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An international, expert-based, multispecialty Delphi consensus document on stroke risk stratification and the optimal management of patients with asymptomatic and symptomatic carotid stenosis
No full textObjective: The optimal management of patients with asymptomatic carotid stenosis (AsxCS) and symptomatic carotid stenosis (SxCS) is controversial and includes intensive medical management (ie, best medical therapy [BMT]) with or without an additional carotid revascularization procedure (ie, carotid endarterectomy [CEA], transfemoral carotid artery stenting [TFCAS] or transcarotid artery revascularization [TCAR]). The aim of this international, expert-based, multispecialty Delphi consensus document was to reconcile the conflicting views regarding the optimal management of AsxCS and SxCS patients.Methods: A three-round Delphi consensus process was performed including 63 experts from Europe (n = 37) and the United States (n = 26). A total of six different clinical scenarios were identified involving patients with either AsxCS or SxCS. For each scenario, five treatment options were available: (i) BMT alone, (ii) BMT plus CEA, (iii) BMT plus TFCAS, (iv) BMT plus TCAR, and (v) BMT plus CEA/TFCAS/TCAR. Differences in treatment preferences between US and European participants were assessed using Fisher's exact test, and odds ratios were used to quantify the magnitude and direction of association. Consensus was achieved when >70% of the Delphi consensus participants agreed on a therapeutic approach.Results: Most participants concurred that BMT alone is not adequate for the management of a 70-year-old fit male or female patient with 80% to 99% AsxCS (52/63 [82.5%] and 45/63 [71.5%], respectively). In contrast, most panelists would opt for BMT alone for an 80-year-old male AsxCS patient with several comorbidities (48/63 [76.2%]). The majority of participants would opt for BMT plus a carotid revascularization procedure for an 80-year-old male SxCS patient with a recent ipsilateral cerebrovascular event, an ipsilateral 70% to 99% SxCS, and a 5-year predicted risk of ipsilateral ischemic event of 10% (54/63 [85.7%]), 15% (59/63 [93.6%]), or 20% (63/63 [100%]). The opinion of US-based participants varied from that of Europe-based respondents in some scenarios.Conclusions: The panel agreed that BMT alone is insufficient for most patients with SxCS, and that select subgroups of AsxCS patients may also benefit from revascularization, especially when high-risk features are present. Patients should be stratified according to their predicted stroke risk, as well as their individual clinical, anatomical, and imaging features and should be treated accordingly.</p
Health, space & place:a geographical perspective on pandemic preparedness
No full textThis thesis investigates how a geographical perspective enhances our ability to understand infectious disease dynamics and strengthens the broader agenda of pandemic preparedness. Using an interdisciplinary approach, the thesis demonstrates that maps and spatio-temporal analyses are indispensable tools for anticipating, monitoring, and managing infectious disease outbreaks. The four studies collected here explore modern analytic uses of mobility and climatic data, develop methodological frameworks for mapping space–time processes, and examine historical examples where mapped metaphors influenced the creation of epidemic knowledge. Together, they show that a geographical perspective provides pivotal contributions to the analysis, interpretations and communication of infectious disease outbreaks, making it a crucial factor in pandemic preparedness
Coronary calcium scoring on contrast-enhanced spectral coronary computed tomography angiography using a calcium-specific algorithm
No full textBACKGROUND: Coronary artery calcium (CAC) scoring requires a non-contrast scan in addition to contrast-enhanced coronary CT angiography (CCTA), increasing radiation dose and scan time. Virtual non contrast (VNC) methods from spectral CT may obviate the CAC CT scan, but available methods underestimate CAC scores and show low detectability. Although VNC-based CAC scoring is feasible via conversion factors, it misses low-density calcifications, requiring improved VNC methods.PURPOSE: This study evaluates a self-developed CAC-preserving VNC (TrueCa) method to improve detectability and quantification of CAC on CCTA.METHODS: An artificial hollow coronary artery containing five cylindrical calcifications of varying density calcium hydroxyapatite (75-800 mg/cc) was filled with 0%, 50%, 100% (400 Hounsfield units) and 150% of a clinical