25 research outputs found
MimicPlay: Long-Horizon Imitation Learning by Watching Human Play
Imitation learning from human demonstrations is a promising paradigm for
teaching robots manipulation skills in the real world. However, learning
complex long-horizon tasks often requires an unattainable amount of
demonstrations. To reduce the high data requirement, we resort to human play
data - video sequences of people freely interacting with the environment using
their hands. Even with different morphologies, we hypothesize that human play
data contain rich and salient information about physical interactions that can
readily facilitate robot policy learning. Motivated by this, we introduce a
hierarchical learning framework named MimicPlay that learns latent plans from
human play data to guide low-level visuomotor control trained on a small number
of teleoperated demonstrations. With systematic evaluations of 14 long-horizon
manipulation tasks in the real world, we show that MimicPlay outperforms
state-of-the-art imitation learning methods in task success rate,
generalization ability, and robustness to disturbances. Code and videos are
available at https://mimic-play.github.ioComment: 7th Conference on Robot Learning (CoRL 2023 oral presentation
Systematic expression analysis of plasticity-related genes in mouse brain development brings PRG4 into play
Background: Plasticity-related genes (Prgs/PRGs) or lipid phosphate phosphatase-related proteins (LPPRs) comprise five known members, which have been linked to neuronal differentiation processes, such as neurite outgrowth, axonal branching, or dendritic spine formation. PRGs are highly brain-specific and belong to the lipid phosphate phosphatases (LPPs) superfamily, which influence lipid metabolism by dephosphorylation of bioactive lipids. PRGs, however, do not possess enzymatic activity, but modify lipid metabolism in a way that is still under investigation. Results: We analyzed mRNA expression levels of all Prgs during mouse brain development, in the hippocampus, neocortex, olfactory bulbs, and cerebellum. We found different spatio-temporal expression patterns for each of the Prgs, and identified a high expression of the uncharacterized Prg4 throughout brain development. Unlike its close family members PRG3 and PRG5, PRG4 did not induce filopodial outgrowth in non-neuronal cell lines, and does not localize to the plasma membrane of filopodia. Conclusion: We showed PRG4 to be highly expressed in the developing and the adult brain, suggesting that it is of vital importance for normal brain function. Despite its similarities to other family members, it seems not to be involved in changes of cell morphology; instead, it is more likely to be associated with intracellular signaling
Kinematic Simulation and Analysis of Globoidal Indexing Cam
As an important mechanism with intermittent motion, the globoidal indexing cam is always a research hot in the mechanical fields. The working profile of globoidal indexing cam is extremely complicated and undevelopable, which make it quite difficult to be protracted by the conventional drafting method. Aiming at this problem, the working curvilinear equation of the intermittent motion of an indexing cam is derived based on the RPY (Roll-Pitch-Yaw) coordinate transformation method. The 3D model based on the curvilinear equation is built by the Creo2.0 modeling software. The virtual prototype is established based on the ADAMS software, while the kinematics simulation is implemented. The success of virtual simulation verifies the correctness of curvilinear equation. The numerical results, presented and discussed in the paper, indicate that the proposed model is feasible to foresee the kinematic behaviour of an actual system
Kinematic Simulation and Analysis of Globoidal Indexing Cam
As an important mechanism with intermittent motion, the globoidal indexing cam is always a research hot in the mechanical fields. The working profile of globoidal indexing cam is extremely complicated and undevelopable, which make it quite difficult to be protracted by the conventional drafting method. Aiming at this problem, the working curvilinear equation of the intermittent motion of an indexing cam is derived based on the RPY (Roll-Pitch-Yaw) coordinate transformation method. The 3D model based on the curvilinear equation is built by the Creo2.0 modeling software. The virtual prototype is established based on the ADAMS software, while the kinematics simulation is implemented. The success of virtual simulation verifies the correctness of curvilinear equation. The numerical results, presented and discussed in the paper, indicate that the proposed model is feasible to foresee the kinematic behaviour of an actual system
Proteomics of the corpus callosum to identify novel factors involved in hypomyelinated Niemann-Pick Type C disease mice
Abstract Hypomyelination in the central nerves system (CNS) is one of the most obviously pathological features in Niemann-Pick Type C disease (NPC), which is a rare neurodegenerative disorder caused by mutations in the NPC intracellular cholesterol transporter 1 or 2 (Npc1 or Npc2). Npc1 plays key roles in both neurons and oligodendrocytes during myelination, however, the linkage between the disturbed cholesterol transport and inhibited myelination is unrevealed. In this study, mass spectrometry (MS)-based differential quantitative proteomics was applied to compare protein composition in the corpus callosum between wild type (WT) and NPC mice. In total, 3009 proteins from both samples were identified, including myelin structural proteins, neuronal proteins, and astrocyte-specific proteins. In line to hypomyelination, our data revealed downregulation of myelin structural and indispensable proteins in Npc1 mutant mice. Notably, the reduced ceramide synthase 2 (Cers2), UDP glycosyltransferase 8 (Ugt8), and glycolipid transfer protein (Gltp) indicate the altered sphingolipid metabolism in the disease and the involvement of Gltp in myelination. The identification of most reported myelin structural proteins and proteins from other cell types advocates the use of the corpus callosum to investigate proteins in different cell types that regulate myelination
