Showing papers by "Emmanuel Dubois published in 2000"

Kinetics of scanned probe oxidation: Space-charge limited growth

Abstract: This article proposes an enhanced oxidation model for scanning probe microscope (SPM) nanolithography that reproduces the power-of-time law reported for tip-induced anodic oxidation. It is shown that the space charge resulting from nonstoichiometric states strongly limits the oxidation rate. The direct relationship between the oxide thickness and time is provided by integration of the oxide rate equation. Measurements on SPM-induced oxides generated on a titanium surface are compared to theory. The predominant role of the space charge is corroborated by electrical measurements on oxide barriers that exhibit current fluctuations due to Coulombic effects.

A dimension space for the design of interactive systems within their physical environments

Abstract: This paper introduces a Dimension Space describing the entities making up richly interactive systems. The Dimension Space is intended to help designers understand both the physical and virtual entities from which their systems are built, and the tradeoffs involved in both the design of the entities themselves and of the combination of these entities in a physical space. Entities are described from the point of view of a person carrying out a task at a particular time, in terms of their attention received, role, manifestation, input and output capacity and informational density. The Dimension Space is applied to two new systems developed at Grenoble, exposing design tradeoffs and design rules for richly interactive systems.

Augmented reality: which augmentation for which reality?

Abstract: In this paper, we first present a brief review of approaches used for studying and designing Augmented Reality (AR) systems. The variety of approaches and definitions in AR requires classification. We define two intrinsic characteristics of AR systems, task focus and nature of augmentation. Based on these two characteristics, we identify four classes of AR systems. In addition our OP-a-S notation provides a complementary characterization method based on interaction. Using OP-a-S, an AR system is modeled as a set of components that communicate with each other. One crucial type of OP-a-S component is the Adapter that establishes a bridge between the real world and the virtual world. By defining a classification scheme, we aim at providing a better understanding of the paradigm of AR and at laying the foundations of future design principles according to the class of systems.

Computer-Guided Pericardiocentesis: Experimental Results and Clinical Perspectives

Abstract: Percutaneous pericardial puncture is a relatively safe and effective technique in case of large pericardial effusions when practiced under echographic or radiological control. The goal of our project is to improve the performance of this technique, mainly in case of smaller and loculated effusions using an accurate guidance towards a preplanned target, based on a model of the pericardial effusion. This paper presents preclinical results of this new computer-assisted technique used to reach the pericardial cavity. The procedure is divided into 3 steps: 1. acquisition of ultrasound data, using an echocardiographic device connected to a 3-D localizer and to a computer, 2. modeling procedure to define the optimal strategy taking into account the mobility of organs on a digital model, 3. guided puncture with a localized needle to reach the predefined target using a passive guidance system. After validation on a dynamic phantom and a feasibility study on dogs, an accuracy and reliability analysis protocol was realized on pigs with experimental pericardial effusion. Feasibility of the technique is demonstrated on animal study with an accuracy of at least 2.5 mm. Further clinical investigation is in progress using a more ergonomic and less cumbersome system. This study demonstrates the feasibility of computer-assisted pericardiocentesis. Beyond the simple improvement of the current technique, this could be a new way to reach the heart or a new tool for percutaneous access and image-guided puncture of soft tissues.