SZZ Unleashed: An Open Implementation of the SZZ Algorithm -- Featuring Example Usage in a Study of Just-in-Time Bug Prediction for the Jenkins Project

Numerous empirical software engineering studies rely on detailed information about bugs. While issue trackers often contain information about when bugs were fixed, details about when they were introduced to the system are often absent. As a remedy, researchers often rely on the SZZ algorithm as a heuristic approach to identify bug-introducing software changes. Unfortunately, as reported in a recent systematic literature review, few researchers have made their SZZ implementations publicly available. Consequently, there is a risk that research effort is wasted as new projects based on SZZ output need to initially reimplement the approach. Furthermore, there is a risk that newly developed (closed source) SZZ implementations have not been properly tested, thus conducting research based on their output might introduce threats to validity. We present SZZ Unleashed, an open implementation of the SZZ algorithm for git repositories. This paper describes our implementation along with a usage example for the Jenkins project, and conclude with an illustrative study on just-in-time bug prediction. We hope to continue evolving SZZ Unleashed on GitHub, and warmly invite the community to contribute

Coopetition during times of crisis

The aim of this study was to examine how organizations integrate and use coopetition as strategy during times of crisis and how it potentially differs from normal circumstances. Despite much research in the topic of coopetition there was a lack of previous research literature that examines how coopetition is affected during market crises. Our inspiration for our thesis initially came from an article by Crick and Crick (2020) which suggested that due to the lack of sound research on the topic of coopetition during times of crisis, businesses might get into such relationships without enough knowledge, which can possibly lead to grave consequences. In conducting the research, we chose to utilize a qualitative approach to better understand the intricacies and complexity of coopetition. To collect the data, we did semi-structured interviews with managers about their organization’s strategy and experience with coopetitive relationships. The data sample ended up being five interview objects in different industries. The data was then systematically categorized in themes by antecedents and consequences, systematically analyzed and then compared to earlier study findings of coopetition explored in the literature review. The main findings in this master thesis suggest that some antecedents and consequences played a key role in coopetitive relationships during the COVID-19 pandemic. Notably did flexibility as consequence from coopetition make the organizations better suited to withstand and quickly adapt to the impact of the volatile market circumstances during the pandemic. This flexibility was achieved primarily by sharing workforce and reducing costs in collaboration with competitors. In regard to antecedents of coopetition, our study shows that multiple key drivers of coopetition were present during the pandemic, suggesting that the crisis generated new coopetition agreements in the business market. Multiple of the interviewed organizations in the study reported about positive experience from using coopetition as strategy during the COVID-19 pandemic. The small sample size of in the study harms the generalizability of the study, but we still believe that the observations and conclusions in our thesis is a contribution to the narrow field of coopetition during crisis and could be a good starting point for future research on the topic

Coopetition during times of crisis

The aim of this study was to examine how organizations integrate and use coopetition as strategy during times of crisis and how it potentially differs from normal circumstances. Despite much research in the topic of coopetition there was a lack of previous research literature that examines how coopetition is affected during market crises. Our inspiration for our thesis initially came from an article by Crick and Crick (2020) which suggested that due to the lack of sound research on the topic of coopetition during times of crisis, businesses might get into such relationships without enough knowledge, which can possibly lead to grave consequences. In conducting the research, we chose to utilize a qualitative approach to better understand the intricacies and complexity of coopetition. To collect the data, we did semi-structured interviews with managers about their organization’s strategy and experience with coopetitive relationships. The data sample ended up being five interview objects in different industries. The data was then systematically categorized in themes by antecedents and consequences, systematically analyzed and then compared to earlier study findings of coopetition explored in the literature review. The main findings in this master thesis suggest that some antecedents and consequences played a key role in coopetitive relationships during the COVID-19 pandemic. Notably did flexibility as consequence from coopetition make the organizations better suited to withstand and quickly adapt to the impact of the volatile market circumstances during the pandemic. This flexibility was achieved primarily by sharing workforce and reducing costs in collaboration with competitors. In regard to antecedents of coopetition, our study shows that multiple key drivers of coopetition were present during the pandemic, suggesting that the crisis generated new coopetition agreements in the business market. Multiple of the interviewed organizations in the study reported about positive experience from using coopetition as strategy during the COVID-19 pandemic. The small sample size of in the study harms the generalizability of the study, but we still believe that the observations and conclusions in our thesis is a contribution to the narrow field of coopetition during crisis and could be a good starting point for future research on the topic

