The challenges of nanostructures for theory

It is tempting to believe that modelling in nanotechnology is much the same as that for conventional solid-state physics. However, important areas of nanotechnology address different systems. The mechanics of DNA (for instance) resembles spaghetti more than silicon, the statistical physics needed is often not carrier statistics, and the role of viscosity (the low Reynolds number limit) is not always the familiar one. The idea of equilibrium may be irrelevant, as the kinetics of nonequilibrium (perhaps quasi-steady state) can be crucial. Even when the issues are limited to nanoscale structures (rather than functions), there is a complex range of ideas. Some features, like elasticity and electrostatic energies, have clear macroscopic analogies, but different questions emerge, such as the accuracy of self-organisation. Others concepts like epitaxy and templating are usually micro- or mesostructural. Some of the ideas, which emerge in modelling for the nanoscale, suggest parallels between molecular motors and recombination enhanced diffusion in semiconductors. (C) 2002 Elsevier Science B.V. All rights reserved

The Non-Ideal Organic Electrochemical Transistors Impedance

Organic electrochemical transistors offer powerful functionalities for biosensors and neuroinspired electronics, with still much to understand on the time dependent behavior of this electrochemical device. Here, we report on distributed element modeling of the impedance of such microfabricated device, systematically performed under a large concentration variation for KCl(aq) and CaCl2(aq). We propose a new model which takes into account three main deviations to ideality, that were systematically observed, caused by both the materials and the device complexity, over large frequency range (1 Hz to 1 MHz). More than introducing more freedom degree, the introduction of these non redundant parameters and the study of their behaviors as function of the electrolyte concentration and applied voltage give a more detailed picture of the OECT working principles. This optimized model can be further useful for improving OECT performances in many applications (e.g. biosensors, neuroinspired devices) and circuit simulations.Comment: Full paper with supporting informatio

TechNews digests: Jan - Mar 2010

TechNews is a technology, news and analysis service aimed at anyone in the education sector keen to stay informed about technology developments, trends and issues. TechNews focuses on emerging technologies and other technology news. TechNews service : digests september 2004 till May 2010 Analysis pieces and News combined publish every 2 to 3 month

Cognitive Machine Individualism in a Symbiotic Cybersecurity Policy Framework for the Preservation of Internet of Things Integrity: A Quantitative Study

This quantitative study examined the complex nature of modern cyber threats to propose the establishment of cyber as an interdisciplinary field of public policy initiated through the creation of a symbiotic cybersecurity policy framework. For the public good (and maintaining ideological balance), there must be recognition that public policies are at a transition point where the digital public square is a tangible reality that is more than a collection of technological widgets. The academic contribution of this research project is the fusion of humanistic principles with Internet of Things (IoT) technologies that alters our perception of the machine from an instrument of human engineering into a thinking peer to elevate cyber from technical esoterism into an interdisciplinary field of public policy. The contribution to the US national cybersecurity policy body of knowledge is a unified policy framework (manifested in the symbiotic cybersecurity policy triad) that could transform cybersecurity policies from network-based to entity-based. A correlation archival data design was used with the frequency of malicious software attacks as the dependent variable and diversity of intrusion techniques as the independent variable for RQ1. For RQ2, the frequency of detection events was the dependent variable and diversity of intrusion techniques was the independent variable. Self-determination Theory is the theoretical framework as the cognitive machine can recognize, self-endorse, and maintain its own identity based on a sense of self-motivation that is progressively shaped by the machine’s ability to learn. The transformation of cyber policies from technical esoterism into an interdisciplinary field of public policy starts with the recognition that the cognitive machine is an independent consumer of, advisor into, and influenced by public policy theories, philosophical constructs, and societal initiatives

Calculating and Aggregating Direct Trust and Reputation in Organic Computing Systems

