This work is motivated by two non-intuitive predictions of Quantum Mechanics: non-locality and contextuality. Non-locality is a phenomenon whereby interactions between spatially separated objects appear to be occurring faster than the speed of light. Contextuality is a phenomenon whereby the outcome of a measurement cannot be interpreted as the revelation of an intrinsic fixed property of the system being measured, but instead necessarily depends on the configuration of the measurement apparatus. Quantum Mechanics predicts non-local behavior in certain types of experiments collectively known as Bell tests. However, ruling out all possible alternative local theories is a subtle and demanding task. In this work, we lay out a mathematically-rigorous framework for analyzing Bell experiments. Using this framework, we derive the famous Clauser-Horne-Shimony-Holt (CHSH) inequality, an important constraint that is obeyed by all local theories and violated by Quantum Mechanics. We further demonstrate how to analyze the data of a CHSH experiment without assuming that successive experimental trials are independent and/or identically distributed. We also derive the Clauser-Horne (CH74) inequality, an inequality that is more well-suited for realistic Bell experiments using photons. We demonstrate a robust method for statistically analyzing the data of a CH74 experiment, and show how to calculate exact p-values for this analysis, improving on the previously-best-known (loose) upper bounds obtained from Hoeffding-style inequalities. The work concludes with an exploration of contextuality. The Kochen-Specker theorem -- a result demonstrating the contextual nature of Quantum Mechanics -- is applied to resolve a conjecture in Domain Theory regarding the spectral order on quantum states. / acase@tulane.edu

Current therapeutic options for ischemic stroke are limited to tissue plasminogen activator and mechanical clot removal therapies. Diazoxide (DZ) is a mitochondrial ATP-sensitive potassium channel opener and is protective in models of brain ischemia, but the signaling pathways involved are unknown. The mammalian target of rapamycin (mTOR) is a master regulator of protein synthesis and is involved in protection against cerebral ischemia. The neuronal nitric oxide synthase (nNOS) pathway has also been shown to provide protection from ischemic insults. Additionally, mitochondrial respiratory status has not been investigated. I examined the role of the mTOR pathway, the nNOS pathway, and mitochondrial respiration in delayed DZ-induced preconditioning of neurons. I cultured rat primary cortical neurons and simulated ischemic stroke using oxygen-glucose deprivation (OGD) for 3 h followed by re-oxygenation. Viability, mitochondrial membrane potential, reactive oxygen species (ROS) measurements, and western blots were performed. The mTOR pathway was inhibited by rapamycin, Torin-1, and S6K targeted silencing RNA. The NOS pathway was inhibited by L-NAME. NO-donors SNP and DEANONOate (DEANO) were applied to rescue the effects of L-NAME. Mitochondrial oxygen consumption rate (OCR) was measured in intact neurons by serial injections of oligomycin, FCCP, and antimycin/rotenone. OGD decreased viability by 50 percent, depolarized mitochondria, and reduced mitochondrial respiration whereas DZ improved viability to 75 percent and suppressed reactive oxygen species production, but did not restore mitochondrial membrane potential after OGD. Diazoxide also increased phosphorylation of protein kinase B, mTOR, and S6K. Rapamycin, Torin-1, and S6K targeted siRNA abolished the protective effects of DZ. Co-application of L-NAME with DZ prevented preconditioning whereas adding SNP or DEANO along with L-NAME and DZ restored protection. Diazoxide increased phosphorylated nNOS. Interestingly, co-application of LNAME with DZ blocked the phosphorylation of nNOS as well as S6K. The ratio of phosphorylated/total Akt and mTOR were not significantly altered with L-NAME co-application. Diazoxide altered OCR 24 and 48 h after the ischemic period. Diazoxide had no acute effect on OCR but increased ECAR significantly. Activation of the mTOR and nNOS pathways is critical for DZ preconditioning in neurons. Furthermore, OCR is modified by the DZ-induced preconditioning of neurons. / acase@tulane.edu

