Variabilidade espacial do fósforo de solo sob pastagem de Brachiaria brizantha de baixa produtividade

A falta de dados de campo sobre o fósforo (P) do solo sob pastagens cultivadas de baixa produtividade na Região do Cerrado e o levantamento de outros possíveis problemas ligados ao P motivaram o presente trabalho. Estudou-se a variabilidade espacial do fósforo de um Latossolo Vermelho cultivado por 10 anos com Brachiaria brizantha (BB), sem aplicação de fertilizantes, em área experimental localizada em Planaltina (GO). A amostragem do solo foi realizada em malha sistemática de 10 em 10 metros, em 98 pontos, antes (entre touceiras e sob touceira) e depois da implantação do experimento (após fertilização). A gramínea forrageira também foi coletada e separada em frações para a determinação dos teores de N e P. O conteúdo do P no solo foi determinado pelo método de resina (Pr) e complementado por análises de cinética de troca isotópica com 32P. A descrição da variabilidade espacial foi realizada por meio de análises estatística descritiva e geoestatística. As amostras sob touceiras apresentaram médias e medianas de P 45 % superiores entre touceiras, provavelmente associada à maior concentração do sistema radicular da BB, maior conteúdo de matéria orgânica do solo e da reciclagem do P via touceira da planta. A variabilidade espacial do Pr foi alta principalmente após a aplicação do fertilizante. Essa variável não apresentou dependência espacial para uma amostragem regular de 10 metros. O conhecimento da variabilidade do P em solos sob pastagens cultivadas de baixa produtividade revelou problemas relacionados à metodologia de amostragem tradicionalmente utilizada e à aplicação do fertilizante realizada.Studies on soil phosphorus (P) of low productivity cultivated pastures in Cerrado (Brazilian Savanna) areas and surveys on other possible problems related to P are scarce. The spatial variability of soil phosphorus content of a Rhodic Ferralsol was studied in a low productivity pasture of Brachiaria brizantha (BB) grown for 10 years, without fertilizer application, in an experimental area at Planaltina (GO), Brazil. Soil samplings were performed on a regular grid of 10 by 10 meters, with 98 sampling points before (between tussocks and under tussocks) and after the establishment of the experiment (after fertilizing). On the same grid, forage plants were collected and separated into fractions for N and P content analyses. Soil available phosphate was determined by the resin method (Pr) and complemented by the 32P isotopic exchange kinetics analysis. Descriptive statistical and geostatistical analyses were utilized to describe the spatial variability. The Pr content on soil samples under tussocks presented mean and median values 45% larger than in soil samples taken between tussocks. The higher variation is probably related to the greater concentration of BB roots, soil organic matter content and soil P recycled through the plants tussocks. The spatial variability of Pr in this soil was high especially after fertilizer application. This variable did not present spatial dependence for the regular 10 m sampling. The generated knowledge on P variability of soils under low productivity cultivated pastures revealed problems related to the sampling methodology traditionally utilized and to P application

Removing Barriers, Integrating Research, Spreading Excellence: The European Satellite Communications Network of Excellence "SatNEx"

Within the recently launched 6th Research Framework Programme of the European Commission, 21 major players in satellite communications research have joined forces to implement the European Satellite Communications Network of Excellence (SatNEx). The primary goal of SatNEx is to achieve long-lasting integration of the European research in satellite communication and to develop a common base of knowledge, thus contributing to the realization of the European Research Area. This paper discusses the background and motivation for implementation of the network and highlights the SatNEx mission and key objectives. A top-level overview is then provided including a description of the consortium, the Joint Programme of Activities (JPA) and the time schedule with deliverables and milestones. Finally, an update of ongoing work is presented

Synthèse des unités mémoire pour le traitement du signal

Les études concernant la synthèse automatique de systèmes numériques ont donné naissance à de nombreux outils synthèse architecturale s'appliquant à différents domaines d'application. Ainsi, les méthodes d'ordonnancement permettent de concevoir les unités de traitement (UT). Les unités de contrôle (UC) sont décrites sous forme d'une machine d'états qui peuvent être, dans la plupart des cas, matérialisées par un outil de synthèse logique du commerce. Les unités de mémorisation (UM) et de communication (UCom) restent, quand à elles, à la charge du concepteur. Cette étude propose une formalisation des problèmes liés à la synthèse des UM en vue d'une intégration dans un outil de synthèse d'architecture. Après une introduction de la synthèse d'architecture et des problèmes spécifiques au TS, nous examinerons l'état de la recherche concernant la synthèse des UM. Nous proposerons une démarche visant à générer ces unités de façon automatique, puis nous présenterons une première série de résultats. Enfin, nous concluerons et nous évoquerons les perspectives afin d'optimiser cette synthèse

Иловые растворы морских отложений в природной экосистеме шельфа Черного моря

Иловые растворы донных морских отложений рассматриваются как часть гидрохимической и экологической системы шельфа Черного моря. Они образуют нижнюю сероводородную (восстановительную) зону, которая подстилает кислородную (окислительную) зону моря. Иловые растворы влияют на эколого-гидрохимическую среду шельфа как источник поступления сероводорода, аммония, микроэлементов в придонный слой морской воды.Мулові розчини донних морських відкладів розглядаються як частина гідрохімічної та екологічної системи шельфу Чорного моря. Вони утворюють нижню сірководневу (відновлювальну) зону, яка підстелює кисневу (окислювальну) зону моря. Мулові розчини впливають на еколого-гідрохімічне середовище шельфу як джерело надходження сірководню, амонію, мікроелементів у придонний шар морської води.Silt solutions of seabed sediments are considered as a part of the hydrogeochemical and ecological system of the Black Sea shelf. They form the lower hydrogen sulphide (reducing) zone spreading under the oxygen (oxidizing) zone of sea water. Silt solutions have an influence on the ecohydrochemical medium of the shelf as a source of hydrogen sulphide, ammonia and microelements in to the ground layer of sea water

SYNTHESE DE HAUT NIVEAU DES ARCHITECTURES ASYNCHRONES EN TRAITEMENT NUMERIQUE DU SIGNAL

RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF