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Random effects meta-analysis is a widely applied methodology to synthetize research findings of studies in a specific scientific question. Besides estimating the mean effect, an important aim of the meta-analysis is to summarize the heterogeneity, i.e. the variation in the underlying effects caused by the differences in study circumstances. The prediction interval is frequently used for this purpose: a 95% prediction interval contains the true effect of a similar new study in 95% of the cases when it is constructed, or in other words, it covers 95% of the true effects distribution on average. In this article, after providing a clear mathematical background, we present an extensive simulation investigating the performance of all frequentist prediction interval methods published to date. The work focuses on the distribution of the coverage probabilities and how these distributions change depending on the amount of heterogeneity and the number of involved studies. Although the single requirement that a prediction interval has to fulfill is to keep a nominal coverage probability on average, we demonstrate why the distribution of coverages cannot be disregarded, and that for small number of studies no reliable conclusion can be drawn from the prediction interval. We argue that assessing only the mean coverage can easily lead to misunderstanding and misinterpretation. The length of the intervals and the robustness of the methods concerning non-normality of the true effects are also investigated., Comment: To be published in Research Synthesis Methods

We derive explicit solution representations for linear, dissipative, second-order Initial-Boundary Value Problems (IBVPs) with coefficients that are spatially varying, with linear, constant-coefficient, two-point boundary conditions. We accomplish this by considering the variable-coefficient problem as the limit of a constant-coefficient interface problem, previously solved using the Unified Transform Method of Fokas. Our method produces an explicit representation of the solution, allowing us to determine properties of the solution directly. As explicit examples, we demonstrate the solution procedure for different IBVPs of variations of the heat equation, and the linearized complex Ginzburg-Landau (CGL) equation (periodic boundary conditions). We can use this to find the eigenvalues of dissipative second-order linear operators (including non-self-adjoint ones) as roots of a transcendental function, and we can write their eigenfunctions explicitly in terms of the eigenvalues.

Strongly laser-driven semiconductor crystals offer substantial advantages for the study of many-body physics and ultrafast optoelectronics via the high harmonic generation process. While this phenomenon has been employed to investigate the dynamics of solids in the presence of strong laser fields, its potential to be utilized as an attosecond light source has remained unexploited. Here, we demonstrate that the high harmonics generated through the interaction of mid--infrared pulses with a ZnO crystal leads to the production of attosecond pulses, that can be used to trace the ultrafast ionization dynamics of alkali metals. In a cross--correlation approach, we photoionize Cesium atoms with the vacuum-ultraviolet (VUV) high-harmonics in the presence of a mid-infrared laser field. We observe strong oscillations of the photoelectron yield originating from the instantaneous polarization of the atoms by the laser field. The phase of the oscillations encodes the attosecond synchronization of the ionizing high-harmonics and is used for attosecond pulse metrology. This light source opens a new spectral window for attosecond spectroscopy, paving the way for studies of systems with low ionization potentials including neutral atoms, molecules and solids. Additionally, our results highlight the significance of the source for generating non--classical massively entangled light states in the visible--VUV spectral region., Comment: 9 pages (7 main text + 2 supplementary material), 4 figures

We construct irrational irreducible components of the Hilbert scheme of points of affine n-dimensional space, for n at least 12. We start with irrational components of the Hilbert scheme of curves in P^3 and use methods developed by Jelisiejew to relate these to irreducible components of the Hilbert schemes of points of A^n. The result solves Problem XX of [J. Jelisiejew, Open problems in deformations of Artinian algebras, Hilbert schemes and around, arXiv:2307.08777, 2023].

