Prospect theory based estimation of drivers' risk attitudes in route choice behaviors.

Science.gov (United States)

Zhou, Lizhen; Zhong, Shiquan; Ma, Shoufeng; Jia, Ning

2014-12-01

This paper applied prospect theory (PT) to describe drivers' route choice behavior under Variable Message Sign (VMS), which presented visual traffic information to assist them to make route choice decisions. A quite rich empirical data from questionnaire and field spot was used to estimate parameters of PT. In order to make the parameters more realistic with drivers' attitudes, they were classified into different types by significant factors influencing their behaviors. Based on the travel time distribution of alternative routes and route choice results from questionnaire, the parameterized value function of each category was figured out, which represented drivers' risk attitudes and choice characteristics. The empirical verification showed that the estimates were acceptable and effective. The result showed drivers' risk attitudes and route choice characteristics could be captured by PT under real-time information shown on VMS. For practical application, once drivers' route choice characteristics and parameters were identified, their route choice behavior under different road conditions could be predicted accurately, which was the basis of traffic guidance measures formulation and implementation for targeted traffic management. Moreover, the heterogeneous risk attitudes among drivers should be considered when releasing traffic information and regulating traffic flow. Copyright © 2014 Elsevier Ltd. All rights reserved.

Developing an objective evaluation method to estimate diabetes risk in community-based settings.

Science.gov (United States)

Kenya, Sonjia; He, Qing; Fullilove, Robert; Kotler, Donald P

2011-05-01

Exercise interventions often aim to affect abdominal obesity and glucose tolerance, two significant risk factors for type 2 diabetes. Because of limited financial and clinical resources in community and university-based environments, intervention effects are often measured with interviews or questionnaires and correlated with weight loss or body fat indicated by body bioimpedence analysis (BIA). However, self-reported assessments are subject to high levels of bias and low levels of reliability. Because obesity and body fat are correlated with diabetes at different levels in various ethnic groups, data reflecting changes in weight or fat do not necessarily indicate changes in diabetes risk. To determine how exercise interventions affect diabetes risk in community and university-based settings, improved evaluation methods are warranted. We compared a noninvasive, objective measurement technique--regional BIA--with whole-body BIA for its ability to assess abdominal obesity and predict glucose tolerance in 39 women. To determine regional BIA's utility in predicting glucose, we tested the association between the regional BIA method and blood glucose levels. Regional BIA estimates of abdominal fat area were significantly correlated (r = 0.554, P < 0.003) with fasting glucose. When waist circumference and family history of diabetes were added to abdominal fat in multiple regression models, the association with glucose increased further (r = 0.701, P < 0.001). Regional BIA estimates of abdominal fat may predict fasting glucose better than whole-body BIA as well as provide an objective assessment of changes in diabetes risk achieved through physical activity interventions in community settings.

Research on the method of information system risk state estimation based on clustering particle filter

Directory of Open Access Journals (Sweden)

Cui Jia

2017-05-01

Full Text Available With the purpose of reinforcing correlation analysis of risk assessment threat factors, a dynamic assessment method of safety risks based on particle filtering is proposed, which takes threat analysis as the core. Based on the risk assessment standards, the method selects threat indicates, applies a particle filtering algorithm to calculate influencing weight of threat indications, and confirms information system risk levels by combining with state estimation theory. In order to improve the calculating efficiency of the particle filtering algorithm, the k-means cluster algorithm is introduced to the particle filtering algorithm. By clustering all particles, the author regards centroid as the representative to operate, so as to reduce calculated amount. The empirical experience indicates that the method can embody the relation of mutual dependence and influence in risk elements reasonably. Under the circumstance of limited information, it provides the scientific basis on fabricating a risk management control strategy.

Research on the method of information system risk state estimation based on clustering particle filter

Science.gov (United States)

Cui, Jia; Hong, Bei; Jiang, Xuepeng; Chen, Qinghua

2017-05-01

With the purpose of reinforcing correlation analysis of risk assessment threat factors, a dynamic assessment method of safety risks based on particle filtering is proposed, which takes threat analysis as the core. Based on the risk assessment standards, the method selects threat indicates, applies a particle filtering algorithm to calculate influencing weight of threat indications, and confirms information system risk levels by combining with state estimation theory. In order to improve the calculating efficiency of the particle filtering algorithm, the k-means cluster algorithm is introduced to the particle filtering algorithm. By clustering all particles, the author regards centroid as the representative to operate, so as to reduce calculated amount. The empirical experience indicates that the method can embody the relation of mutual dependence and influence in risk elements reasonably. Under the circumstance of limited information, it provides the scientific basis on fabricating a risk management control strategy.

Adequacy of relative and absolute risk models for lifetime risk estimate of radiation-induced cancer

International Nuclear Information System (INIS)

McBride, M.; Coldman, A.J.

1988-03-01

This report examines the applicability of the relative (multiplicative) and absolute (additive) models in predicting lifetime risk of radiation-induced cancer. A review of the epidemiologic literature, and a discussion of the mathematical models of carcinogenesis and their relationship to these models of lifetime risk, are included. Based on the available data, the relative risk model for the estimation of lifetime risk is preferred for non-sex-specific epithelial tumours. However, because of lack of knowledge concerning other determinants of radiation risk and of background incidence rates, considerable uncertainty in modelling lifetime risk still exists. Therefore, it is essential that follow-up of exposed cohorts be continued so that population-based estimates of lifetime risk are available

Nonparametric estimation of benchmark doses in environmental risk assessment

Science.gov (United States)

Piegorsch, Walter W.; Xiong, Hui; Bhattacharya, Rabi N.; Lin, Lizhen

2013-01-01

Summary An important statistical objective in environmental risk analysis is estimation of minimum exposure levels, called benchmark doses (BMDs), that induce a pre-specified benchmark response in a dose-response experiment. In such settings, representations of the risk are traditionally based on a parametric dose-response model. It is a well-known concern, however, that if the chosen parametric form is misspecified, inaccurate and possibly unsafe low-dose inferences can result. We apply a nonparametric approach for calculating benchmark doses, based on an isotonic regression method for dose-response estimation with quantal-response data (Bhattacharya and Kong, 2007). We determine the large-sample properties of the estimator, develop bootstrap-based confidence limits on the BMDs, and explore the confidence limits’ small-sample properties via a short simulation study. An example from cancer risk assessment illustrates the calculations. PMID:23914133

Risk Estimates and Risk Factors Related to Psychiatric Inpatient Suicide

DEFF Research Database (Denmark)

Madsen, Trine; Erlangsen, Annette; Nordentoft, Merete

2017-01-01

trends, and socio-demographic and clinical risk factors of suicide in psychiatric inpatients. Psychiatric inpatients have a very high risk of suicide relative to the background population, but it remains challenging for clinicians to identify those patients that are most likely to die from suicide during......People with mental illness have an increased risk of suicide. The aim of this paper is to provide an overview of suicide risk estimates among psychiatric inpatients based on the body of evidence found in scientific peer-reviewed literature; primarily focusing on the relative risks, rates, time...... admission. Most studies are based on low power, thus compromising quality and generalisability. The few studies with sufficient statistical power mainly identified non-modifiable risk predictors such as male gender, diagnosis, or recent deliberate self-harm. Also, the predictive value of these predictors...

Risk Estimates and Risk Factors Related to Psychiatric Inpatient Suicide

DEFF Research Database (Denmark)

Madsen, Trine; Erlangsen, Annette; Nordentoft, Merete

2017-01-01

People with mental illness have an increased risk of suicide. The aim of this paper is to provide an overview of suicide risk estimates among psychiatric inpatients based on the body of evidence found in scientific peer-reviewed literature; primarily focusing on the relative risks, rates, time...... trends, and socio-demographic and clinical risk factors of suicide in psychiatric inpatients. Psychiatric inpatients have a very high risk of suicide relative to the background population, but it remains challenging for clinicians to identify those patients that are most likely to die from suicide during...... is low. It would be of great benefit if future studies would be based on large samples while focusing on modifiable predictors over the course of an admission, such as hopelessness, depressive symptoms, and family/social situations. This would improve our chances of developing better risk assessment...

Challenges in risk estimation using routinely collected clinical data: The example of estimating cervical cancer risks from electronic health-records.

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Landy, Rebecca; Cheung, Li C; Schiffman, Mark; Gage, Julia C; Hyun, Noorie; Wentzensen, Nicolas; Kinney, Walter K; Castle, Philip E; Fetterman, Barbara; Poitras, Nancy E; Lorey, Thomas; Sasieni, Peter D; Katki, Hormuzd A

2018-06-01

Electronic health-records (EHR) are increasingly used by epidemiologists studying disease following surveillance testing to provide evidence for screening intervals and referral guidelines. Although cost-effective, undiagnosed prevalent disease and interval censoring (in which asymptomatic disease is only observed at the time of testing) raise substantial analytic issues when estimating risk that cannot be addressed using Kaplan-Meier methods. Based on our experience analysing EHR from cervical cancer screening, we previously proposed the logistic-Weibull model to address these issues. Here we demonstrate how the choice of statistical method can impact risk estimates. We use observed data on 41,067 women in the cervical cancer screening program at Kaiser Permanente Northern California, 2003-2013, as well as simulations to evaluate the ability of different methods (Kaplan-Meier, Turnbull, Weibull and logistic-Weibull) to accurately estimate risk within a screening program. Cumulative risk estimates from the statistical methods varied considerably, with the largest differences occurring for prevalent disease risk when baseline disease ascertainment was random but incomplete. Kaplan-Meier underestimated risk at earlier times and overestimated risk at later times in the presence of interval censoring or undiagnosed prevalent disease. Turnbull performed well, though was inefficient and not smooth. The logistic-Weibull model performed well, except when event times didn't follow a Weibull distribution. We have demonstrated that methods for right-censored data, such as Kaplan-Meier, result in biased estimates of disease risks when applied to interval-censored data, such as screening programs using EHR data. The logistic-Weibull model is attractive, but the model fit must be checked against Turnbull non-parametric risk estimates. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Value-at-risk estimation with wavelet-based extreme value theory: Evidence from emerging markets

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Cifter, Atilla

2011-06-01

This paper introduces wavelet-based extreme value theory (EVT) for univariate value-at-risk estimation. Wavelets and EVT are combined for volatility forecasting to estimate a hybrid model. In the first stage, wavelets are used as a threshold in generalized Pareto distribution, and in the second stage, EVT is applied with a wavelet-based threshold. This new model is applied to two major emerging stock markets: the Istanbul Stock Exchange (ISE) and the Budapest Stock Exchange (BUX). The relative performance of wavelet-based EVT is benchmarked against the Riskmetrics-EWMA, ARMA-GARCH, generalized Pareto distribution, and conditional generalized Pareto distribution models. The empirical results show that the wavelet-based extreme value theory increases predictive performance of financial forecasting according to number of violations and tail-loss tests. The superior forecasting performance of the wavelet-based EVT model is also consistent with Basel II requirements, and this new model can be used by financial institutions as well.

A risk-based microbiological criterion that uses the relative risk as the critical limit

DEFF Research Database (Denmark)

Andersen, Jens Kirk; Nørrung, Birgit; da Costa Alves Machado, Simone

2015-01-01

A risk-based microbiological criterion is described, that is based on the relative risk associated to the analytical result of a number of samples taken from a food lot. The acceptable limit is a specific level of risk and not a specific number of microorganisms, as in other microbiological...... criteria. The approach requires the availability of a quantitative microbiological risk assessment model to get risk estimates for food products from sampled food lots. By relating these food lot risk estimates to the mean risk estimate associated to a representative baseline data set, a relative risk...... estimate can be obtained. This relative risk estimate then can be compared with a critical value, defined by the criterion. This microbiological criterion based on a relative risk limit is particularly useful when quantitative enumeration data are available and when the prevalence of the microorganism...

Process-based Cost Estimation for Ramjet/Scramjet Engines

Science.gov (United States)

Singh, Brijendra; Torres, Felix; Nesman, Miles; Reynolds, John

2003-01-01

Process-based cost estimation plays a key role in effecting cultural change that integrates distributed science, technology and engineering teams to rapidly create innovative and affordable products. Working together, NASA Glenn Research Center and Boeing Canoga Park have developed a methodology of process-based cost estimation bridging the methodologies of high-level parametric models and detailed bottoms-up estimation. The NASA GRC/Boeing CP process-based cost model provides a probabilistic structure of layered cost drivers. High-level inputs characterize mission requirements, system performance, and relevant economic factors. Design alternatives are extracted from a standard, product-specific work breakdown structure to pre-load lower-level cost driver inputs and generate the cost-risk analysis. As product design progresses and matures the lower level more detailed cost drivers can be re-accessed and the projected variation of input values narrowed, thereby generating a progressively more accurate estimate of cost-risk. Incorporated into the process-based cost model are techniques for decision analysis, specifically, the analytic hierarchy process (AHP) and functional utility analysis. Design alternatives may then be evaluated not just on cost-risk, but also user defined performance and schedule criteria. This implementation of full-trade study support contributes significantly to the realization of the integrated development environment. The process-based cost estimation model generates development and manufacturing cost estimates. The development team plans to expand the manufacturing process base from approximately 80 manufacturing processes to over 250 processes. Operation and support cost modeling is also envisioned. Process-based estimation considers the materials, resources, and processes in establishing cost-risk and rather depending on weight as an input, actually estimates weight along with cost and schedule.

Psychological methods of subjective risk estimates

International Nuclear Information System (INIS)

Zimolong, B.

1980-01-01

Reactions to situations involving risks can be divided into the following parts/ perception of danger, subjective estimates of the risk and risk taking with respect to action. Several investigations have compared subjective estimates of the risk with an objective measure of that risk. In general there was a mis-match between subjective and objective measures of risk, especially, objective risk involved in routine activities is most commonly underestimated. This implies, for accident prevention, that attempts must be made to induce accurate subjective risk estimates by technical and behavioural measures. (orig.) [de

Security Events and Vulnerability Data for Cybersecurity Risk Estimation.

Science.gov (United States)

Allodi, Luca; Massacci, Fabio

2017-08-01

Current industry standards for estimating cybersecurity risk are based on qualitative risk matrices as opposed to quantitative risk estimates. In contrast, risk assessment in most other industry sectors aims at deriving quantitative risk estimations (e.g., Basel II in Finance). This article presents a model and methodology to leverage on the large amount of data available from the IT infrastructure of an organization's security operation center to quantitatively estimate the probability of attack. Our methodology specifically addresses untargeted attacks delivered by automatic tools that make up the vast majority of attacks in the wild against users and organizations. We consider two-stage attacks whereby the attacker first breaches an Internet-facing system, and then escalates the attack to internal systems by exploiting local vulnerabilities in the target. Our methodology factors in the power of the attacker as the number of "weaponized" vulnerabilities he/she can exploit, and can be adjusted to match the risk appetite of the organization. We illustrate our methodology by using data from a large financial institution, and discuss the significant mismatch between traditional qualitative risk assessments and our quantitative approach. © 2017 Society for Risk Analysis.

Estimation of cancer risks from radiotherapy of benign diseases

International Nuclear Information System (INIS)

Trott, K.R.; Kamprad, F.

2006-01-01

Background: The effective-dose method which was proposed by the ICRP (International Commission of Radiation Protection) for the estimation of risk to the general population from occupational or environmental, low-dose radiation exposure is not adequate for estimating the risk of cancer induction by radiotherapy of malignant or nonmalignant diseases. Methods:The risk of cancer induction by radiotherapy of benign diseases should be based on epidemiologic data directly derived from follow-up studies of patients who had been given radiotherapy for nonmalignant diseases in the past. Results: Risk factors were derived from epidemiologic studies of patients treated with irradiation for nonmalignant diseases to be used for selecting treatment options and optimizing treatment procedures. Conclusion: In most cases, cancer risks estimated by the effective-dose method may overestimate the true risks by one order of magnitude, yet in other cases even may underestimate it. The proposed method using organ-specific risk factors may be more suitable for treatment planning. (orig.)

Estimation of unit risk for coke oven emissions

International Nuclear Information System (INIS)

Moolgavkar, S.H.; Luebeck, E.G.; Anderson, E.L.

1998-01-01

In 1984, based on epidemiological data on cohorts of coke oven workers, USEPA estimated a unit risk for lung cancer associated with continuous exposure from birth to 1 microg/m 3 of coke oven emissions, of 6.2 x 10 -4 . This risk assessment was based on information on the cohorts available through 1966. Follow-up of these cohorts has now been extended to 1982 and, moreover, individual job histories, which were not available in 1984, have been constructed. In this study, lung cancer mortality in these cohorts of coke oven workers with extended follow-up was analyzed using standard techniques of survival analysis and a new approach based on the two stage clonal expansion model of carcinogenesis. The latter approach allows the explicit consideration of detailed patterns of exposure of each individual in the cohort. The analyses used the extended follow-up data through 1982 and the detailed job histories now available. Based on these analyses, the best estimate of unit risk is 1.5 x 10 -4 with 95% confidence interval = 1.2 x 10 -4 --1.8 x 10 -4

Risk estimates for the health effects of alpha radiation

International Nuclear Information System (INIS)

Thomas, D.C.; McNeill, K.G.

1981-09-01

This report provides risk estimates for various health effects of alpha radiation. Human and animal data have been used to characterize the shapes of dose-response relations and the effects of various modifying factors, but quantitative risk estimates are based solely on human data: for lung cancer, on miners in the Colorado plateau, Czechoslovakia, Sweden, Ontario and Newfoundland; for bone and head cancers, on radium dial painters and radium-injected patients. Slopes of dose-response relations for lung cancer show a tendency to decrease with increasing dose. Linear extrapolation is unlikely to underestimate the excess risk at low doses by more than a factor of l.5. Under the linear cell-killing model, our best estimate

Relative risk estimation of Chikungunya disease in Malaysia: An analysis based on Poisson-gamma model

Science.gov (United States)

Samat, N. A.; Ma'arof, S. H. Mohd Imam

2015-05-01

Disease mapping is a method to display the geographical distribution of disease occurrence, which generally involves the usage and interpretation of a map to show the incidence of certain diseases. Relative risk (RR) estimation is one of the most important issues in disease mapping. This paper begins by providing a brief overview of Chikungunya disease. This is followed by a review of the classical model used in disease mapping, based on the standardized morbidity ratio (SMR), which we then apply to our Chikungunya data. We then fit an extension of the classical model, which we refer to as a Poisson-Gamma model, when prior distributions for the relative risks are assumed known. Both results are displayed and compared using maps and we reveal a smoother map with fewer extremes values of estimated relative risk. The extensions of this paper will consider other methods that are relevant to overcome the drawbacks of the existing methods, in order to inform and direct government strategy for monitoring and controlling Chikungunya disease.

Estimating and mapping the population at risk of sleeping sickness.

Directory of Open Access Journals (Sweden)

Pere P Simarro

Full Text Available Human African trypanosomiasis (HAT, also known as sleeping sickness, persists as a public health problem in several sub-Saharan countries. Evidence-based, spatially explicit estimates of population at risk are needed to inform planning and implementation of field interventions, monitor disease trends, raise awareness and support advocacy. Comprehensive, geo-referenced epidemiological records from HAT-affected countries were combined with human population layers to map five categories of risk, ranging from "very high" to "very low," and to estimate the corresponding at-risk population.Approximately 70 million people distributed over a surface of 1.55 million km(2 are estimated to be at different levels of risk of contracting HAT. Trypanosoma brucei gambiense accounts for 82.2% of the population at risk, the remaining 17.8% being at risk of infection from T. b. rhodesiense. Twenty-one million people live in areas classified as moderate to very high risk, where more than 1 HAT case per 10,000 inhabitants per annum is reported.Updated estimates of the population at risk of sleeping sickness were made, based on quantitative information on the reported cases and the geographic distribution of human population. Due to substantial methodological differences, it is not possible to make direct comparisons with previous figures for at-risk population. By contrast, it will be possible to explore trends in the future. The presented maps of different HAT risk levels will help to develop site-specific strategies for control and surveillance, and to monitor progress achieved by ongoing efforts aimed at the elimination of sleeping sickness.

Estimating Risks and Relative Risks in Case-Base Studies under the Assumptions of Gene-Environment Independence and Hardy-Weinberg Equilibrium

Science.gov (United States)

Chui, Tina Tsz-Ting; Lee, Wen-Chung

2014-01-01

Many diseases result from the interactions between genes and the environment. An efficient method has been proposed for a case-control study to estimate the genetic and environmental main effects and their interactions, which exploits the assumptions of gene-environment independence and Hardy-Weinberg equilibrium. To estimate the absolute and relative risks, one needs to resort to an alternative design: the case-base study. In this paper, the authors show how to analyze a case-base study under the above dual assumptions. This approach is based on a conditional logistic regression of case-counterfactual controls matched data. It can be easily fitted with readily available statistical packages. When the dual assumptions are met, the method is approximately unbiased and has adequate coverage probabilities for confidence intervals. It also results in smaller variances and shorter confidence intervals as compared with a previous method for a case-base study which imposes neither assumption. PMID:25137392

Estimating risks and relative risks in case-base studies under the assumptions of gene-environment independence and Hardy-Weinberg equilibrium.

Directory of Open Access Journals (Sweden)

Tina Tsz-Ting Chui

Full Text Available Many diseases result from the interactions between genes and the environment. An efficient method has been proposed for a case-control study to estimate the genetic and environmental main effects and their interactions, which exploits the assumptions of gene-environment independence and Hardy-Weinberg equilibrium. To estimate the absolute and relative risks, one needs to resort to an alternative design: the case-base study. In this paper, the authors show how to analyze a case-base study under the above dual assumptions. This approach is based on a conditional logistic regression of case-counterfactual controls matched data. It can be easily fitted with readily available statistical packages. When the dual assumptions are met, the method is approximately unbiased and has adequate coverage probabilities for confidence intervals. It also results in smaller variances and shorter confidence intervals as compared with a previous method for a case-base study which imposes neither assumption.

Semantic risk estimation of suspected minefields based on spatial relationships analysis of minefield indicators from multi-level remote sensing imagery

Science.gov (United States)

Chan, Jonathan Cheung-Wai; Sahli, Hichem; Wang, Yuhang

2005-06-01

This paper presents semantic risk estimation of suspected minefields using spatial relationships of minefield indicators extracted from multi-level remote sensing. Both satellite image and pyramidal airborne acquisitions from 900m to 30m flying heights with resolutions from 1m to 2cm resolutions are used for identification of minefield indicators. R-Histogram [1] is a quantitative representation of spatial relationship between two objects in an image. Eight spatial relationships can be generated: 1) LEFT OF, 2) RIGHT OF, 3) ABOVE, 4) BELOW, 5) NEAR, 6) FAR, 7) INSIDE, 8) OUTSIDE. R-Histogram semantics are first generated from selected indicators and metrics such as topological proximity and directional relationships are trained for soft classification of risk index (normalized as 0-1). We presented a framework of how semantic metadata generated from remote sensing images are used in risk estimation. The resultant risk index identified seven out of twelve mine accidents occurred at high risk region. More importantly, comparison with ground truth obtained after mine clearance show that three out of the four identified pattern minefields falls into the area estimated at very high risk. A parcel-based per-field risk estimation can also be easily generated to show the usefulness of the risk index.

Exposure Estimation and Interpretation of Occupational Risk: Enhanced Information for the Occupational Risk Manager

Science.gov (United States)

Waters, Martha; McKernan, Lauralynn; Maier, Andrew; Jayjock, Michael; Schaeffer, Val; Brosseau, Lisa

2015-01-01

The fundamental goal of this article is to describe, define, and analyze the components of the risk characterization process for occupational exposures. Current methods are described for the probabilistic characterization of exposure, including newer techniques that have increasing applications for assessing data from occupational exposure scenarios. In addition, since the probability of health effects reflects variability in the exposure estimate as well as the dose-response curve—the integrated considerations of variability surrounding both components of the risk characterization provide greater information to the occupational hygienist. Probabilistic tools provide a more informed view of exposure as compared to use of discrete point estimates for these inputs to the risk characterization process. Active use of such tools for exposure and risk assessment will lead to a scientifically supported worker health protection program. Understanding the bases for an occupational risk assessment, focusing on important sources of variability and uncertainty enables characterizing occupational risk in terms of a probability, rather than a binary decision of acceptable risk or unacceptable risk. A critical review of existing methods highlights several conclusions: (1) exposure estimates and the dose-response are impacted by both variability and uncertainty and a well-developed risk characterization reflects and communicates this consideration; (2) occupational risk is probabilistic in nature and most accurately considered as a distribution, not a point estimate; and (3) occupational hygienists have a variety of tools available to incorporate concepts of risk characterization into occupational health and practice. PMID:26302336

Estimating the risk of cardio vascular diseases among pakistani diabetics using uk pds risk engine

International Nuclear Information System (INIS)

Moazzam, A.; Amer, J.

2015-01-01

The concept of risk estimation of Coronary Heart Disease (CHD) is helpful for clinician to identifying high risk populations for their effective treatment. Latest studies recommended only initiating cardio-protective treatment in diabetic patients based on personalized CHD risk estimates so as to reduce undue harm from overly aggressive risk factor modification. The United Kingdom Prospective Diabetes Study (UK PDS) Risk Engine is a widely used tool to assess the risk of Cardio Vascular diseases (CVD) in diabetics. The literature search so far did not reveal any study of risk assessment among Pakistani Diabetics. Methods: This descriptive study is based on the data of 470 type-2 diabetics seen in Department of Endocrinology and Metabolism, Services Institute of Medical Sciences, Lahore during 2011. The data of these 470 patients was analyzed through UKPDS Risk Engine. CHD risk was calculated. Results: The 10 years risk of CHD, fatal CHD, stroke and fatal stroke was 9.4%, 4.4%, 1.7% and 0.2% respectively. Conclusions: The present study show a lower risk of CVD occurring among Pakistani diabetics as compared to studies from western countries. (author)

Estimation of lifetime cumulative incidence and mortality risk of gastric cancer.

Science.gov (United States)

Taniyama, Yukari; Katanoda, Kota; Charvat, Hadrien; Hori, Megumi; Ohno, Yuko; Sasazuki, Shizuka; Tsugane, Shoichiro

2017-11-01

To estimate cumulative incidence and mortality risk for gastric cancer by risk category. Risk was classified into four types according to the presence/absence of Helicobacter pylori infection and chronic atrophic gastritis: in order of lowest to highest risk, Group A: H. pylori(-) and atrophic gastritis(-); Group B: H. pylori(+) and atrophic gastritis(-); Group C:H. pylori(+) and atrophic gastritis(+); and, Group D: H. pylori(-) and atrophic gastritis(+). We used vital statistics for the crude all-cause and crude gastric cancer mortality rates in 2011 and data from population-based cancer registries (the Monitoring of Cancer Incidence in Japan) for gastric cancer incidence in 2011. For relative risk and prevalence, we used the results of a meta-analysis integrating previous studies and data from the Japan Public Health Center-based Prospective Study for the Next Generation, respectively (baseline survey 2011-16). We calculated the crude incidence and mortality rates and estimated the cumulative risk using a life-table method. The estimated lifetime cumulative incidence risk was 11.4% for men and 5.7% for women. The estimated risk for Groups A, B, C and D was 2.4%, 10.8%, 26.7% and 35.5% for men, and 1.2%, 5.5%, 13.5% and 18.0% for women, respectively. Similarly, the estimated lifetime cumulative mortality risk was 3.9% for men and 1.8% for women. The estimated risk of mortality for Groups A, B, C and D was 0.8%, 3.6%, 9.0% and 12.0% for men, and 0.4%, 1.7%, 4.2% and 5.7% for women, respectively. Our results may be useful for designing individually tailored prevention programs. © The Author 2017. Published by Oxford University Press.

How are flood risk estimates affected by the choice of return-periods?

Science.gov (United States)

Ward, P. J.; de Moel, H.; Aerts, J. C. J. H.

2011-12-01

Flood management is more and more adopting a risk based approach, whereby flood risk is the product of the probability and consequences of flooding. One of the most common approaches in flood risk assessment is to estimate the damage that would occur for floods of several exceedance probabilities (or return periods), to plot these on an exceedance probability-loss curve (risk curve) and to estimate risk as the area under the curve. However, there is little insight into how the selection of the return-periods (which ones and how many) used to calculate risk actually affects the final risk calculation. To gain such insights, we developed and validated an inundation model capable of rapidly simulating inundation extent and depth, and dynamically coupled this to an existing damage model. The method was applied to a section of the River Meuse in the southeast of the Netherlands. Firstly, we estimated risk based on a risk curve using yearly return periods from 2 to 10 000 yr (€ 34 million p.a.). We found that the overall risk is greatly affected by the number of return periods used to construct the risk curve, with over-estimations of annual risk between 33% and 100% when only three return periods are used. In addition, binary assumptions on dike failure can have a large effect (a factor two difference) on risk estimates. Also, the minimum and maximum return period considered in the curve affects the risk estimate considerably. The results suggest that more research is needed to develop relatively simple inundation models that can be used to produce large numbers of inundation maps, complementary to more complex 2-D-3-D hydrodynamic models. It also suggests that research into flood risk could benefit by paying more attention to the damage caused by relatively high probability floods.

Quantitative Estimation of Risks for Production Unit Based on OSHMS and Process Resilience

Science.gov (United States)

Nyambayar, D.; Koshijima, I.; Eguchi, H.

2017-06-01

Three principal elements in the production field of chemical/petrochemical industry are (i) Production Units, (ii) Production Plant Personnel and (iii) Production Support System (computer system introduced for improving productivity). Each principal element has production process resilience, i.e. a capability to restrain disruptive signals occurred in and out of the production field. In each principal element, risk assessment is indispensable for the production field. In a production facility, the occupational safety and health management system (Hereafter, referred to as OSHMS) has been introduced to reduce a risk of accidents and troubles that may occur during production. In OSHMS, a risk assessment is specified to reduce a potential risk in the production facility such as a factory, and PDCA activities are required for a continual improvement of safety production environments. However, there is no clear statement to adopt the OSHMS standard into the production field. This study introduces a metric to estimate the resilience of the production field by using the resilience generated by the production plant personnel and the result of the risk assessment in the production field. A method for evaluating how OSHMS functions are systematically installed in the production field is also discussed based on the resilience of the three principal elements.

Estimating the value of a Country's built assets: investment-based exposure modelling for global risk assessment

Science.gov (United States)

Daniell, James; Pomonis, Antonios; Gunasekera, Rashmin; Ishizawa, Oscar; Gaspari, Maria; Lu, Xijie; Aubrecht, Christoph; Ungar, Joachim

2017-04-01

In order to quantify disaster risk, there is a demand and need for determining consistent and reliable economic value of built assets at national or sub national level exposed to natural hazards. The value of the built stock in the context of a city or a country is critical for risk modelling applications as it allows for the upper bound in potential losses to be established. Under the World Bank probabilistic disaster risk assessment - Country Disaster Risk Profiles (CDRP) Program and rapid post-disaster loss analyses in CATDAT, key methodologies have been developed that quantify the asset exposure of a country. In this study, we assess the complementary methods determining value of building stock through capital investment data vs aggregated ground up values based on built area and unit cost of construction analyses. Different approaches to modelling exposure around the world, have resulted in estimated values of built assets of some countries differing by order(s) of magnitude. Using the aforementioned methodology of comparing investment data based capital stock and bottom-up unit cost of construction values per square meter of assets; a suitable range of capital stock estimates for built assets have been created. A blind test format was undertaken to compare the two types of approaches from top-down (investment) and bottom-up (construction cost per unit), In many cases, census data, demographic, engineering and construction cost data are key for bottom-up calculations from previous years. Similarly for the top-down investment approach, distributed GFCF (Gross Fixed Capital Formation) data is also required. Over the past few years, numerous studies have been undertaken through the World Bank Caribbean and Central America disaster risk assessment program adopting this methodology initially developed by Gunasekera et al. (2015). The range of values of the building stock is tested for around 15 countries. In addition, three types of costs - Reconstruction cost

A review of radiation risk estimates

International Nuclear Information System (INIS)

1991-06-01

Three authoritative reports (UNSCEAR-1988, BEIR-V-1990, and ICRP-1990 Recommendations) on risk estimates have been reviewed and compared to previous risk estimates published by the same organizations. The ICRP now uses the term 'probability' in place of the term 'risk'. For fatal cancers, the new ICRP probability estimates are 5.0 x 10 -2 Sv -1 for a population of all ages and 4.0 x 10 -2 Sv -1 for a population of working age. For serious hereditary effects summarized over all generations, the ICRP probability coefficients are 1.0 x 10 -2 Sv -1 for a population of all ages and 0.6 x 10 -2 Sv -1 for a population of working age. For prenatal irradiation, at 8 - 15 weeks after conception, there may be a decrease of 30 I.Q. points per Sv and a risk of cancer which may lie in the range of 2 to 10 x 10 -2 Sv -1 . Based mainly on the new probability estimates the ICRP recommends a limit on effective dose of 20 mSv per year, averaged over 5 years (100 mSv in 5 years) with the further provision that the effective dose should not exceed 50 mSv in any single year. For public exposure the ICRP recommends an annual limit on effective dose of 1 mSv. However, in special circumstances, a higher value of effective dose could be allowed in a single year provided that the average over 5 five years does not exceed 1 mSv per year. Once pregnancy has been declared, the conceptus should be protected by applying a supplementary equivalent dose limit to the surface of the woman's abdomen of 2 mSv for the remainder of the pregnancy and by limiting intakes of radionuclides to about 1/20 of the annual limit on intake. A brief survey of epidemiological studies of workers and the risks from radon and thoron progeny is also included. (110 refs, 29 tabs., 10 figs.)

Estimating micro area behavioural risk factor prevalence from large population-based surveys: a full Bayesian approach

Directory of Open Access Journals (Sweden)

L. Seliske

2016-06-01

Full Text Available Abstract Background An important public health goal is to decrease the prevalence of key behavioural risk factors, such as tobacco use and obesity. Survey information is often available at the regional level, but heterogeneity within large geographic regions cannot be assessed. Advanced spatial analysis techniques are demonstrated to produce sensible micro area estimates of behavioural risk factors that enable identification of areas with high prevalence. Methods A spatial Bayesian hierarchical model was used to estimate the micro area prevalence of current smoking and excess bodyweight for the Erie-St. Clair region in southwestern Ontario. Estimates were mapped for male and female respondents of five cycles of the Canadian Community Health Survey (CCHS. The micro areas were 2006 Census Dissemination Areas, with an average population of 400–700 people. Two individual-level models were specified: one controlled for survey cycle and age group (model 1, and one controlled for survey cycle, age group and micro area median household income (model 2. Post-stratification was used to derive micro area behavioural risk factor estimates weighted to the population structure. SaTScan analyses were conducted on the granular, postal-code level CCHS data to corroborate findings of elevated prevalence. Results Current smoking was elevated in two urban areas for both sexes (Sarnia and Windsor, and an additional small community (Chatham for males only. Areas of excess bodyweight were prevalent in an urban core (Windsor among males, but not females. Precision of the posterior post-stratified current smoking estimates was improved in model 2, as indicated by narrower credible intervals and a lower coefficient of variation. For excess bodyweight, both models had similar precision. Aggregation of the micro area estimates to CCHS design-based estimates validated the findings. Conclusions This is among the first studies to apply a full Bayesian model to complex

Risk Estimates and Risk Factors Related to Psychiatric Inpatient Suicide—An Overview

Directory of Open Access Journals (Sweden)

Trine Madsen

2017-03-01

Full Text Available People with mental illness have an increased risk of suicide. The aim of this paper is to provide an overview of suicide risk estimates among psychiatric inpatients based on the body of evidence found in scientific peer-reviewed literature; primarily focusing on the relative risks, rates, time trends, and socio-demographic and clinical risk factors of suicide in psychiatric inpatients. Psychiatric inpatients have a very high risk of suicide relative to the background population, but it remains challenging for clinicians to identify those patients that are most likely to die from suicide during admission. Most studies are based on low power, thus compromising quality and generalisability. The few studies with sufficient statistical power mainly identified non-modifiable risk predictors such as male gender, diagnosis, or recent deliberate self-harm. Also, the predictive value of these predictors is low. It would be of great benefit if future studies would be based on large samples while focusing on modifiable predictors over the course of an admission, such as hopelessness, depressive symptoms, and family/social situations. This would improve our chances of developing better risk assessment tools.

Quantifying IT estimation risks

NARCIS (Netherlands)

Kulk, G.P.; Peters, R.J.; Verhoef, C.

2009-01-01

A statistical method is proposed for quantifying the impact of factors that influence the quality of the estimation of costs for IT-enabled business projects. We call these factors risk drivers as they influence the risk of the misestimation of project costs. The method can effortlessly be

Jumps and Betas: A New Framework for Disentangling and Estimating Systematic Risks

DEFF Research Database (Denmark)

Todorov, Viktor; Bollerslev, Tim

market portfolio, we find the estimated diffusive and jump betas with respect to the market to be quite dif- ferent for many of the stocks. Our findings have direct and important implications for empirical asset pricing finance and practical portfolio and risk management decisions.......We provide a new theoretical framework for disentangling and estimating sensitivity towards systematic diffusive and jump risks in the context of factor pricing models. Our estimates of the sensitivities towards systematic risks, or betas, are based on the notion of increasingly finer sampled...

Methods to estimate the genetic risk

International Nuclear Information System (INIS)

Ehling, U.H.

1989-01-01

The estimation of the radiation-induced genetic risk to human populations is based on the extrapolation of results from animal experiments. Radiation-induced mutations are stochastic events. The probability of the event depends on the dose; the degree of the damage dose not. There are two main approaches in making genetic risk estimates. One of these, termed the direct method, expresses risk in terms of expected frequencies of genetic changes induced per unit dose. The other, referred to as the doubling dose method or the indirect method, expresses risk in relation to the observed incidence of genetic disorders now present in man. The advantage of the indirect method is that not only can Mendelian mutations be quantified, but also other types of genetic disorders. The disadvantages of the method are the uncertainties in determining the current incidence of genetic disorders in human and, in addition, the estimasion of the genetic component of congenital anomalies, anomalies expressed later and constitutional and degenerative diseases. Using the direct method we estimated that 20-50 dominant radiation-induced mutations would be expected in 19 000 offspring born to parents exposed in Hiroshima and Nagasaki, but only a small proportion of these mutants would have been detected with the techniques used for the population study. These methods were used to predict the genetic damage from the fallout of the reactor accident at Chernobyl in the vicinity of Southern Germany. The lack of knowledge for the interaction of chemicals with ionizing radiation and the discrepancy between the high safety standards for radiation protection and the low level of knowledge for the toxicological evaluation of chemical mutagens will be emphasized. (author)

Estimation of Radiological Terrorism Risk by Administrative Districts

Energy Technology Data Exchange (ETDEWEB)

Kim, Suk Hoon; Kim, Ju Youl [Seoul National Univ., Seoul (Korea, Republic of); Yoo, Ho Sik [Korea Institute of Nuclear Nonproliferation and Control, Daejeon (Korea, Republic of)

2008-10-15

Since the 9/11 attack in USA, the threat of terrorism across the world has dramatically increased. Accordingly, estimating terrorism risk has become an essential part of catastrophe risk strategies throughout the world. There are many forms of terrorism. Recently, the prospect of the radiological terrorist attack using the radioactive material is considered as one of the most serious threats. The aim of this paper is to assess the radiological terrorism risk by administrative districts based on the parameters that imply threat, vulnerability, and consequences of terrorist attacks.

Estimation of Radiological Terrorism Risk by Administrative Districts

International Nuclear Information System (INIS)

Kim, Suk Hoon; Kim, Ju Youl; Yoo, Ho Sik

2008-01-01

Since the 9/11 attack in USA, the threat of terrorism across the world has dramatically increased. Accordingly, estimating terrorism risk has become an essential part of catastrophe risk strategies throughout the world. There are many forms of terrorism. Recently, the prospect of the radiological terrorist attack using the radioactive material is considered as one of the most serious threats. The aim of this paper is to assess the radiological terrorism risk by administrative districts based on the parameters that imply threat, vulnerability, and consequences of terrorist attacks

Life cycle cost and risk estimation of environmental management options

International Nuclear Information System (INIS)

Shropshire, D.; Sherick, M.

1996-01-01

The evaluation process is demonstrated in this paper through comparative analysis of two alternative scenarios identified for the management of the alpha-contaminated fixed low-level waste currently stored at INEL. These two scenarios, the Base Case and the Delay Case, are realistic and based on actual data, but are not intended to exactly match actual plans currently being developed at INEL. Life cycle cost estimates were developed for both scenarios using the System Cost Model; resulting costs are presented and compared. Life cycle costs are shown as a function of time and also aggregated by pretreatment, treatment, storage, and disposal activities. Although there are some short-term cost savings for the Delay Case, cumulative life cycle costs eventually become much higher than costs for the Base Case over the same period of time, due mainly to the storage and repackaging necessary to accommodate the longer Delay Case schedule. Life cycle risk estimates were prepared using a new risk analysis method adapted to the System Cost Model architecture for automated, systematic cost/risk applications. Relative risk summaries are presented for both scenarios as a function of time and also aggregated by pretreatment, treatment, storage, and disposal activities. Relative risk of the Delay Case is shown to be higher than that of the Base Case. Finally, risk and cost results are combined to show how the collective information can be used to help identify opportunities for risk or cost reduction and highlight areas where risk reduction can be achieved most economically

Designing and evaluating risk-based surveillance systems

DEFF Research Database (Denmark)

Willeberg, Preben; Nielsen, Liza Rosenbaum; Salman, Mo

2012-01-01

Risk-based surveillance systems reveal occurrence of disease or infection in a sample of population units, which are selected on the basis of risk factors for the condition under study. The purpose of such systems for supporting practical animal disease policy formulations and management decisions...... with prudent use of resources while maintaining acceptable system performance. High-risk category units are selected for testing by identification of the presence of specific high-risk factor(s), while disregarding other factors that might also influence the risk. On this basis we argue that the most...... applicable risk estimate for use in designing and evaluating a risk-based surveillance system would be a crude (unadjusted) relative risk, odds ratio or apparent prevalence. Risk estimates found in the published literature, however, are often the results of multivariable analyses implicitly adjusting...

Estimating cancer risks to adults undergoing body CT examinations

International Nuclear Information System (INIS)

Huda, W.; He, W.

2012-01-01

The purpose of the study is to estimate cancer risks from the amount of radiation used to perform body computed tomography (CT) examination. The ImPACT CT Patient Dosimetry Calculator was used to compute values of organ doses for adult body CT examinations. The radiation used to perform each examination was quantified by the dose-length product (DLP). Patient organ doses were converted into corresponding age and sex dependent cancer risks using data from BEIR VII. Results are presented for cancer risks per unit DLP and unit effective dose for 11 sensitive organs, as well as estimates of the contribution from 'other organs'. For patients who differ from a standard sized adult, correction factors based on the patient weight and antero-posterior dimension are provided to adjust organ doses and the corresponding risks. At constant incident radiation intensity, for CT examinations that include the chest, risks for females are markedly higher than those for males, whereas for examinations that include the pelvis, risks in males were slightly higher than those in females. In abdominal CT scans, risks for males and female patients are very similar. For abdominal CT scans, increasing the patient age from 20 to 80 resulted in a reduction in patient risks of nearly a factor of 5. The average cancer risk for chest/abdomen/pelvis CT examinations was ∼26 % higher than the cancer risk caused by 'sensitive organs'. Doses and radiation risks in 80 kg adults were ∼10 % lower than those in 70 kg patients. Cancer risks in body CT can be estimated from the examination DLP by accounting for sex, age, as well as patient physical characteristics. (authors)

Model-Based Estimation of Collision Risks of Predatory Birds with Wind Turbines

Directory of Open Access Journals (Sweden)

Marcus Eichhorn

2012-06-01

Full Text Available The expansion of renewable energies, such as wind power, is a promising way of mitigating climate change. Because of the risk of collision with rotor blades, wind turbines have negative effects on local bird populations, particularly on raptors such as the Red Kite (Milvus milvus. Appropriate assessment tools for these effects have been lacking. To close this gap, we have developed an agent-based, spatially explicit model that simulates the foraging behavior of the Red Kite around its aerie in a landscape consisting of different land-use types. We determined the collision risk of the Red Kite with the turbine as a function of the distance between the wind turbine and the aerie and other parameters. The impact function comprises the synergistic effects of species-specific foraging behavior and landscape structure. The collision risk declines exponentially with increasing distance. The strength of this decline depends on the raptor's foraging behavior, its ability to avoid wind turbines, and the mean wind speed in the region. The collision risks, which are estimated by the simulation model, are in the range of values observed in the field. The derived impact function shows that the collision risk can be described as an aggregated function of distance between the wind turbine and the raptor's aerie. This allows an easy and rapid assessment of the ecological impacts of (existing or planned wind turbines in relation to their spatial location. Furthermore, it implies that minimum buffer zones for different landscapes can be determined in a defensible way. This modeling approach can be extended to other bird species with central-place foraging behavior. It provides a helpful tool for landscape planning aimed at minimizing the impacts of wind power on biodiversity.

Estimating adolescent risk for hearing loss based on data from a large school-based survey

NARCIS (Netherlands)

Vogel, L.; Verschuure, H.; Ploeg, C.P.B. van der; Brug, J.; Raat, H.

2010-01-01

Objectives. We estimated whether and to what extent a group of adolescents were at risk of developing permanent hearing loss as a result of voluntary exposure to high-volume music, and we assessed whether such exposure was associated with hearing-related symptoms. Methods. In 2007, 1512 adolescents

Estimating adolescent risk for hearing loss based on data from a large school-based survey

NARCIS (Netherlands)

I. Vogel (Ineke); H. Verschuure (Hans); C.P.B. van der Ploeg (Catharina); J. Brug (Hans); H. Raat (Hein)

2010-01-01

textabstractObjectives. We estimated whether and to what extent a group of adolescents were at risk of developing permanent hearing loss as a result of voluntary exposure to high-volume music, and we assessed whether such exposure was associated with hearing-related symptoms. Methods. In 2007, 1512

How much does HDL cholesterol add to risk estimation? A report from the SCORE Investigators.

LENUS (Irish Health Repository)

Cooney, Marie Therese

2009-06-01

Systematic COronary Risk Evaluation (SCORE), the risk estimation system recommended by the European guidelines on cardiovascular disease prevention, estimates 10-year risk of cardiovascular disease mortality based on age, sex, country of origin, systolic blood pressure, smoking status and either total cholesterol (TC) or TC\\/high-density lipoprotein cholesterol (HDL-C) ratio. As, counterintuitively, these two systems perform very similarly, we have investigated whether incorporating HDL-C and TC as separate variables improves risk estimation.

Data Sources for the Model-based Small Area Estimates of Cancer-Related Knowledge - Small Area Estimates

Science.gov (United States)

The model-based estimates of important cancer risk factors and screening behaviors are obtained by combining the responses to the Behavioral Risk Factor Surveillance System (BRFSS) and the National Health Interview Survey (NHIS).

Backtesting for Risk-Based Regulatory Capital

NARCIS (Netherlands)

Kerkhof, F.L.J.; Melenberg, B.

