MS, University of Cincinnati, 2021, Engineering and Applied Science: Computer Science

Modeling of bacteria growth under different environmental conditions provides a useful tool to predict food and consumer goods safety. This study introduces a flexible, unique, and data-driven model to predict the bacteria growth under different pH conditions, using a one-to-many Long-Short-Term Memory (LSTM) model. When compared with a benchmark model the proposed model showed a good predictive power for different bacteria behaviors. In addition to its predictive ability, the model architecture is flexible and can be adapted for different bacteria behavior patterns without additional prior assumptions.

Committee: Anca Ralescu Ph.D. (Committee Chair); Kenneth Berman Ph.D. (Committee Member); Mark Maupin Ph.D. (Committee Member); Dan Ralescu Ph.D. (Committee Member) Subjects: Computer Science

Doctor of Philosophy, The Ohio State University, 2014, Nuclear Engineering

Precise knowledge of prompt γ-ray intensities following neutron capture is critical for elemental and isotopic analyses, homeland security, modeling nuclear reactors, etc. A recently-developed database of prompt γ-ray production cross sections and nuclear structure information in the form of a decay scheme, called the Evaluated Gamma-ray Activation File (EGAF), is under revision. Statistical model calculations are useful for checking the consistency of the decay scheme, providing insight on its completeness and accuracy. Furthermore, these statistical model calculations are necessary to estimate the contribution of continuum γ-rays, which cannot be experimentally resolved due to the high density of excited states in medium- and heavy-mass nuclei. Decay-scheme improvements in EGAF lead to improvements to other databases (Evaluated Nuclear Structure Data File, Reference Input Parameter Library) that are ultimately used in nuclear-reaction models for generating the Evaluated Nuclear Data File (ENDF). In this work, gamma-ray transitions following neutron capture in 93Nb have been studied at the cold-neutron beam facility at the Budapest Research Reactor. Measurements have been performed using a coaxial HPGe detector with Compton suppression. Partial γ-ray production capture cross sections at a neutron velocity of 2200 m/s have been deduced relative to that of the 255.9-keV transition after cold-neutron capture by 93Nb. With the measurement of a niobium chloride target, this partial cross section was internally standardized to the cross section of the 1951-keV transition after cold-neutron capture by 35Cl. The resulting (0.1377 ± 0.0018) barn (b) partial cross section produced a calibration factor that was 23% lower than previously measured for the EGAF database. The thermal-neutron capture cross sections were deduced for the 93Nb(n,γ)94mNb and 93Nb(n,γ)94gNb reactions by summing the experimentally-measured partial γ-ray production cross sections associated with t (open full item for complete abstract)

Committee: Lei Cao PhD (Advisor); Tunc Aldemir PhD (Committee Member); Thomas Blue PhD (Committee Member); Shamsuzzoha Basunia PhD (Committee Member) Subjects: Nuclear Engineering

Doctor of Philosophy, The Ohio State University, 2003, Veterinary Biosciences

Helicobacter pylori causes chronic active gastritis and ulceration and has been associated with the development of gastric cancer and gastric MALT lymphoma in a subpopulation of humans. In many areas of the world, gastric cancer causes significant morbidity and mortality in humans. Gastric cancer development is a multistep process similar to that proposed for colorectal cancer, and an important aspect of gastric carcinogenesis is proliferation of gastric epithelial cells. Gastric epithelial proliferation in combination with DNA damage can result in development of neoplasia. The inflammatory milieu of Helicobacter pylori infection is complex with elevated levels of proinflammatory cytokines. The role of proinflammatory cytokines such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-1 in the development of pathologic gastric epithelial hyperplasia was investigated. In mouse models of Helicobacter pylori gastritis, CD4+ T-cells are necessary for gastric epithelial proliferation, CD4+ T-cells are a major component of the inflammatory infiltrate, and gastric epithelial apoptosis and expansion of the gastric proliferation zone was associated with the CD4+ inflammatory infiltrate. Proinflammatory cytokines had no direct proliferative effect. Interferon-gamma, tumor necrosis factor-alpha, and interleukin-1 alpha elicited decreased proliferation of gastric epithelial cells in culture, while interferon-gamma apparently accomplished this by causing apoptosis. Transcript levels of interferon-gamma and its receptor, tumor necrosis factor-alpha, lymphotoxin, interleukin-10, interleukin-12, keratinocyte growth factor and its receptor, and transforming growth factor-alpha were all elevated in infected recipient severe combined immunodeficient (SCID) and wild-type C57BL/6 mice compared to uninfected and non-recipient mice. Transcript levels supported an association between interferon-gamma and keratinocyte growth factor. An indirect role of proinflammatory cytokines (open full item for complete abstract)

Committee: Kathryn Eaton (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2003, Materials Science and Engineering

There has been a heightened interest in the high temperature behavior of gamma-based titanium aluminide alloys in the past decade or so. Despite the large body of work done in the area of high-temperature creep, the present understanding of creep mechanisms and the effect of alloying and microstructure is limited. The first part of this investigation concentrates on the creep behavior in the equiaxed microstructure of gamma-TiAl alloys. The aim is to understand the mechanisms and develop a physically-based model for creep in the gamma phase. A modification of the classic jogged-screw model has been previously adopted to explain observations of 1/2[110]-type jogged-screw dislocations in equiaxed Ti-48Al under creep conditions. The goal of this study is to verify and validate the parameters and functional dependencies that have been assumed in that model. The original solution has been reformulated with the aid of analytical modeling, numerical simulations and Transmission Electron Microscopy. Combining the parameters and dependencies, derived both from experiment and theory, leads to an excellent prediction of creep rates and stress exponents. In the second part of this study creep behavior of the fully lamellar TiAl alloys is investigated. Dislocation structures similar to those observed in the equiaxed alloys suggests that the jogged-screw model can be adapted for lamellar alloys. The aim of the model is to predict the unique creep phenomenology of fully lamellar alloys. The strengths and shortcomings of the model are discussed. Probable low stress creep mechanisms are also suggested. The origin of fully lamellar alloys' superior creep properties stems from the constrained nature of deformation in the lamellae. The results from stress drop experiments are analysed to explore the origin of the large back stresses associated with the fully lamellar alloys. Reduction of the lamellar spacing is proposed as the best way to lower creep rates. In the final part of this st (open full item for complete abstract)

Committee: Michael Mills (Advisor) Subjects: Engineering, Materials Science