Cell Pattern in Adult Human Corneal Endothelium

A review of the current data on the cell density of normal adult human endothelial cells was carried out in order to establish some common parameters appearing in the different considered populations. From the analysis of cell growth patterns, it is inferred that the cell aging rate is similar for each of the different considered populations. Also, the morphology, the cell distribution and the tendency to hexagonallity are studied. The results are consistent with the hypothesis that this phenomenon is analogous with cell behavior in other structures such as dry foams and grains in polycrystalline materials. Therefore, its driving force may be controlled by the surface tension and the mobility of the boundaries

Open X-Embodiment:Robotic learning datasets and RT-X models

Large, high-capacity models trained on diverse datasets have shown remarkable successes on efficiently tackling downstream applications. In domains from NLP to Computer Vision, this has led to a consolidation of pretrained models, with general pretrained backbones serving as a starting point for many applications. Can such a consolidation happen in robotics? Conventionally, robotic learning methods train a separate model for every application, every robot, and even every environment. Can we instead train "generalist" X-robot policy that can be adapted efficiently to new robots, tasks, and environments? In this paper, we provide datasets in standardized data formats and models to make it possible to explore this possibility in the context of robotic manipulation, alongside experimental results that provide an example of effective X-robot policies. We assemble a dataset from 22 different robots collected through a collaboration between 21 institutions, demonstrating 527 skills (160266 tasks). We show that a high-capacity model trained on this data, which we call RT-X, exhibits positive transfer and improves the capabilities of multiple robots by leveraging experience from other platforms. The project website is robotics-transformer-x.github.io

The Chip-Level and Package-Level Degradation of Cascode GaN Device Under Repetitive Power Cycling Stress

In this work, the electrical characteristics’ failure due to the chip-level damage and its relationship with the package-level degradation have been investigated for the Cascode GaN device under long-term repetitive power cycling test (PCT). At first, it is found that, the device’s transfer characteristics and threshold voltages have not changed until 8000-cycle PCT, while its on-state current decreases as the increases in cycles number. Meanwhile, the device’s gate-to-source leakage have not changed even after 8000-cycle PCT, but there is a significant increase in drain-to-source leakage. The above phenomenon has been attributed to the structural damage in the gate region of GaN HEMT, which has been verified by TCAD simulation and EMMI analysis. Then, it is found that the device’s thermal resistance is increased after the repetitive power cycling test, which is due to the package-level degradation. The increased thermal resistance will lead to the increase of heat accumulation, which has been verified by TCAD simulation, subsequently leading to the chip-level damage and electrical performance failure for Cascode GaN device. The relevant results may help to improve the long-term reliability of Cascode GaN device