WorldWideScience

Sample records for optimal risk sharing

  1. Game-theoretic approaches to optimal risk sharing

    NARCIS (Netherlands)

    Boonen, T.J.

    2014-01-01

    This Ph.D. thesis studies optimal risk capital allocation and optimal risk sharing. The first chapter deals with the problem of optimally allocating risk capital across divisions within a financial institution. To do so, an asymptotic approach is used to generalize the well-studied Aumann-Shapley

  2. Optimal sharing of quantity risk for a coalition of wind power producers facing nodal prices

    KAUST Repository

    Bitar, E. Y.; Baeyens, E.; Khargonekar, P. P.; Poolla, K.; Varaiya, P.

    2012-01-01

    It is widely accepted that aggregation of geographically diverse wind energy resources offers compelling potential to mitigate wind power variability, as wind speed at different geographic locations tends to decorrelate with increasing spatial separation. In this paper, we explore the extent to which a coalition of wind power producers can exploit the statistical benefits of aggregation to mitigate the risk of quantity shortfall with respect to forward contract offerings for energy. We propose a simple augmentation of the existing two-settlement market system with nodal pricing to permit quantity risk sharing among wind power producers by affording the group a recourse opportunity to utilize improved forecasts of their ensuing wind energy production to collectively modify their forward contracted positions so as to utilize the projected surplus in generation at certain buses to balance the projected shortfall in generation at complementary buses. Working within this framework, we show that the problem of optimally sizing a set of forward contracts for a group of wind power producers reduces to convex programming and derive closed form expressions for the set of optimal recourse policies. We also asses the willingness of individual wind power producers to form a coalition to cooperatively offer contracts for energy. We first show that the expected profit derived from coalitional contract offerings with recourse is greater than that achievable through independent contract offerings. And, using tools from coalitional game theory, we show that the core for our game is non-empty.

  3. Optimal sharing of quantity risk for a coalition of wind power producers facing nodal prices

    KAUST Repository

    Bitar, E. Y.

    2012-06-01

    It is widely accepted that aggregation of geographically diverse wind energy resources offers compelling potential to mitigate wind power variability, as wind speed at different geographic locations tends to decorrelate with increasing spatial separation. In this paper, we explore the extent to which a coalition of wind power producers can exploit the statistical benefits of aggregation to mitigate the risk of quantity shortfall with respect to forward contract offerings for energy. We propose a simple augmentation of the existing two-settlement market system with nodal pricing to permit quantity risk sharing among wind power producers by affording the group a recourse opportunity to utilize improved forecasts of their ensuing wind energy production to collectively modify their forward contracted positions so as to utilize the projected surplus in generation at certain buses to balance the projected shortfall in generation at complementary buses. Working within this framework, we show that the problem of optimally sizing a set of forward contracts for a group of wind power producers reduces to convex programming and derive closed form expressions for the set of optimal recourse policies. We also asses the willingness of individual wind power producers to form a coalition to cooperatively offer contracts for energy. We first show that the expected profit derived from coalitional contract offerings with recourse is greater than that achievable through independent contract offerings. And, using tools from coalitional game theory, we show that the core for our game is non-empty.

  4. Incentivizing intelligent customer behavior in smart-grids: a risk-sharing tariff & optimal strategies

    NARCIS (Netherlands)

    G. Methenitis (Georgios); M. Kaisers (Michael); J.A. La Poutré (Han)

    2016-01-01

    textabstractCurrent electricity tariffs for retail rarely provide incentives for intelligent demand response of flexible customers. Such customers could otherwise contribute to balancing supply and demand in future smart grids. This paper proposes an innovative risk-sharing tariff to incentivize

  5. How to share our risks efficiently? Principles for optimal social insurance and pension provision

    NARCIS (Netherlands)

    Teulings, C.N.

    2010-01-01

    The efficient organisation of social insurance is an important problem for modern societies. The paper discusses evidence that shocks in labour income have largely persistent effects and analyses the implications of this observation for the optimal design of institutions for wage contracting, social

  6. Globalization and Risk Sharing

    OpenAIRE

    Jaume Ventura; Fernando A. Broner

    2006-01-01

    We study the effects of globalization on risk sharing and welfare. Like the previous literature, we assume that governments cannot commit to enforce the repayment of debts owed by their citizens. Unlike the previous literature, we assume that governments cannot discriminate between domestic and foreign creditors when enforcing debt payments. This creates novel interactions between domestic and international trade in assets. (i) Increases in domestic trade raise the benefits of enforcement and...

  7. The Political Economy of Intergenerational Risk Sharing

    NARCIS (Netherlands)

    Hollanders, D.A.

    2010-01-01

    This paper analyses the political constraints of intergenerational risk sharing. The rst result is that the political process generally does not lead to ex ante optimal insurance. The second result is that in a second best political setting PAYG still contributes to intergenerational risk sharing.

  8. Facilitating Shared Understandings of Risk

    DEFF Research Database (Denmark)

    Mitchell, Robb

    This thesis contributes an identification of a key mechanism and its constituent qualities, for facilitating shared understandings of risk. Globalisation and the pace of technological change increases the uncertainties of decision making within many design and innovation practices. Accordingly......, the focus of participatory workshops has expanded towards addressing broader questions of strategy, business models and other organizational and inter-organisational issues. To develop effective partnerships across the boundaries separating companies, I argue that is necessary for those involved to gain...... or proxy for absent others, 4) an incomplete comic with which children could contribute sketched ideas to a design process 5) a table top tool kits for discussing business relationship issues and 5) a number of bespoke interactive sculpture-like artifacts for provoking insights concerning business dilemmas...

  9. Risk taking and risk sharing does responsibility matter?

    NARCIS (Netherlands)

    Cettolin, E.; Tausch, F.

    2013-01-01

    Risk sharing arrangements diminish individuals’ vulnerability to probabilistic events that negatively affect their financial situation. This is because risk sharing implies redistribution, as lucky individuals support the unlucky ones. We hypothesize that responsibility for risky choices decreases

  10. Risk taking and risk sharing : does responsibility matter?

    NARCIS (Netherlands)

    Cettolin, Elena; Tausch, Franziska

    Risk sharing arrangements diminish individuals’ vulnerability to probabilistic events that negatively affect their financial situation. This is because risk sharing implies redistribution, as lucky individuals support the unlucky ones. We hypothesize that responsibility for risky choices decreases

  11. Contract of Shared Risk. New investment opportunities

    International Nuclear Information System (INIS)

    Carta Petrolera

    1997-01-01

    In order to offering to the private capital, new investment opportunities in exploration and production in Colombia, ECOPETROL settled down since 1996 the Contract of Shared Risk. This is a novel recruiting modality, because the shared risk is applied to the exploratory areas that are assigned for the direct operation of ECOPETROL

  12. Risk sharing relations and enforcement mechanisms

    NARCIS (Netherlands)

    Barr, A.; Dekker, M.; Fafchamps, M.

