Global ETD Search

1	Macroscopic Patterning via Dynamic Self-assembly and Wrinkling Instability Kim, Hyun Suk 01 September 2012 (has links) My PhD work focuses on developing new methods to create the macroscopic patterns in a simple, robust, and versatile way. For macroscopic pattern formation, we first use flow coating as an assembly technique, uniquely balancing two driving forces: (i) evaporative deposition of nonvolatile solutes at a three-phase contact line and (ii) precision movement of a confined meniscus layer. This balance leads to the formation of line-based patterns that range in height and width from nanometers to microns, with lengths greater than centimeters. Moreover, we couple this deposition methodology with functional ligand chemistry on the nanoparticle surface, which allows us to create complex nanoparticle structures. By lifting crosslinked nanoparticle ribbons and ropes, exceptionally intriguing structures emanate from this process. The nanoparticle ribbons and ropes demonstrate a leap forward in nanomaterials fabrication, since the nanoscale properties are embedded within a macroscale object that can be manipulated with conventional methods and engineered into advanced technologies Using mechanical instability, we fabricate a simple, robust stimuli-responsive surface with periodic structures over a large area based upon osmotically-driven surface wrinkling. Although surface wrinkling has received considerable attention in the scientific literature, only a handful of papers have shown the ability to harness perhaps the greatest potential attribute of surface wrinkles: their active reversible nature. The ability to precisely control surface topographic morphologies in accordance with established scaling relationships opens a wide array of advanced materials applications, which do not rely upon cost-limiting fabrication techniques. Specifically, the surfaces respond to solvent exposure by developing well-defined topographic structures over laterally extensive areas due to osmotically-driven differential strains between a surface layer and underlying soft substrate. The observed wrinkling occurs spontaneously, forming hierarchical morphologies with controlled dimensions, and vanishes upon removal of the solvent driving force. The combined responsiveness and reversibility of wrinkling allow for the realization of functional devices, such as smart windows, smart microlens arrays, reversible channels in microfluidic devices. Moreover, by using thermal and osmotic approaches, we study the influence of geometry and material properties on surface instability such as cracking and wrinkling in a trilayer system consisting of a thin film on a soft foundation supported by a rigid substrate. evaporative self-assembly multicomponent patterning periodic patterns wrinkling Polymer Science
2	Dolování periodických vzorů / Periodic Patterns Mining Stríž, Rostislav January 2012 (has links) Data collecting and analysis are commonly used techniques in many sectors of today's business and science. Process called Knowledge Discovery in Databases presents itself as a great tool to find new and interesting information that can be used in a future developement. This thesis deals with basic principles of data mining and temporal data mining as well as with specifics of concrete implementation of chosen algorithms for mining periodic patterns in time series. These algorithms have been developed in a form of managed plug-ins for Microsoft Analysis Services -- service that provides data mining features for Microsoft SQL Server. Finally, we discuss obtained results of performed experiments focused on time complexity of implemented algorithms.
3	Neural basis and behavioral effects of dynamic resting state functional magnetic resonance imaging as defined by sliding window correlation and quasi-periodic patterns Thompson, Garth John 20 September 2013 (has links) While task-based functional magnetic resonance imaging (fMRI) has helped us understand the functional role of many regions in the human brain, many diseases and complex behaviors defy explanation. Alternatively, if no task is performed, the fMRI signal between distant, anatomically connected, brain regions is similar over time. These correlations in “resting state” fMRI have been strongly linked to behavior and disease. Previous work primarily calculated correlation in entire fMRI runs of six minutes or more, making understanding the neural underpinnings of these fluctuations difficult. Recently, coordinated dynamic activity on shorter time scales has been observed in resting state fMRI: correlation calculated in comparatively short sliding windows and quasi-periodic (periodic but not constantly active) spatiotemporal patterns. However, little relevance to behavior or underlying neural activity has been demonstrated. This dissertation addresses this problem, first by using 12.3 second windows to demonstrate a behavior-fMRI relationship previously only observed in entire fMRI runs. Second, simultaneous recording of fMRI and electrical signals from the brains of anesthetized rats is used to demonstrate that both types of dynamic activity have strong correlates in electrophysiology. Very slow neural signals correspond to the quasi-periodic patterns, supporting the idea that low-frequency activity organizes large scale information transfer in the brain. This work both validates the use of dynamic analysis of resting state fMRI, and provides a starting point for the investigation of the systemic basis of many neuropsychiatric diseases. fMRI Dynamic analysis Sliding window Sliding windows Resting state Default mode Functional connectivity Functional network Correlation Coherence Functional magnetic resonance imaging Local field potentials LFP Band-limited power BLP Inter-individual Intra-individual Spontaneous activity Brain Primary somatosensory cortex Rodent Rat Human Simultaneous experiments Neural basis Glial basis Neurons Astrocytes Vasomotion Hemodynamic response Dynamic Spatiotemporal dynamics Quasi-periodic patterns Brain networks Resting state networks Anesthesia Dexmedetomidine Isoflurane Awake Global signal Magnetic resonance imaging Brain Pathophysiology Brain mapping

1

Page generated in 0.0894 seconds