465 research outputs found
VolTeMorph: Realtime, Controllable and Generalisable Animation of Volumetric Representations
The recent increase in popularity of volumetric representations for scene
reconstruction and novel view synthesis has put renewed focus on animating
volumetric content at high visual quality and in real-time. While implicit
deformation methods based on learned functions can produce impressive results,
they are `black boxes' to artists and content creators, they require large
amounts of training data to generalise meaningfully, and they do not produce
realistic extrapolations outside the training data. In this work we solve these
issues by introducing a volume deformation method which is real-time, easy to
edit with off-the-shelf software and can extrapolate convincingly. To
demonstrate the versatility of our method, we apply it in two scenarios:
physics-based object deformation and telepresence where avatars are controlled
using blendshapes. We also perform thorough experiments showing that our method
compares favourably to both volumetric approaches combined with implicit
deformation and methods based on mesh deformation.Comment: 18 pages, 21 figure
Fractal Bubble Cosmology: A concordant cosmological model?
The Fractal Bubble model has been proposed as a viable cosmology that does
not require dark energy to account for cosmic acceleration, but rather
attributes its observational signature to the formation of structure. In this
paper it is demonstrated that, in contrast to previous findings, this model is
not a good fit to cosmological supernovae data; there is significant tension in
the best fit parameters obtained from different samples, whereas LCDM is able
to fit all datasets consistently. Furthermore, the concordance between galaxy
clustering scales and data from the cosmic microwave background is not achieved
with the most recent supernova compilations. The validity of the FB formalism
as a sound cosmological model is further challenged as it is shown that
previous studies of this model achieve concordance by requiring a value for the
present day Hubble constant that is derived from supernovae data containing an
arbitrary distance normalisation.Comment: 6 pages, 3 figures, revised version published in MNRAS letter
Halo Mass Functions in Early Dark Energy Cosmologies
We examine the linear density contrast at collapse time, for
large-scale structure in dynamical dark energy cosmologies, including models
with early dark energy. Contrary to previous results, we find that as long as
dark energy is homogeneous on small scales, is insensitive to dark
energy properties for parameter values fitting current data, including the case
of early dark energy. This is significant since using the correct is
crucial for accurate Press-Schechter prediction of the halo mass function.
Previous results have found an apparent failing of the extended Press-Schechter
approach (Sheth-Tormen) for early dark energy. Our calculations demonstrate
that with the correct the accuracy of this approach is restored. We
discuss the significance of this result for the halo mass function and examine
what dark energy physics would be needed to cause significant change in
, and the observational signatures this would leave.Comment: 5 pages, 2 figures. Accepted for MNRAS Letter
Hematopoietic Cell–Restricted Deletion of CD36 Reduces High-Fat Diet–Induced Macrophage Infiltration and Improves Insulin Signaling in Adipose Tissue
OBJECTIVE: The fatty acid translocase and scavenger receptor CD36 is important in the recognition and uptake of lipids. Accordingly, we hypothesized that it plays a role in saturated fatty acid-induced macrophage lipid accumulation and proinflammatory activation. RESEARCH DESIGN AND METHODS: In vitro, the effect of CD36 inhibition and deletion in lipid-induced macrophage inflammation was assessed using the putative CD36 inhibitor, sulfosuccinimidyl oleate (SSO), and bone marrow-derived macrophages from mice with (CD36KO) or without (wild-type) global deletion of CD36. To investigate whether deletion of macrophage CD36 would improve insulin sensitivity in vivo, wild-type mice were transplanted with bone marrow from CD36KO or wild-type mice and then fed a standard or high-fat diet (HFD) for 20 weeks. RESULTS: SSO treatment markedly reduced saturated fatty acid-induced lipid accumulation and inflammation in RAW264.7 macrophages. Mice harboring CD36-specific deletion in hematopoietic-derived cells (HSC CD36KO) fed an HFD displayed improved insulin signaling and reduced macrophage infiltration in adipose tissue compared with wild-type mice, but this did not translate into protection against HFD-induced whole-body insulin resistance. Contrary to our hypothesis and our results using SSO in RAW264.7 macrophages, neither saturated fatty acid-induced lipid accumulation nor inflammation was reduced when comparing CD36KO with wild-type bone marrow-derived macrophages. CONCLUSIONS: Although CD36 does not appear important in saturated fatty acid-induced macrophage lipid accumulation, our study uncovers a novel role for CD36 in the migration of proinflammatory phagocytes to adipose tissue in obesity, with a concomitant improvement in insulin action
Hot Quarks and Gluons at an Electron-Ion Collider
The nuclear wave-function is dominated at low- and medium-x by gluons. As the
rapid growth of the gluon distribution towards low x, as derived from current
theoretical estimates, would violate unitarity, there must be a mechanism that
tames this explosive growth. This is most efficiently studied in colliders
running in e+A mode, as the nucleus is an efficient amplifier of saturation
effects occurring with high gluon densities. In fact, large A can lead to these
effects manifesting themselves at energies a few orders of magnitude lower than
in e+p collisions. In order to study these effects, there are proposals to
build an e+A machine in the USA, operating over a large range of masses and
energies. These studies will allow for an in-depth comparison to A+A collisions
where results have given tantalising hints of a new state of matter with
partonic degrees of freedom. In order to explain these results quantitively,
the gluons and their interactions must be understood fully as they are the
dominant source of hard probes at both RHIC and LHC energies.Comment: Proceedings of Hot Quarks 2008 - submitted to EPJ
Kepler Flares II: The Temporal Morphology of White-Light Flares on GJ 1243
We present the largest sample of flares ever compiled for a single M dwarf,
the active M4 star GJ 1243. Over 6100 individual flare events, with energies
ranging from to erg, are found in 11 months of 1-minute
cadence data from Kepler. This sample is unique for its completeness and
dynamic range. We have developed automated tools for finding flares in
short-cadence Kepler light curves, and performed extensive validation and
classification of the sample by eye. From this pristine sample of flares we
generate a median flare template. This template shows that two exponential
cooling phases are present during the white-light flare decay, providing
fundamental constraints for models of flare physics. The template is also used
as a basis function to decompose complex multi-peaked flares, allowing us to
study the energy distribution of these events. Only a small number of flare
events are not well fit by our template. We find that complex, multi-peaked
flares occur in over 80% of flares with a duration of 50 minutes or greater.
The underlying distribution of flare durations for events 10 minutes and longer
appears to follow a broken power law. Our results support the idea that
sympathetic flaring may be responsible for some complex flare events.Comment: 12 pages, 9 figures, accepted for publication in Ap
Can Early Dark Energy be Detected in Non-Linear Structure?
We present the first study of early dark energy cosmologies using N-body
simulations to investigate the formation of non-linear structure. In contrast
to expectations from semi-analytic approaches, we find that early dark energy
does not imprint a unique signature on the statistics of non-linear structures.
Investigating the non-linear power spectra and halo mass functions, we show
that universal mass functions hold for early dark energy, making its presence
difficult to distinguish from CDM. Since early dark energy biases the
baryon acoustic oscillation scale, the lack of discriminating power is
problematic.Comment: 11 pages, 19 figures. Minor changes to match version accepted to
MNRA
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