Melanie Freed

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Use of the highly sensitive Hokupa'a/Gemini curvature wavefront sensor has allowed direct adaptive optics (AO) guiding on very low mass (VLM) stars with SpT=M8.0-L0.5. A survey of 39 such objects detected 9 VLM binaries (7 of which were discovered for the first time to be binaries). Most of these systems are tight (separation < 5 AU) and have similar masses(More)
BACKGROUND Cardiovascular magnetic resonance (CMR) T1 mapping indices, such as T1 time and partition coefficient (λ), have shown potential to assess diffuse myocardial fibrosis. The purpose of this study was to investigate how scanner and field strength variation affect the accuracy and precision/reproducibility of T1 mapping indices. METHODS CMR studies(More)
  • Suresh Sivanandam, Phil M Hinz, Ari N Heinze, Melanie Freed, Andrew H Breuninger
  • 2006
Clio is an adaptive-optics camera mounted on the 6.5 meter MMT optimized for diffraction-limited L' and M-band imaging over a ∼ 15 ′′ field. The instrument was designed from the ground up with a large well-depth, fast readout thermal infrared (∼ 3 − 5 µm) 320 by 256 pixel InSb detector, cooled optics, and associated focal plane and pupil masks (with the(More)
We plan to take advantage of the unprecedented combination of low thermal background and high resolution provided by the 6.5m MMT's adaptive secondary mirror, to target the 3-5 micron atmospheric window where giant exoplanets are expected to be anomalously bright. We are in the process of building a 3-5 micron camera that we will use to carry out a survey(More)
  • Philip M Hinz, A N Heinze, Suresh Sivanandam, Douglas L Miller, Matthew A Kenworthy, Guido Brusa +2 others
  • 2006
Vega may have a massive companion in a wide orbit, as evidenced by structure in its cold dust debris. We have tested this hypothesis by direct imaging with adaptive optics in the M band. The observations were made with a newly commissioned thermal infrared camera, Clio, on the 6.5 MMT AO system with low-background deformable secondary. The observations(More)
Using the adaptive optics system, Hokupa'a, at Gemini-North, we have directly imaged a companion around the UKIRT faint standard M8 star, LHS 2397a (FS 129) at a separation of 2.96 AU. Near-Infrared photometry of the companion has shown it to be an L7.5 brown dwarf and confirmed the spectral type of the primary to be M8. We also derive a substellar mass of(More)
Variability in diagnostic performance of breast dynamic contrast-enhanced MRI has highlighted the need for improved standardization. While guidance exists on some aspects of the technique, currently, there is no standardized method for selecting repetition time and flip angle, which are important determinants of image contrast. This study develops a(More)
We quantify the variation in resolution due to anisotropy caused by oblique X-ray incidence in indirect flat-panel detectors for computed tomography breast imaging systems. We consider a geometry and detector type utilized in breast computed tomography (CT) systems currently being developed. Our methods rely on mantis, a combined X-ray, electron, and(More)
In this paper, we consider a prototype of an adaptive SPECT system, and we use simulation to objectively assess the system's performance with respect to a conventional, non-adaptive SPECT system. Objective performance assessment is investigated for a clinically relevant task: the detection of tumor necrosis at a known location and in a random lumpy(More)
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