Enabling Mobile Communications for the Needy: Affordability Methodology, and Approaches to Requalify Universal Service Measures

This paper links communications and media usage to social and household economics boundaries. It highlights that in present day society, communications and media are a necessity, but not always affordable, and that they furthermore open up for addictive behaviors which raise additional financial and social risks. A simple and efficient methodology compatible with state-of-the-art social and communications business statistics is developed, which produces the residual communications and media affordability budget and ultimately the value-at-risk in terms of usage and tariffs. Sensitivity analysis provides precious information on bottom-up communications and media adoption on the basis of affordability. This approach differs from the regulated but often ineffective Universal service obligation, which instead of catering for individual needs mostly addresses macro-measures helping geographical access coverage (e.g. in rural areas). It is proposed to requalify the Universal service obligations on operators into concrete measures, allowing, with unchanged funding, the needy to adopt mobile services based on their affordability constraints by bridging the gap to a standard tariff. Case data are surveyed from various countries. ICT policy recommendations are made to support widespread and socially responsible communications access.Affordability, Mobile communications, Media usage, Addiction, Residual budget, Social and communications regulations, Social tariffs

WiFi Hot Spot Service Business for the Automotive and Oil Industries: A Competitive Analysis

While you refuel for gas, why not refuel for information or upload vehicle data, using a cheap wireless technology as WiFi? This paper analyzes in extensive detail the user segmentation by vehicle usage, service offering, and full business models from WiFi hot spot services delivered to and from vehicles (private, professional, public) around gas stations. Are also analyzed the parties which play a role in such services: authorization, provisioning and delivery, with all the dependencies modelled by attributed digraphs. Account is made of WiFi base station technical capabilities and costs. Five year financial models (CAPEX, OPEX), and data pertain to two possible service suppliers: multi-service oil companies, and mobile service operators (or MVNOs). Model optimization on the return-on-investment (R.O.I.) is carried out for different deployment scenarios, geographical coverage assumptions, as well as tariff structures. Comparison is also being made with public GPRS and 3G data services, as precursors to HSPA/LTE, and the effect of WiFi roaming is analyzed. Regulatory implications, including those dealing with public safety, are addressed. Analysis shows that due to manpower costs and marketing costs, suitable R.O.I. will not be achieved unless externalities are accounted for and innovative tariff structures are introduced. Open issues and further research are outlined. Further work is currently carried out with automotive electronics sector, wireless systems providers, wireless terminals platform suppliers, and vehicle manufacturers. Future relevance of this work is also discussed for the emerging electrical reloading grids for electrical vehicles.WiFi, Fuel Stations, Business Models, Oil Company, Mobile Operator, WiFi Services, Regulations, Professional Vehicles

Multistability and memory effect in a highly turbulent flow: experimental evidence for a global bifurcation

We report an experimental evidence of a global bifurcation on a highly turbulent von Karman flow. The mean flow presents multiple solutions: the canonical symmetric solution becomes marginally unstable towards a flow which breaks the basic symmetry of the driving apparatus even at very large Reynolds number. The global bifurcation between these states is highly subcritical and the system thus keeps a memory of its history. The transition recalls low-dimension dynamical systems transitions and exhibits a very peculiar statistics. We discuss the role of turbulence in two ways: the multiplicity of hydrodynamical solutions and the effect of fluctuations on the nature of transitions.Comment: submitted to Physical Review Letters 19 May 2004, accepted 10 September 200

Transport in the metallic regime of Mn doped III-V Semiconductors

The standard model of Mn doping in GaAs is subjected to a coherent potential approximation (CPA) treatment. Transport coefficients are evaluated within the linear response Kubo formalism. Both normal (NHE) and anomalous contributions (AHE) to the Hall effect are examined. We use a simple model density of states to describe the undoped valence band. The CPA bandstructure evolves into a spin split band caused by the $p-d$ exchange scattering with Mn dopants. This gives rise to a strong magnetoresistance, which decreases sharply with temperature. The temperature ($T$) dependence of the resistance is due to spin disorder scattering (increasing with $T$), CPA bandstructure renormalization and charged impurity scattering (decreasing with $T$). The calculated transport coefficients are discussed in relation to experiment, with a view of assessing the overall trends and deciding whether the model describes the right physics. This does indeed appear to be case, bearing in mind that the hopping limit needs to be treated separately, as it cannot be described within the band CPA.Comment: submitted to Phys. Rev.

