THE IMPACT OF POSTTRAUMATIC STRESS DISORDER ON PERIPHERAL VASCULAR FUNCTION

The physiological manifestations of posttraumatic stress disorder (PTSD) have been associated with an increase in risk of cardiovascular disease (CVD) independent of negative lifestyle factors. Peripheral vascular dysfunction may be a mechanism by which PTSD increases CVD risk via increases in oxidative stress, inflammation, and/or sympathetic nervous system activity. PURPOSE: This study sought to examine peripheral vascular function in those with PTSD compared to age-matched controls. METHODS: Eight individuals with PTSD (5 women, 3 men; age 22 ± 2 years), and sixteen healthy controls (CON; 10 women, 6 men, 23 ± 2 years), participated in the study. Leg vascular function was assessed via passive leg movement (PLM) technique and evaluated with Doppler ultrasonography. PLM-induced increases in leg blood flow were quantified as peak change in blood flow from baseline (ΔPeak LBF) and blood flow area under the curve (LBF AUC). RESULTS: Significant differences in leg vascular function were revealed between groups. The PTSD group reported significantly lower ΔPeak LBF (PTSD: 294.16 ± 54.16; CON: 594.78 ± 73.70 ml∙min-1; p = 0.01) and LBF AUC (PTSD: 57.23 ± 24.37; CON: 169.92 ± 29.84 ml; p = 0.02) when compared to the CON group. CONCLUSION: This study revealed that lower limb vascular function is impaired in individuals with PTSD when compared to healthy counterparts.https://scholarscompass.vcu.edu/gradposters/1043/thumbnail.jp

A comparison of the electrical properties of polymer LEDs based on poly(thiophene)s and PPV-derivatives

This thesis describes the electrical properties of conjugated polymer LEDs. It is important to understand these electrical properties in detail for optimisation of the efficiency of the LEDs (the ratio between the amount of photons generated and the amount of charge carriers injected into the structure). It is very well known that proper alignment of the Ferrni-level position of the metallic electrodes to the molecular transport levels of the organic semiconductor enhances the efficiency considerably. This however is only the case if the electrical properties of the device are dominated by charge carrier injection from the contacts. This thesis shows that not all conjugated polymers could be optimised by reducing interfacial barrier heights, but that for some materials bulk electrical properties of the material are dominant. The single-layer and multi-layer device properties of several conjugated polymers [poly(thiophene)s and PPV-derivatives] are compared and this shows that the background concentration of charged species left from the synthesis procedure determines how dominant the bulk properties are in comparison to the contact properties.

The Coastal Zone Management Act: A Mixed Success

Coastal zones in the United States are becoming overpopulated and underlying ecosystems are being degraded. The ecosystem services that coastal zones provide will be compromised if we follow the current management path. As the population in these areas increases, so too does the amount of non-point source pollution. Integrated coastal zone management programs are needed to address non-point source pollution. Coastal zones are also in peril due to the current projections of sea level rise caused by climate change. A precautionary approach, such as that employed in Australia and New Zealand, must be used to protect coastal zones from the effects of global warming. The Coastal Zone Management Act (CZMA) of 1972 was created to preserve and protect coastal areas from pollution and overpopulation. The purpose of this paper is to examine the effectiveness of the CZMA and the challenges it will face going forward

Electrodeposition of Pure and Doped ZnO

A study of the electrodeposition of pure and doped zinc oxide from a basic solution was completed using SEM, EDS, UV-Vis, and XRD analysis. The presence of a highly ordered zinc oxide film was confirmed. The doping of zinc oxide films with 3, 5, and 10 at wt% chromium was documented. Tests were run to ensure the incorporation of chromium from solution and not the substrate which also contained chromium. Aluminum was doped into zinc oxide films at 3, 5, 10 and 20 at wt% but its presence could not be determined using these characterization techniques

Temporal contrast-dependent modeling of laser-driven solids - studying femtosecond-nanometer interactions and probing

Establishing precise control over the unique beam parameters of laser-accelerated ions from relativistic ultra-short pulse laser-solid interactions has been a major goal for the past 20 years. While the spatio-temporal coupling of laser-pulse and target parameters create transient phenomena at femtosecond-nanometer scales that are decisive for the acceleration performance, these scales have also largely been inaccessible to experimental observation. Computer simulations of laser-driven plasmas provide valuable insight into the physics at play. Nevertheless, predictive capabilities are still lacking due to the massive computational cost to perform these in 3D at high resolution for extended simulation times. This thesis investigates the optimal acceleration of protons from ultra-thin foils following the interaction with an ultra-short ultra-high intensity laser pulse, including realistic contrast conditions up to a picosecond before the main pulse. Advanced ionization methods implemented into the highly scalable, open-source particle-in-cell code PIConGPU enabled this study. Supporting two experimental campaigns, the new methods led to a deeper understanding of the physics of Laser-Wakefield acceleration and Colloidal Crystal melting, respectively, for they now allowed to explain experimental observations with simulated ionization- and plasma dynamics. Subsequently, explorative 3D3V simulations of enhanced laser-ion acceleration were performed on the Swiss supercomputer Piz Daint. There, the inclusion of realistic laser contrast conditions altered the intra-pulse dynamics of the acceleration process significantly. Contrary to a perfect Gaussian pulse, a better spatio-temporal overlap of the protons with the electron sheath origin allowed for full exploitation of the accelerating potential, leading to higher maximum energies. Adapting well-known analytic models allowed to match the results qualitatively and, in chosen cases, quantitatively. However, despite complex 3D plasma dynamics not being reflected within the 1D models, the upper limit of ion acceleration performance within the TNSA scenario can be predicted remarkably well. Radiation signatures obtained from synthetic diagnostics of electrons, protons, and bremsstrahlung photons show that the target state at maximum laser intensity is encoded, previewing how experiments may gain insight into this previously unobservable time frame. Furthermore, as X-ray Free Electron Laser facilities have only recently begun to allow observations at femtosecond-nanometer scales, benchmarking the physics models for solid-density plasma simulations is now in reach. Finally, this thesis presents the first start-to-end simulations of optical-pump, X-ray-probe laser-solid interactions with the photon scattering code ParaTAXIS. The associated PIC simulations guided the planning and execution of an LCLS experiment, demonstrating the first observation of solid-density plasma distribution driven by near-relativistic short-pulse laser pulses at femtosecond-nanometer resolution