Resonant tunneling of electromagnetic waves through polariton gaps

We consider resonant tunneling of electromagnetic waves through an optical barrier formed by dielectric layers with the frequency dispersion of their dielectric permiability. The frequency region between lower and upper polariton branches in these materials presents a stop band for electromagnetic waves. We show that resonance tunneling through this kind of barriers is qualitatevely different from tunneling through other kind of optical barriers as well as from quantum mechanic tunneling through a rectangular barrier. We find that the width of the resonance maxima of the transmission coeffcient tends to zero as frequency approach the lower boundary of the stop band in a very sharp non-analytical way. Resonance transmission peaks give rise to new photonic bands inside the stop band if one considers periodical array of the layers.Comment: 8 pages, 5 figure

Testing for Time Dependence in Parameters

This paper proposes a new test based on a Fourier series expansion to approximate the unknown functional form of a nonlinear time-series model. The test specifically allows for structural breaks, seasonal parameters and time-varying parameters. The test is shown to have evry good size and power properties. However, it is not especially good in detecting nonlinearity in variables. As such, the test can help determine whether an observed rejection of the joint null hypothesis of linearity and time invariant parameters is due to time-varying coefficients of a nonliearity in variables.time varying parameters; fourier-series; nuisance parameters

Lorentz Invariant Superluminal Tunneling

It is shown that superluminal optical signalling is possible without violating Lorentz invariance and causality via tunneling through photonic band gaps in inhomogeneous dielectrics of a special kind.Comment: 10 pages revtex, no figure, more discussions added, submitted to Phys. Rev.

Deep Reinforcement Learning Applied to Spacecraft Attitude Control and Moment of Inertia Estimation via Recurrent Neural Networks

This study investigated two distinct problems related to unknown spacecraft inertia. The first problem explored the use of a recurrent neural network to estimate spacecraft moments of inertia using angular velocity measurements. Initial results showed that, for the configuration examined, the neural network can estimate the moments of inertia when there is a known external torque. The second problem trained a reinforcement learning agent, via proximal policy optimization, to control the attitude of a spacecraft. The results demonstrated that reinforcement learning may be a viable option for guidance and control solutions where the spacecraft model may be unknown. The trained agents displayed a degree of autonomy with their ability to recover from events never experienced in training

Die neuen Hochschulprofessionellen in Europa: Ausdifferenzierung und Aufgaben im internationalen Vergleich

In den vergangenen zwei Jahrzehnten mussten europäische Universitäten eine Vielzahl verschiedens-ter Anforderungen und Wandlungen bewältigen. Neben der Autonomisierung der Universitäten ge-hörten dazu vor allem die fortgesetzte Expansion der Hochschulsysteme, die Implementation der Bologna-Reformen, die Internationalisierung von Lehre und Forschung sowie die Einführung neuer Mechanismen zur Steuerung und Regulierung des Hochschulsektors. Universitäten sehen sich durch diese Veränderungen einer gesteigerten Komplexität gegenüber, die ihnen nicht nur ein höheres Maß an Verantwortlichkeit für ihr eigenes Handeln auferlegt, sondern es auch notwendig macht, dass Universitäten in der Lage sind, reflektierte Entscheidungen zu treffen. Dies setzt wiederum vo-raus, dass sie über entsprechende personelle Kapazitäten verfügen bzw. solche Kapazitäten entwi-ckeln, die sie in die Lage versetzen, den gesteigerten Anforderungen gerecht zu werden

Роль человеческого капитала в условиях перехода к экономике, основанной на знаниях

В данной статье рассматривается сущность экономики, основанной на знаниях. Отмечается, что именно человеческий капитал является основой для развития производства, промышленности и национальной экономики в целом. Наблюдается выход на первый план ценности человеческих способностей, знаний, приносящих доходность хозяйствующим субъектам. В работе выделяются основные проблемы развития экономики знаний

Multibarrier tunneling

We study the tunneling through an arbitrary number of finite rectangular opaque barriers and generalize earlier results by showing that the total tunneling phase time depends neither on the barrier thickness nor on the inter-barrier separation. We also predict two novel peculiar features of the system considered, namely the independence of the transit time (for non resonant tunneling) and the resonant frequency on the number of barriers crossed, which can be directly tested in photonic experiments. A thorough analysis of the role played by inter-barrier multiple reflections and a physical interpretation of the results obtained is reported, showing that multibarrier tunneling is a highly non-local phenomenon.Comment: RevTex, 7 pages, 1 eps figur

Tunneling dynamics in relativistic and nonrelativistic wave equations

We obtain the solution of a relativistic wave equation and compare it with the solution of the Schroedinger equation for a source with a sharp onset and excitation frequencies below cut-off. A scaling of position and time reduces to a single case all the (below cut-off) nonrelativistic solutions, but no such simplification holds for the relativistic equation, so that qualitatively different ``shallow'' and ``deep'' tunneling regimes may be identified relativistically. The nonrelativistic forerunner at a position beyond the penetration length of the asymptotic stationary wave does not tunnel; nevertheless, it arrives at the traversal (semiclassical or B\"uttiker-Landauer) time "tau". The corresponding relativistic forerunner is more complex: it oscillates due to the interference between two saddle point contributions, and may be characterized by two times for the arrival of the maxima of lower and upper envelops. There is in addition an earlier relativistic forerunner, right after the causal front, which does tunnel. Within the penetration length, tunneling is more robust for the precursors of the relativistic equation