Homogenization of a catalyst layer model for periodically distributed pore geometries in PEM fuel cells

We formally derive an effective catalyst layer model comprising the reduction of oxygen for periodically distributed pore geometries. By assumption, the pores are completely filled with water and the surrounding walls consist of catalyst particles which are attached to an electron conducting microstructure. The macroscopic transport equations are established by a multi-scale approach, based on microscopic phenomena at the pore level, and serve as a first step toward future optimization of catalyst layer designs

How does continuing training on social interaction skills benefit teachers?

5th ICEEPSY International Conference on Education & Educational Psychology in Kyrenia Cyprus (Oct 22-25, 2014)/ guest editors: Zafer Bekirogullari, Melis Minas.Peer reviewe

Vergleich und Bewertung der Datenbanksicherheit von relationalen Datenbanksystemen

Der digitale Schwarzmarkt mit gestohlenen Daten floriert. Alleine im Jahr 2015 wurden über eine halbe Milliarde Datensätze aus Datenbanksystemen entwendet. Viele Unternehmen bemerken den Sicherheitsvorfall selbst nicht oder geben aus Angst vor einem Imageschaden den Vorfall nicht bekannt. Sind die Datenbestände nicht durch effektive Sicherheitsmechanismen vor Datendiebstahl geschützt, können Cyberkriminelle leicht aus den gestohlenen Daten Kapital schlagen. Die Softwarehersteller von Datenbanksystemen bieten für ihre Produkte unterschiedliche Schutzvorkehrungen an. Ziel dieser Ausarbeitung ist es, die Bedrohungen und die Sicherheitsrisiken von Datenbanksystemen aufzuzeigen und daraus die Aspekte der Datenbanksicherheit abzuleiten. Die ausgearbeiteten Sicherheitsaspekte bilden die Grundlage für den Vergleich der Datenbanksicherheit von relationalen Datenbanklösungen. Die anschließende Bewertung dient dem Nachweis und der Überprüfbarkeit der Datenbanksicherheit relationaler Datenbanksysteme

Investigations concerning functional leukocyte inhibtion in cardiac surgery patients undergoing extracorporeal circulation

