A 2-D Random Walk Mobility Model for WiMAX Location Update

Mobile Worldwide Interoperability for Microwave Access (WiMAX) network is increasingly popular, and upcoming deployments can be expected with the development of intelligent transport systems (ITS) and the advent of smart cities. However, both applications will demand an efficient management of high mobility. Therefore, optimizing the cost of mobility signaling procedures of the network is key. In this work we study the location update procedure in WiMAX networks. Whilst previous works consider 1-D layouts of base stations (BSs), corresponding to ITS-based scenarios, we focus on extending that scenario to develop an analytical model for 2-D layouts, which fit better for cities. Our model consider the two cases in which the logical entity in charge of handling the location tracking and paging operations, known as anchor paging controller (APC), is assigned for a mobile station (MS) during a location update: when the old APC is reassigned (no relocation), and when a new APC is assigned (relocation). The comparison is made by calculating the cost (as the number of exchanged messages) of the location update procedure in each case. We validate our model through simulations, and discuss the impact on the final cost of several parameters, such as type and frequency of the movements. Finally, we provide some guidelines on how to assign the APC depending on the network parameters

Analysis of a Fast LZ-Based Entropy Estimator for Mobility Data

Randomness in people\u27s movements might serve to detect behavior anomalies. The concept of entropy can be used for this purpose, but its estimation is computational intensive, particularly when processing long movement histories. Moreover, disclosing such histories to third parties may violate user privacy. With a goal to keep the mobility data in the mobile device itself yet being able to measure randomness, we propose three fast entropy estimators based on Lempel-Ziv (LZ) prediction algorithms. We evaluated them with 95 movement histories of real users tracked during 9 months using GSM-based mobility data. The results show that the entropy tendencies of the approaches proposed in this work and those in the literature are the same as time evolves. Therefore, our proposed approach could potentially detect variations in the mobility patterns of the user with a lower computational cost. This allows to unveil shifts in the users mobility behavior without disclosing their sensible location data

A Bandwidth-Efficient Dissemination Scheme of Non-Safety Information in Urban VANETs

The recent release of standards for vehicular communications will hasten the development of smart cities in the following years. Many applications for vehicular networks, such as blocked road warnings or advertising, will require multi-hop dissemination of information to all vehicles in a region of interest. However, these networks present special features and difficulties that may require special measures. The dissemination of information may cause broadcast storms. Urban scenarios are especially sensitive to broadcast storms because of the high density of vehicles in downtown areas. They also present numerous crossroads and signal blocking due to buildings, which make dissemination more difficult than in open, almost straight interurban roadways. In this article, we discuss several options to avoid the broadcast storm problem while trying to achieve the maximum coverage of the region of interest. Specifically, we evaluate through simulations different ways to detect and take advantage of intersections and a strategy based on store-carry-forward to overcome short disconnections between groups of vehicles. Our conclusions are varied, and we propose two different solutions, depending on the requirements of the application

A Bandwidth-Efficient Service for Local Information Dissemination in Sparse to Dense Roadways

Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios

Entropy-based privacy against profiling of user mobility

Location-based services (LBSs) flood mobile phones nowadays, but their use poses an evident privacy risk. The locations accompanying the LBS queries can be exploited by the LBS provider to build the user profile of visited locations, which might disclose sensitive data, such as work or home locations. The classic concept of entropy is widely used to evaluate privacy in these scenarios, where the information is represented as a sequence of independent samples of categorized data. However, since the LBS queries might be sent very frequently, location profiles can be improved by adding temporal dependencies, thus becoming mobility profiles, where location samples are not independent anymore and might disclose the user's mobility patterns. Since the time dimension is factored in, the classic entropy concept falls short of evaluating the real privacy level, which depends also on the time component. Therefore, we propose to extend the entropy-based privacy metric to the use of the entropy rate to evaluate mobility profiles. Then, two perturbative mechanisms are considered to preserve locations and mobility profiles under gradual utility constraints. We further use the proposed privacy metric and compare it to classic ones to evaluate both synthetic and real mobility profiles when the perturbative methods proposed are applied. The results prove the usefulness of the proposed metric for mobility profiles and the need for tailoring the perturbative methods to the features of mobility profiles in order to improve privacy without completely loosing utility

Study of LZ-Based Location Prediction and Its Application to Transportation Recommender Systems

Predicting users’ next location allows to anticipate their future context, thus providing additional time to be ready for that context and react consequently. This work is focused on a set of LZ-based algorithms (LZ, LeZi Update and Active LeZi) capable of learning mobility patterns and estimating the next location with low resource needs, which makes it possible to execute them on mobile devices. The original algorithms have been divided into two phases, thus being possible to mix them and check which combination is the best one to obtain better prediction accuracy or lower resource consumption. To make such comparisons, a set of GSM-based mobility traces of 95 different users is considered. Finally, a prototype for mobile devices that integrates the predictors in a public transportation recommender system is described in order to show an example of how to take advantage of location prediction in an ubiquitous computing environment

Nut Consumptions as a Marker of Higher Diet Quality in a Mediterranean Population at High Cardiovascular Risk

