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We theoretically study dipole-dipole interactions on 3P0-3D1 with ultracold Sr atoms in a deep optical lattice. To prepare such a dense atomic sample, Bose-Einstein condensates (BEC) will be performed and subsequently are loaded into a Mott insulator by increasing the optical potential. Here, we calculate the important properties of Sr dipole-dipole interactions based on the coupled dipole model and also show the setup for the preparation of the Sr sample. Both simulation results and the feasibility of experiments indicate that lattice-based Sr atoms is an excellent candidate for studying dipoledipole interactions.

We consider magnetoactive elastomer samples based on the elastic matrix and magnetizable particle inclusions. The application of an external magnetic field to such composite samples causes the magnetization of particles, which start to interact with each other. This interaction is determined by the magnetization field, generated not only by the external magnetic field but also by the magnetic fields arising in the surroundings of interacting particles. Due to the scale invariance of magnetic interactions (O(r−3) in d=3 dimensions), a comprehensive description of the local as well as of the global effects requires a knowledge about the magnetization fields within individual particles and in mesoscopic portions of the composite material. Accordingly, any precise calculation becomes technically infeasible for a specimen comprising billions of particles arranged within macroscopic sample boundaries. Here, we show a way out of this problem by presenting a greatly simplified, but accurate approximation approach for the computation of magnetization fields in the composite samples. Based on the dipole model to magnetic interactions, we introduce the cascading mean-field description of the magnetization field by separating it into three contributions on the micro-, meso-, and macroscale. It is revealed that the contributions are nested into each other, as in the Matryoshka’s toy. Such a description accompanied by an appropriate linearization scheme allows for an efficient and transparent analysis of magnetoactive elastomers under rather general conditions.

We develop a dipole model describing the thermal far-field radiation of a nanoparticle in close vicinity to a substrate. By including in our description the contribution of eddy currents and the possibility to choose different temperatures for the nanoparticle, the substrate, and the background, we generalize the existing models. We discuss the impact of the different temperatures, particle size, emission angle, and the distance dependence for all four combinations of gold and SiC nanoparticles or substrates., Comment: 13 pages, 8 figures, submitted to Journal of Quantitative Spectroscopy & Radiative Transfer

We present a set of formulas to extract the longitudinal structure function from the proton structure function and its derivatives with respect to lnQ2 in the next-to-next-to-leading order of the perturbative theory at low x based on a hard poemron exchange. The behavior of the DIS cross section ratio R(x;Q2) and the ratio FL(x;Q2)=F2(x;Q2) studied and compared with the experimental data, also these behaviors controlled by the color dipole model bound. These results show a good agreement with the DIS experimental data throughout the low values of x. These results within the next-to-next-to-leading order approximation at very low x can be applied in the LHeC region for analyses of ultra-high energy processes., Comment: 15 pages, 7 figures

Cutaneous electrogastrography (EGG) is used in clinical and physiological fields to noninvasively measure the electrical activity of the stomach and intestines. Dipole models that mathematically express the electrical field characteristics generated by the stomach and intestines have been developed to investigate the relationship between the electrical control activity (ECA) (slow waves) shown in EGG and the internal gastric electrical activity. However, these models require a mathematical description of the movement of an annular band of dipoles, which limits the shape that can be modeled. In this study, we propose a novel polygonally meshed dipole model to conveniently reproduce ECA based on the movement of the annular band in complex shapes, such as the shape of the stomach and intestines, constructed in three-dimensional (3D) space. We show that the proposed model can reproduce ECA simulation results similar to those obtained using conventional models. Moreover, we show that the proposed model can reproduce the ECA produced by a complex geometrical shape, such as the shape of the intestines. The study results indicate that ECA simulations can be conducted based on structures that more closely resemble real organs than those used in conventional dipole models, with which, because of their intrinsic construction, it would be difficult to include realistic complex shapes, using the mathematical description of the movement of an annular band of dipoles. Our findings provide a powerful new approach for computer simulations based on the electric dipole model.

