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This thesis presents the results of optimizing loading capacity of the sandwich panel by proposing a functionally graded sandwich panels and predicting the detailed failure mechanism of such panels. This study implemented the finite element based Extended This thesis presents the results of optimizing loading capacity of the sandwich panel by proposing a functionally graded sandwich panels and predicting the detailed failure mechanism of such panels. This study implemented the finite element based Extended Cohesive Damage Model (ECDM) to study the detailed failure mechanism of functionally graded sandwich panel. This research first time explored an in-depth investigation on the failure mechanism of syntactic foam sandwiches with a multi-layered core. This sandwich consists of laminated fibre sheets on the top and bottom individually, and a syntactic foam core with multiple graded layers between two laminated sheets. The failure mechanism of this kind of syntactic foam sandwich panels were studied through numerical modelling under quasi static three-point bending. The prediction showed perfect agreements with experimental work on investigating the sandwiches with homogeneous core and the core with four functionally graded layers. This investigation did not only found that the failure mode of a sandwich panel with the multi-layered core is shear failure dominated delamination but also found an excellent mechanical performance when the core has multiple graded layers in the investigated sandwiches compared to the case of the homogenous core. The delamination was along with the path close to the interface between the core and the bottom sheet. The correlation between loading capacity and the number of graded layers in the core of the investigated syntactic foam sandwiches is introduced for the first time. The ECDM predicted loading capacity of the investigated sandwich panel with an 8- layered core is increased ultimately by 61% compared to the case with the homogenous core. The geometric ratio, depth to span, of sandwich panel affects failure behaviour. Hence, it is the first time that this investigation explored geometrical ratio effects on the failure mechanism of functionally graded sandwiches with multi-layered cores. The FGSP showed different failure modes when their geometrical ratio between the depth and the span varies. Furthermore, this research also introduced the correlation between the failure load and the geometrical ratio of the FGSP with a multi layered in the core. The outcomes of this research contribute to academic knowledge, and industrial applications are summarized as follows: -It is the first time that this work explored the detailed failure mechanism of functionally graded syntactic foam core sandwich panel having more than four layers in the core using ECDM; -It introduced the correlation between failure load and the number of layers; ⮚ Likewise, geometric ratio effects on the failure mechanism of functionally graded sandwich panels are studied; -Finally, it also introduced the correlation between failure load and the geometric ratio; -Academically, these novel contributions can be used for future research as a benchmark. Likewise, this correlation can be used to predict the failure mechanism of the intermediate number of layered cores to gain a general overview of the initial design of FGSP; -These findings can be used to carry out further researches and to manufacture sandwich panels for various engineering applications with different geometrical depth-span ratios and variable layered sandwich cores; -This investigation also showed that the ECDM is a robust tool for predicting failure mechanism of syntactic foam sandwiches.

Introduction and Objectives: Nephrolithiasis is one of the most common renal diseases, but with poorly understood pathophysiology. The current understanding of how genetic, environmental, and metabolic factors act singly or in concert to trigger stone formation remains patchy, and the progress of medical therapy has been very modest. Vertebrate models for nephrolithiasis are limited in their ability to rapidly screen multiple and varied interventions that modulate urinary stone formation. Therefore, we hypothesis that the basic research directed at model systems that elucidate the pathophysiology of stone disease is the best hope for advancing the field and leading to the development of new therapeutic approaches that have the potential to reduce the morbidity, mortality, and cost associated with this disease. Further, most studies have confounded that age and temperature share some contribution in precipitation of kidney stones. We also hypothesise that change in temperature (from colder to warmer, low temperature to higher temperature) may have a greater impact on the formation rate of nephrolithiasis. Methods: A short lifespan, rapid deployment of transgenic lines and conception of rapid stone formation makes Drosophila melanogaster an ideal system to screen large numbers of interventions to assess their effect on kidney stone formation. Knockdown of gene candidates for their ability to vary the formation of urinary stones was employed utilising Drosophila. Microdissection, imaging and quantification facilitate identification and collection of fly stones within the lumen of the Drosophila Malpighian tubules (the functional equivalent of the human renal tubule). Further, UAS-RNAi knockdown efficiency was validated by qPCR . The genes which upon knockdown modulated the concentration of accumulated stones were further studied using various genetic, immunostaining and molecular techniques. In addition to that I also identified role of temperature and age in kidney stone formation by rearing flies at 18, 22, 26 and 29 for different time frame (day 7, day 14, day 21 and day 28) and quantifying accumulated stones during that period. The stones obtained were further validated by genetic, temperature switch, colorimetric and biochemical assays. Results: Calcium oxalate stone formation was associated with the stones accumulated intraluminally in parental lines and gene knockdown or mutant panel of genes fed with sodium oxalate (0.2% for 2 days). An unbiased knockdown screen of more than 20 RNAi lines was performed utilising the GAL4-UAS RNAi system and identified 8 genes that rescued kidney stone accumulation compared to parental lines. Microdissection and microscopy confirmed that five genes decreased stone formation in the fly, including genes Waterwitch (Wtrw), Serine Pyruvate Amino Transferase (Spat), Cinnamon (Cin), Na+-dependent inorganic Phosphate Co-transporter (NaPi-T), Sarcoplasmic Calcium-binding Protein 2 (Scp2) and Secretory Pathway Ca2+/Mn2+-ATPase (SPoCK). From the hits, I showed that mutation of SRY interacting protein (Sip1) in Drosophila MTs Stellate cells resulted in the accumulation of uric acid stones with a particularly notable interaction with Moesin and NHE2. I also demonstrated a combined impact of age and temperature in stone formation. Critically, I confirmed that they cause an accumulation of stones due to variation in expression of phosphate transporters NaPi-T and Picot. Our work also provides more precise insight into the impact of age and temperature in stone formation, given that we have shown that stone accumulation increases with age and in flies reared at high temperature compared to flies reared at a lower temperature. Conclusions: A Drosophila urinary stone model was leveraged to perform large scale genetic screens to identify novel genes that modulate calculi formation. Our hits may now be screened as a candidate gene in future cases with a clinical presentation. Our study documents the first case of uric-acid stone formation caused by mutations of a gene using Drosophila as a model organism. Confirmation of these mutations as a causative factor and that the stones accumulated were uric acid stones was done by genetic, molecular and physiological experiments.

Aluminium adjuvants (Alum) are the only widely approved adjuvants used in human vaccines, although their mechanism of action remains controversial. It is generally accepted that adjuvants mediate their effects on the adaptive immune system cells via innate antigen presenting cells (APCs), in particular dendritic cells (DCs). In this study the way in which Alum modulates several steps in DC functions that lead to T cell activation to underpin adjuvant function was investigated. Using EαGFP/YAe, it was demonstrated that Alum increased the rate and magnitude of antigen internalisation in an actin-dependent manner by DCs in vitro. It was observed that Alum caused an initial reduction in presentation compared with soluble antigen, but eventually increased the magnitude and duration of antigen presentation that was associated with reduced protein degradation in DCs. Using costimulatory-independent-DO11.GFP hybridoma, it was shown that Alum enhanced presentation of antigens derived from protein as well as peptide. As well as having an antigen targeting effect on DCs, this adjuvant works by mechanism(s) other than simply antigen delivery as adsorption to Alum is dispensable for boosting their antigen presenting efficiency. Alum enhanced DC activation characterised by the enhanced expression of CD86, CD80 and OX-40ligand (L) and the production of interleukin (IL)-1β, tumour necrosis factor (TNF)-α and IL-6. In in vivo studies employing adoptive transfer of transgenic T cells and subcutaneous (s.c.) injection, Alum caused a sustained accumulation of cells leading to draining lymph node (DLN) shutdown. In conclusion, it was shown that the dynamic alterations in phenotypic and functional changes underlie enhanced DC function in response to Alum. Due to increasing demand for novel adjuvants, a clearer understanding of the mechanisms that allow these important agents to affect adaptive immune responses will make a significant contribution to the rational design of future vaccines.

