Dust and gas emission from cometary nuclei: the case of comet 67P/Churyumov-Gerasimenko

Comets display with decreasing solar distance an increased emission of gas and dust particles, leading to the formation of the coma and tail. Spacecraft missions provide insight in the temporal and spatial variations of the dust and gas sources located on the cometary nucleus. For the case of comet 67P/Churyumov-Gerasimenko (67P/C-G), the long-term observations from the Rosetta mission point to a homogeneous dust emission across the entire illuminated surface. Despite the homogeneous initial distribution, a collimation in jet-like structures becomes visible. We propose that this observation is linked directly to the complex shape of the nucleus and projects concave topographical features into the dust coma. To test this hypothesis, we put forward a gas-dust description of 67P/C-G, where gravitational and gas forces are accurately determined from the surface mesh and the rotation of the nucleus is fully incorporated. The emerging jet-like structures persist for a wide range of gas-dust interactions and show a dust velocity dependent bending.Comment: 17 pages, with 7 figures. To appear in Advances in Physics X (2018

GIMO : A multi-objective anytime rule mining system to ease iterative feedback from domain experts

Data extracted from software repositories is used intensively in Software Engineering research, for example, to predict defects in source code. In our research in this area, with data from open source projects as well as an industrial partner, we noticed several shortcomings of conventional data mining approaches for classification problems: (1) Domain experts’ acceptance is of critical importance, and domain experts can provide valuable input, but it is hard to use this feedback. (2) Evaluating the quality of the model is not a matter of calculating AUC or accuracy. Instead, there are multiple objectives of varying importance with hard to quantify trade-offs. Furthermore, the performance of the model cannot be evaluated on a per-instance level in our case, because it shares aspects with the set cover problem. To overcome these problems, we take a holistic approach and develop a rule mining system that simplifies iterative feedback from domain experts and can incorporate the domain-specific evaluation needs. A central part of the system is a novel multi-objective anytime rule mining algorithm. The algorithm is based on the GRASP-PR meta-heuristic but extends it with ideas from several other approaches. We successfully applied the system in the industrial context. In the current article, we focus on the description of the algorithm and the concepts of the system. We make an implementation of the system available. © 2020 The Author

Einfluss des Prewarmings auf den narkosebedingten Abfall der Körperkerntemperatur bei cytoreduktiven gynäkologisch-onkochirurgischen Eingriffen

