Performance comparisons of contour-based corner detectors

Corner detectors have many applications in computer vision and image identification and retrieval. Contour-based corner detectors directly or indirectly estimate a significance measure (e.g., curvature) on the points of a planar curve, and select the curvature extrema points as corners. While an extensive number of contour-based corner detectors have been proposed over the last four decades, there is no comparative study of recently proposed detectors. This paper is an attempt to fill this gap. The general framework of contour-based corner detection is presented, and two major issues-curve smoothing and curvature estimation, which have major impacts on the corner detection performance, are discussed. A number of promising detectors are compared using both automatic and manual evaluation systems on two large datasets. It is observed that while the detectors using indirect curvature estimation techniques are more robust, the detectors using direct curvature estimation techniques are faster.     

Predicting the Lifetimes of Nuclear Waste Containers

As for many aspects of the disposal of nuclear waste, the greatest challenge we have in the study of container materials is the prediction of the long-term performance over periods of tens to hundreds of thousands of years. Various methods have been used for predicting the lifetime of containers for the disposal of high-level waste or spent fuel in deep geological repositories. Both mechanical and corrosion-related failure mechanisms need to be considered, although until recently the interactions of mechanical and corrosion degradation modes have not been considered in detail. Failure from mechanical degradation modes has tended to be treated through suitable container design. In comparison, the inevitable loss of container integrity due to corrosion has been treated by developing specific corrosion models. The most important aspect, however, is to be able to justify the long-term predictions by demonstrating a mechanistic understanding of the various degradation modes.     

Which visual measures affect change in driving difficulty after first eye cataract surgery?

Objective

To investigate self-reported driving difficulty before and after first eye cataract surgery and determine which visual measures are associated with changes in self-reported driving difficulty after surgery.

Methods

A cohort of 99 older drivers with bilateral cataract were assessed the week before and 12 weeks after first eye cataract surgery. Visual measures including visual acuity, contrast sensitivity, stereopsis and useful field of view were assessed. Self-reported driving difficulty was measured via the Driving Habits Questionnaire. Cognitive status was assessed using the Mini Mental State Examination. Regression analysis was undertaken to determine the association between changes in visual measures and self-reported driving difficulty after first eye cataract surgery.

Results

Overall, self-reported driving difficulty improved after first eye cataract surgery. However, 16% of participants did not improve and driving difficulty worsened in 11% following surgery. Improvement in driving difficulty score after first eye cataract surgery was associated with improved contrast sensitivity in the operated eye (p < 0.001), new glasses after surgery (p < 0.001), and fewer chronic health conditions (p = 0.016).

Conclusion

Contrast sensitivity rather than visual acuity was a significant factor affecting change in self-reported driving difficulty after first eye cataract surgery for bilateral patients. This has implications for driver licensing authorities worldwide that rely heavily on visual acuity as a measure of visual fitness to drive.     

The Photography of Roman Freulich from Poland to Hollywood

Professional contributions and technical innovations of photographer Roman Freulich to the Hollywood film industry are contextualised regarding the heritage of his life experiences in Czenstochowa, Poland, New York and Los Angeles. The remarkable output of Freulich's independent work, consisting of film projects that ventured far beyond the relative professional shelter provided by his popular glamour shots, emerges in the present study. Freulich sought to give voice to the voiceless as evidenced in his self-produced film Broken Earth (1936) – the first film to feature a black actor in a starring role – as well as his collaborations with the actor Paul Robeson. Freulich's immigration to America and the loss of his family members who remained in Poland are two legacies that distinguished Freulich from his fellow cameramen. Freulich both achieved a fruitful Hollywood career as a photographer of contract players – aided by his early use of the 35 mm camera – and authored a narrative of Joseph Trumpeldor, founder of the Jewish Legion. A survivor of the Holocaust, Freulich did more than preserve these dual identities; his lasting achievement lies in the incorporation of a veteran's sensitivity toward war in cinematic works that expanded early principles of still and moving image photography. Perspective by Freulich's family members is presented in original form, illuminating chronological events in the life of a pioneering photographer, writer and soldier.     

