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MLFusion: Multilevel Data Fusion using CNNS for atrial fibrillation detection
Get PDFData fusion, involving the simultaneous integration of signals from multiple sensors, is an emerging field that facilitates more accurate inferences in instrumentation applications. This paper presents a novel fusion methodology for multi-sensor multimodal data using convolutional neural networks (CNNs), which introduces a data-driven approach to automatically select the optimal level of information abstraction for fusion. Unlike traditional methods, the proposed model allows for a self-learning fusion process, eliminating the need for manual selection of the fusion level by the designer. The model uniquely integrates feature extraction and fusion into a unified framework, enhancing efficiency and performance. Additionally, the fusion network incorporates signal quality indicators (SQIs) as input streams, enabling the model to account for the quality of each input signal during the fusion process. The methodology is evaluated on the task of atrial fibrillation detection through the fusion of two multimodal signal inputs taken from a portion of the MIMIC III database. The fusion network, using electrocardiogram (ECG) and photoplethsymogram (PPG) signals as inputs, and trained with an average loss function, achieved an accuracy of 99.33% and a sensitivity of 99.74%. The model’s robustness in the presence of noisy inputs is also analyzed, demonstrating the effectiveness of the SQI-based multi-level fusion approach. This novel methodology represents a significant advancement in data fusion by offering a fully automated, quality-aware approach to multi-sensor multimodal signal fusion
In Vitro Investigation of Microcatheter Behavior During Microsphere Injection in Transarterial Radioembolization
Get PDFPurpose: To experimentally investigate the behavior of a clinically used microcatheter during transarterial radioembolization (TARE) microsphere injection in a successively bifurcating in vitro model. Materials and Methods: A symmetrical phantom was developed which bifurcated 3 times into 8 outlets. A blood-mimicking fluid was pumped through the phantom using a physiological representative waveform. Holmium-165 microspheres were injected in a pulsed manner at 3 different locations using a standard microcatheter and a rigid counterpart with same dimensions as a control. Motion of the catheter was studied with a top- and side-view camera on the phantom. Microspheres were collected at each outlet and their distribution over the 8 outlets was analyzed. Results: Due to the pulsatile flow in the phantom, strengthened by the pulsatile microsphere injection, the clinical catheter showed maximum displacements of 0.87 mm within a vessel with a diameter of 3.6 mm. This motion resulted in a different microsphere distribution for the clinical catheter compared with the rigid counterpart (75.9% vs 49.4% of the microspheres went to outlet 1–4, respectively). Conclusion: In this in vitro model, the motion of the clinical catheter affected distribution of microspheres. Since the pulsatile administration of microspheres resulted in increased motion of the clinical catheter, standardizing microsphere administration could be beneficial to reduce interprocedural differences in TARE. Clinical Impact: Our study demonstrated that microsphere distribution during transarterial radioembolization (TARE) is affected by catheter motion. Furthermore, increased catheter motion was observed as a result of the injection profile. Predictive tools such as the contrast CBCT and scout dose use different injection profiles compared to therapeutic TARE injections, potentially altering catheter tip behaviour and microsphere distribution, which could compromise their predictive values. Additionally, current TARE microsphere injection guidelines provide limited details, which may lead to variability across institutes and interventional radiologists. Standardizing injection techniques could reduce catheter motion variability and may facilitate more consistent and predictable microsphere distribution patterns.</p
Spontaneous Emission of Precisely Positioned Quantum Dots in 3D Silicon Photonic Band Gap Crystals
Get PDFIt is well known from quantum mechanics that the control of photonic band gap crystals over the spontaneous emission of embedded quantum emitters - such as semiconductor nanocrystal quantum dots - depends sensitively on where the emitters are located. Therefore, it is an outstanding challenge to derive methods to precisely position emitters inside photonic crystal nanostructures. This thesis takes on this challenge by the use of modern chemical methodologies: we study how to position quantum dots inside photonic band gap crystals with polymer brushes. Therefore, we investigated a suitable surface chemistry via silane monolayer formation, polymer brushes, and the covalent attachment of lead sulfide quantum dots with a suitable organic ligand. The knowledge we initially obtained from flat silicon substrates was used as input to derive advanced methods for complex 2D and 3D silicon photonic crystal nanostructures. We have shown that the polymer must be judiciously chosen in order to control the layer thickness of the grafted polymer brushes on silicon. By choosing poly(N-isopropylacrylamide) layers, we achieved a precise control over the layer thickness by varying the activating and de-activating catalyst species. For poly(glycidyl methacrylate) (PGMA) we were able to control