Balancing the Migration of Virtual Network Functions with Replications in Data Centers

The Network Function Virtualization (NFV) paradigm is enabling flexibility, programmability and implementation of traditional network functions into generic hardware, in form of the so-called Virtual Network Functions (VNFs). Today, cloud service providers use Virtual Machines (VMs) for the instantiation of VNFs in the data center (DC) networks. To instantiate multiple VNFs in a typical scenario of Service Function Chains (SFCs), many important objectives need to be met simultaneously, such as server load balancing, energy efficiency and service execution time. The well-known \emph{VNF placement} problem requires solutions that often consider \emph{migration} of virtual machines (VMs) to meet this objectives. Ongoing efforts, for instance, are making a strong case for migrations to minimize energy consumption, while showing that attention needs to be paid to the Quality of Service (QoS) due to service interruptions caused by migrations. To balance the server allocation strategies and QoS, we propose using \emph{replications} of VNFs to reduce migrations in DC networks. We propose a Linear Programming (LP) model to study a trade-off between replications, which while beneficial to QoS require additional server resources, and migrations, which while beneficial to server load management can adversely impact the QoS. The results show that, for a given objective, the replications can reduce the number of migrations and can also enable a better server and data center network load balancing

[Review of] Hoerder, Dirk. Cultures in Contact: World Migrations in the Second Millennium

Cultures in Contact is an ambitious tome of the annotated world history of human mass migrations both within and between national boundaries. This book provides a glorious descriptive wealth of when, where, and to a lesser extent why mass migrations have occurred across the largest and most populous regions of the planet earth over the span of the past millennium. In this regard it may serve as a valued reference work for anyone curious about the bigger picture of migration flows; however, those seeking a simplistic theoretical synthesis that would account for the myriad patterns of human migrations over the past millennium will not be much gratified by Hoerder\u27s tome. As the author highlights in his introductory chapter, human migration flows may be either voluntary or coerced and in either case must be viewed in a socio-historically specific systems context

Migration, urban population growth and regional disparity in China

The main objective of this paper is to study the determinants of city population growth in China during the 1990s', as well as the determinants of migrations towards cities, which constitutes the main source of urban population growth in this period. A second objective is to identify regional differences in the urban growth and migrations, that is, whether urban growth and migration patterns are different between coastal and inland provinces. Additionally, we are interested in the differences between temporary and permanent migrations towards urban areas.cerdi

Modeling Credit Risk by Affine Processes

In this paper, the treasury rates and the credit migrations are jointly modeled by multi-dimensional affine processes. In order to capture the entire information, including credit migrations and default events, we construct non-conservative regular affine processes to model credit migrations and characterize the default by the death of the processes. In particular, two specific cases: purely jump affine models and affine diffusion models with potentials, are discussed. This affine approach not only produces the explicit formulas for the prices of corporate bonds and other credit derivatives, but also directly incorporates the credit rating information as a parameter into the pricing formulas. Moreover, our affine models allow to consider the joint credit migrations within an analytically tractable framework in order to capture the correlations of credit movements between firms. Finally, the empirical testing results of a simple affine model are presented to support the effectiveness of our models.Credit Risk Models, Credit Migrations, Affine Processes

Migration, urban population growth and regional disparity in China

The main objective of this paper is to study the determinants of city population growth in China during the 1990s’, as well as the determinants of migrations towards cities, which constitutes the main source of urban population growth in this period. A second objective is to identify regional differences in the urban growth and migrations, that is, whether urban growth and migration patterns are different between coastal and inland provinces. Additionally, we are interested in the differences between temporary and permanent migrations towards urban areas.

Public goods’ attractiveness and migrations

The aim of this paper is to develop a dynamic model of migrations, in which migration is driven by size asymmetries between countries and by the relative preferences of consumers between private consumption and consumption of public goods. The dynamic trajectories heavily depend on the degree of attractiveness for public goods We show that monotone migrations require sufficiently strong preferences for public goods, and can only be sustained from the small to the large countries. We identify the threshold value of the public goods’ intensity of preferences guaranteeing the survival of the small country. For weaker preference intensities, oscillating migrations may arise, but they finally converge to situation where both countries are of equal size.migration, public goods, income tax.

Developments in Education and International Migrations in New Member States of the EU

The paper examines the development of education systems and international migrations in selected new Member States. The countries are Estonia, the Czech Republic and Slovakia. The paper focuses on various elements in the development of education systems making people able to cope with competition on global labour markets. The outcomes of these developments largely regulate the supply of labour and consequently its international demand. Some statistics on international migration and integration of migrants in global labour markets are presented. The aim of this paper is to raise questions about relevant issues to be paid attention to in studies focusing on education and international migrations rather than to try to give any straightforward solutions