The role of African Union law in integrating Africa

This article traces how the development of regional law is linked to the state of regional integration in Africa. Given the prominent role European Union law plays in the functioning of the European Union, the question is posed whether there is similar scope for the development of ‘African Union law’, a term not established hitherto. Initially devoid from the necessary supranational elements required to adopt law that would automatically bind member states, the African Union is leaning towards a functionalist approach paving the way for transfer of sovereign powers to African Union institutions. It is argued that law-making capacity, be it through the activities of the Pan-African Parliament, the Peace and Security Council or the African court system are necessary requirements to accelerate the process of regional integration. African Union law will hold member states accountable to comply with international and continentally agreed standards on inter alia democracy, good governance and human rights

Forced marriage, slavery, and plural legal systems: An African example

Slavery, long abolished under international law, left a devastating imprint on Africa. However, enslavement of women through forced marriages remains a common phenomenon in many African states. These African states share the common feature of legal pluralism where traditional legal systems continue to be observed alongside national laws in which slavery is outlawed. Where traditional practices condone the marriage of underage girls who are legally unable to consent, the questioning of age-old accepted forms of marriage can generate strong reactions. This article traces the position of forced and child marriages in international law, and investigates how legality becomes a moveable target when legal systems exist in parallel. Despite international and African Union conventions on slavery and human rights declaring that marriages not based on the full and free consent of both parties are considered a violation of human rights and a form of slavery, these practices persist. These instruments are assessed to gauge the level of conformity (or variance) of African state practice where forced marriages commonly occur. Importantly, the reasons behind noncompliance and the impact of legal pluralism are explored in African states where forced marriages commonly occur

The Emergence of Gravitational Wave Science: 100 Years of Development of Mathematical Theory, Detectors, Numerical Algorithms, and Data Analysis Tools

On September 14, 2015, the newly upgraded Laser Interferometer Gravitational-wave Observatory (LIGO) recorded a loud gravitational-wave (GW) signal, emitted a billion light-years away by a coalescing binary of two stellar-mass black holes. The detection was announced in February 2016, in time for the hundredth anniversary of Einstein's prediction of GWs within the theory of general relativity (GR). The signal represents the first direct detection of GWs, the first observation of a black-hole binary, and the first test of GR in its strong-field, high-velocity, nonlinear regime. In the remainder of its first observing run, LIGO observed two more signals from black-hole binaries, one moderately loud, another at the boundary of statistical significance. The detections mark the end of a decades-long quest, and the beginning of GW astronomy: finally, we are able to probe the unseen, electromagnetically dark Universe by listening to it. In this article, we present a short historical overview of GW science: this young discipline combines GR, arguably the crowning achievement of classical physics, with record-setting, ultra-low-noise laser interferometry, and with some of the most powerful developments in the theory of differential geometry, partial differential equations, high-performance computation, numerical analysis, signal processing, statistical inference, and data science. Our emphasis is on the synergy between these disciplines, and how mathematics, broadly understood, has historically played, and continues to play, a crucial role in the development of GW science. We focus on black holes, which are very pure mathematical solutions of Einstein's gravitational-field equations that are nevertheless realized in Nature, and that provided the first observed signals.Comment: 41 pages, 5 figures. To appear in Bulletin of the American Mathematical Societ

Toward Optimal Run Racing: Application to Deep Learning Calibration

This paper aims at one-shot learning of deep neural nets, where a highly parallel setting is considered to address the algorithm calibration problem - selecting the best neural architecture and learning hyper-parameter values depending on the dataset at hand. The notoriously expensive calibration problem is optimally reduced by detecting and early stopping non-optimal runs. The theoretical contribution regards the optimality guarantees within the multiple hypothesis testing framework. Experimentations on the Cifar10, PTB and Wiki benchmarks demonstrate the relevance of the approach with a principled and consistent improvement on the state of the art with no extra hyper-parameter

