Table of contents

We study correlation properties of the generalized elastic model which accounts for the dynamics of polymers, membranes, surfaces and fluctuating interfaces, among others. We develop a theoretical framework which leads to the emergence of universal scaling laws for systems starting from thermal (equilibrium) or non-thermal (non-equilibrium) initial conditions. Our analysis incorporates and broadens previous results such as observables' double scaling regimes, (super)roughening and anomalous diffusion, and furnishes a new scaling behavior for correlation functions at small times (long distances). We discuss ageing and ergodic properties of the generalized elastic model in non-equilibrium conditions, providing a comparison with the situation occurring in continuous time random walk. Our analysis also allows to assess which observable is able to distinguish whether the system is in or far from equilibrium conditions in an experimental set-up.

We study the dynamics of 2d spin-ice following a quench from a fully disordered initial condition (equilibrium at infinite temperature) into its disordered, ferromagnetic and antiferromagnetic phases. We analyze the evolution of the density of topological defects and we show that these take finite density over very long periods of time in all kinds of quenches. We identify the leading mechanisms for the growth of domains in the ordered phases and we evaluate the (anisotropically) growing lengths involved in dynamic scaling.

We assume that Markovian dynamics on a finite graph enjoys a gauge symmetry under local scalings of the probability density, derive the transformation law for the transition rates and interpret the thermodynamic force as a gauge potential. A widely accepted expression for the total entropy production of a system arises as the simplest gauge-invariant completion of the time derivative of Gibbs's entropy. We show that transition rates can be given a simple physical characterization in terms of locally detailed balanced heat reservoirs. It follows that Clausius's measure of irreversibility along a cyclic transformation is a geometric phase. In this picture, the gauge symmetry arises as the arbitrariness in the choice of a prior probability. Thermostatics depends on the information that is disposable to an observer; thermodynamics does not.

In this letter we present a new method, called increment chain equation method (ICEM), for computing a cascade of distinct modes in a two-dimensional weakly nonlinear wave system generated by narrow frequency band excitation. The ICEM is a means for computing the quantized energy spectrum as an explicit function of frequency ω₀ and stationary amplitude A₀ of excitation. The physical mechanism behind the generation of the quantized cascade is modulation instability. The ICEM can be used in numerous 2D weakly nonlinear wave systems with narrow frequency band excitation appearing in hydrodynamics, nonlinear optics, electrodynamics, convection theory etc. In this letter the ICEM is demonstrated with examples of gravity and capillary waves with dispersion functions ω(k)∼k^1/2 and ω(k)∼k^3/2, respectively, and for two different levels of nonlinearity ε=A₀k₀: small (ε∼0.1 to 0.25) and moderate (ε∼0.25 to 0.4).

We present new, original and alternative method for searching signals coded in noisy data. The method is based on the properties of random matrix eigenvalue density. First, we describe general ideas and support them with results of numerical simulations for basic periodic signals hidden in artificial stochastic noise. Then, the main effort is put to examine the strength of a new method in investigation of data content taken from the real astrophysical NAUTILUS detector designed to search for gravitational waves. Our method discovers some previously unknown problems with data aggregation in this experiment. We provide also the results of new method applied to the entire respond signal from ground-based bar detectors in future experimental activities with reduced background noise level. A good performance of our method is indicated what makes it a positive predictor for further applications in many areas.

The pattern formation in a magnetic wire forced by a transversal uniform and oscillatory magnetic field is studied. This system is described in the continuous framework by the Landau-Lifshitz-Gilbert equation. We find numerically that, the spatio-temporal magnetization field exhibits a family of localized states that connect asymptotically a uniform oscillatory state with an extended wave. Close to parametrical resonance instability, an amended amplitude equation is derived, which allows us to understand and characterize these localized waves.

