Dynamics in the vicinity of (101955) Bennu: Solar radiation pressure effects in equatorial orbits

Here we study the dynamical effects of the solar radiation pressure (SRP) on a spacecraft that will survey the near-Earth rotating asteroid (101955) Bennu when the projected shadow is accounted for. The spacecraft's motion near (101955) Bennu is modelled in the rotating frame fixed at the centre of the asteroid, neglecting the sun gravity effects. We calculate the solar radiation pressure at the perihelion, semi-major axis and aphelion distances of the asteroid from the Sun. The goals of this work are to analyse the stability for both homogeneous and inhomogeneous mass distribution and study the effects of the solar radiation pressure in equatorial orbits close to the asteroid (101955) Bennu. As results, we find that the mascon model divided into ten equal layers seems to be the most suitable for this problem. We can highlight that the centre point $E$8, which was linearly stable in the case of the homogeneous mass distribution, becomes unstable in this new model changing its topological structure. For a Sun initial longitude $\psi_0 = -180^o$, starting with the spacecraft longitude $\lambda = 0$, the orbits suffer fewer impacts and some (between 0.4 and 0.5 km), remaining unwavering even if the maximum solar radiation is considered. When we change the initial longitude of the Sun to $\psi_0 = -135^o$, the orbits with initial longitude $\lambda = 90^0$ appear to be more stable. Finally, when the passage of the spacecraft in the shadow is accounted for, the effects of solar radiation pressure are softened, and we find more stable orbits.Comment: Accepted 2017 May 10. Received 2017 April 29; in original form 2017 January 1

Impact of Oportunidades on skilled attendance at delivery in rural areas.

Oportunidades (formerly PROGRESA) is a conditional cash transfer program ran by the Mexican federal government designed to break the intergenerational cycle of poverty. Among other activities, it provides free delivery attendance for women enrolled in the program. Skilled attendance at delivery has been identified as an effective strategy to reduce maternal mortality, an important health problem in Mexico. In this paper we assess the impact of Oportunidades on skilled attendance at delivery taking advantage of the experimental design implemented for the evaluation of this program in rural areas and using a variety of analytical techniques. The main results of the study indicate that Oportunidades had, at best, only a small effect on skilled attendance at delivery in treatment communities. The program had larger effects on those women who had one birth just prior to the experimental treatment and another birth subsequent to the experimental treatment. These results should lead to a review about the strategies used by Oportunidades to increase skilled attendance at delivery

Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED

We present a way to engineer an effective anti-Jaynes-Cumming and a Jaynes-Cumming interaction between an atomic system and a single cavity mode and show how to employ it in reservoir engineering processes. To construct the effective Hamiltonian, we analyse considered the interaction of an atomic system in a \{Lambda} configuration, driven by classical fields, with a single cavity mode. With this interaction, we firstly show how to generate a decoherence-free displaced squeezed state for the cavity field. In our scheme, an atomic beam works as a reservoir for the radiation field trapped inside the cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401 (2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in high-Q resonators. In our scheme, all the atoms have to be prepared in the ground state and, as in the cited article, neither atomic detection nor precise interaction times between the atoms and the cavity mode are required. From this same interaction, we can also generate an ideal squeezed reservoir for atomic systems. For this purpose we have to assume, besides the engineered atom-field interaction, a strong decay of the cavity field (i.e., the cavity decay must be much stronger than the effective atom-field coupling). With this scheme, some interesting effects in the dynamics of an atom in a squeezed reservoir could be tested

Response to “Lean body mass should not be used as a surrogate measurement of muscle mass in malnourished men and women: Comment on Compher et al”

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Agricultural practices and ecosystem services provision to ensure the food, water and energy security.

Considering the importance of the agricultural sector in Brazil and the existence of areas in different stages of degradation, it becomes strategic for interventions that can generate socio-economic and environmental benefits and positive impacts to the tripod F-W-E. Thus, the present study is based on the Ribeirão das Lajes dam (RJ), a core area for the water supply of the second largest city in Brazil - Rio de Janeiro. A methodological approach will be developed that will generate an integrated assessment tool to evaluate the impact of agriculture practices and its potentiality to ecosystem services provision in the Nexus F-W-E approach

Paleoclimatic and paleobiological correlations by mammal faunas from Southern America and SW Europe

Proceedings of the 1" R.C.A.N.S. Congress, Lisboa, October 1992The preliminary results of a research dealing with the study of global changes in the last 5 Ma by correlations of continental records between the Northern and the Southern Hemispheres (SW Europe and Argentina, respectively) are reported. The first analyses of the evolutionary patterns point out, in Argentina, two different turnover times: the first one is characterized by a high percentage of mammalautochthonous extinctions placed in the span of time between the last Chapadmalalan and the first Ensenadan faunas, around 2.5-2.3 Ma. It is possible to identify a high percentage of new immigrant genera from North America in the first turnover, while the second one, associated to the "last Pleistocene megafaunal extinctions", probably occurred at the beginning of the "Glacial Pleistocene", around 1.0-0.8 Ma. The oxygen isotope composition of phosphate from fossil mammal bones was measured to have a better climatic resolution from faunal elements of two hemispheres and to compare them by results as quantitative as possible. The preliminary efforts are brought out on fourteen deposits from SE Spain. Isotopic and chemical results strongly suggest the existence of a relation between the oxygen isotope composition in various skeletal components and the taphonomic processes of a single deposit. The variations of 0180 in the mammal teeth of Equidae from SE Spain suggest a shift towards a colder environment from the older one, Huelago, to more recent deposits, as well as from Venta Micena to Fuensanta in agreement with the transition from the Middle to the Upper Villafranchian, around 2.5 Ma, and the transition between the "Preglacial" to the "Glacial" Pleistocene, around 1.9-0.8 Ma

Avaliação de modelo matemático-espectral para estimativa da safra de cana-de-açúcar.

Esse trabalho visa testar a aplicação e o ajuste de um modelo matemático-espectral para estimativa de biomassa de cana-de-açúcar, tomando como parâmetro de comparação a produtividade estimada pelo censo agropecuário do IBGE