Searching for New Long Lived Particles in Heavy Ion Collisions at the LHC

We show that heavy ion collisions at the LHC provide a promising environment to search for new long lived particles in well-motivated New Physics scenarios. One advantage lies in the possibility to operate the main detectors with looser triggers, which can increase the number of observable events by orders of magnitude if the long lived particles are produced with low transverse momentum. In addition, the absence of pileup in heavy ion collisions can avoid systematic nuisances that will be present in future proton runs, such as the problem of vertex mis-identification. Finally, there are new production mechanisms that are absent or inefficient in proton collisions. We show that the looser triggers alone can make searches in heavy ion data competitive with proton data for the specific example of heavy neutrinos in the Neutrino Minimal Standard Model, produced in the decay of B mesons. Our results suggest that collisions of ions lighter than lead, which are currently under discussion in the heavy ion community, are well-motivated from the viewpoint of searches for New Physics.Comment: Version accepted by Physical Review Letters for publication as a Letter. 6 pages, 3 figure

Numerical approximation of poroelasticity with random coefficients using Polynomial Chaos and Hybrid High-Order methods

In this work, we consider the Biot problem with uncertain poroelastic coefficients. The uncertainty is modelled using a finite set of parameters with prescribed probability distribution. We present the variational formulation of the stochastic partial differential system and establish its well-posedness. We then discuss the approximation of the parameter-dependent problem by non-intrusive techniques based on Polynomial Chaos decompositions. We specifically focus on sparse spectral projection methods, which essentially amount to performing an ensemble of deterministic model simulations to estimate the expansion coefficients. The deterministic solver is based on a Hybrid High-Order discretization supporting general polyhedral meshes and arbitrary approximation orders. We numerically investigate the convergence of the probability error of the Polynomial Chaos approximation with respect to the level of the sparse grid. Finally, we assess the propagation of the input uncertainty onto the solution considering an injection-extraction problem.Comment: 30 pages, 15 Figure

Fine‐Sediment Erosion and Sediment‐Ribbon Morphodynamics in Coarse‐Grained Immobile Beds

In rivers, fine sediments are often transported over immobile coarse grains. With low sediment supply, they tend to aggregate in longitudinal ribbons. Yet, the long-term evolution of such ribbons and the influence of immobile grains on the erosion of fine sediments are still not well understood. Flume experiments without sediment supply were therefore performed to investigate the erosion of an initially uniform fine-sediment bed covering an immobile bed of staggered spheres through topographic and flow measurements. The topographic measurements yielded the spheres\u27 protrusion above the fine sediment (P) and revealed long-lived ribbons with ridges and troughs. The ridges are the main long-term sediment source as the troughs are quickly eroded to a stable bed level resulting from the spheres\u27 sheltering. The ridges stabilize with a spacing of 1.3 effective water depths, their number resulting from the integer number of wavelengths fitting into the effective channel width which excludes side-wall accumulations. The ridges\u27 erosion is damped by the local upflow of secondary current cells, which displaces the strongest sweep events above the bed. The upflow intensity is controlled by the ridges\u27 height for low P, while for high P by the lateral roughness heterogeneity. The trends in erosion rates over ridges and troughs are similar and characterized by the following sequence of four regimes with increasing P: a drag sheltering, a turbulence-enhancement, a wake-interference sheltering, and a skimming-flow sheltering regime. The critical P levels at the transitions are independent of the flow above the canopy, depending only on the geometrical configuration of the immobile bed

Ethical and Unethical Hacking

The goal of this chapter is to provide a conceptual analysis of ethical, comprising history, common usage and the attempt to provide a systematic classification that is both compatible with common usage and normatively adequate. Subsequently, the article identifies a tension between common usage and a normativelyadequate nomenclature. ‘Ethical hackers’ are often identified with hackers that abide to a code of ethics privileging business-friendly values. However, there is no guarantee that respecting such values is always compatible with the all-things-considered morally best act. It is recognised, however, that in terms of assessment, it may be quite difficult to determine who is an ethical hacker in the ‘all things considered’ sense, while society may agree more easily on the determination of who is one in the ‘business-friendly’ limited sense. The article concludes by suggesting a pragmatic best-practice approach for characterising ethical hacking, which reaches beyond business-friendly values and helps in the taking of decisions that are respectful of the hackers’ individual ethics in morally debatable, grey zones