Abacus, which represents numbers via a visuospatial format, is a traditional device to facilitate arithmetic operations. Skilled abacus users, who have acquired the ability of abacus-based mental ...calculation (AMC), can perform fast and accurate calculations by manipulating an imaginary abacus in mind. Due to this extraordinary calculation ability in AMC users, there is an expanding literature investigating the effects of AMC training on cognition and brain systems. This review study aims to provide an updated overview of important findings in this fast-growing research field. Here, findings from previous behavioral and neuroimaging studies about AMC experts as well as children and adults receiving AMC training are reviewed and discussed. Taken together, our review of the existing literature suggests that AMC training has the potential to enhance various cognitive skills including mathematics, working memory and numerical magnitude processing. Besides, the training can result in functional and anatomical neural changes that are largely located within the frontal-parietal and occipital-temporal brain regions. Some of the neural changes can explain the training-induced cognitive enhancements. Still, caution is needed when extend the conclusions to a more general situation. Implications for future research are provided.
Titanium dioxide nanoparticles (TiO2 NPs) are one of the most widely used nanomaterials in the consumer products, agriculture, and energy sectors. Their large demand and widespread applications will ...inevitably cause damage to organisms and ecosystems. A better understanding of TiO2 NP toxicity in living organisms may promote risk assessment and safe use practices of these nanomaterials. This review summarizes the toxic effects of TiO2 NPs on multiple taxa of microorganisms, algae, plants, invertebrates, and vertebrates. The mechanism of TiO2 NP toxicity to organisms can be outlined in three aspects: The Reactive Oxygen Species (ROS) produced by TiO2 NPs following the induction of electron–hole pairs; cell wall damage and lipid peroxidation of the cell membrane caused by NP-cell attachment by electrostatic force owing to the large surface area of TiO2 NPs; and TiO2 NP attachment to intracellular organelles and biological macromolecules following damage to the cell membranes.
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•The overall maximum dynamic in the time domain is minimized.•The possible non-differentiability of the overall maximum dynamic response is demonstrated.•The max operator in objective function is ...replaced by an aggregation functional.•Differentiate-then-discrete approach can be used for sensitivity analysis.•Numerical examples demonstrate the effectiveness of the proposed method.
This paper develops an efficient approach to solving dynamic response topology optimization problems in the time domain. The objective is to minimize the maximum response of the structure over the complete vibration phase. In order to alleviate the difficulties due to the max operator in the objective function, an aggregation functional is proposed and employed to transform the original problem formulation into one that is computational tractable. The main advantage of the proposed aggregation functional over the existing aggregation functions, such as KS function and the p-norm function is that, for the dynamic response problems in the time domain, the differentiate-then-discretize approach can now be used for adjoint sensitivity analysis, instead of the discretize-then-differentiate approach, which is tightly coupled with the numerical integration schemes of the primal analysis and is more cumbersome. In addition to the solution method, some issues of dynamic response topology optimization problems in the time domain are discussed. The reason why the maximum dynamic response may occur in the free vibration phase for transient load is uncovered. A strategy to reduce the maximum dynamic response over the complete vibration phase is proposed. Numerical examples demonstrate the effectiveness of the proposed method.
•We develop an approach to robust topology optimization under loading uncertainty.•We model loading uncertainty by the distribution of their magnitude and direction.•The effects of loading ...uncertainty on optimization results are demonstrated.
This paper proposes an efficient approach to solving robust topology optimization problem of structures under loading uncertainty. The objective is to minimize a weighted sum of the mean and standard deviation of structural compliance. Loading uncertainties can be in either concentrated loads or uniformly distributed loads. By exploiting of the linear elastic nature of structure, Monte Carlo sampling is completely separated from the topology optimization process, thus accurate calculation of objective function becomes possible. Efficient sensitivity analysis method is developed and its computational cost is only linearly proportional to the number of uncertain loads. The sensitivity analysis is also integrated into the density based topology optimization approach to solve the robust topology optimization problems. The numerical examples demonstrate the effectiveness of the proposed approach. The effect of uncertainty level, probability distribution of uncertainty and different influence of loading magnitude and directional uncertainty on the robust designs are also shown by the numerical examples.
