The Locus Algorithm II: A robust software system to maximise the quality of fields of view for Differential Photometry

We present the software system developed to implement the Locus Algorithm, a novel algorithm designed to maximise the performance of differential photometry systems by optimising the number and quality of reference stars in the Field of View with the target. Firstly, we state the design requirements, constraints and ambitions for the software system required to implement this algorithm. Then, a detailed software design is presented for the system in operation. Next, the data design including file structures used and the data environment required for the system are defined. Finally, we conclude by illustrating the scaling requirements which mandate a high-performance computing implementation of this system, which is discussed in the other papers in this series

How Relevant? The EU’s ‘Geopolitical’ Commission and the Response to the Covid-19 Pandemic. College of Europe Policy Brief #4.20 April 2020

The Covid-19 pandemic constitutes an unprecedented challenge for the European Union (EU), posing existential internal as well as external threats to the European integration project. > At the same time, the impact of this global crisis on the international order opens unexpected windows of opportunity for reinforced European integration and a stronger EU presence in the world. > To seize the momentum, the European Commission needs to act consistently with the geopolitical approach put forward by President Ursula von der Leyen. > Internally, it must promote cohesion and unity among member states and coordinate a joint European response to the sanitary, political, and socioeconomic challenges. > Externally, it must join efforts with like-minded members of the international community to establish a robust system of multilateral crisis management tackling the multiple dimensions of the crisis

The Glueball Spectrum from a Potential Model

The spectrum of two-gluon glueballs below 3 GeV is investigated in a potential model with dynamical gluon mass using variational method. The short distance potential is approximated by one-gluon exchange, while the long distance part is taken as a breakable string. The mass and size of the radial as well as orbital excitations up to principle quantum number n=3 are evaluated. The predicted mass ratios are compared with experimental and lattice results.Comment: Revtex, 6 pages with 1 eps figur

Spinoza

"Spinoza", second edition. Encyclopedia entry for the Springer Encyclopedia of EM Phil and the Sciences, ed. D. Jalobeanu and C. T. Wolfe

Implications of a "Fast Radio Burst" from a Galactic Magnetar

A luminous radio burst was recently detected in temporal coincidence with a hard X-ray flare from the Galactic magnetar SGR 1935+2154 with a time and frequency structure consistent with cosmological fast radio bursts (FRB) and a fluence within a factor of $\lesssim 10$ of the least energetic extragalactic FRB previously detected. Although active magnetars are commonly invoked FRB sources, several distinct mechanisms have been proposed for generating the radio emission which make different predictions for the accompanying higher frequency radiation. We show that the properties of the coincident radio and X-ray flares from SGR 1935+2154, including their approximate simultaneity and relative fluence $E_{\rm radio}/E_{\rm X} \sim 10^{-5}$, as well as the duration and spectrum of the X-ray emission, are consistent with extant predictions for the synchrotron maser shock model. Rather than arising from the inner magnetosphere, the X-rays are generated by (incoherent) synchrotron radiation from thermal electrons heated at the same shocks which produce the coherent maser emission. Although the rate of SGR 1935+2154-like bursts in the local universe is not sufficient to contribute appreciably to the extragalactic FRB rate, the inclusion of an additional population of more active magnetars with stronger magnetic fields than the Galactic population can explain both the FRB rate as well as the repeating fraction, however only if the population of active magnetars are born at a rate that is at least two-orders of magnitude lower than that of SGR 1935+2154-like magnetars. This may imply that the more active magnetar sources are not younger magnetars formed in a similar way to the Milky Way population (e.g. via ordinary supernovae), but instead through more exotic channels such as superluminous supernovae, accretion-induced collapse or neutron star mergers.Comment: 21 pages, 9 figures; submitted to ApJL; comments welcome

Identifying Bugs in Make and JVM-Oriented Builds

Incremental and parallel builds are crucial features of modern build systems. Parallelism enables fast builds by running independent tasks simultaneously, while incrementality saves time and computing resources by processing the build operations that were affected by a particular code change. Writing build definitions that lead to error-free incremental and parallel builds is a challenging task. This is mainly because developers are often unable to predict the effects of build operations on the file system and how different build operations interact with each other. Faulty build scripts may seriously degrade the reliability of automated builds, as they cause build failures, and non-deterministic and incorrect build results. To reason about arbitrary build executions, we present buildfs, a generally-applicable model that takes into account the specification (as declared in build scripts) and the actual behavior (low-level file system operation) of build operations. We then formally define different types of faults related to incremental and parallel builds in terms of the conditions under which a file system operation violates the specification of a build operation. Our testing approach, which relies on the proposed model, analyzes the execution of single full build, translates it into buildfs, and uncovers faults by checking for corresponding violations. We evaluate the effectiveness, efficiency, and applicability of our approach by examining hundreds of Make and Gradle projects. Notably, our method is the first to handle Java-oriented build systems. The results indicate that our approach is (1) able to uncover several important issues (245 issues found in 45 open-source projects have been confirmed and fixed by the upstream developers), and (2) orders of magnitude faster than a state-of-the-art tool for Make builds