Orbital evolution of the mu and nu dust ring particles of Uranus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Time analysis for temporary gravitational capture - Stable orbits

In a previous work, Vieira Neto & Winter (2001) numerically explored the capture times of particles as temporary satellites of Uranus. The study was made in the framework of the spatial, circular, restricted three-body problem. Regions of the initial condition space whose trajectories are apparently stable were determined. The criterion adopted was that the trajectories do not escape from the planet during an integration of 10(5) years. These regions occur for a wide range of orbital initial inclinations (i). In the present work it is studied the reason for the existence of such stable regions. The stability of the planar retrograde trajectories is due to a family of simple periodic orbits and the associated quasi-periodic orbits that oscillate around them. These planar stable orbits had already been studied (Henon 1970; Huang & Innanen 1983). Their results are reviewed using Poincare surface of sections. The stable non-planar retrograde trajectories, 110 degrees less than or equal to i < 180, are found to be tridimensional quasi-periodic orbits around the same family of periodic orbits found for the planar case (i = 180 degrees). It was not found any periodic orbit out of the plane associated to such quasi-periodic orbits. The largest region of stable prograde trajectories occurs at i = 60 degrees. Trajectories in such region are found to behave as quasi-periodic orbits evolving similarly to the stable retrograde trajectories that occurs at i = 120 degrees.

On the scattering of comets by a planet

In this paper, numerical simulations are made, using the three-dimensional restricted three-body problem as the mathematical model, to calculate the effects of a swing-by with the planet Saturn in the orbit of a comet. To show the results, the orbit of the comet is classified in four groups: elliptic direct, elliptic retrograde, hyperbolic direct and hyperbolic retrograde. Then, the modification in the orbit of the comet due to the close approach is shown in plots that specify from which group the comet's orbit is coming and to which group it is going. Several families of orbits are found and shown in detail. An analysis about the trends as parameters (position and velocity at the periapse) vary is performed and the influence of each of them is shown and explained. The result is a collection of maps that describe the evolution of the trajectory of the comet due to the close approach. Those maps can be used to estimate the probability of some events, like the capture or escape of a comet. An example of this technique is shown in the paper. (C) 2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

Effects of the planetary migration on some primordial satellites of the outer planets

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The role of Mab as a source for the mu ring of Uranus (Research Note)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Time analysis for temporary gravitational capture: Satellites of Uranus

We study the problem of gravitational capture in the framework of the Sun-Uranus-particle system. Part of the space of initial conditions is systematically explored, and the duration of temporary gravitational capture is measured. The location and size of different capture-time regions are given in terms of diagrams of initial semimajor axis versus eccentricity. The other initial orbital elements - inclination (i), longitude of the node (Ω), argument of pericenter (ω), and time of pericenter passage (τ) - are first taken to be zero. Then we investigate the cases with ω = 90°, 180°, and 270°. We also present a sample of results for Ω = 90°, considering the cases i = 60°, 120°, 150°, and 180°. Special attention is given to the influence of the initial orbital inclination, taking orbits initially in opposition at pericenter. In this case, the initial inclination is varied from 0° to 180° in steps of 10°. The success of the final stage of the capture problem, which involves the transformation of temporary captures into permanent ones, is highly dependent on the initial conditions associated with the longest capture times. The largest regions of the initial-conditions space with the longest capture times occur at inclinations of 60°-70° and 160°. The regions of possible stability as a function of initial inclination are also delimited. These regions include not only a known set of retrograde orbits, but also a new sort of prograde orbit with inclinations greater than zero.

Dinâmica e estabilidade de satélites regulares como consequência da migração planetária

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

TERRESTRIAL PLANET FORMATION IN A PROTOPLANETARY DISK WITH A LOCAL MASS DEPLETION: A SUCCESSFUL SCENARIO FOR THE FORMATION OF MARS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sobre a dinâmica de rotação de um planeta através de um sistema médio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Planet formation in a triple stellar system: implications of the third star's orbital inclination

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Fungal Planet description sheets: 320-370

Novel species of fungi described in the present study include the following from Malaysia: Castanediella eucalypti from Eucalyptus pellita, Codinaea acacia from Acacia mangium, Emarcea eucalyptigena from Eucalyptus brassiana, Myrtapenidiella eucalyptorum from Eucalyptus pellita, Pilidiella eucalyptigena from Eucalyptus brassiana and Strelitziana malaysiana from Acacia mangium. Furthermore, Stachybotrys sansevieriicola is described from Sansevieria ehrenbergii (Tanzania), Phacidium grevilleae from Grevillea robusta (Uganda), Graphium jumulu from Adansonia gregorii and Ophiostoma eucalyptigena from Eucalyptus marginata (Australia), Pleurophoma ossicola from bone and Plectosphaerella populi from Populus nigra (Germany), Colletotrichum neosansevieriae from Sansevieria trifasciata, Elsinoë othonnae from Othonna quinquedentata and Zeloasperisporium cliviae (Zeloasperisporiaceae fam. nov.) from Clivia sp. (South Africa), Neodevriesia pakbiae, Phaeophleospora hymenocallidis and Phaeophleospora hymenocallidicola on leaves of a fern (Thailand), Melanconium elaeidicola from Elaeis guineensis (Indonesia), Hormonema viticola from Vitis vinifera (Canary Islands), Chlorophyllum pseudoglobossum from a grassland (India), Triadelphia disseminata from an immunocompromised patient (Saudi Arabia), Colletotrichum abscissum from Citrus (Brazil), Polyschema sclerotigenum and Phialemonium limoniforme from human patients (USA), Cadophora vitícola from Vitis vinifera (Spain), Entoloma flavovelutinum and Bolbitius aurantiorugosus from soil (Vietnam), Rhizopogon granuloflavus from soil (Cape Verde Islands), Tulasnella eremophila from Euphorbia officinarum subsp. echinus (Morocco), Verrucostoma martinicensis from Danaea elliptica (French West Indies), Metschnikowia colchici from Colchicum autumnale (Bulgaria), Thelebolus microcarpus from soil (Argentina) and Ceratocystis adelpha from Theobroma cacao (Ecuador). Myrmecridium iridis (Myrmecridiales ord. nov., Myrmecridiaceae fam. nov.) is also described from Iris sp. (The Netherlands). Novel genera include (Ascomycetes): Budhanggurabania from Cynodon dactylon (Australia), Soloacrosporiella, Xenocamarosporium, Neostrelitziana and Castanediella from Acacia mangium and Sabahriopsis from Eucalyptus brassiana (Malaysia), Readerielliopsis from basidiomata of Fuscoporia wahlbergii (French Guyana), Neoplatysporoides from Aloe ferox (Tanzania), Wojnowiciella, Chrysofolia and Neoeriomycopsis from Eucalyptus (Colombia), Neophaeomoniella from Eucalyptus globulus (USA), Pseudophaeomoniella from Olea europaea (Italy), Paraphaeomoniella from Encephalartos altensteinii, Aequabiliella, Celerioriella and Minutiella from Prunus (South Africa). Tephrocybella (Basidiomycetes) represents a novel genus from wood (Italy). Morphological and culture characteristics along with ITS DNA barcodes are provided for all taxa.

