699 research outputs found
An efficient surrogate model for emulation and physics extraction of large eddy simulations
In the quest for advanced propulsion and power-generation systems,
high-fidelity simulations are too computationally expensive to survey the
desired design space, and a new design methodology is needed that combines
engineering physics, computer simulations and statistical modeling. In this
paper, we propose a new surrogate model that provides efficient prediction and
uncertainty quantification of turbulent flows in swirl injectors with varying
geometries, devices commonly used in many engineering applications. The novelty
of the proposed method lies in the incorporation of known physical properties
of the fluid flow as {simplifying assumptions} for the statistical model. In
view of the massive simulation data at hand, which is on the order of hundreds
of gigabytes, these assumptions allow for accurate flow predictions in around
an hour of computation time. To contrast, existing flow emulators which forgo
such simplications may require more computation time for training and
prediction than is needed for conducting the simulation itself. Moreover, by
accounting for coupling mechanisms between flow variables, the proposed model
can jointly reduce prediction uncertainty and extract useful flow physics,
which can then be used to guide further investigations.Comment: Submitted to JASA A&C
GAMIVAL: Video Quality Prediction on Mobile Cloud Gaming Content
The mobile cloud gaming industry has been rapidly growing over the last
decade. When streaming gaming videos are transmitted to customers' client
devices from cloud servers, algorithms that can monitor distorted video quality
without having any reference video available are desirable tools. However,
creating No-Reference Video Quality Assessment (NR VQA) models that can
accurately predict the quality of streaming gaming videos rendered by computer
graphics engines is a challenging problem, since gaming content generally
differs statistically from naturalistic videos, often lacks detail, and
contains many smooth regions. Until recently, the problem has been further
complicated by the lack of adequate subjective quality databases of mobile
gaming content. We have created a new gaming-specific NR VQA model called the
Gaming Video Quality Evaluator (GAMIVAL), which combines and leverages the
advantages of spatial and temporal gaming distorted scene statistics models, a
neural noise model, and deep semantic features. Using a support vector
regression (SVR) as a regressor, GAMIVAL achieves superior performance on the
new LIVE-Meta Mobile Cloud Gaming (LIVE-Meta MCG) video quality database.Comment: Accepted to IEEE SPL 2023. The implementation of GAMIVAL has been
made available online: https://github.com/lskdream/GAMIVA
Study of Subjective and Objective Quality Assessment of Mobile Cloud Gaming Videos
We present the outcomes of a recent large-scale subjective study of Mobile
Cloud Gaming Video Quality Assessment (MCG-VQA) on a diverse set of gaming
videos. Rapid advancements in cloud services, faster video encoding
technologies, and increased access to high-speed, low-latency wireless internet
have all contributed to the exponential growth of the Mobile Cloud Gaming
industry. Consequently, the development of methods to assess the quality of
real-time video feeds to end-users of cloud gaming platforms has become
increasingly important. However, due to the lack of a large-scale public Mobile
Cloud Gaming Video dataset containing a diverse set of distorted videos with
corresponding subjective scores, there has been limited work on the development
of MCG-VQA models. Towards accelerating progress towards these goals, we
created a new dataset, named the LIVE-Meta Mobile Cloud Gaming (LIVE-Meta-MCG)
video quality database, composed of 600 landscape and portrait gaming videos,
on which we collected 14,400 subjective quality ratings from an in-lab
subjective study. Additionally, to demonstrate the usefulness of the new
resource, we benchmarked multiple state-of-the-art VQA algorithms on the
database. The new database will be made publicly available on our website:
\url{https://live.ece.utexas.edu/research/LIVE-Meta-Mobile-Cloud-Gaming/index.html}Comment: Accepted to IEEE Transactions on Image Processing, 2023. The database
will be publicly available by 1st week of July 202
Galaxy source counts at 7.7 m, 10 m and 15 m with the James Webb Space Telescope
We present mid-infrared galaxy number counts based on the Early Release
Observations obtained by the James Webb Space Telescope (JWST) at 7.7-, 10- and
15-m (F770W, F1000W and F1500W, respectively) bands of the Mid-Infrared
Instrument (MIRI). Due to the superior sensitivity of JWST, the 80 percent
completeness limits reach 0.32, 0.79 and 2.0 Jy in F770W, F1000W and
F1500W filters, respectively, i.e., 100 times deeper than previous space
