Extracting scene and object information from natural stimuli: the influence of scene structure and eye movements

When we observe a scene in our daily lives, our brains seemingly effortlessly extract various aspects of that scene. This can be attributed to different aspects of the human visual system, including but not limited to (1) its tuning to natural regularities in scenes and (2) its ability to bring different parts of the visual environment into focus via eye movements. While eye movements are a ubiquitous and natural behavior, they are considered undesirable in many highly controlled visual experiments. Participants are often instructed to fixate but cannot always suppress involuntary eye movements, which can challenge the interpretation of neuroscientific data, in particular for magneto- and electroencephalography (M/EEG). This dissertation addressed how scene structure and involuntary eye movements influence the extraction of scene and object information from natural stimuli. First, we investigated when and where real-world scene structure affects scene-selective cortical responses. Second, we investigated whether spatial structure facilitates the temporal analysis of a scene’s categorical content. Third, we investigated whether the spatial content of a scene aids in extracting task-relevant object information. Fourth, we explored whether the choice of fixation cross influences eye movements and the classification of natural images from EEG and eye tracking. The first project showed that spatial scene structure impacts scene-selective neural responses in OPA and PPA, revealing genuine sensitivity to spatial scene structure starting from 255 ms, while scene-selective neural responses are less sensitive to categorical scene structure. The second project demonstrated that spatial scene structure facilitates the extraction of the scene’s categorical content within 200 ms of vision. The third project showed that coherent scene structure facilitates the extraction of object information if the object is task-relevant, suggesting a task-based modulation. The fourth project showed that choosing a centrally presented bullseye instead of a standard fixation cross reduces eye movements on the single image level and subtly removes systematic eye movement related activity in M/EEG data. Taken together, the results advanced our understanding of (1) the impact of real-world structure on scene perception as well as the extraction of object information and (2) the influence of eye movements on advanced analysis methods.Wenn wir in unserem täglichen Leben eine Szene beobachten, extrahiert unser Gehirn scheinbar mühelos verschiedene Aspekte dieser Szene. Dies kann auf verschiedene Aspekte des menschlichen Sehsystems zurückgeführt werden, unter anderem auf (1) seine Ausrichtung auf natürliche Regelmäßigkeiten in Szenen und (2) seine Fähigkeit, verschiedene Teile der visuellen Umgebung durch Augenbewegungen in den Fokus zu bringen. Obwohl Augenbewegungen ein allgegenwärtiges und natürliches Verhalten sind, werden sie in vielen stark kontrollierten visuellen Experimenten als unerwünscht angesehen. Die Teilnehmer werden oft angewiesen, zu fixieren, können aber unwillkürliche Augenbewegungen nicht immer unterdrücken, was die Interpretation neurowissenschaftlicher Daten, insbesondere der Magneto- und Elektroenzephalographie (M/EEG), in Frage stellen kann. In dieser Dissertation wurde untersucht, wie Szenenstruktur und unbewusste Augenbewegungen die Extraktion von Szenen- und Objektinformationen aus natürlichen Stimuli beeinflussen. Zunächst untersuchten wir, wann und wo die Struktur einer realen Szene die szenenselektiven kortikalen Reaktionen beeinflusst. Zweitens untersuchten wir, ob die räumliche Struktur die zeitliche Analyse des kategorialen Inhalts einer Szene erleichtert. Drittens untersuchten wir, ob der räumliche Inhalt einer Szene bei der Extraktion aufgabenrelevanter Objektinformationen hilft. Viertens untersuchten wir, ob die Wahl des Fixationskreuzes die Augenbewegungen und die Klassifizierung natürlicher Bilder aus EEG und Eye-Tracking beeinflusst. Das erste Projekt zeigte, dass sich die räumliche Szenenstruktur auf szenenselektive neuronale Reaktionen in OPA und PPA auswirkt, wobei eine echte Empfindlichkeit für räumliche Szenenstrukturen ab 255 ms festgestellt wurde, während szenenselektive neuronale Reaktionen weniger empfindlich auf kategoriale Szenenstrukturen reagieren. Das zweite Projekt zeigte, dass die räumliche Szenenstruktur die Extraktion des kategorialen Inhalts der Szene innerhalb von 200 ms nach dem Sehen erleichtert. Das dritte Projekt zeigte, dass eine kohärente Szenenstruktur die Extraktion von Objektinformationen erleichtert, wenn das Objekt aufgabenrelevant ist, was auf eine aufgabenbezogene Modulation hindeutet. Das vierte Projekt zeigte, dass die Wahl eines zentral präsentierten Bullauges anstelle eines Standard-Fixationskreuzes Augenbewegungen auf Einzelbildebene reduziert und systematische Augenbewegungsaktivität in M/EEG-Daten auf subtile Weise beseitigt. Zusammengenommen haben die Ergebnisse unser Verständnis (1) der Auswirkungen der Struktur der realen Welt auf die Wahrnehmung der Szene und die Extraktion von Objektinformationen und (2) des Einflusses von Augenbewegungen auf fortgeschrittene Analysemethoden verbessert

Advanced Fault Diagnosis and Health Monitoring Techniques for Complex Engineering Systems