10Â Hz repetitive transcranial magnetic stimulation (rTMS) may improve cognitive function: An exploratory study of schizophrenia patients with auditory hallucinations
Objectives: Cognitive impairment in schizophrenia patients with auditory hallucinations is more prominent compared to those without. Our study aimed to investigate the cognitive improvement effects of 10Â Hz repetitive transcranial magnetic stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) in schizophrenia with auditory hallucinations. Methods: A total of 60 schizophrenic patients with auditory hallucinations in this study were randomly assigned to sham or active group. Both groups received 10Â Hz or sham rTMS targeted in left DLPFC for 20 sessions. The Positive and Negative Syndrome Scale (PANSS), the Auditory Hallucination Rating Scale (AHRS), the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and the Udvalg for Kliniske Under-sogelser (UKU) side effect scale were used to measure psychiatric symptoms, auditory hallucinations, cognition, and side reaction, respectively. Results: Our results indicated that the active group experienced greater improvements in RBANS-total score (PÂ =Â 0.043) and immediate memory subscale score (PÂ =Â 0.001). Additionally, the PANSS-total score, negative and positive subscale score were obviously lower in the active group compared to the sham group (all PÂ <Â 0.050). Furthermore, our study found that the improvement of RBANS-total score was positively associated with the decline of positive factor score, and the improvement of language score in RBANS was positively associated with the reduction in PANSS-total scale, negative and positive subscale score in the real stimulation group (all PÂ <Â 0.050). Conclusion: Our results demonstrated that a four-week intervention of 10Â Hz rTMS over the left DLPFC can improve cognition (particularly immediate memory) among schizophrenia patients with auditory hallucinations. Future studies with larger sample size are needful to verify our preliminary findings
RMC - A Monte Carlo Code for Reactor Core Analysis
A new Monte Carlo transport code RMC has been being developed by Department of Engineering Physics, Tsinghua University, Beijing as a tool for reactor core analysis on high-performance computing platforms. To meet the requirements of reactor analysis, RMC now has such functions as criticality calculation, fixed-source calculation, burnup calculation and kinetics simulations. Some techniques for geometry treatment, new burnup algorithm, source convergence acceleration, massive tally and parallel calculation, and temperature dependent cross sections processing are researched and implemented in RMC to improve the effciency. Validation results of criticality calculation, burnup calculation, source convergence acceleration, tallies performance and parallel performance shown in this paper prove the capabilities of RMC in dealing with reactor analysis problems with good performances
ADAM10 Negatively Regulates Neuronal Differentiation during Spinal Cord Development
<div><p>Members of the ADAM (a disintegrin and metalloprotease) family are involved in embryogenesis and tissue formation via their proteolytic function, cell-cell and cell-matrix interactions. ADAM10 is expressed temporally and spatially in the developing chicken spinal cord, but its function remains elusive. In the present study, we address this question by electroporating ADAM10 specific morpholino antisense oligonucleotides (ADAM10-mo) or dominant-negative ADAM10 (dn-ADAM10) plasmid into the developing chicken spinal cord as well as by in vitro cell culture investigation. Our results show that downregulation of ADAM10 drives precocious differentiation of neural progenitor cells and radial glial cells, resulting in an increase of neurons in the developing spinal cord, even in the prospective ventricular zone. Remarkably, overexpression of the dn-ADAM10 plasmid mutated in the metalloprotease domain (dn-ADAM10-me) mimics the phenotype as found by the ADAM10-mo transfection. Furthermore, in vitro experiments on cultured cells demonstrate that downregulation of ADAM10 decreases the amount of the cleaved intracellular part of Notch1 receptor and its target, and increases the number of βIII-tubulin-positive cells during neural progenitor cell differentiation. Taken together, our data suggest that ADAM10 negatively regulates neuronal differentiation, possibly via its proteolytic effect on the Notch signaling during development of the spinal cord.</p></div
Downregulation of ADAM10 drives differentiation of radial glial cells in the ventral spinal cord.
<p>After electroporation at E4, transverse sections were used for detection at E6. The transfected cells are marked by green fluorescence and the control morpholinos (Fluo-m) and the untransfected side (left side) serve as controls. The immune reactive cells are stained by red. Cell nuclei are labeled by DAPI (blue). Immunohistochemistry was performed in adjacent sections with antibodies against Nestin (A–H) and vimentin (3CB2; I–M), respectively. Arrows in A–D indicate transfected regions (green) and in E–K the inhibition of nestin (E–H) and vimentin (I–K) in the transfected region. Noted that no change of viementin expression in the transfected region above the floor plate is found (arrows in L, M). Scale bar, 200 µm in (A) for (A–K).</p