Overview of the coordinated ground-based observations of Titan during the Huygens mission

Coordinated ground-based observations of Titan were performed around or during the Huygens atmospheric probe mission at Titan on 14 January 2005, connecting the momentary in situ observations by the probe with the synoptic coverage provided by continuing ground-based programs. These observations consisted of three different categories: (1) radio telescope tracking of the Huygens signal at 2040 MHz, (2) observations of the atmosphere and surface of Titan, and (3) attempts to observe radiation emitted during the Huygens Probe entry into Titan's atmosphere. The Probe radio signal was successfully acquired by a network of terrestrial telescopes, recovering a vertical profile of wind speed in Titan's atmosphere from 140 km altitude down to the surface. Ground-based observations brought new information on atmosphere and surface properties of the largest Saturnian moon. No positive detection of phenomena associated with the Probe entry was reported. This paper reviews all these measurements and highlights the achieved results. The ground-based observations, both radio and optical, are of fundamental importance for the interpretation of results from the Huygens mission

My Land Is My Flesh Silver Bluff, the Creek Indians, and the Transformation of Colonized Space in Early America

This essay explores how Native peoples like the Creek (Muscogee) Indians invested colonized spaces in early American society with their own material, commercial, political, and spiritual meanings and importance. In particular, Creek Indians from the town of Coweta transformed Silver Bluff, the plantation of the trader and merchant George Galphin, into a “white ground,” as a place connected to Creek Country by a “white path,” and as a space where Creek and British leaders congregated to conduct business and negotiate politics. For it is no coincidence that the treaties of Augusta in 1763 and 1773, peaceful resolutions agreed to by the Creeks with the British Empire in 1760, 1764, 1773, 1774, and 1776, the negotiations over boundary lines in 1768 and 1774, and several other instances of cross-cultural dialogue all unfolded, started, or ended at Silver Bluff. The Creeks thereby enfolded occupied spaces like Silver Bluff—and the peoples who inhabited or congregated at such places—into their own worlds and according to their own understandings of those spaces. This process of spatial assimilation by the Creeks was as much collaborative as it was contested with Europeans throughout the eighteenth century

First-passage time for superstatistical Fokker-Planck models

The first-passage-time (FPT) problem is studied for superstatistical models assuming that the mesoscopic system dynamics is described by a Fokker-Planck equation. We show that all moments of the random intensive parameter associated to the superstatistical approach can be put in one-to-one correspondence with the moments of the FPT. For systems subjected to an additional uncorrelated external force, the same statistical information is obtained from the dependence of the FPT moments on the external force. These results provide an alternative technique for checking the validity of superstatistical models. As an example, we characterize the mean FPT for a forced Brownian particle.Fil: Budini, Adrian Adolfo. Universidad Tecnológica Nacional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Caceres Garcia Faure, Manuel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentin

Vector opinion dynamics in a model for social influence

We present numerical simulations of a model of social influence, where the opinion of each agent is represented by a binary vector. Agents adjust their opinions as a result of random encounters, whenever the difference between opinions is below a given threshold. Evolution leads to a steady state, which highly depends on the threshold and a convergence parameter of the model. We analyze the transition between clustered and homogeneous steady states. Results of the cases of complete mixing and small-world networks are compared.Comment: Latex file, 14 pages and 11 figures, Accepted in Physica

Anisotropic thermally activated diffusion in percolation systems

We present a study of static and frequency-dependent diffusion with anisotropic thermally activated transition rates in a two-dimensional bond percolation system. The approach accounts for temperature effects on diffusion coefficients in disordered anisotropic systems. Static diffusion shows an Arrhenius behavior for low temperatures with an activation energy given by the highest energy barrier of the system. From the frequency-dependent diffusion coefficients we calculate a characteristic frequency $\omega_{c}\sim 1/t_{c}$, related to the time $t_c$ needed to overcome a characteristic barrier. We find that $\omega_c$ follows an Arrhenius behavior with different activation energies in each direction.Comment: 5 pages, 4 figure

Job-search strategies of individuals at risk of poverty and social exclusion in Spain

In Spain, the issue of unemployment or precarious employment worsen with globalization, leading to an expansion of the so-called working poor in the labour market.According to previous literature, the economic poverty that is characteristic of this group may accompany poverty competency.In particular, the working poor resort to informal and poorly developed job-searchstrategies.This study addresses the job search methods used by people at risk of poverty and social exclusion. It provides evidence on the subject and serves as a basis for the adaptation of socio-labour intermediation programmes to this group.The hypothesis of this study is that people at high risk will predominantly use informal strategies that require a low level of job-searchs kills.A survey-based correlational study is conducted using a questionnaire completed by 279 people participating in socio-labourinter mediation programmes developed by the Action against Hunger Foundation(AaHF) in Spain.Information on poverty indicators and on job-search strategies is collected.Data are analysed through cluster analysis,which distinguish two groups of people at risk of poverty and social exclusion(high risk and low risk),followed by a comparison of means(t-test)with a subsequent calculation of effect size using Cohen’s d. Results show statistically significant differences with a medium effect size(between 0.45 and 0.50)for the typology of job-search strategies used,confirming the initial hypothesis.These results offer relevant information that should be considered when developing programmes aimed at improving social and labour issues for people at risk of poverty and social exclusion.Ministry of Economy and Competitiveness (MINECO- Government of Spain)European Regional Development Fund (ERDF-FEDER