1,344 research outputs found

    LIPIcs, Volume 251, ITCS 2023, Complete Volume

    Get PDF
    LIPIcs, Volume 251, ITCS 2023, Complete Volum

    Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5

    Get PDF
    This ļ¬fth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different ļ¬elds of applications and in mathematics, and is available in open-access. The collected contributions of this volume have either been published or presented after disseminating the fourth volume in 2015 in international conferences, seminars, workshops and journals, or they are new. The contributions of each part of this volume are chronologically ordered. First Part of this book presents some theoretical advances on DSmT, dealing mainly with modiļ¬ed Proportional Conļ¬‚ict Redistribution Rules (PCR) of combination with degree of intersection, coarsening techniques, interval calculus for PCR thanks to set inversion via interval analysis (SIVIA), rough set classiļ¬ers, canonical decomposition of dichotomous belief functions, fast PCR fusion, fast inter-criteria analysis with PCR, and improved PCR5 and PCR6 rules preserving the (quasi-)neutrality of (quasi-)vacuous belief assignment in the fusion of sources of evidence with their Matlab codes. Because more applications of DSmT have emerged in the past years since the apparition of the fourth book of DSmT in 2015, the second part of this volume is about selected applications of DSmT mainly in building change detection, object recognition, quality of data association in tracking, perception in robotics, risk assessment for torrent protection and multi-criteria decision-making, multi-modal image fusion, coarsening techniques, recommender system, levee characterization and assessment, human heading perception, trust assessment, robotics, biometrics, failure detection, GPS systems, inter-criteria analysis, group decision, human activity recognition, storm prediction, data association for autonomous vehicles, identiļ¬cation of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classiļ¬cation. Finally, the third part presents interesting contributions related to belief functions in general published or presented along the years since 2015. These contributions are related with decision-making under uncertainty, belief approximations, probability transformations, new distances between belief functions, non-classical multi-criteria decision-making problems with belief functions, generalization of Bayes theorem, image processing, data association, entropy and cross-entropy measures, fuzzy evidence numbers, negator of belief mass, human activity recognition, information fusion for breast cancer therapy, imbalanced data classiļ¬cation, and hybrid techniques mixing deep learning with belief functions as well

    Functional connectivity and dendritic integration of feedback in visual cortex

    Get PDF
    A fundamental question in neuroscience is how different brain regions communicate with each other. Sensory processing engages distributed circuits across many brain areas and involves information flow in the feedforward and feedback direction. While feedforward processing is conceptually well understood, feedback processing has remained mysterious. Cortico-cortical feedback axons are enriched in layer 1, where they form synapses with the apical dendrites of pyramidal neurons. The organization and dendritic integration of information conveyed by these axons, however, are unknown. This thesis describes my efforts to link the circuit-level and dendritic-level organization of cortico-cortical feedback in the mouse visual system. First, using cellular resolution all-optical interrogation across cortical areas, I characterized the functional connectivity between the lateromedial higher visual area (LM) and primary visual cortex (V1). Feedback influence had both facilitating and suppressive effects on visually-evoked activity in V1 neurons, and was spatially organized: retinotopically aligned feedback was relatively more suppressive, while retinotopically offset feedback was relatively more facilitating. Second, to examine how feedback inputs are integrated in apical dendrites, I optogenetically stimulated presynaptic neurons in LM while using 2-photon calcium imaging to map feedback-recipient spines in the apical tufts of layer 5 neurons in V1. Activation of a single feedback-providing input was sufficient to boost calcium signals and recruit branch-specific local events in the recipient dendrite, suggesting that feedback can engage dendritic nonlinearities directly. Finally, I measured the recruitment of apical dendrites during visual stimulus processing. Surround visual stimuli, which should recruit relatively more facilitating feedback, drove local calcium events in apical tuft branches. Moreover, global dendritic event size was not purely determined by somatic activity but modulated by visual stimuli and behavioural state, in a manner consistent with the spatial organization of feedback. In summary, these results point toward a possible involvement of active dendritic processing in the integration of feedback signals. Active dendrites could thus provide a biophysical substrate for the integration of essential top-down information streams, including contextual or predictive processing

    Experimental studies of radiation reaction in strong fields with Bayesian inference and model selection

