Search

Do language skills affect investment decisions? This article addresses this question by identifying the effect of English proficiency on the stock market participation of immigrants in the United States and Australia. To establish causality, we construct an instrumental variable for English proficiency by exploiting the phenomenon that younger children acquire languages more easily than older children. We find that English proficiency has a significant positive effect on stock ownership among immigrants in both countries. Moreover, we provide evidence that a reduction in information costs and an increase in trust may serve as the mechanisms underlying the language ability effect. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) can be employed in a cell-free system to create favorable propagation conditions from base stations (BSs) to users via configurable elements. However, prior works on RIS-aided cell-free system designs mainly rely on the instantaneous channel state information (CSI), which may incur substantial overhead due to extremely high dimensions of estimated channels. To mitigate this issue, a low-complexity algorithm via the two-timescale transmission protocol is proposed in this paper, where the joint beamforming at BSs and RISs is facilitated via alternating optimization framework to maximize the average weighted sum-rate. Specifically, the passive beamformers at RISs are optimized through the statistical CSI, and the transmit beamformers at BSs are based on the instantaneous CSI of effective channels. In this manner, a closed-form expression for the achievable weighted sum-rate is derived, which enables the evaluation of the impact of key parameters on system performance. To gain more insights, a special case without line-of-sight (LoS) components is further investigated, where a power gain on the order of $\mathcal {O}(M)$ is achieved, with $M$ being the BS antennas number. Numerical results validate the tightness of our derived analytical expression and show the fast convergence of the proposed algorithm. Findings illustrate that the performance of the proposed algorithm with two-timescale CSI is comparable to that with instantaneous CSI in low or moderate SNR regime. The impact of key system parameters such as the number of RIS elements, CSI settings and Rician factor is also evaluated. Moreover, the remarkable advantages from the adoption of the cell-free paradigm and the deployment of RISs are demonstrated intuitively. [ABSTRACT FROM AUTHOR]

Background: The prevalence of dementia in China, particularly in rural areas, is consistently increasing; however, research on population-attributable fractions (PAFs) of risk factors for dementia is scarce. Methods: We conducted a cross-sectional survey, namely, the China Multicentre Dementia Survey (CMDS) in selected rural and urban areas from 2018 to 2020. We performed face-to-face interviews and neuropsychological and clinical assessments to reach a consensus on dementia diagnosis. Prevalence and weighted PAFs of eight modifiable risk factors (six classical: less childhood education, hearing impairment, depression, physical inactivity, diabetes, and social isolation, and two novels: olfactory decline and being unmarried) for all-cause dementia were estimated. Results: Overall, CMDS included 17,589 respondents aged ≥ 65 years, 55.6% of whom were rural residents. The age- and sex-adjusted prevalence for all-cause dementia was 9.11% (95% CI 8.96–9.26), 5.19% (5.07–5.31), and 11.98% (11.8–12.15) in the whole, urban, and rural areas of China, respectively. Further, the overall weighted PAFs of the eight potentially modifiable risk factors were 53.72% (95% CI 52.73–54.71), 50.64% (49.4–51.89), and 56.54% (55.62–57.46) in the whole, urban, and rural areas of China, respectively. The eight risk factors' prevalence differed between rural and urban areas. Lower childhood education (PAF: 13.92%) and physical inactivity (16.99%) were primary risk factors in rural and urban areas, respectively. Conclusions: The substantial urban–rural disparities in the prevalence of dementia and its risk factors exist, suggesting the requirement of resident-specific dementia-prevention strategies. [ABSTRACT FROM AUTHOR]

