Signal Temporal Logic Control Synthesis among Uncontrollable Dynamic Agents with Conformal Prediction

The control of dynamical systems under temporal logic specifications among uncontrollable dynamic agents is challenging due to the agents' a-priori unknown behavior. Existing works have considered the problem where either all agents are controllable, the agent models are deterministic and known, or no safety guarantees are provided. We propose a predictive control synthesis framework that guarantees, with high probability, the satisfaction of signal temporal logic (STL) tasks that are defined over the system and uncontrollable stochastic agents. We use trajectory predictors and conformal prediction to construct probabilistic prediction regions for each uncontrollable agent that are valid over multiple future time steps. Specifically, we reduce conservatism and increase data efficiency compared to existing works by constructing a normalized prediction region over all agents and time steps. We then formulate a worst-case mixed integer program (MIP) that accounts for all agent realizations within the prediction region to obtain control inputs that provably guarantee task satisfaction with high probability. To efficiently solve this MIP, we propose an equivalent MIP program based on KKT conditions of the original one. We illustrate our control synthesis framework on two case studies

A proposal for detecting the spin of a single electron in superfluid helium

The electron bubble in superfluid helium has two degrees of freedom that may offer exceptionally low dissipation: the electron's spin and the bubble's motion. If these degrees of freedom can be read out and controlled with sufficient sensitivity, they would provide a novel platform for realizing a range of quantum technologies and for exploring open questions in the physics of superfluid helium. Here we propose a practical scheme for accomplishing this by trapping an electron bubble inside a superfluid-filled opto-acoustic cavity.Comment: Main text: 5 pages, 5 figures. Supplement: 11 pages, 2 figures, 1 tabl

Dietary exposure assessment of dibutyl phthalate in edible vegetable oil in Shanghai

Objective This paper aim to investigate dibutyl phthalate (DBP) concentration level in edible vegetable oil sold in Shanghai, and to evaluate the dietary exposure risk of local residents. Methods By combining monitoring data of DBP in edible vegetable oil sold in Shanghai from 2015 to 2019 with the dietary consumption data of residents, the dietary exposure of DBP in edible vegetable oil was assessed via point assessment method. Results A total of 1 248 DBP samples in edible vegetable oil were tested from 2015 to 2019, the overall unqualified rate was 3.4% (43/1 248), and the mean concentration was (0.34±2.15) mg/kg. According to the annual statistics, the unqualified rate showed an upward trend of fluctuation and reached 4.4% (13/295) in 2019. According to the statistics of edible vegetable oil varieties, DBP contamination levels in walnut oil, sesame oil and rapeseed oil were relatively serious, with the unqualified rate of 28.6% (6/21), 10.5% (20/190) and 9.2% (8/87), respectively. The mean and 97.5 percentile daily DBP intake from edible vegetable oil in general population were 0.23 and 0.40 μg/kg BW, accounting for 2.3% and 4.0% of tolerable daily intake (TDI, 10 μg/kg BW), respectively. Conclusion The health risk of DBP intake from edible vegetable oil was relatively low and acceptable for Shanghai residents

Effects of precipitation changes on aboveground net primary production and soil respiration in a switchgrass field

Switchgrass (Panicum virgatum L.) is widely selected as a model feedstock for sustainable replacement of fossil fuels and climate change mitigation. However, how climate changes, such as altered precipitation (PPT), will influence switchgrass growth and soil carbon storage potential have not been well investigated. We conducted a two-year PPT manipulation experiment with five treatments: −50%, −33%, +0%, +33%, and +50% of ambient PPT, in an “Alamo” switchgrass field in Nashville, TN. Switchgrass aboveground net primary production (ANPP), leaf gas exchange, and soil respiration (SR) were determined each growing season. Data collected from this study was then used to test whether switchgrass ANPP responds to PPT changes in a double asymmetry pattern as framed by Knapp et al. (2017), and whether it is held true for other ecosystem processes such as SR. Results showed that the wet (+33%, and +50%) treatments had little effects on ANPP and leaf gas exchange compared to the ambient precipitation treatment, regardless of fertilization or not. The −33% treatment did not change ANPP and leaf photosynthesis, but significantly decreased transpiration and enhanced water use efficiency (WUE). Only the −50% treatment significantly decreased ANPP and LAI, without changing leaf photosynthesis. SR generally decreased under the drought treatments and increased under the wet treatments, while there was no significant difference between the two drought treatments or between the two wet treatments. Our results demonstrate that switchgrass ANPP responded in a single negative asymmetry model to PPT changes probably due to relative high PPT in the region. However, even in such a mesic ecosystem, SR responded strongly to PPT changes in an “S” curve model, suggesting that future climate changes may have greater but more complex effects on switchgrass belowground than aboveground processes. The contrasting models for switchgrass ANPP and SR in response to PPT indicate that extreme wet or dry PPT conditions may shift ecosystem from carbon accumulation toward debt, and in turn provide government and policy makers with useful information for sustainable management of switchgrass

