32 research outputs found
Learning Continuous Grasping Function with a Dexterous Hand from Human Demonstrations
We propose to learn to generate grasping motion for manipulation with a
dexterous hand using implicit functions. With continuous time inputs, the model
can generate a continuous and smooth grasping plan. We name the proposed model
Continuous Grasping Function (CGF). CGF is learned via generative modeling with
a Conditional Variational Autoencoder using 3D human demonstrations. We will
first convert the large-scale human-object interaction trajectories to robot
demonstrations via motion retargeting, and then use these demonstrations to
train CGF. During inference, we perform sampling with CGF to generate different
grasping plans in the simulator and select the successful ones to transfer to
the real robot. By training on diverse human data, our CGF allows
generalization to manipulate multiple objects. Compared to previous planning
algorithms, CGF is more efficient and achieves significant improvement on
success rate when transferred to grasping with the real Allegro Hand. Our
project page is at https://jianglongye.com/cgf .Comment: Project page: https://jianglongye.com/cg
Zeeman field-induced two-dimensional Weyl semimetal phase in cadmium arsenide
We report a topological phase transition in quantum-confined cadmium arsenide
(Cd3As2) thin films under an in-plane Zeeman field when the Fermi level is
tuned into the topological gap via an electric field. Symmetry considerations
in this case predict the appearance of a two-dimensional Weyl semimetal (2D
WSM), with a pair of Weyl nodes of opposite chirality at charge neutrality that
are protected by space-time inversion (C2T) symmetry. We show that the 2D WSM
phase displays unique transport signatures, including saturated resistivities
on the order of h/e^2 that persist over a range of in-plane magnetic fields.
Moreover, applying a small out-of-plane magnetic field, while keeping the
in-plane field within the stability range of the 2D WSM phase, gives rise to a
well-developed odd integer quantum Hall effect, characteristic of degenerate,
massive Weyl fermions. A minimal four-band k.p model of Cd3As2, which
incorporates first-principles effective g factors, qualitatively explains our
findings.Comment: Accepted for publication in Physical Review Letter
Two-dimensional topological insulator state in cadmium arsenide thin films
Two-dimensional topological insulators (2D TIs) are a highly desired quantum
phase but few materials have demonstrated clear signatures of a 2D TI state. It
has been predicted that 2D TIs can be created from thin films of
three-dimensional TIs by reducing the film thickness until the surface states
hybridize. Here, we employ this technique to report the first observation of a
2D TI state in epitaxial thin films of cadmium arsenide, a prototype Dirac
semimetal in bulk form and a 3D TI in thin films. Using magnetotransport
measurements with electrostatic gating, we observe a Landau level spectrum and
quantum Hall effect that are in excellent agreement with those of an ideal 2D
TI. Specifically, we observe a crossing of the zeroth Landau levels at a
critical magnetic field. We show that the film thickness can be used to tune
the critical magnetic field. Moreover, a larger change in film thickness causes
a transition from a 2D TI to a 2D trivial insulator, just as predicted by
theory. The high degree of tunability available in epitaxial cadmium arsenide
heterostructures can thus be used to fine-tune the 2D TI, which is essential
for future topological devices.Comment: Accepted for publication in Physical Review Letters. Fixed issues
with the display of Fig. 3 in the pdf in this versio
Dynamic Handover: Throw and Catch with Bimanual Hands
Humans throw and catch objects all the time. However, such a seemingly common
skill introduces a lot of challenges for robots to achieve: The robots need to
operate such dynamic actions at high-speed, collaborate precisely, and interact
with diverse objects. In this paper, we design a system with two multi-finger
hands attached to robot arms to solve this problem. We train our system using
Multi-Agent Reinforcement Learning in simulation and perform Sim2Real transfer
to deploy on the real robots. To overcome the Sim2Real gap, we provide multiple
novel algorithm designs including learning a trajectory prediction model for
the object. Such a model can help the robot catcher has a real-time estimation
of where the object will be heading, and then react accordingly. We conduct our
experiments with multiple objects in the real-world system, and show
significant improvements over multiple baselines. Our project page is available
at \url{https://binghao-huang.github.io/dynamic_handover/}.Comment: Accepted at CoRL 2023.
