Analysis of crime patterns through the integration of an agent-based model and a population microsimulation

In recent years, criminologists have become interested in understanding crime variations at progressively finer spatial scales, right down to individual streets or even houses. To model at these fine spatial scales, and to better account for the dynamics of the crime system, agent-based models of crime are emerging. Generally, these have been more successful in representing the behaviour of criminals than their victims. In this paper it is suggested that individual representations of criminal behaviour can be enhanced by combining them with models of the criminal environment which are specified at a similar scale. In the case of burglary this means the identification of individual households as targets. We will show how this can be achieved using the complementary technique of microsimulation. The work is significant because it allows agent-based models of crime to be refined geographically (to allow, for example, individual households with varying wealth or occupancy measures) and leads to the identification of the characteristics of individual victims.     

The enhancement of spatial microsimulation models using geodemographics

The generation of synthetic population estimates through spatial microsimulation has been a popular technique in recent years, with applications to research and policy problems in many areas of social science. Estimation techniques typically involve cloning or matching households in surveys with small-area census data. When model estimates are benchmarked against real-world data, the models are typically well behaved and very robust, but they can struggle to capture the diversity of spatial variations shown by observed data. We argue in this paper that this is the result of 3 potential problems in spatial microsimulation estimation techniques. The first issue results from the matching process in the estimation techniques, and the second problem relates to the variations of household types in the surveys being reweighted. Third, similar household types may show different behaviours or have different attributes depending on geographical factors not contained in surveys (such as the proximity of service or job locations). The aim of this paper is to demonstrate and measure the loss of accuracy and intensity induced by spatial microsimulation in the context of real individual data. It will be argued in particular that while the first two problems have begun to be addressed in the literature, the third issue is still largely unreported. The paper will thus suggest a solution framework which involves linking spatial microsimulation models with geodemographics and demonstrates the promise of this technique with real numerical experiments.     

An Enzyme Switch Employing Direct Electrochemical Communication between Horseradish Peroxidase and a Poly(aniline) Film

An enzyme switch, or microelectrochemical enzyme transistor, responsive to hydrogen peroxide was made by connecting two carbon band electrodes (～10 μm wide, 4.5 mm long separated by a 20-μm gap) with an anodically grown film of poly(aniline). Horseradish peroxidase (EC 1.11.1.7) was either adsorbed onto the poly(aniline) film or immobilized in an insulating poly(1,2-diaminobenzene) polymer grown electrochemically on top of the poly(aniline) film to complete the device. In the completed device, the conductivity of the poly(aniline) film changes from conducting (between - 0.05 and + 0.3 V vs SCE at pH 5) to insulating (>+0.3 V vs SCE at pH 5) on addition of hydrogen peroxide. The change in conductivity is brought about by oxidation of the poly(aniline) film by direct electrochemical communication between the enzyme and the conducting polymer. This was confirmed by measuring the potential of the poly(aniline) film during switching of the conductivity in the presence of hydrogen peroxide. The devices can be reused by rereducing the poly(aniline) electrochemically to a potential below +0.3 V vs SCE. A blind test showed that the device can be used to determine unknown concentrations of H(2)O(2) in solution and that, when used with hydrogen peroxide concentrations below 0.5 mmol dm(-)(3), the same device maybe reused several times. The possible development of devices of this type for use in applications requiring the measurement of low levels of hydrogen peroxide or horseradish peroxidase is discussed.     

Potential Effect of Cavitation on the Physical Properties of Interesterified Soybean Oil Using High-Intensity Ultrasound: A Long-Term Storage Study

The objective of this research was to evaluate if cavitation events generated during sonication (20 kHz, 216 μm amplitude, 10 s) are responsible for changes in physical properties of a fat with low levels of saturated fatty acids and if these changes are maintained during storage. The fat was crystallized at 24 and 34 °C and stored at 25 °C for up to 24 weeks. An increase in solid fat content and melting enthalpy was observed for sonicated samples crystallized at 34 °C and an increase in elasticity was observed for sonicated samples crystallized at 24 °C (P < 0.05). Hardness increased in sonicated samples crystallized at 24 and 34 °C (P < 0.05) after 60 min of crystallization and after 24 weeks storage. Elasticity of non-sonicated samples crystallized at 24 °C decreased (P < 0.05) after storage at 25 °C for 48 h while it remained constant in sonicated samples. Sonicated samples had more, and smaller crystals compared to the non-sonicated ones. No significant change was observed in physical properties of sonicated samples crystallized at 24 °C and 34 °C during the 24 weeks of storage. Sonication at 24 °C was less efficient at changing the physical properties of the fat compared to 34 °C; however, the number of subharmonic components generated during sonication at these two temperatures was not affected by crystallization temperature. These results suggest that changes in physical properties are associated with secondary effects of sonication such as bubble streamers rather than changes in cluster dynamics.     

Identifying the effect of retail brands on private residential rental prices in Great Britain

Journal of Housing and the Built Environment - This study extends our understanding of the influence of proximity to retail grocery provision on housing rental prices. To achieve this, extensive...     

Indexing the census: a by-product of the simulation of whole populations by means of SAS and SAR data

"Amongst the new output formats adopted for the 1991 [U.K.] census were the Small Area and Local Base Statistics tables and the Samples of Anonymised Records. During an attempt to combine these data sources to estimate whole populations, a need was recognised for a computer algorithm to aggregate SAR data flexibly into LBS and SAS table look-alikes. This paper is a report on progress in the development of such an algorithm, including the concomitant development of a meta-database of census tables and variables required as an input to the algorithm. Out of this work a user-friendly, freely disseminable version of the census meta-database has been created, of interest to all census users."     

A simple and inexpensive microfluidic electrolysis cell

A single channel microfluidic electrolysis cell based on inexpensive materials and fabrication techniques is described. The cell is characterised using the electrochemistry of the Fe(CN)₆³⁻/Fe(CN)₆⁴⁻ couple and its application in electrosynthesis is illustrated using the methoxylation reactions of N-formylpyrrolidine and 4-t-butyltoluene. It is shown that the reactions can be carried out with a good conversion in a single pass. The device, as described, allows the production of several mmol/hour of the methoxylated products.     

Femtosecond Yb:YCOB laser pumped by narrow-stripe laser diode andpassively modelocked using ion implanted saturable-absorber mirror

The authors present, what they believe to be, the first femtosecond Yb:YCOB laser, pumped by a low-power, narrow-stripe laser diode. To facilitate modelocking, high-energy oxygen ion implantation of the saturable absorber is employed. 210 fs pulse generation at 16 mW average output power for 140 mW incident pump power is reported