The most significant bottleneck in wireless communication systems is an ever-increasing disproportion between the bandwidth demand and the available spectrum. A major challenge in the field of wireless communications is to maximise the spatial reuse of resources whilst avoiding detrimental co-channel interference (CCI). To this end, frequency planning and centralised coordination approaches are widely used in wireless networks. However, the networks for the next generation of wireless communications are often envisioned to be decentralised, randomly distributed in space, hierarchical and support heterogeneous traffic and service types. Fixed frequency allocation would not cater for the heterogeneous demands and centralised resource allocation would be cumbersome and require a lot of signalling. Decentralised radio resource allocation based on locally available information is considered the key. In this context, the busy burst (BB) signalling concept is identified as a potential mechanism for decentralised interference management in future generation networks. Interference aware allocation of time-frequency slots (chunks) is accomplished by letting receivers transmit a BB in a time-multiplexed mini-slot, upon successful reception of data. Exploiting channel reciprocity of the time division duplex (TDD) mode, the transmitters avoid reusing the chunks where the received BB power is above a pre-determined threshold so as to limit the CCI caused towards the reserved chunks to a threshold value. In this thesis, the performance of BB signalling mechanism in orthogonal frequency division multiple access - time division duplexing (OFDMA-TDD) systems is evaluated by means of system level simulations in networks operating in ad hoc and cellular scenarios. Comparisons are made against the state-of-the-art centralised CCI avoidance and mitigation methods, viz. frequency planning, fractional frequency reuse, and antenna array with switched grid of beams, as well as decentralised methods such as the carrier sense multiple access method that attempt to avoid CCI by avoiding transmission on chunks deemed busy. The results demonstrate that with an appropriate choice of threshold parameter, BB-based techniques outperform all of the above state-of-the-art methods. Moreover, it is demonstrated that by adjusting the BB-specific threshold parameter, the system throughput can be traded off for improving throughput for links with worse channel condition, both in the ad hoc and cellular scenario. Moreover, by utilising a variable BB power that allows a receiver to signal the maximum CCI it can tolerate, it is shown that a more favourable trade-off between total system throughput and link throughput can be made. Furthermore, by performing link adaptation, it is demonstrated that the spatial reuse and the energy efficiency can be traded off by adjusting the threshold parameter. Although the BB signalling mechanism is shown to be effective in avoiding detrimental CCI, it cannot mitigate CCI by itself. On the other hand, multiple antenna techniques such as adaptive beamforming or switched beam approaches allow CCI to be mitigated but suffer from hidden node problems. The final contribution of this thesis is that by combining the BB signalling mechanism with multiple antenna techniques, it is demonstrated that the hybrid approach enhances spatial reusability of resources whilst avoiding detrimental CCI. In summary, this thesis has demonstrated that BB provides a flexible radio resource mechanism that is suitable for future generation networks.

Introduction: This thesis aims to characterize the biology of solid and liquid phase coronary thromboaspirate obtained during therapeutic aspiration at primary angioplasty for ST elevation myocardial infarction (STEMI). Methods: We studied coronary thromboaspirate obtained from the coronary artery (CA) in STEMI and focussed on three lines of investigation: • Intracoronary solid phase thrombus was subjected to immunohistochemistry for characterization and quantification of the different leukocyte types and proteins involved in the thrombus. • Resident cell populations in the liquid phase filtrate from the aspirate including platelets and leukocytes along with their subpopulations were analysed by flow cytometry for phenotypic and activation markers. Comparison was made with cells in the peripheral femoral artery (FA) blood. • Paired plasma/serum from the CA filtrate and FA blood were analysed for the presence of autoreactive antibodies and cytotoxic potential. Results: • Leukocytes were heterogeneously distributed in the ex-vivo thrombus. The granulocyte population was predominant and strongly expressed CD11b and vimentin. • The CA aspirate filtrate when compared to the paired FA blood contained significantly more leukocyte-platelet conjugates, more activated platelets, and more Vimentin. • More of the CD4+ T cells in the CA than FA had lost the co-stimulatory molecule CD28 (p<0.00001) and they often expressed effector phenotype marker. • Conversely, the immune-regulatory T cells expressing the FoxP3 were more attenuated in the CA than FA (p<0.00001). • Whilst IgG and IgM antivimentin antibody titres in the CA sera were consistently lower than the titres in FA sera (p<0.001), auto-reactive non-HLA IgM were more prevalent in CA sera. The CA sera had increased potential to induce apoptosis than FA sera when incubated with endothelial cells (p<0.001). Conclusions: • Aspirated intracoronary clot contained granulocytes as the predominant leukocyte component. This investigation of the immune system in the CA during AMI therefore moved on to the adaptive system in the coronary filtrate. • Increased concentrations of pro-inflammatory immune cells and reduced concentrations of immune-modulating cells were observed in the aspirate from the culprit site of CA occlusion when compared with the FA. The presence of T memory cells implies that this subset may have been released from the ruptured coronary plaque and this phenotypic analysis may help clarify the role of the immune system in the pathogenesis of coronary plaque instability. • The higher titres of auto-reactive IGM in the CA than FA sera have the potential to activate the complement system and may contribute to myocardial injury following therapeutic restoration of coronary flow in STEMI.

A total of 425 questionnaire-based interviews and 15 in-depth interviews with FSWs in Nepal including non-participant observation in the field were conducted in 2006. The age range of the FSWs participated was 15-46 years.  FSWs (30.8%) reported having had STI symptoms in presences 12 month.  The quantitative findings suggested that many reported having used condoms during their last sexual intercourse, but in-depth interviews suggested the opposite.  One fifth (21%) had never visited health facilities.  Of those who visited, 149 (50.3%) turned to a private clinic and pharmacy; 181 (61.1%) used Non-Governmental Organisation (NGO) clinics, 79 (26.6%) resorted to care in hospital and 30 (10.1%) treated themselves.  The remainder 85 (28.7%) were found to seek help from primary health care centre, health posts, family planning clinic or other health institutions for treatment.  The behaviour theories and models used in this study (i.e. health belief model, theory of reasoned action and planned behaviour) partly explain the decisions of FSW on use and non-use of available health services.  The study identified that lack of confidentiality and privacy created distrust among FSWs and stopped them from accessing health services.  Embarrassment, disregard by health care providers and poor communication with them, long waiting time and fear of exposure as a sex worker were major barriers to seeking health services. It is therefore necessary to provide specific training to service providers in all types of health care institutions in order to promote confidential and quality health services.

Agricultural extension services are under pressure to improve their services and contribute more to agricultural development. Extension services require human resources that are competent both technically as well as in process skills. Little is known about whether and how competent extension professionals are to serve in the changing context and as demanded by their clients. Examining the competencies of extension staff members is vital to management being cognizant of training and educational needs of their staff members as well as being able to effectively mobilize them to accomplish extension tasks. This four-paper dissertation seeks to assess how Nepalese extension professionals perceive extension core competencies. Using extension experts' input and information drawn from a literature review, the first paper identifies areas of core competency that the agricultural extension professionals in Nepal need to possess to effectively deliver extension services to farmers. The eight core competency areas identified are communication, program planning, program implementation, personal and professional development, education and informational technology, diversity, program evaluation, and technical subject matter expertise. The second paper uses self-administered in-person and web based survey data and discusses the perceptions of importance of core competencies of extension professionals. Respondents perceived core competencies to be very important to their work are those related to personal and professional development, followed by communication skills. The third paper examines extension professionals' levels in the core competencies. The findings show a moderate level of competency among extension professionals and a clear gap exists between the perceived level of importance and current level of competency. The widest such gap is in educational and informational technology followed closely by technical subject matter expertise and program evaluation. The fourth paper assesses respondents' perceptions of level of competency pertaining to demand-driven extension and ways to acquire competencies. Respondents felt only moderately competent to demand-driven extension competency. Generally, all four ways in-service, preservice, basic induction and workshop/seminar/webinar seem to be appropriate to acquire core competencies, but in particular, respondents from government organizations preferred in-service and/or basic induction training to acquire core competency than respondents from non-governmental organizations did. The study has several implications for the preservice and in-service agricultural education and training in Nepal. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]

Hardware Trojans are malicious circuits, hidden in integrated circuits (ICs) which pose a significant threat to security. Detection of hardware Trojans is important to build trust, verify, and make the semiconductor ICs process secure. The existing hardware Trojan detection methods are generally destructive, require intricate comparisons, or require a long time for reverse engineering.In the initial phase of this study, the substitution of supervised hardware Trojan detection methods in ASICs chips is explored with unsupervised approaches, thereby eliminating the dependence on golden references. The Trojan detection uses a ring oscillator (RO) based on NAND as the power monitor. Frequency side channels are computed, and unsupervised classifiers are employed, achieving a commendable accuracy of 93%, comparable to state-of-the-art methods requiring golden data.In the later part of our work, different feature extraction techniques are applied to improve the competence and precision of Trojan detection. Experiments include frequency side-channel extraction with the use of implanted ROs in Basys FPGA, resulting a higher F1 score and accuracy (95\%) in detection of the Trojan. Further, the method has performed equally well for all the Trojan sizes considered (8-bit, 16-bit, and 32-bit) during the performance evaluation with no significant difference and has yielded equal efficiency in detecting even small-sized Trojans.After clustering ICs, a post-processing localization algorithm is proposed to help in identifying and locating hardware Trojan within the chip with reference to the ROs. This algorithm eliminates the requirement of complete reverse engineering of at least one IC from a cluster to figure out if the cluster formed by ML contains Trojan-infected or not 'golden' chips.The proposed algorithm simplifies this process by focusing mainly on the chip portion, where the Trojan is localized.Lastly, the study presents some vulnerability of the clustering model to adversarial attacks in the Trojan detection technique. These attacks reduce significantly the accuracy of chip clustering into the correct cluster up to 50\%. Consequently, we advocate for the integration of adversarial defense mechanisms into the hardware Trojan detection machine learning models, an area we identify as a focus for future research. In conclusion, the presented work enhances unsupervised hardware Trojan detection improvements by presenting new feature extraction techniques and giving a localization algorithm to avoid reverse engineering efforts. The need and importance of adversarial defense mechanisms to make machine learning systems detect Trojans has been highlighted.

