Pre-training Contextualized World Models with In-the-wild Videos for Reinforcement Learning

Unsupervised pre-training methods utilizing large and diverse datasets have achieved tremendous success across a range of domains. Recent work has investigated such unsupervised pre-training methods for model-based reinforcement learning (MBRL) but is limited to domain-specific or simulated data. In this paper, we study the problem of pre-training world models with abundant in-the-wild videos for efficient learning of downstream visual control tasks. However, in-the-wild videos are complicated with various contextual factors, such as intricate backgrounds and textured appearance, which precludes a world model from extracting shared world knowledge to generalize better. To tackle this issue, we introduce Contextualized World Models (ContextWM) that explicitly model both the context and dynamics to overcome the complexity and diversity of in-the-wild videos and facilitate knowledge transfer between distinct scenes. Specifically, a contextualized extension of the latent dynamics model is elaborately realized by incorporating a context encoder to retain contextual information and empower the image decoder, which allows the latent dynamics model to concentrate on essential temporal variations. Our experiments show that in-the-wild video pre-training equipped with ContextWM can significantly improve the sample-efficiency of MBRL in various domains, including robotic manipulation, locomotion, and autonomous driving

Impact of sarcopenia on postoperative pulmonary complications after gastric cancer surgery: A retrospective cohort study

BackgroundFew studies have investigated the relationship between sarcopenia and postoperative pulmonary complications (PPCs) after gastric cancer surgery. This study aimed to explore the impact of sarcopenia on PPCs in patients who had undergone gastric cancer surgery.MethodsWe included patients who underwent a transabdominal radical gastrectomy between June 2016 and October 2020. Patients were divided into two groups according to the median prevalence rate of lumbar triplane skeletal muscle index (L3 SMI): sarcopenia group (≤37.5% percentile in male and female group) and non-sarcopenia group (>37.5% percentile in male and female group). Baseline characteristics, intraoperative and postoperative conditions, pulmonary complications, and overall complications were compared between the two groups. The primary outcome was the incidence of PPCs. The secondary outcomes were overall postoperative complications and length of stay (LOS).ResultsAmong the 143 patients included, 50 had sarcopenia and 93 had not. Compared to the non-sarcopenia group, the sarcopenia group had a higher the incidence of PPCs (22.0% vs. 8.6%, P = 0.024). The incidence of overall postoperative complications in the sarcopenia group was higher than that in the non-sarcopenia group (36.00% vs. 20.43%, P = 0.043). There was no significant difference in the LOS between the two groups.ConclusionsOur research indicates that sarcopenia, preoperative comorbidities, and longer duration of intraoperative oxygen saturation <95% were risk factors for PPCs. Sarcopenia is an independent risk factor for postoperative complications. Given that our results provided a correlation rather than causation, future prospective randomized trials are needed to confirm the relationship between sarcopenia and prognosis

Growth, Gas Exchange, and Mineral Nutrients of Ornamental Grasses Irrigated with Saline Water

Ornamental grasses are commonly used in urban landscapes in Utah and the Intermountain West of the United States. The relative salt tolerance of Eragrostis spectabilis (Pursh) Steud. (purple love grass), Miscanthus sinensis Andersson ‘Gracillimus’ (maiden grass), Panicum virgatum L. ‘Northwind’ (switchgrass), and Schizachyrium scoparium (Michx.) Nash (little bluestem) were evaluated in a greenhouse. Plants were irrigated with a nutrient solution at an electrical conductivity (EC) of 1.2 dS·m–1 (control), or saline solution at an EC of 5.0 or 10.0 dS·m–1. At harvest (65 days after the initiation of treatment), P. virgatum and S. scoparium exhibited no foliar salt damage, and E. spectabilis and M. sinensis had minimal foliar salt damage when irrigated with saline solution at an EC of 5.0 dS·m–1. At an EC of 10.0 dS·m–1, P. virgatum and S. scoparium still had no foliar salt damage, but E. spectabilis and M. sinensis displayed slight foliar salt damage, with visual scores greater than 3 (0 = dead; 5 = excellent). Compared with the control, saline solution at an EC of 5.0 and 10.0 dS·m–1 reduced the shoot dry weight of all ornamental grasses by 25% and 46%, respectively. The leaf sodium (Na+) concentration of E. spectabilis, M. sinensis, P. virgatum, and S. scoparium irrigated with saline solution at an EC of 10.0 dS·m–1 increased 14.3, 52.6, 5.3, and 1.7 times, respectively, and the chloride (Cl–) concentration increased by 9.4, 11.1, 2.8, and 2.7 times, respectively. As a result of the salt-induced water deficit, plant height, leaf area, number of inflorescences and tillers, net photosynthesis rate (Pn), stomatal conductance (gS), and transpiration rate of four tested ornamental grasses decreased to some extent. Although high Na+ and Cl– accumulated in the leaf tissue, all ornamental grass species still had a good visual quality, with average visual scores greater than 3. In conclusion, all ornamental grasses showed a very strong tolerance to the salinity levels used in this research

