Fractal and complex network analyses of protein molecular dynamics

Based on protein molecular dynamics, we investigate the fractal properties of energy, pressure and volume time series using the multifractal detrended fluctuation analysis (MF-DFA) and the topological and fractal properties of their converted horizontal visibility graphs (HVGs). The energy parameters of protein dynamics we considered are bonded potential, angle potential, dihedral potential, improper potential, kinetic energy, Van der Waals potential, electrostatic potential, total energy and potential energy. The shape of the h(q)h(q) curves from MF-DFA indicates that these time series are multifractal. The numerical values of the exponent h(2)h(2) of MF-DFA show that the series of total energy and potential energy are non-stationary and anti-persistent; the other time series are stationary and persistent apart from series of pressure (with H≈0.5H≈0.5 indicating the absence of long-range correlation). The degree distributions of their converted HVGs show that these networks are exponential. The results of fractal analysis show that fractality exists in these converted HVGs. For each energy, pressure or volume parameter, it is found that the values of h(2)h(2) of MF-DFA on the time series, exponent λλ of the exponential degree distribution and fractal dimension dBdB of their converted HVGs do not change much for different proteins (indicating some universality). We also found that after taking average over all proteins, there is a linear relationship between 〈h(2)〉〈h(2)〉 (from MF-DFA on time series) and 〈dB〉〈dB〉 of the converted HVGs for different energy, pressure and volume

Validation of the Social Networking Activity Intensity Scale among Junior Middle School Students in China.

Online social networking use has been integrated into adolescents' daily life and the intensity of online social networking use may have important consequences on adolescents' well-being. However, there are few validated instruments to measure social networking use intensity. The present study aims to develop the Social Networking Activity Intensity Scale (SNAIS) and validate it among junior middle school students in China.A total of 910 students who were social networking users were recruited from two junior middle schools in Guangzhou, and 114 students were retested after two weeks to examine the test-retest reliability. The psychometrics of the SNAIS were estimated using appropriate statistical methods.Two factors, Social Function Use Intensity (SFUI) and Entertainment Function Use Intensity (EFUI), were clearly identified by both exploratory and confirmatory factor analyses. No ceiling or floor effects were observed for the SNAIS and its two subscales. The SNAIS and its two subscales exhibited acceptable reliability (Cronbach's alpha = 0.89, 0.90 and 0.60, and test-retest Intra-class Correlation Coefficient = 0.85, 0.87 and 0.67 for Overall scale, SFUI and EFUI subscale, respectively, p<0.001). As expected, the SNAIS and its subscale scores were correlated significantly with emotional connection to social networking, social networking addiction, Internet addiction, and characteristics related to social networking use.The SNAIS is an easily self-administered scale with good psychometric properties. It would facilitate more research in this field worldwide and specifically in the Chinese population

Hypoxia affects in vitro proliferation and differentiation of mouse corneal epithelial progenitor cell

National Natural Science Foundation of China (NSFC) [81100639, U1205025, 81270978, 81000367, 81201276]; Fundamental Research Funds for the Central Universities of China [2011121063]; Xiamen Science and Technology Plan Projects [3502Z20124037, 2011S0589]; Natural Science Foundation of Fujian Province of China [2010D023, 2012J05067]This study was to investigate the proliferation and differentiation of mouse corneal epithelial progenitor cell in hypoxic airlift culture. Mouse corneal epithelial progenitor cell line progenitor cells were cultured under airlift with normoxic and hypoxic conditions for various durations up to 2 wk. Under normoxic conditions when exposed to air, the hyperproliferation and abnormal epidermal-like differentiation of mouse corneal epithelium was induced, whereas when exposed to air under hypoxic conditions, although we observed augmented proliferation, the abnormal differentiation was inhibited. The mechanism by which hypoxia prevents abnormal differentiation may involve downregulation of Wnt signaling pathways, which were inhibited in cells cultured with hypoxic airlift technique. In conclusion, hypoxia can prevent abnormal differentiation while enhancing the proliferation of corneal epithelial cells by blocking Wnt/beta-catenin signaling pathway

Effects of physical activity and use of digital devices on visual acuity in children and adolescents during the COVID-19 pandemic: A cross-sectional study

PurposeTo determine the association between poor visual acuity, the use of digital devices and physical activity (PA) during the COVID-19 pandemic.MethodsA total of 327,646 Chinese children and adolescents were included in the analysis using a cluster random sampling method; this is a case-control study, of those 144,708 children and adolescents with poor visual acuity were included in the case group, while 182,938 who did not have poor visual acuity were included in the control group. A logistic regression model was used to assess the contribution of PA and the use of digital devices to poor visual acuity.ResultsA total of 144,708 children and adolescents experienced poor visual acuity during the COVID-19 pandemic; 54.8% were male, and 55.2% live in rural areas. Compared to controls, children and adolescents with poor visual acuity exhibited more time for the use of digital devices (4.51 ± 2.44 vs. 3.79 ± 2.34 for cases and controls, respectively; P &lt; 0.001) and PA (3.07 ± 0.92 vs. 2.85 ± 1.00 for cases and controls, respectively; P &lt; 0.001). During the COVID-19 pandemic, risk factors related to poor visual acuity among children and adolescents included the use of digital devices (OR 1.135; 95% CI 1.132–1.139), and PA (OR 1.269; 95%CI 1.259–1.278). The results of interaction analysis show that for children and adolescents aged 12 to 17, the positive association between the use of digital devices and poor visual acuity decreased. The interaction effect between PA and digital devices is 0.987.ConclusionsChildren and adolescents were at risk of poor visual acuity during the COVID-19 pandemic. Extended use of the digital devices increased the risk of poor visual acuity, especially for children aged 6–11 years. But the risk of poor visual acuity among children and adolescents decreases as the time spent on PA increases

Description of sample characteristics (<i>n</i> = 910).

<p>Description of sample characteristics (<i>n</i> = 910).</p

Factor loadings and path loadings estimated by exploratory and confirmatory factor analyses for the Social Networking Activity Intensity Scale (SNAIS).

<p>Factor loadings and path loadings estimated by exploratory and confirmatory factor analyses for the Social Networking Activity Intensity Scale (SNAIS).</p

Mean differences of scores of SNAIS, SFUI and EFUI by groups (<i>n</i> = 910).

<p>Mean differences of scores of SNAIS, SFUI and EFUI by groups (<i>n</i> = 910).</p