In this letter, the designable integrability (DI) of the variable coefficient derivative nonlinear Schrödinger equation (VCDNLSE) is shown by construction of an explicit transformation which maps VCDNLSE to the usual derivative nonlinear Schrödinger equation (DNLSE). One novel feature of VCDNLSE with DI is that its coefficients can be designed artificially and analytically by using transformation. What is more, from the rogue wave and rational traveling solution of the DNLSE, we get two kinds of rogue waves of the VCDNLSE by this transformation. One kind of rogue wave has vanishing boundary condition, and the other non-vanishing boundary condition. The DI of the VCDNLSE also provides a possible way to control the profile of the rogue wave in physical experiments.

We propose a simple way to measure the three-dimensional rotational diffusion of micrometric wires, using two-dimensional video microscopy. The out-of-plane Brownian motion of the wires in a viscous fluid is deduced from their projection on the focal plane of an optical microscope objective. An angular variable reflecting the out-of-plane motion, and satisfying a Langevin equation, is computed from the apparent wire length and its projected angular displacement. The rotational diffusion coefficient of wires between 1 and 100 μm is extracted, as well as the diameter distribution. Translational and rotational diffusion were found to be in good agreement. This is a promising way to characterize soft visco-elastic materials, and probe the dimension of anisotropic objects.

The energy of the first-excited state in ¹⁹⁷Au has been measured with high precision using conventional γ-ray spectroscopy with HPGe detectors. A γ77 keV line of ¹⁹⁷Au and K_β lines of Au are overlapped almost completely and such measurements present a very serious challenge. The coincidence measurements have been applied, first, with the γ77 keV line for the precise energy calibration using K_α and K_β lines of Au, secondly, with K_α lines of Au for the precise energy measurement of the first-excited state in ¹⁹⁷Au. Our current result is 77.339± 0.003 keV, confirming the observations of the recent ¹⁹⁷Au NEET experiment performed at SPring-8, while, according to available nuclear data, the energy of the first-excited state in ¹⁹⁷Au is 77.351±0.002 keV.

The method of generation of metal nanoclusters consists in the injection of a metal microparticle in a vertical flow of a buffer gas where this microparticle stops because of the equality of the gravitation and Stokes forces and rises up along a funnel-shaped tube in the course of evaporation under the action of an external field. The formed metal atoms are transformed into nanoclusters in a cold region of the flow. Parameters of processes involving nanoclusters are analyzed for a silver microparticle in an argon flow.

We derive and discuss an experimentally realistic model describing ultracold atoms in an optical lattice including a commensurate, but staggered, spin-flip term. The resulting band structure is quite exotic; fermions in the third band have an unusual rounded picture-frame Fermi surface (essentially two concentric squircles), leading to imperfect nesting. We develop a generalized theory describing the spin and charge degrees of freedom simultaneously at the random-field-approximation level, and show that the system can develop a coupled spin-charge-density wave order. Our generic approach can be used to study spin and charge instabilities in many materials, such as high-T_c superconductors, organic compounds, graphene, and iron pnictides.

Radiation by elementary sources is a basic problem in wave physics. We show that the time-domain energy flux radiated from electromagnetic and acoustic subwalength sources exhibits remarkable features. In particular, a subtle trade-off between source emission and absorption underlies the mechanism of radiation. This behavior should be observed for any kind of classical waves, thus having broad potential implications. We discuss the implication for subwavelength focusing by time reversal with active sources.

Ocean acoustic propagation can be formulated as a wave guide with a weakly random medium generating multiple scattering. Twenty years ago, this was recognized as a quantum chaos problem, and yet random matrix theory, one pillar of quantum or wave chaos studies, has never been introduced into the subject. The modes of the wave guide provide a representation for the propagation, which in the parabolic approximation is unitary. Scattering induced by the ocean's internal waves leads to a power-law random banded unitary matrix ensemble for long-range deep-ocean acoustic propagation. The ensemble has similarities, but differs, from those introduced for studying the Anderson metal-insulator transition. The resulting long-range propagation ensemble statistics agree well with those of full wave propagation using the parabolic equation.

