On the origin dependence of multipole moments in electromagnetism

The standard description of material media in electromagnetism is based on multipoles. It is well known that these moments depend on the point of reference chosen, except for the lowest order. It is shown that this "origin dependence" is not unphysical as has been claimed in the literature but forms only part of the effect of moving the point of reference. When also the complementary part is taken into account then different points of reference lead to different but equivalent descriptions of the same physical reality. This is shown at the microscopic as well as at the macroscopic level. A similar interpretation is valid regarding the "origin dependence" of the reflection coefficients for reflection on a semi infinite medium. We show that the "transformation theory" which has been proposed to remedy this situation (and which is thus not needed) is unphysical since the transformation considered does not leave the boundary conditions invariant.Comment: 14 pages, 0 figure

Let’s do the time warp again – embodied learning of the concept of time in an applied school setting

This article has been accepted for publication in Interactive Learning Environments, published by Taylor & Francis. Embodied Cognition approaches suggest that movements influence the understanding of abstract concepts such as time. It follows that moving the arms as watch hands should boost children’s learning to read the clock. In a school setting, we compared three learning conditions: an embodied (movement) condition, an interactive App condition, and a text condition. Age, self-reported enjoyment, and group size were controlled. In a clock-time-test, the embodied condition resulted in better performances than the mean of the other conditions in small, but not in large groups. This innovative, theory-informed approach may advance learning of abstract concepts in children

Industrija čelika u novim članicama EU u usporedbi s globalnim trendovima

Accession of the metallurgically significant countries of the Central and Eastern Europe to the EU in 2004 was conditioned by fulfilling the Restructuring Programs as the foundation for achievement of competitiveness and guarancy of viability. The Restructuring Programs, which fulfilling and regular monitoring had lasted 5 years, demonstrated the right of the significant position of the steel industry in the new EU members, especially in Poland, Czech Republic, Slovakia, and in Hungary. The objective of the article is to point to the key elements in context of steel industry global trends, regarding either production or especially utility values and total consumption. In this connection, privatization took an important role too.Prinos metalurgije glavnih zemalja Srednje i Istočne Europe u EU u 2004. je bilo ostvarenje restrukturiranja programa kao temelj za postizanje konkurentnosti i jamstvo opstanka. Restrukturiranje programa, provedba i redovito praćenj za 5 godina opravdalo je značajno mjesto u industriji čelika u novim zemljama EU, naročito u Poljskoj, Češkoj, Slovačkoj i Mađarskoj. Ovaj članak ima za cilj istaknuti ključne elemente u razvojnom konextu industrija čelika u svijetu, kako u pogledu proizvodnje, a posebice u odnosu na kvalitete i ukupnu potrošnju. Važan element u tom pogledu, nastavak privatizacije

Electromagnetic multipole theory for optical nanomaterials

Optical properties of natural or designed materials are determined by the electromagnetic multipole moments that light can excite in the constituent particles. In this work we present an approach to calculate the multipole excitations in arbitrary arrays of nanoscatterers in a dielectric host medium. We introduce a simple and illustrative multipole decomposition of the electric currents excited in the scatterers and link this decomposition to the classical multipole expansion of the scattered field. In particular, we find that completely different multipoles can produce identical scattered fields. The presented multipole theory can be used as a basis for the design and characterization of optical nanomaterials

Motional sidebands and direct measurement of the cooling rate in the resonance fluorescence of a single trapped ion

Resonance fluorescence of a single trapped ion is spectrally analyzed using a heterodyne technique. Motional sidebands due to the oscillation of the ion in the harmonic trap potential are observed in the fluorescence spectrum. From the width of the sidebands the cooling rate is obtained and found to be in agreement with the theoretical prediction.Comment: 4 pages, 4 figures. Final version after minor changes, 1 figure replaced; to be published in PRL, July 10, 200

Magnetic dipole moments in single and coupled split-ring resonators

We examine the role of magnetic dipoles in single and coupled pairs of metallic split-ring resonators by numerically computing their magnitude and examining their relative contributions to the scattering cross section. We demonstrate that magnetic dipoles can strongly influence the scattering cross section along particular directions. It is also found that the magnetic dipole parallel to the incident magnetic field and/or high-order multipoles may play a significant role in the linear response of coupled split-ring resonators.Comment: 7 pages, 3 figures, 1 tabl

Effects of visual blur and contrast on spatial and temporal precision in manual interception.

