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We present LLM-KT, a flexible framework designed to enhance collaborative filtering (CF) models by seamlessly integrating LLM (Large Language Model)-generated features. Unlike existing methods that rely on passing LLM-generated features as direct inputs, our framework injects these features into an intermediate layer of any CF model, allowing the model to reconstruct and leverage the embeddings internally. This model-agnostic approach works with a wide range of CF models without requiring architectural changes, making it adaptable to various recommendation scenarios. Our framework is built for easy integration and modification, providing researchers and developers with a powerful tool for extending CF model capabilities through efficient knowledge transfer. We demonstrate its effectiveness through experiments on the MovieLens and Amazon datasets, where it consistently improves baseline CF models. Experimental studies showed that LLM-KT is competitive with the state-of-the-art methods in context-aware settings but can be applied to a broader range of CF models than current approaches., Comment: accepted at ICDM 2024 (demo track)

The yields of the inverse beta decay events produced by antineutrinos from a certain nuclear reactor fuel component are used by many experiments to check various model predictions. Yet measurements of the absolute yields feature significant uncertainties coming, mainly, from the understanding of the antineutrino detection efficiency. This work presents a simple novel approach to directly determine the $^{235}$U to $^{239}$Pu inverse beta decay yield ratio using the fuel evolution analysis. This ratio can be used for a sensitive test of reactor models, while the proposed method, results in smaller systematic uncertainties., Comment: 5 pages, 2 figures

Electron antineutrinos are emitted in the decay chains of the fission products inside a reactor core and could be used for remote monitoring of nuclear reactors. The DANSS detector is placed under the core of the 3.1 GW power reactor at the Kalinin Nuclear Power Plant (KNPP) and collects up to 5000 antineutrino events per day. DANSS measured changes of the reactor power by antineutrino counting rates over 7 years with 1.0% accuracy in one week periods. The systematic uncertainty of this measurement is less than 0.8%. It is comparable to the accuracy of conventional methods of the reactor power measurements while it is based on completely different approach. For the first time the 239Pu and 235U fission fractions were reconstructed using antineutrino inverse beta-decay spectrum which is a completely new technique. This method was applied to the data from three reactor fuel campaigns (approximately 1.5 year each). The reconstructed fission fractions in about one week measurements and the fission fractions provided by KNPP coincide within about 3% accuracy. This provides confidence in both completely different approaches of the fission fraction determination.

Attosecond photoelectron interferometry based on the combination of an attosecond pulse train and a synchronized infrared field is a fundamental technique for the temporal characterization of attosecond waveforms and for the investigation of electron dynamics in the photoionization process. In this approach, the comb of extreme ultraviolet harmonics typically lies above the ionization threshold of the target under investigation, thus releasing a photoelectron by single-photon absorption. The interaction of the outgoing photoelectron with the infrared pulse results in the absorption or emission of infrared photons, thereby creating additional peaks in the photoelectron spectrum, referred to as sidebands. While, in the absence of resonances in the first ionization step, the phases imparted on the photoionization process evolve smoothly with the photon energy, the presence of intermediate resonances imprints a large additional phase on the outgoing photoelectron wave packet. In this work, using a comb of harmonics below and above the ionization threshold of neon, we investigate the effect of intermediate bound excited states on attosecond photoelectron interferometry. We show that the phase of the oscillations of the sidebands and their angular distributions are strongly affected by such resonances. By slightly tuning the photon energies of the extreme ultraviolet harmonics, we show how the contributions of selected resonances can be enhanced or suppressed., Comment: 10 pages, 8 figures

