226 research outputs found
NICU Poster - 2019
NICU Poster - 2019https://scholarlycommons.libraryinfo.bhs.org/research_education/1006/thumbnail.jp
A method for evaluating the murine pulmonary vasculature using micro-computed tomography
AbstractBackgroundSignificant mortality and morbidity are associated with alterations in the pulmonary vasculature. While techniques have been described for quantitative morphometry of whole-lung arterial trees in larger animals, no methods have been described in mice. We report a method for the quantitative assessment of murine pulmonary arterial vasculature using high-resolution computed tomography scanning.MethodsMice were harvested at 2 weeks, 4 weeks, and 3 months of age. The pulmonary artery vascular tree was pressure perfused to maximal dilation with a radio-opaque casting material with viscosity and pressure set to prevent capillary transit and venous filling. The lungs were fixed and scanned on a specimen computed tomography scanner at 8-μm resolution, and the vessels were segmented. Vessels were grouped into categories based on lumen diameter and branch generation.ResultsRobust high-resolution segmentation was achieved, permitting detailed quantitation of pulmonary vascular morphometrics. As expected, postnatal lung development was associated with progressive increase in small-vessel number and arterial branching complexity.ConclusionsThese methods for quantitative analysis of the pulmonary vasculature in postnatal and adult mice provide a useful tool for the evaluation of mouse models of disease that affect the pulmonary vasculature
Supernova PTF12glz: a possible shock breakout driven through an aspherical wind
We present visible-light and ultraviolet (UV) observations of the supernova
PTF12glz. The SN was discovered and monitored in near-UV and R bands as part of
a joint GALEX and Palomar Transient Factory campaign. It is among the most
energetic Type IIn supernovae observed to date (~10^51erg). If the radiated
energy mainly came from the thermalization of the shock kinetic energy, we show
that PTF12glz was surrounded by ~1 solar mass of circumstellar material (CSM)
prior to its explosive death. PTF12glz shows a puzzling peculiarity: at early
times, while the freely expanding ejecta are presumably masked by the optically
thick CSM, the radius of the blackbody that best fits the observations grows at
~8000km/s. Such a velocity is characteristic of fast moving ejecta rather than
optically thick CSM. This phase of radial expansion takes place before any
spectroscopic signature of expanding ejecta appears in the spectrum and while
both the spectroscopic data and the bolometric luminosity seem to indicate that
the CSM is optically thick. We propose a geometrical solution to this puzzle,
involving an aspherical structure of the CSM around PTF12glz. By modeling
radiative diffusion through a slab of CSM, we show that an aspherical geometry
of the CSM can result in a growing effective radius. This simple model also
allows us to recover the decreasing blackbody temperature of PTF12glz.
SLAB-Diffusion, the code we wrote to model the radiative diffusion of photons
through a slab of CSM and evaluate the observed radius and temperature, is made
available on-line.Comment: Sumbitted to ApJ. Comments are welcom
Cataclysmic Variables in the First Year of the Zwicky Transient Facility
Using selection criteria based on amplitude, time, and color, we have identified 329 objects as known or candidate cataclysmic variables (CVs) during the first year of testing and operation of the Zwicky Transient Facility. Of these, 90 are previously confirmed CVs, 218 are strong candidates based on the shape and color of their light curves obtained during 3–562 days of observation, and the remaining 21 are possible CVs but with too few data points to be listed as good candidates. Almost half of the strong candidates are within 10 deg of the galactic plane, in contrast to most other large surveys that have avoided crowded fields. The available Gaia parallaxes are consistent with sampling the low mass transfer CVs, as predicted by population models. Our follow-up spectra have confirmed Balmer/helium emission lines in 27 objects, with four showing high-excitation He ii emission, including candidates for an AM CVn, a polar, and an intermediate polar. Our results demonstrate that a complete survey of the Galactic plane is needed to accomplish an accurate determination of the number of CVs existing in the Milky Way
Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma
Purpose
To compare optic disc perfusion between normal subjects and subjects with glaucoma using optical coherence tomography (OCT) angiography and to detect optic disc perfusion changes in glaucoma.
Design
Observational, cross-sectional study.
Participants
Twenty-four normal subjects and 11 patients with glaucoma were included.
Methods
One eye of each subject was scanned by a high-speed 1050-nm–wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to compute 3-dimensional optic disc angiography. A disc flow index was computed from 4 registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc (C/D) ratios. Wide-field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness.
Main Outcome Measures
Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations among disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression.
Results
In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in subjects with glaucoma. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV, respectively. The disc flow index was reduced by 25% in the glaucoma group (P = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation (R[superscript 2] = 0.752, P = 0.001). These correlations were significant even after accounting for age, C/D area ratio, NFL, and rim area.
Conclusions
Optical coherence tomography angiography, generated by the new SSADA, repeatably measures optic disc perfusion and may be useful in the evaluation of glaucoma and glaucoma progression.National Institutes of Health (U.S.) (Grant 1R01 EY023285-01)Rosenbaum's P30EY010572National Institutes of Health (U.S.). Clinical and Translational Science Awards (CTSA) Program (Grant UL1TR000128)Research to Prevent Blindness, Inc. (United States) (Grant R01-EY11289-26)United States. Air Force Office of Scientific Research (FA9550-10-1-0551)German Research Foundation (DFG-HO-1791/11-1)German Research Foundation (DFG-GSC80-SAOT)German Research Foundation (Training Group 1773
Real-Time Detection and Rapid Multiwavelength Follow-up Observations of a Highly Subluminous Type II-P Supernova from the Palomar Transient Factory Survey
The Palomar Transient Factory (PTF) is an optical wide-field variability
survey carried out using a camera with a 7.8 square degree field of view
mounted on the 48-in Oschin Schmidt telescope at Palomar Observatory. One of
the key goals of this survey is to conduct high-cadence monitoring of the sky
in order to detect optical transient sources shortly after they occur. Here, we
describe the real-time capabilities of the PTF and our related rapid
multiwavelength follow-up programs, extending from the radio to the gamma-ray
bands. We present as a case study observations of the optical transient
PTF10vdl (SN 2010id), revealed to be a very young core-collapse (Type II-P)
supernova having a remarkably low luminosity. Our results demonstrate that the
PTF now provides for optical transients the real-time discovery and
rapid-response follow-up capabilities previously reserved only for high-energy
transients like gamma-ray bursts.Comment: ApJ, in press; all spectroscopic data available from the Weizmann
Institute of Science Experimental Astrophysics Spectroscopy System (WISEASS;
http://www.weizmann.ac.il/astrophysics/wiseass/
- …