1,258 research outputs found
Advances and Applications of DSmT for Information Fusion. Collected Works, Volume 5
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
On the Utility of Representation Learning Algorithms for Myoelectric Interfacing
Electrical activity produced by muscles during voluntary movement is a reflection of the firing patterns of relevant motor neurons and, by extension, the latent motor intent driving the movement. Once transduced via electromyography (EMG) and converted into digital form, this activity can be processed to provide an estimate of the original motor intent and is as such a feasible basis for non-invasive efferent neural interfacing. EMG-based motor intent decoding has so far received the most attention in the field of upper-limb prosthetics, where alternative means of interfacing are scarce and the utility of better control apparent. Whereas myoelectric prostheses have been available since the 1960s, available EMG control interfaces still lag behind the mechanical capabilities of the artificial limbs they are intended to steerāa gap at least partially due to limitations in current methods for translating EMG into appropriate motion commands. As the relationship between EMG signals and concurrent effector kinematics is highly non-linear and apparently stochastic, finding ways to accurately extract and combine relevant information from across electrode sites is still an active area of inquiry.This dissertation comprises an introduction and eight papers that explore issues afflicting the status quo of myoelectric decoding and possible solutions, all related through their use of learning algorithms and deep Artificial Neural Network (ANN) models. Paper I presents a Convolutional Neural Network (CNN) for multi-label movement decoding of high-density surface EMG (HD-sEMG) signals. Inspired by the successful use of CNNs in Paper I and the work of others, Paper II presents a method for automatic design of CNN architectures for use in myocontrol. Paper III introduces an ANN architecture with an appertaining training framework from which simultaneous and proportional control emerges. Paper Iv introduce a dataset of HD-sEMG signals for use with learning algorithms. Paper v applies a Recurrent Neural Network (RNN) model to decode finger forces from intramuscular EMG. Paper vI introduces a Transformer model for myoelectric interfacing that do not need additional training data to function with previously unseen users. Paper vII compares the performance of a Long Short-Term Memory (LSTM) network to that of classical pattern recognition algorithms. Lastly, paper vIII describes a framework for synthesizing EMG from multi-articulate gestures intended to reduce training burden
Modern meat: the next generation of meat from cells
Modern Meat is the first textbook on cultivated meat, with contributions from over 100 experts within the cultivated meat community.
The Sections of Modern Meat comprise 5 broad categories of cultivated meat: Context, Impact, Science, Society, and World.
The 19 chapters of Modern Meat, spread across these 5 sections, provide detailed entries on cultivated meat. They extensively tour a range of topics including the impact of cultivated meat on humans and animals, the bioprocess of cultivated meat production, how cultivated meat may become a food option in Space and on Mars, and how cultivated meat may impact the economy, culture, and tradition of Asia
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Analysis of bendable osteochondral allograft treatment and investigations of articular cartilage wear mechanics
Osteoarthritis is a highly prevalent, debilitating disease characterized by the wear and degradation of articular cartilage. While many surgical interventions exist, few are consistently effective and those that are effective are not necessarily suitable for all patients. The objective of this dissertation is to improve patient care through the development of a new surgical technique and through basic science studies which seek to better understand articular cartilage wear initiation. Four studies, which address this objective are summarized below.
Osteochondral allograft transplantation provides a safe and effective treatment option for large cartilage defects, but its use is limited partly due to the difficulty of matching articular surface curvature between donor and recipient. We hypothesize that bendable osteochondral allografts may provide better curvature matching for patella transplants in the patellofemoral joint. The finite element study presented in Chapter 2 investigates patellofemoral joint congruence for unbent and bendable osteochondral allografts, at various flexion angles. Finite element models were created for 12 femur-patella osteochondral allograft pairings. Two grooves were cut into the bony substrate of each allograft, allowing the articular layer to bend. Patellofemoral joints with either unbent (OCA) or permanently bent (BOCA) allografts were articulated from 40 to 70 degrees flexion and contact area was calculated. OCAs and BOCAs were then shifted 6 mm distally toward the tibia (S-OCA, S-BOCA) to investigate the influence of proximal-distal alignment on congruence. On average, no significant difference in contact area was found between native patellofemoral joints and either OCAs or BOCAs (p > 0.25), indicating that both types of allografts restored native congruence. This result provides biomechanical support in favor of an emerging surgical procedure. S-BOCAs resulted in a significant increase in contact area relative to the remaining groups (p < 0.02). The fact that bendable osteochondral allografts produced equally good results implies that these bendable allografts may prove useful in future surgical procedures, with the possibility of transplanting them with a small distal shift. Surgeons who are reluctant to use osteochondral allografts for resurfacing patellae based on curvature matching capabilities may be more amenable to adopting bendable osteochondral allografts.
