Cross-sectional associations between variations in ankle shape by statistical shape modeling, injury history, and race : the Johnston County Osteoarthritis Project

Rheumatology Research Foundation Medical Student Preceptorship Award (Lateef/Nelson), NIAMS K23 AR061406 (Nelson); NIH/NIAMS P60AR064166 and U01DP003206 (Jordan/Renner), NIH/NIAMS R01AR067743 (Golightly). The funders had no role in study design; collection, analysis, or interpretation of data; writing the manuscript or the decision to submit for publication.Peer reviewedPublisher PD

Evaluation of Explanted CorMatrix Intracardiac Patches in Children With Congenital Heart Disease

Animal data demonstrate that intracardiac patches of decellularized porcine small intestine submucosa (CorMatrix; CorMatrix Cardiovascular, Inc, Atlanta, GA) become repopulated with native cells, suggesting the possibility of a substrate for regenerative tissue in humans. We report the only prospective series to date of explanted CorMatrix patches placed in infants with congenital heart disease

The Radio Light Curve of the Gamma-Ray Nova in V407 Cyg: Thermal Emission from the Ionized Symbiotic Envelope, Devoured from Within by the Nova Blast

We present multi-frequency radio observations of the 2010 nova event in the symbiotic binary V407 Cygni, obtained with the Karl G. Jansky Very Large Array and spanning 1-45 GHz and 17-770 days following discovery. This nova---the first ever detected in gamma rays---shows a radio light curve dominated by the wind of the Mira giant companion, rather than the nova ejecta themselves. The radio luminosity grew as the wind became increasingly ionized by the nova outburst, and faded as the wind was violently heated from within by the nova shock. This study marks the first time that this physical mechanism has been shown to dominate the radio light curve of an astrophysical transient. We do not observe a thermal signature from the nova ejecta or synchrotron emission from the shock, due to the fact that these components were hidden behind the absorbing screen of the Mira wind. We estimate a mass loss rate for the Mira wind of Mdot_w ~ 10^-6 M_sun/yr. We also present the only radio detection of V407 Cyg before the 2010 nova, gleaned from unpublished 1993 archival VLA data, which shows that the radio luminosity of the Mira wind varies by a factor of >~20 even in quiescence. Although V407 Cyg likely hosts a massive accreting white dwarf, making it a candidate progenitor system for a Type Ia supernova, the dense and radially continuous circumbinary material surrounding V407 Cyg is inconsistent with observational constraints on the environments of most Type Ia supernovae.Comment: Resubmitted to ApJ after incorporating referee's comment

Radio studies of novae: a current status report and highlights of new results

Novae, which are the sudden visual brightening triggered by runaway thermonuclear burning on the surface of an accreting white dwarf, are fairly common and bright events. Despite their astronomical significance as nearby laboratories for the study of nuclear burning and accretion phenomena, many aspects of these common stellar explosions are observationally not well-constrained and remain poorly understood. Radio observations, modeling and interpretation can potentially play a crucial role in addressing some of these puzzling issues. In this review on radio studies of novae, we focus on the possibility of testing and improving the nova models with radio observations, and present a current status report on the progress in both the observational front and theoretical developments. We specifically address the issues of accurate estimation of ejecta mass, multi-phase and complex ejection phenomena, and the effect of a dense environment around novae. With highlights of new observational results, we illustrate how radio observations can shed light on some of these long-standing puzzles.Comment: 19 pages, 4 figures. Review article published in the Bulletin of the Astronomical Society of India (BASI) special issue on nova

Correcting for T1 bias in Magnetization Transfer Saturation (MTsat) Maps Using Sparse-MP2RAGE

Purpose: Magnetization transfer saturation (MTsat) mapping is commonly used to examine the macromolecular content of brain tissue. This study compared variable flip angle (VFA) T1 mapping against compressed sensing (cs)MP2RAGE T1 mapping for accelerating MTsat imaging. Methods: VFA, MP2RAGE and csMP2RAGE were compared against inversion recovery (IR) T1 in a phantom at 3 Tesla. The same 1 mm VFA, MP2RAGE and csMP2RAGE protocols were acquired in four healthy subjects to compare the resulting T1 and MTsat. Bloch-McConnell simulations were used to investigate differences between the phantom and in vivo T1 results. Finally, ten healthy controls were imaged twice with the csMP2RAGE MTsat protocol to quantify repeatability. Results: The MP2RAGE and csMP2RAGE protocols were 13.7% and 32.4% faster than the VFA protocol, respectively. All approaches provided accurate T1 values (<5% difference) in the phantom, but the accuracy of the T1 times was more impacted by differences in T2 for VFA than for MP2RAGE. In vivo, VFA generated longer T1 times than MP2RAGE and csMP2RAGE. Simulations suggest that the bias in the T1 values between VFA and IR-based approaches (MP2RAGE and IR) could be explained by the MT-effects from the inversion pulse. In the test-retest experiment, we found that the csMP2RAGE has a minimum detectable change of 3% for T1 mapping and 7.9% for MTsat imaging. Conclusions: We demonstrated that csMP2RAGE can be used in place of VFA T1 mapping in an MTsat protocol. Furthermore, a shorter scan time and high repeatability can be achieved using the csMP2RAGE sequence.Comment: 23 pages, 7 figures, 2 table