Various Applications of Methods and Elements of Adaptive Optics

This volume is focused on a wide range of topics, including adaptive optic components and tools, wavefront sensing, different control algorithms, astronomy, and propagation through turbulent and turbid media

Autocalibration Region Extending Through Time: A Novel GRAPPA Reconstruction Algorithm to Accelerate 1H Magnetic Resonance Spectroscopic Imaging

Magnetic resonance spectroscopic imaging (MRSI) has the ability to noninvasively interrogate metabolism in vivo. However, excessively long scan times have thus far prevented its adoption into routine clinical practice. Generalized autocalibrating partially parallel acquisitions (GRAPPA) is a parallel imaging technique that allows one to reduce acquisition duration and use spatial sensitivity correlations to reconstruct the unsampled data points. The coil sensitivity weights are determined implicitly via a fully-sampled autocalibration region in k-space. In this dissertation, a novel GRAPPA-based algorithm is presented for the acceleration of 1H MRSI. Autocalibration Region extending Through Time (ARTT) GRAPPA instead extracts the coil weights from a region in k-t space, allowing for undersampling along each spatial dimension. This technique, by exploiting spatial-spectral correlations present in MRSI data, allows for a more accurate determination of the coil weights and subsequent parallel imaging reconstruction. This improved reconstruction accuracy can then be traded for more aggressive undersampling and a further reduction of acquisition duration. It is shown that the ARTT GRAPPA technique allows for approximately two-fold more aggressive undersampling than the conventional technique while achieving the same reconstruction accuracy. This accelerated protocol is then applied to acquire high-resolution brain metabolite maps in less than twenty minutes in three healthy volunteers at B0 = 7 T

Somaesthetics and Aesthetic Transactions: Art and Phenomenology Today

This thesis inquires into the application of Richard Shusterman’s somaesthetics with respect to contemporary art, through an analysis of the work of Yann Toma and Tatiana Trouvé included in the exhibition Aesthetic Transactions, 2012. In exploring somaesthetics in relation to art, this thesis addresses John Dewey’s aesthetics and idea of the consummatory experience, and Maurice Merleau-Ponty’s phenomenology with respect to art and experience as parts of the foundation of Shusterman’s ideas of somaesthetics. In today’s decentralized, global art world, can somaesthetics offer a means of understanding and maintaining art’s vitality for viewers and/or artists? In this thesis, I argue for somaesthetics’ potential utility in approaching contemporary art

The ESPAS e-infrastructure

ESPAS provides an e-Infrastructure to support access to a wide range of archived observations and model derived data for the near-Earth space environment, extending from the Earth's middle atmosphere up to the outer radiation belts. To this end, ESPAS will serve as a central access hub for researchers who wish to exploit multi-instrument multipoint data for scientific discovery, model development and validation, and data assimilation, among others. Observation based and model enhanced scientific understanding of the physical state of the Earth's space environment and its evolution is critical to advancing space weather and space climate studies, two very active branches of current scientific research. ESPAS offers an interoperable data infrastructure that enables users to find, access, and exploit near-Earth space environment observations from ground-based and spaceborne instruments and data from relevant models, obtained from distributed repositories. In order to facilitate efficient user queries ESPAS allows a highly flexible workflow scheme to select and request the desired data sets. ESPAS has the strategic goal of making Europe a leading player in the efficient use and dissemination of near-Earth space environment information offered by institutions, laboratories and research teams in Europe and worldwide, that are active in collecting, processing and distributing scientific data. Therefore, ESPAS is committed to support and foster new data providers who wish to promote the easy use of their data and models by the research community via a central access framework. ESPAS is open to all potential users interested in near-Earth space environment data, including those who are active in basic scientific research, technical or operational development and commercial applications

The Chronicle [April 6, 2009]

The Chronicle, April 6, 2009https://repository.stcloudstate.edu/chron/1705/thumbnail.jp

Coded Territories

This collection of essays provides a historical and contemporary context for Indigenous new media arts practice in Canada. The writers are established artists, scholars, and curators who cover thematic concepts and underlying approaches to new media from a distinctly Indigenous perspective. Through discourse and narrative analysis, the writers discuss a number of topics ranging from how Indigenous worldviews inform unique approaches to new media arts practice to their own work and specific contemporary works. Contributors include: Archer Pechawis, Jackson 2Bears, Jason Edward Lewis, Steven Foster, Candice Hopkins, and Cheryl L'Hirondelle