infrared telescopes such as Spitzer or AKARI. The number counts reach much
deeper than the broad bump around mJy due to polycyclic aromatic
hydrocarbon (PAH) emissions. An extrapolation towards fainter flux from the
evolutionary models in the literature agrees amazingly well with the new data,
where the extrapolated faint-end of infrared luminosity functions combined with
the cosmic star-formation history to higher redshifts can reproduce the deeper
number counts by JWST. Our understanding of the faint infrared sources has been
confirmed by the observed data due to the superb sensitivity of JWST.Comment: 6 pages, 8 figures. Accepted for publication in MNRA
Polycyclic aromatic hydrocarbon (PAH) luminous galaxies in JWST CEERS data
It has been an unanswered question how many dusty galaxies have been
undetected from the state-of-the-art observational surveys. JWST enables us to
detect faint IR galaxies that have prominent polycyclic aromatic hydrocarbon
(PAH) features in the mid-IR wavelengths. PAH is a valuable tracer of star
formation and dust properties in the mid-infrared wavelength. The JWST Cosmic
Evolution Early Release Science (CEERS) fields provide us with wavelength
coverage from 7.7 to 21 m using six photometric bands of the mid-infrared
instrument (MIRI). We have identified galaxies dominated by mid-IR emission
from PAHs, termed PAH galaxies. From our multi-band photometry catalogue, we
selected ten PAH galaxies displaying high flux ratios of . The SED fitting analysis indicates that these galaxies are star-forming
galaxies with total IR luminosities of
at z . The morphology of PAH galaxies does not show any clear
signatures of major merging or interaction within the MIRI resolution. The
majority of them are on the star-formation main sequence at . Our
result demonstrates that JWST can detect PAH emissions from normal star-forming
galaxies at , in addition to ultra-luminous infrared galaxies
(ULIRGs) or luminous infrared galaxies (LIRGs).Comment: 12 pages, 20 figures, 4 tables. Accepted by MNRAS. A summary video is
at https://www.youtube.com/watch?v=UtPaVTFM4f8&ab_channel=NTHUCosmolog
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Functional complexity of hair follicle stem cell niche and therapeutic targeting of niche dysfunction for hair regeneration
Stem cell activity is subject to non-cell-autonomous regulation from the local microenvironment, or niche. In adaption to varying physiological conditions and the ever-changing external environment, the stem cell niche has evolved with multifunctionality that enables stem cells to detect these changes and to communicate with remote cells/tissues to tailor their activity for organismal needs. The cyclic growth of hair follicles is powered by hair follicle stem cells (HFSCs). Using HFSCs as a model, we categorize niche cells into 3 functional modules, including signaling, sensing and message-relaying. Signaling modules, such as dermal papilla cells, immune cells and adipocytes, regulate HFSC activity through short-range cell-cell contact or paracrine effects. Macrophages capacitate the HFSC niche to sense tissue injury and mechanical cues and adipocytes seem to modulate HFSC activity in response to systemic nutritional states. Sympathetic nerves implement the message-relaying function by transmitting external light signals through an ipRGC-SCN-sympathetic circuit to facilitate hair regeneration. Hair growth can be disrupted by niche pathology, e.g. dysfunction of dermal papilla cells in androgenetic alopecia and influx of auto-reacting T cells in alopecia areata and lichen planopilaris. Understanding the functions and pathological changes of the HFSC niche can provide new insight for the treatment of hair loss
The bracteatus pineapple genome and domestication of clonally propagated crops
Domestication of clonally propagated crops such as pineapple from South America was hypothesized to be a 'one-step operation'. We sequenced the genome of Ananas comosus var. bracteatus CB5 and assembled 513 Mb into 25 chromosomes with 29,412 genes. Comparison of the genomes of CB5, F153 and MD2 elucidated the genomic basis of fiber production, color formation, sugar accumulation and fruit maturation. We also resequenced 89 Ananas genomes. Cultivars 'Smooth Cayenne' and 'Queen' exhibited ancient and recent admixture, while 'Singapore Spanish' supported a one-step operation of domestication. We identified 25 selective sweeps, including a strong sweep containing a pair of tandemly duplicated bromelain inhibitors. Four candidate genes for self-incompatibility were linked in F153, but were not functional in self-compatible CB5. Our findings support the coexistence of sexual recombination and a one-step operation in the domestication of clonally propagated crops. This work guides the exploration of sexual and asexual domestication trajectories in other clonally propagated crops
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