nils-herrmann/clean_scirepeval huggingface dataset:
Decay of helical and nonhelical magnetic knots.

We present calculations of the relaxation of magnetic field structures that have the shape of particular knots and links. A set of helical magnetic flux configurations is considered, which we call n-foil knots of which the trefoil knot is the most primitive member. We also consider two nonhelical knots; namely, the Borromean rings as well as a single interlocked flux rope that also serves as the logo of the Inter-University Centre for Astronomy and Astrophysics in Pune, India. The field decay characteristics of both configurations is investigated and compared with previous calculations of helical and nonhelical triple-ring configurations. Unlike earlier nonhelical configurations, the present ones cannot trivially be reduced via flux annihilation to a single ring. For the n-foil knots the decay is described by power laws that range form t(-2/3) to t(-1/3), which can be as slow as the t(-1/3) behavior for helical triple-ring structures that were seen in earlier work. The two nonhelical configurations decay like t(-1), which is somewhat slower than the previously obtained t(-3/2) behavior in the decay of interlocked rings with zero magnetic helicity. We attribute the difference to the creation of local structures that contain magnetic helicity which inhibits the field decay due to the existence of a lower bound imposed by the realizability condition. We show that net magnetic helicity can be produced resistively as a result of a slight imbalance between mutually canceling helical pieces as they are being driven apart. We speculate that higher order topological invariants beyond magnetic helicity may also be responsible for slowing down the decay of the two more complicated nonhelical structures mentioned above.
The Relativity of Simultaneity: An Analysis Based on the Properties of Electromagnetic Waves

The determination of whether two distant events are simultaneous depends on the velocity of the observer. This velocity dependence is typically explained in terms of the relativity of space and time in a counterintuitive manner by the Special Theory of Relativity. In this paper, I describe a straightforward and intuitive way to explain the velocity dependence of simultaneity in terms of velocity-dependent changes in the spatial (k, {\lambda}) and temporal ({\omega}, ) characteristics of electromagnetic waves that result from the Doppler effect. Since, for any solution to a wave equation, the angular wave vector (k) and distance vector (r) as well as the angular frequency ({\omega}) and time (t) are complementary pairs (k *r) and ({\omega}t), it is only a matter of taste which members of the pairs (k, {\omega}) or (r, t) one assumes to depend on the relative velocity of the source and observer. Einstein chose r and t and I chose k and {\omega}. I present this electromagnetic wave approach to understanding the velocity dependence of simultaneity as a physically realistic alternative to Einstein's Special Theory of Relativity.
Scaling Limits of Additive Functionals of Interacting Particle Systems

Using the renormalization method introduced by the authors, we prove what we call the local Boltzmann‐Gibbs principle for conservative, stationary interacting particle systems in dimension d = 1. As applications of this result, we obtain various scaling limits of additive functionals of particle systems, like the occupation time of a given site or extensive additive fields of the dynamics. As a by‐product of these results, we also construct a novel process, related to the stationary solution of the stochastic Burgers equation.
On the Accuracy of Language Trees

Historical linguistics aims at inferring the most likely language phylogenetic tree starting from information concerning the evolutionary relatedness of languages. The available information are typically lists of homologous (lexical, phonological, syntactic) features or characters for many different languages: a set of parallel corpora whose compilation represents a paramount achievement in linguistics. From this perspective the reconstruction of language trees is an example of inverse problems: starting from present, incomplete and often noisy, information, one aims at inferring the most likely past evolutionary history. A fundamental issue in inverse problems is the evaluation of the inference made. A standard way of dealing with this question is to generate data with artificial models in order to have full access to the evolutionary process one is going to infer. This procedure presents an intrinsic limitation: when dealing with real data sets, one typically does not know which model of evolution is the most suitable for them. A possible way out is to compare algorithmic inference with expert classifications. This is the point of view we take here by conducting a thorough survey of the accuracy of reconstruction methods as compared with the Ethnologue expert classifications. We focus in particular on state-of-the-art distance-based methods for phylogeny reconstruction using worldwide linguistic databases. In order to assess the accuracy of the inferred trees we introduce and characterize two generalizations of standard definitions of distances between trees. Based on these scores we quantify the relative performances of the distance-based algorithms considered. Further we quantify how the completeness and the coverage of the available databases affect the accuracy of the reconstruction. Finally we draw some conclusions about where the accuracy of the reconstructions in historical linguistics stands and about the leading directions to improve it.
Modeling the dynamical interaction between epidemics on overlay networks

