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Punctured groups for exotic fusion systems
No full textThe transporter systems of Oliver and Ventura and the localities of Chermak are classes of algebraic structures that model the -local structures of finite groups. Other than the transporter categories and localities of finite groups, important examples include centric, quasicentric, and subcentric linking systems for saturated fusion systems. These examples are, however, not defined in general on the full collection of subgroups of the Sylow group. We study here punctured groups, a short name for transporter systems or localities on the collection of nonidentity subgroups of a finite -group. As an application of the existence of a punctured group, we show that the subgroup homology decomposition on the centric collection is sharp for the fusion system. We also prove a Signalizer Functor Theorem for punctured groups and use it to show that the smallest Benson–Solomon exotic fusion system at the prime 2 has a punctured group, while the others do not. As for exotic fusion systems at odd primes , we survey several classes and find that in almost all cases, either the subcentric linking system is a punctured group for the system, or the system has no punctured group because the normalizer of some subgroup of order is exotic. Finally, we classify punctured groups restricting to the centric linking system for certain fusion systems on extraspecial -groups of order 3
Daseinsvorsorge in Deutschland - eine empirische Analyse der Zufriedenheit mit der Abholung der Haushaltsabfälle: Einflussfaktoren, Wirkungsgrad, demographische Unterschiede und Optimierungsansätze
No full textDie Dissertation vereint drei Artikel und ein Arbeitspapier mit dem Ziel, Grundlagenwissen über zufriedenheitsbeeinflussende Faktoren in der Entsorgungswirtschaft zu schaffen. Darüber hinaus wird ein Modell entwickelt, welches es den verschiedenen wirtschaftenden Akteuren der andienungspflichtigen Abfallentsorgung in Deutschland ermöglicht, auf wissenschaftlichen Erkenntnissen fußende operative Entscheidungen zu treffen (Abbildung 1). Neben Artikel A, welcher neues Grundlagenwissen über die Zufriedenheit beeinflussende Faktoren mithilfe durchgeführter und ausgewerteter Expertenbefragungen generiert, zeigen Artikel B und C zum einen die Einflussstärke einzelner Faktoren auf die allgemeine Zufriedenheit mit der Abfallabholung und zum anderen die Ausprägung dieser Faktoren in verschiedenen demographischen Clustern der befragten Stichprobe auf. Auf diesen Erkenntnissen aufbauend habe ich im Rahmen einer weiteren Expertenbefragung den Bedarf zur Steigerung der Zufriedenheit mit der Abfallabholung unter Berücksichtigung wirtschaftlicher und logistischer Vorgaben abgefragt. Die Fragen dienen der grundsätzlichen Einschätzung, ob eine autonome, dezentral gesteuerte Abfallabholung zur Optimierung der Leistungsfaktoren sinnvoll ist und welche Faktoren dabei die als entscheidende Zielvorgabe gesetzt werden. Somit wird ein Bogen gespannt von der Entstehung und Beeinflussung der Zufriedenheit über den aktuellen Stand und die Ausprägung der einzelnen Faktoren bis hin zur Handlungsempfehlung zur Verbesserung der logistischen Prozesse, um die Zufriedenheit effektiv und effizient zu steigern
Von Wittenberg und Nürnberg nach Kronstadt: Die Siebenbürgischen Kirchenordnungen von 1543/47 vor dem Hintergrund ihrer Wurzeln
No full textIn the early phase of the Reformation in Transylvania, two churchregulating texts became particularly important: Johannes Honter’s little Reformation booklet for Kronstadt und Burzenland from 1543 and the church regulations published in print in 1547, which the Universitas Saxonum made binding for the entire area of Saxon law three years later. The essay focuses on these two important texts and analyzes their roots in the Reformation tradition of the Holy Roman Empire and the Swiss Confederation. Wittenberg and Nuremberg stand for two of the possible sources from which the Transylvanian church ordinances could have drawn. In view of more than a century of intensive historiographical debate on these questions, an attempt is made to present the different positions and to check them for plausibility. The influence of Swiss theology, which is important from a church historical perspective, is also analyzed here
