14 research outputs found

    Assessment of Trend and Seasonality in Road Accident Data: An Iranian Case Study

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    Background: Road traffic accidents and their related deaths have become a major concern, particularly in developing countries. Iran has adopted a series of policies and interventions to control the high number of accidents occurring over the past few years. In this study we used a time series model to understand the trend of accidents, and ascertain the viability of applying ARIMA models on data from Taybad city. Methods : This study is a cross-sectional study. We used data from accidents occurring in Taybad between 2007 and 2011. We obtained the data from the Ministry of Health (MOH) and used the time series method with a time lag of one month. After plotting the trend, non-stationary data in mean and variance were removed using Box-Cox transformation and a differencing method respectively. The ACF and PACF plots were used to control the stationary situation. Results : The traffic accidents in our study had an increasing trend over the five years of study. Based on ACF and PACF plots gained after applying Box-Cox transformation and differencing, data did not fit to a time series model. Therefore, neither ARIMA model nor seasonality were observed. Conclusion : Traffic accidents in Taybad have an upward trend. In addition, we expected either the AR model, MA model or ARIMA model to have a seasonal trend, yet this was not observed in this analysis. Several reasons may have contributed to this situation, such as uncertainty of the quality of data, weather changes, and behavioural factors that are not taken into account by time series analysis

    A Novel Bio-Chemical Sensor Based on the Microsphere Raman Laser in the Presence of an External Non metallic Mirror

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    In the presence of an external nonmetallic mirror in adjacent of a microsphere resonator each of the resonance frequency of the microsphere is split into two different resonance frequencies. The new frequencies are symmetrical around the microsphere resonance frequency. The upper and lower frequencies are called blue and red shifted modes. Depending on the sign of the difference between the ratio of loss to the Raman gain at the blue and red shifted frequencies, one of these modes is stable and the other one is unstable. In this paper on the basis of this effect, two ultra sensitive biochemical sensor design based on the steady state and transient response is proposed. The sensitivity of the sensor based on the steady state regime of operation has its maximum value when the ratio of loss to the Raman gain of red shifted and blue shifted modes have the same value

    Long-distance high-fidelity continuous-variable quantum key distribution with non-Gaussian operations: An exact closed form solution

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    In this paper, we derive a closed-form expression for the output state of a CV-QKD protocol in the presence of zero-photon catalysis (ZPC) and a quantum scissor (QS). Then, based on this closed-form solution, we use a direct search algorithm to find the appropriate values of input state and QS parameters, which considerably enhance the range and the fidelity of a CV-QKD protocol. In the special case of pure loss channel, the largest range of the protocol is only 6.5% less than the fundamental limit of repeaterless quantum communication. In addition, examination of the protocol for different values of excess noise, reveals that there is a trade-off between range and fidelity, and a high value of fidelity can be obtained at the cost of a slight reduction in protocol range

    Non-invasive Optical Techniques for determination of blood Glucose levels: A Review Article

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    This article reviews the development of non-invasive optical techniques for determination of blood glucose concentrations in diabetic patients. Early diagnosis and daily management are essential for ensuring the healthy life of diabetic patients. The determination of blood glucose concentration with common devices involves the chemical analysis of blood samples, which are obtained by pricking the finger or extracting blood from the forearm. Pain, discomfort, and inconvenience, associated with current invasive methods, have necessitated the investigation of non-invasive measurement techniques. Non-invasive monitoring of blood glucose level offers several advantages, including absence of pain and biohazard materials, non- exposure to sharp objects, increased testing frequency and consequently, tighter control of glucose concentration. Considering these potential advantages commercialization of non-invasive glucose monitoring devices has become a subject of increasing interest. Several optical technologies have the potential to provide viable non-invasive measuring devices. this review study aimed to describe the major optical technologies for non-invasive glucose monitoring and compare their advantages and disadvantages. second scenario) better than other methods in presence of a typically low false positive rate equal to 3%

    Determining the Effective Factors on Gastric Cancer Using Frailty Model in South-East and North of Iran

