Dependence of chaotic actuation dynamics of Casimir oscillators on optical properties and electrostatic effects

With Casimir and electrostatic forces playing a crucial role for the performance and stability of microelectromechanical systems (MEMS), the presence of chaotic behavior, which is often unavoidable, leads to device malfunction due to stiction. Therefore, we investigate here how the optical properties of different materials influence the chaotic behavior of electrostatic torsional MEMS due to changes in magnitude of the Casimir forces and torques. We consider the materials Au, which is a good conductor, AIST, which is a phase change material being close to metal in the crystalline state, and finally doped SiC as a very poor conductor. For the conservative systems, there is no chaotic behavior and the analysis of phase portraits and bifurcation diagrams reveal the strong sensitivity of stable actuation dynamics on the material optical properties, while applied electrostatic potentials lead faster to instability and stiction for higher conductivity materials. For the driven systems, the Melnikov method is used to study the chaotic behavior. The results from this method are supported by the study of the contours of the transient time to stiction in the phase plane, which reveal a substantially increased chaotic behavior for higher conductivity materials, associated with stronger Casimir torques and applied electrostatic potentials

Serological Diagnosis of Helicobacter pylori Infection in Patients With a Polycystic Ovary Syndrome

Background: Polycystic Ovary Syndrome (PCOS) is the most common endocrine disorder in 4%-6% of women in the reproductive age and is a common cause of infertility. Even though the number of investigations is scarce, studies show that Helicobacter pylori infection may influence reproduction. Objectives: The purpose of this study was to determine and compare the levels of H. pylori specific antibodies IgA, IgG and anti-CagA at both PCOS and non-PCOS women with their spouses using the serological test. Patients and Methods: In this cross-sectional study, 127 women with their spouses (age range, 30 - 60 years) were selected. These patient were referred to infertility center of Shariati Hospital in Tehran, Iran, with a diagnostic criteria of PCOS based on Androgen Excess Society (AES). The specific antibodies of IgA, IgG and anti-CagA were measured using the commercial Enzyme-Linked Immunosorbent Assay (ELISA) kit. Results: The positive titers of H. pylori antibodies IgA, IgG and anti-CagA in the PCOS group were 45 (35%), 79 (62%) and 77 (60.5%), respectively, while in non-PCOS group were 38 (30%), 76 (60%) and 50 (39.5%), respectively. The sera positive for IgA, IgG and anti-CagA antibodies in spouses of the non-PCOS group were 38 (30%), 84 (66%) and 79 (62%) respectively, but in spouses of the PCOS group were 51 (40%), 83 (66%) and 48 (38%), respectively. The results showed that H. pylori infection probably did not affect infertility or reproduction. Conclusions: Findings of this study demonstrate no significant difference between levels of H. pylori specific antibodies of IgA, IgG, anti-CagA and the presence of PCOS disorders, and also indicate that serologic testing is a sensitive method for the detection of H. pylori antibodies. The high prevalence of H. pylori positive antibody levels in both PCOS and non-PCOS patients can be probably associated with the high frequency of H. pylori infection

A PCA-OLS Model for Assessing the Impact of Surface Biophysical Parameters on Land Surface Temperature Variations

Analysis of land surface temperature (LST) spatiotemporal variations and characterization of the factors affecting these variations are of great importance in various environmental studies and applications. The aim of this study is to propose an integrated model for characterizing LST spatiotemporal variations and for assessing the impact of surface biophysical parameters on the LST variations. For this purpose, a case study was conducted in Babol City, Iran, during the period of 1985 to 2018. We used 122 images of Landsat 5, 7, and 8, and products of water vapor (MOD07) and daily LST (MOD11A1) from the MODIS sensor of the Terra satellite, as well as soil and air temperature and relative humidity data measured at the local meteorological station over 112 dates for the study. First, a single-channel algorithm was applied to estimate LST, while various spectral indices were computed to represent surface biophysical parameters, which included the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), normalized difference water index (NDWI), normalized difference built-up index (NDBI), albedo, brightness, greenness, and wetness from tasseled cap transformation. Next, a principal component analysis (PCA) was conducted to determine the degree of LST variation and the surface biophysical parameters in the temporal dimension at the pixel scale based on Landsat imagery. Finally, the relationship between the first component of the PCA of LST and each surface biophysical parameter was investigated by using the ordinary least squares (OLS) regression with both regional and local optimizations. The results indicated that among the surface biophysical parameters, variations of NDBI, wetness, and greenness had the highest impact on the LST variations with a correlation coefficient of 0.75, −0.70, and −0.44, and RMSE of 0.71, 1.03, and 1.06, respectively. The impact of NDBI, wetness, and greenness varied geographically, but their variations accounted for 43%, 38%, and 19% of the LST variation, respectively. Furthermore, the correlation coefficient and RMSE between the observed LST variation and modeled LST variation, based on the most influential biophysical factors (NDBI, wetness, and greenness) yielded 0.85 and 1.06 for the regional approach and 0.93 and 0.26 for the local approach, respectively. The results of this study indicated the use of an integrated PCA–OLS model was effective for modeling of various environmental parameters and their relationship with LST. In addition, the PCA–OLS with the local optimization was found to be more efficient than the one with the regional optimization

A historical and future impact assessment of mining activities on surface biophysical characteristics change : A remote sensing-based approach

