24,974 research outputs found
Understanding the truth about subjectivity
Results of two experiments show childrenās understanding of diversity in personal preference is incomplete. Despite acknowledging diversity, in Experiment 1(N=108), 6-
and 8-year-old children were less likely than adults to see preference as a legitimate basis for personal tastes and more likely to say a single truth could be found about a matter of taste. In Experiment 2 (N=96), 7- and 9-year-olds were less likely than 11- and 13-yearolds to say a dispute about a matter of preference might not be resolved. These data suggest that acceptance of the possibility of diversity does not indicate an adult-like understanding of subjectivity. An understanding of the relative emphasis placed on objective and subjective factors in different contexts continues to develop into adolescence
Ground effects on V/STOL and STOL aircraft: A survey
The flow fields encountered by jet- and fan-powered Vertical/Short Takeoff and Landing (V/STOL) aircraft operating in ground effect are reviewed and their general effects on the aerodynamic characteristics are discussed. The ground effects considered include: (1) the suckdown experienced by a single jet configuration in hover; (2) the fountain flow and additional suckdown experienced by multiple jet configurations in hover; (3) the ground vortex generated by jet and jet flap configurations in short takeoff and landing (STOL) operation and the associated aerodynamic and hot-gas-ingestion effects; and (4) the change in the downwash at the tail due to ground proximity. After over 30 years of research on V/STOL aircraft, the general flow phenomena are well-known and, in most areas, the effects of ground proximity can be established or can be determined experimentally. However, there are some anomalies in the current data base which are discussed
Calibrating and Stabilizing Spectropolarimeters with Charge Shuffling and Daytime Sky Measurements
Well-calibrated spectropolarimetry studies at resolutions of 10,000 with
signal-to-noise ratios (SNRs) better than 0.01\% across individual line
profiles, are becoming common with larger aperture telescopes.
Spectropolarimetric studies require high SNR observations and are often limited
by instrument systematic errors. As an example, fiber-fed spectropolarimeters
combined with advanced line-combination algorithms can reach statistical error
limits of 0.001\% in measurements of spectral line profiles referenced to the
continuum. Calibration of such observations is often required both for
cross-talk and for continuum polarization. This is not straightforward since
telescope cross-talk errors are rarely less than 1\%. In solar
instruments like the Daniel K. Inouye Solar Telescope (DKIST), much more
stringent calibration is required and the telescope optical design contains
substantial intrinsic polarization artifacts. This paper describes some
generally useful techniques we have applied to the HiVIS spectropolarimeter at
the 3.7m AEOS telescope on Haleakala. HiVIS now yields accurate polarized
spectral line profiles that are shot-noise limited to 0.01\% SNR levels at our
full spectral resolution of 10,000 at spectral sampling of 100,000. We
show line profiles with absolute spectropolarimetric calibration for cross-talk
and continuum polarization in a system with polarization cross-talk levels of
essentially 100\%. In these data the continuum polarization can be recovered to
one percent accuracy because of synchronized charge-shuffling model now working
with our CCD detector. These techniques can be applied to other
spectropolarimeters on other telescopes for both night and day-time
applications such as DKIST, TMT and ELT which have folded non-axially symmetric
foci.Comment: Accepted to A&
Unifying metastasis--Integrating intravasation, circulation and end organ colonization
Recent technological advances that have enabled the measurement of circulating tumour cells (CTCs) in patients have spurred interest in the circulatory phase of metastasis. Techniques that do not solely rely on a blood sample allow substantial biological interrogation beyond simply counting CTCs
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