The degree of experimentally attainable nonlocality, as gauged by the amount of loophole-free violation of Bell inequalities, remains severely limited due to inefficient detectors. We address an experimentally motivated question: Which quantum strategies attain the maximal loophole-free nonlocality in the presence of inefficient detectors? For any Bell inequality and any specification of detection efficiencies, the optimal strategies are those that maximally violate a tilted version of the Bell inequality in ideal conditions. In the simplest scenario, we demonstrate that the quantum strategies that maximally violate the tilted versions of Clauser-Horne-Shimony-Holt inequality are unique up to local isometries. However, self-testing via the standard sum of squares decomposition method turns out to be analytically intractable since even high levels of the Navascu\'es--Pironio--Ac\'in hierarchy are insufficient to saturate the maximum quantum violation of these inequalities. Instead, we utilize a novel Jordan's lemma-based proof technique to obtain robust analytical self-testing statements for the entire family of tilted-Bell inequalities. These results allow us to unveil intriguing aspects of the effect of inefficient detectors and the complexity of characterizing the set of quantum correlations, in the simplest Bell scenario., Comment: First draft, comments are welcome

We consider a hierarchically structured population in which the amount of resources an individual has access to is affected by individuals that are larger, and that the intake of resources by an individual only affects directly the growth rate of the individual. We formulate a deterministic model, which takes the form of a delay equation for the population birth rate. We also formulate an individual based stochastic model, and study the relationship between the two models. In particular the stationary birth rate of the deterministic model is compared to that of the quasi-stationary birth rate of the stochastic model. Since the quasi-stationary birth rate cannot be obtained explicitly, we derive a formula to approximate it. We show that the stationary birth rate of the deterministic model can be obtained as the large population limit of the quasi-stationary birth rate of the stochastic model. This relation suggests that the deterministic model is a good approximation of the stochastic model when the number of individuals is sufficiently large., Comment: 3 figures, to appear in Journal of Applied Mathematics and Computing

We study Banach spaces induced by families of finite sets in the most natural (Schreier-like) way, that is, we consider the completion $X_\mc{F}$ of $c_{00}$ with respect to the norm $\sup\{\sum_{k\in F}|x(k)|:F\in\mc{F}\}$ where $\mc{F}$ is an arbitrary (not necessarily compact) family of finite sets covering $\mbb{N}$. Among other results, we discuss the following: (1) Structure theorems bonding the combinatorics of $\mc{F}$ and the geometry of $X_\mc{F}$ including possible characterizations and variants of the Schur property, $\ell_1$-saturation, and the lack of copies of $c_0$ in $X_\mc{F}$. (2) A plethora of examples including a relatively simple $\ell_1$-saturated combinatorial space which does not satisfy the Schur property, as well as a new presentation of Pe\l czy\'nski's universal space. (3) The complexity of the family $\{H\subseteq\NN:X_{\mc{F}\upharpoonright H}$ does not contain $c_0\}$.

Two-dimensional (2D) materials have attracted considerable attention due to their unique physicochemical properties and significant potential in energy-related applications. Polymeric carbon nitrides (PCNs) with 2D stacked architecture show promise as photocatalysts for solar-to-fuel conversion and as versatile 2D semiconductors. However, the lack of a clear definition of the exact structural model of these materials limits our fundamental understanding of their unique properties. Here, we investigate the structure-induced optical properties of PCNs through \textit{ab initio} calculations. Our study on the electronic and optical properties of PCNs highlights the significant influence of structure on their behavior, especially near band edges. The analysis reveals that the degree of condensation and corrugation influences the electron/hole localization and the energy levels of $\pi$ electrons, which are crucial for the optical behavior. In addition, the microstructures of 2D configurations lead to divergent optical properties in 3D configurations, with characteristic peaks identified at 350 nm and interlayer interactions ranging from 400 to 500 nm, depending on the specific microstructures. Through observations over 2D and 3D structures, we elucidate exciton photophysical processes in PCN materials. This highlights the substantial differences in optical properties between actual 2D and 3D structures, while also demonstrating the potential for carrier and energy transport mechanisms to occur perpendicular to the plane. Finally, our results provide deep insights into the understanding of previously hidden microstructural, electronic, and optical properties of PCNs, paving the way for further performance and property enhancements in this class of materials.

Although BiFeO$_3$ is one of the most studied multiferroic materials, recent magnetization and neutron scattering studies have revealed a new magnetic phase in this compound - the transverse conical phase. To study the collective spin excitations of this phase, we performed THz spectroscopy in magnetic fields up to 17 T at and above room temperature. We observed five spin-wave branches in the magnetic phase with long wavelength conical modulation. Using a numerical spin dynamics model we found two kinds of excitations with magnetic moments oscillating either along or perpendicular to the static fields. Remarkably, we detected strong directional dichroism, an optical manifestation of the magnetoelectric effect, for two spin-wave modes of the conical phase. According to our experiments, the stability of the conical state is sensitive to the magnetic field history and it can become (meta)stable at or close to zero magnetic field, which may allow exploiting its magnetoelectric properties at room temperature.

