课程文献中心 更多>>

关键词： antioxidant capacity   Folin-Ciocalteu   Fruit wine   non-phenolic antioxidants   sulphite   total phenolics  

摘要： The Folin-Ciocalteu reagent (FCR) assay is a reliable and robust, in vitro measure of antioxidant capacity (AOC) of foods but in winemaking its use has generally been confined to measuring total phenolics. However, the contributions of non-phenolics and sulphites, and total AOC are also of interest for winemaking process control and human health functionality. Accordingly, we adapted the FCR assay and evaluated it with a range of wines made from grapes and other fruits, viz. peach, Chinese quince, blueberry, bayberry and red dragon fruit. The novel protocol avoided recognised interferences and revealed a wide variation among the wines in the contributions of phenolics, non-phenolics and sulphites to their total AOC. Of the fruit-derived antioxidants, phenolics accounted for 67.7-98.9% and non-phenolics, 1.0-26.0% of the AOC, respectively. Direct reaction of sulphites with FCR accounted for 0.1-10.6% of the AOC.

关键词： Encoding   Optimization   Search problems   Statistics   Sociology   Decoding   Traveling salesman problems   Differential evolution (DE)   linear ordering problem (LOP)   random key (RK) encoding   search space analysis   traveling salesman problem (TSP)  

摘要： Differential evolution is a powerful nature-inspired real-parameter optimization algorithm that has been successfully used to solve a number of hard optimization problems. It has been used to tackle both continuous and discrete optimization problems. The application of a continuous method to discrete problems involves several challenges, including solution representation and search space-solution space mapping. In this work, we study random key encoding, a popular encoding scheme that is used to represent permutations in high-dimensional continuous spaces. We analyze the search space it constitutes, study its structure and properties, and introduce two novel modifications of the encoding. We investigate the proposed encoding strategies in the context of four variants of the differential evolution algorithm and demonstrate their usefulness for two widespread permutation problems: 1) the linear ordering problem and 2) the traveling salesman problem.

关键词： MMC-HVDC   Frequency dependent characteristics   Metallic return   DC fault   Travelling wave differential protection  

摘要： With the increase of voltage level and transmission capacity, the symmetric bipolar modular multilevel converter based high voltage direct current (MMC-HVDC) grid has become popular in actual projects. Due to the DC fault must be cleared within the timeframe of milliseconds, fast and reliable identification of faulty line is a key issue. The grounding method of HVDC grid and the frequency dependent characteristics of transmission line influence the fault characteristics are rarely taken consideration. To make up for the insufficiency, a reverse travelling wave differential protection scheme is proposed in this paper. Based on the grounding mode of metallic return, the compound sequence boundary conditions under different DC faults are derived first. Then, the travelling wave theory based on Marti frequency dependent model is analysed, and the reverse travelling wave differential value is calculated. Based on the analysis, the protection strategy of different DC faults is established. The proposed protection scheme can meet the rapidity requirements, with low sampling frequency and easy setting. The effectiveness is verified by PSCAD/EMTDC, and extensive simulation results are carried out to verify the advantages in fault resistance tolerance and anti-interference capability.

关键词： Decellularized ECM   SCG neurons   Neurite morphology   Growth cone   Fibronectin  

摘要： The extracellular matrix (ECM) plays a critical role in development, homeostasis, and regeneration of tissue structures and functions. Cell interactions with the ECM are dynamic and cells respond to ECM remodeling by changes in morphology and motility. During nerve regeneration, the ECM facilitates neurite outgrowth and guides axons with target specificity. Decellularized ECMs retain structural, biochemical, and biomechanical cues of native ECM and have the potential to replace damaged matrix to support cell activities during tissue repair. To determine the ECM components that contribute to nerve regeneration, we analyzed neuron-ECM interactions on two types of decellularized ECM. One matrix was composed primarily of fibronectin (FN) fibrils, and the other FN-rich ECM also contained significant numbers of type I collagen (COL I) fibrils. Using primary neurons dissociated from superior cervical ganglion (SCG) explants, we found that neurites were extended on both matrices without a significant difference in average neurite length after 24 h. The most distinctive features of neurites on the FN matrix were numerous short actin-filled protrusions and longer branches extending from neurite shafts. Very few protrusions and branches were detected on FN-COL matrix. Growth cone morphologies also differed with mostly filopodial growth cones on FN matrix whereas on FN-COL matrix, equivalent numbers of filopodial and slender growth cones were formed. Our work provides new information about how changes in major components of the ECM during tissue repair modulate neuron and growth cone morphologies and helps to define the contributions of neuron-ECM interactions to nerve development and regeneration.

