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This paper explores the application of artificial intelligence techniques in audio and voice processing, focusing on the integration of wake words and speaker recognition for secure access in embedded systems. With the growing prevalence of voice-activated devices such as Amazon Alexa, ensuring secure and user-specific interactions has become paramount. Our study aims to enhance the security framework of these systems by leveraging wake words for initial activation and speaker recognition to validate user permissions. By incorporating these AI-driven methodologies, we propose a robust solution that restricts system usage to authorized individuals, thereby mitigating unauthorized access risks. This research delves into the algorithms and technologies underpinning wake word detection and speaker recognition, evaluates their effectiveness in real-world applications, and discusses the potential for their implementation in various embedded systems, emphasizing security and user convenience. The findings underscore the feasibility and advantages of employing these AI techniques to create secure, user-friendly voice-activated systems.

As the number of scientific publications and preprints is growing exponentially, several attempts have been made to navigate this complex and increasingly detailed landscape. These have almost exclusively taken unsupervised approaches that fail to incorporate domain knowledge and lack the structural organisation required for intuitive interactive human exploration and discovery. Especially in highly interdisciplinary fields, a deep understanding of the connectedness of research works across topics is essential for generating insights. We have developed a unique approach to data navigation that leans on geographical visualisation and uses hierarchically structured domain knowledge to enable end-users to explore knowledge spaces grounded in their desired domains of interest. This can take advantage of existing ontologies, proprietary intelligence schemata, or be directly derived from the underlying data through hierarchical topic modelling. Our approach uses natural language processing techniques to extract named entities from the underlying data and normalise them against relevant domain references and navigational structures. The knowledge is integrated by first calculating similarities between entities based on their shared extracted feature space and then by alignment to the navigational structures. The result is a knowledge graph that allows for full text and semantic graph query and structured topic driven navigation. This allows end-users to identify entities relevant to their needs and access extensive graph analytics. The user interface facilitates graphical interaction with the underlying knowledge graph and mimics a cartographic map to maximise ease of use and widen adoption. We demonstrate an exemplar project using our generalisable and scalable infrastructure for an academic biomedical literature corpus that is grounded against hundreds of different named domain entities.

We analyze the network of transactions among cities based on the electronic invoice database for the municipalities in the Cear\'a state, Brazil. It consists of approximately 3.7 billion records, registered during the period between the years 2016 to 2019. All the transactions are grouped in a unique dataset and represented as an asymmetrical adjacency matrix corresponding to a directed graph with connections weighted by the number of transactions among cities. Due to the large size of Cear\'a state, its unequal distribution of wealth, and spatially heterogeneous population, we initially determine communities of cities based on their mutual intensity of trades and verify to which extent their economic interests reflect a community cohesiveness. For the first task, we use the Infomap algorithm to detect the partition which provides the shortest description length and captures the optimal community structure of the network in terms of its associated flow dynamics. Surprisingly, the partition identified has five modules, whose two-dimensional geographical projections are all simply-connected domains. We proceed with the analysis of traded products by building bipartite structures represented in terms of adjacency matrices between municipalities and products, considering selling and buying. Using the revealed comparative advantage (RCA) concept, we define a non-monetary and binary activity index that can distinguish the RCA of a city in a class of goods or services as evidenced by trade flows. Finally, through the pairwise Maximum Entropy Model, we can associate to the largest communities their corresponding binary Ising-like Hamiltonian models. In an analogy with critical phenomena, our results reveal that each community operates at a "temperature" that is close to the corresponding "critical point", suggesting a high degree of "economic cohesiveness" in its trade network of cities., Comment: 29 pages, 10 figures

In this study we focused on the linear Kawahara equation in a bounded domain, employing two boundary controls. The controllability of this system has been previously demonstrated over the past decade using the Hilbert uniqueness method which involves proving an observability inequality, in general, demonstrated via Carleman estimates. Here, we extend this understanding by achieving the exact controllability within a space of analytic functions, employing the flatness approach which is a new approach for higher-order dispersive systems., Comment: 30 pages. Comments are welcome

In this work, we present a gravitational dual to a constriction Josephson junction constructed from the AdS/BCFT correspondence. On the gravity side, we consider a planar AdS-Schwarzschild black hole. Our junction is connected by the boundary $\partial\Omega$ with tension $\Sigma$ on the boundary CFT. This approach lead us to analytical solutions rather than usual numerical methods. Our computations on the gravity side reproduce the standard relation between the current across the junction and the phase difference of the condensate controlled by the tension $\Sigma$. We also study the maximum current's dependence on the junction's tension and size and reproduce familiar results., Comment: 17 pages, 6 figures

