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In this paper, we present a telegraph diffusion model with variable exponents for image despeckling. Moving beyond the traditional assumption of a constant exponent in the telegraph diffusion framework, we explore three distinct variable exponents for edge detection. All of these depend on the gray level of the image or its gradient. We rigorously prove the existence and uniqueness of weak solutions of our model in a functional setting and perform numerical experiments to assess how well it can despeckle noisy gray-level images. We consider both a range of natural images contaminated by varying degrees of artificial speckle noise and synthetic aperture radar (SAR) images. We finally compare our method with the nonlocal speckle removal technique and find that our model outperforms the latter at speckle elimination and edge preservation., Comment: 33 pages, 19 figures, 3 tables

The Toffoli is an important universal quantum gate, and will alongside the Clifford gates be available in future Fault-Tolerant Quantum Computing hardware. Many quantum algorithms rely on performing arbitrarily small single-qubit rotations for their function, and these rotations may also be used to construct any unitary from a limited (but universal) gate set; it is then of significant interest how to carry out such rotations. In this work, we evaluate the performance of a recently proposed single-qubit rotation algorithm using the Clifford+Toffoli gate set by implementation on both a real and simulated quantum computer. We test the algorithm under various simulated noise levels utilizing a per-qubit depolarizing error noise model, finding that the errors are seemingly explained by a binomial distribution wherein these errors change controlling ancilla measurements from $0$ into $1$. Similar observations appear to hold when conducting live runs; noise levels here make further meaningful conclusions difficult, although for the smallest possible number of ancillary controls we do note that error mitigation is helpful. Our results suggest that the algorithm will perform well under up to $1\%$ noise, under the noise model we chose. Our results also suggest the algorithm could be used as a benchmark for Quantum Processing Units, given its linear increase in total number of qubits and Toffoli gates required., Comment: 10 pages, 14 figures, 3 tables, v2: expand on benchmarking use

This booklet on Active Assisted Living (AAL) technologies has been created as part of the GoodBrother COST Action, which has run from 2020 to 2024. COST Actions are European research programs that promote collaboration across borders, uniting researchers, professionals, and institutions to address key societal challenges. GoodBrother focused on ethical and privacy concerns surrounding video and audio monitoring in care settings. The aim was to ensure that while AAL technologies help older adults and vulnerable individuals, their privacy and data protection rights remain a top priority. This booklet is designed to guide you through the role that AAL technologies play in improving the quality of life for older adults, caregivers, and people with disabilities. AAL technologies offer tools for those facing cognitive or physical challenges. They can enhance independence, assist with daily routines, and promote a safer living environment. However, the rise of these technologies also brings important questions about data protection and user autonomy. This resource is intended for a wide audience, including end users, caregivers, healthcare professionals, and policymakers. It provides practical guidance on integrating AAL technologies into care settings while safeguarding privacy and ensuring ethical use. The insights offered here aim to empower users and caregivers to make informed choices that enhance both the quality of care and respect for personal autonomy.

The streaming instability is a mechanism whereby pebble-sized particles in protoplanetary discs spontaneously come together in dense filaments, which collapse gravitationally to form planetesimals upon reaching the Roche density. The extent of the filaments along the orbital direction is nevertheless poorly characterised, due to a focus in the literature on small simulation domains where the behaviour of the streaming instability on large scales cannot be determined. We present here computer simulations of the streaming instability in boxes with side lengths up to 6.4 scale heights in the plane. This is 32 times larger than typically considered simulation domains and nearly a factor 1,000 times the volume. We show that the azimuthal extent of filaments in the non-linear state of the streaming instability is limited to approximately one gas scale height. The streaming instability will therefore not transform the pebble density field into axisymmetric rings; rather the non-linear state of the streaming instability appears as a complex structure of loosely connected filaments. Including the self-gravity of the pebbles, our simulations form up to 4,000 planetesimals. This allows us to probe the high-mass end of the initial mass function of planetesimals with much higher statistical confidence than previously. We find that this end is well-described by a steep exponential tapering. Since the resolution of our simulations is moderate -- a necessary trade-off given the large domains -- the mass distribution is incomplete at the low-mass end. When putting comparatively less weight on the numbers at low masses, at intermediate masses we nevertheless reproduce the power-law shape of the distribution established in previous studies., Comment: 15 pages, 14 figures, 2 tables; accepted for publication in A&A