关键词： mental health   Medicare   prescription drugs   cost-sharing   deductibles and coinsurance   insurance  

摘要： Objective: The objective of this study was to study how changes in insurance benefit design affect medication use of older adults with mental disorders. Data Sources: US Medicare claims data from 2007 to 2018. Study Design: Exploiting the gradual elimination of the Medicare prescription drug coverage gap beginning in 2011, we examine the effects on medication use and out-of-pocket spending by drug type with a difference-in-differences approach. We identify subpopulations by mental disorder and compare the estimates across mental health groups and to the general Medicare population. Principal Findings: Closing the gap substantially reduced individuals' out-of-pocket spending, and the reduction was larger for those with more severe mental disorders. The policy led to a statistically significant increase in branded drugs used for the Medicare population (0.91;P<0.01;12.12% increase), beneficiaries with severe mental disorders (2.71;P<0.01;11.13% increase), and common mental disorders (2.63;P<0.01;11.62% increase), whereas such effect for beneficiaries with Alzheimer disease and dementia (AD) is substantially smaller (0.44;P<0.01;1.83% increase). In contrast, the policy decreased generic drugs used by about 3%-5% for all groups. Overall, beneficiaries without mental health illness have a statistically significant increase in total medication use (2.05%) following the coverage gap closure, while all 3 mental health groups have either no statistically significant changes or a small reduction in total mediation use (AD, -1.26%). Conclusions: Patients' responses to price changes vary across mental disorders and by drug type. The impact on branded drug utilization among those with AD is particularly small. Our findings suggest that lowering medication costs has differential impacts across diseases and may not be sufficient to improve adherence for all conditions, in particular those with severe mental health disorders such as AD.

关键词： Iron   Games   Interconnected systems   Observers   Bidirectional control   Fault tolerant systems   Fault tolerance   Fault estimation (FE)   fault-tolerant control (FTC)   graphical game   interconnected systems   Stackelberg differential game  

摘要： This article addresses the distributed optimal fault estimation (FE) and fault-tolerant control (FTC) issues under the bidirectional interaction between a possibly faulty interconnected system and its associated diagnostic interconnected observer. The proposed methodology is based on a framework, named Stackelberg differential graphical game, in which the interconnected observer and its corresponding interconnected system are formulated as two graphical games, and they, respectively, play the role of the follower and leader to make sequential decisions of the FE and the FTC. Such a framework allows us to fully reveal the property of the bidirectional interaction, based on which a distributed optimal FE and FTC scheme is developed. Moreover, a new concept named interactive Stackelberg equilibrium is proposed, where, to reach this equilibrium, an auxiliary controller is suitably designed for each subobserver. In this way, this auxiliary controller can cooperate with other auxiliary controllers of subobservers, and noncooperate with controllers of subsystems, which helps to achieve the distributed optimal FE and FTC goals.

关键词： Polarization differential imaging   Underwater image restoration   Periodic integration   Texture enhancement   Noise suppression  

摘要： Underwater image restoration is extensively used in many applications, such as ocean exploration and underwater rescue. With the development of polarization imaging technology, polarization differential imaging (PDI) has gradually become one of the most effective tools for image restoration in the underwater environment. To eliminate the interferences of inconsistent polarization direction and image noise in conventional PDI systems, we propose a new underwater image restoration method based on the periodic integration of polarization images. The method replaces one or two pairs of orthogonal polarization images with the integration of a series of polarization images in PDI system to achieve underwater image restoration. Firstly, we captured a series of polarization images in different polarization directions during a complete variation cycle of image intensity. Then, these polarization images are accumulated together, and the result is approximately regarded as the intensity integration of polarization light in the dimension of polarization direction. Finally, we can calculate the polarization degree of each pixel and obtain a clear polarization differential image. Compared with the existing PDI methods based on one or two pairs of orthogonal polarization images, both qualitative and quantitative experimental results show that the proposed method has better performance in texture enhancement and noise suppression.

