A Study of the Learnability of Relational Properties: Model Counting Meets Machine Learning (MCML)

This paper introduces the MCML approach for empirically studying the learnability of relational properties that can be expressed in the well-known software design language Alloy. A key novelty of MCML is quantification of the performance of and semantic differences among trained machine learning (ML) models, specifically decision trees, with respect to entire (bounded) input spaces, and not just for given training and test datasets (as is the common practice). MCML reduces the quantification problems to the classic complexity theory problem of model counting, and employs state-of-the-art model counters. The results show that relatively simple ML models can achieve surprisingly high performance (accuracy and F1-score) when evaluated in the common setting of using training and test datasets - even when the training dataset is much smaller than the test dataset - indicating the seeming simplicity of learning relational properties. However, MCML metrics based on model counting show that the performance can degrade substantially when tested against the entire (bounded) input space, indicating the high complexity of precisely learning these properties, and the usefulness of model counting in quantifying the true performance

Advances in atomic force microscopy

This article reviews the progress of atomic force microscopy (AFM) in ultra-high vacuum, starting with its invention and covering most of the recent developments. Today, dynamic force microscopy allows to image surfaces of conductors \emph{and} insulators in vacuum with atomic resolution. The mostly used technique for atomic resolution AFM in vacuum is frequency modulation AFM (FM-AFM). This technique, as well as other dynamic AFM methods, are explained in detail in this article. In the last few years many groups have expanded the empirical knowledge and deepened the theoretical understanding of FM-AFM. Consequently, the spatial resolution and ease of use have been increased dramatically. Vacuum AFM opens up new classes of experiments, ranging from imaging of insulators with true atomic resolution to the measurement of forces between individual atoms.Comment: In press (Reviews of Modern Physics, scheduled for July 2003), 86 pages, 44 figure

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Husbandry Of Monodelphis Domestica In The Study Of Mammalian Embryogenesis

Monodelphis domestica, commonly called the laboratory opossum, is a useful laboratory animal for studying marsupial embryogenesis and mammalian development. Females breed year-round and the animals can be sustainably bred indoors. The authors draw on their own laboratory\u27s experience to supplement previously published research on laboratory opossums. They describe a breeding protocol that reliably produces timed-pregnant M. domestica. Additionally, the authors discuss general laboratory opossum husbandry techniques and describe how to collect, handle and culture embryos

Diagnostic de mortalité embryonnaire par la détermination du nombre de corps jaunes chez la chèvre gestante, étude ex-vivo.

Objectif : L’objectif poursuivi consistait à identifier les structures lutéales chez la chèvre gestante et à poser le diagnostic de mortalité embryonnaire en étude ex vivo. Cette étude était menée à la tuerie du marché L.D. KABILA de Lubumbashi, de mars à juin 2009, sur un effectif de 500 femelles de race locale.Méthodologie et résultats : Les travaux s’étaient appuyés sur une caractérisation zootechnique. L’examen exvivo de l’appareil génital femelle permettait le constat d’un état gestatif établi en tenant compte de l’état des cornes utérines et de la présence d’un corps jaune gestatif. Le diagnostic de corps jaune tenait compte de leur nombre et de la présence numérique et de la latéralité gauche et droite d’embryon et/ou foetus. Les gestations de triplets avaient présenté une faible fréquence (0,43%) par rapport aux gestations gémellaires (47,05%) et simples (52 ,2%). La prolificité attendue était de 1,4 (679/500). Le diagnostic des corps jaunes gestatifs était observé en nombre supérieur à la présence des embryons/foetus et traduisait la proportion des mortalités embryonnaires (11,1%). La latéralité gauche/droite des corps jaunes gestatifs avait permis de noter la présence de 1-2 corps jaunes sur l’un ou l’autre ovaire, sans toutefois mettre en évidence la présence de triplet sur un ovaire. L’ovaire gauche n’était pas significativement plus actif que l’ovaire droit. La latéralité permettait d’observer des cas de gestation dans la corne gauche (53,3%) et dans la corne droite (46,7%). La présence d’un embryon/foetus était accompagnée de deux corps jaunes portés soit bilatéralement par les deux ovaires, soit unilatéralement par chaque ovaire. Les cas avec trois corps jaunes avaient des faibles proportions.Conclusion et application des résultats : L’abattage des femelles gestantes réduit la prolificité attendue. Un suivi d’élevage est nécessaire pour pallier ces pertes au travers d’un diagnostic échographique de gestation avant le transfert des chèvres vers l’abattoir. Ce suivi est une opportunité pour améliorer la productivité de l’élevage traditionnel de la chèvre ou « vache du pauvre » dont le bénéfice alimentaire, économique et socioculturel en fait un véritable compte sur pied au bénéfice des communautés confrontées à la pauvreté et à la malnutrition. En perspectives, la mise en place de la gestion de reproduction permettra d’améliorer la rentabilité des élevagesMots clés : Embryon, foetus, mortalité embryonnaire, corps jaune, chèvre, étude ex-vivo, Lubumbash