Towards the ground state of molecules via diffusion Monte Carlo on neural networks.

Diffusion Monte Carlo (DMC) based on fixed-node approximation has enjoyed significant developments in the past decades and become one of the go-to methods when accurate ground state energy of molecules and materials is needed. However, the inaccurate nodal structure hinders the application of DMC for more challenging electronic correlation problems. In this work, we apply the neural-network based trial wavefunction in fixed-node DMC, which allows accurate calculations of a broad range of atomic and molecular systems of different electronic characteristics. Our method is superior in both accuracy and efficiency compared to state-of-the-art neural network methods using variational Monte Carlo (VMC). We also introduce an extrapolation scheme based on the empirical linearity between VMC and DMC energies, and significantly improve our binding energy calculation. Overall, this computational framework provides a benchmark for accurate solutions of correlated electronic wavefunction and also sheds light on the chemical understanding of molecules.

Interatomic force from neural network based variational quantum Monte Carlo.

Accurate ab initio calculations are of fundamental importance in physics, chemistry, biology, and materials science, which have witnessed rapid development in the last couple of years with the help of machine learning computational techniques such as neural networks. Most of the recent efforts applying neural networks to ab initio calculation have been focusing on the energy of the system. In this study, we take a step forward and look at the interatomic force obtained with neural network wavefunction methods by implementing and testing several commonly used force estimators in variational quantum Monte Carlo (VMC). Our results show that neural network ansatz can improve the calculation of interatomic force upon traditional VMC. The relationship between the force error and the quality of the neural network, the contribution of different force terms, and the computational cost of each term is also discussed to provide guidelines for future applications. Our work demonstrates that it is promising to apply neural network wavefunction methods in simulating structures/dynamics of molecules/materials and provide training data for developing accurate force fields.

Differential Effects of Monetary and Social Rewards on Product Online Rating Decisions in E-Commerce in China.

Humans can change their behaviors to obtain environmental rewards (e.g., money, food, and sex). However, our knowledge regarding how rewards affect human behaviors by priming and whether there are differences among types of rewards is limited. This study focused on whether monetary and social rewards have different priming effects on product rating decisions in e-commerce by using a behavioral experiment and event-related potentials (ERPs). Using cash/discount coupons as a monetary reward and greeting cards as a social reward, the behavioral data showed that unsatisfactory products with a monetary reward induced a less negative consumer attitude than those with a social reward or no reward; additionally, such products were associated with a longer reaction time while rating products than those with a social reward, reflecting that monetary rewards made it more difficult for the subjects to rate unsatisfactory products than social rewards. The P2, N2, and P3 components of the ERP data were evaluated. Unsatisfactory products caused negative emotion, which could be compensated more by the monetary reward than the social reward as reflected by a smaller P2 amplitude. Due to the compensation effect of the monetary reward, unsatisfactory products were associated with more decision conflict than the social reward as reflected by a more negative N2 amplitude, which is consistent with the behavioral results. However, in the subsequent controlled process, regardless of whether the products were satisfactory or unsatisfactory, the monetary reward caused more attention reallocation and was more motivating than the social reward as reflected by a larger P3 component. These findings have implications for the marketing strategy of online sellers and value of online reviews and suggest attaching importance to ethical issues induced by monetary rewards in rating behaviors.

Corrigendum: The Effects of Money on Fake Rating Behavior in E-Commerce: Electrophysiological Time Course Evidence From Consumers.

[This corrects the article DOI: 10.3389/fnins.2018.00156.].

The Effects of Money on Fake Rating Behavior in E-Commerce: Electrophysiological Time Course Evidence From Consumers.

Online ratings impose significant effects on the behaviors of potential customers. Thus, online merchants try to adopt strategies that affect this rating behavior, and most of these strategies are connected to money, such as the strategies of returning cash coupons if a consumer gives a five-star rating (RI strategy, an acronym for "returning" and "if") or returning cash coupons directly with no additional requirements (RN strategy, an acronym for "returning" and "no"). The current study explored whether a certain strategy (RN or RI) was more likely to give rise to false rating behaviors, as assessed by event-related potentials. A two-stimulus paradigm was used in this experiment. The first stimulus (S1) was the picture of a product with four Chinese characters that reflected the product quality (slightly defective vs. seriously defective vs. not defective), and the second stimulus (S2) displayed the coupon strategy (RN or RI). The participants were asked to decide whether or not to give a five-star rating. The behavioral results showed that the RI strategy led to a higher rate of five-star ratings than the RN strategy. For the electrophysiological time courses, the N1, N2, and LPP components were evaluated. The slightly defective products elicited a larger amplitude of the N1 component than the seriously defective and not-defective products, reflecting that perceptual difficulty was associated with the processing of the slightly defective products. The RI strategy evoked a less negative N2 and a more positive LPP than the RN strategy, indicating that the subjects perceived less conflict and experienced stronger incentives when processing the RI strategy. These findings will benefit future studies of fake online comments and provide evidence supporting the policy of forbidding the use of the RI strategy in e-commerce.

Safety assessment of powdered Cistanche deserticola Y. C. Ma by a 90-day feeding test in Sprague-Dawley rats.

