130 research outputs found
Moderate Resolution Spectroscopy For The Space Infrared Telescope Facility (SIRTF)
A conceptual design for an infrared spectrometer capable of both low resolution (λ/Î-λ = 50; 2.5-200 microns) and moderate resolution (1000; 4-200 microns) and moderate resolution (1000; 4-200 microns) has been developed. This facility instrument will permit the spectroscopic study in the infrared of objects ranging from within the solar system to distant galaxies. The spectroscopic capability provided by this instrument for SIRTF will give astronomers orders of magnitude greater sensitivity for the study of faint objects than had been previously available. The low resolution mode will enable detailed studies of the continuum radiation. The moderate resolution mode of the instrument will permit studies of a wide range of problems, from the infrared spectral signatures of small outer solar system bodies such as Pluto and the satellites of the giant planets, to investigations of more luminous active galaxies and QS0s at substantially greater distances. A simple design concept has been developed for the spectrometer which supports the science investigation with practical cryogenic engineering. Operational flexibility is preserved with a minimum number of mechanisms. The five modules share a common aperture, and all gratings share a single scan mechanism. High reliability is achieved through use of flight-proven hardware concepts and redundancy. The design controls the heat load into the SIRTF cryogen, with all heat sources other than the detectors operating at 7K and isolated from the 4K cold station. Two-dimensional area detector arrays are used in the 2.5-120ÎŒm bands to simultaneously monitor adjacent regions in extended objects and to measure the background near point sources
Moderate Resolution Spectroscopy For The Space Infrared Telescope Facility (SIRTF)
A conceptual design for an infrared spectrometer capable of both low resolution (λ/Î-λ = 50; 2.5-200 microns) and moderate resolution (1000; 4-200 microns) and moderate resolution (1000; 4-200 microns) has been developed. This facility instrument will permit the spectroscopic study in the infrared of objects ranging from within the solar system to distant galaxies. The spectroscopic capability provided by this instrument for SIRTF will give astronomers orders of magnitude greater sensitivity for the study of faint objects than had been previously available. The low resolution mode will enable detailed studies of the continuum radiation. The moderate resolution mode of the instrument will permit studies of a wide range of problems, from the infrared spectral signatures of small outer solar system bodies such as Pluto and the satellites of the giant planets, to investigations of more luminous active galaxies and QS0s at substantially greater distances. A simple design concept has been developed for the spectrometer which supports the science investigation with practical cryogenic engineering. Operational flexibility is preserved with a minimum number of mechanisms. The five modules share a common aperture, and all gratings share a single scan mechanism. High reliability is achieved through use of flight-proven hardware concepts and redundancy. The design controls the heat load into the SIRTF cryogen, with all heat sources other than the detectors operating at 7K and isolated from the 4K cold station. Two-dimensional area detector arrays are used in the 2.5-120ÎŒm bands to simultaneously monitor adjacent regions in extended objects and to measure the background near point sources
The Infrared Spectrograph on the Spitzer Space Telescope
The Infrared Spectrograph (IRS) is one of three science instruments on the
Spitzer Space Telescope. The IRS comprises four separate spectrograph modules
covering the wavelength range from 5.3 to 38micron with spectral resolutions, R
\~90 and 600, and it was optimized to take full advantage of the very low
background in the space environment. The IRS is performing at or better than
the pre-launch predictions. An autonomous target acquisition capability enables
the IRS to locate the mid-infrared centroid of a source, providing the
information so that the spacecraft can accurately offset that centroid to a
selected slit. This feature is particularly useful when taking spectra of
sources with poorly known coordinates. An automated data reduction pipeline has
been developed at the Spitzer Science Center.Comment: Accepted in ApJ Sup. Spitzer Special Issue, 6 pages, 4 figure
Moderate Resolution Spectroscopy For The Space Infrared Telescope Facility (SIRTF)
A conceptual design for an infrared spectrometer capable of both low resolution (λ/Î-λ = 50; 2.5-200 microns) and moderate resolution (1000; 4-200 microns) and moderate resolution (1000; 4-200 microns) has been developed. This facility instrument will permit the spectroscopic study in the infrared of objects ranging from within the solar system to distant galaxies. The spectroscopic capability provided by this instrument for SIRTF will give astronomers orders of magnitude greater sensitivity for the study of faint objects than had been previously available. The low resolution mode will enable detailed studies of the continuum radiation. The moderate resolution mode of the instrument will permit studies of a wide range of problems, from the infrared spectral signatures of small outer solar system bodies such as Pluto and the satellites of the giant planets, to investigations of more luminous active galaxies and QS0s at substantially greater distances. A simple design concept has been developed for the spectrometer which supports the science investigation with practical cryogenic engineering. Operational flexibility is preserved with a minimum number of mechanisms. The five modules share a common aperture, and all gratings share a single scan mechanism. High reliability is achieved through use of flight-proven hardware concepts and redundancy. The design controls the heat load into the SIRTF cryogen, with all heat sources other than the detectors operating at 7K and isolated from the 4K cold station. Two-dimensional area detector arrays are used in the 2.5-120ÎŒm bands to simultaneously monitor adjacent regions in extended objects and to measure the background near point sources
