Recent Submissions
Non-invasive bone registration resorting to ultrasound for surgical navigation
( 2026 ) Silva, Francisca Fernandes; Santos, Cristina; Momi, Elena de
Orthopaedic procedures are vital for alleviating chronic pain and restoring mobility, significantly improving
patients’ quality of life, but demand extreme surgical precision, as there is a narrow margin for
error, and depend heavily on the surgeon’s experience. Computer-assisted orthopaedic surgery (CAOS)
systems have emerged as an important support tool for surgeons, facilitating planning and intraoperative
navigation to achieve better clinical outcomes. Yet, registration, the critical process of aligning virtual
models with the patient’s anatomy during surgical navigation, remains a major clinical bottleneck. This
process is predominantly invasive, requiring bone markers that, while accurate, cause additional surgical
trauma and increase the risk of postoperative infections.
To address these clinical limitations, this dissertation proposes a non-invasive, ultrasound based bone
registration framework for intraoperative surgical navigation. The computational pipeline seamlessly integrates
artificial intelligence with spatial tracking, utilising advanced deep learning architectures, trained
on an expertly annotated human US dataset, for the automatic segmentation of bone surfaces. To operationalise
the system, custom software modules were developed to manage real-time communication,
execute dynamic three-dimensional reconstructions, and perform the registration of the models.
Validation studies of the system have highlighted its intraoperative feasibility in real-world conditions.
The iterative closest point algorithm demonstrated superiority over the coherent point drift method, achieving
a target registration error of 1.46 mm, within the clinical margin of 1.5 mm, in 87 s. Ultimately, this
thesis establishes a highly accurate, non-invasive CAOS system, paving the way for future advances in
real-time non-invasive bone tracking and in vivo human validation.
Exploring police officers’ narratives about racism in Portugal
( 2026 ) Neiva, Laura
This article examines how police officers in Portugal narrate racism in relation to policing practices, victim descriptions, police databases, and Big Data technologies. Drawing on 34 interviews with members of the Public Security Police (PSP) and the Judiciary Police (PJ), the analysis identifies three interconnected empirical themes: the concentration of policing resources in racialised neighbourhoods; the use of racial identifiers in victim descriptions; and the perceived neutrality of police databases and algorithmic systems. The article argues that officers’ narratives may contribute to the reproduction of institutional racism by presenting racialised outcomes as spatially necessary, procedurally neutral, or technologically objective. Critical Race Theory provides the overarching framework for examining how racial power may be reproduced through formally neutral practices, while policing studies situate these processes within professional cultures and institutional routines. Durrheim et al.’s framework is used as a secondary interpretative resource to identify how racism is split, displaced, de-racialised, relativised, or trivialised. The findings show how apparently minor and disconnected practices may interact to reinforce racial disproportionality while preserving an institutional self-image of impartiality. By bringing CRT into dialogue with policing studies and critical research on technology, the article contributes to understanding the subtle mechanisms through which institutional racism may be reproduced in Portuguese and European policing contexts.
Pre-dissolution activation of glass powder: ionic release mechanisms and their limited impact on mortar performance
( 2026 ) Jesus, Carlos Manuel Gonçalves; Fernandes, Élia; Reis, Rui; Couto, Rúben; Ribeiro, Manuel; Puga, Hélder; Camões, Aires; Malheiro, Raphaele Lira Meireles Castro
This study evaluates the influence of different pre-dissolution methods on the ionic release behavior of glass powder (GP) and the mechanical and microstructural performance of mortars incorporating 25% volumetric cement replacement. Green bottle glass waste was milled and fractionated, and the GP25 fraction—whose particle size is comparable to cement and fly ash—was selected. The powder was immersed in water for 6 h under six conditions: static resting, orbital agitation, magnetic stirring, mechanical stirring, ultrasonic bath, and ultrasonic probe. The release of Naþ and Ca2þ ions was quantified prior to mortar production. Ultrasonic treatments promoted the highest ionic dissolution but also increased porosity and slightly reduced strength. In contrast, conventional agitation methods produced moderate ion release and more balanced microstructures. Complementary analyses (TGA, electrical resistivity, capillary absorption, chloride migration and mercury intrusion porosimetry) showed that increased ionic release does not necessarily translate into improved hydration, strength or durability of GP-modified mortars.