Efficient computation based on stochastic spikes

The speed and reliability of mammalian perception indicate that cortical computations can rely on very few action potentials per involved neuron. Together with the stochasticity of single-spike events in cortex, this appears to imply that large populations of redundant neurons are needed for rapid computations with action potentials. Here we demonstrate that very fast and precise computations can be realized also in small networks of stochastically spiking neurons. We present a generative network model for which we derive biologically plausible algorithms that perform spike-by-spike updates of the neuron's internal states and adaptation of its synaptic weights from maximizing the likelihood of the observed spike patterns. Paradigmatic computational tasks demonstrate the online performance and learning efficiency of our framework. The potential relevance of our approach as a model for cortical computation is discussed.     

Quality and Reliability Problems from a Consumer's Perspective: an Increasing Problem Overlooked by Businesses?

Currently, many businesses in the consumer electronics industry are facing an increasing number of consumer complaints, despite the application of quality tools that proved to be very powerful in the past. We assessed over 20 new product development projects, to understand the reasons behind the rising number of consumer complaints. We found that businesses are developing more innovative products that are brought to the market faster, with inherently higher uncertainties on the consumer expectations of these products. Current analyses of consumer complaints solely focus on checking if the product is functioning according to the technical specification, and these analyses show a rising number of consumer complaints where no failure could be established. When looking at product quality and reliability from a consumer's perspective, we found that consumers complain not only about technical product failures but also when the product does not satisfy their expectations. In this paper we will take the perspective of the consumer to analyse dissatisfaction with new products from various available sources, which were not set‐up for quality and reliability purposes. We will show that analysing information from these sources gives better information, especially on the non‐technical failures compared with the traditional quality and reliability sources. Copyright © 2006 John Wiley & Sons, Ltd.     

Development of gluten-free fresh egg pasta based on oat and teff flour

Due to increased awareness of consumers about the relationship between food and health as well as the requirements of people following a gluten-free diet, the production of cereal products from raw materials other than wheat is of interest. However, the elimination of the visco-elastic gluten protein represents a technological challenge. During this study, response surface methodology was applied to determine optimal formulations for the production of egg pasta from oat and teff flour. Wheat flour was used as a control. The resulting products were characterised regarding firmness and elasticity, stickiness and cooking loss. The results showed that the mechanical texture of oat and teff pasta was comparable to wheat pasta, however, elasticity was significantly reduced. Compositional analysis was carried out on flour raw materials as well as on the final pasta products, showing that regarding fibre and mineral content, oat and teff samples are nutritionally superior to wheat. In addition, the microstructure was investigated by means of scanning electron microscopy, allowing also the observation of structural changes occurring during cooking. Upon cooking, a distinct outer layer can be observed, resulting from protein denaturation and starch gelatinisation. This structural feature is clearly visible for cooked wheat pasta and but is less apparent for teff and oat pasta.     

High‐Pressure Thermal Sterilization: Food Safety and Food Quality of Baby Food Puree

The benefits that high‐pressure thermal sterilization offers as an emerging technology could be used to produce a better overall food quality. Due to shorter dwell times and lower thermal load applied to the product in comparison to the thermal retorting, lower numbers and quantities of unwanted food processing contaminants (FPCs), for example, furan, acrylamide, HMF, and MCPD‐esters could be formed. Two spore strains were used to test the technique; Geobacillus stearothermophilus and Bacillus amyloliquefaciens, over the temperature range 90 to 121 °C at 600 MPa. The treatments were carried out in baby food puree and ACES‐buffer. The treatments at 90 and 105 °C showed that G. stearothermophilus is more pressure‐sensitive than B. amyloliquefaciens. The formation of FPCs was monitored during the sterilization process and compared to the amounts found in retorted samples of the same food. The amounts of furan could be reduced between 81% to 96% in comparison to retorting for the tested temperature pressure combination even at sterilization conditions of F₀‐value in 7 min.     

Chemical warfare and survival strategies in bacterial range expansions

Dispersal of species is a fundamental ecological process in the evolution and maintenance of biodiversity. Limited control over ecological parameters has hindered progress in understanding of what enables species to colonize new areas, as well as the importance of interspecies interactions. Such control is necessary to construct reliable mathematical models of ecosystems. In our work, we studied dispersal in the context of bacterial range expansions and identified the major determinants of species coexistence for a bacterial model system of three Escherichia coli strains (toxin-producing, sensitive and resistant). Genetic engineering allowed us to tune strain growth rates and to design different ecological scenarios (cyclic and hierarchical). We found that coexistence of all strains depended on three strongly interdependent factors: composition of inoculum, relative strain growth rates and effective toxin range. Robust agreement between our experiments and a thoroughly calibrated computational model enabled us to extrapolate these intricate interdependencies in terms of phenomenological biodiversity laws. Our mathematical analysis also suggested that cyclic dominance between strains is not a prerequisite for coexistence in competitive range expansions. Instead, robust three-strain coexistence required a balance between growth rates and either a reduced initial ratio of the toxin-producing strain, or a sufficiently short toxin range.     

Studying Organizational Creativity as Process: Fluidity or Duality?

This paper contributes to process studies on organizational creativity by developing two competing research agendas. The first perspective, the ‘becoming’ view, depicts creativity as a constant flow of activity that crystallizes every once in a while in unpredictable moments of creativity. The second perspective, the ‘practice’ view, understands creativity as a practised social process, in which structures play the important role of both enabling and constraining individual agents in pursuing creativity as a collective phenomenon. We compare and contrast these two theoretical perspectives, which are based on different process ontologies, and discuss their methodological implications. We argue that the practice perspective offers particular promise, because it allows us to address the important yet paradoxical question of how creativity may be organized and managed.     

Metal Oxide Nanowires for Gas Sensor Applications

We report on the synthesis of SnO₂ and CuO nanowires and their application as gas sensing components. The fabrication of SnO₂ and CuO single nanowire devices by optical and electron beam lithography is described, and sensing performance to the toxic gas carbon monoxide is demonstrated. We briefly present the development of CMOS fabricated micro-hotplates as platforms for gas sensors and show our approach for nanowire implementation. Finally, we demonstrate a fully CMOS integrated CuO multi nanowire device and present our roadmap for a fully integrated multi-parameter smart sensor device which could be implemented as safety feature in smart phones.     

Effect of free water removal from early-age hydrated cement pastes on thermal analysis

In order to follow the progress of cement hydration by analytical techniques, the ongoing hydration reactions must be stopped by complete removal of free water. A comparison between solvent exchange, oven drying and vacuum drying, using thermal analysis, is presented for early-age hydrated cement pastes. Results show that oven drying at 105 °C accelerates hydration, causes dehydration of some hydrated cement phases and favours carbonation. Solvent exchange with ethanol, ether and methanol results in a strong absorption and an incomplete removal of solvents. FT-IR and XRD gave evidence of the formation of carbonate-like phases due to an interaction upon heating, i.e. during thermal analysis, between the strongly absorbed solvents and the cement compounds or hydrates. Vacuum drying reveals reliable results as no interaction products can be formed and the Ca(OH)₂ content, determined by thermal analysis, gives a good approximation of the real amount of Ca(OH)₂.