Cloud geometry for passive remote sensing

An important cause for disagreements between current climate models is lack of understanding of cloud processes. In order to test and improve the assumptions of such models, detailed and large scale observations of clouds are necessary. Passive remote sensing methods are well-established to obtain cloud properties over a large observation area in a short period of time. In case of the visible to near infrared part of the electromagnetic spectrum, a quick measurement process is achieved by using the sun as high-intensity light source to illuminate a cloud scene and by taking simultaneous measurements on all pixels of an imaging sensor. As the sun as light source can not be controlled, it is not possible to measure the time light travels from source to cloud to sensor, which is how active remote sensing determines distance information. But active light sources do not provide enough radiant energy to illuminate a large scene, which would be required to observe it in an instance. Thus passive imaging remains an important remote sensing method. Distance information and accordingly cloud surface location information is nonetheless crucial information: cloud fraction and cloud optical thickness largely determines the cloud radiative effect and cloud height primarily influences a cloud's influence on the Earth's thermal radiation budget. In combination with ever increasing spatial resolution of passive remote sensing methods, accurate cloud surface location information becomes more important, as the largest source of retrieval uncertainties at this spatial scale, influences of 3D radiative transfer effects, can be reduced using this information. This work shows how the missing location information is derived from passive remote sensing. Using all sensors of the improved hyperspectral and polarization resolving imaging system specMACS, a unified dataset, including classical hyperspectral measurements as well as cloud surface location information and derived properties, is created. This thesis shows how RGB cameras are used to accurately derive cloud surface geometry using stereo techniques, complementing the passive remote sensing of cloud microphysics on board the German High-Altitude Long-Range research aircraft (HALO). Measured surface locations are processed into a connected surface representation, which in turn is used to assign height and location to other passive remote sensing observations. Furthermore, cloud surface orientation and a geometric shadow mask are derived, supplementing microphysical retrieval methods. The final system is able to accurately map visible cloud surfaces while flying above cloud fields. The impact of the new geometry information on microphysical retrieval uncertainty is studied using theoretical radiative transfer simulations and measurements. It is found that in some cases, information about surface orientation allows to improve classical cloud microphysical retrieval methods. Furthermore, surface information helps to identify measurement regions where a good microphysical retrieval quality is expected. By excluding likely biased regions, the overall microphysical retrieval uncertainty can be reduced. Additionally, using the same instrument payload and based on knowledge of the 3D cloud surface, new approaches for the retrieval of cloud droplet radius exploiting measurements of parts of the polarized angular scattering phase function become possible. The necessary setup and improvements of the hyperspectral and polarization resolving measurement system specMACS, which have been developed throughout four airborne field campaigns using the HALO research aircraft are introduced in this thesis.Ein wichtiger Grund für Unterschiede zwischen aktuellen Klimamodellen sind nicht ausreichend verstandene Wolkenprozesse. Um die zugrundeliegenden Annahmen dieser Modelle zu testen und zu verbessern ist es notwendig detaillierte und großskalige Beobachtungen von Wolken durch zu führen. Methoden der passiven Fernerkundung haben sich für die schnelle Erfassung von Wolkeneigenschaften in einem großen Beobachtungsgebiet etabliert. Für den sichtbaren bis nahinfraroten Bereich des elektromagnetischen Spektrums kann eine schnelle Messung erreicht werden, in dem die Sonne als starke Lichtquelle genutzt wird und die Wolkenszene durch simultane Messung über alle Pixel eines Bildsensors erfasst wird. Da die Sonne als Lichtquelle nicht gesteuert werden kann, ist es nicht möglich die Zeit zu messen die von einem Lichtstrahl für den Weg von der Quelle zur Wolke und zum Sensor benötigt wird, so wie es bei aktiven Verfahren zur Distanzbestimmung üblich ist. Allerdings können aktive Lichtquellen nicht genügend Energie bereitstellen um eine große Szene gut genug zu beleuchten um diese Szene in einem kurzen Augenblick vollständig zu erfassen. Aus diesem Grund werden passive bildgebende Verfahren weiterhin eine wichtige Methode zur Fernerkundung bleiben. Trotzdem ist der Abstand zur beobachteten Wolke und damit der Ort der Wolke eine entscheidende Information: Wolkenbedeckungsgrad und die optische Dicke einer Wolke bestimmen einen Großteil des Strahlungseffektes von Wolken und die Höhe der Wolken ist der Haupteinflussfaktor von Wolken auf die thermische Strahlungsbilanz der Erde. Einhergehend mit der weiterhin zunehmenden Auflösung von passiven Fernerkundungsmethoden werden genaue Informationen über den Ort von Wolkenoberflächen immer wichtiger. Dreidimensionale Strahlungstransporteffekte werden auf kleineren räumlichen Skalen zum dominierenden Faktor für Fehler in Messverfahren für Wolkenmikrophysik. Dieser Einfluss auf die Messverfahren kann durch die Nutzung von Informationen über die Lage der Wolken reduziert und die Ergebnisse somit verbessert werden. Diese Arbeit zeigt, wie die fehlenden Ortsinformationen aus passiven Fernerkundungsmethoden gewonnen werden können. Damit kann ein vereinheitlichter Datensatz aller Sensoren des verbesserten specMACS-Systems für hyperspektrale und polarisationsaufgelöste Bilderfassung erstellt werden, in dem außer den gemessenen Strahlungsdichten auch die Positionen der beobachteten Wolkenoberflächen und daraus abgeleitete Größen enthalten sind. In dieser Arbeit wird gezeigt, wie RGB-Kameras genutzt werden, um mit Hilfe stereographischer Techniken die Geometrie der beobachteten Wolken ab zu leiten und so die Möglichkeiten zur passiven Fernerkundung auf dem Forschungsflugzeug HALO zu erweitern. Aus den so gemessenen Positionen der Wolkenoberflächen wird eine geschlossene Darstellung der Wolkenoberflächen berechnet. Dies ermöglicht es die Daten aus anderen passiven Fernerkundungsmethoden um Höhe und Ort der Messung zu erweitern. Außerdem ist es so möglich die Orientierung der Wolkenoberflächen und eine Schattenmaske auf Grund der nun bekannten Beobachtungsgeometrie zu berechnen. Das fertige System ist in der Lage, die sichtbaren Wolkenoberflächen aus Daten von einem Überflug zu rekonstruieren. Mit Hilfe theoretischer Strahlungstransportsimulationen und Messungen wird der Einfluss der neu gewonnenen Informationen auf bestehende Rekonstruktionsmethoden für Wolkenmikrophysik untersucht. In manchen Fällen helfen die neu gewonnenen Informationen direkt die Ergebnisse dieser Methoden zu verbessern und in jedem Fall ermöglichen es die Positionsdaten Bereiche zu identifizieren für die bekannt ist, dass bisherige Rekonstruktionsmethoden nicht funktionieren. Durch Ausschluss solcher Bereiche wird der Gesamtfehler von Mirkophysikrekonstruktionen weiterhin reduziert. Das aktuelle specMACS System ermöglicht auch polarisationsaufgelöste Messungen, wodurch eine sehr genaue Bestimmung der Wolkentropfengrößen möglich wird. Die nun verfügbaren Positionsdaten der Wolkenoberflächen helfen die Genauigkeit dieses Verfahrens deutlich zu verbessern. Die notwendigen Auf- und Umbauten des hyperspektralen und polarisationsauflösenden Messsystems specMACS, die während vier Flugzeuggestützer Messkampagnen auf dem Forschungsflugzeug HALO entwickelt wurden sind in dieser Arbeit beschrieben