    2008-01-01

    We investigate whether the set of available enforcement mechanisms affects the formation of risk sharing relations by applying dyadic regression analysis to data from a specifically designed behavioural experiment, two surveys and a genealogical mapping exercise. During the experiment participants

  13. Framework for Shared Drinking Water Risk Assessment.

    Energy Technology Data Exchange (ETDEWEB)

    Lowry, Thomas Stephen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tidwell, Vincent C. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Peplinski, William John [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Mitchell, Roger [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Binning, David [AEM Corp., Herndon, VA (United States); Meszaros, Jenny [AEM Corp., Herndon, VA (United States)

    2017-01-01

    Central to protecting our nation's critical infrastructure is the development of methodologies for prioritizing action and supporting resource allocation decisions associated with risk-reduction initiatives. Toward this need a web-based risk assessment framework that promotes the anonymous sharing of results among water utilities is demonstrated. Anonymous sharing of results offers a number of potential advantages such as assistance in recognizing and correcting bias, identification of 'unknown, unknowns', self-assessment and benchmarking for the local utility, treatment of shared assets and/or threats across multiple utilities, and prioritization of actions beyond the scale of a single utility. The constructed framework was demonstrated for three water utilities. Demonstration results were then compared to risk assessment results developed using a different risk assessment application by a different set of analysts.

  14. Sharing of risks in Islamic finance

    OpenAIRE

    Sekreter, Ahmet

    2011-01-01

    For most of the people the prohibition on interest is the well known part of Islamic finance. Indeed, the concept of Islamic finance was not being discussed enough till financial crisis, after crisis it started to be seen as an alternative financial system for conventional finance. Sharing the risks is the main concept of Islamic finance and one of the main differences between conventional and Islamic finance. Depositors/savers do not bear any risk in conventional finance however Islamic fina...

  15. Risk-sharing agreements in the EU

    DEFF Research Database (Denmark)

    Traulsen, Janine Marie; Traulsen, Janine Marie; Holm-Larsen, Tove

    2017-01-01

    Abstract Objective Our objectives were to explore the changes in the level of interest in risk-sharing agreements (RSAs) in the EU during the last 15 years and the underlying reasons for these changes. Methods A systematic literature review was conducted using PubMed, Scopus, Web of Science...

  16. Pension systems, intergenerational risk sharing and inflation

    NARCIS (Netherlands)

    Beetsma, R.M.W.J.; Bovenberg, A.L.

    2006-01-01

    We investigate intergenerational risk sharing in two-pillar pension systems with a pay-as-you-go pillar and a funded pillar. We consider shocks in productivity, depreciation of capital and inflation. The funded pension pillar can be either defined contribution or defined benefit, with benefits

  17. [Risk sharing methods in middle income countries].

    Science.gov (United States)

    Inotai, András; Kaló, Zoltán

    2012-01-01

    The pricing strategy of innovative medicines is based on the therapeutic value in the largest pharmaceutical markets. The cost-effectiveness of new medicines with value based ex-factory price is justifiable. Due to the international price referencing and parallel trade the ex-factory price corridor of new medicines has been narrowed in recent years. Middle income countries have less negotiation power to change the narrow drug pricing corridor, although their fair intention is to buy pharmaceuticals at lower price from their scarce public resources compared to higher income countries. Therefore the reimbursement of new medicines at prices of Western-European countries may not be justifiable in Central-Eastern European countries. Confidential pricing agreements (i.e. confidential price discounts, claw-back or rebate) in lower income countries of the European Union can alleviate this problem, as prices of new medicines can be adjusted to local purchasing power without influencing the published ex-factory price and so the accessibility of patients to these drugs in other countries. In order to control the drug budget payers tend to apply financial risk sharing agreements for new medicines in more and more countries to shift the consequences of potential overspending to pharmaceutical manufacturers. The major paradox of financial risk-sharing schemes is that increased mortality, poor persistence of patients, reduced access to healthcare providers, and no treatment reduce pharmaceutical spending. Consequently, payers have started to apply outcome based risk sharing agreements for new medicines recently to improve the quality of health care provision. Our paper aims to review and assess the published financial and outcome based risk sharing methods. Introduction of outcome based risk-sharing schemes can be a major advancement in the drug reimbursement strategy of payers in middle income countries. These schemes can help to reduce the medical uncertainty in coverage

  18. 24 CFR 266.15 - Risk-Sharing Agreement.

    Science.gov (United States)

    2010-04-01

    ... HOUSING FINANCE AGENCY RISK-SHARING PROGRAM FOR INSURED AFFORDABLE MULTIFAMILY PROJECT LOANS General Provisions § 266.15 Risk-Sharing Agreement. Execution of a Risk-Sharing Agreement is a prerequisite to... 24 Housing and Urban Development 2 2010-04-01 2010-04-01 false Risk-Sharing Agreement. 266.15...

  19. Risk Management Collaboration through Sharing Interactive Graphics

    Science.gov (United States)

    Slingsby, Aidan; Dykes, Jason; Wood, Jo; Foote, Matthew

    2010-05-01

    Risk management involves the cooperation of scientists, underwriters and actuaries all of whom analyse data to support decision-making. Results are often disseminated through static documents with graphics that convey the message the analyst wishes to communicate. Interactive graphics are increasingly popular means of communicating the results of data analyses because they enable other parties to explore and visually analyse some of the data themselves prior to and during discussion. Discussion around interactive graphics can occur synchronously in face-to-face meetings or with video-conferencing and screen sharing or they can occur asynchronously through web-sites such as ManyEyes, web-based fora, blogs, wikis and email. A limitation of approaches that do not involve screen sharing is the difficulty in sharing the results of insights from interacting with the graphic. Static images accompanied can be shared but these themselves cannot be interacted, producing a discussion bottleneck (Baker, 2008). We address this limitation by allowing the state and configuration of graphics to be shared (rather than static images) so that a user can reproduce someone else's graphic, interact with it and then share the results of this accompanied with some commentary. HiVE (Slingsby et al, 2009) is a compact and intuitive text-based language that has been designed for this purpose. We will describe the vizTweets project (a 9-month project funded by JISC) in which we are applying these principles to insurance risk management in the context of the Willis Research Network, the world's largest collaboration between the insurance industry and the academia). The project aims to extend HiVE to meet the needs of the sector, design, implement free-available web services and tools and to provide case studies. We will present a case study that demonstrate the potential of this approach for collaboration within the Willis Research Network. Baker, D. Towards Transparency in Visualisation Based