the polymer layer thickness by the polymerization time. Since the grafting of poly(glycidyl methacrylate) brushes was more reliable, we decided to proceed with the epoxide-containing polymer. In order to precisely position the quantum dots within the pores of 3D silicon photonic crystals, it was necessary to develop a sophisticated surface chemistry strategy. Since we made the choice for PGMA layers, a suitable organic ligand on the lead sulfide (PbS) quantum dots was important. We reacted the epoxide side chains of PGMA with amine-PEGylated lead sulfide quantum dots. By varying the coupling conditions, we achieved densely packed quantum dots attached to PGMA brushes.Near-infrared emitting quantum dots were studied in this thesis because their emitted photons are not absorbed by the silicon backbone of our 3D photonic band gap crystals. We chose lead sulfide quantum dots for our studies because they are commercially available with various organic ligands. Quantum dot suspensions were studied to measure spectra and time-resolved emission rates of the nanocrystals. We successfully interpreted the decay rates of the lead sulfide quantum dot suspensions with a model for an ideal two-level exciton, as well as an adapted model.In order to apply the acquired surface chemistry, we had to ensure that the silicon photonic crystals have very clean silicon-air surfaces after the fabrication. Therefore, we had to overcome the problem that after the fabrication of our silicon photonic crystals, fluorocarbon residues are present on the pore walls of the crystals. These contaminations had to be removed by several harsh cleaning steps. Our cleaning procedure, consisting of RCA-2 cleaning and an oxidation step at 800 °C in a furnace, resulted in ultra-clean silicon photonic crystal samples that could be used for the functionalization with quantum dots by means of elaborate surface chemistry.One highlight of this thesis consists of the experimental observations of quantum dots inside 3D photonic band gap crystals made at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The silicon photonic crystals were analyzed by X-ray tomography to determine the electron density. We were able to analyze the chemical composition of our crystals using X-ray fluorescence tomography. To the best of our knowledge, our study is the first to obtain experimental data on silicon nanostructures doped with quantum dots whose positions were controlled by polymer brushes. We present the strengths and advantages of X-ray fluorescence tomography compared to other techniques. After a detailed analysis of the acquired data, insights into the quantum dot coverage inside the pores of the photonic crystals were obtained. In addition, we were able to characterize the distinctive bromine atoms of the ATRP initiator molecules and the chlorine atoms of the polymer brushes.The “pièce de résistance” of the thesis consists of optical measurements on our best samples, which were studied by X-ray imaging. The silicon photonic crystal samples were studied in terms of spectra and time-resolved emission of the embedded PbS quantum dots. We observed a record of strongly inhibited emission power in the range of the 3D photonic band gap, in agreement with theory. The successful results were reproduced by emission measurements on different 3D photonic crystals. The decay rates of quantum dots positioned in photonic crystals were lower than those of dots positioned on a flat polymer layer outside the crystal on flat silicon. Compared to suspensions, the decay rates were very fast and we estimate very low quantum efficiencies of the dots positioned in the photonic crystals. Our results open up new avenues for functionalizing the sample architecture to create novel types of organic solar cells with high efficiencies.<br/
Integrative Approaches to Interconnected Environmental Challenges:How Institutional Factors Influence Cross-Sector Integration in Dutch Rural Areas
Get PDFEnvironmental challenges are increasingly often interconnected. Yet, they are commonly addressed separately, which might result in inefficiencies and missed opportunities. While it is widely acknowledged that integrative solutions can bring co-benefits and synergetic outcomes for different sectors, empirical studies that systematically explore cross-sector integration at the operational level are rare. Drawing from two case studies with a high potential for reducing the environmental impacts of energy production and agriculture while restoring nature in the Dutch rural context, this exploratory study aims to provide an improved understanding of the institutional factors that influence the fulfillment of integrative potential in rural areas. To understand how institutional factors influence integrative outcomes, we use the operational level rules that guide actions and interactions among the actors of the Institutional Analysis and Development (IAD) framework. Our analysis shows that the potential of integrative solutions is not fully recognized and realized in Dutch rural areas. Key institutional factors that hamper integration are diverging perceptions of desired outcomes (scope rule), exclusion of important actors from decision-making (position rule), and imbalances in the sharing of costs and benefits (payoff rule). We conclude that agreement on the rules of actions and interactions between the actors is necessary for fulfillment of integrative potential
From SOFT approach to SWOT analysis, a historical reconstruction
