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User's requirements have become a key factor for any Quality of Service (QoS) management model to succeed. The advent and rise of new broadband services and network architectures (Triple-Play-Services, NGN…) depends on the ability of providers to achieve user's expectations in these scenarios. For that reason, the overall end user's perception (Quality of Experience -QoE) must be audited, on a regular basis, to address changing user's needs. This paper presents a general system developed to evaluate QoE on IP networks. The system architecture is designed to be capable of emulating multi agent networks and dynamically changing conditions. In addition, the results of a Web browsing QoE experiment, laid out within this emulation system, are described. The experiment was conducted on the basis of ITU-T Recommendation G.1030, and aimed to update the perceptual model, provided in this Recommendation, to today's user requirements and technical improvements.

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The 1985 Mexico City earthquake caused very serious damage, especially in reinforced concrete buildings, making it necessary to repair and strengthen many structures. The authors had the opportunity to study 114 of these retrofitted buildings. The data base created with the collected information contains the description of the building, its damages and the retrofitting techniques used. The statistical analysis of this information makes it possible to identify the correlation among the structural and foundation types, the dominant failure modes, the causes of damage and the repair and strengthening techniques used in this group of buildings.

We present new shear wave anisotropy measurements in the continental crust in northern Guerrero obtained from tectonic tremor. Measurements of crustal anisotropy had not been performed in this area due to the lack of seismicity. However, tectonic tremor activity is abundant and offers an opportunity to determine anisotropy parameters. Polarization and splitting analyses were performed using broadband three‐component seismograms. Results show that splitting times range between 0.07 and 0.36 s. These values are similar to the splitting magnitudes typically observed in the continental crust. The state of stress in the continental crust was investigated by inverting focal mechanisms determined in this study, and also from previous structural geology studies. Unfortunately, no stress measurements were possible in the area where tectonic tremor occurs. It was determined that, to the south of the study area, near the Pacific coast, and to the north, in the volcanic arc, the maximum compressive stress shows a general E‐W trend. The fast polarization directions are oriented NE‐SW and are oblique to the observed maximum compressive stress surrounding the study area. Thus, the relationship between the maximum compressive stress and the observed anisotropic pattern cannot be conclusively established. Several factors such as nonlinear strain in the continental crust as a result of Slow Slip Events, variations of pore fluid pressure, deep crustal mineralogy, and/or upper crust foliations and schistosity could be inducing the observed anisotropy pattern. In general, the fast axes tend to parallel the regional Laramide and Tertiary folds‐and‐thrusts which strike NNE‐SSW. This system of folds‐and‐thrusts is highly foliated in low‐grade schist and seems likely to control the anisotropic structure observed within the tectonic tremor region in Guerrero.

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We present results from a regional study of ground-motion scaling parameters in central Mexico using data from a short-period vertical-component network and two broadband stations within the valley of Mexico. A total of 1220 waveforms recorded between 1994 and 2001 are used for the analysis. A damped least-squares regression using a simple model to separate the excitation, site, and propagation effects for the peak velocities in selected narrow-bandpass frequencies was carried out. The propagation term was parameterized to define a piecewise continuous geometrical spreading function, a frequency-dependent Q (f ), and a distancedependent duration that are consistent with the random vibration theory. We measured the average attenuation of S and Lg waves. A final model with a quality factor of Q(f ) ‫ס‬ 180f 0.66 and a geometrical spreading of

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