2002-01-01

In this paper we present a framework for backtesting all currently popular risk measurement methods (including value-at-risk and expected shortfall) using the functional delta method.Estimation risk can be taken explicitly into account.Based on a simulation study we provide evidence that tests for

Simplifying cardiovascular risk estimation using resting heart rate.

LENUS (Irish Health Repository)

Cooney, Marie Therese

2010-09-01

Elevated resting heart rate (RHR) is a known, independent cardiovascular (CV) risk factor, but is not included in risk estimation systems, including Systematic COronary Risk Evaluation (SCORE). We aimed to derive risk estimation systems including RHR as an extra variable and assess the value of this addition.

LIFETIME LUNG CANCER RISKS ASSOCIATED WITH INDOOR RADON EXPOSURE BASED ON VARIOUS RADON RISK MODELS FOR CANADIAN POPULATION.

Science.gov (United States)

Chen, Jing

2017-04-01

This study calculates and compares the lifetime lung cancer risks associated with indoor radon exposure based on well-known risk models in the literature; two risk models are from joint studies among miners and the other three models were developed from pooling studies on residential radon exposure from China, Europe and North America respectively. The aim of this article is to make clear that the various models are mathematical descriptions of epidemiologically observed real risks in different environmental settings. The risk from exposure to indoor radon is real and it is normal that variations could exist among different risk models even when they were applied to the same dataset. The results show that lifetime risk estimates vary significantly between the various risk models considered here: the model based on the European residential data provides the lowest risk estimates, while models based on the European miners and Chinese residential pooling with complete dosimetry give the highest values. The lifetime risk estimates based on the EPA/BEIR-VI model lie within this range and agree reasonably well with the averages of risk estimates from the five risk models considered in this study. © Crown copyright 2016.

Estimating radiation-induced cancer risk using MVK two-stage model for carcinogenesis

International Nuclear Information System (INIS)

Kai, M.; Kusama, T.; Aoki, Y.

1993-01-01

Based on the carcinogenesis model as proposed by Moolgavkar et al., time-dependent relative risk models were derived for projecting the time variation in excess relative risk. If it is assumed that each process is described by time-independent linear dose-response relationship, the time variation in excess relative risk is influenced by the parameter related with the promotion process. The risk model based carcinogenesis theory would play a marked role in estimating radiation-induced cancer risk in constructing a projection model or transfer model

Value-at-Risk analysis using ARMAX GARCHX approach for estimating risk of banking subsector stock return’s

Science.gov (United States)

Dewi Ratih, Iis; Sutijo Supri Ulama, Brodjol; Prastuti, Mike

2018-03-01

Value at Risk (VaR) is one of the statistical methods used to measure market risk by estimating the worst losses in a given time period and level of confidence. The accuracy of this measuring tool is very important in determining the amount of capital that must be provided by the company to cope with possible losses. Because there is a greater losses to be faced with a certain degree of probability by the greater risk. Based on this, VaR calculation analysis is of particular concern to researchers and practitioners of the stock market to be developed, thus getting more accurate measurement estimates. In this research, risk analysis of stocks in four banking sub-sector, Bank Rakyat Indonesia, Bank Mandiri, Bank Central Asia and Bank Negara Indonesia will be done. Stock returns are expected to be influenced by exogenous variables, namely ICI and exchange rate. Therefore, in this research, stock risk estimation are done by using VaR ARMAX-GARCHX method. Calculating the VaR value with the ARMAX-GARCHX approach using window 500 gives more accurate results. Overall, Bank Central Asia is the only bank had the estimated maximum loss in the 5% quantile.

Explaining behavior change after genetic testing: the problem of collinearity between test results and risk estimates.

Science.gov (United States)

Fanshawe, Thomas R; Prevost, A Toby; Roberts, J Scott; Green, Robert C; Armstrong, David; Marteau, Theresa M

2008-09-01

This paper explores whether and how the behavioral impact of genotype disclosure can be disentangled from the impact of numerical risk estimates generated by genetic tests. Secondary data analyses are presented from a randomized controlled trial of 162 first-degree relatives of Alzheimer's disease (AD) patients. Each participant received a lifetime risk estimate of AD. Control group estimates were based on age, gender, family history, and assumed epsilon4-negative apolipoprotein E (APOE) genotype; intervention group estimates were based upon the first three variables plus true APOE genotype, which was also disclosed. AD-specific self-reported behavior change (diet, exercise, and medication use) was assessed at 12 months. Behavior change was significantly more likely with increasing risk estimates, and also more likely, but not significantly so, in epsilon4-positive intervention group participants (53% changed behavior) than in control group participants (31%). Intervention group participants receiving epsilon4-negative genotype feedback (24% changed behavior) and control group participants had similar rates of behavior change and risk estimates, the latter allowing assessment of the independent effects of genotype disclosure. However, collinearity between risk estimates and epsilon4-positive genotypes, which engender high-risk estimates, prevented assessment of the independent effect of the disclosure of an epsilon4 genotype. Novel study designs are proposed to determine whether genotype disclosure has an impact upon behavior beyond that of numerical risk estimates.

Estimation of risks from medical irradiation

International Nuclear Information System (INIS)

Persson, B.R.R.

1983-01-01

This paper discuss various concepts of quantifying risks from medical irradiation. The expected individual risk from specific medical examination can be derived by estimation the dose-equivalent in different organs and tissues and apply the risk factors recommended for these tissues. A more practical way is to estimate or measure the energy imparted which has been found to correlate quite well with the total risk derived by summing up the risks for the involved tissues. The effective dose-equivalent concept can be used to derive the collective effective dose-equivalent in a population in order to compare the contribution from medical exposure with the contribution from other sources of irradiation in the society. In many countries it is thus shown that medical exposures gives the largest man-made contribution to the population dose

Risk based surveillance for vector borne diseases

DEFF Research Database (Denmark)

Bødker, Rene

of samples and hence early detection of outbreaks. Models for vector borne diseases in Denmark have demonstrated dramatic variation in outbreak risk during the season and between years. The Danish VetMap project aims to make these risk based surveillance estimates available on the veterinarians smart phones...... in Northern Europe. This model approach may be used as a basis for risk based surveillance. In risk based surveillance limited resources for surveillance are targeted at geographical areas most at risk and only when the risk is high. This makes risk based surveillance a cost effective alternative...... sample to a diagnostic laboratory. Risk based surveillance models may reduce this delay. An important feature of risk based surveillance models is their ability to continuously communicate the level of risk to veterinarians and hence increase awareness when risk is high. This is essential for submission...

Stochastic risk estimation from medical x-ray diagnostic examinations, 3

International Nuclear Information System (INIS)

Hashizume, Tadashi; Maruyama, Takashi; Noda, Yutaka; Iwai, Kazuo; Fukuhisa, Kenjiro

1981-01-01

The genetically significant dose (GSD), per Caput mean bone marrow dose (CMD), leukemia significant dose (LSD) and malignancy significant dose (MSD) from medical diagnostic X-ray examinations in Japan were estimated based on a 1979 nationwide survey of randomly sampled hospitals and clinics. The population risk estimates were carried out using the resultant values of GSD, LSD and MSD. In the risk estimates, the significant factors, namely, the relative child expectancy, the leukemia significant factor and the malignancy significant factor, for patients were assumed to be same as those of general population. The risk factors used were 185 x 10 -6 rad -1 for genetic risk of all generations, 20 x 10 -6 rad -1 for fatal leukemia and 165 x 10 -6 rad -1 for fatal malignant diseases, respectively. The resultant annual population doses per person were 15 mrad (0.15 mGy) for GSD, 107 mrad (1.07 mGy) for CMD, 86 mrad (0.86 mGy) for LSD and 43 mrad (0.43 mGy) for MSD, respectively. The present data other than the MSD were compared with the data in 1960, 1969 and 1974. For example, the GSD of 1979 was approximately same as that of 1974, although the annual number of examinations in 1979 increased by about 30 percent as compared with those of 1974. The population risks from X-ray diagnosis were estimated to be 260 persons per year for genetic risk of all generations, 192 person per year for fatal leukemic risk and 825 person per year for malignant risk, respectively, for the whole population in Japan, assuming that the X-ray diagnosis in 1979 will be performed continuously in the future. The average risks per one exposure for X-ray radiography were estimated using the weighted average of the significant factor and the organ or tissue dose with the number of radiographic exposures by age and by type of examination. The average risks per radiographic exposure were 176 x 10 -9 for genetic risk, 285 x 10 -9 for leukemic risk and 1.75 x 10 -6 for malignant risk respectively. (author)

The need to estimate risks

International Nuclear Information System (INIS)

Pochin, E.E.

1980-01-01

In an increasing number of situations, it is becoming possible to obtain and compare numerical estimates of the biological risks involved in different alternative sources of action. In some cases these risks are similar in kind, as for example when the risk of including fatal cancer of the breast or stomach by x-ray screening of a population at risk, is compared with the risk of such cancers proving fatal if not detected by a screening programme. In other cases in which it is important to attempt a comparison, the risks are dissimilar in type, as when the safety of occupations involving exposure to radiation or chemical carcinogens is compared with that of occupations in which the major risks are from lung disease or from accidental injury and death. Similar problems of assessing the relative severity of unlike effects occur in any attempt to compare the total biological harm associated with a given output of electricity derived from different primary fuel sources, with its contributions both of occupation and of public harm. In none of these instances is the numerical frequency of harmful effects alone an adequate measure of total biological detriment, nor is such detriment the only factor which should influence decisions. Estimations of risk appear important however, since otherwise public health decisions are likely to be made on more arbitrary grounds, and public opinion will continue to be affected predominantly by the type rather than also by the size of risk. (author)

Estimating the Value-at-Risk for some stocks at the capital market in Indonesia based on ARMA-FIGARCH models

Science.gov (United States)

Sukono; Lesmana, E.; Susanti, D.; Napitupulu, H.; Hidayat, Y.

2017-11-01

Value-at-Risk has already become a standard measurement that must be carried out by the financial institution for both internal interest and regulatory. In this paper, the estimation of Value-at-Risk of some stocks with econometric models approach is analyzed. In this research, we assume that the stock return follows the time series model. To do the estimation of mean value we are using ARMA models, while to estimate the variance value we are using FIGARCH models. Furthermore, the mean value estimator and the variance are used to estimate the Value-at-Risk. The result of the analysis shows that from five stock PRUF, BBRI, MPPA, BMRI, and INDF, the Value-at-Risk obtained are 0.01791, 0.06037, 0.02550, 0.06030, and 0.02585 respectively. Since Value-at-Risk represents the maximum risk size of each stock at a 95% level of significance, then it can be taken into consideration in determining the investment policy on stocks.

Canadian population risk of radon induced lung cancer variation range assessment based on various radon risk models

International Nuclear Information System (INIS)

Chen, Jing

2017-01-01

To address public concerns regarding radon risk and variations in risk estimates based on various risk models available in the literature, lifetime lung cancer risks were calculated with five well-known risk models using more recent Canadian vital statistics (5-year averages from 2008 to 2012). Variations in population risk estimation among various models were assessed. The results showed that the Canadian population risk of radon induced lung cancer can vary from 5.0 to 17% for men and 5.1 to 18% for women based on different radon risk models. Averaged over the estimates from various risk models with better radon dosimetry, 13% of lung cancer deaths among Canadian males and 14% of lung cancer deaths among Canadian females were attributable to long-term indoor radon exposure. (authors)

Risk estimates for exposure to alpha emitters

International Nuclear Information System (INIS)

1982-07-01

The primary scope of this report is to evaluate the risk of lung cancer from occupational exposure to short-lived daughters of radon and thoron. The Subcommittee on Risk Estimates considers that inhalation of radon and thoron daughters is the major radiation hazard from alpha radiation in uranium mining. The secondary scope of this report is the consideration of the applicability of the risk estimates derived from miners to the general public. The risk to members of the public from radium-226 in drinking water is also considered. Some research requirments are suggested

Review of the current status of radiation risk estimates

International Nuclear Information System (INIS)

Charles, M.W.; Little, M.P.

1988-10-01

This report reviews the current status of radiation risk estimation for low linear energy transfer radiation. Recent statements by various national and international organisations regarding risk estimates are critically discussed. The recently published revised population risk estimates from the study of Japanese bomb survivors are also reviewed and used with some unpublished data from Japan to calculate risk figures for a general work force. (author)

A Risk Metric Assessment of Scenario-Based Market Risk Measures for Volatility and Risk Estimation: Evidence from Emerging Markets

Directory of Open Access Journals (Sweden)

Sitima Innocent

2015-03-01

Full Text Available The study evaluated the sensitivity of the Value- at- Risk (VaR and Expected Shortfalls (ES with respect to portfolio allocation in emerging markets with an index portfolio of a developed market. This study utilised different models for VaR and ES techniques using various scenario-based models such as Covariance Methods, Historical Simulation and the GARCH (1, 1 for the predictive ability of these models in both relatively stable market conditions and extreme market conditions. The results showed that Expected Shortfall has less risk tolerance than VaR based on the same scenario-based market risk measures

Risk estimation using probability machines

Science.gov (United States)

2014-01-01

Background Logistic regression has been the de facto, and often the only, model used in the description and analysis of relationships between a binary outcome and observed features. It is widely used to obtain the conditional probabilities of the outcome given predictors, as well as predictor effect size estimates using conditional odds ratios. Results We show how statistical learning machines for binary outcomes, provably consistent for the nonparametric regression problem, can be used to provide both consistent conditional probability estimation and conditional effect size estimates. Effect size estimates from learning machines leverage our understanding of counterfactual arguments central to the interpretation of such estimates. We show that, if the data generating model is logistic, we can recover accurate probability predictions and effect size estimates with nearly the same efficiency as a correct logistic model, both for main effects and interactions. We also propose a method using learning machines to scan for possible interaction effects quickly and efficiently. Simulations using random forest probability machines are presented. Conclusions The models we propose make no assumptions about the data structure, and capture the patterns in the data by just specifying the predictors involved and not any particular model structure. So they do not run the same risks of model mis-specification and the resultant estimation biases as a logistic model. This methodology, which we call a “risk machine”, will share properties from the statistical machine that it is derived from. PMID:24581306

Estimation of insurance premiums for coverage against natural disaster risk: an application of Bayesian Inference

NARCIS (Netherlands)

Paudel, Y.; Botzen, W.J.W.; Aerts, J.C.J.H.

2013-01-01

This study applies Bayesian Inference to estimate flood risk for 53 dyke ring areas in the Netherlands, and focuses particularly on the data scarcity and extreme behaviour of catastrophe risk. The probability density curves of flood damage are estimated through Monte Carlo simulations. Based on

Prognostic risk estimates of patients with multiple sclerosis and their physicians: comparison to an online analytical risk counseling tool.

Directory of Open Access Journals (Sweden)

Christoph Heesen

Full Text Available BACKGROUND: Prognostic counseling in multiple sclerosis (MS is difficult because of the high variability of disease progression. Simultaneously, patients and physicians are increasingly confronted with making treatment decisions at an early stage, which requires taking individual prognoses into account to strike a good balance between benefits and harms of treatments. It is therefore important to understand how patients and physicians estimate prognostic risk, and whether and how these estimates can be improved. An online analytical processing (OLAP tool based on pooled data from placebo cohorts of clinical trials offers short-term prognostic estimates that can be used for individual risk counseling. OBJECTIVE: The aim of this study was to clarify if personalized prognostic information as presented by the OLAP tool is considered useful and meaningful by patients. Furthermore, we used the OLAP tool to evaluate patients' and physicians' risk estimates. Within this evaluation process we assessed short-time prognostic risk estimates of patients with MS (final n = 110 and their physicians (n = 6 and compared them with the estimates of OLAP. RESULTS: Patients rated the OLAP tool as understandable and acceptable, but to be only of moderate interest. It turned out that patients, physicians, and the OLAP tool ranked patients similarly regarding their risk of disease progression. Both patients' and physicians' estimates correlated most strongly with those disease covariates that the OLAP tool's estimates also correlated with most strongly. Exposure to the OLAP tool did not change patients' risk estimates. CONCLUSION: While the OLAP tool was rated understandable and acceptable, it was only of modest interest and did not change patients' prognostic estimates. The results suggest, however, that patients had some idea regarding their prognosis and which factors were most important in this regard. Future work with OLAP should assess long-term prognostic

Prognostic risk estimates of patients with multiple sclerosis and their physicians: comparison to an online analytical risk counseling tool.

Science.gov (United States)

Heesen, Christoph; Gaissmaier, Wolfgang; Nguyen, Franziska; Stellmann, Jan-Patrick; Kasper, Jürgen; Köpke, Sascha; Lederer, Christian; Neuhaus, Anneke; Daumer, Martin

2013-01-01

Prognostic counseling in multiple sclerosis (MS) is difficult because of the high variability of disease progression. Simultaneously, patients and physicians are increasingly confronted with making treatment decisions at an early stage, which requires taking individual prognoses into account to strike a good balance between benefits and harms of treatments. It is therefore important to understand how patients and physicians estimate prognostic risk, and whether and how these estimates can be improved. An online analytical processing (OLAP) tool based on pooled data from placebo cohorts of clinical trials offers short-term prognostic estimates that can be used for individual risk counseling. The aim of this study was to clarify if personalized prognostic information as presented by the OLAP tool is considered useful and meaningful by patients. Furthermore, we used the OLAP tool to evaluate patients' and physicians' risk estimates. Within this evaluation process we assessed short-time prognostic risk estimates of patients with MS (final n = 110) and their physicians (n = 6) and compared them with the estimates of OLAP. Patients rated the OLAP tool as understandable and acceptable, but to be only of moderate interest. It turned out that patients, physicians, and the OLAP tool ranked patients similarly regarding their risk of disease progression. Both patients' and physicians' estimates correlated most strongly with those disease covariates that the OLAP tool's estimates also correlated with most strongly. Exposure to the OLAP tool did not change patients' risk estimates. While the OLAP tool was rated understandable and acceptable, it was only of modest interest and did not change patients' prognostic estimates. The results suggest, however, that patients had some idea regarding their prognosis and which factors were most important in this regard. Future work with OLAP should assess long-term prognostic estimates and clarify its usefulness for patients and physicians

Multivariate Risk-Return Decision Making Within Dynamic Estimation

Directory of Open Access Journals (Sweden)

Josip Arnerić

2008-10-01

Full Text Available Risk management in this paper is focused on multivariate risk-return decision making assuming time-varying estimation. Empirical research in risk management showed that the static "mean-variance" methodology in portfolio optimization is very restrictive with unrealistic assumptions. The objective of this paper is estimation of time-varying portfolio stocks weights by constraints on risk measure. Hence, risk measure dynamic estimation is used in risk controlling. By risk control manager makes free supplementary capital for new investments.Univariate modeling approach is not appropriate, even when portfolio returns are treated as one variable. Portfolio weights are time-varying, and therefore it is necessary to reestimate whole model over time. Using assumption of bivariate Student´s t-distribution, in multivariate GARCH(p,q models, it becomes possible to forecast time-varying portfolio risk much more precisely. The complete procedure of analysis is established from Zagreb Stock Exchange using daily observations of Pliva and Podravka stocks.

Metamodeling-based approach for risk assessment and cost estimation: Application to geological carbon sequestration planning

Science.gov (United States)

Sun, Alexander Y.; Jeong, Hoonyoung; González-Nicolás, Ana; Templeton, Thomas C.

2018-04-01

Carbon capture and storage (CCS) is being evaluated globally as a geoengineering measure for significantly reducing greenhouse emission. However, long-term liability associated with potential leakage from these geologic repositories is perceived as a main barrier of entry to site operators. Risk quantification and impact assessment help CCS operators to screen candidate sites for suitability of CO2 storage. Leakage risks are highly site dependent, and a quantitative understanding and categorization of these risks can only be made possible through broad participation and deliberation of stakeholders, with the use of site-specific, process-based models as the decision basis. Online decision making, however, requires that scenarios be run in real time. In this work, a Python based, Leakage Assessment and Cost Estimation (PyLACE) web application was developed for quantifying financial risks associated with potential leakage from geologic carbon sequestration sites. PyLACE aims to assist a collaborative, analytic-deliberative decision making processes by automating metamodel creation, knowledge sharing, and online collaboration. In PyLACE, metamodeling, which is a process of developing faster-to-run surrogates of process-level models, is enabled using a special stochastic response surface method and the Gaussian process regression. Both methods allow consideration of model parameter uncertainties and the use of that information to generate confidence intervals on model outputs. Training of the metamodels is delegated to a high performance computing cluster and is orchestrated by a set of asynchronous job scheduling tools for job submission and result retrieval. As a case study, workflow and main features of PyLACE are demonstrated using a multilayer, carbon storage model.

A framework for estimating radiation-related cancer risks in Japan from the 2011 Fukushima nuclear accident.

Science.gov (United States)

Walsh, L; Zhang, W; Shore, R E; Auvinen, A; Laurier, D; Wakeford, R; Jacob, P; Gent, N; Anspaugh, L R; Schüz, J; Kesminiene, A; van Deventer, E; Tritscher, A; del Rosarion Pérez, M

2014-11-01

We present here a methodology for health risk assessment adopted by the World Health Organization that provides a framework for estimating risks from the Fukushima nuclear accident after the March 11, 2011 Japanese major earthquake and tsunami. Substantial attention has been given to the possible health risks associated with human exposure to radiation from damaged reactors at the Fukushima Daiichi nuclear power station. Cumulative doses were estimated and applied for each post-accident year of life, based on a reference level of exposure during the first year after the earthquake. A lifetime cumulative dose of twice the first year dose was estimated for the primary radionuclide contaminants ((134)Cs and (137)Cs) and are based on Chernobyl data, relative abundances of cesium isotopes, and cleanup efforts. Risks for particularly radiosensitive cancer sites (leukemia, thyroid and breast cancer), as well as the combined risk for all solid cancers were considered. The male and female cumulative risks of cancer incidence attributed to radiation doses from the accident, for those exposed at various ages, were estimated in terms of the lifetime attributable risk (LAR). Calculations of LAR were based on recent Japanese population statistics for cancer incidence and current radiation risk models from the Life Span Study of Japanese A-bomb survivors. Cancer risks over an initial period of 15 years after first exposure were also considered. LAR results were also given as a percentage of the lifetime baseline risk (i.e., the cancer risk in the absence of radiation exposure from the accident). The LAR results were based on either a reference first year dose (10 mGy) or a reference lifetime dose (20 mGy) so that risk assessment may be applied for relocated and non-relocated members of the public, as well as for adult male emergency workers. The results show that the major contribution to LAR from the reference lifetime dose comes from the first year dose. For a dose of 10 mGy in

Parametric estimation of P(X > Y) for normal distributions in the context of probabilistic environmental risk assessment.

Science.gov (United States)

Jacobs, Rianne; Bekker, Andriëtte A; van der Voet, Hilko; Ter Braak, Cajo J F

2015-01-01

Estimating the risk, P(X > Y), in probabilistic environmental risk assessment of nanoparticles is a problem when confronted by potentially small risks and small sample sizes of the exposure concentration X and/or the effect concentration Y. This is illustrated in the motivating case study of aquatic risk assessment of nano-Ag. A non-parametric estimator based on data alone is not sufficient as it is limited by sample size. In this paper, we investigate the maximum gain possible when making strong parametric assumptions as opposed to making no parametric assumptions at all. We compare maximum likelihood and Bayesian estimators with the non-parametric estimator and study the influence of sample size and risk on the (interval) estimators via simulation. We found that the parametric estimators enable us to estimate and bound the risk for smaller sample sizes and small risks. Also, the Bayesian estimator outperforms the maximum likelihood estimators in terms of coverage and interval lengths and is, therefore, preferred in our motivating case study.

Graphs to estimate an individualized risk of breast cancer.

Science.gov (United States)

Benichou, J; Gail, M H; Mulvihill, J J

1996-01-01

Clinicians who counsel women about their risk for developing breast cancer need a rapid method to estimate individualized risk (absolute risk), as well as the confidence limits around that point. The Breast Cancer Detection Demonstration Project (BCDDP) model (sometimes called the Gail model) assumes no genetic model and simultaneously incorporates five risk factors, but involves cumbersome calculations and interpolations. This report provides graphs to estimate the absolute risk of breast cancer from the BCDDP model. The BCDDP recruited 280,000 women from 1973 to 1980 who were monitored for 5 years. From this cohort, 2,852 white women developed breast cancer and 3,146 controls were selected, all with complete risk-factor information. The BCDDP model, previously developed from these data, was used to prepare graphs that relate a specific summary relative-risk estimate to the absolute risk of developing breast cancer over intervals of 10, 20, and 30 years. Once a summary relative risk is calculated, the appropriate graph is chosen that shows the 10-, 20-, or 30-year absolute risk of developing breast cancer. A separate graph gives the 95% confidence limits around the point estimate of absolute risk. Once a clinician rules out a single gene trait that predisposes to breast cancer and elicits information on age and four risk factors, the tables and figures permit an estimation of a women's absolute risk of developing breast cancer in the next three decades. These results are intended to be applied to women who undergo regular screening. They should be used only in a formal counseling program to maximize a woman's understanding of the estimates and the proper use of them.

Risk-based indicators of Canadians' exposures to environmental carcinogens.

Science.gov (United States)

Setton, Eleanor; Hystad, Perry; Poplawski, Karla; Cheasley, Roslyn; Cervantes-Larios, Alejandro; Keller, C Peter; Demers, Paul A

2013-02-12

Tools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers. Our objective was to develop indicators of population exposure to selected environmental carcinogens that can be easily updated over time, and allow comparisons and prioritization between different carcinogens and exposure pathways. We employed a risk assessment-based approach to produce screening-level estimates of lifetime excess cancer risk for selected substances listed as known carcinogens by the International Agency for Research on Cancer. Estimates of lifetime average daily intake were calculated using population characteristics combined with concentrations (circa 2006) in outdoor air, indoor air, dust, drinking water, and food and beverages from existing monitoring databases or comprehensive literature reviews. Intake estimates were then multiplied by cancer potency factors from Health Canada, the United States Environmental Protection Agency, and the California Office of Environmental Health Hazard Assessment to estimate lifetime excess cancer risks associated with each substance and exposure pathway. Lifetime excess cancer risks in excess of 1 per million people are identified as potential priorities for further attention. Based on data representing average conditions circa 2006, a total of 18 carcinogen-exposure pathways had potential lifetime excess cancer risks greater than 1 per million, based on varying data quality. Carcinogens with moderate to high data quality and lifetime excess cancer risk greater than 1 per million included benzene, 1,3-butadiene and radon in outdoor air; benzene and radon in indoor air; and arsenic and hexavalent chromium in drinking water. Important data gaps were identified for asbestos, hexavalent chromium and diesel exhaust in outdoor and indoor air, while little data were available to assess risk for substances in dust, food and beverages. The ability to

Development of cancer risk estimates from epidemiologic studies

International Nuclear Information System (INIS)

Webster, E.W.

1983-01-01

Radiation risk estimates may be made for an increase in mortality from, or for an increase in incidence of, particular types of disease. For both endpoints, two numerical systems of risk expression are used: the absolute risk system (usually the excess deaths or cases per million persons per year per rad), and the relative risk system (usually excess deaths or cases per year per rad expressed as a percentage of those normally expected). Risks may be calculated for specific age groups or for a general population. An alternative in both risk systems is the estimation of cumulative of lifetime risk rather than annual risk (e.g. in excess deaths per million per rad over a specified long period including the remainder of lifespan). The derivation of both absolute and relative risks is illustrated by examples. The effects on risk estimates of latent period, follow-up time, age at exposure and age standardization within dose groups are illustrated. The dependence of the projected cumulative (lifetime) risk on the adoption of a constant absolute risk or constant relative risk is noted. The use of life-table data in the adjustment of cumulative risk for normal mortality following single or annual doses is briefly discussed

Coronary risk assessment by point-based vs. equation-based Framingham models: significant implications for clinical care.

Science.gov (United States)

Gordon, William J; Polansky, Jesse M; Boscardin, W John; Fung, Kathy Z; Steinman, Michael A

2010-11-01

US cholesterol guidelines use original and simplified versions of the Framingham model to estimate future coronary risk and thereby classify patients into risk groups with different treatment strategies. We sought to compare risk estimates and risk group classification generated by the original, complex Framingham model and the simplified, point-based version. We assessed 2,543 subjects age 20-79 from the 2001-2006 National Health and Nutrition Examination Surveys (NHANES) for whom Adult Treatment Panel III (ATP-III) guidelines recommend formal risk stratification. For each subject, we calculated the 10-year risk of major coronary events using the original and point-based Framingham models, and then compared differences in these risk estimates and whether these differences would place subjects into different ATP-III risk groups (20% risk). Using standard procedures, all analyses were adjusted for survey weights, clustering, and stratification to make our results nationally representative. Among 39 million eligible adults, the original Framingham model categorized 71% of subjects as having "moderate" risk (20%) risk. Estimates of coronary risk by the original and point-based models often differed substantially. The point-based system classified 15% of adults (5.7 million) into different risk groups than the original model, with 10% (3.9 million) misclassified into higher risk groups and 5% (1.8 million) into lower risk groups, for a net impact of classifying 2.1 million adults into higher risk groups. These risk group misclassifications would impact guideline-recommended drug treatment strategies for 25-46% of affected subjects. Patterns of misclassifications varied significantly by gender, age, and underlying CHD risk. Compared to the original Framingham model, the point-based version misclassifies millions of Americans into risk groups for which guidelines recommend different treatment strategies.

12 CFR 955.6 - Risk-based capital requirement for acquired member assets.

Science.gov (United States)

2010-01-01

... losses as support for the credit risk of all AMA estimated by the Bank to represent a credit risk that is...) Recalculation of credit enhancement. For risk-based capital purposes, each Bank shall recalculate the estimated... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Risk-based capital requirement for acquired...

Effects of a risk-based online mammography intervention on accuracy of perceived risk and mammography intentions.

Science.gov (United States)

Seitz, Holli H; Gibson, Laura; Skubisz, Christine; Forquer, Heather; Mello, Susan; Schapira, Marilyn M; Armstrong, Katrina; Cappella, Joseph N

2016-10-01

This experiment tested the effects of an individualized risk-based online mammography decision intervention. The intervention employs exemplification theory and the Elaboration Likelihood Model of persuasion to improve the match between breast cancer risk and mammography intentions. 2918 women ages 35-49 were stratified into two levels of 10-year breast cancer risk (<1.5%; ≥1.5%) then randomly assigned to one of eight conditions: two comparison conditions and six risk-based intervention conditions that varied according to a 2 (amount of content: brief vs. extended) x 3 (format: expository vs. untailored exemplar [example case] vs. tailored exemplar) design. Outcomes included mammography intentions and accuracy of perceived breast cancer risk. Risk-based intervention conditions improved the match between objective risk estimates and perceived risk, especially for high-numeracy women with a 10-year breast cancer risk ≤1.5%. For women with a risk≤1.5%, exemplars improved accuracy of perceived risk and all risk-based interventions increased intentions to wait until age 50 to screen. A risk-based mammography intervention improved accuracy of perceived risk and the match between objective risk estimates and mammography intentions. Interventions could be applied in online or clinical settings to help women understand risk and make mammography decisions. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Cardiovascular risk estimation in older persons

DEFF Research Database (Denmark)

Cooney, Marie Therese; Selmer, Randi; Lindman, Anja

2016-01-01

.73 to 0.75). Calibration was also reasonable, Hosmer-Lemeshow goodness of fit test: 17.16 (men), 22.70 (women). Compared with the original SCORE function extrapolated to the ≥65 years age group discrimination improved, p = 0.05 (men), p women). Simple risk charts were constructed. On simulated...... risk estimation systems, that risk factors function similarly in all age groups. We aimed to derive and validate a risk estimation function, SCORE O.P., solely from data from individuals aged 65 years and older. METHODS AND RESULTS: 20,704 men and 20,121 women, aged 65 and over and without pre...... model and were included in the SCORE O.P. model were: age, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, smoking status and diabetes. SCORE O.P. showed good discrimination; area under receiver operator characteristic curve (AUROC) 0.74 (95% confidence interval: 0...

Methods for risk estimation in nuclear energy

Energy Technology Data Exchange (ETDEWEB)

Gauvenet, A [CEA, 75 - Paris (France)

1979-01-01

The author presents methods for estimating the different risks related to nuclear energy: immediate or delayed risks, individual or collective risks, risks of accidents and long-term risks. These methods have attained a highly valid level of elaboration and their application to other industrial or human problems is currently under way, especially in English-speaking countries.

Risk estimates for bone

International Nuclear Information System (INIS)

Schlenker, R.A.

1982-01-01

Bone sarcoma data for 226 228 Ra and 224 Ra are analyzed within the dosage ranges where the observed risk is zero. The uncertainty in the risk may be effectively illustrated by using pairs of functions based on a statistically-based measure of confidence. For radiation protection, the appropriate measure of risk is cumulative incidence in the presence of competing risks, as this takes into account the reduction of radiation effects brought about by natural mortality

Dynamic Estimation of Volatility Risk Premia and Investor Risk Aversion from Option-Implied and Realized Volatilities

DEFF Research Database (Denmark)

Bollerslev, Tim; Gibson, Michael; Zhou, Hao

experiment confirms that the procedure works well in practice. Implementing the procedure with actual S&P500 option-implied volatilities and high-frequency five-minute-based realized volatilities indicates significant temporal dependencies in the estimated stochastic volatility risk premium, which we in turn...

Estimation of baseline lifetime risk of developed cancer related to radiation exposure in China

International Nuclear Information System (INIS)

Li Xiaoliang; Niu Haowei; Sun Quanfu; Ma Weidong

2011-01-01

Objective: To introduce the general international method for estimation of lifetime risk of developed cancer, and to estimate the lifetime risk baseline values of several kinds of cancers related to radiation exposures in China. Methods: The risk estimation was based on the data from Chinese Cancer Registry Annual Report (2010) and China Population and Employment Statistics Yearbook (2009), and made according to the method previously published by National Cancer Institute (NCI) in USA. Results: The lifetime risk of all cancer in China in 2007 was estimated to be 27.77%, that of lung cancer 5.96%, that of breast cancer for female 3.34%, that of all leukemia 0.14%, that of thyroid cancer 0.37%. The lifetime risks of all cancer were estimated to be 32.74% for males and 24.73% for females, and that was 36.47% for urban residents and 26.79% for rural people. Conclusions: The lifetime risk of all cancer for males in 2007 was about 1.25 times as much as that for females. The value of all cancer for urban residents was about 1.35 times as much as that for rural residents. The lifetime risk of developed cancers in 2007 in China is lower than that in the developed countries,such as Japan. (authors)

Comments on mutagenesis risk estimation

International Nuclear Information System (INIS)

Russell, W.L.

1976-01-01

Several hypotheses and concepts have tended to oversimplify the problem of mutagenesis and can be misleading when used for genetic risk estimation. These include: the hypothesis that radiation-induced mutation frequency depends primarily on the DNA content per haploid genome, the extension of this concept to chemical mutagenesis, the view that, since DNA is DNA, mutational effects can be expected to be qualitatively similar in all organisms, the REC unit, and the view that mutation rates from chronic irradiation can be theoretically and accurately predicted from acute irradiation data. Therefore, direct determination of frequencies of transmitted mutations in mammals continues to be important for risk estimation, and the specific-locus method in mice is shown to be not as expensive as is commonly supposed for many of the chemical testing requirements

Psychological impact of providing women with personalised 10-year breast cancer risk estimates.

Science.gov (United States)

French, David P; Southworth, Jake; Howell, Anthony; Harvie, Michelle; Stavrinos, Paula; Watterson, Donna; Sampson, Sarah; Evans, D Gareth; Donnelly, Louise S

2018-05-08

The Predicting Risk of Cancer at Screening (PROCAS) study estimated 10-year breast cancer risk for 53,596 women attending NHS Breast Screening Programme. The present study, nested within the PROCAS study, aimed to assess the psychological impact of receiving breast cancer risk estimates, based on: (a) the Tyrer-Cuzick (T-C) algorithm including breast density or (b) T-C including breast density plus single-nucleotide polymorphisms (SNPs), versus (c) comparison women awaiting results. A sample of 2138 women from the PROCAS study was stratified by testing groups: T-C only, T-C(+SNPs) and comparison women; and by 10-year risk estimates received: 'moderate' (5-7.99%), 'average' (2-4.99%) or 'below average' (<1.99%) risk. Postal questionnaires were returned by 765 (36%) women. Overall state anxiety and cancer worry were low, and similar for women in T-C only and T-C(+SNPs) groups. Women in both T-C only and T-C(+SNPs) groups showed lower-state anxiety but slightly higher cancer worry than comparison women awaiting results. Risk information had no consistent effects on intentions to change behaviour. Most women were satisfied with information provided. There was considerable variation in understanding. No major harms of providing women with 10-year breast cancer risk estimates were detected. Research to establish the feasibility of risk-stratified breast screening is warranted.

Backtesting Portfolio Value-at-Risk with Estimated Portfolio Weights

OpenAIRE

Pei Pei

2010-01-01

This paper theoretically and empirically analyzes backtesting portfolio VaR with estimation risk in an intrinsically multivariate framework. For the first time in the literature, it takes into account the estimation of portfolio weights in forecasting portfolio VaR and its impact on backtesting. It shows that the estimation risk from estimating the portfolio weights as well as that from estimating the multivariate dynamic model of asset returns make the existing methods in a univariate framew...

Estimating Risk Parameters

OpenAIRE

Aswath Damodaran

1999-01-01

Over the last three decades, the capital asset pricing model has occupied a central and often controversial place in most corporate finance analysts’ tool chests. The model requires three inputs to compute expected returns – a riskfree rate, a beta for an asset and an expected risk premium for the market portfolio (over and above the riskfree rate). Betas are estimated, by most practitioners, by regressing returns on an asset against a stock index, with the slope of the regression being the b...

Estimation of insurance premiums for coverage against natural disaster risk: an application of Bayesian Inference

Directory of Open Access Journals (Sweden)

Y. Paudel

2013-03-01

Full Text Available This study applies Bayesian Inference to estimate flood risk for 53 dyke ring areas in the Netherlands, and focuses particularly on the data scarcity and extreme behaviour of catastrophe risk. The probability density curves of flood damage are estimated through Monte Carlo simulations. Based on these results, flood insurance premiums are estimated using two different practical methods that each account in different ways for an insurer's risk aversion and the dispersion rate of loss data. This study is of practical relevance because insurers have been considering the introduction of flood insurance in the Netherlands, which is currently not generally available.

Estimation of insurance premiums for coverage against natural disaster risk: an application of Bayesian Inference

Science.gov (United States)

Paudel, Y.; Botzen, W. J. W.; Aerts, J. C. J. H.

2013-03-01

This study applies Bayesian Inference to estimate flood risk for 53 dyke ring areas in the Netherlands, and focuses particularly on the data scarcity and extreme behaviour of catastrophe risk. The probability density curves of flood damage are estimated through Monte Carlo simulations. Based on these results, flood insurance premiums are estimated using two different practical methods that each account in different ways for an insurer's risk aversion and the dispersion rate of loss data. This study is of practical relevance because insurers have been considering the introduction of flood insurance in the Netherlands, which is currently not generally available.

[The concept of risk and its estimation].

Science.gov (United States)

Zocchetti, C; Della Foglia, M; Colombi, A

1996-01-01

The concept of risk, in relation to human health, is a topic of primary interest for occupational health professionals. A new legislation recently established in Italy (626/94) according to European Community directives in the field of Preventive Medicine, called attention to this topic, and in particular to risk assessment and evaluation. Motivated by this context and by the impression that the concept of risk is frequently misunderstood, the present paper has two aims: the identification of the different meanings of the term "risk" in the new Italian legislation and the critical discussion of some commonly used definitions; and the proposal of a general definition, with the specification of a mathematical expression for quantitative risk estimation. The term risk (and risk estimation, assessment, or evaluation) has mainly referred to three different contexts: hazard identification, exposure assessment, and adverse health effects occurrence. Unfortunately, there are contexts in the legislation in which it is difficult to identify the true meaning of the term. This might cause equivocal interpretations and erroneous applications of the law because hazard evaluation, exposure assessment, and adverse health effects identification are completely different topics that require integrated but distinct approaches to risk management. As far as a quantitative definition of risk is of concern, we suggest an algorithm which connects the three basic risk elements (hazard, exposure, adverse health effects) by means of their probabilities of occurrence: the probability of being exposed (to a definite dose) given that a specific hazard is present (Pr(e[symbol: see text]p)), and the probability of occurrence of an adverse health effect as a consequence of that exposure (Pr(d[symbol: see text]e)). Using these quantitative components, risk can be defined as a sequence of measurable events that starts with hazard identification and terminates with disease occurrence; therefore, the

Bayesian estimation of covariance matrices: Application to market risk management at EDF

International Nuclear Information System (INIS)

Jandrzejewski-Bouriga, M.

2012-01-01

In this thesis, we develop new methods of regularized covariance matrix estimation, under the Bayesian setting. The regularization methodology employed is first related to shrinkage. We investigate a new Bayesian modeling of covariance matrix, based on hierarchical inverse-Wishart distribution, and then derive different estimators under standard loss functions. Comparisons between shrunk and empirical estimators are performed in terms of frequentist performance under different losses. It allows us to highlight the critical importance of the definition of cost function and show the persistent effect of the shrinkage-type prior on inference. In a second time, we consider the problem of covariance matrix estimation in Gaussian graphical models. If the issue is well treated for the decomposable case, it is not the case if you also consider non-decomposable graphs. We then describe a Bayesian and operational methodology to carry out the estimation of covariance matrix of Gaussian graphical models, decomposable or not. This procedure is based on a new and objective method of graphical-model selection, combined with a constrained and regularized estimation of the covariance matrix of the model chosen. The procedures studied effectively manage missing data. These estimation techniques were applied to calculate the covariance matrices involved in the market risk management for portfolios of EDF (Electricity of France), in particular for problems of calculating Value-at-Risk or in Asset Liability Management. (author)

Future flood risk estimates along the river Rhine

Directory of Open Access Journals (Sweden)

A. H. te Linde

2011-02-01

Full Text Available In Europe, water management is moving from flood defence to a risk management approach, which takes both the probability and the potential consequences of flooding into account. It is expected that climate change and socio-economic development will lead to an increase in flood risk in the Rhine basin. To optimize spatial planning and flood management measures, studies are needed that quantify future flood risks and estimate their uncertainties. In this paper, we estimated the current and future fluvial flood risk in 2030 for the entire Rhine basin in a scenario study. The change in value at risk is based on two land-use projections derived from a land-use model representing two different socio-economic scenarios. Potential damage was calculated by a damage model, and changes in flood probabilities were derived from two climate scenarios and hydrological modeling. We aggregated the results into seven sections along the Rhine. It was found that the annual expected damage in the Rhine basin may increase by between 54% and 230%, of which the major part (~ three-quarters can be accounted for by climate change. The highest current potential damage can be found in the Netherlands (110 billion €, compared with the second (80 billion € and third (62 billion € highest values in two areas in Germany. Results further show that the area with the highest fluvial flood risk is located in the Lower Rhine in Nordrhein-Westfalen in Germany, and not in the Netherlands, as is often perceived. This is mainly due to the higher flood protection standards in the Netherlands as compared to Germany.

Uranium mill tailings and risk estimation

International Nuclear Information System (INIS)

Marks, S.

1984-04-01

Work done in estimating projected health effects for persons exposed to mill tailings at vicinity properties is described. The effect of the reassessment of exposures at Hiroshima and Nagasaki on the risk estimates for gamma radiation is discussed. A presentation of current results in the epidemiological study of Hanford workers is included. 2 references

Estimating Worker Risk Levels Using Accident/Incident Data

Energy Technology Data Exchange (ETDEWEB)

Kenoyer, Judson L.; Stenner, Robert D.; Andrews, William B.; Scherpelz, Robert I.; Aaberg, Rosanne L.

2000-09-26

The purpose of the work described in this report was to identify methods that are currently being used in the Department of Energy (DOE) complex to identify and control hazards/risks in the workplace, evaluate them in terms of their effectiveness in reducing risk to the workers, and to develop a preliminary method that could be used to predict the relative risks to workers performing proposed tasks using some of the current methodology. This report describes some of the performance indicators (i.e., safety metrics) that are currently being used to track relative levels of workplace safety in the DOE complex, how these fit into an Integrated Safety Management (ISM) system, some strengths and weaknesses of using a statistically based set of indicators, and methods to evaluate them. Also discussed are methods used to reduce risk to the workers and some of the techniques that appear to be working in the process of establishing a condition of continuous improvement. The results of these methods will be used in future work involved with the determination of modifying factors for a more complex model. The preliminary method to predict the relative risk level to workers during an extended future time period is based on a currently used performance indicator that uses several factors tracked in the CAIRS. The relative risks for workers in a sample (but real) facility on the Hanford site are estimated for a time period of twenty years and are based on workforce predictions. This is the first step in developing a more complex model that will incorporate other modifying factors related to the workers, work environment and status of the ISM system to adjust the preliminary prediction.

Risk-Based Sampling: I Don't Want to Weight in Vain.

Science.gov (United States)

Powell, Mark R

2015-12-01

Recently, there has been considerable interest in developing risk-based sampling for food safety and animal and plant health for efficient allocation of inspection and surveillance resources. The problem of risk-based sampling allocation presents a challenge similar to financial portfolio analysis. Markowitz (1952) laid the foundation for modern portfolio theory based on mean-variance optimization. However, a persistent challenge in implementing portfolio optimization is the problem of estimation error, leading to false "optimal" portfolios and unstable asset weights. In some cases, portfolio diversification based on simple heuristics (e.g., equal allocation) has better out-of-sample performance than complex portfolio optimization methods due to estimation uncertainty. Even for portfolios with a modest number of assets, the estimation window required for true optimization may imply an implausibly long stationary period. The implications for risk-based sampling are illustrated by a simple simulation model of lot inspection for a small, heterogeneous group of producers. © 2015 Society for Risk Analysis.

Fatalities in high altitude mountaineering: a review of quantitative risk estimates.

Science.gov (United States)

Weinbruch, Stephan; Nordby, Karl-Christian

2013-12-01

Quantitative estimates for mortality in high altitude mountaineering are reviewed. Special emphasis is placed on the heterogeneity of the risk estimates and on confounding. Crude estimates for mortality are on the order of 1/1000 to 40/1000 persons above base camp, for both expedition members and high altitude porters. High altitude porters have mostly a lower risk than expedition members (risk ratio for all Nepalese peaks requiring an expedition permit: 0.73; 95 % confidence interval 0.59-0.89). The summit bid is generally the most dangerous part of an expedition for members, whereas most high altitude porters die during route preparation. On 8000 m peaks, the mortality during descent from summit varies between 4/1000 and 134/1000 summiteers (members plus porters). The risk estimates are confounded by human and environmental factors. Information on confounding by gender and age is contradictory and requires further work. There are indications for safety segregation of men and women, with women being more risk averse than men. Citizenship appears to be a significant confounder. Prior high altitude mountaineering experience in Nepal has no protective effect. Commercial expeditions in the Nepalese Himalayas have a lower mortality than traditional expeditions, though after controlling for confounding, the difference is not statistically significant. The overall mortality is increasing with increasing peak altitude for expedition members but not for high altitude porters. In the Nepalese Himalayas and in Alaska, a significant decrease of mortality with calendar year was observed. A few suggestions for further work are made at the end of the article.

