RESUMO
Visible Light Communications (VLC) is a cutting edge technology for data communication that is being considered to be implemented in a wide range of applications such as Inter-vehicle communication or Local Area Network (LAN) communication. As a novel technology, some aspects of the implementation of VLC have not been deeply considered or tested. Among these aspects, security and its implementation may become an obstacle for VLCs broad usage. In this article, we have used the well-known Risk Matrix methodology to determine the relative risk that several common attacks have in a VLC network. Four examples: a War Driving, a Queensland alike Denial of Service, a Preshared Key Cracking, and an Evil Twin attack, illustrate the utilization of the methodology over a VLC implementation. The used attacks also covered the different areas delimited by the attack taxonomy used in this work. By defining and determining which attacks present a greater risk, the results of this work provide a lead into which areas should be invested to increase the safety of VLC networks.
Assuntos
Comunicação , Segurança Computacional , Luz , Redes LocaisRESUMO
Due to the massive insertion of embedded cameras in a wide variety of devices and the generalized use of LED lamps, Optical Camera Communication (OCC) has been proposed as a practical solution for future Internet of Things (IoT) and smart cities applications. Influence of mobility, weather conditions, solar radiation interference, and external light sources over Visible Light Communication (VLC) schemes have been addressed in previous works. Some authors have studied the spatial intersymbol interference from close emitters within an OCC system; however, it has not been characterized or measured in function of the different transmitted wavelengths. In this work, this interference has been experimentally characterized and the Normalized Power Signal to Interference Ratio (NPSIR) for easily determining the interference in other implementations, independently of the selected system devices, has been also proposed. A set of experiments in a darkroom, working with RGB multi-LED transmitters and a general purpose camera, were performed in order to obtain the NPSIR values and to validate the deduced equations for 2D pixel representation of real distances. These parameters were used in the simulation of a wireless sensor network scenario in a small office, where the Bit Error Rate (BER) of the communication link was calculated. The experiments show that the interference of other close emitters in terms of the distance and the used wavelength can be easily determined with the NPSIR. Finally, the simulation validates the applicability of the deduced equations for scaling the initial results into real scenarios.
RESUMO
Objetivo: Identificar las creencias, prácticas y necesidad de tratamiento periodontal en la población adulta que asiste al Colegio Odontológico Colombiano de Cali en el año 2003. Materiales y métodos: Estudio observacional, descriptivo de corte transversal. Por muestreo aleatorio simple proporcional, se obtuvo una muestra de 127 pacientes que asisten a las clínicas del Colegio Odontológico Colombiano. Para la recolección de datos se utilizó un cuestionario de 41 puntos (basado en el modelo de creencias en salud) sobre creencias de enfermedad periodontal y prácticas de higiene oral más un componente clínico en el que se utilizaron los índices IPB (Greene y Vermilion) y el ICNTP. Resultados: De 127 participantes, 69.3% creen que el sangrado gingival es signo de enfermedad, y 65.4% creen que la enfermedad periodontal es consecuencia de la mala higiene oral; 86.6% afirmaron que no tener la enfermedad les ayuda a desempeñarse socialmente. Además, 23% creen que prevenir la enfermedad periodontal es costoso. Sólo 2.3% presentaron valores menores a 12% (considerado como normal) en el índice de IPB. En 97.6% hubo algún parámetro de enfermedad periodontal como sangrado, cálculo y bolsas. Conclusiones: El modelo de creencias en salud permitió conocer las creencias sobre enfermedad periodontal. Aunque una gran proporción de los participantes sufre de enfermedad periodontal, un poco más de la mitad ignora que la padece; los participantes no cuentan con suficiente información sobre la enfermedad. Aunque los participantes se sienten susceptibles y conocen los beneficios de estar libre de la enfermedad periodontal, casi la totalidad de los encuestados están afectados.
Objective: To identify the beliefs, practices and periodontal treatment needs in an adult population who assist to the clinics of the Colegio Odontológico Colombiano, Cali, 2003. Materials and methods: An observacional, descriptive cross sectional study was made. A proportional simple random sampling was used. A sample of 127 patients was obtained from the total number of attendants to the clinics of the Colegio Odontológico Colombiano. For data collection a questionnaire of 41 items (based on the health belief model) about the beliefs and practices of periodontal disease was used. Also, a clinical approach was made using the oral Greene & Vermilion hygiene index and the index of community periodontal index of treatment needs (CPITN). Results: Of the total, 69.3% believed that gum bleeding is a sign of disease; 65.4% believed that the cause of periodontal disease is the bad oral hygiene. 86.6% said that not having the disease helps to have a better social relation. 23% thought that preventing the periodontal disease is expensive. 2.3% had the oral hygiene index lower than the normal one of 12%, and 97.6% presented a sign of periodontal disease like bleeding, calculus, pockets. Conclusions: The Health Belief Model allowed to know the beliefs on periodontal disease. Although a great proportion of participants suffer periodontal disease, more than half of the population ignores that they suffer the disease. The participants do not have sufficient information about this disease. Although the participants feel susceptible and know the benefits of not having periodontal disease, almost all of them were affected.