Cooperative Multi-Bitrate Video Caching and Transcoding in Multicarrier NOMA-Assisted Heterogeneous Virtualized MEC Networks

Cooperative video caching and transcoding in mobile edge computing (MEC) networks is a new paradigm for future wireless networks, e.g., 5G and 5G beyond, to reduce scarce and expensive backhaul resource usage by prefetching video files within radio access networks (RANs). Integration of this technique with other advent technologies, such as wireless network virtualization and multicarrier non-orthogonal multiple access (MC-NOMA), provides more flexible video delivery opportunities, which leads to enhancements both for the network's revenue and for the end-users' service experience. In this regard, we propose a two-phase RAF for a parallel cooperative joint multi-bitrate video caching and transcoding in heterogeneous virtualized MEC networks. In the cache placement phase, we propose novel proactive delivery-aware cache placement strategies (DACPSs) by jointly allocating physical and radio resources based on network stochastic information to exploit flexible delivery opportunities. Then, for the delivery phase, we propose a delivery policy based on the user requests and network channel conditions. The optimization problems corresponding to both phases aim to maximize the total revenue of network slices, i.e., virtual networks. Both problems are non-convex and suffer from high-computational complexities. For each phase, we show how the problem can be solved efficiently. We also propose a low-complexity RAF in which the complexity of the delivery algorithm is significantly reduced. A Delivery-aware cache refreshment strategy (DACRS) in the delivery phase is also proposed to tackle the dynamically changes of network stochastic information. Extensive numerical assessments demonstrate a performance improvement of up to 30% for our proposed DACPSs and DACRS over traditional approaches.Comment: 53 pages, 24 figure

Bridging the Climate Information Gap: A Framework for Engaging Knowledge Brokers and Decision Makers in State Climate Assessments

Large-scale analyses like the National Climate Assessment (NCA) contain a wealth of information critical to national and regional responses to climate change but tend to be insufficiently detailed for action at state or local levels. Many states now engage in assessment processes to meet information needs for local authorities. The goals of state climate assessments (SCAs) should be to provide relevant, actionable information to state and local authorities, and to generate primary sources, build networks and inform stakeholders. To communicate local climate impacts to decision makers, SCAs should express credibility, salience and legitimacy. They can provide information (e.g., case studies, data sets) and connect stakeholders to the NCA and its process. Based on our experience in the Vermont Climate Assessment (VCA), we present a framework to engage decision makers in SCAs using a fluid network of scientific experts and knowledge brokers to conduct subject area prioritization, data analysis and writing. The VCA addressed economic, environmental and social impacts of climate change at local scales to increase resiliency and manage risk. Knowledge brokers communicated VCA findings through their own stakeholder networks. We include a qualitative impact evaluation, and believe our framework for interaction among scientists, knowledge brokers and stakeholders to be an effective structure for SCAs and a transformative experience for students

The Failure of Corporate Governance in State Owned Enterprises and the Need for Restructured Governance in Fully and Partially Privatized Enterprises: The Case of Kenya

This Article argues that the initiatives adopted in order to make parastatals more efficient are inadequate and will not realize the intended objectives unless the chief executives of parastatals are hired on a competitive basis, given more autonomy and the government is committed not only to designing performance contracts that set realistic standards, but also enforcing them strictly. It also contends that there is a need to streamline the multiple regulations that govern parastatals and reform the corporate regulatory framework of the private sector in order to raise standards of corporate governance and, as a result, ensure that the privatized services are managed prudently

Cardiac evaluation of young athletes: Time for a risk-based approach?

Pre-participation cardiovascular screening (PPCS) is recommended by several scientific and sporting organizations on the premise that early detection of cardiac disease provides a platform for individualized risk assessment and management; which has been proven to lower mortality rates for certain conditions associated with sudden cardiac arrest (SCA) and sudden cardiac death (SCD). What constitutes the most effective strategy for PPCS of young athletes remains a topic of considerable debate. The addition of the electrocardiogram (ECG) to the medical history and physical examination undoubtedly enhances early detection of disease, which meets the primary objective of PPCS. The benefit of enhanced sensitivity must be carefully balanced against the risk of potential harm through increased false-positive findings, costly downstream investigations, and unnecessary restriction/disqualification from competitive sports. To mitigate this risk, it is essential that ECG-based PPCS programs are implemented by institutions with a strong infrastructure and by physicians appropriately trained in modern ECG standards with adequate cardiology resources to guide downstream investigations. While PPCS is compulsory for most competitive athletes, the current debate surrounding ECG-based programs exists in a binary form; whereby ECG screening is mandated for all competitive athletes or none at all. This polarized approach fails to consider individualized patient risk and the available sports cardiology resources. The limitations of a uniform approach are highlighted by evolving data, which suggest that athletes display a differential risk profile for SCA/SCD, which is influenced by age, sex, ethnicity, sporting discipline, and standard of play. Evaluation of the etiology of SCA/SCD within high-risk populations reveals a disproportionately higher prevalence of ECG-detectable conditions. Selective ECG screening using a risk-based approach may, therefore, offer a more cost-effective and feasible approach to PPCS in the setting of limited sports cardiology resources, although this approach is not without important ethical considerations

The Political Economy of State Government Subsidy Adoption: The Case of Ethanol

In this paper we examine the factors that determine the adoption of state economic development incentives in the ethanol industry. We compile data on the implementation dates for subsidies/tax credits for all states for years 1984-2007, a period that covers the complete emergence of the biofuel industry in the United States and that was characterized by the passage of a numerous of state-level subsidies and tax breaks aimed at increasing ethanol production. Using Cox proportional hazard regression analysis, we find that states are more likely to adopt ethanol subsidies when corn production is high, when corn prices are low and gasoline prices are high, when a state is affiliated with the National Corn Growers Association, when a check-off is present, and when state government is under the control of Democrats.ethanol, subsidies, political economy, rent seeking, proportional hazard estimation

Improving Schools Through Youth Leadership and Community Action

Presents a case study of community organizing for school reform by Northwest Bronx Community and Clergy Coalition and Sistas and Brothas United: how their campaigns shaped leadership development, district policy, school capacity, and student outcomes