Report from GI-Dagstuhl Seminar 16394: Software Performance Engineering in the DevOps World

This report documents the program and the outcomes of GI-Dagstuhl Seminar 16394 "Software Performance Engineering in the DevOps World". The seminar addressed the problem of performance-aware DevOps. Both, DevOps and performance engineering have been growing trends over the past one to two years, in no small part due to the rise in importance of identifying performance anomalies in the operations (Ops) of cloud and big data systems and feeding these back to the development (Dev). However, so far, the research community has treated software engineering, performance engineering, and cloud computing mostly as individual research areas. We aimed to identify cross-community collaboration, and to set the path for long-lasting collaborations towards performance-aware DevOps. The main goal of the seminar was to bring together young researchers (PhD students in a later stage of their PhD, as well as PostDocs or Junior Professors) in the areas of (i) software engineering, (ii) performance engineering, and (iii) cloud computing and big data to present their current research projects, to exchange experience and expertise, to discuss research challenges, and to develop ideas for future collaborations

Frustrated quantum antiferromagnetism with ultracold bosons in a triangular lattice

We propose to realize the anisotropic triangular-lattice Bose-Hubbard model with positive tunneling matrix elements by using ultracold atoms in an optical lattice dressed by a fast lattice oscillation. This model exhibits frustrated antiferromagnetism at experimentally feasible temperatures; it interpolates between a classical rotor model for weak interaction, and a quantum spin-1/2 $XY$-model in the limit of hard-core bosons. This allows to explore experimentally gapped spin liquid phases predicted recently [Schmied et al., New J. Phys. {\bf 10}, 045017 (2008)].Comment: 6 pages, as published in EP

Coarse groups, and the isomorphism problem for oligomorphic groups

Let $S_\infty$ denote the topological group of permutations of the natural numbers. We study the complexity of the isomorphism relation on classes of closed subgroups $S_\infty$ in the setting of Borel reducibility between equivalence relations on Polish spaces. Given a closed subgroup $G$ of $S_\infty$, the coarse group $\mathcal M(G)$ is the structure with domain the cosets of open subgroups of $G$, and a ternary relation $AB \sqsubseteq C$. If $G$ has only countably many open subgroups, then $\mathcal M(G)$ is a countable structure. Coarse groups form our main tool in studying such closed subgroups of $S_\infty$. We axiomatise them abstractly as structures with a ternary relation. For appropriate classes of groups, including the profinite groups, we set up a Stone-type duality between the groups and the corresponding coarse groups. In particular we can recover an isomorphic copy of~$G$ from $\mathcal M(G)$ in a Borel fashion. A closed subgroup $G$ of $S_\infty$ is called oligomorphic if for each $n$, its natural action on $n$-tuples of natural numbers has only finitely many orbits. We use the concept of a coarse group to show that the isomorphism relation for oligomorphic subgroups of $S_\infty$ is Borel reducible to a Borel equivalence relation with all classes countable. We show that the same upper bound applies to the larger class of closed subgroups of $S_\infty$ that are topologically isomorphic to oligomorphic groups

Delimitation of the organizer from the posterior notochord : descriptive and functional studies in mouse and African clawed frog