The growing complexity of current computer systems requires a high amount of administration, which poses an increasingly challenging task for manual administration. The Autonomic and Organic Computing Initiatives have introduced so called self-x properties, including self-configuration, self-optimization, self-healing, and self-protection, to allow administration to become autonomous. Although research in this area revealed promising results, it expects all participants to further the system goal, i.e., their benevolence is assumed. In open systems, where arbitrary participants can join the systems, this benevolence assumption must be dropped, since such a participant may act maliciously and try to exploit the system. This introduces a not yet considered uncertainty, which needs to be addressed. In human society, trust relations are used to lower the uncertainty of transactions with unknown interaction partners. Trust is based on past experiences with someone, as well as recommendations of trusted third parties. In this work trust metrics for direct trust, reputation, confidence, and an aggregation of them are presented. While the presented metrics were primarily designed to improve the self-x properties of OC systems they can also be used by applications in Multi-Agent-Systems to evaluate the behavior of other agents. Direct trust is calculated by the Delayed-Ack metric, that assesses the reliability of nodes in Organic Computing systems. The other metrics are general enough to be used with all kinds of contexts and facets to cover any kind of trust requirements of a system, as long as corresponding direct trust values exist. These metrics include reputation (Neighbor-Trust), confidence, and an aggregation of them. Evaluations based on an Automated Design Space Exploration are conducted to find the best configurations for each metric, especially to identify the importance of direct trust, reputation, and confidence for the total trust value. They illustrate, that reputation, i.e., the recommendations of others, is an important aspect to evaluate the trustworthiness of an interaction partner. In addition, it is shown that a gradual change of priority from reputation to direct trust is preferable instead of a sudden switch when enough confidence in the correctness of ones own experiences is accumulated. All evaluations focus on systems with volatile behavior, i.e., system participants change their behavior over time. In such a system, the ability to adapt fast to behavior changes has turned out to be the most important parameter.Die steigende Komplexität aktueller Systeme benötigt einen hohen Grad an Administration, was eine wachsende Herausforderung für die manuelle Administration darstellt. Die Autonomic- und Organic-Computing Initiativen haben so genannte Selbst-x Eigenschaften vorgestellt, unter anderem Selbst-Konfiguration, Selbst-Optimierung, Selbst-Heilung sowie Selbst-Schutz, die eine autonome Administration erlauben. Obwohl die Forschung in diesem Gebiet erfolgversprechende Ergebnisse geliefert hat, wird von allen Teilnehmern erwartet, dass sie das Systemziel vorantreiben, d.h., ihr Wohlwollen wird vorausgesetzt. In offenen Systemen, in denen beliebige Teilnehmer dem System beitreten können, muss diese Wohlverhaltensannahme fallen gelassen werden, da solche Teilnehmer bösartig handeln und versuchen können, das System auszunutzen. In einer menschlichen Gesellschaft werden Vertrauensbeziehungen dazu benutzt, die Unsicherheit von Transaktionen mit unbekannten Interaktionspartnern zu mindern. Vertrauen basiert auf den bisherigen Erfahrungen mit Jemandem und auf Empfehlungen von Dritten. In dieser Arbeit werden Trust-Metriken für direkten Trust, Reputation, Konfidenz und deren Aggregation vorgestellt. Obwohl die vorgestellten Metriken hauptsächlich dafür entworfen wurden, die Selbst-x Eigenschaften von Organic-Computing Systemen zu verbessern, können sie ebenso von Applikationen in Multi-Agenten-Systemen benutzt werden, um das Verhalten anderer Agenten einschätzen zu können. Direkter Trust wird durch die Delayed-Ack Metrik berechnet, welche die Zuverlässigkeit von Knoten in Organic-Computing Systemen einschätzt. Die anderen Metriken sind allgemein genug gehalten, um in jedem Kontext und jeder Facette benutzt werden zu können, in dem ein System operiert, solange ein Trust-Wert für direkten Trust existiert. Diese Metriken beinhalten Reputation (Neighbor-Trust), Konfidenz und die Aggregation dieser. Es werden Evaluationen basierend auf einer automatischen Design Space Exploration durchgeführt, um die beste Konfiguration für jede Metrik zu finden, um dabei speziell die Wichtigkeit von direktem Trust, Reputation und Konfidenz auf den gesamten Trust-Wert zu identifizieren. Sie veranschaulichen, dass Reputation, d.h. die Vorschläge Dritter, ein wichtiger Aspekt ist, um die Vertrauenswürdigkeit eines Interaktionspartners einschätzen zu können. Zusätzlich zeigen sie, dass ein gradueller Wechsel von Reputation zu eigenen Erfahrungen einem plötzlichen Wechsel vorzuziehen ist, wenn genug Zuversicht auf die Korrektheit der eigenen Erfahrungen vorhanden ist. Alle Auswertungen befassen sich mit Systemen mit unbeständigem Verhalten, d.h. Systemteilnehmer ändern ihr Verhalten über die Zeit. In solch einem System hat sich herausgestellt, dass die Fähigkeit, sich schnell an Verhaltensänderungen anpassen zu können, der wichtigste Faktor ist