A case study of MMO2's Madic: A framework for creating mobile internet systems

Mobile Internet applications on ubiquitous mobile networks allows real-time, anywhere, anytime connectivity to services. Due to its scalability and potential cost savings, mobile communication is being increasingly applied in the business and consumer communities to create innovative data and voice application, which run over the Internet infrastructure. This paper reports on a case study at an organisation that created an innovative approach to developing mobile applications developed by third party independent developers. A conceptual wireless reference model is presented that was used to define the various system components required to create effective mobile applications

A note on dissipation in helical turbulence

In helical turbulence a linear cascade of helicity accompanying the energy cascade has been suggested. Since energy and helicity have different dimensionality we suggest the existence of a characteristic inner scale, $\xi=k_H^{-1}$, for helicity dissipation in a regime of hydrodynamic fully developed turbulence and estimate it on dimensional grounds. This scale is always larger than the Kolmogorov scale, $\eta=k_E^{-1}$, and their ratio $\eta / \xi$ vanishes in the high Reynolds number limit, so the flow will always be helicity free in the small scales.Comment: 2 pages, submitted to Phys. Fluid

Exploring the Issues of Security, Privacy and Trust in eGovernment: UK Citizens\u27 Perspective

Recognising the potential that Information and Communications Technologies (ICTs)2 offer for competitiveness and the effectiveness of communities, Governments across the globe are striving to provide online products and services3 to all user groups. There are various definitions of e-government within the literature, and the one being applied in this research is: Egovernment is the application of technology to enable, enhance and improve access to the delivery of government services for the benefit of citizens, employees and enterprise (Silcock, 2001) Whilst there are diverse definitions of e-government, there are also variations in the classification of e-government, each dependent upon the relation between the various stakeholders. Bélanger and Hiller (2005) classified e-government into six categories: Government Delivering Services to Individuals (G2IS), Government to Individuals as a Part of the Political Process (G2IP), Government to Business as a Citizen (G2BC), Government to Business in the Marketplace (G2BMKT), Government to Employees (G2E) and Government to Government (G2G). G2IS involves communication and services between government and citizens (G2C); G2IP involves the relationship that the government has with citizens as a part of the democratic process, such as e-voting. G2BC involves organizations paying taxes or filing reports, and G2BMKT focuses on business transactions between government and businesses, such as e-procurement. Electronic interactions between Government and Citizen can also be classified as a ‘Government to Citizen’ (G2C) model of eGovernment (Beynon-Davies: 2007). This is also referred to as the ‘Transactional’ stage of eGovernment, where the interaction can occur with an agency (NAO, 2007). This interaction involves the receipt or dissemination of information, the completion or submission of a form, the sending of payments, the inspection of an account, or more complicated sets of dealings. It is such transactions that can be perceived to be of sensitive nature for citizens and users are reluctant to conduct transactions, with concerns ranging from: payment security, not understanding how to integrate information and customization impacting their privacy (Belanger & Hiller; 2005). This leads onto security and privacy and their possible effects on transactional stage adoption. In this research paper the aim is to explore how UK is dealing with the issues of security, privacy and trust when adopting and using online government products or services. This is pertinent at this time as the government is taking large steps to increase adoption and usage amongst citizens. By undertaking this research, several contributions are made: Governments around the globe, including, UK are increasingly seeking success at e-Government adoption and usage and such research assists policymakers in obtaining a better understanding. For industry, private sector organizations are partners in the provision of the infrastructure and involved in many other implementation and adoption e-Government projects and research such as this allows them to consider these factors in more depth. For academics, security, privacy and trust are issues of immense importance and research such as this allows academics to become more aware of these topics

Effective swimming strategies in low Reynolds number flows

The optimal strategy for a microscopic swimmer to migrate across a linear shear flow is discussed. The two cases, in which the swimmer is located at large distance, and in the proximity of a solid wall, are taken into account. It is shown that migration can be achieved by means of a combination of sailing through the flow and swimming, where the swimming strokes are induced by the external flow without need of internal energy sources or external drives. The structural dynamics required for the swimmer to move in the desired direction is discussed and two simple models, based respectively on the presence of an elastic structure, and on an orientation dependent friction, to control the deformations induced by the external flow, are analyzed. In all cases, the deformation sequence is a generalization of the tank-treading motion regimes observed in vesicles in shear flows. Analytic expressions for the migration velocity as a function of the deformation pattern and amplitude are provided. The effects of thermal fluctuations on propulsion have been discussed and the possibility that noise be exploited to overcome the limitations imposed on the microswimmer by the scallop theorem have been discussed.Comment: 14 pages, 5 figure

Atmospheric Newtonian noise modeling for third-generation gravitational wave detectors

The sensitivity and the frequency bandwidth of third-generation gravitational-wave detectors are such that the Newtonian noise (NN) signals produced by atmospheric turbulence could become relevant. We build models for atmospheric NN that take into account finite correlation times and inhomogeneity along the vertical direction, and are therefore accurate enough to represent a reliable reference tool for evaluating this kind of noise. We compute the NN spectral density from our models and compare it with the expected sensitivity curve of the Einstein Telescope (ET) with the xylophone design. The noise signal decays exponentially for small values of the frequency and the detector's depth, followed by a power law for large values of the parameters. We find that, when the detector is built at the Earth's surface, the NN contribution in the low-frequency band is above the ET sensitivity curve for strong wind. Building the detector underground is sufficient to push the noise signal under the ET sensitivity curve, but the decrement is close to marginal for strong wind. In light of the slow decay with depth of the NN, building the detector underground could be only partially effective as passive noise mitigation

Transport properties of heavy particles in high Reynolds number turbulence

The statistical properties of heavy particle trajectories in high Reynolds numbers turbulent flows are analyzed. Dimensional analysis assuming Kolmogorov scaling is compared with the result of numerical simulation using a synthetic turbulence advecting field. The non-Markovian nature of the fluid velocity statistics along the solid particle trajectories is put into evidence, and its relevance in the derivation of Lagrangian transport models is discussed.Comment: 30 pages, 11 eps figures included. To appear in Physics of Fluid

Transport Properties of a Chain of Anharmonic Oscillators with random flip of velocities

We consider the stationary states of a chain of $n$ anharmonic coupled oscillators, whose deterministic hamiltonian dynamics is perturbed by random independent sign change of the velocities (a random mechanism that conserve energy). The extremities are coupled to thermostats at different temperature $T_\ell$ and $T_r$ and subject to constant forces $\tau_\ell$ and $\tau_r$. If the forces differ $\tau_\ell \neq \tau_r$ the center of mass of the system will move of a speed $V_s$ inducing a tension gradient inside the system. Our aim is to see the influence of the tension gradient on the thermal conductivity. We investigate the entropy production properties of the stationary states, and we prove the existence of the Onsager matrix defined by Green-kubo formulas (linear response). We also prove some explicit bounds on the thermal conductivity, depending on the temperature.Comment: Published version: J Stat Phys (2011) 145:1224-1255 DOI 10.1007/s10955-011-0385-

Effect of demographic noise in a phytoplankton-zooplankton model of bloom dynamics

An extension of the Truscott-Brindley model (Bull. Math. Biol. {\bf 56}, 981 (1994)) is derived to account for the effect of demographic fluctuations. In the presence of seasonal forcing, and sufficiently shallow water conditions, the fluctuations induced by the discreteness of the zooplankton component appear sufficient to cause switching between the bloom and no-bloom cycle predicted at the mean-field level by the model.The destabilization persists in the thermodynamic limit of a water basin infinitely extended in the horizontal direction.Comment: 10 pages, 8 figure