Bond v. United States. Deciphering Missouri v. Holland and the Scope of Congress\u27s Powers when Implementing a Non-Self-Executing Treaty

This commentary previews an upcoming Supreme Court case, Bond v. United States. What started as an act of revenge by a jealous wife will require the Supreme Court to examine a ninety-year old precedent concerning the extent of Congress\u27s powers when acting pursuant to a treaty and whether a valid treaty allows Congress to act without being limited by the Article I enumerated powers

Latent segmentation of older adults in the use of social networks and e-banking services

Introduction. This study analyses heterogeneity in the online behaviour of elderly people. Previous research has centred on the socio-demographic segmentation of the elderly regarding their Internet use. Method. The novelty that this study adds is in determining this segmentation through variables that have been especially chosen for studies of the elderly and which are related to their utilitarian use of e-banking, compared to the more hedonic nature of using online social networks. Analysis. The sample was collected using 474 students over 55 years old enrolled in a class of experience in a University in the South of Europe (Spain). We use a latent class cluster model which is appropriate in situations of a posterior segmentation. Results. In dealing with such behaviour in situations of the elderly using these technologies, we have detected the presence of five groups or segments with highly differentiated use-related profiles concerning the variables analysed: venturesomeness, technology anxiety and selfconfidence in information and communication technologies use. Conclusion. We discover the existence of heterogeneity in the behaviour of the elderly regarding services available in Internet. The results support the idea proposed. The stereotype of the elderly cut off from technology is mistaken, as is shown by the different segments found

Large-signal theory of the effect of dispersive propagation on the intensity modulation response of semiconductor lasers

We have derived an exact large-signal theory of propagation in a dispersive fiber of an optical wave with sinusoidal amplitude and frequency modulation. This has been applied to the study of large-signal direct-modulation of semiconductor lasers. It is shown that the large-signal response can significantly deviate from the predictions of the small-signal theory. In particular, the improvement in modulation response caused by frequency-to-intensity modulation conversion in propagation that occurs with small-signal modulation is no longer achieved with large-signal modulation, which could affect systems such as dispersion supported transmission. Experimental results confirm our theory

Supermodes of grating-coupled multimode waveguides and application to mode conversion between copropagating modes mediated by backward Bragg scattering

An analysis of multimode waveguides where several modes are coupled via quasiperiodic perturbations is presented. The supermodes (or eigenmodes) of the structure are derived and orthonormality considerations are discussed. In addition, a new type of mode converter between copropagating modes is proposed, where mode conversion is mediated by a backward propagating mode. Adiabatic and nonadiabatic coupling coefficients are considered and the supermode formalism is used to conveniently describe the mode of operation of the device

Degradation of modulation and noise characteristics of semiconductor lasers after propagation in optical fiber due to a phase-shift induced by stimulated Brillouin scattering

Here we demonstrate theoretically that stimulated Brillouin scattering (SBS) can induce a phase shift of the optical carrier relative to its sidebands due to the waveguiding effect of the optical fiber on the acoustic wave. This causes conversion of frequency modulation to intensity modulation, which results in an increase in the relative intensity noise and degradation of the modulation response of directly modulated lasers after propagation in an optical fiber, in agreement with our experimental observations. Suppression of SBS can be achieved at low frequencies and high modulation powers due to the laser adiabatic chirp

Generalized Bloch wave analysis for fiber and waveguide gratings

We have developed a generalized Bloch wave approach for the analysis of aperiodic gratings. This method yields both a macroscopic (i.e., reflection or transmission coefficient) as well as a microscopic (i.e., dispersion diagram and microstructure of the propagating internal field) characterization of fiber and waveguide aperiodic gratings

Measurement and characterization of laser chirp of multiquantum-well distributed-feedback lasers

Measurements of relative intensity noise and modulation response, before and after propagation in optical fiber, of the output field of multiquantum-well distributed-feedback (MQW-DFB) lasers are used to determine the influence of the intraband damping mechanisms, the DFB structure and the carrier transport and carrier capture into the QWs on the laser chirp. The power dependence of the linewidth enhancement factor is shown to explain the saturation of the laser linewidth at high optical powers