Ohmic Contact to Two-Dimensional Nanofabricated Silicon Structures with a Two-Probe Scanning Tunneling Microscope.

We used multiprobe scanning tunneling microscope (STM) to fabricate and electrically characterize nanostructures on Si surfaces. We overcame resistive contacts by using field evaporation to clean tip apexes in order to create Ohmic contact with the Si surface states on a Si substrate. A two-probe (2P-) STM with Ohmic contact allowed for measurement at very low bias, limiting conduction through space-charge layer and bulk states. The Ohmic 2P-STM measurement clarified the surface conductivity of the Si(111)-(7 × 7) surface. We also confirmed that Ohmic 2P-STM can be replaced with more convenient Ohmic one-probe STM for the conductance measurements on the Si surface. We prepared nanostructures using STM lithography to define electronically isolated two-dimensional (2D) regions with various aspect ratios. Their surface conduction properties are described well by the conventional sheet model, proving the diffusive 2D conduction on the Si surface. Constrictions and breaks in 2D structures were also evaluated. Ohmic 2P-STM will be helpful for the investigation of exploratory atomic-scale circuitry or cutting-edge materials sciences.

The significance of coronary artery calcium score as a predictor of coronary artery stenosis in individuals referred for CT angiography.

Introduction: Cardiovascular diseases, including coronary artery disease (CAD), are among the most common causes of death in the elderly population. Recent studies have found that coronary artery calcium score (CACS) is a strong independent predictor of CAD. Here we aimed to investigate the association between CACS and demographic, clinical, laboratory, and CT angiographic findings inpatients with suspected CAD. Methods: From June 2008 to August 2018, we retrospectively reviewed 219 consecutive patients suspected with CAD who were referred for CT angiography in Rajaie Cardiovascular, Medical, and Research Center. Medical records were reviewed, and relevant demographic, clinical, laboratory and imaging were collected. Results: A total of 219 patients with an average age of 62.64±12.39 were included. Twelve patients(5.5%) had normal coronary angiography, and 50.2% had mild CAD. An obstructive CAD was found in97 patients (44.3%). The median CACS was 76.4 (IQR, 13.0-289.1). The frequency of obstructive CAD was 28.1% in the CACS <100 group, and 67.0% in CACS >100 group (P < 0.001). On multiple logistic regression analysis, age (OR=1.04 [1.01-1.07], P = 0.006), CACS (OR= 4.31 [2.33-7.98], P < 0.001), and neutrophil to lymphocyte ratio (NLR) (OR = 0.82 [0.68-0.98], P = 0.027) were independent predictors of obstructive CAD. Conclusion: We found a direct association between higher CACS and obstructive patterns in coronary CT angiography. Our findings indicate that the possibility of the presence of obstructive CAD was higher among symptomatic patients with older age, lower NLR, and CACS >100.

Epidemiologic study of traffic crash mortality among motorcycle users in Iran (2011-2017).

PURPOSE: Motorcycle accident is a major cause of road traffic injuries and the motorcyclists are considered as vulnerable road users. The present study aimed to determine the epidemiological characteristics of fatal motorcycle crashes in Iran. METHODS: In this cross-sectional study, a total of 28,356 motorcycle traffic fatalities registered in the Legal Medicine Organization of Iran were analyzed during the period between March 2011 and March 2017. The examined variables included demographic characteristics, helmet use, crash mechanisms, crash location, position state, type of counterpart vehicle, cause of death and place of death. In the study, road traffic mortalities involving drivers and/or passenger of motorcycles were included. Cases or events registered without these conditions were excluded from the study. To analyse the data, SPSS statistics 25 and GraphPad Prism 8 softwares were used. RESULTS: Of the 122,682 fatal traffic injury cases, 28,356 (23.1%) were motorcycle users, of whom 95.3% were male and 4.7% were female. Most of the motorcycle fatalities belonged to the age group of 18-24 years (29.1%). Head trauma was the major cause of death (59.0%). Also, the overall proportion of safety helmet use among motorcycle crash victims was estimated at 37.4%. Most of the road traffic crash cases (46.8%) happened out of city and half of people (49.9%) died in hospital. About 77.4% of the victims were motorcycle riders and 21.1% were pillion passengers. The highest rate of mortality belonged to the self-employed (38.4%) and then workers (21.8%) and students (10.2%). In addition, most fatalities occurred in people with low education (77.5%) and the least occurred in university graduates (5.5%). Among 31 provinces of Iran, Fars had the highest (9.3%) occurrence rate and Kohgiluyeh and Buyer-Ahmad had the lowest (0.5%). Most of the crash mechanisms were due to motorcycle-vehicle crashes (80.2%), followed by rollover (9.8%). CONCLUSION: Comprehensive public education and special rules are needed to reduce the rate of deaths in motorcycle crashes.

Short sleep is associated with higher prevalence and increased predicted risk of cardiovascular diseases in an Iranian population: Fasa PERSIAN Cohort Study.

