Anticipatory routing of police helicopters

We have developed a decision support application for the Dutch Aviation Police and Air Support unit for routing their helicopters in anticipation of unknown future incidents. These incidents are not known in advance, yet do require a swift response. A response might include the dispatch of a police helicopter to support the police on the ground. If a helicopter takes too long to arrive at the crime scene, it might be too late to assist. Hence, helicopters have to be proximate when an incident happens to increase the likelihood of being able to support the police on the ground in apprehending suspects. We propose the use of a forecasting technique, followed by a routing heuristic to maximize the number of incidents where a helicopter provides a successful assist. We have implemented these techniques in a decision support application in collaboration with the Dutch Aviation Police and Air Support. Using numerical experiments, we show that our application has the potential to improve the success rate with a factor nine. The Dutch Air Support and Aviation Police are now using the application.     

Mirror or Molder? A Study of Media Coverage,Stock Prices,and Trading Volumes in Germany

This article investigates the short‐term relationship between media coverage, stock prices, and trading volumes of eight listed German companies. A content analysis of news reports about the selected companies and a secondary analysis of the daily changes in closing prices and the trading volumes of these companies were combined in a time‐series design. After ARIMA‐modeling each of them, the results suggest that media coverage rather reflects than shapes the development at stock exchanges from a short‐term perspective (2 months). There were almost no hints for a widespread media effect, that is, an impact on so many investors that it will result in a measurable change in stock prices or trading volumes. Finally, theoretical and methodological consequences for exploring widespread media effects are discussed.     

Agglomeration and productivity: evidence from firm-level data

Do agglomerations stimulate productivity? An extensive literature on agglomeration economies, or urban increasing returns, has analyzed this question with aggregated spatial data. This paper estimates the relationship between agglomeration and productivity at the firm level using static and dynamic models. It makes use of a rich dataset comprising register information on all manufacturing firms in Sweden with 10 or more employees over the period 1997–2004. Three things emerge. First, firms located in larger regions are more productive when controlling for size, human capital, physical capital, ownership structure, import and export, industry classification, and time trend. Second, results from dynamic panel estimations suggests a learning effect in that agglomeration enhances firms’ productivity. Third, the role of agglomeration phenomena does not seem to have a clear coupling to firm size.     

Dynamic prototypicality effects in visual search.

In recent studies, researchers have discovered a larger neural activation for stimuli that are more extreme exemplars of their stimulus class, compared with stimuli that are more prototypical. This has been shown for faces as well as for familiar and novel shape classes. We used a visual search task to look for a behavioral correlate of these findings regarding both simple geometrical shapes and more complex, novel shape classes. The latter stimulus set enabled us to control for the physical properties of the shapes, establishing that the effects are solely due to the positions of the particular stimuli in a particular shape space (i.e., more extreme versus more central in shape space) and not to specific shape features. The results indicate that finding an atypical instance of a shape class among more prototypical ones is easier and faster than the other way around. The prototypical status of a shape in our experiment could change very quickly, that is, within minutes, depending on the subset of shapes that was shown to the participants. Manipulating the degree of familiarity toward the shapes by selectively increasing familiarity for the extreme shapes did not influence our results. In general, we show that the prototypical status of a stimulus in visual search is a highly dynamic property, depending on the distribution of stimuli within a shape space but not on familiarity with the prototype. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Efficiency evaluation for pooling resources in health care

Hospitals traditionally segregate resources into centralized functional departments such as diagnostic departments, ambulatory care centers, and nursing wards. In recent years this organizational model has been challenged by the idea that higher quality of care and efficiency in service delivery can be achieved when services are organized around patient groups. Examples include specialized clinics for breast cancer patients and clinical pathways for diabetes patients. Hospitals are struggling with the question of whether to become more centralized to achieve economies of scale or more decentralized to achieve economies of focus. In this paper we examine service and patient group characteristics to study the conditions where a centralized model is more efficient, and conversely, where a decentralized model is more efficient. This relationship is examined analytically with a queuing model to determine the most influential factors and then with simulation to fine-tune the results. The tradeoffs between economies of scale and economies of focus measured by these models are used to derive general management guidelines.     

Prediction of Transport Properties of Liquid Ammonia and Its Binary Mixture with Methanol by Molecular Simulation

Transport properties of ammonia and of the binary mixture ammonia + methanol are predicted for a broad range of liquid states by molecular dynamics (MD) simulation on the basis of rigid, non-polarizable molecular models of the united-atom type. These models were parameterized in preceding work using only experimental vapor-liquid equilibrium data. The self- and the Maxwell-Stefan (MS) diffusion coefficients as well as the shear viscosity are obtained by equilibrium MD and the Green-Kubo formalism. Non-equilibrium MD is used for the thermal conductivity. The transport properties of liquid ammonia are predicted for temperatures between 223 K and 473 K up to pressures of 200 MPa and are compared to experimental data and correlations thereof. Generally, good agreement is achieved. The predicted self-diffusion coefficient as well as the shear viscosity deviates on average by less than 15 % from the experiment and the thermal conductivity by less than 6 %. Furthermore, the self- and the MS transport diffusion coefficients as well as the shear viscosity of the liquid mixture ammonia + methanol are studied at different compositions and compared to the available experimental data.     

A scanning electron microscopy specimen holder for viewing different angles of a single specimen

The specimen holder for scanning electron microscopy described herein allows a single specimen to be examined in any possible view and significantly improves object illumination. The specimen is glued to a fine pin and flexibly mounted on a double‐sided adhesive conductive pad on a rotatable pivot. A milled pot placed beneath the specimen acts as an electron trap. This provides a homogeneous black image background by minimizing noisy signals from the specimen's surroundings. Microsc. Res. Tech. 73:1073–1076, 2010. © 2010 Wiley‐Liss, Inc.     

The use of interorganisational ICT in United States construction projects

In recent research, the use of ICT applications in real time construction projects have been documented and analysed extensively. However, there is a need for identifying and analysing in-depth the mechanisms influencing the use of interorganisational ICT applications and for solutions to eliminate potential barriers to the successful use of ICT. A model is developed providing insights in these mechanisms. Based on this model and expert interviews in the United States construction industry directions for solutions to barriers to the successful use of interorganisational ICT — document management applications, workflow management applications, and product modelling applications — in construction projects are formulated. These solutions focus on stimulating the personal motivation to use ICT, the external motivation to use this technology, and facilitating conditions in terms of knowledge and skills and acting opportunities to use ICT.