Search

Your search keyword '"Maier, E. R."' showing total 6 results
Start Over Author "Maier, E. R."
6 results on '"Maier, E. R."'

1. A two-band approach to n$\lambda$ phase error corrections with LBTI's PHASECam

Author

Maier, E. R., Hinz, P. M., Defrère, D., Ertel, S., and Downey, E.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

PHASECam is the Large Binocular Telescope Interferometer's (LBTI) phase sensor, a near-infrared camera which is used to measure tip/tilt and phase variations between the two AO-corrected apertures of the Large Binocular Telescope (LBT). Tip/tilt and phase sensing are currently performed in the H (1.65 $\mu$m) and K (2.2 $\mu$m) bands at 1 kHz, and the K band phase telemetry is used to send tip/tilt and Optical Path Difference (OPD) corrections to the system. However, phase variations outside the range [-$\pi$, $\pi$] are not sensed, and thus are not fully corrected during closed-loop operation. PHASECam's phase unwrapping algorithm, which attempts to mitigate this issue, still occasionally fails in the case of fast, large phase variations. This can cause a fringe jump, in which case the unwrapped phase will be incorrect by a wavelength or more. This can currently be manually corrected by the observer, but this is inefficient. A more reliable and automated solution is desired, especially as the LBTI begins to commission further modes which require robust, active phase control, including controlled multi-axial (Fizeau) interferometry and dual-aperture non-redundant aperture masking interferometry. We present a multi-wavelength method of fringe jump capture and correction which involves direct comparison between the K band and currently unused H band phase telemetry., Comment: 17 pages, 10 figures

Published
2018
Full Text
View/download PDF

3. The Roman space telescope coronagraph technology demonstration: current status and relevance to future missions

Author

Mennesson, B., Bailey, V. P., Zellem, R., Hildebrandt, S., Ygouf, M., Rhodes, J., Zimmerman, N., Kasdin, J., Macintosh, B., Turnbull, M., Douglas, E., Mandell, A., Maier, E. R., Nemati, B., Gonzalez, G., Cady, E., Kern, B., Krist, J., Heydorff, K., Luchik, T., Mok, F., Morrissey, P., Pobereszhskiy, I., Riggs, A. J., Shi, F., Zhao, F., Akeson, R., Armus, L., Ingalls, J., Lowrance, P., Meshkat, T., Shaklan, Stuart B., and Ruane, Garreth J.

Subjects
Wavefront, Data processing, Spitzer Space Telescope, law, Computer science, Detector, Astronomy, Large format, Coronagraph, Exoplanet, Deformable mirror, law.invention
Abstract

The Nancy Grace Roman Space Telescope (formally WFIRST) will be launched in the mid-2020’s with an onboard coronagraph instrument which will serve as a technology demonstrator for exoplanet direct imaging. The Roman Coronagraph will be capable of detecting and characterizing exoplanets and circumstellar disks in visible light at an unprecedented contrast level of ~10⁻⁸ or lower. Such a contrast level, which is several magnitudes better than state-of-the-art visible or near-infrared coronagraphs, raises entirely new challenges that will be overcome using a combination of hardware, calibration and data processing. In particular, the Roman Coronagraph will be the first space-based coronagraphic instrument with real-time active wavefront control through the use of large format deformable mirrors, and its EMCCD detector will enable faint signal detection in photon-counting mode. The Roman Coronagraph instrument passed its critical design review successfully in April 2021, and is now well on its path to demonstrate many core technologies at the levels required for future exo-Earth direct imaging missions.

Published
2021
Full Text
View/download PDF

4. The Roman space telescope coronagraph technology demonstration: current status and relevance to future missions

Author

Shaklan, Stuart B., Ruane, Garreth J., Mennesson, B., Bailey, V. P., Zellem, R., Hildebrandt, S., Ygouf, M., Rhodes, J., Zimmerman, N., Kasdin, J., Macintosh, B., Turnbull, M., Douglas, E., Mandell, A., Maier, E. R., Nemati, B., Gonzalez, G., Cady, E., Kern, B., Krist, J., Heydorff, K., Luchik, T., Mok, F., Morrissey, P., Pobereszhskiy, I., Riggs, A. J., Shi, F., Zhao, F., Akeson, R., Armus, L., Ingalls, J., Lowrance, P., Meshkat, T., Shaklan, Stuart B., Ruane, Garreth J., Mennesson, B., Bailey, V. P., Zellem, R., Hildebrandt, S., Ygouf, M., Rhodes, J., Zimmerman, N., Kasdin, J., Macintosh, B., Turnbull, M., Douglas, E., Mandell, A., Maier, E. R., Nemati, B., Gonzalez, G., Cady, E., Kern, B., Krist, J., Heydorff, K., Luchik, T., Mok, F., Morrissey, P., Pobereszhskiy, I., Riggs, A. J., Shi, F., Zhao, F., Akeson, R., Armus, L., Ingalls, J., Lowrance, P., and Meshkat, T.

Abstract

The Nancy Grace Roman Space Telescope (formally WFIRST) will be launched in the mid-2020’s with an onboard coronagraph instrument which will serve as a technology demonstrator for exoplanet direct imaging. The Roman Coronagraph will be capable of detecting and characterizing exoplanets and circumstellar disks in visible light at an unprecedented contrast level of ~10⁻⁸ or lower. Such a contrast level, which is several magnitudes better than state-of-the-art visible or near-infrared coronagraphs, raises entirely new challenges that will be overcome using a combination of hardware, calibration and data processing. In particular, the Roman Coronagraph will be the first space-based coronagraphic instrument with real-time active wavefront control through the use of large format deformable mirrors, and its EMCCD detector will enable faint signal detection in photon-counting mode. The Roman Coronagraph instrument passed its critical design review successfully in April 2021, and is now well on its path to demonstrate many core technologies at the levels required for future exo-Earth direct imaging missions.

Published
2021

6. Amino acid administration enhances renal protein metabolism after acute tubular necrosis.

Author

Toback FG, Dodd RC, Maier ER, and Havener LJ

Subjects
Amino Acids administration & dosage, Animals, Infusions, Parenteral, Kidney Tubular Necrosis, Acute therapy, Leucine metabolism, Male, Rats, Rats, Inbred Strains, Acute Kidney Injury metabolism, Amino Acids therapeutic use, Kidney Cortex metabolism, Kidney Tubular Necrosis, Acute metabolism, Proteins metabolism
Abstract

The capacity of exogenous amino acids to alter renal protein metabolism was studied during renal regeneration after mercuric chloride-induced acute tubular necrosis in the rat. In regenerating cortical tissue, the free leucine concentration was 17% lower than normal, and was decreased further after glucose infusion. The concentration was raised above normal by amino acid infusion thereby ameliorating the deficit of this amino acid. Synthesis and degradation of rapidly-turning over proteins in renal cortical cells was examined in vitro. Renal protein synthesis in cortical slices was assessed by measurements of tissue leucine specific radioactivity and cycloheximide-inhibitable [14C]leucine incorporation into protein. Protein synthesis in regenerating tissue was 52% higher than normal and was not increased further by glucose infusion. In contrast, amino acid infusion increased the rate 47% above that observed after an isocaloric glucose infusion, thereby demonstrating that amino acid enhancement of protein synthesis is superimposed upon the increased synthetic rate observed during renal regeneration. Renal protein degradation remained at the normal rate after amino acid infusion, but was increased in regenerating tissue and after glucose infusion. These results indicate that infused amino acids act on the kidney to enhance protein synthesis and reduce protein degradation in regenerating renal cells after acute tubular necrosis.

Published
1983
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results