The thermodynamics of latent fingerprint corrosion of metal elements and alloys

Redox reactions taking place between the surface of a metal and fingerprint residue have been expressed thermodynamically in terms of both the Nernst equation for reduction potential and the complexation constant for the formation of complex metal halide ions in aqueous solution. These expressions are used to explain experimental results for the corrosion of 10 different metal elements by fingerprint residue in air at room temperature. Corrosion of noble metals, such as silver and gold, supports the proposition that the degree of metal corrosion is enhanced by the presence of chloride ions in eccrine sweat. Extending the experiments to include 10 metal alloys enabled the construction of a fingerprint corrosion series for 20 different metals. Fingerprint corrosion on metals alloyed with > approximately 40% copper was found to display third level fingerprint detail. A comparison of both conventional ink on paper and digital (Livescan) fingerprinting techniques with fingerprints deposited on 9 Karat gold alloy has shown that gold alloy depositions are least susceptible to third level detail obliteration by poor fingerprint capturing techniques.     

Social Endorsement Cues and Political Participation

Which individuals are most responsive to get-out-the-vote (GOTV) messages that emphasize the social aspects of voting? Recent literature has shown that GOTV messages that emphasize the social environment in which an individual is embedded are particularly effective at increasing voting rates. Until now, we have not had good estimates for the types of people for whom social GOTV messages are most effective. We report a new set of disaggregated results of a randomized controlled trial of political mobilization messages delivered to 61 million Facebook users during the 2010 U.S. Congressional elections. The results suggest that social endorsement cues are differentially effective for different types of political behaviors—political expression, information seeking, and voting—and for different kinds of people, based on both demographic and social characteristics, raising new questions about the mechanisms explaining social pressure effects.     

Contested water,contested development: unpacking the hydro-social cycle of the Ñuble River,Chile

The way that water is entangled with broader social relations has become a prominent concern in political ecology, geography and beyond. Employing the concept of the hydro-social cycle highlights how water is produced by, and simultaneously constitutes, social and power relations. Applying and expanding the hydro-social cycle as an analytical lens, this paper explores the contestation of different discourses of water. Looking at the conflict over the construction of a proposed dam in Chile, we examine different meanings given to water to understand how these produce uneven power relations with material and symbolic implications. By teasing out the workings and contestations of this conflict as a hydro-social cycle, we aim to highlight the diverse range of elements enlisted in it beyond water, to expose its complexity and to search for more just and inclusive alternatives.     

Behavioural case linkage with solved and unsolved crimes

Offender behaviour is used to distinguish between crimes committed by the same person (linked crimes) and crimes committed by different people (unlinked crimes) through behavioural case linkage. There is growing evidence to support the use of behavioural case linkage by investigative organisations such as the police, but this research is typically limited to samples of solved crime that do not reflect how this procedure is used in real life. The current paper extends previous research by testing the potential for behavioural case linkage in a sample containing both solved and unsolved crimes. Discrimination accuracy is examined across crime categories (e.g. a crime pair containing a car theft and a residential burglary), across crime types (e.g. a crime pair containing a residential burglary and a commercial burglary), and within crime types (e.g. a crime pair containing two residential burglaries) using the number of kilometres (intercrime distance) and the number of days (temporal proximity) between offences to distinguish between linked and unlinked crimes. The intercrime distance and/or the temporal proximity were able to achieve statistically significant levels of discrimination accuracy across crime categories, across crime types, and within crime types as measured by Receiver Operating Characteristic (ROC) analysis. This suggests that behavioural case linkage can be used to assist the investigation, detection and prosecution of prolific and versatile serial offenders.     

Enhancement of Latent Fingerprints on Fabric Using the Cyanoacrylate Fuming Method Followed by Infrared Spectral Mapping

A method has been developed for the visualization of latent fingerprints on fabrics, which is based upon cyanoacrylate (superglue) fuming followed by imaging using an infrared microscope. Results show that imaging on smooth, shiny fabrics such as polyester, silk, nylon, and acetate of different colors and patterns can give an improvement over existing enhancement methods. Results for cotton and polycotton were less successful and it is thought this may be due a combination of the presence of the carbonyl functional group in these fabrics as well as their absorbency to fingerprint sweat. The carbonyl peak (1700 cm^?1) provided the optimum spectroscopic feature to map and image a fingerprint. Comparisons between infrared mapping at a specific frequency range and principal component analysis showed that improved imaging was obtained with principal component analysis.     