This study evaluated effects of dietary forage to concentrate ratio (F:C) on the body weight, digestibility, ruminal fermentation and rumen bacterial composition in Angus cows. Three diets with ...different F:C (LCD: 65:35, MCD:50:50, and HCD: 35:65) were fed to ninety Angus cows (3.2 ± 0.18 years old, 387.2 ± 22.6 kg). The average daily gain (ADG) and ammonia nitrogen concentration increased (P = 0.039 and P = 0.026, respectively), whereas the acetate to propionate ratio (P = 0.027) and the neutral detergent fiber (NDF) digestibility decreased with increasing concentrate level. The acetate concentration and ruminal pH (P = 0.033 and P = 0.029, respectively) decreased by feeding HCD diet. Serum amyloid A (SAA), C-reactive protein (CRP), haptoglobin (Hp) and lipopolysaccharide binding protein (LBP) increased under the HCD. The relative abundances of Bacteroidetes, Fibrobacterota, Prevotella and Prevotellaceae UCG-003 decreased, whereas the relative abundances of Ruminococcaceae NK4A214 group, Saccharofermentans and Spirochaetota increased with increasing dietary concentrate level. Our study provides a better understanding of rumen fermentation parameters and microbiota under a wide range of dietary F:C ratios, supporting the potential dietary manipulation of microbes, which could enhance feed digestibility associated with cow rearing.
Measurements of speciated atmospheric mercury play a key role in identifying mercury behavior in the atmosphere. In this study, we measured speciated atmospheric mercury, including gaseous elemental ...mercury (GEM), reactive gaseous mercury (RGM), and particulate bound mercury (PBM) (<2.5 μm), in 2015 and 2016 at an urban site in Beijing, China. The mean concentrations of GEM, RGM, and PBM were 4.70 ± 3.53 ng m−3, 18.47 ± 22.27 pg m−3, and 85.18 ± 95.34 pg m−3, respectively. The concentration of PM2.5 significantly affected the distribution of reactive mercury between the gaseous and particulate phases. With the raising of PM2.5 levels, PBM concentrations increased, on the contrary, the concentrations of RGM decreased gradually. The mean concentration of PBM during air-pollution events was more than three times that during clear days. During days with air pollution, the relative humidity significantly affected the gas-particle partitioning of reactive mercury. The linear relationships between gas-particle partitioning coefficient and meteorological factors (air temperature and relative humidity) were obtained over the four seasons. The data also showed that the gas-particle partitioning coefficient of reactive mercury was related to particle composition (e.g., Cl−, BC). The data present in this paper suggested the influence of anthropogenic emissions on reactive mercury in Beijing urban. And the findings will contribute to understand the gas-particle partitioning of reactive mercury and its influencing factors with complex urban pollution.
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•Three speciated atmospheric mercury exhibited obviously seasonal and diurnal variations.•Increasing PM2.5 led to a decrease in RGM levels and an increase in PBM levels.•Temperature, relative humidity, and particle composition were important factors in determining the reactive mercury gas-particle partitioning.
PM2.5 levels influenced the RGM and PBM concentrations, and the important factors that affect the reactive mercury gas-particle partitioning were discussed.