Construction and Properties of Polyvinyl Alcohol/Chitosan Electrospun Film Loaded with Catechins

In order to develop a new bio-based food packaging material and improve the bioavailability of natural phenolic compounds, an electrospinning film loaded with Catechin was prepared by electrospinning using catechin (CT), polyvinyl alcohol (PVA) and chitosan (CS) as substrates. The microstructure and diameter distribution of the electrospun films were analyzed by scanning electron microscopy. The interaction between CT and film forming substrate was studied by Fourier infrared spectroscopy, X-ray diffraction and thermal analysis. The effects of CT addition on the physical and chemical properties of the electrospun film were investigated by taking the mechanical properties, gas permeability and antioxidant activity of the film as parameters. Finally, the preservation effect of electrospun film was analyzed by sensory evaluation, water loss rate and titrable acid content. The results showed that the intermolecular hydrogen bond was formed between CT and CS, and the hydrophobic property was improved. When the concentration of CT was 0.8%, the comprehensive performance of the electrospun film was the best. It had good morphology, dense structure and good thermal stability. At this point, the tensile strength and elongation at break reached the maximum, which were 12.89 MPa and 62.45% respectively. The water solubility, water vapor transmittance and CO2 transmittance were the lowest, which were 29.51%, 0.1532 g·mm·(m2·h·kPa)−1 and 5.9 g·(m2·h)−1, respectively. Besides, the scavenging rate of DPPH free radical also reached the maximum value, which was 71.02%. Moreover, the electrospun membrane had sustained release effect. When the CT concentration was 0.8%, its cumulative release rate was the highest. The preservation research results showed that the electrospun film could effectively delay the deterioration of strawberry, and the electrospun film with 0.8% CT concentration had the best preservation effect. In conclusion, the electrospun film with 0.8% CT concentration had the best comprehensive performance, and it had certain antioxidation and fresh-keeping ability

Variety-dependent Physiologic and Biochemical Effects of Copper Nano Particles on Rosie and Green Bok Choy (Brassica rapa) Phenotypes

The effects of Cu-based nanoparticles (NPs) in bok choy (Brassica rapa subsp. chinensis) are unknown. In this study, Rosie and Green, two varieties of bok choy, with different anthocyanin content, were cultivated for 70 days in soil amended with copper oxide nanoparticles (nano CuO), bulk copper oxide (bulk CuO) and copper chloride (CuCl2) at 75, 150, 300 and 600 mg Cu/kg soil. Cu and essential elements in tissues, and relative chlorophyll content, were determined. In both varieties, nano CuO treatments caused significantly more Cu uptake in roots and shoots, compared with bulk CuO and ion CuCl2 (p ≤ 0.05). Additionally, under the same concentration treatments, Cu uptake in Rosie was higher than in Green. At all concentration the copper compounds reduced the biomass of both Rosie and Green bok choy. At 150 mg/kg, nano CuO reduced K by 45% in Rosie leaves, while at 600 mg/kg reduced it by 41% in Green root, with respect to each control (p ≤ 0.05). Fe accumulation in roots was significantly reduced in the range of 18-50% in both Rosie and Green plants, compared with control (p ≤ 0.05). Similarly, root P was also significantly decreased up to 70% with Cu-based compounds (p ≤ 0.05), with respect to control. Total sugar, starch and protein content were not significantly altered by any of the treatments, except for bulk CuO at 150, 300, and 600 mg/kg, which increased total sugar in Rosie leaves by 56.87%, 51.89% and 49.46%, respectively, compared with control ( p ≤ 0.05). Rosie bok choy, with significantly higher anthocyanin content, accumulated more Cu in both root and leaf and the growth of plants was inhibited more than Green bok choy significantly (p ≤ 0.05). Results showed that nano CuO was more toxic to bok choy plants than bulk CuO, especially at higher concentrations (300 and 600 mg/kg)

