901 research outputs found

    Studies of opinion stability for small dynamic networks with opportunistic agents

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    There are numerous examples of societies with extremely stable mix of contrasting opinions. We argue that this stability is a result of an interplay between society network topology adjustment and opinion changing processes. To support this position we present a computer model of opinion formation based on some novel assumptions, designed to bring the model closer to social reality. In our model, the agents, in addition to changing their opinions due to influence of the rest of society and external propaganda, have the ability to modify their social network, forming links with agents sharing the same opinions and cutting the links with those they disagree with. To improve the model further we divide the agents into `fanatics' and `opportunists', depending on how easy is to change their opinions. The simulations show significant differences compared to traditional models, where network links are static. In particular, for the dynamical model where inter-agent links are adjustable, the final network structure and opinion distribution is shown to resemble real world observations, such as social structures and persistence of minority groups even when most of the society is against them and the propaganda is strong.Comment: Revised version accepted by International Journal of Modern Physics C Added analysis, references and a new figur

    Carbon export and regeneration in the coastal upwelling system of Monterey Bay, central California

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    In order to quantify the role of coastal upwelling regions as source or sink areas for carbon, the relationships between particulate organic carbon (POC) production, export, remineralization, and accumulation were examined in Monterey Bay from 1989 through 1992. During a normal upwelling year (1989–90), a high positive correlation (r = 0.91) is observed between biweekly primary production and POC export at 450 m. Primary production values range from 500 mgC m−2 d−1 during the winter, to 2600 mgC m−2 d−1 in the spring and summer upwelling months. Corresponding deep-water (450 m) POC fluxes vary from a minimum of 10 mgC m−2 d−1 in December, to 120 mgC m−2 d−1 in May. In contrast, the mid-1991 through 1992 data sets obtained during the \u2791–92 El Nino period, show a relatively poor correlation (r = 0.23) between productivity and carbon export. Calculated ratios of POC export to POC production (defined as e-ratios) display a trend for the three-year data sets in which the e-ratio values are greatest during periods of low productivity and decrease to minimal values when surface production is high. Upwelling-induced, offshore Ekman transport of organic matter and probable seasonal changes in the planktonic community structure are the mechanisms likely to be responsible for the e-ratio trends. Based on the data sets reported from this work, a simple box model of the annual export and regeneration of particulate organic carbon is presented for the Monterey Bay region. An appreciable advective and/or recycling “loss” from the euphotic zone of 362.8 gC m−2 y−1 is estimated, representing primarily algal material transported offshore and/or recycled within the upper 100 m of the water column. Annual mid-water (≈100– 450 m) and deep-water (\u3e450 m) POC remineralization rates of 71.8 gC m−2 y−1 of 7.2 gC m−2 y−1, respectively, are reported for Monterey Bay. The average POC rain rate to the underlying slope sediments is sufficient to satisfy reported benthic utilization requirements without invoking an additional input source of POC via deep lateral advection and/or the downslope movement of particulate material

    Distribution of extracellular flavins in a coastal marine basin and their relationship to redox gradients and microbial community members

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    The flavins (including flavin mononucleotide (FMN) and riboflavin (RF)) are a class of organic compounds synthesized by organisms to assist in critical redox reactions. While known to be secreted extracellularly by some species in laboratory-based cultures, flavin concentrations are largely unreported in the natural environment. Here, we present pore water and water column profiles of extracellular flavins (FMN and RF) and two degradation products (lumiflavin and lumichrome) from a coastal marine basin in the Southern California Bight alongside ancillary geochemical and 16S rRNA microbial community data. Flavins were detectable at picomolar concentrations in the water column (93–300 pM FMN, 14–40 pM RF) and low nanomolar concentrations in pore waters (250–2070 pM FMN, 11–210 pM RF). Elevated pore water flavin concentrations displayed an increasing trend with sediment depth and were significantly correlated with the total dissolved Fe (negative) and Mn (positive) concentrations. Network analysis revealed a positive relationship between flavins and the relative abundance of Dehalococcoidia and the MSBL9 clade of Planctomycetes, indicating possible secretion by members of these lineages. These results suggest that flavins are a common component of the so-called shared extracellular metabolite pool, especially in anoxic marine sediments where they exist at physiologically relevant concentrations for metal oxide reduction

    Temporal evolution of shallow marine diagenetic environments: Insights from carbonate concretions