The article raises the issue regarding the possibilities of using musical noise instruments in the process of mass art education. The relevance of the topic is predetermined by these facts: a) ...insufficient attention of representatives of musical education to the use of musical noise instruments; b) the growing importance of this type of instrument in academic and popular music; c) increasing interest of modern youth in instrumental music making; b) the low degree of development of the theory and methodology of playing musical noise instruments. The goal of the work is to consider the phenomenon of musical noise instruments from the education viewpoint as well as to determine their pedagogical potential. The content of the article. Based on the analysis of special literature, the classification concept “musical noise instruments” has been specified. Their mechanical, acoustic, plastic, cultural and educational properties have been characterised. The features of musical noise instruments that determine the possibility and expediency of their use in the practice of musical education have been determined. The results of the study. It is proposed to understand “musical noise instruments” as acoustic mechanical devices that allow creating more or less plastic broadband and colour noises. It has been established that musical noise instruments have an important educational value, which can be explained by a number of factors: a) these instruments belong to the oldest sound generation devices in the history of mankind, familiarity with them serves to expand cultural knowledge and gnostic motivation for art education; b) mastery of them opens the way for developing traditions of the native national art and the wealth of other national cultures; c) musical noise instruments primarily serve to reproduce the musical rhythm in all its expressiveness and structural complexity; involvement of schoolchildren in playing music with musical noise instruments promotes the development of their musical and rhythmic abilities, perceptions and skills; d) since the role of musical noise instruments today has significantly increased in the practice of classical, jazz and popular music, the acquaintance of students with these instruments should be considered as one of the ways to master the poetics and artistic language of modern music in its various style and genre manifestations; e) musical noise instruments have a high potential in attracting preschool children and primary school pupils to active ensemble music playing. Modern pedagogy of higher education should study and develop the didactic capabilities of musical noise instruments in training future teachers of musical art: the formation of their sense of rhythm, texture, architectonics, timbre palette, intonational expressiveness; arranging skills, expanding musical and cultural experience. These tasks require an appropriate technique, the development of which is the author’s further task.
Executive function (EF) refers as to a set of high-level cognitive abilities that are critical to many aspects of daily life. Despite its importance in human daily life, the neural networks ...responsible for the development of EF in childhood are not well understood. The present study thus aimed to examine the development of task-dependent brain network organization and its relationship to age-related improvements in EF. To address this issue, we recruited eighty-eight Chinese children ranging in age from 7 to 12 years old, and collected their functional magnetic resonance imaging (fMRI) data when they performed an EF task. By utilizing graph theory, we found that the task-dependent brain network modules became increasingly segregated with age. Specifically, the intra-module connections within the default-mode network (DMN), frontal-parietal network (FPN) and sensorimotor network (SMN) increased significantly with age. In contrast, the inter-module connections of the visual network to both the FPN/SMN decreased significantly with age. Most importantly, modular segregation of the FPN significantly mediated the relationship between age and EF performance. These findings add to our growing understanding of how development changes in task-dependent brain network organization support vast behavioral improvements in EF observed during childhood.
The emission of mercury (Hg) from cropland soil greatly affects the global Hg cycle. Combinations of different crop cultivars and planting densities will result in different light transmittance under ...canopies, which directly affects the solar and heat radiation flux received by the soil surface below crops. In turn, this might lead to differences in the soil–air total gaseous mercury (TGM) exchange under different cropping patterns. However, soil–air TGM exchange fluxes in croplands under differing canopies have been poorly investigated. Here, a one-year observation of TGM exchange flux was conducted for cropland soils covering five different crop cultivars and three planting densities in North China Plain using the dynamic flux chamber method. The results showed that light transmittance under the canopies was the key control on soil–air TGM exchange fluxes. High light transmittance can enhance soil TGM emission rates and increase the magnitude of diurnal variations in soil–air TGM exchange fluxes. Furthermore, we found that there were piecewise–function relationships (Peak function–constant equation) between light transmittance under the different canopies and the numbers of days after crop sowing. The soil–air TGM exchange fluxes showed a parabolic response to changes in light transmittance under the different canopies. A second-order model was established for the response relationship between soil–air TGM exchange flux and soil Hg concentration, total solar radiation above the canopy, and numbers of days after sowing. The estimated annual average soil–air TGM exchange flux was 5.46 ± 21.69 ng m−2 h−1 at corn–wheat rotation cropland with 30 cm row spacing using this second-order model. Our results might a data reference and a promising foundation for future model development of soil–air TGM exchange in croplands under different crop cultivars and planting densities.
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•Seasonal and diurnal patterns in soil–air mercury fluxes varied with different crops canopies.•Light transmittance under the canopies was the key control on soil–air mercury exchange fluxes.•A second-order model was established for different crop cultivars and planting densities soil–air mercury exchange flux.•The application of result may help to improve the accuracy of soil mercury emission estimation by satellite image inversion.
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