An Image-Denoising Framework Fit for Quantum Annealing via QUBO and Restricted Boltzmann Machines

We investigate a framework for binary image denoising via restricted Boltzmann machines (RBMs) that introduces a denoising objective in quadratic unconstrained binary optimization (QUBO) form and is well-suited for quantum annealing. The denoising objective is attained by balancing the distribution learned by a trained RBM with a penalty term for derivations from the noisy image. We derive the statistically optimal choice of the penalty parameter assuming the target distribution has been well-approximated, and further suggest an empirically supported modification to make the method robust to that idealistic assumption. We also show under additional assumptions that the denoised images attained by our method are, in expectation, strictly closer to the noise-free images than the noisy images are. While we frame the model as an image denoising model, it can be applied to any binary data. As the QUBO formulation is well-suited for implementation on quantum annealers, we test the model on a D-Wave Advantage machine, and also test on data too large for current quantum annealers by approximating QUBO solutions through classical heuristics.Comment: 13 pages, 6 figure

The Meeting of Two Cultures: Public Broadcasting on the Threshold of the Digital Age

Provides a summary of discussions held in November 2007 on "Public Broadcasting: The Digital Challenge" among representatives of foundations, public broadcasting corporations and academia. Includes essays on visions for the future of public media

Mark Philp’s notes on the form of knowledge In social work revisited

In social work literature some papers might matter more than others. We assume this might be the case with ‘Notes on the form of knowledge in Social Work’, written by Mark Philp. Even though it was written in 1979, this paper recurrently keeps appearing on and off through writings and footnotes of many scholars in social work and beyond. In brief, Philp might have been pioneering discours analysis on social work literature and practices and suggests there is an underlying constitution of everything that is said and done in social work. This constitution he argues, creates knowledge in social work but also limits social worker to this very knowledge. His analysis draws on Marxist, Foucauldian theories and is utterly ‘historical’ as social work knowledge “is created by historically located shifts in discursive relations“ (Philp, 1979: 103). However, there might be more continuity, as he positions social work historically as mediator between objectified individuals and subjectivity. A stance, which we assume, might still be acknowledged in social work today. In this respect we wondered how scholars in social work today would read and comprehend this seminal paper. What aspects of Philps’ hypothesis, analysis and arguments would they find relevant for social work analysis today and why? In what way might his ‘notes’ enable us to challenge social works knowledge base and positioning? Our analysis is based on two distinct research methods. Firstly, we read through some of his references in order to get more familiar with his thoughts, sources and time. Secondly, we held two discussion panels: one in Antwerp (B) and one held in Ghent (B). Participants, 16 in sum, were selected based on their contribution to social work practice, social work education or research. They have scholarly backgrounds in social work, philosophy, criminology, history, pedagogy and psychology. In our presentation and drawing on Philps' analysis and the comments of Belgian scholars, we will focus on the question if social work should preferably should be seen as a mediator. Or is this positioning no longer relevant or tenable in social work today as society since 1979 has changed dramatically

Geschlechtersensible Arbeit an Ganztagsschulen

In diesem Zusammenhang soll im vorliegenden Beitrag gezeigt werden, weshalb eine Ausweitung gendersensibler Arbeit an Ganztagsschulen notwendig ist und welche Perspektiven mögliche Ausbaumaßnahmen dieser Arbeit bieten. Hierzu wird zunächst grundlegend die Konstruktion der Geschlechterrollen untersucht und dabei detaillierter auf die soziale Konstruktion von Geschlecht sowie auf geschlechterspezifische Selbstbilder von Mädchen und Jungen eingegangen. Darauf aufbauend wird sich der Frage gewidmet, welche Konzeption von Geschlecht im Kontext Schule existiert und inwieweit diese mit geschlechterspezifischen Leistungserwartungen im Unterricht und in Nachmittagsangeboten in Zusammenhang steht. Von diesem theoretischen Fundament und Befunden ausgehend, soll darauffolgend die Notwendigkeit gendersensibler Arbeit in Ganztagsschulen auf Grundlage des Auftrages der Institution Schule zur Chancengleichheit dargelegt werden. Im Anschluss daran werden konkrete Maßnahmen zum Ausbau der gendersensiblen Arbeit an Ganztagsschulen und deren mögliche Perspektiven diskutiert. Dabei kommt ein besonderes Augenmerk der Professionalisierung von Lehrkräften und der Implementierung geschlechterspezifischer Lern- und Freizeitangebote zu

Information Complexity of Mixed-integer Convex Optimization

We investigate the information complexity of mixed-integer convex optimization under different types of oracles. We establish new lower bounds for the standard first-order oracle, improving upon the previous best known lower bound. This leaves only a lower order linear term (in the dimension) as the gap between the lower and upper bounds. This is derived as a corollary of a more fundamental ``transfer" result that shows how lower bounds on information complexity of continuous convex optimization under different oracles can be transferred to the mixed-integer setting in a black-box manner. Further, we (to the best of our knowledge) initiate the study of, and obtain the first set of results on, information complexity under oracles that only reveal \emph{partial} first-order information, e.g., where one can only make a binary query over the function value or subgradient at a given point. We give algorithms for (mixed-integer) convex optimization that work under these less informative oracles. We also give lower bounds showing that, for some of these oracles, every algorithm requires more iterations to achieve a target error compared to when complete first-order information is available. That is, these oracles are provably less informative than full first-order oracles for the purpose of optimization.Comment: 35 pages, 4 figure

An exact Riemann Solver and Godunov Scheme for Simulating Highly Transient Mixed Flows

AbstractThe current research aims at deriving a one-dimensional numerical model for describing highly transient mixed flows. In particular, this paper focuses on the development and assessment of a unified numerical scheme adapted to describe free-surface flow, pressurized flow and mixed flow (characterized by the simultaneous occurrence of free-surface and pressurized flows). The methodology includes three steps. First, the authors derived a unified mathematical model based on the Preissmann slot model. Second, a first-order explicit finite volume Godunov-type scheme is used to solve the set of equations. Third, the numerical model is assessed by comparison with analytical, experimental and numerical results. The key results of the paper are the development of an original negative Preissmann slot for simulating sub-atmospheric pressurized flow and the derivation of an exact Riemann solver for the Saint-Venant equations coupled with the Preissmann slot