Epidemics seldom occur as isolated phenomena. Typically, two or more viral agents spread within the same host population and may interact dynamically with each other. We present a general model where two viral agents interact via an immunity mechanism as they propagate simultaneously on two networks connecting the same set of nodes. By exploiting a correspondence between the propagation dynamics and a dynamical process performing progressive network generation, we develop an analytical approach that accurately captures the dynamical interaction between epidemics on overlay networks. The formalism allows for overlay networks with arbitrary joint degree distribution and overlap. To illustrate the versatility of our approach, we consider a hypothetical delayed intervention scenario in which an immunizing agent is disseminated in a host population to hinder the propagation of an undesirable agent (e.g., the spread of preventive information in the context of an emerging infectious disease).
Quantum fluctuations in dipolar Bose gases

We investigate the influence of quantum fluctuations upon dipolar Bose gases by means of the Bogoliubov-de Gennes theory. Thereby, we make use of the local density approximation to evaluate the dipolar exchange interaction between the condensate and the excited particles. This allows to obtain the Bogoliubov spectrum analytically in the limit of large particle numbers. After discussing the condensate depletion and the ground-state energy correction, we derive quantum-corrected equations of motion for harmonically trapped dipolar Bose gases by using superfluid hydrodynamics. These equations are subsequently applied to analyze the equilibrium configuration, the low-lying oscillation frequencies, and the time-of-flight dynamics. We find that both atomic magnetic and molecular electric dipolar systems offer promising scenarios for detecting beyond mean-field effects.
Fermi problem with artificial atoms in circuit QED.

We propose a feasible experimental test of a 1D version of the Fermi problem using superconducting qubits. We give an explicit nonperturbative proof of strict causality in this model, showing that the probability of excitation of a two-level artificial atom with a dipolar coupling to a quantum field is completely independent of the other qubit until signals from it may arrive. We explain why this is in perfect agreement with the existence of nonlocal correlations and previous results which were used to claim apparent causality problems for Fermi's two-atom system.
Cooperative crosslink (un)binding in slowly driven bundles of semiflexible filaments.

Combining simulations and theory I study the interplay between bundle elastic degrees of freedom and crosslink binding propensity. By slowly driving bundles into a deformed configuration, and depending on the mechanical stiffness of the crosslinking agent, the binding affinity is shown to display a sudden and discontinuous drop. This indicates a cooperative unbinding process that involves the crossing of a free-energy barrier. Choosing the proper crosslinker therefore not only allows us to change the composite elastic properties of the bundle but also the relevant time scales which can be tuned from the single crosslink binding rate to the much longer escape time over the free-energy barrier.
Exact solution of the Schrödinger equation with the spin-boson Hamiltonian

We address the problem of obtaining the exact reduced dynamics of the spin-half (qubit) immersed within the bosonic bath (environment). An exact solution of the Schrödinger equation with the paradigmatic spin-boson Hamiltonian is obtained. We believe that this result is a major step ahead and may ultimately contribute to the complete resolution of the problem in question. We also construct the constant of motion for the spin-boson system. In contrast to the standard techniques available within the framework of the open quantum systems theory, our analysis is based on the theory of block operator matrices.
Dansgaard-Oeschger events: tipping points in the climate system

The largest variability in temperature over the last sixty thousand years is connected with Dansgaard-Oeschger events. Various prototype models have been proposed to explain these rapid climate fluctuations, but until now no observational constraint has been forwarded to choose between different theories. We assess the bimodality of the system reconstructing the topology of the multi-dimensional attractor over which the climate system evolves. Furthermore, we show that Dansgaard-Oeschger events are compatible with the crossing of a tipping point in the climate system. We use high-resolution ice core isotope data to investigate the statistical properties of the climate fluctuations in the period before the onset of the abrupt change. We find that the statistics are consistent with the switches between two different climate equilibrium states in response to a changing external forcing.
Domenico Pacini, uncredited pioneer of the discovery of cosmic rays

During a series of experiments performed between 1907 and 1911, Domenico Pacini (Marino 1878-Roma 1934), at that time researcher at the Central Bureau of Meteorology and Geodynamics in Roma, studied the origin of the radiation today called "cosmic rays", the nature of which was unknown at that time. In his conclusive measurements in June 1911 at the Naval Academy in Livorno, and confirmed in Bracciano a couple of months later, Pacini, proposing a novel experimental technique, observed the radiation strength to decrease when going from the surface to a few meters underwater (both in the sea and in the lake), thus demonstrating that such radiation could not come from the Earth's crust. Pacini's work was largely overlooked. Hess was awarded the Nobel Prize in Physics in 1936, two years after the death of Pacini, who had become a full professor of Experimental Physics at the University of Bari. The discovery of cosmic rays -a milestone in science- involved several scientists in Europe and in the United States of America and took place during a period characterized by nationalism and lack of communication. Historical, political and personal facts, embedded in the pre- and post-World War I context, might have contributed to the substantial disappearance of Pacini from the history of science. This article aims to give an unbiased historical account of the discovery of cosmic rays; in the centenary of Pacini's pioneering experiments, his work, which employed a technique that was complementary to, and independent of that of Hess, will be duly taken into consideration. A translation into English of three fundamental early articles by Pacini is provided in the Appendix.
Non-Bayesian Social Learning