Use of GIS in the estimation and development of risk reduction technology

International Nuclear Information System (INIS)

Ha, Jae Joo

1998-03-01

The occurrence probability of a severe accident in the nuclear power plant is very small because the safety of a plant and the public is considered in the design and operation of a nuclear power plant. However, if a severe accident occurs, the establishment of a reduction strategy of damages resulting from it is essential because the effect of it on the human and the environment is very large. The important criterion which determines the severity of an accident is risk, which is defined as the product of its frequently and the consequence. The establishment of countermeasures in order to estimate and reduce risks quantitatively can be a very powerful tool to minimize the effect of an accident on the human and the environment. The research on the establishment of a framework which integrates a geographic information system (GIS), a database management system (DBMS), and decision making support system (DMSS) is considered very actively. Based on these systems, we can accomplish the estimation and display of risks and the development of reduction methodologies which are essential parts of an accident management of a nuclear power plant. The GIS plays a role to support users to systematize and comprehend spatial relationships of information which are necessary for the decision making. Through the DBMS, we can establish and manage spatial and attribute data, and use them in the query and selection. The DMSS is a computer-based information system which makes a necessary decision easily. In this study, we reviewed the fundamental concepts of a GIS and examined the methodology for the use of it in the estimation and display of risks. Also, we established the fundamental GIS platform of a Yonggwang site and the necessary database systems for the estimation of risks. (author). 17 refs., 9 tabs., 34 figs

Assessment of Methods for Estimating Risk to Birds from ...

Science.gov (United States)

The U.S. EPA Ecological Risk Assessment Support Center (ERASC) announced the release of the final report entitled, Assessment of Methods for Estimating Risk to Birds from Ingestion of Contaminated Grit Particles. This report evaluates approaches for estimating the probability of ingestion by birds of contaminated particles such as pesticide granules or lead particles (i.e. shot or bullet fragments). In addition, it presents an approach for using this information to estimate the risk of mortality to birds from ingestion of lead particles. Response to ERASC Request #16

A Study on the Estimation Method of Risk Based Area for Jetty Safety Monitoring

Directory of Open Access Journals (Sweden)

Byeong-Wook Nam

2015-09-01

Full Text Available Recently, the importance of safety-monitoring systems was highlighted by the unprecedented collision between a ship and a jetty in Yeosu. Accordingly, in this study, we introduce the concept of risk based area and develop a methodology for a jetty safety-monitoring system. By calculating the risk based areas for a ship and a jetty, the risk of collision was evaluated. To calculate the risk based areas, we employed an automatic identification system for the ship, stopping-distance equations, and the regulation velocity near the jetty. In this paper, we suggest a risk calculation method for jetty safety monitoring that can determine the collision probability in real time and predict collisions using the amount of overlap between the two calculated risk based areas. A test was conducted at a jetty control center at GS Caltex, and the effectiveness of the proposed risk calculation method was verified. The method is currently applied to the jetty-monitoring system at GS Caltex in Yeosu for the prevention of collisions.

A Knowledge-Based Model of Audit Risk

OpenAIRE

Dhar, Vasant; Lewis, Barry; Peters, James

1988-01-01

Within the academic and professional auditing communities, there has been growing concern about how to accurately assess the various risks associated with performing an audit. These risks are difficult to conceptualize in terms of numeric estimates. This article discusses the development of a prototype computational model (computer program) that assesses one of the major audit risks -- inherent risk. This program bases most of its inferencing activities on a qualitative model of a typical bus...

A Web-Based System for Bayesian Benchmark Dose Estimation.

Science.gov (United States)

Shao, Kan; Shapiro, Andrew J

2018-01-11

Benchmark dose (BMD) modeling is an important step in human health risk assessment and is used as the default approach to identify the point of departure for risk assessment. A probabilistic framework for dose-response assessment has been proposed and advocated by various institutions and organizations; therefore, a reliable tool is needed to provide distributional estimates for BMD and other important quantities in dose-response assessment. We developed an online system for Bayesian BMD (BBMD) estimation and compared results from this software with U.S. Environmental Protection Agency's (EPA's) Benchmark Dose Software (BMDS). The system is built on a Bayesian framework featuring the application of Markov chain Monte Carlo (MCMC) sampling for model parameter estimation and BMD calculation, which makes the BBMD system fundamentally different from the currently prevailing BMD software packages. In addition to estimating the traditional BMDs for dichotomous and continuous data, the developed system is also capable of computing model-averaged BMD estimates. A total of 518 dichotomous and 108 continuous data sets extracted from the U.S. EPA's Integrated Risk Information System (IRIS) database (and similar databases) were used as testing data to compare the estimates from the BBMD and BMDS programs. The results suggest that the BBMD system may outperform the BMDS program in a number of aspects, including fewer failed BMD and BMDL calculations and estimates. The BBMD system is a useful alternative tool for estimating BMD with additional functionalities for BMD analysis based on most recent research. Most importantly, the BBMD has the potential to incorporate prior information to make dose-response modeling more reliable and can provide distributional estimates for important quantities in dose-response assessment, which greatly facilitates the current trend for probabilistic risk assessment. https://doi.org/10.1289/EHP1289.

Estimation, assessment and management of risks

International Nuclear Information System (INIS)

Reinoehl-Kompa, S.

2005-01-01

After the introductory lectures the closed conference divided into sessions on the estimation, assessment and management of risks. This review article summarises some of the central issues which were addressed in the discussions held during the closed conference and which may be of significance for the future work of the ''Radiation Risk'' Committee within the Radiation Protection Commission. Fundamental difficulties still persist in the implementation of risk quantities within the concepts of radiation protection (lectures by Breckow and Kiefer). Some of these difficulties have to do with the definition of dose quantities, in particular with the one most central to radiation protection, the effective dose. In the field of sparsely ionizing radiation attention was focused on two main topics, namely the risk of acquiring thyroid cancer in association with the Chernobyl desaster and analyses of new mortality data on the survivors of the nuclear bomb attacks on Hiroshima and Nagasaki. In the area of lung cancer risk from radon exposure, attention was focused on indoor exposure and the cohort study on bismuth miners. The body of knowledge that has accumulated on the risk of acquiring cancer through UV radiation takes a special position within the wider field of risks associated with nonionizing radiation, since much has already been achieved towards identifying the action mechanisms involved here. Since skin cancer shows the highest increments in incidence of all types of cancer, estimating the risk of acquiring skin cancer through UV radiation will be an important issue in future. One of the tasks of risk management is to translate the results of risk assessment into action. One task of particular importance in this regard is ''risk communication'', the problems surrounding which were illuminated from different perspectives in various contributions

41 CFR 102-80.50 - Are Federal agencies responsible for identifying/estimating risks and for appropriate risk...

Science.gov (United States)

2010-07-01

... Environmental Management Risks and Risk Reduction Strategies § 102-80.50 Are Federal agencies responsible for... identify and estimate safety and environmental management risks and appropriate risk reduction strategies... responsible for identifying/estimating risks and for appropriate risk reduction strategies? 102-80.50 Section...

Estimating oil price 'Value at Risk' using the historical simulation approach

International Nuclear Information System (INIS)

David Cabedo, J.; Moya, Ismael

2003-01-01

In this paper we propose using Value at Risk (VaR) for oil price risk quantification. VaR provides an estimation for the maximum oil price change associated with a likelihood level, and can be used for designing risk management strategies. We analyse three VaR calculation methods: the historical simulation standard approach, the historical simulation with ARMA forecasts (HSAF) approach, developed in this paper, and the variance-covariance method based on autoregressive conditional heteroskedasticity models forecasts. The results obtained indicate that HSAF methodology provides a flexible VaR quantification, which fits the continuous oil price movements well and provides an efficient risk quantification

Estimating oil price 'Value at Risk' using the historical simulation approach

International Nuclear Information System (INIS)

Cabedo, J.D.; Moya, I.

2003-01-01

In this paper we propose using Value at Risk (VaR) for oil price risk quantification. VaR provides an estimation for the maximum oil price change associated with a likelihood level, and can be used for designing risk management strategies. We analyse three VaR calculation methods: the historical simulation standard approach, the historical simulation with ARMA forecasts (HSAF) approach. developed in this paper, and the variance-covariance method based on autoregressive conditional heteroskedasticity models forecasts. The results obtained indicate that HSAF methodology provides a flexible VaR quantification, which fits the continuous oil price movements well and provides an efficient risk quantification. (author)

12 CFR 652.65 - Risk-based capital stress test.

Science.gov (United States)

2010-01-01

...) You will use Corporation loan-level data to implement the credit risk component of the risk-based... Service corporate income tax schedule, as further described in appendix A to this subpart. (b) Credit risk. The credit risk part estimates loan losses during a period of sustained economic stress. (1) For each...

Revision of risk estimates and implications for dose limits

International Nuclear Information System (INIS)

Clarke, R.H.

1989-01-01

It has been apparent for some time that our estimates of the risks associated with exposure to ionizing radiation must be increased above those values reported by UNSCEAR in 1977 an dused by ICRP to form their present recommendations. NRPB foresaw some of these changes and introduced interim advice within the UK to restrict exposures of wordkers and members of the public to levels below the existing limits. Since that advice was given, UNSCEAR has produced a 1988 report reviewing human data to provide new estimates of risks associated with exposure at high doses and high doserates. These risk figures are up to 4 times higher than when UNSCEAR reported in 1977. In this paper, the reasons for the changes in the estimates of risk will be described and the current NRPB guidelines for risk factors for protection purposes will be presented. The implications of these new risk factors for the setting of dose limits will then be discussed. (Author). 10 refs.; 2 tabs

The estimation of small probabilities and risk assessment

International Nuclear Information System (INIS)

Kalbfleisch, J.D.; Lawless, J.F.; MacKay, R.J.

1982-01-01

The primary contribution of statistics to risk assessment is in the estimation of probabilities. Frequently the probabilities in question are small, and their estimation is particularly difficult. The authors consider three examples illustrating some problems inherent in the estimation of small probabilities

A novel SURE-based criterion for parametric PSF estimation.

Science.gov (United States)

Xue, Feng; Blu, Thierry

2015-02-01

We propose an unbiased estimate of a filtered version of the mean squared error--the blur-SURE (Stein's unbiased risk estimate)--as a novel criterion for estimating an unknown point spread function (PSF) from the degraded image only. The PSF is obtained by minimizing this new objective functional over a family of Wiener processings. Based on this estimated blur kernel, we then perform nonblind deconvolution using our recently developed algorithm. The SURE-based framework is exemplified with a number of parametric PSF, involving a scaling factor that controls the blur size. A typical example of such parametrization is the Gaussian kernel. The experimental results demonstrate that minimizing the blur-SURE yields highly accurate estimates of the PSF parameters, which also result in a restoration quality that is very similar to the one obtained with the exact PSF, when plugged into our recent multi-Wiener SURE-LET deconvolution algorithm. The highly competitive results obtained outline the great potential of developing more powerful blind deconvolution algorithms based on SURE-like estimates.

Risk estimation for carcinogens based on epidemiological data: A structured approach, illustrated by an example on chromium

NARCIS (Netherlands)

Goldbohm, R.A.; Tielemans, E.L.J.P.; Heederik, D.; Rubingh, C.M.; Dekkers, S.; Willems, M.I.; Dinant Kroese, E.

2006-01-01

It is generally recognized that human, epidemiological data, if available, are preferred as the starting point for quantitative risk analysis above the use of data from animal studies. Although methods to obtain proper risk estimates from epidemiological data are available, several impediments

The impact of advances in human molecular biology on radiation genetic risk estimation in man

International Nuclear Information System (INIS)

Sankaranarayanan, K.

1996-01-01

This paper provides an overview of the conceptual framework, the data base, methods and assumptions used thus far to assess the genetic risks of exposure of human populations to ionising radiation. These are then re-examined in the contemporary context of the rapidly expanding knowledge of the molecular biology of human mendelian diseases. This re-examination reveals that (i) many of the assumptions used thus far in radiation genetic risk estimation may not be fully valid and (ii) the current genetic risk estimates are probably conservative, but provide an adequate margin of safety for radiological protection. The view is expressed that further advances in the field of genetic risk estimation will be largely driven by advances in the molecular biology of human genetic diseases. (author). 37 refs., 5 tabs

Assessing the risk of Legionnaires' disease: the inhalation exposure model and the estimated risk in residential bathrooms.

Science.gov (United States)

Azuma, Kenichi; Uchiyama, Iwao; Okumura, Jiro

2013-02-01

Legionella are widely found in the built environment. Patients with Legionnaires' disease have been increasing in Japan; however, health risks from Legionella bacteria in the environment are not appropriately assessed. We performed a quantitative health risk assessment modeled on residential bathrooms in the Adachi outbreak area and estimated risk levels. The estimated risks in the Adachi outbreak approximately corresponded to the risk levels exponentially extrapolated into lower levels on the basis of infection and mortality rates calculated from actual outbreaks, suggesting that the model of Legionnaires' disease in residential bathrooms was adequate to predict disease risk for the evaluated outbreaks. Based on this model, the infection and mortality risk levels per year in 10 CFU/100 ml (100 CFU/L) of the Japanese water quality guideline value were approximately 10(-2) and 10(-5), respectively. However, acceptable risk levels of infection and mortality from Legionnaires' disease should be adjusted to approximately 10(-4) and 10(-7), respectively, per year. Therefore, a reference value of 0.1 CFU/100 ml (1 CFU/L) as a water quality guideline for Legionella bacteria is recommended. This value is occasionally less than the actual detection limit. Legionella levels in water system should be maintained as low as reasonably achievable (<1 CFU/L). Copyright © 2012 Elsevier Inc. All rights reserved.

Best-Estimates in Bond Markets with Reinvestment Risk

Directory of Open Access Journals (Sweden)

Anne MacKay

2015-07-01

Full Text Available The concept of best-estimate, prescribed by regulators to value insurance liabilities for accounting and solvency purposes, has recently been discussed extensively in the industry and related academic literature. To differentiate hedgeable and non-hedgeable risks in a general case, recent literature defines best-estimates using orthogonal projections of a claim on the space of replicable payoffs. In this paper, we apply this concept of best-estimate to long-maturity claims in a market with reinvestment risk, since in this case the total liability cannot easily be separated into hedgeable and non-hedgeable parts. We assume that a limited number of short-maturity bonds are traded, and derive the best-estimate price of bonds with longer maturities, thus obtaining a best-estimate yield curve. We therefore use the multifactor Vasiˇcek model and derive within this framework closed-form expressions for the best-estimate prices of long-term bonds.

Risk-based rules for crane safety systems

Energy Technology Data Exchange (ETDEWEB)

Ruud, Stian [Section for Control Systems, DNV Maritime, 1322 Hovik (Norway)], E-mail: Stian.Ruud@dnv.com; Mikkelsen, Age [Section for Lifting Appliances, DNV Maritime, 1322 Hovik (Norway)], E-mail: Age.Mikkelsen@dnv.com

2008-09-15

The International Maritime Organisation (IMO) has recommended a method called formal safety assessment (FSA) for future development of rules and regulations. The FSA method has been applied in a pilot research project for development of risk-based rules and functional requirements for systems and components for offshore crane systems. This paper reports some developments in the project. A method for estimating target reliability for the risk-control options (safety functions) by means of the cost/benefit decision criterion has been developed in the project and is presented in this paper. Finally, a structure for risk-based rules is proposed and presented.

Risk-based rules for crane safety systems

International Nuclear Information System (INIS)

Ruud, Stian; Mikkelsen, Age

2008-01-01

The International Maritime Organisation (IMO) has recommended a method called formal safety assessment (FSA) for future development of rules and regulations. The FSA method has been applied in a pilot research project for development of risk-based rules and functional requirements for systems and components for offshore crane systems. This paper reports some developments in the project. A method for estimating target reliability for the risk-control options (safety functions) by means of the cost/benefit decision criterion has been developed in the project and is presented in this paper. Finally, a structure for risk-based rules is proposed and presented

Population-based estimate of sibling risk for preterm birth, preterm premature rupture of membranes, placental abruption and pre-eclampsia.

Science.gov (United States)

Plunkett, Jevon; Borecki, Ingrid; Morgan, Thomas; Stamilio, David; Muglia, Louis J

2008-07-08

Adverse pregnancy outcomes, such as preterm birth, preeclampsia and placental abruption, are common, with acute and long-term complications for both the mother and infant. Etiologies underlying such adverse outcomes are not well understood. As maternal and fetal genetic factors may influence these outcomes, we estimated the magnitude of familial aggregation as one index of possible heritable contributions. Using the Missouri Department of Health's maternally-linked birth certificate database, we performed a retrospective population-based cohort study of births (1989-1997), designating an individual born from an affected pregnancy as the proband for each outcome studied. We estimated the increased risk to siblings compared to the population risk, using the sibling risk ratio, lambdas, and sibling-sibling odds ratio (sib-sib OR), for the adverse pregnancy outcomes of preterm birth, preterm premature rupture of membranes (PPROM), placental abruption, and pre-eclampsia. Risk to siblings of an affected individual was elevated above the population prevalence of a given disorder, as indicated by lambdaS (lambdaS (95% CI): 4.3 (4.0-4.6), 8.2 (6.5-9.9), 4.0 (2.6-5.3), and 4.5 (4.4-4.8), for preterm birth, PPROM, placental abruption, and pre-eclampsia, respectively). Risk to siblings of an affected individual was similarly elevated above that of siblings of unaffected individuals, as indicated by the sib-sib OR (sib-sib OR adjusted for known risk factors (95% CI): 4.2 (3.9-4.5), 9.6 (7.6-12.2), 3.8 (2.6-5.5), 8.1 (7.5-8.8) for preterm birth, PPROM, placental abruption, and pre-eclampsia, respectively). These results suggest that the adverse pregnancy outcomes of preterm birth, PPROM, placental abruption, and pre-eclampsia aggregate in families, which may be explained in part by genetics.

Urban micro-scale flood risk estimation with parsimonious hydraulic modelling and census data

Directory of Open Access Journals (Sweden)

C. Arrighi

2013-05-01

Full Text Available The adoption of 2007/60/EC Directive requires European countries to implement flood hazard and flood risk maps by the end of 2013. Flood risk is the product of flood hazard, vulnerability and exposure, all three to be estimated with comparable level of accuracy. The route to flood risk assessment is consequently much more than hydraulic modelling of inundation, that is hazard mapping. While hazard maps have already been implemented in many countries, quantitative damage and risk maps are still at a preliminary level. A parsimonious quasi-2-D hydraulic model is here adopted, having many advantages in terms of easy set-up. It is here evaluated as being accurate in flood depth estimation in urban areas with a high-resolution and up-to-date Digital Surface Model (DSM. The accuracy, estimated by comparison with marble-plate records of a historic flood in the city of Florence, is characterized in the downtown's most flooded area by a bias of a very few centimetres and a determination coefficient of 0.73. The average risk is found to be about 14 € m−2 yr−1, corresponding to about 8.3% of residents' income. The spatial distribution of estimated risk highlights a complex interaction between the flood pattern and the building characteristics. As a final example application, the estimated risk values have been used to compare different retrofitting measures. Proceeding through the risk estimation steps, a new micro-scale potential damage assessment method is proposed. This is based on the georeferenced census system as the optimal compromise between spatial detail and open availability of socio-economic data. The results of flood risk assessment at the census section scale resolve most of the risk spatial variability, and they can be easily aggregated to whatever upper scale is needed given that they are geographically defined as contiguous polygons. Damage is calculated through stage–damage curves, starting from census data on building type and

Estimating radiation risk induced by CT screening for Korean population

Science.gov (United States)

Yang, Won Seok; Yang, Hye Jeong; Min, Byung In

2017-02-01

The purposes of this study are to estimate the radiation risks induced by chest/abdomen computed tomography (CT) screening for healthcare and to determine the cancer risk level of the Korean population compared to other populations. We used an ImPACT CT Patient Dosimetry Calculator to compute the organ effective dose induced by CT screening (chest, low-dose chest, abdomen/pelvis, and chest/abdomen/pelvis CT). A risk model was applied using principles based on the BEIR VII Report in order to estimate the lifetime attributable risk (LAR) using the Korean Life Table 2010. In addition, several countries including Hong Kong, the United States (U.S.), and the United Kingdom, were selected for comparison. Herein, each population exposed radiation dose of 100 mSv was classified according to country, gender and age. For each CT screening the total organ effective dose calculated by ImPACT was 6.2, 1.5, 5.2 and 11.4 mSv, respectively. In the case of Korean female LAR, it was similar to Hong Kong female but lower than those of U.S. and U.K. females, except for those in their twenties. The LAR of Korean males was the highest for all types of CT screening. However, the difference of the risk level was negligible because of the quite low value.

Seismic Risk Assessment and Loss Estimation for Tbilisi City

Science.gov (United States)

Tsereteli, Nino; Alania, Victor; Varazanashvili, Otar; Gugeshashvili, Tengiz; Arabidze, Vakhtang; Arevadze, Nika; Tsereteli, Emili; Gaphrindashvili, Giorgi; Gventcadze, Alexander; Goguadze, Nino; Vephkhvadze, Sophio

2013-04-01

The proper assessment of seismic risk is of crucial importance for society protection and city sustainable economic development, as it is the essential part to seismic hazard reduction. Estimation of seismic risk and losses is complicated tasks. There is always knowledge deficiency on real seismic hazard, local site effects, inventory on elements at risk, infrastructure vulnerability, especially for developing countries. Lately great efforts was done in the frame of EMME (earthquake Model for Middle East Region) project, where in the work packages WP1, WP2 , WP3 and WP4 where improved gaps related to seismic hazard assessment and vulnerability analysis. Finely in the frame of work package wp5 "City Scenario" additional work to this direction and detail investigation of local site conditions, active fault (3D) beneath Tbilisi were done. For estimation economic losses the algorithm was prepared taking into account obtained inventory. The long term usage of building is very complex. It relates to the reliability and durability of buildings. The long term usage and durability of a building is determined by the concept of depreciation. Depreciation of an entire building is calculated by summing the products of individual construction unit' depreciation rates and the corresponding value of these units within the building. This method of calculation is based on an assumption that depreciation is proportional to the building's (constructions) useful life. We used this methodology to create a matrix, which provides a way to evaluate the depreciation rates of buildings with different type and construction period and to determine their corresponding value. Finally loss was estimated resulting from shaking 10%, 5% and 2% exceedance probability in 50 years. Loss resulting from scenario earthquake (earthquake with possible maximum magnitude) also where estimated.

Cancer risk estimation for mixtures of coal tars and benzo(a)pyrene

International Nuclear Information System (INIS)

Gaylor, D.W.; Culp, S.J.; Goldstein, L.S.; Beland, F.A.

2000-01-01

Two-year chronic bioassays were conducted by using B6C3F1 female mice fed several concentrations of two different mixtures of coal tars from manufactured gas waste sites or benzo(a)pyrene (BaP). The purpose of the study was to obtain estimates of cancer potency of coal tar mixtures, by using conventional regulatory methods, for use in manufactured gas waste site remediation. A secondary purpose was to investigate the validity of using the concentration of a single potent carcinogen, in this case benzo(a)pyrene, to estimate the relative risk for a coal tar mixture. The study has shown that BaP dominates the cancer risk when its concentration is greater than 6,300 ppm in the coal tar mixture. In this case the most sensitive tissue site is the forestomach. Using low-dose linear extrapolation, the lifetime cancer risk for humans is estimated to be: Risk -4 (ppm coal tar in total diet) + 240 x 10 -4 (ppm BaP in total diet), based on forestomach tumors. If the BaP concentration in the coal tar mixture is less than 6,300 ppm, the more likely case, then lung tumors provide the largest estimated upper limit of risk, Risk -4 (ppm coal tar in total diet), with no contribution of BaP to lung tumors. The upper limit of the cancer potency (slope factor) for lifetime oral exposure to benzo(a)pyrene is 1.2 x 10 -3 per microg per kg body weight per day from this Good Laboratory Practice (GLP) study compared with the current value of 7.3 x 10 -3 per microg per kg body weight per day listed in the US EPA Integrated Risk Information System

New risk estimates at low doses

International Nuclear Information System (INIS)

Fry, R.J.M.

1992-01-01

The age of molecular radiation epidemiology may be at hand. The techniques are available to establish with the degree of precision required to determine whether agent-specific mutations can be identified consistently. A concerted effort to examine radiation-induced changes in as many relevant genes as possible appears to be justified. Cancers in those exposed to low doses of ionizing radiation should be chosen for the investigation. Parallel studies of radiation-induced cancers in experimental animals would not only complement the human studies, but perhaps reveal approaches to extrapolation of risk estimates across species. A caveat should be added to this optimistic view of what molecular studies might contribute to the knotty problem of risk estimates at low doses. The suggestions are made by one with no expertise in the field of molecular biology

Questionnaire-based risk assessment system

International Nuclear Information System (INIS)

Sakajo, Satoko; Ohi, Tadashi

2004-01-01

In order to reduce human errors efficiently, it is important to evaluate error-likely tasks and improve them. There are a lot of evaluation methods, for example, experimental evaluation methods, investigations by the expert of human factors, checking guidelines, estimating human error probabilities, and so on. There are roughly two problems in those methods. (1) Qualitative evaluation methods do not evaluate how likely human errors will occur and do not estimate how effective the countermeasure is in reducing human error. (2) Most of the quantitative evaluation methods and detailed analysis methods require expert's judgment. We developed a questionnaire-based risk assessment method and its system. In this paper, we introduce the concept of the method, realization, and applications to a maintenance procedure of a nuclear power plant and an elevator. The feature of the method is that it is so simple and the inexpert can easily evaluate the risk of human error. Furthermore, because it is provided as an application service provider system, a lot of evaluators can use it simultaneously through internet and it is easy to collect and sum up the responses. We confirmed that it is useful to evaluate the risk of human error, analyze the problem, and estimate the effectiveness of countermeasures in advance through the applications. (author)

Prostate cancer risk prediction based on complete prostate cancer family history

OpenAIRE

Albright, Frederick; Stephenson, Robert A; Agarwal, Neeraj; Teerlink, Craig C; Lowrance, William T; Farnham, James M; Albright, Lisa A Cannon

2014-01-01

Background Prostate cancer (PC) relative risks (RRs) are typically estimated based on status of close relatives or presence of any affected relatives. This study provides RR estimates using extensive and specific PC family history. Methods A retrospective population-based study was undertaken to estimate RRs for PC based on complete family history of PC. A total of 635,443 males, all with ancestral genealogy data, were analyzed. RRs for PC were determined based upon PC rates estimated from ma...

Estimating cancer risk from outdoor concentrations of hazardous air pollutants in 1990

Energy Technology Data Exchange (ETDEWEB)

Woodruff, T.J.; Caldwell, J.; Cogliano, V.J.; Axelrad, D.A.

2000-03-01

A public health concern regarding hazardous air pollutants (HAPs) is their potential to cause cancer. It has been difficult to assess potential cancer risks from HAPs, due primarily to lack of ambient concentration data for the general population. The Environmental Protection Agency's Cumulative Exposure Project modeled 1990 outdoor concentrations of HAPs across the United States, which were combined with inhalation unit risk estimates to estimate the potential increase in excess cancer risk for individual carcinogenic HAPs. These were summed3d to provide an estimate of cancer risk from multiple HAPs. The analysis estimates a median excess cancer risk of 18 lifetime cancer cases per 100,000 people for all HAP concentrations. About 75% of estimated cancer risk was attributable to exposure to polycyclic organic matter, 1,3-butadiene, formaldehyde, benzene, and chromium. Consideration of some specific uncertainties, including underestimation of ambient concentrations, combining upper 95% confidence bound potency estimates, and changes to potency estimates, found that cancer risk may be underestimated by 15% or overestimated by 40--50%. Other unanalyzed uncertainties could make these under- or overestimates larger. This analysis used 1990 estimates of concentrations and can be used to track progress toward reducing cancer risk to the general population.

Probabilistic fuzzy systems in value-at-risk estimation

NARCIS (Netherlands)

Almeida, R.J.; Kaymak, U.

2009-01-01

Value-at-risk (VaR) is a popular measure for quantifying the market risk that a financial institution faces into a single number. Owing to the complexity of financial markets, the risks associated with a portfolio varies over time. Consequently, advanced methods of VaR estimation use parametric

An interim UK response to revised risk estimates

International Nuclear Information System (INIS)

Beaver, P.F.; Bines, W.P.

1992-01-01

This paper describes the legal framework in place when the revised risk estimates were announced by the International Commission for Radiological Protection (ICRP) in 1987 and how an addition to that framework enabled the revised risk estimates to be taken into account when making decisions about radiation protection practice both at plant and individual worker level. It is suggested that this a may be an early example of the use of a constraint applied generically. (author)

Sensitivity Analysis of Median Lifetime on Radiation Risks Estimates for Cancer and Circulatory Disease amongst Never-Smokers

Science.gov (United States)

Chappell, Lori J.; Cucinotta, Francis A.

2011-01-01

Radiation risks are estimated in a competing risk formalism where age or time after exposure estimates of increased risks for cancer and circulatory diseases are folded with a probability to survive to a given age. The survival function, also called the life-table, changes with calendar year, gender, smoking status and other demographic variables. An outstanding problem in risk estimation is the method of risk transfer between exposed populations and a second population where risks are to be estimated. Approaches used to transfer risks are based on: 1) Multiplicative risk transfer models -proportional to background disease rates. 2) Additive risk transfer model -risks independent of background rates. In addition, a Mixture model is often considered where the multiplicative and additive transfer assumptions are given weighted contributions. We studied the influence of the survival probability on the risk of exposure induced cancer and circulatory disease morbidity and mortality in the Multiplicative transfer model and the Mixture model. Risks for never-smokers (NS) compared to the average U.S. population are estimated to be reduced between 30% and 60% dependent on model assumptions. Lung cancer is the major contributor to the reduction for NS, with additional contributions from circulatory diseases and cancers of the stomach, liver, bladder, oral cavity, esophagus, colon, a portion of the solid cancer remainder, and leukemia. Greater improvements in risk estimates for NS s are possible, and would be dependent on improved understanding of risk transfer models, and elucidating the role of space radiation on the various stages of disease formation (e.g. initiation, promotion, and progression).

Residual risk over-estimated

International Nuclear Information System (INIS)

Anon.

1982-01-01

The way nuclear power plants are built practically excludes accidents with serious consequences. This is attended to by careful selection of material, control of fabrication and regular retesting as well as by several safety systems working independently. But the remaining risk, a 'hypothetic' uncontrollable incident with catastrophic effects is the main subject of the discussion on the peaceful utilization of nuclear power. The this year's 'Annual Meeting on Nuclear Engineering' in Mannheim and the meeting 'Reactor Safety Research' in Cologne showed, that risk studies so far were too pessimistic. 'Best estimate' calculations suggest that core melt-down accidents only occur if almost all safety systems fail, that accidents take place much more slowly, and that the release of radioactive fission products is by several magnitudes lower than it was assumed until now. (orig.) [de

Risks of circulatory diseases among Mayak PA workers with radiation doses estimated using the improved Mayak Worker Dosimetry System 2008

Energy Technology Data Exchange (ETDEWEB)

Moseeva, Maria B.; Azizova, Tamara V.; Grigoryeva, Evgenia S. [Southern Urals Biophysics Institute (SUBI), Ozyorsk, Chelyabinsk Region (Russian Federation); Haylock, Richard [Public Health of England, London (United Kingdom)

2014-05-15

The new Mayak Worker Dosimetry System 2008 (MWDS-2008) was published in 2013 and supersedes the Doses-2005 dosimetry system for Mayak Production Association (PA) workers. It provides revised external and internal dose estimates based on the updated occupational history data. Using MWDS-2008, a cohort of 18,856 workers first employed at one of the main Mayak PA plants during 1948-1972 and followed up to 2005 was identified. Incidence and mortality risks from ischemic heart disease (IHD) (International Classification of Diseases (ICD)-9 codes 410-414) and from cerebrovascular diseases (CVD) (ICD-9 codes 430-438) were examined in this cohort and compared with previously published risk estimates in the same cohort based on the Doses-2005 dosimetry system. Significant associations were observed between doses from external gamma-rays and IHD and CVD incidence and also between internal doses from alpha-radiation and IHD mortality and CVD incidence. The estimates of excess relative risk (ERR)/Gy were consistent with those estimates from the previous studies based on Doses-2005 system apart from the relationship between CVD incidence and internal liver dose where the ERR/Gy based on MWDS-2008 was just over three times higher than the corresponding estimate based on Doses-2005 system. Adjustment for smoking status did not show any effect on the estimates of risk from internal alpha-particle exposure. (orig.)

A population-based national estimate of the prevalence and risk factors associated with hypertension in Rwanda: implications for prevention and control.

Science.gov (United States)

Nahimana, Marie-Rosette; Nyandwi, Alypio; Muhimpundu, Marie Aimee; Olu, Olushayo; Condo, Jeanine Umutesi; Rusanganwa, Andre; Koama, Jean Baptiste; Ngoc, Candide Tran; Gasherebuka, Jean Bosco; Ota, Martin O; Okeibunor, Joseph C

2017-07-10

Hypertension is a leading cause of cardiovascular diseases and a growing public health problem in many developed and developing countries. However, population-based data to inform policy development are scarce in Rwanda. This nationally representative study aimed to determine population-based estimates of the prevalence and risk factors associated with hypertension in Rwanda. We conducted secondary epidemiological analysis of data collected from a cross-sectional population-based study to assess the risk factors for NCDs using the WHO STEPwise approach to Surveillance of non-communicable diseases (STEPS). Adjusted odds ratios at 95% confidence interval were used to establish association between hypertension, socio-demographic characteristics and health risk behaviors. Of the 7116 study participants, 62.8% were females and 38.2% were males. The mean age of study participants was 35.3 years (SD 12.5). The overall prevalence of hypertension was 15.3% (16.4% for males and 14.4% for females). Twenty two percent of hypertensive participants were previously diagnosed. A logistic regression model revealed that age (AOR: 8.02, 95% CI: 5.63-11.42, p Rwanda, suggesting the need for prevention and control interventions aimed at decreasing the incidence taking into consideration the risk factors documented in this and other similar studies.

Crossover effect of spouse weekly working hours on estimated 10-years risk of cardiovascular disease.

Directory of Open Access Journals (Sweden)

Mo-Yeol Kang

Full Text Available To investigate the association between spouse weekly working hours (SWWH and the estimated 10-years risk of cardiovascular disease (CVD.This cross-sectional study was based on the data obtained from the Korean National Health and Nutrition Examination Survey 2007-2012. Data of 16,917 participants (8,330 husbands, 8,587 wives were used for this analysis. The participants' clinical data were collected to estimate the 10-years risk of CVD, as well as weekly working hours. Multiple logistic regression was conducted to investigate the association between SWWH and the estimated 10-years risk of CVD. We also performed a stratified analysis according to each participant's and their spouse's employment status.Compared to those whose spouses worked 30 hours per week, estimated 10-years risk of CVD was significantly higher as SWWH increase among those whose spouses worked >30 hours per week. After adjusting for covariates, the odds ratio for high CVD risk was found to increase as SWWH increased, up to 2.52 among husbands and 2.43 among wives. We also found that the association between SWWH and the estimated 10-years risk of CVD varied according to the employment status. Analysis of each component included in the CVD appraisal model showed that SWWH had close relationship with diabetes in men, and smoking habits in women.Spouse's long working hours are associated with individual's risk of CVD in future, especially among husbands.

Aid decision algorithms to estimate the risk in congenital heart surgery.

Science.gov (United States)

Ruiz-Fernández, Daniel; Monsalve Torra, Ana; Soriano-Payá, Antonio; Marín-Alonso, Oscar; Triana Palencia, Eddy

2016-04-01

In this paper, we have tested the suitability of using different artificial intelligence-based algorithms for decision support when classifying the risk of congenital heart surgery. In this sense, classification of those surgical risks provides enormous benefits as the a priori estimation of surgical outcomes depending on either the type of disease or the type of repair, and other elements that influence the final result. This preventive estimation may help to avoid future complications, or even death. We have evaluated four machine learning algorithms to achieve our objective: multilayer perceptron, self-organizing map, radial basis function networks and decision trees. The architectures implemented have the aim of classifying among three types of surgical risk: low complexity, medium complexity and high complexity. Accuracy outcomes achieved range between 80% and 99%, being the multilayer perceptron method the one that offered a higher hit ratio. According to the results, it is feasible to develop a clinical decision support system using the evaluated algorithms. Such system would help cardiology specialists, paediatricians and surgeons to forecast the level of risk related to a congenital heart disease surgery. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

A non-stationary cost-benefit analysis approach for extreme flood estimation to explore the nexus of 'Risk, Cost and Non-stationarity'

Science.gov (United States)

Qi, Wei

2017-11-01

Cost-benefit analysis is commonly used for engineering planning and design problems in practice. However, previous cost-benefit based design flood estimation is based on stationary assumption. This study develops a non-stationary cost-benefit based design flood estimation approach. This approach integrates a non-stationary probability distribution function into cost-benefit analysis, and influence of non-stationarity on expected total cost (including flood damage and construction costs) and design flood estimation can be quantified. To facilitate design flood selections, a 'Risk-Cost' analysis approach is developed, which reveals the nexus of extreme flood risk, expected total cost and design life periods. Two basins, with 54-year and 104-year flood data respectively, are utilized to illustrate the application. It is found that the developed approach can effectively reveal changes of expected total cost and extreme floods in different design life periods. In addition, trade-offs are found between extreme flood risk and expected total cost, which reflect increases in cost to mitigate risk. Comparing with stationary approaches which generate only one expected total cost curve and therefore only one design flood estimation, the proposed new approach generate design flood estimation intervals and the 'Risk-Cost' approach selects a design flood value from the intervals based on the trade-offs between extreme flood risk and expected total cost. This study provides a new approach towards a better understanding of the influence of non-stationarity on expected total cost and design floods, and could be beneficial to cost-benefit based non-stationary design flood estimation across the world.

Estimating the risks of cancer mortality and genetic defects resulting from exposures to low levels of ionizing radiation

International Nuclear Information System (INIS)

Buhl, T.E.; Hansen, W.R.

1984-05-01

Estimators for calculating the risk of cancer and genetic disorders induced by exposure to ionizing radiation have been recommended by the US National Academy of Sciences Committee on the Biological Effects of Ionizing Radiations, the UN Scientific Committee on the Effects of Atomic Radiation, and the International Committee on Radiological Protection. These groups have also considered the risks of somatic effects other than cancer. The US National Council on Radiation Protection and Measurements has discussed risk estimate procedures for radiation-induced health effects. The recommendations of these national and international advisory committees are summarized and compared in this report. Based on this review, two procedures for risk estimation are presented for use in radiological assessments performed by the US Department of Energy under the National Environmental Policy Act of 1969 (NEPA). In the first procedure, age- and sex-averaged risk estimators calculated with US average demographic statistics would be used with estimates of radiation dose to calculate the projected risk of cancer and genetic disorders that would result from the operation being reviewed under NEPA. If more site-specific risk estimators are needed, and the demographic information is available, a second procedure is described that would involve direct calculation of the risk estimators using recommended risk-rate factors. The computer program REPCAL has been written to perform this calculation and is described in this report. 25 references, 16 tables

Estimating the risks of cancer mortality and genetic defects resulting from exposures to low levels of ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Buhl, T.E.; Hansen, W.R.

1984-05-01

Estimators for calculating the risk of cancer and genetic disorders induced by exposure to ionizing radiation have been recommended by the US National Academy of Sciences Committee on the Biological Effects of Ionizing Radiations, the UN Scientific Committee on the Effects of Atomic Radiation, and the International Committee on Radiological Protection. These groups have also considered the risks of somatic effects other than cancer. The US National Council on Radiation Protection and Measurements has discussed risk estimate procedures for radiation-induced health effects. The recommendations of these national and international advisory committees are summarized and compared in this report. Based on this review, two procedures for risk estimation are presented for use in radiological assessments performed by the US Department of Energy under the National Environmental Policy Act of 1969 (NEPA). In the first procedure, age- and sex-averaged risk estimators calculated with US average demographic statistics would be used with estimates of radiation dose to calculate the projected risk of cancer and genetic disorders that would result from the operation being reviewed under NEPA. If more site-specific risk estimators are needed, and the demographic information is available, a second procedure is described that would involve direct calculation of the risk estimators using recommended risk-rate factors. The computer program REPCAL has been written to perform this calculation and is described in this report. 25 references, 16 tables.

Neoplastic potential of gastric irradiation. IV. Risk estimates

International Nuclear Information System (INIS)

Griem, M.L.; Justman, J.; Weiss, L.

1984-01-01

No significant tumor increase was found in the initial analysis of patients irradiated for peptic ulcer and followed through 1962. A preliminary study was undertaken 22 years later to estimate the risk of cancer due to gastric irradiation for peptic ulcer disease. A population of 2,049 irradiated patients and 763 medically managed patients has been identified. A relative risk of 3.7 was found for stomach cancer and an initial risk estimate of 5.5 x 10(-6) excess stomach cancers per person rad was calculated. A more complete follow-up is in progress to further elucidate this observation and decrease the ascertainment bias; however, preliminary data are in agreement with the Japanese atomic bomb reports

A risk adjustment approach to estimating the burden of skin disease in the United States.

Science.gov (United States)

Lim, Henry W; Collins, Scott A B; Resneck, Jack S; Bolognia, Jean; Hodge, Julie A; Rohrer, Thomas A; Van Beek, Marta J; Margolis, David J; Sober, Arthur J; Weinstock, Martin A; Nerenz, David R; Begolka, Wendy Smith; Moyano, Jose V

2018-01-01

Direct insurance claims tabulation and risk adjustment statistical methods can be used to estimate health care costs associated with various diseases. In this third manuscript derived from the new national Burden of Skin Disease Report from the American Academy of Dermatology, a risk adjustment method that was based on modeling the average annual costs of individuals with or without specific diseases, and specifically tailored for 24 skin disease categories, was used to estimate the economic burden of skin disease. The results were compared with the claims tabulation method used in the first 2 parts of this project. The risk adjustment method estimated the direct health care costs of skin diseases to be $46 billion in 2013, approximately $15 billion less than estimates using claims tabulation. For individual skin diseases, the risk adjustment cost estimates ranged from 11% to 297% of those obtained using claims tabulation for the 10 most costly skin disease categories. Although either method may be used for purposes of estimating the costs of skin disease, the choice of method will affect the end result. These findings serve as an important reference for future discussions about the method chosen in health care payment models to estimate both the cost of skin disease and the potential cost impact of care changes. Copyright © 2017 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.

Measurement of total risk of spontaneous abortion: the virtue of conditional risk estimation

DEFF Research Database (Denmark)

Modvig, J; Schmidt, L; Damsgaard, M T

1990-01-01

The concepts, methods, and problems of measuring spontaneous abortion risk are reviewed. The problems touched on include the process of pregnancy verification, the changes in risk by gestational age and maternal age, and the presence of induced abortions. Methods used in studies of spontaneous...... abortion risk include biochemical assays as well as life table technique, although the latter appears in two different forms. The consequences of using either of these are discussed. It is concluded that no study design so far is appropriate for measuring the total risk of spontaneous abortion from early...... conception to the end of the 27th week. It is proposed that pregnancy may be considered to consist of two or three specific periods and that different study designs should concentrate on measuring the conditional risk within each period. A careful estimate using this principle leads to an estimate of total...

A new technique for fire risk estimation in the wildland urban interface

Science.gov (United States)

Dasgupta, S.; Qu, J. J.; Hao, X.

A novel technique based on the physical variable of pre-ignition energy is proposed for assessing fire risk in the Grassland-Urban-Interface The physical basis lends meaning a site and season independent applicability possibilities for computing spread rates and ignition probabilities features contemporary fire risk indices usually lack The method requires estimates of grass moisture content and temperature A constrained radiative-transfer inversion scheme on MODIS NIR-SWIR reflectances which reduces solution ambiguity is used for grass moisture retrieval while MODIS land surface temperature emissivity products are used for retrieving grass temperature Subpixel urban contamination of the MODIS reflective and thermal signals over a Grassland-Urban-Interface pixel is corrected using periodic estimates of urban influence from high spatial resolution ASTER

Cost Risk Analysis Based on Perception of the Engineering Process

Science.gov (United States)

Dean, Edwin B.; Wood, Darrell A.; Moore, Arlene A.; Bogart, Edward H.

1986-01-01

In most cost estimating applications at the NASA Langley Research Center (LaRC), it is desirable to present predicted cost as a range of possible costs rather than a single predicted cost. A cost risk analysis generates a range of cost for a project and assigns a probability level to each cost value in the range. Constructing a cost risk curve requires a good estimate of the expected cost of a project. It must also include a good estimate of expected variance of the cost. Many cost risk analyses are based upon an expert's knowledge of the cost of similar projects in the past. In a common scenario, a manager or engineer, asked to estimate the cost of a project in his area of expertise, will gather historical cost data from a similar completed project. The cost of the completed project is adjusted using the perceived technical and economic differences between the two projects. This allows errors from at least three sources. The historical cost data may be in error by some unknown amount. The managers' evaluation of the new project and its similarity to the old project may be in error. The factors used to adjust the cost of the old project may not correctly reflect the differences. Some risk analyses are based on untested hypotheses about the form of the statistical distribution that underlies the distribution of possible cost. The usual problem is not just to come up with an estimate of the cost of a project, but to predict the range of values into which the cost may fall and with what level of confidence the prediction is made. Risk analysis techniques that assume the shape of the underlying cost distribution and derive the risk curve from a single estimate plus and minus some amount usually fail to take into account the actual magnitude of the uncertainty in cost due to technical factors in the project itself. This paper addresses a cost risk method that is based on parametric estimates of the technical factors involved in the project being costed. The engineering

Estimating the risk of dengue transmission from Dutch blood donors travelling to Suriname and the Dutch Caribbean.

Science.gov (United States)

Oei, W; Lieshout-Krikke, R W; Kretzschmar, M E; Zaaijer, H L; Coutinho, R A; Eersel, M; Jubithana, B; Halabi, Y; Gerstenbluth, I; Maduro, E; Tromp, M; Janssen, M P

2016-05-01

The risk of dengue transmitted by travellers is known. Methods to estimate the transmission by transfusion (TT) risk from blood donors travelling to risk areas are available, for instance, the European Up-Front Risk Assessment Tool (EUFRAT). This study aimed to validate the estimated risk from travelling donors obtained from EUFRAT. Surveillance data on notified dengue cases in Suriname and the Dutch Caribbean islands (Aruba, Curaçao, St. Maarten, Bonaire, St. Eustatius and Saba) in 2001-2011 was used to calculate local incidence rates. Information on travel and donation behaviour of Dutch donors was collected. With the EUFRAT model, the TT risks from Dutch travelling donors were calculated. Model estimates were compared with the number of infections in Dutch travellers found by laboratory tests in the Netherlands. The expected cumulative number of donors becoming infected during travels to Suriname and the Dutch Caribbean from 2001 to 2011 was estimated at 5 (95% CI, 2-11) and 86 (45-179), respectively. The infection risk inferred from the laboratory-based study was 19 (9-61) and 28 (14-92). Given the independence of the data sources, these estimates are remarkably close. The model estimated that 0·02 (0·001-0·06) and 0·40 (0·01-1·4) recipients would have been infected by these travelling donors. The EUFRAT model provided an estimate close to actual observed number of dengue infections. The dengue TT risk among Dutch travelling donors can be estimated using basic transmission, travel and donation information. The TT risk from Dutch donors travelling to Suriname and the Dutch Caribbean is small. © 2016 International Society of Blood Transfusion.