Ammonia-oxidizing bacteria (AOB), ammonia-oxidizing archaea (AOA) and complete ammonia oxidizers (comammox) comprise aerobic ammonia oxidizers (AO). Here, we present the ammonium concentration as a determinant of the distribution of ammonia-oxidizers. The ecophysiology of comammox enrichment Cmx-BO4 was characterized by growing it in different ammonium concentrations, pH, light and nitrite concentrations. Cmx-BO4 oxidized up to 3 mM ammonium, with the highest growth rate at 10 M ammonium. The comammox enrichment oxidized ammonium through pH 6 to 8 and was inhibited by blue and white light. Cmx-BO4 oxidized nitrite in presence of ammonium but did not oxidize nitrite only. The genomic characterization of comammox strain Nitrospira sp. BO4 in the comammox enrichment Cmx-BO4 was performed through metagenomic sequencing. The metagenome assembled genome (MAG) of Nitrospira sp. BO4 possessed genes for ammonia and nitrite oxidation. The MAG, however, lacked genes for assimilatory nitrite reduction and nitrite transporters, corresponding to the inability of the culture to consume nitrite as the nitrogen source.Comammox Nitrospira sp. BO4 was competed for ammonium against AOA Nitrosoarchaeum sp. BO1 to investigate if the two oligotrophic AO had niche differentiation or if they co-existed in nature. Cmx-BO4 and AOA-BO1 have Nitrosopira sp. BO4 and Nitrosoarchaeum sp. BO1 as the AO respectively. Nitrospira sp. BO4 outcompeted Nitrospira sp. BO1 at all three tested ammonium concentrations (

Current Virginia nitrogen (N) fertilizer recommendations do not include site-specific estimates of N supply from cover crops (CCs) or soil organic matter (SOM). Recent research successfully predicted the contribution of N from SOM and CCs to corn (Zea mays L.) in Pennsylvania. The objective of this work was to validate the biophysical model developed in Pennsylvania under Virginia conditions and to evaluate the decomposition rates of different surface-applied CC residues and the relationship between their chemical composition and decomposition rate. For the first objective, 83 N response trials were conducted in different regions of Virginia across 9 years using a randomized complete block design with four replications. The model was able to explain 47% and 15% of variability in unfertilized corn yield (RMSE = 1.6 Mg ha-1) and economical optimum N rate (EONR) (RMSE = 30 kg N ha-1) respectively. Efforts to improve the model by adding economically unresponsive sites improved the model performance to explain 45% of the variability in EONR. For the second objective, a lab incubation was performed to compare carbon (C) and N mineralization from four different CCs {Cereal Rye (CR), Hairy vetch (HV), Crimson clover (Cc) and Rapeseed (R)} on a sandy loam soil. Destructive sampling was performed at 6 different sampling dates – 3, 7, 14, 28, 56 and 112 days. ANOVA test revealed that the effects of CC species, incubation days and their interaction had a significant effect on mass decomposed, plant biochemical composition and net N mineralization. Variation in mass loss was positively related to lignin content for all the CCs while it was moderately correlated to C:N ratio for CR and R and weakly to HV and Cc. Biomass loss and N release was highest in HV followed by Cc, R and CR. Net N mineralization was highest in HV followed by R, Cc and CR amended soils.

Using dairy farm data, this dissertation investigates the environmental and health implications of concentrated animal feeding operations (CAFOs) in New Mexico. It seeks to answer three primary research questions: (1) the relationship between environmental justice indicators and proximity to dairy farms; (2) the overall health consequences of dairy air pollutants; and (3) the viability of implementing an anaerobic digester (AD) system as a potential solution to externality concerns while maintaining dairy farm economic sustainability. The first study demonstrates that foreign-born populations and Hispanics disproportionately experience emissions from CAFOs, with living near dairy farms or in areas with elevated ammonia levels linked to lower family income, fewer high school graduates, and higher poverty rates. These findings provide insights to inform policy decisions aimed at reducing environmental injustice, benefiting policymakers, stakeholders, and activists dealing with similar challenges in other regions. The second study quantified the health damages caused by dairy air pollutants. The study determined that increased PM2.5 concentrations from dairy farm emissions resulted in 12.41 annual deaths, equivalent to $129 million in monetary terms. The primary pollutant responsible for these health damages was found to be ammonia, contributing 99.38% of the damages through its transformation into secondary PM2.5. This research is one of the first to quantify and monetize health costs related to dairy farms and suggests the need for expanded research to include other livestock types and geographical regions. The third study evaluated potential solutions to address these challenges. We assessed the cost and revenue parameters of various AD systems and environmental incentive regimes, focusing on configurations with fiber and nutrient separation due to their large private and social benefits. Recommendations were provided to policymakers on how to address challenges such as high initial capital costs and the lack of markets for co-products to optimize net benefits for both private and public parties. In conclusion, CAFOs impose substantial human health costs and contribute to global greenhouse gas emissions. However, an integrated approach utilizing AD systems can address both local pollution and global climate change concerns. Policymakers can foster the implementation of such systems through grants, low-interest loans, and assistance in establishing markets for AD co-products. Future research should include geographical extension of studies, lifecycle assessments of CAFOs, identification of optimal locations for dairy farms, comparative studies of large farms versus traditional farming methods, and investigations on the impact of further government regulations on dairy farm operations. This comprehensive assessment of environmental, health, and socioeconomic impacts of CAFOs will inform more sustainable and equitable policy decisions.

This study aims to advance the understanding and application of spectroscopic sensor data fusion for improving soil nutrient content predictions. In addition to presenting an extensive review of studies on the spectroscopic sensor data fusion, a research investigation was conducted to assess the effectiveness of five fusion algorithms in predicting three primary nutrients (Nitrogen, Phosphorous, and Potassium) and two secondary nutrients (Calcium and Magnesium) in soil using Visible and Near-Infrared, Mid-Infrared, and X-ray Fluorescence data. Among the five fusion algorithms, one was a low-level fusion involving data concatenation. Two were mid-level fusions, incorporating feature extraction by applying (i) Principal Component reduction and (ii) Partial Least Squares reduction. The other two were high-level fusions, namely (i) Simple Averaging and (ii) Granger Ramanathan Averaging. The results indicate that Low-Level Fusion may not be suitable for inherently incompatible data. Mid-level fusion improved the R² by 0.1-18%, RMSE by 0-8%, and RPIQ by 0-11.5%, while high-level fusion enhanced the R² by 0-12.5%, RMSE by 0-12%, and RPIQ by 2.3-13.4%, depending on the nutrients and fusion algorithms. Despite these improvements, predictions were only satisfactory for primary nutrients, and none of the algorithms could notably enhance predictions for Phosphorous. The study also finds that fusion algorithms do not significantly improve bias. The study provided evidence of improvement in prediction accuracy with data fusion which can aid in delineating management zones for precision agriculture. It also encourages further research on novel approaches of sensor fusion and algorithms that can effectively handle non-linearity introduced due to the fusion of data. Advisor: Yufeng Ge

Sustainable management practices have been recognized to improve ecosystem functions such as productivity, soil health, and resilience. The impacts of livestock and cover crop integration as sustainable techniques on soil health, however, are not well studied in South Dakota cropping systems. This study was conducted at the Southeast Research Farm, South Dakota with objectives to evaluate the impacts of cover crops and livestock integration on (i) soil bio-chemical properties and (ii) soil pore characteristics and hydro-physical properties. The research site was established based on no-till corn (Zea mays L.)-soybean (Glycine max (L.) Merr.)-oat (Avena sativa L.) rotation systems in 2016. The experiment was a randomized complete block design with four replicates. Treatments include a complete combination of three management strategies (integrated cover-crop livestock system (ICLS), cover crop without grazing (CC), and no cover crop or grazing control (CNT)) and three crop phases (corn, soybean, oat). For the first objective, soil sampling was conducted from all nine treatments in two seasons, October 2021 (fall) and May 2022 (spring) at 0-10 cm. For the second objective, sampling was conducted by collecting intact soil cores at 0-10 and 10-20 cm in May 2018 in the corn phase under the three management strategies. Results showed the potential of ICLS and CC in improving soil health. Total organic carbon and total nitrogen were increased under ICLS (30.3 and 2.51 g kg-1, respectively) and CC (30.4 and 2.56 g kg-1, respectively) compared to CNT (28 and 2.29 g kg-1, respectively). In Spring, soil microbial communities such as gram-positive bacteria, gram negative bacteria, actinomycetes and total fungi were promoted in oat phase under ICLS and were the lowest in soybean phase under CNT. Soil hydrophysical properties were also improved by CC or ICLS management, such as the increased number of pores, coarse mesoporosity and saturated hydraulic conductivity and decreased bulk density compared to those under CNT. Some other biological and hydro-physical characteristics, however, were regulated by seasons or crop phases rather than management. Thus, long-term study is necessary to further understand the soil health influenced by CC and ICLS in cropping systems under similar climate conditions and crop rotation strategies.