WARS1 and SARS1: Two tRNA synthetases implicated in autosomal recessive microcephaly
No full textAminoacylation of transfer RNA (tRNA) is a key step in protein biosynthesis, carried out by highly specific aminoacyl‐tRNA synthetases (ARSs). ARSs have been implicated in autosomal dominant and autosomal recessive human disorders. Autosomal dominant variants in tryptophanyl‐tRNA synthetase 1 (WARS1) are known to cause distal hereditary motor neuropathy and Charcot‐Marie‐Tooth disease, but a recessively inherited phenotype is yet to be clearly defined. Seryl‐tRNA synthetase 1 (SARS1) has rarely been implicated in an autosomal recessive developmental disorder. Here, we report five individuals with biallelic missense variants in WARS1 or SARS1, who presented with an overlapping phenotype of microcephaly, developmental delay, intellectual disability, and brain anomalies. Structural mapping showed that the SARS1 variant is located directly within the enzyme's active site, most likely diminishing activity, while the WARS1 variant is located in the N‐terminal domain. We further characterize the identified WARS1 variant by showing that it negatively impacts protein abundance and is unable to rescue the phenotype of a CRISPR/Cas9 wars1 knockout zebrafish model. In summary, we describe two overlapping autosomal recessive syndromes caused by variants in WARS1 and SARS1, present functional insights into the pathogenesis of the WARS1‐ related syndrome and define an emerging disease spectrum: ARS‐related developmental disorders with or without microcephaly
„Von der Liebe zur Natur und Blumen ...”: Sächsische Gärten in Reiseberichten österreichischer Hofgärtner aus den Jahren 1882, 1887 und 1891: Saxon gardens in travel reports by Austrian court gardeners from the years 1882, 1887 and 1891
No full textIn den Jahren 1882, 1887 sowie 1889 bis 1891 reisten fünf österreichische Hofgärtner im Zuge von Weiterbildungsreisen durch West- und Mitteleuropa. Auch Sachsen stand auf ihrem Reiseprogramm. Die erhaltenen und nun transkribierten Reiseberichte ermöglichen einen unterschiedlich tiefen fachlichen Blick auf Schlossgärten, öffentliche Parks, Handelsgärtnereien und Baumschulen in Leipzig und Dresden. Da die fünf Hofgärtner nicht den jeweiligen Eigentümern, sondern – wenn überhaupt – nur ihrem Auftraggeber schmeicheln mussten, gewähren ihre Berichte einen vielschichtigen Eindruck der besichtigten sächsischen Grünanlagen und Gärtneretablissements.In the years 1882, 1887 and 1889 to 1891, five Austrian court gardeners traveled through Western and Central Europe as part of a training trip. Saxony was also on their itinerary. The surviving and now transcribed travel reports provide an insight into palace gardens, public parks, commercial nurseries and tree nurseries in Leipzig and Dresden in varying degrees of depth. As the five court gardeners did not have to flatter the respective owners, but only – if at all – their patrons, their reports provide a multilayered impression of the Saxon parks and gardening establishments they visited
Modeling and Analysis of Dependable Systems
No full textThis PhD thesis illustrates how applying formal analysis techniques can systematically assess the dependability of diverse systems with a wide range of requirements susceptible to various threats. It covers reliability, availability, integrity, and safety requirements.
Furthermore, this thesis considers malicious faults within the network or caused by malicious administrators. It also considers benign faults, such as transient faults, hardware faults, and software faults. To conclude this thesis, a summary of the results and the key lessons learned are presented, along with an outlook on possible future work.
This thesis considers dependable systems with various requirements. The objective is to increase confidence in the correctness of these systems with respect to their requirements. The outcomes of this work are the following:
• Quantitatively estimating the efficacy of specific fault tolerance approaches (Chapter 3 and Chapter 4).
• Identifying failure scenarios during both development (Chapter 5 and Chapter 6) and runtime (Chapter 7) phases.
• Verify the correctness of specific dependable systems formally after considering the necessary countermeasures to remove the identified failures (Chapter 5, Chapter 6, and Chapter 7).