Context. Simulating solar flares, which involve large-scale dynamics and small-scale magnetic reconnection, poses significant computational challenges. Aims. This study aims to develop an explicit Particle-In-Cell (PIC) solver within the DISPATCH framework to model the small-scale kinetic processes in solar corona setting. This study in the first in a series with the ultimate goal to develop a hybrid PIC-MHD solver, to simulate solar flares. Methods. The PIC solver, inspired by the PhotonPlasma code, solves the Vlasov-Maxwell equations in a collisionless regime using explicit time-staggering and spatial-staggering techniques. Validation included unit tests, plasma frequency recovery, two-stream instability, and current sheet dynamics. Results. Validation tests confirmed the solver's accuracy and robustness in modeling plasma dynamics and electromagnetic fields. Conclusions. The integration of the explicit PIC solver into the DISPATCH framework is the first step towards bridging the gap between large and small scale dynamics, providing a robust platform for future solar physics research., Comment: 12 pages, 13 figures

Recursive Fourier Sampling (RFS) is one of the earliest problems demonstrating a quantum advantage, and is known to lie outside the Merlin-Arthur complexity class. This paper contains a description of the phenomenon of phase kickback and its use in RFS, and how and why this is the enabling quantum computational property for the quantum advantage in RFS. Most importantly, describing the computational process of quantum computation in the terminology of phase kickback gives a much better understanding of why uncomputation is necessary when solving RFS, pointing to the underlying reason for the limitations of the quantum advantage., Comment: 6 pages, 1 figure

In the period between 2009 and 2015, several very high-energy (VHE $> 100$ GeV) gamma-ray flaring events from the BL Lac object PKS 1424+240 were observed by the Cerenkov telescopes VERITAS and MAGIC. It had uncertain redshift ($z$) and using spectroscopical measurement, Paiano et al. (2017) found it to be $z=0.604$. Using four different extragalactic background light (EBL) models and the photohadronic model, nine independently observed VHE gamma-ray spectra of PKS 1424+240 are analyzed and a global $\chi^2$ fit is performed on all observations to estimate the best-fit value for the redshift for each EBL model. Confidence levels (CL) intervals for the redshift are also estimated using all the EBL models. This method is tested by comparing our analysis with the observed value. It is shown that the photohadronic scenario provides an excellent description of all the observed spectra. It is found that the EBL model of Dom\'inguez et al. (2011) is the one that provides the most restrictive limits on the redshift of PKS 1424+240, but in our analysis, $z=0.604$ lies within the $3\sigma$ CL interval of the EBL model of Saldana-Lopez et al. (2021)., Comment: 8 pages, 2 figures. To be published in MNRAS

Computation of a grid of self consistent 1D model atmospheres of cool stars, sub-stellar objects and exoplanets in the effective temperature range 300K to 3000K, including cloud formation, chemical non-equilibrium effects, and stellar irradiation. The models are called MSG, because they are based on an iterative coupling between three well tested codes, the MARCS stellar atmosphere code, the StaticWeather cloud formation code and the GGchem chemical equilibrium code. It includes up-to-date molecular and atomic opacities, cloud formation and advanced chemical equilibrium calculations, and involves new numerical methods at low temperatures to allow robust convergence. The coupling between the MARCS radiative transfer and GGchem chemical equilibrium computations has made it possibly effectively to reach convergence based on electron pressure for the warmer models and gas pressure for the cooler models, enabling self-consistent modelling of stellar, sub-stellar and exoplanetary objects in a very wide range of effective temperatures. Here we describe the basic details of the models, with illustrative examples of cloudy and irradiated models as well as models based on non-equilibrium chemistry. The qualitative changes in the relative abundances of TiO, H2O, CH4, NH3, and other molecules in our models follow the observationally defined M, L, T (and Y) sequences, but reveal more complex and depth dependent abundance changes, and therefore a spectral classification depending on more parameters. The self consistent coupling to Static-Weather cloud computations, allows detailed comparison between nucleation and observed relative dimming of different spectral bands, with advanced applications for new identification methods of potential exoplanetary biology.

