Ion etching of ultranarrow structures

We describe the use of Polymethylmethacrylate as both electron beam sensitive resist and ion etch mask for high-resolution pattern transfer. By using high-resolution electron beam lithography, chemically assisted ion beam etching, and in-situ metallization, we have fabricated ultra-narrow gates with lateral dimensions below 20 nm, spaced with < 50 nm pitch on high mobility 2D electron gas material. This technique, which is thought to provide extremely small lateral electron depletion lengths and well defined confienement potentials, allows us to produce new and more complicated structures for the study of quantum transport

Pre-processing for Triangulation of Probabilistic Networks

The currently most efficient algorithm for inference with a probabilistic network builds upon a triangulation of a network's graph. In this paper, we show that pre-processing can help in finding good triangulations forprobabilistic networks, that is, triangulations with a minimal maximum clique size. We provide a set of rules for stepwise reducing a graph, without losing optimality. This reduction allows us to solve the triangulation problem on a smaller graph. From the smaller graph's triangulation, a triangulation of the original graph is obtained by reversing the reduction steps. Our experimental results show that the graphs of some well-known real-life probabilistic networks can be triangulated optimally just by preprocessing; for other networks, huge reductions in their graph's size are obtained.Comment: Appears in Proceedings of the Seventeenth Conference on Uncertainty in Artificial Intelligence (UAI2001

Microfabrication below 10 nm

We describe a new electron beam lithography method for producing structures with lateral sizes smaller than the incident beam diameter. These patterns are transferred into GaAs/AlGaAs, InGaAs/GaAs and InGaAs/InP quantum well heterostructures using chemically assisted ion beam etching, thereby forming uniform arrays of pillars with lateral dimensions at or below 10 nm. To correlate the sizes of such structures with our exposure and development conditions, reflection electron microscopy observations are used

Ion etching of ultranarrow structures

We describe the use of Polymethylmethacrylate as both electron beam sensitive resist and ion etch mask for high-resolution pattern transfer. By using high-resolution electron beam lithography, chemically assisted ion beam etching, and in-situ metallization, we have fabricated ultra-narrow gates with lateral dimensions below 20 nm, spaced with < 50 nm pitch on high mobility 2D electron gas material. This technique, which is thought to provide extremely small lateral electron depletion lengths and well defined confienement potentials, allows us to produce new and more complicated structures for the study of quantum transport

A simulation model shows how individual differences affect major life decisions

Individuals are faced with a number of major decisions throughout their lives, including the choice of a suitable education, career, and life partner. Making such ‘major life decisions’ is challenging, as is evidenced by substantial rates of divorce and drop-out from higher education. Although poor major life decisions can lead to considerable costs for both individuals and society, little is known about how people make these decisions. This is because major life decisions are not simple short-term weighings of options – they are strongly intertwined with identity development. Here, we present a simulation model of major life decisions that integrates the short-term perspective of decision science with the long-term perspective of identity theory. We model major life decisions as a process comprising many explorations of available options, resulting in changing commitments, and eventually leading to a decision. Using our model, we run a large-scale in silico experiment, systematically simulating how three key individual characteristics affect the choice process and the quality of the decision: (1) exploration tendency (broad vs in-depth), (2) accuracy in assessing how well options fit, and (3) selectiveness. We identify the types of individuals who are at risk of exhibiting ‘maladaptive’ decision dynamics, including ruminative exploration and rash decision making, and conclude that these features often, but not always, lead to bad decisions. Our simulation results generate concrete predictions that can be empirically tested and may eventually result in individually tailored tools to aid individuals in making major life decisions

Epidemiological and economic effects of Salmonella control in the pork supply chain

In this paper a salmonella simulation model for the pork production chain is presented to evaluate the epidemiological and economic effects of hygiene measures and price differentiation on Salmonella. Results indicate that the farm stages in the chain are the most important stages to achieve reduction of Salmonella in pork. To reach an acceptable overall level of Salmonella however, every stage has to contribute. With a new system of price differentiation between infected and Salmonella free piglets and pork, the stages can be motivated to take measures for reduction and control of Salmonella

Geïntegreerde bestrijding van trips en weekhuidmijten

Omdat meer kennis over natuurlijke bestrijders in zomerbloemen gewenst is, hebben de projectpartners een vijftal bijeenkomsten gehouden. Voor deze bijeenkomsten zijn de telers van zomerbloemen uitgenodigd. De bijeenkomsten werden begeleid door LTO Groeiservice, FytoConsult en DLV Plant. Naast de bijeenkomsten is onderzoek gedaan in Delphinium en Alchemilla naar de aanwezigheid en vestiging van roofmijten. In Delphinium komen weekhuidmijten voor en in Alchemilla komt trips voor als plaag. Spint kan eveneens in deze gewassen optreden. In beide gewassen werden drie soorten roofmijten geïntroduceerd: Neoseiulus alpinus, Neoseiulus reductus en Amblyseisus montdorensis. In Delphinium werden tijdens de waarnemingen geen weekhuidmijten gevonden en in Alchemilla was trips schaars. Neoseiulus reductus werd goed terug gevonden in Delphinium, in tegenstelling tot de andere soorten roofmijten. In Alchemilla werden alle drie de soorten roofmijten terug gevonden. Voorlopig lijkt Neoseiulus alpinus in het voordeel in Alchemilla, gevolgd door Neoseiulus reductus. Om hieromtrent duidelijkheid te krijgen en ook om een effect aan te tonen van de roofmijten op de plagen zijn meer waarnemingen noodzakelijk

The Landscape of Identity Model:An Integration of Qualitative and Quantitative Aspects of Identity Development

The landscape of identity model views identity as a constellation of commitments with different levels of strength and integration, showing how this constellation emerges from everyday life experiences. Drawing on key principles from the complex dynamic systems approach, our model further describes this conceptualization, as well as the mechanisms underlying the development of an identity landscape. We show that the model solves current conceptual issues within identity theory, specifies how Marcia’s four identity statuses can be viewed as particular types of identity landscapes, and helps to further develop the identity field by generating predictions regarding how individuals with different types of identity landscapes would respond to major life events

Are transport anomalies in "electron waveguides" classical?

We test the implicit prediction of a recent classical model that transport anomalies in ballistic multiprobe conductors—the last plateau, quenching, and the negative bend resistance—should scale with Fermi momentum, pF. Data from junctions defined by adiabatic lateral potentials (having corners with radii of curvature rJ>ħ/pF) qualitatively scale classically; departures observed are attributed to momentum-memory loss from random scattering. With more abrupt (square-cornered) junctions, however, nonclassical pF dependence emerges