After devoting to asymptotical instability for decades, the hydrodynamic community noticed that non-normality of the evolution operator for perturbations may have dominant effects over limited time horizons by inducing significant transient energy growth, especially in linearly stable/weakly unstable flows. In flow past a rotating cylinder, it has been observed that the unsteadiness and asymptotical instability associated with vortex shedding are suppressed over a wide range of the ratio between the rotating velocity and free stream velocity. In this work, we investigate the transient energy growth of initial perturbations in this stabilized flow and the physical relevance of the optimal initial perturbation. The nonlinear development of the initial perturbations is further studied by evolving the base flow initially perturbed by the optimal initial perturbation in DNS (Direct Numerical Simulation). As the initial perturbation is convected downstream, it is observed that the vortex shedding reassumes transiently.

We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction ϕ_avg ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of ϕ_avg and anticorrelations for ϕ_avg> 0.8277. The spatial extent of the anti-correlation increases with ϕ_avg while the position of the maximum of the anticorrelation and the extent of the positive correlation shrink with ϕ_avg. We conjecture that the onset of anticorrelation corresponds to dilatancy onset in this system.

In spontaneous Raman process in atomic cell at high gain, both the Stokes field and the accompanying collective atomic excitation (atomic spin wave) are coherent. We find that, due to the spontaneous nature of the process, the phases of the Stokes field and the atomic spin wave change randomly from one realization to another but are anti-correlated. The phases of the atomic ensembles are read out via another Raman process at a later time, thus realizing phase memory in atoms. The observation of phase correlation between the Stokes field and the collective atomic excitations is an important step towards macroscopic EPR-type entanglement of continuous variables between light and atoms.

The 4/5-law of turbulence, which characterizes the energy cascade from large to small-sized eddies at high Reynolds numbers in classical fluids, is verified experimentally in a superfluid ⁴He wind tunnel, operated down to 1.56 K and up to R_λ≈1640. The result is corroborated by high-resolution simulations of Landau-Tisza's two-fluid model down to 1.15 K, corresponding to a residual normal fluid concentration below 3% but with a lower Reynolds number of order R_λ≈100. Although the Kármán-Howarth equation (including a viscous term) is not valid a priori in a superfluid, it is found that it provides an empirical description of the deviation from the ideal 4/5-law at small scales and allows us to identify an effective viscosity for the superfluid, whose value matches the kinematic viscosity of the normal fluid regardless of its concentration.

Based on molecular-dynamics simulations and experimental data, a new coarse-grained forcefield is proposed for the polyacrylamide (PAM)-water system that allows to study dynamical properties of chains at several concentrations with molecular weight up to 17000 g/mol. Non-equilibrium simulations were used to compute relative viscosities, enabling a direct comparison with experimental values. High-shear-rate measurements for low-molecular-weight PAM (10000 g/mol) were done using a microfluidic rheometer Rheosense to decrease the gap between experimental and simulated shear rates. DPD simulations reproduced qualitatively and quantitatively structural properties as well as rheological properties in the dilute regime and qualitatively in the semi-dilute regime.

Planck's law describes the radiation of black bodies. The study of its properties is of special interest, as black bodies are a good description for the behavior of many phenomena. In this work a new mathematical study of Planck's law is performed and new properties of this old acquaintance are obtained. As a result, the exact form for the locus in a color-color diagram has been deduced, and an analytical formula to determine with precision the black-body temperature of an object from any pair of measurements has been developed. Thus, by using two images of the same field obtained with different filters, one can compute a fast estimation of black-body temperatures for every pixel in the image, that is, a new image of the black-body temperatures for all the objects in the field. Once these temperatures are obtained, the method allows, as a consequence, a quick estimation of their emission in other frequencies, assuming a black-body behavior. These results provide new tools for data analysis.