A nação pela pedra: coleções de paleontologia no Brasil, 1836-1844

A formação e o estudo de coleções de história natural e de paleontologia participaram da instauração da ordem política do Império do Brasil, delineando também uma ordem científica. A simbiose entre ciência e nação encontrou em Peter W. Lund, iniciador dos estudos de paleontologia em nosso país, um agente ativo e constante. As coleções e escritos desse naturalista deram amparo à visualização do passado e à escrita da história em museus, instituições científicas e culturais brasileiras e europeias. As disputas pelo ordenamento político sob as Regências e a Maioridade foram acompanhadas de perto pelo estudo e a explicação das formas de vida e do globo no passado.

Intercomparison of integrated water vapor estimates from multisensors in the amazonian region

Water vapor is an atmospheric component of major interest in atmospheric science because it affects the energy budget and plays a key role in several atmospheric processes. The Amazonian region is one of the most humid on the planet, and land use change is able to affect the hydrologic cycle in several areas and consequently to generate severe modifications in the global climate. Within this context, accessing the error associated with atmospheric humidity measurement and the validation of the integrated water vapor (IWV) quantification from different techniques is very important in this region. Using data collected during the Radiation, Cloud, and Climate Interactions in Amazonia during the Dry-to-Wet Transition Season (RACCI/DRY-TO-WET), an experiment carried out in southwestern Amazonia in 2002, this paper presents quality analysis of IWV measurements from RS80 radiosondes, a suite of GPS receivers, an Aerosol Robotic Network (AERONET) solar radiometer, and humidity sounding from the Humidity Sounder for Brazil (HSB) aboard the Aqua satellite. When compared to RS80 IWV values, the root-mean-square (RMS) from the AERONET and GPS results are of the order of 2.7 and 3.8 kg m(-2), respectively. The difference generated between IWV from the GPS receiver and RS80 during the daytime was larger than that of the nighttime period because of the combination of the influence of high ionospheric activity during the RACCI experiment and a daytime drier bias from the RS80.

Second and Third Order Ionospheric Effects on GNSS Positioning: A Case Study in Brazil

The Global Positioning System (GPS) transmits signals in two frequencies. It allows the correction of the first order ionospheric effect by using the ionosphere free combination. However, the second and third order ionospheric effects, which combined may cause errors of the order of centimeters in the GPS measurements, still remain. In this paper the second and third order ionospheric effects, which were taken into account in the GPS data processing in the Brazilian region, were investigated. The corrected and not corrected GPS data from these effects were processed in the relative and precise point positioning (PPP) approaches, respectively, using Bernese V5.0 software and the PPP software (GPSPPP) from NRCAN (Natural Resources Canada). The second and third order corrections were applied in the GPS data using an in-house software that is capable of reading a RINEX file and applying the corrections to the GPS observables, creating a corrected RINEX file. For the relative processing case, a Brazilian network with long baselines was processed in a daily solution considering a period of approximately one year. For the PPP case, the processing was accomplished using data collected by the IGS FORT station considering the period from 2001 to 2006 and a seasonal analysis was carried out, showing a semi-annual and an annual variation in the vertical component. In addition, a geographical variation analysis in the PPP for the Brazilian region has confirmed that the equatorial regions are more affected by the second and third order ionospheric effects than other regions.

The limits of human development and the use of energy and natural resources

The development of nations is an unquestionable requirement. A lot of challenges concerning health, education and economy are present. A discussion on these development models has occupied the minds of decision makers in recent years. When energy supply and demand is considered, the situation becomes critical and the crucial question is: how to improve the quality of life of developing countries based on available models of development that are related to the life style of developed countries, for which the necessary use and waste of energy are present? How much energy is essential to humanity for not so as to endangering the survival conditions of future generations? the human development index (HDI) establishes the relationship among energy use, economic growth and social growth. Here it can be seen that 75% of the world population has a significant energy consumption potential. This is a strong reason to consider that the sustainable development concepts on energy policies are strategic to the future of the planet. This paper deals with the importance of seeking alternative development models for human development balance, natural resources conservation and environment through rational energy use concepts. (c) 2004 Elsevier Ltd. All rights reserved.