389 research outputs found
"TNOs are Cool": A survey of the trans-Neptunian region VI. Herschel/PACS observations and thermal modeling of 19 classical Kuiper belt objects
Trans-Neptunian objects (TNO) represent the leftovers of the formation of the
Solar System. Their physical properties provide constraints to the models of
formation and evolution of the various dynamical classes of objects in the
outer Solar System. Based on a sample of 19 classical TNOs we determine
radiometric sizes, geometric albedos and beaming parameters. Our sample is
composed of both dynamically hot and cold classicals. We study the correlations
of diameter and albedo of these two subsamples with each other and with orbital
parameters, spectral slopes and colors. We have done three-band photometric
observations with Herschel/PACS and we use a consistent method for data
reduction and aperture photometry of this sample to obtain monochromatic flux
densities at 70.0, 100.0 and 160.0 \mu m. Additionally, we use Spitzer/MIPS
flux densities at 23.68 and 71.42 \mu m when available, and we present new
Spitzer flux densities of eight targets. We derive diameters and albedos with
the near-Earth asteroid thermal model (NEATM). As auxiliary data we use
reexamined absolute visual magnitudes from the literature and data bases, part
of which have been obtained by ground based programs in support of our Herschel
key program. We have determined for the first time radiometric sizes and
albedos of eight classical TNOs, and refined previous size and albedo estimates
or limits of 11 other classicals. The new size estimates of 2002 MS4 and 120347
Salacia indicate that they are among the 10 largest TNOs known. Our new results
confirm the recent findings that there are very diverse albedos among the
classical TNOs and that cold classicals possess a high average albedo (0.17 +/-
0.04). Diameters of classical TNOs strongly correlate with orbital inclination
in our sample. We also determine the bulk densities of six binary TNOs.Comment: 21 pages, 9 figures, accepted for publication in Astronomy and
Astrophysic
Biochars from animal wastes as alternative materials to treat colored effluents containing Basic Red 9
Bovine bones (BB) and fish scales (FS) were used as alternative precursors to produce biochars, which in turn, were applied for the removal of Basic Red 9 (BR9) from aqueous solutions. BB and FS were pyrolyzed generating a solid (biochars), a liquid (pyrolytic oils) and a gas fraction. All fractions were characterized to evaluate the pyrolysis process. The biochars presented different functional groups and a mesoporous structure with surface areas around 90 m2 g–1. Both biochars demonstrated potential to adsorb BR9, with maximum adsorption capacities of 49.5 (BB–biochar) and 52.3 mg g–1 (FS–biochar). Pyrolytic oils were composed mainly by palmitic acid (BB) and imidazolidinedione (FS), which are compounds with biological and antioxidant activity. Pyrolysis of BB generated CO2 while pyrolysis of FS generated H2. In summary, bovine bones and fish scales are promising precursors to concomitantly produce biochars with great adsorbent potential and oils with interesting characteristics
Origin and Dynamical Evolution of Neptune Trojans - I: Formation and Planetary Migration
We present the results of detailed dynamical simulations of the effect of the
migration of the four giant planets on both the transport of pre-formed Neptune
Trojans, and the capture of new Trojans from a trans-Neptunian disk. We find
that scenarios involving the slow migration of Neptune over a large distance
(50Myr to migrate from 18.1AU to its current location) provide the best match
to the properties of the known Trojans. Scenarios with faster migration (5Myr),
and those in which Neptune migrates from 23.1AU to its current location, fail
to adequately reproduce the current day Trojan population. Scenarios which
avoid disruptive perturbation events between Uranus and Neptune fail to yield
any significant excitation of pre-formed Trojans (transported with efficiencies
between 30 and 98% whilst maintaining the dynamically cold nature of these
objects). Conversely, scenarios with periods of strong Uranus-Neptune
perturbation lead to the almost complete loss of such pre-formed objects. In
these cases, a small fraction (~0.15%) of these escaped objects are later
recaptured as Trojans prior to the end of migration, with a wide range of
eccentricities (<0.35) and inclinations (<40 deg). In all scenarios (including
those with such disruptive interaction between Uranus and Neptune) the capture
of objects from the trans-Neptunian disk (through which Neptune migrates) is
achieved with efficiencies between ~0.1 and ~1%. The captured Trojans display a
