Studying the Use of SZZ with Non-functional bugs

Non-functional bugs bear a heavy cost on both software developers and end-users. Tools to reduce the occurrence, impact, and repair time of non-functional bugs can therefore provide key assistance for software developers racing to fix these issues. Classification models that focus on identifying defect-prone commits, referred to as \emph{Just-In-Time (JIT) Quality Assurance} are known to be useful in allowing developers to review risky commits. JIT models, however, leverage the SZZ approach to identify whether or not a past change is bug-inducing. However, the due to the nature of non-functional bugs, their fixes may be scattered and separate from their bug-inducing locations in the source code. Yet, prior studies that leverage or evaluate the SZZ approach do not consider non-functional bugs, leading to potential bias on the results. In this thesis, we conduct an empirical study on the results of the SZZ approach on the non-functional bugs in the NFBugs dataset, and the performance bugs in Cassandra, and Hadoop. We manually examine whether each identified bug-inducing change is indeed the correct bug-inducing change. Our manual study shows that a large portion of non-functional bugs cannot be properly identified by the SZZ approach. We uncover root causes for false detection that have not been previously found. We evaluate the identified bug-inducing changes based on criteria from prior research. Our results may be used to assist in future research on non-functional bugs, and highlight the need to complement SZZ to accommodate the unique characteristics of non-functional bugs. Furthermore, we conduct an empirical study to evaluate model performance for JIT models by using them to identify bug-inducing code commits for performance related bugs. Our findings show that JIT defect prediction classifies non-performance bug-inducing commits better than performance bug-inducing commits. However, we find that manually correcting errors in the training data only slightly improves the models. In the absence of a large number of correctly labelled performance bug-inducing commits, our findings show that combining all available training data yields the best classification results

Hans Rottenhammer in Venice: Networking in Style between Italy and Germany

Scholarship on cultural and artistic exchanges between northern Europe and Italy during the sixteenth and early seventeenth centuries has focused primarily on the development of artistic style, largely ignoring the fact that successful artists were also successful businessmen. My work places the early modern artist in a different context, reconstructing the interrelationships between art, commerce, and networks. This dissertation examines the ways in which German painter Hans Rottenhammer (c. 1564–1625) achieved international success from Venice through his use of networks. Part of the late sixteenth-century wave of northern European artists traveling south to Italy for further training, Rottenhammer is best known for his small-format paintings of religious and mythological subjects on copper panels. His decision to actively pursue and develop an artistic style that met the sophisticated tastes of European courts and international merchants saw the critical imitation of Venetian and Roman masters. As a foreign artist in Venice, equally significant for Rottenhammer and his career was the strategic use of various groups in his social network. His collaborative copper painting enterprise with Flemish landscape specialists Paul Bril and Jan Brueghel the Elder brought him into the rarefied circles of leading patrons, such as Cardinal Federico Borromeo. Rottenhammer’s artist-friends and German merchants around Venice’s Fondaco dei Tedeschi also served as intermediaries and agents, marketing his work to collectors on both sides of the Alps. In presenting an alternative model for how artists garnered success through the use of intermediaries and agents—different from the long-standing artist-patron relationship and the “open market” models—this dissertation further illuminates the close connections between art, commerce, and networks in the early modern period.Chapter 1 traces Rottenhammer’s stylistic development, from his apprenticeship in Munich to his continued education in Italy and demonstrates Rottenhammer’s critical imitation of Italian, Flemish, and German masters. It also argues for a connection between the international style practiced by Rottenhammer and efforts toward a common European culture. Chapter 2 reconstructs Rottenhammer’s social network through correspondences, testimonials, princely court and city records, and contemporary biographies. Using the methods of social network theory and network visualization, the chapter shows how Rottenhammer negotiated with and worked through overlapping networks of artist-friends, patrons, and merchants in order to establish his career. The chapter also brings attention to Rottenhammer’s activities as an art agent, connecting the multiple roles served by the artist to his associations with merchants and professional art agents. Chapter 3 investigates copper painting economics through the infrastructure of the European copper metal trade. This chapter frames copper painting as a luxury product supported by Southern German merchant trade networks involved in the mining and trade of European metals. Chapter 4 examines Rottenhammer’s collaborations on copper, namely copper panel paintings produced with Paul Bril and Jan Brueghel the Elder, and engravings after Rottenhammer’s designs by the Sadeler family and Lucas Kilian. This final chapter provides an alternative model to understand the phenomenon of collaborative paintings, distinct from the long-standing scholarly discussions of friendship, for Rottenhammer’s collaborative copper paintings with Bril and Brueghel, produced at long distances apart, were predicated upon existing networks and infrastructures

TSPO PET signal using [F-18]GE180 is associated with survival in recurrent gliomas