Get PDFPurpose: The purpose of this study is to revisit the conventional wisdom about a key contribution [i.e. strengths, weaknesses, opportunities, threats (SWOT) analysis] in the field of strategic management. The societal context and the role of academics, consultants and executives is taken into account in the emergence of SWOT analysis during the 1960–1980 period as a pivotal development within the broader context of the satisfactory, opportunities, faults, threats (SOFT) approach. The authors report on both the content and the approach, so that other scholars seeking to invigorate indigenous theories and/or underreported strategy practices will thrive. Design/methodology/approach: Applying a historiographic approach, the authors introduce an evidence-based methodology for interpreting historical sources. This methodology incorporates source criticism, triangulation and hermeneutical interpretation, drawing upon insights from robust evidence through three iterative stages. Findings: The underreporting of the SOFT approach/SWOT analysis can be attributed to several factors, including strategy tools being integrated into planning frameworks rather than being published as standalone materials; restricted circulation of crucial long-range planning service/theory and practice of planning reports due to copyright limitations; restricted access to the Stanford Research Institute Planning Library in California; and the enduring popularity of SOFT and SWOT variations, driven in part by their memorable acronyms. Originality: In the spirit of a renaissance in strategic planning research, the authors unveil novel theoretical and social connections in the emergence of SWOT analysis by combining evidence from both theory and practice and delving into previously unexplored areas. Research implications: Caution is advised for scholars who examine the discrete time frame of 1960–1980 through mere bibliometric techniques. This study underscores the risks associated with gathering incomplete and/or inaccurate data, emphasizing the importance of triangulating evidence beyond scholarly databases. The paradigm shift of strategic management research due to the advent of large language models poses new challenges and the risk of conserving and perpetuating academic urban legends, myths and lies if training data is not adequately curated.</p
Measuring and implementing lexical alignment:A systematic literature review
Get PDFLexical Alignment is a phenomenon often found in human–human conversations, where the interlocutors converge during a conversation to use the same terms and phrases for the same underlying concepts. Alignment (linguistic) is a mechanism used by humans for better communication between interlocutors at various levels of linguistic knowledge and features, and one of them is lexical. The existing literature suggests that alignment has a significant role in communication between humans, and is also beneficial in human–agent communication. Various methods have been proposed in the past to measure lexical alignment in human–human conversations, and also to implement them in conversational agents. In this research, we carry out an analysis of the existing methods to measure lexical alignment and also dissect methods to implement it in a conversational agent for personalizing human–agent interactions. We propose a new set of criteria that such methods should meet and discuss the possible improvements that can be made to existing methods
In‐line spectroscopy for iodine quantification in dynamic contrast‐enhanced dedicated breast CT
Get PDFIn 4D dynamic contrast‐enhanced dedicated breast computed tomography (4D DCE‐bCT), the functional properties of the breast will be characterized by monitoring the uptake and washout of iodine‐based contrast agents over time. This information could be valuable in breast cancer treatment. However, prior to clinical implementation, it is crucial to validate the quantitative estimates of iodine concentrations at each time point during acquisition.Purpose<jats:p/>To develop an in‐line spectroscopy system capable of measuring iodine concentrations in a dynamic x‐ray breast phantom in real‐time.Methods<jats:p/>Potassium iodide served as the contrast agent. The system was set‐up at both the entrance and exit of the phantom. It comprises a fiber‐coupled green LED and collimator, which together ensure that a parallel beam passes through the sample holder. Transmitted light is captured by a collimator on the opposite side and directed through a fiber optic cable to a photodetector for intensity measurement. The relationship between 13 iodine concentrations (0–6 mg I/mL) and light transmission was tested, and the system's repeatability and accuracy were determined.Results<jats:p/>The system exhibited a strong correlation between iodine concentration and transmission values, achieving a root‐mean‐square error of 0.007. The repeated measurements had relative standard deviations of 0.04% and 0.1% for repeated water measurements at the phantom's entrance and exit, respectively. Furthermore, the accuracy measurements gave a mean error of fitting of 0.008 (± 0.07) mg I/mL.Conclusion<jats:p/>The in‐line spectroscopy system can effectively monitor iodine concentrations in a dynamic breast phantom, providing a reliable method for quantitative validation of 4D DCE‐bCT
Non-collinear wave mixing to determine physical ageing in PVC pipelines
