Temporal and spatial variation of crown condition of main Norway spruce and oak species

The aim of this Internal Report is to analyse the spatial and temporal development of defoliation for Norway spruce (Picea abies) as well as for European and Sessile oak (Quercus robur and Q. petraea) in Europe by means of the transnational Level I data set of ICP Forests and the European Union's 'Scheme on the Protection of Forests against Atmospheric Pollution'. Additional external deposition and meteorological data are used to describe the influence of single stress factors. According to the methodology published in LORENZ et al. (2002) the medium term mean defoliation is used to describe the spatial variability whereas the plot and year specific differences to the medium term mean are used to describe the temporal variability. Possible refinements of the methodology are outlined as well. In line with expectations the analyses of the spatial variability of Norway spruce and oak species show significant correlations of insects, age and country with annual mean defoliation. In general, the deposition of sulphur was positively correlated with medium term mean defoliation. The models revealed no consistent results for the nitrogen components but nitrate deposition was significant in the model for Norway spruce with negative regression coefficients. The index for fungi infestation was negatively correlated with medium term mean defoliation of oak species. This was not expected from the understanding of fungi as damaging effect but was also found for beech (Fagus sylvatica) in earlier evaluations (LORENZ et al. 2002). The index for insect pests was significant in the models for Norway spruce as well as for oak. Additionally, plausible but not significant correlations were found with precipitation. Time trends were mapped for Norway spruce and oak species as a description of the mean development in the evaluation period. The analyses of the temporal variation of defoliation for Norway spruce and oak will be carried out for the Technical Report Level I 2003. Additionally, alternative methods and amendments to the method published by LORENZ et al. (2002) will be tested

The integration of multi-color taint-analysis with dynamic symbolic execution for Java web application security analysis

The view of IT security in today’s software development processes is changing. While IT security used to be seen mainly as a risk that had to be managed during the operation of IT systems, a class of security weaknesses is seen today as measurable quality aspects of IT system implementations, e.g., the number of paths allowing SQL injection attacks. Current trends, such as DevSecOps pipelines, therefore establish security testing in the development process aiming to catch these security weaknesses before they make their way into production systems. At the same time, the analysis works differently than in functional testing, as security requirements are mostly universal and not project specific. Further, they measure the quality of the source code and not the function of the system. As a consequence, established testing strategies such as unit testing or integration testing are not applicable for security testing. Instead, a new category of tools is required in the software development process: IT security weakness analyzers. These tools scan the source code for security weaknesses independent of the functional aspects of the implementation. In general, such analyzers give stronger guarantees for the presence or absence of security weaknesses than functional testing strategies. In this thesis, I present a combination of dynamic symbolic execution and explicit dynamic multi-color taint analysis for the security analysis of Java web applications. Explicit dynamic taint analysis is an established monitoring technique that allows the precise detection of security weaknesses along a single program execution path, if any are present. Multi-color taint analysis implies that different properties defining diverse security weaknesses can be expressed at the same time in different taint colors and are analyzed in parallel during the execution of a program path. Each taint color analyzes its own security weakness and taint propagation can be tailored in specific sanitization points for this color. The downside of dynamic taint analysis is the single exploration of one path. Therefore, this technique requires a path generator component as counterpart that ensures all relevant paths are explored. Dynamic symbolic execution is appropriate here, as enumerating all reachable execution paths in a program is its established strength. The Jaint framework presented here combines these two techniques in a single tool. More specifically, the thesis looks into SMT meta-solving, extending dynamic symbolic execution on Java programs with string operations, and the configuration problem of multi-color taint analysis in greater detail to enable Jaint for the analysis of Java web applications. The evaluation demonstrates that the resulting framework is the best research tool on the OWASP Benchmark. One of the two dynamic symbolic execution engines that I worked on as part of the thesis has won gold in the Java track of SV-COMP 2022. The other demonstrates that it is possible to lift the implementation design from a research specific JVM to an industry grade JVM, paving the way for the future scaling of Jaint

Bildung und Macht

Die zwei hier skizzierten Paradigmen gesellschaftlicher Entwicklung werden insbesondere hinsichtlich ihrer Rolle in Projekten und Programmen der internationalen Entwicklungszusammenarbeit diskutiert

Decision diagrams in machine learning: an empirical study on real-life credit-risk data.

Decision trees are a widely used knowledge representation in machine learning. However, one of their main drawbacks is the inherent replication of isomorphic subtrees, as a result of which the produced classifiers might become too large to be comprehensible by the human experts that have to validate them. Alternatively, decision diagrams, a generalization of decision trees taking on the form of a rooted, acyclic digraph instead of a tree, have occasionally been suggested as a potentially more compact representation. Their application in machine learning has nonetheless been criticized, because the theoretical size advantages of subgraph sharing did not always directly materialize in the relatively scarce reported experiments on real-world data. Therefore, in this paper, starting from a series of rule sets extracted from three real-life credit-scoring data sets, we will empirically assess to what extent decision diagrams are able to provide a compact visual description. Furthermore, we will investigate the practical impact of finding a good attribute ordering on the achieved size savings.Advantages; Classifiers; Credit scoring; Data; Decision; Decision diagrams; Decision trees; Empirical study; Knowledge; Learning; Real life; Representation; Size; Studies;

A tool-supported approach to inter-tabular verification.