Experiments in materials with a compensated ordering of magnetic moments have demonstrated a potential for approaching the thermodynamic limit of the fastest and least-dissipative operation of a digital memory bit. In addition, these materials are very promising for a construction of energy-efficient analog devices with neuromorphic functionalities, which are inspired by computing-in-memory capabilities of the human brain. In this paper, we report on experimental separation of switching-related and heat-related resistance signal dynamics in memory devices microfabricated from CuMnAs antiferromagnetic metal. We show that the memory variable multilevel resistance can be used as a long-term memory (LTM), lasting up to minutes at room temperature. In addition, ultrafast reflectivity change and heat dissipation from nanoscale-thickness CuMnAs films, taking place on picosecond to hundreds of nanoseconds time scales, can be used as a short-term memory (STM). Information about input stimuli, represented by femtosecond laser pulses, can be transferred from STM to LTM after rehearsals at picosecond to nanosecond times in these memory devices, where information can be retrieved at times up to 10^15 longer than the input pulse duration. Our results open a route towards ultra-fast low-power implementations of spiking neuron and synapse functionalities using a resistive analog antiferromagnetic memory., Comment: 21 pages, 4 figures

Random access codes are a type of communication task that is widely used in quantum information science. The optimal average success probability that can be achieved through classical strategies is known for any random access code. However, only a few cases are solved exactly for quantum random access codes. In this paper, we provide bounds for the fully general setting of n independent variables, each selected from a d-dimensional classical alphabet and encoded in a D-dimensional quantum system subject to an arbitrary quantum measurement. The bound recovers the exactly known special cases, and we demonstrate numerically that even though the bound is not tight overall, it can still yield a good approximation., Comment: 9 pages, 2 figures, comments are welcome

Deterministic communication means reliable packet forwarding with close to zero packet loss and bounded latency. Packet loss or delay above a threshold caused by, e.g., equipment failure or malfunction could be catastrophic for applications that require deterministic communication. To meet loss related targets, per-packet service protection has been introduced by deterministic communications standards; it is provided by Frame Replication and Elimination for Reliability (FRER) for Layer 2 Ethernet networks and by Packet Replication, Elimination, and Ordering Functions (PREOF) for Layer 3 IP/MPLS networks. We have implemented FRER with two conceptually different methods: (1) in eBPF/XDP as a lightweight software implementation; and (2) in userspace. We evaluate our XDP FRER via an experimental analysis and compare the two FRER implementations., Comment: Paper submission for the talk with same title on netdev 0x17 conference: https://netdevconf.info/0x17/sessions/talk/lightweight-implementation-of-per-packet-service-protection-in-ebpfxdp.html

Kuiper belt objects are thought to be formed at least a few million years after the formation of calcium-aluminium-rich inclusions, at a time when the $^{26}$Al isotope -- the major source of radiogenic heat in the early Solar System -- had significantly depleted. The internal structure of these objects is highly dependent on any additional source that can produce extra heat in addition to that produced by the remaining, long-lasting radioactive isotopes. In this paper, we explore how serpentinization, the hydration of silicate minerals, can contribute to the heat budget and to what extent it can modify the internal structure of large Kuiper belt objects. We find that the extent of restructuring depends very strongly on the start time of the formation process, the size of the object, and the starting ice-to-rock ratio. Serpentinization is able to restructure most of the interior of all objects in the whole size range (400-1200\,km) and ice-to-rock ratio range investigated if the process starts early, $\sim$3\,Myr after CAI formation, potentially leading to a predominantly serpentine core much earlier than previously thought ($\leq$5\,Myr vs. several tens of million years). While the ratio of serpentinized material gradually decreases with the increasing formation time, the increasing ice-to-rock ratio, and the increasing start time of planetesimal formation in the outer solar system, in the case of the largest objects a significant part of the interior will be serpentinized even if the formation starts relatively late, $\sim$5\,Myr after CAI formation. Therefore it is feasible that the interior of planetesimals may have contained a significant amount of serpentine, and in some cases, it could have been a dominant constituent, at the time of satellite-forming impacts., Comment: Accepted for publication in the Publications of the Astronomical Society of the Pacific (PASP)

