Sensitivity to Heavy Neutral Leptons with the SAND detector at the DUNE ND complex

Heavy Neutral Leptons (HNLs) have been an interesting topic for experimental particle physics in the past few years. A study has been performed within the framework of the multi-instrument DUNE near detector complex, specifically regarding the on-Axis System, to assess the sensitivity to HNL within six years of exposure. By utilizing two MC generators, and charmed heavy meson decay channels, the sensitivity to HNL masses between 0.3 and 1.8 GeV/$c^2$ has been explored. A Mad-Graph/Mad-Dump model has been implemented based on the $\nu MSM$ Lagrangian, and used to obtain accurate kinematics for the decay of mesons and HNL. The simulated final-state particles have been propagated through the detector; a track reconstruction algorithm, based on the Kalman Filter technique, along with a simple two-body decay selection, is implemented to estimate efficiency and background rejection. The HNL sensitivity has been estimated both from purely phenomenological as well as experimental point of view, reaching O($10^{-9}$) for higher HNL masses, with about a factor 3 deterioration between the phenomenological and the experimental case. In this paper, the results for direct and indirect decay channels of charmed meson $D_s$ to HNL has been investigated and the potential for further improvements has been discussed.Comment: General revisio

Flow boiling heat transfer characteristics of R245fa refrigerant in a plate heat exchanger

Plate heat exchangers (PHEs) are used extensively in industrial applications and, owing to their compactness, and higher thermal efficiency, they are keys component of organic Rankine cycle (ORC) application. This study presents the experimental heat transfer characteristics during flow boiling of R245fa refrigerant with a commercial working fluid used in ORCs; inside brazed plate heat exchanger with chevron angle of 65 degree. The flow boiling heat transfer characteristics were measured with varying saturation temperatures, mass flux and heat flux, which range from 55.5 \ub0C-61.8 \ub0C, 15.5-17.4 kg m-2 s-1, and 6400-10120 W m-2, respectively. The experimental results showed that flow boiling heat transfer coefficient is dependent upon the heat flux and mass flux. The results showed that the heat transfer coefficient increases with the increase of heat flux, and then starts to decrease due to local dry out. However, at low mass flux, locally triggering dry out was more prominent than that high mass flux. The heat transfer coefficient showed to be sensitive to the change in the saturation temperature. Moreover, flow boiling heat transfer coefficient showed a linear relationship with mass flux of the refrigerant

Effects of Smoking Cessation Counseling Based on the Stages of Change Model in a Dental School Setting: A Semi-Experimental Study

Objectives The present study aimed to evaluate the effects of smoking cessation counseling by a dentist on the smokers’ preparation for change to quit smoking. Methods This study was performed on 150 smokers, admitted to the Dental School of Shahid Beheshti University of Medical Sciences, Tehran, Iran. The patients were randomly divided into two groups of 75 participants. The intervention group received smoking cessation counseling by a single senior dental student for 30 min session. The patient’s status in the stages of change was determined at baseline and after the intervention. For statistical analysis, paired t-test, Mann-Whitney U test, and multivariate linear regression analysis were performed at a significance level of P<0.05. Results At baseline, there were no significant differences between the intervention and control groups in terms of the stage of change for smoking cessation. Also, there was no significant difference in the stages of change in the control group between the baseline and one-month follow-up. However, this difference was significant in the intervention group (P=0.006). In other words, the number of patients in the pre-contemplation stage decreased by 43%, the number of patients in the contemplation stage increased by 20%, and the number of patients in the action stage increased by 16%. Conclusion It can be concluded that smoking cessation counseling enhances a person’s forward movement and transition through the stages of change for smoking cessatio