The use of decision tables to verify KBS has been advocated several times in the V&V literature. However, one of the main drawbacks of those system is that they fail to detect anomalies which occur over rule chains. In a decision table based context this means that anomalies which occur due to interactions between tables are neglected. These anomalies are called inter-tabular anomalies. In this paper we investigate an approach that deals with inter-tabular anomalies. One of the prerequisites for the approach was that it could be used by the knowledge engineer during the development of the KBS. This requires that the anomaly check can be performed on-line. As a result, the approach partly uses heuristics where exhaustive checks would be too inefficient. All detection facilities that will be described, have been implemented in a table-based development tool called PROLOGA. The use of this tool will be briefly illustrated. In addition, some experiences in verifying large knowledge bases are discussed.

Examining the Roles of the Receptor Tyrosine Kinase PVR and the Bone Morphogenic Protein Receptor Thickvein in Regulating Self-Renewal and Division Frequency in the Cyst Stem Cells of the Drosophila Testis Niche

Adult stem cells live in different tissues, and they support and regenerate both the tissue they reside in and themselves. The stemness behavior is tightly regulated by the niche. The Drosophila testis is a valuable model to study stem cells in their niche. In this niche, there are two populations of stem cells; germline stem cells (GSCs) and somatic cyst stem cells (CySCs). GSCs and CySCs provide the cellular structure required to maintain the production of sperm in Drosophila males. These stem cells co-mingle around a group of non-dividing somatic cells known as the hub, and is the niche that provides molecular signals to instruct the behavior of stem cells. The fate of GSCs and differentiating germ cells is dependent on CySCs and their descendants, cyst cells, because if these cells are blocked, GSCs would be unable to be maintained normally as stem cells or differentiate properly. This dissertation describes the role of PVR and BMP signaling pathways in the CySCs of the Drosophila testis stem cell niche. PVR signaling regulates the cell division frequency of the CySCs in the stem cell niche. This was shown by loss of function experiments, as inhibiting PVR in the CySCs by RNA interference and dominant negative transgene expression resulted in significant reduction of CySCs at the niche and the cycling CySCs and disruption of transit amplifying germ cells non-autonomously. It was also demonstrated by constitutive PVR expression, or ectopic Pvf1 ligand expression, which resulted in tumorous accumulation of cyst lineage cells throughout the testis, and misregulated cycling of these cells outside of the niche. PVR might also play a role in stem cell competition at the niche. PVR mutant CySCs clones do not persist as stem cells in the testis and PVR mutant clones are out competed with the wildtype CySCs. Our result also demonstrated that when constitutively activate PVR is combined with tumor suppressor Merlin over-expression in the cyst cells lineage, Merlin suppresses PVR signaling and is able to prevent any tumor formation due to hyperproliferation of cyst cells in the testis. BMP signaling pathway is the main self-renewal regulator in GSCs. We have examined the requirement for BMP signaling in the CySCs and demonstrated that BMP signaling pathway regulates stem cell maintenance in the Drosophila testis stem cell niche. When we ablated tkv, the type I receptor of BMP pathway in the cyst lineage cells by RNA interference, we observed a partial loss of CySCs and loss of differentiated cyst cells. In the absence of cyst cells, the germline cells were also incapable of completing differentiation and the number of GSCs also decreased in the manipulated testes showing the non-autonomous effect of ablating BMP pathway in CySCs on the population of GSCs

Die strategische Triage

Durch die moralische Analyse des Triagekonzeptes aus der medizinischen Versorgung wird neben der allgemein üblichen Verwendung dieser Konzeption in Notfallkontexten die Anwendbarkeit als Orientierungsmittel bei der strategischen Planung bi- und multilateraler Operationen in entwicklungspolitischen Programmen eruiert. Dabei zeigt sich die besondere Eignung der Triagekonzeption als Verwaltungsstrategie chronischer Mangelsituationen sowie ihre Fähigkeit vorhandene Ressourcen Effizienz maximierend einzusetzen. Anders als in der Debatte um positive wie negative Konditionalität im internationalen Menschenrechtsschutz ist die strategische Triage als utilitaristische Auswahlregel weniger stark politisch geprägt und orientiert sich weitaus stärker an der Wirkungseffizienz der eingesetzten Mittel als an den Möglichkeiten politischer Einflussnahme. Trotz umfassender moralischer Einwände gegenüber einer strategischen Anwendung bleibt die Triage unter der Annahme einer persistenten Unterversorgung in der internationalen Entwicklungszusammenarbeit letztlich alternativlos