Reinforcement learning (RL) agents need to explore their environments in order to learn optimal policies. In many environments and tasks, safety is of critical importance. The widespread use of simulators offers a number of advantages, including safe exploration which will be inevitable in cases when RL systems need to be trained directly in the physical environment (e.g. in human-robot interaction). The popular Safety Gym library offers three mobile agent types that can learn goal-directed tasks while considering various safety constraints. In this paper, we extend the applicability of safe RL algorithms by creating a customized environment with Panda robotic arm where Safety Gym algorithms can be tested. We performed pilot experiments with the popular PPO algorithm comparing the baseline with the constrained version and show that the constrained version is able to learn the equally good policy while better complying with safety constraints and taking longer training time as expected., Comment: 4 pages, 2 figures. Appeared in 2023 International Conference on Artificial Neural Networks (ICANN) proceedings. Published version copyrighted by Springer. This work was funded by the Horizon Europe Twinning project TERAIS, G.A. number 101079338 and in part by the national project APVV-21-0105. Link to the code: https://zenodo.org/doi/10.5281/zenodo.10694747

Human eye gaze estimation is an important cognitive ingredient for successful human-robot interaction, enabling the robot to read and predict human behavior. We approach this problem using artificial neural networks and build a modular system estimating gaze from separately cropped eyes, taking advantage of existing well-functioning components for face detection (RetinaFace) and head pose estimation (6DRepNet). Our proposed method does not require any special hardware or infrared filters but uses a standard notebook-builtin RGB camera, as often approached with appearance-based methods. Using the MetaHuman tool, we also generated a large synthetic dataset of more than 57,000 human faces and made it publicly available. The inclusion of this dataset (with eye gaze and head pose information) on top of the standard Columbia Gaze dataset into training the model led to better accuracy with a mean average error below two degrees in eye pitch and yaw directions, which compares favourably to related methods. We also verified the feasibility of our model by its preliminary testing in real-world setting using the builtin 4K camera in NICO semi-humanoid robot's eye., Comment: 6 pages, 10 figures, accepted to 2023 IEEE Symposium Series on Computational Intelligence (SSCI). Published version copyrighted by IEEE. This work was funded by the Horizon Europe Twinning project TERAIS G.A. number 101079338, and in part by the national project APVV-21-0105. The link to the code: https://zenodo.org/doi/10.5281/zenodo.10696083

We introduce an approach to building a custom model from ready-made self-supervised models via their associating instead of training and fine-tuning. We demonstrate it with an example of a humanoid robot looking at the mirror and learning to detect the 3D pose of its own body from the image it perceives. To build our model, we first obtain features from the visual input and the postures of the robot's body via models prepared before the robot's operation. Then, we map their corresponding latent spaces by a sample-efficient robot's self-exploration at the mirror. In this way, the robot builds the solicited 3D pose detector, which quality is immediately perfect on the acquired samples instead of obtaining the quality gradually. The mapping, which employs associating the pairs of feature vectors, is then implemented in the same way as the key-value mechanism of the famous transformer models. Finally, deploying our model for imitation to a simulated robot allows us to study, tune up, and systematically evaluate its hyperparameters without the involvement of the human counterpart, advancing our previous research., Comment: This work was funded (or co-funded) by the Horizon-Widera-2021 European Twinning project TERAIS G.A. n. 101079338, 32nd International Conference on Artificial Neural Networks, Heraklion, Greece, September 26-29, 2023, citations: https://link.springer.com/chapter/10.1007/978-3-031-44207-0_39, codes: https://github.com/andylucny/learningImitation/tree/main/mirror, 12 pages, 3 figures, 0 tables