Nambu-determinant brackets on $R^d\ni x=(x^1,...,x^d)$, $\{f,g\}_d(x)=\rho(x) \det(\partial(f,g,a_1,...,a_{d-2})/\partial(x^1,...,x^d))$, with $a_i\in C^\infty(R^d)$ and $\rho\partial_x\in\mathfrak{X}^d(R^d)$, are a class of Poisson structures with (non)linear coefficients, e.g., polynomials of arbitrarily high degree. With good cocycles in the graph complex, Kontsevich associated universal -- for all Poisson bivectors $P$ on affine $R^d_{aff}$ -- elements $\dot{P}=Q^\gamma(P)\in H^2_{P}(R^d_{aff})$ in the Lichnerowicz-Poisson second cohomology groups; we note that known graph cocycles $\gamma$ preserve the Nambu-Poisson class $\{P(\rho,a)\}$, and we express, directly from $\gamma$, the evolution $\dot{\rho}$,$\dot{a}$ that induces $\dot{P}$. Over all $d\geq2$ at once, there is no universal mechanism for the bivector cocycles $Q^\gamma_d$ to be trivial, $Q^\gamma_d=[\![P,\vec{X}^\gamma_d(P)]\!]$, w.r.t. vector fields defined uniformly for all dimensions $d$ by the same graph formula. While over $R^2$, the graph flows $\dot{P} = Q^{\gamma_i}_{2D}(P(\rho))$ for $\gamma\in\{\gamma_3,\gamma_5,\gamma_7,...\}$ are trivialized by vector fields $\vec{X}^{\gamma_i}_{2D}=(dx\wedge dy)^{-1}d_{dR}(Ham^{\gamma_i}(P))$ of peculiar shape, we detect that in $d\geq3$, the 1-vectors from 2D, now with $P(\rho,a_1,...,a_{d-2})$ inside, do not solve the problems $Q^{\gamma_i}_{d\geq3}=[\![P,{\vec{X}^{\gamma_i}_{d\geq3}}(P(\rho,a))]\!]$, yet they do yield good Ansatz where we find solutions $\vec{X}^{\gamma_i}_{d=3,4}(P(\rho,a))$. In the study of the step $d\mapsto d+1$, by adapting the Kontsevich graph calculus to the Nambu-Poisson class of brackets, we discover more identities for the Jacobian determinants within $P(\rho,a)$, i.e. for multivector-valued $GL(d)$-invariants on $R^d_{aff}$., Comment: Plenary talk given by AVK at the international conference on Integrable Systems and Quantum Symmetries (ISQS28) held on 1-5 July 2024 at CVUT Prague, Czech Republic; 13 pages, 1 table; followed by papers II. (arXiv:2409.12555 [math.QA]) and III. (arXiv:2409.15932 [math.QA]) by the same authors

Kontsevich constructed a map between `good' graph cocycles $\gamma$ and infinitesimal deformations of Poisson bivectors on affine manifolds, that is, Poisson cocycles in the second Lichnerowicz--Poisson cohomology. For the tetrahedral graph cocycle $\gamma_3$ and for the class of Nambu-determinant Poisson bivectors $P$ over $\mathbb{R}^2$, $\mathbb{R}^3$ and $\mathbb{R}^4$, we know the fact of trivialization, $\dot{P}=[[ P, \vec{X}^{\gamma_3}_{\text{dim}}]]$, by using dimension-dependent vector fields $\vec{X}^{\gamma_3}_{\text{dim}}$ expressed by Kontsevich (micro-) graphs. We establish that these trivializing vector fields $\vec{X}^{\gamma_3}_{\text{dim}}$ are unique modulo Hamiltonian vector fields $\vec{X}_{H}=d_P(H)= [[ P, H]]$, where $d_P$ is the Lichnerowicz--Poisson differential and where the Hamiltonians $H$ are also represented by Kontsevich (micro-)graphs. However, we find that the choice of Kontsevich (micro-)graphs to represent the aforementioned multivectors is not unique.

Kontsevich constructed a map from suitable cocycles in the graph complex to infinitesimal deformations of Poisson bi-vector fields. Under the deformations, the bi-vector fields remain Poisson. We ask, are these deformations trivial, meaning, do they amount to a change of coordinates along a vector field? We examine this question for the tetrahedron, the smallest nontrivial suitable graph cocycle in the Kontsevich graph complex, and for the class of Nambu--Poisson brackets on $\mathbb{R}^d$. Within Kontsevich's graph calculus, we use dimension-specific micro-graphs, in which each vertex represents an ingredient of the Nambu--Poisson bracket. For the tetrahedron, Kontsevich knew that the deformation is trivial for $d = 2$ (1996). In 2020, Buring and the third author found that the deformation is trivial for $d = 3$. Building on these discoveries, we now establish that the deformation is trivial for $d = 4$.

