Island formation without attractive interactions

We show that adsorbates on surfaces can form islands even if there are no attractive interactions. Instead strong repulsion between adsorbates at short distances can lead to islands, because such islands increase the entropy of the adsorbates that are not part of the islands. We suggest that this mechanism cause the observed island formation in O/Pt(111), but it may be important for many other systems as well.Comment: 11 pages, 4 figure

Television broadcast satellite study research and technology implications report

Feasibility of future television broadcasting satellite

Ordering dominant markers in F2 populations

Ordering dominant markers in F2 populations is considered a difficult problem. The difficulties arise from the fact that recombinations cannot be observed directly from the data. In general, the multi-point maximum likelihood would be the appropriate criterion for ordering markers. This criterion takes into account all available information present in marker data. However, calculation of multi-point maximum likelihoods is very time-demanding, especially if the number of markers is large. In this paper, ordering markers by minimising the number of recombinations between adjacent markers is used as a simple alternative to multi-point maximum likelihood. Contrary to multi-point maximum likelihood, this method does not involve any probability assumptions about the occurrence of recombination events. Simulated data indicate that the minimum number of recombinations between adjacent markers is approximately a linear function of the map length obtained by multi-point maximum likelihood. As a consequence, it will lead to more or less the same optimum marker orders. Optimisation of marker orders with regard to the number of recombinations between adjacent markers is carried out by a modified form of simulated annealing. The reliability of the resulting marker orders is studied by generating marker orders that are plausible with the data using a Metropolis algorith

Distributed debugging and tumult

A description is given of Tumult (Twente university multicomputer) and its operating system, along with considerations about parallel debugging, examples of parallel debuggers, and the proposed debugger for Tumult. Problems related to debugging distributed systems and solutions found in other distributed debuggers are discussed. The following are the main features of the debugger: it is event based, using a monitor for intercepting these events; record and reply are the main debugging techniques; preprocessing of events is done by programmable filters; the user interface is graphical, using grouping as the main abstraction mechanism. Parts of the debugger, as well as initial versions of the global and local event managers, have been implemented. A slow serial link between the front-end processor and the Tumult system has been replaced by a fast SCSI communication link. The user interface is partly textual, partly graphical. The languages used to implement the debugger are Modula-2 and C. The X Window System and OSF/Motif are used for the graphical user interfac

Materials analysis of fluorocarbon films for MEMS applications

In this paper the results of the materials analysis of fluorocarbon (FC) films are presented. The properties of the fluorocarbon films are comparable to those of polytetrafluoroethylene (PTFE), better known under the trademarks such as teflon and fluon. The properties of PTFE are desirable for MEMS applications and enable new designs, new applications and new technological processing routes for microsystems. Therefore, FC films have a tremendous potential for MEMS applications. Furthermore, FC films can easily be deposited via spin coating, e-beam evaporation, in conventional reactive ion etchers and in plasma-enhanced deposition chambers using a carbonhydrotrifluoride plasma facilitating the use of the films for micro electro-mechanical structures. The films deposited in a reactive ion etcher are extremely chemical resistant. The X-ray photoelectron spectroscopy (XPS) analyses results are presente

Real Time in a Real Operating System

this paper, be stamped with ecclesiastical authorit