aims to evaluate the relationship of thyroid function during the first trimester of pregnancy with lipid levels and pregnancy outcomes. Methods: Women who delivered babies at the Shanghai General Hospital between March 2019 and December 2019 with a known pregnancy outcome and complete data were included in the present study (n = 1779). A retrospective cohort study of all subjects with available first-trimester thyroid function testing and lipid levels data was conducted, and the relationship of thyroid function with lipid levels and pregnancy outcomes was evaluated. The data were analyzed using the SPSS software for statistical correlation. Results: The proportion of caesarean sections was higher in women with hypothyroxinemia (HIA) and hypothyroidism than in women with euthyroidism. Hypothyroidism was shown to be related with polyhydramnios, preterm labor and hypertriglyceridemia. HIA was correlated with increased rates of gestational diabetes mellitus (GDM), preeclampsia, gestational hypertension and hypertriglyceridemia. Compared with the euthyroidism group, the hypothyroidism group had a higher apolipoprotein A1 (Apo A1) level and apolipoprotein B level; the subclinical hypothyroidism group had a higher total cholesterol (TC) level and low-density lipoprotein cholesterol level; the HIA group had higher triglyceride, high-density lipoprotein cholesterol levels and lower TC, Apo A1 levels. TC levels were positively correlated with the thyroid-stimulating hormone level and negatively correlated with free thyroxine (FT4) level, and free triiodothyronine and FT4 levels were positively correlated with GDM occurrence. Conclusion: Thyroid function in early pregnancy is associated with dyslipidemia and pregnancy outcomes; conventional screening of thyroid diseases in early pregnancy may help improve lipid levels and decrease adverse pregnancy outcomes. [ABSTRACT FROM AUTHOR]

Using microdata from the Chinese General Social Survey (CGSS 2010), this paper investigates whether there are green returns to education in China, where educational attainment promotes pro-environmental attitudes and behaviors. We establish causality by exploiting the exogenous variation induced by the implementation of the Compulsory Schooling Law (CSL) in China. We find evidence that educational attainment is associated with higher levels of pro-environmental attitudes and behaviors, and these estimates are robust to various robustness checks. Further analysis reveals that the acquisition of environmental knowledge is the channel that drives the effect of education on pro-environmental attitudes and behaviors. Finally, the effects of education are heterogeneous across individuals. [ABSTRACT FROM AUTHOR]

Background: Despite the improved access to health services in China, inadequate diagnosis and management of dementia are common issues, especially in rural regions.Objective: The Hubei Memory & Aging Cohort Study was designed as a prospective study in Central China to determine the prevalence, incidence, and risk factors for dementia and mild cognitive impairment (MCI) among urban and rural older adults.Methods: From 2018-2020, participants aged ≥65 years were screened, and data regarding their life behaviors, families, socio-economic status, physical and mental health, social and psychological factors, and cognition were collected. Diagnoses of MCI and dementia were made via consensus diagnosis using the Diagnostic and Statistical Manual of Mental Disorders fourth edition criteria.Results: Of 8,221 individuals who completed their baseline clinical evaluation, 4,449 (54.1%) were women and 3,164 (38.4%) were from remote rural areas (average age: 71.96 years; mean education period: 7.58 years). At baseline, 25.98%(95%confidence interval [CI]: 24.99-26.96) and 7.24%(95%CI: 6.68-7.80) of the participants were diagnosed with MCI and dementia, respectively. Prevalence showed a strong relationship with age. The substantial disparities between rural and urban regions in MCI and dementia prevalence and multiple dementia-related risk factors were revealed. Especially for dementia, the prevalence rate in rural areas was 2.65 times higher than that in urban regions.Conclusion: Our results suggested that public health interventions are urgently needed to achieve equitable diagnosis and management for people living with dementia in the communities across urban and rural areas. [ABSTRACT FROM AUTHOR]

Background: Some studies have demonstrated an association between low and high body mass index (BMI) and an increased risk of dementia. However, only a few of these studies were performed in rural areas.Objective: This cross-sectional study investigated the associations between BMI and cognitive impairment among community-dwelling older adults from rural and urban areas.Methods: 8,221 older persons enrolled in the Hubei Memory & Ageing Cohort Study (HMACS) were recruited. Sociodemographic and lifestyle data, comorbidities, physical measurements, and clinical diagnoses of cognitive impairment were analyzed. Logistic regression was performed to assess the associations of BMI categories with cognitive impairment. A series of sensitivity analyses were conducted to test whether reverse causality could influence our results.Results: Being underweight in the rural-dwelling participants increased the risk of cognitive impairment. Being overweight was a protective factor in rural-dwelling participants aged 65-69 years and 75-79 years, whereas being underweight was significantly associated with cognitive impairment (OR, 1.37; 95% CI: 1.03-1.83; p < 0.05). Sensitivity analyses support that underweight had an additive effect on the odds of cognitive impairment and was related to risk of dementia. Interaction test revealed that the differences between urban/rural in the relationship between BMI and cognitive impairment are statistically significant.Conclusion: Associations between BMI and cognitive impairment differ among urban/rural groups. Older people with low BMI living in rural China are at a higher risk for dementia than those living in urban areas. [ABSTRACT FROM AUTHOR]