We develop a dynamic model of opinion formation in social networks when the information required for learning a parameter may not be at the disposal of any single agent. Individuals engage in communication with their neighbors in order to learn from their experiences. However, instead of incorporating the views of their neighbors in a fully Bayesian manner, agents use a simple updating rule which linearly combines their personal experience and the views of their neighbors. We show that, as long as individuals take their personal signals into account in a Bayesian way, repeated interactions lead them to successfully aggregate information and learn the true parameter. This result holds in spite of the apparent naivete of agentsʼ updating rule, the agentsʼ need for information from sources the existence of which they may not be aware of, worst prior views, and the assumption that no agent can tell whether her own views or those of her neighbors are more accurate.
W\gamma \gamma production with leptonic decays at NLO QCD

The computation of the O(αs) QCD corrections to the cross sections for Wγγ production in hadronic collisions is presented. We consider the case of real photons in the final state, but include full leptonic decays of the W . Numerical results for the LHC and the Tevatron are obtained through a parton level Monte Carlo based on the structure of the VBFNLO program, allowing an easy implementation of general cuts and distributions. We show the dependence on scale variations of the integrated cross sections and provide evidence of the fact that NLO QCD corrections strongly modify the LO predictions for observables at the LHC both in magnitude and in shape.  2013 —0:42
Statistical Inference for Valued-Edge Networks: The Generalized Exponential Random Graph Model

Across the sciences, the statistical analysis of networks is central to the production of knowledge on relational phenomena. Because of their ability to model the structural generation of networks based on both endogenous and exogenous factors, exponential random graph models are a ubiquitous means of analysis. However, they are limited by an inability to model networks with valued edges. We address this problem by introducing a class of generalized exponential random graph models capable of modeling networks whose edges have continuous values (bounded or unbounded), thus greatly expanding the scope of networks applied researchers can subject to statistical analysis.
A de Sitter Farey Tail

We consider quantum Einstein gravity in three dimensional de Sitter space. The Euclidean path integral is formulated as a sum over geometries, including both perturbative loop corrections and non-perturbative instanton corrections coming from geometries with non-trivial topology. These non-trivial geometries have a natural physical interpretation. Conventional wisdom states that the sphere is the unique Euclidean continuation of de Sitter space. However, when considering physics only in the causal patch of a single observer other Euclidean geometries, in this case lens spaces, contribute to physical observables. This induces quantum gravitational effects which lead to deviations from the standard thermal behaviour obtained by analytic continuation from the three sphere. The sum over these geometries can be formulated as a sum over cosets of the modular group/ this is the de Sitter analog of the celebrated 'black hole Farey tail.' We compute the vacuum partition function including the sum over these geometries. Perturbative quantum corrections are computed to all orders in perturbation theory using the relationship between Einstein gravity and Chern-Simons theory, which is checked explicitly at tree and one-loop level using heat kernel techniques. The vacuum partition function, including all instanton and perturbative corrections, is shown to diverge in a way which can not be regulated using standard field theory techniques.
$\Lambda_c N$ bound states revisited

The one-boson exchange potential model for $\Lambda_cN$ is constructed and the possibility of $\Lambda_cN$ bound states is examined. We consider an effective Lagrangian for the charmed baryons, $\Lambda_c$, $\Sigma_c$, and $\Sigma_c^*$, reflecting the heavy quark symmetry, chiral symmetry, and hidden local symmetry. We determine the coupling constants using various methods. With the derived nonrelativistic potentials, we study the bound state problem of the $\Lambda_cN$ system and relevant coupled channel effects. It is found that molecular bound states of $\Lambda_cN$ are plausible, for which the channel couplings of $\Sigma_cN$ and $\Sigma_c^*N$ are essential.
Superradiant phase transitions and the standard description of circuit QED.

