339 research outputs found
Federal Courts - Doctrine of Abstention
The United States District Court for the Eastern District of Pennsylvania has held that the court need not abstain from approving a consent agreement between the Commonwealth and the Pennsylvania Association for Retarded Children, although the statutes challenged under the equal protection clause and under state law were unclear.
The Pennsylvania Association for Retarded Children v. Pennsylvania, 343 F. Supp. 279 (E.D. Pa. 1972)
Thiol-disulfide exchange is involved in the catalytic mechanism of peptide methionine sulfoxide reductase
Characterisation of the new target of the NASA Lucy mission: asteroid 152830 Dinkinesh (1999 VD57)
The NASA Lucy mission is aimed at the study of the very interesting
population of Jupiter Trojans, considered as time capsules from the origin of
our solar system. During its journey, the mission will pass near a main belt
asteroid, Donaldjohanson. Recently, NASA has announced that a new asteroid in
the belt will also be visited by Lucy: 152830 Dinkinesh (1999 VD57). The main
goal of this work is to characterise this newly selected target, asteroid
Dinkinesh, in order to provide critical information to the mission team. To
achieve it, we have obtained visible spectra, colour photometry, and
time-series photometry of Dinkinesh, using several telescopes located at
different observatories. For the spectra we used the 10.4m Gran Telescopio
Canarias (GTC), in the island of La Palma (Spain); for the colour photometry
the 4.3m Lowell Discovery Telescope (LDT), near Happy Jack, Arizona (USA) was
used; and for the time-series photometry we used the 82cm IAC80 telescope
located in the island of Tenerife (Spain). Both visible spectrum and
reflectance values computed from colour photometry show that Dinkinesh is an
S-type asteroid, i.e., it is composed mainly of silicates and some metal.
According to observations done by the NEOWISE survey, S-type asteroids have
typical geometric albedo of = 0.223 0.073. From our time-series
photometry, we obtained an asteroid mean magnitude = 19.99 0.05,
which provides an absolute magnitude = 17.53 0.07 assuming =
0.19 0.25 for S-types. Using our colour-photometry, we transformed
to = 17.48 0.05. This value of absolute magnitude combined
with the geometric albedo provides a mean diameter for Dinkinesh of 900
m, ranging between a minimum size of 542 m and a maximum size of 1309 m.Comment: 4 pages, 3 figures, Accepted for publication in A&
The Near-Earth Encounter of Asteroid 308635 (2005 YU55): Thermal IR Observations
The near-Earth approach (0.00217 AU, or 0.845 lunar distances) of the C-type asteroid 308635 (2005 YU55) in November 2011 presented a rare opportunity for detailed observations of a low-albedo NEA in this size range. As part of a multi-telescope campaign to measure visible and infrared spectra and photometry, we obtained mid-infrared (approx. 8 to 22 micron) photometry and spectroscopy of 2005 YU55 using Michelle on the Gemini North telescope on UT November 9 and 10,2011. An extensive radar campaign together with optical light-curves established the rotation state of YU55. In addition, the radar imaging resulted in a shape model for the asteroid, detection of numerous boulders on its surface, and a preliminary estimate of its equatorial diameter at 380 +/- 20 m. In a preliminary analysis, applying the radar and lightcurve-derived parameters to a rough-surface thermophysical model fit to the Gemini/Michelle thermal emission photometry results in a thermal inertia range of approximately 500 to 1500 J/sq m/0.5s/K, with the low-thermal-inertia solution corresponding to the small end of the radar size range and vice versa. Updates to these results will be presented and modeling of the thermal contribution to the measured near-infrared spectra from Palomar/Triplespec and IRTF/SpeX will also be discussed
Recommended from our members
Impact histories of Vesta and Vestoids inferred from howardites, eucrites and diogenites
The parent body of the howardites, eucrites and diogenites (HEDs) is thought to be asteroid (4) Vesta [1]. However, several eucrites have now been recognized, like NWA 011 and Ibitira, with major element compositions and mineralogy like normal eucrites but with different oxygen isotope compositions and minor element concentrations suggesting they are not from the same body [2, 3]. The discoveries of abnormal eucrites and V-type asteroids that are probably not from Vesta [see 4] raise the question whether the HEDs with normal oxygen isotopes are coming from Vesta [3]. To address this issue and understand more about the evolution of Vesta in preparation for the arrival of the Dawn spacecraft, we integrate fresh insights from Ar-Ar dating and oxygen isotope analyses of HEDs, radiometric dating of differentiated meteorites, as well as dynamical and astronomical studies of Vesta, the Vesta asteroid family (i.e., the Vestoids), and other V-type asteroids
Conditional Allocation of Control Rights in Venture Capital Finance
When a young entrepreneurial firm matures, it is often necessary to replace the founding entrepreneur by a professional manager. This replacement decision can be affected by the private benefits of control enjoyed by the entrepreneur which gives rise to a conflict of interest between the entrepreneur and the venture capitalist. We show that a combination of convertible securities and contingent control rights can be used to resolve this conflict efficiently. This contractual arrangement is frequently observed in venture capital finance
A 2km-size asteroid challenging the rubble-pile spin barrier – A case for cohesion
The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than ~200-300. m. Among thousands of asteroids with diameters larger than ~300. m, only a handful of asteroids are known to rotate faster than 2.0. h, all are in the sub-km range (≤0.6. km). Here we present photometric measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt asteroid with a relatively large diameter of 2.3-0.7+0.6km, completes one rotation in 1.9529. ±. 0.0002. h. Its unique diameter and rotation period allow us to examine scenarios about asteroid internal structure and evolution: a rubble pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic structure; an asteroid experiencing mass shedding; an asteroid experiencing YORP spin-up/down; and an asteroid with a unique octahedron shape results with a four-peak lightcurve and a 3.9. h period. We find that the most likely scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from disrupting without requiring a monolithic structure or a unique shape. Due to the uniqueness of (60716) 2000 GD65, we suggest that most asteroids typically have smaller cohesion than that of lunar regolith. Keywords: Asteroids; Asteroids, rotation; Rotational dynamics; PhotometryUnited States. National Aeronautics and Space Administration (Grant NNX12AL26G
- …