82 research outputs found
DisCoHead: Audio-and-Video-Driven Talking Head Generation by Disentangled Control of Head Pose and Facial Expressions
For realistic talking head generation, creating natural head motion while
maintaining accurate lip synchronization is essential. To fulfill this
challenging task, we propose DisCoHead, a novel method to disentangle and
control head pose and facial expressions without supervision. DisCoHead uses a
single geometric transformation as a bottleneck to isolate and extract head
motion from a head-driving video. Either an affine or a thin-plate spline
transformation can be used and both work well as geometric bottlenecks. We
enhance the efficiency of DisCoHead by integrating a dense motion estimator and
the encoder of a generator which are originally separate modules. Taking a step
further, we also propose a neural mix approach where dense motion is estimated
and applied implicitly by the encoder. After applying the disentangled head
motion to a source identity, DisCoHead controls the mouth region according to
speech audio, and it blinks eyes and moves eyebrows following a separate
driving video of the eye region, via the weight modulation of convolutional
neural networks. The experiments using multiple datasets show that DisCoHead
successfully generates realistic audio-and-video-driven talking heads and
outperforms state-of-the-art methods. Project page:
https://deepbrainai-research.github.io/discohead/Comment: Accepted to ICASSP 202
Accelerated identification of equilibrium structures of multicomponent inorganic crystals using machine learning potentials
The discovery of new multicomponent inorganic compounds can provide direct
solutions to many scientific and engineering challenges, yet the vast size of
the uncharted material space dwarfs current synthesis throughput. While the
computational crystal structure prediction is expected to mitigate this
frustration, the NP-hardness and steep costs of density functional theory (DFT)
calculations prohibit material exploration at scale. Herein, we introduce
SPINNER, a highly efficient and reliable structure-prediction framework based
on exhaustive random searches and evolutionary algorithms, which is completely
free from empiricism. Empowered by accurate neural network potentials, the
program can navigate the configuration space faster than DFT by more than
10-fold. In blind tests on 60 ternary compositions diversely selected
from the experimental database, SPINNER successfully identifies experimental
(or theoretically more stable) phases for ~80% of materials within 5000
generations, entailing up to half a million structure evaluations for each
composition. When benchmarked against previous data mining or DFT-based
evolutionary predictions, SPINNER identifies more stable phases in the majority
of cases. By developing a reliable and fast structure-prediction framework,
this work opens the door to large-scale, unbounded computational exploration of
undiscovered inorganic crystals.Comment: 3 figure
Surface energy-mediated construction of anisotropic semiconductor wires with selective crystallographic polarity.
ZnO is a wide band-gap semiconductor with piezoelectric properties suitable for opto-electronics, sensors, and as an electrode material. Controlling the shape and crystallography of any semiconducting nanomaterial is a key step towards extending their use in applications. Whilst anisotropic ZnO wires have been routinely fabricated, precise control over the specific surface facets and tailoring of polar and non-polar growth directions still requires significant refinement. Manipulating the surface energy of crystal facets is a generic approach for the rational design and growth of one-dimensional (1D) building blocks. Although the surface energy is one basic factor for governing crystal nucleation and growth of anisotropic 1D structures, structural control based on surface energy minimization has not been yet demonstrated. Here, we report an electronic configuration scheme to rationally modulate surface electrostatic energies for crystallographic-selective growth of ZnO wires. The facets and orientations of ZnO wires are transformed between hexagonal and rectangular/diamond cross-sections with polar and non-polar growth directions, exhibiting different optical and piezoelectrical properties. Our novel synthetic route for ZnO wire fabrication provides new opportunities for future opto-electronics, piezoelectronics, and electronics, with new topological properties
Cellular direct conversion by cell penetrable OCT4-30Kc19 protein and BMP4 growth factor
Background : The number of patients suffering from osteoporosis is increasing as the elderly population increases. The demand for investigating bone regeneration strategies naturally arises. One of the approaches to induce bone regeneration is somatic cell transdifferentiation. Among the transcriptional regulators for transdifferentiation, octamer-binding transcription factor 4 (OCT4) is famous for its role in the regulation of pluripotency of stem cells. Bone morphogenetic protein 4 (BMP4) is another factor that is known to have a significant role in osteogenic differentiation. Previous studies have achieved transdifferentiation of cells into osteoblasts using viral and plasmid deliveries of these factors. Although these methods are efficient, viral and plasmid transfection have safety issues such as permanent gene incorporations and bacterial DNA insertions. Herein, we developed a cell penetrating protein-based strategy to induce transdifferentiation of endothelial cells into osteoblasts via nuclear delivery of OCT4 recombinant protein combined with the BMP4 treatment. For the nuclear delivery of OCT4 protein, we fused the protein with 30Kc19, a cell-penetrating and protein stabilizing protein derived from a silkworm hemolymph of Bombyx mori with low cytotoxic properties. This study proposes a promising cell-based therapy without any safety issues that existing transdifferentiation approaches had.
