Shapley Computations Using Surrogate Model-Based Trees

Shapley-related techniques have gained attention as both global and local interpretation tools because of their desirable properties. However, their computation using conditional expectations is computationally expensive. Approximation methods suggested in the literature have limitations. This paper proposes the use of a surrogate model-based tree to compute Shapley and SHAP values based on conditional expectation. Simulation studies show that the proposed algorithm provides improvements in accuracy, unifies global Shapley and SHAP interpretation, and the thresholding method provides a way to trade-off running time and accuracy

Graphical Models in Financial Market and Portfolio Allocation: Applications and Considerations

In recent years, the L-1 regularization has been extensively used to estimate a sparse precision matrix and encode an undirected graphical model. Because the regularized estimates are biased, the application of the graphical models has largely been restricted and has been ignored in many areas. In this work, we show that graphical models and their regularized estimates can be useful in the area of finance. We present our discussion in three parts. First, we propose a graphical representation model for the asset returns. The model captures observed variance in the equity market endogenously and offers a new perspective on the covariance estimation for asset returns. We show that such a model may provide a straightforward interpretation for investors regarding investment decision making. Second, we show that regularized estimates of graphical models, though biased, are useful to estimate the minimum variance portfolio and determine the portfolio rebalancing strategy. Third, we discuss the algorithms of solving one of the graphical models -- the graphical Concord. We present the software development process for the graphical Concord and illustrate the usage of the packages with some examples

Investigation and Validation of Mission Evaluation Models for Space Close-Range Inspection

Space close-range inspection can be used to carry out close-range observation and monitoring of targets for identifying the target’s types and working states, which is of great significance for space missions such as in-orbit services. The effectiveness evaluation of space inspection tasks will significantly affect the studies on the trajectory design, orbit motion control, and task termination conditions. However, the evaluation models in previous studies are too simple such as that they are usually without considering dynamic changes in the satellite orbit relative motion. Besides, these studies fail to build a comprehensive evaluation model for the whole inspection task process. In this paper, taking the most commonly used optical inspection as an example, the novel multifactor inspection task effectiveness evaluation models were investigated, including the constraint models of observation, the relative distance evaluation model, the effective observation time evaluation model, and the target observation angle evaluation model. These models solve the effectiveness evaluation problem for the complete process of an inspection task, which can support the design of inspection strategies and trajectories better by using the evaluation results. In addition, numerical simulations and 20 semiphysical experiments were carried out to validate the proposed evaluation models

Mineralization of High-Concentration Aqueous Aniline by Hybrid Process

The efficient mineralization of high-concentration aqueous aniline (HCAA) is an issue needing to be resolved. In this study, a hybrid process of ozonation and electrochemical oxidation (ECO) was proposed for improving the mineralization of HCAA (1000 mg·L−1). The results indicated that chemical oxygen demand (COD) removal by the hybrid process was far greater than that of a single ozonation or ECO process, revealing that the hybrid process might avoid low efficiency in late ozonation and initial ECO. Thus, a subsequent combination effect clearly existed. In this hybrid process, ozonation stage time was selected as 60 min for optimal COD removal. The main products of the ozonation stage were maleic and succinic acids, with declining pH which was beneficial to the following ECO stage. Nitrite and nitrate formed during ozonation, which acted as electrolytes for the ECO stage, in which maleic and succinic acids were fully degraded and pH thus increased. Moreover, the aniline degradation mechanism of the hybrid process was deduced, demonstrating the superiority of this hybrid process. Finally, more than 95% COD removal was achieved, which met the COD limit requirement and achieved pH control simultaneously, according to the discharge standards of water pollutants for dyeing and finishing of the textile industry in China (GB 4287–2012)

Mineralization of High-Concentration Aqueous Aniline by Hybrid Process

The efficient mineralization of high-concentration aqueous aniline (HCAA) is an issue needing to be resolved. In this study, a hybrid process of ozonation and electrochemical oxidation (ECO) was proposed for improving the mineralization of HCAA (1000 mg·L−1). The results indicated that chemical oxygen demand (COD) removal by the hybrid process was far greater than that of a single ozonation or ECO process, revealing that the hybrid process might avoid low efficiency in late ozonation and initial ECO. Thus, a subsequent combination effect clearly existed. In this hybrid process, ozonation stage time was selected as 60 min for optimal COD removal. The main products of the ozonation stage were maleic and succinic acids, with declining pH which was beneficial to the following ECO stage. Nitrite and nitrate formed during ozonation, which acted as electrolytes for the ECO stage, in which maleic and succinic acids were fully degraded and pH thus increased. Moreover, the aniline degradation mechanism of the hybrid process was deduced, demonstrating the superiority of this hybrid process. Finally, more than 95% COD removal was achieved, which met the COD limit requirement and achieved pH control simultaneously, according to the discharge standards of water pollutants for dyeing and finishing of the textile industry in China (GB 4287–2012)

