Analytical Arguments Research Articles

An improved Representative Particle Monte Carlo method for the simulation of particle growth

Context. A rocky planet is formed out of the agglomeration of around 1040 cosmic dust particles. As dust aggregates grow by coagulation, their number decreases. But until they have grown to hundreds of kilometres, their number still remains well above the number of particles a computer model can handle directly. The growth from micrometres to planetesimal-sized objects therefore has to be modelled using statistical methods, often using size distribution functions or Monte Carlo methods. However, when the particles reach planetary masses, they must be treated individually. This can be done by defining two classes of objects: a class of many small bodies or dust particles treated in a statistical way, and a class of individual bodies such as one or more planets. This introduces a separation between small and big objects, but it leaves open how to transition from small to big objects, and how to treat objects of intermediate sizes. Aims. We aim to improve the Representative Particle Monte Carlo (RPMC) method, which is often used for the study of dust coagulation, to be able to smoothly transition from the many-particle limit into the single-particle limit. Results. Our new version of the RPMC method allows for variable swarm masses, making it possible to refine the mass resolution where needed. It allows swarms to consist of few numbers of particles, and it includes a treatment of the transition from swarm to individual particles. The correctness of the method for a simplified two-component test case is validated with an analytical argument. The method is found to retain statistical balance and to accurately describe runaway growth, as is confirmed with the standard constant kernel, linear kernel, and product kernel tests as well as by comparison with a fiducial non-representative Monte Carlo simulation.

Reflected entropy in random tensor networks. Part II. A topological index from canonical purification

In ref. [1], we analyzed the reflected entropy (SR) in random tensor networks motivated by its proposed duality to the entanglement wedge cross section (EW) in holographic theories, {S}_R=2frac{EW}{4G} . In this paper, we discover further details of this duality by analyzing a simple network consisting of a chain of two random tensors. This setup models a multiboundary wormhole. We show that the reflected entanglement spectrum is controlled by representation theory of the Temperley-Lieb algebra. In the semiclassical limit motivated by holography, the spectrum takes the form of a sum over superselection sectors associated to different irreducible representations of the Temperley-Lieb algebra and labelled by a topological index k ∈ ℤ>0. Each sector contributes to the reflected entropy an amount 2kfrac{EW}{4G} weighted by its probability. We provide a gravitational interpretation in terms of fixed-area, higher-genus multiboundary wormholes with genus 2k – 1 initial value slices. These wormholes appear in the gravitational description of the canonical purification. We confirm the reflected entropy holographic duality away from phase transitions. We also find important non-perturbative contributions from the novel geometries with k ≥ 2 near phase transitions, resolving the discontinuous transition in SR. Along with analytic arguments, we provide numerical evidence for our results. We finally speculate that signatures of a non-trivial von Neumann algebra, connected to the Temperley-Lieb algebra, will emerge from a modular flowed version of reflected entropy.

Experimental estimation of liquid phase concentration in aerosol jet

Rapid-mixed models are a key tool in the numerical solution of aerosol flow evaporation problems. Despite the fact that these models are mainly based on analytical arguments, they have shown fairly good reproducibility in practice. However, with the advent of the DNS results, cases of discrepancies with the classical theory of droplet evaporation began to be discovered, which require an experimental study of the problem. The present paper shows an experimental method for estimating the concentration of the liquid phase in aerosol flows based on digital video processing.