  20. Optimizing Knowledge Sharing in Learning Networks through Peer Tutoring

    NARCIS (Netherlands)

    Hsiao, Amy; Brouns, Francis; Kester, Liesbeth; Sloep, Peter

    2009-01-01

    Hsiao, Y. P., Brouns, F., Kester, L., & Sloep, P. (2009). Optimizing Knowledge Sharing in Learning Networks through Peer Tutoring. Presentation at the IADIS international conference on Cognition and Exploratory in Digital Age (CELDA 2009). November, 20-22, 2009, Rome, Italy.

  1. Optimizing Knowledge Sharing In Learning Networks Through Peer Tutoring

    NARCIS (Netherlands)

    Hsiao, Amy; Brouns, Francis; Kester, Liesbeth; Sloep, Peter

    2009-01-01

    Hsiao, Y. P., Brouns, F., Kester, L., & Sloep, P. B. (2009). Optimizing Knowledge Sharing In Learning Networks Through Peer Tutoring. In D. Kinshuk, J. Sampson, J. Spector, P. Isaías, P. Barbosa & D. Ifenthaler (Eds.). Proceedings of IADIS International Conference Cognition and Exploratory Learning

  2. Load Sharing Multiobjective Optimization Design of a Split Torque Helicopter Transmission

    Directory of Open Access Journals (Sweden)

    Chenxi Fu

    2015-01-01

    Full Text Available Split torque designs can offer significant advantages over the traditional planetary designs for helicopter transmissions. However, it has two unique properties, gap and phase differences, which result in the risk of unequal load sharing. Various methods have been proposed to eliminate the effect of gap and promote load sharing to a certain extent. In this paper, system design parameters will be optimized to change the phase difference, thereby further improving load sharing. A nonlinear dynamic model is established to measure the load sharing with dynamic mesh forces quantitatively. Afterwards, a multiobjective optimization of a reference split torque design is conducted with the promoting of load sharing property, lightweight, and safety considered as the objectives. The load sharing property, which is measured by load sharing coefficient, is evaluated under multiple operating conditions with dynamic analysis method. To solve the multiobjective model with NSGA-II, an improvement is done to overcome the problem of time consuming. Finally, a satisfied optimal solution is picked up as the final design from the Pareto optimal front, which achieves improvements in all the three objectives compared with the reference design.

  3. Risk modelling in portfolio optimization

    Science.gov (United States)

    Lam, W. H.; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi

    2013-09-01

    Risk management is very important in portfolio optimization. The mean-variance model has been used in portfolio optimization to minimize the investment risk. The objective of the mean-variance model is to minimize the portfolio risk and achieve the target rate of return. Variance is used as risk measure in the mean-variance model. The purpose of this study is to compare the portfolio composition as well as performance between the optimal portfolio of mean-variance model and equally weighted portfolio. Equally weighted portfolio means the proportions that are invested in each asset are equal. The results show that the portfolio composition of the mean-variance optimal portfolio and equally weighted portfolio are different. Besides that, the mean-variance optimal portfolio gives better performance because it gives higher performance ratio than the equally weighted portfolio.

  4. Optimizing risk management

    International Nuclear Information System (INIS)

    Kindred, G.W.

    2000-01-01

    Commercial nuclear power plant management is focussed on the safe, efficient, economical production of electricity. To accomplish the safe aspect of the equation, risk must be determined for the operation and maintenance of the facility. To accomplish the efficient aspect of the equation, management must understand those risks and factor risk insights into their decision process. The final piece of the equation is economical which is accomplished by minimizing, plant outage durations and proper utilization of resources. Probabilistic Risk Assessment can provide the risk insights to accomplish all three; safety, efficiency, and economically. How? Safe production of electricity can be quantified by use of PRA modeling and other risk insights that can determine the core damage frequency. Efficient production of electricity can be influenced by providing management with quantified risk insights for use in decision making. And, one example of economical production of electricity is by not having over conservative deterministic based defense in depth approaches to system maintenance and availability. By using risk-informed insights nuclear safety can be quantified and risk can be managed. Confidence in this approach can be achieved by ensuring the content and quality of the PRA is standardized throughout the industry. The time has arrived for Probabilistic Risk Assessment to take an active position as a major role player in the safe, efficient, and economical operation of commercial nuclear power plants. (author)

  5. Risk Aversion and Engagement in the Sharing Economy

    Directory of Open Access Journals (Sweden)

    Jessica Santana

    2015-10-01

    Full Text Available The sharing economy is a new online community that has important implications for offline behavior. This study evaluates whether engagement in the sharing economy is associated with an actor’s aversion to risk. Using a web-based survey and a field experiment, we apply an adaptation of Holt and Laury’s (2002 risk lottery game to a representative sample of sharing economy participants. We find that frequency of activity in the sharing economy predicts risk aversion, but only in interaction with satisfaction. While greater satisfaction with sharing economy websites is associated with a decrease in risk aversion, greater frequency of usage is associated with greater risk aversion. This analysis shows the limitations of a static perspective on how risk attitudes relate to participation in the sharing economy.

  6. Model Risk in Portfolio Optimization

    Directory of Open Access Journals (Sweden)

    David Stefanovits

    2014-08-01

    Full Text Available We consider a one-period portfolio optimization problem under model uncertainty. For this purpose, we introduce a measure of model risk. We derive analytical results for this measure of model risk in the mean-variance problem assuming we have observations drawn from a normal variance mixture model. This model allows for heavy tails, tail dependence and leptokurtosis of marginals. The results show that mean-variance optimization is seriously compromised by model uncertainty, in particular, for non-Gaussian data and small sample sizes. To mitigate these shortcomings, we propose a method to adjust the sample covariance matrix in order to reduce model risk.

