10081 research outputs found
Sort by
Galaxy cluster cosmology in KiDS, Planck, and Euclid surveys
Get PDFIn this Thesis, we present a series of works that encompass the fundamental steps of cosmological analyses based on galaxy clusters, spanning from mass calibration to deriving cosmological constraints through counts and clustering.
Firstly, we focus on the 3D two-point correlation function (2PCF) of the galaxy cluster sample by Planck Collaboration XXVII (2016). The masses of these clusters are expected to be underestimated, as they are derived from a scaling relation calibrated through X-ray observations. We derived a mass bias which disagrees with simulation predictions, consistent with what derived by Planck Collaboration VI (2020).
Furthermore, in this Thesis we analyse the cluster counts and 2PCF, respectively, of the photometric galaxy cluster sample developed by Maturi et al. (2019), based on the third data release of KiDS (KiDS-DR3, de Jong et al. 2017). We derived constraints on fundamental cosmological parameters which are consistent and competitive, in terms of uncertainties, with other state-of-the-art cosmological analyses.
Then, we introduce a novel approach to establish galaxy colour-redshift relations for cluster weak-lensing analyses, regardless of the specific photometric bands in use. This method optimises the selection completeness of cluster background galaxies while maintaining a defined purity threshold. Based on the galaxy sample by Bisigello et al. (2020), we calibrated two colour selections, one relying on the ground-based griz bands, and the other including the griz and Euclid YJH bands.
In addition, we present the preliminary work on the weak-lensing mass calibration of the clusters detected by Maturi et al. (in prep.) in the fourth data release of KiDS (KiDS-1000, Kuijken et al. 2019). This mass calibration will enable the cosmological analyses based on cluster counts and clustering, from which we expect remarkable improvements in the results compared to those derived in KiDS-DR3
Black hole scattering from Worldline Quantum Field Theory and the Classical Double Copy of Spinning particles
Get PDFThis PhD thesis focuses on studying the classical scattering of massive/massless particles toward black holes, and investigating double copy relations between classical observables in gauge theories and gravity. This is done in the Post-Minkowskian approximation i.e. a perturbative expansion of observables controlled by the gravitational coupling constant κ = 32πGN, with GN being the Newtonian coupling constant. The investigation is performed by using the Worldline Quantum Field Theory (WQFT), displaying a worldline path integral describing the scattering objects and a QFT path integral in the Born approximation, describing the intermediate bosons exchanged in the scattering event by the massive/massless particles.
We introduce the WQFT, by deriving a relation between the Kosower- Maybee-O’Connell (KMOC) limit of amplitudes and worldline path integrals, then, we use that to study the classical Compton amplitude and higher point amplitudes. We also present a nice application of our formulation to the case of Hard Thermal Loops (HTL), by explicitly evaluating hard thermal currents in gauge theory and gravity.
Next we move to the investigation of the classical double copy (CDC), which is a powerful tool to generate integrands for classical observables related to the binary inspiralling problem in General Relativity. In order to use a Bern-Carrasco-Johansson (BCJ) like prescription, straight at the classical level, one has to identify a double copy (DC) kernel, encoding the locality structure of the classical amplitude. Such kernel is evaluated by using a theory where scalar particles interacts through bi-adjoint scalars. We show here how to push forward the classical double copy so to account for spinning particles, in the framework of the WQFT. Here the quantization procedure on the worldline allows us to fully reconstruct the quantum theory on the gravitational side. Next we investigate how to describe the scattering of massless particles off black holes in the WQFT
6G enabled IoV scenarios with distributed intelligence mechanisms
Get PDFThe Internet of Vehicles (IoV) paradigm has emerged in recent times, where with the support of technologies like the Internet of Things and V2X , Vehicular Users (VUs) can access different services through internet connectivity. With the support of 6G technology, the IoV paradigm will evolve further and converge into a fully connected and intelligent vehicular system. However, this brings new challenges over dynamic and resource-constrained vehicular systems, and advanced solutions are demanded. This dissertation analyzes the future 6G enabled IoV systems demands, corresponding challenges, and provides various solutions to address them. The vehicular services and application requests demands proper data processing solutions with the support of distributed computing environments such as Vehicular Edge Computing (VEC). While analyzing the performance of VEC systems it is important to take into account the limited resources, coverage, and vehicular mobility into account. Recently, Non terrestrial Networks (NTN) have gained huge popularity for boosting the coverage and capacity of terrestrial wireless networks. Integrating such NTN facilities into the terrestrial VEC system can address the above mentioned challenges. Additionally, such integrated Terrestrial and Non-terrestrial networks (T-NTN) can also be considered to provide advanced intelligent solutions with the support of the edge intelligence paradigm. In this dissertation, we proposed an edge computing-enabled joint T-NTN-based vehicular system architecture to serve VUs. Next, we analyze the terrestrial VEC systems performance for VUs data processing problems and propose solutions to improve the performance in terms of latency and energy costs. Next, we extend the scenario toward the joint T-NTN system and address the problem of distributed data processing through ML-based solutions. We also proposed advanced distributed learning frameworks with the support of a joint T-NTN framework with edge computing facilities. In the end, proper conclusive remarks and several future directions are provided for the proposed solutions