Artificial intelligence as a creator of journalistic content

The advent of Artificial Intelligence (AI) is gradually reshaping society and impacting more and more areas, not excluding media. However, if we want to exploit the potential of this new technological phenomenon as effectively as possible, and in order to maintain established norms of media production, it is necessary to examine the capabilities of AI tools and compare them with human creations. One popular AI tool is ChatGPT. In media production, it is used, for example, in the creation of journalistic texts, as it is specialized to generate texts in a ‘human way’ based on input data. Therefore, the research paper aims to assess this AI tool in the context of the criteria of press release production as a basic journalistic genre. The object of investigation is to assess and evaluate the fulfilment of the basic criteria set for a quality press release, for two groups of media content – human-generated and ChatGPT-generated. In the evaluation, the authors will emphasize the fulfillment of the specific criteria formulated in the assignment, noting also the AI’s ability to learn and improve its creations. In its theoretical framework and analytical argumentation, the paper draws on existing knowledge from the literature, including scholarly studies by experts such as H. Pravdová (2016), T. Rončáková (2011), B. Jones et al. (2022), A. Tušer (2010), J. Mistrík (1989), M. Richter (2023), A. Kellerman (2023), B. Dhiman (2023), D. Zagorulko (2023) and others.

Shell viscosity estimation of lipid-coated microbubbles.

Understanding the shell rheology of ultrasound contrast agent microbubbles is vital for anticipating their bioeffects in clinical practice. Past studies using sophisticated acoustic and optical techniques have made enormous progress in this direction, enabling the development of shell models that adequately reproduce the nonlinear behaviour of the coated microbubble under acoustic excitation. However, there have also been puzzling discrepancies and missing physical explanations for the dependency of shell viscosity on the equilibrium bubble radius, which demands further experimental investigations. In this study, we aim to unravel the cause of such behaviour by performing a refined characterisation of the shell viscosity. We use ultra-high-speed microscopy imaging, optical trapping and wide-field fluorescence to accurately record the individual microbubble response upon ultrasound driving across a range of bubble sizes. An advanced model of bubble dynamics is validated and employed to infer the shell viscosity of single bubbles from their radial time evolution. The resulting values reveal a prominent variability of the shell viscosity of about an order of magnitude and no dependency on the bubble size, which is contrary to previous studies. We find that the method called bubble spectroscopy, which has been used extensively in the past to determine the shell viscosity, is highly sensitive to methodology inaccuracies, and we demonstrate through analytical arguments that the previously reported unphysical trends are an artifact of these biases. We also show the importance of correct bubble sizing, as errors in this aspect can also lead to unphysical trends in shell viscosity, when estimated through a nonlinear fitting from the time response of the bubble.

True God and True Man: some implications

The paper aims to analyze the problems that religious truth, particularly Christian truth understood as an event, poses to the category of de re truth. How does the conception of truth ‘as event’ stand phenomenologically in relation to the contemporary analytical debate on truth? Statements in the catechism such as “true God and true man” referring to Jesus, or the same words attributed to Jesus in John’s gospel (14:6) such as “I am the way, the truth or the life” how can they be understood in relation to the category of recently called ‘dual character concepts’? Is there a difference between the notion of ‘true warrior’ and that of ‘true God’? When is a person appropriately categorized as a true man? When is a person appropriately categorized as a true God? What is the relationship between faith and truth?

Metapopulation persistence can be inferred from incomplete surveys.

Habitat destruction and fragmentation are principal causes of species loss. While a local population might go extinct, a metapopulation-populations inhabiting habitat patches connected by dispersal-can persist regionally by recolonizing empty patches. To assess metapopulation persistence, two widely adopted indicators in conservation management are metapopulation capacity and patch importance. However, we face a fundamental limitation in that assessing metapopulation persistence requires that we survey or sample all the patches in a landscape: often these surveys are logistically challenging to conduct and repeat, which raises the question whether we can learn enough about the metapopulation persistence from an incomplete survey. Here, we provide a robust statistical approach to infer metapopulation capacity and patch importance by sampling a portion of all patches. We provided analytic arguments on why the metapopulation capacity and patch importance can be well predicted from sub-samples of habitat patches. Full-factorial simulations with more complex models corroborate our analytic predictions. We applied our model to an empirical metapopulation of mangrove hummingbirds (Amazilia boucardi). On the basis of our statistical framework, we provide some sampling suggestion for monitoring metapopulation persistence. Our approach allows for rapid and effective inference of metapopulation persistence from incomplete patch surveys.