The loss landscape of neural networks is a critical aspect of their training, and understanding its properties is essential for improving their performance. In this paper, we investigate how the loss surface changes when the sample size increases, a previously unexplored issue. We theoretically analyze the convergence of the loss landscape in a fully connected neural network and derive upper bounds for the difference in loss function values when adding a new object to the sample. Our empirical study confirms these results on various datasets, demonstrating the convergence of the loss function surface for image classification tasks. Our findings provide insights into the local geometry of neural loss landscapes and have implications for the development of sample size determination techniques.

In the present paper, it is shown how the columnar/layered CoLaNET spiking neural network (SNN) architecture can be used in supervised learning image classification tasks. Image pixel brightness is coded by the spike count during image presentation period. Image class label is indicated by activity of special SNN input nodes (one node per class). The CoLaNET classification accuracy is evaluated on the MNIST benchmark. It is demonstrated that CoLaNET is almost as accurate as the most advanced machine learning algorithms (not using convolutional approach)., Comment: arXiv admin note: substantial text overlap with arXiv:2409.01230

In the present paper, I describe a spiking neural network (SNN) architecture which, can be used in wide range of supervised learning classification tasks. It is assumed, that all participating signals (the classified object description, correct class label and SNN decision) have spiking nature. The distinctive feature of this architecture is a combination of prototypical network structures corresponding to different classes and significantly distinctive instances of one class (=columns) and functionally differing populations of neurons inside columns (=layers). The other distinctive feature is a novel combination of anti-Hebbian and dopamine-modulated plasticity. The plasticity rules are local and do not use the backpropagation principle. Besides that, as in my previous studies, I was guided by the requirement that the all neuron/plasticity models should be easily implemented on modern neurochips. I illustrate the high performance of my network on a task related to model-based reinforcement learning, namely, evaluation of proximity of an external world state to the target state.

We investigate Lorentz invariance breaking in quantum wires due to Rashba spin-orbit interaction and transverse phonons. Using bosonization, we derive an effective action coupling electronic and mechanical degrees of freedom. Stikingly, at a quantum phase transition between straight and bent wire states, we find a gapped phonon mode and a gapless mode with quadratic dispersion, signaling the breaking of Lorentz invariance. We explore stability conditions for general potentials and propose nano-mechanical back-action as a sensitive tool for detecting this transition, with implications for Sliding Luttinger Liquids and dimensional crossover studies., Comment: 6 pages, 5 figures

This paper demonstrates the efficacy of a modified U-Net structure for the extraction of vascular tree masks for human fundus photographs. On limited compute resources and training data, the proposed model only slightly underperforms when compared to state of the art methods., Comment: 8 pages

We study penetration of interstellar cosmic rays (CRs) into molecular clouds surrounded by nonuniform diffuse envelopes. The present work generalizes our earlier model of CR self-modulation (Ivlev et al. 2018, Dogiel et al. 2018), in which the value for the envelope's gas density where CRs excite MHD waves was treated as a free parameter. Now, we investigate the case where the density monotonically increases toward the center. Assuming that CRs are relativistic, we obtain a universal analytical solution which does not depend on the particular shape of gas distribution in the envelope, and self-consistently derive boundaries of the diffusion zone formed within the envelope, where CRs are scattered at the self-excited waves. The values of the gas density at the boundaries are found to be substantially smaller than those assumed in the earlier model, which leads to a significantly stronger modulation of penetrating CRs. We compute the impact of CR self-modulation on the gamma-ray emission, and show that the results of our theoretical model are in excellent agreement with recent observations of nearby giant molecular clouds by Yang et al. (2023)., Comment: 11 pages, 4 figures, accepted to PRD

We consider the decentralized minimization of a separable objective $\sum_{i=1}^{n} f_i(x_i)$, where the variables are coupled through an affine constraint $\sum_{i=1}^n\left(\mathbf{A}_i x_i - b_i\right) = 0$. We assume that the functions $f_i$, matrices $\mathbf{A}_i$, and vectors $b_i$ are stored locally by the nodes of a computational network, and that the functions $f_i$ are smooth and strongly convex. This problem has significant applications in resource allocation and systems control and can also arise in distributed machine learning. We propose lower complexity bounds for decentralized optimization problems with coupled constraints and a first-order algorithm achieving the lower bounds. To the best of our knowledge, our method is also the first linearly convergent first-order decentralized algorithm for problems with general affine coupled constraints.