Fluorophores containing donor, ᴫ linker, and acceptor units are gaining importance in the field of organic chemistry, especially showing fluorescence at near-infrared region. Herein, we report the synthesis and optical properties of donor-ᴫ-acceptor fluorophores containing indole, benzo[e]indole, and benzothiazole as donor units. The cyanoacetic acid/ malononitrile were used as acceptor units. The Vilsmeier Haack linker substituted with different functional groups such as hydrogen, t-butyl and phenyl at the 4th position was the as ᴫ-linker. The chlorine at meso-position was replaced with various nucleophiles such as piperidin-4-ylmethanol and pyridine-4-thiol. The fluorophores showed absorbance and emission maxima in NIR region (λabs =645 - 825 nm and λem = 784 - 828 nm) with and high molar extinction coefficients and photothermal stability. The fluorophores had Stokes shift of 6 – 143 nm and quantum yield of 7 - 20%. The biodistribution of the synthesized fluorophores were studied in collaboration with Dr. Hak Soo Choi.

The addition of nanocarbons to copper (Cu), specifically in the form of graphene (GN), has been shown to enhance copper's properties. GN-Cu nanocomposites can potentially achieve higher electrical, mechanical, and thermal properties compared with copper. These characteristics make GN-Cu materials interesting for several applications including but not limited to interconnects, high voltage lines, and rotating machines. Copper’s microstructure and nanoscale interfacial phenomena between the GN and Cu control charge conduction in GN-Cu materials. In this work, we investigated the possibilities of conductivity enhancement in multi-layered GN-Cu composites both theoretically (classical, quantum, and atomistic models) and experimentally. Additionally, our work elucidates possible errors in electrical conductivity measurements of thin GN-Cu films. GN-Cu samples were prepared by the processing of chemical vapor deposition (CVD) GN on Cu samples using spark plasma sintering (SPS) or hot isostatic pressing (HIP). Structure-property relationships, measured over a wide temperature range, revealed conduction mechanisms in these materials. This dissertation also investigates the high electrical current processing of copper-carbon melt, namely the Covetic processing.

The 30P(p,γ)31S reaction acts as a bottleneck for classical nova nucleosynthesis beyond A=30 in ONe novae, due in part to the long lifetime of 30P (∼2.5 minutes) with respect to the timescale of a nova outburst. Also, the 30P(p,γ)31S reaction rate directly affects the isotopic ratio of 30Si/28Si, which is an important nova identifier in the analysis of pre-solar grains. O/S, S/Al, O/P, and P/Al elemental abundance ratios can be used as nuclear thermometers for classical novae by constraining the 30P(p,γ)31S reaction rate. However, direct measurement of the 30P(p,γ)31S reaction is not feasible because proton capture reactions at astrophysical energies have very low cross sections as the proton has to tunnel through the Coulomb barrier and due to experimental challenges in producing an intense 30P beam at relevant astrophysical energies. An indirect method was used which measured the 30P(d,pγ)31P transfer reaction with a radioactive 30P beam at 8 MeV/A at Argonne National Laboratory using the GODDESS (GRETINA-ORRUBA: Dual Detectors for Experimental Structure Studies) system, which is a coupling of position-sensitive silicon detectors array ORRUBA, with the γ-ray tracking array GRETINA. The angular distributions and the single-neutron spectroscopic structure of 31P were studied. The single-proton spectroscopic structure, resonance structure, and reaction rate of the astrophysically important resonances in 31S were constrained via mirror symmetry. Details of the experiment, data analysis process, and results from this work will be presented.

Size premium puzzle, also known as the size effect, is one of the most studied anomalies in asset pricing literature. It refers to the observation that, on average, smaller firms have higher risk-adjusted returns than larger firms over a long period of time. While many studies have debated the existence of the size effect, the question of why it exists has become a subject of heated debate. Thus, this dissertation aims to examine if previously overlooked factors can, at least partially, explain the size effect. Essay 1 examines if merger and acquisition activity can explain a part of the size effect. I find that merger and acquisition activity explain a part of the size effect. The size effect is found to be stronger during merger waves but is not consistent across industries. Further, the size effect tends to be stronger when acquisition activity is concentrated among smaller firms. Essay 2 investigates if expectational errors explain the higher return of small firms. Several empirical studies show that stocks that investors underestimate yield higher returns. However, I do not find support for the underestimation explanation in explaining the higher returns of small firms. Instead, I find that investors are overly optimistic about the growth of small firms. In essay 3, I examine if the size effect can be explained by perceived risk. Using the implied cost of capital (ICC) as a measure of perceived risk, I find that small firms are perceived to be riskier by the market, and the perceived risk explains the size effect.

Oat is an important cereal crop grown worldwide. Oats have the potential to contribute to human health due to their unique nutritional attributes. Developing oat cultivars with efficient root systems able to extract heterogeneously distributed soil resources can help maintain yield under drought conditions and in nutrient poor soil. Various root traits determine the soil volume that is explored by the root system for resource acquisition. Knowledge about the genetic control of oat root traits and response to biotic and abiotic environmental factors is lacking. Identifying quantitative trait loci associated with root traits and understanding the response of roots to abiotic and biotic environmental factors such as drought and endophytic bacteria may enable plant breeders to develop oat cultivars with efficient roots that can maintain yield under unstable climates. To understand the genetic basis of various root traits in oats and how the oat root and shoot development is impacted by drought and by plant growth-promoting endophytic bacteria, we conducted three different experiments. First, we studied the response of oat root and shoot development to endophytic bacterial inoculation by conducting a root vigor assay and a greenhouse experiment. Several endophytic bacteria significantly increased the root length, root area and root volume for one of the two oat cultivars evaluated in the root xiii vigor assay. The greenhouse study revealed that the response of oat cultivars to endophytic bacterial inoculation varied depending on the growth parameters evaluated, the nitrogen fertilization level, the oat genotype, and their interactions. Thus, identifying a specific strain of bacteria for overall growth promotion in oats might be difficult. To gain a better understanding of the extent of phenotypic differences in roots among oat genotypes and how those variations are controlled genetically, a genome-wide association study of root system architectural traits was conducted. Root traits were phenotyped at the seedling stage using a germination paper-based growth platform and a high-throughput image analysis system. Significant variability in root traits among the 285 genotypes evaluated was observed and broad-sense heritability ranged from 0.17 to 0.59 depending on the trait. We identified 82 significant marker-trait associations using a mixed linear model approach. Markers significantly associated with root traits explained from 7.6 to 19.9 % of the phenotypic variation. We identified multiple candidate genes located close to the significant markers that are known to have a role in root development. Finally, we evaluated the morphological and physiological responses of root and shoot development of ten oat genotypes under drought stress. After withholding watering for two weeks on 21 days old seedlings, we measured chlorophyll content, relative water content, stomatal conductance, stomata number, shoot dry weight, root dry weight, root length, root area, and root volume. Seed yield per plant was also collected by continuing the drying and rewatering cycle until physiological maturity. All traits measured were significantly impacted by the water regime. Oat cultivar Hayden showed the smallest reduction in vigor assay. The greenhouse study revealed that the response of oat cultivars to endophytic bacterial inoculation varied depending on the growth parameters evaluated, the nitrogen fertilization level, the oat genotype, and their interactions. Thus, identifying a specific strain of bacteria for overall growth promotion in oats might be difficult. To gain a better understanding of the extent of phenotypic differences in roots among oat genotypes and how those variations are controlled genetically, a genome-wide association study of root system architectural traits was conducted. Root traits were phenotyped at the seedling stage using a germination paper-based growth platform and a high-throughput image analysis system. Significant variability in root traits among the 285 genotypes evaluated was observed and broad-sense heritability ranged from 0.17 to 0.59 depending on the trait. We identified 82 significant marker-trait associations using a mixed linear model approach. Markers significantly associated with root traits explained from 7.6 to 19.9 % of the phenotypic variation. We identified multiple candidate genes located close to the significant markers that are known to have a role in root development. Finally, we evaluated the morphological and physiological responses of root and shoot development of ten oat genotypes under drought stress. After withholding watering for two weeks on 21 days old seedlings, we measured chlorophyll content, relative water content, stomatal conductance, stomata number, shoot dry weight, root dry weight, root length, root area, and root volume. Seed yield per plant was also collected by continuing the drying and rewatering cycle until physiological maturity. All traits measured were significantly impacted by the water regime. Oat cultivar Hayden showed the smallest reduction in yield in response to drought treatment. Hayden also showed a smaller reduction in relative water content, chlorophyll content, and a strong reduction in stomata number. Results indicated that the larger root system may not necessarily provide a yield advantage under drought conditions in oats. The importance of root mass distribution into lower and upper soil layers should be investigated to improve our understanding of mechanisms involved in coping with drought.