Charged and radially excited boson stars in anti–de Sitter spacetime

We study charged and radially excited boson stars in both asymptotically flat as well as asymptotically anti--de Sitter spacetime. We demonstrate that two different types of radially excited solutions exist: one that persists in the linear limit of small scalar fields, in which analytical arguments suggest the existence of these solutions, and one that appears only in the highly nonlinear regime of the model. We also demonstrate that the formation of wavy scalar hair discussed previously for black holes and boson stars in asymptotically flat spacetime persists for asymptotically anti--de Sitter spacetime.

Applied Geospatial Bayesian Modeling in the Big Data Era: Challenges and Solutions

Two important trends in applied statistics are an increased usage of geospatial models and an increased usage of big data. Naturally, there has been overlap as analysts utilize the techniques associated with each. With geospatial methods such as kriging, the computation required becomes intensive quickly, even with datasets that would not be considered huge in other contexts. In this work we describe a solution to the computational problem of estimating Bayesian kriging models with big data, Bootstrap Random Spatial Sampling (BRSS), and first provide an analytical argument that BRSS produces consistent estimates from the Bayesian spatial model. Second, with a medium-sized dataset on fracking in West Virginia, we show that bootstrap sample effects from a full-information Bayesian model are reduced with more bootstrap samples and more observations per sample as in standard bootstrapping. Third, we offer a realistic illustration of the method by analyzing campaign donors in California with a large geocoded dataset. With this solution, scholars will not be constrained in their ability to apply theoretically relevant geospatial Bayesian models when the size of the data produces computational intractability.

Partial lifting of degeneracy in the J1−J2−J3 Ising antiferromagnet on the kagome lattice

Motivated by dipolar-coupled artificial spin systems, we present a theoretical study of the classical $J_1-J_2-J_3$ Ising antiferromagnet on the kagome lattice. We establish the ground-state phase diagram of this model for $J_1 > |J_2|, |J_3|$ based on exact results for the ground-state energies. When all the couplings are antiferromagnetic, the model has three macroscopically degenerate ground-state phases, and using tensor networks, we can calculate the entropies of these phases and of their boundaries very accurately. In two cases, the entropy appears to be a fraction of that of the triangular lattice Ising antiferromagnet, and we provide analytical arguments to support this observation. We also notice that, surprisingly enough, the dipolar ground state is not a ground state of the truncated model, but of the model with smaller $J_3$ interactions, an indication of a very strong competition between low-energy states in this model.

On the properties of Alfvénic switchbacks in the expanding solar wind: The influence of the Parker spiral

Switchbacks—rapid, large deflections of the solar wind's magnetic field—have generated interest as possible signatures of the mechanisms that heat the corona and accelerate the solar wind. In this context, an important task for theories of switchback formation and evolution is to understand their observable distinguishing features, allowing them to be carefully assessed using spacecraft data. Here, we work toward this goal by studying how Alfvénic switchbacks evolve in the expanding solar wind beyond the Alfvén radius, when the background magnetic field also rotates due to the Parker spiral. Using simple analytic arguments based on the physics of one-dimensional spherically polarized (constant-field-magnitude) Alfvén waves, we find that, by controlling the wave's obliquity, a Parker spiral strongly impacts switchback properties. Surprisingly, parallel magnetic-field deflections (switchbacks) can grow faster in a Parker spiral than in a radial background field, even though normalized wave amplitudes grow more slowly. In addition, switchbacks become strongly asymmetric: large switchbacks preferentially involve magnetic-field rotations in the plane of the Parker spiral (tangential deflections) rather than perpendicular (normal) rotations, and such deflections are strongly “tangentially skewed,” meaning switchbacks always involve field rotations in the same direction (toward the positive-radial direction for an outward mean field). In a companion paper [Johnston et al., Phys. Plasmas 29, 072902 1346 (2022)], we show that these properties also occur in turbulent 3D fields with switchbacks, given various caveats. Given that these nontrivial asymmetries and correlations develop purely as a consequence of switchback propagation in the solar wind, our results show that in situ observed asymmetrical switchback features cannot be used straightforwardly to infer properties of sources in the low corona.