Methods : OCT4-30Kc19 protein with high penetrating activities and stability was synthesized for a protein-based osteogenic transdifferentiation system. Cells were treated with OCT4-30Kc19 and BMP4 to evaluate their cellular penetrating activity, cytotoxicity, osteogenic and angiogenic potentials in vitro. The osteogenic potential of 3D cell spheroids was also analyzed. In addition, in vivo cell delivery into subcutaneous tissue and cranial defect model was performed.
Results : OCT4-30Kc19 protein was produced in a soluble and stable form. OCT4-30Kc19 efficiently penetrated cells and were localized in intracellular compartments and the nucleus. Cells delivered with OCT4-30Kc19 protein combined with BMP4 showed increased osteogenesis, both in 2D and 3D culture, and showed increased angiogenesis capacity in vitro. Results from in vivo subcutaneous tissue delivery of cell-seeded scaffolds confirmed enhanced osteogenic properties of transdifferentiated HUVECs via treatment with both OCT4-30Kc19 and BMP4. In addition, in vivo mouse cranial defect experiment demonstrated successful bone regeneration of HUVECs pretreated with both OCT4-30Kc19 and BMP4.
Conclusions : Using a protein-based transdifferentiation method allows an alternative approach without utilizing any genetic modification strategies, thus providing a possibility for safer use of cell-based therapies in clinical applications.This work was fnancially supported by the Ministry of Science and ICT (NRF2021R1A2C2008821). The Institute of Engineering Research at Seoul National University provided research facilities for this work
Heterogeneous stacking of nanodot monolayers by dry pick-and-place transfer and its applications in quantum dot light-emitting diodes
Layered assembly structures composed of nanomaterials, such as nanocrystals, have
attracted considerable attention as promising candidates for new functional devices whose
optical, electromagnetic and electronic behaviours are determined by the spatial arrangement
of component elements. However, difficulties in handling each constituent layer in a materialspecific
manner limit the 3D integration of disparate nanomaterials into the appropriate
heterogeneous electronics. Here we report a pick-and-place transfer method that enables the
transfer of large-area nanodot assemblies. This solvent-free transfer utilizes a lifting layer and
allows for the reliable transfer of a quantum dot (QD) monolayer, enabling layer-by-layer
design. With the controlled multistacking of different bandgap QD layers, we are able to
probe the interlayer energy transfer among different QD monolayers. By controlling the
emission spectrum through such designed monolayer stacking, we have achieved white
emission with stable optoelectronic properties, the closest to pure white among the QD lightemitting
diodes reported so far. (c) 2013 Macmillan Publishers Limited. All rights reserved.402
Visible Wavelength Color Filters using Dielectric Subwavelength Gratings for Backside-illuminated CMOS Image Sensor Technologies
We report transmissive color filters based on subwavelength dielectric gratings that can replace conventional dye-based color filters used in backside-illuminated CMOS image sensor (BSI CIS) technologies. The filters are patterned in an 80-nm-thick poly-silicon film on a 115-nm-thick SiO_2 spacer layer. They are optimized for operating at the primary RGB colors, exhibit peak transmittance of 60-80%, and an almost insensitive response over a ±20° angular range. This technology enables shrinking of the pixel sizes down to near a micrometer
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
A unified analytical SOI MOSFET model for fully- and partially-depleted SOI devices
We present a new unified analytical front surface potential model. It is valid in all regions of operation (from the sub-threshold to the strong inversion) and an analytical expression for the critical voltage V c delineating the partially depleted (PD) and the fully depleted (FD) region is introduced. The drift/diffusion equation is used to derive a single formula for the drain current valid in all regions of operation. The model has been fit to a range of the Si film thickness t si values of SOI device
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