Spin effects in Kapitza-Dirac scattering at light with elliptical polarization

The Kapitza-Dirac effect, which refers to electron scattering at standing light waves, is studied in the Bragg regime with counterpropagating elliptically polarized electromagnetic waves with the same intensity, wavelength, and degree of polarization for two different setups. In the first setup, where the electric-field components of the counterpropagating waves have the same sense of rotation, we find distinct spin effects. The spins of the scattered electrons and of the nonscattered electrons, respectively, precess with a frequency that is of the order of the Bragg-reflection Rabi frequency. When the electric-field components of the counterpropagating waves have an opposite sense of rotation, which is the second considered setup, the standing wave has linear polarization, and no spin effects can be observed. Our results are based on numerical solutions of the time-dependent Dirac equation and the analytical solution of a relativistic Pauli equation, which accounts for the leading relativistic effects

Circular business strategies and supply chain finance in the Aruba waste sector : a case study of a small island jurisdiction

This paper focuses on possibilities and obstacles for a circular economy in the waste management sector in Aruba. The authors describe the Aruban economy and the consequences of its SIDS characteristics. The article defines concepts in the field of circular economy and presents a conceptual model for research in this area. Based on multimethod research, the paper argues that small and medium-sized firms (SMEs) in the waste sector in Aruba determine their financial needs partly on the opportunities offered by the international market and price developments. Financing often takes place from own resources or via a local bank. No examples of circular chain financing were identified. Chain cooperation takes place with partners within the existing holding or with international partners, whereby performance and hedging contracts are concluded to guarantee quality and delivery and to mitigate business risks such as price fluctuations on the world market. During the research, it became obvious that limitations resulting from Aruba’s small scale and ‘islandness’ – such as the limited goods flow, limited quantities of feed waste materials and financing facilities offered by the local banking sector, as well as insufficiently stimulating legislation and regulations, coupled with faltering knowledge circulation and social awareness – seriously hamper the development of circular entrepreneurism in Aruba. The article offers policy recommendations to mitigate the bottlenecks for sustainable development in Aruba.peer-reviewe

Pseudo Random Coins Show More Heads Than Tails

Tossing a coin is the most elementary Monte Carlo experiment. In a computer the coin is replaced by a pseudo random number generator. It can be shown analytically and by exact enumerations that popular random number generators are not capable of imitating a fair coin: pseudo random coins show more heads than tails. This bias explains the empirically observed failure of some random number generators in random walk experiments. It can be traced down to the special role of the value zero in the algebra of finite fields.Comment: 10 pages, 12 figure

Accelerating the Fourier split operator method via graphics processing units

Current generations of graphics processing units have turned into highly parallel devices with general computing capabilities. Thus, graphics processing units may be utilized, for example, to solve time dependent partial differential equations by the Fourier split operator method. In this contribution, we demonstrate that graphics processing units are capable to calculate fast Fourier transforms much more efficiently than traditional central processing units. Thus, graphics processing units render efficient implementations of the Fourier split operator method possible. Performance gains of more than an order of magnitude as compared to implementations for traditional central processing units are reached in the solution of the time dependent Schr\"odinger equation and the time dependent Dirac equation

Does a Better Job Match Make Women Happier?: Work Orientations, Work-Care Choices and Subjective Well-Being in Germany

The study examines the effects of work orientations and work-leisure choices alongside the effect of genes or personality traits on subjective well-being (SWB). The former effects are assumed to be mediated by the match between women's preferred and actual number of working hours indicating labor market and time constraints. Data come from 24 waves of the German (SOEP) Household Panel (1984-2007). Random and fixed-effect panel regression models are estimated. Work orientations and work-leisure choices indeed matter for women's SWB but the effects are strongly mediated by the job match especially for younger birth cohorts and higher educated women. Therefore, apart from the impact of genes or personality traits preferences and choices as well as labor market and time constraints matter significantly for the well-being of women, providing partial support to the role (scarcity-expansion) theory and the combination pressure thesis while at the same time challenging set-point theory.Subjective well-being, set-point theory, life satisfaction, preference formation theory, role (scarcity-expansion) theory, job match, work-leisure choices, panel regression models

Electron-spin dynamics in elliptically polarized light waves

We investigate the coupling of the spin angular momentum of light beams with elliptical polarization to the spin degree of freedom of free electrons. It is shown that this coupling, which is of similar origin as the well-known spin-orbit coupling, can lead to spin precession. The spin-precession frequency is proportional to the product of the laser-field's intensity and its spin density. The electron-spin dynamics is analyzed by employing exact numerical methods as well as time-dependent perturbation theory based on the fully relativistic Dirac equation and on the nonrelativistic Pauli equation that is amended by a relativistic correction that accounts for the light's spin density