27 research outputs found

    A Branching Process for Convergent Product Optimization

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    We consider a discrete time branching process where the population consists of k types of convergent products, an action is chosen for that which affects the lifetime, the number and types of its functions, and the profit received. The problem of maximizing the expected profit is shown to be equivalent to a generalized Markov decision problem of maximizing the expected profit is shown to be equivalent to a generalized Markov decision problem where the  transition matrices are non-negative but not necessarily sub stochastic

    Identification and Prioritization Effective Inter-Project and Environmental Challenges on Implementation of Project Management System (Case study: Projects of Pars Special Economic Energy Zone)

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    Project performance depends on performance of its administrative organizations. Obviously, maturity level of these organizations depends on various internal and environmental factors. Defect in each factor can disturb project performance and accomplishment of its purposes. This article aims on identification and prioritization effective environmental and inter-project challenges on implementation of project management system. It calculated each choice distance by Fuzzy ideal solution and Fuzzy anti-ideal solution by TOPSIS method and finally proximity index coefficient of each choice was calculated to indicate choices ranking. Higher values of proximity coefficients mean more proximity to Fuzzy ideal solution and more distance from Fuzzy anti-ideal solution.  Statistical population of this study is limited to 40 people; therefore, 40 ones were selected as responders and sampling was avoided. Research results have shown that prioritization of criteria from first to the third is cost management, time management, and quality management in projects. According to ongoing challenges of each project including strategic, operational, and environmental factors, these choices are ranked

    Presenting of safety performance assessment pattern of road trucks

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    Background and aim: hazardous materials transport is one of the most important problems in developing countries. The accidents involving the fleet of hazardous materials transport can have irreparable consequences. The study was aimed to present safety performance assessment pattern of road trucks with risk assessment approach. Methods: This is a descriptive study. In this study, the Accidents of road trucks with fix tank were studied during a 10-year period (1384-1394).The safety criteria and sub-criteria with respect to technical characteristics of road trucks divided in two categories: “Inductive factors of human error” and “Non-inductive factors of human error” In order to determine the final criteria and sub criteria and weighting them, the team of experts and FAHP method was used. Result: The results showed that the most important effective criterion on safety performance of road truck is “Inductive factors of human error”. Also, the most important effective sub-criteria are “Brake system and their connections”, “Ventilation system” and “Technical inspections”. With respect to the pattern “Hino, Mack, Howo 6×4(10 wheels), Dangfeng” trucks have received the lowest safety level. Conclusion: The causes of low safety level in fleet of hazardous materials transport in Iran, are the lack of timely inspections and inefficiencies in the technical equipment of the trucks such as “malfunction of ventilation and Brake system and their connections” which it’s most important reason is non-commitment of Iran to ADR agreement. &#160

    Fluorescence devices for the detection of dental caries

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    BACKGROUND: Caries is one of the most prevalent and preventable conditions worldwide. If identified early enough then non‐invasive techniques can be applied, and therefore this review focusses on early caries involving the enamel surface of the tooth. The cornerstone of caries detection is a visual and tactile dental examination, however alternative methods of detection are available, and these include fluorescence‐based devices. There are three categories of fluorescence‐based device each primarily defined by the different wavelengths they exploit; we have labelled these groups as red, blue, and green fluorescence. These devices could support the visual examination for the detection and diagnosis of caries at an early stage of decay. OBJECTIVES: Our primary objectives were to estimate the diagnostic test accuracy of fluorescence‐based devices for the detection and diagnosis of enamel caries in children or adults. We planned to investigate the following potential sources of heterogeneity: tooth surface (occlusal, proximal, smooth surface or adjacent to a restoration); single point measurement devices versus imaging or surface assessment devices; and the prevalence of more severe disease in each study sample, at the level of caries into dentine. SEARCH METHODS: Cochrane Oral Health's Information Specialist undertook a search of the following databases: MEDLINE Ovid (1946 to 30 May 2019); Embase Ovid (1980 to 30 May 2019); US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov, to 30 May 2019); and the World Health Organization International Clinical Trials Registry Platform (to 30 May 2019). We studied reference lists as well as published systematic review articles. SELECTION CRITERIA: We included diagnostic accuracy study designs that compared a fluorescence‐based device with a reference standard. This included prospective studies that evaluated the diagnostic accuracy of single index tests and studies that directly compared two or more index tests. Studies that explicitly recruited participants with caries into dentine or frank cavitation were excluded. DATA COLLECTION AND ANALYSIS: Two review authors extracted data independently using a piloted study data extraction form based on the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS‐2). Sensitivity and specificity with 95% confidence intervals (CIs) were reported for each study. This information has been displayed as coupled forest plots and summary receiver operating characteristic (SROC) plots, displaying the sensitivity‐specificity points for each study. We estimated diagnostic accuracy using hierarchical summary receiver operating characteristic (HSROC) methods. We reported sensitivities at fixed values of specificity (median 0.78, upper quartile 0.90). MAIN RESULTS: We included a total of 133 studies, 55 did not report data in the 2 x 2 format and could not be included in the meta‐analysis. 79 studies which provided 114 datasets and evaluated 21,283 tooth surfaces were included in the meta‐analysis. There was a high risk of bias for the participant selection domain. The index test, reference standard, and flow and timing domains all showed a high proportion of studies to be at low risk of bias. Concerns regarding the applicability of the evidence were high or unclear for all domains, the highest proportion being seen in participant selection. Selective participant recruitment, poorly defined diagnostic thresholds, and in vitro studies being non‐generalisable to the clinical scenario of a routine dental examination were the main reasons for these findings. The dominance of in vitro studies also means that the information on how the results of these devices are used to support diagnosis, as opposed to pure detection, was extremely limited. There was substantial variability in the results which could not be explained by the different devices or dentition or other sources of heterogeneity that we investigated. The diagnostic odds ratio (DOR) was 14.12 (95% CI 11.17 to 17.84). The estimated sensitivity, at a fixed median specificity of 0.78, was 0.70 (95% CI 0.64 to 0.75). In a hypothetical cohort of 1000 tooth sites or surfaces, with a prevalence of enamel caries of 57%, obtained from the included studies, the estimated sensitivity of 0.70 and specificity of 0.78 would result in 171 missed tooth sites or surfaces with enamel caries (false negatives) and 95 incorrectly classed as having early caries (false positives). We used meta‐regression to compare the accuracy of the different devices for red fluorescence (84 datasets, 14,514 tooth sites), blue fluorescence (21 datasets, 3429 tooth sites), and green fluorescence (9 datasets, 3340 tooth sites) devices. Initially, we allowed threshold, shape, and accuracy to vary according to device type by including covariates in the model. Allowing consistency of shape, removal of the covariates for accuracy had only a negligible effect (Chi(2) = 3.91, degrees of freedom (df) = 2, P = 0.14). Despite the relatively large volume of evidence we rated the certainty of the evidence as low, downgraded two levels in total, for risk of bias due to limitations in the design and conduct of the included studies, indirectness arising from the high number of in vitro studies, and inconsistency due to the substantial variability of results. AUTHORS' CONCLUSIONS: There is considerable variation in the performance of these fluorescence‐based devices that could not be explained by the different wavelengths of the devices assessed, participant, or study characteristics. Blue and green fluorescence‐based devices appeared to outperform red fluorescence‐based devices but this difference was not supported by the results of a formal statistical comparison. The evidence base was considerable, but we were only able to include 79 studies out of 133 in the meta‐analysis as estimates of sensitivity or specificity values or both could not be extracted or derived. In terms of applicability, any future studies should be carried out in a clinical setting, where difficulties of caries assessment within the oral cavity include plaque, staining, and restorations. Other considerations include the potential of fluorescence devices to be used in combination with other technologies and comparative diagnostic accuracy studies

