Using Non-Invasive Multi-Spectral Imaging to Quantitatively Assess Tissue Vasculature

This research describes a non-invasive, non-contact method used to quantitatively analyze the functional characteristics of tissue. Multi-spectral images collected at several near-infrared wavelengths are input into a mathematical optical skin model that considers the contributions from different analytes in the epidermis and dermis skin layers. Through a reconstruction algorithm, we can quantify the percent of blood in a given area of tissue and the fraction of that blood that is oxygenated. Imaging normal tissue confirms previously reported values for the percent of blood in tissue and the percent of blood that is oxygenated in tissue and surrounding vasculature, for the normal state and when ischemia is induced. This methodology has been applied to assess vascular Kaposi's sarcoma lesions and the surrounding tissue before and during experimental therapies. The multi-spectral imaging technique has been combined with laser Doppler imaging to gain additional information. Results indicate that these techniques are able to provide quantitative and functional information about tissue changes during experimental drug therapy and investigate progression of disease before changes are visibly apparent, suggesting a potential for them to be used as complementary imaging techniques to clinical assessment

PREDICTION OF THE ONSET OF DAMAGE IN UNI-DIRECTIONAL LAMAINATES UNDER TRANSVERSE IMPACT LOADING USING FINITE ELEMENT ANALYSIS

Thesis (Master's)--University of Washington, 2016-12With the increase in application of Carbon Fiber Reinforced Plastics (CFRP) as principle materials in commercial airlines, the ability to predict the damage from transverse impact events has become an important parameter in the design of airframe sections that can be exposed to impact events. The purpose of this research is to investigate the applicability of Finite Element Analysis (FEA), particularly using the commercial solver Abaqus/Explicit, to predict the onset of damage in laminated plates. Closed forms solutions have been developed in the past to predict the onset of damage, but only in terms of mid ply delaminations. The research presented in this thesis looks to use a Continuum Damage Mechanics material model in Abaqus, coupled with surface based cohesive interactions to simulate the interlaminar bonds between the lamina. To evaluate the predictive capability of the methodology, the onset of damage prediction will be compared against experimental data, examining when the damage begins to accumulate in the FEM and if there is a corresponding change in slope of the experimental Force vs. Displacement curve

Numerical methods for the characterization of transverse low velocity impact in stochastic tow based discontinuous fiber composites

Thesis (Ph.D.)--University of Washington, 2022Stochastic tow-based discontinuous composite (STBDC) laminates are made from compression-molded tows of carbon fiber reinforced polymer (CFRP). STBDCs are a material system that can be manufactured in complex three-dimensional geometries which provides an alternative to metallic components for primary and secondary structures. The discontinuous mesostructure gives the material system increased moldability versus continuous fiber composites allowing complex three-dimensional parts to be manufactured. However, the discontinuous mesostructure creates challenges for engineers designing parts as the effective properties are variable. Low velocity impact induced damage is a primary sizing constraint to ensure a structure is damage tolerant. Significant work has been done to experimentally and numerically characterize the LVI induced damage of continuous fiber composites, however little has been performed for STBDCs. The objective of this work is to develop a framework that enables the prediction of LVI induced damage through simulation of the mesostructural fine element models. Full mesostructures are generated, enabling simulations capturing the unique failure modes, which are primarily tensile matrix cracking and delamination. The results correlate well with experimental data collected and prove useful in predicting the initiation and evolution of damage in STDBCs. From the simulations, an impact damage threshold is established, demonstrating the value of the framework in predicting the damage of STBDCs

Cefuroxime induced lymphomatoid hypersensitivity reaction

An 84 year old women developed erythematous blotchy erythema and purpuric rashes over the lower limbs three days after being started on intravenous cefuroxime for acute diverticulitis. A skin biopsy specimen showed a mixed infiltrate of lymphoid cells and eosinophils; many of the lymphocytes were large, pleomorphic, and showed a raised mitotic rate. Immunohistochemistry showed the infiltrate to be T cell rich, with all the large cells being CD30 positive. Typical mycosis fungoides cells, marked epidermotropism, and Pautrier's abscesses were not seen. The rash disappeared 10( )days after cessation of cefuroxime and the patient remained asymptomatic 15 months later. This apparent cutaneous T cell lymphoma-like reaction is best described as lymphomatoid vascular reaction. The drug induced immune response with an atypical cutaneous lymphoid infiltrate mimics a cutaneous pseudolymphoma.


Keywords: cefuroxime; atypical cutaneous lymphomatoid infiltrate; cutaneous T cell lymphom