scholarly journals Modeling User Reputation in Online Social Networks: The Role of Costs, Benefits, and Reciprocity

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1073
Author(s):  
Frank Schweitzer ◽  
Pavlin Mavrodiev ◽  
Adrian M. Seufert ◽  
David Garcia
Keyword(s):  
Online Social Networks ◽  
Online Social Network ◽  
Agent Based ◽  
Optimal Cost ◽  
The Core ◽  
User Reputation ◽  
The Cost ◽  
Computational Analyses

We analyze an agent-based model to estimate how the costs and benefits of users in an online social network (OSN) impact the robustness of the OSN. Benefits are measured in terms of relative reputation that users receive from their followers. They can be increased by direct and indirect reciprocity in following each other, which leads to a core-periphery structure of the OSN. Costs relate to the effort to login, to maintain the profile, etc. and are assumed as constant for all users. The robustness of the OSN depends on the entry and exit of users over time. Intuitively, one would expect that higher costs lead to more users leaving and hence to a less robust OSN. We demonstrate that an optimal cost level exists, which maximizes both the performance of the OSN, measured by means of the long-term average benefit of its users, and the robustness of the OSN, measured by means of the lifetime of the core of the OSN. Our mathematical and computational analyses unfold how changes in the cost level impact reciprocity and subsequently the core-periphery structure of the OSN, to explain the optimal cost level.

scholarly journals Assisting humans in privacy management: an agent-based approach

2020 ◽  
Vol 35 (1) ◽  
Author(s):  
A. Can Kurtan ◽  
Pınar Yolum
Keyword(s):  
Online Social Networks ◽  
Online Social Network ◽  
Real Life ◽  
Privacy Management ◽  
Agent Based ◽  
Image Sharing ◽  
Privacy Preferences ◽  
Privacy Settings ◽  
Privacy Setting ◽  
Sharing Behavior

AbstractImage sharing is a service offered by many online social networks. In order to preserve privacy of images, users need to think through and specify a privacy setting for each image that they upload. This is difficult for two main reasons: first, research shows that many times users do not know their own privacy preferences, but only become aware of them over time. Second, even when users know their privacy preferences, editing these privacy settings is cumbersome and requires too much effort, interfering with the quick sharing behavior expected on an online social network. Accordingly, this paper proposes a privacy recommendation model for images using tags and an agent that implements this, namely pelte. Each user agent makes use of the privacy settings that its user have set for previous images to predict automatically the privacy setting for an image that is uploaded to be shared. When in doubt, the agent analyzes the sharing behavior of other users in the user’s network to be able to recommend to its user about what should be considered as private. Contrary to existing approaches that assume all the images are available to a centralized model, pelte is compatible to distributed environments since each agent accesses only the privacy settings of the images that the agent owner has shared or those that have been shared with the user. Our simulations on a real-life dataset shows that pelte can accurately predict privacy settings even when a user has shared a few images with others, the images have only a few tags or the user’s friends have varying privacy preferences.

scholarly journals Trust in multi-agent systems

2004 ◽  
Vol 19 (1) ◽  
pp. 1-25 ◽  
Author(s):  
SARVAPALI D. RAMCHURN ◽  
DONG HUYNH ◽  
NICHOLAS R. JENNINGS
Keyword(s):  
Large Scale ◽  
State Of The Art ◽  
Comprehensive Treatment ◽  
Multi Agent Systems ◽  
Agent Based ◽  
Agent Systems ◽  
The Core ◽  
Open Distributed Systems ◽  
Multi Agent

Trust is a fundamental concern in large-scale open distributed systems. It lies at the core of all interactions between the entities that have to operate in such uncertain and constantly changing environments. Given this complexity, these components, and the ensuing system, are increasingly being conceptualised, designed, and built using agent-based techniques and, to this end, this paper examines the specific role of trust in multi-agent systems. In particular, we survey the state of the art and provide an account of the main directions along which research efforts are being focused. In so doing, we critically evaluate the relative strengths and weaknesses of the main models that have been proposed and show how, fundamentally, they all seek to minimise the uncertainty in interactions. Finally, we outline the areas that require further research in order to develop a comprehensive treatment of trust in complex computational settings.