Einleitung: Die intraoperative Hypothermie beschreibt einen Abfall der Körperkerntemperatur unter 36°C während einer Operation. Vorrangig ist sie einer anästhesiebedingten Vasodilatation mit konsekutiver Wärmeumverteilung geschuldet. Sie ist mit verschiedenen perioperativen Komplikationen assoziiert wie bspw. kardialen Ereignissen, erhöhtem Blutverlust, eingeschränkter Gerinnungsfunktion, Wundheilungsstörungen, Wundinfektionen, postoperativem Shivering und Veränderungen des Medikamentenmetabolismus. Über ein aktives, 30-minütiges, konvektives Vorwärmen soll primär der initiale, anästhesiebedingte Temperaturabfall gemindert und sekundär eine potentielle Beeinflussung von Hämodynamik, Säure-Basen-Haushalt, Blutverlust und Prozesszeiten identifiziert werden. Zusätzlich soll die „zero-heat-flux“ Messmethode zur kontinuierlichen, nichtinvasiven Messung der Körperkerntemperatur mit den Messungen mittels tympanalem Infrarotthermometer und nasopharyngealer Temperatursonde verglichen werden. Methodik: 48 Patientinnen zur cytoreduktiven Therapie bei Ovarialkarzinom wurden prospektiv randomisiert. Patientinnen der Prewarmgruppe wurden mit Beginn der ersten anästhesiologischen Maßnahmen für mindestens 30 Minuten bei 43°C mittels Wärmehemd während der Anlage der Periduralanästhesie konvektiv gewärmt. Patientinnen der Standardgruppe erhielten eine gewärmte Baumwolldecke. Intraoperativ wurden beide Gruppen konvektiv bei 43°C gewärmt. Die Temperaturen wurden diskontinuierlich sublingual und tympanal (Infrarotthermometer), kontinuierlich mittels SpotOn™ und intraoperativ zusätzlich kontinuierlich nasopharyngeal gemessen. Parameter der Hämodynamik wurden in 15-minütigen Abständen mithilfe des Anästhesiemonitors gemessen, der Blutverlust wurde anhand des Sauger¬inhalts und der Anzahl gebrauchter Bauchtücher geschätzt. Stündlich wurden arterielle Blutgasanalysen erhoben. Zur statistischen Auswertung wurde der Mann-Whitney-U-Test angewandt, für den Vergleich der Temperaturmessmethoden wurden Bland-Altman-Diagramme erstellt. Eine Irrtumswahrscheinlichkeit p<0,05 wurde als statistisch signifikant angenommen. Ergebnisse: In den Basischarakteristika der Patientinnen gab es abgesehen von einer durchschnittlich um 3,3 cm höheren Körpergröße in der Prewarmgruppe (p=0,047) keine signifikanten Unterschiede zwischen den Gruppen. Primär fiel, bei identischen Ausgangstemperaturen, die Körperkerntemperatur bis zum Hautschnitt um 0,4°C (Interquartilsabstand: -0,6°C; -0,175°C) in der Prewarm-, und um 1,1°C (-1,3°C; -0,8°C) in der Standardgruppe signifikant ab (p<0,001). Im Vergleich der Prewarmgruppe mit der Standardgruppe unterschieden sich sekundär die mediane Herzfrequenz (65,3 beats per minute (bpm) vs. 62 bpm; p=0,048), der Kohlendioxidpartialdruck (37,6 mmHg vs. 39,1 mmHg; p=0,001), der pH-Wert (7,425 vs. 7,409; p=0,028) und die operative Vorlaufzeit (34,4 min vs. 27,1 min; p=0,007) signifikant voneinander. Schlussfolgerung: Ein aktives, konvektives Prewarming während der Anlage eines Periduralkatheters kann den durch die Narkoseeinleitung bedingten Abfall der Körperkerntemperatur bis zum Operationsbeginn signifikant mindern, ohne die anästhesiologischen Prozesszeiten zu beeinflussen. Inwieweit ein Einfluss der klinischen Surrogatparameter intraoperativer Hypothermie durch Prewarming besteht, muss in weiteren Studien mit ggf. höherer Fallzahl untersucht werden. Die SpotOn™-Temperaturmessung zeigte eine gute Übereinstimmung mit der nasopharyngealen Messung, die tympanale Messung per Infrarotthermometer hingegen nicht.Introduction: Intraoperative hypothermia describes a body core temperature below 36°C during surgery. It is mainly caused by an anaesthesia-induced vasodilatation, which causes a redistribution of the body heat. Hypothermia is associated with perioperative complications like cardiac events, coagulation impairment, increased blood loss, impaired wound healing, wound infections, postoperative shivering and an impact on the metabolism of medication, which can prolong the duration of action. By implementing a 30-minute period of convective prewarming, we aimed to primarily reduce the initial, anaesthesia-induced temperature drop and secondarily investigated the possible influence of haemodynamics, acid-base balance, blood loss and process times. We further compared the continuously, non-invasive core body temperature measurement by “zero-heat-flux”-thermometry to the nasopharyngeal and the tympanally infrared thermometry. Methods: 48 patients with surgery of ovarian cancer were prospectively randomized into two groups. Patients in the prewarm group received at least 30 minutes of convective prewarming at 43°C during administration of peridural catheter, starting with the first anaesthesiologic measures. Patients of the control group received a warmed cotton blanket. Both groups were convectively warmed at 43°C intraoperatively. Temperatures were discontinuously measured sublingually and tympanally (infrared thermometer), continuously via SpotOn™ and intraoperatively also nasopharyngeally. Haemodynamic parameters were obtained quarter-hourly from the anaesthesia monitor. Blood loss was estimated by the volume from the suction device and the number of used surgical towels. Arterial blood gas analyses were performed hourly. Statistical analysis was performed by Mann-Whitney-U-tests, the thermometries were compared via Bland-Altman plots. A probability of error of P<0,05 was defined as statistically significant. Results: Besides a significant difference of a 3,3 cm larger body height in the prewarm group (p=0,047), demographic parameters were similar between groups. Primarily, after similar body core temperatures at the beginning, median core temperatures dropped by -0,4°C (interquartile range: -0,6°C; -0,175°C) in the prewarm group and -1,1°C (-1,3°C; -0,8°C) in the control group (p<0,001) until skin incision. Secondary outcomes were a higher heart rate (65,3bpm vs. 62bpm; p=0,048), a lower arterial carbon dioxide tension (37,6mmHg vs. 39,1mmHg; p=0,001), a higher pH (7,425 vs. 7,409; p=0,028) and a prolonged preincisional time (34,4min vs. 27,1min; p=0,007) in the prewarm group. Conclusion: Convective prewarming during anaesthesiologic measures is an effective method to reduce the anaesthesia-induced temperature drop before start of surgery, without affecting the anaesthesiologic process times. For evaluation of the secondary outcomes, larger studies are needed. SpotOn™ temperature measurements showed good consistency with nasopharyngeal measurements, whereas tympanal infrared-thermometry did not

