Collective and Single-particle Motion in Beyond Mean Field Approaches

We present a novel nuclear energy density functional method to calculate spectroscopic properties of atomic nuclei. Intrinsic nuclear quadrupole deformations and rotational frequencies are considered simultaneously as the degrees of freedom within a symmetry conserving configuration mixing framework. The present method allows the study of nuclear states with collective and single-particle character. We calculate the fascinating structure of the semi-magic 44S nucleus as a first application of the method, obtaining an excellent quantitative agreement both with the available experimental data and with state-of-the-art shell model calculations.Comment: 5 pages, 4 figures, accepted for publication in Phys. Rev. Let

Time-frequency characterization of a sound propagation channel as an educational tool

This paper discusses the use of sound waves to illustrate multipath radio propagation concepts. Specifically, a procedure is presented to measure the time-varying frequency response of the channel. This helps demonstrate how a propagation channel can be characterized in time and frequency, and provides visualizations of the concepts of coherence time and coherence bandwidth. The measurements are very simple to carry out, and the required equipment is easily available. The proposed method can be useful for wireless or mobile communication courses

Large amplitude pairing fluctuations in atomic nuclei

Pairing fluctuations are self-consistently incorporated on the same footing as the quadrupole deformations in present state of the art calculations including particle number and angular momentum conservation as well as configuration mixing. The approach is complemented by the use of the finite range density dependent Gogny force which, with a unique source for the particle-hole and particle-particle interactions, guarantees a self-consistent interplay in both channels. We have applied our formalism to study the role of the pairing degree of freedom in the description of the most relevant observables like spectra, transition probabilities, separation energies, etc. We find that the inclusion of pairing fluctuations mostly affects the description of excited states, depending on the excitation energy and the angular momentum. $E0$ transition probabilities experiment rather big changes while $E2$'s are less affected. Genuine pairing vibrations are thoroughly studied with the conclusion that deformations strongly inhibits their existence. These studies have been performed for a selection of nuclei: spherical, deformed and with different degree of collectivity.Comment: 23 pages, 23 Figures, To be published in Phys. Rev.

Illustrating multipath propagation by means of sound waves

A method is presented that uses sound waves to illustrate multipath propagation concepts. This is based on the existing analogy between radio and sound waves, and has the advantage that the required equipment is easily available. Different measurement techniques are introduced to respectively examine time dispersion, time variation, and both aspects of the multipath channel simultaneously. The proposed techniques are justified, example results are given, and the specific features that are illustrated by each type of measurement are discussed. Suggestions are given regarding application in courses on wireless communications

Using the Spectrum Analyzer as an Educational Tool for Mobile Communications

Application of the spectrum analyzer for illustrating several concepts associated with mobile communications is discussed. Specifically, two groups of observable features are described. First, time variation and frequency selectivity of multipath propagation can be revealed by carrying out simple measurements on commercial-network GSM and UMTS signals. Second, the main time-domain and frequency-domain features of GSM and UMTS radio signals can be observed. This constitutes a valuable tool for teaching mobile communication courses

Estimation of a Probability with Guaranteed Normalized Mean Absolute Error

The estimation of a probability p from repeated Bernoulli trials is considered in this letter. A sequential approach is followed, using a simple stopping rule. A closed-form expression and an upper bound are obtained for the mean absolute error of the unbiased estimator of p. The results given permit the estimation of an arbitrary probability with a prescribed level of normalized mean absolute error

Triaxial Angular Momentum Projection and Configuration Mixing calculations with the Gogny force

We present the first implementation in the $(\beta,\gamma)$ plane of the generator coordinate method with full triaxial angular momentum and particle number projected wave functions using the Gogny force. Technical details about the performance of the method and the convergence of the results both in the symmetry restoration and the configuration mixing parts are discussed in detail. We apply the method to the study of $^{24}$Mg, the calculated energies of excited states as well as the transition probabilities are compared to the available experimental data showing a good overall agreement. In addition, we present the RVAMPIR approach which provides a good description of the ground and gamma bands in the absence of strong mixing.Comment: 40 pages,14 figure

Framing Effects in Public Goods: Prospect Theory and Experimental Evidence

This paper studies, both theoretically and experimentally, frame effects in the context of a public good game in which players have to make a costly contribution either i) to achieve or ii) not to lose a non excludable monetary prize. Our protocol leads to public good provision (not deterioration) only if a certain contribution level is achieved. Since both frames differ with respect to the reference point, we use Prospect Theory to derive testable predictions. In particular, Prospect Theory predicts more contribution in the second frame. Our evidence suggests that a) subjects¿ behavior is highly sensitive to frames and b) the theoretical prediction is confirmed except when the threshold is low. We also estimate the parameters which better suit our experimental evidence, partly confirming previous results in the literature.Public goods provision, framing, prospect theory

Land Policies and Labour Markets in Sub?Saharan Africa: A Law and Economics Analysis

This article examines foreign agricultural investment contracts and their potential to contribute to alleviating unemployment and underemployment particularly of young people in sub?Saharan Africa. This investment trend has accelerated rapidly since the 2008 food crisis to over 56 million hectares. Law and economics methodologies are applied to analyse this phenomenon. The article outlines the labour market situation in sub?Saharan Africa and investment policies in agriculture. Public choice theory is applied to understand why agricultural projects are producing unintended negative effects. This article also analyses signed contracts to evaluate whether they can improve the actual labour market situation. It found that it is not possible, from the rational theory viewpoint, that such instruments will contribute to the creation of new jobs for the local youth and promote development. It contends that effective national and international legal institutions need to be created to enforce social clauses with strong participation of local youth and their representatives