Learning to Use Chopsticks in Diverse Gripping Styles

Learning dexterous manipulation skills is a long-standing challenge in computer graphics and robotics, especially when the task involves complex and delicate interactions between the hands, tools and objects. In this paper, we focus on chopsticks-based object relocation tasks, which are common yet demanding. The key to successful chopsticks skills is steady gripping of the sticks that also supports delicate maneuvers. We automatically discover physically valid chopsticks holding poses by Bayesian Optimization (BO) and Deep Reinforcement Learning (DRL), which works for multiple gripping styles and hand morphologies without the need of example data. Given as input the discovered gripping poses and desired objects to be moved, we build physics-based hand controllers to accomplish relocation tasks in two stages. First, kinematic trajectories are synthesized for the chopsticks and hand in a motion planning stage. The key components of our motion planner include a grasping model to select suitable chopsticks configurations for grasping the object, and a trajectory optimization module to generate collision-free chopsticks trajectories. Then we train physics-based hand controllers through DRL again to track the desired kinematic trajectories produced by the motion planner. We demonstrate the capabilities of our framework by relocating objects of various shapes and sizes, in diverse gripping styles and holding positions for multiple hand morphologies. Our system achieves faster learning speed and better control robustness, when compared to vanilla systems that attempt to learn chopstick-based skills without a gripping pose optimization module and/or without a kinematic motion planner

Measuring Access to Medicines: A Survey of Prices, Availability and Affordability in Shaanxi Province of China

Objective: To measure the prices and availability of selected medicines in Shaanxi Province after the implementation of new healthcare reform in 2009. Methods: Data on the prices and availability of 47 medicines were collected from 50 public and 36 private sector medicine outlets in six regions of Shaanxi Province, Western China using a standardized methodology developed by the World Health Organization and Health Action International from September to October 2010. Medicine prices were compared with international reference prices to obtain a median price ratio. Affordability was measured as the number of days’ wages required for the lowest-paid unskilled government worker to purchase standard treatments for common conditions. Findings: The mean availabilities of originator brands and lowest-priced generics were 8.9% and 26.5% in the public sector, and 18.1% and 43.6% in the private sector, respectively. The public sector procured generics and originator brands at median price ratios of 0.75 and 8.49, respectively, while patients paid 0.97 and 10.16. Final patient prices for lowest-priced generics and originator brands in the private sector were about 1.53 and 8.36 times their international retail prices, respectively. Public sector vendors applied high markups of 30.4% to generics, and 19.6% to originator brands. In the private sector, originator brands cost 390.7% more, on average, than their generic equivalents. Generic medicines were priced 17.3% higher in the private sector than the public sector. The lowest-paid government worker would need 0.1 day’s wages to purchase captopril for lowest-priced generics from private sector, while 6.6 days’ wages for losartan. For originator brands, the costs rise to 1.2 days’ wages for salbutamol inhaler and 15.6 days’ wages for omeprazole. Conclusions: The prices, availability and affordability of medicines in China should be improved to ensure equitable access to basic medical treatments, especially for the poor. This requires multi-faceted interventions, as well as the review and refocusing of policies, regulations and educational interventions

Kinematic Design of a Seven-Bar Linkage with Optimized Centrodes for Pure-Rolling Cutting

A novel method for designing a seven-bar linkage based on the optimization of centrodes is presented in this paper. The proposed method is applied to the design of a pure-rolling cutting mechanism, wherein close interrelation between the contacting lines and centrodes of two pure-rolling bodies is formulated and the genetic optimization algorithm is adopted for the dimensional synthesis of the mechanism. The optimization is conducted to minimize the error between mechanism centrodes and the expected trajectories, subject to the design requirements of the opening distance, the maximum amount of overlap error, and peak value of shearing force. An optimal solution is obtained and the analysis results show that the horizontal slipping and standard deviation of the lowest moving points of the upper shear blade have been reduced by 78.0% and 80.1% and the peak value of shear stress decreases by 29%, which indicate better cutting performance and long service life

Direct Manipulation of quantum entanglement from the non-Hermitian nature of light-matter interaction

Biphoton process is an essential benchmark for quantum information science and technologies, while great efforts have been made to improve the coherence of the system for better quantum correlations. Nevertheless, we find that the non-Hermitian features induced by the atomic quantum interference could be well employed for the direct control of entanglement. We report the demonstration of exceptional point (EP) in biphotons by measuring the light-atom interaction as a natural non-Hermitian system, in which the electromagnetically induced transparency regime provides a powerful mechanism to precisely tune the non-Hermitian coupling strength. Such biphoton correlation is tuned within an unprecedented large range from Rabi oscillation to antibunching-exponential-decay, also indicating high-dimensional entanglement within the strong and weak light-matter coupling regimes. The EP at the transition point between the two regimes is clearly observed with the biphoton quantum correlation measurements, exhibiting a single exponential decay and manifesting the coalesced single eigenstate. Our results provide a unique method to realize the controllability of natural non-Hermitian processes without the assistance of artificial photonic structures, and paves the way for quantum control by manipulating the non-Hermitian features of the light-matter interaction