Spasers are devices based on the effects of a plasmonic field and emulate a laser phenomenon in a nanoscale. A spaser consists of a resonator, which is a metal, and a gain, which is usually a semiconductor. The topological properties of materials are independent of geometrical deformations and are invariant under structural changes and perturbations. The electronic properties of a group called transition metal dichalcogenides(TMDCs), a type of two-dimensional(2D) materials, exhibit robustness around certain symmetry points called valleys, where the dipole-transitions are most probable. Topological nanospaser consists of a silver nanospheroid and a gain 2D monolayer TMDC placed atop of it. The metallic spheroid acts as a nanoresonator for the plasmonic field. It supports two dipole modes rotating in the opposite directions with surface plasmon resonance frequency ($\omega_{sp}$). When transition frequency in the gain matches to the $\omega_{sp}$ of nanospheroid there is a coupling between the plasmonic modes and the chiral valleys ($\mathrm{K}$ and $\mathrm{K^\prime}$) which results in the generation of plasmons. Here, we selectively pump a single valley and study the dynamics of a nanospaser for different radii of the gain flake. When the radius of TMDC nanoflake is less than the radius of the nanospheroid, the plasmons generated are only those which match the chirality of the pumped valley and plasmons with the opposite chirality are absent. However, for a large enough flake size, the plasmonic field outside the footprint of the spheroid polarizes the unpumped valley and the generation of these mismatched plasmonic modes becomes highly probable. In addition, we also analyze the far-field radiation due to this nanospaser. We, further, study the effects of inter-level relaxation in a spaser system of spherical nanoparticle embedded inside a sphere composed of dye. Assuming gain to be a three-level model, we will explain the effects due to relaxation in the higher energy levels in the generation of plasmons. Contrary to a two-level system spaser where the dependence of plasmons on excitation is linear, we observe a quadratic relationship. Both these nanospasers have tremendous potential uses in the different areas of infrared spectroscopy, sensing, probing, and mainly biomedical treatment.

Epilepsy is one of the most common neurological diseases affecting over 50 million people worldwide. Approximately one-third of these patients are refractory to anti-epileptic drugs and surgical resection of epileptic focus remains their only hope for cure. Despite many diagnostic tools, the clear identification of a resectable epileptic focus is still a major bottleneck. This work presents a set of comprehensive quantitative analysis techniques for analyzing and synthesizing infraslow intracranial electroencephalography (iEEG) signals and resting state functional magnetic resonance imaging (rsfMRI) to quantify infra-slow (0.01- 0.1 Hz) network activities, localize seizure onset zones and determine pathological propagation pathways. Firstly, we examine the existence of a stable network from infra-slow to very high frequencies throughout multiple phases of focal epilepsy using quantitative methods based on spectral Granger causality and graph measures. We show that the strongest infra-slow iEEG (IsEEG) signal correlates highly with the location of the visible seizure focus, and also with that of the strongest high frequency EEG signal, in both the preictal and interictal phases of the epilepsy cycle. Secondly, we present a novel quantitative analysis technique to localize the seizure focus by seeding the focus locations from iEEG to rsfMRI. We show that the iEEG electrode contacts with the strongest infraslow iEEG signal correlates with the slow spontaneous blood-oxygen-level-dependent (BOLD) fluctuations in corresponding locations; and those voxels form a highly significant grouping when compared to others throughout the entire brain. This presents an exciting direction in refractory epilepsy to link an invasively recorded iEEG infra-slow network, from a few hypothesized cortical areas, to a non-invasive, whole brain fMRI network.

The fundamental vibrational modes of biological constituents in the tissues and the complex body fluids coincide with optical frequencies in the infrared region. Therefore, spatially resolved molecular compositions and interaction information within the biological materials can be extracted non-destructively using IR radiation without the use of labels or probes. However, the feasibility of this technique to elucidate constituent molecular compositions and interactions within the diagnostic mediums is not well explored. This study demonstrates an application of infrared (IR) spectroscopy of sera for monitoring inflammatory bowel diseases (IBD) and various cancers. Using samples from experimental mice and human patients, the power of IR spectroscopy in structural studies of proteins and other complex band contours are explored to find spectral signatures. Two experimental models of IBD; interleukin 10 knockouts (IL10-/-) and Dextran Sodium Sulfate (DSS) induced mouse shows diagnostic accuracy with 80-100% sensitivity and specificity values. Importantly, the findings of human IBD patients’ serum also show promising results resembling our proofs-of-concept investigations of mouse models. Maximum values of sensitivity and specificity are 100% and 86%, respectively, in human samples. Similarly, in cancer studies, the EL4 mouse model of non-Hodgkin lymphoma (NHL) and a B16 mouse model of the subcutaneous melanoma are used to extract a snapshot of tumor-associated alteration in the serum. The study of both cancer-bearing mouse models in wild types (WT) and their corresponding control types emphasizes the diagnostic potential of this approach as a screening technique for the NHL and melanoma skin cancer. The breast cancer (BC) -associated protein conformational alteration in the serum samples shows the sensitivity and the specificity of identifying spectral signatures were both 90%. All in all, IR spectroscopy of serum samples accompanied by spectral analysis technique shows some promising results for disease diagnostics. The brief outlook of the fundamentals of the infrared detection technique and their applicability for the development of portable spectroscopy is also provided.

Lead (Pb) -Tin (Sn) mixed perovskites suffer from large open-circuit voltage (VOC) loss due to the rapid crystallization of perovskite film, creating Sn and Pb vacancies. Such vacancies act as defect sites expediting charge carrier recombination, thus hampering the charge carrier dynamics and optoelectronic properties of perovskite films. In the first project, we focused on the passivation of perovskite surface defects to increase the opencircuit voltage of the 1.25 eV low-bandgap perovskite solar cells by utilizing a trace amount of Phenethylammonium iodide (PEAI) in the perovskite precursor solution as a doping agent. The incorporation of PEAI in perovskite precursors improved the perovskite film quality and crystallinity. In addition, it lowered the electronic disorder, enhancing opencircuit voltage up to 0.85 V, and power conversion efficiency up to 17.33 % was obtained with improved dark and ambient stabilities. In the second project, we improved the charge transport dynamics of the Pb-Sn perovskite using interface engineering strategy by inserting an ultra-thin layer poly [bis(4- phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) over the commonly used HSL of poly(3,4 ethylenedioxythiophene)polystyrenesulfonicacid (PEDOT: PSS). Modification of HSL ensured the suppression of the interfacial defects, enlarged the perovskite grain sizes, improved the crystallinity of the perovskite layer, enhancing open-circuit voltage up to 0.85 V, and a fill factor approached to ~ 80 % thus, power conversion efficiency boosted up to 19.41 % with improved dark-shelf and operational stabilities. These simple yet powerful additives and interface engineering techniques seem promising strategies to mitigate VOC-loss in Pb-Sn mixed low-bandgap perovskite solar cells and can be easily applied in other mid-bandgap wide-bandgap perovskites.

Low grain protein content in hard red winter (HRW) wheat (Triticum aestivum L.) has been a serious challenge for rainfed wheat growers, particularly in years with elevated grain yield. Proper nitrogen (N) management with adequate N rate and time of application will be critical for optimizing both grain yield and protein content. In addition, crop canopy reflectance sensors (CRS), which have been widely used for precision N management in corn in Nebraska and explored in winter wheat in some other states, are yet to be explored in Nebraska. This 2-yr experiment evaluated the effects of different N rates (0%, 25%, 50%, 75%, 100%, and 125% of recommended rate) and application timings (fall, spring, and split between fall and spring) on grain yield and protein of HRW wheat. Field experiments were conducted at four different sites across Nebraska under rainfed conditions in 2018/2019 (Year 1) and 2019/2020 (Year 2). Nitrogen fertilization significantly increased grain yield in a year with above-average precipitation (Year 1). There was an increase in grain protein with increasing N rates at all sites in both years and the highest grain protein was always with the 125% N rate. Spring and split applied N was effective over fall application in the site-year when there was a risk of applied N loss via leaching or denitrification. Ruth, as a semi-dwarf most recently developed variety for greater adaptation in Nebraska and neighboring states demonstrated potential to benefit from spring or split N application given no disease pressure. Normalized Difference Vegetation Index (NDVI) obtained from active CRS at different growth stages had significant positive relationship with applied N rate, grain yield, and protein at certain growth stages and site-years, indicating its potential use for in-season N management in winter wheat. The results of this study suggest that an effective N management strategy for winter wheat should account for and be adaptable to weather variability to optimize grain yield and protein content in winter wheat. Advisor: Bijesh Maharjan