Over the last few decades, the field of fault diagnostics and structural health management has been experiencing rapid developments. The reliability, availability, and safety of engineering systems can be significantly improved by implementing multifaceted strategies of in situ diagnostics and prognostics. With the development of intelligence algorithms, smart sensors, and advanced data collection and modeling techniques, this challenging research area has been receiving ever-increasing attention in both fundamental research and engineering applications. This has been strongly supported by the extensive applications ranging from aerospace, automotive, transport, manufacturing, and processing industries to defense and infrastructure industries

2022 Review of Data-Driven Plasma Science

Data-driven science and technology offer transformative tools and methods to science. This review article highlights the latest development and progress in the interdisciplinary field of data-driven plasma science (DDPS), i.e., plasma science whose progress is driven strongly by data and data analyses. Plasma is considered to be the most ubiquitous form of observable matter in the universe. Data associated with plasmas can, therefore, cover extremely large spatial and temporal scales, and often provide essential information for other scientific disciplines. Thanks to the latest technological developments, plasma experiments, observations, and computation now produce a large amount of data that can no longer be analyzed or interpreted manually. This trend now necessitates a highly sophisticated use of high-performance computers for data analyses, making artificial intelligence and machine learning vital components of DDPS. This article contains seven primary sections, in addition to the introduction and summary. Following an overview of fundamental data-driven science, five other sections cover widely studied topics of plasma science and technologies, i.e., basic plasma physics and laboratory experiments, magnetic confinement fusion, inertial confinement fusion and high-energy-density physics, space and astronomical plasmas, and plasma technologies for industrial and other applications. The final section before the summary discusses plasma-related databases that could significantly contribute to DDPS. Each primary section starts with a brief introduction to the topic, discusses the state-of-the-art developments in the use of data and/or data-scientific approaches, and presents the summary and outlook. Despite the recent impressive signs of progress, the DDPS is still in its infancy. This article attempts to offer a broad perspective on the development of this field and identify where further innovations are required

Dynamical Systems

Complex systems are pervasive in many areas of science integrated in our daily lives. Examples include financial markets, highway transportation networks, telecommunication networks, world and country economies, social networks, immunological systems, living organisms, computational systems and electrical and mechanical structures. Complex systems are often composed of a large number of interconnected and interacting entities, exhibiting much richer global scale dynamics than the properties and behavior of individual entities. Complex systems are studied in many areas of natural sciences, social sciences, engineering and mathematical sciences. This special issue therefore intends to contribute towards the dissemination of the multifaceted concepts in accepted use by the scientific community. We hope readers enjoy this pertinent selection of papers which represents relevant examples of the state of the art in present day research. [...

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

On Foundations of Protecting Computations

Information technology systems have become indispensable to uphold our way of living, our economy and our safety. Failure of these systems can have devastating effects. Consequently, securing these systems against malicious intentions deserves our utmost attention. Cryptography provides the necessary foundations for that purpose. In particular, it provides a set of building blocks which allow to secure larger information systems. Furthermore, cryptography develops concepts and tech- niques towards realizing these building blocks. The protection of computations is one invaluable concept for cryptography which paves the way towards realizing a multitude of cryptographic tools. In this thesis, we contribute to this concept of protecting computations in several ways. Protecting computations of probabilistic programs. An indis- tinguishability obfuscator (IO) compiles (deterministic) code such that it becomes provably unintelligible. This can be viewed as the ultimate way to protect (deterministic) computations. Due to very recent research, such obfuscators enjoy plausible candidate constructions. In certain settings, however, it is necessary to protect probabilistic com- putations. The only known construction of an obfuscator for probabilistic programs is due to Canetti, Lin, Tessaro, and Vaikuntanathan, TCC, 2015 and requires an indistinguishability obfuscator which satisfies extreme security guarantees. We improve this construction and thereby reduce the require- ments on the security of the underlying indistinguishability obfuscator. (Agrikola, Couteau, and Hofheinz, PKC, 2020) Protecting computations in cryptographic groups. To facilitate the analysis of building blocks which are based on cryptographic groups, these groups are often overidealized such that computations in the group are protected from the outside. Using such overidealizations allows to prove building blocks secure which are sometimes beyond the reach of standard model techniques. However, these overidealizations are subject to certain impossibility results. Recently, Fuchsbauer, Kiltz, and Loss, CRYPTO, 2018 introduced the algebraic group model (AGM) as a relaxation which is closer to the standard model but in several aspects preserves the power of said overidealizations. However, their model still suffers from implausibilities. We develop a framework which allows to transport several security proofs from the AGM into the standard model, thereby evading the above implausi- bility results, and instantiate this framework using an indistinguishability obfuscator. (Agrikola, Hofheinz, and Kastner, EUROCRYPT, 2020) Protecting computations using compression. Perfect compression algorithms admit the property that the compressed distribution is truly random leaving no room for any further compression. This property is invaluable for several cryptographic applications such as “honey encryption” or password-authenticated key exchange. However, perfect compression algorithms only exist for a very small number of distributions. We relax the notion of compression and rigorously study the resulting notion which we call “pseudorandom encodings”. As a result, we identify various surprising connections between seemingly unrelated areas of cryptography. Particularly, we derive novel results for adaptively secure multi-party computation which allows for protecting computations in distributed settings. Furthermore, we instantiate the weakest version of pseudorandom encodings which suffices for adaptively secure multi-party computation using an indistinguishability obfuscator. (Agrikola, Couteau, Ishai, Jarecki, and Sahai, TCC, 2020