628 research outputs found
Constraining multiple systems with GAIA
GAIA will provide observations of some multiple asteroid and dwarf systems.
These observations are a way to determine and improve the quantification of
dynamical parameters, such as the masses and the gravity fields, in these
multiple systems. Here we investigate this problem in the cases of Pluto's and
Eugenia's system. We simulate observations reproducing an approximate planning
of the GAIA observations for both systems, as well as the New Horizons
observations of Pluto. We have developed a numerical model reproducing the
specific behavior of multiple asteroid system around the Sun and fit it to the
simulated observations using least-square method, giving the uncertainties on
the fitted parameters. We found that GAIA will improve significantly the
precision of Pluto's and Charon's mass, as well as Petit Prince's orbital
elements and Eugenia's polar oblateness.Comment: 5 pages, accepted by Planetary and Space Science, Gaia GREAT-SSO-Pis
MapX: an In-Situ Mapping X-Ray Fluorescence Instrument for Detection of Biosignatures and Habitable Planetary Environments
The search for evidence of life or its processes on other worlds takes on two major themes: the detection of biosignatures indicating extinct or extant life, or the determination that an environment either has or once had the potential to harbor living organisms. In situ elemental imaging is useful in either case, since features on the mm to m scale reveal geological processes which may indicate past or present habitability. Further, biomineralization can leave traces in the morphology and element distribution of surfaces. The Mapping X-ray Fluorescence Spectrometer (MapX) is an in-situ instrument designed to identify these features on planetary surfaces [1]. Progress on instrument development, data analysis methods, and element quantification are presented
Gemini Planet Imager Observational Calibrations III: Empirical Measurement Methods and Applications of High-Resolution Microlens PSFs
The newly commissioned Gemini Planet Imager (GPI) combines extreme adaptive
optics, an advanced coronagraph, precision wavefront control and a
lenslet-based integral field spectrograph (IFS) to measure the spectra of young
extrasolar giant planets between 0.9-2.5 um. Each GPI detector image, when in
spectral model, consists of ~37,000 microspectra which are under or critically
sampled in the spatial direction. This paper demonstrates how to obtain
high-resolution microlens PSFs and discusses their use in enhancing the
wavelength calibration, flexure compensation and spectral extraction. This
method is generally applicable to any lenslet-based integral field spectrograph
including proposed future instrument concepts for space missions.Comment: 10 pages, 6 figures. Proceedings of the SPIE, 9147-282 v2: reference
adde
The hierarchical stability of the seven known large size ratio triple asteroids using the empirical stability parameters
In this study, the hierarchical stability of the seven known large size ratio triple asteroids is investigated. The effect of the solar gravity and primary’s J(2) are considered. The force function is expanded in terms of mass ratios based on the Hill’s approximation and the large size ratio property. The empirical stability parameters are used to examine the hierarchical stability of the triple asteroids. It is found that the all the known large size ratio triple asteroid systems are hierarchically stable. This study provides useful information for future evolutions of the triple asteroids
Review: Insects and former foodstuffs for upgrading food waste biomasses/streams to feed ingredients for farm animals
The increasing global need to find alternative protein/energy sources has triggered research in the field of non-conventional feed ingredients, with insects and former foodstuffs being the most promising. Insects contain high level of protein and fat, whereas former foodstuffs contain high energy in the form of carbohydrates and fats; therefore, both should be considered as promising alternative feed ingredients for livestock production. In addition to the nutritional value, they also represent a way by which food waste biomasses/streams can be upgraded to valuable feed ingredients. This review outlines the main nutritional and safety issues of insects and former foodstuffs, and also considers the legal framework involved. The importance of the type of insect metamorphosis and tailored substrates that could lead to the production of a premium feed is also described. This is also the first time that a review discusses the nutritional quality of former foodstuffs. Energy and the main nutrient content of former foodstuff are compared with the composition of common cereals as the principal energy sources in animal feed. For both ingredients a critical review of the safety issues is provided. Based on the current data available, both insects and former foodstuffs have an excellent potential use as alternative feed ingredients for livestock production. When produced in line with the criteria set by major feed/food authorities, they are characterized by high quality and safety standards. This makes them comparable to other feed materials and ingredients currently available on the market, although their full nutritional, functional, safety and sustainability evaluation cannot be considered complete
