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Non-classical and chaotic motion of two-dimensional light
Get PDFUnderstanding how classical and quantum descriptions of nature connect remains one of the central challenges in physics. Classical mechanics provides a deterministic picture for macroscopic systems, while quantum mechanics is governed by probabilistic behavior at microscopic scales. In the intermediate regime — where quantum effects clash with classical intuition, such as tunneling through forbidden regions or the appearance of chaos-like features in quantum systems — new experimental insight is essential.This thesis investigates two questions: How fast can a particle move within a classically forbidden region? and In what ways can classical chaos leave signatures in quantum systems? Both problems are explored experimentally using an optical microcavity filled with dye, in which confined photons behave as massive particles. This platform provides offers high-resolution spatial and temporal access to quantities that are difficult to measure in traditional quantum systems.In the first part of this thesis, we examine the kinematics of classically forbidden motion, where the particle energy is lower than the potential energy of a barrier or a potential step. While classical mechanics forbids such motion, quantum mechanics allows particles to explore these regions due to an effectively negative local kinetic energy, raising the long-standing question of tunneling time: How long does it take to traverse a barrier? We address this by engineering a system in which the speed associated with forbidden motion can be derived and directly measured. Different theoretical approaches to tunneling time are compared, and we discuss how our results relate to and challenge existing models, with particular attention to Bohmian mechanics.The second half of this thesis focuses on the emergence of classical chaos signatures in quantum systems. While the correspondence principle suggests that quantum behavior should resemble classical physics in certain limits, quantum systems are fundamentally linear and therefore cannot exhibit chaos in the classical sense. Nonetheless, under specific conditions – such as non-resonant optical pumping leading to lasing – we observe sensitivity to initial conditions in a billiard-shaped potential.By combining novel experimental techniques with foundational theoretical questions, this thesis contributes to the ongoing dialogue between classical and quantum physics.<br/
Bistable Perception Discriminates Between Depressive Patients, Controls, Schizophrenia Patients, and Their Siblings
Get PDFBackground and Hypothesis Individuals with schizophrenia have less priors than controls, meaning they rely less upon their prior experiences to interpret the current stimuli. These differences in priors are expected to show as higher alternation rates in bistable perception tasks like the Structure-from-Motion (SfM) paradigm. In this paradigm, continuously moving dots in two dimensions are perceived subjectively as traveling along a three-dimensional sphere, which results in a direction of motion (left or right) that shifts approximately every few seconds. Study Design Here, we tested healthy controls, patients with schizophrenia, siblings of patients with schizophrenia, and patients with depression with both the intermittent and continuous variants of the SfM paradigm. Study Results In the intermittent variant of the SfM paradigm, depressive patients exhibited the lowest alternation rate, followed by unaffected controls. In contrast, patients with schizophrenia and their unaffected siblings displayed significantly higher alternation rates. In the continuous variant of the SfM paradigm, patients with schizophrenia showed the lowest mean percept durations, while there were no differences between the other three groups. Conclusions The intermittent SfM paradigm is a candidate endophenotype for schizophrenia. The aberrant processing in the patients may stem from alterations in adaptation and/or cross-inhibition mechanisms leading to changes in priors, as suggested by current models in the field. The intermittent SfM paradigm is, hence, a trait marker that offers the great opportunity to investigate perceptual abnormalities across the psychiatry spectrum, ranging from depression to psychosis.</p
FibrilPaint to determine the length of Tau amyloids in fluids
Get PDFTau aggregation into amyloid fibrils is linked to the development of neurodegenerative diseases, including Alzheimer's disease (AD). The molecular processes driving aggregation in disease are still being uncovered, highlighting the need for innovative tools to study aggregation reactions. Here, we introduce FibrilPaint1 as a tool to measure the size of Tau amyloid fibrils in fluids, from early aggregation stages to mature fibrils. FibrilPaint1 is a 22mer peptide with exciting properties: i) FibrilPaint1 binds fibrils with nanomolar affinity; ii) it also binds to precursors, down to a size of only 4 layers; iii) it does not bind to monomers; iv) it is fluorescently labeled, which allows monitoring and localizing interactions; v) FibrilPaint1 recognizes various Tau fibrils, including patient-derived fibrils from AD, corticobasal degeneration (CBD), and frontotemporal dementia (FTD); vi) it also binds to fibrils from amyloids derived from Amyloid-β, α-synuclein, and huntingtin vii) FibrilPaint1 is selective for the amyloid state and does not have background binding to amorphous aggregates, blood serum, or cell lysate. In combination with flow-induced dispersion analysis (FIDA), a microfluidics technology, we determined the molecular size of amyloid fibrils with submicroliter sample volumes. This setup acts as a molecular ruler at layer resolution-we determined Tau fibril length from 4 to 1100 layers in solution. This is an interesting parameter for molecular studies in dementia, with potential for diagnostic applications.</p
