Fixed-wing UAV tracking of evasive targets in 3-dimensional space

In this thesis, we explore the development of autonomous tracking and interception strategies for single and multiple fixed-wing Unmanned Aerial Vehicles (UAVs) pursuing single or multiple evasive targets in 3-dimensional (3D) space. We considered a scenario where we intend to protect high-value facilities from adversarial groups employing ground-based vehicles and quadrotor swarms and focused on solving the target tracking problem. Accordingly, we refined a min-max optimal control algorithm for fixed-wing UAVs tracking ground-based targets, by introducing constraints on bank angles and turn rates to enhance actuator reliability when pursuing agile and evasive targets. An intelligent and persistent evasive control strategy for the target was also devised to ensure robust performance testing and optimisation. These strategies were extended to 3D space, incorporating three altitude control algorithms to facilitate flexible UAV altitude control, leveraging various parameters such as desired UAV altitude and image size on the tracking camera lens. A novel evasive quadrotor algorithm was introduced, systematically testing UAV tracking efficacy against various evasive scenarios while implementing anti-collision measures to ensure UAV safety and adaptive optimisation improve the achieved performance. Using decentralised control strategies, cooperative tracking by multiple UAVs of single evasive quadrotor-type and dynamic target clusters was developed along with a new altitude control strategy and task assignment logic for efficient target interception. Lastly, a countermeasure strategy for tracking and neutralising non-cooperative adversarial targets within restricted airspace was implemented, using both Nonlinear Model Predictive Control (NMPC) and optimal controllers. The major contributions of this thesis include optimal control strategies, evasive target control, 3D target tracking, altitude control, cooperative multi-UAV tracking, adaptive optimisation, high-precision projectile algorithms, and countermeasures. We envision practical applications of the findings from this research in surveillance, security, search and rescue, agriculture, environmental monitoring, drone defence, and autonomous delivery systems. Future efforts to extend this research could explore adaptive evasion, enhanced collaborative UAV swarms, machine learning integration, sensor technologies, and real-world testing

Vision based strategies for implementing Sense and Avoid capabilities onboard Unmanned Aerial Systems

Current research activities are worked out to develop fully autonomous unmanned platform systems, provided with Sense and Avoid technologies in order to achieve the access to the National Airspace System (NAS), flying with manned airplanes. The TECVOl project is set in this framework, aiming at developing an autonomous prototypal Unmanned Aerial Vehicle which performs Detect Sense and Avoid functionalities, by means of an integrated sensors package, composed by a pulsed radar and four electro-optical cameras, two visible and two Infra-Red. This project is carried out by the Italian Aerospace Research Center in collaboration with the Department of Aerospace Engineering of the University of Naples “Federico II”, which has been involved in the developing of the Obstacle Detection and IDentification system. Thus, this thesis concerns the image processing technique customized for the Sense and Avoid applications in the TECVOL project, where the EO system has an auxiliary role to radar, which is the main sensor. In particular, the panchromatic camera performs the aiding function of object detection, in order to increase accuracy and data rate performance of radar system. Therefore, the thesis describes the implemented steps to evaluate the most suitable panchromatic camera image processing technique for our applications, the test strategies adopted to study its performance and the analysis conducted to optimize it in terms of false alarms, missed detections and detection range. Finally, results from the tests will be explained, and they will demonstrate that the Electro-Optical sensor is beneficial to the overall Detect Sense and Avoid system; in fact it is able to improve upon it, in terms of object detection and tracking performance

