Fast electrical lysis of cells for capillary electrophoresis

In the past decade, capillary electrophoresis has demonstrated increasing utility for the quantitative analysis of single cells. New applications for the analysis of dynamic cellular properties demand sampling methods with sufficient temporal resolution to accurately measure these processes. In particular, intracellular signaling pathways involving many enzymes can be modulated on subsecond time scales. We have developed a technique to rapidly lyse an adherent mammalian cell using a single electrical pulse followed by efficient loading of the cellular contents into a capillary. Microfabricated electrodes were designed to create a maximum voltage drop across the flattened cell's plasma membrane at a minimum interelectrode voltage. The influence of the interelectrode distance, pulse duration, and pulse strength on the rate of cell lysis was determined. The ability to rapidly lyse a cell and collect and separate the cellular contents was demonstrated by loading cells with Oregon Green and two isomers of carboxyfluorescein. All three fluorophores were detected with a separation efficiency comparable to that of standards. Parallel comparison of electrical lysis to that produced by a laser-based lysis system revealed that the sampling efficiencies of the two techniques were comparable. Rapid cell lysis by an electrical pulse may increase the application of capillary electrophoresis to the study of cellular dynamics requiring fast sampling times.     

Relations between compliances of inhomogeneities having the same shape but different elastic constants

The contributions of inhomogeneities having the same shape but different elastic constants, to the overall elastic properties are interrelated. The utility of these relations lies, in particular, in the possibility to extend available results for pores or rigid inclusions to inhomogeneities of arbitrary elastic properties. The relations are exact for ellipsoids and approximate for non-ellipsoidal shapes. The constructed approximation also constitutes approximate connection between the first Eshelby’s problem (the eigenstrain problem) and the second one (the inhomogeneity problem), for non-ellipsoidal shapes. It also yields approximate formulas for the contribution of a non-ellipsoidal inhomogeneity to effective elastic properties.     

Evaluation of markov program models in virtual memory systems

A first order Markov model of program behaviour is developed from FORTRAN program instruction data. The program model is evaluated by using it to generate page references for input into a simple virtual memory operating system (VMOS) simulation model. The actual trace data are also used to drive the VMOS model. In both cases the fault probability is obtained for different replacement rules, memory sizes and page sizes. A comparison of fault probabilities is used to determine the effectiveness of the Markov program model.     

Artefacts au cours de la préparation de coupes de grains d'amidon. Etude par microscopie photonique et électronique

Artefacts During the Preparation of Sections of Starch Granules. Studies under Light and Electron Microscope. Dark bands which are usually observed in ultrathin sections of starch granules, „coloured”︁ or not, have been considered by some authors as marking the presence of protidic substances, by others as artefacts of sectioning, on account of the diversity of their shapes and the frequency of their appearance. Examinations under light microscope show that this phenomenon appears effectively, during the sectioning of the inclusion block, when the ultrathin section of starch comes into contact with the surface of water in the collecting tank and then swells. The examination under electron microscope of ultrathin sections shadowed with gold, allows us to show that these dark bands are the consequence of surface folding of the cut starch grains. The measurements of electron density show that there are folds like S or double folds like S, and that electron transmission across the sample follows a logarithmic rule. A discussion leads to think that these artefacts are the consequence of a defective permeation of starch with the inclusion material and the result of starch water affinity. We must definitely leave out that dark bands should be a manifestation of protidic material.     

Microscopic Effects of Ultrasound on the Structure of Potato Starch Preliminary Study

This preliminary study has related the nature of rupture in starch grains, induced by ultrasound, to the ambient atmosphere, the concentration of the suspension, the frequency and the time of irradiation. It has been tentatively concluded that principally mechanical effects have been induced under conditions that would promote vaporous cavitation (280 KHz, 15 W/cm²). In an atmosphere of hydrogen, many deep conical pits are produced. In an atmosphere of air or oxygen, deep pitting is somewhat less pronounced than in hydrogen but injury to other parts of the surface is greater. Virtually no effect is produced in vacuo, and under carbon dioxide the effect is very weak. The extent of damage increases with time of radiation and decreases with increasing concentration of starch in the suspension. It is suggested that damage produced by ultrasound indicates a primarily radial structure of submicroscopic units in the starch grain. Explanations proposed for the effects observed must be tested in further experiments.     

