397 research outputs found
Digital Strategies in Local Government: Private Sector and Early Adopters Lessons Learned
In recent years, both the public and private sectors have been using digital strategies, which represent an integration of business and technology plans in an organization. This paper investigates the early adoption of digital strategies in the public sector at the local government level using case studies for southern Ontario that focus on existing academic and practice-based literature, along with documented government adoptions of digital strategies to identify trends and issues. The findings support the private sector lessons and further indicate that there is little consistency in approach, methodology, or stage of digital strategy implementation within the public sector. Research also indicates that Canada has been slow to move forward on digital transformation in general
Baseline Requirements For Detecting Biosignatures with the HabEx and LUVOIR Mission Concepts
A milestone in understanding life in the universe is the detection of
biosignature gases in the atmospheres of habitable exoplanets. Future mission
concepts under study by the 2020 decadal survey, e.g., HabEx and LUVOIR, have
the potential of achieving this goal. We investigate the baseline requirements
for detecting four molecular species, HO, O, CH, and CO,
assuming concentrations of these species equal to that of modern Earth. These
molecules are highly relevant to habitability and life on Earth and other
planets. Through numerical simulations, we find the minimum requirements of
spectral resolution, starlight suppression, and exposure time for detecting
biosignature and habitability marker gases. The results are highly dependent on
cloud conditions. A low-cloud case is more favorable because of deeper and
denser lines whereas a no-cloud case is the pessimistic case for its low
albedo. The minimum exposure time for detecting a certain molecule species can
vary by a large factor (10) between the low-cloud case and the no-cloud
case. For all cases, we provide baseline requirements for HabEx and LUVOIR. The
impact of exo-zodiacal contamination and thermal background is also discussed
and will be included in future studies.Comment: 15 pages, 5 figures, 1 table, accepted by JATI
Observing Exoplanets with High-Dispersion Coronagraphy. II. Demonstration of an Active Single-Mode Fiber Injection Unit
High-dispersion coronagraphy (HDC) optimally combines high contrast imaging
techniques such as adaptive optics/wavefront control plus coronagraphy to high
spectral resolution spectroscopy. HDC is a critical pathway towards fully
characterizing exoplanet atmospheres across a broad range of masses from giant
gaseous planets down to Earth-like planets. In addition to determining the
molecular composition of exoplanet atmospheres, HDC also enables Doppler
mapping of atmosphere inhomogeneities (temperature, clouds, wind), as well as
precise measurements of exoplanet rotational velocities. Here, we demonstrate
an innovative concept for injecting the directly-imaged planet light into a
single-mode fiber, linking a high-contrast adaptively-corrected coronagraph to
a high-resolution spectrograph (diffraction-limited or not). Our laboratory
demonstration includes three key milestones: close-to-theoretical injection
efficiency, accurate pointing and tracking, on-fiber coherent modulation and
speckle nulling of spurious starlight signal coupling into the fiber. Using the
extreme modal selectivity of single-mode fibers, we also demonstrated speckle
suppression gains that outperform conventional image-based speckle nulling by
at least two orders of magnitude.Comment: 10 pages, 7 figures, accepted by Ap
Wavefront control for minimization of speckle coupling into a fiber injection unit based on the electric field conjugation algorithm
A fiber injection unit situated in the focal plane behind a coronagraph feeding a high resolution spectrograph can be used to couple light from an exoplanet to obtain high resolution spectra with improved sensitivity. However, the signal-to-noise ratio of the planet signal is limited by the coupling of starlight into the single mode fiber. To minimize this coupling, we need to apply a control loop on the stellar wavefront at the input of the fiber. We present here a wavefront control algorithm based on the formalism of the Electric Field Conjugation (EFC) controller that accounts for the effect of the fiber. The control output is the overlap integral of the electric field with the fundamental mode of a single mode fiber. This overlap integral is estimated by sending probes to a deformable mirror. We present results from simulations, and laboratory results obtained at the Caltech Exoplanet Technology Lab’s transmissive testbed. We show that our approach offers a significant improvement in starlight suppression through the fiber relative to a conventional EFC controller. This new approach improves the contrast of a high contrast instrument and could be used in future missions
Mechanical effect of friction and stretching on endothelium denudation
Peer reviewed: NoNRC publication: Ye
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