Research on Ternary Interactive Gatekeeping Model for Multi-Channel Networks (MCNs) in Social Media Era

In the digital content industry, the emerging multi-channel networks (MCNs) have dramatically changed the ways of content production and distribution in sustainable social media. As a result, it also brings an unprecedented impact and challenge to the traditional gatekeeping model, which play a vital role to describe and explain the reporting process regarding news events. In this paper, we propose a Ternary Interactive Gatekeeping (TIG) model and then discusse the gatekeeping behaviors of MCNs from the aspects of content production and distribution, which intend to integrate the roles of MCNs, content creators and social platforms all in one. In this way, MCNs are not only the intermediary, but also undertake the responsibility of gatekeeper in social media, which exerts the important role in online pseudo-environments. Semi-structured interviews are conducted with 15 interviewees that consist of the advertiser, creator, and staff in MCNs and platforms. For the content production, the gatekeeping behaviors of MCNs consist of selection, shaping and withholding. Those contents that satisfy the profits and development requirements of MCNs are chosen. For the content distribution, the gatekeeping behaviors of MCNs consist of display, timing and repetition, which aim to realize the high media exposure for Internet users. It can be seen that MCNs’ gatekeeping behaviors are affected by the business-logic. By the proposed gatekeeping scheme, we intend to provide a new perspective for future research on information management of social media.

The role of surface adhesion on the macroscopic wrinkling of biofilms

Biofilms, bacterial communities of cells encased by a self-produced matrix, exhibit a variety of three-dimensional structures. Specifically, channel networks formed within the bulk of the biofilm have been identified to play an important role in the colonies viability by promoting the transport of nutrients and chemicals. Here, we study channel formation and focus on the role of the adhesion of the biofilm matrix to the substrate in Pseudomonas aeruginosa biofilms grown under constant flow in microfluidic channels. We perform phase contrast and confocal laser scanning microscopy to examine the development of the biofilm structure as a function of the substrates surface energy. The formation of the wrinkles and folds is triggered by a mechanical buckling instability, controlled by biofilm growth rate and the film's adhesion to the substrate. The three-dimensional folding gives rise to hollow channels that rapidly increase the overall volume occupied by the biofilm and facilitate bacterial movement inside them. The experiments and analysis on mechanical instabilities for the relevant case of a bacterial biofilm grown during flow enable us to predict and control the biofilm morphology.

Global rates and patterns of channel migration in river deltas

River deltas are dynamic systems whose channels can widen, narrow, migrate, avulse, and bifurcate to form new channel networks through time. With hundreds of millions of people living on these globally ubiquitous systems, it is critically important to understand and predict how delta channel networks will evolve over time. Although much work has been done to understand drivers of channel migration on the individual channel scale, a global-scale analysis of the current state of delta morphological change has not been attempted. In this study, we present a methodology for the automatic extraction of channel migration vectors from remotely sensed imagery by combining deep learning and principles from particle image velocimetry (PIV). This methodology is implemented on 48 river delta systems to create a global dataset of decadal-scale delta channel migration. By comparing delta channel migration distributions with a variety of known external forcings, we find that global patterns of channel migration can largely be reconciled with the level of fluvial forcing acting on the delta, sediment flux magnitude, and frequency of flood events. An understanding of modern rates and patterns of channel migration in river deltas is critical for successfully predicting future changes to delta systems and for informing decision makers striving for deltaic resilience.

Protegendo Redes de Canais de Pagamento Sem Fio com Janelas de Tempo de Bloqueio Mínimas

Redes de canais de pagamento (Payment Channel Networks - PCN) aumentam o impacto das criptomoedas, fornecendo uma solução rápida e independente de consenso para mitigar os problemas de escalabilidade dos protocolos tradicionais de correntes de blocos (blockchain). No entanto, as PCNs atuais são baseadas em nós robustos com alta disponibilidade e capacidade computacional, dificultando sua adoção em ambientes móveis e sem fio. Este artigo propõe uma arquitetura PCN híbrida que estende as funcionalidades das PCNs tradicionais para cenários de dispositivos sem fio com recursos limitados. O artigo analisa a vulnerabilidade de roubo de tokens e propõe uma contramedida com base em janelas de tempo de bloqueio. O artigo avalia a proposta com dados reais da Lightning Network e de redes de banda larga móvel. Os resultados mostram que a janela de tempo mínimo de bloqueio depende do tempo de inatividade dos dispositivos e que selecionar uma janela padrão é mais eficaz quando os dispositivos apresentam alta disponibilidade.