In this dissertation, we are interested in solving a linear inverse problem: inverse electrophysiological (EP) imaging, where our objective is to computationally reconstruct personalized cardiac electrical signals based on body surface electrocardiogram (ECG) signals. EP imaging has shown promise in the diagnosis and treatment planning of cardiac dysfunctions such as atrial flutter, atrial fibrillation, ischemia, infarction and ventricular arrhythmia. Towards this goal, we frame it as a problem of learning a function from the domain of measurements to signals. Depending upon the assumptions, we present two classes of solutions: 1) Bayesian inference in a probabilistic graphical model, 2) Learning from samples using deep networks. In both of these approaches, we emphasize on learning the inverse function with good generalization ability, which becomes a main theme of the dissertation. In a Bayesian framework, we argue that this translates to appropriately integrating different sources of knowledge into a common probabilistic graphical model framework and using it for patient specific signal estimation through Bayesian inference. In learning from samples setting, this translates to designing a deep network with good generalization ability, where good generalization refers to the ability to reconstruct inverse EP signals in a distribution of interest (which could very well be outside the sample distribution used during training). By drawing ideas from different areas like functional analysis (e.g. Fenchel duality), variational inference (e.g. Variational Bayes) and deep generative modeling (e.g. variational autoencoder), we show how we can incorporate different prior knowledge in a principled manner in a probabilistic graphical model framework to obtain a good inverse solution with generalization ability. Similarly, to improve generalization of deep networks learning from samples, we use ideas from information theory (e.g. information bottleneck), learning theory (e.g. analytical learning theory), adversarial training, complexity theory and functional analysis (e.g. RKHS). We test our algorithms on synthetic data and real data of the patients who had undergone through catheter ablation in clinics and show that our approach yields significant improvement over existing methods. Towards the end of the dissertation, we investigate general questions on generalization and stabilization of adversarial training of deep networks and try to understand the role of smoothness and function space complexity in answering those questions. We conclude by identifying limitations of the proposed methods, areas of further improvement and open questions that are specific to inverse electrophysiological imaging as well as broader, encompassing theory of learning and generalization.

The finite element analysis (FEA) has been done for polyurethane discs, one of the main components of a disc bearing, with necessary boundary conditions under compressive and rotational loadings and their integrated behavior have been studied. The compressive stiffness, rotational stiffness, bulging pattern, compressive stresses, shear stresses, and shear strain of the discs have been determined from the analysis. The results are validated with the experimental results. The results obtained from FEA are later compared with analytical results and found out that the compressive stiffness calculated from both are alike, however, the analytical method overestimates the rotational stiffness. To resemble with FEA results, the formula for both the compressive and rotational stiffnesses are proposed. In addition, failure theory has also been developed based on the FEA results. Hence, this study can be referenced to understand the behavior of the polyurethane discs, stiffnesses calculations, and develop a possible failure theory to incorporate in AASHTO specifications.

This non-experimental correlational study assessed the effectiveness of a model of teacher preparation that infuses a focus on teaching English learners, the One-Plus model, by examining pre-service teachers' (PST) effectiveness in narrowing English learner achievement gaps during their final student teaching experience. The study spanned five semesters of internship data, exploring how each semester's PST effectiveness changed over time. This study utilized teacher work sample data that interns collected and submitted to the institutional effectiveness division of the college, with an n of 20,809 K-12 students who attended the 768 One-Plus PSTs' classes during their semester-long internship. The results showed that there remained a statistically significant achievement gap between student groups based on their sociodemographic characteristics, and the biggest gap was between EL and non-EL students. Students had statistically significantly higher posttest scores compared to the pretest scores, and the rate of change in test scores was much steeper in historically low-achieving students than their counterparts. There was an approximately 50% decrease in EL's achievement gap in the posttest model compared to the pretest. Likewise, the gaps between low-SES and high-SES students, students with exceptionalities and students without exceptionalities, Black and White Students, and Hispanic and White students were reduced by approximately 40%, 38%, 48%, and 26%, respectively. Finally, there was a statistically significant linear growth in students' posttest scores over a period of five semesters.

Human gut microbiota is comprised of thousands of species which fall into two major categories or “enterotypes” based on dominating bacteria: “Bacteroides” and “Prevotella”. Bacteroides enterotype dominates the microbiota of the western population because of a high protein and fat diet, whereas Prevotella enterotype is dominate in the gut of the eastern population because of a high carbohydrate diet. While most of the microbiota studies focused on the Bacteroides enterotype using both metagenomics and culturomics, Prevotella enterotype is understudied, especially in the field of culturomics. The structure of the Prevotella dominated gut microbiome is revealed by metagenomic studies, but the individual bacterial species and their characteristics require culturomics and phenotypic characterization studies. To understand how microbes assemble into communities and provide colonization resistance against pathogens, we used the culturomics approach to capture the bacterial diversity of the Prevotella dominated community. We cultured 1590 isolates belonging to 102 bacterial species and characterized them for their substrate utilization, short chain fatty acid production and inhibition of Clostridium difficile. We found that 66 bacterial species were able to inhibit C. difficile in vitro. Furthermore, using a combinatorial community assembly approach, we identified the minimum number of bacteria required to resist C. difficile in vitro is twelve. During this culturomics, we also isolated two novel bacterial species from the Prevotella dominated microbiome. Furthermore, to understand how the Prevotella dominated community is shaped by certain prebiotic substrates, we combined rice bran and quercetin to analyze their effect on microbiome composition in minibioreactors. The combination of these prebiotics significantly reduces potential pathogenic bacteria by alleviating propionate levels. Also, there are studies suggesting inhibition of C. difficile may occur by conversion of bile acids by C. scindens. We analyzed the genetic differences of five C. scindens strains and tested their ability to inhibit C. difficile in vitro. We found a variation in C. scindens genomes and their ability to inhibit C. difficile in the presence and absence of bile. This research improves our understanding of gut microbiota using culturomics and identifies mechanisms utilized by gut microbes to inhibit C. difficile in vitro, which is valuable step in the development of biotherapeutics for gut diseases in future.

In addition to the remarkable intrinsic features of carbon materials, such as high specific surface area, large pore volume, high thermal and chemical stability etc., introduction of some other physiochemical properties (heteroatom doping, graphitic domains, nanostructure design) is essential for enhancing their performance in adsorption, catalysis, energy storage/ conversion or even extend their applications in biomedicine, drug delivery, etc. Although some of these features have been achieved by using various set of precursors and different experimental conditions, the bottleneck of such precursor-driven development is costly, time and energy consuming. This dissertation aspires to elaborate an alternative strategy to finely tune the desired properties using a single precursor set (resorcinol and formaldehyde) in a cost-effective way by adopting very popular one-pot Stober-like synthesis. The first project is devoted towards the exploration of the effect of the amount of tetraethyl orthosilicate on i) porosity tuning from micropores to mesopores, ii) nanostructure tuning from homogeneously distributed mesoporous carbon, hollow mesoporous carbon spheres and even to core-shell -shell carbon spheres of different density. This study further discusses the role of ethanol-water ratio in such structural evolution. The second project shows a novel route to obtain nitrogen-doped carbon spheres with precisely tailorable sizes using polyvinyl pyrrolidone-assisted Stober method at elevated temperature, which eliminates the need of post-synthetic hydrothermal treatment making this synthesis industrially scalable.The third project focuses on the synthesis of graphitic porous carbon spheres with incorporated very small nickel nanoparticles by simply modifying the Stober-like synthesis. The sintering of nanoparticles during thermal treatment was effectively reduced by adding amino acids (histidine or arginine) during the synthesis. The fourth project extends the incorporation of uniform, small-sized nickel nanoparticles in highly ordered, high-surface-area porous supports like MCM-41-carbon composites with the aid of histidine. The recipe of general synthesis of MCM-41 was simply modified by adding optimum amount of resorcinol, formaldehyde as carbon precursors and nickel nitrate as nickel precursor till the ordered MCM-41 type of mesostructure was retained.

