Effective Hamiltonians in Nonrelativistic Quantum Electrodynamics

In this paper, we consider some second-order effective Hamiltonians describing the interaction of the quantum electromagnetic field with atoms or molecules in the nonrelativistic limit. Our procedure is valid only for off-energy-shell processes, specifically virtual processes such as those relevant for ground-state energy shifts and dispersion van der Waals and Casimir-Polder interactions, while on-energy-shell processes are excluded. These effective Hamiltonians allow for a considerable simplification of the calculation of radiative energy shifts, dispersion, and Casimir-Polder interactions, including in the presence of boundary conditions. They can also provide clear physical insights into the processes involved. We clarify that the form of the effective Hamiltonian depends on the field states considered, and consequently different expressions can be obtained, each of them with a well-defined range of validity and possible applications. We also apply our results to some specific cases, mainly the Lamb shift, the Casimir-Polder atom-surface interaction, and the dispersion interactions between atoms, molecules, or, in general, polarizable bodies.

Case-Marking in the Romance Languages

Case-marking is subject to several important developments in the passage from Latin to the Romance languages. With respect to synthetic marking, nouns and adjectives witness considerable simplification, leading (with some exceptions, i.e., the binary case systems) to the almost complete disappearance of inflectional case-marking, while pronouns continue to show consistent inflectional case-marking. In binary case systems, case distinctions are also marked in the inflection of determiners. Inflectional simplification is compensated for by the profusion of analytic and mixed case-marking strategies and by alternative strategies of encoding grammatical relations (see article on “Argument Marking in Romance” in this encyclopedia, forthcoming).

Holographic complexity of rotating black holes

Within the framework of the “complexity equals action” and “complexity equals volume” conjectures, we study the properties of holographic complexity for rotating black holes. We focus on a class of odd-dimensional equal-spinning black holes for which considerable simplification occurs. We study the complexity of formation, uncovering a direct connection between complexity of formation and thermodynamic volume for large black holes. We consider also the growth-rate of complexity, finding that at late-times the rate of growth approaches a constant, but that Lloyd’s bound is generically violated.

Recent Applications of Magnetic Nanoparticles in Food Analysis

Nanotechnology has become a topic of interest due to the outstanding advantages that the use of nanomaterials offers in many fields. Among them, magnetic nanoparticles (m-NPs) have been one of the most widely applied in recent years. In addition to the unique features of nanomaterials in general, which exclusively appear at nanoscale, these present magnetic or paramagnetic properties that result of great interest in many applications. In particular, in the area of food analysis, the use of these nanomaterials has undergone a considerable increase since they can be easily separated from the matrix in sorbent-based extractions, providing a considerable simplification of the procedures. This allows reducing cost and giving fast responses, which is essential in the food trade to guarantee consumer safety. These materials can also be easily tunable, providing higher selectivity. Moreover, their particular electrical, thermal and optical characteristics allow enhancing sensor signals, increasing the sensitivity of the approaches based on this type of device. The aim of this review article is to summarise the most remarkable applications of m-NPs in food analysis in the last five years (2016–2020) showing a general view of the use of such materials in the field.

La production des aciers inoxydables: Histoire de son développement et des procédés de fabrication. Partie III. Évolutions des méthodes de coulée et de mise en forme des aciers inoxydables

La coulée des aciers inoxydables, autrefois en lingots, s’effectue aujourd’hui par coulée continue. Ce mode de coulée a permis une considérable simplification de la gamme de fabrication (suppression du dégrossissage au blooming). La généralisation de la coulée continue aux aciers inoxydables fut assez tardive car il fallait satisfaire à deux impératifs qualitatifs essentiels : l’état de surface et la propreté inclusionnaire du métal déjà largement pris en compte par les affinages AOD et VOD. La complexité de la séquence de solidification des aciers inoxydables, notamment celle des aciers austénitiques, a aussi pesé sur le choix du mode de coulée. Le choix des outils de la filière coulée continue/mise en forme à chaud, pour les produits plats, est largement conditionné par le volume de production et par la proximité d’un train à bandes. Le laminoir Steckel a eu son utilité pour des productions de faibles volumes. Aujourd’hui les grandes usines en produits plats en aciers inoxydables ont des capacités suffisamment importantes pour leur dédier un train à bande (TAB) ; d’autres utilisent, en association, un train à bande pour aciers au carbone. La résolution des problèmes particuliers posés par la mise en forme à chaud des aciers inoxydables, notamment ceux liés au trou de ductilité à chaud des austénites, est décrite. Les cas particuliers de la mise en forme à chaud des tubes, des produits forgés sont évoqués. Les questions concernant la mise en forme à froid : laminage, emboutissage, écrouissage… sont abordées.

