Regulation of Off-Network Pricing in a Nonneutral Network

Representatives of several Internet service providers (ISPs) have expressed their wish to see a substantial change in the pricing policies of the Internet. In particular, they would like to see content providers (CPs) pay for use of the network, given the large amount of resources they use. This would be in clear violation of the ``network neutrality'' principle that had characterized the development of the wireline Internet. Our first goal in this article is to propose and study possible ways of implementing such payments and of regulating their amount. We introduce a model that includes the users' behavior, the utilities of the ISP and of the CPs, and, the monetary flow that involves the content users, the ISP and CP, and, in pUrticular, the CP's revenues from advertisements. We consider various game models and study the resulting equilibria; they are all combinations of a noncooperative game (in which the ISPs and CPs determine how much they will charge the users) with a ``cooperative'' one on how the CP and the ISP share the payments. We include in our model a possible asymmetric weighting parameter (that varies between zero to one). We also study equilibria that arise when one of the CPs colludes with the TSP. We also study two dynamic game models as well as the convergence of prices to the equilibrium values.

Acoustic phonon behavior of PbWO4 and BaWO4 probed by low temperature Brillouin spectroscopy

Temperature dependent acoustic phonon behavior of PbWO4 and BaWO4 using Brillouin spectroscopy has been explained for the first time. Low temperature Brillouin studies on PbWO4 and BaWO4 have been carried out from 320-20 K. In PbWO4, we observe a change in acoustic phonon mode behavior around 180 K. But in the case of BaWO4, we have observed two types of change in acoustic phonon mode behavior at 240 K and 130 K. The change in Brillouin shift omega and the slope d omega/dT are the order parameter for all kinds of phase transitions. Since we do not see hysteresis on acoustic phonon mode behavior in the reverse temperature experiments, these second order phase transitions are no related to structural phase change and could be related to acoustic phonon coupled electronic transitions. In PbWO4 he temperature driven phase transition at 180 K could be due to changes in he environment around he lead vacancy (V-pb(2-)) changes the electronic states. In the case of BaWO4, the phase transition at 240 K shows he decrease in penetration depth of WO3 impurity. So it becomes more metallic. The transition at 130 K could be he same electronic transitions as that of PbWO4 as function of temperature. The sound velocity and elastic moduli of BaWO4 shows that it could be the prominent material for acousto-optic device applications. (C) 2014 Elsevier Ltd. All rights reserved.

Optimal values of bipartite entanglement in a tripartite system

For a general tripartite system in some pure state, an observer possessing any two parts will see them in a mixed state. By the consequence of Hughston-Jozsa-Wootters theorem, each basis set of local measurement on the third part will correspond to a particular decomposition of the bipartite mixed state into a weighted sum of pure states. It is possible to associate an average bipartite entanglement ((S) over bar) with each of these decompositions. The maximum value of (S) over bar is called the entanglement of assistance (E-A) while the minimum value is called the entanglement of formation (E-F). An appropriate choice of the basis set of local measurement will correspond to an optimal value of (S) over bar; we find here a generic optimality condition for the choice of the basis set. In the present context, we analyze the tripartite states W and GHZ and show how they are fundamentally different. (C) 2014 Elsevier B.V. All rights reserved.

Functionality preservation with enhanced mechanical integrity in the nanocomposites of the metal-organic framework, ZIF-8, with BN nanosheets

Metal-organic frameworks (MOFs) and boron nitride both possess novel properties, the former associated with microporosity and the latter with good mechanical properties. We have synthesized composites of the imidazolate based MOF, ZIF-8, and few-layer BN in order to see whether we can incorporate the properties of both these materials in the composites. The composites so prepared between BN nanosheets and ZIF-8 have compositions ZIF-1BN, ZIF-2BN, ZIF-3BN and similar to ZIF-4BN. The composites have been characterized by PXRD, TGA, XPS, electron microscopy, IR, Raman and solid state NMR spectroscopy. The composites possess good surface areas, the actual value decreasing only slightly with the increase in the BN content. The CO2 uptake remains nearly the same in the composites as in the parent ZIF-8. More importantly, the addition of BN markedly improves the mechanical properties of ZIF-8, a feature that is much desired in MOFs. Observation of microporous features along with improved mechanical properties in a MOF is indeed noteworthy. Such manipulation of properties can be profitably exploited in practical applications.

Characterizing the Impact of Feedback Delays on Wideband Rate Adaptation

In contemporary orthogonal frequency division multiplexing (OFDM) systems, such as Long Term Evolution (LTE), LTE-Advanced, and WiMAX, a codeword is transmitted over a group of subcarriers. Since different subcarriers see different channel gains in frequency-selective channels, the modulation and coding scheme (MCS) of the codeword must be selected based on the vector of signal-to-noise-ratios (SNRs) of these subcarriers. Exponential effective SNR mapping (EESM) maps the vector of SNRs into an equivalent flat-fading SNR, and is widely used to simplify this problem. We develop a new analytical framework to characterize the throughput of EESM-based rate adaptation in such wideband channels in the presence of feedback delays. We derive a novel accurate approximation for the throughput as a function of feedback delay. We also propose a novel bivariate gamma distribution to model the time evolution of EESM between the times of estimation and data transmission, which facilitates the analysis. These are then generalized to a multi-cell, multi-user scenario with various frequency-domain schedulers. Unlike prior work, most of which is simulation-based, our framework encompasses both correlated and independent subcarriers and various multiple antenna diversity modes; it is accurate over a wide range of delays.

