Extractors are Boolean functions that allow, in some precise sense, extraction of randomness from somewhat random distributions, using only a small amount of truly random bits. Extractors, and the closely related ``dispersers,'' exhibit some of the most ``random-like'' properties of explicitly constructed combinatorial structures. In this paper we do two things. First, we survey extractors and ...

Patients with infarctions in the territory of the right middle cerebral artery (RMCA) sometimes present with an agitated confusional state. We reviewed clinical data on 46 patients with RMCA infarcts and compared neurologic findings in patients with and without agitated confusion. Neither of the two patients presenting with agitated confusion showed obvious localizing neurologic signs; subtle m...

OBJECTIVE To monitor daily shift-by-shift changes in agitated behaviour during adult brain injury rehabilitation. DESIGN A prospective, descriptive study. METHODS Eight participants were monitored daily for up to 28 days. The Agitated Behaviour Scale (ABS) evaluated behaviour during three nursing shifts (morning, afternoon, night). Severity of agitation, peak intensity and concomitant behav...

We give the first construction of a family of quantum-proof extractors that has optimal seed length dependence O(log(n/ǫ)) on the input length n and error ǫ. Our extractors support any min-entropy k = Ω(log n+ log(1/ǫ)) and extract m = (1− α)k bits that are ǫ-close to uniform, for any desired constant α > 0. Previous constructions had a quadratically worse seed length or were restricted to very...

Since its introduction by Nisan and Zuckerman (STOC ‘93) nearly a decade ago, the notion of a randomness extractor has proven to be a fundamental and powerful one. Extractors and their variants have found widespread application in a variety of areas, including pseudorandomness and derandomization, combinatorics, cryptography, data structures, and computational complexity. Equally striking has b...

Initiative: The Tygerberg Children's Hospital and Rotary Telemedicine Project in South Africa links specialists from Tygerberg Hospital to doctors at regional community or "district" hospitals to improve healthcare in rural areas. The initiative has assembled its own telemedicine system using off-the-shelf computer equipment and software that is more affordable than commercial telemedicine syst...