  7. The Foreign Investment Risks of Chinese B Share Market

    OpenAIRE

    JIANG, MINCHANG

    2014-01-01

    The objective of this dissertation is to investigate and analyse the risks existing in Chinese B share market for foreign investment. Based on the brief history of B share market as well as background information such as characteristics of Chinese stock exchange, several areas of risks are identified as: macroeconomic risks, stock volatility and return including cross-impacts among market segmentations and different countries’ markets, financial market and currency risks, and finally the poli...

  8. Egalitarian Risk Sharing under Liquidity Constraints

    NARCIS (Netherlands)

    Koster, M.; Boonen, T.

    2014-01-01

    Undertaking joint projects in practice involves a lot of uncertainty, especially when it comes to the final costs. This paper addresses the problem of sharing realized costs by the participants, subject to their indvidual liquidity constraints. If all cost levels can be accounted for, and it the

  9. Risk sharing, public policy and the contribution of Islamic finance

    Directory of Open Access Journals (Sweden)

    Hossein Askari

    2014-12-01

    Full Text Available A major reason for the recurrent episodes of financial instability is the predominance of interest-based debt and leveraging. Financial stability is achievable through risk sharing finance instead of risk shifting that characterizes contemporary finance. A risk sharing system serves the true function of finance as facilitator of real sector activities and avoids the emergence of a “paper economy” where there is gradual decoupling of finance from the real sector. Islamic finance was initially proposed as a profit-loss sharing system, but its core principle is risk sharing. In prohibiting interest-based debt instruments, Islam grounds finance on a strong risk sharing footing. Although still a young industry that has come a long way, it has not managed to develop truly risk-sharing instruments that would allow individuals, households, and firms as well as whole economies to mitigate systematic and un-systematic risks. It is suggested that governments should intervene and issue macro-market instruments to provide their treasuries with a significant source of non-interest rate based financing while promoting risk sharing. Moreover, given that evidence across the world suggests that monetary policy’s transmission mechanism may be impaired, it is suggested that these government issued securities could also impart added potency to monetary policy.

  10. Online Information Sharing About Risks: The Case of Organic Food.

    Science.gov (United States)

    Hilverda, Femke; Kuttschreuter, Margôt

    2018-03-23

    Individuals have to make sense of an abundance of information to decide whether or not to purchase certain food products. One of the means to sense-making is information sharing. This article reports on a quantitative study examining online information sharing behavior regarding the risks of organic food products. An online survey among 535 respondents was conducted in the Netherlands to examine the determinants of information sharing behavior, and their relationships. Structural equation modeling was applied to test both the measurement model and the structural model. Results showed that the intention to share information online about the risks of organic food was low. Conversations and email were the preferred channels to share information; of the social media Facebook stood out. The developed model was found to provide an adequate description of the data. It explained 41% of the variance in information sharing. Injunctive norms and outcome expectancies were most important in predicting online information sharing, followed by information-related determinants. Risk-perception-related determinants showed a significant, but weak, positive relationship with online information sharing. Implications for authorities communicating on risks associated with food are addressed. © 2018 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

  11. Petroleum tax systems and risk sharing

    International Nuclear Information System (INIS)

    Sunnevaag, K.

    1992-12-01

    We have focused on four different measures of risk, well known from the finance literature, namely sensitivity, standard deviation, coefficient of variation and finally probability of a negative expected net present value (NPV). While the two first measures show that the state carries most of the risk, the latter measures show the opposite result. Whether or not the project is developed on a stand-alone or on-going basis, has a crucial impact on much risk the company carries. We have also looked at the risk development as a consequence of changes in tax regime. While the two first measures of risk (sensitivity and standard deviation) show an increase in risk for the company from the pre 1987 tax regime to the 1987-1991 tax regime, and a decrease in risk as a consequence of the last change, the opposite is the case when we look at the two last measures of risk, namely coefficient of variation and probability of a negative expected NPV. The same is the conclusion for the state, except that the sign of change is the opposite that of the company. This analysis could have been extended to include a risk concept based on the well known Capital Asset Pricing Model, which is relevant risk, or covariance risk. This model concludes that the return on any risky asset is a function of the correlation between the return on this asset and the market portfolio. In this case only the projects contribution to the portfolio risk should be accounted for. For the Norwegian state it is not unreasonable to assume that the risk contribution of a medium sized oil field to a big portfolio of fields and onshore activities only is marginal. For the national or international oil company it is somewhat less marginal, and for a company developing the field on a stand-alone basis it is substantial. 12 refs., 15 figs

  12. Risk taking and risk sharing: does responsibility matter? (RM/13/045-revised-)

    NARCIS (Netherlands)

    Cettolin, Elena; Tausch, Franziska

    2016-01-01

    Risk sharing arrangements diminish individuals’ vulnerability to probabilistic events that negatively affect their financial situation. This is because risk sharing implies redistribution, as lucky individuals support the unlucky ones. We hypothesize that responsibility for risky choices decreases

  13. Modifiable risk factors for prescription medicine sharing behaviours.

    Science.gov (United States)

    Beyene, Kebede; Aspden, Trudi; McNeill, Rob; Sheridan, Janie

    2018-04-06

    Prescription medicine sharing has been defined as giving one's own medicine to someone else (lending) or taking someone else's medicine (borrowing). Medicines can be shared for non-medical purposes (recreational sharing or drug abuse) or for their intended therapeutic benefits (non-recreational sharing, e.g. sharing antibiotics to self-treat); the latter is the focus of this research. Limited research evidence is available about modifiable risk factors for non-recreational medicine sharing and addressing this issue was the main aim of this research. An online, cross-sectional survey design was used. The study population comprised a convenience sample of 233 adults, who were primarily recruited through patient support groups across New Zealand. Principal component analysis was used to develop scales assessing attitudes toward medicine lending and borrowing. Logistic regression was used to examine the relationship between explanatory (demographics, medical conditions, and attitudes towards medicine sharing) and outcome (medicine sharing behaviours) variables. Half of the study participants reported ever borrowing/lending medicines, and approximately a third of participants reported borrowing/lending in the past year. Modifiable risk factors associated with an increased risk of medicine borrowing behaviour were having more difficulty with accessing medicine ('access-related issue'), stronger 'emotional beliefs about borrowing', and greater 'concern about missing doses.' Greater 'concern for the wellbeing of others' and stronger 'beliefs about the benefits and safety of lending' were associated with an increased risk of medicine lending behaviour. Those with a higher 'perceived risk of harm' were less likely to borrow or lend medicines. This research expands the current knowledge of medicine sharing by examining underlying behavioural factors which predict sharing behaviours and that can be modified by interventions. This research suggests using multifaceted

