/library/oar/handle/123456789/2064 Thu, 06 Nov 2025 21:42:52 GMT 2025-11-06T21:42:52Z /library/oar/handle/123456789/140906 Title: Of comets and cosmology in Antonino Saliba's Nuova Figura di tutte le cose of 1582 Authors: Caruana, Joseph Abstract: Antonino Saliba, a sixteenth century cartographer hailing from the Maltese island of Gozo, published a map in 1582 espousing his cosmology. Its popularity at the time is attested via the multiple editions and copies that were produced in Europe. Numerous sky phenomena, amongst them comets, are portrayed in the map. This study presents a detailed analysis of Saliba's treatment of these phenomena, following the first comprehensive translation of the map's text to English. It elucidates the sources that Saliba used, clarifying and shedding further light on the views he held. Where possible, the comets mentioned by Saliba are identified and explained. Besides showing how Saliba wholly conformed to the Aristotelian and Ptolemaic representation of the world, in which respect he was quite orthodox, it is also shown for the first time that his work is significantly derived from previous and contemporary sources. Mon, 01 Jan 2024 00:00:00 GMT /library/oar/handle/123456789/140906 2024-01-01T00:00:00Z /library/oar/handle/123456789/140597 Title: Variational quantum algorithms for thermal states preparation Abstract: The quantum simulation of thermal equilibrium states is a promising near-term application of quantum computation, with applicability in fields such as quantum chemistry. This dissertation investigates Gibbs state preparation of the free fermion Hamiltonian using a variational quantum algorithm (VQA). While the Grover-Rudolph algorithm can prepare an arbitrary distribution of 2n probabilities using 2n − 1 circuit parameters, it does not achieve quantum advantage, since it offers no exponential speed-up over classical methods. This work is motivated by the circuit optimisation problem: can the properties of the free fermion Hamiltonian be used to design a more efficient Ansatz for this problem with a reduced number of gate parameters? By investigating the properties of the Gibbs states for small numbers of qubits, results were found suggesting that the Gibbs states of the free fermion Hamiltonian can be generated with only n single-qubit gates, without requiring any entangling gates. This optimised single-qubit gate circuit was used as the Ansatz in a VQA for Gibbs state preparation, and the calculated and target probability distributions were compared for different system sizes and temperatures using the VQA cost function as well as various distance measures. The VQA results show that the single-qubit Ansatz is expressible enough for up to n = 5 qubits, reducing the circuit complexity for this problem. Description: B.Sc. (Hons)(Melit.) Wed, 01 Jan 2025 00:00:00 GMT /library/oar/handle/123456789/140597 2025-01-01T00:00:00Z /library/oar/handle/123456789/140596 Title: Dielectric and thermal properties of phantoms for electromagnetic based hyperthermic technologies Abstract: Hyperthermia, a therapeutic technique used in cancer treatment, relies on the precise heating of target tissues to enhance the effectiveness of radiotherapy or chemotherapy. To achieve this, electromagnetic (EM)-based hyperthermic technologies require accurate simulation of human tissue properties under hyperthermia conditions (40–48°C). However, existing tissue-mimicking phantoms face limitations, particularly at higher temperatures, hindering reliable testing of hyperthermia devices. This dissertation addresses this challenge by developing phantoms that replicate the dielectric and thermal properties of skin, fat, muscle, and tumour tissues at temperatures up to 50°C. This work improves the semi-solid phantom recipe proposed by Lazebnik et al. (2005) by replacing the gelling agent gelatine with agar-agar, thereby increasing the melting point while maintaining tissue-like behaviour. Additionally, the project will provide a thorough characterisation of the dielectric and thermal properties of these phantoms, ensuring they closely match the electromagnetic and thermal properties of real tissue across a range of frequencies and temperatures. The modified agar-based phantoms demonstrate successful replication of real tissue properties under hyperthermia conditions, exhibiting less than 20% deviation from literature values. This confirms their validity for precise laboratory evaluation of electromagnetic (EM)-based medical devices, particularly for hyperthermia treatment planning and device calibration. By developing these phantoms, this research aims to enable the accurate testing and optimisation of EM-based hyperthermic devices in the laboratory, reducing the need for extensive preclinical trials and accelerating the transition to clinical validation. This work has the potential to significantly improve the safety and efficacy of hyperthermic technologies, ultimately contributing to better outcomes in cancer treatment and other medical applications. Description: B.Sc. (Hons)(Melit.) Wed, 01 Jan 2025 00:00:00 GMT /library/oar/handle/123456789/140596 2025-01-01T00:00:00Z /library/oar/handle/123456789/140595 Title: Exploring late-time cosmic evolution through dynamical systems in non-minimally coupled scalar-tensor models Abstract: This dissertation explores late-time cosmic evolution through the lens of scalartensor theories using a dynamical systems approach. Although the Λ Cold Dark Matter (ΛCDM) model has been successful in accounting for the accelerated expansion of the Universe, it faces persistent theoretical challenges such as the cosmological constant problem and observational tensions like the Hubble constant (H0) discrepancy. Scalar fields central to early-universe inflation and now considered candidates for dark energy offer a promising extension to standard cosmology. We construct dynamical systems by introducing non-minimal scalar field couplings into the cosmological equations, focussing on exponential and power-law potentials. The resulting systems are analysed using critical points, stability theory, and phase portraits to reveal attractor solutions and asymptotic behaviours. Our study demonstrates that certain scalar-field models can replicate the late-time acceleration of the Universe while offering richer dynamics than the cosmological constant alone. Many of the models explored exhibit the key critical points found in ΛCDM and, in some cases, additional points that reflect a more nuanced evolution profile. These results underscore the utility of dynamical systems in probing beyond-ΛCDM scenarios and provide a pathway for future observational tests of scalar-tensor cosmologies. Description: B.Sc. (Hons)(Melit.) Wed, 01 Jan 2025 00:00:00 GMT /library/oar/handle/123456789/140595 2025-01-01T00:00:00Z