Operative Eingriffe am offenen Herzen wie die häufig durchgeführten Bypass- und Herzklappenersatzoperationen bedürfen fast immer der Unterstützung durch die Herz Lungenmaschine bzw. extrakorporale Zirkulation. Durch den Kontakt des Blutes mit nichtorganischen Fremdoberflächen der EKZ kommt es zur Induktion einer transienten Hyperaktivität neutrophiler Granulozyten. Nachdem Herz und Lunge nach Öffnung der Aortenklemme ihre physiologische Funktion wieder aufnehmen und reperfundiert werden, werden aus diesen ischämischen Organen darüber hinaus pathogene Moleküle wie freie Sauerstoffradikale freigesetzt. Von aktivierten Neutrophilen freigesetzte, immmunkompetente Moleküle (z.B. Zytokine) führen zusammen mit diesem oxidativen Stress zu Organdysfunktionen durch Ödembildung in Körpergeweben wie Myokard, Lunge, Gehirn und Gastrointestinaltrakt und dadurch zu typischen Folgeerscheinungen wie z.B. verlängerter postoperativer Beatmungszeit oder (meist transienten) neuropsychologischen Dysfunktionen im Sinne von kognitiven Defiziten. Andere Pathomechanismen wie Mikroembolien durch z.B. Kleinstteilchen und Gasbildungen aus dem OP Gebiet verstärken diese pathogenen Effekte. Resultat ist eine verlängerte Regenerationsdauer und ein verlängerter Krankenhausaufenthalt der operierten Patienten. Zur Minimierung dieser unerwünschten Wirkungen der EKZ wurden in den letzen 20 Jahren diverse Techniken zur Filtration der unterschiedlichen Kreislaufbestandteile innerhalb der EKZ entwickelt. Von besonderem Interesse ist die seit ca. 8 bis 10 Jahren etablierte Filtration aktivierter neutrophiler Granulozyten, die die Hauptverantwortung für das aseptische Entzündungsgeschehen unter Anwendung der EKZ tragen. Entwicklung und Einsatz dieser leukozytenspezifischen Filtersysteme führt zwar zu einer deutlichen Reduktion der zirkulierenden immunaktiven Zellen und zu einer geringgradigen Verringerung der pathogenen EKZ Folgeerscheinungen, die Effektivität der gegenwärtigen Leukozytenfiltration stellt sich allerdings nur in einzelnen Berichten als positiv dar. Die Daten, die einen deutlichen klinischen Vorteil der Leukozytenfiltration zeigen, sind nicht vorhanden. Die unterstützende Anwendung antiinflammatorischer, systemisch angewandter Pharmaka führte zwar bei den meisten Präparaten zu Erfolg versprechenden Ergebnissen im Tierversuch, konnte aber beim operierten Patienten selbst zu keiner deutlichen Verminderung der unerwünschten EKZ Wirkungen beitragen. Unter der Vorstellung, dass gefilterte, aktivierte Leukozyten zum Großteil zwar nicht in den Patientenkreislauf zurückgepumpt werden, jedoch immer noch immunaktive Stoffe von ihnen synthetisiert und sezerniert werden können, liegt es auf der Hand, dass die aktuell zum klinischen Einsatz kommenden Filtersysteme zum Zwecke der Filtrationsoptimierung und konsekutiver Pathogenitätsminimierung durchaus verbesserungsbedürftig sind. Die in Abschnitt 3 angeführten Ergebnisse belegen, dass antikörperbeschichtete Leukozytenfiltermembranen durchaus in der Lage sind, in einem Kreislaufmodell ihre entsprechenden Antigene herauszufiltern und damit zu inaktivieren. Als klinische Anwendung ist dieses Modell allerdings nur unter einem immensem Technik- sowie Kostenaufwand umsetzbar, so dass sich die Frage nach alternativen Lösungsstrategien stellt. Diese Arbeit leistete die theoretische Grundlage zur Entwicklung eines in naher Zukunft möglicherweise klinisch praktikablen Moduls zur Leukozyteninaktivierung. Da anti CD95 IgM in der Lage sind, Apoptose in CD95 Rezeptor tragenden Zellen zu induzieren und diese damit bzgl. ihrer Stoffwechselaktivität zu limitieren bzw. zu inaktivieren, konnte ein ebenfalls in Abschnitt 3 vorgestelltes Modell zeigen, dass in CD 95 Rezeptor tragenden Zellen über ihren Kontakt mit anti CD95 IgM beschichteten Leukozytenfiltermembranen Apoptose induziert werden kann. Ein detailverbessertes, anti CD95 IgM beschichtetes Leukozytenfiltersystem (Leukozyteninhibitionsmodul, „LIM“) zeigte bereits im Schweineversuch eine deutliche Verbesserung der postoperativen Herzfunktion gegenüber der Tiergruppe, die mit herkömmlichem Leukozytenfiltersystem operiert wurde. Außerdem konnte eine deutlich reduzierte Transmigrationsfähigkeit (als Maß des Aktivierungszustandes) der aus dieser EKZ isolierten Neutrophilen nachgewiesen werden, so dass Grund zur Annahme besteht, dass dieses Modell in Zukunft den herkömmlichen Leukozytenfilter ablösen könnte. Mit dieser Arbeit wurde eine Möglichkeit aufgezeigt, wie die Problematik der EKZ induzierten Immunpathogenese grundlegender bekämpft werden kann.Cardiovascular surgery like coronary bypass grafts or valvular tranplantation is often associated with the support by extracorporeal circulation (ECC). As a consequence of the contact between blood an anorganic surfaces an autoimmune reaction with chemotactical activation of neutrophil granulocytes and generation of immune cascades, e.g complement sytem, is started. After opening the Aortic cross clamp, ischemic heart and lung are perfused again, resume their physiological functions and release pathogenic molecules like free oxygen radicals, which aggravate the marring processes. Neutrophiles release immune modulation molecules like cytokines supported by free oxygen radicals mentioned above, which results in multiple organ dysfunctions like oedema in different tissues: myocard, lung, brain and gastrointestinal tract. This involves extended postoperative tracheal respiration and neuropsychological deficits like (often transient) cognitive deficits. Other pathomechanisms like small particles- and gas microemboli released from the operation area contribute to the pathogenic effects. As a result of this regeneration time and postoperative hospital residence are extended. To minimize these undesirable side effects caused by extarcorporeal circulation different strategies like filtration of the different ECC parts were developed within the last 20 years. Since 8-10 years filtration of activated neutrophiles, which are mainly responsible for the aseptic inflammation, was expected to be the most beneficial tool concerning this problem. On the one hand progression and use of these specific filter systems contribute to an effective quantitative reduction of activated neutrophiles inside of ECC and a marginal diminishment of pathogenic ECC consequences. On the other hand convincing scientific data regarding clinical benefit by leucocyte filtration systems is missing. The use of antiinflammatory systemical drugs showed promising results in animal experiments in contrast to the findings in cardiac surgery patients. Under the assumption, that on the one hand filtered, activated leucocytes are held by the filter meshes and not brought back into the patient circulation, on the other hand still produce and release immune modulation molecules it is obvious that these conventional leuycocyte filtration systems are not effective enough concerning their disposal and have to be improved within the next years. The results mentioned in part three proof, that antibody coated leucocyte filter membranes are able to filter and inactivate their respective antigenes in a circulation model. As a clinical application this model is indeed connected with an enormous complexity and expense. This doctorate performed the theoretical fundament for the development of a leukocyte inhibition module, which potentially can be applied for clinical use in the near future. Since anti CD95 IgM molecules are able to induce apoptosis in CD95 receptor positive cells and limit respectively inactivate these cells concerning their metabolism activity an also in part three introduced model indicated, that anti CD95 coated leukocyte filter membrane is able to induce apoptosis in CD95 receptor positive cells by contacting them. An advanced anti CD95 IgM coated model (leukocyte inhibition module, „LIM”) revealed an obvious improved postoperative heart function in a pork model compared to pork, which were operated with common leukocyte filter sytems. In addition to this, a definit reduced ability of transmigration (quantum of the cell activation status) was demonstrated for the neutrophiles isolated from ECC. In conclusion, LIM proved to be an effective tool to functionally inhibit leukocyte activation and thus to limit pathogenic sequelae related to cardiac surgery with ECC. LIM allows the inactivation of neutrophils via CD95 stimulation without affecting other organs by apoptosis-mediated inflammation. Further studies ought to be conducted to evaluate postoperative benefits and the efficacy of LIM in clinical studies