  14. Online Information Sharing About Risks : The Case of Organic Food

    NARCIS (Netherlands)

    Hilverda, Femke; Kuttschreuter, Margôt

    2018-01-01

    Individuals have to make sense of an abundance of information to decide whether or not to purchase certain food products. One of the means to sense-making is information sharing. This article reports on a quantitative study examining online information sharing behavior regarding the risks of organic

  15. Risk Sharing Partnerships With Suppliers: The Case of EMBRAER

    Directory of Open Access Journals (Sweden)

    Paulo Figueiredo

    2008-04-01

    Full Text Available Since the mid 1990s, the global aircraft industry has been creating new solutions for product development. Risk-sharing partnerships with suppliers began to be established in an attempt to reduce investments and, consequentially, the dependence on loans. The partners began not only to invest in tooling, engineering and infrastructure, but also to participate more directly in the projects, in the investments and design activities, acquiring rights to future sales income of products. This contractual modality, called risk-sharing partnership, is the focus of this study. Specifically, it analyzes the risk-sharing partnerships made by Embraer during the projects of the ERJ-170/190 family of aircrafts. It also aims to justify these partnerships, considering the current global aircraft market conditions, evaluating the critical success factors, requirements and macro-economic conditions which supported the adoption of this new policy.

  16. A Discussion of a Risk-Sharing Pension Plan

    Directory of Open Access Journals (Sweden)

    Catherine Donnelly

    2017-02-01

    Full Text Available I show that risk-sharing pension plans can reduce some of the shortcomings of defined benefit and defined contributions plans. The risk-sharing pension plan presented aims to improve the stability of benefits paid to generations of members, while allowing them to enjoy the expected advantages of a risky investment strategy. The plan does this by adjusting the investment strategy and benefits in response to a changing funding level, motivated by the with-profits contract proposed by Goecke (2013. He suggests a mean-reverting log reserve (or funding ratio, where mean reversion occurs through adjustments to the investment strategy and declared bonuses. To measure the robustness of the plan to human factors, I introduce a measurement of disappointment, where disappointment is high when there are many consecutive years over which benefit payments are declining. Another measure introduced is devastation, where devastation occurs when benefit payments are zero. The motivation is that members of a pension plan who are easily disappointed or likely to get no benefit, are more likely to exit the plan. I find that the risk-sharing plan offers more disappointment than a defined contribution plan, but it eliminates the devastation possible in a plan that tries to accumulate contributions at a steadily increasing rate. The proposed risk-sharing plan can give a narrower range of benefits than in a defined contribution plan. Thus it can offer a stable benefit to members without the risk of running out of money.

  17. Benefits and risks of shared services in healthcare.

    Science.gov (United States)

    Kennewell, Suzanne; Baker, Laura

    2016-05-16

    Purpose - The purpose of this paper is to explore the experiences of staff in a large, public health service involved in transitioning support services to a shared services model. It aims to understand their perceptions of the benefits and risks arising from this change. Design/methodology/approach - Thematic analysis of qualitative data from semi-structured interviews with both service provider and customer agency staff was used to identify, analyze and report patterns of benefits and risks within data. Findings - Staff expressed the need for relevant subject-matter-experts to work within customer agencies to facilitate effective communication between the customer agency and shared services provider, reflecting observations found in out-sourcing literature. Research limitations/implications - Results point to significant challenges continuing to occur for shared services in healthcare. Risks identified suggest a more intimate relationship between clinical and support services than previously discussed. Originality/value - Previous discussion of the shared services model has not considered the skills, knowledge and ability required by staff in the customer agency. This research indicates that in the absence of such consideration, the concepts of the shared services model are weakened.

  18. Optimal Black-Box Secret Sharing over Arbitrary Abelian Groups

    DEFF Research Database (Denmark)

    Cramer, Ronald; Fehr, Serge

    2002-01-01

    A black-box secret sharing scheme for the threshold access structure T t,n is one which works over any finite Abelian group G. Briefly, such a scheme differs from an ordinary linear secret sharing scheme (over, say, a given finite field) in that distribution matrix and reconstruction vectors...... are defined over ℤ and are designed independently of the group G from which the secret and the shares are sampled. This means that perfect completeness and perfect privacy are guaranteed regardless of which group G is chosen. We define the black-box secret sharing problem as the problem of devising......, for an arbitrary given T t,n , a scheme with minimal expansion factor, i.e., where the length of the full vector of shares divided by the number of players n is minimal. Such schemes are relevant for instance in the context of distributed cryptosystems based on groups with secret or hard to compute group order...

  19. Supporting the Maritime Information Dominance: Optimizing Tactical Network for Biometric Data Sharing in Maritime Interdiction Operations

    Science.gov (United States)

    2015-03-01

    biometric data collection. Capture role- player mock biometric data including finger prints, iris scans, and facial recognition photos. (MOC training...MARITIME INFORMATION DOMINANCE: OPTIMIZING TACTICAL NETWORK FOR BIOMETRIC DATA SHARING IN MARITIME INTERDICTION OPERATIONS by Adam R. Sinsel...MARITIME INFORMATION DOMINANCE: OPTIMIZING TACTICAL NETWORK FOR BIOMETRIC DATA SHARING IN MARITIME INTERDICTION OPERATIONS 6. AUTHOR(S) Adam R

  20. Multi-period risk sharing under financial fairness

    NARCIS (Netherlands)

    Bao, Hailong; Ponds, Eduard; Schumacher, Hans

    We work with a multi-period system where a finite number of agents need to share multiple monetary risks. We look for the solutions that are both Pareto efficient utility-wise and financially fair value-wise. A buffer enables the inter-temporal capital transfer. Expected utility is used to evaluate

