Policies restricting semiautomatic assault weapons and large-capacity ammunition magazines are intended to reduce gunshot victimizations by limiting the stock of semiautomatic firearms with large ammunition capacities and other military-style features conducive to criminal use. The federal government banned such weaponry from 1994 to 2004, and a few states currently impose similar restrictions. Recent debates concerning these weapons have highlighted their use in mass shootings, but there has been little examination of their use in gun crime more generally since the expiration of the federal ban. This study investigates current levels of criminal activity with assault weapons and other high-capacity semiautomatics in the USA using several local and national data sources including the following: (1) guns recovered by police in ten large cities, (2) guns reported by police to federal authorities for investigative tracing, (3) guns used in murders of police, and (4) guns used in mass murders. Results suggest assault weapons (primarily assault-type rifles) account for 2-12% of guns used in crime in general (most estimates suggest less than 7%) and 13-16% of guns used in murders of police. Assault weapons and other high-capacity semiautomatics together generally account for 22 to 36% of crime guns, with some estimates upwards of 40% for cases involving serious violence including murders of police. Assault weapons and other high-capacity semiautomatics appear to be used in a higher share of firearm mass murders (up to 57% in total), though data on this issue are very limited. Trend analyses also indicate that high-capacity semiautomatics have grown from 33 to 112% as a share of crime guns since the expiration of the federal ban-a trend that has coincided with recent growth in shootings nationwide. Further research seems warranted on how these weapons affect injuries and deaths from gun violence and how their regulation may impact public health.

Purpose The purpose of this paper is to document the diffusion of license plate readers (LPRs) in the USA, examining the variety, evolution and tracking of their uses through a national survey. Design/methodology/approach This study employs a national, stratified, representative survey of US law enforcement agencies with 100 or more officers. Findings LPR technology is currently used by at least two-thirds of larger police agencies, which represents a more than threefold increase in LPR acquisition in the last 10 years. The number of LPRs per agency, while small (about eight on average), has also more than doubled. Federal and state funding, advocacy by law enforcement leaders, and the intuitive appeal of LPRs have likely contributed to this rapid adoption. While LPRs are still primarily used to detect and recover stolen automobiles in patrol, their use has expanded into other types of investigative and security functions. Despite the increased use and numbers of LPRs in policing, their use is highly discretionary and infrequently tracked. Practical implications LPRs continue to be widely used in law enforcement, despite a lack of strong research evidence for their crime prevention benefits. Further studies are needed on the most effective ways for agencies to utilize small numbers of LPRs and the potential return on investment for acquiring larger numbers of the devices. Originality/value This study tracks the history of LPR diffusion and use and goes beyond prior law enforcement surveys by examining specific uses of LPRs and the extent to which agencies track their uses and outcomes.

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Despite rapid advances in sensor development and technological miniaturization, it remains challenging to non-invasively record small-amplitude electrophysiological signals from an animal in its natural environment. Many advances in ecophysiology and biologging have arisen through sleep studies, which rely on detecting small signals over multiple days and minimal disruption of natural animal behavior. This paper describes the development of a surface-mounted system that has allowed novel electrophysiological recordings of sleep in wild marine mammals. We discuss our iterative design process by providing sensor-comparison data, detailed technical illustrations, and material recommendations. We describe the system’s performance over multiple days in 12 freely moving northern elephant seals (Mirounga angustirostris) sleeping on land and in water in captivity and the wild. We leverage advances in signal processing by applying independent components analysis and inertial motion sensor calibrations to maximize signal quality across large (> 10 gigabyte), multi-day datasets. Our study adds to the suite of biologging tools available to scientists seeking to understand the physiology and behavior of wild animals in the context in which they evolved.

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