We show that the moduli space R_9 of Prym curves of genus 9 is uniruled. This is the largest genus g for which R_g has negative Kodaira dimension., Comment: 17 pages. Final version, to appear in Advances in Mathematics

Device-independent quantum key distribution allows for proving the security of a shared cryptographic key between two distant parties with potentially untrusted devices. The security proof is based on the measurement outcome statistics (correlation) of a Bell experiment, and security is guaranteed by the laws of quantum theory. While it is known that the observed correlation must be Bell non-local in order to prove security, recent results show that Bell non-locality is in general not sufficient for standard device-independent quantum key distribution. In this work, we show that conversely, there is no lower bound on the amount of non-locality that is sufficient for device-independent quantum key distribution. Even more so, we show that from certain correlations that exhibit arbitrarily small non-locality, one can still extract unbounded device-independent key rates. Therefore, a quantitative relation between device-independent key rates and Bell non-locality cannot be drawn in general. Our main technique comprises a rigorous connection between self-testing and device-independent quantum key distribution, applied to a recently discovered family of Bell inequalities with arbitrarily many measurement outcomes., Comment: some updated references

We discuss the factorization and continuity properties of fields in the Euclidean gravitational path integral with higher dimension operators constructed from powers of the Riemann tensor. We construct the boundary terms corresponding to the microcanonical ensemble and show that the saddle point approximation to the path integral with a quasilocal energy constraint generally yields a saddle point with discontinuous temperature. This extends a previous result for the Euclidean Schwarzschild-de Sitter geometry in Einstein gravity and shows that it is robust against at least some types of quantum corrections from heavy fields. As an application, we compute the entropy of SdS in $\text{D}=4$ using the BTZ method. Our result matches the entropy calculated using Wald's formula., Comment: 32 pages, 1 figure, 3 appendices

Hexapeptides are increasingly applied as model systems for studying the amyloidogenecity properties of oligo- and polypeptides. It is possible to construct 64 million different hexapeptides from the twenty proteinogenic amino acid residues. Today's experimental amyloid databases contain only a fraction of these annotated hexapeptides. For labeling all the possible hexapeptides as "amyloidogenic" or "non-amyloidogenic" there exist several computational predictors with good accuracies. It may be of interest to define and study a simple graph structure on the 64 million hexapeptides as nodes when two hexapeptides are connected by an edge if they differ by only a single residue. For example, in this graph, HIKKLM is connected to AIKKLM, or HIKKNM, or HIKKLC, but it is not connected with an edge to VVKKLM or HIKNPM. In the present contribution, we consider our previously published artificial intelligence-based tool, the Budapest Amyloid Predictor (BAP for short), and demonstrate a spectacular property of this predictor in the graph defined above. We show that for any two hexapeptides predicted to be "amyloidogenic" by the BAP predictor, there exists an easily constructible path of length at most 6 that passes through neighboring hexapeptides all predicted to be "amyloidogenic" by BAP. For example, the predicted amyloidogenic ILVWIW and FWLCYL hexapeptides can be connected through the length-6 path ILVWIW-IWVWIW-IWVCIW-IWVCIL-FWVCIL-FWLCIL-FWLCYL in such a way that the neighbors differ in exactly one residue, and all hexapeptides on the path are predicted to be amyloidogenic by BAP. The symmetric statement also holds for non-amyloidogenic hexapeptides. It is noted that the mentioned property of the Budapest Amyloid Predictor \url{https://pitgroup.org/bap} is not proprietary; it is also true for any linear Support Vector Machine (SVM)-based predictors.

Each connected graded, graded-commutative algebra $A$ of finite type over a field $\Bbbk$ of characteristic zero defines a complex of finitely generated, graded modules over a symmetric algebra, whose homology graded modules are called the (higher) Koszul modules of $A$. In this note, we investigate the geometry of the support loci of these modules, called the resonance schemes of the algebra. When $A=\Bbbk\langle \Delta \rangle$ is the exterior Stanley-Reisner algebra associated to a finite simplicial complex $\Delta$, we show that the resonance schemes are reduced. We also compute the Hilbert series of the Koszul modules and give bounds on the regularity and projective dimension of these graded modules. This leads to a relationship between resonance and Hilbert series that generalizes a known formula for the Chen ranks of a right-angled Artin group., Comment: 17 pages; accepted for publication in Journal of Algebraic Combinatorics