  1. Shared Genetic Risk Factors of Intracranial, Abdominal, and Thoracic Aneurysms

    NARCIS (Netherlands)

    van 't Hof, Femke N G; Ruigrok, Ynte M; Lee, Cue Hyunkyu; Ripke, Stephan; Anderson, Graig; de Andrade, Mariza; Baas, Annette F; Blankensteijn, Jan D; Böttinger, Erwin P; Bown, Matthew J; Broderick, Joseph; Bijlenga, Philippe; Carrell, David S; Crawford, Dana C; Crosslin, David R; Ebeling, Christian; Eriksson, Johan G; Fornage, Myriam; Foroud, Tatiana; von Und Zu Fraunberg, Mikael; Friedrich, Christoph M; Gaál, Emília I; Gottesman, Omri; Guo, Dong-Chuan; Harrison, Seamus C; Hernesniemi, Juha; Hofman, Albert; Inoue, Ituro; Jääskeläinen, Juha E; Jones, Gregory T; Kiemeney, Lambertus A L M; Kivisaari, Riku; Ko, Nerissa; Koskinen, Seppo; Kubo, Michiaki; Kullo, Iftikhar J; Kuivaniemi, Helena; Kurki, Mitja I; Laakso, Aki; Lai, Dongbing; Leal, Suzanne M; Lehto, Hanna; LeMaire, Scott A; Low, Siew-Kee; Malinowski, Jennifer; McCarty, Catherine A; Milewicz, Dianna M; Mosley, Thomas H; Nakamura, Yusuke; Nakaoka, Hirofumi; Niemelä, Mika; Pacheco, Jennifer; Peissig, Peggy L; Pera, Joanna; Rasmussen-Torvik, Laura; Ritchie, Marylyn D; Rivadeneira, Fernando; van Rij, Andre M; Santos-Cortez, Regie Lyn P; Saratzis, Athanasios; Slowik, Agnieszka; Takahashi, Atsushi; Tromp, Gerard; Uitterlinden, André G; Verma, Shefali S; Vermeulen, Sita H; Wang, Gao T; Han, Buhm; Rinkel, Gabriël J E; de Bakker, Paul I W

    2016-01-01

    BACKGROUND: Intracranial aneurysms (IAs), abdominal aortic aneurysms (AAAs), and thoracic aortic aneurysms (TAAs) all have a familial predisposition. Given that aneurysm types are known to co-occur, we hypothesized that there may be shared genetic risk factors for IAs, AAAs, and TAAs. METHODS AND

  2. Shared genetic risk factors of intracranial, abdominal, and thoracic aneurysms

    NARCIS (Netherlands)

    van 't Hof, Femke N G; Ruigrok, Ynte M; Lee, Cue Hyunkyu; Ripke, Stephan; Anderson, Graig; de Andrade, Mariza; Baas, Annette F; Blankensteijn, Jan D; Böttinger, Erwin P; Bown, Matthew J; Broderick, Joseph; Bijlenga, Philippe; Carrell, David S; Crawford, Dana C; Crosslin, David R; Ebeling, Christian; Eriksson, Johan G; Fornage, Myriam; Foroud, Tatiana; von Und Zu Fraunberg, Mikael; Friedrich, Christoph M; Gaál, Emília I; Gottesman, Omri; Guo, Dong-Chuan; Harrison, Seamus C; Hernesniemi, Juha; Hofman, Albert; Inoue, Ituro; Jääskeläinen, Juha E; Jones, Gregory T; Kiemeney, Lambertus A L M; Kivisaari, Riku; Ko, Nerissa; Koskinen, Seppo; Kubo, Michiaki; Kullo, Iftikhar J; Kuivaniemi, Helena; Kurki, Mitja I; Laakso, Aki; Lai, Dongbing; Leal, Suzanne M; Lehto, Hanna; LeMaire, Scott A; Low, Siew-Kee; Malinowski, Jennifer; McCarty, Catherine A; Milewicz, Dianna M; Mosley, Thomas H; Nakamura, Yusuke; Nakaoka, Hirofumi; Niemelä, Mika; Pacheco, Jennifer; Peissig, Peggy L; Pera, Joanna; Rasmussen-Torvik, Laura; Ritchie, Marylyn D; Rivadeneira, Fernando; van Rij, Andre M; Santos-Cortez, Regie Lyn P; Saratzis, Athanasios; Slowik, Agnieszka; Takahashi, Atsushi; Tromp, Gerard; Uitterlinden, André G; Verma, Shefali S; Vermeulen, Sita H; Wang, Gao T; Han, Buhm; Rinkel, Gabriël J E; de Bakker, Paul I W

    2016-01-01

    Background--Intracranial aneurysms (IAs), abdominal aortic aneurysms (AAAs), and thoracic aortic aneurysms (TAAs) all have a familial predisposition. Given that aneurysm types are known to co-occur, we hypothesized that there may be shared genetic risk factors for IAs, AAAs, and TAAs. Methods and

  3. Multi-Period Risk Sharing under Financial Fairness

    NARCIS (Netherlands)

    Bao, Hailong; Ponds, Eduard; Schumacher, Hans

    2015-01-01

    We work with a multi-period system where a finite number of agents need to share multiple monetary risks. We look for the solutions that are both Pareto efficient utility-wise and financially fair value-wise. A buffer enables the inter-temporal capital transfer. Expected utility is used to evaluate

  4. International Risk-Sharing: Macroeconomic and Financial Aspects

    NARCIS (Netherlands)

    Hadzi-Vaskov, M.

    2008-01-01

    International risk-sharing is one of the most important benefits from the process of international financial integration, which gained in speed, scope, and geographical coverage during the past decades. As long as different national economies are not perfectly correlated, there are possibilities for

  5. Accounting for Households' Perceived Income Uncertainty in Consumption Risk Sharing

    NARCIS (Netherlands)

    Singh, S.; Stoltenberg, C.A.

    2017-01-01

    We develop a consumption risk-sharing model that distinguishes households' perceived income uncertainty from income uncertainty as measured by an econometrician. Households receive signals on their future disposable income that can drive a gap between the two uncertainties. Accounting for the

  6. Sharing as risk pooling in a social dilemma experiment

    Directory of Open Access Journals (Sweden)

    Todd L. Cherry

    2015-03-01

    Full Text Available In rural economies with missing or incomplete markets, idiosyncratic risk is frequently pooled through informal networks. Idiosyncratic shocks, however, are not limited to private goods but can also restrict an individual from partaking in or benefiting from a collective activity. In these situations, a group must decide whether to provide insurance to the affected member. We describe results of a laboratory experiment designed to test whether a simple sharing institution can sustain risk pooling in a social dilemma with idiosyncratic risk. We tested whether risk could be pooled without a commitment device and, separately, whether effective risk pooling induced greater cooperation in the social dilemma. We found that even in the absence of a commitment device or reputational considerations, subjects voluntarily pooled risk, thereby reducing variance in individual earnings. In spite of effective risk pooling, however, cooperation in the social dilemma was unaffected.

  7. Risk Based Optimal Fatigue Testing

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Faber, M.H.; Kroon, I.B.