Purpose Glioma patients, especially recurrent glioma, suffer from a poor prognosis. While advances to classify glioma on a molecular level improved prognostication at initial diagnosis, markers to prognosticate survival in the recurrent situation are still needed. As 18 kDa translocator protein (TSPO) was previously reported to be associated with aggressive histopathological glioma features, we correlated the TSPO positron emission tomography (PET) signal using [F-18]GE180 in a large cohort of recurrent glioma patients with their clinical outcome. Methods In patients with [F-18]GE180 PET at glioma recurrence, [F-18]GE180 PET parameters (e.g., SUVmax) as well as other imaging features (e.g., MRI volume, [F-18]FET PET parameters when available) were evaluated together with patient characteristics (age, sex, Karnofsky-Performance score) and neuropathological features (e.g. WHO 2021 grade, IDH-mutation status). Uni- and multivariate Cox regression and Kaplan-Meier survival analyses were performed to identify prognostic factors for post-recurrence survival (PRS) and time to treatment failure (TTF). Results Eighty-eight consecutive patients were evaluated. TSPO tracer uptake correlated with tumor grade at recurrence (p < 0.05), with no significant differences in IDH-wild-type versus IDH-mutant tumors. Within the subgroup of IDH-mutant glioma (n = 46), patients with low SUVmax (median split, <= 1.60) had a significantly longer PRS (median 41.6 vs. 25.3 months, p = 0.031) and TTF (32.2 vs 8.7 months, p = 0.001). Also among IDH-wild-type glioblastoma (n = 42), patients with low SUVmax (<= 1.89) had a significantly longer PRS (median not reached vs 8.2 months, p = 0.002). SUVmax remained an independent prognostic factor for PRS in the multivariate analysis including CNS WHO 2021 grade, IDH status, and age. Tumor volume defined by [F-18]FET PET or contrast-enhanced MRI correlated weakly with TSPO tracer uptake. Treatment regimen did not differ among the median split subgroups. Conclusion Our data suggest that TSPO PET using [F-18]GE180 can help to prognosticate recurrent glioma patients even among homogeneous molecular subgroups and may therefore serve as valuable non-invasive biomarker for individualized patient management

Differential Spatial Distribution of TSPO or Amino Acid PET Signal and MRI Contrast Enhancement in Gliomas

In this study, dual PET and contrast enhanced MRI were combined to investigate their correlation per voxel in patients at initial diagnosis with suspected glioblastoma. Correlation with contrast enhancement (CE) as an indicator of BBB leakage was further used to evaluate whether PET signal is likely caused by BBB disruption alone, or rather attributable to specific binding after BBB passage. PET images with [18F]GE180 and the amino acid [18F]FET were acquired and normalized to healthy background (tumor-to-background ratio, TBR). Contrast enhanced images were normalized voxel by voxel with the pre-contrast T1-weighted MRI to generate relative CE values (rCE). Voxel-wise analysis revealed a high PET signal even within the sub-volumes without detectable CE. No to moderate correlation of rCE with TBR voxel-values and a small overlap as well as a larger distance of the hotspots delineated in rCE and TBR-PET images were detected. In contrast, voxel-wise correlation between both PET modalities was strong for most patients and hotspots showed a moderate overlap and distance. The high PET signal in tumor sub-volumes without CE observed in voxel-wise analysis as well as the discordant hotspots emphasize the specificity of the PET signals and the relevance of combined differential information from dual PET and MRI images

Partnership for Research on Ebola VACcination (PREVAC): protocol of a randomized, double-blind, placebo-controlled phase 2 clinical trial evaluating three vaccine strategies against Ebola in healthy volunteers in four West African countries

International audienceAbstract Introduction The Ebola virus disease (EVD) outbreak in 2014–2016 in West Africa was the largest on record and provided an opportunity for large clinical trials and accelerated efforts to develop an effective and safe preventative vaccine. Multiple questions regarding the safety, immunogenicity, and efficacy of EVD vaccines remain unanswered. To address these gaps in the evidence base, the Partnership for Research on Ebola Vaccines (PREVAC) trial was designed. This paper describes the design, methods, and baseline results of the PREVAC trial and discusses challenges that led to different protocol amendments. Methods This is a randomized, double-blind, placebo-controlled phase 2 clinical trial of three vaccine strategies against the Ebola virus in healthy volunteers 1 year of age and above. The three vaccine strategies being studied are the rVSVΔG-ZEBOV-GP vaccine, with and without a booster dose at 56 days, and the Ad26.ZEBOV,MVA-FN-Filo vaccine regimen with Ad26.ZEBOV given as the first dose and the MVA-FN-Filo vaccination given 56 days later. There have been 4 versions of the protocol with those enrolled in Version 4.0 comprising the primary analysis cohort. The primary endpoint is based on the antibody titer against the Ebola virus surface glycoprotein measured 12 months following the final injection. Results From April 2017 to December 2018, a total of 5002 volunteers were screened and 4789 enrolled. Participants were enrolled at 6 sites in four countries (Guinea, Liberia, Sierra Leone, and Mali). Of the 4789 participants, 2560 (53%) were adults and 2229 (47%) were children. Those < 18 years of age included 549 (12%) aged 1 to 4 years, 750 (16%) 5 to 11 years, and 930 (19%) aged 12–17 years. At baseline, the median (25th, 75th percentile) antibody titer to Ebola virus glycoprotein for 1090 participants was 72 (50, 116) EU/mL. Discussion The PREVAC trial is evaluating—placebo-controlled—two promising Ebola candidate vaccines in advanced stages of development. The results will address unanswered questions related to short- and long-term safety and immunogenicity for three vaccine strategies in adults and children. Trial registration ClinicalTrials.gov NCT02876328 . Registered on 23 August 2016