EGNOS based virtual reference stations

We propose the use of the European Geostationary Navigation Overlay Service (EGNOS) data - real time on line data provided by SISNeT - to develop Virtual Reference Stations and, thus, increase the quality of the Position, Velocity an Time (PVT) solution of receivers unable to interface directly with EGNOS. A Virtual Reference Station (VRS) is a concept where the existence of a differential reference station located near a mobile rover is simulated by software in order to increase the accuracy of the PVT solution of the mobile GNSS receiver

A descoberta da Dupla Hélice do DNA: contributo para possíveis narrativas

Até ao final dos anos 40, o DNA não era reconhecido como portador da informação genética. Era uma molécula demasiado simples, difícil de isolar e incompatível com os métodos de análise da química orgânica e da biologia. Quando alguns cientistas começam a acreditar na importância do DNA, percebem que são incapazes, tecnicamente, de determinar a sua estrutura. É nesse espírito que James Watson vai para a Europa e, na primavera de 1951, ao assistir à conferência de Maurice Wilkins, da King’s College, onde vê uma fotografia do padrão de difração de raios X, percebe que será esta a técnica chave para a determinação da estrutura do DNA e, subsequentemente, dos segredos da vida. É este o início de uma das possíveis narrativas sobre uma das principais descobertas científicas do séc. XX que muitas vezes se reduz a: “A dupla hélice do DNA foi descoberta em 1953 por Watson e Crick”. Esta dissertação propõe-se a demonstrar que, apesar de em termos estritos, se tratar de uma afirmação verdadeira, não é suficiente para garantir uma experiência pedagógica significativa, nem fazer jus ao que é o funcionamento da ciência, com todas as implicações humanas, contextuais, éticas, consequências e impacto

Real Time Internet DGPS Service

The accuracy of the Navigation Satellite Timing and Ranging (NAVSTAR) Global Positioning System (GPS) measurements is insufficient for many outdoor navigation tasks. As a result, in the late nineties, a new methodology – the Differential GPS (DGPS) – was developed. The differential approach is based on the calculation and dissemination of the range errors of the GPS satellites received. GPS/DGPS receivers correlate the broadcasted GPS data with the DGPS corrections, granting users increased accuracy. DGPS data can be disseminated using terrestrial radio beacons, satellites and, more recently, the Internet. Our goal is to provide mobile platforms within our campus with DGPS data for precise outdoor navigation. To achieve this objective, we designed and implemented a three-tier client/server distributed system that establishes Internet links with remote DGPS sources and performs campus-wide dissemination of the obtained data. The Internet links are established between data servers connected to remote DGPS sources and the client, which is the data input module of the campus-wide DGPS data provider. The campus DGPS data provider allows the establishment of both Intranet and wireless links within the campus. This distributed system is expected to provide adequate support for accurate (submetric) outdoor navigation tasks

Evaluation of a real time DGPS data server

The goal of the this paper is to show that the DGPS data Internet service we designed and developed provides campus-wide real time access to Differential GPS (DGPS) data and, thus, supports precise outdoor navigation. First we describe the developed distributed system in terms of architecture (a three tier client/server application), services provided (real time DGPS data transportation from remote DGPS sources and campus wide data dissemination) and transmission modes implemented (raw and frame mode over TCP and UDP). Then we present and discuss the results obtained and, finally, we draw some conclusions

Internet based VRS Code Positioning

Absolute positioning – the real time satellite based positioning technique that relies solely on global navigation satellite systems – lacks accuracy for several real time application domains. To provide increased positioning quality, ground or satellite based augmentation systems can be devised, depending on the extent of the area to cover. The underlying technique – multiple reference station differential positioning – can, in the case of ground systems, be further enhanced through the implementation of the virtual reference station concept. Our approach is a ground based system made of a small-sized network of three stations where the concept of virtual reference station was implemented. The stations provide code pseudorange corrections, which are combined using a measurement domain approach inversely proportional to the distance from source station to rover. All data links are established trough the Internet

Implementation of a Campus wide DGPS Data Server

Although the Navigation Satellite Timing and Ranging (NAVSTAR) Global Positioning System (GPS) is, de facto, the standard positioning system used in outdoor navigation, it does not provide, per se, all the features required to perform many outdoor navigational tasks. The accuracy of the GPS measurements is the most critical issue. The quest for higher position readings accuracy led to the development, in the late nineties, of the Differential Global Positioning System (DGPS). The differential GPS method detects the range errors of the GPS satellites received and broadcasts them. The DGPS/GPS receivers correlate the DGPS data with the GPS satellite data they are receiving, granting users increased accuracy. DGPS data is broadcasted using terrestrial radio beacons, satellites and, more recently, the Internet. Our goal is to have access, within the ISEP campus, to DGPS correction data. To achieve this objective we designed and implemented a distributed system composed of two main modules which are interconnected: a distributed application responsible for the establishment of the data link over the Internet between the remote DGPS stations and the campus, and the campus-wide DGPS data server application. The DGPS data Internet link is provided by a two-tier client/server distributed application where the server-side is connected to the DGPS station and the client-side is located at the campus. The second unit, the campus DGPS data server application, diffuses DGPS data received at the campus via the Intranet and via a wireless data link. The wireless broadcast is intended for DGPS/GPS portable receivers equipped with an air interface and the Intranet link is provided for DGPS/GPS receivers with just a RS232 DGPS data interface. While the DGPS data Internet link servers receive the DGPS data from the DGPS base stations and forward it to the DGPS data Internet link client, the DGPS data Internet link client outputs the received DGPS data to the campus DGPS data server application. The distributed system is expected to provide adequate support for accurate (sub-metric) outdoor campus navigation tasks. This paper describes in detail the overall distributed application