Submerged in a solvent-containing environment and subject to applied forces, a covalent polymer network absorbs the solvent and deforms, forming an elastomeric gel. The equations of state are derived under two assumptions. First, the amount of the solvent in the gel varies when the gel changes volume, but remains constant when the gel changes shape. Second, the Helmholtz free energy of the gel is separable into the contribution due to stretching the network and that due to mixing the polymer and the solvent. We demonstrate that these equations of state fit several sets of experimental data in the literature remarkably well.

We propose to realize a passive optical quantum swapping device which allows for the exchange of the quantum fluctuations of two bright optical fields interacting with a coherent atomic medium in an optical cavity. The device is based on a quantum interference process between the fields within the cavity bandwidth arising from coherent population trapping in the atomic medium.

The charges of μm-size particles in the quasineutral bulk plasma of a dc discharge are determined experimentally in a pressure range between 100 and 500 Pa, spanning the transition between the weakly collisional and highly collisional (hydrodynamic) regimes, where the ion mean free path drops below the plasma screening length. The charge is determined using the force balance condition from the measured particle drift velocities in stable particle flows. A simple interpolation formula for the ion flux to the grain in the transitional regime is shown to fit quite well the experimental results.

It is widely believed that relativistic low magnetized shocks are mediated by filamentary (Weibel) instability. Numerical simulations show that the developing filamentation results in the shock formation accompanied by ion deceleration and efficient electron heating. Similar heating efficiency was found in periodic numerical simulations which indicates similar mechanisms for both systems. Yet, the mechanism of the electron energization has not been identified so far. Here a new simple model of electron acceleration in filamentary relativistic shocks is presented. We suggest that the large-scale inductive electric field, generated in the course of the filamentary instability, is responsible for ion deceleration and electron energization within the filaments. Acceleration of electrons along the filaments is due to the electric field alignment with the filaments, while isotropization is due to the magnetic scattering, broadband nature of the instability and continuous growth of the dominant scale of the magnetic field. This electron heating is a nonstationary effect and occurs as long as the filaments keep growing.

In this work we provide the first explanation for observations made in 1997 on the Joint European Torus of unexpected ion heating with fusion-born alpha particles occurring over time scales much shorter than those theoretically foreseen. We demonstrate that non-thermal alpha particles above a critical concentration stabilize ion-drift-wave turbulence, therefore significantly reducing one of the main energy loss channels for thermal ions. As such ion heating occurs over times scales much shorter than those classically predicted, this mechanism opens new prospects on additional paths for the self-sustainment of thermonuclear fusion reactions in magnetically confined plasmas.

Based on a Mach-Zehnder interferometer, we report on the first observation of two different modes of wire explosion for nanosized powder production in 5–30 kPa ambient gas, depending on the property of wire material. For wire material with relatively high resistivity, such as titanium, more than one vapor burst was observed. While for wire material with relatively low resistivity, such as copper, the whole wire would explode totally within one single vapor burst.

Metalorganic chemical vapor deposition growth of InAs/GaSb superlattices is reported using an As_xSb_1−x plane that connects the InAs and GaSb layers to compensate the tensile strain introduced by the InAs layers. The effects of gas switching sequences for growing the As_xSb_1−x planes on the interface structure and crystalline quality of InAs/GaSb superlattices were investigated by Raman scattering spectroscopy and X-ray diffraction. It is found that uniform interfaces and high-quality superlattice can be obtained by growing the As_xSb_1−x planes through the exchange interaction of As and Sb atoms at the surfaces of InAs or GaSb layers.

Indium molybdenum oxide (IMO) thin films were radio-frequency (RF) sputtered at room temperature (RT) and studied as a function of base pressure (BP). The crystallinity of the films is decreased with the increase in BP. A maximum mobility (μ) of 49.6 cm² V⁻¹ s⁻¹ was obtained from the IMO films deposited at RT without any post-annealing treatment. The electronic behaviour of the deposited films was investigated by temperature-dependent (100–550 K) Hall measurements. Study on the scattering mechanisms based on the experimental data and theoretical models show that the ionized scattering centres are dominating. The films possess wide work function (4.91 eV) and high transmittance (> 70%) over visible and near infrared (NIR) range. The obtained results, especially the high work function and NIR transmittance, are very promising particularly in applications such as optical detectors and solar cells.

