ABSTRACT Air navigation is increasingly dependent on the use of Global Navigation Satellite Systems (GNSS). It allows the determination of the aircraft’s position in all phases of the flight and brings many advantages. Although GNSS navigation results in gains, the radio signals from these systems are strongly influenced by the ionospheric environment. It introduces errors that can affect the accuracy, integrity, availability and continuity requirements established by the International Civil Aviation Organization (ICAO). The ionospheric layer has different behaviors depending on the latitude, time of day, season of the year, geomagnetic activity and solar cycle. Since Brazil is located in a region of low latitudes, it experiences a series of unique challenges when compared to regions of mid-latitudes. For this reason, the application of GNSS-based technologies in aviation over the Brazilian territory requires an in-depth assessment of the ionosphere effects. Therefore, the Instituto Nacional de Ciência e Tecnologia (INCT) named GNSS Technology for Supporting Air Navigation was formed in 2017 to better assess the ionosphere impacts and assist government agencies and companies in the development of safe air navigation procedures over Brazil in a near future. This paper presents the most relevant advances achieved so far within this multidisciplinary project that involves Brazilian research centers and universities.

Abstract The present work describes the use of a simulation model based on asymptotic methods (ray tracing) on the propagation of ultra-wideband radio signals in a densely-arborized urban channel. The model was previously validated and adjusted using data obtained from measurement campaigns in the millimeter-wave band in locations different from the one to be analyzed here. The simulation uses deterministic methods to predict the received power, cross-polar discrimination, root mean square delay spread, and mean delay in a channel with a high density of scatterers (trees, buildings, and poles). Simulated signals were transmitted in the vertical and horizontal polarizations, considering non-specular reflections caused by rough surfaces and the effect of the transmitter’s height variation in outdoor channels.

Abstract The two-dimensional ray tracing method allows an easy and fast modeling of tropospheric propagation in the microwave frequency range. A version of this method that determines ray trajectories, amplitudes and delays of the electromagnetic field, as well as the propagation loss in a two-dimensional inhomogeneous environment will be described. The implemented algorithm may consider generalized maps of modified refractivity (or refractive modulus), including not only the vertical gradients, but also their horizontal variations along the path between transmitter and receiver. Next, the present paper will discuss the results from the application of a model of evaporation duct height to data from instruments installed in sea buoys located along the Brazilian coast. Finally, the results from the application of the ray-tracing model to evaporation ducts will be presented, to analyze the propagation of microwave signals in the maritime environment. These results will also be compared with corresponding ones from the software Advanced Refractive Effects Prediction System 3.6, based on the numerical solution of a parabolic equation.

RESUMO Objetivo: determinar o índice de trauma cardíaco fatal na cidade de Manaus e esclarecer os mecanismos de trauma e de morte, o tratamento hospitalar prévio, assim como as lesões associadas ao trauma cardíaco. Métodos: estudo retrospectivo, observacional, transversal, que revisou os laudos de necropsias do Instituto Médico Legal de Manaus entre novembro de 2015 e outubro de 2016, cuja causa mortis foi lesão cardíaca. Resultados: o índice de trauma cardíaco foi de 5,98% (138 casos) dentre 2306 necropsias realizadas no período do estudo. Homens foram afetados em 92%. A mediana de idade foi de 27 anos (14 a 83). A arma de fogo foi o mecanismo de trauma em 62,3% e a arma branca em 29,7%. A exsanguinação foi responsável pela maioria das mortes e o tamponamento cardíaco esteve presente em segundo lugar. Óbito no local ocorreu em 86,2%. Os ventrículos foram as câmaras mais lesionadas. O hemotórax foi descrito em 90,6%. Apenas 23 (16,7%) doentes foram removidos até o pronto socorro, porém seis deles (26,2%) não foram submetidos à toracotomia, apenas à drenagem de tórax. O pulmão foi acometido em 57% unilateralmente e 43% bilateralmente. Conclusão: o trauma cardíaco fatal representou um índice de 5,98% na cidade de Manaus. A maioria dos doentes morre na cena do trauma, geralmente devido à exsanguinação causada por ferimento de arma de fogo. Cerca de um quarto dos pacientes que chegaram ao pronto socorro e morreram, não foram diagnosticados com trauma cardíaco em tempo hábil.

ABSTRACT Objective: to determine the frequency of fatal cardiac trauma in the city of Manaus, Brazil, between November 2015 and October 2016, and to clarify the mechanisms of trauma and death, previous hospital treatment, as well as the injuries associated with cardiac trauma. Methods: retrospective, observational, and cross-sectional study, which reviewed the necropsy reports of individuals whose cause of death was cardiac injury. Results: the cardiac trauma rate was of 5.98% (138 cases) out of 2,306 necropsies performed in the study period by Instituto Médico Legal (IML) de Manaus (IML is a Brazilian institute responsible for necropsies and cadaveric reports). Males accounted for 92% of the cases. The median age was 27 years (14-83). Gunshot wounds (GSW) was the trauma mechanism in 62.3% and stab wound (SW) in 29.7%. Exsanguination was responsible for most of the deaths and cardiac tamponade was present in second place. On-site death occurred in 86.2% of the cases. The ventricles were the most common site of cardiac injury. Hemothorax was identified in 90.6% of the individuals. Only 23 patients (16.7%) were taken to the hospital (Emergency Room), but six (26.2%) were submitted only to chest drainage, not to thoracotomy. The lung was unilaterally affected in 57% of the cases and bilaterally in 43%. Conclusion: fatal cardiac trauma represented an index of 5.98% in the city of Manaus. Most patients die at the scene of the trauma, usually due to exsanguination caused by gunshot wound. About a quarter of patients who reached the hospital and died were not diagnosed with cardiac trauma in time.

A distribution-free model is presented for the cumulative distribution function of the differential rain attenuation between two co-channel converging terrestrial links operating at frequencies above 10 GHz. This is accomplished through an extension of the Misme and Fimbel model, which determines the cumulative distribution of the rain attenuation on an isolated link from its parameters and data for the radio climatic region, as well as concepts from probability theory. Next, model predictions and experimental results are compared and effects from variations of the angle between the links and of the path length are studied. Finally, rain effects on the cumulative distribution of the C/I ratio between the desired and interference powers at the same receiver are analyzed, considering the angular discrimination of the receiving antenna.