(abridged) The Atacama Large Aperture Submillimeter Telescope (AtLAST) is undergoing a design study for a large (50 meter) single-dish submm-wavelength Ritchey-Chr\'etien telescope to be located 5050 meters above sea level in the Atacama Desert in northern Chile. It will allow for observations covering 30 to 950 GHz. Observing at such high frequencies with a 50~m primary mirror will be challenging, and has never been attempted thus far. This observational capability demands exquisite control of systematics to ensure a reliable beam shape, and to mitigate the expected sidelobe levels. Among them, critical issues that large telescopes like AtLAST need to deal with are introduced by the panel gap pattern, the secondary mirror supporting struts, mirror deformations produced by thermal and gravitational effects, and Ruze scattering due to surface roughness. Proprietary software such as TICRA-Tools allows for full-wave, complex-field physical optics simulations taking into account these features. Such calculations can be computationally expensive since the mirror surfaces are gridded (meshed) into a fine array in which each element is treated as a current source. If the telescope size is large and the wavelengths are short this may lead to very long running times. Here we present a set of physical optics results that allow us to estimate the performance of the telescope in terms of beam shape, directivity, sidelobes level and stray light. We also discuss how we addressed the computational challenges, and provide caveats on how to shorten the run times. Above all, we conclude that the scattering effects from the gaps and tertiary support structure are minimal, and subdominant to the Ruze scattering., Comment: Submitted to SPIE Proceedings

Recent results on short-lived hadronic resonances obtained with the ALICE detector at LHC energies are presented. These results include system-size and collision-energy evolution of transverse momentum spectra, yields and the ratios of resonance yields to those of longer-lived particles, and nuclear modification factors. Results will be compared with model predictions., Comment: 8 pages, 8 figures, 1 table, Talk at RAS24, Dubna, Russia, April 1-5, 2024. submitted to Phys. Part. Nucl

The Atacama Large Aperture Submm Telescope (AtLAST) is a concept for a novel 50-meter class single-dish telescope operating at sub-millimeter and millimeter wavelengths (30-950 GHz). The telescope will provide an unprecedentedly wide field of view (FoV) of 1-2 degree diameter with a large receiver cabin housing six major instruments in Nasmyth and Cassegrain positions. The high observing frequencies, combined with the scanning operation movements with up to 3 deg/second, place high demands on the accuracy and stability of the optical and structural components. The design features the introduction of a rocking chair type mount with an iso-statically decoupled main reflector backup structure and an active main reflector surface with a high precision metrology system. The planned site location is in the Chilean Atacama Desert at approximately 5050 meters above sea level, near Llano de Chajnantor. This paper gives an overview of the optical, structural, and mechanical design concepts. It explains the flow-down from key science requirements to technical design decisions as well as showing design analogies from other existing large radio, (sub-)mm, and optical telescopes., Comment: 20 pages. Submitted to the SPIE proceedings

The use of self-assembled monolayers (SAMs) with anchoring groups was considered as an effective approach for interface engineering in perovskite solar cells with metal oxide charge transporting layers. However, the coating of SAM layers in PSMs by means of a slot-die is a challenging process due to the low viscosity of the solutions and the low wettability of the films. In this study, we integrate a triphenylamine-based polymer, pTPA-TDP, blended with SAM based on 5-[4-[4-(diphenylamino) phenyl] thiophene-2-carboxylic acid (TPATC), to address the challenges of uniform slot-die coating and interface passivation in large-area modules. We fabricated p-i-n oriented PSMs on 50x50 mm2 substrates (12-sub-cells) with NiO hole transport layer (HTL) and organic interlayers for surface modification. Wetting angle mapping demonstrated that ununiform regions of the slot-die coated SAM have hydrophobicity with contact angle values up to 90{\deg}, causing fluctuations in absorber thickness and the presence of macro-defects at buried interfaces. The incorporation of the blended interlayer to NiO/perovskite junction homogenized the surface wettability (contact angle=40{\deg}) and mitigated lattice strain in the absorber. This enabled the effective use of SAM properties on a large-area surface, improving energy level alignment and enhancing the power conversion efficiency (PCE) of the modules from 13.98% to 15.83% and stability (ISOS-L-2, T80 period) from 500-1000 hours to 1630 hours. Investigation of PSMs upon cooling till -5 {\deg}C showed that the PCE increased by +0.19%/{\deg}C for samples with NiO HTL, while using SAM and blended interlayers raised the coefficient to ~0.40%/{\deg}C due to changes in activation energy and trap contributions to device performance across a wide temperature range.