Reconfigurable intelligent surface (RIS) is a promising solution to build a programmable wireless environment with reconfigurable passive elements, which can achieve high spectral and energy efficiency. In this paper, we investigate the ergodic capacity of RIS-assisted multi-user multiple-input single-output (MISO) wireless systems in both uplink and downlink scenarios. Unlike most of prior works, where instantaneous channel state information (CSI) is assumed, we consider the realistic scenario with only statistical CSI. For both scenarios, we first present an analytical expressions for the ergodic sum capacity of the system. Based on which, the joint power control (or transmit beamforming) and phase shift design problem maximizing the ergodic sum capacity is formulated. Capitalizing on the alternating direction method of multipliers (ADMM), fractional programming (FP) and alternating optimization (AO) methods, efficient suboptimal solutions are obtained for the non-convex design problems. Simulation results are presented to validate the accuracy of the analytical ergodic sum capacity expressions and evaluate the impact of key system parameters such as CSI, Rician $K$ factor, number of RIS elements, and RIS location on the ergodic capacity performance. The findings suggest that the proposed statistical CSI design achieves decent performance compared with the instantaneous CSI based design. Moreover, a signal hot spot can be created when placing the RIS close to the users. [ABSTRACT FROM AUTHOR]

Background: The causes of gestational diabetes mellitus (GDM) are still unclear. Recent studies have found that the imbalance of the gut microbiome could lead to disorders of human metabolism and immune system, resulting in GDM. This study aims to reveal the different gut compositions between GDM and normoglycemic pregnant women and find the relationship between gut microbiota and GDM.Methods: Fecal microbiota profiles from women with GDM (n = 21) and normoglycemic women (n = 32) were assessed by 16S rRNA gene sequencing. Fasting metabolic hormone concentrations were measured using multiplex ELISA.Results: Metabolic hormone levels, microbiome profiles, and inferred functional characteristics differed between women with GDM and healthy women. Additionally, four phyla and seven genera levels have different correlations with plasma glucose and insulin levels. Corynebacteriales (order), Nocardiaceae (family), Desulfovibrionaceae (family), Rhodococcus (genus), and Bacteroidetes (phylum) may be the taxonomic biomarkers of GDM. Microbial gene functions related to amino sugar and nucleotide sugar metabolism were found to be enriched in patients with GDM.Conclusion: Our study indicated that dysbiosis of the gut microbiome exists in patients with GDM in the second trimester of pregnancy, and gut microbiota might be a potential diagnostic biomarker for the diagnosis, prevention, and treatment of GDM. [ABSTRACT FROM AUTHOR]

This letter presents a detailed investigation on the performance of reconfigurable intelligent surface (RIS)-assisted communication system with user scheduling. Depending on the availability of channel state information (CSI) at the RIS, two separate scenarios are considered, namely without CSI and with CSI. Closed-form expressions are derived for the ergodic capacity of the system in both scenarios. It is found that CSI has a significant impact on the performance of the system. Without CSI, the RIS provides an array gain of N, where N is the number of reflecting elements, and user scheduling provides an multi-user gain of $\log \log \text {M}$ , where M is the number of users. With CSI, the RIS provides an array gain of $\text {N}^{2}$ , while no multi-user diversity gain can be obtained. [ABSTRACT FROM AUTHOR]

Fracture to fifth metatarsal's base is one the most common injury experienced at the foot. Studies have for long debated the use of operative and non-operative interventions for the management of the fracture, especially owing to its peculiar vasculature. However, to date, no attempt has been made to synthesize the evidence comparing the efficacy of operative and non-operative interventions for managing the fifth metatarsal's base fracture. To meta-statistically compare the effects of operative and non-operative management of fifth metatarsal base fracture. A systematic identification of literature was performed according to PRISMA guidelines on four academic databases: MEDLINE, Scopus, EMBASE, and CENTRAL. A meta-analysis evaluated the influence of operative and non-operative interventions on rate of non-union, mean duration of union, duration of return to activity, duration of return to sport, visual analog scale, and the American orthopedic foot & ankle scale. Out of 1,170 records, 11 articles including 404 participants (mean age: 29.8 ± 7.4 years) were included in this review. This systematic review presents a 1b level of evidence supporting the use of operative interventions for enhancing fracture union as compared to non-operative interventions. The meta-analysis reveals beneficial effects for operative interventions by demonstrating medium to large effect reduction of rate of non-union (Hedge's g: -0.66), duration of union (-1.7), duration of return to activity (-2.07), visual analog scale (-0.86), and enhancement of the American orthopedic foot & ankle scale score (0.73) as compared to non-operative intervention. The current systematic review and meta-analysis recommend the use of operative interventions for managing the fifth metatarsal's base fracture. The review reports beneficial effects of operative interventions as compared to non-operative interventions for reducing the rate of non-union, duration of union, duration of return to activity, duration of return to sport, visual analog scale, and increasing the American orthopedic foot & ankle scale score. [ABSTRACT FROM AUTHOR]