The visual system is said to be especially sensitive towards spatial but lesser so towards temporal information. To test this, in two experiments, we systematically reduced the acuity and contrast of a visual stimulus and examined the impact on spatial and temporal precision (and accuracy) in a manual interception task. In Experiment 1, we blurred a virtual, to-be-intercepted moving circle (ball). Participants were asked to indicate (i.e., finger tap) on a touchscreen where and when the virtual ball crossed a ground line. As a measure of spatial and temporal accuracy and precision, we analyzed the constant and variable errors, respectively. With increasing blur, the spatial and temporal variable error, as well as the spatial constant error increased, while the temporal constant error decreased. Because in the first experiment, blur was potentially confounded with contrast, in Experiment 2, we re-ran the experiment with one difference: instead of blur, we included five levels of contrast matched to the blur levels. We found no systematic effects of contrast. Our findings confirm that blurring vision decreases spatial precision and accuracy and that the effects were not mediated by concomitant changes in contrast. However, blurring vision also affected temporal precision and accuracy, thereby questioning the generalizability of the theoretical predictions to the applied interception task. [Abstract copyright: © 2021. The Author(s).

Multipole nonlinearity of metamaterials

We report on the linear and nonlinear optical response of metamaterials evoked by first and second order multipoles. The analytical ground on which our approach bases permits for new insights into the functionality of metamaterials. For the sake of clarity we focus here on a key geometry, namely the split-ring resonator, although the introduced formalism can be applied to arbitrary structures. We derive the equations that describe linear and nonlinear light propagation where special emphasis is put on second harmonic generation. This contribution basically aims at stretching versatile and existing concepts to describe light propagation in nonlinear media towards the realm of metamaterials.Comment: 7 pages, 3 figure

A Lifespan Perspective on Embodied Cognition

Since its infancy embodied cognition research has fundamentally changed our understanding of how action, perception, and cognition relate to and interact with each other. Ideas from different schools of thought have led to controversial theories and a unifying framework is still being debated. In this perspective paper, we argue that in order to improve our understanding of embodied cognition and to take significant steps toward a comprehensive framework, a lifespan approach is mandatory. Given that most established theories have been developed and tested in the adult population, which is characterized by relatively robust and stable sensorimotor and cognitive abilities, we deem it questionable whether embodied cognition effects found in this population are representative for different life stages such as childhood or the elderly. In contrast to adulthood, childhood is accompanied by a rapid increase of sensorimotor and cognitive skills, and the old age by a decline of such capacities. Hence, sensorimotor and cognitive capacities, as well as their interactions, are more fragile at both extremes of the lifespan, thereby offering a unique window into the emergence of embodied cognition effects and age-related differences therein. A lifespan approach promises to make a major contribution toward a unifying and comprehensive theory of embodied cognition that is valid across the lifespan and ‘gets better with age.

Walking back to the future: The impact of walking backward and forward on spatial 2 and temporal concepts

Embodied cognition frameworks suggest a direct link between sensorimotor experience and cognitive representations of concepts (Shapiro, 2011). We examined whether this holds also true for concepts that cannot be directly perceived with the sensorimotor system (i.e., temporal concepts). To test this, participants learned object–space (Exp. 1) or object–time (Exp. 2) associations. Afterwards, participants were asked to assign the objects to their location in space/time meanwhile they walked backward, forward, or stood on a treadmill. We hypothesized that walking backward should facilitate the on-line processing of ”behind”/“past”-related stimuli, but hinder the processing of “ahead”/“future”-related stimuli, and a reversed effect for forward walking. Indeed, “ahead”- and “future”-related stimuli were processed slower during backward walking. During forward walking and standing, stimuli were processed equally fast. The results provide partial evidence for the activation of specific spatial and temporal concepts by whole-body movements and are discussed in the context of movement familiarity