Iterative restoration of MR images corrupted with translational motion

Patient motion during the acquisition of magnetic resonance imaging data causes loss of resolution and ghost repetitions of the moving structures in the reconstructed image. In this paper the motion is modeled as being translational, and it is shown that this causes either the magnitude or the phase of the data to be corrupted, depending upon whether the motion is within or perpendicular to the imaging plane. The problem of restoring the image using only the corrupted data and no knowledge about the motion is addressed. The restoration problem is nonlinear in general, but is linear in two special cases. An iterative algorithm is developed that uses projections onto convex sets for magnitude retrieval and generalized projections for phase retrieval. In both cases constraint sets containing all a priori knowledge are used, and this is shown to be necessary for rapid convergence. The two algorithms may be combined to restore images corrupted by three-dimensional motion. The algorithms were verified using simulated data.     

Utilizing theory of mind for action selection applied in the domain of fighter pilot training

When developing intelligent agents, approaches that allow the anticipation of other agents is of utmost importance. For humans, this has also been shown to be crucial to establish good interactions. In this paper, a design for an agent that is equipped with theory of mind based reasoning capabilities is presented. The approach moves beyond the state of the art from several angles: first, it allows for the expression of certainties with respect to the predicted states of the other agents. Second, it allows the prediction during a substantial number of time steps in the future, thereby utilizing the theory of mind model multiple times. The approach has been applied to the domain of fighter pilots whereby intelligent opponents are developed to facilitate dedicated training for F16 fighter pilots.     

Modelling collective decision making in groups and crowds: Integrating social contagion and interacting emotions, beliefs and intentions

Collective decision making involves on the one hand individual mental states such as beliefs, emotions and intentions, and on the other hand interaction with others with possibly different mental states. Achieving a satisfactory common group decision on which all agree requires that such mental states are adapted to each other by social interaction. Recent developments in social neuroscience have revealed neural mechanisms by which such mutual adaptation can be realised. These mechanisms not only enable intentions to converge to an emerging common decision, but at the same time enable to achieve shared underlying individual beliefs and emotions. This paper presents a computational model for such processes. As an application of the model, an agent-based analysis was made of patterns in crowd behaviour, in particular to simulate a real-life incident that took place on May 4, 2010 in Amsterdam. From available video material and witness reports, useful empirical data were extracted. Similar patterns were achieved in simulations, whereby some of the parameters of the model were tuned to the case addressed, and most parameters were assigned default values. The results show the inclusion of contagion of belief, emotion, and intention states of agents results in better reproduction of the incident than non-inclusion.     

Factors facilitating or impeding older adults’ creative contributions in the collaborative design of a novel DTV-based application

This article describes some of the challenges of supporting older adults’ creative input to the design of an (as yet) undefined digital television application. Focusing on commonly used brainstorming and paper prototyping techniques, constructive insights are gathered from users with limited experience of interactive technology. Encouraging older participants to move beyond what they are familiar with, the research reports on how fragmented conceptual knowledge of familiar technologies can either facilitate or impede the creative development of new ideas. This includes bias or contradictory ideas that can emerge in the elicitation process. As reported, other factors, such as the self-perception of inadequate drawing skills, demonstrate further barriers for some older adults to articulate their visions and aspirations for suitably designed technology.     

Böhler Edelstahl

Böhler Edelstahl produces high performance tool and high speed steels via an optimised powder metallurgy/hot isostatic pressing route, as part of a high value special alloys portfolio.