Forensic analysis of bicomponent fibers using infrared chemical imaging

The application of infrared chemical imaging to the analysis of bicomponent fibers was evaluated. Eleven nominally bicomponent fibers were examined either side-on or in cross-section. In six of the 11 samples, infrared chemical imaging was able to spatially resolve two spectroscopically distinct regions when the fibers were examined side-on. As well as yielding characteristic infrared spectra of each component, the technique also provided images that clearly illustrated the side-by-side configuration of these components in the fiber. In one case it was possible to prepare and image a cross-section of the fiber, but in general the preparation of fiber cross-sections proved very difficult. In five of the 11 samples, the infrared spectra could be used to identify the overall chemical composition of the fibers, according to a published classification scheme, but the fiber components could not be spatially resolved. Difficulties that are inherent to conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic type fibers, were also encountered in the infrared chemical image analysis of bicomponent fibers. A number of infrared sampling techniques were investigated to overcome these problems, and recommendations for the best sampling technique are given. Chemical imaging results were compared with those obtained using conventional fiber microscopy techniques.     

Packing Heat in the Classroom: Public Support for “Armed Teacher” Policy

ABSTRACT

Recently, states have enacted teacher-carry laws. While controversial, little scholarship has tapped public attitudes toward such reforms. Because public opinion shapes policy, the public is an important stakeholder in this debate. Thus, we investigated three questions. First, how supportive is the public of arming teachers? Second, what demographic and social divides exist, if any, for reform approval? Finally, do crime-related perceptions, concerning views about public safety, and criminogenic influences shape policy preferences? We test these questions using a 2018 poll of Virginia residents (N = 521). Overall, approval for teacher-carry is split. Crime-related perceptions mediate some of the initial social and demographic divides in opinion but other correlates, such as parental status, remain salient predictors of views. Implications are discussed.     

Rapid and nondestructive analysis of lipstick on different substrates using ATR-FTIR spectroscopy and chemometrics

Lipstick can be an important piece of evidence in crimes like murders, rapes, and suicides. Due to its prevalence, it can be an important corroborative evidence in crime reconstruction. The analysis of such evidence can provide an evidentiary link between the suspect, the victim, object, or the crime scene. We report the use of nondestructive ATR-FTIR spectroscopy combined with chemometrics for the classification of 10 brands of lipsticks with nine samples each. Chemometric method of partial least square-discriminant analysis (PLS-DA) has been employed to interpret the data and classify the samples into their respective classes. The PLS-DA model provides an AUC figure above 0.99 in all brands except one; for which it is slightly less at 0.94. We have also tested the traces of these lipstick samples on different substrates treating them as unknowns in the already trained PLS-DA model. 100% of the samples on nine substrates viz. a cotton, nylon, plastic, dry tissue, denim (blue jeans), wet tissue, nitrile gloves, white paper, and polyester were correctly attributed to their source brand. In conclusion, the results suggest that ATR-FTIR combined with the chemometrics is a rapid, nondestructive, and accurate method for the discrimination and source attribution of lipstick. This study has potential for use in actual forensic casework conditions.     

Forensic integrity verification of video recordings based on MTS files

Digital video is used in criminal trials as evidence with legal responsibility because video content vividly depicts events occurring at a crime scene. However, using sophisticated video editing software, assailants can easily manipulate visible clues for their own benefit. Therefore, the integrity of digital video files acquired or submitted as evidence must be ensured. Forensic analysis of digital video is key to ensuring the integrity of links with individual cameras. In this study, we analyzed whether it is possible to ensure the integrity of MTS video files. Herein, we propose a method to verify the integrity of MTS files encoded by advanced video coding high definition (AVCHD), which is frequently used for video recording. To verify MTS file integrity, we propose five features. Codec information, picture timing, and camera manufacture/model are modified AVI and MP4-like format video verification features. Group of pictures and Universally Unique Identifier patterns were specifically developed for MTS streams. We analyzed the features of 44 standard files recorded using all recording options of seven cameras. We checked whether integrity can be validated on unmanipulated videos recorded in various environments. In addition, we considered whether manipulated MTS files edited in video editing software could be validated. Experimental results show that all unmanipulated and manipulated MTS files with known recording devices were discriminated only when all five features were checked. These results show that the proposed method verifies the integrity of MTS files, strengthening the validity of MTS file-based evidence in trials.     

The situational public engagement model in a municipal watershed protection program: information seeking,information sharing,and the use of organizational and social media

In an extension of the situational theory of publics, we tested a situational engagement model to answer how situational factors affect public engagement via both communication behaviors and the use of social media and organizational media. As part of the evaluation of a collaborative stormwater outreach and education campaign, a campus‐wide survey, assisted by a large public university's public affairs office, was conducted to identify key predictors of public engagement in a watershed protection program. A path analysis for the proposed situation engagement model revealed that problem recognition was the key to predicting both information seeking and sharing. The path analysis also yielded a significant association between communication behaviors and public engagement, mediated by the use of organizational media in seeking information on the issue. Further, the analysis showed a significant direct effect of involvement on engagement. The current study provided a preliminary framework that explains individuals' environmental behaviors in today's participatory and user‐generating media environment. Theoretical and practical implications were discussed. Copyright © 2015 John Wiley & Sons, Ltd.