Bone biomineralization in osteosarcoma: a multimodal multiscale in/ex vivo study through synchrotron-based X-ray and NMR techniques
Get PDFOsteosarcoma (OS) is a rare and aggressive bone tumor mainly affecting adolescents and young adults. Recent studies suggested that dysfunctions in osteogenic differentiation may contribute to OS genesis and development, leading to a malignant environment that promotes cancer growth and migration. OS clinical diagnosis involves investigating persistent bone pain, swelling, and fractures through radiological imaging and biopsy. In addition, treatment typically involves a multimodal approach combining surgical resection of the tumor and chemotherapy before and after surgery. This thesis aims to provide new insights into osteosarcoma through a comprehensive multiscale characterization of the tumor, exploiting advanced synchrotron-based X-ray and magnetic resonance techniques. SaOS-2 cells were induced to differentiate into osteoblasts and were studied during the early stages of biomineralization. Mineral matrix formation was monitored exploiting synchrotron-based X-ray techniques, suggesting a mechanism based on the interaction between mitochondria and vesicles. OS is characterized by uncontrolled cells proliferation and consequent generation of an abnormal tissue microenvironment that promotes tumor growth and metastasis. Therefore, an extensive structural and morphological characterization of osteosarcoma tissue holds great potential for identifying new targets and therapeutic strategies. Synchrotron-based X-ray techniques were utilized to analyze resected human osteosarcoma tissues, revealing differences in morphology, mineral, and chemical composition compared to normal bone. Currently, invasive biopsy remains the gold standard for identifying bone sarcomas and monitoring their pathological progression. Nuclear magnetic resonance (NMR) techniques at ultra-high field, particularly diffusion-weighted imaging and magnetic resonance spectroscopy, showed promise in characterizing bone sarcomas cellularity and metabolism. In conclusion, thanks to the combination of synchrotron-based and NMR techniques, this work tackles the challenge to bridge the gap between cellular and clinical aspects of osteosarcoma. Moreover, the multimodal approach provides new insights into bone sarcomas, paving the way for the development of improved therapeutic strategies and more precise diagnostic tools
Study of charge, spin, and structural orderings in quantum materials using nuclei and muons as local probes
Get PDFQuantum Materials are many body systems displaying emergent phenomena caused by quantum collective behaviour, such as superconductivity, charge density wave, fractional hall effect, and exotic magnetism. Among quantum materials, two families have recently attracted attention: kagome metals and Kitaev materials.
Kagome metals have a unique crystal structure made up of triangular lattice layers that are used to form the kagome layer. Due to superconductivity, magnetism, and charge ordering states such as the Charge Density Wave (CDW), unexpected physical phenomena such as the massive Anomalous Hall Effect (AHE) and possible Majorana fermions develop in these materials.
Kitaev materials are a type of quantum material with a unique spin model named after Alexei Kitaev. They include fractional fluctuations of Majorana fermions and non-topological abelian anyons, both of which might be used in quantum computing. Furthermore, they provide a realistic framework for the development of quantum spin liquid (QSL), in which quantum fluctuations produce long-range entanglements between electronic states despite the lack of classical magnetic ordering.
In my research, I performed several nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and muon spin spectroscopy (µSR) experiments to explain and unravel novel phases of matter within these unusual families of materials. NMR has been found to be an excellent tool for studying these materials’ local electronic structures and magnetic properties. I could use NMR to determine, for the first time, the structure of a novel kagome superconductor, RbV3Sb5, below the CDW transition, and to highlight the role of chemical doping in the CDW phase of AV3Sb5 superconductors. µSR has been used to investigate the effect of doping on kagome material samples in order to study the presence and behaviour of an anomalous phase developing at low temperatures and possibly related to time-reversal symmetry breaking
Novel biomaterials for regeneration of periapical bone defects in endodontic and implant therapy
Get PDFEndodontic-related periapical bone defects are a common occurrence in the global populations. Considering the number of root canal treatments performed annually, new strategies and new biomaterials for the management of these bone defects will be important and highlight the need for continued research and development in endodontic field.
The present PhD thesis have several objectives and is divided into two main sections: one focused on in vitro and laboratory research and the other on clinical in vivo investigations.