Cistanche deserticola (C. deserticola), a holoparasitic plant widely distributed in arid or semi-arid areas in Eurasia and North Africa, has been used as an important tonic in traditional Eastern medicine for centuries. However, little information on the systemic toxicity and safety evaluation of it is available. The purpose of this study was to investigate the potential toxicity of powdered C. deserticola as a novel food ingredient by use of a subchronic toxicity study in Sprague-Dawley (SD) rats. A total of 80 male and female rats were fed with diets containing 8, 4, 2 and 0% (control) powdered C. deserticola for 90 days. A toxicological assessment was performed including mortality, body and organ weight, food consumption, blood biochemistry, hematology, gross necropsy and histopathological examinations. There were no signs of toxicity and treatment-related changes in rats treated with powdered C. deserticola. The no-observed-adverse-effect level (NOAEL) of powdered C. deserticola was 7.8 g kg-1 body weight for males and 8.0 g kg-1 body weight for females of rats under the experimental conditions of this study.

Duration of untreated psychosis and clinical outcomes of first-episode schizophrenia: a 4-year follow-up study.

BACKGROUND: The relationship between the duration of untreated psychosis and long-term clinical outcomes remains uncertain. OBJECTIVE: Prospectively assess the relationship of the duration of untreated psychosis on clinical outcomes in a sample of individuals with first-onset schizophrenia treated at the Pudong Mental Health Center from January 2007 to December 2008. METHODS: Information about general health, psychotic symptoms and social functioning were collected using the Brief Psychiatric Rating Scale (BPRS), Treatment Emergent Symptom Scale (TESS), Morningside Rehabilitation Status Scale (MRSS), and Social Disability Screening Schedule (SDSS) at baseline and in June 2010 and June 2012. RESULTS: The 43 individuals with first-episode schizophrenia participating in the study were divided into short (<24 weeks) and long (>24weeks) duration of untreated psychosis (DUP) groups. The mean (sd) duration of follow-up was 1197 (401) days in the short DUP group and 1412 (306) days in the long DUP group (t=9.98, p=0.055). Despite less prominent psychotic symptoms at the time of first diagnosis among patients who had a long DUP compared to those with a short DUP (BPRS mean scores, 42.5 [8.4] v. 50.0 [10.6], t=2.42, p=0.0210) and a similar number of clinical relapses (based on positive symptoms assessed by the BPRS), patients with a long DUP were more likely to require hospitalization at the time of first diagnosis (52% [11/21] v. 9% [2/22], χ(2) =9.55, p=0.002) and more likely to require re-hospitalization during the first two years of treatment (67% [14/21] v. 32% [7/22], χ(2) =5.22, p=0.022). Moreover, after four years of routine treatment, despite a similar severity of positive symptoms, patients who had had a long DUP prior to initiating treatment had significantly poorer social functioning than those who had had a short DUP (SDSS mean scores, 7.0 [5.2] v. 3.4 [4.9], t=2.20, p=0.035). CONCLUSIONS: These findings show that despite having a similar level of psychotic symptoms - as measured by the BPRS - compared to patients with a short DUP, patients with schizophrenia who have a long DUP prior to initial treatment have poorer long-term social functioning. This confirms the clinical importance of the early recognition and treatment of individuals with chronic psychotic conditions.

QSAR study of carboxylic acid derivatives as HIV-1 Integrase inhibitors.

QSAR studies have been carried out on carboxylic acid derivatives as HIV-1 Integrase inhibitors using 3D-MoRSE (3D-Molecular Representation of Structure based on Electron diffraction) descriptors. The stepwise multiple linear regression (stepwise-MLR) and replacement method (RM) methods are used to select descriptors which are responsible for the inhibitory activity of these compounds. Mathematical models are obtained by support vector machine (SVM), back-propagation neural networks (BPNN) and multiple linear regression (MLR). Leave-one-out, Leave-many-out (7% and 18%) cross-validation and external validation are carried out with the aim of evaluating the predictive ability of the models. The values of their respective squared correlations coefficients are 0.731, 0.664, 0.523 and 0.766, respectively. Our best QSAR model reveals the polarizability, mass as the most influencing atomic properties in the structures of the carboxylic acid derivatives.

[A discussion on the CSP genotyping of Plasmodium vivax and malaria control in five southern provinces of China].

OBJECTIVE: To explore circumsporozoite protein (CSP) genotype structure of Plasmodium vivax in southern China and evaluate its epidemiological significance. METHODS: Filter paper blood samples were collected from 346 vivax malaria patients in 5 provinces (Autonomous Region) including Hainan, Yunnan, Guangxi, Guangdong and Guizhou for identifying CSP genotypes, by using the method of single-tube nested/multiplex PCR. The findings combined with relevant data were statistically analyzed. RESULTS: In Guangdong, Guangxi and Guizhou Provinces (Autonomous Region), the temperate zone family strains accounted for more than 90%, with only a few tropical zone family strains and no PV-type II each strain. In Yunnan Province, temperate strains and tropical strains accounted for 71.4% and 28.6% respectively, with occasional PV-type II strain. In Hainan Province, strains of temperate zone, tropical zone and PV-type II accounted for about one-third. CONCLUSIONS: The temperate zone family strains were the predominant ones in the Provinces (Autonomous Region) of Guangdong, Guangxi and Guizhou where malaria control was carried out effectively; while in Hainan and Yunnan Provinces the difficulties in malaria control may probably be related to the complex structure of P. vivax population and multiple infections of different genotypes. The findings indicate that the complexity of the P. vivax genotype structure might be an indicative epidemiological feature for malaria control and surveillance.