Molybdenum-dependent nitrogenases catalyze the transformation of dinitrogen into ammonia under ambient conditions. The active site (FeMo cofactor) is the structurally and electronically complex weak-field metal cluster [MoFe7S9C] built of Fe4S3 and MoFe3S3C portions connected by three sulfur bridges and containing an interstitial carbon atom centered in an Fe6 trigonal prism. Chemical synthesis of this cluster is a major challenge in biomimetic inorganic chemistry. One synthetic approach of core ligand metathesis has been developed based on the design and synthesis of unprecedented incomplete ([(Tp*)WFe2S3Q3]-) and complete ([(Tp*)WFe3S3Q4]2-) cubane-type clusters containing bridging halide (Q = halide). These clusters are achieved by template-assisted assembly in the presence of sodium benzophenone ketyl reductant; products are controlled by reaction stoichiometry. Incomplete cubane clusters are subject to a variety of metathesis reactions resulting in substitution of a μ2-bridging ligand with other bridges such as N3-, MeO-, and EtS-. Reactions of complete cubanes with Me3SiN3 and S8 undergo a redox metathesis process and lead to core ligand displacement and formation of [(Tp*)WFe3S3(μ3-Q)Cl3]- (Q = Me3SiN2-, S2-). This work affords entry to a wide variety of heteroleptic clusters derivable from incomplete and complete cubanes; examples are provided. Among these is the cluster [(Tp*)WFe3S3(μ3-NSiMe3)Cl3]-, one of the very few instances of a synthetic Fe-S cluster containing a light atom (C, N, O) in the core, which constitutes a close mimic of the [MoFe3S3C] fragment in FeMo cofactor. Superposition of them and comparison of metric information disclose a clear structural relationship [Tp* = tris(3,5-dimethyl-1-pyrazolyl)hydroborate(1-)]. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Zhejiang University: Science A is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For the accurate description of aerodynamic characteristics for aircraft, a wavelet neural network (WNN) aerodynamic modeling method from flight data, based on improved particle swarm optimization (PSO) algorithm with information sharing strategy and velocity disturbance operator, is proposed. In improved PSO algorithm, an information sharing strategy is used to avoid the premature convergence as much as possible; the velocity disturbance operator is adopted to jump out of this position once falling into the premature convergence. Simulations on lateral and longitudinal aerodynamic modeling for ATTAS (advanced technologies testing aircraft system) indicate that the proposed method can achieve the accuracy improvement of an order of magnitude compared with SPSO-WNN, and can converge to a satisfactory precision by only 60-120 iterations in contrast to SPSO-WNN with 6 times precocities in 200 times repetitive experiments using Morlet and Mexican hat wavelet functions. Furthermore, it is proved that the proposed method is feasible and effective for aerodynamic modeling from flight data. [ABSTRACT FROM AUTHOR]

In order to accurately describe the dynamic characteristics of flight vehicles through aerodynamic modeling, an adaptive wavelet neural network (AWNN) aerodynamic modeling method is proposed, based on subset kernel principal components analysis (SKPCA) feature extraction. Firstly, by fuzzy C-means clustering, some samples are selected from the training sample set to constitute a sample subset. Then, the obtained samples subset is used to execute SKPCA for extracting basic features of the training samples. Finally, using the extracted basic features, the AWNN aerodynamic model is established. The experimental results show that, in 50 times repetitive modeling, the modeling ability of the method proposed is better than that of other six methods. It only needs about half the modeling time of KPCA-AWNN under a close prediction accuracy, and can easily determine the model parameters. This enables it to be effective and feasible to construct the aerodynamic modeling for flight vehicles. [ABSTRACT FROM AUTHOR]