Ultra-high strength metal matrix composites (MMCs) with extended ductility manufactured by size-controlled powder and spherical cast tungsten carbide

The main challenge of particle reinforced metal matrix composites (MMCs) is balancing strength and ductility. This research uses type 420 stainless steel and spherical cast tungsten carbide (WC/W2C) with a similar powder size and range as raw powders to manufacture laser powder bed fusion (LPBF) 420 + 5 wt% WC/W2C MMCs. LPBF 420 + 5 wt% WC/W2C MMCs contain austenite, martensite, and W-rich carbides (WC/W2C, FeW3C, M6C, and M7C3) from nanometre to micrometre scale. The well-balanced composition creates a crack-free reaction layer between the reinforced particles and matrix. This reaction layer consists of two distinct layers, depending on the element concentration. The LPBF 420 + 5 wt% WC/W2C MMCs achieved an excellent compressive strength of ∼5.5 GPa and a considerable fracture strain exceeding 50 %. The underlying mechanisms for the improved mechanical properties are discussed, providing further insight to advance the application of MMCs via additive manufacturing

Hepatitis B virus induces G1 phase arrest by regulating cell cycle genes in HepG2.2.15 cells

<p>Abstract</p> <p>Background</p> <p>To investigate the effect of HBV on the proliferative ability of host cells and explore the potential mechanism.</p> <p>Methods</p> <p>MTT, colony formation assay and tumourigenicity in nude mice were performed to investigate the effect of HBV on the proliferative capability of host cells. In order to explore the potential mechanism, cell cycle and apoptosis were analysed. The cell cycle genes controlling the G1/S phase transition were detected by immunohistochemistry, westernblot and RT-PCR.</p> <p>Results</p> <p>HepG2.2.15 cells showed decreased proliferation ability compared to HepG2 cells. G1 phase arrest was the main cause but was not associated with apoptosis. p53, p21 and total retinoblastoma (Rb) were determined to be up-regulated, whereas cyclinE was down-regulated at both the protein and mRNA levels in HepG2.2.15 cells. The phosphorylated Rb in HepG2.2.15 cells was decreased.</p> <p>Conclusions</p> <p>Our results suggested that HBV inhibited the capability of proliferation of HepG2.2.15 cells by regulating cell cycle genes expression and inducing G1 arrest.</p

Hepatitis B virus induces G1 phase arrest by regulating cell cycle genes in HepG2.2.15 cells

<p>Abstract</p> <p>Background</p> <p>To investigate the effect of HBV on the proliferative ability of host cells and explore the potential mechanism.</p> <p>Methods</p> <p>MTT, colony formation assay and tumourigenicity in nude mice were performed to investigate the effect of HBV on the proliferative capability of host cells. In order to explore the potential mechanism, cell cycle and apoptosis were analysed. The cell cycle genes controlling the G1/S phase transition were detected by immunohistochemistry, westernblot and RT-PCR.</p> <p>Results</p> <p>HepG2.2.15 cells showed decreased proliferation ability compared to HepG2 cells. G1 phase arrest was the main cause but was not associated with apoptosis. p53, p21 and total retinoblastoma (Rb) were determined to be up-regulated, whereas cyclinE was down-regulated at both the protein and mRNA levels in HepG2.2.15 cells. The phosphorylated Rb in HepG2.2.15 cells was decreased.</p> <p>Conclusions</p> <p>Our results suggested that HBV inhibited the capability of proliferation of HepG2.2.15 cells by regulating cell cycle genes expression and inducing G1 arrest.</p