The first part, focused on laboratory and in vitro research, investigated 2 main topics:
• the microbial communities of apical periodontitis to evaluate the predominant bacterial using 16sr DNA-targeted Nanopore sequencing;
• the physical-chemical properties of innovative premixed calcium-silicate based bioceramic sealers for endodontic therapy;
The second part, focused on in vivo clinical studies, investigated 2 main topics:
• the clinical application of premixed calcium-silicate-based sealers. Ethical committee approval was obtained in 2 separate in vivo studies. The first one is a prospective cohort study with a two-year follow-up where the test group was compared with a control group (considered the gold standard). The second is a pilot prospective cohort study with a 12-month follow-up which set the foundation for a subsequent randomized investigation. Thanks to these investigations, we validated a new technique that innovatively associates a warm obturation technique with calcium-silicate-based sealers. Historically, these sealers were only used with cold techniques. This investigation highlights the possibility for wider utilization and improvements in endodontic techniques.
• The outcome of 2 different types of implants characterized by different surface treatments and placed with different techniques. The marginal bone level and periodontal parameters were evaluated with a follow-up of 4 and 10 years.
This Ph.D thesis is based on a compilation of published papers I have done during my three-year PhD program
Establishment of a radiomics laboratory: data mining and quantitative imaging techniques in clinical radiation oncology
Get PDFThis thesis focuses on the field of data mining and radiomics and its application in clinical radiation oncology from cancer diagnosis to therapies.
One of the thesis objective is to establish a "Romagna Imaging Biobank" and apply radiomics to specific oncological pathologies. The goals are to establish a link between tumor phenotype and quantitative image descriptors and personalize anti-cancer therapies.
First the thesis outlines a software platform development and a multicentre study for radiomic tools testing, investigating their reproducibility, sensitivity and stability in terms of features extraction.
We examine the use of imaging biomarkers, both through phantom-based testing and patient-focused studies:
In the first study, software packages compliant with the Image Biomarkers Standardization Initiative (IBSI) were assessed, revealing high standardization in feature implementation. Then we present a multicentre evaluation of dosiomics features, emphasizing their stability and effectiveness in distinguishing dose distributions across various radiation therapy technologies and techniques.
The former investigates the use of MR-based quantitative analysis to differentiate testicular tumors, while the latter assesses the complementary roles of MRI-ADC and [68Ga]Ga-PSMA-11-based quantitative analysis in distinguishing prostate cancer patients of varying risk levels. The last patient-focused study introduces a radiomic signature for the classification of benign lipid-poor adrenal adenomas, with potential applications in reducing unnecessary investigations and enhancing the accuracy of not-enhanced CT scans. A review on radiomic studies for lipid-poor adrenal adenomas is in preparation.
In conclusion, the outlook of the radiomics laboratory is rooted in the ever-evolving field of data-driven medicine. Collaboration with various medical physics associations and research initiatives, including artificial intelligence, promises to drive progress in clinical oncology. The integration of digital image flows within hospitals and the implementation of standardized practices further enhance a comprehensive cancer care network and strengthen the establishment of a “Romagna Imaging Biobank
Off-label use of balloon-expandable transcatheter valves to treat pure aortic regurgitation
Get PDFBackground
Transcatheter aortic valve implantation (TAVI) in pure severe aortic regurgitation (AR) is challenging, as dedicated devices are not widely available. Off-label use of transcatheter heart valves (THVs) approved for the treatment of aortic stenosis has been reported. When balloon-expandable valves (BEV) are preferred, oversizing with respect to the annulus is necessary, but there is scant data regarding optimal oversizing. The study assesses BEV oversizing and outcomes of TAVI with BEV in pure AR.
Methods
Consecutive patients undergoing transfemoral TAVI in pure AR with Sapien BEV at our centre between 2019 and 2023 were included. Bicuspid (BAV) and tricuspid (TAV) aortic valves were analyzed separately. The aim was to implant a valve with 20-30% oversizing with respect to the annulus. TAV were divided into small annulus group (≤618mm2, SA) where ≥20% oversizing is achievable based on published data on BEV overexpansion and larger annulus group (LA, >618mm2). Overexpansion and oversizing were measured on post-procedural CT. Procedural and clinical outcomes were analyzed using the VARC-3 criteria.