Improvements to the Froissart bound from AdS/CFT

In this paper we consider the issue of the Froissart bound on the high energy behaviour of total cross sections. This bound, originally derived using principles of analyticity of scattering amplitudes, is seen to be satisfied by all the available experimental data on total hadronic cross sections. At strong coupling, gauge/gravity duality has been used to provide some insights into this behaviour. In this work, we find the subleading terms to the so-derived Froissart bound from AdS/CFT. We find that a (ln s/s0) term is obtained, with a negative coefficient. We see that the fits to the currently available data confirm improvement in the fits due to the inclusion of such a term, with the appropriate sign. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license.

Thermalization of Green functions and quasinormal modes

We develop a new method to study the thermalization of time dependent retarded Green function in conformal field theories holographically dual to thin shell AdS Vaidya space times. The method relies on using the information of all time derivatives of the Green function at the shell and then evolving it for later times. The time derivatives of the Green function at the shell is given in terms of a recursion formula. Using this method we obtain analytic results for short time thermalization of the Green function. We show that the late time behaviour of the Green function is determined by the first quasinormal mode. We then implement the method numerically. As applications of this method we study the thermalization of the retarded time dependent Green function corresponding to a minimally coupled scalar in the AdS 3 and AdS 5 thin Vaidya shells. We see that as expected the late time behaviour is determined by the first quasinormal mode. We apply the method to study the late time behaviour of the shear vector mode in AdS 5 Vaidya shell. At small momentum the corresponding time dependent Green function is expected to relax to equilibrium by the shear hydrodynamic mode. Using this we obtain the universal ratio of the shear viscosity to entropy density from a time dependent process.

Pressure-induced phase transition in Bi2Se3 at 3 GPa: electronic topological transition or not?

In recent years, a low pressure transition around P similar to 3 GPa exhibited by the A(2)B(3)-type 3D topological insulators is attributed to an electronic topological transition (ETT) for which there is no direct evidence either from theory or experiments. We address this phase transition and other transitions at higher pressure in bismuth selenide (Bi2Se3) using Raman spectroscopy at pressure up to 26.2 GPa. We see clear Raman signatures of an isostructural phase transition at P similar to 2.4 GPa followed by structural transitions at similar to 10 GPa and 16 GPa. First-principles calculations reveal anomalously sharp changes in the structural parameters like the internal angle of the rhombohedral unit cell with a minimum in the c/a ratio near P similar to 3 GPa. While our calculations reveal the associated anomalies in vibrational frequencies and electronic bandgap, the calculated Z(2) invariant and Dirac conical surface electronic structure remain unchanged, showing that there is no change in the electronic topology at the lowest pressure transition.

Explicit and Unique Construction of Tetrablock Unitary Dilation in a Certain Case

Consider the domain E in defined by This is called the tetrablock. This paper constructs explicit boundary normal dilation for a triple (A, B, P) of commuting bounded operators which has as a spectral set. We show that the dilation is minimal and unique under a certain natural condition. As is well-known, uniqueness of minimal dilation usually does not hold good in several variables, e.g., Ando's dilation is known to be not unique, see Li and Timotin (J Funct Anal 154:1-16, 1998). However, in the case of the tetrablock, the third component of the dilation can be chosen in such a way as to ensure uniqueness.

The principled executive

Resumen: El artículo presenta el problema de la escisión del hombre de negocios entre su esfera pública en el ámbito del management, y el ámbito privado de la vida familiar y religiosa. Señala la importancia del documento pontificio al detectar este problema e intentar establecer modos de mitigarlo. El autor analiza el tema de la vocación empresaria en el mundo actual, que los nuevos líderes deben poseer para poder enfrentar los problemas propios del mundo financiero tras la crisis económica mundial del año 2008. Finalmente, hace referencia a la importancia de la educación, especialmente dentro del marco de las Universidades católicas

La vocación del líder empresarial desde la reflexión de un empresario

Resumen: Este artículo parte del interrogante acerca de la necesidad de volver sobre los conceptos postulados desde la Carta Encíclica Rerum Novarum del Papa León XIII acerca del desarrollo social, y analiza el modo en que estos principios son retomados por el documento pontificio La vocación del líder empresarial: una reflexión. El autor destaca la importancia del documento y su análisis de las tres facetas en que se desenvuelve la vida empresarial: ver, juzgar y actuar. Sólo el empresario capaz de alcanzar un equilibrio entre estos aspectos, podrá ser un verdadero líder de negocios cristiano

Terrorism and the World Economy

Published as an article in: European Economic Review, 2008, vol. 52, issue 1, pages 1-27.

Detección del movimiento cíclico estacional en edificios históricos por métodos topográficos

[ES] Para más información véase el trabajo LDGP_mem_003-2: "Estudio topográfico de las deformaciones del conjunto arquitectónico de la iglesia de Nuestra Señora de la Blanca (Agoncillo, La Rioja) [Julio 2007 – Octubre 2009]", http://hdl.handle.net/10810/7050