Catalytic bio-hybrid polymersomes: towards novel biomedical applications

Merging synthetic polymers with potent biomolecules is an effective strategy to build hybrid systems that benefit from the best of both worlds. However, the combination of polymers with biomolecules bearing strong appeal for biomedical applications, e.g., enzymes producing therapeutic compounds or detectable signals as diagnostic indicators, is often compromised due to the properties of the polymers not matching the requirements for the incorporation of the said active biomolecules. Hence, bio-hybrid polymer nanosystems have yet to develop their full potential for biomedical applications. Chapter 1 introduces the concept of mimicking compartmentalization of biological cells by the means of synthetic polymers able to build nanocompartments with a large potential for accommodating various biomolecules. An overview of polymer properties, self-assembly of amphiphilic block-copolymers and polymersome formation techniques, as well as target applications of bio-hybrid nanocompartments is given. Finally, strategies to overcome drawbacks of such hybrid systems are introduced. Chapter 2 describes the aim of this work which is to set stage for biomedical applications involving innovative catalytic nanocompartments encapsulating enzymes. The targeted applications and adopted strategies to develop different bio-hybrid systems are presented. Chapter 3 highlights the development of a theranostic polymersome-based super assembly aimed at providing a novel type of treatment for atherosclerosis. Separate imaging and therapeutic nanocompartments were tethered together via hybridizing surface-exposed, complementary DNA strands, to form dual-functional polymersome clusters with simultaneous therapeutic and imaging properties. On one hand, on-site dopamine production was achieved by therapeutic compartments encapsulating active Dopa Decarboxylase (DDC), which are permeabilized by membrane insertion of OmpF porin. On the other hand, imaging compartments containing fluorescent dyes enabled tracking of the complete super-assemblies in parallel to their attachment to epithelial cells. Special emphasis is placed on the modularity of such polymersome clusters, as this system represents a novel platform for future dual-functional systems aiming at other biomedical applications. Chapter 4 presents a polymersome-based bioluminescent system that is able to produce a strong and long-lasting light signal as is desired for pre-clinical imaging applications. The encapsulation of Gaussia Luciferase (GLuc) within the cavity of polymersomes enabled efficient light production. The diffusion of GLuc substrate thought the membrane-inserted OmpF was exploited to modulate the enzyme kinetics such that the signal turned long-lasting. The applicability of such a system was investigated in vitro in cultured cells and in vivo in a mouse model. Chapter 5 illustrates how mimicking native organelles can be exploited to provide a novel bio-hybrid system showing cell-photoprotective potential. Melanosome mimics were developed via encapsulation of Tyrosinase together with precursors L-DOPA/Dopamine to form macromolecular melanin/polydopamine (PDA) within the cavity of polymersomes. By enclosing the melanin/PDA production, the polymeric membrane prevents the major pitfalls associated with synthetic melanin/PDA nanoparticles and enables a bio-hybrid system with reduced cytotoxicity and enhanced colloidal stability while UV-absorption properties are preserved. Finally, the mix and match of strategies employed to build the different bio-hybrid systems, the challenge of balancing the polymer/biomolecules selection with the design and optimization possibilities, and the potential of the resulting bio-hybrid systems to evolve into novel biomedical applications are discussed (chapter 6). Complementary material including additional experimental details (chapter 7), relevant literature (chapter 8), contributor and funding acknowledgment (chapter 9), and supplementary figures (chapter 10) conclude this thesis

Developing tools to study carbohydrate processing enzymes in AmpC β-lactamase antibiotic resistance and OGA-based neurodegenerative research

Carbohydrates are one of the four main classes of biological macromolecules in nature, alongside lipids, proteins, and nucleic acids. They serve in a wide range of cellular functions fundamental to the existence of biological organisms. These functions include but are not limited to cellular metabolism, energy production and storage, structural support, signaling, and recognition. The ubiquitous presence of carbohydrates in organisms has led to the study of their role in various maladies, such as neurodegenerative and infectious diseases. Deciphering the role of carbohydrates in these diseases allows for the possibility of developing treatments for associated diseases. In this manner, it is necessary to develop tools to exploit and test our understanding of these mechanisms. Existing methodologies may need to be adapted for application to larger scale experimental designs, such as those used in chronic dosing studies using preclinical animal models or high-throughput automated screening assays. This thesis describes improvements to previously published methods in the synthesis of one such chemical tool, Thiamet-G, a small molecule inhibitor used to study the carbohydrate processing enzyme O-GlcNAcase, which has been linked to neurodegenerative diseases including Alzheimer’s and Parkinson’s Disease. This thesis also seeks to apply the concepts developed during creation of a live cell assay towards creation of a new experimental approach suitable for large scale high through-put screening of compound libraries. Such an application would allow for the efficient pursuit of inhibitors of the bacterial protein AmpG - a transporter that is essential for inducible AmpC β-lactamase-driven antibiotic resistance

Aerospace Medicine and Biology: A continuing bibliography, supplement 191

A bibliographical list of 182 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1979 is presented

Lipid-based nanoparticles for magnetic resonance molecular imaging : design, characterization, and application