A coevolution model of defensive medicine, litigation and medical malpractice insurance

We model the interactions between physicians and patients, subject to clinical and legal risks, by means of an evolutionary game. In each instant of time, there is a large number of random pairwise encounters between members of the two populations. In each encounter, a physician heals a patient. The outcome of the healing process is uncertain and may result in patient harm; if that happens, the patient may sue the physician for medical malpractice. Physicians have to choose between two alternative treatments, D and ND, with different levels of benefits and risks. The treatment D is less risky than the alternative treatment ND, but has the disadvantage of providing a lower expected benefit to the patient. Therefore its provision corresponds to practicing “negative” defensive medicine.Physicians prevent, at least partially, negligence charges by buying medical malpractice insurance. This transfers the risk of litigation from the physician to the insurer.The dynamics we analyze are determined by a three-dimensional discrete-time dynamic system, where the variables x and y are, respectively, the shares of defensive physicians and litigious patients, while the variable a represents the insurance premium.In such a context we show that, depending on the policy’s price calculation principle as well as on model’s parameters related to the accuracy of the judicial system and legal reforms, the game’s final outcome could be an appealing equilibrium point in which the defensive strategy of physicians and litigious behavior of patients vanish, an interior (Nash) equilibrium in which all strategies coexist, or even an oscillatory behavior arisen via a Neimart–Sacker bifurcation in which strategies coexist in a recurrent manner. Furthermore, we state a “no chaos” conjecture, supported by analytical, numerical and empirical arguments.

Rise and Fall, and Slow Rise Again, of Operator Entanglement under Dephasing.

The operator space entanglement entropy, or simply "operator entanglement" (OE), is an indicator of the complexity of quantum operators and of their approximability by matrix product operators (MPOs). We study the OE of the density matrix of 1D many-body models undergoing dissipative evolution. It is expected that, after an initial linear growth reminiscent of unitary quench dynamics, the OE should be suppressed by dissipative processes as the system evolves to a simple stationary state. Surprisingly, we find that this scenario breaks down for one of the most fundamental dissipative mechanisms: dephasing. Under dephasing, after the initial "rise and fall," the OE can rise again, increasing logarithmically at long times. Using a combination of MPO simulations for chains of infinite length and analytical arguments valid for strong dephasing, we demonstrate that this growth is inherent to a U(1) conservation law. We argue that in an XXZ spin model and a Bose-Hubbard model the OE grows universally as 1/4log_{2}t at long times and as 1/2log_{2}t for a Fermi-Hubbard model. We trace this behavior back to anomalous classical diffusion processes.

La primera fase del Gobierno Revolucionario de las Fuerzas Armadas y su repercusión en la sociedad

The first phase of the Revolutionary Government of the Armed Forces (RGAF) (1968-1975) was led by the Divisional General Peruvian Army Juan Francisco Velasco Alvarado, who was responsible of significant changes in the Peruvian State to tackle national problems which the country dragged from the beginning of the republic, particularly social problems inherited from the viceregal period. These measures were taken as a result of the existing threats in the national and international context. However, those measures which were taken in both agricultural and educational reforms and technological development, have led to different discussions in the academic and political fields despite the years that have passed. The purpose of this paper is to analyze the context within which the reforms were carried out by the Revolutionary Government of the Armed Forces during the phase of the General Velasco; thus, contributing to analytical reflection and argument on the matter subject after reviewing the large existing bibliography about the mentioned period of government and that who personified it.

