Explaining Dosage Diffusion During Hot Spot Patrols: An Application of Optimal Foraging Theory to Police Officer Behavior

Drawing from the concepts of optimal foraging theory, this paper presents and tests the assumptions of a foraging theory of police behavior during hot spots patrols. The theory explains why, over time, officers involved in hot spots policing interventions would leave the hot spots they are assigned to police and begin working within other locations. We test what factors influence the amounts of activity that officers undertake outside of their assigned hot spots and at nearby streets using data gathered as part of the Philadelphia Foot Patrol Experiment. Officers performed more activity outside of their beats as the experiment progressed. Several theoretically relevant variables predict the level of activity that officers perform outside their beats, including the size of the target area and the amounts of crime occurring within and outside of the target area. “Dosage diffusion” might be one reason why hot spot interventions have diminishing effects over time. From an optimal foraging theory perspective, hot spots requiring police officers to constrain their actions to pre-defined areas can be perceived as counter-intuitive by the officers, especially over extended periods of time. The results of this study support the suggestion that hot spots patrols should be short-term and randomly rotated across hot spots.     

Stubs Versus Swabs? A Comparison of Gunshot Residue Collection Techniques

Abstract: The collection efficiency of two widely used gunshot residue (GSR) collection techniques—carbon‐coated adhesive stubs and alcohol swabs—has been compared by counting the number of characteristic GSR particles collected from the firing hand of a shooter after firing one round. Samples were analyzed with both scanning electron microscopy and energy dispersive X‐rays by an experienced GSR analyst, and the number of particles on each sample containing Pb, Ba, and Sb counted. The adhesive stubs showed a greater collection efficiency as all 24 samples gave positive results for GSR particles whereas the swabs gave only positive results for half of the 24 samples. Results showed a statistically significant collection efficiency for the stub collection method and likely reasons for this are considered.     

Commercial Sexual Exploitation of Children: an Assessment of Offender Characteristics

The commercial sexual exploitation of children (CSEC), specifically child trafficking, producers or consumers of child sex trafficking (i.e., prostitution), sexual abuse images, and enticement, has become a growing area of concern. The increasing profitability of CSEC, combined with the clandestine nature of the offenses, calls for immediate attention from international law enforcement and the mental health community. Paramount to the resolution of this global crisis is the identification of the perpetrators of various CSEC crimes. The research pertaining to these offenders is most frequently aggregated and limited to basic demographic data, providing a larger, more generalized picture of CSEC. The purpose of this study is to determine characteristics, within a sample of known CSEC offenders, that differentiate among offenders who engage in sex trafficking as trafficker; engage in sex trafficking as a producer or consumer; produce, distribute, or possess child sexual abuse images; and travel or use enticements to engage in illicit sexual contact with a minor. This observational, survey design includes a record review of 98 offenders who were processed through the FBI Miami Field Office. Results showed that males are more likely to engage in CSEC offenses compared to females. Offenders who collect child sexual abuse images tended to be employed, had no history of prior arrests, and were older than other CSEC offenders. Additionally, engaging in befriending strategies in order to gain access to a victim was also predictive of involvement in child sexual abuse images. Unemployment was the only statistically significant predictor of engaging in child sex trafficking as either a sex buyer or a producer. Finally, perpetrators who engaged in the traveling/enticement of victims were found to be younger, unemployed, single, and without a known history of contact offending. Implications of the findings are discussed.     

Non-traumatic forensic neuropathology

The practicing Forensic Pathologist is likely to encounter case material in which either the cause of death or a major contribution to the cause of death is underlying damage to or disease of the central nervous system. While it is good practice in many instances to have a working relationship with a Department of Neuropathology, from which advice and practical help can be sought, there may be instances when the Forensic Pathologist needs to proceed on a basis of a working knowledge of Forensic Neuropathology up to and including how to examine the specimen and take tissue blocks for processing and subsequent histological examination. Some of the more common conditions of the central nervous system such as damage consequent to hypoxia-ischaemia, hypoglycemia and epilepsy, the encephalopathies associated with altered sodium concentration, deficiency due to Vitamin B(1) and various neurodegenerative diseases that manifest as dementia and include Alzheimer's disease, cortical Lewy body disease and the prion disorders, are outlined in this article.     

A test of the effectiveness of speaker verification for differentiating between identical twins

This paper presents investigations into the ability of speaker verification technology to discriminate between identical twins. It is shown that whilst, in general, the genetic and non-genetic characteristics of voice are both of value to speaker verification capabilities, it is the latter which is highly beneficial in the separation of the speech of identical twins. It is further demonstrated that through the use of unconstrained cohort normalisation as a complementary means for the exploitation of such voice characteristics, the verification reliability can be considerably enhanced for both identical twins and unrelated speakers. Experiments were conducted using a bespoke clean-speech database consisting of utterances from 49 identical twin pairs. The paper details the problem in speaker verification posed by identical twins, discusses the experimental investigations and provides an analysis of the results.