Results
Seventeen patients were identified (76.5% males, mean age 79.2 years, STS 3.8%, TAV 13 patients). Mean aortic valvular calcium volume was: TAV=15.4mm3 and BAV=171.0mm3 (p=0.001). Technical success was 94.1% with one valve embolisation in TAV LA group. Mild paravalvular leak (PVL) was more frequent in BAV (p=0.0088). The post-procedural CT in TAV patients showed a mean 28.3% oversizing, significantly higher in SA (31.2%) then in LA group (19.4%), p= 0.0092. Oversizing ≥20% was achieved in 100% SA vs 33.3% LA patients (p=0.046). In LA patients the implanted BEVs were significantly more overexpanded than in SA group (10.8% vs 22.3%, p=0.0119)
In-hospital mortality was 5.9%. There was no difference in 1-year mortality between groups.
Conclusions
TAVI in pure AR with oversized Sapien BEV showed good procedural and short-term outcomes when ≥20% oversizing was predictably achievable
The new frontiers of urban equalisation between soil protection and urban regeneration
No full textLa presente tesi di dottorato si focalizza sull’analisi delle diverse forme di perequazione urbanistica presenti nell’ordinamento giuridico italiano. La ricerca parte dal rapporto conflittuale tra pianificazione del territorio e diritto di costruire, cercando di approfondire la nascita del fenomeno perequativo dall’origine, come rimedio agli effetti discriminanti della zonizzazione, componente fondamentale del piano regolatore generale. La tesi, poi, si concentra sulla figura della compensazione urbanistica, quale soluzione alternativa all’espropriazione per pubblica utilità, e sulla premialità o incentivazione edilizia, dando risalto così alle diverse sfaccettature del fenomeno perequativo. In tale contesto, i diritti edificatori divengono strumento per la soddisfazione di altri interessi pubblici legati al territorio, rispetto allo scambio tra privati (originariamente denominato, come da prassi, “cessione di cubatura”). Infine, nell’ultima parte della tesi ci si sofferma sul fenomeno perequativo nella dimensione attuale, provando a ipotizzare una circolazione sovracomunale dei titoli volumetrici per finalità rigenerative e nell’ottica della limitazione del consumo di nuovo suolo. Si tenta, in sostanza, di valorizzare le forme di perequazione anche in un contesto profondamente mutato, immaginando la gestione dei volumi ad un livello intercomunale ovvero sovracomunale, e includendo la desigillazione come tecnica di valorizzazione al contempo urbanistico-edilizia ed ambientale.This doctoral thesis focuses on the analysis of the different forms of urban equalisation present in the Italian legal system. The research starts from the conflicting relationship between spatial planning and the right to build, attempting to investigate the birth of the equalisation phenomenon from its origin, as a remedy to the discriminating effects of zoning, a fundamental component of the general regulatory plan. The thesis then focuses on the figure of urban compensation, as an alternative solution to expropriation for public utility, and on building bonuses or incentives, thus emphasising the various facets of the equalisation phenomenon. In this context, building rights become a tool for the satisfaction of other public interests linked to the territory, as opposed to the exchange between private parties (originally referred to as "“cessione di cubatura”). Finally, the last part of the thesis focuses on the equalisation phenomenon in its current dimension, trying to hypothesise a supra-municipal circulation of volume titles for regenerative purposes and with a view to limiting the consumption of new land. In essence, an attempt is made to valorise the forms of equalisation even in a profoundly changed context, imagining the management of volumes at an inter-municipal or supra-municipal level, and including desegregation as a technique of valorisation at the same time as urban-planning and environmental development
Online hate speech and intermediary liability in the age of algorithmic moderation
Get PDFThis research aims to investigate the impact of liability-enhancing legal strategies in the context of the governance of online hate speech. Indeed, the increased reliance of the law on the role of private platforms for the purposes of moderating and removing hate speech deeply affects constitutional principles and individual fundamental rights. For instance, the enhancement of intermediary liability and responsibilities can con-tribute to the phenomenon of the over-removal of user content, with little regard to basic constitutional guarantees. Furthermore, research has shown that the ever-increasing use of automated systems for hate speech moderation gives rise to a whole new set of challenges and issues related to the concrete risk of errors and biased results, leading to a disproportionate removal of content produced by minority, vulnerable, or discriminated groups of people. After dealing with the question concerning the ra-tionale(s) of hate speech regulation and arguing for an increased role for the principle of substantive equality in this regard, this work investigates the developing trends con-cerning the imposition of forms of intermediary liability with respect to the spread of hate speech content across the Internet, keeping a close eye on the evolving European framework. In doing so, this work also explores the relationship between platforms’ content moderation practices and the promotion of fundamental rights and values – in-cluding the principle of substantive equality – especially in the light of the ever-increasing use of artificial intelligence systems for the detection and removal of hate speech. In the context of the European Union, it is held that such reflections are of ut-most importance particularly following the adoption of the Digital Services Act. In this respect, the work argues for the need for a renewed code of conduct on hate speech, with a view to further protecting constitutional values and the rights of users