Surface coupling effects on the capacitance of thin insulating films

A general form for the surface roughness effects on the capacitance of a capacitor is proposed. We state that a capacitor with two uncoupled rough surfaces could be treated as two capacitors in series which have been divided from the mother capacitor by a slit. This is in contrast to the case where the two rough surfaces are coupled. When the rough surfaces are coupled, the type of coupling decides the modification of the capacitance in comparison to the uncoupled case. It is shown that if the coupling between the two surfaces of the capacitor is positive (negative), the capacitance is less (higher) than the case of two uncoupled rough plates. Also, we state that when the correlation length and the roughness exponent are small, the coupling effect is not negligible

Quantum Bohmian-inspired potential to model non–Gaussian time series and Its application in financial markets

We have implemented quantum modeling mainly based on Bohmian mechanics to study time series that contain strong coupling between their events. Compared to time series with normal densities, such time series are associated with rare events. Hence, employing Gaussian statistics drastically underestimates the occurrence of their rare events. The central objective of this study was to investigate the effects of rare events in the probability densities of time series from the point of view of quantum measurements. For this purpose, we first model the non-Gaussian behavior of time series using the multifractal random walk (MRW) approach. Then, we examine the role of the key parameter of MRW, λ, which controls the degree of non-Gaussianity, in quantum potentials derived for time series. Our Bohmian quantum analysis shows that the derived potential takes some negative values in high frequencies (its mean values), then substantially increases, and the value drops again for rare events. Thus, rare events can generate a potential barrier in the high-frequency region of the quantum potential, and the effect of such a barrier becomes prominent when the system transverses it. Finally, as an example of applying the quantum potential beyond the microscopic world, we compute quantum potentials for the S&P financial market time series to verify the presence of rare events in the non-Gaussian densities and demonstrate deviation from the Gaussian case

Spectra of empirical autocorrelation matrices: A random-matrix-theory–inspired perspective

We construct an autocorrelation matrix of a time series and analyze it based on the random-matrix theory (RMT) approach. The autocorrelation matrix is capable of extracting information which is not easily accessible by the direct analysis of the autocorrelation function. In order to provide a precise conclusion based on the information extracted from the autocorrelation matrix, the results must be first evaluated. In other words they need to be compared with some sort of criterion to provide a basis for the most suitable and applicable conclusions. In the context of the present study, the criterion is selected to be the well-known fractional Gaussian noise (fGn). We illustrate the applicability of our method in the context of stock markets. For the former, despite the non-Gaussianity in returns of the stock markets, a remarkable agreement with the fGn is achieved

Serum Zinc level and liver pathological grading correlation in nonalcoholic steatohepatitis, in a university hospital in Tehran

Background: Nonalcoholic fatty liver disease (NAFLD) includes steatosis, nonalcoholic steatohepatitis, fibrosis and liver cirrhosis. The oxidative stress enzymes are the diagnostic markers to prediction of histologic status of liver in nonalcoholic steatohepatitis disease. The aim of the study was to assessment of relationship between serum Zinc (Zn) levels with pathologic manifestation in patients with nonalcoholic steatohepatitis. Methods: This cohort study was done in patients with nonalcoholic steatohepatitis that had been visited in gastrointestinal clinic of Sina Hospital, Tehran, Iran from April, 2014 to April, 2015. Control group included the patients with no clinical manifestation of nonalcoholic steatohepatitis and normal liver ultrasonography, lab test and liver biopsy. Serum Zn level was measured with atomic absorption spectroscopy. Normal Serum level of Zn was considered 10.7-22.9 µmol/L (70-150 µg/dL) and less than 7 µg/dL was considered as Zn deficiency. Pathological findings were grading according to NAFLD activity score. Results: One hundred twenty patients were selected for the study in two equal groups. Six and 26 patients were excluded in case and control groups, respectively due to no consent to lab test. Finally, 54 patients (35 male/19 female) and 34 patients (22 male/12 female) in control group were participated in data analysis. The mean age on case and control group was 37.02±9.82 year and 33.24±12.01 year, respectively (P= 0.111). Zn level in case and control groups were 90.82±13.69 and 88.82±13.10, respectively. There were no statistically significant differences between two group in serum Zn level (P= 0.50). Also, there were no statistically significant differences between pathological grading in case group participants (steatosis: P= 0.640; Lobular inflammation: P= 0.882; fibrosis: P= 0.531). Conclusion: The finding of the study showed no significant association between serum zinc level and hepatic steatosis, lobular inflammation and fibrosis of the liver in nonalcoholic steatohepatitis