Comparison of Chemical and Heating Methods to Enhance Latent Fingerprint Deposits on Thermal Paper

A comparison is made of proprietary methods to develop latent fingerprint deposits on the inked side of thermal paper using either chemical treatment (Thermanin) or the application of heat to the paper (Hot Print System). Results with a trial of five donors show that the application of heat produces statistically significantly more fingerprint ridge detail than the chemical treatment for both fingerprint deposits aged up to 4 weeks and for a nine sequence depletion series. Subjecting the thermal paper to heat treatment with the Hot Print System did not inhibit subsequent ninhydrin chemical development of fingerprint deposits on the noninked side of the paper. A further benefit of the application of heat is the rapid development of fingerprint deposits (less than a minute) compared with up to 12 h for the Thermanin chemical treatment.     

The property-contract boundary: an economic analysis of leases

This paper examines how the legal design of a leasing arrangementaffects the value of the leased asset. The model focuses onthe incentive problems that arise when the ownership and useof an asset are separated. The results suggest that an efficientlydesigned lease may involve elements of property law, contractlaw, or both. This conclusion helps explain why the law of leaseshas historically occupied the nexus between these two areasof the common law.     

Visualization of latent fingerprint corrosion of metallic surfaces

Abstract:  Chemical reactions between latent fingerprints and a variety of metal surfaces are investigated by heating the metal up to temperatures of ∼600°C after deposition of the fingerprint. Ionic salts present in the fingerprint residue corrode the metal surface to produce an image of the fingerprint that is both durable and resistant to cleaning of the metal. The degree of fingerprint enhancement appears independent of the elapsed time between deposition and heating but is very dependent on both the composition of the metal and the level of salt secretion by the fingerprint donor. Results are presented that show practical applications for the enhancement to fingerprints deposited in arson crime scenes, contaminated by spray painting, or deposited on brass cartridge cases prior to discharge. The corrosion of the metal surface is further exploited by the demonstration of a novel technique for fingerprint enhancement based on the electrostatic charging of the metal and then the preferential adherence of a metallic powder to the corroded part of the metal surface.     

A Modified Electrostatic Adsorption Apparatus for Latent Fingerprint Development on Unfired Cartridge Cases

Visualization of latent fingerprints on metallic surfaces by the method of applying electrostatic charging and adsorption is considered as a promising chemical‐free method, which has the merit of nondestruction, and is considered to be effective for some difficult situations such as aged fingerprint deposits or those exposed to environmental extremes. In fact, a portable electrostatic generator can be easily accessible in a local forensic technology laboratory, which is already widely used in the visualization of footwear impressions. In this study, a modified version of this electrostatic apparatus is proposed for latent fingerprint development and has shown great potential in visualizing fingerprints on metallic surfaces such as cartridge cases. Results indicate that this experimental arrangement can successfully develop aged latent fingerprints on metal surfaces, and we demonstrate its effectiveness compared with existing conventional fingerprint recovery methods.     

The Effect of Varying the Composition of Fingerprint Sweat Deposits on the Corrosion of Brass and Fingerprint Visibility

Corrosion of α‐phase brass by sebaceous sweat fingerprint deposits produced identifiable impressions in a majority of samples (n = 40) 4 days after deposition. Combining sebaceous with eccrine sweat yielded a greater percentage of identifiable fingerprint deposits, although this increase was not statistically significant. Production of identifiable fingerprints from eccrine sweat deposits was dependent on the sampling time of year with deposits taken during summer months giving similar percentages of identifiable fingerprints to sebaceous deposits. A statistically significant positive correlation was found between elapsed days after deposition and identifiable eccrine (ρ = 0.787, p < 0.05), sebaceous (ρ = 0.724, p < 0.05), and eccrine/sebaceous mixture (ρ = 0.908, p < 0.01) fingerprints deposited during summer months. The summer increase in the percentage of identifiable eccrine sweat deposits was statistically significant compared to winter eccrine deposits (p < 0.0001). Observations were consistent with results obtained from artificial sebaceous and eccrine sweat.