Fire ant self-assemblages

Fire ants link their legs and jaws together to form functional structures called self- assemblages. Examples include floating rafts, towers, bridges, and bivouacs. We investigate these self-assemblages of fire ants. Our studies are motivated in part by the vision of providing guidance for programmable robot swarms. The goal for such systems is to develop a simple programmable element from which complex patterns or behaviors emerge on the collective level. Intelligence is decentralized, as is the case with social insects such as fire ants. In this combined experimental and theoretical study, we investigate the construction of two fire ant self-assemblages that are critical to the colony’s survival: the raft and the tower. Using time-lapse photography, we record the construction processes of rafts and towers in the laboratory. We identify and characterize individual ant behaviors that we consistently observe during assembly, and incorporate these behaviors into mathematical models of the assembly process. Our models accurately predict both the assemblages’ shapes and growth patterns, thus providing evidence that we have identified and analyzed the key mechanisms for these fire ant self-assemblages. We also develop novel techniques using scanning electron microscopy and micro-computed tomography scans to visualize and quantify the internal structure and packing properties of live linked fire ants. We compare our findings to packings of dead ants and similarly shaped granular material packings to understand how active arranging affects ant spacing and orientation. We find that ants use their legs to increase neighbor spacing and hence reduce their packing density by one-third compared to packings of dead ants. Also, we find that live ants do not align themselves in parallel with nearest neighbors as much as dead ants passively do. Our main contribution is the development of parsimonious mathematical models of how the behaviors of individuals result in the collective construction of fire ant assemblages. The models posit only simple observed behaviors based on local information, yet their mathe- matical analysis yields accurate predictions of assemblage shapes and construction rates for a wide range of ant colony sizes.Ph.D

A single-phase slotless axial-flux low-power generator with ferrite magnets

The design and development of an axial-flux ferrite magnet slotless generator for use in a small-scale wind turbine is described. The 4/4-pole single-phase machine is designed for simplicity and ease of manufacture and it consists of one slotless stator disc. The generator produces approx. 12 W at 1000 rpm with electrical efficiency of up to 46%. Because the efficiency of the machine is important, the power curve characteristics and voltage produced by the generator are investigated. The presented generator should generate sufficient output DC voltage to charge 4 to 5 batteries of 12 volt each. Finally, the finite element (FE) results are compared with measurements on a prototype. The calculated values coincide to a strong degree with the experimental results

Spectral Integration and Bandwidth Effects on Speech Recognition in School-Aged Children and Adults

Previous studies have shown that adult listeners are more adept than child listeners at identifying spectrally-degraded speech. However, the development of the ability to combine speech information from different frequency regions has received little previous attention. The purpose of the present study was to determine the effect of age on the bandwidth necessary to achieve a relatively low criterion level of speech recognition for two frequency bands, then to determine the improvement in speech recognition that resulted when both speech bands were present simultaneously

High Level Trigger Configuration and Handling of Trigger Tables in the CMS Filter Farm

The CMS experiment at the CERN Large Hadron Collider is currently being commissioned and is scheduled to collect the first pp collision data in 2008. CMS features a two-level trigger system. The Level-1 trigger, based on custom hardware, is designed to reduce the collision rate of 40 MHz to approximately 100 kHz. Data for events accepted by the Level-1 trigger are read out and assembled by an Event Builder. The High Level Trigger (HLT) employs a set of sophisticated software algorithms, to analyze the complete event information, and further reduce the accepted event rate for permanent storage and analysis. This paper describes the design and implementation of the HLT Configuration Management system. First experiences with commissioning of the HLT system are also reported

Infrastructures and Installation of the Compact Muon Solenoid Data Acquisition at CERN

At the time of this paper, all hardware elements of the CMS Data Acquisition System have been installed and commissioned both in the underground and surface areas. This paper describes in detail the infrastructures and the different steps that were necessary from the very beginning when the underground control rooms and surface building were building sites to a working system collecting data fragment from ~650 sources and sending them to surface for assembly and analysis

Framing the agricultural use of antibiotics and antimicrobial resistance in UK national newspapers and the farming press

Despite links to animal disease governance, food and biosecurity, rural studies has neglected consideration of how actors make sense of the use of antibiotics in animal agriculture and the implications for animal and human health. As antimicrobial resistance (AMR) has become a high-profile problem, the contribution of animal antibiotics is frequently mentioned in scientific and policy documents but how different agricultural actors interpret its significance is less clear. This paper offers the first social scientific investigation of contestation and consensus surrounding the use of antibiotics in agriculture and their implications for AMR as mediated through mainstream news-media and farming print media in the UK. Frame analysis of four national newspapers and one farming paper reveals three distinct frames. A ‘system failure’ frame is the most frequently occurring and positions intensive livestock production systems as a key contributor to AMR-related crises in human health. A ‘maintaining the status quo’ frame argues that there is no evidence linking antibiotics in farming to AMR in humans and stresses the necessity of (some) antibiotic use for animal health. A third frame – which is only present in the farming media – highlights a need for voluntary, industry-led action on animal antibiotic use in terms of farmer self-interest. Common to all frames is that the relationship between agricultural use of antibiotics and problems posed by AMR is mostly discussed in terms of the implications for human health as opposed to both human and animal health