Understanding planning support systems institutionalization in the planning process through actor–network theory:The case of the strategic development framework methodology
Get PDFStudies conceptualize planning support systems (PSS) outcomes as post-implementation use (limited or continuous) in the planning process. This paper presents another perspective on PSS implementation outcomes—its institutionalization in the planning process. It combines the sociology of translation (SoT) and actor–network theory (ANT) as an analytic framework to investigate and explain a country’s PSS institutionalization in the planning process over 8 years. Ethnographic methods aid qualitative data collection and analysis. Results provide insight in the following three ways: (1) how heterogeneous actors create networks for PSS use, (2) to what extent the network(s) shape PSS institutionalization, and (3) why PSS institutionalization in planning processes does or does not happen. This paper argues that if PSS research investigates and documents these three ways, it will provide additional insights into the decisions, actions, and agencies of PSS institutionalization compared to studies that conceptualize PSS outcomes with use. It contributes to PSS research and practice by demonstrating the value of ANT in enhancing our understanding of PSS institutionalization in planning processes. It recommends further studies to validate this research regarding both retrospective understanding of and prospective management for PSS institutionalization
A conceptual model to quantify probabilistic dike breach outflow
Get PDFHydrodynamic models can provide accurate information on the consequences of a dike breach, but their long computation times hinder the analysis of uncertainties and scenarios during a time-sensitive emergency situation. Conceptual models use simplified rules and relations, and allow for much faster computation while preserving reasonable accuracy. In this study, we develop a conceptual model with breach growth that estimates the dike breach outflow for varying river discharge events and for varying dike breach locations along the Rhine’s bifurcations in the Netherlands and Germany. The results show that the model is able to provide a good estimate of the breach outflow, regardless of river discharge waves shape and peak discharge. The model achieves an approximate error of 10 to 15% compared to an operational hydrodynamic model of the study area. Its computation speed allows the analysis of thousands of scenarios per minute, enabling decision makers to probabilistically analyse breach outflow hydrographs at sampled critical water levels for an incoming extreme river discharge wave. We conclude that this conceptual model can provide realistic first estimates of breach outflow for large-scale dike breaches, while requiring little input data and computational time.</p
Mobile Therapeutic Attention for Treatment-Resistant Schizophrenia (m-RESIST) Solution for Improving Clinical and Functional Outcomes in Treatment-Resistant Schizophrenia:Prospective, Multicenter Efficacy Study
Get PDFBackground: Treatment-resistant schizophrenia (TRS) is a severe form of schizophrenia associated with low adherence to treatment and poor outcomes. Mobile health (mHealth) interventions may be effective in preventing relapses, increasing treatment adherence, and managing some of the symptoms of schizophrenia. Mobile therapeutic attention for treatment-resistant schizophrenia (m-RESIST) is an innovative mHealth developed specifically for TRS. Objective: We aim to evaluate the effects of m-RESIST on the clinical and functional outcomes and on the perceived quality of life in people with TRS. Methods: A feasibility study without a control group was performed to test the m-RESIST solution on patients with TRS. Participants were recruited from Spain, Israel, and Hungary. This study’s population (N=31) followed 3 months of intervention. The m-RESIST was configured by an app, a wearable, and a web-based platform. The severity of symptoms was evaluated by using the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression-Schizophrenia (CGI-SCH) scale. Functionality was assessed by the Global Assessment of Functioning and perceived quality of life was evaluated by the EuroQol visual analogue scale (EQ-VAS). Results: Significant reductions were found in symptoms from pretrial to posttrial on the PANSS total (mean difference −7.2, 95% CI −11.1 to −3.4; P=.001), the PANSS positive (mean difference −1.36, 95% CI −2.6 to −0.1; P=.04), the PANSS negative (mean difference −2.1, 95% CI −3.1 to −1.1; P<.001), and the PANSS general symptoms (mean difference −3.8, 95% CI −6.8 to −0.8; P=.02). In almost one-fifth of the participants (6/31), the overall score for the PANSS decreased by more than 20%, which may be considered a clinically significant change. On the CGI-SCH scale, the sum of total severity of illness decreased significantly (P=.03). A decrease in the sum of positive and negative symptoms of the CGI-SCH score was also found (P=.04 and P=.03, respectively). The sum of depressive or cognitive symptoms did not change. The functionality of participants increased significantly on the Global Assessment of Functioning (P≤.001). The perceived quality of life on the EQ-VAS also improved (mean difference 6.7, 95% CI 0.5 to 12.9; P=.04). Conclusions: To our best knowledge, this was the first study to address the efficacy of the mHealth app m-RESIST on the symptoms and functional capacity and on the quality of life for people with TRS. Our preliminary findings showed that implementing the m-RESIST solution decreased the symptoms and severity of disease, and improved the functionality and perceived quality of life among those with TRS. The change of symptoms on the PANSS total may be clinically significant. Modern technologies such as mHealth interventions may be useful in treating symptoms and functionality even in TRS, which is a major clinical challenge, with usually poor outcomes. These results should be corroborated by performing a controlled trial.</p
