Flexible Authentication in Vehicular Ad hoc Networks

A Vehicular Ad-Hoc Network (VANET) is a form of Mobile ad-hoc network, to provide communications among nearby vehicles and between vehicles and nearby fixed roadside equipment. The key operation in VANETs is the broadcast of messages. Consequently, the vehicles need to make sure that the information has been sent by an authentic node in the network. VANETs present unique challenges such as high node mobility, real-time constraints, scalability, gradual deployment and privacy. No existent technique addresses all these requirements. In particular, both inter-vehicle and vehicle-to-roadside wireless communications present different characteristics that should be taken into account when defining node authentication services. That is exactly what is done in this paper, where the features of inter-vehicle and vehicle-to-roadside communications are analyzed to propose differentiated services for node authentication, according to privacy and efficiency needs

El ácido úrico se asocia con características de un síndrome de resistencia insulínica en los niños obesos en etapas perdurables

Elevated plasma uric acid levels are associated with obesity and could be an expression of insulin-resistant state. The aim of the present study was to evaluate plasma uric acid in obese and normal-weight children exclusively at prepubertal stage and its relationship with anthropometric measurements, intake, and features of the insulin resistance syndrome. A study was performed in 34 obese and 20 normal- weight prepubertal children. Nutrient intake was determined using a 72 h recall questionnaire and a consumption food frequency questionnaire. Anthropometric parameters and fasting plasma lipids, glucose, insulin, leptin, adiponectin, tumour necrosis factor (TNF-α) and uric acid were measured. Multiple regression analysis was used to identify association of anthropometric parameters, nutrient intake and insulin resistance syndrome variables (arterial blood pressure, plasma glucose, insulin, homeostasis model assessment of insulin resistance index- HOMA- triacylglycerols and, HDL-cholesterol) with uric acid. Plasma uric concentration was significantly higher in the obese group than in the control group and when adjusted by sex, age and BMI was positively associated with tricipital skinfold and insulin resistance, and negatively with adiponectin. In multiple regression analysis, BMI, HDL-cholesterol and adiponectin were independent predictors of plasma uric acid. In conclusion, elevated levels of uric acid in obese children, compared with lean subjects, at the prepubertal period, seems to be an early metabolic alteration that is associated with other features of insulin resistance syndrome.Los niveles elevados de ácido úrico plasmáticos se asocian a la obesidad y pueden ser la expresión de un estado de resistencia insulínica. El objetivo de este estudio ha sido evaluar la concentración plasmática de ácido úrico en niños obesos y normales, exclusivamente en edad prepuberal, y determinar su relación con las medidas antropométricas, la ingesta dietética y los parámetros asociados al síndrome de resistencia insulínica. El estudio se llevó a cabo en 34 niños obesos y 20 controles en edad prepuberal a los cuales se les estimó su ingesta dietética mediante el registro de un cuestionario de ingesta de alimentos de 72 h y un cuestionario de frecuencia de consumo de alimentos y se determinaron, además de los parámetros antropométricos, la glucosa, la insulina, la leptina, la adiponectina y el factor de necrosis tumoral alfa (TNF-α) plasmáticos. Se realizó un análisis de regresión múltiple para identificar la asociación entre los niveles de ácido úrico y los parámetros antropométricos, la ingesta de nutrientes y las variables clásicas relacionadas con el síndrome de resistencia insulínica (hipertensión, glucosa, insulina, índice de resistencia insulínica HOMA, triglicéridos y HDL-colesterol plasmáticos), así como con leptina, adiponectina y TNF-α. La concentración plasmática de ácido úrico fue significativamente más elevada en los niños obesos que en los controles y, cuando se ajustó por sexo, edad e índice de masa corporal, los niveles de ácido úrico se asociaron con el pliegue tricipital y la resistencia inulínica, y negativamente con la adiponectina. En el análisis de regresión múltiple, el índice de masa corporal, el HDL-colesterol y la adiponectina fueron predictores independientes del ácido úrico plasmático. En conclusión, los niveles elevados de ácido úrico en niños obesos en edad prepuberal, comparado con los de los niños normales, representan una alteración metabólica temprana asociada con la resistencia insulínica.This work was supported by the Spanish Ministry of Health and Consumer Affairs, the Spanish National Program for Scientific Research, Development, and Technological Innovation (I+D+I), and the Instituto de Salud Carlos III (Spanish National Health Research Institute), FEDER co-financed Project No. PI 051968. Mercedes Gil-Campos was a research scientist appointed on a training contract funded by the Carlos III Health Research Institute