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    Background and Purpose: Gastric cancer is the third leading cause of mortality in Iran after cardiovascular diseases and accidents. The aim of the present study was to assess survival and it’s affecting factors in gastric cancer patients through using Cox and parametric models along with frailty. Materials and Methods: In this study, the medical records of gastric cancer patients treated from 2008 to late 2010 were collected in Afzalipour and Bahonar Hospitals in Kerman and Imam Khomeini Hospital in Sari. 383 patients entered the study and were followed up for at least five years. The survival of patients was assessed by using Cox proportional hazard, log-normal and log-logistic models under gamma and inverse-Gaussian distributions, as two special models for frailty. Models efficiency comparison criteria were Akaike information criterion and Cox-Snell residuals. Results: Out of 196 patients in Kerman, 132(67.3%) were males and 64(32.7%) were females. The average age of the patient was 61yr and 59 yr for the males and females, respectively. Also, the survival rates after 1, 3, and 5 years of the diagnosis were 62%, 50%, and 45%, respectively. In the city of Sari, 69% (129 people) of the patients were male and 31% were female. The mean ages of male and female were 66 and 62 yr, respectively. At the same time, 1, 3, and 5 year survival rates of patients were 58%, 36%, and 30%, respectively. Based on Akaike information criterion, Cox-Snell residuals, and non-monotonic failure rate, log-logistic model along with gamma frailty was more fitted in comparison with other models. Using this model, radiotherapy, heartburn, and tumor grade were found as significant predictors. Conclusion: Radiotherapy, heartburn, and tumor grade could be considered as more affected factors. According to rejection of the proportional hazard assumption, assessments of residual figures, and according to non-significant frailty effect by log-normal model, log-logistic model along with gamma frailty was found to be the best fitted model

    PLASMA HOMOCYSTEINE CONCENTRATIONS IN YOUNG PATIENTS WITH ACUTE MYOCARDIAL INFARCTION

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    &nbsp; Abstract INTRODUCTION: Most studies indicate that increased plasma homocysteine level is a risk factor for coronary artery disease. However, data concerning the role of homocysteine in young patients with acute myocardial infarction (AMI) is scanty. The aim of this study was to study the possible association between homocysteine plasma levels and early-onset AMI. methods: This case-control study included 83 AMI patients and 83 healthy controls. Biochemical parameters were determined and homocysteine was measured by enzyme immunoassay. Multivariate logistic regression analysis was used to test the association of homocysteine with the occurrence of AMI. results: Homocysteine concentration in patients with AMI was higher than in controls (19.54&plusmn;13.3 and 15.54&plusmn;8.9 &micro;mol/l, respectively, P=0.002). Hyper-homocysteinemia was associated with early myocardial infarction (odds ratio=5.05). Hypercholesterolemia (OR=4/21), opium addiction (OR=4/78) and age (OR=1/24) also had associations with AMI. CONCLUSIONS: Our results showed that homocysteine levels are elevated in young patients with AMI, and hyperhomocysteinemia is associated with early myocardial infarction; hence it should be evaluated in all young patients with AMI. &nbsp; &nbsp; Keywords: Homocysteine, Acute myocardial infarction, young, risk factor.</div

    Terahertz twisted beams generation in plasma

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    The resonant vortex terahertz beam generation by the cross-focusing of two twisted coaxial laser beams is investigated. For the resonant excitation of terahertz radiation, the rippled density in plasma and the ripple wave number is suitably chosen to satisfy the phase matching condition. The nonlinear current density at terahertz frequency arises due to the spatial variation of two Laguerre-Gaussian coupled field. The terahertz intensity scales as the ponderomotive force of laser beams which imparts an oscillatory velocity to the electrons and, in fact, input Laguerre-Gaussian laser beams properties such as vortex charge number and beam waist. Various laser and plasma parameters are employed to yield vortex terahertz radiation with higher efficiency. Also, it is shown that when the beating frequency approaches plasma frequency, the amplitude of THz radiation increases
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