Nuclear shadowing corrections to the structure functions of deep inelastic scattering on intermediate-mass nuclei are calculated at very small values of Bjorken x and small values of Q^2 (Q^2, 12 pages, 8 figures

The suspended ferromagnetic particles subjected to the gradient and uniform magnetic fields experience both the translational force generated by the field gradient and the rotational torque generated by the fields strengths. Although the uniform field does not contribute to the force, it nevertheless influences the translational motion of these particles. This occurs because the translational force depends on the direction of the particle magnetization, which in turn depends on the fields strengths. To study this influence, a minimal set of equations describing the coupled translational and rotational motions of nanosized ferromagnetic particles is introduced and solved in the low Reynolds number approximation. Trajectory analysis reveals that, depending on the initial positions of nanoparticles, there exist four regimes of their directed transport. The intervals of initial positions that correspond to different dynamical regimes are determined, their dependence on the uniform magnetic field is established, and strong impact of this field on the directed transport is demonstrated. The ability and efficiency of the uniform magnetic field to control the separation of suspended ferromagnetic nanoparticles is also discussed., Comment: 14 pages, 5 figures

Field studies on freely behaving animals commonly require tagging and often are focused on single species. Weakly electric fish generate a species- and individual-specific electric organ discharge (EOD) and therefore provide a unique opportunity for individual tracking without tagging. We here present and test tracking algorithms based on recordings with submerged electrode arrays. Harmonic structures extracted from power spectra provide fish identity. Localization of fish based on weighted averages of their EOD amplitudes is found to be more robust than fitting a dipole model. We apply these techniques to monitor a community of three species,Apteronotus rostratus,Eigenmannia humboldtii, andSternopygus dariensis, in their natural habitat in Darién, Panamá. We found consistent upstream movements after sunset followed by downstream movements in the second half of the night. Extrapolations of these movements and estimates of fish density obtained from additional transect data suggest that some fish cover at least several hundreds of meters of the stream per night. Most fish, includingEigenmannia, were traversing the electrode array solitarily. Fromin-situmeasurements of the decay of the EOD amplitude with distance of individual animals we estimated that fish can detect conspecifics at distances of up to 2 m. Our recordings also emphasize the complexity of natural electrosensory scenes resulting from the interactions of the EODs of different species. Electrode arrays thus provide an unprecedented window into the so-far hidden nocturnal activities of multispecies communities of weakly electric fish at an unmatched level of detail.Summary statementDetailed movement patterns and complex electrosensory scenes of three species of weakly electric fish were tracked without tagging using a submerged electrode array in a small Neotropical stream.

It has been shown theoretically and experimentally that locally magnetizing rebar through a protective layer of concrete makes it possible to determine both the depth of the protective layer of concrete and the diameter of rebar based on stray magnetic fields regardless of the magnetic properties of steel that rebar is made of.

The libration dynamics of the electrodynamic tether system is studied for 13° International Geomagnetic Reference Field. Using the International Geomagnetic Reference Field including up to 13 t h order and 13° terms to describe the geomagnetic field, the attitude dynamic equations of the system in the elliptical orbits are built. The generalized forces produced by this magnetic model are derived. The generalized forces related to the in-plane and out-of-plane angles are sum of generalized forces for nontilted dipole model and generalized forces for higher order geomagnetic model terms. In the analysis of the libration dynamic characteristics, the generalized forces for higher order geomagnetic model terms are regarded as perturbations to the dynamic equations for the nontilted dipole model. The simulation results show that differences of components of these two geomagnetic model and differences of generalized forces related to them are all small. Failure time of the libration motion is defined to measure the influence of the perturbation to the system. Examples for different electrodynamic parameters and orbital parameters are simulated. The results show that the perturbations have obvious effects on the attitude dynamics. The influences of perturbations caused by higher order terms of 13° International Geomagnetic Reference Field for different parameters are all obtained.

We study the photoproduction of vector mesons off proton and off nuclear targets. We work within the colour dipole model in an approach that includes subnucleon degrees of freedom, so-called hot spots, whose positions in the impact-parameter plane change event-by-event. The key feature of our model is that the number of hot spots depends on the energy of the photon--target interaction. Predictions are presented for exclusive and dissociative production of $\rho^{0}$, $\mathrm{J/}\psi$, and $\Upsilon(1S)$ off protons, as well as for coherent and incoherent photoproduction of $\rho^{0}$ off nuclear targets, where Xe, Au, and Pb nuclei are considered. We find that the mass dependence of dissociative production off protons as a function of the energy of the interaction provides a further handle to search for saturation effects at HERA, the LHC and future colliders. We also find that the coherent photonuclear production of $\rho^{0}$ is sensitive to fluctuations in the subnucleon degrees of freedom at RHIC and LHC energies., Comment: 19 pages, 4 figures. Typo in legend of figs. 1 and 2 corrected