acase@tulane.edu

acase@tulane.edu

The retina is a sensory tissue that converts optical images into neural signals known as light responses. Light responses are transmitted from photoreceptors to bipolar cells to retinal ganglion cells (RGCs) in parallel pathways specific for either light increments or light decrements. This improves vision by doubling the retina’s dynamic range and increasing contrast sensitivity. Research has shown that Off pathways, which are sensitive to light decrements, are likely modulated by the activity of metabotropic glutamate receptor 6 (mGluR6) receptors, cannabinoid 1 receptors (CB1Rs), and γ-aminobutyric acid C (GABAC) receptors. In this dissertation, I investigate how these neurotransmitter receptors modulate Off responses in the retina by performing whole-cell recordings of mouse RGCs. On bipolar cells express mGluR6 receptors, a type of glutamate receptor that hyperpolarizes bipolar cells when bound to glutamate. Previous research has shown that these receptors modulate Off responses under dark adaptation, but effects under light adaptation were unclear. My research has shown that mGluR6 receptor agonist DL-2-amino-4-phosphonobutyric acid (APB) decreases light-evoked Off responses under light adaptation by disrupting dopaminergic transmission between amacrine cells and Off bipolar cells. CB1Rs are localized to many cell types including cone and bipolar cell axon terminals, each of which release glutamate. Research primarily in brain has shown that cannabinoid receptor activation prevents neurotransmitter release from the presynapse. This has led to the hypothesis that CB1R activation would decrease glutamate release in Off pathways and attenuate Off responses. My research shows that CB1R agonists differentially modulate Off responses. Based on my results, I suggest that CB1R agonists increase light-evoked Off responses in one population of RGCs by reducing GABA transmission between GABAergic amacrine cells and Off bipolar cells. GABAergic amacrine cells feed back onto bipolar cell axon terminals that express GABAC receptors. Previous research has shown that GABAC receptor antagonist (1,2,5,6-tetrahydropyridin-4-yl)methylphosphinic acid (TPMPA) alters On responses, but effects on Off responses are unclear. I show that TPMPA modulates kinetics of both On and Off responses recorded from On-Off RGCs. All together, the results in this dissertation indicate that mGluR6 receptors, CB1Rs, and GABAC receptors modulate Off responses, and therefore vision. / acase@tulane.edu

In rodents, spatial learning and memory is contingent upon examining the relationships between cues in a three-dimensional environment. Although multiple brain structures are involved, the hippocampus serves as the epicenter of spatial information processing. Alternatively, on certain dual-solution navigational tasks, reliance on either a hippocampus-dependent place learning strategy or striatum-dependent response or stimulus-response learning strategy can be used to locate a goal. However, factors that dysregulate hippocampus function result in both poorer performance on spatial tasks and a shift toward adopting striatum-dependent learning strategies. Because gonadal hormones, affective states, and cholinergic neurotransmission modulate hippocampus function, the goal of the current study was to gain a greater understanding of how these factors impact spatial cognition and learning strategy preference. Relative to female rats, male rats performed better during the learning phase of a dual-solution learning task and exhibited a greater preference for a place learning strategy. Notably, in female rats, ovarian hormones modulated both spatial cognition and learning strategy preference, effects that likely involved activation of the putative estrogen membrane receptor GPR30. Alternatively, in male rats, spatial learning and memory, but not the preference for a place learning strategy, was attenuated by the removal of testicular hormones, an effect abrogated by testosterone treatment. Furthermore, for male rats, higher levels of trait anxiety and exposure to multiple reminders of a stressor were associated with a greater reliance on striatum-based learning strategies. From a neurochemical standpoint, the preference for a striatum-based learning strategy in male rats was associated with lower levels of choline acetyltransferase in the hippocampus, which indicates that the cholinergic system is involved in learning strategy preference. However, antagonism of muscarinic receptors in the hippocampus caused a learning impairment in male rats on the same dual-solution learning task, which indicates that cholinergic neurotransmission in the hippocampus is necessary for learning a task in which the striatum also provides solution. Identifying factors such as stress exposure or gonadal hormones that alter the cholinergic integrity of the hippocampus is an important step in generating therapeutic strategies designed to treat individuals suffering from cogniti / acase@tulane.edu

