Viral Strain on the System: Organizational Differences in Healthcare Systems and the Control of Infectious Disease Crises

HonorsPolitical ScienceUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/169408/1/pulkakim.pd

Microvascular Corrosion Casting in the Study of Tumor Vascularity: A Review

Tumor blood flow is dependent on the structure and three-dimensional (3-D) architecture of the vascular network. The latter can be best studied by scanning electron microscopy of microvascular corrosion casts. However, literature reviews show that nearly all studies using this technique render comparisons of different tumors more difficult since they are mainly based on descriptive terms that might lead to misunderstandings. Qualitative comparisons of 13 experimental and 3 human primary tumors of different origin show a high degree of similarity in the vasculature. Quantitative analysis of these casts reveals similar ranges of parameters such as diameters, intervascular and interbranching distances. Diameters of vessels with capillary wall structure range from 6 μm to 55 μm in the human primary tumors (renal clear cell carcinoma, basalioma), and from 5 μm to 80 μm in xenografted tumors (sarcomas, colon carcinoma). Intervascular distances in the human primary tumors range from 2 μm to 52 μm, and from 11 μm to 105 μm in the xenografts. Interbranching distances range from 34 μm to 258 μmin the former, and from 11 μm to 160 μmin the latter. Both qualitative and quantitative analyses of tumor microvascular corrosion casts enable pathophysiological conclusions to be drawn and contribute to a better understanding of tumor vascularity

Platform Design and Electronic Word-of-Mouth Adaptability: A Construal Level Perspective

Drawing on the construal level theory, this thesis examines how two platform design features (structural complexity and length requirement) may impact eWOM favourability. Converging evidence from five lab studies and a field study indicates that a structurally complex (vs. structurally simple) design and a high-word-count (vs. low-word-count) design each induce review content lower in eWOM favourability. This research contributes to the bourgeoning eWOM literature by highlighting the significance of review platform design

Ethylene Synthesis and Sensitivity in Crop Plants

The gaseous plant hormone ethylene is a small molecule that regulates developmental change. Research was conducted in three areas: sensitivity, synthesis, and alterations to synthesis. Vegetative pea plants were more sensitive than radish plants to atmospheric ethylene. Light intensity did not affect ethylene sensitivity. Ethylene synthesis rates were measured for unstressed cotton, corn, soybean, and tomato plants. The per-plant ethylene synthesis rate ranged from 0.1-80 pmol plant-1 s-1. However, when normalized to net photosynthetic rate, this range was 1-4 µmol of ethylene synthesis per mol of CO2 uptake. Diurnal cycles in ethylene synthesis were present in all crops studied. These cycles were disrupted by drought stress and were attenuated when synthesis rates underwent large changes. Drought stress decreased synthesis in cotton. Flooded corn and soybean had increased synthesis. Blocked perception had no effect on ethylene synthesis or net photosynthetic rate in healthy unstressed plants

A whole-body Fast Field-Cycling scanner for clinical molecular imaging studies

The authors would like to thank the clinical teams of the Royal Aberdeen Infirmary for their support, in particular Dr German Guzman-Guttierez, Mr Paddy Ashcroft, Dr Tanja Gagliardi, Prof Steven Heys, Prof Alison Murray and Prof Graeme Murray. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 668119 (project “IDentIFY”).Peer reviewedPublisher PD

The impact of vestibular modulations on whole brain structure and function in humans

The vestibular system is a sensory system that monitors active and passive headmovements while at the same time permanently sensing gravity. Vestibular information is important for maintaining balance and stabilisation of vision and ultimately for general orientation in space. A distributed set of cortical vestibular regions process vestibular sensory information, together with other sensory and motor signals. How these brain regions are influenced by or interact with each other, and how this depends on the context in which the system is acting is not well understood. In my research I investigated the whole brain consequences of different vestibular sensory contexts by means of structural and functional magnetic resonance (MR) imaging on three different time scales (long-term, short-term, and medium-term). For the long-term time scale, I investigated functional brain connectivity in individuals experiencing a type of chronic dizziness that cannot be explained by structural damage within the nervous system. These patients exhibit chronic or long-term alterations in their processing of vestibular information, which leads to dizziness and vertigo. I found altered sensory and cerebellar network connectivity when they experience a dizziness-provoking stimulus. These two networks contain, but are not limited to, vestibular processing regions, demonstrating the importance of a whole-brain approach. The alterations correspond the notion that these patients have dysfunctional stimulus expectations. The short-term vestibular processing I investigated was the effect of artificial vestibular stimulation, which is frequently used in vestibular research and treatment. For this, I analysed functional network connectivity in healthy participants. I found that short-term vestibular stimulation does not cause a cortical functional reorganisation, although a nociceptive stimulus, which was matched for the somatosensory component of this stimulation, led to a reorganisation. The fact that cortical reorganisation does not occur during exclusively vestibular stimulation may reflect subconscious nature of vestibular processing in that it does not induce a different internal brain state. On the medium-term time scale, I investigated whole-brain structural changes as a result of gravity. Astronauts that travel to space for extended periods of time experience several physiological symptoms also affecting the fluid exchange of the brain. To characterise if these fluid exchanges also affect size of the spaces around brain blood vessels (perivascular spaces), I developed a semi-automatic detection pipeline which requires only one type of structural MR image. I found that space travellers have enlarged perivascular spaces even before their mission, when compared to a control population. These spaces were to a small extend further increased shortly after a long duration space flight of 6 months. Astronaut training thus contributes to structural changes in the whole brain in combination with long-duration space flight. This further suggests that additional contextual factors such as sleep quality should be considered in the future. Overall, in my thesis I show that investigating the whole brain during different vestibular modulations provides additional and novel insights about the underlying neural processes. I found that long-term vestibular states have an impact on functional networks, whilst short-term vestibular modulations do not seem to impact functional network organisation. In addition, I quantified the structural impact of microgravity and astronaut training in the whole brain using a new analysis pipeline. In the future, I expect that new advancements in the field of neuroimaging analysis, such as high sampling of individuals and dynamic network analysis will advance the field. This will potentially also provide new means to monitor disease progression or intervention success

Nonlinear layered lattice model and generalized solitary waves in imperfectly bonded structures

We study nonlinear waves in a two-layered imperfectly bonded structure using a nonlinear lattice model. The key element of the model is an anharmonic chain of oscillating dipoles, which can be viewed as a basic lattice analog of a one-dimensional macroscopic waveguide. Long nonlinear longitudinal waves in a layered lattice with a soft middle or bonding layer are governed by a system of coupled Boussinesq-type equations. For this system we find conservation laws and show that pure solitary waves, which exist in a single equation and can exist in the coupled system in the symmetric case, are structurally unstable and are replaced with generalized solitary waves