322 research outputs found
Disease modification and other trials in systemic sclerosis have come a long way, but have to go further
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92019/1/21673_ftp.pd
EFFECTIVENESS OF SURGICAL RECONSTRUCTION TO RESTORE RADIOCARPAL JOINT MECHANICS AFTER SCAPHOLUNATE LIGAMENT INJURY. AN IN VIVO MODELING STUDY
Disruption of the scapholunate ligament can cause a loss of normal scapholunate mechanics and eventually lead to osteoarthritis. Surgical reconstruction attempts to restore scapholunate relationship and shows improvement in functional outcomes, but postoperative effectiveness in restoring normal radiocarpal mechanics still remains a question. The objective of this study was to investigate the benefits of surgical repair by observing changes in contact mechanics on the cartilage surface before and after surgical treatment. Six patients with unilateral scapholunate dissociation were enrolled in the study, and displacement driven magnetic resonance image based-surface contact modeling was used to investigate normal, injured and postoperative radiocarpal mechanics. Model geometry was acquired from images of wrists taken in a relaxed position. Kinematics were acquired from image registration between the relaxed images, and images taken during functional loading. Results showed a trend for increase in radiocarpal contact parameters with injury. Peak and mean contact pressures significantly decreased after surgery in the radiolunate articulation and there were no significant differences between normal and postoperative wrists. Results indicated surgical repair improves contact mechanics after injury and that contact mechanics can be surgically restored to be similar to normal. This study provides novel contact mechanics data on the effects of surgical repair after scapholunate ligament injury. With further work, it may be possible to more effectively differentiate between treatments and degenerative changes based on in vivo contact mechanics data
Deep three-dimensional solid-state qubit arrays with long-lived spin coherence
Nitrogen-vacancy centers (NVCs) in diamond show promise for quantum computing, communication, and sensing. However, the best current method for entangling two NVCs requires that each one is in a separate cryostat, which is not scalable. We show that single NVCs can be laser written 6–15-µm deep inside of a diamond with spin coherence times that are an order of magnitude longer than previous laser-written NVCs and at least as long as naturally occurring NVCs. This depth is suitable for integration with solid immersion lenses or optical cavities and we present depth-dependent T2 measurements. 200 000 of these NVCs would fit into one diamond
Wandering Black Hole Candidates in Dwarf Galaxies at VLBI Resolution
Thirteen dwarf galaxies have recently been found to host radio-selected
accreting massive black hole (MBH) candidates, some of which are ``wandering"
in the outskirts of their hosts. We present 9 GHz Very Long Baseline Array
(VLBA) observations of these sources at milliarcsecond resolution. Our
observations have beam solid angles times smaller than the
previous Very Large Array (VLA) observations at 9 GHz, with comparable point
source sensitivities. We detect milliarcsecond-scale radio sources at the
positions of the four VLA sources most distant from the photo-centers of their
associated dwarf galaxies. These sources have brightness temperatures of
, consistent with active galactic nuclei (AGNs), but the
significance of their preferential location at large distances
(-value~) favors a background AGN interpretation. The VLBA
non-detections toward the other 9 galaxies indicate that the VLA sources are
resolved out on scales of tens of milliarcseconds, requiring extended radio
emission and lower brightness temperatures consistent with either star
formation or radio lobes associated with AGN activity. We explore the star
formation explanation by calculating the expected radio emission for these nine
VLBA non-detections, finding that about 5 have VLA luminosities that are
inconsistent with this scenario. Of the remaining four, two are associated with
spectroscopically confirmed AGNs that are consistent with being located at
their galaxy photo-centers. There are therefore between 5 and 7 wandering MBH
candidates out of the 13 galaxies we observed, although we cannot rule out
background AGNs for five of them with the data in hand.Comment: 13 pages, 3 figures, Accepted in Ap
The Structure of the {\beta} Leonis Debris Disk
We combine nulling interferometry at 10 {\mu}m using the MMT and Keck
Telescopes with spectroscopy, imaging, and photometry from 3 to 100 {\mu}m
using Spitzer to study the debris disk around {\beta} Leo over a broad range of
spatial scales, corresponding to radii of 0.1 to ~100 AU. We have also measured
the close binary star o Leo with both Keck and MMT interferometers to verify
our procedures with these instruments. The {\beta} Leo debris system has a
complex structure: 1.) relatively little material within 1 AU; 2.) an inner
component with a color temperature of ~600 K, fitted by a dusty ring from about
2 to 3 AU; and 3.) a second component with a color temperature of ~120 K fitted
by a broad dusty emission zone extending from about ~5 AU to ~55 AU. Unlike
many other A-type stars with debris disks, {\beta} Leo lacks a dominant outer
belt near 100 AU.Comment: 14 page body, 3 page appendix, 15 figure
- …