Quantitative Analysis of Arterial Spin Labeling FMRI Data Using a General Linear Model

Arterial spin labeling techniques can yield quantitative measures of perfusion by fitting a kinetic model to difference images (tagged-control). Because of the noisy nature of the difference images investigators typically average a large number of tagged versus control difference measurements over long periods of time. This averaging requires that the perfusion signal be at a steady state and not at the transitions between active and baseline states in order to quantitatively estimate activation induced perfusion. This can be an impediment for functional magnetic resonance imaging task experiments. In this work, we introduce a general linear model (GLM) that specifies Blood Oxygenation Level Dependent (BOLD) effects and arterial spin labeling modulation effects and translate them into meaningful, quantitative measures of perfusion by using standard tracer kinetic models. We show that there is a strong association between the perfusion values using our GLM method and the traditional subtraction method, but that our GLM method is more robust to noise

Dynamic Response of an Electron Storage Ring Magnet.

A combined experimental and numerical methodology was employed to investigate the dynamic response of the electron storage ring dipole magnets located in the Center for Advanced Microstructural Devices (CAMD) at Louisiana State University (L.S.U.). The magnet are highly anisotropic and can not be analysed for dynamic response without knowledge of the effective elastic properties. The theory of wave propagation in conjunction with finite element analysis was used to determine the variation of the effective modulus of elasticity magnets in question. The structure of the magnet was modeled with NASTRAN. A theoretical analysis was performede that supported the experimental variation of the modulus of elasticity with variation of residual clamping stress througout the magnet. The effect of damping on the effective modulus was also examined. The dynamic response of these magnets to their seismic input were analyzed. The path of the motion of the electron and its deviation from the expected path due to seismic input were determined

Quantitative Evaluation of Geared Manual Wheelchair Mobility in Individuals with Spinal Cord Injury: An Integrative Approach

The purpose of this dissertation is to quantify the effects of using geared wheelchair wheels on upper extremity biomechanics and energy expenditure during functional mobility tasks in individuals with spinal cord injury (SCI). The effects of using geared wheels on hand-rim biomechanics, glenohumeral joint dynamics, and shoulder muscle activity were investigated during manual wheelchair propulsion over tiled and carpeted level-floors and up a ramp in low gear (1.5:1) and standard gear (1:1) conditions. The results for the hand-rim biomechanics indicated that regardless of the terrain, using the geared wheels in the low gear condition significantly decreased the propulsion speed, stroke distance, and hand-rim kinetics, including the peak hand-rim resultant force, propulsive moment, and rate of the rise of the resultant force. The significant decrease in the normalized integrated hand-rim propulsive moment suggests that the low gear condition is less demanding than the standard gear condition, in spite of the higher repetition during propulsion in low gear. Analysis of the glenohumeral joint dynamics and shoulder muscle activity during geared manual wheelchair propulsion over carpeted floor showed that the peak glenohumeral joint inferior force and flexion moment, as well as the shoulder flexors muscle activity, decreased significantly during the low gear condition. Manual wheelchair users with SCI were tested during the six-minute push tests on passive wheelchair rollers to evaluate the effects of using geared wheels on energy expenditure. The results indicated that using geared wheels in the low gear condition significantly increased the energy cost of propulsion and decreased the intensity of wheelchair propulsion. The findings of this dissertation demonstrate that using geared wheels in comparison to standard wheels decreases the demands on the upper extremity of manual wheelchair users, which may ultimately help preserve upper limb function leading to higher levels of activity, independence and quality of life

