799 research outputs found
System design of the Pioneer Venus spacecraft. Volume 14: Test planning trades
Pioneer Venus system test plans and trade studies which were first published as Study Tasks (References 1 through 5) are reviewed. The plan and trade studies are presented in a condensed form. Greater detail may be found in the referenced study tasks if desired. All significant conclusions and plan outlines of the original studies are, presented
The weight of water
Leonardo da Vinci’s pioneering work on hydrostatics combined traditional knowledge and innovative empiricism in an attempt to understand an object fraught with paradox: the water-filled container
Evaluation of the deposition, infiltration and drainage of the atmospheric pollutants in the vadose zone
In the last decades, a large effort has been carried out to reduce atmospheric pollutant emissions in Europe. However, despite the progresses of the last 30 years (Rogora et al., 2016), water and soil acidification, nutrition unbalance in forest trees, and eutrophication in surface waters are still of great concern. In particular, nutrients that fall on the ground from the atmosphere represent a minor component of the total nitrogen input to soils, especially when compared to agricultural, civil and industrial inputs (EEA, 2005). Although often underestimated, this source apportionment becomes a part of leaching from the soil to groundwater. Therefore, the overarching goal of this study is to identify anthropogenic background values of pollutants in groundwater, not related to direct sources of contamination (e.g., industrial wastes, leakages from sewage systems, fertilizers)
First astronomical unit scale image of the GW Ori triple. Direct detection of a new stellar companion
Young and close multiple systems are unique laboratories to probe the initial
dynamical interactions between forming stellar systems and their dust and gas
environment. Their study is a key building block to understanding the high
frequency of main-sequence multiple systems. However, the number of detected
spectroscopic young multiple systems that allow dynamical studies is limited.
GW Orionis is one such system. It is one of the brightest young T Tauri stars
and is surrounded by a massive disk. Our goal is to probe the GW Orionis
multiplicity at angular scales at which we can spatially resolve the orbit. We
used the IOTA/IONIC3 interferometer to probe the environment of GW Orionis with
an astronomical unit resolution in 2003, 2004, and 2005. By measuring squared
visibilities and closure phases with a good UV coverage we carry out the first
image reconstruction of GW Ori from infrared long-baseline interferometry. We
obtain the first infrared image of a T Tauri multiple system with astronomical
unit resolution. We show that GW Orionis is a triple system, resolve for the
first time the previously known inner pair (separation 1.4 AU) and
reveal a new more distant component (GW Ori C) with a projected separation of
8 AU with direct evidence of motion. Furthermore, the nearly equal (2:1)
H-band flux ratio of the inner components suggests that either GW Ori B is
undergoing a preferential accretion event that increases its disk luminosity or
that the estimate of the masses has to be revisited in favour of a more equal
mass-ratio system that is seen at lower inclination. Accretion disk models of
GW Ori will need to be completely reconsidered because of this outer companion
C and the unexpected brightness of companion B.Comment: 5 pages, 9 figures, accepted Astronomy and Astrophysics Letters. 201
Combining molecular dynamics and docking simulations to develop targeted protocols for performing optimized virtual screening campaigns on the HTRPM8 channel
Background: There is an increasing interest in TRPM8 ligands of medicinal interest, the rational design of which can be nowadays supported by structure-based in silico studies based on the recently resolved TRPM8 structures. Methods: The study involves the generation of a reliable hTRPM8 homology model, the reliability of which was assessed by a 1.0 \u3bcs MD simulation which was also used to generate multiple receptor conformations for the following structure-based virtual screening (VS) campaigns; docking simulations utilized different programs and involved all monomers of the selected frames; the so computed docking scores were combined by consensus approaches based on the EFO algorithm. Results: The obtained models revealed very satisfactory performances; LiGen\u2122 provided the best results among the tested docking programs; the combination of docking results from the four monomers elicited a markedly beneficial effect on the computed consensus models. Conclusions: The generated hTRPM8 model appears to be amenable for successful structure-based VS studies; cross-talk modulating effects between interacting monomers on the binding sites can be accounted for by combining docking simulations as performed on all the monomers; this strategy can have general applicability for docking simulations involving quaternary protein structures with multiple identical binding pockets
Efeito de infestação de Tibraca limbativentris (Heteroptera: pentatomidae) na produção de arroz irrigado.
Experimentos de campo foram conduzidos durante os cultivos de 2006 e 2007 para determinar o impacto de infestação de T. limbativentris (percevejo-do-colmo) na produção de grãos de arroz irrigado.Resumo ID: 111-1
Torrefaction of residues and by-products from sunflower chain
The high heterogeneity of some residual biomasses makes rather difficult their energy use and standardisation is a key aspect for these fuel products. Torrefaction is an interesting process used to improve the quality of ligno-cellulosic biomasses and to achieve standardisation. In the present study torrefaction has been employed on residues and by-products deriving from sunflower production chain, in particular sunflower stalks and oil press cake. The thermal behaviour of materials has been studied at first by thermo-gravimetric analysis in order to identify torrefaction temperatures range. Different residence time and torrefaction temperatures have been employed in a bench top torrefaction reactor afterwards. Analyses of raw and torrefied materials have been carried out to assess the influence of the process. As a consequence of torrefaction, the carbon and ash contents increase while the volatilisation range is reduced making the material more stable and standardised. Mass yield, energy yield and energy densification reach values of about 60 %, 80 % and 1.33 for sunflower stalks and 64 %, 85 % and 1.33 for sunflower oil press cake respectively. As highlighted by results, torrefaction is more interesting for sunflower stalks than oil cake and husks because of the different starting characteristics. Untreated oil cake and husks already show a good high heating value and the eventual torrefaction should be mild. On the contrary for sunflower stalks the process is more useful and could be more severe
Resposta do arroz irrigado à infestação de Tibraca limbativentris (Heteroptera: pentatomidae).
O objetivo deste trabalho foi determinar o relacionamento entre a população de T. limbativentris e a redução na produção de arroz irrigado. A quantificação desta relação é essencial para a determinação do nível de dano econômico para esta praga
Hot exozodiacal dust resolved around Vega with IOTA/IONIC
Although debris discs have been detected around a significant number of
main-sequence stars, only a few of them are known to harbour hot dust in their
inner part where terrestrial planets may have formed. Thanks to infrared
interferometric observations, it is possible to obtain a direct measurement of
these regions, which are of prime importance for preparing future exo-Earth
characterisation missions. In this context, we have resolved the exozodiacal
dust disc around Vega with the help of infrared stellar interferometry and
estimated the integrated H-band flux originating from the first few AUs of the
debris disc. Using precise H-band interferometric measurements obtained with
the 3-telescope IOTA/IONIC interferometer (Mount Hopkins, Arizona), thorough
modelling of both interferometric data (squared visibility and closure phase)
and spectral energy distribution was performed to constrain the nature of the
near-infrared excess emission. The most straightforward scenario consists in a
compact dust disc producing a thermal emission that is largely dominated by
small grains located between 0.1 and 0.3 AU from Vega and accounting for 1.23
+/- 0.45% of the near-infrared stellar flux for our best-fit model. This flux
ratio is shown to vary slightly with the geometry of the model used to fit our
interferometric data (variations within +/-0.19%). Initially revealed by K-band
CHARA/FLUOR observations, the presence of hot exozodiacal dust in the vicinity
of Vega is confirmed by our H-band IOTA/IONIC measurements at the 3-sigma
level. Whereas the origin of the dust is still uncertain, its presence and the
possible connection with the outer disc suggest that the Vega system is
currently undergoing major dynamical perturbations.Comment: 10 pages, 9 figures, accepted for publication in A&
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