Deborah Olsen Public Service Scholarship Essay

In this essay, Maura Hand reflects on the ten weeks she spent interning with the State Department\u27s Office of Foreign Missions (OFM) in San Francisco, California

First Semester Reflection

Postcard from Maura Hand, during the Linfield College Semester Abroad Program at the Universidad de Alicante in Spai

Conditions for Existence of Dual Certificates in Rank-One Semidefinite Problems

Several signal recovery tasks can be relaxed into semidefinite programs with rank-one minimizers. A common technique for proving these programs succeed is to construct a dual certificate. Unfortunately, dual certificates may not exist under some formulations of semidefinite programs. In order to put problems into a form where dual certificate arguments are possible, it is important to develop conditions under which the certificates exist. In this paper, we provide an example where dual certificates do not exist. We then present a completeness condition under which they are guaranteed to exist. For programs that do not satisfy the completeness condition, we present a completion process which produces an equivalent program that does satisfy the condition. The important message of this paper is that dual certificates may not exist for semidefinite programs that involve orthogonal measurements with respect to positive-semidefinite matrices. Such measurements can interact with the positive-semidefinite constraint in a way that implies additional linear measurements. If these additional measurements are not included in the problem formulation, then dual certificates may fail to exist. As an illustration, we present a semidefinite relaxation for the task of finding the sparsest element in a subspace. One formulation of this program does not admit dual certificates. The completion process produces an equivalent formulation which does admit dual certificates

Temperature compensated digital inertial sensor

A circuit which maintains the inertial element of a gyroscope or accelerometer at a constant position by delivering pulses to a rebalancing motor is discussed. The circuit compensates for temperature changes by using a temperature sensor that varies the threshold of inertial element movement required to generate a rebalance pulse which reacts to changes in viscosity of the flotation fluid. The output of the temperature sensor also varies the output level of the current source to compensate for changes in the strength of the magnets of the rebalancing motor. The sensor also provides a small signal to the rebalance motor to provide a temperature dependent compensation for fixed drift or fixed bias

Andrew Silke, et al., (edited by Andrew Silke). The psychology of counter-terrorism. Routledge: Oxon UK, 2011. pp. 202. £21.98. ISBN: 978-0-415-55840-2 [Book review]

Reviewed by Robert W. Hand, University of Aberdeen.Publisher PD

Rejoinder: Classifier Technology and the Illusion of Progress

Rejoinder: Classifier Technology and the Illusion of Progress [math.ST/0606441]Comment: Published at http://dx.doi.org/10.1214/088342306000000079 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org