Генерация капельных квазибесселевых пучков при помощи полупроводникового лазера

A method for generation of droplet quasi-Bessel beams using a conical lens with a rounded tip is demonstrated. The study of the longitudinal distribution of the intensity of the obtained quasi-Bessel beam showed that, due to the interference of two wavefronts that occurred as the generating beam passed through the rounded axicon, periodical intensity pulsations that looked like “drops” of light occurred in the resulting beam. These light beams can be used for micromanipulation of biological objects and in super-resolution microscopy. The application of an axicon with a rounded tip for generation of a droplet beam allows considerable simplification and miniaturization of the experimental setup, which paves the way for multiple practical applications.

Nawiązania do tradycji nowożytnej w ceglanej architekturze wczesnomodernistycznej północnych Niemiec

One of the manifestations of the so called ‘conservative modernism’ was the reference to the brick building tradition in Northern Germany. The trend was primarily associated with the activities of Fritz Schumacher and Fritz Höger in Hamburg and Bremen in the 1920s and 1930s, but the genesis of this architecture dates back to the first decade of the 20th century and is associated with the attempts to shape North German patriotism. Just as in the art of neo-Gothic, brick architecture of ‘conservative modernism’ was meant to express the ‘North German Identity’, and in fact help in the creation of identities of the Bismarck Germany. Like the late neo-Gothic architecture, this architecture was perceived as a kind of ‘Hanseatic style’, reflecting the specificity (perceived in a mythologized way) of the Hanseatic League as a prefiguration of the New Germany and their power in maritime trade. Early-modern architecture continued to refer to the art of the past. However, the way of referring to the past changed: with only few quotes from the old art, with a considerable simplification of historical styles’ and so did the historical point of reference. In addition, the modernists became more interested in the brick building of the 17th and 18th centuries, the times of the Baroque and early Neoclassicism. Tis is evident in the works of the most important architects of North German modernism, including Fritz Höger, Fritz Schumacher, or Bruno Möhring but also works of lesser-known, though certainly interesting artists like Johann Garlef, Erich Blunck or Eugen Prinz. The interest of the North German architects of early modernism in brick construction is an element of a wider process that had been thriving in Northern Germany since the early 1900s. Interestingly enough, this process was equally intense in great artistic centres (Hamburg and Bremen) as well as in less-significant cities which were looking for their identity or tried to recreate it, as was the case in Kiel, Lubec or Szczecin. Tis paper is an attempt to show the evolution of this architecture and its most important features. The examples have been selected to show the most important characteristics of this architecture and its geographical range.

A New Approach for Semi-Analytical Solution of Cross-plane Phonon Transport in Silicon–Diamond Thin Films

Transient analysis of phonon cross-plane transport across two consecutively placed thin films is considered, and a new approach is introduced to obtain the semi-analytical solution for the equation of phonon radiative transport. The orthogonality properties of trigonometric functions are used in the mathematical analysis. Silicon and diamond thin films are used to resemble the consecutively placed thin films. The films are thermally disturbed from its edges to initiate the phonon transport, and thermal boundary resistance is introduced at the films interface. Equivalent equilibrium temperature is incorporated to quantify the phonon intensity distribution in the films. It is found that the results of the analytical solution agree well with their counterparts obtained from the numerical simulations. Phonon intensity at the film edges and interface reduces significantly due to boundary scattering. The analytical solution captures phonon scattering at boundaries and interface correctly, and provides considerable simplification of the numerical treatment of the equation for phonon radiative transport. It also reduces significantly the numerical efforts required for solving the transient phonon radiative transport equation pertinent to the cross-plan transport across the thin films in terms of program size and run-time.

Flow behavior in weakly permeable micro-tube with varying viscosity near the wall

Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.

Simplifying the one-loop five graviton amplitude in type IIB string theory

We consider the [Formula: see text] and [Formula: see text] terms in the low momentum expansion of the five graviton amplitude in type IIB string theory at one loop. They involve integrals of various modular graph functions over the fundamental domain of [Formula: see text]. Unlike the graphs which arise in the four graviton amplitude or at lower orders in the momentum expansion of the five graviton amplitude where the links are given by scalar Green functions, there are several graphs for the [Formula: see text] and [Formula: see text] terms where each of these two links are given by a derivative of the Green function. Starting with appropriate auxiliary diagrams, we show that these graphs can be expressed in terms of those which do not involve any derivatives. This results in considerable simplification of the amplitude.