Telemetry-based mortality estimates of juvenile spot in two North Carolina estuarine creeks

Science.gov (United States)

Friedl, Sarah E.; Buckel, Jeffery A.; Hightower, Joseph E.; Scharf, Frederick S.; Pollock, Kenneth H.

2013-01-01

We estimated natural mortality rates (M) of age-1 Spot Leiostomus xanthurus by using a sonic telemetry approach. Sonic transmitters were surgically implanted into a total of 123 age-1 Spot in two North Carolina estuarine creeks during spring 2009 and 2010, and the fish were monitored by using a stationary acoustic receiver array and manual tracking. Fates of telemetered Spot were inferred based on telemetry information from estimated locations and swimming speeds. Potential competitors of age-1 Spot were assessed through simultaneous otter trawl sampling, while potential predators of Spot were collected using gill nets and trammel nets. The number of inferred natural mortalities was zero in 2009 (based on 29 telemetered Spot at risk) and four in 2010 (based on 52 fish at risk), with fish being at risk for up to about 70 d each year. Catches of potential competitors or predators did not differ between years, and age-1 Spot were not found in analyzed stomach contents of potential predators. Our estimated 30-d M of 0.03 (95% credible interval = 0.01–0.07) was lower than that predicted from weight-based (M = 0.07) and life-history-based (M = 0.06–0.36) estimates. Our field-based estimate of M for age-1 Spot in this estuarine system can assist in the assessment and management of Spot by allowing a direct comparison with M-values predicted from fish size or life history characteristics. The field telemetry and statistical analysis techniques developed here provide guidance for future telemetry studies of relatively small fish in open, dynamic habitat systems, as they highlight strengths and weaknesses of using a telemetry approach to estimate M.

Comparison of cystatin C- and creatinine-based estimated glomerular filtration rate to predict coronary heart disease risk in Japanese patients with obesity and diabetes.

Science.gov (United States)

Ito, Ryo; Yamakage, Hajime; Kotani, Kazuhiko; Wada, Hiromichi; Otani, Sumire; Yonezawa, Kazuya; Ogo, Atsushi; Okajima, Taiichiro; Adachi, Masahiro; Araki, Rika; Yoshida, Kazuro; Saito, Miho; Nagaoka, Tadasu; Toyonaga, Tetsushi; Tanaka, Tsuyoshi; Yamada, Tsutomu; Ota, Itsuro; Oishi, Mariko; Miyanaga, Fumiko; Shimatsu, Akira; Satoh-Asahara, Noriko

2015-01-01

The aim of this study is to determine which indicator of chronic kidney disease most closely correlates with 10-year Framingham coronary heart disease (CHD) risk among serum creatinine, serum cystatin C (S-CysC), urine albumin-creatinine ratio (UACR), estimated creatinine-based GFRs (eGFRcre), and estimated CysC-based GFRs (eGFRcys) in patients with obesity and diabetes. Serum creatinine, S-CysC, UACR, and cardio-ankle vascular index (CAVI) were examined in 468 outpatients with obesity and type 2 diabetes, free of severe renal dysfunction or previous history of cardiovascular disease, as a cross-sectional survey using baseline data from the multi-centered Japan Diabetes and Obesity Study. S-CysC and eGFRcys had significantly stronger correlations with the 10-year Framingham CHD risk than serum creatinine, eGFRcre, and UACR (creatinine, ρ = 0.318; S-CysC, ρ = 0.497; UACR, ρ = 0.174; eGFRcre, ρ = -0.291; eGFRcys, ρ = -0.521; P obesity and diabetes.

Comparison of additive (absolute) risk projection models and multiplicative (relative) risk projection models in estimating radiation-induced lifetime cancer risk

International Nuclear Information System (INIS)

Kai, Michiaki; Kusama, Tomoko

1990-01-01

Lifetime cancer risk estimates depend on risk projection models. While the increasing lengths of follow-up observation periods of atomic bomb survivors in Hiroshima and Nagasaki bring about changes in cancer risk estimates, the validity of the two risk projection models, the additive risk projection model (AR) and multiplicative risk projection model (MR), comes into question. This paper compares the lifetime risk or loss of life-expectancy between the two projection models on the basis of BEIR-III report or recently published RERF report. With Japanese cancer statistics the estimates of MR were greater than those of AR, but a reversal of these results was seen when the cancer hazard function for India was used. When we investigated the validity of the two projection models using epidemiological human data and animal data, the results suggested that MR was superior to AR with respect to temporal change, but there was little evidence to support its validity. (author)

Estimating the re-identification risk of clinical data sets

Directory of Open Access Journals (Sweden)

Dankar Fida

2012-07-01

Full Text Available Abstract Background De-identification is a common way to protect patient privacy when disclosing clinical data for secondary purposes, such as research. One type of attack that de-identification protects against is linking the disclosed patient data with public and semi-public registries. Uniqueness is a commonly used measure of re-identification risk under this attack. If uniqueness can be measured accurately then the risk from this kind of attack can be managed. In practice, it is often not possible to measure uniqueness directly, therefore it must be estimated. Methods We evaluated the accuracy of uniqueness estimators on clinically relevant data sets. Four candidate estimators were identified because they were evaluated in the past and found to have good accuracy or because they were new and not evaluated comparatively before: the Zayatz estimator, slide negative binomial estimator, Pitman’s estimator, and mu-argus. A Monte Carlo simulation was performed to evaluate the uniqueness estimators on six clinically relevant data sets. We varied the sampling fraction and the uniqueness in the population (the value being estimated. The median relative error and inter-quartile range of the uniqueness estimates was measured across 1000 runs. Results There was no single estimator that performed well across all of the conditions. We developed a decision rule which selected between the Pitman, slide negative binomial and Zayatz estimators depending on the sampling fraction and the difference between estimates. This decision rule had the best consistent median relative error across multiple conditions and data sets. Conclusion This study identified an accurate decision rule that can be used by health privacy researchers and disclosure control professionals to estimate uniqueness in clinical data sets. The decision rule provides a reliable way to measure re-identification risk.

Occupational and consumer risk estimates for nanoparticles emitted by laser printers

International Nuclear Information System (INIS)

Haenninen, Otto; Brueske-Hohlfeld, Irene; Loh, Miranda; Stoeger, Tobias; Kreyling, Wolfgang; Schmid, Otmar; Peters, Annette

2010-01-01

Several studies have reported laser printers as significant sources of nanosized particles ( -1 ; particle number 1.1-3.1 x 10 9 d -1 ) were estimated to correspond to 4-13 (mass) or 12-34 (number) deaths per million persons exposed on the basis of epidemiological risk estimates for ambient particles. These risks are higher than the generally used definition of acceptable risk of 1 x 10 -6 , but substantially lower than the estimated risks due to ambient particles. Toxicological studies on ambient particles revealed consistent values for lowest observed effect levels (LOELs) which were converted into equivalent daily uptakes using allometric scaling. These LOEL uptakes were by a factor of about 330-1,000 (mass) and 1,000-2,500 (particle surface area) higher than estimated uptakes from printers. This toxicological assessment would indicate no significant health risks due to printer particles. Finally, our study suggests that particle number (not mass) and mass (not surface area) are the most conservative risk metrics for the epidemiological and toxicological risks presented here, respectively.

Relative Risks for Lethal Prostate Cancer Based on Complete Family History of Prostate Cancer Death.

Science.gov (United States)

Albright, Frederick S; Stephenson, Robert A; Agarwal, Neeraj; Cannon-Albright, Lisa A

2017-01-01

There are few published familial relative risks (RR) for lethal prostate cancer. This study estimates RRs for lethal prostate cancer based on comprehensive family history data, with the goal of improving identification of those men at highest risk of dying from prostate cancer. We used a population-based genealogical resource linked to a statewide electronic SEER cancer registry and death certificates to estimate relative risks (RR) for death from prostate cancer based upon family history. Over 600,000 male probands were analyzed, representing a variety of family history constellations of lethal prostate cancer. RR estimates were based on the ratio of the observed to the expected number of lethal prostate cancer cases using internal rates. RRs for lethal prostate cancer based on the number of affected first-degree relatives (FDR) ranged from 2.49 (95% CI: 2.27, 2.73) for exactly 1 FDR to 5.30 (2.13, 10.93) for ≥3 affected FDRs. In an absence of affected FDRs, increased risk was also significant for increasing numbers of affected second-degree or third degree relatives. Equivalent risks were observed for similar maternal and paternal family history. This study provides population-based estimates of lethal prostate cancer risk based on lethal prostate cancer family history. Many family history constellations associated with two to greater than five times increased risk for lethal prostate cancer were identified. These lethal prostate cancer risk estimates hold potential for use in identification, screening, early diagnosis, and treatment of men at high risk for death from prostate cancer. Prostate77:41-48, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Comparison of cluster-based and source-attribution methods for estimating transmission risk using large HIV sequence databases.

Science.gov (United States)

Le Vu, Stéphane; Ratmann, Oliver; Delpech, Valerie; Brown, Alison E; Gill, O Noel; Tostevin, Anna; Fraser, Christophe; Volz, Erik M

2018-06-01

Phylogenetic clustering of HIV sequences from a random sample of patients can reveal epidemiological transmission patterns, but interpretation is hampered by limited theoretical support and statistical properties of clustering analysis remain poorly understood. Alternatively, source attribution methods allow fitting of HIV transmission models and thereby quantify aspects of disease transmission. A simulation study was conducted to assess error rates of clustering methods for detecting transmission risk factors. We modeled HIV epidemics among men having sex with men and generated phylogenies comparable to those that can be obtained from HIV surveillance data in the UK. Clustering and source attribution approaches were applied to evaluate their ability to identify patient attributes as transmission risk factors. We find that commonly used methods show a misleading association between cluster size or odds of clustering and covariates that are correlated with time since infection, regardless of their influence on transmission. Clustering methods usually have higher error rates and lower sensitivity than source attribution method for identifying transmission risk factors. But neither methods provide robust estimates of transmission risk ratios. Source attribution method can alleviate drawbacks from phylogenetic clustering but formal population genetic modeling may be required to estimate quantitative transmission risk factors. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Uncertainty in exposure of underground miners to radon daughters and the effect of uncertainty on risk estimates

International Nuclear Information System (INIS)

1989-10-01

Studies of underground miners provide the principal basis for assessing the risk from radon daughter exposure. An important problem in all epidemiological studies of underground miners is the reliability of the estimates of the miners' exposures. This study examines the various sources of uncertainty in exposure estimation for the principal epidemiologic studies reported in the literature including the temporal and spatial variability of radon sources and, with the passage of time, changes to both mining methods and ventilation conditions. Uncertainties about work histories and the role of other hard rock mining experience are also discussed. The report also describes two statistical approaches, both based on Bayesian methods, by which the effects on the estimated risk coefficient of uncertainty in exposure (WLM) can be examined. One approach requires only an estimate of the cumulative WLM exposure of a group of miners, an estimate of the number of (excess) lung cancers potentially attributable to that exposure, and a specification of the uncertainty about the cumulative exposure of the group. The second approach is based on a linear regression model which incorporates errors (uncertainty) in the independent variable (WLM) and allows the dependent variable (cases) to be Poisson distributed. The method permits the calculation of marginal probability distributions for either slope (risk coefficient) or intercept. The regression model approach is applied to several published data sets from epidemiological studies of miners. Specific results are provided for each data set and apparent differences in risk coefficients are discussed. The studies of U.S. uranium miners, Ontario uranium miners and Czechoslovakian uranium miners are argued to provide the best basis for risk estimation at this time. In general terms, none of the analyses performed are inconsistent with a linear exposure-effect relation. Based on analyses of the overall miner groups, the most likely ranges

Evidence-based estimate of appropriate radiotherapy utilization rate for prostate cancer

International Nuclear Information System (INIS)

Foroudi, Farshad; Tyldesley, Scott; Barbera, Lisa; Huang, Jenny; Mackillop, William J.

2003-01-01

Purpose: Current estimates of the proportion of cancer patients who will require radiotherapy (RT) are based almost entirely on expert opinion. The objective of this study was to use an evidence-based approach to estimate the proportion of incident cases of prostate cancer that should receive RT at any point in the evolution of the illness. Methods and Materials: A systematic review of the literature was undertaken to identify indications for RT for prostate cancer and to ascertain the level of evidence that supported each indication. An epidemiologic approach was then used to estimate the incidence of each indication for RT in a typical North American population of prostate cancer patients. The effect of sampling error on the estimated appropriate rate of RT was calculated mathematically, and the effect of systematic error using alternative sources of information was estimated by sensitivity analysis. Results: It was estimated that 61.2% ±5.6% of prostate cancer cases develop one or more indications for RT at some point in the course of the illness. The plausible range for this rate was 57.3%-69.8% on sensitivity analysis. Of all prostate cancer patients, 32.2%±3.8% should receive RT in their initial treatment and 29.0% ± 4.1% later for recurrence or progression. The proportion of cases that ever require RT is risk grouping dependent; 43.9%±2.2% in low-risk disease, 68.7%± .5% in intermediate-risk disease; and 79.0% ± 3.8% in high-risk locoregional disease. For metastatic disease, the predicted rate was 66.4%±0.3%. Conclusion: This method provides a rational starting point for the long-term planning of radiation services and for the audit of access to RT at the population level. By completing such evaluations in major cancer sites, it will be possible to estimate the appropriate RT rate for the cancer population as a whole

MARKET RISK ESTIMATION IN (T+-TRANSACTIONS

Directory of Open Access Journals (Sweden)

Radik B. Begov

2016-01-01

Full Text Available Market risk analysis and estimation are presentedin T+ transactionsas they are used within the Moscow Exchange. There is a need to do so as a result of the cut-off of a new REPO product with Central Counterpartner (CCP. Here repurchase agreement goes through the National Clearing Center (NCC, the last being a bank and a clearing structure within the Moscow Exchange group.NCC actsas an intermediary (so called “Central Counterpartner” between trading participants.REPOs with CCP raisecontractor claims and commitments to the CCP which takes the risk of default on commitments from unfair contract side. The REPO with CCP cut-off made ready a technological platform to implement T+2 trades at the Moscow Exchange. As a result of it there appeared the possibility to enter security purchase/sell contracts partially collateralized. All these transactions (the REPO with CCP, T+ made it a must determining security market risks. The paper is aimed at presenting VaR-like risk estimates. The methods used are from the computer fi nance. Unusual TS rate of return indicator is proposed and applied to find optimal portfolios under the Markowitz approach and their VaRs (losses forecasts given the real “big” share price data and various horizons. Portfolio extreme rate and loss forecasting is our goal. To this end the forecasts are computed for three horizons (2, 5 and 10 days and for three significance levels.There were developed R-, Excel- and Bloomberg-basedsoftware tools as needed. The whole range of proposed computing steps and the tables with charts may be considered as candidates to be included in the future market risk standards.Paper results permit capital market participants to choose the correct (as to the required risk level common stocks.

Estimation of lung cancer risk from environmental exposure to airborne plutonium from the Rocky Flats Plant

International Nuclear Information System (INIS)

Sutherland, J.V.

1983-01-01

A three-phase study was undertaken to (1) determine the nature of disagreement among scientists concerning risk of environmental release of plutonium, (2) develop an analytic procedure for determining risk based on clearly stated principles defensible by reference to the literature, and (3) develop estimates of radiation dose to the lung from exposure to plutonium in ambient air for the purpose of evaluating risk to an individual with a specified age and smoking history. Eleven epidemiologists, biostatisticians and radiation scientists participated in Phase I of the study. It was shown that no clearly stated analytical principles for risk estimation were in common use, resulting in widely divergent risk estimates. Five of these disagreeing scientists in Phase I (including all cancer epidemiologists in the Denver metropolitan area) were chosen for Phase II of the study. A single analytic procedure was developed which was unanimously agreed upon. This procedure was dependent on the estimate of dose to the lung from ambient air levels of Rocky Flats plutonium. In Phase III of the study, a panel of four radiation scientists developed a procedure for estimation of dose to the lung from chronic exposure to plutonium ambient air levels. Results from all phases of the study were used to develop a method for estimation of relative risk of lung cancer for an individual, given plutonium dose to the lung, age, smoking history and other radiation exposure

Estimating adolescent risk for hearing loss based on data from a large school-based survey.

Science.gov (United States)

Vogel, Ineke; Verschuure, Hans; van der Ploeg, Catharina P B; Brug, Johannes; Raat, Hein

2010-06-01

We estimated whether and to what extent a group of adolescents were at risk of developing permanent hearing loss as a result of voluntary exposure to high-volume music, and we assessed whether such exposure was associated with hearing-related symptoms. In 2007, 1512 adolescents (aged 12-19 years) in Dutch secondary schools completed questionnaires about their music-listening behavior and whether they experienced hearing-related symptoms after listening to high-volume music. We used their self-reported data in conjunction with published average sound levels of music players, discotheques, and pop concerts to estimate their noise exposure, and we compared that exposure to our own "loosened" (i.e., less strict) version of current European safety standards for occupational noise exposure. About half of the adolescents exceeded safety standards for occupational noise exposure. About one third of the respondents exceeded safety standards solely as a result of listening to MP3 players. Hearing symptoms that occurred after using an MP3 player or going to a discotheque were associated with exposure to high-volume music. Adolescents often exceeded current occupational safety standards for noise exposure, highlighting the need for specific safety standards for leisure-time noise exposure.

Annual effective dose due to residential radon progeny in Sweden: Evaluations based on current risk projections models and on risk estimates from a nation-wide Swedish epidemiological study

Energy Technology Data Exchange (ETDEWEB)

Doi, M [National Inst. of Radiological Sciences, Chiba (Japan); Lagarde, F [Karolinska Inst., Stockholm (Sweden). Inst. of Environmental Medicine; Falk, R; Swedjemark, G A [Swedish Radiation Protection Inst., Stockholm (Sweden)

1996-12-01

Effective dose per unit radon progeny exposure to Swedish population in 1992 is estimated by the risk projection model based on the Swedish epidemiological study of radon and lung cancer. The resulting values range from 1.29 - 3.00 mSv/WLM and 2.58 - 5.99 mSv/WLM, respectively. Assuming a radon concentration of 100 Bq/m{sup 3}, an equilibrium factor of 0.4 and an occupancy factor of 0.6 in Swedish houses, the annual effective dose for the Swedish population is estimated to be 0.43 - 1.98 mSv/year, which should be compared to the value of 1.9 mSv/year, according to the UNSCEAR 1993 report. 27 refs, tabs, figs.

Annual effective dose due to residential radon progeny in Sweden: Evaluations based on current risk projections models and on risk estimates from a nation-wide Swedish epidemiological study

International Nuclear Information System (INIS)

Doi, M.; Lagarde, F.

1996-12-01

Effective dose per unit radon progeny exposure to Swedish population in 1992 is estimated by the risk projection model based on the Swedish epidemiological study of radon and lung cancer. The resulting values range from 1.29 - 3.00 mSv/WLM and 2.58 - 5.99 mSv/WLM, respectively. Assuming a radon concentration of 100 Bq/m 3 , an equilibrium factor of 0.4 and an occupancy factor of 0.6 in Swedish houses, the annual effective dose for the Swedish population is estimated to be 0.43 - 1.98 mSv/year, which should be compared to the value of 1.9 mSv/year, according to the UNSCEAR 1993 report. 27 refs, tabs, figs

Patient- and cohort-specific dose and risk estimation for abdominopelvic CT: a study based on 100 patients

Science.gov (United States)

Tian, Xiaoyu; Li, Xiang; Segars, W. Paul; Frush, Donald P.; Samei, Ehsan

2012-03-01

The purpose of this work was twofold: (a) to estimate patient- and cohort-specific radiation dose and cancer risk index for abdominopelvic computer tomography (CT) scans; (b) to evaluate the effects of patient anatomical characteristics (size, age, and gender) and CT scanner model on dose and risk conversion coefficients. The study included 100 patient models (42 pediatric models, 58 adult models) and multi-detector array CT scanners from two commercial manufacturers (LightSpeed VCT, GE Healthcare; SOMATOM Definition Flash, Siemens Healthcare). A previously-validated Monte Carlo program was used to simulate organ dose for each patient model and each scanner, from which DLP-normalized-effective dose (k factor) and DLP-normalized-risk index values (q factor) were derived. The k factor showed exponential decrease with increasing patient size. For a given gender, q factor showed exponential decrease with both increasing patient size and patient age. The discrepancies in k and q factors across scanners were on average 8% and 15%, respectively. This study demonstrates the feasibility of estimating patient-specific organ dose and cohort-specific effective dose and risk index in abdominopelvic CT requiring only the knowledge of patient size, gender, and age.

Association between subjective risk perception and objective risk estimation in patients with atrial fibrillation: a cross-sectional study.

Science.gov (United States)

Zweiker, David; Zweiker, Robert; Winkler, Elisabeth; Roesch, Konstantina; Schumacher, Martin; Stepan, Vinzenz; Krippl, Peter; Bauer, Norbert; Heine, Martin; Reicht, Gerhard; Zweiker, Gudrun; Sprenger, Martin; Watzinger, Norbert

2017-09-25

Oral anticoagulation (OAC) is state-of-the-art therapy for atrial fibrillation (AF), the most common arrhythmia worldwide. However, little is known about the perception of patients with AF and how it correlates with risk scores used by their physicians. Therefore, we correlated patients' estimates of their own stroke and bleeding risk with the objectively predicted individual risk using CHA 2 DS 2 -VASc and HAS-BLED scores. Cross-sectional prevalence study using convenience sampling and telephone follow-up. Eight hospital departments and one general practitioner in Austria. Patients' perception of stroke and bleeding risk was opposed to commonly used risk scoring. Patients with newly diagnosed AF and indication for anticoagulation. Comparison of subjective risk perception with CHA 2 DS 2 -VASc and HAS-BLED scores showing possible discrepancies between subjective and objective risk estimation. Patients' judgement of their own knowledge on AF and education were also correlated with accuracy of subjective risk appraisal. Ninety-one patients (age 73±11 years, 45% female) were included in this study. Subjective stroke and bleeding risk estimation did not correlate with risk scores (ρ=0.08 and ρ=0.17). The majority of patients (57%) underestimated the individual stroke risk. Patients feared stroke more than bleeding (67% vs 10%). There was no relationship between accurate perception of stroke and bleeding risks and education level. However, we found a correlation between the patients' judgement of their own knowledge of AF and correct assessment of individual stroke risk (ρ=0.24, p=0.02). During follow-up, patients experienced the following events: death (n=5), stroke (n=2), bleeding (n=1). OAC discontinuation rate despite indication was 3%. In this cross-sectional analysis of OAC-naive patients with AF, we found major differences between patients' perceptions and physicians' assessments of risks and benefits of OAC. To ensure shared decision-making and informed

On estimation of time-dependent attributable fraction from population-based case-control studies.

Science.gov (United States)

Zhao, Wei; Chen, Ying Qing; Hsu, Li

2017-09-01

Population attributable fraction (PAF) is widely used to quantify the disease burden associated with a modifiable exposure in a population. It has been extended to a time-varying measure that provides additional information on when and how the exposure's impact varies over time for cohort studies. However, there is no estimation procedure for PAF using data that are collected from population-based case-control studies, which, because of time and cost efficiency, are commonly used for studying genetic and environmental risk factors of disease incidences. In this article, we show that time-varying PAF is identifiable from a case-control study and develop a novel estimator of PAF. Our estimator combines odds ratio estimates from logistic regression models and density estimates of the risk factor distribution conditional on failure times in cases from a kernel smoother. The proposed estimator is shown to be consistent and asymptotically normal with asymptotic variance that can be estimated empirically from the data. Simulation studies demonstrate that the proposed estimator performs well in finite sample sizes. Finally, the method is illustrated by a population-based case-control study of colorectal cancer. © 2017, The International Biometric Society.

Estimation of risks to humans following intake of plutonium

International Nuclear Information System (INIS)

Dolphin, G.W.

1979-01-01

The lung cancer in humans induced by plutonium intake usually starts in bronchial epithelium. The main types of lung cancer are epidermoid or squamous cell carcinoma, small cell anaplastic carcinoma, carcinoid types and bronchio-loalveolar cell carcinoma. The data on cancer in the patients given intravascular injections of Thorotrast are the only source of data from which risk estimates can be made for liver cancer. In the beagles injected with plutonium citrate, the only type of liver tumors observed in cholangiosarcoma, and if this were the case for humans, then the appropriate risk estimate is 3 times lower in human patients. Bone sarcoma and the cancer of the epithelial surfaces close to bones have been reported extensively in workers and patients exposed to radium-226 and radium-224. In the case of plutonium, it is assumed for the purpose of risk estimates that the cancer of the epithelial surfaces near bones does not occur. Plutonium passes through guts following ingestion or following the clearance of particles initially deposited in respiratory tracts. In the case of all long-lived radionuclides, lower large intestines are the region which receive the greatest dose from the activity passing through guts. It is assumed that plutonium accumulates in bone marrows through the action of macrophages engulfing the plutonium resorbed from bone surfaces. The main uncertainty in estimating the annual limit of intake probably lies in the metabolic and dosimetric models, and to a lesser extent, in the estimate of risk. (Yamashita, S.)

Comparison of prospective risk estimates for postoperative complications: human vs computer model.

Science.gov (United States)

Glasgow, Robert E; Hawn, Mary T; Hosokawa, Patrick W; Henderson, William G; Min, Sung-Joon; Richman, Joshua S; Tomeh, Majed G; Campbell, Darrell; Neumayer, Leigh A

2014-02-01

Surgical quality improvement tools such as NSQIP are limited in their ability to prospectively affect individual patient care by the retrospective audit and feedback nature of their design. We hypothesized that statistical models using patient preoperative characteristics could prospectively provide risk estimates of postoperative adverse events comparable to risk estimates provided by experienced surgeons, and could be useful for stratifying preoperative assessment of patient risk. This was a prospective observational cohort. Using previously developed models for 30-day postoperative mortality, overall morbidity, cardiac, thromboembolic, pulmonary, renal, and surgical site infection (SSI) complications, model and surgeon estimates of risk were compared with each other and with actual 30-day outcomes. The study cohort included 1,791 general surgery patients operated on between June 2010 and January 2012. Observed outcomes were mortality (0.2%), overall morbidity (8.2%), and pulmonary (1.3%), cardiac (0.3%), thromboembolism (0.2%), renal (0.4%), and SSI (3.8%) complications. Model and surgeon risk estimates showed significant correlation (p risk for overall morbidity to be low, the model-predicted risk and observed morbidity rates were 2.8% and 4.1%, respectively, compared with 10% and 18% in perceived high risk patients. Patients in the highest quartile of model-predicted risk accounted for 75% of observed mortality and 52% of morbidity. Across a broad range of general surgical operations, we confirmed that the model risk estimates are in fairly good agreement with risk estimates of experienced surgeons. Using these models prospectively can identify patients at high risk for morbidity and mortality, who could then be targeted for intervention to reduce postoperative complications. Published by Elsevier Inc.

Cancer risk estimation from the A-bomb survivors

International Nuclear Information System (INIS)

Pierce, D.A.; Vaeth, M.

1989-10-01

Generalizations regarding radiogenic cancer risks from the A-bomb survivor data of the Radiation Effects Research Foundation involve a large number of well-identified uncertainties and approximations. These include extrapolation to low doses and dose rates, projections in time, sampling variation, the quality of the data, extrapolation to other populations, and the use of simplifying conventions. This paper discusses some of these issues, with emphasis on the first three. Results are given regarding the maximum 'linear-quadratic' curvature consistent with these data, taking into account uncertainties in individual exposure estimates. Discussion is given regarding use of relative risk models and projection of lifetime risks, emphasizing results for those who were old enough at exposure to have been followed up for a major part of their lives by now, and stressing the speculative aspects of conclusions about those exposed as children. Combining these results, and brief discussion of other uncertainties itemized above, comment is made on the evolution of risk estimates over the past 15 years. (author)

A clustering approach to segmenting users of internet-based risk calculators.

Science.gov (United States)

Harle, C A; Downs, J S; Padman, R

2011-01-01

Risk calculators are widely available Internet applications that deliver quantitative health risk estimates to consumers. Although these tools are known to have varying effects on risk perceptions, little is known about who will be more likely to accept objective risk estimates. To identify clusters of online health consumers that help explain variation in individual improvement in risk perceptions from web-based quantitative disease risk information. A secondary analysis was performed on data collected in a field experiment that measured people's pre-diabetes risk perceptions before and after visiting a realistic health promotion website that provided quantitative risk information. K-means clustering was performed on numerous candidate variable sets, and the different segmentations were evaluated based on between-cluster variation in risk perception improvement. Variation in responses to risk information was best explained by clustering on pre-intervention absolute pre-diabetes risk perceptions and an objective estimate of personal risk. Members of a high-risk overestimater cluster showed large improvements in their risk perceptions, but clusters of both moderate-risk and high-risk underestimaters were much more muted in improving their optimistically biased perceptions. Cluster analysis provided a unique approach for segmenting health consumers and predicting their acceptance of quantitative disease risk information. These clusters suggest that health consumers were very responsive to good news, but tended not to incorporate bad news into their self-perceptions much. These findings help to quantify variation among online health consumers and may inform the targeted marketing of and improvements to risk communication tools on the Internet.

Some statistical considerations related to the estimation of cancer risk following exposure to ionizing radiation

International Nuclear Information System (INIS)

Land, C.E.; Pierce, D.A.

1983-01-01

Statistical theory and methodology provide the logical structure for scientific inference about the cancer risk associated with exposure to ionizing radiation. Although much is known about radiation carcinogenesis, the risk associated with low-level exposures is difficult to assess because it is too small to measure directly. Estimation must therefore depend upon mathematical models which relate observed risks at high exposure levels to risks at lower exposure levels. Extrapolated risk estimates obtained using such models are heavily dependent upon assumptions about the shape of the dose-response relationship, the temporal distribution of risk following exposure, and variation of risk according to variables such as age at exposure, sex, and underlying population cancer rates. Expanded statistical models, which make explicit certain assumed relationships between different data sets, can be used to strengthen inferences by incorporating relevant information from diverse sources. They also allow the uncertainties inherent in information from related data sets to be expressed in estimates which partially depend upon that information. To the extent that informed opinion is based upon a valid assessment of scientific data, the larger context of decision theory, which includes statistical theory, provides a logical framework for the incorporation into public policy decisions of the informational content of expert opinion

FN-curves: preliminary estimation of severe accident risks after Fukushima

International Nuclear Information System (INIS)

Vasconcelos, Vanderley de; Soares, Wellington Antonio; Costa, Antonio Carlos Lopes da

2015-01-01

Doubts of whether the risks related to severe accidents in nuclear reactors are indeed very low were raised after the nuclear accident at Fukushima Daiichi in 2011. Risk estimations of severe accidents in nuclear power plants involve both probability and consequence assessment of such events. Among the ways to display risks, risk curves are tools that express the frequency of exceeding a certain magnitude of consequence. Societal risk is often represented graphically in a FN-curve, a type of risk curve, which displays the probability of having N or more fatalities per year, as a function of N, on a double logarithmic scale. The FN-curve, originally introduced for the assessment of the risks in the nuclear industry through the U.S.NRC Reactor Safety Study WASH-1400 (1975), is used in various countries to express and limit risks of hazardous activities. This first study estimated an expected rate of core damage equal to 5x10 -5 by reactor-year and suggested an upper bound of 3x10 -4 by reactor-year. A more recent report issued by Electric Power Research Institute - EPRI (2008) estimates a figure of the order of 2x10 -5 by reactor-year. The Fukushima nuclear accident apparently implies that the observed core damage frequency is higher than that predicted by these probabilistic safety assessments. Therefore, this paper presents a preliminary analyses of the FN-curves related to severe nuclear reactor accidents, taking into account a combination of available data of past accidents, probability modelling to estimate frequencies, and expert judgments. (author)

FN-curves: preliminary estimation of severe accident risks after Fukushima

Energy Technology Data Exchange (ETDEWEB)

Vasconcelos, Vanderley de; Soares, Wellington Antonio; Costa, Antonio Carlos Lopes da, E-mail: vasconv@cdtn.br, E-mail: soaresw@cdtn.br, E-mail: aclc@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2015-07-01

Doubts of whether the risks related to severe accidents in nuclear reactors are indeed very low were raised after the nuclear accident at Fukushima Daiichi in 2011. Risk estimations of severe accidents in nuclear power plants involve both probability and consequence assessment of such events. Among the ways to display risks, risk curves are tools that express the frequency of exceeding a certain magnitude of consequence. Societal risk is often represented graphically in a FN-curve, a type of risk curve, which displays the probability of having N or more fatalities per year, as a function of N, on a double logarithmic scale. The FN-curve, originally introduced for the assessment of the risks in the nuclear industry through the U.S.NRC Reactor Safety Study WASH-1400 (1975), is used in various countries to express and limit risks of hazardous activities. This first study estimated an expected rate of core damage equal to 5x10{sup -5} by reactor-year and suggested an upper bound of 3x10{sup -4} by reactor-year. A more recent report issued by Electric Power Research Institute - EPRI (2008) estimates a figure of the order of 2x10{sup -5} by reactor-year. The Fukushima nuclear accident apparently implies that the observed core damage frequency is higher than that predicted by these probabilistic safety assessments. Therefore, this paper presents a preliminary analyses of the FN-curves related to severe nuclear reactor accidents, taking into account a combination of available data of past accidents, probability modelling to estimate frequencies, and expert judgments. (author)

Radiation-Induced Second Cancer Risk Estimates From Radionuclide Therapy

Science.gov (United States)

Bednarz, Bryan; Besemer, Abigail

2017-09-01

The use of radionuclide therapy in the clinical setting is expected to increase significantly over the next decade. There is an important need to understand the radiation-induced second cancer risk associated with these procedures. In this study the radiation-induced cancer risk in five radionuclide therapy patients was investigated. These patients underwent serial SPECT imaging scans following injection as part of a clinical trial testing the efficacy of a 131Iodine-labeled radiopharmaceutical. Using these datasets the committed absorbed doses to multiple sensitive structures were calculated using RAPID, which is a novel Monte Carlo-based 3D dosimetry platform developed for personalized dosimetry. The excess relative risk (ERR) for radiation-induced cancer in these structures was then derived from these dose estimates following the recommendations set forth in the BEIR VII report. The radiation-induced leukemia ERR was highest among all sites considered reaching a maximum value of approximately 4.5. The radiation-induced cancer risk in the kidneys, liver and spleen ranged between 0.3 and 1.3. The lifetime attributable risks (LARs) were also calculated, which ranged from 30 to 1700 cancers per 100,000 persons and were highest for leukemia and the liver for both males and females followed by radiation-induced spleen and kidney cancer. The risks associated with radionuclide therapy are similar to the risk associated with external beam radiation therapy.

Impact of microbial count distributions on human health risk estimates

DEFF Research Database (Denmark)

Ribeiro Duarte, Ana Sofia; Nauta, Maarten

2015-01-01

Quantitative microbiological risk assessment (QMRA) is influenced by the choice of the probability distribution used to describe pathogen concentrations, as this may eventually have a large effect on the distribution of doses at exposure. When fitting a probability distribution to microbial...... enumeration data, several factors may have an impact on the accuracy of that fit. Analysis of the best statistical fits of different distributions alone does not provide a clear indication of the impact in terms of risk estimates. Thus, in this study we focus on the impact of fitting microbial distributions...... on risk estimates, at two different concentration scenarios and at a range of prevalence levels. By using five different parametric distributions, we investigate whether different characteristics of a good fit are crucial for an accurate risk estimate. Among the factors studied are the importance...

Maximum likelihood estimation of semiparametric mixture component models for competing risks data.

Science.gov (United States)

Choi, Sangbum; Huang, Xuelin

2014-09-01

In the analysis of competing risks data, the cumulative incidence function is a useful quantity to characterize the crude risk of failure from a specific event type. In this article, we consider an efficient semiparametric analysis of mixture component models on cumulative incidence functions. Under the proposed mixture model, latency survival regressions given the event type are performed through a class of semiparametric models that encompasses the proportional hazards model and the proportional odds model, allowing for time-dependent covariates. The marginal proportions of the occurrences of cause-specific events are assessed by a multinomial logistic model. Our mixture modeling approach is advantageous in that it makes a joint estimation of model parameters associated with all competing risks under consideration, satisfying the constraint that the cumulative probability of failing from any cause adds up to one given any covariates. We develop a novel maximum likelihood scheme based on semiparametric regression analysis that facilitates efficient and reliable estimation. Statistical inferences can be conveniently made from the inverse of the observed information matrix. We establish the consistency and asymptotic normality of the proposed estimators. We validate small sample properties with simulations and demonstrate the methodology with a data set from a study of follicular lymphoma. © 2014, The International Biometric Society.

Artificial force fields for multi-agent simulations of maritime traffic and risk estimation

NARCIS (Netherlands)

Xiao, F.; Ligteringen, H.; Van Gulijk, C.; Ale, B.J.M.

2012-01-01

A probabilistic risk model is designed to estimate probabilities of collisions for shipping accidents in busy waterways. We propose a method based on multi-agent simulation that uses an artificial force field to model ship maneuvers. The artificial force field is calibrated by AIS data (Automatic

Distribution of Estimated 10-Year Risk of Recurrent Vascular Events and Residual Risk in a Secondary Prevention Population

NARCIS (Netherlands)

Kaasenbrood, Lotte; Boekholdt, S. Matthijs; van der Graaf, Yolanda; Ray, Kausik K.; Peters, Ron J. G.; Kastelein, John J. P.; Amarenco, Pierre; LaRosa, John C.; Cramer, Maarten J. M.; Westerink, Jan; Kappelle, L. Jaap; de Borst, Gert J.; Visseren, Frank L. J.

2016-01-01

Among patients with clinically manifest vascular disease, the risk of recurrent vascular events is likely to vary. We assessed the distribution of estimated 10-year risk of recurrent vascular events in a secondary prevention population. We also estimated the potential risk reduction and residual

Distribution of Estimated 10-Year Risk of Recurrent Vascular Events and Residual Risk in a Secondary Prevention Population

NARCIS (Netherlands)

Kaasenbrood, Lotte; Boekholdt, S. Matthijs; Van Der Graaf, Yolanda; Ray, Kausik K.; Peters, Ron J G; Kastelein, John J P; Amarenco, Pierre; Larosa, John C.; Cramer, Maarten J M; Westerink, Jan; Kappelle, L. Jaap; De Borst, Gert J.; Visseren, Frank L J

2016-01-01

Background: Among patients with clinically manifest vascular disease, the risk of recurrent vascular events is likely to vary. We assessed the distribution of estimated 10-year risk of recurrent vascular events in a secondary prevention population. We also estimated the potential risk reduction and

Estimating Stochastic Volatility Models using Prediction-based Estimating Functions

DEFF Research Database (Denmark)

Lunde, Asger; Brix, Anne Floor

to the performance of the GMM estimator based on conditional moments of integrated volatility from Bollerslev and Zhou (2002). The case where the observed log-price process is contaminated by i.i.d. market microstructure (MMS) noise is also investigated. First, the impact of MMS noise on the parameter estimates from......In this paper prediction-based estimating functions (PBEFs), introduced in Sørensen (2000), are reviewed and PBEFs for the Heston (1993) stochastic volatility model are derived. The finite sample performance of the PBEF based estimator is investigated in a Monte Carlo study, and compared...... to correctly account for the noise are investigated. Our Monte Carlo study shows that the estimator based on PBEFs outperforms the GMM estimator, both in the setting with and without MMS noise. Finally, an empirical application investigates the possible challenges and general performance of applying the PBEF...

A practical approach to risk-benefit estimation in pediatric drug research.

Science.gov (United States)

Koren, Gideon

2015-02-01

One of the most difficult challenges in pediatric drug research is in exposing children to risk, often without a balanced chance of benefits. While the concept of risk is similar in adult research, the adult patient can decide for himself/herself on an acceptable level of risk, whereas children have to accept the decisions of their guardians. This paper attempts to put the complexities of estimating risk in pediatric drug research into their practical perspective, and to familiarize the reader with the way such processes are conducted in different parts of the world. Although there are regional differences, all authorities typically quantify risks of pediatric research in general, and drug research in particular, in three levels: those experienced in day-to-day life; risks slightly above this 'baseline' risk; and risks substantially above 'baseline risk'. Proportionally, the diligence of the ethics process depends on these levels, as well as on the potential benefits (or lack of) to the child involved in the research. Importantly, risk is context dependent, and a particular intervention may be effective or safe in one setting but not in another, based on local experience, staffing levels, and similar variabilities.

Radiobiological risk estimates of adverse events and secondary cancer for proton and photon radiation therapy of pediatric medulloblastoma

Energy Technology Data Exchange (ETDEWEB)

Brodin, N. Patrik (Radiation Medicine Research Center, Dept. of Radiation Oncology, Rigshospitalet, Univ. of Copenhagen (Denmark); Niels Bohr Inst., Faculty of Sciences, Univ. of Copenhagen (Denmark)), e-mail: brodin.patrik@gmail.com; Munck af Rosenschoeld, Per; Aznar, Marianne C.; Vogelius, Ivan R. (Radiation Medicine Research Center, Dept. of Radiation Oncology, Rigshospitalet, Univ. of Copenhagen (Denmark)); Kiil-Berthelsen, Anne (Radiation Medicine Research Center, Dept. of Radiation Oncology, Rigshospitalet, Univ. of Copenhagen (Denmark); Dept. of Clinical Physiology and Nuclear Medicine, Centre of Diagnostic Investigations, Rigshospitalet, Univ. of Copenhagen (Denmark)); Nilsson, Per; Bjoerk-Eriksson, Thomas (Dept. of Oncology, Skaane Univ. Hospital and Lund Univ., Lund (Sweden)); Lannering, Birgitta (Dept. of Paediatric Oncology, The Queen Silvia Children' s Hospital, Gothenburg (Sweden))

2011-08-15

Introduction. The aim of this model study was to estimate and compare the risk of radiation-induced adverse late effects in pediatric patients with medulloblastoma (MB) treated with either three-dimensional conformal radiotherapy (3D CRT), inversely-optimized arc therapy (RapidArc (RA)) or spot-scanned intensity-modulated proton therapy (IMPT). The aim was also to find dose-volume toxicity parameters relevant to children undergoing RT to be used in the inverse planning of RA and IMPT, and to use in the risk estimations. Material and methods. Treatment plans were created for all three techniques on 10 pediatric patients that have been treated with craniospinal irradiation (CSI) at our institution in 2007-2009. Plans were generated for two prescription CSI doses, 23.4 Gy and 36 Gy. Risk estimates were based on childhood cancer survivor data when available and secondary cancer (SC) risks were estimated as a function of age at exposure and attained age according to the organ-equivalent dose (OED) concept. Results. Estimates of SC risk was higher for the RA plans and differentiable from the estimates for 3D CRT at attained ages above 40 years. The risk of developing heart failure, hearing loss, hypothyroidism and xerostomia was highest for the 3D CRT plans. The risks of all adverse effects were estimated as lowest for the IMPT plans, even when including secondary neutron (SN) irradiation with high values of the neutron radiation weighting factors (WR{sub neutron}). Conclusions. When comparing RA and 3D CRT treatment for pediatric MB it is a matter of comparing higher SC risk against higher risks of non-cancer adverse events. Considering time until onset of the different complications is necessary to fully assess patient benefit in such a comparison. The IMPT plans, including SN dose contribution, compared favorably to the photon techniques in terms of all radiobiological risk estimates

Radiobiological risk estimates of adverse events and secondary cancer for proton and photon radiation therapy of pediatric medulloblastoma

International Nuclear Information System (INIS)

Brodin, N. Patrik; Munck af Rosenschoeld, Per; Aznar, Marianne C.; Vogelius, Ivan R.; Kiil-Berthelsen, Anne; Nilsson, Per; Bjoerk-Eriksson, Thomas; Lannering, Birgitta

2011-01-01

Introduction. The aim of this model study was to estimate and compare the risk of radiation-induced adverse late effects in pediatric patients with medulloblastoma (MB) treated with either three-dimensional conformal radiotherapy (3D CRT), inversely-optimized arc therapy (RapidArc (RA)) or spot-scanned intensity-modulated proton therapy (IMPT). The aim was also to find dose-volume toxicity parameters relevant to children undergoing RT to be used in the inverse planning of RA and IMPT, and to use in the risk estimations. Material and methods. Treatment plans were created for all three techniques on 10 pediatric patients that have been treated with craniospinal irradiation (CSI) at our institution in 2007-2009. Plans were generated for two prescription CSI doses, 23.4 Gy and 36 Gy. Risk estimates were based on childhood cancer survivor data when available and secondary cancer (SC) risks were estimated as a function of age at exposure and attained age according to the organ-equivalent dose (OED) concept. Results. Estimates of SC risk was higher for the RA plans and differentiable from the estimates for 3D CRT at attained ages above 40 years. The risk of developing heart failure, hearing loss, hypothyroidism and xerostomia was highest for the 3D CRT plans. The risks of all adverse effects were estimated as lowest for the IMPT plans, even when including secondary neutron (SN) irradiation with high values of the neutron radiation weighting factors (WR neutron ). Conclusions. When comparing RA and 3D CRT treatment for pediatric MB it is a matter of comparing higher SC risk against higher risks of non-cancer adverse events. Considering time until onset of the different complications is necessary to fully assess patient benefit in such a comparison. The IMPT plans, including SN dose contribution, compared favorably to the photon techniques in terms of all radiobiological risk estimates

Portfolio Value at Risk Estimate for Crude Oil Markets: A Multivariate Wavelet Denoising Approach

Directory of Open Access Journals (Sweden)

Kin Keung Lai

2012-04-01

Full Text Available In the increasingly globalized economy these days, the major crude oil markets worldwide are seeing higher level of integration, which results in higher level of dependency and transmission of risks among different markets. Thus the risk of the typical multi-asset crude oil portfolio is influenced by dynamic correlation among different assets, which has both normal and transient behaviors. This paper proposes a novel multivariate wavelet denoising based approach for estimating Portfolio Value at Risk (PVaR. The multivariate wavelet analysis is introduced to analyze the multi-scale behaviors of the correlation among different markets and the portfolio volatility behavior in the higher dimensional time scale domain. The heterogeneous data and noise behavior are addressed in the proposed multi-scale denoising based PVaR estimation algorithm, which also incorporatesthe mainstream time series to address other well known data features such as autocorrelation and volatility clustering. Empirical studies suggest that the proposed algorithm outperforms the benchmark ExponentialWeighted Moving Average (EWMA and DCC-GARCH model, in terms of conventional performance evaluation criteria for the model reliability.