    Get PDF
    Radiation reaction is the recoil of a charge upon emitting radiation. This effect is expected to play a significant role in the dynamics of charges, particularly electrons, and the radiation they produce in strong-field environments. Of particular interest are environments in which the electric field strength approaches the Schwinger field, E_sch=(m_e^2 c^3)/eā„=1.38Ɨ10^16 Vcm^-1 defined as the field strength which can induce electron-positron pair production from vacuum. Electric field strengths approaching the Schwinger field may be generated by astrophysical bodies, such as pulsars and quasars. In such environments, classical theories of radiation reaction are expected to break down. Thus, a quantum description of radiation reaction is needed to accurately model radiation generation and other related processes such as pair production in these environments. The subject of this thesis is an experiment, conducted at the Central Laser Facility in 2021, the aim of which was to measure radiation reaction. The experiment utilised an all-optical set-up in which an energetic electron beam (peak energy ā‰ˆ1 GeV) generated by a wakefield accelerator collided with a tightly focussed, counter-propagating laser pulse. In this thesis, I introduce and discuss a Bayesian analysis procedure which I have developed. This allows the post-collision electron spectrum and the spectrum of gamma radiation emitted during the col- lision to be used to quantitatively compare different models of radiation reaction, whilst also retrieving information concerning the collision conditions which could not be measured during the experiment. We find evidence of radiation reaction to 8Ļƒ, the highest degree of significance of any all-optical experi- ment to date. Using the Bayesian framework, we find that a quantum model of radiation reaction is more consistent with the spectrum of emitted radiation and the electron energy loss measured experimentally than a classical or a semiclassical model.Open Acces

    Micropipette Manipulation for the Production and Characterisation of Microparticles in Biomaterials Discovery

    Get PDF
    The use of microparticles for biological applications is increasing, and with it, the need for specialised microparticles. While one of the major advantages of microparticles is the ability to fine-tune properties, such as chemistry and morphology to best serve an application, achieving this usually relies on lengthy trial-and-error processes. Micropipette manipulation techniques have proven to be valuable tools in studying cell mechanics, protein dehydration and material characterisation. The techniques permit the study of simple and complex multicomponent systems from an alternative perspective to traditional techniques. Utilising these techniques droplets and particle forming systems can be studied on the microscale and in real time. Thus, providing improved understanding of microparticle formation and aiding in particle design and optimisation. The hypothesis for this work was that micropipette manipulation techniques can be employed to understand and improve formation of bio-instructive microparticles. In this thesis, micropipette manipulation techniques were used to study a series of microparticle systems. To better enable this application, methods were developed to improve or extend existing analysis practices. The new routines allowed for a reduction in measurement error to the limit of detection, improved efficiency, and increased processing capabilities. Additionally new methods were developed for analysing droplet microstructure. A comprehensive assessment of the impact of the most widely utilised microparticle materials, poly(vinyl alcohol) (PVA) and poly(D, L lactic acid) (PDLLA), on solvent/water interfaces was conducted using the static equilibrium interfacial tension method. The polymers were treated as additives to two solvent/water combination base systems (dichloromethane (DCM) and ethyl acetate.) From this assessment empirical equations were derived for calculating the interfacial tension for given concentrations of the polymers. The maximum interfacial tension for DCM/water to remain as stable drops during particle formation was determined as approximately 11.1 mN m-1. Droplet dissolution was assessed for both base solvents with a range of PDLLA/PVA concentrations. The diffusion coefficients for the base solvents in water were 17 Ā± 3.8 x10-6 cm2 s-1 (DCM) and 10.1 Ā± 0.28 x10-6 cm2 s-1 (ethyl acetate). Negligible change was seen for the addition of polymer to either phase. Comparisons to the Epstein-Plesset model and the activity-based model for dissolution were conducted for both solvents for the range of PDLLA concentrations concerned. Dissolution followed the curve of the Epstein-Plesset model but deviated from the expected final size given by the activity-based dissolution model. A series of novel, bio-instructive surfactants were assessed for their use in particle formation through the polymerisation of monomer droplets produced using droplet microfluidics. The effectiveness of the different surfactants was determined using static equilibrium interfacial tension measurements. Different core monomers, polymer architecture and hydrophilic and hydrophobic components were considered. Optimum concentrations of surfactants were taken into droplet microfluidics for optimised particle production. Flow maps were generated mathematically using the optimised compositions and showed good agreement with the stable regions found experimentally. Investigations of material transfer between the monomer drop and the surroundings showed unusual behaviour by the monomer for which a mechanism is proposed to explain such behaviour. A dual surfactant system for enabling the production of biodegradable microparticles using droplet microfluidics was investigated and the concentrations optimised for performance and application criteria. The particles produced using PDLLA in ethyl acetate formed secondary droplets both inside and on the surface of drop as dissolution occurred. By varying the concentrations of surfactant, core polymer and continuous phase saturation, the morphology of these particles could be manipulated. Using EGPEA-mPEGMA it was possible to generate a topography, reproducible between single particles studies and high volume microparticle production, that could be controlled by adjusting surfactant concentration. The studies presented here demonstrate the improved understanding of selected microparticle formation systems through the application of micropipette manipulation techniques. Characterisation of novel biomaterials was conducted which in turn allowed the optimisation of bio-instructive microparticles through droplet microfluidics

    Neuromolecular basis of anomalous feeding behaviour in the valproate rat model of autism