iodine concentration. The phantom was scanned on dual-layer spectral CT with a CAC scoring and CCTA protocol with five repetitions. CAC CT reconstruction followed Agatston protocol. CCTA scans were reconstructed at thick (3 mm) and thin (0.67 mm) slices using (1) commercially available VNC and (2) self-developed TrueCa algorithm, generated via linear separation of spectral data. Non-overlapping 95% confidence intervals between Agatston scores (AS) from the CAC protocol and CCTA protocol indicated significant differences. Volume scores (VS) were compared to physical calcification volume.RESULTS: For AS, thick-slice VNC CCTA underestimated AS by 30%-65% across all CAC densities, failing to detect CAC below 400 mg/cc. TrueCa CCTA detected all calcifications without significant difference with CAC CT for all CAC densities. Thin-slice compared to thick-slice TrueCa significantly increased AS in low-density CAC. For VS, TrueCa CCTA showed less underestimation than VNC CCTA across all densities except for highest-density calcifications. VS accuracy improved by up to 40% using TrueCa over VNC in medium to lowest-density calcifications.CONCLUSION: In this phantom study, TrueCa CCTA demonstrated superior performance in calcium detection and quantification across most CAC densities, showing potential as a reliable alternative to CAC CT.</p
Transitioning to a 100% Renewable Power Grid:Key Challenges and Opportunities
No full textLimiting global warming to below 1.5°C necessitates a global shift toward renewable energy sources (RESs). However, transitioning to a fully RES-based power system presents challenges related to technical feasibility, socio-political implications, economic factors, and geographical differences. This study examines the feasibility of such a transition from multiple dimensions, including the technical integration and stability of RES technologies, social acceptance, political landscape (policy design and regulatory frameworks), and geographical factors such as resource availability and regional demand. A systematic literature review, combined with a case study of the Integrated Nordic Power System (INPS), provides insights into these challenges. INPS is selected for its complexity and its representation of a large-scale, multi-country power system. The findings highlight the key role of region-specific strategies, stakeholder engagement, and strong policy and regulatory support in enabling successful renewable energy transitions. The INPS case study demonstrates how regional cooperation can help address geographical and political disparities, offering valuable lessons for global applications. Despite the challenges, transitioning to a fully RES-based power system presents significant benefits, including environmental sustainability, socioeconomic development, and long-term cost reductions. Achieving this transition requires substantial investment, technological advancements, strategic management, and global collaboration, highlighting the necessity of long-term political commitment and stakeholder consensus.</p
Influence of MWCNTs Length on the Ferroelectric and Piezoelectric Properties of PVDF-TrFE Composite Films
No full textMulti-walled carbon nanotubes (MWCNTs) were employed as third-phase conductive fillers to explore their structural influence on the ferroelectric and piezoelectric characteristics of composite films. Departing from traditional physical mixing, this work adopted chemical vcapor deposition for the insitu growth of MWCNTs on BaTiO3 surfaces, enhancing their electrical coupling. BaTiO3 with different length of MWCNTs were incorporated into the PVDF-TrFE matrix, followed by complete characterization and performance testing. The findings reveal that short MWCNTs at a 5 wt\% concentration improve the ferroelectric properties of composite films, boosting remnant polarization Pr by 131% and lowering the coercive field Ec from 685 kV/cm to 585 kV/cm, better meeting application's requirements such as those of F-RAM devices. The piezoelectric performance is improved, with the piezoelectric coefficient d33 increasing by 62%, leading to higher output and sensitivity in piezoelectric sensors. In contrast, incorporating the same amount of longer MWCNTs creates a conductive network within the matrix, transforming the film into a conductive system unsuitable for ferroelectric and piezoelectric applications. Therefore, short MWCNTs at the right concentration are more effective in improving performance, although minor agglomeration still persists. Refining processing parameters to optimize MWCNTs length and dispersion could lead to further advancements in performance.</p