A non-stationary cost-benefit based bivariate extreme flood estimation approach

Science.gov (United States)

Qi, Wei; Liu, Junguo

2018-02-01

Cost-benefit analysis and flood frequency analysis have been integrated into a comprehensive framework to estimate cost effective design values. However, previous cost-benefit based extreme flood estimation is based on stationary assumptions and analyze dependent flood variables separately. A Non-Stationary Cost-Benefit based bivariate design flood estimation (NSCOBE) approach is developed in this study to investigate influence of non-stationarities in both the dependence of flood variables and the marginal distributions on extreme flood estimation. The dependence is modeled utilizing copula functions. Previous design flood selection criteria are not suitable for NSCOBE since they ignore time changing dependence of flood variables. Therefore, a risk calculation approach is proposed based on non-stationarities in both marginal probability distributions and copula functions. A case study with 54-year observed data is utilized to illustrate the application of NSCOBE. Results show NSCOBE can effectively integrate non-stationarities in both copula functions and marginal distributions into cost-benefit based design flood estimation. It is also found that there is a trade-off between maximum probability of exceedance calculated from copula functions and marginal distributions. This study for the first time provides a new approach towards a better understanding of influence of non-stationarities in both copula functions and marginal distributions on extreme flood estimation, and could be beneficial to cost-benefit based non-stationary bivariate design flood estimation across the world.

A New Model for the Estimation of Breast Cancer Risk

National Research Council Canada - National Science Library

Giger, Maryellen Lissak

2001-01-01

... for use in estimating risk of breast cancer. The specific aims include 1. Creating a database of mammograms, along with tabulated clinical information of women at low risk and high risk for breast cancer; 2...

Estimation of enhanced cancer risk with 18FDG PET/CT investigations

International Nuclear Information System (INIS)

Kaushik, Aruna; Mishra, Anil K.; Sharma, Rajnish; Mondal, Anupam; Dwarakanath, B.S.

2014-01-01

18 F-Fluorodeoxyglucose ( 18 FDG) Positron Emission Tomography/Computed Tomography (PET/CT) investigation involves internal administration of 18 FDG and use of CT X-rays for the purpose of obtaining functional and anatomical information of a patient. However, the radiation exposure from undergoing PET/CT investigation may enhance the risk of cancer incidence as per the Linear-No-Threshold (LNT) model. The objective of the present study was to quantify the risk of cancer incidence associated with radiation exposure from 18 FDG PET/CT investigations. The organ doses from internally administered 18 FDG were estimated using OLINDA/EXM Code by performing dynamic PET scans in different regions of the body in a total of forty-nine patients. Organ doses from the CT component were calculated using the software CT-Expo. The associated cancer risk was calculated in terms of life time risk of cancer incidence resulting from a specified dose of ionizing radiation and was expressed in terms of Lifetime Attributable Risk (LAR). LAR values and the organ doses estimated for males and females were used to estimate the lifetime risk of cancer incidence from whole body 18 FDG PET/CT scan. Since from 18 FDG whole body PET/CT investigations, various tissues of the body receive substantially different doses, the site specific risk of cancer incidence was estimated and summed to obtain the total risk. This was compared with the baseline lifetime risk of cancer incidence in Indian population. LAR of cancer incidence was observed to be relatively higher in females as compared to males. The risk estimates ranged from 0.36% to 0.49% for a 20 year old male and 0.58% to 0.79% for a 20 year old female and were observed to be higher in younger ages and decreased with age. 18 FDG whole body PET/CT investigation was observed to be associated with non-negligible radiation risk as compared to the risks associated with other diagnostic modalities. (author)

Reconstruction of financial networks for robust estimation of systemic risk

Science.gov (United States)

Mastromatteo, Iacopo; Zarinelli, Elia; Marsili, Matteo

2012-03-01

In this paper we estimate the propagation of liquidity shocks through interbank markets when the information about the underlying credit network is incomplete. We show that techniques such as maximum entropy currently used to reconstruct credit networks severely underestimate the risk of contagion by assuming a trivial (fully connected) topology, a type of network structure which can be very different from the one empirically observed. We propose an efficient message-passing algorithm to explore the space of possible network structures and show that a correct estimation of the network degree of connectedness leads to more reliable estimations for systemic risk. Such an algorithm is also able to produce maximally fragile structures, providing a practical upper bound for the risk of contagion when the actual network structure is unknown. We test our algorithm on ensembles of synthetic data encoding some features of real financial networks (sparsity and heterogeneity), finding that more accurate estimations of risk can be achieved. Finally we find that this algorithm can be used to control the amount of information that regulators need to require from banks in order to sufficiently constrain the reconstruction of financial networks.

Reconstruction of financial networks for robust estimation of systemic risk

International Nuclear Information System (INIS)

Mastromatteo, Iacopo; Zarinelli, Elia; Marsili, Matteo

2012-01-01

In this paper we estimate the propagation of liquidity shocks through interbank markets when the information about the underlying credit network is incomplete. We show that techniques such as maximum entropy currently used to reconstruct credit networks severely underestimate the risk of contagion by assuming a trivial (fully connected) topology, a type of network structure which can be very different from the one empirically observed. We propose an efficient message-passing algorithm to explore the space of possible network structures and show that a correct estimation of the network degree of connectedness leads to more reliable estimations for systemic risk. Such an algorithm is also able to produce maximally fragile structures, providing a practical upper bound for the risk of contagion when the actual network structure is unknown. We test our algorithm on ensembles of synthetic data encoding some features of real financial networks (sparsity and heterogeneity), finding that more accurate estimations of risk can be achieved. Finally we find that this algorithm can be used to control the amount of information that regulators need to require from banks in order to sufficiently constrain the reconstruction of financial networks

An Estimation of Risk Impact of Anticipated Transients without Scram for a KSNP

Energy Technology Data Exchange (ETDEWEB)

Han, Seok Jung; Yang Joon Eon

2006-07-15

Anticipated transient without scram (ATWS) event is an accident sequence with large risk impact, while it is a beyond design basis accident (BDBA). We have estimated a risk due to an ATWS accident sequence for the KSNP in consideration of the recent accident analysis results. The SECY-83-293's model for the CE type plants has been used in a risk estimation of ATWS. A risk estimation due to an ATWS for the KSNP has been performed in consideration of the recent ATWS accident analysis results and plant information. We reviewed influence factors in the SECY-83-293's model, these factors have been re-estimated by using current information and PSA results for a KSNP. A risk due to an ATWS has been estimated as 3.6E-6/yr of CDF by using domestic aspect and recent KSNP information. A sensitivity study for the UET variation has been performed. As the results of the sensitivity analysis, the overall risk spectrum by the UET variation is bounded between 7.80E-7/yr to 8.00E-6/yr of CDF. As the result of the current study, the risk due to an ATWS accident sequence has been identified as a considerable impact on the entire risk of a KSNP, so the risk estimation of that plant should be upgraded by considering the recent information like the ATWS accident analysis results. Finally, we expect that this study can become a basis for the entire risk estimation of the referred plant.

Estimation of extreme risk regions under multivariate regular variation

NARCIS (Netherlands)

Cai, J.; Einmahl, J.H.J.; de Haan, L.F.M.

2011-01-01

When considering d possibly dependent random variables, one is often interested in extreme risk regions, with very small probability p. We consider risk regions of the form {z ∈ Rd : f (z) ≤ β}, where f is the joint density and β a small number. Estimation of such an extreme risk region is difficult

ESTIMATING RISK ON THE CAPITAL MARKET WITH VaR METHOD

Directory of Open Access Journals (Sweden)

Sinisa Bogdan

2015-06-01

Full Text Available The two basic questions that every investor tries to answer before investment are questions about predicting return and risk. Risk and return are generally considered two positively correlated sizes, during the growth of risk it is expected increase of return to compensate the higher risk. The quantification of risk in the capital market represents the current topic since occurrence of securities. Together with estimated future returns it represents starting point of any investment. In this study it is described the history of the emergence of VaR methods, usefulness in assessing the risks of financial assets. Three main Value at Risk (VaR methodologies are decribed and explained in detail: historical method, parametric method and Monte Carlo method. After the theoretical review of VaR methods it is estimated risk of liquid stocks and portfolio from the Croatian capital market with historical and parametric VaR method, after which the results were compared and explained.

Genetic risks from radiation: recent assessments by the BEIR and UNSCEAR Committees and suggestions as to how future research can improve such estimates

International Nuclear Information System (INIS)

Selby, P.B.

1979-01-01

Recently two widely-recognized committees, namely the UNSCEAR and BEIR Committees, have reevaluated their estimates of genetic risks from radiation. Their estimates for gene mutations are based on two different approaches, one being the doubling-dose approach and the other being a new direct approach based on an empirical determination of the amount of dominant induced damage in the skeletons of mice in the first generation following irradiation. The estimates made by these committees are in reasonably good agreement and suggest that the genetic risks from present exposures resulting from nuclear power production are small. There is room for much improvement in the reliability of the risk estimates. The relatively new approach of measuring the amount of induced damage to the mouse skeleton shows great promise of improving knowledge about how changes in the mutation frequency affect the incidence of genetic disorders. Such findings may have considerable influence on genetic risk estimates for radiation and on the development of risk estimates for other less-well-understood environmental mutagens

Model-based approach for quantitative estimates of skin, heart, and lung toxicity risk for left-side photon and proton irradiation after breast-conserving surgery.

Science.gov (United States)

Tommasino, Francesco; Durante, Marco; D'Avino, Vittoria; Liuzzi, Raffaele; Conson, Manuel; Farace, Paolo; Palma, Giuseppe; Schwarz, Marco; Cella, Laura; Pacelli, Roberto

2017-05-01

Proton beam therapy represents a promising modality for left-side breast cancer (BC) treatment, but concerns have been raised about skin toxicity and poor cosmesis. The aim of this study is to apply skin normal tissue complication probability (NTCP) model for intensity modulated proton therapy (IMPT) optimization in left-side BC. Ten left-side BC patients undergoing photon irradiation after breast-conserving surgery were randomly selected from our clinical database. Intensity modulated photon (IMRT) and IMPT plans were calculated with iso-tumor-coverage criteria and according to RTOG 1005 guidelines. Proton plans were computed with and without skin optimization. Published NTCP models were employed to estimate the risk of different toxicity endpoints for skin, lung, heart and its substructures. Acute skin NTCP evaluation suggests a lower toxicity level with IMPT compared to IMRT when the skin is included in proton optimization strategy (0.1% versus 1.7%, p < 0.001). Dosimetric results show that, with the same level of tumor coverage, IMPT attains significant heart and lung dose sparing compared with IMRT. By NTCP model-based analysis, an overall reduction in the cardiopulmonary toxicity risk prediction can be observed for all IMPT compared to IMRT plans: the relative risk reduction from protons varies between 0.1 and 0.7 depending on the considered toxicity endpoint. Our analysis suggests that IMPT might be safely applied without increasing the risk of severe acute radiation induced skin toxicity. The quantitative risk estimates also support the potential clinical benefits of IMPT for left-side BC irradiation due to lower risk of cardiac and pulmonary morbidity. The applied approach might be relevant on the long term for the setup of cost-effectiveness evaluation strategies based on NTCP predictions.

Estimation of value at risk and conditional value at risk using normal mixture distributions model

Science.gov (United States)

Kamaruzzaman, Zetty Ain; Isa, Zaidi

2013-04-01

Normal mixture distributions model has been successfully applied in financial time series analysis. In this paper, we estimate the return distribution, value at risk (VaR) and conditional value at risk (CVaR) for monthly and weekly rates of returns for FTSE Bursa Malaysia Kuala Lumpur Composite Index (FBMKLCI) from July 1990 until July 2010 using the two component univariate normal mixture distributions model. First, we present the application of normal mixture distributions model in empirical finance where we fit our real data. Second, we present the application of normal mixture distributions model in risk analysis where we apply the normal mixture distributions model to evaluate the value at risk (VaR) and conditional value at risk (CVaR) with model validation for both risk measures. The empirical results provide evidence that using the two components normal mixture distributions model can fit the data well and can perform better in estimating value at risk (VaR) and conditional value at risk (CVaR) where it can capture the stylized facts of non-normality and leptokurtosis in returns distribution.

Summary of the BEIR V committee's estimates of genetic risks

International Nuclear Information System (INIS)

Grahn, D.

1990-01-01

The Committee on the Biological Effects of Ionizing Radiations (BEIR V) was constituted in late 1986 to conduct a comprehensive review of the biological effects of ionizing radiations focusing on information reported since the conclusion of the 1980 BEIR study, and to provide new estimates of the risks of genetic and somatic effects in humans due to low-level exposures of ionizing radiation. The Committee preferred the doubling-dose method of genetic risk estimation over the direct method. Data from animal (mouse) studies provide a median value of 100 to 114 cGy for long-term low dose rate exposure doubling doses. These values are lower than the median from human studies. The BEIR Committee believed that a doubling dose of 100 cGy would be a prudent value leading to conservative estimates. The estimated risks themselves are not much different from those generated by previous BEIR committees, UNSCEAR, and other published estimates. The Committee estimates that between 100 and 200 added cases per million live births will be observed at genetic equilibrium if the population is exposed each generation to a dose of 0.01 Sv (1 rem). Nearly half ware attributed to clinically mild dominant defects, and the balance to congenital abnormalities. (L.L.) (2 tabs.)

Estimating the annual risk of HIV transmission within HIV sero-discordant couples in sub-Saharan Africa.

Science.gov (United States)

Awad, Susanne F; Chemaitelly, Hiam; Abu-Raddad, Laith J

2018-01-01

To estimate the annual risk of HIV transmission (ϕ) within HIV sero-discordant couples in 23 countries in sub-Saharan Africa (SSA), by utilizing newly available national population-based data and accounting for factors known to potentially affect this estimation. We used a recently developed pair-based mathematical model that accommodates for HIV-dynamics temporal variation, sexual risk-behavior heterogeneity, and antiretroviral therapy (ART) scale-up. Estimated country-specific ϕ (in absence of ART) ranged between 4.2% (95% uncertainty interval (UI): 1.9%-6.3%) and 47.4% (95% UI: 37.2%-69.0%) per person-year (ppy), with a median of 12.4%. ϕ was strongly associated with HIV prevalence, with a Pearson correlation coefficient of 0.92, and was larger in high- versus low-HIV-prevalence countries. ϕ increased by 1.31% (95% confidence interval: 1.00%-1.55%) ppy for every 1% increase in HIV prevalence. ϕ estimates were similar to earlier estimates, and suggested considerable heterogeneity in HIV infectiousness across SSA. This heterogeneity may explain, partly, the differences in epidemic scales. Copyright © 2017 The Author(s). Published by Elsevier Ltd.. All rights reserved.

Estimates of Present and Future Flood Risk in the Conterminous United States

Science.gov (United States)

Wing, O.; Bates, P. D.; Smith, A.; Sampson, C. C.; Johnson, K.; Fargione, J.; Morefield, P.

2017-12-01

Past attempts to estimate flood risk across the USA either have incomplete coverage, coarse resolution or use overly simplified models of the flooding process. In this paper, we use a new 30m resolution model of the entire conterminous US (CONUS) with realistic flood physics to produce estimates of flood hazard which match to within 90% accuracy the skill of local models built with detailed data. Socio-economic data of commensurate resolution are combined with these flood depths to estimate current and future flood risk. Future population and land-use projections from the US Environmental Protection Agency (USEPA) are employed to indicate how flood risk might change through the 21st Century, while present-day estimates utilize the Federal Emergency Management Agency (FEMA) National Structure Inventory and a USEPA map of population distribution. Our data show that the total CONUS population currently exposed to serious flooding is 2.6 to 3.1 times higher than previous estimates; with nearly 41 million Americans living within the so-called 1 in 100-year (1% annual probability) floodplain, compared to only 13 million according to FEMA flood maps. Moreover, socio-economic change alone leads to significant future increases in flood exposure and risk, even before climate change impacts are accounted for. The share of the population living on the 1 in 100-year floodplain is projected to increase from 13.3% in the present-day to 15.6 - 15.8% in 2050 and 16.4 - 16.8% in 2100. The area of developed land within this floodplain, currently at 150,000 km2, is likely to increase by 37 - 72% in 2100 based on the scenarios selected. 5.5 trillion worth of assets currently lie on the 1% floodplain; we project that by 2100 this number will exceed 10 trillion. With this detailed spatial information on present-day flood risk, federal and state agencies can take appropriate action to mitigate losses. Use of USEPA population and land-use projections mean that particular attention can be

New approach for risk based inspection of H2S based Process Plants

International Nuclear Information System (INIS)

Vinod, Gopika; Sharma, Pavan K.; Santosh, T.V.; Hari Prasad, M.; Vaze, K.K.

2014-01-01

Highlights: • Study looks into improving the consequence evaluation in risk based inspection. • Ways to revise the quantity factors used in qualitative approach. • New approach based on computational fluid dynamics along with probit mathematics. • Demonstrated this methodology along with a suitable case study for the said issue. - Abstract: Recent trend in risk informed and risk based approaches in life management issues have certainly put the focus on developing estimation methods for real risk. Idea of employing risk as an optimising measure for in-service inspection, termed as risk based inspection, was accepted in principle from late 80s. While applying risk based inspection, consequence of failure from each component needs to be assessed. Consequence evaluation in a Process Plant is a crucial task. It may be noted that, in general, the number of components to be considered for life management is very large and hence the consequence evaluation resulting from their failures (individually) is a laborious task. Screening of critical components is usually carried out using simplified qualitative approach, which primarily uses influence factors for categorisation. This necessitates logical formulation of influence factors and their ranges with a suitable technical basis for acceptance from regulators. This paper describes application of risk based inspection for H 2 S based Process Plant along with the approach devised for handling the influence factor related to the quantity of H 2 S released

The estimation of risk-premium implicit in oil prices

International Nuclear Information System (INIS)

Luis, J.B.

2001-01-01

The futures price can be seen as the sum of the expected value of the underlying asset price and a risk-premium. In order to disentangle these two components of the futures price, one can try to model the relationship between spot and futures prices, in order to obtain a closed expression for the risk-premium, or to use information from spot and option prices to estimate risk-aversion functions. Given the high volatility of the ratios between futures and spot prices, we opted for the latter, estimating risk-neutral and subjective probability density functions, respectively, from observed option and spot prices. looking at the prices of Brent and West Texas Intermediate light/sweet crude oil options, the obtained evidence suggests that risk-aversion is typically very low for levels near the futures prices. However, due to price volatility and, consequently, to the tails of distribution, the risk-aversion functions are badly behaved in extreme prices and futures prices do not anticipate sharp movements in oil spot prices. Therefore, futures oil prices seem to be useful in forecasting spot prices only when moderate price changes occur. (author)

[Survival analysis with competing risks: estimating failure probability].

Science.gov (United States)

Llorca, Javier; Delgado-Rodríguez, Miguel

2004-01-01

To show the impact of competing risks of death on survival analysis. We provide an example of survival time without chronic rejection after heart transplantation, where death before rejection acts as a competing risk. Using a computer simulation, we compare the Kaplan-Meier estimator and the multiple decrement model. The Kaplan-Meier method overestimated the probability of rejection. Next, we illustrate the use of the multiple decrement model to analyze secondary end points (in our example: death after rejection). Finally, we discuss Kaplan-Meier assumptions and why they fail in the presence of competing risks. Survival analysis should be adjusted for competing risks of death to avoid overestimation of the risk of rejection produced with the Kaplan-Meier method.

A probabilistic risk assessment for field radiography based on expert judgment and opinion

International Nuclear Information System (INIS)

Jang, Han-Ki; Ryu, Hyung-Joon; Kim, Ji-Young; Lee, Jai-Ki; Cho, Kun-Woo

2011-01-01

A probabilistic approach was applied to assess radiation risk associated with the field radiography using gamma sources. The Delphi method based on the expert judgments and opinions was used in the process of characterization of parameters affecting risk, which are inevitably subject to large uncertainties. A mathematical approach applying the Bayesian inferences was employed for data processing to improve the Delphi results. This process consists of three phases: (1) setting prior distributions, (2) constructing the likelihood functions and (3) deriving the posterior distributions based on the likelihood functions. The approach for characterizing input parameters using the Bayesian inference is provided for improved risk estimates without intentional rejection of part of the data, which demonstrated utility of Bayesian updating of distributions of uncertain input parameters in PRA (Probabilistic Risk Assessment). The data analysis portion for PRA in field radiography is addressed for estimates of the parameters used to determine the frequencies and consequences of the various events modeled. In this study, radiological risks for the worker and the public member in the vicinity of the work place are estimated for field radiography system in Korea based on two-dimensional Monte Carlo Analysis (2D MCA). (author)

Bioassay-based risk assessment of complex mixtures

International Nuclear Information System (INIS)

Donnelly, K.C.; Huebner, H.J.

1996-01-01

The baseline risk assessment often plays an integral role in various decision-making processes at Superfund sites. The present study reports on risk characterizations prepared for seven complex mixtures using biological and chemical analysis. Three of the samples (A, B, and C) were complex mixtures of polycyclic aromatic hydrocarbons (PAHs) extracted from coal tar; while four samples extracted from munitions-contaminated soil contained primarily nitroaromatic hydrocarbons. The chemical-based risk assessment ranked sample C as least toxic, while the risk associated with samples A and B was approximately equal. The microbial bioassay was in general agreement for the coal tar samples. The weighted activity of the coal tar extracts in Salmonella was 4,960 for sample C, and 162,000 and 206,000 for samples A and B, respectively. The bacterial mutagenicity of 2,4,6-trinitrotoluene contaminated soils exhibited an indirect correlation with chemical-based risk assessment. The aqueous extract of sample 004 induced 1,292 net revertants in Salmonella, while the estimated risk to ingestion and dermal adsorption was 2E-9. The data indicate that the chemical-based risk assessment accurately predicted the genotoxicity of the PAHs, while the accuracy of the risk assessment for munitions contaminated soils was limited due to the presence of metabolites of TNT degradation. The biological tests used in this research provide a valuable compliment to chemical analysis for characterizing the genotoxic risk of complex mixtures

Estimating the decline in excess risk of cerebrovascular disease following quitting smoking--a systematic review based on the negative exponential model.

Science.gov (United States)

Lee, Peter N; Fry, John S; Thornton, Alison J

2014-02-01

We attempted to quantify the decline in stroke risk following quitting using the negative exponential model, with methodology previously employed for IHD. We identified 22 blocks of RRs (from 13 studies) comparing current smokers, former smokers (by time quit) and never smokers. Corresponding pseudo-numbers of cases and controls/at risk formed the data for model-fitting. We tried to estimate the half-life (H, time since quit when the excess risk becomes half that for a continuing smoker) for each block. The method failed to converge or produced very variable estimates of H in nine blocks with a current smoker RR <1.40. Rejecting these, and combining blocks by amount smoked in one study where problems arose in model-fitting, the final analyses used 11 blocks. Goodness-of-fit was adequate for each block, the combined estimate of H being 4.78(95%CI 2.17-10.50) years. However, considerable heterogeneity existed, unexplained by any factor studied, with the random-effects estimate 3.08(1.32-7.16). Sensitivity analyses allowing for reverse causation or differing assumed times for the final quitting period gave similar results. The estimates of H are similar for stroke and IHD, and the individual estimates similarly heterogeneous. Fitting the model is harder for stroke, due to its weaker association with smoking. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Ethnic disparities in educational and occupational gradients of estimated cardiovascular disease risk: The Healthy Life in an Urban Setting study.

Science.gov (United States)

Perini, Wilco; Agyemang, Charles; Snijder, Marieke B; Peters, Ron J G; Kunst, Anton E

2018-03-01

European societies are becoming increasingly ethnically diverse. This may have important implications for socio-economic inequalities in health due to the often disadvantaged position of ethnic minority groups in both socio-economic status (SES) and disease, especially cardiovascular disease (CVD). The aim of this study was to determine whether the socio-economic gradient of estimated CVD risk differs between ethnic groups. Using the Healthy Life in an Urban Setting study, we obtained data on SES and CVD risk factors among participants from six ethnic backgrounds residing in Amsterdam. SES was measured using educational level and occupational level. CVD risk was estimated based on the occurrence of CVD risk factors using the Dutch version of the systematic coronary risk evaluation algorithm. Ethnic disparities in socio-economic gradients for estimated CVD risk were determined using the relative index of inequality (RII). Among Dutch-origin men, the RII for estimated CVD risk according to educational level was 6.15% (95% confidence interval [CI] 4.35-7.96%), indicating that those at the bottom of the educational hierarchy had a 6.15% higher estimated CVD risk relative than those at the top. Among Dutch-origin women, the RII was 4.49% (CI 2.45-6.52%). The RII was lower among ethnic minority groups, ranging from 0.83% to 3.13% among men and -0.29% to 5.12% among women, indicating weaker associations among these groups. Results were similar based on occupational level. Ethnic background needs to be considered in associations between SES and disease. The predictive value of SES varies between ethnic groups and may be quite poor for some groups.

Evidence that Risk Adjustment is Unnecessary in Estimates of the User Cost of Money

Directory of Open Access Journals (Sweden)

Diego A. Restrepo-Tobón

2015-12-01

Full Text Available Investors value the  special attributes of monetary assets (e.g.,  exchangeability, liquidity, and safety  and pay a premium for holding them in the form of a lower return rate. The user cost of holding monetary assets can be measured approximately by the difference between the  returns on illiquid risky assets and  those of safer liquid assets. A more appropriate measure should adjust this difference by the  differential risk of the  assets in question. We investigate the  impact that time  non-separable preferences has on the  estimation of the  risk-adjusted user cost of money. Using U.K. data from 1965Q1 to 2011Q1, we estimate a habit-based asset pricing model  with money  in the utility function and  find that the  risk  adjustment for risky monetary assets is negligible. Thus, researchers can dispense with risk adjusting the  user cost of money  in constructing monetary aggregate indexes.

Space Radiation Heart Disease Risk Estimates for Lunar and Mars Missions

Science.gov (United States)

Cucinotta, Francis A.; Chappell, Lori; Kim, Myung-Hee

2010-01-01

The NASA Space Radiation Program performs research on the risks of late effects from space radiation for cancer, neurological disorders, cataracts, and heart disease. For mortality risks, an aggregate over all risks should be considered as well as projection of the life loss per radiation induced death. We report on a triple detriment life-table approach to combine cancer and heart disease risks. Epidemiology results show extensive heterogeneity between populations for distinct components of the overall heart disease risks including hypertension, ischaemic heart disease, stroke, and cerebrovascular diseases. We report on an update to our previous heart disease estimates for Heart disease (ICD9 390-429) and Stroke (ICD9 430-438), and other sub-groups using recent meta-analysis results for various exposed radiation cohorts to low LET radiation. Results for multiplicative and additive risk transfer models are considered using baseline rates for US males and female. Uncertainty analysis indicated heart mortality risks as low as zero, assuming a threshold dose for deterministic effects, and projections approaching one-third of the overall cancer risk. Medan life-loss per death estimates were significantly less than that of solid cancer and leukemias. Critical research questions to improve risks estimates for heart disease are distinctions in mechanisms at high doses (>2 Gy) and low to moderate doses (<2 Gy), and data and basic understanding of radiation doserate and quality effects, and individual sensitivity.

Use of results of microbiological analyses for risk-based control of Listeria monocytogenes in marinated broiler legs.

Science.gov (United States)

Aarnisalo, Kaarina; Vihavainen, Elina; Rantala, Leila; Maijala, Riitta; Suihko, Maija-Liisa; Hielm, Sebastian; Tuominen, Pirkko; Ranta, Jukka; Raaska, Laura

2008-02-10

Microbial risk assessment provides a means of estimating consumer risks associated with food products. The methods can also be applied at the plant level. In this study results of microbiological analyses were used to develop a robust single plant level risk assessment. Furthermore, the prevalence and numbers of Listeria monocytogenes in marinated broiler legs in Finland were estimated. These estimates were based on information on the prevalence, numbers and genotypes of L. monocytogenes in 186 marinated broiler legs from 41 retail stores. The products were from three main Finnish producers, which produce 90% of all marinated broiler legs sold in Finland. The prevalence and numbers of L. monocytogenes were estimated by Monte Carlo simulation using WinBUGS, but the model is applicable to any software featuring standard probability distributions. The estimated mean annual number of L. monocytogenes-positive broiler legs sold in Finland was 7.2x10(6) with a 95% credible interval (CI) 6.7x10(6)-7.7x10(6). That would be 34%+/-1% of the marinated broiler legs sold in Finland. The mean number of L. monocytogenes in marinated broiler legs estimated at the sell-by-date was 2 CFU/g, with a 95% CI of 0-14 CFU/g. Producer-specific L. monocytogenes strains were recovered from the products throughout the year, which emphasizes the importance of characterizing the isolates and identifying strains that may cause problems as part of risk assessment studies. As the levels of L. monocytogenes were low, the risk of acquiring listeriosis from these products proved to be insignificant. Consequently there was no need for a thorough national level risk assessment. However, an approach using worst-case and average point estimates was applied to produce an example of single producer level risk assessment based on limited data. This assessment also indicated that the risk from these products was low. The risk-based approach presented in this work can provide estimation of public health risk

Estimated risks and optimistic self-perception of breast cancer risk in Korean women.

Science.gov (United States)

Chung, ChaeWeon; Lee, Suk Jeong

2013-11-01

To determine women's perceived personal and comparative risks of breast cancer, and to examine the relationships with risk factors. Despite the increasing incidence of breast cancer in younger women and the availability of screening, women's health behaviors have not advanced accordingly. A cross-sectional survey design utilized a convenience sample of 222 women in their 30s and 40s recruited from community settings in Seoul. Self-administered questionnaire data were analyzed by descriptive statistics, the chi-squared test, and ANOVA. Risk perception levels differed significantly by breast cancer risk factors. Half of the women were optimistic about their breast cancer risk, while perceived personal risk did not reflect women's own risk factors and comparative risk differed only by the practice of clinical breast exam. Women's knowledge and awareness of their breast cancer risk factors need to be improved for appropriate risk perception and health behaviors, and accurate risk estimation could be utilized to educate them in clinical settings. © 2013.

Competing risk bias was common in Kaplan-Meier risk estimates published in prominent medical journals.

Science.gov (United States)

van Walraven, Carl; McAlister, Finlay A

2016-01-01

Risk estimates from Kaplan-Meier curves are well known to medical researchers, reviewers, and editors. In this study, we determined the proportion of Kaplan-Meier analyses published in prominent medical journals that are potentially biased because of competing events ("competing risk bias"). We randomly selected 100 studies that had at least one Kaplan-Meier analysis and were recently published in prominent medical journals. Susceptibility to competing risk bias was determined by examining the outcome and potential competing events. In susceptible studies, bias was quantified using a previously validated prediction model when the number of outcomes and competing events were given. Forty-six studies (46%) contained Kaplan-Meier analyses susceptible to competing risk bias. Sixteen studies (34.8%) susceptible to competing risk cited the number of outcomes and competing events; in six of these studies (6/16, 37.5%), the outcome risk from the Kaplan-Meier estimate (relative to the true risk) was biased upward by 10% or more. Almost half of Kaplan-Meier analyses published in medical journals are susceptible to competing risk bias and may overestimate event risk. This bias was found to be quantitatively important in a third of such studies. Copyright © 2016 Elsevier Inc. All rights reserved.

Cardiovascular risk estimation by professionally active cardiovascular nurses: results from the Basel 2005 Nurses Cohort.

Science.gov (United States)

Scholte op Reimer, Wilma J M; Moons, Philip; De Geest, Sabina; Fridlund, Bengt; Heikkilä, Johanna; Jaarsma, Tiny; Lenzen, Mattie; Martensson, Jan; Norekvål, Tone M; Smith, Karen; Stewart, Simon; Strömberg, Anna; Thompson, David R

2006-12-01

Nurses play a key role in the prevention of cardiovascular disease (CVD) and one would, therefore, expect them to have a heightened awareness of the need for systematic screening and their own CVD risk profile. The aim of this study was to examine personal awareness of CVD risk among a cohort of cardiovascular nurses attending a European conference. Of the 340 delegates attending the 5th annual Spring Meeting on Cardiovascular Nursing (Basel, Switzerland, 2005), 287 (83%) completed a self-report questionnaire to assess their own risk factors for CVD. Delegates were also asked to give an estimation of their absolute total risk of experiencing a fatal CVD event in the next 10 years. Level of agreement between self-reported CVD risk estimation and their actual risk according to the SCORE risk assessment system was compared by calculating weighted Kappa (kappa(w)). Overall, 109 responders (38%) self-reported having either pre-existing CVD (only 2%), one or more markedly raised CVD risk factors, a high total risk of fatal CVD (> or =5% in 10 years) or a strong family history of CVD. About half of this cohort (53%) did not know their own total cholesterol level. Less than half (45%) reported having a 10-year risk of fatal CVD of or =5%. Based on the SCORE risk function, the estimated 10-year risk of a fatal CVD event was or =5% risk of such an event. Overall, less than half (46%) of this cohort's self-reported CVD risk corresponded with that calculated using the SCORE risk function (kappa(w)=0.27). Most cardiovascular nurses attending a European conference in 2005 poorly understood their own CVD risk profile, and the agreement between their self-reported 10-year risk of a fatal CVD and their CVD risk using SCORE was only fair. Given the specialist nature of this conference, our findings clearly demonstrate a need to improve overall nursing awareness of the role and importance of systematic CVD risk assessment.

Model estimation of claim risk and premium for motor vehicle insurance by using Bayesian method

Science.gov (United States)

Sukono; Riaman; Lesmana, E.; Wulandari, R.; Napitupulu, H.; Supian, S.

2018-01-01

Risk models need to be estimated by the insurance company in order to predict the magnitude of the claim and determine the premiums charged to the insured. This is intended to prevent losses in the future. In this paper, we discuss the estimation of risk model claims and motor vehicle insurance premiums using Bayesian methods approach. It is assumed that the frequency of claims follow a Poisson distribution, while a number of claims assumed to follow a Gamma distribution. The estimation of parameters of the distribution of the frequency and amount of claims are made by using Bayesian methods. Furthermore, the estimator distribution of frequency and amount of claims are used to estimate the aggregate risk models as well as the value of the mean and variance. The mean and variance estimator that aggregate risk, was used to predict the premium eligible to be charged to the insured. Based on the analysis results, it is shown that the frequency of claims follow a Poisson distribution with parameter values λ is 5.827. While a number of claims follow the Gamma distribution with parameter values p is 7.922 and θ is 1.414. Therefore, the obtained values of the mean and variance of the aggregate claims respectively are IDR 32,667,489.88 and IDR 38,453,900,000,000.00. In this paper the prediction of the pure premium eligible charged to the insured is obtained, which amounting to IDR 2,722,290.82. The prediction of the claims and premiums aggregate can be used as a reference for the insurance company’s decision-making in management of reserves and premiums of motor vehicle insurance.

Bioassay-based risk assessment of complex mixtures

Energy Technology Data Exchange (ETDEWEB)

Donnelly, K.C.; Safe, S.H. [Texas A& M Univ., Houston, TX (United States); Randerath, K.; Randerath, E. [College Station and Baylor College of Medicine, Houston, TX (United States)

1994-12-31

To compare the standard chemical-based risk assessment with in vitro genotoxicity assays, two complex environmental mixtures from a wood preserving site were analyzed in the Salmonella/microsome and E. coli prophage induction assays. Using GC/MS, sample 003 was found to contain relatively low levels of polycyclic aromatic hydrocarbons (PNAs) and elevated levels of polychlorinated dibenzo-p-dioxins (PCDDs), while sample 005 had higher levels of PNAs and relatively low levels of PCDDs. The complex mixtures were sequentially extracted with methylene chloride and methanol for analysis in Salmonella, or extracted with 1:1 hexane: acetone mixture for analysis in the prophage induction assay. At a dose of 1.0 mg/plate in Salmonella strain TA98 with metabolic activation, the methanol extract of sample 003 induced 197 net revertants, while sample 005 induced 436 net revertants. In the prophage induction assay, with activation, the hexane:acetone extract of sample 003 induced a fold increase that was slightly lower than that observed with sample 005. The estimated incremental carcinogenic risk for dermal adsorption and ingestion was 1.5E-3 for sample 003, while for sample 005 the estimated risk was 1.5E-2. Thus, the sample which induced the maximum response in both bioassays also had the highest estimated cancer risk. However, the frequency of PNA-DNA adducts in both skin and liver tissues was appreciably higher with sample 005 than with sample 003.

Sample size estimation to substantiate freedom from disease for clustered binary data with a specific risk profile

DEFF Research Database (Denmark)

Kostoulas, P.; Nielsen, Søren Saxmose; Browne, W. J.

2013-01-01

and power when applied to these groups. We propose the use of the variance partition coefficient (VPC), which measures the clustering of infection/disease for individuals with a common risk profile. Sample size estimates are obtained separately for those groups that exhibit markedly different heterogeneity......, thus, optimizing resource allocation. A VPC-based predictive simulation method for sample size estimation to substantiate freedom from disease is presented. To illustrate the benefits of the proposed approach we give two examples with the analysis of data from a risk factor study on Mycobacterium avium...

Stochastic evaluation of tsunami inundation and quantitative estimating tsunami risk

International Nuclear Information System (INIS)

Fukutani, Yo; Anawat, Suppasri; Abe, Yoshi; Imamura, Fumihiko

2014-01-01

We performed a stochastic evaluation of tsunami inundation by using results of stochastic tsunami hazard assessment at the Soma port in the Tohoku coastal area. Eleven fault zones along the Japan trench were selected as earthquake faults generating tsunamis. The results show that estimated inundation area of return period about 1200 years had good agreement with that in the 2011 Tohoku earthquake. In addition, we evaluated quantitatively tsunami risk for four types of building; a reinforced concrete, a steel, a brick and a wood at the Soma port by combining the results of inundation assessment and tsunami fragility assessment. The results of quantitative estimating risk would reflect properly vulnerability of the buildings, that the wood building has high risk and the reinforced concrete building has low risk. (author)

Identifying patient preferences for communicating risk estimates: A descriptive pilot study

Directory of Open Access Journals (Sweden)

O'Connor Annette M

2001-08-01

Full Text Available Abstract Background Patients increasingly seek more active involvement in health care decisions, but little is known about how to communicate complex risk information to patients. The objective of this study was to elicit patient preferences for the presentation and framing of complex risk information. Method To accomplish this, eight focus group discussions and 15 one-on-one interviews were conducted, where women were presented with risk data in a variety of different graphical formats, metrics, and time horizons. Risk data were based on a hypothetical woman's risk for coronary heart disease, hip fracture, and breast cancer, with and without hormone replacement therapy. Participants' preferences were assessed using likert scales, ranking, and abstractions of focus group discussions. Results Forty peri- and postmenopausal women were recruited through hospital fliers (n = 25 and a community health fair (n = 15. Mean age was 51 years, 50% were non-Caucasian, and all had completed high school. Bar graphs were preferred by 83% of participants over line graphs, thermometer graphs, 100 representative faces, and survival curves. Lifetime risk estimates were preferred over 10 or 20-year horizons, and absolute risks were preferred over relative risks and number needed to treat. Conclusion Although there are many different formats for presenting and framing risk information, simple bar charts depicting absolute lifetime risk were rated and ranked highest overall for patient preferences for format.

Using the Violence Risk Scale-Sexual Offense version in sexual violence risk assessments: Updated risk categories and recidivism estimates from a multisite sample of treated sexual offenders.

Science.gov (United States)

Olver, Mark E; Mundt, James C; Thornton, David; Beggs Christofferson, Sarah M; Kingston, Drew A; Sowden, Justina N; Nicholaichuk, Terry P; Gordon, Audrey; Wong, Stephen C P

2018-04-30

The present study sought to develop updated risk categories and recidivism estimates for the Violence Risk Scale-Sexual Offense version (VRS-SO; Wong, Olver, Nicholaichuk, & Gordon, 2003-2017), a sexual offender risk assessment and treatment planning tool. The overarching purpose was to increase the clarity and accuracy of communicating risk assessment information that includes a systematic incorporation of new information (i.e., change) to modify risk estimates. Four treated samples of sexual offenders with VRS-SO pretreatment, posttreatment, and Static-99R ratings were combined with a minimum follow-up period of 10-years postrelease (N = 913). Logistic regression was used to model 5- and 10-year sexual and violent (including sexual) recidivism estimates across 6 different regression models employing specific risk and change score information from the VRS-SO and/or Static-99R. A rationale is presented for clinical applications of select models and the necessity of controlling for baseline risk when utilizing change information across repeated assessments. Information concerning relative risk (percentiles) and absolute risk (recidivism estimates) is integrated with common risk assessment language guidelines to generate new risk categories for the VRS-SO. Guidelines for model selection and forensic clinical application of the risk estimates are discussed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Panel data nonparametric estimation of production risk and risk preferences

DEFF Research Database (Denmark)

Czekaj, Tomasz Gerard; Henningsen, Arne

approaches for obtaining firm-specific measures of risk attitudes. We found that Polish dairy farmers are risk averse regarding production risk and price uncertainty. According to our results, Polish dairy farmers perceive the production risk as being more significant than the risk related to output price......We apply nonparametric panel data kernel regression to investigate production risk, out-put price uncertainty, and risk attitudes of Polish dairy farms based on a firm-level unbalanced panel data set that covers the period 2004–2010. We compare different model specifications and different...

Improved seismic risk estimation for Bucharest, based on multiple hazard scenarios, analytical methods and new techniques

Science.gov (United States)

Toma-Danila, Dragos; Florinela Manea, Elena; Ortanza Cioflan, Carmen

2014-05-01

Bucharest, capital of Romania (with 1678000 inhabitants in 2011), is one of the most exposed big cities in Europe to seismic damage. The major earthquakes affecting the city have their origin in the Vrancea region. The Vrancea intermediate-depth source generates, statistically, 2-3 shocks with moment magnitude >7.0 per century. Although the focal distance is greater than 170 km, the historical records (from the 1838, 1894, 1908, 1940 and 1977 events) reveal severe effects in the Bucharest area, e.g. intensities IX (MSK) for the case of 1940 event. During the 1977 earthquake, 1420 people were killed and 33 large buildings collapsed. The nowadays building stock is vulnerable both due to construction (material, age) and soil conditions (high amplification, generated within the weak consolidated Quaternary deposits, their thickness is varying 250-500m throughout the city). A number of 373 old buildings, out of 2563, evaluated by experts are more likely to experience severe damage/collapse in the next major earthquake. The total number of residential buildings, in 2011, was 113900. In order to guide the mitigation measures, different studies tried to estimate the seismic risk of Bucharest, in terms of buildings, population or economic damage probability. Unfortunately, most of them were based on incomplete sets of data, whether regarding the hazard or the building stock in detail. However, during the DACEA Project, the National Institute for Earth Physics, together with the Technical University of Civil Engineering Bucharest and NORSAR Institute managed to compile a database for buildings in southern Romania (according to the 1999 census), with 48 associated capacity and fragility curves. Until now, the developed real-time estimation system was not implemented for Bucharest. This paper presents more than an adaptation of this system to Bucharest; first, we analyze the previous seismic risk studies, from a SWOT perspective. This reveals that most of the studies don't use

Stochastic risk estimation from medical x-ray diagnostic examinations, 2. Risk estimates of individuals from x-ray diagnosis

Energy Technology Data Exchange (ETDEWEB)

Hashizume, T; Maruyama, T; Noda, Y; Iwai, K; Tateno, Y [National Inst. of Radiological Sciences, Chiba (Japan); Nishizawa, K

1981-01-01

The risks of genetic, leukemia and malignant diseases from medical X-ray diagnostic examinations were estimated using the frequency of radiographic and fluoroscopic exposures per diagnostic examination, child expectancy, leukemia and malignancy significant factors, and using a weighting factor determined on the basis of data concerning the cancer mortality among atomic bomb survivors in Nagasaki and of a recommendation of International Commission of Radiological Protection. The organ or tissue doses with respect to the stochastic risks were determined with ionization chambers and thermoluminescent dosimeters placed at the positions of the organs or tissues in a RANDO woman phantom which was exposed to diagnostic X-rays according to technical factors of typical radiographic and fluoroscopic examinations obtained from a nationwide survey. The resultant risks by age-group and type of radiographic and fluoroscopic examination are tabulated in terms of risk level of 10/sup -6/. In general, the total risk defined as the sum of genetic, leukemia and malignant risks was a high value for the X-ray diagnosis of digestive organs involving barium meal and barium enema. For example, the total risk for young age-group was 100 to 200 x 10/sup -6/ for the X-ray diagnosis of digestive organs. The total risk from the chest radiography was lower value as compared with the risk from the X-ray diagnosis of other organs or tissues. On the contrary, the risk from the chest tomography was comparable to the risk from the diagnosis of digestive organs. The total risk decreased with increasing of age for every X-ray diagnostic examination.

Burden of typhoid fever in low-income and middle-income countries: a systematic, literature-based update with risk-factor adjustment.

Science.gov (United States)

Mogasale, Vittal; Maskery, Brian; Ochiai, R Leon; Lee, Jung Seok; Mogasale, Vijayalaxmi V; Ramani, Enusa; Kim, Young Eun; Park, Jin Kyung; Wierzba, Thomas F

2014-10-01

No access to safe water is an important risk factor for typhoid fever, yet risk-level heterogeneity is unaccounted for in previous global burden estimates. Since WHO has recommended risk-based use of typhoid polysaccharide vaccine, we revisited the burden of typhoid fever in low-income and middle-income countries (LMICs) after adjusting for water-related risk. We estimated the typhoid disease burden from studies done in LMICs based on blood-culture-confirmed incidence rates applied to the 2010 population, after correcting for operational issues related to surveillance, limitations of diagnostic tests, and water-related risk. We derived incidence estimates, correction factors, and mortality estimates from systematic literature reviews. We did scenario analyses for risk factors, diagnostic sensitivity, and case fatality rates, accounting for the uncertainty in these estimates and we compared them with previous disease burden estimates. The estimated number of typhoid fever cases in LMICs in 2010 after adjusting for water-related risk was 11·9 million (95% CI 9·9-14·7) cases with 129 000 (75 000-208 000) deaths. By comparison, the estimated risk-unadjusted burden was 20·6 million (17·5-24·2) cases and 223 000 (131 000-344 000) deaths. Scenario analyses indicated that the risk-factor adjustment and updated diagnostic test correction factor derived from systematic literature reviews were the drivers of differences between the current estimate and past estimates. The risk-adjusted typhoid fever burden estimate was more conservative than previous estimates. However, by distinguishing the risk differences, it will allow assessment of the effect at the population level and will facilitate cost-effectiveness calculations for risk-based vaccination strategies for future typhoid conjugate vaccine. Copyright © 2014 Mogasale et al. Open Access article distributed under the terms of CC BY-NC-SA. Published by .. All rights reserved.