Standard self-confinement and extrinsic turbulence models for cosmic ray transport are fundamentally incompatible with observations

ABSTRACT Models for cosmic ray (CR) dynamics fundamentally depend on the rate of CR scattering from magnetic fluctuations. In the ISM, for CRs with energies ∼MeV-TeV, these fluctuations are usually attributed either to ‘extrinsic turbulence’ (ET) – a cascade from larger scales – or ‘self-confinement’ (SC) – self-generated fluctuations from CR streaming. Using simple analytic arguments and detailed ‘live’ numerical CR transport calculations in galaxy simulations, we show that both of these, in standard form, cannot explain even basic qualitative features of observed CR spectra. For ET, any spectrum that obeys critical balance or features realistic anisotropy, or any spectrum that accounts for finite damping below the dissipation scale, predicts qualitatively incorrect spectral shapes and scalings of B/C and other species. Even if somehow one ignored both anisotropy and damping, observationally required scattering rates disagree with ET predictions by orders of magnitude. For SC, the dependence of driving on CR energy density means that it is nearly impossible to recover observed CR spectral shapes and scalings, and again there is an orders-of-magnitude normalization problem. But more severely, SC solutions with super-Alfvénic streaming are unstable. In live simulations, they revert to either arbitrarily rapid CR escape with zero secondary production, or to bottleneck solutions with far-too-strong CR confinement and secondary production. Resolving these fundamental issues without discarding basic plasma processes requires invoking different drivers for scattering fluctuations. These must act on a broad range of scales with a power spectrum obeying several specific (but plausible) constraints.

Dispersive transport dynamics in porous media emerge from local correlations

Understanding and controlling transport through complex media is central for a plethora of processes ranging from technical to biological applications. Yet, the effect of micro-scale manipulations on macroscopic transport dynamics still poses conceptual conundrums. Here, we demonstrate the predictive power of a conceptual shift in describing complex media by local micro-scale correlations instead of an assembly of uncorrelated minimal units. Specifically, we show that the non-linear dependency between microscopic morphological properties and macroscopic transport characteristics in porous media is captured by transport statistics on the level of pore junctions instead of single pores. Probing experimentally and numerically transport through two-dimensional porous media while gradually increasing flow heterogeneity, we find a non-monotonic change in transport efficiency. Using analytic arguments, we built physical intuition on how this non-monotonic dependency emerges from junction statistics. The shift in paradigm presented here broadly affects our understanding of transport within the diversity of complex media.

Теоретико-методологічні засади наукової творчості Валерія Степанкова (до 75-річчя дослідника)

The purpose of this article is to analyze the theoretical and methodological principles of Valerii Stepankov’s scientifi c work. He has a Doctorate Degree in Historical Sciences, Professor, head of the Department of World History at Kamianets-Podilskyi Ivan Ohiienko National University. Th e methodological ground of the research is the principles of historicism, comprehensiveness and consistency. Th e author has widely used problem-chronological, comparative and diachronic methods. Th e scientifi c novelty of the article is determined by the number of historiographical sources –individual works of the researcher that were used. Conclusions. Th e family upbringing formed in the future historian the main worldview mat- rix of moral and ethical values based on honesty, decency, diligence, responsible performance of assignments and tasks. Th e initial stage of his formation as a scientist evolved during his student years and the fi rst years of work as an assistant in the General History Department of Kamianets-Podilskyi Volodymyr Zatonskyi Pedagogical Institute (1967-1975) and was determined by the Marxist methodology of author’s research initiatives. Th e next stage (1976-1988) started aft er V. Stepankov’s acquaintance with the books of M. Hrushevsky «History of Ukraine- Rus» and V. Lypynsky «Ukraine at the Turn of 1657-1659» which was the impetus for the pro- cess of rethinking the concept of the liberation struggle of the Ukrainian people in 1648-1654. It was unfortunate period for the author, because he could not publicly present it within the socio-political conditions of that time. During the «turning decade» (1989-1998), the removal of ideological restrictions and the actualization of the problem in connection with the forma- tion of independent Ukraine created favorable conditions for the professional self-realization of Mr. V. Stepankov who became a successful scientist-innovator. Based on the statehood approach, he has formulated the concept of the National Liberation Revolution of 1648-1676. From the end of the XXth century and to the present days, he continues to deepen and expand the analytical arguments of his vision of the events of Ukrainian / national history of the middle and second half of the XVIIth century. Nowadays, V. Stepankov uses the principles of positivism and neo- positivism as the methodological basis of his research, but does not limit himself to this. He also extensively uses the tools of the «Annals» school, the «new» social history, modal biography, and psychohistory.