wide range of inclinations (<40 deg for slow migration, and <20 deg for rapid
migration) and eccentricities (<0.35), and we conclude that, given the vast
amount of material which undoubtedly formed beyond the orbit of Neptune, such
captured objects may be sufficient to explain the entire Neptune Trojan
population. (Shortened version)Comment: 25 pages, 6 figure
Pierce the ear and stab the spleen
Splenic abscess is a rare but extremely dangerous condition generally spreading from a local, or systemic, focus of infection. We present the case of a young immunocompetent female admitted with sepsis and multiple splenic abscesses. The patient had a recent left ear piercing on the tragus complicated by an ear infection. The presence of a solitary parotid abscess, the absence of other infectious foci on computed tomography scan, the negativity of blood cultures and the absence of endocarditis vegetations led us to think that the most likely culprit was a hematogenous dissemination from the left tragus. The patient was successfully treated with intravenous antibiotics. There had been no need of splenectomy or any other procedure. This rather unique case underscores that splenic abscess should be suspected when a long-lasting fever and pain in the left hypochondrium are present, even when an apparently innocuous invasive procedure, such as a body piercing, is performed
Thermal infrared observations of the Hayabusa spacecraft target asteroid 25143 Itokawa
We obtained N- and Q-band observations of the Apollo-type asteroid 25143
Itokawa during its close Earth approach in July 2004 with TIMMI2 at the ESO 3.6
m telescope. Our photometric measurement, in combination with already published
data, allowed us to derive a radiometric effective diameter of 0.32+/-0.03 km
and an albedo of 0.19 +0.11/-0.03 through a thermophysical model. This
effective diameter corresponds to a slightly asymmetrical and flattened
ellipsoid of the approximate size of 520(+/-50) x 270(+/-30) x 230(+/-20) m,
based on the Kaasalainen et al. (2005) shape model. Our studies show that the
thermal observations lead to size estimates which are about 15% smaller than
the radar results (Ostro et al. 2005), slightly outside the stated radar
uncertainties of +/-10%. We determined a rather high thermal inertia of 750
Jm-2s-0.5K-1. This is an indication for a bare rock dominated surface, a thick
dust regolith can be excluded as well as a metallic surface. From our data we
constructed a 10.0 micrometer thermal lightcurve which is nicely matched in
amplitude and phase by the shape and spin vector solution in combination with
our TPM description. The assumed S-type bulk density in combination with
radiometric size lead to a total mass estimate of 4.5 +2.0/-1.8 x 10^10 kg.Comment: 9 pages, 7 figures, accepted for publication by A&A 29/Aug/200
Resultados de unidades de observação de linhagens de soja da Embrapa Trigo, safra 2007/08.
bitstream/item/128676/1/ID2832-LVdocumentos86-p64-69.pd
Substituição do milho moÃdo pela glicerina como aditivo em silagem de capim elefante
Objetivou-se com este estudo testar o aumento linear da inclusão de glicerina bruta (86% de pureza) em substituição ao milho moÃdo, como aditivo, na forragem de capim-elefante destinada a ensilagem, avaliando-se a qualidade nutricional do alimento e a viabilidade da ensilagem do material. Foram testados cinco nÃveis de substituição do milho pela glicerina em taxas que variaram de 3,12 a 12,5% sobre a matéria natural da forragem, além de um tratamento controle (apenas forragem). Realizaram-se análises bromatológicas e de digestibilidade para avaliar o valor nutricional da mistura durante a ensilagem e após o processo fermentativo, na silagem. Para avaliar a qualidade fermentativa foram feitas avaliações de pH, nitrogênio amoniacal, recuperação de matéria seca e densidade. A inclusão do milho moÃdo incrementou (P<0,05) o teor de matéria seca em até 28%, tanto na forragem fresca, bem como na silagem. Tanto a inclusão do milho, bem como a substituição deste pela glicerina resultou (P<0,05) em um incremento médio de 25% e 32 % na digestibilidade in situ e valor energético da silagem, respectivamente quando comparado ao capim puro. Isto, devido ao decréscimo (P<0,05) dos teores de fibra em detergente neutro e fibra em detergente ácido na silagem. A inclusão de glicerina aumentou (P<0,05) as perdas de proteÃna bruta durante a fermentação e diminuiu a recuperação da matéria seca. O teor de matéria seca da forragem parece ser fator chave para o sucesso de inclusão da glicerina como aditivo na ensilagem do capim-elefante, no intuito de evitar perdas expressivas de qualidade nutricional durante a fermentação
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