https://binghao-huang.github.io/dynamic_handover
Characteristics of nearâsurface soil freezeâthaw status using high resolution CLM5.0 simulations on the Tibetan Plateau
Abstract Soil freezeâthaw alternation is a natural characteristic of the Tibetan Plateau (TP), and plays an important role in surface energy balance and ecoâhydrological processes. The soil freezeâthaw process on the TP has changed significantly owing to global warming, affecting the alpine ecosystem structure and function. This study used highâresolution atmospheric forcing datasets to drive the Community Land Model version 5.0 (CLM5.0) to simulate the nearâsurface soil freezeâthaw status between 1979 and 2020. The simulated results were compared with in situ observations, and then the spatiotemporal distribution of the freeze startâdate (FSD), freeze endâdate (FED), freeze duration (FD), and thaw duration (TD) at a depth of 0.1âm were analyzed. The NashâSutcliffe efficiency coefficients (NSEs) of FSD, FED, FD, and TD between simulations and in situ observations were 0.77, 0.90, 0.98 and 0.92, and the correlation coefficients of FSD, FED, FD, TD were 0.97, 0.99, 0.99 and 0.98, respectively. The spatial distribution of FSD and TD was characterized by gradually increasing from northwest to southeast while FED and FD exhibited the opposite characteristics. FSD, FED, FD, and TD changed at an areaâmean rate of 1.1, â1.4, â2.5, and 2.5âdays decadeâ1, respectively. This study provides an important reference for analyzing and predicting the changes in near surface soil freezeâthaw status on the TP under the warming climate
Edge mode percolation and equilibration in the topological insulator cadmium arsenide
Abstract Two-dimensional topological insulators can feature one-dimensional charge transport via edge modes, which offer a rich ground for studying exotic quasi-particles and for quantum materials applications. In this work, we use lateral junction devices, defined by nanoscale finger gates, to study edge mode transport in the two-dimensional topological insulator Cd3As2. The finger gate can be tuned to transmit an integer number of quantum Hall edge modes and exhibits full equilibration in the bipolar regime. When the Fermi level of the channel crosses a Landau level, reflected modes percolate through the channel, resulting in an anomalous conductance peak. The device does not fully pinch off when the channel is tuned into the topological gap, which is a sign of remnant modes in the channel. These modes are expected from band inversion, while residual bulk conduction associated with the disorder potential may also play a role
BAG3 as a novel prognostic biomarker in kidney renal clear cell carcinoma correlating with immune infiltrates
Abstract Purpose BCL-2-associated athanogene 3 (BAG3) is an anti-apoptotic protein that plays an essential role in the onset and progression of multiple cancer types. However, the clinical significance of BAG3 in kidney renal clear cell carcinoma (KIRC) remains unclear. Methods Using Tumor IMmune Estimation Resource (TIMER), The Cancer Genome Atlas (TCGA), and Gene Expression Omnibus (GEO) database, we explored the expression, prognostic value, and clinical correlations of BAG3 in KIRC. In addition, immunohistochemistry (IHC) of HKH cohort further validated the expression of BAG3 in KIRC and its impact on prognosis. Gene Set Cancer Analysis (GSCA) was utilized to scrutinize the prognostic value of BAG3 methylation. Gene Ontology (GO) term analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene set enrichment analysis (GSEA) were used to identify potential biological functions of BAG3 in KIRC. Single-sample gene set enrichment analysis (ssGSEA) was performed to confirm the correlation between BAG3 expression and immune cell infiltration. Results BAG3 mRNA expression and protein expression were significantly downregulated in KIRC tissues compared to normal kidney tissues, associated with adverse clinicalâpathological factors and poor clinical prognosis. Multivariate Cox regression analysis indicated that low expression of BAG3 was an independent prognostic factor in KIRC patients. GSEA analysis showed that BAG3 is mainly involved in DNA methylation and the immune-related pathways in KIRC. In addition, the expression of BAG3 is closely related to immune cell infiltration and immune cell marker set. Conclusion BAG3 might be a potential therapeutic target and valuable prognostic biomarker of KIRC and is closely related to immune cell infiltration
IRTKS Promotes Insulin Signaling Transduction through Inhibiting SHIP2 Phosphatase Activity
Insulin signaling is mediated by a highly integrated network that controls glucose metabolism, protein synthesis, cell growth, and differentiation. Our previous work indicates that the insulin receptor tyrosine kinase substrate (IRTKS), also known as BAI1-associated protein 2-like 1 (BAIAP2L1), is a novel regulator of insulin network, but the mechanism has not been fully studied. In this work we reveal that IRTKS co-localizes with Src homology (SH2) containing inositol polyphosphate 5-phosphatase-2 (SHIP2), and the SH3 domain of IRTKS directly binds to SHIP2’s catalytic domain INPP5c. IRTKS suppresses SHIP2 phosphatase to convert phosphatidylinositol 3,4,5-triphosphate (PI(3,4,5)P3, PIP3) to phosphatidylinositol (3,4) bisphosphate (PI(3,4)P2). IRTKS-knockout significantly increases PI(3,4)P2 level and decreases cellular PI(3,4,5)P3 content. Interestingly, the interaction between IRTKS and SHIP2 is dynamically regulated by insulin, which feeds back and affects the tyrosine phosphorylation of IRTKS. Furthermore, IRTKS overexpression elevates PIP3, activates the AKT–mTOR signaling pathway, and increases cell proliferation. Thereby, IRTKS not only associates with insulin receptors to activate PI3K but also interacts with SHIP2 to suppress its activity, leading to PIP3 accumulation and the activation of the AKT–mTOR signaling pathway to modulate cell proliferation