We report on the observation of previously-unknown isotope $^{21}$Al, the first unbound aluminum isotope located beyond the proton dripline. The $^{21}$Al nucleus decays by one-proton (1p) emission, and its in-flight decays were detected by tracking trajectories of all decay products with micro-strip silicon detectors. The 1p-emission processes were studied by analyses of the measured angular correlations of decay products $^{20}$Mg+p. The 1p-decay energies of ground and low-lying excited states of $^{21}$Al, its mass excess and proton separation energy value $S_p$=$-1.1(1)$ MeV were determined., Comment: 6 pages, 7 figures

Topological magnetic solitons, such as skyrmions, exhibit intriguing particle-like properties that make them attractive for fundamental research and practical applications. While many magnetic systems can host skyrmions as statically stable configurations, chiral magnets stand out for their ability to accommodate a wide diversity of skyrmions with arbitrary topological charges and varied morphologies. Despite extensive investigation, a complete understanding of chiral magnetic skyrmions has remained elusive. We present a classification of all chiral skyrmions, demonstrating three classes based on their response to external magnetic field pulses: stationary, translating, and rotating. We highlight the role of magnetic texture symmetry in this classification. Skyrmions with varied dynamics offer avenues for exploring phenomena like skyrmion-skyrmion scattering that might be crucial for future applications., Comment: 12 pages, 6 figures

There has been a surge in developing various Large Language Models (LLMs). However, text generation for languages other than English often faces significant challenges, including poor generation quality and reduced computational performance due to the disproportionate representation of tokens in the model's vocabulary. In this work, we address these issues by developing a pipeline for adapting English-oriented pre-trained models to other languages and constructing efficient bilingual LLMs. Using this pipeline, we construct Vikhr, a state-of-the-art bilingual open-source instruction-following LLM designed specifically for the Russian language. "Vikhr" refers to the name of the Mistral LLM series and means a "strong gust of wind." Unlike previous Russian-language models that typically rely on LoRA adapters on top of English-oriented models, sacrificing performance for lower training costs, Vikhr features an adapted tokenizer vocabulary and undergoes continued pre-training and instruction tuning of all weights. This not only enhances the model's performance but also significantly improves its computational and contextual efficiency. The remarkable performance of Vikhr across various Russian-language benchmarks can also be attributed to our efforts in expanding instruction datasets and corpora for continued pre-training. Vikhr not only sets a new state of the art among open-source LLMs for Russian but even outperforms some proprietary closed-source models on certain benchmarks. The model weights, instruction sets, and code are publicly available., Comment: Accepted at WMRL @ EMNLP-2024

In this paper, a kinetic energy recovery system for large telescopes is presented, with the Atacama Large Aperture Submm Telescope (AtLAST) as a possible target application. The system consists of supercapacitors integrated in the DC-link of motor inverters through a bidirectional DC-DC converter. The optimal system design, based on the energy flow analysis within the telescope's power electronics, is introduced. The proposed system is simulated as part of the telescope's drives, providing not only a significant reduction in energy consumption of the telescope due to motion, but also remarkably reducing (or shaving) grid power peaks. We find that the system presented here can contribute to making both current and future observatories more sustainable., Comment: 9 pages, 8 figures; Submitted to as an SPIE Proceedings paper for the 2024 SPIE Astronomical Telescopes + Instrumentation meeting

In this work, we explore the dynamics of time varying photonic media with an optical Kerr nonlinearity and an associated phase transition. The interplay between a periodically modulated permittivity and the nonlinearity induces a continuous transition of electromagnetic waves to a state with broken spatial and time translation symmetries. This transition gives rise to a lattice-like wave pattern, in many ways similar to a spatial crystallization in solids. Symmetry breaking triggers the emergence of soft, Goldstone-like modes, which propagate as deformations of the lattice structure, as well as massive Higgs-like modes -- spatially uniform oscillations of the field amplitude. We extend the analysis of the non-equlibrium symmetry breaking to 2+1 dimensional time varying media and discuss pattern formation as well as the connection to discrete dissipative time crystals.