Molecular Assembly-Induced Charge Transfer for Programmable Functionalities

© 2017 American Chemical Society. The donor-acceptor interface within molecular charge transfer (CT) solids plays a vital role in the hybridization of molecular orbitals to determine their carrier transport and electronic delocalization. In this study, we demonstrate molecular assembly-driven bilayer and crystalline solids, consisting of electron donor dibenzotetrathiafulvalene (DBTTF) and acceptor C60, in which interfacial engineering-induced CT degree control is a key parameter for tuning its optical, electronic, and magnetic performance. Compared to the DBTTF/C60 bilayer structure, the DBTTFC60 cocrystalline solids show a stronger degree of charge transfer for broad CT absorption and a large dielectric constant. In addition, the DBTTFC60 cocrystals exhibit distinct CT arrangement-driven anisotropic electron mobility and spin characteristics, which further enables the development of high-penetration and high-energy γ-ray photodetectors. The results presented in this paper provide a basis for the design and control of molecular charge transfer solids, which facilitates the integration of such materials into molecular electronics

Isolation, characterization, and structure-based engineering of a neutralizing nanobody against SARS-CoV-2

International audienceSARS-CoV-2 engages with human cells through the binding of its Spike receptor-binding domain (S-RBD) to the receptor ACE2. Molecular blocking of this engagement represents a proven strategy to treat COVID-19. Here, we report a single-chain antibody (nanobody, DL4) isolated from immunized alpaca with picomolar affinity to RBD. DL4 neutralizes SARS-CoV-2 pseudoviruses with an IC50 of 0.101 mu g mL-1 (6.2 nM). A crystal structure of the DL4-RBD complex at 1.75-angstrom resolution unveils the interaction detail and reveals a direct competition mechanism for DL4's ACE2-blocking and hence neutralizing activity. The structural information allows us to rationally design a mutant with higher potency. Our work adds diversity of neutralizing nanobodies against SARS-CoV-2 and should encourage protein engineering to improve antibody affinities in general

Potential Hormetic Effects of Cimetidine on Aerobic Composting of Human Feces from Rural China

Aerobic composting is widely used worldwide as a natural process for handling human waste. Such waste often contains pharmaceutical residues from human consumption, yet their impact on composting has not been studied. The aim of this study is to investigate the impact of the antihistamine cimetidine (10 mg/kg, 100 mg/kg) on the aerobic composting of human feces. The key results show that 10 mg/kg of cimetidine accelerates temperature increase and moisture removal of the composting substrate. The organic matter in all the groups gradually decreased, and the pH values increased first and then declined with the composting time, with no significant differences between the groups. The NH4+-N concentrations and NH3 emission reached the maximum at 1.5 days and then declined rapidly, while the NO2−-N concentrations increased and then decreased, and the NO3−-N contents tended to increase all the time during the composting. The 100 mg/kg cimetidine caused a higher maximal NH4+-N concentration of compost, and a lower maximal NH3 emission at 1.5 days, while 10 mg/kg cimetidine led to more NO2−-N and NO3−-N contents. In addition, 10 mg/kg cimetidine enhanced the aromatization and humification of dissolved organic matter and promoted the degradation of aliphatic substances. Furthermore, 100 mg/kg cimetidine generated a larger influence on the microorganisms than 10 mg/kg cimetidine, especially for the microorganisms related to nitrogen transformation. The findings imply that cimetidine has a dose-dependent impact on the decomposition of organic matter and the conversion of nitrogen in human feces during composting. It deserves further investigation of the possible hormesis effect

Potential Hormetic Effects of Cimetidine on Aerobic Composting of Human Feces from Rural China

Aerobic composting is widely used worldwide as a natural process for handling human waste. Such waste often contains pharmaceutical residues from human consumption, yet their impact on composting has not been studied. The aim of this study is to investigate the impact of the antihistamine cimetidine (10 mg/kg, 100 mg/kg) on the aerobic composting of human feces. The key results show that 10 mg/kg of cimetidine accelerates temperature increase and moisture removal of the composting substrate. The organic matter in all the groups gradually decreased, and the pH values increased first and then declined with the composting time, with no significant differences between the groups. The NH4+-N concentrations and NH3 emission reached the maximum at 1.5 days and then declined rapidly, while the NO2−-N concentrations increased and then decreased, and the NO3−-N contents tended to increase all the time during the composting. The 100 mg/kg cimetidine caused a higher maximal NH4+-N concentration of compost, and a lower maximal NH3 emission at 1.5 days, while 10 mg/kg cimetidine led to more NO2−-N and NO3−-N contents. In addition, 10 mg/kg cimetidine enhanced the aromatization and humification of dissolved organic matter and promoted the degradation of aliphatic substances. Furthermore, 100 mg/kg cimetidine generated a larger influence on the microorganisms than 10 mg/kg cimetidine, especially for the microorganisms related to nitrogen transformation. The findings imply that cimetidine has a dose-dependent impact on the decomposition of organic matter and the conversion of nitrogen in human feces during composting. It deserves further investigation of the possible hormesis effect