Effects of coated/uncoated copper-based nanoparticles and compounds on rice (oryza sativa) and soybean (glycine max) plants

Engineering nanoparticles (ENPs) have been widely used in industry due to their promising chemical, physical, electrical, magnetic, optical, and electronic properties. Copper-based ENPs are used as gas sensors, catalysts, semiconductors and agricultural products, among others. Because of their antifungal and antibacterial properties, they are used in agriculture as insecticides, herbicides and antifungal agents. Due to their mass production and use, ENPs are likely to be ubiquitous in our in the environment in the near future. In addition, metal nanoparticles are usually coated with organic compounds to enhance the properties of the nanoparticles. Previous studies have shown that copper-based ENPs can interfere with plant physiology and development. However, to our knowledge, very little work has been done on the effects of Cu-based NPs in rice (Oryza sativa) and soybean (Glycine max) plants. Rice is a very important crop widely consumed across cultures as a source of nutrition and caloric intake. Soybean is a worldwide consumed plant, which is very rich in protein. This research project is aimed to understand the effects of copper-based compounds on rice and soybean plants at full life cycle. It also analyzes the effects of surface coated copper based nanoproducts on soybean plants. The investigation included two parts. The first part consisted of culturing two type of rice plants (cultivated and weedy) until reaching physiological maturity (120 days), in soil amended with nano CuO (nCuO), bulk CuO (bCuO), and ionic copper (CuSO4) at 0, 75, 150, 300, and 600 mg/kg. Cu translocation, essential element accumulation, yield, sugar, starch, protein content, and the expression of auxin associated genes in grains were determined. The grains of weedy and cultivated rice were differentially impacted by CuO-based compounds. At ≥ 300 mg/kg, nCuO and bCuO treated rice had no grain production. Treatment at 75 mg/kg significantly decreased grain yield as compared to control with the order: bCuO (by 88.7%) \u3e CuSO4 (by 47.2%) ~ nCuO (by 38.3% only in cultivated rice). These findings demonstrate a cultivar-specific and concentration-dependent response of rice to nCuO. A potential use of nCuO at 75 and 150 mg/kg in cultivar-dependent delivery system was suggested based on enhanced grain nutritional quality, although the yield was compromised. The second part encompassed the evaluation of the effects that citric acid coated copper oxide nanoparticles (CuO-CA NPs) and their application process (foliar exposure, soil exposure) have on the growth and physiology of soybean (Glycine max). This part was conducted in two methods of application, soil exposure and foliar exposure. Seedlings (14-day-old) were transplanted into soil amended with 0 (control), 75, and 300 mg Cu/kg or foliar applied Cu-NPs suspensions. After nanomaterials exposure via foliar and soil application, Cu was detected in the roots, leaves, stem, pod, and seed of the plant. Cu was distributed differently depending on plant organs and surface coating. Foliar application of CuO NPs and CuO-CA NPs increased the soybean yield by 169.47% and 170.07%, respectively. In contrast, the ionic Cu treatment and soil exposure did not affect soybean yield. Our results show that CA coating changed the CuO NPs toxicity in soybean. This research provides direct evidence for the positive effects of CuO-CA NPs on soybean, including accumulation and transfer of the particles, which may have significant implications concerning the risk NPs pose to food safety and security