Creating continuous areas of old forest in long-term forest planning

2000 ◽  
Vol 30 (11) ◽  
pp. 1817-1823 ◽  
Author(s):  
Karin Öhman
Keyword(s):  
Net Present Value ◽  
Problem Formulation ◽  
Core Area ◽  
Northern Sweden ◽  
Present Value ◽  
The Core ◽  
Long Range Planning ◽  
The Cost

Harvest activities tend often to create landscapes where the old forest is fragmented into isolated patches that provide marginal conditions for species that inhabit forest interiors. This paper presents a long-range planning model designed to maximize the net present value and to create continuous patches of old forest. In this model, the spatial structure of old forest is controlled by core area and edge habitats. Core area is defined as the area of old forest that is free of edge effects from surrounding habitats. The core area requirement is set to a fixed value for each of a number of time periods, whereas the area of edge habitats, which should be as small as possible, is weighted against the net present value. The model is applied in a case study to an actual landscape consisting of 755 stands of forest in northern Sweden and solved using simulated annealing. The results show that distinct continuous patches of old forest are created when both a core area requirement and consideration of the amount of edge habitats are included in the problem formulation. The cost of creating continuous areas of old forest was found to be significant.

MACROECONOMIC STABILIZATION AND LONG-TERM GROWTH: THE ROLE OF POLICY DESIGN

2019 ◽  
pp. 1-46 ◽  
Author(s):  
Philipp Harting
Keyword(s):  
Policy Design ◽  
Theoretical Perspective ◽  
Long Term Effects ◽  
Agent Based ◽  
Stabilization Policies ◽  
Endogenous Business Cycles ◽  
The Business Cycle ◽  
Fiscal Stabilization

Do fiscal stabilization policies affect the long-term growth of the economy? If so, are the long-term effects growth enhancing or growth reducing? When addressing these questions from a theoretical perspective, the literature has typically emphasized the importance of structural aspects such as the modeling approach of endogenous technological change while paying less attention to an elaborate design of the considered fiscal stabilization policies. This paper uses an agent-based macroeconomic model that generates endogenous business cycles to emphasize the role of the policy design for long-term growth effects of stabilization policies. By comparing a demand-oriented consumption policy and two different investment subsidizing policies, it can be shown that these policies are successful in smoothing the business cycle but differ in terms of their effects on economic long-term growth. This highlights the importance of policy design for the analysis of long-term effects of stabilization policies.

scholarly journals Trade facilitation through logistics performance:The enabling role of National Government

2011 ◽  
Vol 5 (1) ◽  
Author(s):  
Jan H. Havenga
Keyword(s):  
Transport Network ◽  
Logistics System ◽  
Trade Facilitation ◽  
The Core ◽  
Rural Economies ◽  
Freight Logistics ◽  
Efficient Access ◽  
State Of Affairs

Despite two decades of visionary policies, problems within South Africa’s freight logistics system remain. Logistics costs are high, the current road and rail solutions will be unable to meet long-term demand for freight transport sustainably, and rural economies still do not have efficient access to the corridor transport network. This article postulates that one of the core reasons for the state of affairs is the inability of government to enable an optimally functioning freight logistics system. The main challenges faced by government are identified and an intervention is proposed to develop an overarching framework and implementation plan to address South Africa’s long-term freight logistics needs.

Can Information on Cost Improve Clinicians' Behavior?: Lessons from Health Care Trials and Management

1997 ◽  
Vol 13 (4) ◽  
pp. 553-561 ◽  
Author(s):  
Peter F. Lowet ◽  
John M. Eisenberg
Keyword(s):  
Health Care ◽  
Price Competition ◽  
Educational Interventions ◽  
Cost Information ◽  
Improved Outcomes ◽  
Practice Variations ◽  
The Cost ◽  
The Impact

AbstractFacing intense price competition and societal pressures, health care provider organizations have focused increasingly on the cost-effectiveness of medical services. In instances when there is insufficient evidence that a more expensive treatment course generates improved outcomes, the lower cost option is often encouraged. Yet, with resource utilization still determined principally by individual physicians, large practice variations often persist. This paper reviews the literature and explores the impact of sharing cost information on physicians' practice patterns utilizing management theory concepts. More research should be conducted to determine long-term benefits of educational interventions, physicians' fundamental views on the relationship between cost and quality and its effect on their responsiveness to cost information, and the role of leadership in changing clinical behavior.

scholarly journals Sexually opposite effects of testosterone on mating success in wild rock hyrax

2019 ◽  
Vol 30 (6) ◽  
pp. 1611-1617
Author(s):  
Lee Koren ◽  
Yishai Weissman ◽  
Inbar Schnitzer ◽  
Rosanne Beukeboom ◽  
Einat Bar Ziv ◽  
...  
Keyword(s):  
Mate Guarding ◽  
Female Reproductive Success ◽  
Rock Hyrax ◽  
Proximate Mechanisms ◽  
Physiological Processes ◽  
Procavia Capensis ◽  
Males And Females ◽  
The Cost

Abstract Although males and females share traits, their motivations and needs may be different, due to life-history disparities that lead to divergent selection pressures. Proximate mechanisms underlying differences between the sexes include hormones that mediate the development and activation of suites of traits. Testosterone is associated with morphological features, physiological processes, and social behaviors in both sexes. However, even if present in similar concentrations in the circulation, testosterone often affects males and females differently. We combined behavioral mating observations of the wild polygynandrous rock hyrax (Procavia capensis) with hair testosterone that represents long-term integrated levels. We found that whereas copulation success increases with the rise in testosterone in males it decreases in females. We did not find an association between testosterone and choosiness in either sex. However, we found that males with higher testosterone mate-guarded females with lower testosterone. Our findings show disassortative mating and mate-guarding in respect to testosterone and provide clues to the cost of testosterone for females, in terms of copulation success. These results open up intriguing questions relating to the role of testosterone in mediating a similar trade-off in male and female reproductive success.