Sketchbooks – A Comparative Analysis of the Use of Sketchbooks by Contemporary Artists

This qualitative research project aims to gain a theoretical and practical understanding of what role sketchbooks play in the creative practice of contemporary artists, and what their shared and individual sketchbook methods are. A comparative analysis of thirteen contemporary artists’ sketchbook practices is offered. During the course of the research the private and public nature of sketchbooks emerged as an important and engaging area of inquiry that helped narrow the focus of the research process and offered an entry point for the analysis. The methodology used was fundamentally that of artistic research that drew heavily upon the characteristics of artistic practice in the field of drawing; as well as from hermeneutics, (auto)ethnography, and phenomenological analysis, each of which informed my practice and processes. This research aims to be useful for those conducting research into sketchbooks, drawing, drawing and writing, the nature of artistic process, creativity and pedagogy. The outcomes of this research are presented in two parts, in the thesis text and the documentation of an exhibition. In the final analysis the outcome is a multi - layered and multi - voiced story that identifies individual and shared practices used by contemporary artists during the compilation of their sketchbooks. Both the research and resultant artwork aim to bring to the foreground the largely overlooked public aspect of the sketchbook and contribute to knowledge in the fields of drawing research, video installation art, archival research and interviewing in the context of artistic research. Throughout the project I used drawing and video practices as methods of investigating, interrogating and disseminating knowledge. Thirteen contemporary artists’ interviews were recorded as a core element of the primary research, then reconfigured as an artwork / video installation called Thirteen Narratives By Thirteen Artists About Their Sketchbooks