Deformation Characteristics and Microstructure Analysis of Aluminum Alloy Component with Complex Shape by Cold Orbital Forming

This work aimed to study the deformation characteristics and microstructure of AA6063 aluminum alloy component with complex shape manufactured by cold orbital forming processing. The material flowing behavior was analyzed by Finite Element (FE) simulation and forming experiments were carried out using bar blank with different lengths. The microstructure of the boss zone cut from the formed samples was observed using scanning electron microscopy (SEM) and electron back-scatter diffraction (EBSD). FE simulation and experiment results both showed the aluminum base can be formed using cold orbital forming process. The distributions of the effective strain of the component with different blank lengths were almost the same, and the effective strain was bigger at the boss and the flash as the forming finished. The material flow is complex, especially in the boss, and the folding defect was observed at the root of the boss. The distribution of Mg2Si strengthening precipitate is more homogeneous in the matrix, has a different shape, and shows directivity at different position of boss zone. The grains are elongated, and the extent is different at different positions of the boss zone after cold orbital forming, and the crystal orientation discrepancy is smaller in the component main body and bigger in the boss zone. Subsequent forming process and blank optimization need to be further researched to improve forming quality

Access time oracle for planar graphs

The study of urban networks reveals that the accessibility of important city objects for the vehicle traffic and pedestrians is significantly correlated to the popularity, micro-criminality, micro-economic vitality, and social liveability of the city, and is always the chief factor in regulating the growth and expansion of the city. The accessibility between different components of an urban structure are frequently measured along the streets and routes considered as edges of a planar graph, while the traffic ultimate destination points and street junctions are treated as vertices. For estimation of the accessibility of destination vertex j from vertex i through urban networks, in particular, the random walks are used to calculate the expected distance a random walker starting from i makes before j is visited (known as access time). The state-of-the-art of access time computation is costly in large planar graphs since it involves matrix operation over entire graph. The time complexity is O(n^{2.376}) where n is the number of vertices in the planar graph. To enable efficient access time query answering in large planar graphs, this work proposes the first access time oracle which is based on the proposed access time decomposition and reconstruction scheme. The oracle is a hierarchical data structure with deliberate design on the relationships between different hierarchical levels. The storage requirement of the proposed oracle is O(n^{frac{4}{3}}\log \log n) and the access time query response time is O(n^{frac{2}{3}}) . The extensive tests on a number of large real-world road networks (with up to about 2 million vertices) have verified the superiority of the proposed oracle

Hemiboea albiflora, a new species of Gesneriaceae from Guizhou, China

Hemiboea albiflora X.G.Xiang, Z.Y.Guo & Z.W.Wu, sp. nov., a new species of Gesneriaceae from Guizhou, China, is described and illustrated. This species was previously listed informally as a variety of H. gamosepala, but it differs significantly from H. gamosepala by its 5-parted calyx from the base, longer peduncle, white corolla and longer pistil. Based on recent extensive observations, this new species is similar to H. cavaleriei var. paucinervis and H. subcapitata but differs from them by its longer petiole, larger involucre, white corolla and longer staminal filaments. The conservation status of this species is considered to be “Vulnerable” (VU) according to the IUCN Red List Categories and Criteria

Hemiboea albiflora, a new species of Gesneriaceae from Guizhou, China

Hemiboea albiflora X.G.Xiang, Z.Y.Guo & Z.W.Wu, sp. nov., a new species of Gesneriaceae from Guizhou, China, is described and illustrated. This species was previously listed informally as a variety of H. gamosepala, but it differs significantly from H. gamosepala by its 5-parted calyx from the base, longer peduncle, white corolla and longer pistil. Based on recent extensive observations, this new species is similar to H. cavaleriei var. paucinervis and H. subcapitata but differs from them by its longer petiole, larger involucre, white corolla and longer staminal filaments. The conservation status of this species is considered to be Vulnerable (VU) according to the IUCN Red List Categories and Criteria