Physical unclonable functions (PUFs) are widely researched security primitive in the digital and analog domain but have yet to be explored for asynchronous circuits. In this paper, we propose novel optimization methods to design a weak Asynchronous RESet (ARES) PUF that exploits random start-up characteristics of Threshold M of N Null Conventional Logic (NCL) gates as a source of entropy. We employ two different methods to design the ARES PUF. The first includes traditional delay matching techniques using linear programming-based optimization, whereas the second one uses the genetic algorithm (GA) with delay matching as a fitness function. Both methodologies are explained with analysis and design specifications required to model NCL TH22 gates to achieve PUF characteristics. Threshold 2 of 2 (TH22) and 4 of 4 (TH44) gates are used as test cases for evaluation and comparison. Simulation results using initial delay matching techniques at 90nm and 65nm technology in HSPICE shows that the proposed ARES PUF has a uniqueness of 49.98% and reliability of 96.53% across VDD variation (±10%) and 93.39% across temperature variation (0°C-80°C). Whereas, the GA method can optimize NCL cells to form a PUF with 49% uniqueness at 65nm with an average reliability of 96.4% across VDD and 93.82% across temperature. Preliminary silicon results for proposed TH22 at TSMC 90nm technology node shows a 34% improvement in uniqueness compared to standard TH22 gate with best-case uniqueness of 53.3% and reliability of 100% respectively across repeated measurements (noise). Unlike standard TH22, standard TH44 performs better with 47.62% best-case uniqueness and 98.1% reliability1.

This paper presents the synergistic use of handheld computers and desktop computers as tools for grade school teachers to record observational data from their classrooms. The system uses handheld devices to tersely log events in situ, and allows later reflection and elaboration through annotation of the logged events on desktop computer. The terse, ephemeral capture of events coupled with post-hoc annotation has been novelly exploited to design a system that supports teachers' development as reflective practitioners and enables richer capture of grade school student behaviour and performance.

Email has come to play a central role in task management, yet email tool features have remained relatively static in recent years, lagging behind users? evolving practices. The Taskmaster system narrows this gap by recasting email as task management and embedding task-centric resources directly in the client. In this paper, we describe the field research that inspired Taskmaster and the principles behind its design. We then describe how user studies conducted with ?live? email data over a two-week period revealed the value of a task-centric approach to email system design and its potential benefits for overloaded users.

In this paper, we describe FLANNEL, an architecture for adding computational capabilities to email. FLANNEL allows email to be modified by an application while in transit between sender and receiver. This modification is done without modification to the endpoints---mail clients---at either end. This paper also describes interaction techniques that we have developed to allow senders of email to quickly and easily select computations to be performed by FLANNEL. Through, our experience, we explain the properties that applications must have in order to be successful in the context of FLANNEL.

Abstract We prove a theorem (1.7) about partial orders which can be viewed as a version of the Barwise compactness theorem which does not mention logic. The Barwise compactness theorem is easily equivalent to 1.7 + “Every Henkin set has a model”. We then make the observation that 1.7 gives us the definability of forcing for quantifier-free sentences in the forcing language and use this to give a direct proof of the truth and definability lemmas of forcing.