Enabling Mobile Communications for the Needy: Affordability Methodology, and Approaches to Requalify Universal Service Measures

This paper links communications and media usage to social and household economics boundaries. It highlights that in present day society, communications and media are a necessity, but not always affordable, and that they furthermore open up for addictive behaviors which raise additional financial and social risks. A simple and efficient methodology compatible with state-of-the-art social and communications business statistics is developed, which produces the residual communications and media affordability budget and ultimately the value-at-risk in terms of usage and tariffs. Sensitivity analysis provides precious information on bottom-up communications and media adoption on the basis of affordability. This approach differs from the regulated but often ineffective Universal service obligation, which instead of catering for individual needs mostly addresses macro-measures helping geographical access coverage (e.g. in rural areas). It is proposed to requalify the Universal service obligations on operators into concrete measures, allowing, with unchanged funding, the needy to adopt mobile services based on their affordability constraints by bridging the gap to a standard tariff. Case data are surveyed from various countries. ICT policy recommendations are made to support widespread and socially responsible communications access

Theoretical Study of Comb-Polymers Adsorption on Solid Surfaces

We propose a theoretical investigation of the physical adsorption of neutral comb-polymers with an adsorbing skeleton and non-adsorbing side-chains on a flat surface. Such polymers are particularly interesting as "dynamic coating" matrices for bio-separations, especially for DNA sequencing, capillary electrophoresis and lab-on-chips. Separation performances are increased by coating the inner surface of the capillaries with neutral polymers. This method allows to screen the surface charges, thus to prevent electro-osmosis flow and adhesion of charged macromolecules (e.g. proteins) on the capillary walls. We identify three adsorption regimes: a "mushroom" regime, in which the coating is formed by strongly adsorbed skeleton loops and the side-chains anchored on the skeleton are in a swollen state, a "brush" regime, characterized by a uniform multi-chains coating with an extended layer of non-adsorbing side-chains and a non-adsorbed regime. By using a combination of mean field and scaling approaches, we explicitly derive asymptotic forms for the monomer concentration profiles, for the adsorption free energy and for the thickness of the adsorbed layer as a function of the skeleton and side-chains sizes and of the adsorption parameters. Moreover, we obtain the scaling laws for the transitions between the different regimes. These predictions can be checked by performing experiments aimed at investigating polymer adsorption, such as Neutron or X-ray Reflectometry, Ellipsometry, Quartz Microbalance, or Surface Force Apparatus.Comment: 30 pages, 7 figures, to be published in Macromolecule

Scalable BGP Prefix Selection for Effective Inter-domain Traffic Engineering

Inter-domain Traffic Engineering for multi-homed networks faces a scalability challenge, as the size of BGP routing table continue to grow. In this context, the choice of the best path must be made potentially for each destination prefix, requiring all available paths to be characterised (e.g., through measurements) and compared with each other. Fortunately, it is well-known that a few number of prefixes carry the larger part of the traffic. As a natural consequence, to engineer large volume of traffic only few prefixes need to be managed. Yet, traffic characteristics of a given prefix can greatly vary over time, and little is known on the dynamism of traffic at this aggregation level, including predicting the set of the most significant prefixes in the near future. %based on past observations. Sophisticated prediction methods won't scale in such context. In this paper, we study the relationship between prefix volume, stability, and predictability, based on recent traffic traces from nine different networks. Three simple and resource-efficient methods to select the prefixes associated with the most important foreseeable traffic volume are then proposed. Such proposed methods allow to select sets of prefixes with both excellent representativeness (volume coverage) and stability in time, for which the best routes are identified. The analysis carried out confirm the potential benefits of a route decision engine