Human visual system-based image enhancement and logarithmic contrast measure.

Varying scene illumination poses many challenging problems for machine vision systems. One such issue is developing global enhancement methods that work effectively across the varying illumination. In this paper, we introduce two novel image enhancement algorithms: edge-preserving contrast enhancement, which is able to better preserve edge details while enhancing contrast in images with varying illumination, and a novel multihistogram equalization method which utilizes the human visual system (HVS) to segment the image, allowing a fast and efficient correction of nonuniform illumination. We then extend this HVS-based multihistogram equalization approach to create a general enhancement method that can utilize any combination of enhancement algorithms for an improved performance. Additionally, we propose new quantitative measures of image enhancement, called the logarithmic Michelson contrast measure (AME) and the logarithmic AME by entropy. Many image enhancement methods require selection of operating parameters, which are typically chosen using subjective methods, but these new measures allow for automated selection. We present experimental results for these methods and make a comparison against other leading algorithms.     

River research and applications across borders

Rivers flow across national borders, unfettered by political distinctions, and the ecological health of rivers is closely linked to their degree of connectivity. River research today is more global than it has ever been, but we show that river research, engineering, and management still operate within homegrown local paradigms. As a basis for this discussion, we studied the citation networks surrounding the most widely cited papers in our field, assessing the degree to which researchers have collaborated across geographical boundaries and fully drawn from the international literature. Despite gains over time, our field remains surprisingly and pervasively provincial. The likely explanation for provincial bias is that researchers are generally more familiar and comfortable with their own research methods, sites, and agendas. However, local focus has tangible consequences. For example, contrasting paradigms and differing approaches to river restoration and to flood‐risk management show that opportunities are lost when we fail to learn from the successes and failures of other regions. As we look to the future, increased engagement across political and intellectual and physical borders should propel the field of river science into new and exciting directions.     

Antagonism of etonitazene''s effects in rats and pigeons

The effect of a proteolytic enzyme, pronase, on material present in cisternae of the granular endoplasmic reticulum of mole pinealocytes demonstrates their proteinaceous nature.     

Resolution of ambiguity in parsing

Summary The use of context-free grammars to define the syntax of programming languages is complicated by the phenomenon of ambiguity. Ambiguity can be resolved by the specification of a unique canonical parse. A set of rules is given which defines a canonical bottom-up parse, and these rules are implemented in a left-to-right bottom-up parsing algorithm. A second set of rules is given which defines a canonical top-down parse, and these rules are similarly implemented in a left-to-right top-down parsing algorithm.     

Characterization of used frying oils. Part 1: Isolation and identification of compound classes

In this study, an analytical scheme is presented for detailed qualitative comparisons between heated and unheated oils. This scheme is less subject to loss or alteration of sample components when compared with methods that characterize the distillable non-urea adducting portion of heated oils. In this work, oils were first converted to their corresponding fatty acid methyl esters (FAMEs) by transesterification. These FAMEs were then separated by degree of polarity by means of adsorption chromatography and solid-phase extraction. High-resolution capillary gas and liquid chromatography were used to profile isolated fractions. Mass spectrometric and infrared analyses of major chromatographic features were used to identify the presence of aldehydes, epoxides, ketones, alcohols, phytosterols and dimer methyl esters down to 5 ppm in the original sample.     

The corrosion of nickel–aluminium bronze in seawater

Nickel–aluminium bronze (NAB) alloys show good corrosion resistance under marine conditions. The corrosion behaviour of cast and wrought NAB alloys is illustrated in this work through a range of electrochemical techniques including open-circuit potentiometry with time, oxygen reduction voltammetry, NAB dissolution voltammetry, potential step (or flow step) current transients and linear polarisation resistance. The galvanic coupling of NAB to stainless steel or copper is examined by zero resistance ammetery. The importance of using controlled flow working electrodes is illustrated by the use of a rotating disc electrode, a rotating cylinder electrode and a bimetallic (NAB/copper–nickel) rotating cylinder electrode. In addition to controlling the hydrodynamics, such electrodes allow charge transfer data to separate from those of mass transport control under mixed kinetic control. Longer term seawater immersion trials on planar coupons coupled to titanium or cupronickel are also reported. The relative contributions of erosion and corrosion attack are considered using a wall-jet electrode and the corrosion characteristics of NAB are compared to those of copper and copper–nickel in chloride media.     

Freeze-substitution techniques for preparing nematodes for scanning electron microscopy

The effect of different substitution times, temperatures and the incorporation of fixatives on the preservation of three species of nematode for scanning electron microscopy by freeze substitution with methanol, followed by critical point drying, is investigated. Hammerschmidtiella diesingi adults and Trichostrongylus colubriformis infective juveniles were successfully preserved using methanol at 253 K as the substitution medium. Preservation deteriorated with long substitution times, suggesting the extraction of material and that substitution times should be kept as brief as possible. Panagrolaimus davidi was not successfully preserved using pure methanol, but preservation was improved by using fixatives in the substitution medium, the best results being obtained with 1% OsO₄/3% glutaraldehyde in methanol. A substitution temperature of 193 K did not give any improvement in preservation. The differences in the quality of preservation between the three species may be due to the relative ability of the cuticle to withstand collapse during critical point drying. Chemical fixation using cold fixative resulted in the retention of a natural posture but poor preservation, whereas hot fixatives resulted in good preservation but the loss of a natural posture. Freeze substitution in methanol may prove useful in the preparation of specimens possessing cuticles or cell walls which have sufficient strength to withstand the drying process (e.g. arthropods, plants, fungi, nematodes). More delicate specimens may require the incorporation of fixatives into the substitution medium or conventional fixation.     

Micro- and Nano-scale Tribo-Corrosion of Cast CoCrMo

Previous studies have established that some of the wear damage seen on cast CoCrMo joint surface is caused by entrained third-body hard particles. In this study, wet-cell micro-indentation and nano-scratch tests have been carried out with the direct aim of simulating wear damage induced by single abrasive particles entrained between the surfaces of cast CoCrMo hip implants. In situ electrochemical current noise measurements were uniquely performed to detect and study the wear-induced corrosion as well as the repassivation kinetics under the micro-/nano-scale tribological process. A mathematical model has been explored for the CoCrMo repassivation kinetics after surface oxide film rupture. Greater insights into the nature of the CoCrMo micro-/nano-scale wear-corrosion mechanisms and deformation processes are determined, including the identification of slip band formation, matrix/carbide deformation, nanocrystalline structure formation and strain-induced phase transformation. The electrochemical current noise provides evidence of instantaneous transient corrosion activity at the wearing surface resulting from partial oxide rupturing and stripping, concurrent with the indent/scratch.     

Trends in the use of large wood in UK river restoration projects: insights from the National River Restoration Inventory

Large Wood (LW) is increasingly employed in river restoration to promote physical habitat heterogeneity and ecological diversity. To explore how LW has been used in restoration schemes across the United Kingdom in recent decades, we analysed data on 912 LW projects archived in the UK’s National River Restoration Inventory (NRRI). The number of LW schemes has continued to increase following the earliest records in the 1990s, largely tracking overall trends in river restorations. LW projects have been predominantly located in lowland, rural streams, although there has been a notable cluster in and around London. LW projects have mainly revolved around the desire to deliver hydromorphological improvements and specifically the creation of fish habitat. Most schemes used LW in simple deflector forms despite the growing scientific evidence of the benefits of using structurally complex LW. Post project monitoring has been limited and mostly restricted to photographic records. This type of database analysis can provide important insights and help guide future restoration practice.