The dendrite growth velocity during non-equilibrium solidification of tetragonal Ni₂B crystals is measured as a function of undercooling on electrostatically levitated droplets. High-speed video imaging is applied to measure in situ the propagation of the solid-liquid interface apparent on the sample surface. To analyze the raw data, a three-dimensional model is developed to determine the growth velocity within the volume of the melt. Microstructure analysis is performed to resolve the pattern formation mechanism of tetragonal Ni₂B crystals which differs significantly from the cubic case. The dendrite tips are found to grow perpendicular to the crystallographic {111} planes. As a consequence, the propagation of the solidification front on a macroscopic scale is determined by the lattice parameters of the tetragonal crystal structure. The dendrite growth velocities along the {111} normal directions are analyzed on a mesoscopic scale within a sharp-interface model.

Through a lattice dynamics analysis, it is revealed that the bubble plays a role of energy shield in the graphene, which helps to split the normal modes into two categories of distinct topological nature, namely the bright and dark modes. The topological invariants, Euler characteristic, of the bright and dark modes are 1 and 0, respectively. For bright modes, the energy is confined inside the bubble, so this type of modes is sensitive to the shape of the bubble; while the opposite phenomenon is observed for the dark modes. The different behavior of these two types of normal modes is examined and verified in the process of phonon thermal transport. The bright and dark modes are expected to be distinguished in experiment with existing scanning force microscope techniques, and they should play significant roles in many other physical processes.

The structure of the tilted phase of monolayer-protected nanoparticles is investigated by means of a simple Ginzburg-Landau model. The theory contains two dimensionless parameters representing the preferential tilt angle and the ratio between the energy cost due to spatial variations in the tilt of the coating molecules and that of the van der Waals interactions which favors the preferential tilt. We analyze the model for both spherical and octahedral particles. On spherical particles, we find a transition from a tilted phase, at small , to a phase where the molecules spontaneously align along the surface normal and tilt disappears. Octahedral particles have an additional phase at small characterized by the presence of six topological defects. These defective configurations provide preferred sites for the chemical functionalization of monolayer-protected nanoparticles via place-exchange reactions and their consequent linking to form molecules and bulk materials.

By measuring as a function of temperature the Leslie thermomechnical coefficient in a compensated cholesteric mixture, we arrived at the conclusion that the Lehmann effect, namely the rotation of cholesteric droplets under the action of a temperature gradient, cannot be explained only by the Leslie thermomechanical coupling effect.

Nematic solids, both glassy and elastomeric, with defects in the director field can attain stress-free Gaussian curvature from an initially flat state. In this letter we show how the intrinsic curvature and/or the global topology of the initial reference state interacts with the curvature arising from the spontaneously strained nematic director field. In particular, locally compatible mechanical deformations due to the director can be globally incompatible in certain topologies.

Isostatic networks are minimally rigid and therefore have, generically, nonzero elastic moduli. Regular isostatic networks have finite moduli in the limit of large sizes. However, numerical simulations show that all elastic moduli of geometrically disordered isostatic networks go to zero with system size. This holds true for positional as well as for topological disorder. In most cases, elastic moduli decrease as inverse power laws of system size. On directed isostatic networks, however, of which the square and cubic lattices are particular cases, the decrease of the moduli is exponential with size. For these, the observed elastic weakening can be quantitatively described in terms of the multiplicative growth of stresses with system size, giving rise to bulk and shear moduli of order e^−bL. The case of sphere packings, which only accept compressive contact forces, is considered separately. It is argued that these have a finite bulk modulus because of specific correlations in contact disorder, introduced by the constraint of compressivity. We discuss why their shear modulus, nevertheless, is again zero for large sizes. A quantitative model is proposed that describes the numerically measured shear modulus, both as a function of the loading angle and system size. In all cases, if a density p>0 of overconstraints is present, as when a packing is deformed by compression or when a glass is outside its isostatic composition window, all asymptotic moduli become finite. For square networks with periodic boundary conditions, these are of order . For directed networks, elastic moduli are of order e^−c/p, indicating the existence of an "isostatic length scale" of order 1/p.

