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Clogging of Noncohesive Suspension Flows
Get PDFWhen flowing through narrow channels or constrictions, many-body systems exhibit various flowing patterns, yet they can also get stuck. In many of these systems, the flowing elements remain as individuals (they do not aggregate or merge), sharing strong analogies among each other. This is the case for systems as contrasting as grains in a silo and pedestrians passing through tight spaces. Interestingly, when these entities flow within a fluid medium, numerous similarities persist. However, the fluid dynamics aspects of such clogging events, such as interstitial flow, liquid pressure, and hydrodynamic interactions, has only recently begun to be explored. In this review, we describe parallels with dry granular clogging and extensively analyze phenomena emerging when particles coexist with fluid in the system. We discuss the influence of diverse flow drive, particle propulsion mechanisms, and particle characteristics, and we conclude with examples from nature
Patient perspectives on the use of artificial intelligence in prostate cancer diagnosis on MRI
Get PDFObjectives: This study investigated patients’ acceptance of artificial intelligence (AI) for diagnosing prostate cancer (PCa) on MRI scans and the factors influencing their trust in AI diagnoses.Materials and methods: A prospective, multicenter study was conducted between January and November 2023. Patients undergoing prostate MRI were surveyed about their opinions on hypothetical AI assessment of their MRI scans. The questionnaire included nine items: four on hypothetical scenarios of combinations between AI and the radiologist, two on trust in the diagnosis, and three on accountability for misdiagnosis. Relationships between the items and independent variables were assessed using multivariate analysis.Results: A total of 212 PCa suspicious patients undergoing prostate MRI were included. The majority preferred AI involvement in their PCa diagnosis alongside a radiologist, with 91% agreeing with AI as the primary reader and 79% as the secondary reader. If AI has a high certainty diagnosis, 15% of the respondents would accept it as the sole decision-maker. Autonomous AI outperforming radiologists would be accepted by 52%. Higher educated persons tended to accept AI when it would outperform radiologists (p < 0.05). The respondents indicated that the hospital (76%), radiologist (70%), and program developer (55%) should be held accountable for misdiagnosis.Conclusions: Patients favor AI involvement alongside radiologists in PCa diagnosis. Trust in AI diagnosis depends on the patient’s education level and the AI performance, with autonomous AI acceptance by a small majority on the condition that AI outperforms a radiologist. Respondents held the hospital, radiologist, and program developers accountable for misdiagnosis in descending order of accountability.Clinical relevance statement: Patients show a high level of acceptance for AI-assisted prostate cancer diagnosis on MRI, either alongside radiologists or fully autonomous, particularly if it demonstrates superior performance to radiologists alone. Key Points: Prostate cancer suspicious patients may accept autonomous AI based on performance. Patients prefer AI involvement alongside a radiologist in diagnosing prostate cancer. Patients indicate accountability for AI should be shared among multiple stakeholders.</p
Mitigation of Motion Artifacts in Handheld Laser Speckle Contrast Imaging Illustrated on Psoriasis Lesions
Get PDFBackground: Handheld laser speckle contrast imaging (LSCI) is crucial in clinical settings, but motion artifacts (MA) can compromise perfusion image reliability. Current prevention and suppression methods are often impractical or complex. Machine vision techniques, promising in medical imaging, could improve signal quality, but their use in suppressing MA is still unexplored. Objective: We propose an innovative method based on linear regression for MA correction (MAC) in LSCI and validate it in vivo. Methods: We performed paired handheld and mounted LSCI measurements on 14 subjects with psoriasis using the previously validated handheld perfusion imager (HAPI). By marking lesion boundaries for clinical purposes, the HAPI used a monochromatic camera for both speckle imaging and motion detection, simplifying hardware requirements. Accurate estimation of relative displacements between the test object and LSCI probe allowed us to apply MAC to the perfusion images. Results: Local perfusion values correlated with applied speed were used to calculate and correct MA. The difference between mean perfusion in handheld and mounted modes after MAC significantly decreased (median error 14.2 perfusion units (p.u.) on lesions before correction (p< 0.0005) and 0.5 p.u. after correction (p=0.2)). Conclusion: The findings provide evidence for robust handheld LSCI and validate the MA technique in psoriasis case. Of the two causes of MA-on-surface speeds and wavefront tilt-we address the former and correct mean perfusion, assuming constant temporal perfusion at each location. Significance: We describe a practical, non-contact, marker-free technique for reliable handheld perfusion imaging, supporting further clinical translation in plastic surgery and burns.</p
A research agenda for GIScience in a time of disruptions
Get PDFSocial issues, AI, and climate change are just a few of the disruptive focuses impacting science. The field of GIScience is well positioned to respond to accelerating disruptions due to the interdisciplinary nature of the field and the ability of GIScience approaches to be used in support of decision-making. This manuscript aims to start a conversation that will establish a research agenda for GIScience in an age of disruptions. We outline three guiding principles: (1) focusing on the relevance and real-world impact of research, (2) adopting systems-based thinking and contextual approaches and (3) emphasizing inclusive practices. We then outline prioritized research areas organized by what topics are important focal areas (Data and Infrastructure, Artificial Intelligence, and Causality and Generalizability), and what approaches to science we should be attentive to (Impactful Open Science, Collaborative and Convergent Science, and through Diverse Participation and Partnerships). We conclude with a call to increase impact by balancing slow science with practical and policy-oriented research. We also recognize that while broad adoption of spatial approaches is a signal of GIScience’s success, we should continue to work together to advance core knowledge centered on spatial thinking and approaches
Competencies in interdisciplinary engineering education:Constructing perspectives on interdisciplinarity in a Q-sort study
