Hydrogen atoms in circularly polarized microwave fields: Near-integrability and ionization

This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevA.52.1358.We have recently found that the hydrogen atom in a circularly polarized (CP) microwave field possesses an approximate dynamical symmetry and its bounded motion can be well described by a three-dimensional integrable (but nonseparable) Hamiltonian function with a velocity-dependent potential [Raković and Chu, Phys. Rev. A 50, 5077 (1994)]. This finding provides a theoretical foundation for the understanding of the origin of the regularity of Rydberg atom dynamics in CP fields. We describe here the phase space topology of the three-dimensional integrable system relevant to the microwave ionization of the hydrogen atoms in CP fields. Using the integrable system as an approximation to the real system and with the use of the two additional integrals of motion, we are able to trace the deformation of the tori up to the point of bifurcation (ionization). From this, we have determined the classical ionization-field threshold law fth≊1/cn40, where n0 is the principal quantum number of the initial state of the hydrogen atom and c is almost a constant (≊6 a.u.). These results are in good accord with the existing experimental observations

Approximate dynamical symmetry of hydrogen atoms in circularly polarized microwave fields

This is the published version, also available here: http://dx.doi.org/10.1103/PhysRevA.50.5077.We report the discovery of an integrable three-dimensional Hamiltonian system with a velocity-dependent potential. A two-dimensional restriction of that system is (for low frequencies) a good approximation of the motion (in the polarization plane) of the hydrogen atom in circularly polarized microwave fields. An additional integral of motion of the integrable two-dimensional system (being approximate invariant for the hydrogen atom in a circular field) is used in the calculation of the classical ionization field threshold. The result is consistent with all available experimental observations

Piecewise semi-ellipsoidal control invariant sets

Computing control invariant sets is paramount in many applications. The families of sets commonly used for computations are ellipsoids and polyhedra. However, searching for a control invariant set over the family of ellipsoids is conservative for systems more complex than unconstrained linear time invariant systems. Moreover, even if the control invariant set may be approximated arbitrarily closely by polyhedra, the complexity of the polyhedra may grow rapidly in certain directions. An attractive generalization of these two families are piecewise semi-ellipsoids. We provide in this paper a convex programming approach for computing control invariant sets of this family.Comment: 7 pages, 3 figures, to be published in IEEE Control Systems Letter

What is "system": some decoherence-theory arguments

We discuss the possibility of making the {\it initial} definitions of mutually different (possibly interacting, or even entangled) systems in the context of decoherence theory. We point out relativity of the concept of elementary physical system as well as point out complementarity of the different possible divisions of a composite system into "subsystems", thus eventually sharpening the issue of 'what is system'.Comment: 9 pages, no figure

The extraction of antioxidative compounds from rusks enriched with millet flour (Panicum miliaceum L.)

Two different ways of extracting antioxidative compounds (including soluble polyphenols) from rusks made from wheat flour with added millet (Panicum miliaceum L.) were compared, i.e., solvent extraction and in vitro digestion. Wheat flour was replaced by millet flour in amounts of 10, 20 or 30 wt. % (per dry mass). Solvent extraction was realized using a mixture of ethanol and water in different percentages, with or without the addition of formic acid. The total content of phenolic compounds (TPC) was determined using Folin-Ciocalteu reagent, while the antioxidative capacity was measured by the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay. The efficiency of solvent extraction was enhanced by the addition of formic acid. The addition of millet flour in amounts up to 20 % enhanced the antioxidative properties. It was shown that in vitro digestion was more efficient in the extraction of antioxidative compounds, in comparison with solvent extraction

Primena i provera sistema bezbednosti hrane

Historically, assuring that food is safe to eat included food inspection and laboratory testing of end product. Modern, nowdays food safety assurance system is designed to address potential food safety problems before they actually appear and at points of the food chain where they are expected to appear. In paper is discussed about the implementation and assessment of the Food Safety Management System

An in situ temperature calibration of a guarded hot plate apparatus

This paper presents design, development, and testing of a custom-made calibration environment for the calibration of temperature sensors applied in a guarded hot plate apparatus for thermal conductivity measurements. Description of an in situ calibration principle and realization are introduced. Results of numerical simulation, as well as those of experimental validation are given in a separate section of the paper. According to the results, proposed in situ calibration by using the applied guarded hot plate apparatus elements improves both accuracy and traceability the of thermal conductivity measurement. © 2018 Serbian Society of Heat Transfer Engineers

What is "system": the information-theoretic arguments

The problem of "what is 'system'?" is in the very foundations of modern quantum mechanics. Here, we point out the interest in this topic in the information-theoretic context. E.g., we point out the possibility to manipulate a pair of mutually non-interacting, non-entangled systems to employ entanglement of the newly defined '(sub)systems' consisting the one and the same composite system. Given the different divisions of a composite system into "subsystems", the Hamiltonian of the system may perform in general non-equivalent quantum computations. Redefinition of "subsystems" of a composite system may be regarded as a method for avoiding decoherence in the quantum hardware. In principle, all the notions refer to a composite system as simple as the hydrogen atom.Comment: 13 pages, no figure

Fononska toplotna provodnost tankih kristalnih filmova

In this paper we have analyzed phonon thermal conductivity of thin crystalline films, i.e. of low-dimensional structures with dimensional parameters significantly decreased in only one direction. Finding of coefficient of thermal conductivity is achieved by deriving phonon coefficient of diffusion, phonon specific heat and specific density for explored structure. Coefficient of diffusion is derived by applying method of Green functions, using Kubo formula. Then reduced thermal conductivities for film and bulk structures were compared for wider temperature interval. In the last section an influence of changes of heat conductivity on the boundaries is analyzed.U radu je analizirana fononska toplotna provodnost u kristalnim filmovima, tj. niskodimenzionim strukturama kod kojih su dimenzioni parametri značajno smanjeni samo u jednom pravcu. Određivanje koeficijenta toplotne provodnosti je vršeno određivanjem koeficijenta difuzije fonona, fononske specifične toplote i masene gustine za datu strukturu. Koeficijent difuzije je naen metodom Grinovih funkcija, korišćenjem Kubo formule. Izvršena su poređenja redukovanih toplotnih provodnosti filma i neprekidnih (balk) struktura za širi temperaturski interval. U poslednjem delu je analiziran uticaj promena na granicama na toplotnu provodnost