Mining activities and associated actions cause land-use/land-cover (LULC) changes across the world. The objective of this study were to evaluate the historical impacts of mining activities on surface biophysical characteristics, and for the first time, to predict the future changes in pattern of vegetation cover and land surface temperature (LST). In terms of the utilized data, satellite images of Landsat, and meteorological data of Sungun mine in Iran, Athabasca oil sands in Canada, Singrauli coalfield in India and Hambach mine in Germany, were used over the period of 1989-2019. In the first step, the spectral bands of Landsat images were employed to extract historical LULC changes in the study areas based on the homogeneity distance classification algorithm (HDCA). Thereafter, a CA-Markov model was used to predict the future of LULC changes based on the historical changes. In addition, LST and vegetation cover maps were calculated using the single channel algorithm, and the normalized difference vegetation index (NDVI), respectively. In the second step, the trends of LST and NDVI variations in different LULC change types and over different time periods were investigated. Finally, a CA-Markov model was used to predict the LST and NDVI maps and the trend of their variations in future. The results indicated that the forest and green space cover was reduced from 9.95 in 1989 to 5.9 Km(2) in 2019 for Sungun mine, from 42.14 in 1999 to 33.09 Km(2) in 2019 for Athabasca oil sands, from 231.46 in 1996 to 263.95 Km(2) in 2016 for Singrauli coalfield, and from 180.38 in 1989 to 133.99 Km(2) in 2017 for Hambach mine, as a result of expansion and development of of mineral activities. Our findings about Sungun revealed that the areal coverage of forest and green space will decrease to 15% of the total study area by 2039, resulting in reduction of the mean NDVI by almost 0.06 and increase of mean standardized LST from 0.52 in 2019 to 0.61 in 2039. our results further indicate that for Athabasca oil sands (Singrauli coalfield, Hambach mine), the mean values of standardized LST and NDVI will change from 0.5 (0.44 and 0.4) and 0.38 (0.38, 0.35) in 2019 (2016, 2017) to 0.57 (0.5, 0.47) and 0.33 (0.32, 0.28), in 2039 (2036, 2035), respectively. This can be mainly attributed to the increasing mining activities in the past as well as future years. The discussion and conclusions presented in this study can be of interest to local planners, policy makers, and environmentalists in order to observe the damages brought to the environment and the society in a larger picture.Peer reviewe

Chronic neurological diseases and COVID-19: Associations and considerations

The 2019 novel coronavirus pandemic, severe acute respiratory syndrome CoV-2 (COVID-19), has been a worldwide urgent public health threat, resulting in six-hundred seventy thousand deaths to date. The COVID-19 pandemic has led to a series of public health challenges. One such challenge is the management of diseases such as chronic neurological diseases during an epidemic event. COVID-19 affects all kinds of people, including older people with chronic underlying diseases, who are particularly at risk of severe infection or even death. Chronic neurological diseases such as epilepsy, dementia, Parkinson’s disease (PD), and multiple sclerosis (MS) are frequently associated with comorbidities; thus, these patients are in the high-risk category. Therefore, in this article, we review associations and challenges the people with epilepsy, dementia, PD, and MS faces during the COVID-19 pandemic and suggest approaches to provide consensus recommendations on how to provide the best possible care

Frequency of Metabolic Syndrome in Patients with Chronic Obstructive Pulmonary Disease

Background and purpose: There are controversies on the relationship between metabolic syndrome and chronic obstructive pulmonary disease (COPD). The present study was done to determine the frequency of metabolic syndrome in male patients with COPD as well as the associated illnesses and the symptoms of the disease. Materials and methods: In a cross-sectional survey in Qazvin University of Medical Sciences, 2014, a total of 80 COPD men (33-87-year-old) were enrolled. For all patients, demographic characteristics were recorded, a spirometric examination was done, and metabolic syndrome indicators, systemic inflammation (CRP) levels, and CHARLSON index were measured. We used regression analysis, independent t-test, and ANOVA to analyze the data. Results: The rate of metabolic syndrome was 37.5% in COPD patients. Patients with metabolic syndrome had more severe COPD, higher use of inhaled steroids, and fewer Forced expiratory volume in the first second (FEV1) than those who did not have metabolic syndrome (P<0.05). Diabetes (P= 0.009) and cardiac disorders (P= 0.023) showed a significant association with metabolic syndrome. Among the components of the metabolic syndrome, waist circumference, hypertension, and CRP had a significant association with airway obstruction (P<0.05). Conclusion: The prevalence of metabolic syndrome was high in COPD patients. We also found an association between the airflow obstruction in more severe COPD stages and metabolic syndrome, hypertension, and waist circumference. Keywords: metabolic syndrome, chronic obstructive pulmonary disease, hypertension, waist circumferenc

Direct Carotid-Cavernous sinus Fistula Following Closed Head Injury

A case of direct carotid-cavernous sinus fistula (CCF) after closed head injury is presented. A22-year-old male presented to the emergency department of Shohada Tajrish Hospital with thechief complaint of blurred vision and pulsatile retro-orbital headache. The patient had closed headinjury due to car accident 2 month ago with lower limb fracture. After a 2-week symptom-freeperiod, he developed scalp and right facial tingling, along with pulsatile retro-orbital headacheand vision problems. His vital signs were within normal limits, but on primary evaluationthe patient orbital and carotid bruits could be recognized. Computed tomography (CT) scanand magnetic resonance imaging (MRI) suggested the carotid-cavernous sinus fistula, whichwas confirmed by brain angiographic imaging findings. Carotid-cavernous sinus fistula is anuncommon condition that is usually caused by head trauma but can advance spontaneously inabout one fourth of patients with CCF. The connection between the carotid artery and cavernoussinus leads to increased pressure in the cavernous sinus and compression of its contents, andfinally advances the clinical symptoms and signs seen. Diagnosis is based on clinical evaluationand neuroimaging techniques. The target of management is to decrease the pressure within thecavernous sinus, which results in gradual recovery of symptoms