Cold-atom developments suggest the prospect of measuring scaling properties and long-range fluctuations of continuous phase transitions at zero temperature. We discuss the conditions for characterizing the phase separation of Bose-Einstein condensates of boson atoms in two distinct hyperfine spin states. The mean-field description breaks down as the system approaches the transition from the miscible side. An effective spin description clarifies the ferromagnetic nature of the transition. We show that a difference in the scattering lengths for the bosons in the same spin state leads to an effective internal magnetic field. The point at which the internal magnetic field vanishes (i.e., equal values of the like-boson scattering lengths) is a special point. We show that the long-range density fluctuations are suppressed near that point, while the effective spin exhibits the long-range fluctuations that characterize critical points. The zero-temperature system exhibits critical opalescence with respect to long-wavelength waves of impurity atoms that interact with the bosons in a spin-dependent manner.

Tetrahedral liquids such as water and silica-melt show unusual thermodynamic behavior such as a density maximum and an increase in specific heat when cooled to low temperatures. Previous work had shown that Monte Carlo and mean-field solutions of a lattice model can exhibit these anomalous properties with or without a phase transition, depending on the values of the different terms in the Hamiltonian. Here we use a somewhat different approach, where we start from a very popular empirical model of tetrahedral liquids —the Stillinger-Weber model— and construct a coarse-grained theory which directly quantifies the local structure of the liquid as a function of volume and temperature. We compare the theory to molecular-dynamics simulations and show that the theory can rationalize the simulation results and the anomalous behavior.

We report on theoretical investigation of the thermal conductivity of Al_xGa_1−xN (0⩽x⩽1) films over a wide range of temperature by using both Debye's and Callaway's model. Our calculated results agree well with most of the available experimental results of films grown by Hidride Vapor Phase Epitaxy (HVPE) and Metal Oxide Chemical Vapor Deposition (MOCVD) techniques. We find that the large contribution of alloy mass disorder and point impurity scattering is the primary reason for the increase in thermal conductivity of Al_xGa_1−xN alloy film beyond room temperature. Above room temperature, MOCVD films have lower thermal conductivity compared to HVPE grown films due to the presence of a larger amount of defects in MOCVD films as compared to HVPE films. Variation of thermal resistivity with x in Al_xGa_1−xN shows a peak at x=0.7 due to the highest contribution of mass disorder.

We show that a magnetic insulating state with nonzero spin chirality is realized in a quarter-doped Hubbard model on honeycomb lattice as a result of the nesting property of the Fermi surface. This state is topological nontrivial and has a quantized Hall conductance of . We find that such a state is robust against next-nearest-neighboring hopping and we propose that it can be realized in a quarter-doped graphene system. We also show that the quarter-doped Hubbard model on honeycomb lattice is equivalent to a 3/4-filled Hubbard model on triangular lattice in the weak coupling limit, in which a similar effect was predicted previously.

Positive magnetoresistance (PMR) of a silicon MOSFET in parallel magnetic fields B has been measured at high electron densities n≫n_c, where n_c is the critical density of the metal-insulator transition (MIT). It turns out that the normalized PMR curves, R(B)/R(0), merge together when the field is scaled according to B/B_c(n), where B_c is the field in which electrons become fully spin polarized. The values of B_c have been calculated from the simple equality between the Zeeman splitting energy and the Fermi energy taking into account the experimentally measured dependence of the spin susceptibility on the electron density. This extends the range of validity of the scaling all the way to a deeply metallic regime far away from MIT. The subsequent analysis of PMR for low demonstrated that the merging of the initial parts of curves can be achieved only with taking into account the temperature dependence of B_c. It is also shown that the shape of the PMR curves at strong magnetic fields is affected by a crossover from a purely two-dimensional (2D) electron transport to a regime where out-of-plane carrier motion becomes important (quasi-three-dimensional regime).