The order of expression is a key factor in the production of active transglutaminase in Escherichia coli by co-expression with its pro-peptide

<p>Abstract</p> <p>Background</p> <p><it>Streptomyces </it>transglutaminase (TGase) is naturally synthesized as zymogen (pro-TGase), which is then processed to produce active enzyme by the removal of its N-terminal pro-peptide. This pro-peptide is found to be essential for overexpression of soluble TGase in <it>E. coli</it>. However, expression of pro-TGase by <it>E. coli </it>requires protease-mediated activation <it>in vitro</it>. In this study, we developed a novel co- expression method for the direct production of active TGase in <it>E. coli</it>.</p> <p>Results</p> <p>A TGase from <it>S. hygroscopicus </it>was expressed in <it>E. coli </it>only after fusing with the pelB signal peptide, but fusion with the signal peptide induced insoluble enzyme. Therefore, alternative protocol was designed by co-expressing the TGase and its pro-peptide as independent polypeptides under a single T7 promoter using vector pET-22b(+). Although the pro-peptide was co-expressed, the TGase fused without the signal peptide was undetectable in both soluble and insoluble fractions of the recombinant cells. Similarly, when both genes were expressed in the order of the TGase and the pro-peptide, the solubility of TGase fused with the signal peptide was not improved by the co-expression with its pro-peptide. Interestingly, active TGase was only produced by the cells in which the pro-peptide and the TGase were fused with the signal peptide and sequentially expressed. The purified recombinant and native TGase shared the similar catalytic properties.</p> <p>Conclusions</p> <p>Our results indicated that the pro-peptide can assist correct folding of the TGase inter-molecularly in <it>E. coli</it>, and expression of pro-peptide prior to that of TGase was essential for the production of active TGase. The co-expression strategy based on optimizing the order of gene expression could be useful for the expression of other functional proteins that are synthesized as a precursor.</p

Synthesis of Biotin-Modified Galactosylated Chitosan Nanoparticles and Their Characteristics in Vitro and in Vivo

Background/Aims: Our previous study found that a nanoparticle drug delivery system that operates as a drug carrier and controlled release system not only improves the efficacy of the drugs but also reduces their side effects. However, this system could not efficiently target hepatoma cells. The aim of this study was to synthesize biotin-modified galactosylated chitosan nanoparticles (Bio-GC) and evaluate their characteristics in vitro and in vivo. Methods: Bio-GC nanomaterials were synthesized, and confirmed by fourier transform infrared spectroscopy (FT-IR) and hydrogen-1 nuclear magnetic resonance (1H-NMR). The liver position and cancer target property of Bio-GC nanoparticles in vitro and in vivo was tested by confocal laser and small animal imaging system. The characteristics of Bio-GC/5-fluorouracil (5-FU) nanoparticles in vitro and in vivo were explored by cell proliferation, migration and cytotoxicity test, or by animal experiment. Results: Bio-GC nanoparticles were synthesized with biodegradable chitosan as the nanomaterial skeleton with biotin and galactose grafts. Bio-GC was confirmed by FT-IR and 1H-NMR. Bio-GC/5-FU nanoparticles were synthesized according to the optimal mass ratio for Bio-GC/5-FU (1: 4) and had a mean particle size of 81.1 nm, zeta potential of +39.2 mV, and drug loading capacity of 8.98%. Bio-GC/5-FU nanoparticles had sustained release properties (rapid, steady, and slow release phases). Bio-GC nanoparticles targeted liver and liver cancer cell in vitro and in vivo, and this was confirmed by confocal laser scanning and small animal imaging system. Compared with GC/5-FU nanoparticles, Bio-GC/5-FU nanoparticles showed more specific cytotoxic activity in a dose- and time-dependent manner and a more obvious inhibitory effect on the migration of liver cancer cells. In addition, Bio-GC/5-FU nanoparticles significantly prolonged the survival time of mice in orthotopic liver cancer transplantation model compared with other 5-FU nanoparticles or 5-FU alone. Bio-GC (0.64%) nanomaterial had no obvious cytotoxic effects on cells; thus, the concentration of Bio-GC/5-FU nanoparticles used was only 0.04% and showed no toxic effects on the cells. Conclusion: Bio-GC is a liver- and cancer-targeting nanomaterial. Bio-GC/5-FU nanoparticles as drug carriers have stronger inhibitory effects on the proliferation and migration of liver cancer cells compared with 5-FU in vitro and in vivo