Toward Efficient Nest Location in Social Insects with Harmonic Radar
Get PDFThis study explores a novel strategy for the location of insect nests using harmonic radar. Instead of tracking individual insects, we propose to tag and release multiple foragers followed by a grid search to determine their nesting grounds. Using collective tag-return behaviour, this approach enables efficient, scalable nest discovery that lays the groundwork for future experimental validation
Deep vectorised operators for pulsatile hemodynamics estimation in coronary arteries from a steady-state prior
Get PDFBackground and objective: Cardiovascular hemodynamic fields provide valuable medical decision markers for coronary artery disease. Computational fluid dynamics (CFD) is the gold standard for accurate, non-invasive evaluation of these quantities in silico. In this work, we propose a time-efficient surrogate model, powered by machine learning, for the estimation of pulsatile hemodynamics based on steady-state priors.Methods: We introduce deep vectorised operators, a modelling framework for discretisation-independent learning on infinite-dimensional function spaces. The underlying neural architecture is a neural field conditioned on hemodynamic boundary conditions. Importantly, we show how relaxing the requirement of point-wise action to permutation-equivariance leads to a family of models that can be parametrised by message passing and self-attention layers. We evaluate our approach on a dataset of 74 stenotic coronary arteries extracted from coronary computed tomography angiography (CCTA) with patient-specific pulsatile CFD simulations as ground truth.Results: We show that our model produces accurate estimates of the pulsatile velocity and pressure (approximation disparity 0.368 ± 0.079) while being agnostic (p<0.05 in a one-way ANOVA test) to re-sampling of the source domain, i.e. discretisation-independent. Conclusion: This shows that deep vectorised operators are a powerful modelling tool for cardiovascular hemodynamics estimation in coronary arteries and beyond.</p
Optical detection of single sub-15 nm objects using elastic scattering strong coupling
Get PDFMetallic nano-objects play crucial roles in diverse fields, including biomedical imaging, nanomedicine, spectroscopy, and photocatalysis. Nano-objects smaller than 15 nm exhibit extremely low scattering cross-sections, posing a significant challenge for optical detection. An approach to enhance optical detection is to exploit nonlinearity of strong coupling regime, especially for elastic scattering, which is universal to all objects. However, there is still no observation of the strong coupling of elastic light scattering from nano-objects. Here, we demonstrate the strong coupling of elastic light scattering in self-assembled plasmonic nanocavities formed between a gold nanoprobe and a gold film. We employ this technique to detect individual objects with diameters down to 1.8 nm. The resonant mode of the nano-object in the nanocavity environment strongly couples with the nanocavity mode, revealing anti-crossing scattering modes under dark-field spectroscopy. The experimental result agrees with numerical calculations, which we use to extend this technique to other metals. Furthermore, our results show that scattering cross-section ratio of the nano-object scales with the electric field to fourth power, similar to surface-enhanced Raman spectroscopy. This work establishes a new possibility of elastic strong coupling and demonstrates its applicability for observing small, non-fluorescent, Raman inactive sub-15 nm objects, complementary to existing microscopes.</p
What have urban digital twins contributed to urban planning and decision making?:From a systematic literature review toward a socio-technical research and development agenda
Get PDFHighlights: What are the main findings? The large gap between ambitions of Urban Digital Twins (UDTs) and their realized contributions is due to the lack of addressing socio-technical complexities. There is a shift in academic literature toward a socio-technical understanding of UDTs. What are the implications of the main findings? A socio-technical research and development agenda is proposed to bridge this gap: Augmented Urban Planning (AUP). It is necessary to consolidate a socio-technical methdology for development and use of UDTs within urban planning processes. Urban digital twins (UDTs) were first discussed in 2018. Seven years later, we ask: What has been their contribution to urban planning and decision making so far? Here, we systematically review 88 peer-reviewed articles to map and compare UDTs’ ambitions with their realized contributions. Our results indicate that despite the vast technical developments, socio-technical challenges have remained largely unaddressed, causing many of UDTs’ ambitions to remain unrealized. We identify three categories in these socio-technical challenges: interdisciplinary integration (II), consensual contextualization (CC), and procedural operationalization (PO). Accordingly, we consolidate a socio-technical research and development agenda to realize the ambitions of UDTs for urban planning and decision making: Augmented Urban Planning (AUP).</p