277 research outputs found
Classical approach in quantum physics
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 Poincar 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"
ПРОБЛЕМЫ ОЦЕНКИ ЭФФЕКТИВНОСТИ ИНДИВИДУАЛЬНО-НАКОПИТЕЛЬНОЙ МОДЕЛИ ПЕНСИОННОГО СТРАХОВАНИЯ
Topic. The article presents the results of actuarial analysis of the newest and most controversial component of the Russian system of compulsory pension insurance — accrual one. The prospect of its further development is estimated. The effectiveness of this method of pension provision is assessed by the author from the point of view the role and degree of performance of the institutional functions of the state pension system (i.e., ensuring a decent level of material security of pensioners), and the possibility of achieving the targets formulated in 2012 in the government’s Strategy for the long-term development of the pension system of the Russian Federation.Purpose. Development of economically reasoned justification of real financial relations between participants of the insurance pension system within the framework of individual-accrual models of pension provision.Methodology. The main methodological feature and originality of this study is a multi-factor analysis, using methods of comparative analysis and actuarial forecasting of the whole set of conditions for the formation and implementation by insured persons of their pension rights in the individual-accrual model (both external to the pension system and internal as well), not carried out in other studies on this problem.Results.The article presents the results of economicstudies of the national practice of formation and implementation of pension rights of workers in the framework of the individual-accrual pension insurance program. Those results can be used in substantiating the directions of reforming the accrual methods of pension provision:The degree of direct dependence of the pension system efficiency on external macroeconomic and demographic factors is proved.We formulated criteria for evaluating the effectiveness of the accrual component of the pension system.It is given the characteristic and the main tasks of the accrual component of the compulsory pension insurance system.There are proposed measures to improve the functioning of the accrual component in the existing Russian reality and in the long term.Conclusions. The accrual method of formation and realization of pension rights in specific long-term socioeconomic conditions does not allow the main categories of insured persons to form the level of pensions provided in the solidarity system, and also sharply increases the budgetary risks not only of the Russian Pension Fund (PFR), but also of the Federal budget.В статье представлены результаты актуарного анализа состояния самого нового и наиболее спорного компонента российской системы обязательного пенсионного страхования — накопительного. Оценивается перспектива его дальнейшего развития. Эффективность данного способа пенсионного обеспечения оценивается автором по роли и степени выполнения институциональных функций государственной пенсионной системы (обеспечения достойного уровня материального благосостояния пенсионеров) и достижения ориентиров, заданных правительственной Стратегией долгосрочного развития пенсионной системы Российской Федерации2012 г.Цель статьи — выработка экономически аргументированного обоснования реальных финансовых отношений между участниками страховой пенсионной системы в рамках индивидуально-накопительных моделей пенсионного обеспечения.Главной методологической особенностью и оригинальностью данного исследования является многофакторный анализ с использованием методов сравнительного анализа и актуарного прогнозирования, всего комплекса условий формирования и реализации застрахованными лицами своих пенсионных прав в индивидуально-накопительной модели (как внешних по отношению к пенсионной системе, так и внутрисистемных), не проводившийся в других исследованиях, посвященных данной проблеме.В статье представлены результаты профессионально-экономических исследований отечественной практики формирования и реализации пенсионных прав работников в рамках индивидуально-накопительной программы пенсионного страхования, которые могут быть использованы при обосновании направлений реформирования накопительных способов пенсионного обеспечения:доказана степень непосредственной зависимости эффективности пенсионной системы от внешних макроэкономических и демографических факторов;выработаны критерии оценки эффективности накопительного компонента пенсионной системы;дана характеристика и сформулированы основные задачи накопительного компонента системы обязательного пенсионного страхования;предложены меры по совершенствованию порядка функционирования накопительного компонента в существующих российских реалиях и в долгосрочной перспективе.В результате исследования сделан вывод о том, что накопительный способ формирования и реализации пенсионных прав в конкретных долгосрочных социально-экономических условиях не позволяет основным категориям застрахованных лиц сформировать уровень пенсий, обеспечиваемый в солидарной системе, а также он резко увеличивает бюджетные риски не только ПФР, но и федерального бюджета
Non-sequential double ionization below laser-intensity threshold: Anticorrelation of electrons without excitation of parent ion
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
Incompressible magnetohydrodynamic modes in the thin magnetically twisted flux tube
Context. Observations have shown that twisted magnetic fields naturally occur, and indeed are omnipresent in the Sun’s atmosphere. It
is therefore of great theoretical interest in solar atmospheric waves research to investigate the types of magnetohydrodynamic (MHD)
wave modes that can propagate along twisted magnetic flux tubes.