During vertebrate development, gastrulation is probably the most important phase, as the future body plan is established. Thereby the three body axes anterior-posterior, dorsal-ventral and left-right are determined as well. A central role thereby is taken by the Spemann organizer, as this part of the embryo governs the above mentioned processes. The left-right axis is specified by an extracellular leftward fluid-flow, which results in asymmetric gene expression of the TGFβ factor Nodal. In mice the ciliated epithelium responsible for the fluid-flow as well as the organizer are denominated as ?node?. In contrast to that two distinct entities are thought to be responsible for organizer function and fluid-flow in zebrafish, Xenopus and rabbit embryos. In the present study, it could be shown that this also applies for mouse embryos. In order to prevent further confusion the ciliated epithelium responsible for the fluid-flow was denominated as posterior notochord (PNC) as it is in continuity with the notochord but located anterior to the organizer (?node?). The latter is characterized by the expression of the homeobox gene Goosecoid (Gsc). Gsc possesses, like the tissue of the organizer, the potential to induce an almost complete axis and became therefore famous as ?the organizer gene?. However upon knockout of Gsc in the mouse, surprisingly no gastrulation defects could be detected. Therefore the function of Gsc during gastrulation was investigated using a gain-of-function approach. The analysis of this, in the present and previous studies, indicated that Gsc acts as a switch between two modes of cell movement. Accordingly, Gsc promotes active cell migration and inhibits convergent extension movements. Furthermore it was investigated whether the monoamines adrenaline and serotonin have an influence on the cilia and thus on the leftward fluid-flow, as it was reported in rat and Xenopus experiments. Thereby it could be detected that the addition of adrenaline led to a reduction of the ciliary beat frequency (CBF) and therefore the fluid-flow was attenuated. In contrast to that the addition of serotonin or its antagonists resulted only in minor changes of CBF and thus had no measurable effect on the fluid-flow. The consequences of a malformed PNC were analyzed using embryos mutant for Brachyury (T). Thereby, it was shown that embryos homozygous for this mutation did not develop a functional PNC and thus lacked the fluid-flow. Furthermore a possible cause for the absence of asymmetric Nodal in these embryos was brought into context of an attenuated expression of Fgf8. This indicated that T possesses two distinct roles in left-right development. On the one hand it is necessary for the correct formation of a PNC and on the other hand it is probably needed to maintain the expression of Fgf8, which is a prerequisite for the transcription of Nodal. Finally it was investigated whether these functions were conserved from the African clawed frog Xenopus. Thereby, it could be shown, that Xbra, the homologous gene of T in Xenopus, was also necessary for the formation of the gastrocoel roof plate, the homologous structure of the PNC. Additionally it was observed that the absence of Xbra led to an attenuation of Nodal expression in the midline of Xenopus embryos. This implied that not only the function of Brachyury, but also the process of laterality determination is highly conserved between mammals and amphibians.Während der Entwicklung der Wirbeltiere stellt die Gastrulation die vermutlich wichtigste Phase dar, da sie sich durch die Anlage des zukünftigen Körperbauplans auszeichnet. Dabei werden auch die drei Körperachsen Anterior-Posterior, Dorsal-Ventral und Links-Rechts bestimmt. Eine zentrale Rolle nimmt hierbei der sog. Spemann-Organisator ein, da dieser Teil des Embryos die oben genannten Prozesse steuert. Die Links-Rechts-Achse wird als letzte spezifiziert. Dies geschieht durch eine extrazelluläre, linksgerichtete Flüssigkeitsströmung, die eine links-asymmetrische Genexpression des TGFβ Faktors Nodal zur Folge hat. In Mausembryonen wird das für diese Strömung verantwortliche Epithel darüber hinaus als Homolog des Spemann Organisators betrachtet und als ?node? bezeichnet. In den Wirbeltieren Zebrabärbling, Krallenfrosch und Kaninchen sind im Gegensatz dazu zwei verschiedene Strukturen für Organisatorfunktion und Flüssigkeitsströmung verantwortlich. In der vorliegenden Arbeit konnte gezeigt werden, dass es sich in der Maus ebenfalls um zwei verschieden Einheiten handelt. Um weitere Verwechslungen auszuschließen wurde das cilierte Epithel, das für den Flüssigkeitsstrom verantwortlich ist, als posteriores Notochord (PNC) bezeichnet, da es sich in Kontinuität mit dem restlichen Notochord befindet, aber anterior des Organisators (?node?) liegt. Dieser wird durch die Expression des Homöoboxgens Goosecoid (Gsc) charakterisiert. Gsc besitzt, wie das Gewebe des Organisators, die Fähigkeit eine beinahe vollständige Körperachse zu induzieren und wurde daher als ?das Organisator Gen? berühmt. Durch den Funktionsverlust von Gsc in der Maus wurde überraschenderweise aber keine bemerkbare Beeinträchtigung der Gastrulation festgestellt. Daher sollte mittels Funktionsgewinn untersucht werden, welche Funktion Gsc während der Gastrulation besitzt. Die Analysen in dieser und in vorangegangen Arbeiten zeigte, dass Gsc vermutlich als Schalter zwischen zwei verschiedenen Zellbewegungsmodi fungiert, indem es die aktive Migration unterstützt und den Prozess der konvergenten Extension inhibiert. Darüber hinaus wurde untersucht, ob die Monoamine Serotonin und Adrenalin einen Einfluss auf Cilien des PNCs und damit auf den linksgerichteten Flüssigkeitsstrom haben, da es dafür Hinweise aus Ratten- und Froschexperimenten gibt. Dabei zeigte sich, dass die Zugabe von Adrenalin in einer Reduktion der Cilienschlagfrequenz (CBF) resultierte und somit auch die Flüssigkeitsströmung abgeschwächt wurde. Im Gegensatz dazu veränderte die Zugabe von Serotonin oder dessen Antagonisten die CBF nur in geringem Maße und hatte daher keinen entscheidenden Einfluss auf die Flüssigkeitsströmung. Die Fehlbildung eines PNCs wurde anhand der Brachyury (T) Mutante untersucht. Dabei zeigte sich, dass Embryonen, die diese Mutation homozygot tragen, kein funktionelles PNC ausbilden und daher auch über keinen Flüssigkeitsstrom verfügen. Darüber hinaus wurde nach einer Ursache für das Fehlen der asymmetrischen Expression von Nodal in diesen Embryonen gesucht. Dies konnte in Zusammenhang mit einer Abschwächung der Expression von Fgf8 gebracht werden. Daraus folgte, dass T zwei verschiedene Funktionen bei der Entwicklung der Links-Rechts-Achse einnimmt. Einerseits wird es benötigt um ein funktionelles PNC auszubilden, andererseits ist es vermutlich dafür verantwortlich, dass die Expression von Fgf8 erhalten bleibt und damit die Transkription von Nodal ermöglicht wird. Abschließend wurde T auf eine mögliche Konservierung seiner Funktionen im afrikanischen Krallenfrosch untersucht. Dabei zeigte sich, dass Xbra, das homologe Gen von T im Krallenfrosch, ebenfalls für die Morphogenese der Dachplatte des Archenterons, der homologen Stuktur des PNCs, notwendig ist und in Abwesenheit von Xbra die Expression von Nodal beeinträchtigt ist. Daraus konnte geschlossen werden, dass nicht nur die Funktion von Brachyury, sondern auch der Prozess der Links-Rechts Entwicklung zwischen Säugetieren und Amphibien hoch konserviert ist