A systematic review of breast milk microbiota composition and the evidence for transfer to and colonisation of the infant gut

The intestinal microbiota plays a major role in infant health and development. However, the role of the breastmilk microbiota in infant gut colonisation remains unclear. A systematic review was performed to evaluate the composition of the breastmilk microbiota and evidence for transfer to/colonisation of the infant gut. Searches were performed using PUBMED, OVID, LILACS and PROQUEST from inception until 18th March 2020 with a PUBMED update to December 2021. 88 full texts were evaluated before final critique based on study power, sample contamination avoidance, storage, purification process, DNA extraction/analysis, and consideration of maternal health and other potential confounders. Risk of skin contamination was reduced mainly by breast cleaning and rejecting the first milk drops. Sample storage, DNA extraction and bioinformatics varied. Several studies stored samples under conditions that may selectively impact bacterial DNA preservation, others used preculture reducing reliability. Only 15 studies, with acceptable sample size, handling, extraction, and bacterial analysis, considered transfer of bacteria to the infant. Three reported bacterial transfer from infant to breastmilk. Despite consistent evidence for the breastmilk microbiota, and recent studies using improved methods to investigate factors affecting its composition, few studies adequately considered transfer to the infant gut providing very little evidence for effective impact on gut colonisation

Graph-Based Approach to the Edit Distance Cryptanalysis of Irregularly Clocked Linear Feedback Shift Registers

This paper proposes a speed-up of a known-plaintext attack on some stream ciphers based on Linear Feedback Shift Registers (LFSRs). The algorithm consists of two basic steps: first, to guess the initial seed value of one of the LFSRs, and then to use the resulting binary sequence in order to deduce useful information about the cipher parameters. In particular, the proposed divide-and-conquer attack is based on a combination of graph-based techniques with edit distance concepts. While the original edit distance attack requires the exhaustive search over the set of all possible initial states of the involved LFSR, this work presents a new heuristic optimization that avoids the evaluation of an important number of initial states through the identification of the most promising branches of the search graph. The strongest aspects of the proposal are the facts that the obtained results from the attack are absolutely deterministic, and that many inconsistent initial states of the target LFSRs are recognized and avoided during search.This work was supported by the Spanish Ministry of Science and Innovation and European FEDER Fund under Project TIN2008-02236/TSI as well as by CDTI (Spain)and the companies INDRA, Unin Fenosa, Tecnobit, Visual Tool, Brainstorm, SAC and Technosafe under Project Cenit-HESPERIA.Peer reviewe

Optimal selection and location of bess systems in medium-voltage rural distribution networks for minimizing greenhouse gas emissions

This paper explores a methodology to locate battery energy storage systems (BESS) in rural alternating current (AC) distribution networks fed by diesel generators to minimize total greenhouse gas emissions. A mixed-integer nonlinear programming (MINLP) model is formulated to represent the problem of greenhouse gas emissions minimization, considering power balance and devices capabilities as constraints. To model the BESS systems, a linear relationship is considered between the state of charge and the power injection/consumption using a charging/discharging coefficient. The solution of the MINLP model is reached through the general algebraic modeling system by employing the BONMIN solver. Numerical results in a medium-voltage AC distribution network composed of 33 nodes and 32 branches operated with 12.66 kV demonstrate the effectiveness of including BESS systems to minimize greenhouse gas emissions in diesel generators that feeds rural distribution networks

Secret Sharing Based on a Hard-on-Average Problem

The main goal of this work is to propose the design of secret sharing schemes based on hard-on-average problems. It includes the description of a new multiparty protocol whose main application is key management in networks. Its unconditionally perfect security relies on a discrete mathematics problem classiffied as DistNP-Complete under the average-case analysis, the so-called Distributional Matrix Representability Problem. Thanks to the use of the search version of the mentioned decision problem, the security of the proposed scheme is guaranteed. Although several secret sharing schemes connected with combinatorial structures may be found in the bibliography, the main contribution of this work is the proposal of a new secret sharing scheme based on a hard-on-average problem, which allows to enlarge the set of tools for designing more secure cryptographic applications