Differentiation of black gel inks using optical and chemical techniques

Gel ink pens have become a common writing instrument in the United States. Questioned document examiners often attempt to optically differentiate gel inks from each other and from other non-ballpoint ink writings (e.g., those from roller-ball pens). Since early formulations were primarily pigment-based, they do not elute when analyzed by thin-layer chromatography. However, recent gel ink formulations (i.e., within the past five years) include dye-based inks that can be easily separated. This study differentiates black gel inks using optical and chemical techniques. The techniques include: microscopy, visible and near infrared reflectance, near infrared luminescence, thin-layer chromatography (TLC), spot tests, and gas chromatography/mass spectrometry (GC/MS). As a result of this study a flow chart has been developed allowing for a systematic determination of a questioned ink. In addition, an analysis of volatile compounds found in gel inks revealed that there are some unique ingredients that may be found in gel inks that are not typically found in other non-ballpoint inks.     

Reliability of bloodhounds in criminal investigations

Anecdotal evidence and legend have suggested that bloodhounds are capable of trailing and alerting to a human by his or her individual scent. This same evidence may be presented to a court of law in order to accuse a particular suspect or suspects of a crime. There is little to no scientific evidence confirming the bloodhound's ability to trail and discriminate the scent of different individual humans. Eight bloodhounds (3 novice and 5 veteran), trained in human scent discrimination were used to determine the reliability of evidence, garnered through the use of bloodhounds, in a court of law. These dogs were placed on trails in an environment that simulated real-life scenarios. Results indicate that a veteran bloodhound can trail and correctly identify a person under various conditions. These data suggest that the potential error rate of a veteran bloodhound-handler team is low and can be a useful tool for law enforcement personnel.     

The forensic analysis of thermal transfer printing

Thermal transfer printing refers to printing processes that utilize heat to produce an image by either physical or chemical means or by a combination of both. As the technology has improved and the supplies have become less expensive, the use of thermal printing in the personal and business markets has increased significantly. Specifically, dye diffusion thermal transfer and thermal mass transfer have become predominant in the production of counterfeit credit cards, drivers' licenses, and other types of documents produced on plastic media. Chemical analysis by means of thin layer chromatography (TLC) has proven to be useful in characterizing various types of inks (e.g., writing and inkjet inks). In this study, the authors examined 81 different samples that included a total of 54 printer samples (43 photographic prints on paper and eleven plastic card samples) and 27 printer ribbons. A new TLC method was developed and tested utilizing a solvent system (80% n-hexane, 3% methyl ethyl ketone, and 17% ethyl acetate) that is capable of producing excellent resolution.     

Characterization of surface organic components of human hair by on-line supercritical fluid extraction-gas chromatography/mass spectrometry: a feasibility study and comparison with human identification using mitochondrial DNA sequences

This paper discusses results of a supercritical fluid extraction-gas chromatography/mass spectrometry (SFE-GC/MS) study of small samples ( 100 microg to 1 mg) of human scalp hair. The method offers a number of benefits including greater sensitivity than liquid extraction methods because the entire extractable mass is transferred to the analytical system, compared with only a few percent from a conventional liquid extraction/injection. The project's goals were to determine if SFE-GC/MS analyses of the surface-extractable components of an individual's hair yield consistent chemical profiles and to investigate if the profiles are sufficiently different to distinguish them from those of other individuals. In addition, the mtDNA sequences from ten of the same individuals used in the SFE-GC/MS study from four family units were determined, and, while the families were distinguishable, the maternal relations yielded identical sequences. In tandem, SFE-GC/MS and mtDNA techniques may provide valuable complementary data from forensic hair samples.     

Revealing Preferences: Empirical Estimation of a Crisis Bargaining Game with Incomplete Information

We develop an empirical estimator directly from an extensive-formcrisis bargaining game with incomplete information and discussits features and limitations. The estimator makes it possibleto draw inferences about states' payoffs from observationaldata on crisis outcomes while remaining faithful to the theorizedstrategic and informational structure. We compare this estimatorto one based on a symmetric information version of the samegame, using the quantal response equilibrium proposed in thiscontext by Signorino (1999, American Political Science Review93:279–298). We then address issues of identificationthat arise in trying to learn about actors' utilities by observingtheir play of a strategic game. In general, a number of identifyingrestrictions are needed in order to pin down the distributionof payoffs and the effects of covariates on those payoffs.     

A longitudinal study of ego identity development at a liberal arts college

Ego identity development in the areas of occupational choice, religion, and political ideology was studied using Marcia's categorization system. The results indicated a significant increase in the frequency of the identity achiever status for occupational choice and corresponding decreases in the frequency of the moratorium and identity diffusion statuses. A significant decrease in the frequency of foreclosures on religion was also found. In those instances where students underwent an identity crisis, the probability of resolving it successfully was very high. High scores on the Cultural Sophistication scale of the College Student Questionnaire-Part 1 were found to be associated with presence in the identity achievement status. For students not in the achiever status as freshmen, an interest in various literary and art forms was predictive of becoming an achiever while in college.Received his Ph.D. from SUNY/Buffalo. Recent research has been mainly concerned with the development of ego identity and with techniques for resolving identity crises.Received his Ph.D. from Syracuse University. Recent research has been mainly concerned with personality moderators of human judgment.