Watching the Watchmen: Best Practices for Police Body Cameras

This paper examines the research on the costs and benefits of police body cameras, arguing that the devices can, if properly deployed and regulated, provide a valuable disincentive to police abuses as well as valuable evidence for punishing abuses when they occur

A Taxonomy for Routing Protocols in Mobile Ad Hoc Networks

A Mobile Ad hoc NETwork (manet) is a mobile, multi-hop wireless network which is capable of autonomous operation. It is characterized by energy-constrained nodes, bandwidth-constrained, variable-capacity wireless links and dynamic topology, leading to frequent and unpredictable connectivity changes. In the absence of a fixed infrastructure, manet nodes cooperate to provide routing services, relying on each other to forward packets to their destination. Routing protocols designed for the fixed network are not effective in the dynamic and resource-constrained manet environment; many alternative routing protocols have been suggested. This report provides an overview of a number of manet routing protocols. More importantly, it defines a taxonomy that is suitable for examining a wide variety of protocols in a structured way and exploring tradeoffs associated with various design choices. The emphasis is on practical design and implementation issues rather than complexity analysis

The immune response to malaria in utero.

Malaria causes tremendous early childhood morbidity and mortality, providing an urgent impetus for the development of a vaccine that is effective in neonates. However, the infant immune response to malaria may be influenced by events that occur well before birth. Placental malaria infection complicates one quarter of all pregnancies in Africa and frequently results in exposure of the fetus to malaria antigens in utero, while the immune system is still developing. Some data suggest that in utero exposure to malaria may induce immunologic tolerance that interferes with the development of protective immunity during childhood. More recently, however, a growing body of evidence suggests that fetal malaria exposure can prime highly functional malaria-specific T- and B-cells, which may contribute to postnatal protection from malaria. In utero exposure to malaria also impacts the activation and maturation of fetal antigen presenting cells and innate lymphocytes, which could have implications for global immunity in the infant. Here, we review recent advances in our understanding of how various components of the fetal immune system are altered by in utero exposure to malaria, discuss factors that may tilt the critical balance between tolerance and adaptive immunity, and consider the implications of these findings for malaria prevention strategies

Increments to life and mortality tempo

This paper introduces and develops the idea of “increments to life.†Increments to life are roughly analogous to forces of mortality: they are quantities specified for each age and time by a mathematical function of two variables that may be used to describe, analyze and model changing length of life in populations. The rationale is three-fold. First, I wanted a general mathematical representation of Bongaart’s “life extension†pill (Bongaarts and Feeney 2003) allowing for continuous variation in age and time. This is accomplished in sections 3-5, to which sections 1-2 are preliminaries. It turned out to be a good deal more difficult than I expected, partly on account of the mathematics, but mostly because it requires thinking in very unaccustomed ways. Second, I wanted a means of assessing the robustness of the Bongaarts-Feeney mortality tempo adjustment formula (Bongaarts and Feeney 2003) against variations in increments to life by age. Section 6 shows how the increments to life mathematics accomplishes this with an application to the Swedish data used in Bongaarts and Feeney (2003). In this application, at least, the Bongaarts-Feeney adjustment is robust. Third, I hoped by formulating age-variable increments to life to avoid the slight awkwardness of working with conditional rather than unconditional survival functions. This third aim has not been accomplished, but this appears to be because it was unreasonable to begin with. While it is possible to conceptualize length of life as completely described by an age-varying increments to life function, this is not consistent with the Bongaarts-Feeney mortality tempo adjustment. What seems to be needed, rather, is a model that incorporates two fundamentally different kinds of changes in mortality and length of life, one based on the familiar force of mortality function, the other based on the increments to life function. Section 7 considers heuristically what such models might look like.adult mortality, increments to life, length of life, life expectancy at birth, mortality, mortality measurement, mortality tempo, mortality tempo adjustment, period-cohort relationships, risk of death, robustness of Bongaarts-Feeney method, tempo adjustment

Characterisation of Nitinol for the Design of Tuneable Transducers

No abstract available

A comparison of two configurations for a dual-resonance cymbal transducer

The ability to design tuned ultrasonic devices that can be operated in the same mode at two different frequencies has the potential to benefit a range of applications, such as surgical cutting procedures where the penetration through soft then hard tissues could be enhanced by switching the operating frequency. The cymbal transducer has recently been adapted to form a prototype ultrasonic surgical cutting device that operates at a single frequency. In this paper, two different methods of configuring a dual-resonance cymbal transducer are detailed. The first approach relies on transducer fabrication using different metals for the two end-caps, thereby forming a dual-resonance transducer. The second employs transducer end-caps composed from a shape memory alloy, superelastic Nitinol. The resonance frequency of the Nitinol transducer depends on the phase microstructure of the material, switchable through the temperature and/or stress dependency of the Nitinol end-caps. The vibration response of each transducer is measured through electrical impedance measurements and laser Doppler vibrometry, and finite element analysis is used to show the sensitivity of transducer modal response to the fabrication processes. Through this research, two viable dual-resonance cymbal transducers are designed and characterised, and compared to illustrate the advantages and disadvantages of the two different approaches

Nitinol Cymbal Transducers for Power Ultrasonics Applications

The effects of shape memory alloy phenomena such as superelasticity and thermal phase change on the dynamic response of a cymbal transducer incorporating two Nitinol end-caps has not been studied into detail. The experimental results, using both vibration response and electrical impedance measurements, demonstrate that the use of Nitinol as the end-cap material for a cymbal transducer can impose significant effects on the vibration response. The understanding of the effect Nitinol has on the vibration response of a cymbal transducer provides future opportunities to design a power ultrasonic cymbal transducer that can operate with two different and selectable vibration behaviours, which is particularly appealing in a range of applications, including ultrasonic cutting devices that are required to penetrate more than one material