University of Bremen

About: University of Bremen is a education organization based out in Bremen, Germany. It is known for research contribution in the topics: Population & Context (language use). The organization has 14563 authors who have published 37279 publications receiving 970381 citations. The organization is also known as: Universität Bremen.

Continuous Opinion Dynamics under Bounded Confidence: A Survey

Abstract: Models of continuous opinion dynamics under bounded confidence have been presented independently by Krause and Hegselmann and by Deffuant et al. in 2000. They have raised a fair amount of attention in the communities of social simulation, sociophysics and complexity science. The researchers working on it come from disciplines such as physics, mathematics, computer science, social psychology and philosophy. In these models agents hold continuous opinions which they can gradually adjust if they hear the opinions of others. The idea of bounded confidence is that agents only interact if they are close in opinion to each other. Usually, the models are analyzed with agent-based simulations in a Monte Carlo style, but they can also be reformulated on the agent's density in the opinion space in a master equation style. The contribution of this survey is fourfold. First, it will present the agent-based and density-based modeling frameworks including the cases of multidimensional opinions and heterogeneous bounds o...

Conceptualizing Mediatization: Contexts, Traditions, Arguments

Abstract: Why ‘mediatization’ as a topic for communication theory now? This rather ungainly word has been rising in prominence for the past decade, but many readers of this journal may still want to ask: What does it mean? What does it add to communications theory? And is it necessary at all? The purpose of this introduction to the special issue – apart from introducing and summarizing the articles that follow – is to provide some context for the emergence of ‘mediatization’ as a key theoretical concept for contemporary media and communications research, and to offer some reasons why it now deserves the full attention of scholars of communication theory.

ATMOSPHERIC REMOTE-SENSING REFERENCE DATA FROM GOME: PART 1. TEMPERATURE-DEPENDENT ABSORPTION CROSS-SECTIONS OF NO2 IN THE 231–794 nm RANGE

Abstract: Absorption cross sections of O3 in the 231–794 nm range have been measured at temperatures between 202 and 293 K using the Global Ozone Monitoring Experiment (GOME) Flight-Model (FM) satellite spectrometer. The GOME FM spectra have a spectral resolution of about 0.2 nm below 400 nm and of about 0.3 nm above 400 nm, and were recorded covering simultaneously the Hartley, Huggins, and Chappuis bands centered around 255, 340, and 610 nm, respectively. The variation of the O3 absorption cross sections was investigated over the entire spectral range 231–794 nm. The new cross sections are important as reference data for atmospheric remote-sensing of O3 and other trace gases.

Use of a Rapid Cytotoxicity Screening Approach To Engineer a Safer Zinc Oxide Nanoparticle through Iron Doping

Abstract: The establishment of verifiably safe nanotechnology requires the development of assessment tools to identify hazardous nanomaterial properties that could be modified to improve nanomaterial safety. While there is a lot of debate of what constitutes appropriate safety screening methods, one approach is to use the assessment of cellular injury pathways to collect knowledge about hazardous material properties that could lead to harm to humans and the environment. We demonstrate the use of a multiparameter cytotoxicity assay that evaluates toxic oxidative stress to compare the effects of titanium dioxide (TiO(2)), cerium oxide (CeO(2)), and zinc oxide (ZnO) nanoparticles in bronchial epithelial and macrophage cell lines. The nanoparticles were chosen on the basis of their volume of production and likelihood of spread to the environment. Among the materials, dissolution of ZnO nanoparticles and Zn(2+) release were capable of ROS generation and activation of an integrated cytotoxic pathway that includes intracellular calcium flux, mitochondrial depolarization, and plasma membrane leakage. These responses were chosen on the basis of the compatibility of the fluorescent dyes that contemporaneously assess their response characteristics by a semiautomated epifluorescence procedure. Purposeful reduction of ZnO cytotoxicity was achieved by iron doping, which changed the material matrix to slow Zn(2+) release. In summary, we demonstrate the utility of a rapid throughput, integrated biological oxidative stress response pathway to perform hazard ranking of a small batch of metal oxide nanoparticles, in addition to showing how this assay can be used to improve nanosafety by decreasing ZnO dissolution through Fe doping.