This thesis tackled these issues systematically, contributing to a deeper understanding of these systems and contributing to the enhancement of their dependability.:Contents
List of Figures XIII
List of Tables XIV
List of Listings XV
Conventions XV
1 Introduction 1
1.1 Dependable Systems in Our Vicinity . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Dependability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Thesis Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.4 Thesis Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
1.5 Organization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2 Formal Methods 17
2.1 Formal Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.2 Formal Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3 HAFT: Hardware-Assisted Fault Tolerance 23
3.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3.2 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3.1 Fault Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3.2 HAFT Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.4 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.4.1 Probabilistic Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.4.2 Formally Specifying Probabilistic Systems using PRISM . . . . . . . 30
3.5 Implementation and Verification . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.5.1 Reliability Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.5.2 Availability Modeling With Manual State Recovery. . . . . . . . . . . 37
3.5.3 Availability Modeling With Reboot Crashed Nodes . . . . . . . . . . . 40
3.5.4 Availability Modeling With Both Manual State Recovery and Reboot
Crashed Nodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
3.6 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.7 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.7.1 Quantitative Dependability Modeling and Analysis Techniques. . . . . 46
3.7.2 Resilience-oriented Related Work Built Using HAFT . . . . . . . . . . 47
3.7.3 Reliability Analysis of Fault Tolerance Approaches Against Transient
Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
3.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4 PCRAFT: Capacity Planning for Dependable Services 53
4.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.2 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.3.1 Fault Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
4.3.2 Architecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
4.3.3 Dependable Services . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.3.4 Capacity Planning Process . . . . . . . . . . . . . . . . . . . . . . . . 59
4.4 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.4.1 Availability Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.4.2 Integrity Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.5 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.5.1 Experimental Settings . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.5.2 Experimental Measurements . . . . . . . . . . . . . . . . . . . . . . . 64
4.5.3 Dependability Evaluation. . . . . . . . . . . . . . . . . . . . . . . . . 66
4.6 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.7 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
4.7.1 Dependability Approaches . . . . . . . . . . . . . . . . . . . . . . . . 71
4.7.2 Dependability-costs Studies . . . . . . . . . . . . . . . . . . . . . . . 73
4.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
5 CHORS: Hardening High-Assurance Security Systems with Trusted Computing 75
5.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.2 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.3.1 Threat Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.3.2 TPM-based Approach for Measuring and Attesting the OS Integrity . . 78
5.3.3 CHORS Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
5.4 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.4.1 Formally Specifying Security Protocols using SAPIC . . . . . . . . . 83
5.4.2 Formally Verifying SAPIC Specifications . . . . . . . . . . . . . . . . 85
5.5 Implementation and Verification . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.5.1 Specify and Verify the TPM-based Approach for Measuring and Attesting the OS Integrity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5.5.2 Specify and Verify the CHORS protocol . . . . . . . . . . . . . . . . . 90
5.6 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.7 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
5.7.1 Approaches for Specifying and Verifying Security Protocols . . . . . . 99
5.7.2 Cuckoo Attack Modeling. . . . . . . . . . . . . . . . . . . . . . . . . 100
5.7.3 Intel SGX Formal Verification . . . . . . . . . . . . . . . . . . . . . . 101
5.7.4 TPM Formal Verification . . . . . . . . . . . . . . . . . . . . . . . . . 101
5.7.5 Intel TXT Formal Verification . . . . . . . . . . . . . . . . . . . . . . 102
5.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6 Trusted-Lease 105
6.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.2 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.3 Overview of T-Lease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.3.1 Threat Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
6.3.2 Basic Lease Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6.3.3 T-Lease Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
6.4 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
6.4.1 Formally Specifying Distributed Systems using TLA+ . . . . . . . . . 114
6.4.2 Formally Verifying the TLA+ Specifications . . . . . . . . . . . . . . 114
