975 research outputs found
Wind-tunnel free-flight investigation of a model of a forward-swept-wing fighter configuration
A wind-tunnel free-flight investigation was conducted to study the dynamic stability characteristics of a model of a forward-swept-wing fighter-airplane configuration at high angles of attack. Various other wind-tunnel techniques employed in the study included static- and dynamic- (forced-oscillation) force tests, free-to-roll tests, and flow-visualization tests. A unique facet of the study was the extreme level of static pitch instability (in excess of negative 32-percent static margin) inherent in the airframe design which precluded free-flight testing without stability augmentation in pitch. Results are presented which emphasize the high-angle-of-attack aerodynamics and the vehicle-component contributions to these characteristics. The effects of these aerodynamic characteristics on the high-angle-of-attack flying qualities of the configuration are discussed in terms of results of the wind-tunnel free-flight tests
Sodium dependent inositol transport in HL60 cells is not related to Na+/K+, ATPase activity
AbstractIn HL60 cells, inositol transport is sodium-dependent but functionally independent of Na+/K+ ATPase activity. This observation has implications for the currently proposed theory for the development of diabetic complications
How can we demonstrate the economic value of Precision Agriculture (PA) practices to New Zealand Agriculture service providers and arable farmers?
The amount of data collected has become a major challenge to the uptake of PA practices in New Zealand.
There is a lack of clear value propositions around some PA practices, e.g. variable rate seeding (VRS).
The importance of calibrating yield monitors, collecting yield data and mapping results has not been realised by farmers.
The goal of the study is to provide economic evidence through yield data mining to encourage the adoption of PA
Photoionisation Modelling of the X-ray Emission Line Regions within the Seyfert 2 AGN NGC 1068
We investigate the photoionised X-ray emission line regions (ELRs) within the
Seyfert 2 galaxy NGC 1068, to determine if there are any characteristic changes
between observations taken fourteen years apart. We compare XMM-Newton
observations collected in 2000 and 2014, simultaneously fitting the reflection
grating spectrometer (RGS) and EPIC-pn spectra of each epoch, for the first
time, with the photoionisation model, PION, in SPEX. We find that four PION
components are required to fit the majority of the emission lines in the
spectra of NGC 1068, with , , and
to for both epochs. Comparing the ionisation
state of the components shows almost no difference between the two epochs,
while there is an increase in the total column density. To estimate the
locations of these plasma regions from the central black hole we compare
distance methods, excluding the variability arguments as there is no spectral
change between observations. Although the methods are unable to constrain the
distances, the locations are consistent with the narrow line region, with the
possibility of the higher ionised component being part of the broad line
region, but we cannot conclude this for certain. In addition, we find evidence
for emission from collisionally ionised plasma, while previous analysis had
suggested that collisional plasma emission was unlikely. However, although PION
is unable to account for the FeXVII emission lines at 15 and 17 \AA, we do not
rule out that photoexcitation is a valid processes to produce these lines too.
NGC 1068 has not changed, both in terms of the observed spectra or from our
modelling, within the 14 year time period between observations. This suggests
that the ELRs are fairly static relative to the 14 year time frame between
observations, or there is no dramatic change in the black hole variability.Comment: 19 pages, 10 figure
Spatio-Temporal Dynamics of Human Intention Understanding in Temporo-Parietal Cortex: A Combined EEG/fMRI Repetition Suppression Paradigm
Inferring the intentions of other people from their actions recruits an inferior fronto-parietal action observation network as well as a putative social network that includes the posterior superior temporal sulcus (STS). However, the functional dynamics within and among these networks remains unclear. Here we used functional magnetic resonance imaging (fMRI) and high-density electroencephalogram (EEG), with a repetition suppression design, to assess the spatio-temporal dynamics of decoding intentions. Suppression of fMRI activity to the repetition of the same intention was observed in inferior frontal lobe, anterior intraparietal sulcus (aIPS), and right STS. EEG global field power was reduced with repeated intentions at an early (starting at 60 ms) and a later (âŒ330 ms) period after the onset of a hand-on-object encounter. Source localization during these two intervals involved right STS and aIPS regions highly consistent with RS effects observed with fMRI. These results reveal the dynamic involvement of temporal and parietal networks at multiple stages during the intention decoding and without a strict segregation of intention decoding between these networks
Transient obscuration event captured in NGC 3227 IV. Origin of the obscuring cloud variability
Obscuration events in type I active galactic nuclei (AGN) have been detected
more frequently in recent years. The strong flux decrease in the soft X-ray
band between observations has been caused by clouds with large column densities
transiting our line-of-sight (LOS) and covering the central AGN. Another event
has been captured in NGC 3227 at the end of 2019. We aim to determine the
nature of the observed spectral variability in 2019 obscuration event. We split
the two XMM-Newton observations from 2019 into timing bins of length 10
ks. We used the SPEX code to analyse the 0.35-10 keV EPIC-PN spectra of each
timing bin. In the first observation (Obs 1), there is a strong
anti-correlation between the column density () of the obscurer and the
continuum normalisations of the X-ray power-law and soft Comptonisation
components ( and , respectively). The powerlaw continuum
models the hard X-rays produced by the corona, and the Comptonisation component
models the soft X-ray excess and emission from the accretion disk. Through
further testing we conclude that the continuum is likely to drive the observed
variability, but we cannot rule out a possible contribution from NH of the
obscurer if it fully transverses across the ionising source within our LOS
during the observation. The ionisation parameter () of the obscurer is not
easily constrained, and therefore it is not clear whether it varies in response
to changes in ionising continuum. The second observation (Obs 2) displays a
significantly lower count rate due to the combination of a high NH and covering
fraction of the obscurer, and a lower continuum flux. The observed variability
seen during the obscuration event of NGC 3227 in 2019 is likely driven by the
continuum, but the obscurer varies at the same time, making it difficult to
distinguish between the two possibilities with full certainty.Comment: 19 pages, 15 figure
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