    Get PDF
    Autism spectrum disorder (ASD), which affects circa 1% of the global population, is characterized by impairments in social communication, interaction, language disability, sensory anomalies, repetitive behaviours, and intellectual disability. Aberrant feeding behaviour is a common comorbidity of ASD. ASD individuals often demonstrate extreme food selectivity, refusal, dependence on few very particular food items, neophobia etc. which can lead to nutritional deficiencies affecting development. However, the underlying neurophysiological mechanisms of aberrant food intake in ASD are not well known. Prenatal exposure to the antiepileptic drug, valproic acid (VPA), leads to autism. The prenatally VPA-exposed rats are model organisms to study ASD and they show ASD-like symptoms of, among others, elevated anxiety and decreased social interaction. Importantly, very little is known about appetite control in these animals. The overall goal of the studies included in this thesis was to identify potential feeding behavioural anomalies and associated neuromolecular changes in the VPA rat model of ASD. We thus hypothesize that ASD is associated with abnormal appetite and reward-driven feeding. The key factors shaping consumption involve hunger (determines search for calories), satiation (underpins termination of feeding) and reward (consumption for the 'pleasantness' of food, regardless of the energy requirements). Thus, in the first Specific Aim of this thesis, the hunger processing in the VPA animals was investigated. The ad libitum intake of ā€˜blandā€™ standard laboratory chow was assessed in VPA versus non-VPA controls maintained continuously on this diet. The adult VPA rats ate less ā€˜blandā€™ chow than healthy controls did, and it was coupled with a moderately lower body weight than that of the controls. VPA rats also ate less of the standard chow after acute food deprivation. There was an aberrant change in c-Fos immunoreactivity in key brain sites that govern food intake, including the hypothalamic and brain stem areas, in the VPA animals in contrast to the healthy controls upon food deprivation, which indicates differences in neural processing of hunger in autism. This finding is further supported by a lack of change in expression patterns of feeding-related genes (including oxytocin (OT), Agouti-related protein (AgRP) and mu opioid receptor (MOR)) upon hunger in the hypothalamus in the VPAs as opposed to the controls. Cumulatively, these findings suggest that hunger processing is altered in the VPA rats. In the second Specific Aim of this project, intake of rewarding diets in the VPA rats was examined to address whether ASD affects pleasure-driven consumption. In episodic meal consumption paradigms, i.e., in scenarios in which energy non-deprived animals were given a brief and non-habitual access to diets that differ in palatability, the VPA rats were found to consume elevated amounts of tasty liquid and solid diets. These data suggest that VPA rats display not only altered energy homeostatis processing (as shown in Specific Aim 1), but also indicate changes in the regulation of eating for palatability. Considering the abnormal OT signalling in autism and the fact that OT decreases feeding for energy and feeding for palatability, the third Specific Aim addressed whether VPA rats exhibit heightened sensitivity to exogenously administered OT, a peptide known for its anorexigenic properties. Intraperitoneal OT treatment was found to reduce episodic intake of palatable diets as well as post-energy deprivation intake of ā€˜blandā€™ chow; however, the dose needed to generate hypophagia was lower in VPAs than in controls. c-Fos immunohistochemistry revealed that the lower OT dose found to be anorexigenic in VPA rats, was sufficient to affect brain activation in a manner typical for hypophagia, whereas in healthy control rats, it did not induce significant c-Fos changes. Importantly, OT is involved also in the process of avoidance of toxic foods, i.e., it facilitates the development of a conditioned taste aversion (CTA). Therefore, the goal of the Specific Aim 4, was to assess whether VPA animals display atypical taste aversion acquisition. It was found that VPAs failed to develop aversion to a standard dose of LiCl that induces a CTA in healthy non-ASD controls. In line with the outcome of the behavioural study, the immunohistochemical analysis revealed lower c-Fos-OT colocalization in the PVN in VPAs and a less pronounced broader CTA circuit c-Fos response in ASD animals compared to controls after LiCl treatment. Taken together, evidence presented in this thesis shows that ASD is associated with abnormal appetite in VPA rats and it offers an insight into the neural basis of this phenomenon. The VPA animals show a slight decrease in intake of standard ā€˜blandā€™ chow, an elevated drive to consume palatable tastants, and resistance to taste aversion. These anomalies in feeding behaviours are underpinned by distinct changes in brain activation and gene expression patterns, as well as altered sensitivity to anorexigenic properties of OT, a neuropeptide known to affect other symptoms of ASD, from social deficits to anxiety

    Micro/Nano Structures and Systems

    Get PDF
    Micro/Nano Structures and Systems: Analysis, Design, Manufacturing, and Reliability is a comprehensive guide that explores the various aspects of micro- and nanostructures and systems. From analysis and design to manufacturing and reliability, this reprint provides a thorough understanding of the latest methods and techniques used in the field. With an emphasis on modern computational and analytical methods and their integration with experimental techniques, this reprint is an invaluable resource for researchers and engineers working in the field of micro- and nanosystems, including micromachines, additive manufacturing at the microscale, micro/nano-electromechanical systems, and more. Written by leading experts in the field, this reprint offers a complete understanding of the physical and mechanical behavior of micro- and nanostructures, making it an essential reference for professionals in this field
    • ā€¦
    corecore