With the STAR experiment at the BNL Relativisic Heavy Ion Collider, we characterize $\sqrt{s_\mathrm{NN}}$ = 200 GeV p+Au collisions by event activity (EA) measured within the pseudorapidity range $eta$ $in$ [-5, -3.4] in the Au-going direction and report correlations between this EA and hard- and soft- scale particle production at midrapidity ($\eta$ $\in$ [-1, 1]). At the soft scale, charged particle production in low-EA p+Au collisions is comparable to that in p+p collisions and increases monotonically with increasing EA. At the hard scale, we report measurements of high transverse momentum (pT) jets in events of different EAs. In contrast with the soft particle production, high-pT particle production and EA are found to be inversely related. To investigate whether this is a signal of jet quenching in high-EA events, we also report ratios of pT imbalance and azimuthal separation of dijets in high- and low-EA events. Within our measurement precision, no significant differences are observed, disfavoring the presence of jet quenching in the highest 30% EA p+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 200 GeV., Comment: 12 page, 9 figures

Spectral loopholes in the 1000-2100 nm range have been the focus of attention of quantum hacking research aimed at searching and elimination of vulnerabilities in quantum key distribution systems. In this work, we concentrate on shorter wavelengths ranged from 400 nm up to 800 nm and experimentally study spectra of insertion losses for a number of fiber optical components to assess potentials for their implementation as countermeasures. We show that efficiency of the elements commonly used as countermeasures against hacking attacks in the telecom range can be significantly impaired in the visible range. It is found that the vulnerabilities detected in this range play an increasingly important role for hacking strategies such as the induced-photorefraction attack whose efficiency improves when the wavelength decreases., Comment: 11 pages, 7 figures

Magnetic skyrmions are topologically nontrivial spin configurations that possess particle-like properties. Earlier research was mainly focused on a specific type of skyrmion with topological charge Q = -1. However, theoretical analyses of two-dimensional chiral magnets have predicted the existence of skyrmion bags -- solitons with arbitrary positive or negative topological charge. Although such spin textures are metastable states, recent experimental observations have confirmed the stability of isolated skyrmion bags in a limited range of applied magnetic fields. Here, by utilizing Lorentz transmission electron microscopy, we show the extraordinary stability of skyrmion bags in thin plates of B20-type FeGe. In particular, we show that skyrmion bags embedded within a skyrmion lattice remain stable even in zero or inverted external magnetic fields. A robust protocol for nucleating such embedded skyrmion bags is provided. Our results agree perfectly with micromagnetic simulations and establish thin plates of cubic chiral magnets as a powerful platform for exploring a broad spectrum of topological magnetic solitons., Comment: 17 pages, 15 figures

The submillimeter and millimeter ((sub-)mm) sky contains a vast wealth of information that is both complementary and inaccessible to other wavelengths. Over half the light we receive is observable at (sub-)mm wavelengths, yet we have mapped only a small portion of the sky at sufficient spatial resolution and sensitivity to detect and resolve distant galaxies or star forming cores within their their large-scale environment. For decades the astronomical community has highlighted the need for a large, high-throughput (sub-)mm ($\lambda\sim0.35-10$ mm) single dish; The Atacama Large Aperture Submillimeter Telescope (AtLAST), with its 50-m aperture and $2^\circ$ maximal field of view, aims to be such a facility. We present here the full design concept for AtLAST, developed through an EU-funded project. Our design approach begins with a long lineage of (sub-)mm telescopes, relies on calculations and simulations to realize the optics, and uses finite element analysis to optimize the mechanical structure and subsystems. The demanding design requirements for AtLAST, set by transformative science goals, combine novel concepts with lessons learned from past experience. The result is an innovative rocking chair design with six instrument bays, two of which are mounted on Nasmyth platforms. AtLAST will be capable of $3^\circ\,\rm s^{-1}$ scanning and $1^\circ\,\rm s^{-2}$ acceleration, and aims to feature a surface accuracy of $\leq 20~\mu$m half wavefront error under static deformations, allowing observations up to $\approx 950$~GHz. Crucially, AtLAST will be a sustainable, visionary facility that will allow upgrades for decades to come. While some aspects require further testing, prototyping, and field demonstrations, we estimate that the design will be construction-ready this decade., Comment: This version addresses the first round A&A referee reports