SU-E-T-365: Estimation of Neutron Ambient Dose Equivalents for Radioprotection Exposed Workers in Radiotherapy Facilities Based On Characterization Patient Risk Estimation

Energy Technology Data Exchange (ETDEWEB)

Irazola, L; Terron, J; Sanchez-Doblado, F [Departamento de Fisiologia Medica y Biofisica, Universidad de Sevilla (Spain); Servicio de Radiofisica, Hospital Universitario Virgen Macarena, Sevilla (Spain); Domingo, C; Romero-Exposito, M [Departament de Fisica, Universitat Autonoma de Barcelona, Bellaterra (Spain); Garcia-Fuste, M [Health and Safety Department, ALBA Synchrotron Light Source, Cerdanyola del Valles (Spain); Sanchez-Nieto, B [Instituto de Fisica, Pontificia Universidad Catolica de Chile, Santiago (Chile); Bedogni, R [Laboratori Nazionali di Frascati, Istituto Nazionale di Fisica Nucleare (INFN) (Italy)

2015-06-15

Purpose: Previous measurements with Bonner spheres{sup 1} showed that normalized neutron spectra are equal for the majority of the existing linacs{sup 2}. This information, in addition to thermal neutron fluences obtained in the characterization procedure{sup 3}3, would allow to estimate neutron doses accidentally received by exposed workers, without the need of an extra experimental measurement. Methods: Monte Carlo (MC) simulations demonstrated that the thermal neutron fluence distribution inside the bunker is quite uniform, as a consequence of multiple scatter in the walls{sup 4}. Although inverse square law is approximately valid for the fast component, a more precise calculation could be obtained with a generic fast fluence distribution map around the linac, from MC simulations{sup 4}. Thus, measurements of thermal neutron fluences performed during the characterization procedure{sup 3}, together with a generic unitary spectra{sup 2}, would allow to estimate the total neutron fluences and H*(10) at any point{sup 5}. As an example, we compared estimations with Bonner sphere measurements{sup 1}, for two points in five facilities: 3 Siemens (15–23 MV), Elekta (15 MV) and Varian (15 MV). Results: Thermal neutron fluences obtained from characterization, are within (0.2–1.6×10{sup 6}) cm−{sup 2}•Gy{sup −1} for the five studied facilities. This implies ambient equivalent doses ranging from (0.27–2.01) mSv/Gy 50 cm far from the isocenter and (0.03–0.26) mSv/Gy at detector location with an average deviation of ±12.1% respect to Bonner measurements. Conclusion: The good results obtained demonstrate that neutron fluence and H*(10) can be estimated based on: (a) characterization procedure established for patient risk estimation in each facility, (b) generic unitary neutron spectrum and (c) generic MC map distribution of the fast component. [1] Radiat. Meas (2010) 45: 1391 – 1397; [2] Phys. Med. Biol (2012) 5 7:6167–6191; [3] Med. Phys (2015) 42

INCLUDING INTANGIBLE ASSETS IN RATES TO ESTIMATE THE RISK OF BANKRUPTCY

Directory of Open Access Journals (Sweden)

Eugenia IANCU

2017-12-01

Full Text Available The purpose of this paper is to show that an economic entity’s intangible assets play an important role in predicting the risk of bankruptcy of the company and at the same time in its evolution. Based on benchmarking and on appeal to the experience and intuition of available human expert it can be shaped a credible model and, based on this model can be projected the future course of a business organization. Among other issues, we note that the intangible assets of a company can and should be entered into the equation for estimating the risk of bankruptcy whether it avails or not to artificial intelligence (AI techniques to solve this problem (values lead to bankruptcy and the graphics functions differ majorly when the analysis includes the Rhine rate which takes into account intangibles of firms. From the structure of the paper we can see that whatever the type of model used in predicting the risk of bankruptcy at either classic or using artificial intelligence techniques (AI a leading role in the evolution and the value of the company represents intangible.

Age- and Tumor Subtype-Specific Breast Cancer Risk Estimates for CHEK2*1100delC Carriers

DEFF Research Database (Denmark)

Schmidt, Marjanka K; Hogervorst, Frans; van Hien, Richard R

2016-01-01

PURPOSE: CHEK2*1100delC is a well-established breast cancer risk variant that is most prevalent in European populations; however, there are limited data on risk of breast cancer by age and tumor subtype, which limits its usefulness in breast cancer risk prediction. We aimed to generate tumor...... subtype- and age-specific risk estimates by using data from the Breast Cancer Association Consortium, including 44,777 patients with breast cancer and 42,997 controls from 33 studies genotyped for CHEK2*1100delC. PATIENTS AND METHODS: CHEK2*1100delC genotyping was mostly done by a custom Taqman assay....... Breast cancer odds ratios (ORs) for CHEK2*1100delC carriers versus noncarriers were estimated by using logistic regression and adjusted for study (categorical) and age. Main analyses included patients with invasive breast cancer from population- and hospital-based studies. RESULTS: Proportions...

The estimated risk for coronary heart disease and prevalence of dyslipidemia among workers of information technology industries in Taiwan.

Science.gov (United States)

Yang, Shao-Chi; Chien, Kuo-Liong; Tsai, Wei-I; Ho, Yi-Lwun; Chen, Ming-Fong

2011-03-18

Individuals working in information technology (IT) industries suffer from high work stress, possibly causing adverse impacts on their health. However, studies of cardiovascular risk factors among these workers are lacking. The aims of this study were to evaluate the estimated risk for coronary heart disease (CHD) and prevalence of dyslipidemia among IT workers. A total of 941 employees from 11 IT companies were enrolled and the anthropometrics and serum lipid profiles were measured. The 10-year risk for CHD was calculated based on the Framingham risk score. Compared with lipid profiles in a representative sample (n=6589), IT workers had a significantly higher prevalence of obesity, hypercholesterolemia, low level of HDL-C, and high level of LDL-C in each age group. Their overall estimated 10-year risk for CHD was higher than the average risk of an age- and gender-matched population (2.91% vs. 2.79%, p=0.027). Working for more than 10h/day was associated with a higher estimated CHD risk (3.62% vs. 2.54%, p<0.01). A higher prevalence of hyperlipidemia was noted among IT workers. Their estimated 10-year CHD risk was also higher than average. More aggressive interventions to reduce the risk of CHD in this population are needed. Copyright © 2010 Elsevier B.V. All rights reserved.

Estimation of population dose and risk to holding assistants from veterinary X-ray examination in Japan

International Nuclear Information System (INIS)

Hashizume, Tadashi; Suganuma, Tunenori; Shida, Takuo

1989-01-01

For the estimation of the population doses and risks of stochastic effects to assistants who hold animals during veterinary X-ray examination, a random survey of hospitals and clinics was carried out concerning age distribution of such assistants by groups of facilities. The average organ and tissue dose per examination was evaluated from the experimental data using mean technical factors such as X-ray tube voltage, tube current and field size based on the results of a nationwide survey. The population doses to the assistants were calculated to be about 14 nSv per person per year for the genetically significant dose, 3.5 nSv per person per year for per caput mean marrow dose, 3.3 nSv for the leukemia significant dose and 4.5 nSv for the malignant significant dose, respectively. The total risk of stochastic effects to the Japanese population from holding assistants was estimated using population data and it was estimated to be less than one person per year, but the cancer risks to a number of the assistants were estimated to be more than 4 x 10 -5 . (author)

Dose-response relationships and risk estimates for the induction of cancer due to low doses of low-LET radiation

International Nuclear Information System (INIS)

Elaguppillai, V.

1981-01-01

Risk estimates for radiation-induced cancer at low doses can be obtained only by extrapolation from the known effects at high doses and high dose rates, using a suitable dose-response model. The applicability of three different models, linear, sublinear and supralinear, are discussed in this paper. Several experimental studies tend to favour a sublinear dose-response model (linear-quadratic model) for low-LET radiation. However, human epidemiological studies do not exclude any of the dose-response relationships. The risk estimates based on linear and linear quadratic dose-response models are compared and it is concluded that, for low-LET radiation, the linear dose-response model would probably over-estimate the actual risk of cancer by a factor of two or more. (author)

Recent advances in the estimation of genetic risks of exposure to ionizing radiation

International Nuclear Information System (INIS)

Sankaranarayanan, K.

2002-01-01

This paper reviews the major advances that have occurred during the last few years in the estimation of genetic risks of exposure of human populations to ionizing radiation. Among these are: (i) an upward revision of the estimates of the baseline frequencies of Mendelian diseases (from 1.25% to 2.4%); (ii) the conceptual change to the use of a doubling dose based on human data on spontaneous mutation rates and mouse data on induced mutation rates (from the one based entirely on mouse data on spontaneous and induced mutation rates, which was the case thus far); (iii) the fuller development of the concept of mutation component (MC) and its application to predict the responsiveness of Mendelian and chronic multi factorial diseases to induced mutations; (iv) the introduction of the concept that the major adverse effects of radiation exposure of human germ cells are likely to be manifest as multi-system developmental abnormalities and (v) the introduction of concept of potential recoverability correction factor (PRCF) to bridge the gap between induced mutations studied in mice and the risk of genetic disease in humans are reviewed

Simple estimate of the influence of competitive inhibition on PBTK based risk assessment

DEFF Research Database (Denmark)

Reffstrup, Trine Klein; Petersen, Annette; Nielsen, Elsa

2014-01-01

Background: In recent years, increased focus has been on the development of methods for assessing health risks caused by exposure to mixtures of chemicals from food and the environment. It has been recommended by international bodies to consider physiologically based toxicokinetic (PBTK) modellin...

The Finnish Diabetes Risk Score is associated with insulin resistance but not reduced beta-cell function, by classical and model-based estimates

NARCIS (Netherlands)

Brodovicz, K.G.; Dekker, J.M.; Rijkelijkhuizen, J.M.; Rhodes, T.; Mari, A.; Alssema, M.J.; Nijpels, G.; Williams-Herman, D.E.; Girman, C.J.

2011-01-01

Aims The Finnish Diabetes Risk Score (FINDRISC) is widely used for risk stratification in Type2 diabetes prevention programmes. Estimates of β-cell function vary widely in people without diabetes and reduced insulin secretion has been described in people at risk for diabetes. The aim of this

Comparison of Prevalence- and Smoking Impact Ratio-Based Methods of Estimating Smoking-Attributable Fractions of Deaths

Directory of Open Access Journals (Sweden)

Kyoung Ae Kong

2016-04-01

Full Text Available Background: Smoking is a major modifiable risk factor for premature mortality. Estimating the smoking-attributable burden is important for public health policy. Typically, prevalence- or smoking impact ratio (SIR-based methods are used to derive estimates, but there is controversy over which method is more appropriate for country-specific estimates. We compared smoking-attributable fractions (SAFs of deaths estimated by these two methods. Methods: To estimate SAFs in 2012, we used several different prevalence-based approaches using no lag and 10- and 20-year lags. For the SIR-based method, we obtained lung cancer mortality rates from the Korean Cancer Prevention Study (KCPS and from the United States-based Cancer Prevention Study-II (CPS-II. The relative risks for the diseases associated with smoking were also obtained from these cohort studies. Results: For males, SAFs obtained using KCPS-derived SIRs were similar to those obtained using prevalence-based methods. For females, SAFs obtained using KCPS-derived SIRs were markedly greater than all prevalence-based SAFs. Differences in prevalence-based SAFs by time-lag period were minimal among males, but SAFs obtained using longer-lagged prevalence periods were significantly larger among females. SAFs obtained using CPS-II-based SIRs were lower than KCPS-based SAFs by >15 percentage points for most diseases, with the exceptions of lung cancer and chronic obstructive pulmonary disease. Conclusions: SAFs obtained using prevalence- and SIR-based methods were similar for males. However, neither prevalence-based nor SIR-based methods resulted in precise SAFs among females. The characteristics of the study population should be carefully considered when choosing a method to estimate SAF.

Operational Risk Measurement of Chinese Commercial Banks Based on Extreme Value Theory

Science.gov (United States)

Song, Jiashan; Li, Yong; Ji, Feng; Peng, Cheng

The financial institutions and supervision institutions have all agreed on strengthening the measurement and management of operational risks. This paper attempts to build a model on the loss of operational risks basing on Peak Over Threshold model, emphasizing on weighted least square, which improved Hill’s estimation method, while discussing the situation of small sample, and fix the sample threshold more objectively basing on the media-published data of primary banks loss on operational risk from 1994 to 2007.

Russia-specific relative risks and their effects on the estimated alcohol-attributable burden of disease.

Science.gov (United States)

Shield, Kevin D; Rehm, Jürgen

2015-05-10

Alcohol consumption is a major risk factor for the burden of disease globally. This burden is estimated using Relative Risk (RR) functions for alcohol from meta-analyses that use data from all countries; however, for Russia and surrounding countries, country-specific risk data may need to be used. The objective of this paper is to compare the estimated burden of alcohol consumption calculated using Russia-specific alcohol RRs with the estimated burden of alcohol consumption calculated using alcohol RRs from meta-analyses. Data for 2012 on drinking indicators were calculated based on the Global Information System on Alcohol and Health. Data for 2012 on mortality, Years of Life Lost, Years Lived with Disability, and Disability-Adjusted Life Years (DALYs) lost by cause were obtained by country from the World Health Organization. Alcohol Population-Attributable Fractions (PAFs) were calculated based on a risk modelling methodology from Russia. These PAFs were compared to PAFs calculated using methods applied for all other countries. The 95% Uncertainty Intervals (UIs) for the alcohol PAFs were calculated using a Monte Carlo-like method. Using Russia-specific alcohol RR functions, in Russia in 2012 alcohol caused an estimated 231,900 deaths (95% UI: 185,600 to 278,200) (70,800 deaths among women and 161,100 deaths among men) and 13,295,000 DALYs lost (95% UI: 11,242,000 to 15,348,000) (3,670,000 DALYs lost among women and 9,625,000 DALYs lost among men) among people 0 to 64 years of age. This compares to an estimated 165,600 deaths (95% UI: 97,200 to 228,100) (29,700 deaths among women and 135,900 deaths among men) and 10,623,000 DALYs lost (95% UI: 7,265,000 to 13,754,000) (1,783,000 DALYs lost among women and 8,840,000 DALYs lost among men) among people 0 to 64 years of age caused by alcohol when non-Russia-specific alcohol RRs were used. Results indicate that if the Russia-specific RRs are used when estimating the health burden attributable to alcohol consumption in

Model Selection and Risk Estimation with Applications to Nonlinear Ordinary Differential Equation Systems

DEFF Research Database (Denmark)

Mikkelsen, Frederik Vissing

eective computational tools for estimating unknown structures in dynamical systems, such as gene regulatory networks, which may be used to predict downstream eects of interventions in the system. A recommended algorithm based on the computational tools is presented and thoroughly tested in various......Broadly speaking, this thesis is devoted to model selection applied to ordinary dierential equations and risk estimation under model selection. A model selection framework was developed for modelling time course data by ordinary dierential equations. The framework is accompanied by the R software...... package, episode. This package incorporates a collection of sparsity inducing penalties into two types of loss functions: a squared loss function relying on numerically solving the equations and an approximate loss function based on inverse collocation methods. The goal of this framework is to provide...

Five-year risk of HIV diagnosis subsequent to 147 hospital-based indicator diseases

DEFF Research Database (Denmark)

Omland, Lars Haukali; Legarth, Rebecca; Ahlström, Magnus Glindvad

2016-01-01

. To estimate the risk of HIV diagnosis in the general population without any indicator diseases, we calculated the FYRHD starting at age 25, 35, 45, and 55 years. RESULTS: The risk in the male general population was substantially higher than the female general population, and the risk was lower in the older...... with relevant indicator diseases are nonexistent. METHODS: In a nationwide population-based cohort study encompassing all Danish residents aged 20-60 years during 1994-2013, we estimated the 5-year risk of an HIV diagnosis (FYRHD) after a first-time diagnosis of 147 prespecified potential indicator diseases...

Female Genital Mutilation/Cutting in the United States: Updated Estimates of Women and Girls at Risk, 2012.

Science.gov (United States)

Goldberg, Howard; Stupp, Paul; Okoroh, Ekwutosi; Besera, Ghenet; Goodman, David; Danel, Isabella

2016-01-01

In 1996, the U.S. Congress passed legislation making female genital mutilation/cutting (FGM/C) illegal in the United States. CDC published the first estimates of the number of women and girls at risk for FGM/C in 1997. Since 2012, various constituencies have again raised concerns about the practice in the United States. We updated an earlier estimate of the number of women and girls in the United States who were at risk for FGM/C or its consequences. We estimated the number of women and girls who were at risk for undergoing FGM/C or its consequences in 2012 by applying country-specific prevalence of FGM/C to the estimated number of women and girls living in the United States who were born in that country or who lived with a parent born in that country. Approximately 513,000 women and girls in the United States were at risk for FGM/C or its consequences in 2012, which was more than three times higher than the earlier estimate, based on 1990 data. The increase in the number of women and girls younger than 18 years of age at risk for FGM/C was more than four times that of previous estimates. The estimated increase was wholly a result of rapid growth in the number of immigrants from FGM/C-practicing countries living in the United States and not from increases in FGM/C prevalence in those countries. Scientifically valid information regarding whether women or their daughters have actually undergone FGM/C and related information that can contribute to efforts to prevent the practice in the United States and provide needed health services to women who have undergone FGM/C are needed.

A study on the estimation method of nuclear accident risk cost

International Nuclear Information System (INIS)

Matsuo, Yuji

2016-01-01

The methodology of estimating nuclear accident risk cost, as a part of nuclear power generation cost, has hardly been established due mainly to the extremely wide range of the estimation of the accident frequency. This study estimates the expected nuclear accident frequency for Japan, making use of the method of Bayesian statistics, which exploits both the information obtained by Probabilistic Risk Assessment (PRA) and the observed historical accident frequencies. Using the PRA estimation of the Containment Failure Frequency (CFF) for Tomari nuclear power plant unit 3 of Hokkaido Electric Power Company (average: 2.1 x 10 -4 , 95th percentile: 7.7 x 10 -4 ) and the actual large-scale accident frequency (once in 1,460 reactor-years), the posterior CFF was estimated at 3.8 x 10 -4 . This study also took into account the 'external' factor causing unexpected nuclear accidents, concluding that such factor could result in higher CFF estimations, especially with larger observed accident numbers. (author)

Including pathogen risk in life cycle assessment of wastewater management. 1. Estimating the burden of disease associated with pathogens.

Science.gov (United States)

Harder, Robin; Heimersson, Sara; Svanström, Magdalena; Peters, Gregory M

2014-08-19

The environmental performance of wastewater and sewage sludge management is commonly assessed using life cycle assessment (LCA), whereas pathogen risk is evaluated with quantitative microbial risk assessment (QMRA). This study explored the application of QMRA methodology with intent to include pathogen risk in LCA and facilitate a comparison with other potential impacts on human health considered in LCA. Pathogen risk was estimated for a model wastewater treatment system (WWTS) located in an industrialized country and consisting of primary, secondary, and tertiary wastewater treatment, anaerobic sludge digestion, and land application of sewage sludge. The estimation was based on eight previous QMRA studies as well as parameter values taken from the literature. A total pathogen risk (expressed as burden of disease) on the order of 0.2-9 disability-adjusted life years (DALY) per year of operation was estimated for the model WWTS serving 28,600 persons and for the pathogens and exposure pathways included in this study. The comparison of pathogen risk with other potential impacts on human health considered in LCA is detailed in part 2 of this article series.

Seismic Risk of the Base Isolation System Protected by the Hard Stop

International Nuclear Information System (INIS)

Kim, Jung Han; Choi, In-Kil; Kim, Min Kyu

2015-01-01

The concept of base isolation is to permit the deformation of isolator for absorbing seismic input wave from the ground. In a nuclear power plant design, allowable shear deformation of isolators should be enough to absorb the displacement response by extended design basis (EDB) ground motions. However isolators cannot resist over its displacement capacity. So, the clearance of hard stop (CHS) needs to be set between the response of base isolation system excited by the EDB ground motion and the displacement capacity of isolators. The isolation system must survive with high confidence in any seismic accident because it is a non-redundant system. Therefore, the CHS should be determined carefully based on the failure risk of base isolation system considering the uncertainties of earthquake responses and isolator capacities. In this research, the fragility curve of isolation system and its failure risk were estimated. The procedure to calculate the acceleration based fragility curve of the isolation system was developed. The fragility curve and failure risk for example case was estimated and its result was compared with different isolator capacities

Seismic Risk of the Base Isolation System Protected by the Hard Stop

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Han; Choi, In-Kil; Kim, Min Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2015-10-15

The concept of base isolation is to permit the deformation of isolator for absorbing seismic input wave from the ground. In a nuclear power plant design, allowable shear deformation of isolators should be enough to absorb the displacement response by extended design basis (EDB) ground motions. However isolators cannot resist over its displacement capacity. So, the clearance of hard stop (CHS) needs to be set between the response of base isolation system excited by the EDB ground motion and the displacement capacity of isolators. The isolation system must survive with high confidence in any seismic accident because it is a non-redundant system. Therefore, the CHS should be determined carefully based on the failure risk of base isolation system considering the uncertainties of earthquake responses and isolator capacities. In this research, the fragility curve of isolation system and its failure risk were estimated. The procedure to calculate the acceleration based fragility curve of the isolation system was developed. The fragility curve and failure risk for example case was estimated and its result was compared with different isolator capacities.

Estimating Bird / Aircraft Collision Probabilities and Risk Utilizing Spatial Poisson Processes

Science.gov (United States)

2012-06-10

ESTIMATING BIRD/AIRCRAFT COLLISION PROBABILITIES AND RISK UTILIZING SPATIAL POISSON PROCESSES GRADUATE...AND RISK UTILIZING SPATIAL POISSON PROCESSES GRADUATE RESEARCH PAPER Presented to the Faculty Department of Operational Sciences...COLLISION PROBABILITIES AND RISK UTILIZING SPATIAL POISSON PROCESSES Brady J. Vaira, BS, MS Major, USAF Approved

Estimating mortality risk reduction and economic benefits from controlling ozone air pollution

National Research Council Canada - National Science Library

Committee on Estimating Mortality Risk Reduction Benefits from Decreasing Tropospheric Ozone Exposure

2008-01-01

... in life expectancy, and to assess methods for estimating the monetary value of the reduced risk of premature death and increased life expectancy in the context of health-benefits analysis. Estimating Mortality Risk Reduction and Economic Benefits from Controlling Ozone Air Pollution details the committee's findings and posits several recommendations to address these issues.

Estimating twin concordance for bivariate competing risks twin data

DEFF Research Database (Denmark)

Scheike, Thomas; Holst, Klaus K.; Hjelmborg, Jacob B.

2014-01-01

For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experience...... events with the competing risk death. We thus aim to quantify the degree of dependence through the casewise concordance function and show a significant genetic component...... the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence...... over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer...

Cost-effectiveness and harm-benefit analyses of risk-based screening strategies for breast cancer.

Directory of Open Access Journals (Sweden)

Ester Vilaprinyo

Full Text Available The one-size-fits-all paradigm in organized screening of breast cancer is shifting towards a personalized approach. The present study has two objectives: 1 To perform an economic evaluation and to assess the harm-benefit ratios of screening strategies that vary in their intensity and interval ages based on breast cancer risk; and 2 To estimate the gain in terms of cost and harm reductions using risk-based screening with respect to the usual practice. We used a probabilistic model and input data from Spanish population registries and screening programs, as well as from clinical studies, to estimate the benefit, harm, and costs over time of 2,624 screening strategies, uniform or risk-based. We defined four risk groups, low, moderate-low, moderate-high and high, based on breast density, family history of breast cancer and personal history of breast biopsy. The risk-based strategies were obtained combining the exam periodicity (annual, biennial, triennial and quinquennial, the starting ages (40, 45 and 50 years and the ending ages (69 and 74 years in the four risk groups. Incremental cost-effectiveness and harm-benefit ratios were used to select the optimal strategies. Compared to risk-based strategies, the uniform ones result in a much lower benefit for a specific cost. Reductions close to 10% in costs and higher than 20% in false-positive results and overdiagnosed cases were obtained for risk-based strategies. Optimal screening is characterized by quinquennial or triennial periodicities for the low or moderate risk-groups and annual periodicity for the high-risk group. Risk-based strategies can reduce harm and costs. It is necessary to develop accurate measures of individual risk and to work on how to implement risk-based screening strategies.

Task-based dermal exposure models for regulatory risk assessment

NARCIS (Netherlands)

Warren, N.D.; Marquart, H.; Christopher, Y.; Laitinen, J.; Hemmen, J.J. van

2006-01-01

The regulatory risk assessment of chemicals requires the estimation of occupational dermal exposure. Until recently, the models used were either based on limited data or were specific to a particular class of chemical or application. The EU project RISKOFDERM has gathered a considerable number of

Topics on the problem of genetic risk estimates health research foundation

International Nuclear Information System (INIS)

Nakai, Sayaka

1995-01-01

Reanalysis of the data on untoward pregnancy outcome (UPO) for atomic bomb survivors was undertaken based on following current results of cytogenetic studies obtained in Japan: 1) Human gametes were very sensitive to the production of chromosome aberrations either spontaneous or radiation induced origin. 2) The shape of dose-response relations against to radiations showed humped curve at relatively low dose-range below 3Gy. 3) Existence of very severe selection to the embryo having chromosome aberrations represented during fetus development before the birth. It was concluded that 1) Humped dose-response model was more fitted than the linear dose model. 2) Regression coefficient for the slope of UPO at low doses derived from humped dose model was about 6 times more higher than the previous value based on linear model. 3) Risk factor for genetic detriment in term of UPO was estimated as 0.015/Gy under the condition exposed radiation below 1Gy. 4) It was difficult to find out positive evidence supporting the view which is given by Neel et al. that present estimates of doubling dose based on mouse data thought to be underestimated figure. (author)

Bayesian parameter estimation in probabilistic risk assessment

International Nuclear Information System (INIS)

Siu, Nathan O.; Kelly, Dana L.

1998-01-01

Bayesian statistical methods are widely used in probabilistic risk assessment (PRA) because of their ability to provide useful estimates of model parameters when data are sparse and because the subjective probability framework, from which these methods are derived, is a natural framework to address the decision problems motivating PRA. This paper presents a tutorial on Bayesian parameter estimation especially relevant to PRA. It summarizes the philosophy behind these methods, approaches for constructing likelihood functions and prior distributions, some simple but realistic examples, and a variety of cautions and lessons regarding practical applications. References are also provided for more in-depth coverage of various topics

Estimation of effective dose and lifetime attributable risk from multiple head CT scans in ventriculoperitoneal shunted children

International Nuclear Information System (INIS)

Aw-Zoretic, J.; Seth, D.; Katzman, G.; Sammet, S.

2014-01-01

Purpose: The purpose of this review is to determine the averaged effective dose and lifetime attributable risk factor from multiple head computed tomography (CT) dose data on children with ventriculoperitoneal shunts (VPS). Method and materials: A total of 422 paediatric head CT exams were found between October 2008 and January 2011 and retrospectively reviewed. The CT dose data was weighted with the latest IRCP 103 conversion factor to obtain the effective dose per study and the averaged effective dose was calculated. Estimates of the lifetime attributable risk were also calculated from the averaged effective dose using a conversion factor from the latest BEIR VII report. Results: Our study found the highest effective doses in neonates and the lowest effective doses were observed in the 10–18 years age group. We estimated a 0.007% potential increase risk in neonates and 0.001% potential increased risk in teenagers over the base risk. Conclusion: Multiple head CTs in children equates to a slight potential increase risk in lifetime attributable risk over the baseline risk for cancer, slightly higher in neonates relative to teenagers. The potential risks versus clinical benefit must be assessed

Estimation of sport fish harvest for risk and hazard assessment of environmental contaminants

International Nuclear Information System (INIS)

Poston, T.M.; Strenge, D.L.

1989-01-01

Consumption of contaminated fish flesh can be a significant route of human exposure to hazardous chemicals. Estimation of exposure resulting from the consumption of fish requires knowledge of fish consumption and contaminant levels in the edible portion of fish. Realistic figures of sport fish harvest are needed to estimate consumption. Estimates of freshwater sport fish harvest were developed from a review of 72 articles and reports. Descriptive statistics based on fishing pressure were derived from harvest data for four distinct groups of freshwater sport fish in three water types: streams, lakes, and reservoirs. Regression equations were developed to relate harvest to surface area fished where data bases were sufficiently large. Other aspects of estimating human exposure to contaminants in fish flesh that are discussed include use of bioaccumulation factors for trace metals and organic compounds. Using the bioaccumulation factor and the concentration of contaminants in water as variables in the exposure equation may also lead to less precise estimates of tissue concentration. For instance, muscle levels of contaminants may not increase proportionately with increases in water concentrations, leading to overestimation of risk. In addition, estimates of water concentration may be variable or expressed in a manner that does not truly represent biological availability of the contaminant. These factors are discussed. 45 refs., 1 fig., 7 tabs

12 CFR Appendix A to Part 208 - Capital Adequacy Guidelines for State Member Banks: Risk-Based Measure

Science.gov (United States)

2010-01-01

... reverse within the year. Such projections should include the estimated effect of tax-planning strategies... charges for certain market risks into the risk-based capital ratio. When calculating their risk-based... supplemental rules to determine qualifying and excess capital, calculate risk-weighted assets, calculate market...

The Boehringer Ingelheim employee study (Part 2): 10-year cardiovascular diseases risk estimation.

Science.gov (United States)

Kempf, K; Martin, S; Döhring, C; Dugi, K; Haastert, B; Schneider, M

2016-10-01

Cardiovascular disease (CVD) may cause an economic burden to companies, but CVD risk estimations specific to working populations are lacking. To estimate the 10-year CVD risk in the Boehringer Ingelheim (BI) employee cohort and analyse the potential effect of hypothetical risk reduction interventions. We estimated CVD risk using the Framingham (FRS), PROCAM (PRS) and Reynolds (RRS) risk scores, using cross-sectional baseline data on BI Pharma employees collected from 2005 to 2011. Results were compared using Fisher's exact and Wilcoxon tests. The predictive ability of the score estimates was assessed using receiver-operating characteristics analyses. Among the 4005 study subjects, we estimated 10-year CVD risks of 35% (FRS), 9% (PRS) and 6% (RRS) for men and 10% (FRS), 4% (PRS) and 1% (RRS) for women. One hundred and thirty-four (6%) men and 111 (6%) women employees had current CVD. The best predictors of prevalent CVD were the FRS and the RRS for men [area-under-the-curve 0.62 (0.57-0.67) for both]. A hypothetical intervention that would improve systolic blood pressure, HbA1c (for diabetes), C-reactive protein, triglycerides and total and high-density lipoprotein cholesterol by 10% each would potentially reduce expected CVD cases by 36-41% in men and 30-45% in women, and if smoking cessation is incorporated, by 39-45% and 30-55%, respectively, depending on the pre-intervention risk score. There was a substantial risk of developing CVD in this working cohort. Occupational health programmes with lifestyle interventions for high-risk individuals may be an effective risk reduction measure. © The Author 2016. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Using speeding detections and numbers of fatalities to estimate relative risk of a fatality for motorcyclists and car drivers.

Science.gov (United States)

Huggins, Richard

2013-10-01

Precise estimation of the relative risk of motorcyclists being involved in a fatal accident compared to car drivers is difficult. Simple estimates based on the proportions of licenced drivers or riders that are killed in a fatal accident are biased as they do not take into account the exposure to risk. However, exposure is difficult to quantify. Here we adapt the ideas behind the well known induced exposure methods and use available summary data on speeding detections and fatalities for motorcycle riders and car drivers to estimate the relative risk of a fatality for motorcyclists compared to car drivers under mild assumptions. The method is applied to data on motorcycle riders and car drivers in Victoria, Australia in 2010 and a small simulation study is conducted. Copyright © 2013 Elsevier Ltd. All rights reserved.

We can do better than effective dose for estimating or comparing low-dose radiation risks

International Nuclear Information System (INIS)

Brenner, D.J.

2012-01-01

The effective dose concept was designed to compare the generic risks of exposure to different radiation fields. More commonly these days, it is used to estimate or compare radiation-induced cancer risks. For various reasons, effective dose represents flawed science: for instance, the tissue-specific weighting factors used to calculate effective dose are a subjective mix of different endpoints; and the marked and differing age and gender dependencies for different health detriment endpoints are not taken into account. This paper suggests that effective dose could be replaced with a new quantity, ‘effective risk’, which, like effective dose, is a weighted sum of equivalent doses to different tissues. Unlike effective dose, where the tissue-dependent weighting factors are a set of generic, subjective committee-defined numbers, the weighting factors for effective risk are simply evaluated tissue-specific lifetime cancer risks per unit equivalent dose. Effective risk, which has the potential to be age and gender specific if desired, would perform the same comparative role as effective dose, be just as easy to estimate, be less prone to misuse, be more directly understandable, and would be based on solid science. An added major advantage is that it gives the users some feel for the actual numerical values of the radiation risks they are trying to control.

RiD: A New Approach to Estimate the Insolvency Risk

Directory of Open Access Journals (Sweden)

Marco Aurélio dos Santos Sanfins

2014-10-01

Full Text Available Given the recent international crises and the increasing number of defaults, several researchers have attempted to develop metrics that calculate the probability of insolvency with higher accuracy. The approaches commonly used, however, do not consider the credit risk nor the severity of the distance between receivables and obligations among different periods. In this paper we mathematically present an approach that allow us to estimate the insolvency risk by considering not only future receivables and obligations, but the severity of the distance between them and the quality of the respective receivables. Using Monte Carlo simulations and hypothetical examples, we show that our metric is able to estimate the insolvency risk with high accuracy. Moreover, our results suggest that in the absence of a smooth distribution between receivables and obligations, there is a non-null insolvency risk even when the present value of receivables is larger than the present value of the obligations.

Liver stiffness value-based risk estimation of late recurrence after curative resection of hepatocellular carcinoma: development and validation of a predictive model.

Directory of Open Access Journals (Sweden)

Kyu Sik Jung

Full Text Available Preoperative liver stiffness (LS measurement using transient elastography (TE is useful for predicting late recurrence after curative resection of hepatocellular carcinoma (HCC. We developed and validated a novel LS value-based predictive model for late recurrence of HCC.Patients who were due to undergo curative resection of HCC between August 2006 and January 2010 were prospectively enrolled and TE was performed prior to operations by study protocol. The predictive model of late recurrence was constructed based on a multiple logistic regression model. Discrimination and calibration were used to validate the model.Among a total of 139 patients who were finally analyzed, late recurrence occurred in 44 patients, with a median follow-up of 24.5 months (range, 12.4-68.1. We developed a predictive model for late recurrence of HCC using LS value, activity grade II-III, presence of multiple tumors, and indocyanine green retention rate at 15 min (ICG R15, which showed fairly good discrimination capability with an area under the receiver operating characteristic curve (AUROC of 0.724 (95% confidence intervals [CIs], 0.632-0.816. In the validation, using a bootstrap method to assess discrimination, the AUROC remained largely unchanged between iterations, with an average AUROC of 0.722 (95% CIs, 0.718-0.724. When we plotted a calibration chart for predicted and observed risk of late recurrence, the predicted risk of late recurrence correlated well with observed risk, with a correlation coefficient of 0.873 (P<0.001.A simple LS value-based predictive model could estimate the risk of late recurrence in patients who underwent curative resection of HCC.

Estimated risk from exposure to radon decay products in US homes

International Nuclear Information System (INIS)

Nero, A.V. Jr.

1986-05-01

Recent analyses now permit direct estimation of the risks of lung cancer from radon decay products in US homes. Analysis of data from indoor monitoring in single-family homes yields a tentative frequency distribution of annual-average 222 Rn concentrations averaging 55 Bq m -3 and having 2% of homes exceeding 300 Bq m -3 . Application of the results of occupational epidemiological studies, either directly or using recent advances in lung dosimetry, to indoor exposures suggests that the average indoor concentration entails a lifetime risk of lung cancer of 0.3% or about 10% of the total risk of lung cancer. The risk to individuals occupying the homes with 300 Bq m -3 or more for their lifetimes is estimated to exceed 2%, with risks from the homes with thousands of Bq m -3 correspondingly higher, even exceeding the total risk of premature death due to cigarette smoking. The potential for such average and high-level risks in ordinary homes forces development of a new perspective on environmental exposures

Multifactorial risk assessment for survival of abutments of removable partial dentures based on practice-based longitudinal study.

Science.gov (United States)

Tada, Sayaka; Ikebe, Kazunori; Matsuda, Ken-Ichi; Maeda, Yoshinobu

2013-12-01

Predicting the tooth survival is such a great challenge for evidence-based dentistry. To prevent further tooth loss of partially edentulous patients, estimation of individualized risk and benefit for each residual tooth is important to the clinical decision-making. While there are several reports indicating a risk of losing the abutment teeth of RPDs, there are no existing reports exploring the cause of abutment loss by multifactorial analysis. The aim of this practice-based longitudinal study was to determine the prognostic factors affecting the survival period of RPD abutments using a multifactorial risk assessment. One hundred and forty-seven patients had been previously provided with a total of 236 new RPDs at the Osaka University Dental Hospital; the 856 abutments for these RPDs were analyzed. Survival of abutment teeth was estimated using the Kaplan-Meier method. Multivariate analysis was conducted by Cox's proportional hazard modelling. The 5-year survival rates were 86.6% for direct abutments and 93.1% for indirect abutments, compared with 95.8% survival in non-abutment teeth. The multivariate analysis showed that abutment survival was significantly associated with crown-root ratio (hazard ratio (HR): 3.13), root canal treatment (HR: 2.93), pocket depth (HR: 2.51), type of abutments (HR: 2.19) and occlusal support (HR: 1.90). From this practice-based longitudinal study, we concluded that RPD abutment teeth are more likely to be lost than other residual teeth. From the multifactorial risk factor assessment, several prognostic factors, such as occlusal support, crown-root ratio, root canal treatment, and pocket depth were suggested. These results could be used to estimate the individualized risk for the residual teeth, to predict the prognosis of RPD abutments and to facilitate an evidence-based clinical decision making. Copyright © 2013 Elsevier Ltd. All rights reserved.

SU-F-T-244: Radiotherapy Risk Estimation Based On Expert Group Survey

International Nuclear Information System (INIS)

Koo, J; Yoon, M; Chung, W; Chung, M; Kim, D

2016-01-01

Purpose: To evaluate the reliability of RPN (Risk Priority Number) decided by expert group and to provide preliminary data for adapting FMEA in Korea. Methods: 1163 Incidents reported in ROSIS for 11 years were used as a real data to be compared with, and were categorized into 146 items. The questionnaire was composed of the 146 items and respondents had to valuate ‘occurrence (O)’, ‘severity (S)’, ‘detectability (D)’ of each item on a scale from 1 to 10 according to the proposed AAPM TG-100 rating scales. 19 medical physicists from 19 different organizations in Korea had participated in the survey. Because the number of ROSIS items was not evenly spread enough to be classified into 10 grades, 1–5 scale was chosen instead of 1–10 and survey result was also fit to 5 grades to compare. Results: The average O,S,D were 1.77, 3.50, 2.13, respectively and the item which had the highest RPN(32) was ‘patient movement during treatment’ in the survey. When comparing items ranked in the top 10 of each survey(O) and ROSIS database, two items were duplicated and ‘Simulation’ and ’Treatment’ were the most frequently ranked RT process in top 10 of survey and ROSIS each. The Chronbach α of each RT process were ranged from 0.74 to 0.99 and p-value was <0.001. When comparing O*D, the average difference was 1.4. Conclusion: This work indicates the deviation between actual risk and expectation. Considering that the respondents were Korean and ROSIS is mainly composed of incidents happened in European countries and some of the top 10 items of ROSIS cannot be applied in radiotherapy procedure in Korea, the deviation could have been came from procedural difference. Moreover, if expert group was consisted of experts from various parts, expectation might have been more accurate. Therefore, further research on radiotherapy risk estimation is needed.

SU-F-T-244: Radiotherapy Risk Estimation Based On Expert Group Survey

Energy Technology Data Exchange (ETDEWEB)

Koo, J; Yoon, M [Korea University, Seoul (Korea, Republic of); Chung, W; Chung, M; Kim, D [Kyung Hee University Hospital at Gangdong, Gangdong-gu, Seoul (Korea, Republic of)

2016-06-15

Purpose: To evaluate the reliability of RPN (Risk Priority Number) decided by expert group and to provide preliminary data for adapting FMEA in Korea. Methods: 1163 Incidents reported in ROSIS for 11 years were used as a real data to be compared with, and were categorized into 146 items. The questionnaire was composed of the 146 items and respondents had to valuate ‘occurrence (O)’, ‘severity (S)’, ‘detectability (D)’ of each item on a scale from 1 to 10 according to the proposed AAPM TG-100 rating scales. 19 medical physicists from 19 different organizations in Korea had participated in the survey. Because the number of ROSIS items was not evenly spread enough to be classified into 10 grades, 1–5 scale was chosen instead of 1–10 and survey result was also fit to 5 grades to compare. Results: The average O,S,D were 1.77, 3.50, 2.13, respectively and the item which had the highest RPN(32) was ‘patient movement during treatment’ in the survey. When comparing items ranked in the top 10 of each survey(O) and ROSIS database, two items were duplicated and ‘Simulation’ and ’Treatment’ were the most frequently ranked RT process in top 10 of survey and ROSIS each. The Chronbach α of each RT process were ranged from 0.74 to 0.99 and p-value was <0.001. When comparing O*D, the average difference was 1.4. Conclusion: This work indicates the deviation between actual risk and expectation. Considering that the respondents were Korean and ROSIS is mainly composed of incidents happened in European countries and some of the top 10 items of ROSIS cannot be applied in radiotherapy procedure in Korea, the deviation could have been came from procedural difference. Moreover, if expert group was consisted of experts from various parts, expectation might have been more accurate. Therefore, further research on radiotherapy risk estimation is needed.

Risk-based safety indicators

International Nuclear Information System (INIS)

Szikszai, T.

1997-01-01

The presentation discusses the following issues: The objectives of the risk-based indicator programme. The characteristics of the risk-based indicators. The objectives of risk-based safety indicators - in monitoring safety; in PSA applications. What indicators? How to produce the risk based indicators? PSA requirements

NASA Software Cost Estimation Model: An Analogy Based Estimation Model

Science.gov (United States)

Hihn, Jairus; Juster, Leora; Menzies, Tim; Mathew, George; Johnson, James

2015-01-01

The cost estimation of software development activities is increasingly critical for large scale integrated projects such as those at DOD and NASA especially as the software systems become larger and more complex. As an example MSL (Mars Scientific Laboratory) developed at the Jet Propulsion Laboratory launched with over 2 million lines of code making it the largest robotic spacecraft ever flown (Based on the size of the software). Software development activities are also notorious for their cost growth, with NASA flight software averaging over 50% cost growth. All across the agency, estimators and analysts are increasingly being tasked to develop reliable cost estimates in support of program planning and execution. While there has been extensive work on improving parametric methods there is very little focus on the use of models based on analogy and clustering algorithms. In this paper we summarize our findings on effort/cost model estimation and model development based on ten years of software effort estimation research using data mining and machine learning methods to develop estimation models based on analogy and clustering. The NASA Software Cost Model performance is evaluated by comparing it to COCOMO II, linear regression, and K-­ nearest neighbor prediction model performance on the same data set.

Nuclear reactor component populations, reliability data bases, and their relationship to failure rate estimation and uncertainty analysis

International Nuclear Information System (INIS)

Martz, H.F.; Beckman, R.J.

1981-12-01

Probabilistic risk analyses are used to assess the risks inherent in the operation of existing and proposed nuclear power reactors. In performing such risk analyses the failure rates of various components which are used in a variety of reactor systems must be estimated. These failure rate estimates serve as input to fault trees and event trees used in the analyses. Component failure rate estimation is often based on relevant field failure data from different reliability data sources such as LERs, NPRDS, and the In-Plant Data Program. Various statistical data analysis and estimation methods have been proposed over the years to provide the required estimates of the component failure rates. This report discusses the basis and extent to which statistical methods can be used to obtain component failure rate estimates. The report is expository in nature and focuses on the general philosophical basis for such statistical methods. Various terms and concepts are defined and illustrated by means of numerous simple examples

Simulation-based seismic loss estimation of seaport transportation system

International Nuclear Information System (INIS)

Ung Jin Na; Shinozuka, Masanobu

2009-01-01

Seaport transportation system is one of the major lifeline systems in modern society and its reliable operation is crucial for the well-being of the public. However, past experiences showed that earthquake damage to port components can severely disrupt terminal operation, and thus negatively impact on the regional economy. The main purpose of this study is to provide a methodology for estimating the effects of the earthquake on the performance of the operation system of a container terminal in seaports. To evaluate the economic loss of damaged system, an analytical framework is developed by integrating simulation models for terminal operation and fragility curves of port components in the context of seismic risk analysis. For this purpose, computerized simulation model is developed and verified with actual terminal operation records. Based on the analytical procedure to assess the seismic performance of the terminal, system fragility curves are also developed. This simulation-based loss estimation methodology can be used not only for estimating the seismically induced revenue loss but also serve as a decision-making tool to select specific seismic retrofit technique on the basis of benefit-cost analysis

Space Radiation Cancer, Circulatory Disease and CNS Risks for Near Earth Asteroid and Mars Missions: Uncertainty Estimates for Never-Smokers

Science.gov (United States)

Cucinotta, Francis A.; Chappell, Lori J.; Wang, Minli; Kim, Myung-Hee

2011-01-01

The uncertainties in estimating the health risks from galactic cosmic rays (GCR) and solar particle events (SPE) are a major limitation to the length of space missions and the evaluation of potential risk mitigation approaches. NASA limits astronaut exposures to a 3% risk of exposure induced cancer death (REID), and protects against uncertainties in risks projections using an assessment of 95% confidence intervals after propagating the error from all model factors (environment and organ exposure, risk coefficients, dose-rate modifiers, and quality factors). Because there are potentially significant late mortality risks from diseases of the circulatory system and central nervous system (CNS) which are less well defined than cancer risks, the cancer REID limit is not necessarily conservative. In this report, we discuss estimates of lifetime risks from space radiation and new estimates of model uncertainties are described. The key updates to the NASA risk projection model are: 1) Revised values for low LET risk coefficients for tissue specific cancer incidence, with incidence rates transported to an average U.S. population to estimate the probability of Risk of Exposure Induced Cancer (REIC) and REID. 2) An analysis of smoking attributable cancer risks for never-smokers that shows significantly reduced lung cancer risk as well as overall cancer risks from radiation compared to risk estimated for the average U.S. population. 3) Derivation of track structure based quality functions depends on particle fluence, charge number, Z and kinetic energy, E. 4) The assignment of a smaller maximum in quality function for leukemia than for solid cancers. 5) The use of the ICRP tissue weights is shown to over-estimate cancer risks from SPEs by a factor of 2 or more. Summing cancer risks for each tissue is recommended as a more accurate approach to estimate SPE cancer risks. 6) Additional considerations on circulatory and CNS disease risks. Our analysis shows that an individual s

Does present use of cardiovascular medication reflect elevated cardiovascular risk scores estimated ten years ago? A population based longitudinal observational study

Directory of Open Access Journals (Sweden)

Straand Jørund

2011-03-01

Full Text Available Abstract Background It is desirable that those at highest risk of cardiovascular disease should have priority for preventive measures, eg. treatment with prescription drugs to modify their risk. We wanted to investigate to what extent present use of cardiovascular medication (CVM correlates with cardiovascular risk estimated by three different risk scores (Framingham, SCORE and NORRISK ten years ago. Methods Prospective logitudinal observational study of 20 252 participants in The Hordaland Health Study born 1950-57, not using CVM in 1997-99. Prescription data obtained from The Norwegian Prescription Database in 2008. Results 26% of men and 22% of women aged 51-58 years had started to use some CVM during the previous decade. As a group, persons using CVM scored significantly higher on the risk algorithms Framingham, SCORE and NORRISK compared to those not treated. 16-20% of men and 20-22% of women with risk scores below the high-risk thresholds for the three risk scores were treated with CVM, while 60-65% of men and 25-45% of women with scores above the high-risk thresholds received no treatment. Among women using CVM, only 2.2% (NORRISK, 4.4% (SCORE and 14.5% (Framingham had risk scores above the high-risk values. Low education, poor self-reported general health, muscular pains, mental distress (in females only and a family history of premature cardiovascular disease correlated with use of CVM. Elevated blood pressure was the single factor most strongly predictive of CVM treatment. Conclusion Prescription of CVM to middle-aged individuals by large seems to occur independently of estimated total cardiovascular risk, and this applies especially to females.