    1992-01-01

    Optimal fatigue life testing of materials is considered. Based on minimization of the total expected costs of a mechanical component a strategy is suggested to determine the optimal stress range levels for which additional experiments are to be performed together with an optimal value...

  8. Mutuality and solidarity: assessing risks and sharing losses.

    Science.gov (United States)

    Wilkie, D

    1997-01-01

    Mutuality is the principle of private, commercial insurance; individuals enter the pool for sharing losses, and pay according to the best estimate of the risk they bring with them. Solidarity is the sharing of losses with payment according to some other scheme; this is the principle of state social insurance; essential features of solidarity are comprehensiveness and compulsion. Private insurance is subject to the uberrima fides principle, or utmost good faith; each side declares all it knows about the risk. The Disability Discrimination Act requires insurers to justify disability discrimination on the basis of relevant information, acturial, statistical or medical, on which it is reasonable to rely. It could be very damaging to private insurance to abandon uberrima fides. However, although some genetic information is clearly useful to underwriters, other information may be so general as to be of little use. The way in which mortality rates are assessed is also explained. PMID:9304668

  9. 75 FR 16821 - Housing Finance Agency Risk-Sharing Program

    Science.gov (United States)

    2010-04-02

    ...The proposed information collection requirement described below has been submitted to the Office of Management and Budget (OMB) for review, as required by the Paperwork Reduction Act. The Department is soliciting public comments on the subject proposal. Section 542(c) of the Risk Sharing Program authorizes qualified Housing Finance Agencies (HFAs) to underwrite and process loans. HUD provides full mortgage insurance on affordable multifamily housing project processed by HFAs under this program. Qualified HFAs are vested with the maximum amount of processing responsibilities. By entering into Risk-Sharing Agreement with HUD, HFAs contract to reimburse HUD for a portion of the loss from any defaults that occur while HUD insurance is in force.

  10. Optimized load sharing control by means of thermal reliability management

    DEFF Research Database (Denmark)

    Nesgaard, Carsten; Andersen, Michael Andreas E.

    2004-01-01

    time and system cost. However, due to non-ideal parts each converter unit deviates from the ideal case, which makes a power system comprised of parallel-connected converters a rather poor performing system. To account for the non-ideal parts some form of load sharing is needed, whereby it is ensured......With new applications for high-current low-output voltage power systems emerging nearly every day the need for new and cost-efficient power system designs is a matter of course. As output voltage levels continue to decrease an approach that seems more and more attractive is the implementation...... that each converter in the configuration delivers its share of the total output power. In other words parallel-operation of multiple converters is employed when specifications require a highly reliable system, designable within a very short time frame and at low costs. However, to make full use...

  11. Optimal Cross-Layer Design for Energy Efficient D2D Sharing Systems

    KAUST Repository

    Alabbasi, AbdulRahman; Shihada, Basem

    2016-01-01

    modified energy per good bit (MEPG) metric, with respect to the spectrum sharing user’s transmission power and media access frame length. The cellular users, legacy users, are protected by an outage probability constraint. To optimize the non

  12. A Risk-Based Approach for Asset Allocation with A Defaultable Share

    Directory of Open Access Journals (Sweden)

    Yang Shen

    2018-02-01

    Full Text Available This paper presents a novel risk-based approach for an optimal asset allocation problem with default risk, where a money market account, an ordinary share and a defaultable security are investment opportunities in a general non-Markovian economy incorporating random market parameters. The objective of an investor is to select an optimal mix of these securities such that a risk metric of an investment portfolio is minimized. By adopting a sub-additive convex risk measure, which takes into account interest rate risk, as a measure for risk, the investment problem is discussed mathematically in a form of a two-player, zero-sum, stochastic differential game between the investor and the market. A backward stochastic differential equation approach is used to provide a flexible and theoretically sound way to solve the game problem. Closed-form expressions for the optimal strategies of the investor and the market are obtained when the penalty function is a quadratic function and when the risk measure is a sub-additive coherent risk measure. An important case of the general non-Markovian model, namely the self-exciting threshold diffusion model with time delay, is considered. Numerical examples based on simulations for the self-exciting threshold diffusion model with and without time delay are provided to illustrate how the proposed model can be applied in this important case. The proposed model can be implemented using Excel spreadsheets.

  13. Optimization education after project implementation: sharing "lessons learned" with staff.

    Science.gov (United States)

    Vaughn, Susan

    2011-01-01

    Implementations involving healthcare technology solutions focus on providing end-user education prior to the application going "live" in the organization. Benefits to postimplementation education for staff should be included when planning these projects. This author describes the traditional training provided during the implementation of a bar-coding medication project and then the optimization training 8 weeks later.

  14. The Value of Optimization in Dynamic Ride-Sharing: a Simulation Study in Metro Atlanta

    NARCIS (Netherlands)

    N.A.H. Agatz (Niels); A. Erera (Alan); M.W.P. Savelsbergh (Martin); X. Wang (Xing)

    2010-01-01

    textabstractSmartphone technology enables dynamic ride-sharing systems that bring together people with similar itineraries and time schedules to share rides on short-notice. This paper considers the problem of matching drivers and riders in this dynamic setting. We develop optimization-based

  15. Service network design of bike sharing systems analysis and optimization

    CERN Document Server

    Vogel, Patrick

    2016-01-01

    This monograph presents a tactical planning approach for service network design in metropolitan areas. Designing the service network requires the suitable aggregation of demand data as well as the anticipation of operational relocation decisions. To this end, an integrated approach of data analysis and mathematical optimization is introduced. The book also includes a case study based on real-world data to demonstrate the benefit of the proposed service network design approach. The target audience comprises primarily research experts in the field of traffic engineering, but the book may also be beneficial for graduate students.

  16. The Alberta dilemma: optimal sharing of a water resource by an agricultural and an oil sector

    NARCIS (Netherlands)

    Gaudet, G.; Moreaux, M.; Withagen, C.A.A.M.

    2006-01-01

    We fully characterize the optimal time paths of production and water usage by an agricultural and an oil sector that share a limited water resource. We show that for any given water stock, if the oil stock is sufficiently large, it will become optimal to have a phase during which the agricultural

  17. Optimizing Processes to Minimize Risk

    Science.gov (United States)

    Loyd, David

    2017-01-01

    NASA, like the other hazardous industries, has suffered very catastrophic losses. Human error will likely never be completely eliminated as a factor in our failures. When you can't eliminate risk, focus on mitigating the worst consequences and recovering operations. Bolstering processes to emphasize the role of integration and problem solving is key to success. Building an effective Safety Culture bolsters skill-based performance that minimizes risk and encourages successful engagement.