Background: Nut consumption has been associated with improved nutrient adequacy and diet quality in healthy adult populations but this association has never been explored in individuals at high cardiovascular risk. Objective: to assess the associations between consumption of nuts and nutrient adequacy and diet quality in a Mediterranean population at high cardiovascular risk. Design: baseline assessment of nutritional adequacy in participants (n = 6060, men and women, with ages 55⁻75 years old, with overweight/obesity and metabolic syndrome) in the PREDIMED-PLUS primary cardiovascular prevention randomized trial. Methods: nut intake was assessed using a validated food frequency questionnaire. Participants who reported consuming zero quantity of nuts were classified as 'non-nut consumers'. 'Nut consumers' were participants who reported consuming any quantity of nuts. Nineteen micronutrients were examined (vitamins B1, B2, B3, B6, B12, A, C, D, E and folic acid; Ca, K, P, Mg, Fe, Se, Cr, Zn, and iodine). The proportion of micronutrient inadequacy was estimated using the estimated average requirements (EAR) or adequate intake (AI) cut-points. Diet quality was also assessed using a 17-item Mediterranean dietary questionnaire (Mediterranean diet score, MDS), a carbohydrate quality index (CQI) and a fat quality index (FQI). Results: eighty-two percent of participants were nut consumers (median of nut consumption 12.6 g/day; interquartile range: 6.0⁻25.2). Nut consumers were less likely to be below the EAR for vitamins A, B1, B2, B6, C, D, E, folic acid, and Ca, Mg, Se and Zn than non-nut consumers. Nut consumers were also more likely to be above the AI for K and Cr than non-nut consumers. Nut consumers had lower prevalence of inadequate micronutrient intakes, but also higher CQI, higher FQI, and better scores of adherence to the Mediterranean diet (Mediterranean diet score, MDS). Conclusions: nut consumers had better nutrient adequacy, diet quality, and adherence to the MedDiet than those non-nut consumers

Nut Consumptions as a Marker of Higher Diet Quality in a Mediterranean Population at High Cardiovascular Risk

Background: Nut consumption has been associated with improved nutrient adequacy and diet quality in healthy adult populations but this association has never been explored in individuals at high cardiovascular risk. Objective: to assess the associations between consumption of nuts and nutrient adequacy and diet quality in a Mediterranean population at high cardiovascular risk. Design: baseline assessment of nutritional adequacy in participants (n = 6060, men and women, with ages 55⁻75 years old, with overweight/obesity and metabolic syndrome) in the PREDIMED-PLUS primary cardiovascular prevention randomized trial. Methods: nut intake was assessed using a validated food frequency questionnaire. Participants who reported consuming zero quantity of nuts were classified as 'non-nut consumers'. 'Nut consumers' were participants who reported consuming any quantity of nuts. Nineteen micronutrients were examined (vitamins B1, B2, B3, B6, B12, A, C, D, E and folic acid; Ca, K, P, Mg, Fe, Se, Cr, Zn, and iodine). The proportion of micronutrient inadequacy was estimated using the estimated average requirements (EAR) or adequate intake (AI) cut-points. Diet quality was also assessed using a 17-item Mediterranean dietary questionnaire (Mediterranean diet score, MDS), a carbohydrate quality index (CQI) and a fat quality index (FQI). Results: eighty-two percent of participants were nut consumers (median of nut consumption 12.6 g/day; interquartile range: 6.0⁻25.2). Nut consumers were less likely to be below the EAR for vitamins A, B1, B2, B6, C, D, E, folic acid, and Ca, Mg, Se and Zn than non-nut consumers. Nut consumers were also more likely to be above the AI for K and Cr than non-nut consumers. Nut consumers had lower prevalence of inadequate micronutrient intakes, but also higher CQI, higher FQI, and better scores of adherence to the Mediterranean diet (Mediterranean diet score, MDS). Conclusions: nut consumers had better nutrient adequacy, diet quality, and adherence to the MedDiet than those non-nut consumers

Retrotransposons Are the Major Contributors to the Expansion of the Drosophila ananassae Muller F Element

The discordance between genome size and the complexity of eukaryotes can partly be attributed to differences in repeat density. The Muller F element (∼5.2 Mb) is the smallest chromosome in Drosophila melanogaster, but it is substantially larger (>18.7 Mb) in D. ananassae. To identify the major contributors to the expansion of the F element and to assess their impact, we improved the genome sequence and annotated the genes in a 1.4-Mb region of the D. ananassae F element, and a 1.7-Mb region from the D element for comparison. We find that transposons (particularly LTR and LINE retrotransposons) are major contributors to this expansion (78.6%), while Wolbachia sequences integrated into the D. ananassae genome are minor contributors (0.02%). Both D. melanogaster and D. ananassae F-element genes exhibit distinct characteristics compared to D-element genes (e.g., larger coding spans, larger introns, more coding exons, and lower codon bias), but these differences are exaggerated in D. ananassae. Compared to D. melanogaster, the codon bias observed in D. ananassae F-element genes can primarily be attributed to mutational biases instead of selection. The 5′ ends of F-element genes in both species are enriched in dimethylation of lysine 4 on histone 3 (H3K4me2), while the coding spans are enriched in H3K9me2. Despite differences in repeat density and gene characteristics, D. ananassae F-element genes show a similar range of expression levels compared to genes in euchromatic domains. This study improves our understanding of how transposons can affect genome size and how genes can function within highly repetitive domains