Get PDFInterdisciplinary engineering education (IEE) is gaining traction as engineering practices increasingly acknowledge the need to transcend traditional boundaries given the complexities of globalised systems. IEE, however, faces challenges that underscore uncertainties and different perceptions about what interdisciplinarity means for engineering education, what it requires, and how current educational practices should change accordingly. This study addresses these concerns by taking competencies as indicators. Analysing new angles interdisciplinary approaches bring to traditional engineering competencies, we first propose six IEE-related competency categories. We then use the Q-sort methodology to investigate how interdisciplinarity is envisioned within overall engineering educational goals. Findings highlight three distinct perspectives, seeing IEE respectively as social-holistic, technical problem-solving, and reflective pragmatic. Each perspective embodies specific values and conceptions about the role and implications of interdisciplinarity for engineering education. The multifaceted understandings of and approaches to realise IEE suggest the need for nuanced strategies and continuous dialogues in education
On two open problems on the normality of bent functions
Get PDFNon-normal Boolean bent functions are one of the least understood classes of bent functions, and only a few difficult-to-find examples of such functions are known. In this paper, we consider the following two open problems on the normality of bent functions: 1. Do non-normal bent functions in 8 variables and degree 4 exist? 2. Do non-normal bent functions in the PS−∖PSap class exist? We solve both of these problems by finding among the known PS bent functions in n=8 variables a non-normal bent function in the PS−∖PSap class.</p
The League System, Competitive Balance, and the Future of European Football
Get PDFResearch question: Which combination of league system and competitive balance in European men’s club football maximises welfare, and which policies can improve the combination?Research methods: Qualitative analysis is applied that uses the sport economics literature and other sources. An encompassing number of factors, insights and empirical results are considered to analyse systematically the options to reform European professional football.Results and findings: In the present league system, competitive balance is decreasing which reduces welfare. In a system with a Super League, competitive balance can be higher. The last system also has other advantages, as well as disadvantages, in relation to issues such as the quality of play, the role of star players, chances to lift important trophies, regional and national sentiments and rivalries, and sporting meritocracy. After discussing these issues, it is concluded that a Super League system may improve future welfare. If, however, the present system regains a higher level of competitive balance, it may well generate a higher welfare level than a Super League. Two measures for improving competitive balance are a more equal distribution of broadcasting revenues and a progressive luxury tax.Practical implications: At present, the measures above may seem to be infeasible. However, this can change if the competition authorities accept our interpretation of EU competition law and act accordingly. More generally, the government should become better aware of its potential to improve welfare in the football sector.Research contribution: The paper provides a systematic analysis of the welfare effects of different options to reform Europe’s professional men football. Because of its broad approach it sheds new light on pressing issues and it provides insights for policymaking
State Power and Capital in the Climate Crisis:A Theory of Fossil Imperialism
Get PDFImperialism has long been used as a category to highlight and theorize the connections between capital accumulation and the exogenous use of state power on its behalf. Against the backdrop of an escalating climate crisis, the connections between imperialism and fossil capitalism have recently come under increased scrutiny. Several authors and activists have used the term fossil imperialism to refer to this nexus. Building on their interventions, this chapter theorizes fossil imperialism as a distinct mode of imperial domination. We argue that under fossil capitalism, a central task for imperial states is to ensure and control the flow of cheap fossil energy in the interest of their respective fossil economies. We identify and explore five mechanisms of control by which imperial states facilitate this process: (1) colonization; (2) projection of military power; (3) suppression of anti-extractivist movements; (4) economic warfare; and (5) domination of the global (financial and political) institutions that regulate the trade and distribution of fossil fuels. Finally, we offer some reflections on the possibility of a non-fossil anti-imperialism
Dark Web Dialogues:Analyzing Communication Platform Choices of Underground Forum Users
Get PDFWe investigate the utilization of private communication platforms by underground forum users. We aim to bridge the knowledge gap regarding user preferences for communication platforms employed for private conversations within illicit contexts. We employ social network analysis, topic modeling and statistical analysis on over 7.5 million posts and 260 thousand messages from a popular underground forum. We identify prevalent communication platforms and investigate the relationship between the context in which users share contact details and their social networks in relation to platform preferences. Our contributions include an overview of prominent communication platforms used by forum users, highlighting Telegram's predominant popularity. We show that in hacking related contexts users choose platforms that provide higher security and privacy levels. Lastly, findings from our statistical model indicate a significant relationship between the centrality of users in the social network and their choice of communication platform. We provide valuable insights for law enforcement agencies, helping them make strategic decisions and plan interventions combating cybercrime
Should PLS become factor-based or should CB-SEM become composite-based? Both!
Get PDFThis paper critically discusses a recent EJIS paper entitled “Will PLS have to become factor-based to survive and thrive?”, which laments that covariance-based structural equation modelling cannot handle composite models, postulates that PLS should become factor-based, and advocates the use of the PLSF-SEM method. We clarify that covariance-based structural equation modelling can handle composite models, e.g. using the so-called Henseler – Ogasawara specification, agree that PLS in its original form cannot consistently estimate the parameters of reflective measurement models, and reiterate that consistent PLS is a viable means to overcome this limitation. Finally, we study the performance of PLSF-SEM through scenario analyses. Based on our results, we conclude that PLSF-SEM is inferior to covariance-based structural equation modelling and consistent PLS in almost all respects. Therefore, we cannot currently recommend the use of PLSF-SEM, and it is up to future research to demonstrate potential advantages over existing structural equation modelling techniques