D’Agents: Security in a Multiple-Language, Mobile-Agent System

Abstract. Mobile-agent systems must address three security issues: protecting an individual machine, protecting a group of machines, and protecting an agent. In this chapter, we discuss these three issues in the context of D’Agents, a mobile-agent system whose agents can be written in Tcl, Java and Scheme. (D’Agents was formerly known as Agent Tcl.) First we discuss mechanisms existing in D’Agents for protecting an individual machine: (1) cryptographic authentication of the agent’s owner, (2) resource managers that make policy decisions based on the owner’s identity, and (3) secure execution environments for each language that enforce the decisions of the resource managers. Then we discuss our planned market-based approach for protecting machine groups. Finally we consider several (partial) solutions for protecting an agent from a malicious machine.

An Electrochemical Study of Frustrated Lewis Pairs: A Metal-free Route to Hydrogen Oxidation

[Image: see text] Frustrated Lewis pairs have found many applications in the heterolytic activation of H(2) and subsequent hydrogenation of small molecules through delivery of the resulting proton and hydride equivalents. Herein, we describe how H(2) can be preactivated using classical frustrated Lewis pair chemistry and combined with in situ nonaqueous electrochemical oxidation of the resulting borohydride. Our approach allows hydrogen to be cleanly converted into two protons and two electrons in situ, and reduces the potential (the required energetic driving force) for nonaqueous H(2) oxidation by 610 mV (117.7 kJ mol(–1)). This significant energy reduction opens routes to the development of nonaqueous hydrogen energy technology

Mechanical tuning of the evaporation rate of liquid on crossed fibers

We investigate experimentally the drying of a small volume of perfectly wetting liquid on two crossed fibers. We characterize the drying dynamics for the three liquid morphologies that are encountered in this geometry: drop, column and a mixed morphology, in which a drop and a column coexist. For each morphology, we rationalize our findings with theoretical models that capture the drying kinetics. We find that the evaporation rate depends significantly on the liquid morphology and that the drying of liquid column is faster than the evaporation of the drop and the mixed morphology for a given liquid volume. Finally, we illustrate that shearing a network of fibers reduces the angle between them, changes the morphology towards the column state, and so enhances the drying rate of a volatile liquid deposited on it

Alzheimer\u27s, angiotensin IV and an aminopeptidase

The angiotensin AT4 receptor was originally defined as the specific, high affinity binding site for the hexapeptide angiotensin IV (Ang IV). Subsequently, the peptide LVV-hemorphin 7 was also demonstrated to be a bioactive ligand of the AT4 receptor. Central administration of Ang IV or LVV-hemorphin 7 (LVV-H7) markedly enhances learning and memory in normal rodents and reverse memory deficits observed in animal models of amnesia. The high affinity binding site has a broad distribution in the brain including areas such as the hippocmapus that are involved in memory processing. The high affinity Ang IV binding site (AT4 receptor) has been identified as the transmembrane enzyme, insulin-regulated membrane aminopeptidase (IRAP). Insulin-regulated aminopeptidase is a type II integral membrane spanning protein belonging to the M1 family of aminopeptidases and in insulin-responsive cells colocalizes with GLUT4 in specific intra-cellular vesicles. Both Ang IV and LVV-H7 are competitive inhibitors of IRAP catalytic activity and are not substrates of the enzyme.<br /

The relation of steady evaporating drops fed by an influx and freely evaporating drops

We discuss a thin film evolution equation for a wetting evaporating liquid on a smooth solid substrate. The model is valid for slowly evaporating small sessile droplets when thermal effects are insignificant, while wettability and capillarity play a major role. The model is first employed to study steady evaporating drops that are fed locally through the substrate. An asymptotic analysis focuses on the precursor film and the transition region towards the bulk drop and a numerical continuation of steady drops determines their fully non-linear profiles. Following this, we study the time evolution of freely evaporating drops without influx for several initial drop shapes. As a result we find that drops initially spread if their initial contact angle is larger than the apparent contact angle of large steady evaporating drops with influx. Otherwise they recede right from the beginning

In the Supreme Court of the United States Barbara Grutter, Petitioner, v. Lee Bollinger, et al., Respondents. On Writ of Certiorari to the United States Court of Appeals for the Sixth Circuit

Brief of the University of Michigan Asian Pacific American Law Students Association, the University of Michigan Black Law Students\u27 Alliance, the University of Michigan Latino Law Students Association, and the University of Michigan Native American Law Students Association as Amici Curiae in Support of Respondent

In the Supreme Court of the United States Barbara Grutter, Petitioner, v. Lee Bollinger, et al., Respondents. On Writ of Certiorari to the United States Court of Appeals for the Sixth Circuit

Brief of the University of Michigan Asian Pacific American Law Students Association, the University of Michigan Black Law Students\u27 Alliance, the University of Michigan Latino Law Students Association, and the University of Michigan Native American Law Students Association as Amici Curiae in Support of Respondent

Modification of glassy carbon electrodes by 4-chloromethylphenyl units and d-glucosaminic acid

The present work is dealing with the attachment of d-glucosaminic acid (D-GA) on glassy carbon electrode by two different methods. Firstly, the electrode was modified by chloromethylphenyl groups by reduction of 4-chloromethylphenyldiazonium cations followed by the nucleophilic substitution of the chlorine by the amine functionality of D-GA and secondly by the direct immobilization of the amine terminated molecule. The generality of the nucleophilic substitution reaction and the direct immobilization of an amine were also demonstrated with reactants bearing an electroactive ferrocene moiety; 4-nitrophenylferrocene (NFc) and 4-ferrocenylaniline (FcA). The surfaces modified with FcA and NFc were investigated by cyclic voltammetry, and the D-GA modified electrodes were characterized by X-ray photoelectron spectroscopy. A preliminary evaluation of the efficiency of these surface modifiers to prevent protein adsorption was realized by scanning electron microscopy

Determination of Bond Dissociation Enthalpies in Solution by Photoacoustic Calorimetry

NRC publication: Ye

Electroluminescence stabilization of nanocrystalline porous silicon diodes

NRC publication: Ye