Introduction to this special section: The role of advanced modeling in enhanced carbon storage

2021 ◽  
Vol 40 (6) ◽  
pp. 408-412
Author(s):  
Josef Paffenholz
Keyword(s):  
Carbon Capture ◽  
Fossil Fuels ◽  
Special Section ◽  
Intergovernmental Panel ◽  
Carbon Capture And Sequestration ◽  
Net Zero ◽  
The Cost ◽  
Term Monitoring

To limit the warming of the planet to no more than a 2°C increase, models show that net-zero release of anthropomorphic CO2 must be achieved by the middle of the century. For the foreseeable future, the majority of the world's energy will still be provided by fossil fuels, so other methods, besides expanding the contribution of renewable energy, are needed in order to achieve this goal. According to the Intergovernmental Panel on Climate Change (IPCC), carbon capture and sequestration (CCS) is one such method, without which the cost to achieve the 2°C target would more than double. To achieve this climate goal, CCS efforts must increase by approximately 100-fold from current levels within the next 20 years. Geophysical simulations on suitable geologic models will provide an important tool to streamline and accelerate the vast expansion of geophysical site characterization and long-term monitoring tasks required for industrial-scale CCS to succeed.

The Role of Cardiac Rehabilitation in Achieving Optimal Treatment

2011 ◽  
Vol 7 (1) ◽  
pp. 62
Author(s):  
Miguel Mendes ◽  
Keyword(s):  
Secondary Prevention ◽  
Cardiac Rehabilitation ◽  
Medical Treatment ◽  
Lifestyle Changes ◽  
Coronary Syndrome ◽  
Secondary Prevention Programme ◽  
Lifestyle Measures ◽  
The Cost

The clinical practice of European cardiologists is directed by the European Society of Cardiology’s guidelines for several clinical entities, in which ‘optimal medical treatment’ (a specific drug regime and lifestyle measures) for each syndrome is defined. The described pharmacotherapy is composed of several drugs, since the clinical research behind the recommendations is conducted using an ‘on top of’ strategy. For example, an asymptomatic patient after an acute coronary syndrome with normal ventricular function and without residual ischaemia has an indication to take at least four types of tablets per day, which is difficult to understand and to follow long term. The cost of the drugs is sometimes beyond the patient’s means, which also contributes to lower compliance. A clinician’s practice is usually very busy, which means it is almost impossible to perform patient education and promote adherence to drug therapy and lifestyle changes. Cardiac rehabilitation, as proved by the Global Secondary Prevention Strategies to Limit Event Recurrence after Myocardial Infarction (GOSPEL) study, may be considered the best available secondary prevention programme, as it educates patients and promotes adherence to the optimal medical treatment to a greater degree than usual care.

Rural Road Delineation at Night: The Influence of Road-Side Post Location and Frequency on Curve Direction Estimates

1982 ◽  
Vol 26 (3) ◽  
pp. 233-237 ◽  
Author(s):  
T. J. Triggs ◽  
J. W. Meehan ◽  
W. G. Harris
Keyword(s):  
Frequency Condition ◽  
Left Hand ◽  
Cost Benefits ◽  
The Road ◽  
Rural Road ◽  
The Cost ◽  
Laboratory Situation ◽  
Post Condition

Previous research has demonstrated the efficacy of road-side posts in providing long term delineation information. In order to explore the role of this type of cue further, an experiment was conducted to evaluate the effect of different road-post configurations on the judgements of curve direction by subjects. Specifically, the effect of positioning posts on the inside only, outside only, or both sides of the curve and the influence of post frequency along the road were examined. A range of road contours and distances to the commencement of curves were included in the experimental stimuli. Static views of rural road scenes were presented to subjects in a laboratory situation, and on each trial they were required to make speeded judgements of whether a right-hand or left-hand curve was presented. The results showed that road-side posts provide significantly better information if they are presented on the outside rather than the inside of the curve. Overall, posts on both sides of the road did not result in faster judgements than posts only on the outside of the curve. Subjects performed better in the higher-frequency post condition than in the lower frequency condition, but there was no marked interaction between the post frequency and post location variables. The findings have implications for the cost-benefits of rural road delineation schemes.

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