Interconnect resistance and reliability have emerged as critical factors limiting the performance of advanced CMOS circuits. With the slowdown of transistor scaling, interconnect scaling has become the primary driver of continued circuit miniaturization. The associated scaling challenges for interconnects are expected to further intensify in future CMOS technology nodes. As interconnect dimensions approach the 10 nm scale, the limitations of conventional Cu dual-damascene metallization are becoming increasingly difficult to overcome, spurring over a decade of focused research into alternative metallization schemes. The selection of alternative metals is a highly complex process, requiring consideration of multiple criteria, including resistivity at reduced dimensions, reliability, thermal performance, process technology readiness, and sustainability. This tutorial introduces the fundamental criteria for benchmarking and selecting alternative metals and reviews the current state of the art in this field. It covers materials nearing adoption in high-volume manufacturing, materials currently under active research, and potential future directions for fundamental study. While early alternatives to Cu metallization have recently been introduced in commercial CMOS devices, the search for the optimal interconnect metal remains ongoing., Comment: 74 pages, 27 figures, 5 Tables

Quantum machine learning aims to use quantum computers to enhance machine learning, but it is often limited by the required number of samples due to quantum noise and statistical limits on expectation value estimates. While efforts are made to reduce quantum noise, less attention is given to boosting the confidence of Variational Quantum Classifiers (VQCs) and reducing their sampling needs. This paper focuses on multiclass classification, introducing a parameter-free post-processing technique that treats circuit outputs as edges of an n-dimensional simplex, representing independent binary decisions between each pair of classes. We prove and show in our experiments that this method improves few-sample accuracy by a factor of two by disentangling the wire outputs and compelling the VQC to avoid uncertain outputs. We describe this method and provide comparisons of accuracy, confidence, and entanglement, advocating for few-sample accuracy as a primary goal for effective VQCs., Comment: 10 pages, 4 figures, 3 tables

Context. While Class II stars have already accreted most of their mass, the continued inflow of fresh material via Bondi-Hoyle accretion acts as an additional mass reservoir for their circumstellar disks. This may explain the observed accretion rates of pre-main- sequence (PMS) stars, as well as observational inconsistencies in the mass and angular momentum balance of their disks. Aims. Using a new simulation that reproduces the stellar IMF, we want to quantify the role of Bondi-Hoyle accretion in the formation of Class II disks, as well address the prospect of its observational detection with the James Webb Space Telescope (JWST). Methods. We study the mass and angular momentum of the accreting gas using passively-advected tracer particles in the simulation, and we carry out radiative transfer calculations of near-infrared scattering to generate synthetic JWST observations of Bondi-Hoyle trails of PMS stars. Results. Gas accreting on Class II PMS stars approximately 1 Myr after their formation has enough mass and angular momentum to strongly affect the evolution of the preexisting disks. The accreted angular momentum is large enough to also explain the observed size of Class II disks. The orientation of the angular momentum vector can differ significantly from that of the previously accreted gas, which may result in a significant disk warping or misalignment. We also predict that JWST observations of Class II stars will be able to detect Bondi-Hoyle trails with a 90% success rate with only 2 min exposure time, if stars with accretion rates \dot{M} > 5e-10 Msol/yr and luminosity of L > 0.5 Lsol are selected., Comment: 12 pages, 16 figures, submitted to A&A

Large-scale stellar surveys, such as SDSS-V, 4MOST, WEAVE, and PLATO, require accurate atmospheric models and synthetic spectra of stars for accurate analyses of fundamental stellar parameters and chemical abundances. The primary goal of our work is to develop a new approach to solve radiation-hydrodynamics (RHD) and generate model stellar spectra in a self-consistent and highly efficient framework. We build upon the Copenhagen legacy RHD code, the MULTI3D non-local thermodynamic equilibrium (NLTE) code, and the DISPATCH high-performance framework. The new approach allows us to calculate 3D RHD models of stellar atmospheres on timescales of a few thousand CPU hours and to perform subsequent spectrum synthesis in local thermodynamic equilibrium (LTE) or NLTE for the desired physical conditions within the parameter space of FGK-type stars. We compare the 3D RHD solar model with other available models and validate its performance against solar observations, including the centre-to-limb variation of intensities and key solar diagnostic lines of H and Fe. We show that the performance of the new code allows to overcome the main bottleneck in 3D NLTE spectroscopy and enables calculations of multi-dimensional grids of synthetic stellar observables for comparison with modern astronomical observations., Comment: Accepted by A&A. 20 pages, 16 figures