This work explores the holographic complexity and residual entropy of a rotating BTZ black hole within the framework of Horndeski gravity. The investigation is motivated by the need to understand the emission of information from black holes, as encoded by quantum complexity, which persists even at zero temperature. Traditionally, black holes are considered to cease emitting information upon reaching zero temperature, yet our findings suggest a minimum level of information or minimal entropy. This challenges the classical notion of black hole death. Recent studies in the context of Horndeski gravity and the AdS/BCFT correspondence have identified a non-zero minimal entropy at zero temperature. Our work shows that complexity and entropy provide crucial insights into the information emission from black holes, extending beyond their classical death. These findings significantly affect our understanding of black hole thermodynamics and quantum information theory., Comment: 21 pages, 8 figures

The Synthetic Corona Outflow Model (SynCOM), an empirical model, simulates the solar corona's dynamics to match high-resolution observations, providing a useful resource for testing velocity measurement algorithms. SynCOM generates synthetic images depicting radial variability in polarized brightness and includes stochastic elements for plasma outflows and instrumental noise. It employs a predefined flow velocity probability distribution and an adjustable signal-to-noise ratio to evaluate different data analysis methods for coronal flows. By adjusting parameters to match specific coronal and instrumental conditions, SynCOM offers a platform to assess these methods for determining coronal velocity and acceleration. Validating these measurements would help to understand solar wind origins and support missions such as the Polarimeter to Unify the Corona and Heliosphere (PUNCH). In this study, we demonstrate how SynCOM can be employed to assess the precision and performance of two different flow tracking methods. By providing a ground-truth based on observational data, we highlight the importance of SynCOM in confirming observational standards for detecting coronal flows., Comment: 18 pages, 10 figures

We revisit two evolutionary game theory models, namely the Prisoner and the Snowdrift dilemmas, on top of small-world networks. These dynamics on networked populations (individuals occupying nodes of a graph) are mainly concerning on the competition between to cooperate or to defect, by allowing some process of revision of strategies. Cooperators avoid defectors by forming clusters in a process known as network reciprocity. This defense strategy is based on the fact that any individual interact only with its nearest neighbors. The minimum cluster, in turn, is formed by a set of three completely connected nodes and the bulk of these triplets is associated with the transitivity property of a network. Particularly, we show that the transitivity increases eventually assuming a constant behavior when observed as a function of the number of contacts of an individual. We investigate the influence of the network reciprocity on that transitivity increasing regime on the promotion of a cooperative behavior. The dynamics on small-world networks are compared with those random regular, and annealed networks, the later typically studied as the well-mixed approach. We observe that the Snowdrift Game converge to an annealed scenario as randonness and coordination number increase, whereas the Prisoner's Dilemma becomes more severe against the cooperative behavior under the regime of an increasing network reciprocity., Comment: 10 pages, 7 figures

We introduce the generalized diffusive epidemic process, which is a metapopulation model for an epidemic outbreak where a non-sedentary population of walkers can jump along lattice edges with diffusion rates $D_S$ or $D_I$ if they are susceptible or infected, respectively, and recovered individuals possess permanent immunity. Individuals can be contaminated with rate $\mu_c$ if they share the same lattice node with an infected individual and recover with rate $\mu_r$, being removed from the dynamics. Therefore, the model does not have the conservation of the active particles composed of susceptible and infected individuals. The reaction-diffusion dynamics are separated into two stages: (i) Brownian diffusion, where the particles can jump to neighboring nodes, and (ii) contamination and recovery reactions. The dynamics are mapped into a growing process by activating lattice nodes with successful contaminations where activated nodes are interpreted as infection sources. In all simulations, the epidemic starts with one infected individual in a lattice filled with susceptibles. Our results indicate a phase transition in the dynamic percolation universality class controlled by the population size, irrespective of diffusion rates $D_S$ and $D_I$ and a subexponential growth of the epidemics in the percolation threshold., Comment: 8 pages, 4 figures

In this work, we investigate a spherically symmetric charged black hole in the presence of a Kalb--Ramond field background. We calculate the photon sphere and shadow radii and, corroborating our results, we constrain them from observational data from the Event Horizon Telescope (EHT), particularly focusing on the shadow images of Sagittarius $A^{*}$. Additionally, we analyze the greybody factors, emission rate, and partial absorption cross section. We also examine the topological charge and its application to the deflection angle. Finally, we conduct the analysis of the heat capacity and phase transitions., Comment: 7 pages in two column, 10 figures and 2 tables