This paper presents a set of industrial-grade text processing models for Hungarian that achieve near state-of-the-art performance while balancing resource efficiency and accuracy. Models have been implemented in the spaCy framework, extending the HuSpaCy toolkit with several improvements to its architecture. Compared to existing NLP tools for Hungarian, all of our pipelines feature all basic text processing steps including tokenization, sentence-boundary detection, part-of-speech tagging, morphological feature tagging, lemmatization, dependency parsing and named entity recognition with high accuracy and throughput. We thoroughly evaluated the proposed enhancements, compared the pipelines with state-of-the-art tools and demonstrated the competitive performance of the new models in all text preprocessing steps. All experiments are reproducible and the pipelines are freely available under a permissive license., Comment: Submitted to TSD 2023 Conference

We demonstrate that parametrically excited eigenmodes in nearby nanomagnets can be coupled to each other. Both positive (in-phase) and negative (anti-phase) couplings can be realized by a combination of appropriately chosen geometry and excitation field frequency. The oscillations are sufficiently stable against thermal fluctuations. The phase relation between field-coupled nanomagnets shows a hysteretic behavior with the phase relation being locked over a wide frequency range. We envision that this computational study lays the groundwork to use field-coupled nanomagnets as parametrons as building blocks of logic devices, neuromorphic systems or Ising machines.

A novel original method of determination of stresses and critical resolved shear stresses (CRSSs) using neutron diffraction was proposed. In this method, based on the crystallite group method, the lattice strains were measured in different directions and using different reflections hkl during uniaxial deformation of magnesium alloy AZ31. The advantage of this method is that the stresses for groups of grains having similar orientations can be determined directly from measurement without any models used for data interpretation. The obtained results are unambiguous and do not depend on the models assumptions as in previous works. Moreover, it was possible for the first time to determine the uncertainty of the measured CRSS values and local stresses at groups of grains. The used methodology allowed for the determination of stress partitioning between grains having different orientations and for an explanation of the anisotropic mechanical behaviour of the strongly textured alloy. Finally, the CRSS values allowed for the validation of the type of intergranular interaction assumed in the elastic-plastic self-consistent model and for a significant reduction of the number of unknown parameters when the model is adjusted to the experimental data., Comment: 61 pages, 31 figures, 6 pages in Appendix, Published in Measurement

One of the most counterintuitive aspects of quantum theory is its claim that there is 'intrinsic' randomness in the physical world. Quantum information science has greatly progressed in the study of intrinsic, or secret, quantum randomness in the past decade. With much emphasis on device-independent and semi-device-independent bounds, one of the most basic questions has escaped attention: how much intrinsic randomness can be extracted from a given state $\rho$, and what measurements achieve this bound? We answer this question for three different randomness quantifiers: the conditional min-entropy, the conditional von Neumann entropy and the conditional max-entropy. For the first, we solve the min-max problem of finding the projective measurement that minimises the maximal guessing probability of an eavesdropper. The result is that one can guarantee an amount of conditional min-entropy $H^*_{\textrm{min}}=-\log_2 P_{\textrm{guess}}^{*}(\rho)$ with $P_{\textrm{guess}}^{*}(\rho)=\frac{1}{d}(\textrm{tr} \sqrt{\rho})^2$ by performing suitable projective measurements. For the conditional von Neumann entropy, we find that the maximal value is $H^{*}= \log_{2}d-S(\rho)$, with $S(\rho)$ the von Neumann entropy of $\rho$, while for the conditional max-entropy, we find the maximal value $H^{*}_\textrm{max}=\log_{2}d + \log_{2}\lambda_{\textrm{max}}(\rho)$, where $\lambda_{\textrm{max}}(\rho)$ is the largest eigenvalue of $\rho$. Optimal values for $H^{*}_{\textrm{min}}$, $H^{*}$ and $H^{*}_\textrm{max}$ are achieved by measuring in any basis that is unbiased to the eigenbasis of $\rho$, as well as by other, less intuitive, measurements.