Multidisciplinary investigations of the diets of two post-medieval populations from London using stable isotopes and microdebris analysis
This paper presents the first multi-tissue study of diet in post-medieval London using both the stable light isotope analysis of carbon and nitrogen and analysis of microdebris in dental calculus. Dietary intake was explored over short and long timescales. Bulk bone collagen was analysed from humans from the Queenâs Chapel of the Savoy (QCS) (n = 66) and the St Barnabas/St Mary Abbots (SB) (n = 25). Incremental dentine analysis was performed on the second molar of individual QCS1123 to explore childhood dietary intake. Bulk hair samples (n = 4) were sampled from adults from QCS, and dental calculus was analysed from four other individuals using microscopy. In addition, bone collagen from a total of 46 animals from QCS (n = 11) and the additional site of Prescot Street (n = 35) was analysed, providing the first animal dietary baseline for post-medieval London. Overall, isotopic results suggest a largely C3-based terrestrial diet for both populations, with the exception of QCS1123 who exhibited values consistent with the consumption of C4 food sources throughout childhood and adulthood. The differences exhibited in ÎŽ15Ncoll across both populations likely reflect variations in diet due to social class and occupation, with individuals from SB likely representing wealthier individuals consuming larger quantities of animal and marine fish protein. Microdebris analysis results were limited but indicate the consumption of domestic cereals. This paper demonstrates the utility of a multidisciplinary approach to investigate diet across long and short timescales to further our understanding of variations in social status and mobility
Beyond faith: Biomolecular evidence for changing urban economies in multiâfaith medieval Portugal
During the Middle Ages, Portugal witnessed unprecedented socioeconomic and religious changes under transitioning religious political rule. The implications of changing ruling powers for urban food systems and individual diets in medieval Portugal is poorly understood. This study aimed to elucidate the dietary impact of the Islamic and Christian conquests.info:eu-repo/semantics/publishedVersio
The Small Satellites of Pluto as Observed by New Horizons
The New Horizons mission has provided resolved measurements of Pluto's moons
Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical
diameters of 40 km for Nix and Hydra and ~10 km for Styx and Kerberos.
They are also highly elongated, with maximum to minimum axis ratios of
2. All four moons have high albedos ( 50-90 %) suggestive of
a water-ice surface composition. Crater densities on Nix and Hydra imply
surface ages 4 Ga. The small moons rotate much faster than
synchronous, with rotational poles clustered nearly orthogonal to the common
pole directions of Pluto and Charon. These results reinforce the hypothesis
that the small moons formed in the aftermath of a collision that produced the
Pluto-Charon binary.Comment: in Science 351, aae0030 (2016
Mysid crustaceans as standard models for the screening and testing of endocrine-disrupting chemicals
Author Posting. © Springer, 2007. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Ecotoxicology 16 (2007): 205-219, doi:10.1007/s10646-006-0122-0.Investigative efforts into the potential endocrine-disrupting effects of chemicals have mainly
concentrated on vertebrates, with significantly less attention paid to understanding potential
endocrine disruption in the invertebrates. Given that invertebrates account for at least 95% of all
known animal species and are critical to ecosystem structure and function, it remains essential to
close this gap in knowledge and research. The lack of progress regarding endocrine disruption in
invertebrates is still largely due to: (1) our ignorance of mode-of-action, physiological control, and
hormone structure and function in invertebrates; (2) lack of a standardized invertebrate assay; (3)
the irrelevance to most invertebrates of the proposed activity-based biological indicators for
endocrine disruptor exposure (androgen, estrogen and thyroid); (4) limited field studies. Past and
ongoing research efforts using the standard invertebrate toxicity test model, the mysid shrimp, have
aimed at addressing some of these issues. The present review serves as an update to a previous
publication on the use of mysid shrimp for the evaluation of endocrine disruptors (Verslycke et al.,
2004a). It summarizes recent investigative efforts that have significantly advanced our
understanding of invertebrate-specific endocrine toxicity, population modeling, field studies, and
transgeneration standard test development using the mysid model.Supported by a Fellowship of the Belgian American Educational Foundation
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