950 research outputs found

    Classical and quantum algorithms for scaling problems

    Get PDF
    This thesis is concerned with scaling problems, which have a plethora of connections to different areas of mathematics, physics and computer science. Although many structural aspects of these problems are understood by now, we only know how to solve them efficiently in special cases.We give new algorithms for non-commutative scaling problems with complexity guarantees that match the prior state of the art. To this end, we extend the well-known (self-concordance based) interior-point method (IPM) framework to Riemannian manifolds, motivated by its success in the commutative setting. Moreover, the IPM framework does not obviously suffer from the same obstructions to efficiency as previous methods. It also yields the first high-precision algorithms for other natural geometric problems in non-positive curvature.For the (commutative) problems of matrix scaling and balancing, we show that quantum algorithms can outperform the (already very efficient) state-of-the-art classical algorithms. Their time complexity can be sublinear in the input size; in certain parameter regimes they are also optimal, whereas in others we show no quantum speedup over the classical methods is possible. Along the way, we provide improvements over the long-standing state of the art for searching for all marked elements in a list, and computing the sum of a list of numbers.We identify a new application in the context of tensor networks for quantum many-body physics. We define a computable canonical form for uniform projected entangled pair states (as the solution to a scaling problem), circumventing previously known undecidability results. We also show, by characterizing the invariant polynomials, that the canonical form is determined by evaluating the tensor network contractions on networks of bounded size

    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 fifth volume on Advances and Applications of DSmT for Information Fusion collects theoretical and applied contributions of researchers working in different fields 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 modified Proportional Conflict 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 classifiers, 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, identification of maritime vessels, fusion of support vector machines (SVM), Silx-Furtif RUST code library for information fusion including PCR rules, and network for ship classification. 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 classification, and hybrid techniques mixing deep learning with belief functions as well

    Metadynamics Calculations of Magnetic Skyrmion Stabilities

    Get PDF
    Interfacial magnetic skyrmions are topological spin textures that have been proposed for use as information carriers in spintronic devices. Hence, it is vital that their creation, annihilation, and motion can be accurately controlled. Still, their thermal stability and interactions are not fully understood. Currently, athermal methods such as the geodesic nudged elastic band method (GNEBM) are used to quantify the skyrmion creation and annihilation energy barriers, including only the skyrmion’s internal energy. Furthermore, GNEBM is a low-temperature formalism that samples only saddle points along the energy landscape without providing any information about the transition from a skyrmionic to a ferromagnetic (FM) state and vice versa. Similarly, the skyrmion lifetimes are often estimated using energy barrier calculations and an arbitrary attempt frequency. In contrast with GNEBM calculations, this thesis successfully demonstrated a novel use of metadynamics combined with atomic-scale magnetic simulations performed to reconstruct the free energy landscape (FEL) of macroscopic skyrmion observables. The reconstructed FELs are then used to quantify the skyrmions creation and annihilation energy barriers as a function of temperature, including both the effects of the internal energy and entropy, which is a major factor in skyrmion stability. The reconstructed FEL shows every possible transition path from a skyrmionic to a ferromagnetic path. Additionally, it is demonstrated that the skyrmions’ attempt frequency in finite temperature can be estimated with metadynamics and not assumed. Nonetheless, with the use of metadynamics, the effects of magnetisation reversal in thin films with DMI are explored, revealing the generation of a chiral domain that expands to reverse the magnetisation. Finally, the procedures to explore the effect of lattice defects and exploration of all possible topological spin textures in any thin film heterostructure in finite temperatures with metadynamics are reported. Ultimately, the results of this thesis demonstrate new procedures which can be used to design and realise future skyrmionic devices by identifying possible spin textures and assessing their thermal stability and lifetimes accurately while fully accounting for temperature effects

    Mating Burrows in the Fiddler Crab \u3cem\u3eLeptuca pugilator\u3c/em\u3e: How a Key Resource is Contested, Constructed, and Shared

    Get PDF
    The Atlantic sand fiddler crab, Leptuca pugilator, is found on sandy, vegetated beach across a large portion of the United States’ Atlantic and Gulf of Mexico coasts and is iconic in regions where dense populations of the species occur for its charismatic courtship, competitive, and foraging behaviors. The social dynamics of the species are complex. Reproductively active males maintain mating territories in the dangerous heat of the intertidal zone, away from their food source at the water’s edge, where they inhabit specialized mating burrows. These mating burrows are essential to successful female reproductive success, and when it is time to mate, females will move to the high intertidal to find a burrow-owning male to mate with. Males attract females with a species-specific waving display using their sexually dimorphic major claw to signal their availability. Following attraction, a female may approach a courting male and, provided the male’s burrow is of adequate quality, the two will mate within. The female will then stay below ground in the safety of the terminal chamber of the burrow throughout the oviposition and incubation process until the time comes to release her larvae. The necessity of burrow ownership in mating for males creates a high demand for territory, and males interact with one another, sometime fighting, as each mating burrow is pass down from one owner to the next. In the following pages, I address several unanswered questions concerning the nature of L. pugilator social dynamics and behavior surrounding their most important resource: the mating burrow. In Chapter II, I attempt to discern what factors differentiate territory-owning males from others who do not or cannot own territory. Chapter III is an investigation of mating burrow structure and how it changes across time and space. In Chapter IV, I address the construction of new mating burrows which is a topic that has been left largely uninvestigated at the time of this writing. Finally, Chapter V attempts to unveil the social dynamics within burrow through paternity analysis of cohabitating males and females

    LIPIcs, Volume 261, ICALP 2023, Complete Volume

    Get PDF
    LIPIcs, Volume 261, ICALP 2023, Complete Volum

    Specificity of the innate immune responses to different classes of non-tuberculous mycobacteria

    Get PDF
    Mycobacterium avium is the most common nontuberculous mycobacterium (NTM) species causing infectious disease. Here, we characterized a M. avium infection model in zebrafish larvae, and compared it to M. marinum infection, a model of tuberculosis. M. avium bacteria are efficiently phagocytosed and frequently induce granuloma-like structures in zebrafish larvae. Although macrophages can respond to both mycobacterial infections, their migration speed is faster in infections caused by M. marinum. Tlr2 is conservatively involved in most aspects of the defense against both mycobacterial infections. However, Tlr2 has a function in the migration speed of macrophages and neutrophils to infection sites with M. marinum that is not observed with M. avium. Using RNAseq analysis, we found a distinct transcriptome response in cytokine-cytokine receptor interaction for M. avium and M. marinum infection. In addition, we found differences in gene expression in metabolic pathways, phagosome formation, matrix remodeling, and apoptosis in response to these mycobacterial infections. In conclusion, we characterized a new M. avium infection model in zebrafish that can be further used in studying pathological mechanisms for NTM-caused diseases
    • …
    corecore