Even though flood damage cannot be fully controlled, its effect can be minimized to some extent by careful planning, flood mitigation measures, and an effective flood warning system. Therefore, flood warning systems with flood travel time and inundation area information, derived from accurate model prediction, can be very effective to reduce potential flood damage. While a one-dimensional (1D) model was developed in the former research for the flood warning system, there has not been many comparative assessment of model performance among 1D, two-dimensional (2D), and coupled one-dimensional and two-dimensional (coupled 1D/2D) models particularly in HEC-RAS. Therefore, this research is an extension of the prior research and was especially conducted to calculate and compare the predictive capability of 1D, 2D, and coupled 1D/2D HEC-RAS models for the computation of travel time of flood and extent of flooded area needed for a flood warning system. The research was carried out in the Grand River in Lake County, Ohio. The model performance of 1D, 2D and coupled 1D/2D models were evaluated and sensitivity analysis was conducted using the same set of flow conditions and geometric conditions. The analysis suggested that 2D model could incredibly improve the model performance compared to 1D and coupled 1D/2D models, which were evaluated through the model evaluation indicators for the observed and simulated model outputs. Additionally, sensitivity analysis of input parameters, including discharge and Manning’s roughness, revealed that the 2D model was comparatively less sensitive to the changes in model inflow and Manning's roughness compared to the coupled 1D/2D and 1D models. Furthermore, the flood travel time computed using 1D model was more predicted than that of the 2D model, indicating that the 2D model would be most appropriate to provide a safe evacuation time for the community before flood events. The 1D model consistently over predicted than that of the 2D model, which was also true for the estimation of the inundation flood zone (4.1% higher).In addition, the appropriate assessment of flood damage in the aftermath of major flooding is crucial for flood management agencies, emergency responders, and insurance companies. Therefore, damage assessment is an important step in the evaluation of the flood mitigation measures, vulnerability analysis and flood risk mapping. This is particularly true in a context that the damage assessment so far has been primarily relying on either the coarse resolution, 30m digital elevation model (DEM), or 1D hydraulic model. As this researcher is not aware of any explicit incorporation of 2D HEC-RAS model for the damage assessment among the scientific communities, another major objective of this analysis is to outline the effects of some of the key factors including the mode of hydraulic simulation (1D vs 2D), the effect of inventory data, and the effect of topography on the flood loss estimation. This was accomplished using the 1D and 2D HEC-RAS models to produce the flood depth grids from the varying degree of topographic resolutions including 30m, 10m and LiDAR-derived DEM with and without incorporating actual field survey of the river in each case. The flood loss was estimated using Hazards United States Multi-Hazards (HAZUS-MH) loss estimation software developed by Federal Emergency Management Agency (FEMA) software, for each building within study area for flood events of various recurrence intervals from 10 to 500-year return periods. This was accomplished by updating the default-building inventory within Lake County to represent the actual building information in the model. The analysis indicated that 1D model consistently overestimated the loss in general by 61.48% for the default database and 86.12% for updated inventory. The estimation of the 1D model was consistently larger compared to the 2D model for different set of topographic resolutions and recurrence intervals. These loss estimations significantly increased when analyzed using a coarse resolution terrain, which was true regardless of selecting 1D or 2D models. Furthermore, the 2D model showed a lesser percentage increase (10.45% in 10m DEM, and 25.49% in 30m DEM), whereas the 1D model exhibited a larger increment (23.17% in 10m DEM and 76.81% in 30m DEM). This analysis suggested that the loss estimation would decrease in general by 76.21% after incorporating additional local building data into the HAZUS-MH database. More specifically, this analysis concludes that 2D model with high-resolution topographic data, including the additional incorporation of local data, in HAZUS-MH database are tremendously essential for appropriate flood damage assessment.

This research aims to explore gender relations in the course of student migration from Nepal. It enquires into how Nepalese migrant students in Australia continue or discontinue traditional gender roles by disclosing the lived experiences of a small cohort of Nepalese female students in Brisbane, Australia. A review of the relevant literature indicated that, despite significant development in the field of gender and migration research worldwide, the gender aspect of Nepalese student migration is still under-researched. Responding to this gap, I have developed a study that investigates the ways in which Nepalese female student migrants are negotiating gender relations between home and abroad. This study revolves around their changing perspectives on traditional gender relations as a result of living in the changed socio-cultural settings of host country, and the inherent challenges of implementing the changes in conventional interpretations of gender- based roles after returning their home country. Importantly, I share the same ethnic background and similar migration history with the research participants. Furthermore, my several years of professional experiences in education consultancies became the primary motivation for commencing this study from the position of an ‘insider researcher’ utilising both ethnographic observation and autoethnographic reflection as research tools. Six married Nepalese female students, studying in different institutions in Brisbane, were requested to participate in a qualitative semi-structured interview. In addition, I draw from autoethnographic observations and reflection on my personal encounters as a student migrant in Australia, as well as professional engagement as an education consultant. The semi-structured interviews provided the primary data for the research. Interview transcripts were manually coded based on their affinity with two distinct themes: negotiating in-betweenness in gender relations in the course of living in a different context; and circumstances of mobility either in the origin country or in the host country. At the same time, whether playing the role of passive observer or interviewing the participants as a researcher, their activities, as well as personal experiences and stories, were at times similar to my own. The most revealing and common experiences of all the participants after living in Australia was the feeling of emancipation from the yoke of patriarchy, which required them to play traditional gender roles in their country of origin. In spite of their commitment to make people aware of this new-found freedom, even after returning to their country of origin, the lack of confidence to continue to live with this changed philosophy of life was equally evident in their responses. Moreover, mixed opinions about the metamorphosis of their male counterparts regarding doing and undoing gender also posed a question on whether or not the Nepalese males would continue to cooperate with their wives in introducing changes in the traditional gender roles upon returning to their home country.

South Asia has the second largest burden of perinatal and childhood mortality in the world and Nepal has been reported as a significant contributor to this burden within the region. The main aim of this thesis was to statistically model perinatal and childhood mortality in Nepal. Specifically, this thesis will first conduct a systematic review of factors associated with perinatal mortality in South Asia including Nepal. Second, socioeconomic predictors of stillbirths in Nepal will be examined. Third, Factors associated with perinatal mortality in Nepal will be identified. Finally, this thesis will examine factors associated with under-5 mortality in Nepal. Chapter 2 identifies the factors associated with perinatal and childhood mortality through literature review. The systematic literature review revealed the most common factors associated with perinatal mortality were: low socioeconomic status, lack of quality health care services, pregnancy/obstetric complications and lack of antenatal care. Similarly, poor socio economic status, rural residence, higher birth order and lower birth interval, use of contraceptives, polluted fuel for cooking at home, and antenatal care were found to be associated with under-5 mortality. Chapter 4 examined the socio-economic predictors of stillbirth in Nepal. Multivariable analysis and found maternal age (>25years), ecological zone (mountains or hills), religion (Hindu, Muslim, Christian and others), low maternal education, mother’s occupation (farming) and the use of open defecation system are associated with stillbirth. Chapter 5 presents the factors associated with Perinatal Mortality (PM) and Extended Perinatal Mortality (EPM) in Nepal. In this study, PM rate was 42 [95% Confidence Interval (CI): 39, 44] per 1000 births and the corresponding EPM rate was 49 [95% CI: 46, 51] for the five-year prior each survey (2001-2016). Multivariable analysis revealed that ecological zone, household wealth index, birth order and birth interval; maternal age, use of contraceptives, and types of cooking fuel were associated with PM and EPM. Chapter 6 assesses the common factors associated with neonatal, post-neonatal, infant, child, and under-5 mortality in Nepal, and the study found that the death of the previous child, non usage of contraceptives and non-receipt of TT vaccination during pregnancy were associated with inder-5 mortality. In summary, household with poor socio-economic status, and non-use of contraceptives among mothers were strongly associated with perinatal, and under-5 mortality in Nepal. Hence, future intervention to reduce perinatal and under-5 mortality should focus on family planning and these intervention should target mothers from socioeconomically disadvantaged groups.

In this thesis, we consider the problem of tracking in complex nonlinear dynamical systems. While the Kalman filter is known to be the mean-squared error optimal tracker under linear dynamics and linear measurements, more sophisticated models and algorithms are required for complex dynamics. Here, we consider switching systems where the dynamical properties vary (''switch modes") over time. For example, the dynamics of a vehicle may switch as it transitions from interstate to urban conditions, human speech dynamics switch as speakers change, and stock market dynamics switch with discrete news events. In this work, we use mode-dependent neural networks to capture different nonlinear dynamics in a given system, and we developed a new algorithm, dubbed the Switching Neural Network Tracker (SNNT), to track modes and states over time. The proposed Bayesian system includes Markovian dynamics to model mode transitions and employes the Unscented Transform to mitigate computational complexity while estimating posterior probabilities. Examples using synthetic robot motion data and measured honeybee dance data demonstrate accurate mode identification and a dramatic reduction in state estimation error relative to non-switching systems.

