University of Waterloo

About: University of Waterloo is a education organization based out in Waterloo, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 36093 authors who have published 93906 publications receiving 2948139 citations. The organization is also known as: UW & uwaterloo.

Fast Multiplication on Elliptic Curves over GF(2m) without Precomputation

Abstract: This paper describes an algorithm for computing elliptic scalar multiplications on non-supersingular elliptic curves defined over GF(2m). The algorithm is an optimized version of a method described in [1], which is based on Montgomery's method [8]. Our algorithm is easy to implement in both hardware and software, works for any elliptic curve over GF(2m), requires no precomputed multiples of a point, and is faster on average than the addition-subtraction method described in draft standard IEEE P1363. In addition, the method requires less memory than projective schemes and the amount of computation needed for a scalar multiplication is fixed for all multipliers of the same binary length. Therefore, the improved method possesses many desirable features for implementing elliptic curves in restricted environments.

A Provably Secure True Random Number Generator with Built-In Tolerance to Active Attacks

Abstract: This paper is a contribution to the theory of true random number generators based on sampling phase jitter in oscillator rings. After discussing several misconceptions and apparently insurmountable obstacles, we propose a general model which, under mild assumptions, will generate provably random bits with some tolerance to adversarial manipulation and running in the megabit-per-second range. A key idea throughout the paper is the fill rate, which measures the fraction of the time domain in which the analog output signal is arguably random. Our study shows that an exponential increase in the number of oscillators is required to obtain a constant factor improvement in the fill rate. Yet, we overcome this problem by introducing a postprocessing step which consists of an application of an appropriate resilient function. These allow the designer to extract random samples only from a signal with only moderate fill rate and, therefore, many fewer oscillators than in other designs. Last, we develop fault-attack models and we employ the properties of resilient functions to withstand such attacks. All of our analysis is based on rigorous methods, enabling us to develop a framework in which we accurately quantify the performance and the degree of resilience of the design

Axonal guidance during development of the great cerebral commissures: Descriptive and experimental studies, in vivo, on the role of preformed glial pathways

Abstract: Do structures exist within the embryonic central nervous system that guide axons across the midline during development of the great cerebral commissures (corpus callosum, anterior commissure)? With the use of serial section and reconstructive computer graphic techniques we have found that during normal ontogeny of the mouse forebrain and before the arrival of the pioneer fibers of the corpus callosum at the midline, a population of primitive glial cells migrates medially (through the fused walls of the dorsal septum) from the ependymal zones of each hemisphere. At the midline, and well rostral to the lamina terminalis, these cells unite to form a bridgelike structure or "sling" suspended below the longitudinal cerebral fissure. The first callosal axons grow along the surface of this cellular bridge as they travel toward the contralateral side of the brain. The "sling" disappears neonatally. The fibers of the anterior commissure grow within the lamina terminalis along a different type of preformed glial structure. Movement of these axons occurs through an aligned system of glial processes separated by wide extracellular spaces. Do these transient glial tissues actually provide guidance cues to the commissural axons? Analyses of three situations in which the glial "sling" is genetically or surgically impaired or nonexistent indicate that this structure does, indeed, play an essential role in the development of the corpus callosum. We have analyzed (1) the embryonic stages of a congenitally acallosal mouse mutant (strain BALB/cCF), (2) several pouch stages of a primitive acallosal marsupial, Didelphys virginiana (opossum), and (3) animals in which the "sling" had been lesioned surgically through the uterine wall in the normal embryo (strain C57BL/6J). In the acallosal mouse mutant fusion of the septal midline is delayed by about 72 hours and the "sling" does not form. Although the would-be callosal axons approach the midline on schedule, they do not cross. Instead, the callosal fibers whirl into a pair of large neuromas adjacent to the longitudinal fissure. Similarly, in the opossum, fusion of the medial septal walls and formation of the glial "sling" are also lacking. However, in this species, instead of traveling dorsally, the "callosal" axons turn ventrally and pass contralaterally by way of the anterior commissure pathway. Surgical disunion of the glial "sling" also resulted in acallosal individuals. The callosal pathology in these affected animals mimicked exactly that of the genetically lesioned mutant. Our observations suggest that many different types of oriented glial tissues exist within the embryonic neural anlage. We propose that such tissues have the ability to influence the directionality of axonal movements and, thereby, play a crucial role in establishing orderly fiber projections within the developing central nervous system.

Governance for sustainable development: moving from theory to practice

Abstract: In this paper we examine and elaborate on the central elements of sustainable development and governance, considering their interrelations as they have emerged from the core themes in sustainable development discourses over the past decade and a half. We argue that sustainability is best viewed as a socially instituted process of adaptive change in which innovation is a necessary element. We discuss four key elements of governance for sustainability, which are integrated into the concept of transition management. The result is a conceptual framework for policy-making and action-taking aimed at progress towards sustainability.

Capacity Bounds for the Gaussian Interference Channel

Abstract: The capacity region of the two-user Gaussian interference channel (IC) is studied. Three classes of channels are considered: weak, one-sided, and mixed Gaussian ICs. For the weak Gaussian IC, a new outer bound on the capacity region is obtained that outperforms previously known outer bounds. The sum capacity for a certain range of channel parameters is derived. For this range, it is proved that using Gaussian codebooks and treating interference as noise are optimal. It is shown that when Gaussian codebooks are used, the full Han-Kobayashi achievable rate region can be obtained by using the naive Han-Kobayashi achievable scheme over three frequency bands (equivalently, three subspaces). For the one-sided Gaussian IC, an alternative proof for the Sato's outer bound is presented. We derive the full Han-Kobayashi achievable rate region when Gaussian codebooks are utilized. For the mixed Gaussian IC, a new outer bound is obtained that outperforms previously known outer bounds. For this case, the sum capacity for the entire range of channel parameters is derived. It is proved that the full Han-Kobayashi achievable rate region using Gaussian codebooks is equivalent to that of the one-sided Gaussian IC for a particular range of channel parameters.