A Study on Gas Evolving Electrodes under Extreme Current Densities

ABSTRACT A Study on Gas Evolving Electrodes under Extreme Current Densities Zahra Ghorbani Electrochemical discharges or electrode effects are used in different fields such as micro-machining, nano-particle production, and surface engineering. Further development and improvement of the different applications of electrochemical discharges require a better understanding of this process. Beyond the critical voltage, an insulating gas film forms around the electrode and discharges take place through the gas film. The stability of the gas film affects the quality of the discharges. The gas film formation is therefore investigated in the present thesis. The main objective of the current project is to attain a better insight into the gas film dynamics. This goal is achieved through the following approaches: 1. The current-voltage characteristics are studied prior to the gas film formation and then compared with a model developed based on the percolation theory. 2. Since the hydrodynamic forces define the shape and thickness of the gas film, the effect of the hydrodynamic parameters on a gas film are analyzed. Based on the Pi theorem and dimensional analysis, important dimensionless parameters are derived to investigate the gas film formation. 3. Different system configurations are examined to improve the electrochemical discharge activity. Visual observations indicate that stable discharges are obtained by using a covered electrode and applying an offset pulsed voltage. Key words: Electrochemical discharges, Gas film formation time, Gas film thickness, Gas bubble evolutio

Oil Spill Detection Using Deep Neural Networks

Oil spills have catastrophic effects on the environment, wildlife, economy, and human health. Therefore, timely detection of oil spills can reduce these disastrous impacts. Existing oil spill detection practices include in-situ (e.g., acoustic method, vapor sampling, pressure-point-analysis, and negative pressure wave) and remote sensing methods (e.g., traditional image processing and image processing using artificial intelligence). These methods rely mostly on skilled personnel for data collection, processing, and analysis, thus leading to slow, costly, and subjective results. Furthermore, oil platforms and pipelines are often situated in remote, harsh areas, making inspections hazardous. To remedy this problem, in this Thesis, three state-of-the-art artificial intelligence (AI) models, namely VGG16, YOLOv3 (you-only-look-once), and mask R-CNN (mask region-based convolutional neural network) are used in a transfer learning scheme to facilitate the process of detecting oil spills and surrounding objects such as vessels and oil rigs. Keyword search, a semi-supervised machine learning approach, is used to collect red-green-blue (R-G-B) imagery for training and testing these models. The methodology includes image classification, object detection, and instance segmentation. The VGG16 model is used to predict the existence of an oil spill in an image, yielding an accuracy of 93%. The YOLOv3 model is implemented to detect and mark the location of vessels and oil rigs. The mean average precision for detecting these two object classes is 61.5% (46% for vessel and 77% for oil rig). The mask R-CNN model is utilized to identify oil spill boundaries at the pixel level in the input image. Results (considering all test images) indicate an average precision of 62%, and an average recall of 71%. Findings of this Thesis are sought to benefit oil and gas industry stakeholders and coastal communities by creating operational AI-assisted technologies for timely detection and response to oil spills and other environmental pollutions, ultimately contributing to human health, environment preservation, and profitability of energy exploration projects

The essential role of hippocampo-cortical connections in temporal coordination of spindles and ripples

The predominant activity of slow wave sleep is cortical slow oscillations (SOs), thalamic spindles and hippocampal sharp wave ripples. While the precise temporal nesting of these rhythms was shown to be essential for memory consolidation, the coordination mechanism is poorly understood. Here we develop a minimal hippocampo-cortico-thalamic network that can explain the mechanism underlying the SO-spindle-ripple coupling indicating of the succession of regional neuronal interactions. Further we verify the model predictions experimentally in naturally sleeping rodents showing our simple model provides a quantitative match to several experimental observations including the nesting of ripples in the spindle troughs and larger duration but lower amplitude of the ripples co-occurring with spindles or SOs compared to the isolated ripples. The model also predicts that the coupling of ripples to SOs and spindles monotonically enhances by increasing the strength of hippocampo-cortical connections while it is stronger at intermediate values of the cortico-hippocampal projections

Investigating Barriers to Promoting Oral Health in Students with hearing impairment from Mothers' Perspective: A Qualitative Content Analysis

Objectives Studies have shown the high prevalence of dental caries, negligence of oral health, and unmet dental care needs among children with hearing impairment compared to their healthy peers. This study was conducted to determine the barriers to oral health of children with hearing impairment from the perspective of their mothers. Methods In this qualitative study, semi-structured interviews were conducted with 19 mothers based on purposive sampling in order to investigate the factors affecting compliance with oral health. Interviews were recorded, handwritten, coded and classified; and for content analysis, Graneheim and Lundman's qualitative approach was used. Results As a result of the data analysis, the three main themes of “the effects of general health status, the effects of instruction and learning, and problems in receiving dental health care services” were identified as barriers to good oral health. Moreover,  nine sub-themes of “inadequate education regarding oral health, parental insufficient supervision, shortages in dentistry service delivery systems, obstacles hindering mother from pursuing services, lack of guidelines for offering free periodical dental examinations for children with special needs, the impact of improper nutritional habits on oral health, children’s mental problems, unfavorable oral health conditions, and  the impact of oral health on the child’s general health" were obtained. Conclusion Inadequate education in the field of oral health and difficulties in receiving dental services were identified as the most important factors affecting oral health in children with hearing impairment from their mothers' perspective.