We investigate the equilibrium behavior of a superconducting circuit QED system containing a large number of artificial atoms. It is shown that the currently accepted standard description of circuit QED via an effective model fails in an important aspect: it predicts the possibility of a superradiant phase transition, even though a full microscopic treatment reveals that a no-go theorem for such phase transitions known from cavity QED applies to circuit QED systems as well. We generalize the no-go theorem to the case of (artificial) atoms with many energy levels and thus make it more applicable for realistic cavity or circuit QED systems.
Percolation transition in Yang-Mills matter at a finite number of colors.

We examine baryonic matter at a quark chemical potential of the order of the confinement scale μ(q)∼Λ(QCD). In this regime, quarks are supposed to be confined but baryons are close to the "tightly packed limit" where they nearly overlap in configuration space. We show that this system will exhibit a percolation phase transition when varied in the number of colors N(c): at high N(c), large distance correlations at the quark level are possible even if the quarks are essentially confined. At low N(c), this does not happen. We discuss the relevance of this for dense nuclear matter, and argue that our results suggest a new "phase transition," varying N(c) at constant μ(q).
Non-Decomposable Nambu Brackets

It is well-known that the Fundamental Identity (FI) implies that Nambu brackets are decomposable, i.e., given by a determinantal formula. We find a weaker alternative to the FI that allows for non-decomposable Nambu brackets, but still yields a Darboux-like Theorem via a Nambu-type generalization of Weinstein's splitting principle for Poisson manifolds.
An Empirical Study of Real-World SPARQL Queries

Understanding how users tailor their SPARQL queries is crucial when designing query evaluation engines or fine-tuning RDF stores with performance in mind. In this paper we analyze 3 million real-world SPARQL queries extracted from logs of the DBPedia and SWDF public endpoints. We aim at finding which are the most used language elements both from syntactical and structural perspectives, paying special attention to triple patterns and joins, since they are indeed some of the most expensive SPARQL operations at evaluation phase. We have determined that most of the queries are simple and include few triple patterns and joins, being Subject-Subject, Subject-Object and Object-Object the most common join types. The graph patterns are usually star-shaped and despite triple pattern chains exist, they are generally short.
How accurate is it to update the cosmology of your halo catalogues

We test and present the application of the full rescaling method by Angulo & White to change the cosmology of halo catalogues in numerical simulations for cosmological parameter search using semi-analytic galaxy properties. We show that a reduced form of the method can be applied to small simulations with box side of ∼50 h−1 Mpc or smaller without loss of accuracy. We perform statistical tests on the accuracy of the properties of rescaled individual haloes, and also on the rescaled population as a whole. We find that individual positions and velocities are recovered with almost no detectable biases, but with a scatter that increases slightly with the size of the simulation box when using the full method. The dispersion in the recovered halo mass does not seem to depend on the resolution of the simulation. Regardless of the halo mass, the individual accretion histories, spin parameter evolution and fraction of mass in substructures are remarkably well recovered. In particular, in order to obtain a more accurate estimate of the halo virial mass, it was necessary to apply an additional correction due to the change in the virial overdensity and the estimate of its effect on a Navarro, Frenk & White (NFW) virial mass. The mass of rescaled haloes can be underestimated (overestimated) for negative (positive) variations of either σ8 or , in a way that does not depend on the halo mass. Statistics of abundances and correlation functions of haloes also show small biases of <10 per cent when moving away from the base simulation by up to two times the uncertainty in the WMAP7 cosmological parameters. The merger tree properties related to the final galaxy population in haloes also show small biases; the time since the last major merger, the assembly time-scale, and a time-scale related to the stellar ages show correlated biases which indicate that the spectral shapes of galaxies would only be affected by global age changes of ∼150 Myr, i.e. relatively small shifts in their broad-band colours. We show some of these biases for different separations in the cosmological parameters with respect to the desired cosmology so that these can be used to estimate the expected accuracy of the resulting halo population. We also present a way to construct grids of simulations to provide a stable accuracy across the versus σ8 parameter space.
Rotational-state-specific guiding of large molecules.

A beam of polar molecules can be focused and transported through an ac electric quadrupole guide. At a given ac frequency, the transmission of the guide depends on the mass-to-dipole-moment (m/μ) ratio of the molecular quantum state. Here we present a detailed characterization of the m/μ selector, using a pulsed beam of benzonitrile (C(6)H(5)CN) molecules in combination with rotational quantum state resolved detection. The arrival time distribution as well as the transverse velocity distribution of the molecules exiting the selector are measured as a function of ac frequency. The μ/Δμ resolution of the selector can be controlled by the applied ac waveforms and a value of up to 20 can be obtained with the present setup. This is sufficient to exclusively transmit benzonitrile molecules in quantum states with the same m/μ value as the absolute ground state. The operation characteristics of the m/μ selector are in quantitative agreement with the outcome of trajectory simulations.