2,381 research outputs found
Discovery of a planetary-sized object in the scattered Kuiper belt
We present the discovery and initial physical and dynamical characterization
of the object 2003 UB313. The object is sufficiently bright that for all
reasonable values of the albedo it is certain to be larger than Pluto.
Pre-discovery observations back to 1989 are used to obtain an orbit with
extremely small errors. The object is currently at aphelion in what appears to
be a typical orbit for a scattered Kuiper belt object except that it is
inclined by about 44 degrees from the ecliptic. The presence of such a large
object at this extreme inclination suggests that high inclination Kuiper belt
objects formed preferentially closer to the sun. Observations from Gemini
Observatory show that the infrared spectrum is, like that of Pluto, dominated
by the presence of frozen methane, though visible photometry shows that the
object is almost neutral in color compared to Pluto's extremely red color. 2003
UB313 is likely to undergo substantial seasonal change over the large range of
heliocentric distances that it travels; Pluto at its current distance is likely
to prove a useful analog for better understanding the range of seasonal changes
on this body.Comment: 9 pages, 1 figur
Dependence of Maximum Trappable Field on Superconducting Nb3Sn Cylinder Wall Thickness
Uniform dipole magnetic fields from 1.9 to 22.4 kOe were permanently trapped,
with high fidelity to the original field, transversely to the axes of hollow
Nb3Sn superconducting cylinders. These cylinders were constructed by helically
wrapping multiple layers of superconducting ribbon around a mandrel. This is
the highest field yet trapped, the first time trapping has been reported in
such helically wound taped cylinders, and the first time the maximum trappable
field has been experimentally determined as a function of cylinder wall
thickness.Comment: 8 pages, 4 figures, 1 table. PACS numbers: 74.60.Ge, 74.70.Ps,
41.10.Fs, 85.25.+
Photometric Light Curve for the Kuiper Belt Object 2000 EB173 on 78 Nights
Kuiper Belt Objects (KBOs) are generally very faint and cannot in practice be monitored with a well-sampled long-term light curve; so our discovery of the bright KBO 2000 EB173 offers an excellent opportunity for synoptic studies. We present a well-sampled photometric time series (77 R magnitudes and 29 V magnitudes on 78 nights) over a 225-day time span centered on the 2001 opposition. The light curve (corrected to the year 2001 opposition distance) varies from 19.11 to 19.39 mag with a single peak that is smooth, time symmetric, and coincident with opposition. All variations in the light curve are consistent with a linear opposition surge (Ropp = 19.083 + 0.125Xalpha, where alpha is the solar phase angle), while any rotational modulation must have a peak-to-peak amplitude of less than 0.097 mag. This is the first measured opposition surge for any KBO (other than Pluto). The V-R color is 0.63+-0.02, with no apparent variation with phase at the few percent level. With R=19.11 at opposition, 2000 EB173 remains the brightest known KBO and a prime target for future photometric and spectroscopic studies
Discovery of near-Earth asteroids by CCD scanning
The found near-Earth asteroid are different objects with peculiar orbits. With the new technique of CCD scanning we entered the domain of the smallest, the fastest, and the closest near-Earth asteroids. The results are presented
Direct measurement of the size of 2003 UB313 from the Hubble Space Telescope
We have used the Hubble Space Telescope to directly measure the angular size
of the large Kuiper belt object 2003 UB313. By carefully calibrating the point
spread function of a nearby field star, we measure the size of 2003 UB313 to be
34.31.4 milliarcseconds, corresponding to a diameter of 2400100 km or
a size % larger than Pluto. The V band geometric albedo of 2003 UB313 is
%. The extremely high albedo is consistent with the frosty methane
spectrum, the lack of red coloring, and the lack of observed photometric
variation on the surface of 2003 UB313. Methane photolysis should quickly
darken the surface of 2003 UB313, but continuous evaporation and redeposition
of surface ices appears capable of maintaining the extreme alebdo of this body
Basic Connection between Superconductivity and Superfluidity
A basic and inherently simple connection is shown to exist between
superconductivity and superfluidity. It is shown here that the author's
previously derived general equation which agrees well with the superconducting
transition temperatures for the heavy-electron superconductors, metallic
superconductors, oxide supercon- ductors, metallic hydrogen, and neutron stars,
also works well for the superfluid transition temperature of 2.6 mK for liquid
3He. Reasonable estimates are made from 10^-3 K to 10^9K -- a range of 12
orders of magnitude. The same paradigm applies to the superfluid transition
temperature of liquid 4He, but results in a slightly different equation. The
superfluid transition temperature for dilute solutions of 3He in superfluid 4He
is estimated to be ~ 1 to 10mK. This paradigm works well in detail for
metallic, cuprate, and organic superconductors.Comment: 16 pages, 2 figure
Cliniciansâ Perceptions of Telemedicine for Conducting Family Conferences Prior to Transfer to a Tertiary Care Center Intensive Care Unit
Objectives: Critically ill patients are often transferred from rural to tertiary care medical centres for further higher levels of care. The transportation process may delay family conferences during which prognosis and goals of care are discussed. These conferences typically occur when family members meet the treating physicians for the first time in person after transport. Telemedicine is a tool that may be used to bridge this gap in communication by enabling these family conferences before transport. There are no data on perceptions of telemedicine used in this setting. We conducted a qualitative study assessing provider perceptions regarding the use of telemedicine for conducting family conferences prior to transport. Methods: Critical care physicians and nurses were invited to view an educational video demonstrating the process of conducting a family conference via telemedicine. Immediately following viewing of the video, physicians and nurses filled out an open-ended questionnaire regarding their thoughts and perceptions of the video and the telemedicine family conference approach. Results: There was a 68% response rate to the surveys. Responses were categorised into two major themes: benefits and barriers. Within the theme of benefits, three sub-themes were identified: satisfaction, knowledge and quality of care. We identified four domains within the theme of barriers: time, perception, technology and logistics. Conclusions: Respondents believe that there may be several benefits including increased satisfaction, improved communication and empowerment of families by dissemination of knowledge. Barriers to the use of this intervention identified include costs, time, technology and negative perceptions of the telemedicine conference
Satellites of the largest Kuiper Belt objects
We have searched the four brightest objects in the Kuiper Belt for the presence of satellites using the newly commissioned Keck Observatory Laser Guide Star Adaptive Optics system. Satellites are seen around three of the four objects: Pluto (whose satellite Charon is well-known and whose recently discovered smaller satellites are too faint to be detected), 2003 EL61 (where a second satellite is seen in addition to the previously known satellite), and 2003 UB313 (where a satellite is seen for the first time). The object 2005 FY9, the brightest Kuiper Belt object (KBO) after Pluto, does not have a satellite detectable within 0".4 with a brightness of more than 1% of the primary. The presence of satellites around three of the four brightest KBOs is inconsistent with the fraction of satellites in the Kuiper Belt at large at the 99.2% confidence level, suggesting a different formation mechanism for these largest KBO satellites. The two satellites of 2003 EL61, and the one satellite of 2003 UB313, with fractional brightnesses of 5% and 1.5%, and 2%, of their primaries, respectively, are significantly fainter relative to their primaries than other known KBO satellites, again pointing to possible differences in their origin
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