A theoretical description of a class of unidirectional axisymmetric localized pulses, is given. The equivalence of their representations in the form of relatively undistorted quasi-spherical waves, in the form of Fourier-Bessel integrals and in the form of a superposition of plane waves with wave vectors having positive projections on a given direction is established., Comment: 12 pages, no figures

Search for the population of the low-energy continuum of tetraneutron system was performed for reactions of the $^{8}$He beam on deuterium target. These studies are performed for the data [I.A. Muzalevskii et al., Phys. Rev. C 103, 044313 (2021)], previously used for the studies of $^{7}$H and $^{6}$H in the $^2\text{H}(^8\text{He},{^3\text{He}})^{7}$H and $^2\text{H}(^8\text{He},{^4\text{He}})^{6}$H reactions. Evidence for a hump in the $^4n$ continuum at $3.5 \pm 0.7$ and $3.2 \pm 0.8$ MeV, was observed in the $^2$H($^8$He,$^6$Li)$^4$n and $^2$H($^8$He,$^3$He)$^7$H$\rightarrow ^3$H+$^4$n reactions, respectively. The observed statistics is quite low (6 and up to 40 events) corresponding to very low cross sections of few microbarns or tens of microbarns. The background conditions for the $^2$H($^8$He,$^6$Li)$^4n$ reaction are shown to be good, favoring the physical nature of the observed events. The $^2$H($^8$He,$^3$He)$^7$H$\rightarrow ^3$H+$^4n$ process transforms to the $^2$H($^8$He,$^6$Li$^{\ast})^4n$ reaction in the limit of the highest $^7$H decay energies. The population of the low-energy region in the $^{4}$n spectrum is found to be perfectly correlated with the population of the lowest $^{6}$Li states in the $^{3}$He+$^{3}$H continuum. Theoretical calculations of $^{8}$He in a five-body $\alpha$+$4n$ and of $^{4}$n in a four-body hyperspherical models are presented. The $^{8}$He wave function is shown to contain strong specific correlations, which may give rise to very low-energy structures in tetraneutron continuum in extreme-peripheral reaction scenarios., Comment: 13 pages, 9 figures

Flow coefficients ($v_2$ and $v_3$) are measured in high-multiplicity $p$+Au, $d$+Au, and $^{3}$He$+$Au collisions at a center-of-mass energy of $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV using the STAR detector. The measurements utilize two-particle correlations with a pseudorapidity requirement of $|\eta| <$ 0.9 and a pair gap of $|\Delta\eta|>1.0$. The primary focus is on analysis methods, particularly the subtraction of non-flow contributions. Four established non-flow subtraction methods are applied to determine $v_n$, validated using the HIJING event generator. $v_n$ values are compared across the three collision systems at similar multiplicities; this comparison cancels the final state effects and isolates the impact of initial geometry. While $v_2$ values show differences among these collision systems, $v_3$ values are largely similar, consistent with expectations of subnucleon fluctuations in the initial geometry. The ordering of $v_n$ differs quantitatively from previous measurements using two-particle correlations with a larger rapidity gap, which, according to model calculations, can be partially attributed to the effects of longitudinal flow decorrelations. The prospects for future measurements to improve our understanding of flow decorrelation and subnucleonic fluctuations are also discussed., Comment: 29 pages, 25 figures

The increase in performance and power of computing systems requires the wider use of program optimizations. The goal of performing optimizations is not only to reduce program runtime, but also to reduce other computer resources including power consumption. The goal of the study was to evaluate the impact of different optimization levels and various optimization strategies on power consumption. In a series of experiments, it was established that the average power consumption tends to peak for the programs with optimized source code. The articles also describes the impact of changing computer architecture on power consumption graphs. The relationships between the average and median values of power consumption by example programs are considered. The possibility of creating program energy consumption profile for a parallel program is shown.