In this work, we explore a Schwarzschild-like black hole within the framework of metric--affine bumblebee gravity. First, we investigate the behavior of the Kretschmann scalar and singularities in this modified gravity approach. Next, we introduce a newly defined time coordinate related to a stationary asymptotically flat spacetime. We also analyze the scattering effects and numerically calculate and comprehensively examine the partial and total absorption cross sections. At the high--frequency approximation, we find that the absorption cross section tends to the geodesic capture cross section. The continued fraction method is applied to investigate the quasinormal modes, and we explore the deviations of both the real and imaginary terms of the quasinormal modes from the Schwarzschild case in detail. We verify the relation between the shadow radius and the real part of the quasinormal frequencies at the eikonal limit within this modified gravity framework. Finally, we examine the energy emission rate.

Sustainability commonly refers to entities, such as individuals, companies, and institutions, having a non-detrimental (or even positive) impact on the environment, society, and the economy. With sustainability becoming a synonym of acceptable and legitimate behaviour, it is being increasingly demanded and regulated. Several frameworks and standards have been proposed to measure the sustainability impact of corporations, including United Nations' sustainable development goals and the recently introduced global sustainability reporting framework, amongst others. However, the concept of corporate sustainability is complex due to the diverse and intricate nature of firm operations (i.e. geography, size, business activities, interlinks with other stakeholders). As a result, corporate sustainability assessments are plagued by subjectivity both within data that reflect corporate sustainability efforts (i.e. corporate sustainability disclosures) and the analysts evaluating them. This subjectivity can be distilled into distinct challenges, such as incompleteness, ambiguity, unreliability and sophistication on the data dimension, as well as limited resources and potential bias on the analyst dimension. Put together, subjectivity hinders effective cost attribution to entities non-compliant with prevailing sustainability expectations, potentially rendering sustainability efforts and its associated regulations futile. To this end, we argue that Explainable Natural Language Processing (XNLP) can significantly enhance corporate sustainability analysis. Specifically, linguistic understanding algorithms (lexical, semantic, syntactic), integrated with XAI capabilities (interpretability, explainability, faithfulness), can bridge gaps in analyst resources and mitigate subjectivity problems within data.

This paper introduces a tool for verifying Python programs, which, using type annotation and front-end processing, can harness the capabilities of a bounded model-checking (BMC) pipeline. It transforms an input program into an abstract syntax tree to infer and add type information. Then, it translates Python expressions and statements into an intermediate representation. Finally, it converts this description into formulae evaluated with satisfiability modulo theories (SMT) solvers. The proposed approach was realized with the efficient SMT-based bounded model checker (ESBMC), which resulted in a tool called ESBMC-Python, the first BMC-based Python-code verifier. Experimental results, with a test suite specifically developed for this purpose, showed its effectiveness, where successful and failed tests were correctly evaluated. Moreover, it found a real problem in the Ethereum Consensus Specification.

Collisional Brownian engines have been proposed as alternatives for nonequilibrium nanoscale engines. However, most studies have focused on the simpler overdamped case, leaving the role of inertia much less explored. In this work, we introduce the idea of collisional engines to underdamped Brownian particles, where each stage is sequentially subjected to a distinct driving force. A careful comparison between the performance of underdamped and overdamped Brownian work-to-work engines has been undertaken. The results show that underdamped Brownian engines generally outperform their overdamped counterparts. A key difference is the presence of a resonant regime in underdamped engines, in which both efficiency and power output are enhanced across a broad set of parameters. Our study highlights the importance of carefully selecting dynamics and driving protocols to achieve optimal engine performance., Comment: Comments are welcome

In this study, we investigate the signatures of a non-commutative black hole solution. Initially, we calculate the thermodynamic properties of the system, including entropy, heat capacity, and Hawking radiation. For the latter quantity, we employ two distinct methods: surface gravity and the topological approach. Additionally, we examine the emission rate and remnant mass within this context. Remarkably, the lifetime of the black hole, after reaching its final state due to the evaporation process, is expressed analytically up to a grey-body factor. We estimate the lifetime for specific initial and final mass configurations. Also, we analyze the tensorial quasinormal modes using the 6th-order WKB method. Finally, we study the deflection angle, i.e., gravitational lensing, in both the weak and strong deflection limits., Comment: 27 pages, 13 figures and 4 tables