Engineering Gold Nanoparticles And Their Use To Control Nucleation

This study focuses on fabrication of hybrid nanostructures using gold nanoparticles (AuNP) as seeds and partially oxidized potassium tetracyanoplatinate, known as Krogmann’s salt (KCP), and later this method will be employed to manufacture a prototype sensor for detecting different vapors. Nanocrystals are synthesized using electrochemical method with the aim to have more control over the size and shape of the charge transfer salt based on the seed mediated nucleation method. AuNP seeds are prepared on highly ordered pyrolytic graphite (HOPG) substrate by the electrocrystallization method. An aqueous solution of 0.05 to 1 mM Hydrogen tetrachloroaurate (HAuCl4) with 0.1 mM (Potassium chloride) KCl as the supporting electrolyte was prepared. The electrodeposition of the AuNPs was monitored by Cyclic Voltammetry (CV) and analyzed by Atomic Force Microscopy (AFM). The results show that the most dominant factor to control the AuNP size is the HAuCl4 concentration. Deposition time and applied potential are the other factors controlling the electrodeposition. The smallest particle size was observed with the lowest HAuCl4 concentration. The synthesis of K1.75Pt(CN)4.1.5H2O rods is conducted according to literature on bare HOPG with a concentration of 0.07 M of K2Pt(CN)4 in DI water and a potential pulse of 1.5V (vs SCE ) for 0.1s. Needle shaped crystals with a size range of 600 nm to 5µm in length and 100-500nm in width were synthesized on the bare HOPG. When the experiment was conducted with the same conditions on AuNP decorated HOPG, in result the average diameter and length of the rods were reduced significantly that matches our hypothesis based on seed-mediated nucleation theory. The results will help to have a better understanding of seed-mediated nucleation theory for producing nanoparticles of the desired size and shape, and also introduce a new way of manufacturing future nanosensors and nanoelectrods. Next, micro sized crystals were synthesized using the same method with longer deposition time on patterned Cr/Au electrodes. The conductivity of the KCP crystals was measured in exposure of different vapors. The results show dramatic conductivity change after introducing the vapors to the sensor, and also it shows a rapid respond and more sensitivity compare to commercial sensors .They proves that this prototype can be a reliable and cheap replacement of available sensors in different applications

Timing properties in real-time systems

This dissertation proposes a formalism for the specification and verification of timing properties of real-time systems. Reasoning about properties of a real-time system requires one to consider both relative and absolute timing of events. Relative timing concerns the order in which events occur, such as mutual exclusion and precedence constraint properties. Absolute timing concerns the stringent timing restrictions imposed on a system, such as a response time deadline or a minimum elapsed time between occurrences of two events. The approach is based on Real Time Logic (RTL), a logic invented primarily for the specification of both relative and absolute timing of events. The notion of an event occurrence is central to RTL; an event occurrence marks a point in time which is of significance to the behavior of a system. Hence, concurrency is modeled as a partial ordering of the event occurrences in the system. A system specification and a property to be verified can be expressed as arithmetical relations on algebraic expressions involving the event occurrences. To verify the property with respect to the system specification, we prove that the property is a theorem derivable from the specification. Relationship of RTL to Presburger Arithmetic is discussed and a verification technique based on inequality provers is explored. The dissertation also introduces a specification language, Modechart, for real-time systems. The semantics of Modechart is described in terms of RTL formulas. In Modechart, we make use of the concept of modes which can be thought of as partitioning the state space of a system. Intuitively, modes can be viewed as control information that impose structure on the operation of a system. Modes are arranged hierarchically. Furthermore, modes at the same level of hierarchy can be related in one of two ways: in series or in parallel. A transition can be specified between two modes in series, but no transition is allowed between modes in parallel. The language allows sporadic/periodic actions in modes as well as constructs for specifying timing constraints such as delays and deadlines on mode transitions. Verification procedures are introduced for showing a Modechart specification satisfies a property expressed as an RTL formula.Computer Science

Quantifying aesthetics of visual design applied to automatic design

In today\u27s Instagram world, with advances in ubiquitous computing and access to social networks, digital media is adopted by art and culture. In this dissertation, we study what makes a good design by investigating mechanisms to bring aesthetics of design from realm of subjection to objection. These mechanisms are a combination of three main approaches: learning theories and principles of design by collaborating with professional designers, mathematically and statistically modeling good designs from large scale datasets, and crowdscourcing to model perceived aesthetics of designs from general public responses. We then apply the knowledge gained in automatic design creation tools to help non-designers in self-publishing, and designers in inspiration and creativity. Arguably, unlike visual arts where the main goals may be abstract, visual design is conceptualized and created to convey a message and communicate with audiences. Therefore, we develop a semantic design mining framework to automatically link the design elements, layout, color, typography, and photos to linguistic concepts. The inferred semantics are applied to a design expert system to leverage user interactions in order to create personalized designs via recommendation algorithms based on the user\u27s preferences