Cardiovascular disease (CVD) is the leading cause of death worldwide. One common factor that may affect CVD risk factors is sleep disturbance. The factors influencing an individual's sleep may vary among different cultures. The current study investigated sleep quality and quantity in the Fasa cohort population as an Iranian population. In a cross-sectional study using the Fasa PERSIAN cohort study data, 10,129 subjects aged 35-70 were entered. Self-reported sleep duration and cardiovascular events were recorded. The Framingham risk score (FRS) is used to predict cardiovascular events. Adjusted logistic regression showed significant odds ratios in subjects who sleep less than 6 hours for CVD (OR = 1.23; 95% CI:1.03-1.48), coronary heart disease (CHD) (OR = 1.21; 95% CI:1.009-1.46), and hypertension (HTN) (OR = 1.37; 95% CI:1.16-1.62). Higher risk profiles were also seen in the FRS for short sleepers. The highest significant odds ratios in FRS profiles in the intermediate high-risk group compared with the low-risk group were (1.44; 95% CI:1.18-1.75) in CVD and (1.48; 95% CI:1.16-1.88) in CHD risk score profiles. It can be suggested that participants with short durations of sleep had significantly higher CVD, HTN prevalence, and 10-year FRS. Participants with long sleep durations had no increase in CVD, CHD, myocardial infarction (MI), or HTN prevalence. MI prevalence was at the lowest level in subjects who got 8 to 8.9 hours of sleep.

Quantum plasmonic epsilon near zero: field enhancement and cloaking.

We investigate the effect of the electron wave function producing permittivity (epsilon) near zero in sub-nanometer gaps and at surfaces. The field enhancement is calculated for gaps and nanoparticles, as well as the absorption from nanoparticles. Our modified quantum corrected model shows reduced absorption for nanoparticles due to "cloaking" of the epsilon near zero region, which has lower loss than the bulk region. We demonstrate that a modified quantum corrected model finite-difference time-domain simulation of metal slits with sub-nanometer gaps are in good agreement with the analytic expression for the quantum corrected plasmonic resonance wavelength as a function of gap size coming from Re{ε} = 0.

Evaluating the temporal trend of completed suicides referred to the Iranian Forensic Medicine Organization during 2006-2010.

OBJECTIVE: The objective of the present study was to determine the temporal trend of the rate of completed suicides in Iran during 2006-2010. MATERIAL AND METHODS: Data on completed suicides were collected from the national suicide registry of the Iranian Forensic Medicine Organization. The rates were calculated for males and females for each year of the study period, from which the temporal trends were determined. Statistical analyses were conducted using SPSS software, using chi-squared and analysis of variance (ANOVA) tests. RESULTS: The overall rate of suicide was 4.7/100,000, with a male/female ratio of 2.4. The mean age of suicide was 31.9 years, which was significantly higher in males. Hanging was the most common method, followed by poisoning and self-immolation. During the study period, the rate of drug poisoning almost doubled, while that of firearms halved. The rates of hanging and self-immolation also increased in the last years of the study period. CONCLUSION: According to the results of this study, it can be concluded that Iran has had a constant rate of completed suicides over the past decade. Our study also indicated the need for future nationwide studies on the risk factors of suicidal behavior and on different suicide methods in the entire Iranian population.

Association between suicide method, and gender, age, and education level in Iran over 2006-2010.

INTRODUCTION: We aimed to evaluate the relationship between suicide method, and gender, age, and level of education in a nationwide study in Iran over the period from 2006 to 2010. METHODS: Data on completed suicide cases referred to all forensic medicine centers throughout the country that were approved by an autopsy test were collected using data collection forms, which were filled out by the family members in interview sessions. Then, statistical analyses were performed using analysis of variance and chi-square tests, as well as logistic regression analysis. RESULTS: Hanging is more popular among men (62.9% versus 27.7%), while self-burning is preferable for women (39% versus 7%) (P < 0.0001). Younger individuals more frequently adopt a highly violent method, firearms (mean age of 27.1), while older persons more often use hanging and poisoning (mean ages of 32.4 and 32.1, respectively) (P < 0.0001). Hanging and self-burning are more frequently used by persons with lower levels of education, whereas poisoning is more popular with more educated individuals (P < 0.0001). DISCUSSION: All of the studied variables, that is, gender, age, education level, are critical risk factors of adopting different suicide methods in an Iranian population. Future work is necessary to explore the psychopathology adopting different suicide methods in the Iranian population.

The Association between Completed Suicides and Season of the Year in an Iranian Population.

BACKGROUND: The main objective of the present study was to determine the association between completed suicides and season of the year in Iran during 2006-2010. METHODS: Data on completed suicides were collected by questionnaires field out by the family members of the victims in Legal Medicine Centers throughout the country over the period from 2006 to 2010. The maximum number of completed suicides (380) was observed in August, while the minimum number (231) was reported in February. RESULTS: Season-wise, completed suicides were most prevalent in summer (1040), whereas least prevalent in winter (726). Mean (SD) age of individuals having committed suicide was 31.5 (14.6) years. This value did not change significantly in different seasons (P=0.051); nor, was a statistically significant difference observed in the educational level and the reason for suicide across different seasons of the year. Self-immolation and toxic poisoning were found to be significantly less common in autumn and winter (P<0.05), respectively. The number of completed suicides was higher in warm seasons. CONCLUSION: Season of the year had significant relationships with gender as well the method of suicide, while no significant association was observed for age, level of education, and reason for suicide.