Ischemic cardiovascular disease in workers occupationally exposed to urban air pollution – A systematic review
Introduction. Cardiovascular disease is the first cause of morbidity and mortality worldwide. Among several known risk factors, researchers also focus their attention on the chronic exposure to air pollution. There is much evidence that exposure to air pollution, especially to ultrafine particles, can damage the endothelium and can favour cardiovascular diseases in the general population. Occupational exposition could be an additive risk factor for the cardiovascular system. This article presents a scientific review of the linkage between occupational exposure to air pollution and ischemic heart disease. Materials and method. A scientific review was undertaken, followed by PRISMA Statements. Observational studies were selected from several scientific databases, likesuch as Pubmed, Google Scholar, Nioshtic-2 and Reserchgate, searching
for selected key words: police workers, professional drivers, mail carriers, filling station attendants, road cleaners, garage workers, motor vehicles and engine maintenance. All the key words were combined with “Boolean Operators” with the
following words: cardiovascular (or cardiac) disease, cardiovascular function, cardiovascular system, ischemic heart disease, coronary disease, myocardial infarction. During the systematic research, the focus was on retrospective and prospective studies from January 1990 – December 2014.
Results. Both the retrospective and prospective studies showed an increased risk of ischemic heart disease in occupationally occupied people exposed to air pollution. Only one study presented a ly minor risk.
Conclusions. The findings of this systematic review suggest a possible linkage between occupational exposure to urban air pollution, especially to motor exhaust and particulate, and ischemic heart disease
Main Belt Binary Asteroidal Systems With Eccentric Mutual Orbits
Using 8m-10m class telescopes and their Adaptive Optics (AO) systems, we
conducted a long-term adaptive optics campaign initiated in 2003 focusing on
four binary asteroid systems: (130) Elektra, (283) Emma, (379) Huenna, and
(3749) Balam. The analysis of these data confirms the presence of their
asteroidal satellite. We did not detect any additional satellite around these
systems even though we have the capability of detecting a loosely-bound
fragment (located at 1/4 x RHill) ~40 times smaller in diameter than the
primary. The orbits derived for their satellites display significant
eccentricity, ranging from 0.1 to 0.9, suggesting a different origin. Based on
AO size estimate, we show that (130) Elektra and (283) Emma, G-type and P-type
asteroids respectively, have a significant porosity (30-60% considering CI-CO
meteorites as analogs) and their satellite's eccentricities (e~0.1) are
possibly due to excitation by tidal effects. (379) Huenna and (3749) Balam, two
loosely bound binary systems, are most likely formed by mutual capture. (3749)
Balam's possible high bulk density is similar to (433) Eros, another S-type
asteroid, and should be poorly fractured as well. (379) Huenna seems to display
both characteristics: the moonlet orbits far away from the primary in term of
stability (20% x RHill), but the primary's porosity is significant (30-60%).Comment: 60 pages, 7 tables, 4 figures, in press to Icaru
A low density of 0.8 g/cc for the Trojan binary asteroid 617 Patroclus
The Trojan population consists of two swarms of asteroids following the same
orbit as Jupiter and located at the L4 and L5 Lagrange points of the
Jupiter-Sun system (leading and following Jupiter by 60 degrees). The asteroid
617 Patroclus is the only known binary Trojan (Merline et al. 2001). The orbit
of this double system was hitherto unknown. Here we report that the components,
separated by 680 km, move around the system centre of mass, describing roughly
a circular orbit. Using the orbital parameters, combined with thermal
measurements to estimate the size of the components, we derive a very low
density of 0.8 g/cc. The components of Patroclus are therefore very porous or
composed mostly of water ice, suggesting that they could have been formed in
the outer part of the solar system.Comment: 10 pages, 3 figures, 1 tabl
- …