In this work, we investigate the gravitational lensing of a charged black hole (spherically symmetric) within the context of Lorentz violation triggered by an antisymmetric tensor field. Our calculations consider two different scenarios: the weak and strong deflection limits. For the weak deflection limit, we employ the Gauss-Bonnet theorem to obtain our results. In the strong deflection limit, we utilize the Tsukamoto methodology, which provides measurable outcomes such as relativistic image positions and magnifications. Applying the latter methodology, we analyze the gravitational lensing by Sagittarius $A^{*}$ and derive the related observables, which are expressed as functions of the Lorentz violation parameter. Finally, the time delay is addrressed as well., Comment: 24 pages and 6 figures

Let $\Sigma$ denote a closed surface with constant mean curvature in $\mathbb{G}^3$, a 3-dimensional Lie group equipped with a bi-invariant metric. For such surfaces, there is a harmonic Gauss map which maps values to the unit sphere within the Lie algebra of $\mathbb{G}$. We prove that the energy index of the Gauss map of $\Sigma$ is bounded below by its topological genus. We also obtain index estimates in the case of complete non compact surfaces., Comment: 11 pages

Bosonic stars represent a hypothetical exotic type of compact stellar objects that could be observed from the gravitational signal of coalescing binaries in current and future gravitational wave detectors. There are two main families of bosonic stars, which depend on the nature that governs the particles that build them: Einstein-Klein-Gordon and Proca Stars. We study the multipolar structure for both families of rotating objects, using realistic potentials with the aim of finding possible universal relations and, thus, a method that allows us to distinguish between these and other compact objects in the gravitational wave paradigm. We also show how certain relevant observables can be obtained for these hypothetical but well-motivated astrophysical objects., Comment: 23 pages, 22 figures. We made some corrections

Recently, spherical and static flat space solitons (balls) and self-gravitating, everywhere regular, asymptotically flat solitons (stars) were constructed in an Einstein-Proca-Higgs model [1], where a complex vector field gains mass by coupling to a real scalar field with a Higgs-type potential. The Proca-Higgs model serves as a UV completion of a complex Proca model with self-interactions. Here, we construct and examine the mathematical and physical properties of rotating configurations. In particular, rotation allows horizon-bearing solutions, including stationary clouds surrounding Kerr black holes and their non-linear continuation into black holes with Proca-Higgs hair., Comment: 57 pages

In this work we consider anomalous and linear holographic hard wall (HW) models for light unflavored mesons inspired by the AdS/CFT correspondence. The anomalous dimensions depend on the logarithm of the spin S of the meson state and come from a semiclassical analysis of gauge/string duality. The anomalous HW model produces very good masses and good Regge trajectories for mesons compared with PDG data. Inspired by this anomalous HW model we also propose a phenomenological modification of the dimension of the boundary operators such that the model produces asymptotic linear Regge trajectories. Both anomalous HW models considered here present mass percentage deviations of less than 3%, when compared with PDG data., Comment: Version 2: 26 pages, 4 figures (1 new), 10 tables (4 new). Text improved. Results unchanged. One appendix included with complementary chi^2 analysis. Version published in PRD

We investigate the flux intensities spanning from radio waves to $\gamma$-rays across 36 light curves of Quasar 3C 273, utilizing publicly available data collected by the Integral Science Data Centre (ISDC) database. Our analysis reveals a consistent adherence of all light curves from this quasar to $q$-Gaussian distribution. This compelling finding strongly suggests a nonextensive behavior exhibited by Quasar 3C 273. Moreover, we derive the $q$ entropic indices for these light curves, providing insights into the degree of nonextensivity, where cases with $q>1$ were primarily observed. Utilizing this index, we estimate the nonextensive entropy ($S_{q}$) and explore its correlation with the energy (in eV) and the $q$ index. Notably, we observe a tendency for the $q$ value to increase as the Tsallis entropy decreases. Remarkably, our most significant observation pertains to the relationship between the entropy $S_{q}$ and the energy of the source. We identify an anomalous behavior in entropy, particularly evident in the infrared and $\gamma$-ray wavebands., Comment: 31 pages, 5 figures and 2 tables, submitted to Physica A

We discuss the short-time behavior of the majority vote dynamics on scale-free networks at the critical threshold. We introduce a heterogeneous mean-field theory on the critical short-time behavior of the majority-vote model on scale-free networks. In addition, we also compare the heterogeneous mean-field predictions with extensive Monte Carlo simulations of the short-time dependencies of the order parameter and the susceptibility. We obtained a closed expression for the dynamical exponent $z$ and the time correlation exponent $\nu_\parallel$. Short-time scaling is compatible with a non-universal critical behavior for $5/2 < \gamma < 7/2$, and for $\gamma \geq 7/2$, we have the mean-field Ising criticality with additional logarithmic corrections for $\gamma=7/2$, in the same way as the stationary scaling., Comment: 10 pages, 3 figures, 24 references