A method is described for the calibration of vertical piezoelectric transducer (PZT) stages using a large range metrological atomic force microscope (LRM-AFM). A vertical PZT stage is mounted onto the system and an optical-flat sample is attached on the top of the PZT stage. The AFM probe is operated in contact mode and used as a null indicator to measure the movement of the optical-flat as it is driven by the PZT stage. As the PZT stage is scanned vertically, the AFM probe is in contact with the test surface without lateral scanning. The displacement of the vertical stage of the LRM-AFM is measured by the integrated laser interferometer, and the corresponding laser interferometer readings and the nominal position of the PZT stage are recorded. This body of data is then used to establish the relationship between the laser interferometer reading and the nominal displacement of the PZT stage. Our results show that this method can be used to calibrate PZT stages up to a range of µ250 m with an expanded uncertainty of less than 5 nm. [ABSTRACT FROM AUTHOR]

HIV/AIDS epidemic is crucial in China; however, few studies were performed on youths. This study was performed to examine the effectiveness of peer-led HIV prevention intervention on HIV-related knowledge, attitudes and behaviour intention in senior high-school students in San-ming, a medium-sized city in Fujian province. Three thousand and sixty-eight students completed self-administered questionnaires before and after intervention, of which 981 students (the intervention group) accepted peer-led HIV/ AIDS prevention intervention and others (the control groups) continued the usual teacher-led health education curriculum. Significant increases were observed in the intervention group in HIV-related knowledge, in attitudes and in behaviour intention after intervention. The results of this research also indicated an inconsistent level of HIV/AIDS knowledge and attitude among students, with a significant gender, health education history and style difference in session delivery. More concerted efforts in HIV prevention are needed to improve young people's sexual health. [ABSTRACT FROM AUTHOR]

A direct phase coherent determination of the absolute frequency of the a15 component in the R(12) 26.0 and b10 component in the R(106) 28.0 transitions in 127I2 at 543 nm has been made at the International Bureau of Weights and Measures. Lasers from the Czech Metrology Institute (Czech Republic), the National Institute of Metrology (China), the Centro Nacional de Metrologia (Mexico), the Standards, Productivity and Innovation Board (Singapore), the Centre for Metrology and Accreditation (Finland), the Danish Institute of Fundamental Metrology (Denmark), the National Physical Laboratory (U.K.), and the International Bureau of Weights and Measures took part. The mean frequency values found are ƒ(a15) = 551 579 856 480.4 kHz, uc =4.8 kHz and ƒ(b10) = 551 580 162 397.1 kHz, uc = 4.6 kHz for the current group of lasers, where uc is the combined standard uncertainty. This constitutes a 30-fold improvement in accuracy for this radiation, which is recommended for the realization of the definition of the meter. If only lasers equipped with an iodine cell temperature control are considered, the group of lasers shows a dispersion of 7 kHz. This value is indicative of the level of reproducibility that can be expected at present for this type of standard. [ABSTRACT FROM AUTHOR]

Chiral 1,2-diamines serve as not only common structure units in bioactive molecules but also useful ligands for a range of catalytic asymmetric reactions. Here, we report a method to access anti-1,2-diamine derivatives. By means of the electron-withdrawing nature of 2- or 4-nitro-phenyl group, a copper(I)-catalyzed asymmetric α-addition of ketimines derived from trifluoroacetophenone and 2- or 4-NO2-benzylamines to aldimines is achieved, which affords a series of chiral anti-1,2-diamine derivatives in moderate to high yields with moderate to high diastereoselectivity and high to excellent enantioselectivity. Aromatic aldimines, heteroaromatic aldimines, and aliphatic aldimines serve as suitable substrates. The nitro group is demonstrated as a synthetical handle by several transformations, including a particularly interesting Fe(acac)3-catalyzed radical hydroamination with a trisubstituted olefin. Moreover, the aryl amine moiety obtained by the reduction of the nitro group serves as a synthetically versatile group, which leads to the generation of several functional groups by the powerful Sandmeyer reaction, such as -OH, -Br, -CF3, and -BPin. Chiral 1,2-diamines are useful chemicals used as ligands in asymmetric catalysis. Here, the authors report a copper(I)-catalyzed asymmetric α-addition of ketimines derived from trifluoroacetophenone and 2- or 4-NO2-benzylamines to aldimines, affording a series of chiral anti-1,2-diamine derivatives. [ABSTRACT FROM AUTHOR]