关键词： calicivirus   Akt activation   norovirus   assembly   egress   noroviruses  

摘要： Akt (protein kinase B) is a key signaling protein in eukaryotic cells that controls many cellular processes, such as glucose metabolism and cell proliferation, for survival. As obligate intracellular pathogens, viruses modulate host cellular processes, including Akt signaling, for optimal replication. The mechanisms by which viruses modulate Akt and the resulting effects on the infectious cycle differ widely depending on the virus. In this study, we explored the effect of Akt serine 473 phosphorylation (p-Akt) during murine norovirus (MNV) infection. p-Akt increased during infection of murine macrophages with acute MNV-1 and persistent CR3 and CR6 strains. Inhibition of Akt with MK2206, an inhibitor of all three isoforms of Akt (Akt1/2/3), reduced infectious virus progeny of all three virus strains. This reduction was due to decreased viral genome replication (CR3), defective virus assembly (MNV-1), or altered cellular egress (CR3 and CR6) in a virus strain-dependent manner. Collectively, our data demonstrate that Akt activation increases in macrophages during the later stages of the MNV infectious cycle, which may enhance viral infection in unique ways for different virus strains. The data, for the first time, indicate a role for Akt signaling in viral assembly and high-light additional phenotypic differences between closely related MNV strains. IMPORTANCE Human noroviruses (HNoV) are a leading cause of viral gastroenteritis, resulting in high annual economic burden and morbidity, yet there are no small-animal models supporting productive HNoV infection or robust culture systems producing cell culture-derived virus stocks. As a result, research on drug discovery and vaccine development against norovirus infection has been challenging, and no targeted antivirals or vaccines against HNoV are approved. On the other hand, murine norovirus (MNV) replicates to high titers in cell culture and is a convenient and widespread model in norovirus research. Our data demonstrate

关键词： invasive bacterial infection   children   COVID-19   pandemic   nonpharmaceutical interventions  

摘要： Background: Invasive bacterial infection (IBI) remains a major burden of mortality and morbidity in children. As coronavirus disease 2019 (COVID-19) emerged, stringent nonpharmaceutical interventions (NPIs) were applied worldwide. This study aimed to evaluate the impact of NPIs on pediatric IBI in Korea. Methods: From January 2018 to December 2020, surveillance for pediatric IBIs caused by 9 pathogens (S. pneumoniae, H. influenzae, N. meningitidis, S. agalactiae, S. pyogenes, S. aureus, Salmonella species, L. monocytogenes and E. coli) was performed at 22 hospitals throughout Korea. Annual incidence rates were compared before and after the COVID-19 pandemic. Results: A total of 651 cases were identified and the annual incidence was 194.0 cases per 100,000 in-patients in 2018, 170.0 in 2019 and 172.4 in 2020. Most common pathogen by age group was S. agalactiae in infants < 3 months (n = 129, 46.7%), S. aureus in 3 to < 24 months (n = 35, 37.2%), Salmonella spp. in 24 to < 60 months (n = 24, 34.8%) and S. aureus in children >= 5 years (n = 128, 60.7%). Compared with 2018 to 2019, the incidence rate in 2020 decreased by 57% for invasive pneumococcal disease (26.6 vs. 11.5 per 100,000 in-patients, P = 0.014) and 59% for Salmonella spp. infection (22.8 vs. 9.4 per 100,000 in-patients, P = 0.018). In contrast, no significant changes were observed in invasive infections due to S. aureus, S. agalactiae and E. coli. Conclusions: The NPIs implemented during the COVID-19 pandemic reduced invasive diseases caused by S. pneumoniae and Salmonella spp. but not S. aureus, S. agalactiae and E. coli in children.