    Relocation of facility location based on the inactive defense approach in humanitarian aid logistics

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    In recent years, the increased incidence of natural disasters with irreparable damage to people has led to various efforts to reduce its destructive effects and consequences. Hence, humanitarian aid logistics are aimed at preserving life and reducing the suffering of people in crises. Facility location is a strategic issue in humanitarian logistics and has a planning role before the crisis. Finding the right place for establishment of the facilities can help relieve the disaster. This research is also based on the principles of non-operational defense and the design of a multi-objective mathematical model for seeking a suitable location for the facility. In this mathematical model based on four population density indexes, user appropriateness, access to the road and enclosure of the appropriate location for the establishment of a hospital, temporary care centers, shelters and warehouses is selected. The designed model is solved using Lexicographic method and via GAMS software

    Investigating the Efficiency of Combined Cycle Power Plants with the Data Envelopment Analysis Process (with an Emphasis on Air Pollution)

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    Performance management is one of the most significant strategies in promoting the efficiency of organizations and is highly sensitive. It is important to check the efficiency of combined cycle power plants because of their major contribution to power generation and air pollution. This study was conducted to evaluate the economic and environmental efficiency of Combined Cycle Power Plants (CCPPs). The inputs and outputs required to evaluate the performance of the power plants were determined according to expert opinions. Then, the 7-year statistics and information of the Qom, Neishabour, Shahid Rajaee, Yazd and Kerman power plants were collected as the desired CCPPs in Iran. The Window Data Envelopment Analysis (WDEA) method was used for evaluating the efficiency of the power plants. The 3-year window length showed that most of the power plants were efficient. Only the Rajaee, Neishabour and Yazd power plants were ineffective in some years. The mean efficiency of the power plants in the 4-year window length showed that the plants were efficient from 2008 to 2010

    The Effects of Education Based on the Nursing Process on Ostomy Self-Care Knowledge and Performance of Elderly Patients with Surgical Stoma

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    Background. Patients with surgical stoma experience problems, which can lead to their impaired adaptation and self-efficacy. The nursing process provides a framework for planning and implementing nursing care. This study aimed to investigate the effect of education based on the nursing process on ostomy self-care knowledge and performance of elderly patients with intestinal stoma. Materials and Methods. In this quasi experimental study, 52 elderly patients with intestinal ostomy who were referred to Razi Hospital in Rasht and met the inclusion criteria were invited to participate in research. Sampling was done by a simple random method. The intervention group received an educational programme based on the nursing process, whereas the control group received traditional training. The research instruments included a questionnaire to assess the level of ostomy self-care knowledge and ostomy self-care performance. Data were analyzed by SPSS software version 21 using descriptive and inferential statistics at a significant level of p<0.05. Results. The mean scores of ostomy self-care knowledge and performance in both groups (intervention and control) were increased. However, the improvement in self-care knowledge and performance of the intervention group was significantly greater than that in the control group (p<0.001). Conclusions. The educational programme based on the nursing process compared to the routine patients training caused more improvement in ostomy self-care knowledge and performance of older adult patients with surgical stoma. Therefore, an educational programme based on the nursing process can be used as an educational model for these patients
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