The recent development of bendable osteochondral allografts provides the potential for improved osteoarthritis treatment for joints whose current treatment is unsatisfactory. One such joint is the carpometacarpal joint in the thumb. While the current standard of care for carpometacarpal osteoarthritis, ligament reconstruction and tendon interposition, can reduce pain in the joint, it does not restore full joint function and mobility. A proposed alternative includes using an osteochondral allograft harvested from the femoral trochlea in a donor knee, machining grooves in the bone to allow the allograft to bend, and replacing the trapezium with this bent osteochondral allograft [1,2]. Chapter 3 of this dissertation discusses adjustments to the original design of the bendable allograft and the design of a custom surgical tool to perform the proposed surgery. Specification changes of the allograft included an overall size reduction in order to better fit within the carpometacarpal joint, minimum bone thickness requirements to avoid bone cracking during the surgical procedure, and a reduction from three grooves to two grooves, which provided sufficient bending yet avoided fracture of the allograft. The surgical tool was designed to be a custom forceps device, whose primary features included (1) jaws with an angled face to match the angle of allograft bending and (2) insertion holes for the Kirschner wire and compression screws used to anchor the allograft in the bent position. These customizations allow the tool to be used to bend the allograft, fix it in the bent configuration, and place the allograft in its proper position in the hand during anchoring of the bent allograft to the native trapezium.
The final two studies presented in this dissertation focus on furthering our current understanding of wear and structure-function relationships of articular cartilage. We hypothesize that cartilage wears due to fatigue failure in reciprocating compression instead of reciprocating friction. Chapter 4 compares reciprocating sliding of immature bovine articular cartilage against glass in two testing configurations: (1) a stationary contact area configuration (SCA), which results in static compression, interstitial fluid depressurization and increasing friction coefficient during reciprocating sliding, and (2) a migrating contact area configuration (MCA), which maintains fluid pressurization and low friction while producing reciprocating compressive loading during reciprocating sliding. Contact stress, sliding duration, and sliding distance were controlled to be similar between test groups. SCA tests exhibited an average friction coefficient of Ī¼=0.084Ā±0.032, while MCA tests exhibited a lower average friction coefficient of Ī¼=0.020Ā±0.008 (p<10^(-4)).
Despite the lower friction, MCA cartilage samples exhibited clear surface damage with a significantly greater average surface deviation from a fitted plane after wear testing (R_q=0.125Ā±0.095 mm) than cartilage samples slid in a SCA configuration (R_q=0.044Ā±0.017 mm, p=0.002), which showed minimal signs of wear. Polarized light microscopy confirmed that delamination damage occurred between the superficial and middle zones of the articular cartilage in MCA samples. The greatest wear was observed in the group with lowest friction coefficient, subjected to cyclical instead of static compression, implying that friction is not the primary driver of cartilage wear. Delamination between superficial and middle zones imply the main mode of wear is fatigue failure under cyclical compression, not fatigue or abrasion due to reciprocating frictional sliding.
The final study of this dissertation, presented in Chapter 5, investigates the importance of collagen fibril distribution in articular cartilage computational models. Finite element models were created to approximate a bovine humeral head and replicate previous experimental loading conditions [3]. Five different finite element analyses were run, each using a different fibril distribution model. Three of the models used two, four, or eight discrete fibril bundles, while two models used continuous fibril distributions with either isotropic or depth-dependent ellipsoidal distributions.