Get PDFThe ultrasonic signal amplitudes obtained from non-collinear wave mixing has previously shown significant changes for physically aged Poly-Vinyl Chloride (PVC) pipes, demonstrating the method's effectiveness in assessing the ageing condition of PVC. However, the exact relationship between the measured amplitudes and the extent of physical ageing in PVC has yet to be established. Additionally, it has not yet been validated against established methods or applied to determine the service lifetime of PVC pipes. This study outlines a three-step process to validate the effectiveness of the non-collinear wave mixing technique for assessing the physical ageing of PVC pipelines. Firstly, the non-collinear wave mixing results are compared with the established laboratory method of differential scanning calorimetry, to validate the scattered wave amplitude measurements. Secondly, employing the Arrhenius relation, service lifetime estimates derived from non-collinear wave mixing results align within the expected magnitudes, emphasizing the technique's potential for in-situ pipeline inspections. Finally, a material model is utilized to estimate the Third Order Elastic Coefficient (TOEC) based on the measured amplitudes, demonstrating a linear correlation with annealing time. A 50% change in TOEC signifies a brittle state, indicating a high risk of failure. A combination of experimental and analytical analyses highlighted TOEC variations as the primary factor influencing non-collinear wave mixing amplitude changes during physical ageing. This comprehensive approach also highlights the importance of incorporating diverse factors to precisely forecast and oversee the performance of PVC pipes in real-world environments
The D*Phase-study: Comparing short-term psychodynamic psychotherapy and cognitive behavioural therapy for major depressive disorder in a randomised controlled non-inferiority trial
No full textBackground: Given both the large volume and manifold preferences of patients with depression, the availability of various effective treatments is important. Psychodynamic psychotherapy (PDT) has received less research in comparison to cognitive behavioural therapy (CBT) for major depressive disorder (MDD). This study aimed to establish whether short-term psychodynamic supportive psychotherapy (SPSP) is non-inferior to CBT in the treatment of MDD. Methods: A non-inferiority trial was conducted in a Dutch mental health setting, with 290 patients randomised to receive 16 sessions of either CBT or SPSP, over eight weeks. Primary outcome was depressive symptom severity assessed using the self-rated Inventory of Depressive Symptomatology (IDS-SR). The non-inferiority margin was prespecified as a − 5 post-treatment difference on the IDS-SR. Secondary outcome measures were functional impairment caused by symptoms assessed using the Sheehan disability scale (SDS), and wellbeing measured by the Mental Health Continuum-Short Form (MHC-SF). Results: Both intention-to-treat (baseline-adjusted mean difference 1.62, 95 % CI -1.82 to 5.05) and per-protocol analyses (mean difference 2.54; 95 % CI -0.63 to 5.72) showed SPSP to be non-inferior to CBT in reducing depressive symptoms. SPSP showed slightly but significantly higher remission rates and wellbeing scores. Limitations: Patients opting for other therapies or medication did not take part in the trial. Follow-up measures or clinician-rated questionnaires were not included. Conclusions: The findings support SPSP as a viable treatment option for MDD, expanding the available choices for patients and broadening treatment options.</p
Stakeholder perspectives on fostering the water-energy-food nexus in Jordan:Lessons beyond agricultural water management
Get PDFThe water–energy–food (WEF) nexus is an integrated conceptual tool for achieving sustainable development especially for countries facing limitations in one or more of its three pillars. The approach relies on bringing different stakeholders from the water, food and energy sectors together to collaboratively plan and adopt a holistic approach to resources management. This enables them to address sector-specific issues and develop a comprehensive understanding of the connected sectors leading to better outcomes. However, WEF nexus implementation is currently in its infancy in many countries and stakeholders are in the process of learning how to effectively communicate and collaborate with each other. In this paper, we report the state of the WEF nexus in Jordan, a dry country grappling with water, energy and food production challenges in a changing climate. Stakeholders from line ministries, academics, private sector players and non-state actors were brought together to discuss the status of the WEF nexus and identify challenges that need to be overcome for full realization of the WEF nexus as an operational framework for integrated development at country level. Stakeholders identified 7 cardinal lessons in the process of WEF nexus implementation in Jordan. These are that (i) data/information sharing is vital (ii) WEF nexus requires funding, (iii) collaborations among actors is key, (iv) inclusivity in planning is necessary, (v) clear responsibilities and boundaries among stakeholders are needed, (vi) sustainability and cohesion are a must and (vii) building trust among and within organizations is a primary ingredient for success. A deeper understanding of the interrelated dynamics of these challenges is required to foster the WEF nexus in Jordan as the issues are grave but not insurmountable. It is therefore suggested that deliberate efforts are needed from a technical and policy angle to ensure full operationalization of the WEF nexus approach in Jordan and elsewhere.</p