In this work, we explore the strain and curvature effects on the electronic properties of a curved graphene structure, called the graphene wormhole. The electron dynamics is described by a massless Dirac fermion containing position--dependent Fermi velocity. In addition, the strain produces a pseudo--magnetic vector potential to the geometric coupling. For an isotropic strain tensor, the decoupled components of the spinor field exhibit a supersymmetric (SUSY) potential, depending on the centrifugal term and the external magnetic field only. In the absence of a external magnetic field, the strain yields to an exponential damped amplitude, whereas the curvature leads to a power--law damping of the wave function. The spin--curvature coupling breaks the chiral symmetry between the upper and the lower spinor component, which leads to the increasing of the wave function on either upper or lower region of the wormhole, i.e., depending on the spin number. By adding an uniform magnetic field, the effective potential exhibits an asymptotic quadratic profile and a spin--curvature barrier near the throat. As a result, the bound states (Landau levels) are confined around the wormhole throat showing an asymmetric and spin--dependent profile., Comment: 12 pages, two column, 21 figures

We investigate strategies for reaching the ultimate limit on the precision of frequency estimation when the number of probes used in each run of the experiment is fixed. That limit is set by the quantum Cram\'er-Rao bound (QCRB), which predicts that the use of maximally entangled probes enhances the estimation precision, when compared with the use of independent probes. However, the bound is only achievable if the statistical model used in the estimation remains identifiable throughout the procedure. This in turn sets different limits on the maximal sensing time used in each run of the estimation procedure, when entangled and independent probes are used. When those constraints are taken into account, one can show that, when the total number of probes and the total duration of the estimation process are counted as fixed resources, the use of entangled probes is, in fact, disadvantageous when compared with the use of independent probes. In order to counteract the limitations imposed on the sensing time by the requirement of identifiability of the statistical model, we propose a time-adaptive strategy, in which the sensing time is adequately increased at each step of the estimation process, calculate an attainable error bound for the strategy and discuss how to optimally choose its parameters in order to minimize that bound. We show that the proposed strategy leads to much better scaling of the estimation uncertainty with the total number of probes and the total sensing time than the traditional fixed-sensing-time strategy. We also show that, when the total number of probes and the total sensing time are counted as resources, independent probes and maximally entangled ones have now the same performance, in contrast to the non-adaptive strategy, where the use of independent is more advantageous than the use of maximally entangled ones., Comment: 16 pages, 7 figures

Discovering innovative methods to understand phase transitions, modify phase diagrams, and uncover novel synthesis routes poses significant and far-reaching challenges. In this study, we demonstrate the formation of nanodiamond-like sp3 carbon from few-layer graphene (FLG) stacks at room temperature and relatively low transition pressure (~7.0 GPa) due to chemical interaction with water and physical biaxial strain induced by substrate compression. By employing resonance Raman and optical absorption spectroscopies at high-pressure on FLG systems, utilizing van der Waals heterostructures (hBN/FLG) on different substrates (SiO2/Si and diamond), we originally unveiled the key role of biaxial strain. Ab initio molecular dynamics simulations corroborates the pivotal role of both water and biaxial strain in locally stabilizing sp3 carbon structures at the graphene-ice interface. This breakthrough directly enhances nanodiamond technology but also establishes biaxial strain engineering as a promising tool to explore novel phases of 2D nanomaterials.

This work establishes a series of no-go conjectures that impose rigorous constraints on the localization of bulk fields in braneworld scenarios, specifically affecting gauge and spinor fields within five-dimensional spacetimes. Our approach differs from traditional methods as it does not rely on specific equations of motion, making our results broadly applicable across various braneworld models. These no-go conditions reveal fundamental limitations in field localization, challenging the feasibility of embedding fields on the brane. For instance, our analysis demonstrates that existing models fail to achieve consistent localization for gauge and spinor fields. Additionally, one of our conditions indicates that the effective Lagrangian on the brane cannot exhibit conformal invariance.

Let $G$ be a Chevalley group over a field $\Bbbk$. Fix a maximal torus $\mathbb{T}$ in $ G $, along with opposite Borel subgroups $ B $ and $ B^-$ satisfying $ \mathbb{T} = B \cap B^-$, and denote by $ \mathbb{U} := R_u(B) $ and $ \mathbb{L} := R_u(B^-)$ their respective unipotent radicals. We prove that the multiplication map $ \mu \colon \mathbb{L} \times \mathbb{U}\times \mathbb{L} \times \mathbb{U} \longrightarrow G $ is syntomic and faithfully flat over any base field $ \Bbbk$.