Abstract
A comparative analysis on the performance of different scanning regimes in time domain optical coherence tomography is presented in terms of image size. Safety thresholds due to the different continuous irradiation time per transverse pixel in different scanning regimes are also considered. We present the maximum exposure level for a variety of scanning procedures, employing either A scanning (depth priority) or T scanning (transverse priority) when generating cross section images, en face images or collecting 3D volumes. We present a comparison between such B-scan images, and different criteria to allow the user to choose the right mode of operation. Mainly, two criteria are detailed, a scanning criterion and a safety criterion. The scanning criterion depends on the number of pixels along the lateral and axial directions. The analysis shows that en-face scanning allows wider images while the longitudinal scanning is more suitable to deep cross sections. The safety criterion refers to safety levels to be observed in each scanning mode. We show that the flying spot OCT imaging has different safety limits for T- and A- based imaging modes. The analysis leads to maximum permissible optical power levels that favors T-scan imaging of wide objects. We then apply the analysis considering as object the eye.

Abstract
Markov models have been widely used to represent and analyze user Web navigation data. In previous work, we have proposed a method to dynamically extend the order of a Markov chain model and a complimentary method for assessing the predictive power of such a variable-length Markov chain. Herein, we review these two methods and propose a novel method for measuring the ability of a variable-length Markov model to summarize user Web navigation sessions up to a given length. Although the summarization ability of a model is important to enable the identification of user navigation patterns, the ability to make predictions is important in order to foresee the next link choice of a user after following a given trail so as, for example, to personalize a Web site. We present an extensive experimental evaluation providing strong evidence that prediction accuracy increases linearly with summarization ability.

Abstract
Recently, two CAT-1 projects have been initiated related to Granada Basin area (Betic Cordillera, Southern Spain), aimed at the detection of deformation in the region applying time series InSAR methodology. Due to the outstanding availability of ERS-1/2 and Envisat acquisitions, a time span of more than 12 years is covered and time series can be produced, enabling us to assess the feasibility of monitoring deformation with millimetre precision. The ultimate goal of these projects is the quantification of displacements and determination of their mean directions, relating them to dynamic changes and stress accumulation in order to identify potential seismic hazard locations. For the moment, not all available scenes have been received, so a preliminary data processing has been carried out at the Padul fault area. In this paper, we present a status report of both projects.

Abstract
We present two methods for testing the predictive power of a variable length Markov chain induced from a collection of user web navigation sessions. The collection of sessions is split into a training and a test set. The first method uses a chi(2) statistical test to measure the significance of the distance between the distribution of the probabilities assigned to the test trails by a Markov model build from the full collection of sessions and a model built from the training set. The statistical test measures the ability of the model to generalise its predictions to the unseen sessions from the test set. The second method evaluates the model ability to predict the last page of a navigation session based on the preceding pages viewed by recording the mean absolute error of the rank of the last occurring page among the predictions provided by the model. Experimental results conducted on both real and random data sets are reported and the results show that in most cases a second-order model is able to capture sufficient history to predict the next link choice with high accuracy.

Abstract
This paper studies the adoption of periodic gaits of quadruped animals by multilegged artificial locomotion systems. The purpose is to determine the gait to adopt at different velocities, under distinct robot and locomotion conditions, based on two performance measures. A set of experiments reveals the influence of the gait and the body and ground parameters upon the proposed indices. It is verified that the gait should be adapted to the robot forward velocity and to the conditions under which the robot is moving. The experiments also reveal that a gait that decreases the energy consumption generally implies an increase in the trajectory following errors.

Abstract
We present the time variant second order statistics of the depth-scan photocurrent in timedomain optical coherence tomography (TD-OCT) systems using polarized thermal light sources. Our results are prerequisite for future development of statistical image processing techniques for TD-OCT. © 2007 Optical Society of America.