Two primary findings arose from this investigation. The first was the discovery that as the fibril distribution became more isotropic, the strain throughout the tissue decreased, even though the contact area between the articular surface and rigid platen remained relatively equal across distribution models. This suggests that computational models which approximate the collagen fibrils with an isotropic distribution may be underestimating the strain through the depth of the tissue. The second primary finding was that in the discrete distribution model with two fibril bundles, which followed the classically described Benninghoff structure [4], the greatest magnitude of shear strain during compressive loading was observed in the middle zone. However, the highest magnitude of shear strain observed in the isotropic fibril distribution model occurred in the deep zone near the subchondral surface. The observed results suggest that the type of fibril distribution used to model collagen in articular cartilage plays a role in depth-dependent strain magnitude and strain distribution
The impact of head orientation with respect to B0 on diffusion tensor MRI measures
Diffusion tensor MRI (DT-MRI) remains the most commonly used approach to characterise white matter (WM) anisotropy. However, DT estimates may be affected by tissue orientation w.r.t. Bā0
due to local gradients and intrinsic T2 orientation dependence induced by the microstructure. This work aimed to investigate whether and how diffusion tensor MRI-derived measures depend on the orientation of the head with respect to the static magnetic field, Bā0
ā . By simulating WM as two compartments, we demonstrated that compartmental T2 anisotropy can induce the dependence of diffusion tensor measures on the angle between WM fibres and the magnetic field. In in vivo experiments, reduced radial diffusivity and increased axial diffusivity were observed in white matter fibres perpendicular to Bā0
compared to those parallel to Bā0
ā . Fractional anisotropy varied by up to 20% as a function of the angle between WM fibres and the orientation of the main magnetic field. To conclude, fibre orientation w.r.t. Bā0
is responsible for up to 7% variance in diffusion tensor measures across the whole brain white matter from all subjects and head orientations. Fibre orientation w.r.t. Bā0
may introduce additional variance in clinical research studies using diffusion tensor imaging, particularly when it is difficult to control for (e.g. fetal or neonatal imaging, or when the trajectories of fibres change due to e.g. space occupying lesions)
Individualisation of transcranial electric stimulation to improve motor function after stroke:Current challenges and future perspective
Transcranial electric stimulation (tES) is a non-invasive brain stimulation technique that could potentially improve motor rehabilitation after stroke. However, the effects of tES are in general stronger in healthy individuals compared to people with stroke. Interindividual variability in brain structure and function due to stroke potentially explain this difference in effects. This thesis describes the development of methods to facilitate the individualisation of tES in people with stroke and identifies objective neurophysiological correlates of motor learning that could potentially help to monitor the response to tES.In chapter 2, EEG correlates of explicit motor task learning were derived in healthy, young participants. Chapter 3 investigated the effects of 3 different tDCS configurations (sham, targeting contralateral M1 and targeting the full resting motor network) on corticospinal excitability. Both conventional and motor network tDCS did not increase corticospinal excitability relative to sham stimulation. Chapter 4 describes methods to create head models of people with stroke and assesses the effects of stroke lesions on the electric fields within stimulation targets. Chapter 5 describes a method to experimentally determine the electric conductivity of the stroke lesion. Finally, Chapter 6 analyses the electric fields generated by conventional tDCS in people with stroke and age-matched controls. It is shown that the one-size-fits-all approach results in more variable electric fields in people with stroke compared to controls. Optimisation of the electrode positions to maximise the electric field in stimulation targets increases the electric fields in people with stroke to the same level as found in healthy controls.This thesis shows anatomical and motor function variability exists between people with stroke due to differences in lesion characteristics. While there are several opportunities to individualise tES, more research is needed to investigate if this improves the effects of tES. As such, clinical implementation of tES seems unrealistic in the foreseeable future.<br/
System-wide stress testing & systemic risk
The financial crisis of 2007-2009, which brought the entire system at the brink of collapse, renewed efforts to guard against financial instability. A key pillar of the post-crisis regulatory toolkit is "stress testing". Stress tests provide a forward-looking examination of firmsā potential losses during severely ad- verse conditions. And enable timely action to recapitalise those firms who experience capital shortfalls in such crisis scenarios. Todayās regulatory stress tests do not heed the key lesson of the financial crisis: amplifications in the networked financial system must be taken into account to be able to assess systemic risk. Because of this, these tests are unable to assess systemic risk and ergo to address it ā defeating their raison dāĖetre.
The overarching research question in this thesis is whether new building blocks ā expressing the heterogeneity of institutions, contracts, markets, constraints and behaviour in the interconnected financial system ā can be supplied for system-wide stress tests to better capture the endogenous amplification of shocks in order to improve the assessment of systemic risk and the evaluation of prudential policies to address financial fragility.