Agile software is a collection of software development methods based on iterative and incremental development processes. In an Agile software development approach, the requirements and solutions are obtained through the collaboration and coordination of cross-functional teams with the customer. Agile software development processes aim to produce higher quality software than traditional approaches, and this is supported by both anecdotal and empirical evidence. However, there is little understanding about the relationship between the software development team and the product owner, and the impact this relationship has on project outcomes. The Teamwork model can be used to understand the relationships in the team using Agile software development. Agile software development adopts sets of practices and roles for organizing work during a software development project. However, some challenges exist in Agile software development that impact on the relationships between development team and the product owner. This research identifies these challenges with Agile and explains their impact on the relationship using the Teamwork model. To understand the relationship challenges, a mixed method multi-study approach was undertaken. Data collection from participants involved two instruments: an online questionnaire and a semi-structured interview. Responses from the online questionnaire were analysed using descriptive and inferential statistical methods, and thematic analysis methods were used for qualitative data analysis of the interviews. Two studies were conducted, one with software development teams and one with product owners. Discussion of the results from both studies are presented and then compared in order to understand the relationships from both perspectives. The findings indicated that there were challenges in communication, project requirements, project priorities and project timelines within the team as well as between the team and the product owner. Challenges in communication, project priorities, interpersonal issues and project requirements, have an impact on the completion time of the project. The Teamwork model explained some of the relationship challenges between the Agile software development team and the customer. Challenges that fall outside the original Teamwork model contributed to understanding what factors constituted effective teamwork when applying an Agile process to software development. As a result of the findings from this current research, a revision to the Teamwork model was proposed that introduced two additional constructs: team motivation and organizational culture to the model. Team motivation impacts on the coordination, communication and team support. Organizational culture sets the overall context for the relationship between product owner and software development team. Communication within the relationship has the highest impact on project outcomes.

Planar and stereo particle image velocimetry measurements were conducted of a wing-tip vortex decaying in free-stream turbulence in order to understand the evolution of a vortex and its decay mechanism. The vortex decayed faster in the presence of turbulence. The decay of the circulation was found to be almost entirely due to a decrease in circulation of the vortex core, caused by the relative decrease in peak tangential velocity without a corresponding increase in core radius. These events were found to be connected with the stripping of core fluid from the vortex core. The increased rate of decay of the vortex in turbulence coincided with the formation of secondary vortical structures which wrapped azimuthally around the primary vortex. It was also found that regardless of the free-stream condition, the core scaled by peak tangential velocity and core radius.

Due to widespread and long-term application, Lithium-ion batteries are considered as promising power sources for portable devices, satellites, medical instruments, computers, electric vehicles and grid application. It started to occupy the market once Sony commercialized in 1991. Rechargeable lithium ion batteries drawing people attention due to their peculiar properties such as high energy density and low self-discharge compared to other alkali metals. However, these widespread and long-term applications still require better batteries in terms of performance, safety and cost, which can be achieved by better utilization of anode materials and/or an optimized design of battery configuration. There are several challenges in improving the battery performance, safety and to reduce the cost. The goal of this work was to design a high-performance battery with fabricating porous current collector and copper oxide. Current collector are essential features of batteries and being responsible for efficient charge transport to active electrode materials. In this study, a chemically treated high surface area, three-dimensional copper current collectors considerable improve the anodic performance of a batteries, by means of enhance in specific capacity and control over the fast decay. The electron transfers rapidly at the junction of the metal foam, the active material, and the electrolyte which increase the rate of redox reaction. On the other hand, the transfer of electron relatively slowly between foil current collector and the electrolyte surface of the active material. Impedance analysis also reveals that the charge transfer resistance is lower in porous copper current collector than the non-porous one. Unique properties of porous copper current collector improve the first discharge specific capacity of Li2 Ti5O12 (LTO) from 168.5 mAhg-1 to 235.8 mAhg-1 in comparison with the non-porous copper current collector. Moreover, fabrication of binder-free copper oxide on top of porous copper can open new window to the battery research.

The Watanabe-Cenini-Söderberg reductive N-heterocyclization has emerged as a powerful tool for the synthesis of a variety of functionalized indoles. Söderberg’s elaboration of this methodology has been utilized as a late-stage cyclization protocol for the synthesis of azepinoindole alkaloids, a class of natural products characterized by an azepane skeleton fused with an indole ring. Short syntheses of the naturally occurring azepino[5,4,3-cd]indole alkaloids, cimitrypazepine, fargesine, and the diastereomeric hyrtioreticulins C & D have been completed starting from commercially available tetra-substituted benzene derivatives. The key azepinoindole core in each case was assembled via an intramolecular Mizoroki-Heck reaction followed by a Watanabe-Cenini-Söderberg reductive N-heterocyclization. Synthesis of aurantioclavine using a similar strategy is currently underway.

Enteric coronaviruses (CoVs) of pigs include transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV) and porcine delta coronavirus (PDCoV). They cause significant economic losses in pig industry worldwide. In the US, PEDV emerged in 2013 and caused the death of over 7 million piglets within the first year. Feral pigs have contributed to the transmission of different viral, bacterial and parasitic infections to domestic pigs, other domestic animals and even to humans. However, their role in maintenance and transmission of porcine enteric CoVs is not well understood. In this study, fecal samples of 44 feral pigs were collected from California, USA in early-mid 2016. RNA was extracted from the fecal content supernatant and subjected to conventional reverse transcription (RT)-PCR using two different panCoV primers to detect the presence or absence of porcine enteric CoVs. Quantitative RT-PCR (RT-qPCR) using PEDV N gene and PDCoV M gene specific primers and probes were also performed for amplification of specific viral genes. DNA sequencing of PCR products from likely positive sample was also performed for further confirmation. None of the samples were clearly positive using conventional RT-PCR assays. Few samples were doubtful for PEDV or PDCoV genes and showed Ct values slightly above the detection limit. Repeated testing and/or DNA sequencing confirmed that those samples were negative for PEDV or PDCoV presence. Our results indicated that no porcine enteric CoVs were circulating in the feral pigs in California in early-mid 2016. Similar studies from other states of USA with larger sample sizes will be helpful to ascertain whether wild pigs in USA are playing a role in the maintenance and transmission of porcine enteric CoV or not.

Groundbreaking progress in molecule-based optoelectronic devices for lighting, display and energy-harvesting technologies demands highly efficient and easily processable functional materials with tunable properties governed by their molecular/supramolecular structure variations. To date, functional coordination compounds whose function is governed by non-covalent weak forces (e.g., metallophilic, dπ-acid/dπ-base stacking, halogen/halogen and/or d/π interactions) remain limited. This is unlike the situation for metal-free organic semiconductors, as most metal complexes incorporated in optoelectronic devices have their function determined by the properties of the monomeric molecular unit (e.g., Ir(III)-phenylpyridine complexes in organic light-emitting diodes (OLEDs) and Ru(II)-polypyridyl complexes in dye-sensitized solar cells (DSSCs)). This dissertation represents comprehensive results of both experimental and theoretical studies, descriptions of synthetic methods and possible application allied to monovalent coinage metal-based functional materials. The main emphasis is given to the design and synthesis of functional materials with preset material properties such as light-emitting materials, light-harvesting materials and conducting materials. In terms of advances in fundamental scientific phenomena, the major highlight of the work in this dissertation is the discovery of closed-shell polar-covalent metal-metal bonds manifested by ligand-unassisted d10-d10 covalent bonds between Cu(I) and Au(I) coinage metals in the ground electronic state (~2.87 Å; ~45 kcal/mol). Moreover, this dissertation also reports pairwise intermolecular aurophilic interactions of 3.066 Å for an Au(I) complex, representing the shortest ever reported pairwise intermolecular aurophilic distances among all coinage metal(I) cyclic trimetallic complexes to date; crystals of this complex also exhibit gigantic luminescence thermochromism of 10,200 cm-1 (violet to red). From applications prospective, the work herein presents monovalent coinage metal-based functional optoelectronic materials such as heterobimetallic complexes with near-unity photoluminescence quantum yield, metallic or semiconducting integrated donor-acceptor stacks and a new class of Au(III)-based black absorbers with cooperative intermolecular iodophilic (I…I) interactions that sensitize the harvesting of all UV, all visible, and a broad spectrum of near-IR regions of the solar spectrum. These novel functional materials of cyclic trimetallic coinage metal complexes have been characterized by a broad suit of spectroscopic and structural analysis methods in the solid state and solution.

Optical tweezers are used to investigate small particles from a few micrometers to subnanometer in size at the molecular level. The optical tweezers manipulate molecules tethered between micrometer-sized particles and measures the force of these interactions, which is on the scale of piconewtons. With these advantages, optical tweezers are widely used to study structures and functions of DNA, RNA, and proteins as well as viruses, bacteria, and cells. In this dissertation, use of optical tweezers to study lipid droplet fusion as a single particle research will be presented. The lipid droplet fusion mechanism is relevant to understand growth of lipids inside the cell and its relation with diseases like obesity and fatty liver. Besides lipid droplet fusion, investigation of DNA G-Quadruplexes and its interaction with ligands at a single molecule and sub-molecule level will be presented. This research on the G-Quadruplex gives insight into the structural-stability relation relevant to target it as a means of new cancer therapy.