High Rate Proton Irradiation of 15mm Muon Drifttubes

Future LHC luminosity upgrades will significantly increase the amount of background hits from photons, neutrons and protons in the detectors of the ATLAS muon spectrometer. At the proposed LHC peak luminosity of 5*10^34 1/cm^2s, background hit rates of more than 10 kHz/cm^2 are expected in the innermost forward region, leading to a loss of performance of the current tracking chambers. Based on the ATLAS Monitored Drift Tube chambers, a new high rate capable drift tube detecor using tubes with a reduced diameter of 15mm was developed. To test the response to highly ionizing particles, a prototype chamber of 46 15mm drift tubes was irradiated with a 20 MeV proton beam at the tandem accelerator at the Maier-Leibnitz Laboratory, Munich. Three tubes in a planar layer were irradiated while all other tubes were used for reconstruction of cosmic muon tracks through irradiated and non-irradiated parts of the chamber. To determine the rate capability of the 15mm drift-tubes we investigated the effect of the proton hit rate on pulse height, efficiency and spatial resolution of the cosmic muon signals

Investigation of ion-ion-recombination at atmospheric pressure with a pulsed electron gun

For future development of simple miniaturized sensors based on pulsed atmospheric pressure ionization as known from ion mobility spectrometry, we investigated the reaction kinetics of ion-ion-recombination to establish selective ion suppression as an easy to apply separation technique for otherwise non-selective ion detectors. Therefore, the recombination rates of different positive ion species, such as protonated water clusters H +(H 2O) n (positive reactant ions), acetone, ammonia and dimethyl-methylphosphonate ions, all recombining with negative oxygen clusters O 2 -(H 2O) n (negative reactant ions) in a field-free reaction region, are measured and compared. For all experiments, we use a drift tube ion mobility spectrometer equipped with a non-radioactive electron gun for pulsed atmospheric pressure ionization of the analytes. Both, ionization and recombination times are controlled by the duty cycle and repetition rate of the electron emission from the electron gun. Thus, it is possible to investigate the ion loss caused by ion-ion-recombination depending on the recombination time defined as the time delay between the end of the electron emission and the ion injection into the drift tube. Furthermore, the effect of the initial total ion density in the reaction region on the ion-ion-recombination rate is investigated by varying the density of the emitted electrons. © 2012 The Royal Society of Chemistry