Robust quantum boomerang effect in non-Hermitian systems

Anderson localization is a general phenomenon that applies to a variety of disordered physical systems. Recently, a novel manifestation of Anderson localization for wave packets launched with a finite average velocity was proposed, the Quantum boomerang effect (QBE). This phenomenon predicts that the disorder-averaged center of mass of a particle initially moves ballistically, then makes a U-turn, and finally slowly returns to its initial position. The QBE has been predicted to take place in several Hermitian models with Anderson localization and has been experimentally observed in the paradigmatic quantum kicked rotor model. In this work, we investigate the emergence of the QBE in non-Hermitian systems and clarify the importance of symmetries of the Hamiltonian and the initial state. We generalize the analytical arguments available in the literature and show that even in the case of complex spectrum a boomerang-like behavior can appear in a non-Hermitian system. We confirm our analytical results through a careful numerical investigation of the dynamics for several non-Hermitian models. We find that non-Hermiticity leads to the breakdown of the dynamical relation, though the QBE is preserved. This work opens up new avenues for future investigations in Anderson localized systems. The models studied here may be implemented using cold atoms in optical lattices.

Utwory klawesynowe Weroniki Ratusińskiej-Zamuszko – między przeszłością a współczesnością

Works for Harpsichord by Weronika Ratusińska-Zamuszko—Between the Past and the Present The article is devoted to two works by Weronika Ratusińska-Zamuszko: the cycle Nymphs for soprano saxophone and harpsichord, and the miniature For Berenika. A miniature in the Baroque style. The introduction contains information about the composer and basic facts about the pieces in question. In the following sections of the article the author analyses: harmony (tonal arrangement and harmonic relations), form (formal models, motifs, rhythms), texture and sound as well as aesthetic aspects. Based on these elements, the key determinants of the composer's style are presented, referring to the Baroque techniques as well as those typical of the postmodern musical language, also discussing the issues of non-musical content resulting from the programme titles of the works. In the analytical part, the author presents an innovative analytical method consisting in reducing the notation of the harpsichord part to the basso continuo notation to verify the thesis that the choice of the instrument (in this case, the harpsichord) determines the style of the composition. The analytical argument leads to interesting research conclusions and is an attempt to define the composer's musical language.

Translation and modulation invariant Banach spaces of tempered distributions satisfy the metric approximation property

In this paper, we establish the validity of the so-called Bounded Approximation Property (BAP) for a comprehensive class of translation and modulation invariant Banach spaces (B, ∥ · ∥B) of tempered distributions on the Euclidean space [Formula: see text]. In fact, such spaces have a double module structure, over some Beurling algebra with respect to convolution, and with respect to pointwise multiplication over some Fourier Beurling algebra. Combining this double module structure with functional analytic arguments which describe the approximation of convolution operators by discrete convolutions we are able to verify the BAP, in fact, for most cases even the Metric Approximation Property (MAP) for such Banach space. The family of spaces under consideration is very rich and contains virtually all the classical function spaces relevant for mathematical analysis, as long as the Schwartz space [Formula: see text] is dense in (B, ∥ · ∥B). In particular, all the reflexive spaces in this family are included. Moreover, this family of Banach spaces is closed with respect to intersections, sums and various interpolation methods.