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    Early diagenesis of marine organic matter dramatically impacts Earth's surface chemistry by changing the burial potential of carbon and promoting the formation of authigenic mineral phases including carbonate concretions. Marine sediment-hosted carbonate concretions tend to form as a result of microbial anaerobic diagenetic reactions that degrade organic matter and methane, some of which require an external oxidant. Thus, temporal changes in the oxidation state of Earth's oceans may impart a first-order control on concretion authigenesis mechanisms through time. Statistically significant variability in concretion carbonate carbon isotope compositions indicates changes in shallow marine sediment diagenesis associated with Earth's evolving redox landscape. This variability manifests itself as an expansion in carbon isotope composition range broadly characterized by an increase in maximum and decrease in minimum isotope values through time. Reaction transport modelling helps to constrain the potential impacts of shifting redox chemistry and highlights the importance of organic carbon delivery to the seafloor, marine sulfate concentrations, methane production and external methane influx. The first appearance of conclusively anaerobic oxidation of methane-derived concretions occurs in the Carboniferous and coincides with a Paleozoic rise in marine sulfate. The muted variability recognized in older concretions (and in particular for Precambrian concretions) likely reflects impacts of a smaller marine sulfate reservoir and perhaps elevated marine dissolved inorganic carbon concentrations. Causes of the increase in carbon isotope maximum values through time are more confounding, but may be related to isotopic equilibration of dissolved inorganic carbon with externally derived methane. Ultimately the concretion isotope record in part reflects changes in organic matter availability and marine oxidation state, highlighting connections with the subsurface biosphere and diagenesis throughout geologic time

    Are Newspapers’ Online Discussion Boards Democratic Tools or Conspiracy Theories’ Engines? A Case Study on an Eastern European “Media War”

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    This article analyzes quantitatively and qualitatively 1,583 comments by national newspapers’ online readers in Bulgaria. It investigates readers’ reactions to articles discussing the media war between the biggest press groups—one owned by a Member of Parliament known as “the Murdoch of the East.” The study explores how these stories influence the relationship between newspapers and their readers, and whether they enhance the democratic potential of online discussion. The results show a higher level of reader engagement than in established democracies or nondemocracies. The online space provides an arena for democratic conversations and it is also used as an engine for conspiracy theories

    Contextual Analysis of Stakeholder Opinion on Management and Leadership Competencies for Undergraduate Medical Education: Informing Course Design

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    Background: The study aimed to conduct a contextual analysis of interviews intended to assist with the future design of a feasible and relevant leadership and management course for undergraduate medical students at King Abdulaziz University (KAU), Saudi Arabia. Methods: This was a cross-sectional study conducted at King Abdulaziz University (KAU), Saudi Arabia, during 2019. An exploratory qualitative approach, utilizing systematic content analysis, was used. Data were collected using semi-structured interviews that were conducted with 10 leaders who were stakeholders at KAU, health service providers at KAU hospital, and stakeholders in the Ministry of Health. Results: This study revealed critical findings that highlighted the areas in which KAU could instill better and adequate leadership and management skills in their undergraduate medical students. Multiple core categories for a leadership and management curriculum emerged with many interrelated themes. Most participants mentioned that leadership can be taught and that early exposure is beneficial for developing skills. Additionally, they stated that leaders should have a vision and the ability to articulate that vision. Conclusions: Different implementation challenges were described in relation to the availability of human resources, the current short supply of suitable teachers, and program design. Teaching methods recommended included simulations, lectures, and a project-based approach. Assessment methods that were recommended included objective structured clinical examination (OSCE), formative and summative assessments, self-assessments, and portfolios

    Success or failure in knowledge management systems: a universal issue

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    This paper takes a sociotechnical viewpoint of knowledge management system (KMS) implementation in organizations considering issues such as stakeholder disenfranchisement, lack of communication, and the low involvement of key personnel in system design asking whether KMS designers could learn from applying sociotechnical principles to their systems. The paper discusses design elements drawn from the sociotechnical principles essential for the success of IS and makes recommendations to increase the success of KMS in organizations. It also provides guidelines derived from Clegg’s Principles (2000) for KMS designers to enhance their designs. Our data comes from the application of a plurality of analysis methods on a large comprehensive global survey conducted from 2007 to 2011 of 1034 participants from 76 countries. The survey covers a variety of organizations of all types and sizes from a comprehensive selection of economic sectors and industries. Our results showed that users were not satisfied with the information and knowledge systems that they were being offered. In addition to multiple technology and usability issues, there were human and organisational barriers that prevented the systems from being used to their full potential. We recommend that users of KMS are integrated into the design team so that these usability and other barriers can be addressed during the feasibility stage as well as the actual design and implementation phases

    Cyber security fear appeals:unexpectedly complicated

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    Cyber security researchers are starting to experiment with fear appeals, with a wide variety of designs and reported efficaciousness. This makes it hard to derive recommendations for designing and deploying these interventions. We thus reviewed the wider fear appeal literature to arrive at a set of guidelines to assist cyber security researchers. Our review revealed a degree of dissent about whether or not fear appeals are indeed helpful and advisable. Our review also revealed a wide range of fear appeal experimental designs, in both cyber and other domains, which confirms the need for some standardized guidelines to inform practice in this respect. We propose a protocol for carrying out fear appeal experiments, and we review a sample of cyber security fear appeal studies, via this lens, to provide a snapshot of the current state of play. We hope the proposed experimental protocol will prove helpful to those who wish to engage in future cyber security fear appeal research
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