Salmonella Enteritidis in meat, poultry, and pasteurized egg products regulated by the U.S. Food Safety and Inspection Service, 1998 through 2003

The U.S. Food Safety and Inspection Service (FSIS) tests for Salmonella in meat, poultry, and egg products through three regulatory testing programs: the Pathogen Reduction-Hazard Analysis and Critical Control Point (PR-HACCP) program, the ready-to-eat program for meat and poultry products, and the pasteurized egg products program. From 1998 through 2003, 293,938 samples collected for these testing programs were analyzed for the presence of Salmonella enterica serotypes. Of these samples, 12,699 (4.3%) were positive for Salmonella, and 167 (1.3%) of the positive samples (0.06% of all samples) contained Salmonella Enteritidis. The highest incidence of Salmonella Enteritidis was observed in ground chicken PR-HACCP samples (8 of 1,722 samples, 0.46%), and the lowest was found in steer-heifer PR-HACCP samples (0 of 12,835 samples). Salmonella Enteritidis isolates were characterized by phage type, pulsed-field gel electrophoretic pattern, and antimicrobial susceptibility. Phage typing of 94 Salmonella Enteritidis isolates identified PT13 (39 isolates) and PT8 (36 isolates) as the most common types. One isolate from a ready-to-eat ham product was characterized as PT4. Electrophoretic analysis of 148 Salmonella Enteritidis isolates indicated genetic diversity among the isolates, with 28 unique XbaI electrophoretic patterns identified. Of these 148 isolates, 136 (92%) were susceptible to each of 16 antimicrobials tested. Two isolates were resistant to ampicillin alone, and 10 isolates were resistant to two or more antimicrobials. Isolation of Salmonella Enteritidis from FSIS-regulated products emphasizes the need for continued consumer education on proper food handling and cooking practices and continued work to decrease the prevalence of Salmonella in meat, poultry, and pasteurized egg products.     

Torsional properties of staple fibre plied yarns

A mathematical analysis of the mechanical governing equations applying to the torsional behaviour of multi-ply yarns under tension has been carried out. This analysis clearly shows that there are two components, a geometric component that determines the slope or gradient of the torque due to tension and a component that determines the yarn torque at zero applied tension (intrinsic torque) that depends on the fibre number, fibre moduli and diameter as well as the strand structural geometry. The effect of the ratio of the ply twist to the spinning twist on the two components of yarn torque has been numerically analysed for two-, three- and four-ply yarns prepared from singles 31 yarns spun with different spinning twists and for two different fibre diameters. Other comparisons are made for two-ply yarns prepared from 40 and 80 tex singles yarn. The model allows the effects of the various yarn and fibre parameters to be assessed and compared with experimental data. Experimental torque data for a range of two-ply yarns plied at different percentages of the singles spinning twist and also with different yarn histories and test environments are consistent with the trends identified by the model.     

Fine Structure of Chemically Modified Flax Fibre

The changes in fibre structure caused by the realignment of the microfibrils of fibre and yarn samples treated with swelling agents, such as NaOH, LiOH, ZnCl₂, and butyltrimethyl ammonium hydroxide (BTMAH), both under tension and slack, were studied by light and electron microscopy. The structural effects of treatment of the microfibrils and the ultimate fibres correlated with the measured variations in fibre tenacity and moisture regain. The results of differential thermogravimetric analysis suggested that structural realignment of the cellulosic crystals had taken place during the treatments.     

Crosslinked poly(sodium acrylate) hydrogels

Summary Samples of poly(acry1ic acid) (PAA) neutralized to varying degrees with sodium hydroxide were subjected to -irradiation to yield insoluble crosslinked polyacrylate hydrogels. The efficiency of crosslinking was found to be dependent on the degree of neutralization of the sample and the concentration of the irradiated polymer solution. The extent of water uptake of the gel was shown to be related to the degree of neutralization by titration of acid groups within the gel subsequent to cross-linking. Lightly crosslinked gels exhibited a maximum degree of swelling at a particular neutralization level. This was ascribed to a maximum in the long-range forces exerted cooperatively by the polymeric charges. The presence of simple electrolyte ions reduces swelling by screening these forces.