The Company You Keep : Personality and Friendship Characteristics

Studies on personality and friendship have focused on similarities between friends, while differences in friendship patterns have received less attention. We used data from the British Household Panel Survey data (N = 12,098) to investigate how people's personalities are related to various characteristics of their three closest friends. All personality traits of the five-factor model were associated with several friendship characteristics with effect sizes corresponding to correlations between .06 and .09. Openness was especially prominent and idiosyncratic; individuals with high (vs. low) openness were about 3% more likely to have friends who live further away, are of the opposite sex and another ethnicity, and whom they meet less often. Agreeableness and extroversion were related to more traditional friendship ties. Individuals with high agreeableness had known their friends for a longer time, lived close to them, and had more "stay-at-homes" among their friends.Peer reviewe

Shorter birth intervals between siblings are associated with increased risk of parental divorce

Birth intervals are a crucial component of fertility behaviour and family planning. Short birth intervals are associated—although not necessarily causally—with negative health-related outcomes, but less is known about their associations with family functioning. Here, the associations between birth intervals and marital stability were investigated by Cox regression using a nationally representative, register-based sample of individuals with two (N = 42,481) or three (N = 22,514) children from contemporary Finland (observation period 1972–2009). Shorter interbirth intervals were associated with an increased risk of parental divorce over a ten-year follow-up. Individuals with birth intervals of up to 1.5 years had 24–49 per cent higher divorce risk compared to individuals whose children were born more than 4 years apart. The pattern was similar in all socioeconomic groups and among individuals with earlier and later entry to parenthood. Our results add to the growing body of research showing associations between short birth intervals and negative outcomes in health and family functioning.Peer reviewe