Tunneling and Non-Universality in Continuum Percolation Systems

The values obtained experimentally for the conductivity critical exponent in numerous percolation systems, in which the interparticle conduction is by tunnelling, were found to be in the range of $t_0$ and about $t_0+10$, where $t_0$ is the universal conductivity exponent. These latter values are however considerably smaller than those predicted by the available ``one dimensional"-like theory of tunneling-percolation. In this letter we show that this long-standing discrepancy can be resolved by considering the more realistic "three dimensional" model and the limited proximity to the percolation threshold in all the many available experimental studiesComment: 4 pages, 2 figure

Truth, trust, and civic duty:Cultural factors in citizens' perceptions of mobile phone apps and social media in disasters

This study investigates how citizens perceive the role of mobile phone apps specifically designed for disaster communication, and how these perceptions may differ from perceived roles and functions of social media in disaster-related tasks/situations. Focusing on trust in authorities and technology use, results suggest that social media use not only fosters trust via shared narratives and collective sense-making but may also improve trust relationships through local authorities assuming the function of a trustworthy information provider. In disaster apps usage, trust between citizens and authorities is generated through perceptions of shared responsibility rather than shared narratives. Apps were seen as mechanisms that reveal authorities' general willingness to share control, which may help overcome citizens' perceptions that they are distrusted by authorities.</p

Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research

This review discusses the current status of supermassive black hole research, as seen from a purely observational standpoint. Since the early '90s, rapid technological advances, most notably the launch of the Hubble Space Telescope, the commissioning of the VLBA and improvements in near-infrared speckle imaging techniques, have not only given us incontrovertible proof of the existence of supermassive black holes, but have unveiled fundamental connections between the mass of the central singularity and the global properties of the host galaxy. It is thanks to these observations that we are now, for the first time, in a position to understand the origin, evolution and cosmic relevance of these fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this version contains low resolution figures. The full resolution version can be downloaded from http://www.physics.rutgers.edu/~lff/publications.htm

The Lyman Alpha Forest in the Spectra of QSOs

Observations of redshifted Lyman alpha forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades optical spectroscopy with large ground-based telescopes, and more recently ultraviolet spectroscopy from space have yielded a wealth of information on what appears to be a gaseous, photoionized intergalactic medium, partly enriched by the products of stellar nucleosynthesis, residing in coherent structures over many hundreds of kiloparsecs. Recent progress with cosmological hydro-simulations based on hierarchical structure formation models has led to important insights into the physical structures giving rise to the forest. If these ideas are correct, a truely inter- and proto-galactic medium [at high redshift (z ~ 3), the main repository of baryons] collapses under the influence of dark matter gravity into flattened or filamentary structures, which are seen in absorption against background QSOs. With decreasing redshift, galaxies forming in the denser regions, may contribute an increasing part of the Lyman alpha absorption cross-section. Comparisons between large data samples from the new generation of telescopes and artificial Lyman alpha forest spectra from cosmological simulations promise to become a useful cosmological tool.Comment: latex plus three postscript figures, uses psfig,sty; Annual Review of Astronomy and Astrophysics 1998, vol. 36 (in press

Digital engagement methods for earthquake and fire preparedness:a review

Natural or human-made hazards may occur at any time. Although one might assume that individuals plan in advance for such potentially damaging events, the existing literature indicates that most communities remain inadequately prepared. In the past, research in this area has focused on identifying the most effective ways to communicate risk and elicit preparedness by means of public hazard education campaigns and risk communication programmes. Today, web- and mobile-based technologies are offering new and far-reaching means to inform communities on how to prepare for or cope with extreme events, thus significantly contributing to community preparedness. Nonetheless, their practical efficacy in encouraging proactive hazard preparedness behaviours is not yet proven. Building on behaviour change interventions in the health field and looking in particular at earthquakes and fire hazards, the challenging RISK team has reviewed the currently active websites, Web, and mobile applications that provide information about earthquake and home fire preparedness. The review investigates the type of information provided, the modality of delivery, and the presence of behaviour change techniques in their design. The study proves that most of the digital resources focus on a single hazard and fail to provide context-sensitive information that targets specific groups of users. Furthermore, behaviour change techniques are rarely implemented in the design of these applications and their efficacy is rarely systematically evaluated. Recommendations for improving the design of Web- and mobile-based technologies are made so as to increase their effectiveness and uptake for a multi-hazard approach to earthquake and home fire preparedness

Addressing ethical gaps in ‘Technology for Good’: Foregrounding care and capabilities

This paper identifies and addresses persistent gaps in the consideration of ethical practice in ‘technology for good’ development contexts. Its main contribution is to model an integrative approach using multiple ethical frameworks to analyse and understand the everyday nature of ethical practice, including in professional practice among ‘technology for good’ start-ups. The paper identifies inherent paradoxes in the ‘technology for good’ sector as well as ethical gaps related to (1) the sometimes-misplaced assignment of virtuousness to an individual; (2) difficulties in understanding social constraints on ethical action; and (3) the often unaccounted for mismatch between ethical intentions and outcomes in everyday practice, including in professional work associated with an ‘ethical turn’ in technology. These gaps persist even in contexts where ethics are foregrounded as matters of concern. To address the gaps, the paper suggests systemic, rather than individualized, considerations of care and capability applied to innovation settings, in combination with considerations of virtue and consequence. This paper advocates for addressing these challenges holistically in order to generate renewed capacity for change at a systemic level. </jats:p