Burden of Severe Pneumonia, Pneumococcal Pneumonia and Pneumonia Deaths in Indian States: Modelling Based Estimates

Science.gov (United States)

Farooqui, Habib; Jit, Mark; Heymann, David L.; Zodpey, Sanjay

2015-01-01

The burden of severe pneumonia in terms of morbidity and mortality is unknown in India especially at sub-national level. In this context, we aimed to estimate the number of severe pneumonia episodes, pneumococcal pneumonia episodes and pneumonia deaths in children younger than 5 years in 2010. We adapted and parameterized a mathematical model based on the epidemiological concept of potential impact fraction developed CHERG for this analysis. The key parameters that determine the distribution of severe pneumonia episode across Indian states were state-specific under-5 population, state-specific prevalence of selected definite pneumonia risk factors and meta-estimates of relative risks for each of these risk factors. We applied the incidence estimates and attributable fraction of risk factors to population estimates for 2010 of each Indian state. We then estimated the number of pneumococcal pneumonia cases by applying the vaccine probe methodology to an existing trial. We estimated mortality due to severe pneumonia and pneumococcal pneumonia by combining incidence estimates with case fatality ratios from multi-centric hospital-based studies. Our results suggest that in 2010, 3.6 million (3.3–3.9 million) episodes of severe pneumonia and 0.35 million (0.31–0.40 million) all cause pneumonia deaths occurred in children younger than 5 years in India. The states that merit special mention include Uttar Pradesh where 18.1% children reside but contribute 24% of pneumonia cases and 26% pneumonia deaths, Bihar (11.3% children, 16% cases, 22% deaths) Madhya Pradesh (6.6% children, 9% cases, 12% deaths), and Rajasthan (6.6% children, 8% cases, 11% deaths). Further, we estimated that 0.56 million (0.49–0.64 million) severe episodes of pneumococcal pneumonia and 105 thousand (92–119 thousand) pneumococcal deaths occurred in India. The top contributors to India’s pneumococcal pneumonia burden were Uttar Pradesh, Bihar, Madhya Pradesh and Rajasthan in that order. Our

Burden of Severe Pneumonia, Pneumococcal Pneumonia and Pneumonia Deaths in Indian States: Modelling Based Estimates.

Science.gov (United States)

Farooqui, Habib; Jit, Mark; Heymann, David L; Zodpey, Sanjay

2015-01-01

The burden of severe pneumonia in terms of morbidity and mortality is unknown in India especially at sub-national level. In this context, we aimed to estimate the number of severe pneumonia episodes, pneumococcal pneumonia episodes and pneumonia deaths in children younger than 5 years in 2010. We adapted and parameterized a mathematical model based on the epidemiological concept of potential impact fraction developed CHERG for this analysis. The key parameters that determine the distribution of severe pneumonia episode across Indian states were state-specific under-5 population, state-specific prevalence of selected definite pneumonia risk factors and meta-estimates of relative risks for each of these risk factors. We applied the incidence estimates and attributable fraction of risk factors to population estimates for 2010 of each Indian state. We then estimated the number of pneumococcal pneumonia cases by applying the vaccine probe methodology to an existing trial. We estimated mortality due to severe pneumonia and pneumococcal pneumonia by combining incidence estimates with case fatality ratios from multi-centric hospital-based studies. Our results suggest that in 2010, 3.6 million (3.3-3.9 million) episodes of severe pneumonia and 0.35 million (0.31-0.40 million) all cause pneumonia deaths occurred in children younger than 5 years in India. The states that merit special mention include Uttar Pradesh where 18.1% children reside but contribute 24% of pneumonia cases and 26% pneumonia deaths, Bihar (11.3% children, 16% cases, 22% deaths) Madhya Pradesh (6.6% children, 9% cases, 12% deaths), and Rajasthan (6.6% children, 8% cases, 11% deaths). Further, we estimated that 0.56 million (0.49-0.64 million) severe episodes of pneumococcal pneumonia and 105 thousand (92-119 thousand) pneumococcal deaths occurred in India. The top contributors to India's pneumococcal pneumonia burden were Uttar Pradesh, Bihar, Madhya Pradesh and Rajasthan in that order. Our results

Burden of Severe Pneumonia, Pneumococcal Pneumonia and Pneumonia Deaths in Indian States: Modelling Based Estimates.

Directory of Open Access Journals (Sweden)

Habib Farooqui

Full Text Available The burden of severe pneumonia in terms of morbidity and mortality is unknown in India especially at sub-national level. In this context, we aimed to estimate the number of severe pneumonia episodes, pneumococcal pneumonia episodes and pneumonia deaths in children younger than 5 years in 2010. We adapted and parameterized a mathematical model based on the epidemiological concept of potential impact fraction developed CHERG for this analysis. The key parameters that determine the distribution of severe pneumonia episode across Indian states were state-specific under-5 population, state-specific prevalence of selected definite pneumonia risk factors and meta-estimates of relative risks for each of these risk factors. We applied the incidence estimates and attributable fraction of risk factors to population estimates for 2010 of each Indian state. We then estimated the number of pneumococcal pneumonia cases by applying the vaccine probe methodology to an existing trial. We estimated mortality due to severe pneumonia and pneumococcal pneumonia by combining incidence estimates with case fatality ratios from multi-centric hospital-based studies. Our results suggest that in 2010, 3.6 million (3.3-3.9 million episodes of severe pneumonia and 0.35 million (0.31-0.40 million all cause pneumonia deaths occurred in children younger than 5 years in India. The states that merit special mention include Uttar Pradesh where 18.1% children reside but contribute 24% of pneumonia cases and 26% pneumonia deaths, Bihar (11.3% children, 16% cases, 22% deaths Madhya Pradesh (6.6% children, 9% cases, 12% deaths, and Rajasthan (6.6% children, 8% cases, 11% deaths. Further, we estimated that 0.56 million (0.49-0.64 million severe episodes of pneumococcal pneumonia and 105 thousand (92-119 thousand pneumococcal deaths occurred in India. The top contributors to India's pneumococcal pneumonia burden were Uttar Pradesh, Bihar, Madhya Pradesh and Rajasthan in that order. Our

The complex model of risk and progression of AMD estimation

Directory of Open Access Journals (Sweden)

V. S. Akopyan

2012-01-01

Full Text Available Purpose: to develop a method and a statistical model to estimate individual risk of AMD and the risk for progression to advanced AMD using clinical and genetic risk factors.Methods: A statistical risk assessment model was developed using stepwise binary logistic regression analysis. to estimate the population differences in the prevalence of allelic variants of genes and for the development of models adapted to the population of Moscow region genotyping and assessment of the influence of other risk factors was performed in two groups: patients with differ- ent stages of AMD (n = 74, and control group (n = 116. Genetic risk factors included in the study: polymorphisms in the complement system genes (C3 and CFH, genes at 10q26 locus (ARMS2 and HtRA1, polymorphism in the mitochondrial gene Mt-ND2. Clinical risk factors included in the study: age, gender, high body mass index, smoking history.Results: A comprehensive analysis of genetic and clinical risk factors for AMD in the study group was performed. Compiled statis- tical model assessment of individual risk of AMD, the sensitivity of the model — 66.7%, specificity — 78.5%, AUC = 0.76. Risk factors of late AMD, compiled a statistical model describing the probability of late AMD, the sensitivity of the model — 66.7%, specificity — 78.3%, AUC = 0.73. the developed system allows determining the most likely version of the current late AMD: dry or wet.Conclusion: the developed test system and the mathematical algorhythm for determining the risk of AMD, risk of progression to advanced AMD have fair diagnostic informative and promising for use in clinical practice.

Improving risk estimates of runoff producing areas: formulating variable source areas as a bivariate process.

Science.gov (United States)

Cheng, Xiaoya; Shaw, Stephen B; Marjerison, Rebecca D; Yearick, Christopher D; DeGloria, Stephen D; Walter, M Todd

2014-05-01

Predicting runoff producing areas and their corresponding risks of generating storm runoff is important for developing watershed management strategies to mitigate non-point source pollution. However, few methods for making these predictions have been proposed, especially operational approaches that would be useful in areas where variable source area (VSA) hydrology dominates storm runoff. The objective of this study is to develop a simple approach to estimate spatially-distributed risks of runoff production. By considering the development of overland flow as a bivariate process, we incorporated both rainfall and antecedent soil moisture conditions into a method for predicting VSAs based on the Natural Resource Conservation Service-Curve Number equation. We used base-flow immediately preceding storm events as an index of antecedent soil wetness status. Using nine sub-basins of the Upper Susquehanna River Basin, we demonstrated that our estimated runoff volumes and extent of VSAs agreed with observations. We further demonstrated a method for mapping these areas in a Geographic Information System using a Soil Topographic Index. The proposed methodology provides a new tool for watershed planners for quantifying runoff risks across watersheds, which can be used to target water quality protection strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Risk based modelling

International Nuclear Information System (INIS)

Chapman, O.J.V.; Baker, A.E.

1993-01-01

Risk based analysis is a tool becoming available to both engineers and managers to aid decision making concerning plant matters such as In-Service Inspection (ISI). In order to develop a risk based method, some form of Structural Reliability Risk Assessment (SRRA) needs to be performed to provide a probability of failure ranking for all sites around the plant. A Probabilistic Risk Assessment (PRA) can then be carried out to combine these possible events with the capability of plant safety systems and procedures, to establish the consequences of failure for the sites. In this way the probability of failures are converted into a risk based ranking which can be used to assist the process of deciding which sites should be included in an ISI programme. This paper reviews the technique and typical results of a risk based ranking assessment carried out for nuclear power plant pipework. (author)

Longtime napping is associated with cardiovascular risk estimation according to Framingham risk score in postmenopausal women.

Science.gov (United States)

Li, Feng; Sun, Kan; Lin, Diaozhu; Qi, Yiqin; Li, Yan; Yan, Li; Ren, Meng

2016-09-01

Menopause can affect the physiological timing system, which could result in circadian rhythm changes and development of napping habits. Whether longtime napping in postmenopausal women is associated with cardiovascular disease is, however, still debated. The present study aims to investigate this association. We conducted a population-based study in 4,616 postmenopausal Chinese women. Information on sleep duration was self-reported. The Framingham General Cardiovascular Risk Score was calculated and used to identify participants at high risk of coronary heart disease (CHD). Increased daytime napping hours were positively associated with cardiovascular disease risk factors in postmenopausal women, such as age, waist circumference, systolic blood pressure, triglycerides, fasting glucose, postload glucose, and hemoglobin A1C (all P for trend napping hours, and was 3.7%, 4.3%, and 6.9% in the no daytime napping group, the 0.1 to 1 hour group, and the more than 1 hour group, respectively (P for trend = 0.005). Compared with the no daytime napping group, postmenopausal women with daytime napping more than 1 hour had higher risk of CHD in both univariate (odds ratio 1.94, 95% CI, 1.29-2.95) and multivariate (odds ratio 1.61, 95% CI, 1.03-2.52) logistic regression analyses. No statistically significant association was detected between night sleeping hours and high risk of CHD in postmenopausal participants. Daytime napping is positively associated with estimated 10-year CHD risk in postmenopausal Chinese women.

Sensitivity of Risk-Based Maintenance Planning of Offshore Wind Turbine Farms

DEFF Research Database (Denmark)

Ambühl, Simon; Sørensen, John Dalsgaard

2017-01-01

Inspection and maintenance expenses cover a considerable part of the cost of energy from offshore wind turbines. Risk-based maintenance planning approaches are a powerful tool to optimize maintenance and inspection actions and decrease the total maintenance expenses. Risk-based planning is based...... on many input parameters, which are in reality often not completely known. This paper will assess the cost impact of this incomplete knowledge based on a case study following risk-based maintenance planning. The sensitivity study focuses on weather forecast uncertainties, incomplete knowledge about...... the needed repair time on the site as well as uncertainties about the operational range of the boat and helicopter used to access the broken wind turbine. The cost saving potential is estimated by running Crude Monte Carlo simulations. Furthermore, corrective and preventive (scheduled and condition...

Estimation of Cardiovascular Risk in Patients with Type 2 Diabetes

Directory of Open Access Journals (Sweden)

Belkis Vicente Sánchez

2015-09-01

Full Text Available Background: diabetes mellitus accelerates atherosclerotic changes throughout the vascular tree and consequently increases the risk of developing fatal acute events. Objective: to estimate the global cardiovascular risk in patients with type 2 diabetes mellitus. Method: a cross-sectional study of a series of type 2 diabetic patients from the People's Council of Constancia, Abreus municipality, Cienfuegos province was conducted from July to December 2012. The universe comprised the 180 people with diabetes in the area. Variables studied were: age, sex, body mass index, nutritional assessment, blood pressure, toxic habits, associated chronic diseases, blood levels of glucose, lipids (total cholesterol and triglycerides and microalbuminuria. World Health Organization/International Society of Hypertension prediction charts specific to the region of the Americas, in which Cuba is included, were used to estimate the cardiovascular risk. Results: mean age was 61.63 years and females predominated. Relevant risk factors were hypertension followed by obesity, smoking and dyslipidemia. Mean body mass index was 27.66kg/m2; waist circumference was 94.45 cm in women and 96.86 cm in men. Thirty point six percent had more than two uncontrolled risk factors and 28.3 % of the total presented a high to very high cardiovascular risk. Conclusions: cardiovascular risk prediction charts are helpful tools for making clinical decisions, but their interpretation must be flexible and allow the intervention of clinical reasoning.

The estimation of time-varying risks in asset pricing modelling using B-Spline method

Science.gov (United States)

Nurjannah; Solimun; Rinaldo, Adji

2017-12-01

Asset pricing modelling has been extensively studied in the past few decades to explore the risk-return relationship. The asset pricing literature typically assumed a static risk-return relationship. However, several studies found few anomalies in the asset pricing modelling which captured the presence of the risk instability. The dynamic model is proposed to offer a better model. The main problem highlighted in the dynamic model literature is that the set of conditioning information is unobservable and therefore some assumptions have to be made. Hence, the estimation requires additional assumptions about the dynamics of risk. To overcome this problem, the nonparametric estimators can also be used as an alternative for estimating risk. The flexibility of the nonparametric setting avoids the problem of misspecification derived from selecting a functional form. This paper investigates the estimation of time-varying asset pricing model using B-Spline, as one of nonparametric approach. The advantages of spline method is its computational speed and simplicity, as well as the clarity of controlling curvature directly. The three popular asset pricing models will be investigated namely CAPM (Capital Asset Pricing Model), Fama-French 3-factors model and Carhart 4-factors model. The results suggest that the estimated risks are time-varying and not stable overtime which confirms the risk instability anomaly. The results is more pronounced in Carhart’s 4-factors model.

Screening effects on thyroid cancer risk estimates for populations affected by the Chernobyl accident

International Nuclear Information System (INIS)

Jacob, P.; Kaiser, J. C.; Vavilov, S.E.; Bogdanova, T.; Tronko, N. D.

2004-01-01

Simulation calculations are performed in order to explore the ecological bias in studies as they are performed with settlement specific data in the aftemath of the Chernobyl accident. Based on methods, that were developed by Lubin for exploring the ecologic bias due to smoking in indoor radon studies of lung cancer, the influence of the introduction of ultrasound devices and enhanced medical surveillance on the detection and reporting of thyroid cancer cases was investigated. Calculations were performed by simulating thyroid doses of one million children in a total of 744 settlements and assuming a linear dependence of the risk on dose and various scenarios of the screening. The dose distributions simulate the distributions similar to those used in previous ecologic studies of the thyroid cancer risk in Ukraine after the Chernobyl accident. The ecologic bias was defined as the ratio of risk coefficients derived from an ecological study to the corresponding risk factor in the underlying risl model. the ecologic bias was estimated for each of the screening scenarios. Analytical equations were derived that allow the exact numerical compuation of the bias which is determined by covariance terms between the increased detection and reporting on one side and thyroid dose values (individual and averaged for the settlements) on the other side. Nested in th epopulation data, a cohort study was simulated with 10 000 individuals and an average thyroid dose of 0.3 Gy. the present study underlines the different scopes of the ecologic and cohort study designs perfomed in the aftermed of the Chernobyl accident. Whereas the ecologic studies give an estimate of the excess thyroid cancer risks per unit dose under the conditions of a health care system as it is typical for the affected countries after the Chernobyl accident, the cohort study gives risk estimates within a well screened cohort. Due to the strong screening effects, excess absoulte risks in the ecological study cohort are

Estimating the commodity market price of risk for energy prices

International Nuclear Information System (INIS)

Kolos, Sergey P.; Ronn, Ehud I.

2008-01-01

The purpose of this paper is to estimate the ''market price of risk'' (MPR) for energy commodities, the ratio of expected return to standard deviation. The MPR sign determines whether energy forward prices are upward- or downward-biased predictors of expected spot prices. We estimate MPRs using spot and futures prices, while accounting for the Samuelson effect. We find long-term MPRs generally positive and short-term negative, consistent with positive energy betas and hedging, respectively. In spot electricity markets, MPRs in Day-Ahead Prices agree with short-dated futures. Our results relate risk premia to informed hedging decisions, and futures prices to forecast/expected prices. (author)

Patient-specific radiation dose and cancer risk estimation in CT: Part II. Application to patients

Energy Technology Data Exchange (ETDEWEB)

Li Xiang; Samei, Ehsan; Segars, W. Paul; Sturgeon, Gregory M.; Colsher, James G.; Toncheva, Greta; Yoshizumi, Terry T.; Frush, Donald P. [Medical Physics Graduate Program, Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Department of Physics, and Department of Biomedical Engineering, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 and Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599 (United States); Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Duke Radiation Dosimetry Laboratory, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27705 (United States); Division of Pediatric Radiology, Department of Radiology, Medical Physics Graduate Program, Duke University Medical Center, Durham, North Carolina 27710 (United States)

2011-01-15

Purpose: Current methods for estimating and reporting radiation dose from CT examinations are largely patient-generic; the body size and hence dose variation from patient to patient is not reflected. Furthermore, the current protocol designs rely on dose as a surrogate for the risk of cancer incidence, neglecting the strong dependence of risk on age and gender. The purpose of this study was to develop a method for estimating patient-specific radiation dose and cancer risk from CT examinations. Methods: The study included two patients (a 5-week-old female patient and a 12-year-old male patient), who underwent 64-slice CT examinations (LightSpeed VCT, GE Healthcare) of the chest, abdomen, and pelvis at our institution in 2006. For each patient, a nonuniform rational B-spine (NURBS) based full-body computer model was created based on the patient's clinical CT data. Large organs and structures inside the image volume were individually segmented and modeled. Other organs were created by transforming an existing adult male or female full-body computer model (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program previously developed and validated for dose simulation on the LightSpeed VCT scanner was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Patient-specific organ dose and effective dose were compared with patient-generic CT dose quantities in current clinical use: the volume-weighted CT dose index (CTDI{sub vol}) and the effective dose derived from the dose-length product (DLP). Results: The effective dose for the CT examination of the newborn patient (5.7 mSv) was higher but comparable to that for the CT examination of the teenager patient (4.9 mSv) due to the size-based clinical CT protocols at our institution, which employ lower scan techniques for smaller

Channel Estimation in DCT-Based OFDM

Science.gov (United States)

Wang, Yulin; Zhang, Gengxin; Xie, Zhidong; Hu, Jing

2014-01-01

This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic. PMID:24757439

A novel tool for user-friendly estimation of natural, diagnostic and professional radiation risk: Radio-Risk software

International Nuclear Information System (INIS)

Carpeggiani, Clara; Paterni, Marco; Caramella, Davide; Vano, Eliseo; Semelka, Richard C.; Picano, Eugenio

2012-01-01

Background: Awareness of radiological risk is low among doctors and patients. An educational/decision tool that considers each patient’ s cumulative lifetime radiation exposure would facilitate provider–patient communication. Aim: The purpose of this work was to develop user-friendly software for simple estimation and communication of radiological risk to patients and doctors as a part of the SUIT-Heart (Stop Useless Imaging Testing in Heart disease) Project of the Tuscany Region. Methods: We developed a novel software program (PC-platform, Windows OS fully downloadable at (http://suit-heart.ifc.cnr.it)) considering reference dose estimates from American Heart Association Radiological Imaging 2009 guidelines and UK Royal College of Radiology 2007 guidelines. Cancer age and gender-weighted risk were derived from Biological Effects of Ionising Radiation VII Committee, 2006. Results: With simple input functions (demographics, age, gender) the user selects from a predetermined menu variables relating to natural (e.g., airplane flights and geo-tracked background exposure), professional (e.g., cath lab workers) and medical (e.g., CT, cardiac scintigraphy, coronary stenting) sources. The program provides a simple numeric (cumulative effective dose in milliSievert, mSv, and equivalent number of chest X-rays) and graphic (cumulative temporal trends of exposure, cancer cases out of 100 exposed persons) display. Conclusions: A simple software program allows straightforward estimation of cumulative dose (in multiples of chest X-rays) and risk (in extra % lifetime cancer risk), with simple numbers quantifying lifetime extra cancer risk. Pictorial display of radiation risk may be valuable for increasing radiological awareness in cardiologists.

A novel tool for user-friendly estimation of natural, diagnostic and professional radiation risk: Radio-Risk software

Energy Technology Data Exchange (ETDEWEB)

Carpeggiani, Clara; Paterni, Marco [CNR, Institute of Clinical Physiology (Italy); Caramella, Davide [Radiology Department, Pisa University, Pisa (Italy); Vano, Eliseo [San Carlos Hospital, Radiology Department, Complutense University, Madrid (Spain); Semelka, Richard C. [University of North Carolina, Chapel Hill, NC (United States); Picano, Eugenio, E-mail: picano@ifc.cnr.it [CNR, Institute of Clinical Physiology (Italy)

2012-11-15

Background: Awareness of radiological risk is low among doctors and patients. An educational/decision tool that considers each patient' s cumulative lifetime radiation exposure would facilitate provider-patient communication. Aim: The purpose of this work was to develop user-friendly software for simple estimation and communication of radiological risk to patients and doctors as a part of the SUIT-Heart (Stop Useless Imaging Testing in Heart disease) Project of the Tuscany Region. Methods: We developed a novel software program (PC-platform, Windows OS fully downloadable at (http://suit-heart.ifc.cnr.it)) considering reference dose estimates from American Heart Association Radiological Imaging 2009 guidelines and UK Royal College of Radiology 2007 guidelines. Cancer age and gender-weighted risk were derived from Biological Effects of Ionising Radiation VII Committee, 2006. Results: With simple input functions (demographics, age, gender) the user selects from a predetermined menu variables relating to natural (e.g., airplane flights and geo-tracked background exposure), professional (e.g., cath lab workers) and medical (e.g., CT, cardiac scintigraphy, coronary stenting) sources. The program provides a simple numeric (cumulative effective dose in milliSievert, mSv, and equivalent number of chest X-rays) and graphic (cumulative temporal trends of exposure, cancer cases out of 100 exposed persons) display. Conclusions: A simple software program allows straightforward estimation of cumulative dose (in multiples of chest X-rays) and risk (in extra % lifetime cancer risk), with simple numbers quantifying lifetime extra cancer risk. Pictorial display of radiation risk may be valuable for increasing radiological awareness in cardiologists.

An exploration of spatial risk assessment for soil protection: estimating risk and establishing priority areas for soil protection.

Science.gov (United States)

Kibblewhite, M G; Bellamy, P H; Brewer, T R; Graves, A R; Dawson, C A; Rickson, R J; Truckell, I; Stuart, J

2014-03-01

Methods for the spatial estimation of risk of harm to soil by erosion by water and wind and by soil organic matter decline are explored. Rates of harm are estimated for combinations of soil type and land cover (as a proxy for hazard frequency) and used to estimate risk of soil erosion and loss of soil organic carbon (SOC) for 1 km(2)pixels. Scenarios are proposed for defining the acceptability of risk of harm to soil: the most precautionary one corresponds to no net harm after natural regeneration of soil (i.e. a 1 in 20 chance of exceeding an erosion rate of soils and a carbon stock decline of 0 tha(-1)y(-1) for organic soils). Areas at higher and lower than possible acceptable risk are mapped. The veracity of boundaries is compromised if areas of unacceptable risk are mapped to administrative boundaries. Errors in monitoring change in risk of harm to soil and inadequate information on risk reduction measures' efficacy, at landscape scales, make it impossible to use or monitor quantitative targets for risk reduction adequately. The consequences for priority area definition of expressing varying acceptable risk of harm to soil as a varying probability of exceeding a fixed level of harm, or, a varying level of harm being exceeded with a fixed probability, are discussed. Soil data and predictive models for rates of harm to soil would need considerable development and validation to implement a priority area approach robustly. Copyright © 2013 Elsevier B.V. All rights reserved.

Combining ungrouped and grouped wildfire data to estimate fire risk

KAUST Repository

Hernandez-Magallanes, I.

2013-10-11

© 2013 John Wiley & Sons, Ltd. Frequently, models are required to combine information obtained from different data sources and on different scales. In this work, we are interested in estimating the risk of wildfire ignition in the USA for a particular time and location by merging two levels of data, namely, individual points and aggregate count of points into areas. The data for federal lands consist of the point location and time of each fire. Nonfederal fires are aggregated by county for a particular year. The probability model is based on the wildfire point process. Assuming a smooth intensity function, a locally weighted likelihood fit is used, which incorporates the group effect. A logit model is used under the assumption of the existence of a latent process, and fuel conditions are included as a covariate. The model assessment is based on a residual analysis, while the False Discovery Rate detects spatial patterns. A benefit of the proposed model is that there is no need of arbitrary aggregation of individual fires into counts. A map of predicted probability of ignition for the Midwest US in 1990 is included. The predicted ignition probabilities and the estimated total number of expected fires are required for the allocation of resources.

Estimating the concordance probability in a survival analysis with a discrete number of risk groups.

Science.gov (United States)

Heller, Glenn; Mo, Qianxing

2016-04-01

A clinical risk classification system is an important component of a treatment decision algorithm. A measure used to assess the strength of a risk classification system is discrimination, and when the outcome is survival time, the most commonly applied global measure of discrimination is the concordance probability. The concordance probability represents the pairwise probability of lower patient risk given longer survival time. The c-index and the concordance probability estimate have been used to estimate the concordance probability when patient-specific risk scores are continuous. In the current paper, the concordance probability estimate and an inverse probability censoring weighted c-index are modified to account for discrete risk scores. Simulations are generated to assess the finite sample properties of the concordance probability estimate and the weighted c-index. An application of these measures of discriminatory power to a metastatic prostate cancer risk classification system is examined.

Radiation-Induced Leukemia at Doses Relevant to Radiation Therapy: Modeling Mechanisms and Estimating Risks

Science.gov (United States)

Shuryak, Igor; Sachs, Rainer K.; Hlatky, Lynn; Mark P. Little; Hahnfeldt, Philip; Brenner, David J.

2006-01-01

Because many cancer patients are diagnosed earlier and live longer than in the past, second cancers induced by radiation therapy have become a clinically significant issue. An earlier biologically based model that was designed to estimate risks of high-dose radiation induced solid cancers included initiation of stem cells to a premalignant state, inactivation of stem cells at high radiation doses, and proliferation of stem cells during cellular repopulation after inactivation. This earlier model predicted the risks of solid tumors induced by radiation therapy but overestimated the corresponding leukemia risks. Methods: To extend the model to radiation-induced leukemias, we analyzed in addition to cellular initiation, inactivation, and proliferation a repopulation mechanism specific to the hematopoietic system: long-range migration through the blood stream of hematopoietic stem cells (HSCs) from distant locations. Parameters for the model were derived from HSC biologic data in the literature and from leukemia risks among atomic bomb survivors v^ ho were subjected to much lower radiation doses. Results: Proliferating HSCs that migrate from sites distant from the high-dose region include few preleukemic HSCs, thus decreasing the high-dose leukemia risk. The extended model for leukemia provides risk estimates that are consistent with epidemiologic data for leukemia risk associated with radiation therapy over a wide dose range. For example, when applied to an earlier case-control study of 110000 women undergoing radiotherapy for uterine cancer, the model predicted an excess relative risk (ERR) of 1.9 for leukemia among women who received a large inhomogeneous fractionated external beam dose to the bone marrow (mean = 14.9 Gy), consistent with the measured ERR (2.0, 95% confidence interval [CI] = 0.2 to 6.4; from 3.6 cases expected and 11 cases observed). As a corresponding example for brachytherapy, the predicted ERR of 0.80 among women who received an inhomogeneous low

Predicting Young Adults Binge Drinking in Nightlife Scenes: An Evaluation of the D-ARIANNA Risk Estimation Model.

Science.gov (United States)

Crocamo, Cristina; Bartoli, Francesco; Montomoli, Cristina; Carrà, Giuseppe

2018-05-25

Binge drinking (BD) among young people has significant public health implications. Thus, there is the need to target users most at risk. We estimated the discriminative accuracy of an innovative model nested in a recently developed e-Health app (Digital-Alcohol RIsk Alertness Notifying Network for Adolescents and young adults [D-ARIANNA]) for BD in young people, examining its performance to predict short-term BD episodes. We consecutively recruited young adults in pubs, discos, or live music events. Participants self-administered the app D-ARIANNA, which incorporates an evidence-based risk estimation model for the dependent variable BD. They were re-evaluated after 2 weeks using a single-item BD behavior as reference. We estimated D-ARIANNA discriminative ability through measures of sensitivity and specificity, and also likelihood ratios. ROC curve analyses were carried out, exploring variability of discriminative ability across subgroups. The analyses included 507 subjects, of whom 18% reported at least 1 BD episode at follow-up. The majority of these had been identified as at high/moderate or high risk (65%) at induction. Higher scores from the D-ARIANNA risk estimation model reflected an increase in the likelihood of BD. Additional risk factors such as high pocket money availability and alcohol expectancies influence the predictive ability of the model. The D-ARIANNA model showed an appreciable, though modest, predictive ability for subsequent BD episodes. Post-hoc model showed slightly better predictive properties. Using up-to-date technology, D-ARIANNA appears an innovative and promising screening tool for BD among young people. Long-term impact remains to be established, and also the role of additional social and environmental factors.

Consolidating Risk Estimates for Radiation-Induced Complications in Individual Patient: Late Rectal Toxicity

Energy Technology Data Exchange (ETDEWEB)

Prior, Phillip; Devisetty, Kiran [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Tarima, Sergey S. [Division of Biostatistics, Institute for Health and Society, Medical College of Wisconsin, Milwaukee, WI (United States); Lawton, Colleen A.F. [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States); Semenenko, Vladimir A., E-mail: vsemenenko@mcw.edu [Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI (United States)

2012-05-01

Purpose: To test the feasibility of a new approach to synthesize published normal tissue complication data using late rectal toxicity in prostate cancer as an example. Methods and Materials: A data survey was performed to identify the published reports on the dose-response relationships for late rectal toxicity. The risk estimates for Grade 1 or greater, Grade 2 or greater, and Grade 3 or greater toxicity were obtained for a test cohort of patients treated at our institution. The influence of the potential factors that might have affected the reported toxicity levels was investigated. The studies that did not conform to the general data trends were excluded, and single, combined risk estimates were derived for each patient and toxicity level. Results: A total of 21 studies of nonoverlapping patient populations were identified. Three studies provided dose-response models for more than one level of toxicity. Of these 21 studies, 6, 14, and 5 were used to derive the initial risk estimates for Grade 1, 2, and 3 or greater toxicity, respectively. A comparison of risk estimates between the studies reporting rectal bleeding and rectal toxicity (bleeding plus other symptoms) or between studies with follow-up <36 months and {>=}36 months did not reveal significant differences (p {>=} .29 for all comparisons). After excluding three reports that did not conform to the general data trends, the combined risk estimates were derived from 5 reports (647 patients), 11 reports (3,369 patients), and 5 reports (1,330 patients) for Grade 1, 2, and 3 or greater toxicity, respectively. Conclusions: The proposed approach is feasible and allows for more systematic use of published dose-response data to estimate the complication risks for the individual patient.

Consolidating Risk Estimates for Radiation-Induced Complications in Individual Patient: Late Rectal Toxicity

International Nuclear Information System (INIS)

Prior, Phillip; Devisetty, Kiran; Tarima, Sergey S.; Lawton, Colleen A.F.; Semenenko, Vladimir A.

2012-01-01

Purpose: To test the feasibility of a new approach to synthesize published normal tissue complication data using late rectal toxicity in prostate cancer as an example. Methods and Materials: A data survey was performed to identify the published reports on the dose–response relationships for late rectal toxicity. The risk estimates for Grade 1 or greater, Grade 2 or greater, and Grade 3 or greater toxicity were obtained for a test cohort of patients treated at our institution. The influence of the potential factors that might have affected the reported toxicity levels was investigated. The studies that did not conform to the general data trends were excluded, and single, combined risk estimates were derived for each patient and toxicity level. Results: A total of 21 studies of nonoverlapping patient populations were identified. Three studies provided dose–response models for more than one level of toxicity. Of these 21 studies, 6, 14, and 5 were used to derive the initial risk estimates for Grade 1, 2, and 3 or greater toxicity, respectively. A comparison of risk estimates between the studies reporting rectal bleeding and rectal toxicity (bleeding plus other symptoms) or between studies with follow-up <36 months and ≥36 months did not reveal significant differences (p ≥ .29 for all comparisons). After excluding three reports that did not conform to the general data trends, the combined risk estimates were derived from 5 reports (647 patients), 11 reports (3,369 patients), and 5 reports (1,330 patients) for Grade 1, 2, and 3 or greater toxicity, respectively. Conclusions: The proposed approach is feasible and allows for more systematic use of published dose–response data to estimate the complication risks for the individual patient.

Risk analysis of heat recovery steam generator with semi quantitative risk based inspection API 581

Science.gov (United States)

Prayogo, Galang Sandy; Haryadi, Gunawan Dwi; Ismail, Rifky; Kim, Seon Jin

2016-04-01

Corrosion is a major problem that most often occurs in the power plant. Heat recovery steam generator (HRSG) is an equipment that has a high risk to the power plant. The impact of corrosion damage causing HRSG power plant stops operating. Furthermore, it could be threaten the safety of employees. The Risk Based Inspection (RBI) guidelines by the American Petroleum Institute (API) 58 has been used to risk analysis in the HRSG 1. By using this methodology, the risk that caused by unexpected failure as a function of the probability and consequence of failure can be estimated. This paper presented a case study relating to the risk analysis in the HRSG, starting with a summary of the basic principles and procedures of risk assessment and applying corrosion RBI for process industries. The risk level of each HRSG equipment were analyzed: HP superheater has a medium high risk (4C), HP evaporator has a medium-high risk (4C), and the HP economizer has a medium risk (3C). The results of the risk assessment using semi-quantitative method of standard API 581 based on the existing equipment at medium risk. In the fact, there is no critical problem in the equipment components. Damage mechanisms were prominent throughout the equipment is thinning mechanism. The evaluation of the risk approach was done with the aim of reducing risk by optimizing the risk assessment activities.

Risk analysis of heat recovery steam generator with semi quantitative risk based inspection API 581

International Nuclear Information System (INIS)

Prayogo, Galang Sandy; Haryadi, Gunawan Dwi; Ismail, Rifky; Kim, Seon Jin

2016-01-01

Corrosion is a major problem that most often occurs in the power plant. Heat recovery steam generator (HRSG) is an equipment that has a high risk to the power plant. The impact of corrosion damage causing HRSG power plant stops operating. Furthermore, it could be threaten the safety of employees. The Risk Based Inspection (RBI) guidelines by the American Petroleum Institute (API) 58 has been used to risk analysis in the HRSG 1. By using this methodology, the risk that caused by unexpected failure as a function of the probability and consequence of failure can be estimated. This paper presented a case study relating to the risk analysis in the HRSG, starting with a summary of the basic principles and procedures of risk assessment and applying corrosion RBI for process industries. The risk level of each HRSG equipment were analyzed: HP superheater has a medium high risk (4C), HP evaporator has a medium-high risk (4C), and the HP economizer has a medium risk (3C). The results of the risk assessment using semi-quantitative method of standard API 581 based on the existing equipment at medium risk. In the fact, there is no critical problem in the equipment components. Damage mechanisms were prominent throughout the equipment is thinning mechanism. The evaluation of the risk approach was done with the aim of reducing risk by optimizing the risk assessment activities.

Risk analysis of heat recovery steam generator with semi quantitative risk based inspection API 581

Energy Technology Data Exchange (ETDEWEB)

Prayogo, Galang Sandy, E-mail: gasandylang@live.com; Haryadi, Gunawan Dwi; Ismail, Rifky [Department of Mechanical Engineering, Diponegoro University, Semarang (Indonesia); Kim, Seon Jin [Department of Mechanical & Automotive Engineering of Pukyong National University (Korea, Republic of)

2016-04-19

Corrosion is a major problem that most often occurs in the power plant. Heat recovery steam generator (HRSG) is an equipment that has a high risk to the power plant. The impact of corrosion damage causing HRSG power plant stops operating. Furthermore, it could be threaten the safety of employees. The Risk Based Inspection (RBI) guidelines by the American Petroleum Institute (API) 58 has been used to risk analysis in the HRSG 1. By using this methodology, the risk that caused by unexpected failure as a function of the probability and consequence of failure can be estimated. This paper presented a case study relating to the risk analysis in the HRSG, starting with a summary of the basic principles and procedures of risk assessment and applying corrosion RBI for process industries. The risk level of each HRSG equipment were analyzed: HP superheater has a medium high risk (4C), HP evaporator has a medium-high risk (4C), and the HP economizer has a medium risk (3C). The results of the risk assessment using semi-quantitative method of standard API 581 based on the existing equipment at medium risk. In the fact, there is no critical problem in the equipment components. Damage mechanisms were prominent throughout the equipment is thinning mechanism. The evaluation of the risk approach was done with the aim of reducing risk by optimizing the risk assessment activities.

Estimating young Australian adults' risk of hearing damage from selected leisure activities.

Science.gov (United States)

Beach, Elizabeth; Williams, Warwick; Gilliver, Megan

2013-01-01

Several previous studies have attempted to estimate the risk of noise-induced hearing loss from loud leisure noise. Some of these studies may have overestimated the risk because they used noise estimates taken from the higher end of reported levels. The aim of the present study was to provide a realistic estimate of the number of young Australian adults who may be at risk of hearing damage and eventual hearing loss from leisure-noise exposure. Average noise levels at five high-noise leisure activities, (1) nightclubs; (2) pubs, bars, and registered clubs; (3) fitness classes; (4) live sporting events; (5) concerts and live music venues, were calculated using 108 measurements taken from a large database of leisure noise measurements. In addition, an online survey was administered to a convenience sample of 1000 young adults aged 18 to 35 years, who reported the time spent at these leisure activities and the frequency with which they undertook the activities. They also answered questions about tinnitus and their perceived risk of hearing damage. Although the survey data cannot be considered representative of the population of young Australian adults, it was weighted to this population in respect of age, gender, education, and location. The survey data and the average noise levels were used to estimate each individual's annual noise exposure, and in turn, estimate those at risk of hearing damage from leisure-noise exposure. For the majority of participants (n = 868), the accumulated leisure noise level was within the acceptable workplace limit. However, 132 participants or 14.1% (population weighted) were exposed to an annual noise dose greater than the acceptable workplace noise limit. By far, the main source of high-risk leisure noise was from nightclubs. Those with more leisure-noise exposure experienced more tinnitus and perceived themselves to be more at risk than those with lower noise exposures. It is recommended that nightclub operators reduce noise levels

75 FR 3647 - Federal Agricultural Mortgage Corporation Funding and Fiscal Affairs; Risk-Based Capital...

Science.gov (United States)

2010-01-22

... Funding and Fiscal Affairs; Risk-Based Capital Requirements AGENCY: Farm Credit Administration. ACTION... further directed FCA to estimate the credit risk on the portfolio covered by this new authority at a rate... component to directly recognize the credit risk on such loans.\\4\\ At the time of the Farm Bill's enactment...

Comparison of robustness to outliers between robust poisson models and log-binomial models when estimating relative risks for common binary outcomes: a simulation study.

Science.gov (United States)

Chen, Wansu; Shi, Jiaxiao; Qian, Lei; Azen, Stanley P

2014-06-26

To estimate relative risks or risk ratios for common binary outcomes, the most popular model-based methods are the robust (also known as modified) Poisson and the log-binomial regression. Of the two methods, it is believed that the log-binomial regression yields more efficient estimators because it is maximum likelihood based, while the robust Poisson model may be less affected by outliers. Evidence to support the robustness of robust Poisson models in comparison with log-binomial models is very limited. In this study a simulation was conducted to evaluate the performance of the two methods in several scenarios where outliers existed. The findings indicate that for data coming from a population where the relationship between the outcome and the covariate was in a simple form (e.g. log-linear), the two models yielded comparable biases and mean square errors. However, if the true relationship contained a higher order term, the robust Poisson models consistently outperformed the log-binomial models even when the level of contamination is low. The robust Poisson models are more robust (or less sensitive) to outliers compared to the log-binomial models when estimating relative risks or risk ratios for common binary outcomes. Users should be aware of the limitations when choosing appropriate models to estimate relative risks or risk ratios.

Data analyses and modelling for risk based monitoring of mycotoxins in animal feed

NARCIS (Netherlands)

Ine van der Fels-Klerx, H.J.; Adamse, Paulien; Punt, Ans; Asselt, van Esther D.

2018-01-01

Following legislation, European Member States should have multi-annual control programs for contaminants, such as for mycotoxins, in feed and food. These programs need to be risk based implying the checks are regular and proportional to the estimated risk for animal and human health. This study

Estimates of radiation doses and cancer risk from food intake in Korea

International Nuclear Information System (INIS)

Moon, Eun Kyeong; Lee, Won Jin; Ha, Wi Ho; Seo, Song Won; Jin, Young Woo; Jeong, Kyu Hwan; Yoon, Hae Jung; Kim, Hyoung Soo; Hwang, Myung Sil; Choi, Hoon

2016-01-01

After the Fukushima Daiichi nuclear power plant accident, a widespread public concern for radiation exposure through the contamination of domestic or imported food has continued worldwide. Because the internal exposure from contaminated food is an important consideration for human health effect, some studies for estimating radiation doses and cancer risk from the Fukushima nuclear accident have been conducted in several countries (1). The aims of the study is to estimate internal radiation dose and lifetime risks of cancer from food ingestion in Korean population. Our findings suggest no discernible increase n radiation doses or excess fatal cancer risk from food ingestion at this stage in Korea, and provide scientific evidence of the risk communication with general public associated with low-dose radiation exposure.

Estimates of radiation doses and cancer risk from food intake in Korea

Energy Technology Data Exchange (ETDEWEB)

Moon, Eun Kyeong; Lee, Won Jin [Korea University, Seoul (Korea, Republic of); Ha, Wi Ho; Seo, Song Won; Jin, Young Woo [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Jeong, Kyu Hwan [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Yoon, Hae Jung; Kim, Hyoung Soo; Hwang, Myung Sil [Ministry of Food and Drug Safety, Cheongju (Korea, Republic of); Choi, Hoon [Wonkwang University, Iksan (Korea, Republic of)

2016-04-15

After the Fukushima Daiichi nuclear power plant accident, a widespread public concern for radiation exposure through the contamination of domestic or imported food has continued worldwide. Because the internal exposure from contaminated food is an important consideration for human health effect, some studies for estimating radiation doses and cancer risk from the Fukushima nuclear accident have been conducted in several countries (1). The aims of the study is to estimate internal radiation dose and lifetime risks of cancer from food ingestion in Korean population. Our findings suggest no discernible increase n radiation doses or excess fatal cancer risk from food ingestion at this stage in Korea, and provide scientific evidence of the risk communication with general public associated with low-dose radiation exposure.

A-BOMB SURVIVOR SITE-SPECIFIC RADIOGENIC CANCER RISKS ESTIMATES

Science.gov (United States)

A draft manuscript is being prepared that describes ways to improve estimates of risk from radiation that have been derived from A-bomb survivors. The work has been published in the journal Radiation Research volume 169, pages 87-98.

A Robust Approach to Risk Assessment Based on Species Sensitivity Distributions.

Science.gov (United States)

Monti, Gianna S; Filzmoser, Peter; Deutsch, Roland C

2018-05-03

The guidelines for setting environmental quality standards are increasingly based on probabilistic risk assessment due to a growing general awareness of the need for probabilistic procedures. One of the commonly used tools in probabilistic risk assessment is the species sensitivity distribution (SSD), which represents the proportion of species affected belonging to a biological assemblage as a function of exposure to a specific toxicant. Our focus is on the inverse use of the SSD curve with the aim of estimating the concentration, HCp, of a toxic compound that is hazardous to p% of the biological community under study. Toward this end, we propose the use of robust statistical methods in order to take into account the presence of outliers or apparent skew in the data, which may occur without any ecological basis. A robust approach exploits the full neighborhood of a parametric model, enabling the analyst to account for the typical real-world deviations from ideal models. We examine two classic HCp estimation approaches and consider robust versions of these estimators. In addition, we also use data transformations in conjunction with robust estimation methods in case of heteroscedasticity. Different scenarios using real data sets as well as simulated data are presented in order to illustrate and compare the proposed approaches. These scenarios illustrate that the use of robust estimation methods enhances HCp estimation. © 2018 Society for Risk Analysis.

Assessing network scale-up estimates for groups most at risk of HIV/AIDS: evidence from a multiple-method study of heavy drug users in Curitiba, Brazil.

Science.gov (United States)

Salganik, Matthew J; Fazito, Dimitri; Bertoni, Neilane; Abdo, Alexandre H; Mello, Maeve B; Bastos, Francisco I

2011-11-15

One of the many challenges hindering the global response to the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) epidemic is the difficulty of collecting reliable information about the populations most at risk for the disease. Thus, the authors empirically assessed a promising new method for estimating the sizes of most at-risk populations: the network scale-up method. Using 4 different data sources, 2 of which were from other researchers, the authors produced 5 estimates of the number of heavy drug users in Curitiba, Brazil. The authors found that the network scale-up and generalized network scale-up estimators produced estimates 5-10 times higher than estimates made using standard methods (the multiplier method and the direct estimation method using data from 2004 and 2010). Given that equally plausible methods produced such a wide range of results, the authors recommend that additional studies be undertaken to compare estimates based on the scale-up method with those made using other methods. If scale-up-based methods routinely produce higher estimates, this would suggest that scale-up-based methods are inappropriate for populations most at risk of HIV/AIDS or that standard methods may tend to underestimate the sizes of these populations.