Background and objective Motion tracking and navigation systems are paramount for both safety and efficacy in a variety of surgical insertions, interventions and procedures. Among the state-of-art tracking technology, passive magnetic tracking using permanent magnets or passive magnetic sources for localization is an effective technology to provide untethered medical instrument tracking without cumbersome wires needed for signal or power transmission. Motivated by practical needs in two medical insertion procedures: Nasogastric intubation and Ventriculostomy, we propose a unified method based on passive magnetic-field localization, for enhanced efficacy and safety. Methods Traditional approaches to passive magnetic tracking involve solving the inverse localization problem. Limited by the idealistic magnetic field dipole model and computationally intense nonlinear optimization algorithm, the overall accuracy and computational cost are greatly compromised. The method introduced here features direct localization with artificial neural network (ANN) models that bypasses the need to resolve the inverse problem and is adaptable for a variety of real-time localization and tracking applications. Results The efficiency of the two methods, the inverse optimization method and the direct ANN method are experimentally evaluated by comparing the estimated position of reference trajectories for typical nasogastric and ventriculostomy insertion paths performed by a dexterous robotic arm which provides ground truth measurement. It was found that within the region of interest (ROI), the direct ANN technique could significantly improve the localization accuracy, with an average experimental localization error of less than 2 mm, while that of the traditional inverse optimization method using a dipole-based mathematical model at greater than 5 mm. Ex-vivo experiments were performed to validate the localization methods in clinical settings. Conclusions While the proposed method for passive magnetic tracking requires a procedure-specific pre-procedural calibration, it is able to provide real-time tracking with high accuracy, robustness and diversity. It could be the missing piece to the puzzle to bring passive magnetic tracking technology into practice, therefore leading to untethered medical instrument tracking.

Four geomagnetic field models are discussed: IGRF, inclined, direct and simplified dipoles. Geomagnetic induction vector expressions are provided in different reference frames. Induction vector behavior is compared for different models. Models applicability for the analysis of satellite motion is studied from theoretical and engineering perspectives. Relevant satellite dynamics analysis cases using analytical and numerical techniques are provided. These cases demonstrate the benefit of a certain model for a specific dynamics study. Recommendations for models usage are summarized in the end.

Rapidity distributions of vector mesons are computed in dipole model proton–lead ultraperipheral collisions (UPCs) at the CERN Larger Hadron Collider (LHC). The dipole model framework is implemented in the calculations of cross sections in the photon–hadron interaction. The bCGC model and Boosted Gaussian wave functions are employed in the scattering amplitude. We obtain predictions of rapidity distributions of J / ψ meson proton–lead ultraperipheral collisions. The predictions give a good description to the experimental data of ALICE. The rapidity distributions of ϕ, ω and ψ ( 2 s ) mesons in proton–lead ultraperipheral collisions are also presented in this paper.

Experimentally, we found the percentage of low valence cations, the ionization energy of cations in film, and the band gap of substrates to be decisive for the formation of two-dimensional electron gas at the interface of amorphous/crystalline oxide (a-2DEG). Considering these findings, we inferred that the charge transfer from the film to the interface should be the main mechanism of a-2DEG formation. This charge transfer is induced by oxygen defects in film and can be eliminated by the electron-absorbing process of cations in the film. Based on this, we propose a simple dipole model that successfully explains the origin of a-2DEG, our experimental findings, and some important properties of a-2DEG.

A detailed error analysis of input and output data for several rapid methods of magnetic search is carried out. Computer simulation is used to make comparative estimates of the accuracies and search ranges for a particular measurement situation. Scale modeling for searches and the application of these results to arbitrary measurement situations are discussed.

As a crucial optical element, many different kinds of microlens have been proposed and studied. In this paper, a 2-dimensional microlens has been achieved based on direct bending of wavefront. With only 25 elements, the microlens can achieve subwavelength imaging in a 2-dimensional case. Focusing pattern and sensitivity of object movement have been studied. The physical picture for focusing and imaging has been explained by the help of a Gauss dipole model. Current study can broaden the basic understanding on light-matter interaction and optical element design.

Periodic orbits in irregular gravitational fields are significant for an understanding of dynamical behaviors around asteroids as well as the engineering aspect for deep space explorations. The rotating mass dipole, referred to as the Chermnykh problem, is a good alternative model to study qualitative dynamical environments near elongated asteroids, like the asteroid 1620 Geographos, 216 Kleopatra, or 25143 Itokawa. In this paper a global searching method is adopted to search for periodic orbits around the dipole model based on the concept of Poincare section of surface. Representative families of periodic orbits are illustrated with respect to all three topological cases of the dipole model. Topological transitions of orbits during iso-energetic continuations are also presented as well as identification of new types of periodic orbits.

A theoretical analysis is presented to investigate the orbital angular momentum (OAM) mode purity of microring-resonator-based integrated optical vortex emitters. By extending the dipole model for integrated vortex emitters, the influence of optical losses and grating imperfections on OAM mode purity of the output beam is investigated, thus clarifying the mode purity performance of the device in many practical scenarios. This work provides an efficient tool for the design of emitters with high OAM mode purity for optical communications or quantum information processing.