Perceived oral health among adults in Tehran, Iran; a telephone survey

Objective: In comparison to clinical oral health indices, perceived oral health measures are less applied in large-scale epidemiological oral health studies in Iran. The aim of this study was to measure perceived oral health among adults in Tehran, Iran.Methods: In this cross-sectional study, perceived oral health was measured in 1100 adults in Tehran by two measures: 1- non-replaced extracted teeth, and 2- revised Rand dental health questions including pain, chewing problems and communication problems. Data was gathered by telephone interview using gender, age and level of education as socio-demographic information.Results: The mean number of non-replaced extracted teeth was 1.28 with 53.8% of adults reporting no extracted teeth. Extracted teeth was significantly less in younger (p<0.001) and more educated people (p<0.001). Rand dental health scores increased by age (p<0.001) but had no significant changes in different educational levels. The three items of Rand dental health were highly correlated (p<0.01) with Chronbach’s Alpha=0.73 but were not correlated with extracted teeth.Conclusion: Approximately half of Tehran adults have the experience of lacking one or more teeth, with a small group of them suffering from pain, chewing problems and communication problems

Knowledge, Attitude and Practice of Dental Students in Tehran regarding Hepatitis B, Hepatitis C, and HIV/AIDS

Objectives Healthcare workers including dentists and dental students are at risk of transmission of blood-borne pathogens. Thus, it is imperative to assess their knowledge, attitude and practice regarding the infection control protocols. Methods This cross-sectional study evaluated 164 dental students of Shahid Beheshti University using a self-administered questionnaire. The questionnaire consisted of socio-demographic, knowledge (n=15), attitude (n=27) and performance (n=8) questions regarding hepatitis B, hepatitis C and HIV/AIDS. Data were collected and analyzed using the Kruskal-Wallis and Mann-Whitney U test. Results The mean score of knowledge, attitude and practice regarding hepatitis B, hepatitis C and HIV/AIDS was 18.66 (out of 30), 31.59 (out of 54) and 6.29 (out of 8), respectively. The students had low knowledge level about the routes of transmission, the standard infection control protocols, and infection treatment. They also had poor attitude towards treating the infected patients. There was no significant difference in knowledge, attitude and practice between different academic grades of dental students or males and females. Conclusion The findings did not show satisfactory level of knowledge or attitude of Shahid Beheshti dental students regarding hepatitis B, hepatitis C and HIV/AIDS infections. Thus, more educational programs emphasizing on blood-borne infections are recommended

Effects of Social Media on People’s Tendency Toward Aesthetic Dental Treatments

Objectives This study aimed to investigate the impact of social media on people’s tendency toward aesthetic dental treatments in Iran. Methods This cross-sectional study was performed on 410 individuals, including dentists or dental students and laypeople, who were selected via convenience sampling. A questionnaire, consisting of sociodemographic characteristics, frequency of social media use, tendency toward aesthetic dental treatments, and factors affecting people’s decisions, was completed for data collection. This online questionnaire was created using the Porsline© website and posted on social media. The collected data were analyzed in SPSS version 21, using Chi-square test. A P-value less than 0.05 was considered statistically significant. Results Of 410 participants, 157 (38.3%) were dentists or dental students. Only 38.2% of the participants in the dentist group were willing to receive aesthetic dental treatments, whereas laypeople were significantly more inclined to receive such treatments (69.2%) (P<0.001). Almost half of people who used social media platforms several times a day and also 71.8% of people who used social media once a day or less showed tendency toward aesthetic dental treatments (P=0.01). Conclusion Based on the results, the time spent on social media was not significantly associated with people's tendency to receive aesthetic dental treatments. Also, dentists were less interested in such treatments for themselves