Estimating the decline in excess risk of chronic obstructive pulmonary disease following quitting smoking - a systematic review based on the negative exponential model.

Science.gov (United States)

Lee, Peter N; Fry, John S; Forey, Barbara A

2014-03-01

We quantified the decline in COPD risk following quitting using the negative exponential model, as previously carried out for other smoking-related diseases. We identified 14 blocks of RRs (from 11 studies) comparing current smokers, former smokers (by time quit) and never smokers, some studies providing sex-specific blocks. Corresponding pseudo-numbers of cases and controls/at risk formed the data for model-fitting. We estimated the half-life (H, time since quit when the excess risk becomes half that for a continuing smoker) for each block, except for one where no decline with quitting was evident, and H was not estimable. For the remaining 13 blocks, goodness-of-fit to the model was generally adequate, the combined estimate of H being 13.32 (95% CI 11.86-14.96) years. There was no heterogeneity in H, overall or by various studied sources. Sensitivity analyses allowing for reverse causation or different assumed times for the final quitting period little affected the results. The model summarizes quitting data well. The estimate of 13.32years is substantially larger than recent estimates of 4.40years for ischaemic heart disease and 4.78years for stroke, and also larger than the 9.93years for lung cancer. Heterogeneity was unimportant for COPD, unlike for the other three diseases. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Estimating 'Value at Risk' of crude oil price and its spillover effect using the GED-GARCH approach

International Nuclear Information System (INIS)

Fan, Ying; Wei, Yi-Ming; Zhang, Yue-Jun; Tsai, Hsien-Tang

2008-01-01

Estimation has been carried out using GARCH-type models, based on the Generalized Error Distribution (GED), for both the extreme downside and upside Value-at-Risks (VaR) of returns in the WTI and Brent crude oil spot markets. Furthermore, according to a new concept of Granger causality in risk, a kernel-based test is proposed to detect extreme risk spillover effect between the two oil markets. Results of an empirical study indicate that the GED-GARCH-based VaR approach appears more effective than the well-recognized HSAF (i.e. historical simulation with ARMA forecasts). Moreover, this approach is also more realistic and comprehensive than the standard normal distribution-based VaR model that is commonly used. Results reveal that there is significant two-way risk spillover effect between WTI and Brent markets. Supplementary study indicates that at the 99% confidence level, when negative market news arises that brings about a slump in oil price return, historical information on risk in the WTI market helps to forecast the Brent market. Conversely, it is not the case when positive news occurs and returns rise. Historical information on risk in the two markets can facilitate forecasts of future extreme market risks for each other. These results are valuable for anyone who needs evaluation and forecasts of the risk situation in international crude oil markets. (author)

Model dependencies of risk aversion and working interest estimates

International Nuclear Information System (INIS)

Lerche, I.

1996-01-01

Working interest, W, and risk adjusted value, RAV, are evaluated using both Cozzolino's formula for exponential dependence of risk aversion and also for a hyperbolic tangent dependence. In addition, the general method is given of constructing an RAV formula for any functional choice of risk aversion dependence. Two examples are given to illustrate how the model dependencies influence choices of working interest and risk adjusted value depending on whether the expected value of the project is positive or negative. In general the Cozzolino formula provides a more conservative position for risk than does the hyperbolic tangent formula, reflecting the difference in corporate attitudes to risk aversion. The commonly used Cozzolino formula is shown to have simple exact arithmetic expressions for maximum working interest and maximum RAV; the hyperbolic tangent formula has approximate analytic expressions. Both formulae also yield approximate analytical expressions for the working interest yielding a risk neutral RAV of zero. These arithmetic results are useful for making quick estimates of working interest ranges and risk adjusted values. (Author)

Small-mammal density estimation: A field comparison of grid-based vs. web-based density estimators

Science.gov (United States)

Parmenter, R.R.; Yates, Terry L.; Anderson, D.R.; Burnham, K.P.; Dunnum, J.L.; Franklin, A.B.; Friggens, M.T.; Lubow, B.C.; Miller, M.; Olson, G.S.; Parmenter, Cheryl A.; Pollard, J.; Rexstad, E.; Shenk, T.M.; Stanley, T.R.; White, Gary C.

2003-01-01

��blind” test allowed us to evaluate the influence of expertise and experience in calculating density estimates in comparison to simply using default values in programs CAPTURE and DISTANCE. While the rodent sample sizes were considerably smaller than the recommended minimum for good model results, we found that several models performed well empirically, including the web-based uniform and half-normal models in program DISTANCE, and the grid-based models Mb and Mbh in program CAPTURE (with AÌ‚ adjusted by species-specific full mean maximum distance moved (MMDM) values). These models produced accurate DÌ‚ values (with 95% confidence intervals that included the true D values) and exhibited acceptable bias but poor precision. However, in linear regression analyses comparing each model's DÌ‚ values to the true D values over the range of observed test densities, only the web-based uniform model exhibited a regression slope near 1.0; all other models showed substantial slope deviations, indicating biased estimates at higher or lower density values. In addition, the grid-based DÌ‚ analyses using full MMDM values for WÌ‚ area adjustments required a number of theoretical assumptions of uncertain validity, and we therefore viewed their empirical successes with caution. Finally, density estimates from the independent analysts were highly variable, but estimates from web-based approaches had smaller mean square errors and better achieved confidence-interval coverage of D than did grid-based approaches. Our results support the contention that web-based approaches for density estimation of small-mammal populations are both theoretically and empirically superior to grid-based approaches, even when sample size is far less than often recommended. In view of the increasing need for standardized environmental measures for comparisons among ecosystems and through time, analytical models based on distance sampling appear to offer accurate density estimation approaches for research

Estimating internal exposure risks by the relative risk and the National Institute of Health risk models

International Nuclear Information System (INIS)

Mehta, S.K.; Sarangapani, R.

1995-01-01

This paper presents tabulations of risk (R) and person-years of life lost (PYLL) for acute exposures of individual organs at ages 20 and 40 yrs for the Indian and Japanese populations to illustrate the effect of age at exposure in the two models. Results are also presented for the organ wise nominal probability coefficients (NPC) and PYLL for individual organs for the age distributed Indian population by the two models. The results presented show that for all organs the estimates of PYLL and NPC for the Indian population are lower than those for the Japanese population by both models except for oesophagus, breast and ovary by the relative risk (RR) model, where the opposite trend is observed. The results also show that the Indian all-cancer values of NPC averaged over the two models is 2.9 x 10 -2 Sv -1 , significantly lower than the world average value of 5x10 -2 Sv -1 estimated by the ICRP. (author). 9 refs., 2 figs., 2 tabs

Synchronous Generator Model Parameter Estimation Based on Noisy Dynamic Waveforms

Science.gov (United States)

Berhausen, Sebastian; Paszek, Stefan

2016-01-01

In recent years, there have occurred system failures in many power systems all over the world. They have resulted in a lack of power supply to a large number of recipients. To minimize the risk of occurrence of power failures, it is necessary to perform multivariate investigations, including simulations, of power system operating conditions. To conduct reliable simulations, the current base of parameters of the models of generating units, containing the models of synchronous generators, is necessary. In the paper, there is presented a method for parameter estimation of a synchronous generator nonlinear model based on the analysis of selected transient waveforms caused by introducing a disturbance (in the form of a pseudorandom signal) in the generator voltage regulation channel. The parameter estimation was performed by minimizing the objective function defined as a mean square error for deviations between the measurement waveforms and the waveforms calculated based on the generator mathematical model. A hybrid algorithm was used for the minimization of the objective function. In the paper, there is described a filter system used for filtering the noisy measurement waveforms. The calculation results of the model of a 44 kW synchronous generator installed on a laboratory stand of the Institute of Electrical Engineering and Computer Science of the Silesian University of Technology are also given. The presented estimation method can be successfully applied to parameter estimation of different models of high-power synchronous generators operating in a power system.

Comparative estimates of risks arising from storage of intermediate level radioactive wastes

International Nuclear Information System (INIS)

Moore, D.

1986-04-01

Estimates are presented of risks arising from accidents occuring during storage of nine types of conditioned intermediate level waste. Additional data are introduced relating to the risks from accidents affecting raw waste, and to risks associated with the occupational doses received during normal operation of a waste store. Risks in all three categories are shown to be extremely small. (author)

Uncertainties in fatal cancer risk estimates used in radiation protection

International Nuclear Information System (INIS)

Kai, Michiaki

1999-01-01

Although ICRP and NCRP had not described the details of uncertainties in cancer risk estimates in radiation protection, NCRP, in 1997, firstly reported the results of uncertainty analysis (NCRP No.126) and which is summarized in this paper. The NCRP report pointed out that there are following five factors which uncertainty possessing: uncertainty in epidemiological studies, in dose assessment, in transforming the estimates to risk assessment, in risk prediction and in extrapolation to the low dose/dose rate. These individual factors were analyzed statistically to obtain the relationship between the probability of cancer death in the US population and life time risk coefficient (% per Sv), which showed that, for the latter, the mean value was 3.99 x 10 -2 /Sv, median, 3.38 x 10 -2 /Sv, GSD (geometrical standard deviation), 1.83 x 10 -2 /Sv and 95% confidential limit, 1.2-8.84 x 10 -2 /Sv. The mean value was smaller than that of ICRP recommendation (5 x 10 -2 /Sv), indicating that the value has the uncertainty factor of 2.5-3. Moreover, the most important factor was shown to be the uncertainty in DDREF (dose/dose rate reduction factor). (K.H.)

Risks of CIN 2+, CIN 3+, and Cancer by Cytology and Human Papillomavirus Status: The Foundation of Risk-Based Cervical Screening Guidelines.

Science.gov (United States)

Demarco, Maria; Lorey, Thomas S; Fetterman, Barbara; Cheung, Li C; Guido, Richard S; Wentzensen, Nicolas; Kinney, Walter K; Poitras, Nancy E; Befano, Brian; Castle, Philip E; Schiffman, Mark

2017-10-01

The next round of the American Society for Colposcopy and Cervical Pathology (ASCCP)-sponsored cervical cancer screening and management guidelines will recommend clinical actions based on risk, rather than test-based algorithms. This article gives preliminary risk estimates for the screening setting, showing combinations of the 2 most important predictors, human papillomavirus (HPV) status and cytology result. Among 1,262,713 women aged 25 to 77 years co-tested with HC2 (Qiagen) and cytology at Kaiser Permanente Northern California, we estimated 0-5-year cumulative risk of cervical intraepithelial neoplasia (CIN) 2+, CIN 3+, and cancer for combinations of cytology (negative for intraepithelial lesion or malignancy [NILM], atypical squamous cells of undetermined significance [ASC-US], low-grade squamous intraepithelial lesion [LSIL], atypical squamous cells cannot exclude HSIL [ASC-H], high-grade squamous intraepithelial lesion [HSIL], atypical glandular cells [AGC]) and HPV status. Ninety percent of screened women had HPV-negative NILM and an extremely low risk of subsequent cancer. Five-year risks of CIN 3+ were lower after HPV negativity (0.12%) than after NILM (0.25%). Among HPV-negative women, 5-year risks for CIN 3+ were 0.10% for NILM, 0.44% for ASC-US, 1.8% for LSIL, 3.0% for ASC-H, 1.2% for AGC, and 29% for HSIL+ cytology (which was very rare). Among HPV-positive women, 5-year risks were 4.0% for NILM, 6.8% for ASC-US, 6.1% for LSIL, 28% for ASC-H, 30% for AGC, and 50% for HSIL+ cytology. As a foundation for the next guidelines revision, we confirmed with additional precision the risk estimates previously reported for combinations of HPV and cytology. Future analyses will estimate risks for women being followed in colposcopy clinic and posttreatment and will consider the role of risk modifiers such as age, HPV vaccine status, HPV type, and screening and treatment history.

WEB-BASED INTERSPECIES CORRELATION ESTIMATION (WEB-ICE) FOR ACUTE TOXICITY: USER MANUAL V2

Science.gov (United States)

Predictive toxicological models are integral to environmental risk Assessment where data for most species are limited. Web-based Interspecies Correlation Estimation (Web-ICE) models are least square regressions that predict acute toxicity (LC50/LD50) of a chemical to a species, ...

Geostatistical risk estimation at waste disposal sites in the presence of hot spots

International Nuclear Information System (INIS)

Komnitsas, Kostas; Modis, Kostas

2009-01-01

The present paper aims to estimate risk by using geostatistics at the wider coal mining/waste disposal site of Belkovskaya, Tula region, in Russia. In this area the presence of hot spots causes a spatial trend in the mean value of the random field and a non-Gaussian data distribution. Prior to application of geostatistics, subtraction of trend and appropriate smoothing and transformation of the data into a Gaussian form were carried out; risk maps were then generated for the wider study area in order to assess the probability of exceeding risk thresholds. Finally, the present paper discusses the need for homogenization of soil risk thresholds regarding hazardous elements that will enhance reliability of risk estimation and enable application of appropriate rehabilitation actions in contaminated areas.

Estimating Longitudinal Risks and Benefits From Cardiovascular Preventive Therapies Among Medicare Patients: The Million Hearts Longitudinal ASCVD Risk Assessment Tool: A Special Report From the American Heart Association and American College of Cardiology.

Science.gov (United States)

Lloyd-Jones, Donald M; Huffman, Mark D; Karmali, Kunal N; Sanghavi, Darshak M; Wright, Janet S; Pelser, Colleen; Gulati, Martha; Masoudi, Frederick A; Goff, David C

2017-03-28

The Million Hearts Initiative has a goal of preventing 1 million heart attacks and strokes-the leading causes of mortality-through several public health and healthcare strategies by 2017. The American Heart Association and American College of Cardiology support the program. The Cardiovascular Risk Reduction Model was developed by Million Hearts and the Center for Medicare & Medicaid Services as a strategy to assess a value-based payment approach toward reduction in 10-year predicted risk of atherosclerotic cardiovascular disease (ASCVD) by implementing cardiovascular preventive strategies to manage the "ABCS" (aspirin therapy in appropriate patients, blood pressure control, cholesterol management, and smoking cessation). The purpose of this special report is to describe the development and intended use of the Million Hearts Longitudinal ASCVD Risk Assessment Tool. The Million Hearts Tool reinforces and builds on the "2013 ACC/AHA Guideline on the Assessment of Cardiovascular Risk" by allowing clinicians to estimate baseline and updated 10-year ASCVD risk estimates for primary prevention patients adhering to the appropriate ABCS over time, alone or in combination. The tool provides updated risk estimates based on evidence from high-quality systematic reviews and meta-analyses of the ABCS therapies. This novel approach to personalized estimation of benefits from risk-reducing therapies in primary prevention may help target therapies to those in whom they will provide the greatest benefit, and serves as the basis for a Center for Medicare & Medicaid Services program designed to evaluate the Million Hearts Cardiovascular Risk Reduction Model. Copyright © 2017 American Heart Association, Inc., and the American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Estimation of radiation cancer risk in CT-KUB

Science.gov (United States)

Karim, M. K. A.; Hashim, S.; Bakar, K. A.; Bradley, D. A.; Ang, W. C.; Bahrudin, N. A.; Mhareb, M. H. A.

2017-08-01

The increased demand for computed tomography (CT) in radiological scanning examinations raises the question of a potential health impact from the associated radiation exposures. Focusing on CT kidney-ureter-bladder (CT-KUB) procedures, this work was aimed at determining organ equivalent dose using a commercial CT dose calculator and providing an estimate of cancer risks. The study, which included 64 patients (32 males and 32 females, mean age 55.5 years and age range 30-80 years), involved use of a calibrated CT scanner (Siemens-Somatom Emotion 16-slice). The CT exposures parameter including tube potential, pitch factor, tube current, volume CT dose index (CTDIvol) and dose-length product (DLP) were recorded and analyzed using CT-EXPO (Version 2.3.1, Germany). Patient organ doses, including for stomach, liver, colon, bladder, red bone marrow, prostate and ovaries were calculated and converted into cancer risks using age- and sex-specific data published in the Biological Effects of Ionizing Radiation (BEIR) VII report. With a median value scan range of 36.1 cm, the CTDIvol, DLP, and effective dose were found to be 10.7 mGy, 390.3 mGy cm and 6.2 mSv, respectively. The mean cancer risks for males and females were estimated to be respectively 25 and 46 out of 100,000 procedures with effective doses between 4.2 mSv and 10.1 mSv. Given the increased cancer risks from current CT-KUB procedures compared to conventional examinations, we propose that the low dose protocols for unenhanced CT procedures be taken into consideration before establishing imaging protocols for CT-KUB.

Effect of Antihypertensive Therapy on SCORE-Estimated Total Cardiovascular Risk: Results from an Open-Label, Multinational Investigation—The POWER Survey

Directory of Open Access Journals (Sweden)

Guy De Backer

2013-01-01

Full Text Available Background. High blood pressure is a substantial risk factor for cardiovascular disease. Design & Methods. The Physicians' Observational Work on patient Education according to their vascular Risk (POWER survey was an open-label investigation of eprosartan-based therapy (EBT for control of high blood pressure in primary care centers in 16 countries. A prespecified element of this research was appraisal of the impact of EBT on estimated 10-year risk of a fatal cardiovascular event as determined by the Systematic Coronary Risk Evaluation (SCORE model. Results. SCORE estimates of CVD risk were obtained at baseline from 12,718 patients in 15 countries (6504 men and from 9577 patients at 6 months. During EBT mean (±SD systolic/diastolic blood pressures declined from 160.2 ± 13.7/94.1 ± 9.1 mmHg to 134.5 ± 11.2/81.4 ± 7.4 mmHg. This was accompanied by a 38% reduction in mean SCORE-estimated CVD risk and an improvement in SCORE risk classification of one category or more in 3506 patients (36.6%. Conclusion. Experience in POWER affirms that (a effective pharmacological control of blood pressure is feasible in the primary care setting and is accompanied by a reduction in total CVD risk and (b the SCORE instrument is effective in this setting for the monitoring of total CVD risk.

Effect of Antihypertensive Therapy on SCORE-Estimated Total Cardiovascular Risk: Results from an Open-Label, Multinational Investigation—The POWER Survey

Science.gov (United States)

De Backer, Guy; Petrella, Robert J.; Goudev, Assen R.; Radaideh, Ghazi Ahmad; Rynkiewicz, Andrzej; Pathak, Atul

2013-01-01

Background. High blood pressure is a substantial risk factor for cardiovascular disease. Design & Methods. The Physicians' Observational Work on patient Education according to their vascular Risk (POWER) survey was an open-label investigation of eprosartan-based therapy (EBT) for control of high blood pressure in primary care centers in 16 countries. A prespecified element of this research was appraisal of the impact of EBT on estimated 10-year risk of a fatal cardiovascular event as determined by the Systematic Coronary Risk Evaluation (SCORE) model. Results. SCORE estimates of CVD risk were obtained at baseline from 12,718 patients in 15 countries (6504 men) and from 9577 patients at 6 months. During EBT mean (±SD) systolic/diastolic blood pressures declined from 160.2 ± 13.7/94.1 ± 9.1 mmHg to 134.5 ± 11.2/81.4 ± 7.4 mmHg. This was accompanied by a 38% reduction in mean SCORE-estimated CVD risk and an improvement in SCORE risk classification of one category or more in 3506 patients (36.6%). Conclusion. Experience in POWER affirms that (a) effective pharmacological control of blood pressure is feasible in the primary care setting and is accompanied by a reduction in total CVD risk and (b) the SCORE instrument is effective in this setting for the monitoring of total CVD risk. PMID:23997946

Large-scale model-based assessment of deer-vehicle collision risk.

Directory of Open Access Journals (Sweden)

Torsten Hothorn

Full Text Available Ungulates, in particular the Central European roe deer Capreolus capreolus and the North American white-tailed deer Odocoileus virginianus, are economically and ecologically important. The two species are risk factors for deer-vehicle collisions and as browsers of palatable trees have implications for forest regeneration. However, no large-scale management systems for ungulates have been implemented, mainly because of the high efforts and costs associated with attempts to estimate population sizes of free-living ungulates living in a complex landscape. Attempts to directly estimate population sizes of deer are problematic owing to poor data quality and lack of spatial representation on larger scales. We used data on >74,000 deer-vehicle collisions observed in 2006 and 2009 in Bavaria, Germany, to model the local risk of deer-vehicle collisions and to investigate the relationship between deer-vehicle collisions and both environmental conditions and browsing intensities. An innovative modelling approach for the number of deer-vehicle collisions, which allows nonlinear environment-deer relationships and assessment of spatial heterogeneity, was the basis for estimating the local risk of collisions for specific road types on the scale of Bavarian municipalities. Based on this risk model, we propose a new "deer-vehicle collision index" for deer management. We show that the risk of deer-vehicle collisions is positively correlated to browsing intensity and to harvest numbers. Overall, our results demonstrate that the number of deer-vehicle collisions can be predicted with high precision on the scale of municipalities. In the densely populated and intensively used landscapes of Central Europe and North America, a model-based risk assessment for deer-vehicle collisions provides a cost-efficient instrument for deer management on the landscape scale. The measures derived from our model provide valuable information for planning road protection and defining

Automation of GIS-Based Population Data-Collection for Transportation Risk Analysis

International Nuclear Information System (INIS)

MILLS, G. SCOTT; NEUHAUSER, SIEGLINDE

1999-01-01

Estimation of the potential radiological risks associated with highway transport of radioactive materials (RAM) requires input data describing population densities adjacent to all portions of the route to be traveled. Previously, aggregated risks for entire multi-state routes were adequately estimated from population data with low geographic resolution. Current demands for geographically-specific risk estimates require similar increases in resolution of population density adjacent to route segments. With the advent of commercial geographic information systems (GISs) and databases describing highways, U.S. Census Blocks, and other information that is geographically distributed, it became feasible to determine and tabulate population characteristics along transportation routes with 1-kilometer resolution. This report describes an automated method of collecting population data adjacent to route segments (for calculation of incident-free doses) based on a commercial GIS. It also describes a statistical method of resolving remaining resolution issues, and an adaptation of the automation method to collection of data on population under a hypothetical plume of contamination resulting from a potential transportation accident

Stroke risk estimation across nine European countries in the MORGAM project

DEFF Research Database (Denmark)

Borglykke, Anders; Andreasen, Anne H; Kuulasmaa, Kari

2010-01-01

Previous tools for stroke risk assessment have either been developed for specific populations or lack data on non-fatal events or uniform data collection. The purpose of this study was to develop a stepwise model for the estimation of 10 year risk of stroke in nine different countries across Europe....

Joint Estimation of Cardiac Toxicity and Recurrence Risks After Comprehensive Nodal Photon Versus Proton Therapy for Breast Cancer

Energy Technology Data Exchange (ETDEWEB)

Stick, Line B., E-mail: line.bjerregaard.stick@regionh.dk [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Niels Bohr Institute, Faculty of Science, University of Copenhagen, Copenhagen (Denmark); Yu, Jen [Maryland Proton Treatment Center, University of Maryland School of Medicine, Baltimore, Maryland (United States); Maraldo, Maja V. [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Aznar, Marianne C. [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Nuffield Department of Population Health, University of Oxford, Oxford (United Kingdom); Pedersen, Anders N. [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Bentzen, Søren M. [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark); Maryland Proton Treatment Center, University of Maryland School of Medicine, Baltimore, Maryland (United States); Greenebaum Comprehensive Cancer Center and Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland (United States); Vogelius, Ivan R. [Department of Clinical Oncology, Rigshospitalet, University of Copenhagen, Copenhagen (Denmark)

2017-03-15

Purpose: The study aims to perform joint estimation of the risk of recurrence caused by inadequate radiation dose coverage of lymph node targets and the risk of cardiac toxicity caused by radiation exposure to the heart. Delivered photon plans are compared with realistic proton plans, thereby providing evidence-based estimates of the heterogeneity of treatment effects in consecutive cases for the 2 radiation treatment modalities. Methods and Materials: Forty-one patients referred for postlumpectomy comprehensive nodal photon irradiation for left-sided breast cancer were included. Comparative proton plans were optimized by a spot scanning technique with single-field optimization from 2 en face beams. Cardiotoxicity risk was estimated with the model of Darby et al, and risk of recurrence following a compromise of lymph node coverage was estimated by a linear dose-response model fitted to the recurrence data from the recently published EORTC (European Organisation for Research and Treatment of Cancer) 22922/10925 and NCIC-CTG (National Cancer Institute of Canada Clinical Trials Group) MA.20 randomized controlled trials. Results: Excess absolute risk of cardiac morbidity was small with photon therapy at an attained age of 80 years, with median values of 1.0% (range, 0.2%-2.9%) and 0.5% (range, 0.03%-1.0%) with and without cardiac risk factors, respectively, but even lower with proton therapy (0.13% [range, 0.02%-0.5%] and 0.06% [range, 0.004%-0.3%], respectively). The median estimated excess absolute risk of breast cancer recurrence after 10 years was 0.10% (range, 0.0%-0.9%) with photons and 0.02% (range, 0.0%-0.07%) with protons. The association between age of the patient and benefit from proton therapy was weak, almost non-existing (Spearman rank correlations of −0.15 and −0.30 with and without cardiac risk factors, respectively). Conclusions: Modern photon therapy yields limited risk of cardiac toxicity in most patients, but proton therapy can reduce the

View Estimation Based on Value System

Science.gov (United States)

Takahashi, Yasutake; Shimada, Kouki; Asada, Minoru

Estimation of a caregiver's view is one of the most important capabilities for a child to understand the behavior demonstrated by the caregiver, that is, to infer the intention of behavior and/or to learn the observed behavior efficiently. We hypothesize that the child develops this ability in the same way as behavior learning motivated by an intrinsic reward, that is, he/she updates the model of the estimated view of his/her own during the behavior imitated from the observation of the behavior demonstrated by the caregiver based on minimizing the estimation error of the reward during the behavior. From this view, this paper shows a method for acquiring such a capability based on a value system from which values can be obtained by reinforcement learning. The parameters of the view estimation are updated based on the temporal difference error (hereafter TD error: estimation error of the state value), analogous to the way such that the parameters of the state value of the behavior are updated based on the TD error. Experiments with simple humanoid robots show the validity of the method, and the developmental process parallel to young children's estimation of its own view during the imitation of the observed behavior of the caregiver is discussed.

Risk-based cost-benefit analysis for evaluating microbial risk mitigation in a drinking water system.

Science.gov (United States)

Bergion, Viktor; Lindhe, Andreas; Sokolova, Ekaterina; Rosén, Lars

2018-04-01

Waterborne outbreaks of gastrointestinal diseases can cause large costs to society. Risk management needs to be holistic and transparent in order to reduce these risks in an effective manner. Microbial risk mitigation measures in a drinking water system were investigated using a novel approach combining probabilistic risk assessment and cost-benefit analysis. Lake Vomb in Sweden was used to exemplify and illustrate the risk-based decision model. Four mitigation alternatives were compared, where the first three alternatives, A1-A3, represented connecting 25, 50 and 75%, respectively, of on-site wastewater treatment systems in the catchment to the municipal wastewater treatment plant. The fourth alternative, A4, represented installing a UV-disinfection unit in the drinking water treatment plant. Quantitative microbial risk assessment was used to estimate the positive health effects in terms of quality adjusted life years (QALYs), resulting from the four mitigation alternatives. The health benefits were monetised using a unit cost per QALY. For each mitigation alternative, the net present value of health and environmental benefits and investment, maintenance and running costs was calculated. The results showed that only A4 can reduce the risk (probability of infection) below the World Health Organization guidelines of 10 -4 infections per person per year (looking at the 95th percentile). Furthermore, all alternatives resulted in a negative net present value. However, the net present value would be positive (looking at the 50 th percentile using a 1% discount rate) if non-monetised benefits (e.g. increased property value divided evenly over the studied time horizon and reduced microbial risks posed to animals), estimated at 800-1200 SEK (€100-150) per connected on-site wastewater treatment system per year, were included. This risk-based decision model creates a robust and transparent decision support tool. It is flexible enough to be tailored and applied to local

Risk-based prioritization at Hanford Nuclear Site

International Nuclear Information System (INIS)

Hesser, W.A.; Mosely, M.T.

1995-11-01

This paper describes the method used to incorporate risk-based decision making into the Hanford resource allocation process. This method, the Revised Priority Planning Grid, is used as a tool to calculate benefits and benefit-to-cost ratios for comparison of environmental cleanup activities. The tool is based on Hanford Site objectives. Benefits are determined by estimating the impact on those objectives resulting from funding specific environmental management activities. Impacts are also a function of the weights associated with the objectives. These weights in the Revised Priority Planning Grid reflect US Development of Energy management values, which were obtained through a formal value-elicitation process. With modification to the objectives and weights, the Revised Priority Planning Grid could be used in different situations. By factoring in environmental, safety, and health risk and assigning higher scores to those activities that provide the most benefit, the Revised Priority Planning Grid is a reproducible, scientific way of scoring competing activities or interests

Earthquake insurance pricing: a risk-based approach.

Science.gov (United States)

Lin, Jeng-Hsiang

2018-04-01

Flat earthquake premiums are 'uniformly' set for a variety of buildings in many countries, neglecting the fact that the risk of damage to buildings by earthquakes is based on a wide range of factors. How these factors influence the insurance premiums is worth being studied further. Proposed herein is a risk-based approach to estimate the earthquake insurance rates of buildings. Examples of application of the approach to buildings located in Taipei city of Taiwan were examined. Then, the earthquake insurance rates for the buildings investigated were calculated and tabulated. To fulfil insurance rating, the buildings were classified into 15 model building types according to their construction materials and building height. Seismic design levels were also considered in insurance rating in response to the effect of seismic zone and construction years of buildings. This paper may be of interest to insurers, actuaries, and private and public sectors of insurance. © 2018 The Author(s). Disasters © Overseas Development Institute, 2018.

Estimating Risk of Natural Gas Portfolios by Using GARCH-EVT-Copula Model.

Science.gov (United States)

Tang, Jiechen; Zhou, Chao; Yuan, Xinyu; Sriboonchitta, Songsak

2015-01-01

This paper concentrates on estimating the risk of Title Transfer Facility (TTF) Hub natural gas portfolios by using the GARCH-EVT-copula model. We first use the univariate ARMA-GARCH model to model each natural gas return series. Second, the extreme value distribution (EVT) is fitted to the tails of the residuals to model marginal residual distributions. Third, multivariate Gaussian copula and Student t-copula are employed to describe the natural gas portfolio risk dependence structure. Finally, we simulate N portfolios and estimate value at risk (VaR) and conditional value at risk (CVaR). Our empirical results show that, for an equally weighted portfolio of five natural gases, the VaR and CVaR values obtained from the Student t-copula are larger than those obtained from the Gaussian copula. Moreover, when minimizing the portfolio risk, the optimal natural gas portfolio weights are found to be similar across the multivariate Gaussian copula and Student t-copula and different confidence levels.

Estimating Risk of Natural Gas Portfolios by Using GARCH-EVT-Copula Model

Directory of Open Access Journals (Sweden)

Jiechen Tang

2015-01-01

Full Text Available This paper concentrates on estimating the risk of Title Transfer Facility (TTF Hub natural gas portfolios by using the GARCH-EVT-copula model. We first use the univariate ARMA-GARCH model to model each natural gas return series. Second, the extreme value distribution (EVT is fitted to the tails of the residuals to model marginal residual distributions. Third, multivariate Gaussian copula and Student t-copula are employed to describe the natural gas portfolio risk dependence structure. Finally, we simulate N portfolios and estimate value at risk (VaR and conditional value at risk (CVaR. Our empirical results show that, for an equally weighted portfolio of five natural gases, the VaR and CVaR values obtained from the Student t-copula are larger than those obtained from the Gaussian copula. Moreover, when minimizing the portfolio risk, the optimal natural gas portfolio weights are found to be similar across the multivariate Gaussian copula and Student t-copula and different confidence levels.

Quantified Risk Ranking Model for Condition-Based Risk and Reliability Centered Maintenance

Science.gov (United States)

Chattopadhyaya, Pradip Kumar; Basu, Sushil Kumar; Majumdar, Manik Chandra

2017-06-01

In the recent past, risk and reliability centered maintenance (RRCM) framework is introduced with a shift in the methodological focus from reliability and probabilities (expected values) to reliability, uncertainty and risk. In this paper authors explain a novel methodology for risk quantification and ranking the critical items for prioritizing the maintenance actions on the basis of condition-based risk and reliability centered maintenance (CBRRCM). The critical items are identified through criticality analysis of RPN values of items of a system and the maintenance significant precipitating factors (MSPF) of items are evaluated. The criticality of risk is assessed using three risk coefficients. The likelihood risk coefficient treats the probability as a fuzzy number. The abstract risk coefficient deduces risk influenced by uncertainty, sensitivity besides other factors. The third risk coefficient is called hazardous risk coefficient, which is due to anticipated hazards which may occur in the future and the risk is deduced from criteria of consequences on safety, environment, maintenance and economic risks with corresponding cost for consequences. The characteristic values of all the three risk coefficients are obtained with a particular test. With few more tests on the system, the values may change significantly within controlling range of each coefficient, hence `random number simulation' is resorted to obtain one distinctive value for each coefficient. The risk coefficients are statistically added to obtain final risk coefficient of each critical item and then the final rankings of critical items are estimated. The prioritization in ranking of critical items using the developed mathematical model for risk assessment shall be useful in optimization of financial losses and timing of maintenance actions.

Area-level poverty and preterm birth risk: A population-based multilevel analysis

Science.gov (United States)

DeFranco, Emily A; Lian, Min; Muglia, Louis A; Schootman, Mario

2008-01-01

Background Preterm birth is a complex disease with etiologic influences from a variety of social, environmental, hormonal, genetic, and other factors. The purpose of this study was to utilize a large population-based birth registry to estimate the independent effect of county-level poverty on preterm birth risk. To accomplish this, we used a multilevel logistic regression approach to account for multiple co-existent individual-level variables and county-level poverty rate. Methods Population-based study utilizing Missouri's birth certificate database (1989–1997). We conducted a multilevel logistic regression analysis to estimate the effect of county-level poverty on PTB risk. Of 634,994 births nested within 115 counties in Missouri, two levels were considered. Individual-level variables included demographics factors, prenatal care, health-related behavioral risk factors, and medical risk factors. The area-level variable included the percentage of the population within each county living below the poverty line (US census data, 1990). Counties were divided into quartiles of poverty; the first quartile (lowest rate of poverty) was the reference group. Results PTB rate of PTB poverty and increased through the 4th quartile (4.9%), p poverty was significantly associated with PTB risk. PTB risk (poverty, adjusted odds ratio (adjOR) 1.18 (95% CI 1.03, 1.35), with a similar effect at earlier gestational ages (birth, above other underlying risk factors. Although the risk increase is modest, it affects a large number of pregnancies. PMID:18793437

The Additive Risk Model for Estimation of Effect of Haplotype Match in BMT Studies

DEFF Research Database (Denmark)

Scheike, Thomas; Martinussen, T; Zhang, MJ

2011-01-01

leads to a missing data problem. We show how Aalen's additive risk model can be applied in this setting with the benefit that the time-varying haplomatch effect can be easily studied. This problem has not been considered before, and the standard approach where one would use the expected-maximization (EM......) algorithm cannot be applied for this model because the likelihood is hard to evaluate without additional assumptions. We suggest an approach based on multivariate estimating equations that are solved using a recursive structure. This approach leads to an estimator where the large sample properties can...... be developed using product-integration theory. Small sample properties are investigated using simulations in a setting that mimics the motivating haplomatch problem....

Insulin sensitivity and mortality risk estimation in patients with type 2 ...

African Journals Online (AJOL)

Background: There is at present the dearth of information on the possible contribution of insulin resistance to scores obtained from mortality risk estimation in patients with type 2 diabetes mellitus (T2DM). Aim: This study determined the mortality risk scores in patients with T2DM and its relationship with insulin resistance.

Estimated cancer risk of dioxins to humans using a bioassay and physiologically based pharmacokinetic model

International Nuclear Information System (INIS)

Maruyama, Wakae; Aoki, Yasunobu

2006-01-01

The health risk of dioxins and dioxin-like compounds to humans was analyzed quantitatively using experimental data and mathematical models. To quantify the toxicity of a mixture of three dioxin congeners, we calculated the new relative potencies (REPs) for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 1,2,3,7,8-pentachlorodibenzo-p-dioxin (PeCDD), and 2,3,4,7,8- pentachlorodibenzofuran (PeCDF), focusing on their tumor promotion activity. We applied a liver foci formation assay to female SD rats after repeated oral administration of dioxins. The REP of dioxin for a rat was determined using dioxin concentration and the number of the foci in rat liver. A physiologically based pharmacokinetic model (PBPK model) was used for interspecies extrapolation targeting on dioxin concentration in liver. Toxic dose for human was determined by back-estimation with a human PBPK model, assuming that the same concentration in the target tissue may cause the same level of effect in rats and humans, and the REP for human was determined by the toxic dose obtained. The calculated REPs for TCDD, PeCDD, and PeCDF were 1.0, 0.34, and 0.05 for rats, respectively, and the REPs for humans were almost the same as those for rats. These values were different from the toxic equivalency factors (TEFs) presented previously (Van den Berg, M., Birnbaum, L., Bosveld, A.T.C., Brunstrom, B., Cook, P., Feeley, M., Giesy, J.P., Hanberg, A., Hasegawa, R., Kennedy, S.W., Kubiak, T., Larsen, J.C., Rolaf van Leeuwen, F.X., Liem, A.K.D., Nolt, C., Peterson, R.E., Poellinger. L., Safe, S., Schrenk, D., Tillitt, D, Tysklind, M., Younes, M., Waern, F., Zacharewski, T., 1998. Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environ. Health Perspect. 106, 775-792). The relative risk of excess liver cancer for Japanese people in general was 1.7-6.5 x 10 -7 by TCDD only, and 2.9-11 x 10 -7 by the three dioxins at the present level of contamination

Estimating Risk and Return Combinations for New Derivatives Funds

Directory of Open Access Journals (Sweden)

Alexandre Bona

2004-12-01

Full Text Available Active funds are typically managed by placing bets against a well defined passive bench-mark. In this context, when examining the launching of a new actively managed fund with a target expected excess rate of return relative to the benchmark equal to µ, asset managers face the problem of estimating the risk σ of excess rates of return. This estimate is critical to examine whether the product is commercially feasible and to define risk limits for the manager, if the product is launched. This paper proceeds to examine the solution to this problem assuming an especial form of the binomial model, in the context of the market timing structure advanced by Merton (1981. The paper shows that two variables are relevant for the solution of the proposed problem. The first, and the most relevant, is the skill level of the manager. A ore skilled manager is able to operate a less risky product with the same target excess rate of return µ. The second relevant variable is the trade-off between risk and return determined by existing investment opportunities in the market. The smaller the increases in risk exposure required to obtain an increase in excess returns, the less risky the product will be After solving the problem under specific assumptions, the paper proceeds to test empirically their validity using a representative sample of hedge funds in the Brazilian market. The empirical results strongly support the validity of the required assumptions.

Reliability of Nationwide Prevalence Estimates of Dementia: A Critical Appraisal Based on Brazilian Surveys.

Directory of Open Access Journals (Sweden)

Flávio Chaimowicz

Full Text Available The nationwide dementia prevalence is usually calculated by applying the results of local surveys to countries' populations. To evaluate the reliability of such estimations in developing countries, we chose Brazil as an example. We carried out a systematic review of dementia surveys, ascertained their risk of bias, and present the best estimate of occurrence of dementia in Brazil.We carried out an electronic search of PubMed, Latin-American databases, and a Brazilian thesis database for surveys focusing on dementia prevalence in Brazil. The systematic review was registered at PROSPERO (CRD42014008815. Among the 35 studies found, 15 analyzed population-based random samples. However, most of them utilized inadequate criteria for diagnostics. Six studies without these limitations were further analyzed to assess the risk of selection, attrition, outcome and population bias as well as several statistical issues. All the studies presented moderate or high risk of bias in at least two domains due to the following features: high non-response, inaccurate cut-offs, and doubtful accuracy of the examiners. Two studies had limited external validity due to high rates of illiteracy or low income. The three studies with adequate generalizability and the lowest risk of bias presented a prevalence of dementia between 7.1% and 8.3% among subjects aged 65 years and older. However, after adjustment for accuracy of screening, the best available evidence points towards a figure between 15.2% and 16.3%.The risk of bias may strongly limit the generalizability of dementia prevalence estimates in developing countries. Extrapolations that have already been made for Brazil and Latin America were based on a prevalence that should have been adjusted for screening accuracy or not used at all due to severe bias. Similar evaluations regarding other developing countries are needed in order to verify the scope of these limitations.

Estimate of person-years at risk among A-bomb survivors, Hiroshima and Nagasaki

Energy Technology Data Exchange (ETDEWEB)

Hrubec, Z

1964-11-19

Using information from the Supplementary Schedules of the 1950 National Census and from the JNIH-ABCC Life Span Study, cumulative person-years at risk in 1950 to 1960 were estimated by age ATB, sex, distance from hypocenter, radiation dose and symptoms for A-bomb survivors resident in Hiroshima and Nagasaki cities. The number of person-years at risk in 1951 to 1958 was estimated by applying the survivorship in each age group of the Adult Health Study sample during the period 1951 to 1958 to the number of survivors in 1950. To determine the number of person-years at risk from 1959 to 1960, the average yearly loss was evaluated for each exposure group for the period 1955 to 1958 in Hiroshima and for 1953 to 1958 in Nagasaki which was then applied to 1959 and 1960, respectively. The estimate of person-years among the nonexposed groups for this period was obtained from the above estimates, the total population of both cities, and the number of persons born after the A-bombing. Estimates by other associated factors were obtained by the same procedure. 20 references, 25 tables.

Uncertainty analysis in vulnerability estimations for elements at risk- a review of concepts and some examples on landslides

Science.gov (United States)

Ciurean, R. L.; Glade, T.

2012-04-01

Decision under uncertainty is a constant of everyday life and an important component of risk management and governance. Recently, experts have emphasized the importance of quantifying uncertainty in all phases of landslide risk analysis. Due to its multi-dimensional and dynamic nature, (physical) vulnerability is inherently complex and the "degree of loss" estimates imprecise and to some extent even subjective. Uncertainty analysis introduces quantitative modeling approaches that allow for a more explicitly objective output, improving the risk management process as well as enhancing communication between various stakeholders for better risk governance. This study presents a review of concepts for uncertainty analysis in vulnerability of elements at risk to landslides. Different semi-quantitative and quantitative methods are compared based on their feasibility in real-world situations, hazard dependency, process stage in vulnerability assessment (i.e. input data, model, output), and applicability within an integrated landslide hazard and risk framework. The resulted observations will help to identify current gaps and future needs in vulnerability assessment, including estimation of uncertainty propagation, transferability of the methods, development of visualization tools, but also address basic questions like what is uncertainty and how uncertainty can be quantified or treated in a reliable and reproducible way.

Observer-Based Human Knee Stiffness Estimation.

Science.gov (United States)

Misgeld, Berno J E; Luken, Markus; Riener, Robert; Leonhardt, Steffen

2017-05-01

We consider the problem of stiffness estimation for the human knee joint during motion in the sagittal plane. The new stiffness estimator uses a nonlinear reduced-order biomechanical model and a body sensor network (BSN). The developed model is based on a two-dimensional knee kinematics approach to calculate the angle-dependent lever arms and the torques of the muscle-tendon-complex. To minimize errors in the knee stiffness estimation procedure that result from model uncertainties, a nonlinear observer is developed. The observer uses the electromyogram (EMG) of involved muscles as input signals and the segmental orientation as the output signal to correct the observer-internal states. Because of dominating model nonlinearities and nonsmoothness of the corresponding nonlinear functions, an unscented Kalman filter is designed to compute and update the observer feedback (Kalman) gain matrix. The observer-based stiffness estimation algorithm is subsequently evaluated in simulations and in a test bench, specifically designed to provide robotic movement support for the human knee joint. In silico and experimental validation underline the good performance of the knee stiffness estimation even in the cases of a knee stiffening due to antagonistic coactivation. We have shown the principle function of an observer-based approach to knee stiffness estimation that employs EMG signals and segmental orientation provided by our own IPANEMA BSN. The presented approach makes realtime, model-based estimation of knee stiffness with minimal instrumentation possible.

A Comparison Study on the Integrated Risk Estimation for Various Power Systems

International Nuclear Information System (INIS)

Kim, Tae Woon; Ha, J. J.; Kim, S. H.; Jeong, J. T.; Min, K. R.; Kim, K. Y.

2007-06-01

The objective of this study is to establish a system for the comparative analysis of the environmental impacts, risks, health effects, and social acceptance for various electricity generation systems and a computational framework and necessary databases. In this study, the second phase of the nuclear research and development program(2002-2004), the methodologies for the comparative analysis of the environmental impacts, risks, and health effects for various electricity generation systems was investigated and applied to reference power plants. The life cycle assessment (LCA) methodology as a comparative analysis tool for the environmental impacts was adopted and applied to fossil-fueled and nuclear power plants. The scope of the analysis considered in this study are the construction, operation/fuel cycle), and demolition of each power generation system. In the risk analysis part, the empirical and analytical methods were adopted and applied to fossil-fueled and nuclear power plants. In the empirical risk assessment part, we collected historical experiences of worldwide energy-related accidents with fatalities over the last 30 years. The scope of the analysis considered in this study are the construction, operation (fuel cycle), and demolition stages of each power generation systems. The risks for the case of nuclear power plants which have potential releases of radioactive materials were estimated In a probabilistic way (PSA) by considering the occurrence of severe accidents and compared with the risks of other electricity generation systems. The health effects testimated as external cost) resulting from the operation of nuclear, coal, and hydro power systems were estimated and compared by using the program developed by the IAEA. Regarding a comprehensive comparison of the various power systems, the analytic hierarchy process (AHP) method is introduced to aggregate the diverse information under conflicting decision criteria. Social aspect is treated by a web-based

Risk and size estimation of debris flow caused by storm rainfall in mountain regions

Institute of Scientific and Technical Information of China (English)

CHENG; Genwei

2003-01-01

Debris flow is a common disaster in mountain regions. The valley slope, storm rainfall and amassed sand-rock materials in a watershed may influence the types of debris flow. The bursting of debris flow is not a pure random event. Field investigations show the periodicity of its burst, but no directive evidence has been found yet. A risk definition of debris flow is proposed here based upon the accumulation and the starting conditions of loose material in channel. According to this definition, the risk of debris flow is of quasi-periodicity. A formula of risk estimation is derived. Analysis of relative factors reveals the relationship between frequency and size of debris flow. For a debris flow creek, the longer the time interval between two occurrences of debris flows is, the bigger the bursting event will be.