Aims. Within the framework of ideal MHD, the main aim of this work is to investigate small amplitude incompressible wave modes
of twisted magnetic flux tubes with m ≥ 1. The axial magnetic field strength inside and outside the tube will be allowed to vary, to
ensure the results will not be restricted to only cold plasma equilibria conditions.
Methods. The dispersion equation for these incompressible linear MHD wave modes was derived analytically by implementing the
long wavelength approximation.
Results. It is shown, in the long wavelength limit, that both the frequency and radial velocity profile of the m = 1 kink mode are
completely unaffected by the choice of internal background magnetic twist. However, fluting modes with m ≥ 2 are sensitive to the
particular radial profile of magnetic twist chosen. Furthermore, due to background twist, a low frequency cut-off is introduced for
fluting modes that is not present for kink modes. From an observational point of view, although magnetic twist does not affect the
propagation of long wavelength kink modes, for fluting modes it will either work for or against the propagation, depending on the
direction of wave travel relative to the sign of the background twist
Free Boundary Poisson Bracket Algebra in Ashtekar's Formalism
We consider the algebra of spatial diffeomorphisms and gauge transformations
in the canonical formalism of General Relativity in the Ashtekar and ADM
variables. Modifying the Poisson bracket by including surface terms in
accordance with our previous proposal allows us to consider all local
functionals as differentiable. We show that closure of the algebra under
consideration can be achieved by choosing surface terms in the expressions for
the generators prior to imposing any boundary conditions. An essential point is
that the Poisson structure in the Ashtekar formalism differs from the canonical
one by boundary terms.Comment: 19 pages, Latex, amsfonts.sty, amssymb.st
Hadronic Regge Trajectories: Problems and Approaches
We scrutinized hadronic Regge trajectories in a framework of two different
models --- string and potential. Our results are compared with broad spectrum
of existing theoretical quark models and all experimental data from PDG98. It
was recognized that Regge trajectories for mesons and baryons are not straight
and parallel lines in general in the current resonance region both
experimentally and theoretically, but very often have appreciable curvature,
which is flavor-dependent. For a set of baryon Regge trajectories this fact is
well described in the considered potential model. The standard string models
predict linear trajectories at high angular momenta J with some form of
nonlinearity at low J.Comment: 15 pages, 9 figures, LaTe
Recommended from our members
Crown ethers: novel permeability enhancers for ocular drug delivery?
Crown ethers are cyclic molecules consisting of a ring containing several ether groups. The most common and important members of this series are 12-crown-4 (12C4), 15-crown-5 (15C5), and 18-crown-6 (18C6). These container molecules have the ability to sequester metal ions and their complexes with drugs are able to traverse cell membranes. This study investigated 12C4, 15C5 and 18C6 for their ability to increase solubility of ocular drugs and enhance their penetration into the cornea. Phase solubility analysis determined crown ethers’ ability to enhance the solubility of riboflavin, a drug used for the therapy of keratoconus, and these solutions were investigated for ocular drug permeation enhancing properties. Atomic absorption spectroscopy demonstrated crown ether solutions ability to sequester Ca2+ from corneal epithelia and crown ether mediated adsorption of riboflavin into the stroma was investigated. Induced corneal opacity studies assessed potential toxicity of crown ethers. Crown ethers enhanced riboflavin’s aqueous solubility and its penetration into in vitro bovine corneas; the smaller sized crown ethers gave greatest enhancement. They were shown to sequester Ca2+ ions from corneal epithelia, doing so loosens cellular membrane tight junctions thus enhancing riboflavin penetration. Induced corneal opacity was similar to that afforded by benzalkonium chloride and less than is produced using polyaminocarboxylic acids. However, in vivo experiments performed in rats with 12C4 did not show any statistically significant permeability enhancement compared to enhancer-free formulation
Modeling the Subsurface Structure of Sunspots
While sunspots are easily observed at the solar surface, determining their
subsurface structure is not trivial. There are two main hypotheses for the
subsurface structure of sunspots: the monolithic model and the cluster model.