6.5 Implementation and Verification . . . . . . . . . . . . . . . . . . . . . . . . . 115
6.5.1 Specifying the Basic Lease Protocol with Benign Enclave Interrupts . . 115
6.5.2 Malicious Change of Clock Values During Interrupts and the Corresponding T-Lease Defense Mechanisms . . . . . . . . . . . . . . . . . 121
6.5.3 Attacker attacks the atomicity of the Interrupt Detection Routine and
the Corresponding T-Lease Mechanisms . . . . . . . . . . . . . . . . . 128
6.5.4 Attacker Manipulates the Clock Frequency and the Corresponding T
Lease Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
6.5.5 T-Lease Protocol Progress-guarantees . . . . . . . . . . . . . . . . . . 136
6.6 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
6.7 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.7.1 Lease Modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
6.7.2 Distributed System Specifications and Verification . . . . . . . . . . . 139
6.8 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
7 SMV: Semantic Majority Voting 143
7.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
7.2 Contribution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
7.3 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
7.3.1 Semantic Majority Voting High-level Overview . . . . . . . . . . . . . 145
7.3.2 Fault model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
7.3.3 Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
7.4 Preliminaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
7.5 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
7.5.1 Lane Changing Simulation . . . . . . . . . . . . . . . . . . . . . . . . 149
7.5.2 Replication Semantics . . . . . . . . . . . . . . . . . . . . . . . . . . 154
7.6 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
7.6.1 Performance Overhead . . . . . . . . . . . . . . . . . . . . . . . . . . 159
7.6.2 The Effect of Non-determinism with Fault Injection. . . . . . . . . . . 161
7.7 Discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
7.8 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
7.9 Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
8 Conclusion and Future Work 171
Appendices 177
Bibliography 19
High Performance and Dependable Asynchronous Communication on Multi-Core Systems
No full textAsynchronous communication plays a crucial role in multi-threaded applications such as operating systems, databases, networks, and language runtimes, enabling data transfer, task distribution, and component decoupling. However, with the waning of Moore's Law and the rise of heterogeneous multi-core architectures, existing methods face challenges, including performance issues when dealing with cache and memory hierarchies and leveraging modern hardware instructions, as well as correctness issues due to the increasing complexity when coevolving with modern architectures (e.g., weak memory models).
This thesis investigates the problem of how to design and implement high-performance and dependable asynchronous communication components for multi-core systems and presents novel methods and algorithms to address these challenges. We have invented several queues, including block-based queue (BBQ), concurrent nested queue (CNQ), and block-based work-stealing queue (BWoS), which are verified and optimized using a model-checking-based framework. These queues have been successfully integrated into real-world applications, including DPDK, Linux IO_uring, Java GC, and Go and Rust runtimes. Our experiments demonstrate significant end-to-end performance improvement for industrial software over state-of-the-art approaches
Topology and Magnetism in 2-Dimensional van-der-Waals Materials
No full textIn this thesis, two-dimensional (2D) van der Waals materials have been explored, focusing on the encapsulation of graphene with hexagonal boron nitride (hBN), as well as detailed study of 2D magnets Cr2Ge2Te6 and CuCrP2S6. Graphene has been studied to establish the connection between its quantum Hall phase with the non-hermitian Hatano-Nelson model. Additionally, the thickness-dependent magnetism of Cr2Ge2Te6 has been studied and the exfoliation and oxidation study of CuCrP2S6 has been carried out.
Through the tunable electronic properties of graphene, specifically its ability to move between electron and hole side by applying back gate voltage, we demonstrate how the quantum Hall effect in graphene can proove a physical realization of non-Hermitian topological phase. By systematically measuring the resistance matrices of graphene in the quantum Hall regime and inverting them to the conductance matrices, it has been shown that the quantum Hall phase in graphene corresponds to the conductance matrix in Hatano-Nelson model, with the electron and hole side exhibiting chirality or non-chirality.
For Cr2Ge2Te4, the thickness-dependent magnetism has been studied through exfoliation and succesfully reached a thickness down to 4 nm. Using the magnetooptical Kerr method (MOKE), distinct variations in the hysteresis curve across different thicknesses have been observed. Notably, 8nm thick part of the flake exhibit highly coercive hysteresis, while down-to-a few layer part show no signal. For CuCrP2S6, a systematic degradation study has been conducted. Flakes were observed over the course of the year. AFM analysis confirmed the thickness remained stable for the first month, with no noticeable degradation. However, after a year, significant degradation was visible in optical images, indicating that Cu-CrP2S6 oxidizes in air over a long time scale