386 research outputs found

    The hydrogen atom in electric and magnetic fields : Pauli's 1926 article

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    The results obtained by Pauli, in his 1926 article on the hydrogen atom, made essential use of the dynamical so(4) symmetry of the bound states. Pauli used this symmetry to compute the perturbed energy levels of an hydrogen atom in a uniform electric field (Stark effect) and in uniform electric and magnetic fields. Although the experimental check of the single Stark effect on the hydrogen atom has been studied experimentally, Pauli's results in mixed fields have been studied only for Rydberg states of rubidium atoms in crossedfields and lithium atoms in parallel fields.Comment: 11 pages, latex file, 2 figure

    Classical approach in quantum physics

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    The application of a classical approach to various quantum problems - the secular perturbation approach to quantization of a hydrogen atom in external fields and a helium atom, the adiabatic switching method for calculation of a semiclassical spectrum of hydrogen atom in crossed electric and magnetic fields, a spontaneous decay of excited states of a hydrogen atom, Gutzwiller's approach to Stark problem, long-lived excited states of a helium atom recently discovered with the help of Poincareˊ\acute{\mathrm{e}} section, inelastic transitions in slow and fast electron-atom and ion-atom collisions - is reviewed. Further, a classical representation in quantum theory is discussed. In this representation the quantum states are treating as an ensemble of classical states. This approach opens the way to an accurate description of the initial and final states in classical trajectory Monte Carlo (CTMC) method and a purely classical explanation of tunneling phenomenon. The general aspects of the structure of the semiclassical series such as renormgroup symmetry, criterion of accuracy and so on are reviewed as well. In conclusion, the relation between quantum theory, classical physics and measurement is discussed.Comment: This review paper was rejected from J.Phys.A with referee's comment "The author has made many worthwhile contributions to semiclassical physics, but this article does not meet the standard for a topical review"

    On foundations of quantum physics

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    Some aspects of the interpretation of quantum theory are discussed. It is emphasized that quantum theory is formulated in the Cartesian coordinate system; in other coordinates the result obtained with the help of the Hamiltonian formalism and commutator relations between 'canonically conjugated' coordinate and momentum operators leads to a wrong version of quantum mechanics. The origin of time is analyzed in detail by the example of atomic collision theory. It is shown that for a closed system like the three-body (two nuclei + electron) time-dependent Schroedinger equation has no physical meaning since in the high impact energy limit it transforms into an equation with two independent time-like variables; the time appears in the stationary Schroedinger equation as a result of extraction of a classical subsystem (two nuclei) from a closed three-body system. Following the Einstein-Rozen-Podolsky experiment and Bell's inequality the wave function is interpreted as an actual field of information in the elementary form. The relation between physics and mathematics is also discussed.Comment: This article is extended version of paper: Solov'ev, E.A.: Phys.At.Nuc. v. 72, 853 (2009

    Dynamics of quantum systems

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    A relation between the eigenvalues of an effective Hamilton operator and the poles of the SS matrix is derived which holds for isolated as well as for overlapping resonance states. The system may be a many-particle quantum system with two-body forces between the constituents or it may be a quantum billiard without any two-body forces. Avoided crossings of discrete states as well as of resonance states are traced back to the existence of branch points in the complex plane. Under certain conditions, these branch points appear as double poles of the SS matrix. They influence the dynamics of open as well as of closed quantum systems. The dynamics of the two-level system is studied in detail analytically as well as numerically.Comment: 21 pages 7 figure

    Spectral Properties of Single Crystals of Synthetic Diamond

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    The half-width of the spectrum of Raman scattering (RS) of the first order of a diamond single crystal grown in a nickel-free system containing nitrogen getters is identical to all growth sectors (1.69 ± 0.02 cm−1). The sectorial inhomogeneity is not reflected in the transmission spectra and birefringence of this crystal. The nitrogen concentration is 4⋅1017 cm−3. For different growth sectors of the diamond crystal grown in the Ni–Fe–C system, the half-width of the Raman line varies from 1.74 to 2.08 cm−1, differences in the transmission spectra and birefringence are observed, and photoluminescence is revealed. The concentration of nitrogen in the growth sectors {001} is 1.6⋅1019 cm−3, the content of nickel is estimated to be at a level of 1019 cm−3, and the content of nitrogen in the {111} sectors is 4⋅1019 cm−3

    Non-sequential double ionization below laser-intensity threshold: Anticorrelation of electrons without excitation of parent ion

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    Two-electron correlated spectra of non-sequential double ionization below laser-intensity threshold are known to exhibit back-to-back scattering of the electrons, viz., the anticorrelation of the electrons. Currently, the widely accepted interpretation of the anticorrelation is recollision-induced excitation of the ion plus subsequent field ionization of the second electron. We argue that another mechanism, namely simultaneous electron emission, when the time of return of the rescattered electron is equal to the time of liberation of the bounded electron (the ion has no time for excitation), can also explain the anticorrelation of the electrons in the deep below laser-intensity threshold regime. Our conclusion is based on the results of the numerical solution of the time-dependent Schr\"{o}dinger equation for a model system of two one-dimensional electrons as well as an adiabatic analytic model that allows for a closed-form solution.Comment: 6 pages and 3 figure

    Studies of Immunobiological Properties in <i>Francisella tularensis</i> Vaccine Strain 15 NIIEG under Extended Storage Conditions

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    Investigated have been 8 cultures of Francisella tularensis strain 15 NIIEG (lyophilized in 1953, 1966, 1969, 1987, 1990, 2003, 2012, and 2013, respectively) stored at the State Collection of Microorganisms of the Scientific Center on Expertise of Medical Application Products. It is established that the majority of cultures has maintained their immunobiological properties. However, it is of note that liophilization does not prevent F. tularensis strain 15 NIIEG from changes in its residual virulence under extended storage. Revealed is the fact that LD50 for 7 cultures of tularemia microbe strain is within the limits of 100-250 microbial cells (m.c.). At the same time, residual virulence for the strain which dates back 1966 is 7.3·105 m.c. Immunogenic activity rates in F. tularensis 15 NIIEG strain cultures range within specified limits. Apart from this, F. tularensis 1987 strain does not comply with the established requirements to the “specific safety”, as subcutaneous inoculation with 5·109 m.c./ml caused death of Guinea pigs within the scheduled observation time. Demonstrated is the necessity in maintaining constant stability of the original immunobiological properties in Francisella tularensis strain 15 NIIEG under extended storage conditions

    МИКРОБИОТА, ИММУННАЯ СИСТЕМА И КОЛОРЕКТАЛЬНЫЙ РАК

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    The article briefly considers physiological aspects of the human gut microbiota, associations between dysbiosis and colorectal cancer (CRC), disturbance of immune system in CRC, mechanisms of avoidance of immune surveillance by tumors, genetic instability in CRC, collisions and perspective of immunotherapy of CRC.В статье кратко рассматриваются физиологические аспекты микробиоты кишечника человека, связь дисбиоза с колоректальным раком (КРР), нарушения иммунной системы при развитии КРР, механизмы избегания опухолью иммунного надзора, варианты генетической нестабильности при КРР, коллизии и перспективы иммунотерапии при КРР
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