Dermocosmetic care for rosacea

Rosacea is a chronic inflammatory skin disease that primarily affects the central area of the face; it is characterized by erythema, papules, pustules, nodules, and telangiectasia. This condition arises between 30-60 years of age, and it usually occurs in fair-skinned people. Rosacea is characteristic of sensitive skin, as it is a disease marked with punctuated phases of exacerbated signs and symptoms that alternate with periods of remission. Humans have long incorporated cosmetics in their daily habits; given the scientific and technological developments that emerged in cosmeceuticals or dermocosmetics, the current cosmetic options are now used for much more than adornment or cleansing. The purpose of cosmetic care in rosacea is to restore the balance of the skin, while reducing the underlying inflammation, sensitivity, and dehydration. This review aims to highlight the various dermocosmetic care options that can reduce discomfort for and bring benefit to patients who have reactive and sensitive skin associated with rosacea. Additionally, this report discusses how pharmacists - public health agents - can and should offer counseling and support interventions to patients once oral or topical medications are dispensed to this pathology

Aplicação do modelo SIMWE na definição de áreas suscetíveis à erosão linear: estudo de caso na Região Demarcada do Douro (RDD)

O objetivo deste trabalho centra-se na avaliação da suscetibilidade à erosão linear na RDD, apresentando-se os resultados obtidos através da aplicação do modelo SIMWE (SIMulated Water Erosion). Procede-se, ainda, à análise dos resultados por comparação com as características hidrológicas (capacidade de infiltração, condutividade hidráulica), texturais e estruturais do solo (avaliada pela resistividade elétrica) em áreas classificadas de elevada erosão pelo SIMWE. O estudo demonstra uma associação entre a distribuição espacial das feições erosivas com valores altos de profundidade da lâmina de água e valores reduzidos de fluxo de água que se coadunam com os valores reduzidos de resistividade elétrica em setores coincidentes.Os sectores com maior percentagem de feições erosivas relacionadas ao fluxo de sedimentos, a capacidade de transporte e a concentração de sedimentos assumem valores de suscetibilidade médios. Estes aliam-se a uma condutividade hidráulica e a capacidade de infiltração do solo com valores bastante reduzidos condizentes com a sua textura fina, permitindo um aumento do escoamento superficial e o desenvolvimento de erosão linear.This paper focuses the evaluation of susceptibility to linear erosion in the RDD, presenting the results of SIMWE (Simulated Water Erosion) model application. Furthermore, we also proceed to the results analysis by comparing the hydrological characteristics (infiltration capacity, hydraulic conductivity), soil texture and structure (evaluated by the electrical resistivity) in the high erosion areas defined through SIMWE. The study shows an association between the spatial distribution of erosivefeatures with high values of water depth and reduced water discharge values that are consistent with the reduced values of electrical resistivity sectors. The areas with the highest percentage of erosive features related to sediment flux, the transport capacity and the sediment concentration assume medium susceptibility values. These combined to a hydraulic conductivity and soil infiltration capacity at very low values is consistentwith its fine texture, allowing increased runoff and the development of linear erosion

Estabilidade de taludes em terraços agrícolas na Região Demarcada do Douro : modelação de base estatística

Para a avaliação da instabilidade de vertentes em terraços agrícolas na Região Demarcada do Douro (Quinta das Carvalhas) foram aplicados dois métodos de base estatística - Regressão Logística e Valor Informativo que se fundamentam na correlação estatística entre as ocorrências (variável dependente) e os fatores condicionantes (variáveis independentes). Como fatores condicionantes foram considerados o declive, a curvatura e a exposição, as áreas contributivas, a humidade relativa, o declive do talude em terra e a ocupação do solo. As variáveis armação do terreno e uso do solo foram obtidas através da vetorização com base no ortofotomapacom uma resolução de 50 cm. Foi efetuado o levantamento das ocorrências que resultou num registo de 329 situações de instabilidade. Foram feitos dois cenários com a utilização de modelos digitais de elevação (comresolução de 5 m) construídos com informação de origem diferente: um a partir da altimetria (à escala de 1:25000) com equidistância das curvas de nível de 10 m, pontos cotados e rede hidrográfica (MDT A), e outro a partir de fotografias aéreas com resolução de 50 cm (MDT B). 50% do inventário foi utilizado na modelação e a outra metade foi utilizada na validação com recurso às tabelas de contingência. Daqui verificamos que o Valor Informativo com o MDT A apresenta a melhor validação com um valor de 5.22 na relação True Positive Rate (TPR)/False Positive Rate (FPR).The evaluation of the slope instability in agricultural terraces in the Douro Region (Quinta das Carvalhas) was done by two statistical based methods - Logistic Regression and Information Value Method based on the statistical correlation between the occurrences (dependent variable) and the conditioning factors (independent variables). As conditioning factors were considered the slope, curvature and aspect, contributing areas, the relative humidity, the slope of the agricultural terrace riser and land use. The variables related with the agricultural terraces structures and land usewere obtained by vectorization based on orthophotomap with a resolution of 50 cm. The field camping carried out 329 instability record points.Two scenarios were considered through two elevation models (with a resolution of 5 meters) constructed with different base information: one from contours (scale 1: 25,000) with contour interval of 10 m, spot heights and 3D hydrographic network, and another from aerial photographs with a resolution of 50 cm. 50% of the inventory was used in the modelling and the other half was used to validate with the use of contingency tables. The DTM A Information Value method has the best validation with a value of 5:22 in relation True Positive Rate (TPR)/False Positive Rate (FPR)