We show, by exact Renormalization Group methods, that in multi-layer graphene the dimensional crossover energy scale is decreased by the intra-layer interaction, and that for temperatures and frequencies greater than such scale the conductivity is close to the one of a stack of independent layers up to small corrections.

LiCu₂O₂ is the first multiferroic cuprate to be reported and its ferroelectricity is induced by complex magnetic ordering in ground state, which is still in controversy today. Herein, we have grown nearly untwinned LiCu₂O₂ single crystals of high quality and systematically investigated their dielectric and ferroelectric behaviours in external magnetic fields. The highly anisotropic response observed in different magnetic fields apparently contradicts the prevalent bc- or ab-plane cycloidal spin model. Our observations give strong evidence supporting a new helimagnetic picture in which the normal of the spin helix plane is along the diagonal of CuO₄ squares which form the quasi-1D spin chains by edge-sharing. Further analysis suggests that the spin helix in the ground state is elliptical and in the intermediate state the present c-axis collinear SDW model is applicable with some appropriate modifications. In addition, our studies show that the dielectric and ferroelectric measurements could be used as probes for the characterization of the complex spin structures in multiferroic materials due to the close tie between their magnetic and electric orderings.

The pseudopotential theory is extended to the Bogoliubov-de Gennes equations to determine the excess energy when one atom is added to the trapped superfluid Fermi system with even number of atoms. Particular attention is paid to systems being at the Feshbach resonance point. The results for relatively small particle numbers are in harmony with the Monte Carlo calculations, but are also relevant for systems with larger particle numbers. Concerning the additional one-quasiparticle state we define and determine two new universal numbers to characterize its widths.

The charge redistribution at grain boundaries is critical for the applicability of high-T_c superconductors in electronic devices, because it determines the transport across the material. We investigate the charge transfer and the alterations of the electronic states due to local doping of a normal-state 45°-tilted [001] grain boundary in YBa₂Cu₃O₇ by means of first-principles calculations. Considering Ca doping and O deficiency as prototypical modifications we demonstrate that the redistribution of the charge carriers in the CuO₂ planes displays a very complex spatial pattern, which deviates even qualitatively from the naive expectation.

We study magnetic order induced by non-magnetic impurities in quantum paramagnets with incommensurate host spin correlations. In contrast to the well-studied commensurate case where the defect-induced magnetism is spatially disordered but non-frustrated, the present problem combines strong disorder with frustration and, consequently, leads to spin-glass order. We discuss the crossover from strong randomness in the dilute limit to more conventional glass behavior at larger doping, and numerically characterize the robust short-range order inherent to the spin-glass phase. We relate our findings to magnetic order in both BiCu₂PO₆ and YBa₂Cu₃O_6.6 induced by Zn substitution.

Open resonators have been widely applied in dielectric sensing and laser cavity. In this letter, we designed and fabricated a novel open resonator using a metamaterial transmission line medium. The open-resonance effect which is generated by multiple negative reflections is demonstrated experimentally. It may open up a new avenue for designing open resonators based on metamaterials.

We demonstrate semi-metallic transport in graphene oxide layers treated with an organic acid through a nearly linear current-vs.-voltage relationship and the weak temperature dependence of resistance from high temperatures down to 20 K. Additionally an energy gap was observed below 17 K due to the formation of local barriers by residual oxygen groups and disorder in reduced graphene oxide (RGO) sheets. At higher temperatures resistance shows a negative T² temperature dependence. Temperature dependent magnetization measurements showed a phase transition from diamagnetic to ferromagnetic at around 10 K, in agreement with the electronic transport properties of the RGO films.