The cornerstone of my thesis is the development of a generic network-based method, comprised of these five building blocks (i.e. institutions, contracts, markets, constraints and behaviour), for system-wide stress testing ā which has gained traction from leading central banks, including the Bank of England and the European Central Bank. Using this method, I implement two data-driven models to address some of the most salient financial stability questions of today. First, we ask how the regulatory buffer size and its usability under Basel III affect systemic risk? We find that financial resilience decreases if regulatory buffers are seen to be less usable by banks. If regulatory buffers are not treated as usable, then regulatory buffers de facto act as capital requirements. In such case, if an adverse shock threatens an institution to breach its capital buffers constraints, it is forced to delever, which tends to have a destabilising effect on the financial markets. We show that the size of usable regulatory buffers that is required to maintain stability is underestimated if the interaction between exposure loss contagion, funding contagion, overlapping portfolio contagion and margin call contagion is not taken into account. Second, we inquire what the systemic implications are of the bail-in design to resolve systemically important banks? First of all, we find that the bail-in design tremendously matters for whether bail-ins can be credibly executed in system-wide financial crises and cases of large systemically impor- tant bank failures, without significantly exacerbating financial distress. Our results demonstrate that an early bail-in, strong recapitalisation and fair distribution of equity compensation by means of debt-to-equity conversion rates makes bail-in a feasible option on the table for idiosyncratic cases of bank failure and limits ā but not eliminates ā contagion in cases of system-wide distress. We further show that excluding run-prone, short-term debt from the application of the bail-in tool, increasing the requirements on loss absorbing debt and providing investors with certainty about the bail-in design lowers contagion in system-wide crises to manageable levels. Our findings highlight that while well-designed bail-ins could be credibly administered in system-wide crises, it is not clear that the current bail-in design is in the regime of stability. Altogether, the methods and findings of this thesis emphasise the promise that system-wide stress tests hold for regulators to efficaciously assess systemic risk and calibrate prudential policies constituting the financial architecture
Development and application of NMR methods to study biomolecular dynamics
Structural biology has generated profound insights into biomolecular machines. The molecular basis of processes like binding, folding, catalysis and regulation, which underlie the inner working of living organisms would have largely remained unexplored without the thousands of structures that have been solved over the years. But these machines, formed by proteins and nucleic acids, are inherently dynamic, and information about this fourth dimension, the modulation of their structure with time, is often lacking. Nuclear magnetic resonance (NMR) is exquisitely suited to characterize dynamics over a wide timescale, from picoseconds, where amplitudes and correlation times can be extracted, to microsecond, milliseconds and seconds, where in favourable cases information about the kinetics, the thermodynamics and the structure of an excited state can be retrieved. With increasing size of the molecular system under consideration, however, this characterization is progressively challenging for NMR, and the analysis often focuses on 13CH3 spin systems in a perdeuterated background. As an alternative approach, fluorine NMR has grown in popularity. The 19F isotope can be introduced site-specifically, it gives rise to background-free one-dimensional spectra and the technique bypasses the need for perdeuteration. In my disseration, I expanded the existing toolkit of 19F NMR, applied 19F experiments that report on dynamics to high-molecular weight systems and combined their advantages with established methyl group NMR techniques.
Development of 19F relaxation dispersion experiments
To develop 19F relaxation dispersion (RD) experiments, I used a 7.5 kDa cold shock protein from the thermophilic organism Thermotoga maritima as a protein folding/unfolding model system. The global analysis of three RD experiments showed consistent results for the two-state exchange process. Our new rotating frame relaxation pulse sequences allowed to extract the absolute chemical shift of the unfolded state and significantly extended the range of timescales that can be assessed experimentally. Employing a 360 kDa double heptameric complex, I validated the applicability of the experiments on a highly challenging assembly.
Conformational changes in the exoribonuclease Xrn2
The 5'-3' exoribonuclease Xrn2 operates in the nucleus in RNA processing and RNA turn-over pathways. Static structures of its cytoplasmic homologue Xrn1 in the presence of substrates implicate that the enzymes undergo conformational changes to progress through the catalytic cycle. Here, I solved the X-ray structure of Xrn2 from the thermophilic organism Chaetomium thermophilum to 3 Ć
resolution and combined methyl group and fluorine relaxation dispersion to characterize the exchange in a 100 kDa apo protein core construct in solution. Upon binding of a substrate, the conformational equilibrium is substantially shifted towards the active state. Importantly, the 19F experiments allowed to characterize dynamics in these unstable samples and I could show that the exchange of the enzyme:substrate complex are largely suppressed.
Multi-site exchange in a neomycin-sensing riboswitch
The existence of multiple sparsely populated states complicates the characterization of an exchanging system. Using a synthetic neomycin-binding riboswitch bound to different aminoglycoside ligands, I demonstrated that fluorine NMR can be employed to study exchange topologies with up to four states. To this end, I take advantage of an additional off-resonance technique, 19F chemical exchange saturation transfer. Combined with 19F RD and longitudinal exchange experiments, the results support the notion of a modular impact of aminoglycoside functional groups on the riboswitch dynamics.
Taken together, these results expand and complement the NMR toolbox to study exchanging systems, with an emphasis on high-molecular weight systems and intricate exchange topologies involving more than two states. Furthermore, they elucidate the molecular dynamics in the 5'-3' exoribonuclease Xrn2 and provide a conceptional framework to study dynamics in related systems such as Xrn1
2015 GREAT Day Program
SUNY Geneseoās Ninth Annual GREAT Day.https://knightscholar.geneseo.edu/program-2007/1009/thumbnail.jp
LIPIcs, Volume 261, ICALP 2023, Complete Volume
LIPIcs, Volume 261, ICALP 2023, Complete Volum
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