important issue, just one of many important safety modeling issues, is healthy discourse on the path towards improved safety modeling. This note first provides a summary of prior findings and conclusions of the original paper. It then presents two critical and relevant issues: the maximizing statistical fit fallacy and logic problems with the ZI model in highway safety modeling. Finally, we provide brief conclusions.     

Fine-tuning the fluorescent properties of Li and Na intercalated C60 with hydrogen

In this work we demonstrate how hydrogen can be utilized to fine tune the emission gap of C₆₀ through the formation of direct CH bonds in sodium and lithium intercalated systems (M₆C₆₀H_x). Upon hydrogenation, a shift in the emission spectrum to shorter wavelengths (higher energy) is observed relative to alkali metal free fulleranes (C₆₀H_x) and pure C₆₀. This is attributed to the higher degree of hydrogenation of C₆₀ that can be achieved upon intercalation with alkali metals which increases the sp³ hybridization of the system (decreases conjugation). Quantum yields of the sodium and lithium intercalated fulleranes are 1.3% and 1.8% respectively which are similar to those of alkali metal free fulleranes (1.4%). We also show that polymethyl methacrylate (PMMA) can be infused with the metal intercalated fulleranes to produce a fluorescent polymer with excellent transparency over the visible spectrum. This could potentially lead to further use of these materials in luminescent down shifting applications.     

Conservation of Bakery Products Through Cinnamaldehyde Antimicrobial Films

In this study, an antimicrobial film containing cinnamaldehyde was developed to pack bread and pastry made without preservatives. These products were wrapped with the antimicrobial films and packaged in low‐density polyethylene bags. The antimicrobial activity of the films, the migration of the cinnamaldehyde in the films to the products and product acceptance by consumers were evaluated. Samples of bread and pastry packaged with films without the antimicrobial were used as controls. When samples of bread packaged with the cinnamaldehyde films were analysed, the films were found to be effective in inhibiting the growth of aerobic mesophiles, yeast and mould. The control sample was observed to have twice as much growth (four log cycles) compared with the other treatments after 12 days of storage. After 60 days, the samples of pastry dough showed a reduction of two and three log cycles of growth for aerobic mesophiles and Staphylococcus spp. for the 5 and 10% films, respectively. However, the amounts of yeast and mould in samples packed in either 5 or 10% antimicrobial films did not increase over the storage period. In all evaluations, water activity did not influence the microbiological results. The content of cinnamaldehyde that migrated from the film (5%) to the pastry dough and bread were 0.005 g/g and 0.0025 g/g, respectively, after 3 days of storage at 23 ± 2 °C. This amount of the antimicrobial influenced the acceptance of the pastry dough compared with the control but did not influence the acceptance of the bread, possibly due to the smaller amount of cinnamaldehyde detected in samples of bread in relation to the samples of pastry dough. Copyright © 2013 John Wiley & Sons, Ltd.     

Can experimental models of rodent implantation glioma be improved? A study of pure and mixed glioma cell line tumours

Phosphatidylcholine hydroperoxide (PC-OOH) and phosphatidylethanolamine hydroperoxide (PE-OOH) concentrations were determined in microsomes and plasma membranes prepared from 2- and 17-month-old male Sprague-Dawley rat hepatocytes, to verify the dissimilarity of age dependency of lipid peroxidation in organelle membranes. The hydroperoxides were directly measured by chemiluminescence detection-high-performance liquid chromatography (CL-HPLC), and 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl) phosphatidylcholine (PLPC-OOH) and 1-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl) phosphatidylethanolamine (PLPE-OOH) were enzymatically synthesized and utilized as standards for the calibration. Baseline concentrations of hydroperoxides (PC-OOH + PE-OOH) of the 17-month-old rats were 46 pmol per mg protein in microsomes (2.7 times higher than the 2-month-old rats) and 306 pmol per mg protein in plasma membranes (9.9 times higher than the 2-month-old rats). Both microsomal and plasma membrane lipids were severely peroxidized and converted to phospholipid hydroperoxides by NADPH-dependent lipid peroxidation in vitro, but the age-dependency was only observed in the plasma membranes. These results demonstrate that substantial oxidative damage to membrane phospholipids occurs with ageing both in microsomes and plasma membranes, but is more prevalent in plasma membranes in rat hepatocytes.     

Effect of alginate and alginate-cimetidine combination therapy on stimulated postprandial gastro-oesophageal reflux

This randomized, single-blind cross-over study compared the effectiveness of a conventional alginate reflux barrier formulation (20 mL single dose of Liquid Gaviscon; sodium alginate, sodium bicarbonate, calcium carbonate) with a 20 mL single dose of an alginate-cimetidine combination formulation (Algitec Suspension; sodium alginate, cimetidine) in the suppression of food and acid reflux into the oesophagus after a test meal in 12 healthy volunteers. Subjects were fasted overnight before the study. A pH electrode and gamma detector were accurately positioned 5 cm above the cardia. The volunteers received a 99mTc-labelled meal designed to provoke reflux and then either remained untreated, or 30 min later were given either Algitec Suspension or Liquid Gaviscon. Reflux of both food and acid into the oesophagus was measured for 3 h. There was a seven day wash-out period between each treatment. Food reflux in the control group was 22,878 +/- 14,385 counts x 10(3) and this was significantly suppressed by both Liquid Gaviscon (174 +/- 128 (s.e.) counts x 10(3); P = 0.003); however, although the reduction of food reflux to 3812 +/- 2322 counts x 10(3) observed after Algitec treatment was considerable, this did not reach statistical significance (P > 0.05) due to the large intersubject variation. Liquid Gaviscon was significantly better at reducing food reflux than Algitec (P = 0.001). Gaviscon also significantly reduced acid reflux when compared with the control group (1.08 +/- 0.73 vs 5.87 +/- 3.27% recording time oesophageal pH < 4, respectively) (P = 0.03). The slight reduction in acid reflux after Algitec treatment (3.25 +/- 1.82% recording time oesophageal pH < 4) also did not reach statistical significance. The difference between Algitec and Gaviscon treatment was also not significant.     

Design, modeling, and optimization of mechanically reconfigurableaperture antennas

The work in this study develops the framework for placement and actuation of novel reconfigurable dual-offset contour beam reflector antennas (DCBRA). Toward that end, the methodology for the antennas' design is defined. In addition, two separate optimization problems are stated and solved: actuator position optimization and actuation value optimization. For the former, a method termed as greatest error suppression method is proposed where the position of each actuator is decided one by one after each evaluation of the error between the desired subreflector shape and the actual subreflector shape. For the second problem, a mathematical analysis shows that there exists only one optimal configuration. Two optimization techniques are used for the second problem: the simulated annealing algorithm and a simple univariate optimization technique. The univariate technique always generates the same optimal configuration for different initial configurations and it gives the low bound in the evaluation of the error. The simulated annealing algorithm is a stochastic technique used to search for global optimum point. Finally, as an example the results of the proposed optimization techniques are presented for the generation of a subreflector shape corresponding to the geographical outline of Brazil