In this thesis research is described which was aimed to develop lipidic nanoparticles for the investigation and visualization of atherosclerosis and angiogenesis with both magnetic resonance molecular imaging and optical techniques. The underlying rationale for this is that conventional MR imaging techniques are only capable of visualizing physiological and morphological changes, while magnetic resonance molecular imaging aims to depict cellular and molecular processes that are associated with or lie at the basis of pathological processes. This may lead to earlier detection, and improved diagnosis and prognosis of disease processes. Furthermore this technique may be very useful for the evaluation of a given therapy. The introduction of MRI as a molecular imaging modality is hampered by its low sensitivity compared to nuclear methods like PET and SPECT. With recent developments in chemistry and the synthesis of powerful, innovative, specific, and multimodal contrast agents, e.g. by introducing fluorescent properties as well, MRI is becoming increasingly important for molecular imaging. Therefore, the first aim of the research described in this thesis was to develop biocompatible nanoparticles that can be made target specific and can be detected by both MRI and optical techniques to allow the investigation of disease processes with two highly complementary imaging methods. Chapter 1 gives a general introduction in magnetic resonance molecular imaging and its potential use for the investigation of several pathological processes. Furthermore, contrast enhanced MRI based on differences in T1 and T2 relaxation times is explained. Lastly, different classes of contrast agents and their contrast generating properties are described. Amphphilic molecules are widely applied to serve as building blocks for nanoparticles in biomedical applications. In the field of drug targeting for example, liposomes comprised of amphiphilic molecules hold great promise and have been used extensively the last several decades. Furthermore, micelles, microemulsions, and other amphiphilic aggregates are also under investigation to serve as drug carriers. A relatively new application of lipidic nanoparticles is their use as contrast generating materials for MRI. In Chapter 2 the properties of amphiphilic molecules and their assembly in a wide range of aggregated structures are described. This is followed by an overview of different strategies that are employed to conjugate targeting ligand to such lipid based nanoparticles. The emphasis of this chapter is a literature overview of what has been realized in this research field thus far. Chapter 3 describes the physical characterization of novel liposomal contrast agents. The morphology of different formulations was investigated with electron microscopy, which revealed the necessity of incorporating cholesterol in the liposomal bilayer. Furthermore the relaxation properties of these contrast agent were measured as a function of temperature and magnetic field strength. In Chapter 4 a liposomal contrast agent with both fluorescent and magnetic properties is described. The liposomes were made target specific by conjugating multiple E-selectin specific antibodies to the surface of the nanoparticle. Its feasibility to serve as molecular imaging contrast agent for the detection of the inflammation marker E-selectin is demonstrated in vitro. The specific uptake of the liposomes by human endothelial cells stimulated to express E-selectin was visualized by MRI and fluorescence microscopy. Chapter 5 describes a superparamagnetic nanoparticle encapsulated in a micellular shell. Fluorescent properties were introduced to this contrast agent by the incorporation of fluorescent lipids in the lipid layer. The contrast agent has a very high r2/r1 ratio and therefore is especially suitable to be used for T2 (*) enhanced MRI. The nanoparticle can be made target specific by covalently linking targeting ligands distally to the PEG chains of lipids incorporated in the micellular shell via maleimide-sulfhydryl coupling. Specificity for apoptotic cells was realized by conjugating multiple Annexin A5 proteins. The feasibility to use this contrast agent for molecular imaging purposes was demonstrated in vitro on apoptotic Jurkat cells. In Chapter 6 the synthesis and characterization of a novel bimodal nanoparticle based on semiconductor nanocrystals encapsulated within the corona of paramagnetic micelles is described. The CdSe nanoparticle, also referred to as quantum dot, serves as the contrast generating material for fluorescence imaging, while the paramagnetic micellular coating is employed for contrast enhanced MRI. The in vitro association of this nanoparticle with isolated cells by either conjugating multiple avß3-integrin specific RGDpeptides or multiple phosphatidyl serine specific Annexin A5 proteins was demonstrated with both fluorescence microscopy and MRI. The second aim of the research described in this thesis was to apply the novel nanoparticles for the investigation of atherosclerosis and tumor angiogenesis in mouse models with magnetic resonance molecular imaging. Chapter 7 describes the application of non targeted paramagnetic liposomes for the improved and sustained visualization of neointimal lesions induced after placing a constrictive collar around the right carotid artery of apoE-KO mice. Commercially available Gd-DTPA (Magnevist) showed little potential for the detection of such lesion. In Chapter 8 pegylated micelles conjugated with macrophage scavenger receptor (MSR) specific antibodies were employed for improved atherosclerotic plaque detection and characterization. Existing nanoparticulate agents that are used to detect macrophages, such as USPIO or lipophilic micelles, show little specificity. The micelles used for this study have a hydrophilic PEG coating, and therefore show minimal non-specific interaction with plaque, which results in negligible background signal. In case of the MSR micelles a pronounced enhancement of atherosclerotic plaque was observed. Furthermore, the micelles exhibit fluorescent properties by the incorporation of either quantum dots or fluorescent lipids. This allowed the detection of macrophages with optical techniques as well. Chapter 9 and Chapter 10 describe the application of avß3 targeted bimodal liposomes for the visualization of angiogenically activated tumor blood vessels with both MRI in vivo and fluorescence microscopy ex vivo. The specificity of the contrast agent was demonstrated with an MRI competition experiment, while the exclusive association with endothelial cells was demonstrated with fluorescence microscopy. The follow-up study demonstrates the usefulness of contrast enhanced MRI after applying this contrast agent for the evaluation of angiostatic therapies, i.e. using endostatin and anginex, at two time points after onset of therapy. Most importantly, the in vivo MRI data show very good correlation with ex vivo microvessel density determinations. In the last experimental Chapter 11 of this thesis a sophisticated method for the parallel visualization of angiogenic tumor blood vessels with both intravital microscopy (IVM) and MRI is described. The nanoparticulate contrast agent conjugated with avß3-specific RGDpeptides described in Chapter 6 was administrated to tumor bearing mice. IVM allowed the investigation of the disease process at the cellular level, while MRI was used to investigate angiogenesis at the anatomical level. The contrast agent possesses excellent contrast generating properties for these complementary imaging techniques. Widespread angiogenic activity within the rim of the tumor, and up to 1 cm from the tumor boundary could be observed by using both techniques