Cognitive-support code review tools : improved efficiency of change-based code review by guiding and assisting reviewers

Code reviews, i.e., systematic manual checks of program source code by other developers, have been an integral part of the quality assurance canon in software engineering since their formalization by Michael Fagan in the 1970s. Computer-aided tools supporting the review process have been known for decades and are now widely used in software development practice. Despite this long history and widespread use, current tools hardly go beyond simple automation of routine tasks. The core objective of this thesis is to systematically develop options for improved tool support for code reviews and to evaluate them in the interplay of research and practice. The starting point of the considerations is a comprehensive analysis of the state of research and practice. Interview and survey data collected in this thesis show that review processes in practice are now largely change-based, i.e., based on checking the changes resulting from the iterative-incremental evolution of software. This is true not only for open source projects and large technology companies, as shown in previous research, but across the industry. Despite the common change-based core process, there are various differences in the details of the review processes. The thesis shows possible factors influencing these differences. Important factors seem to be the process variants supported and promoted by the used review tool. In contrast, the used tool has little influence on the fundamental decision to use regular code reviews. Instead, the interviews and survey data suggest that the decision to use code reviews depends more on cultural factors. Overall, the analysis of the state of research and practice shows that there is a potential for developing better code review tools, and this potential is associated with the opportunity to increase efficiency in software development. The present thesis argues that the most promising approach for better review support is reducing the reviewer's cognitive load when reviewing large code changes. Results of a controlled experiment support this reasoning. The thesis explores various possibilities for cognitive support, two of these in detail: Guiding the reviewer by identifying and presenting a good order of reading the code changes being reviewed, and assisting the reviewer through automatic determination of change parts that are irrelevant for review. In both cases, empirical data is used to both generate and test hypotheses. In order to demonstrate the practical suitability of the techniques, they are also used in a partner company in regular development practice. For this evaluation of the cognitive support techniques in practice, a review tool which is suitable for use in the partner company and as a platform for review research is needed. As such a tool was not available, the code review tool "CoRT" has been developed. Here, too, a combination of an analysis of the state of research, support of design decisions through scientific studies and evaluation in practical use was employed. Overall, the results of this thesis can be roughly divided into three blocks: Researchers and practitioners working on improving review tools receive an empirically and theoretically sound catalog of requirements for cognitive-support review tools. It is available explicitly in the form of essential requirements and possible forms of realization, and additionally implicitly in the form of the tool "CoRT". The second block consists of contributions to the fundamentals of review research, ranging from the comprehensive analysis of review processes in practice to the analysis of the impact of cognitive abilities (specifically, working memory capacity) on review performance. As the third block, innovative methodological approaches have been developed within this thesis, e.g., the use of process simulation for the development of heuristics for development teams and new approaches in repository and data mining

A survey on software coupling relations and tools

Context Coupling relations reflect the dependencies between software entities and can be used to assess the quality of a program. For this reason, a vast amount of them has been developed, together with tools to compute their related metrics. However, this makes the coupling measures suitable for a given application challenging to find. Goals The first objective of this work is to provide a classification of the different kinds of coupling relations, together with the metrics to measure them. The second consists in presenting an overview of the tools proposed until now by the software engineering academic community to extract these metrics. Method This work constitutes a systematic literature review in software engineering. To retrieve the referenced publications, publicly available scientific research databases were used. These sources were queried using keywords inherent to software coupling. We included publications from the period 2002 to 2017 and highly cited earlier publications. A snowballing technique was used to retrieve further related material. Results Four groups of coupling relations were found: structural, dynamic, semantic and logical. A fifth set of coupling relations includes approaches too recent to be considered an independent group and measures developed for specific environments. The investigation also retrieved tools that extract the metrics belonging to each coupling group. Conclusion This study shows the directions followed by the research on software coupling: e.g., developing metrics for specific environments. Concerning the metric tools, three trends have emerged in recent years: use of visualization techniques, extensibility and scalability. Finally, some coupling metrics applications were presented (e.g., code smell detection), indicating possible future research directions. Public preprint [https://doi.org/10.5281/zenodo.2002001]

Gammaretroviral Vectors: Biology, Technology and Application

Retroviruses are evolutionary optimized gene carriers that have naturally adapted to their hosts to efficiently deliver their nucleic acids into the target cell chromatin, thereby overcoming natural cellular barriers. Here we will review—starting with a deeper look into retroviral biology—how Murine Leukemia Virus (MLV), a simple gammaretrovirus, can be converted into an efficient vehicle of genetic therapeutics. Furthermore, we will describe how more rational vector backbones can be designed and how these so-called self-inactivating vectors can be pseudotyped and produced. Finally, we will provide an overview on existing clinical trials and how biosafety can be improved