We describe the Stagger Code for simulations of magneto-hydrodynamic (MHD) systems. This is a modular code with a variety of physics modules that will let the user run simulations of deep stellar atmospheres, sunspot formation, stellar chromospheres and coronae, proto-stellar disks, star formation from giant molecular clouds and even galaxy formation. The Stagger Code is efficiently and highly parallelizable, enabling such simulations with large ranges of both spatial and temporal scales. We, describe the methodology of the code, and present the most important of the physics modules, as well as its input and output variables. We show results of a number of standard MHD tests to enable comparison with other, similar codes. In addition, we provide an overview of tests that have been carried out against solar observations, ranging from spectral line shapes, spectral flux distribution, limb darkening, intensity and velocity distributions of granulation, to seismic power-spectra and the excitation of p modes. The Stagger Code has proven to be a high fidelity code with a large range of uses., Comment: accepted for the Astrophysical Journal

We propose a direct (non-recursive) algorithm for applying a rotation $R_{\theta^\ast}$, $\epsilon$-close to a desired rotation $R_\theta$, to a single qubit using the Clifford+Toffoli gate set. Our algorithm does not rely on repeatedly applying a fixed rotation, but immediately applies $R_{\theta^\ast}$. It succeeds with probability strictly greater than $1/2$, has an expected number of repetitions strictly less than 2, expected Toffoli count logarithmic in $\tfrac{1}{\epsilon}$, and expected gate depth also logarithmic in $\tfrac{1}{\epsilon}$., Comment: 6 pages, 3 figures, v4: close to published version

One of the most explored MXenes is the Ti3C2Tx, where Tx is designated to inherently formed termination species. Among many applications, Ti3C2Tx is an excellent material for energy storage, energy converting, and CO2-capturing devices. However, active sites for adsorption and surface reactions on the Ti3C2Tx-surface are still open questions to explore, which have implications for preparation methods when to obtain correct and optimized surface requirements. Here we use X-ray photoelectron spectroscopy to study adsorption of common gas molecules such as H2, CO2, and H2O, which all might be present in energy storage, energy converting, and CO2-capturing devices based on 2D flakes of Ti3C2Tx. The study shows that H2O, with a strong bonding to the Ti-Ti bridge-sites, can be considered as a termination species. An H2O terminated Ti3C2Tx-surface restricts the CO2 adsorption to the Ti on-top sites and reduces the ability to store positive ions, such as Li+ and Na+. On the other hand, an H2O terminated Ti3C2Tx-surface shows the capability to split water. The study further shows that H2 has the ability to remove F at moderate temperatures. The results from this study have implications for correct selection of MXene preparations and the environment around the MXene in different implementations., Comment: 31 pages, 16 figures and 1 table

At the 3 GeV ring of the MAX IV Laboratory, a fourth generation ring-based synchrotron light source, an asymmetric influence of the sign of the amplitude-dependent tune shift (ADTS) on the transverse mode-coupling instability (TMCI) has been observed. Measurements of the instability, in dedicated single-bunch experiments at low chromaticity, revealed a significant dependence of the dynamics of the instability above threshold on the sign of the ADTS. While for a negative sign of the ADTS the crossing of the instability does not lead to a loss of beam current, a positive sign results in the loss of 40% or more of the beam current at the threshold. In order to investigate the observed asymmetry, systematic measurement of beam dynamics above the threshold have been conducted in combination with particle tracking simulations with mbtrack2 and theoretical calculations of the Landau damping due to the ADTS. The findings point towards an influence of the Landau damping in combination with the low synchrotron frequency, which indicates that this effect could become relevant in future low-emittance electron storage rings., Comment: 13 pages, 15 figures

In response to aggressive scaling demands in semiconductor manufacturing and the growing need to apply sustainable practices, this paper presents a holistic sustainability assessment framework for evaluating alternative metals for advanced applications. The framework, consisting of seven sustainability aspects, aims to guide researchers and industry stakeholders towards decisions fostering a more sustainable and secure future for microelectronics. This study applies the framework to assess the sustainability of alternative local interconnect metals. The framework identifies five metals (Ti, Al, Ni, Co, and Mo) with relatively favourable performance in at least six out of nine specific indicators, while others (Pt, Ru, Ir, Rh, and Pd) exhibit poorer sustainability metrics. The study recommends further analyses, suggesting the incorporation of case-specific functional units and the use of normalization and weighting factors for a comprehensive evaluation. Coupled with traditional technological assessments, this framework equips decision-makers with essential tools to broaden criteria for selecting alternative metals, aligning semiconductor manufacturing with broader sustainability objectives., Comment: 20 pages, 5 Figures, 5 Tables, 12 equations