acase@tulane.edu

PURPOSE. To image the fundus non-invasively at two different penetration depths using a multispectral imaging system. Monochromatic images at visible spectrum wavelengths and near-infrared wavelengths were qualitatively assessed for choroidal visibility. These images were used calculate oxygen saturation in retinal tissue, optic nerve head tissue, vein, and choroidal tissue in healthy controls and glaucoma patients. METHODS. A fundus camera-based multispectral snapshot oximeter imaged the fundus of healthy subjects and patients with varying ophthalmological pathology. The images of healthy controls and glaucoma patients were analyzed to determine oxygen saturation in the optic nerve head cup and rim, superficial and deep vein, macula and choroidal tissue. RESULTS. Visible: Average oxygen saturation for the ONH cup was 65 ± 6 percent for healthy controls and 61 ± 10 percent for glaucoma patients. For the ONH rim, it was 67 ± 3 percent for healthy controls and 64 ± 17 percent for glaucoma patients. For the vein, it was 67 ± 15 percent for healthy controls and 56 ± 22 percent for glaucoma patients. For the macula, it was 87 ± 10 percent for healthy controls and 93 ± 1 percent for glaucoma patients. NIR: The average oxygen saturation for the vein was 66 ± 20 percent for healthy controls, 58 ± 0.4 percent for glaucoma suspects and 54 ± 17 percent for glaucoma patients. For the choroidal tissue below the macula, it was 99 ± 5 percent in healthy controls and 81 ± 8 percent in glaucoma patients. CONCLUSIONS. Choroidal visibility is enhanced in near infrared monochromatic images from visible spectrum monochromatic images. Oxygen saturation results were lower in glaucoma patients for all anatomical areas analyzed except the avascular macula. / acase@tulane.edu

Molecular beam methods provide rich possibilities for producing and studying novel species. These can include (1) clusters that would not be accessible in conventional gas phase chemistry and (2) generation and stabilization of reactive species. The methods that allow for (2) can be extended to (3) survey of evolving product chemistry following an initial fast impulse (photolysis, pyrolysis, electrical discharge) on some reactant. The projects undertaken touch on all three of these areas, but the centerpiece and most challenging project applies to the production, for the first time, of several novel organosilicon species. We first present an efficient molecular beam method of silylene production, a method meant to be used for the study of silylene chemistry. A particular goal was to produce a silanone. We present evidence that a silanone has been produced. Of even greater interest is the possible molecular beam production of small disilynes. This development would finally open the future opportunity to study these species in detail. Key to our approach here was the use of laser ablation of several different selected custom synthesized precursors. Based on past work, our expectation was that certain bonds in the precursors would selectively be broken, leading to the production of disilynes that then would be stabilized in cold gas expansions. For three different precursors, we present consistent evidence that the target disilynes were in fact produced. These conclusions were not clear in our initial analysis of the data; only a later and different form of analysis led to convincing evidence that the experiments were in fact successful. Because the main component of the intended project did not at first seem to have been successful, work in several other areas was carried out, related to themes (1) and (3). Related to (1) was methods development, demonstrating the ability to produce clusters of porphyrin and porphyrin-C60, for later extended study. For (3), study was carried out on the possible role of halogen adducts on alkylbenzenes in inhibiting PAH formation following corona discharge. Similarly for (3), method development was carried out to enable to study early product chemistry following the pyrolysis of triacylglycerols (triglycerides). / acase@tulane.edu

The interactions and feedbacks among climate, tectonics and surface erosion are complex but fundamental in geomorphological studies, and the mechanisms that control these processes are still not well understood. This thesis uses numerical models to address the specific question of how spatial rainfall patterns impact bedrock incision and the morphology of fluvial landscapes. This thesis includes three major chapters. In the first major chapter, I perform a series of model experiments to explore the impact of orographic rainfall on channel profile incision under different tectonic conditions. I find that the pattern of rainfall gradients may be more clearly reflected in transient channel profiles than in steady-state profiles. I apply the model to explore how rainfall patterns may lead to the convex upstream and concave downstream channel profiles on the wet side of Kohala, Hawaii. I find that if rainfall gradients lead to a gradient in bedrock erodibility, in addition to discharge variability, climate could explain the complex morphology of these channels. In the second major chapter, I integrate a linear orographic precipitation module into the CHILD landscape evolution model, providing a 2-D quantitative tool to explore the interactions between orographic rainfall and landscape evolution. Using the coupled model, I find that spatial rainfall patterns can affect the channel profile and planform morphologies, and when considered as a whole, the profiles of smaller channels with relatively uniform rainfall may more clearly illustrate rainfall patterns than those of larger channels that flow across rainfall gradients. I also observe a quantifiable change in network characteristics between landscapes with uniform and non-uniform rainfall. In the third major chapter, I employ the CHILD landscape evolution model to explore the mechanisms that control the characteristic length of hillslopes and valley spacing of fluvial channels. I find that the characteristic length is a primary control on the valley spacing of different order streams, and the valley spacing ratio is also well constrained by the counterbalance between the characteristic length and the stream order of dominant channels. However, factors such as initial topography and orographic precipitation likely impact network organization and the valley spacing ratio. / acase@tulane.edu