Local helioseismology is the only means by which we can investigate
subphotospheric structure. However, as current linear inversion techniques do
not yet allow helioseismology to probe the internal structure with sufficient
confidence to distinguish between the monolith and cluster models, the
development of physically realistic sunspot models are a priority for
helioseismologists. This is because they are not only important indicators of
the variety of physical effects that may influence helioseismic inferences in
active regions, but they also enable detailed assessments of the validity of
helioseismic interpretations through numerical forward modeling. In this paper,
we provide a critical review of the existing sunspot models and an overview of
numerical methods employed to model wave propagation through model sunspots. We
then carry out an helioseismic analysis of the sunspot in Active Region 9787
and address the serious inconsistencies uncovered by
\citeauthor{gizonetal2009}~(\citeyear{gizonetal2009,gizonetal2009a}). We find
that this sunspot is most probably associated with a shallow, positive
wave-speed perturbation (unlike the traditional two-layer model) and that
travel-time measurements are consistent with a horizontal outflow in the
surrounding moat.Comment: 73 pages, 19 figures, accepted by Solar Physic
ДИАГНОСТИКА ТЕХНОЛОГИЧЕСКИХ ХАРАКТЕРИСТИК МОЩНЫХ ТРАНЗИСТОРОВ С ПОМОЩЬЮ РЕЛАКСАЦИОННОГО ИМПЕДАНС–СПЕКТРОМЕТРА ТЕПЛОВЫХ ПРОЦЕССОВ
The efficient method of determining thermal parameters in high-power field-effect transistors has been developed and tested based on a study of transient processes during self heating by direct current. With the developed relaxation spectrometer of thermal processes differential distribution profiles of thermal resistance of KP723G transistors have been investigated which were selected in accordance with the regimes of setting of their crystals. Thermal resistance spectra have been obtained from the analysis of time−dependent dynamic thermal impedance using a new non−destructive method of differential spectroscopy using higher order derivatives (order 3). We present both continuous (integral) and discrete spectra of the distribution of internal thermal resistance in the transistors and the value of the junction/case thermal resistance. Thermal characteristics of the KP723G transistors and their imported counterparts IRLZ44 and IRLB3036 have been determined. The method of determining the active area of devices has been developed and its decrease during heating has been shown. The proposed methodology is useful in solving technological problems of forming the setting layers of crystals and intermediate layers between a crystal and a heat sink and also for the development of thermal models in SPICE modeling of powerful MOSFETs and diode emitters.На основе исследования переходных процессов при саморазогреве прямым током разработан и апробирован эффективный метод определения тепловых параметров мощных полевых транзисторов. С помощью разработанного релаксационного спектрометра тепловых процессов исследованы дифференциальные профили распределения теплового сопротивления транзисторов КП723Г, подобранных в партии в соответствии с режимами посадки их кристаллов на теплоотводящее основание. Спектры тепловых сопротивлений рассчитаны из анализа временной зависимости динамического теплового импеданса новым неразрушающим методом дифференциальной спектроскопии с использованием производных высших порядков (3-го порядка). Представлены как непрерывные (интегральные), так и дискретные спектры распределения внутреннего теплового сопротивления транзисторов, а также значения теплового сопротивления переход—корпус. Определены тепловые характеристики транзисторов КП723Г и их импортных аналогов IRLZ44 и IRLB3036. Развит метод оценки активной площади приборов и установлено ее уменьшение с нагревом. Показано, что предложенные методики полезны при решении технологических проблем формирования слоев посадки кристаллов и создания промежуточных слоев между кристаллом и теплоотводящим основанием, а также для разработки тепловых моделей при SPICE-моделировании мощных полевых транзисторов и диодных излучателей
- …