We present a model that predicts the geometry of chromatin fibers as a function of the DNA repeat length. Chromatin fibers are widely observed in vitro and are typically posited as the second level of the hierarchical organization of chromatin in the nuclei of cells. We postulate that the major driving force for fiber formation is the dense packing of the underlying DNA-protein spools, the nucleosomes, allowing for fibers with four possible diameters. We show that the diameters observed in experiments on reconstituted regular fibers correspond to the geometries that minimize the elastic energy of the DNA linking the nucleosomes.

We ask which is the best strategy to reveal uncertainty relations between complementary observables of a continuous variable system for coarse-grained measurements. This leads to the derivation of new uncertainty relations for coarse-grained measurements that are always valid, even for detectors with low precision. These relations should be particularly relevant in experimental demonstrations of squeezing in quantum optics, quantum state reconstruction, and the development of trustworthy entanglement criteria.

Nucleosome repositioning is a fundamental process in gene function. DNA elasticity is a key element of loop-mediated nucleosome repositioning. Two analytical models for DNA elasticity have been proposed: the linear sub-elastic chain (SEC), which allows DNA kinking, and the worm-like chain (WLC), with a harmonic bending potential. In vitro studies have shown that nucleosomes reposition in a discontiguous manner on a segment of DNA and this has also been found in ground-state calculations with the WLC analytical model. Here we study using Monte Carlo simulation the dynamics of DNA loop-mediated nucleosome repositioning at physiological temperatures using the SEC and WLC potentials. At thermal energies both models predict nearest-neighbor repositioning of nucleosomes on DNA, in contrast to the repositioning in jumps observed in experiments. This suggests a crucial role of DNA sequence in nucleosome repositioning.

It is assumed that a galaxy starts as a dark halo of a few million Jeans clusters (JCs), each of which consists of nearly a trillion micro brown dwarfs, MACHOs of Earth mass. JCs in the galaxy center heat up their MACHOs by tidal forces, which makes them expand, so that coagulation and star formation occurs. Being continuously fed by matter from bypassing JCs, the central star(s) may transform into a super massive black hole. It has a fast t³ growth during the first mega years, and a slow t^1/3 growth at giga years. JCs disrupted by a close encounter with this black hole can provide matter for the bulge. Those that survive can be so agitated that they form stars inside them and become globular star clusters. Thus black holes mostly arise together with galactic bulges in their own environment and are about as old as the oldest globular clusters. The age 13.2 Gy of the star HE 1523-0901 puts forward that the Galactic halo was fully assembled at that moment. The star formation rate has a maximum at black hole mass ∼4·10⁷M_⊙ and bulge mass ∼5·10¹⁰M_⊙. In case of merging supermassive black holes the JCs passing near the galactic center provide ideal assistance to overcome the last parsec.

Chiral Lagrangian and quark-meson coupling models of hyperon matter are used to estimate the maximum mass of neutron stars. Our relativistic calculations include, for the first time, both Hartree and Fock contributions in a consistent manner. Being related to the underlying quark structure of baryons, these models are considered to be good candidates for describing the dense core of neutron stars. Taking account of the known experimental constraints at saturation density, the equations of state deduced from these relativistic approaches cannot sustain a neutron star with a mass larger than 1.6–1.66M_⊙.

The superluminal neutrino velocity measured by the OPERA experiment is explained in a non-relativistic spacetime conception. Spacetime is viewed as a permeable medium of wave propagation. The neutrino wave equation is coupled to a permeability tensor, like electromagnetic fields in dielectric media. The inertial frame in which this tensor is isotropic defines a distinguished frame of reference, the rest frame of the aether. The dispersion relation of the spinorial wave modes gives rise to a superluminal group velocity of the energy flux. The Gordon decomposition of spinor currents in a refractive and dispersive spacetime is performed with finite as well as zero rest mass. The convective and spin components of the superluminal neutrino current are related to the permeability tensor. The refractive index of the aether depends on the neutrino energy, and is inferred in the 10 to 50 GeV range from the measured excess velocity. Implications of the superluminal speed of signal transfer regarding relativity principles and causality are discussed.