There is growing interest in the development of a muon collider that would make it possible to produce lepton collisions at energies of several TeV. Among others, there can be significant contributions to electroweak gauge boson, Higgs boson and top quark physics. In this work we pay attention to the latter, in particular, effective flavor-changing top-quark interactions. We discuss two flavor changing $t \bar q$ ($q=u,c$) production processes that can be a good probe of the dimension-six top quark and gauge boson operators in the SMEFT. We consider all nine operators that can generate flavor-changing top quak couplings. After comparing with the current LHC limits, we identify two of them that have the highest sensitivity. On the other hand, for two others the sensitivity is so low that they can be safely discarded from future studies., Comment: 18 pages

The field of Quantum Machine Learning (QML) has emerged recently in the hopes of finding new machine learning protocols or exponential speedups for classical ones. Apart from problems with vanishing gradients and efficient encoding methods, these speedups are hard to find because the sampling nature of quantum computers promotes either simulating computations classically or running them many times on quantum computers in order to use approximate expectation values in gradient calculations. In this paper, we make a case for setting high single-sample accuracy as a primary goal. We discuss the statistical theory which enables highly accurate and precise sample inference, and propose a method of reversed training towards this end. We show the effectiveness of this training method by assessing several effective variational quantum circuits (VQCs), trained in both the standard and reversed directions, on random binary subsets of the MNIST and MNIST Fashion datasets, on which our method provides an increase of $10-15\%$ in single-sample inference accuracy., Comment: 9 pages, 5 figures

Plant-frugivore interactions play a central role for plant persistence and spatial distribution by promoting the long-range dispersal of seeds by frugivores. However, plant-frugivore interactions are increasingly being threatened by anthropogenic activities. An important anthropogenic threat that could expose plant-frugivore systems to extinction risk is fruit harvesting. Here, we develop an individual-based and a pair-approximation model of plant-frugivore-human interactions to elucidate the effects of human harvesting of fruits on plant establishment, persistence, and spatial distribution. Our results show that frugivores strongly affect global density of plants and gradually shift their spatial distribution from aggregated to random, depending on the attack rate and dispersal efficiency of frugivores. We find that, in the absence of frugivores, plants experiencing intense fruit harvesting cannot persist even if their fecundity is high. In the presence of frugivores, fruit harvesting profoundly affects the global dispersal of seeds and thus changes the spatial distributions of plants from random to aggregated, potentially causing plant extinction. Our results demonstrate that sufficiently efficient frugivores mitigate the negative impact of fruit harvesting on plant populations and enable plant establishment precluded by harvesting. Taken together, these results draw attention to previously underappreciated impacts of fruit harvesting in plant-frugivore-human interactions.

A potential application of two-dimensional (2D) MXenes, such as Ti2CTx and Ti3C2Tx, is energy storage devices, such as supercapacitors, batteries, and hydride electrochemical cells, where intercalation of ions between the 2D layers is considered as a charge carrier. Electrochemical cycling investigations in combination with Ti 1s X-ray absorption spectroscopy (XAS) have therefore been performed with the objective to study oxidation state changes during potential variations. In some of these studies Ti3C2Tx has shown main edge shifts in the Ti 1s X-ray absorption near-edge structure (XANES). Here we show that these main edge shifts originate from the Ti 4p orbital involvement in the bonding between the surface Ti and the termination species at the fcc-sites. The study further shows that the t2g-eg crystal field splitting (10Dq) observed in the pre-edge absorption region indicate weaker Ti-C bonds in Ti2CTx and Ti3C2Tx compared to TiC and the corresponding MAX phases. The results from this study provide information necessary for improved electronic modeling and subsequently a better description of the materials properties of the MXenes. In general, potential applications, where surface interactions with intercalation elements are important processes, will benefit from the new knowledge presented., Comment: 7 figures, 1 table

In high performance systems it is sometimes hard to build very large graphs that are efficient both with respect to memory and compute. This paper proposes a data structure called Markov-chain-priority-queue (MCPrioQ), which is a lock-free sparse markov-chain that enables online and continuous learning with time-complexity of $O(1)$ for updates and $O(CDF^{-1}(t))$ inference. MCPrioQ is especially suitable for recommender-systems for lookups of $n$-items in descending probability order. The concurrent updates are achieved using hash-tables and atomic instructions and the lookups are achieved through a novel priority-queue which allows for approximately correct results even during concurrent updates. The approximatly correct and lock-free property is maintained by a read-copy-update scheme, but where the semantics have been slightly updated to allow for swap of elements rather than the traditional pop-insert scheme.