  18. Capital Market Integration and Consumption Risk Sharing over the Long Run

    DEFF Research Database (Denmark)

    Rangvid, Jesper; Santa-Clara, Pedro; Schmeling, Maik

    integration. We also calculate the welfare costs of imperfect capital market integration and risk sharing and find that these costs vary a lot over time. Finally, we show that consumption risk sharing is higher during times of crises, i.e. at times when marginal utility is high and risk sharing is most......We empirically investigate time variation in capital market integration and consumption risk sharing using data for 16 countries from 1875 to 2012. We show that there has been considerable variation over time in the degrees of capital market integration and consumption risk sharing and that higher...... capital market integration forecasts more consumption risk sharing in the future. This finding is robust is to controlling for trade openness and exchange rate volatilities. Hence, financial integration seems to drive consumption risk sharing whereas we find no evidence that risk sharing forecasts market...

  19. RISK OF PROFIT LOSS SHARING FINANCING: THE CASE OF INDONESIA

    Directory of Open Access Journals (Sweden)

    Ernawati Ernawati

    2016-02-01

    Full Text Available This study analyzes the risk of profit-and-loss sharing finance in Indonesian Islamic banking. Data used is secondary data obtained from the Financial Services Authority’s 2009-2014 publication. Financing risk is measured by risk return and opportunity cost. Results of the study show that risk return in mudharaba financing is more volatile than that in musharaka as it is potentially driven by agency problems. In all groups of banks, higher incomes are more promising in mudharaba than musharaka; but individually musharaka is more attractive to Islamic Rural Bank groups, and vice versa for the Sharia Bank groups. The one side it is more secure for Islamic banking to allocate funds in musharaka contract, which is an alternative to murabaha. However, musharaka contract is less attractive due to lower potential returns. Although high returns are more promising in mudaraba, this financing mode has higher risk of returns.DOI: 10.15408/aiq.v8i1.1793

  20. Value at Risk on Composite Price Share Index Stock Data

    Science.gov (United States)

    Oktaviarina, A.

    2018-01-01

    The financial servicest authority was declared Let’s Save Campaign on n commemoration of the World Savings Day that falls on this day, October 31, 2016. The activity was greeted enthusiastically by Indonesia Stock Exchange by taking out the slogan Let’s Save The Stocks. Stock is a form of investment that is expected to benefit in the future despite has risks. Value at Risk (VaR) is a method that can measure how much the risk of a financial investment. Composite Stock Price Indeks is the stock price index used by Indonesia Stock Exchange as stock volatility benchmarks in Indonesia. This study aimed to estimate Value at Risk (VaR) on closing price Composite Price Share Index Stock data on the period 20 September 2016 until 20 September 2017. Box-Pierce test results p value=0.9528 which is greater than a, that shows homoskedasticity. Value at Risk (VaR) with Variance Covariance Method is Rp.3.054.916,07 which means with 99% confindence interval someone who invests Rp.100.000.000,00 will get Rp.3.054.916,07 as a maximum loss.

  1. Human and animal sentinels for shared health risks

    Directory of Open Access Journals (Sweden)

    Peter Rabinowitz, MD, MPH

    2009-03-01

    Full Text Available The tracking of sentinel health events in humans in order to detect and manage disease risks facing a larger population is a well accepted technique applied to influenza, occupational conditions and emerging infectious diseases. Similarly, animal health professionals routinely track disease events in sentinel animal colonies and sentinel herds. The use of animals as sentinels for human health threats, or of humans as sentinels for animal disease risk, dates back at least to the era when coal miners brought caged canaries into mines to provide early warning of toxic gases. Yet the full potential of linking animal and human health information to provide warning of such ‘shared risks’ from environmental hazards has not been realised. Reasons appear to include the professional segregation of human and animal health communities, the separation of human and animal surveillance data and evidence gaps in the linkages between human and animal responses to environmental health hazards. The ‘One Health initiative’ and growing international collaboration in response to pandemic threats, coupled with development in the fields of informatics and genomics, hold promise for improved sentinel event coordination in order to detect and reduce environmental health threats shared between species.

  2. Design of shared unit-dose drug distribution network using multi-level particle swarm optimization.

    Science.gov (United States)

    Chen, Linjie; Monteiro, Thibaud; Wang, Tao; Marcon, Eric

    2018-03-01

    Unit-dose drug distribution systems provide optimal choices in terms of medication security and efficiency for organizing the drug-use process in large hospitals. As small hospitals have to share such automatic systems for economic reasons, the structure of their logistic organization becomes a very sensitive issue. In the research reported here, we develop a generalized multi-level optimization method - multi-level particle swarm optimization (MLPSO) - to design a shared unit-dose drug distribution network. Structurally, the problem studied can be considered as a type of capacitated location-routing problem (CLRP) with new constraints related to specific production planning. This kind of problem implies that a multi-level optimization should be performed in order to minimize logistic operating costs. Our results show that with the proposed algorithm, a more suitable modeling framework, as well as computational time savings and better optimization performance are obtained than that reported in the literature on this subject.

  3. Capital Market Integration and Consumption Risk Sharing over the Long Run

    DEFF Research Database (Denmark)

    Rangvid, Jesper; Santa-Clara, Pedro; Schmeling, Maik

    2016-01-01

    capital market integration forecasts more consumption risk sharing in the future. This finding is robust to controlling for trade openness and exchange rate volatility as alternative drivers of risk sharing. Finally, we calculate the welfare costs of imperfect consumption risk sharing and find......We empirically investigate time variation in capital market integration and consumption risk sharing using data for 16 countries from 1875 to 2012. We show that there has been considerable variation over time in the degrees of capital market integration and consumption risk sharing and that higher...

  4. Financial risk sharing with providers in health maintenance organizations, 1999.

    Science.gov (United States)

    Gold, Marsha R; Lake, Timothy; Hurley, Robert; Sinclair, Michael

    2002-01-01

    The transfer of financial risk from health maintenance organizations (HMOs) to providers is controversial. To provide timely national data on these practices, we conducted a telephone survey in 1999 of a multi-staged probability sample of HMOs in 20 of the nation's 60 largest markets, accounting for 86% of all HMO enrollees nationally. Among those sampled, 82% responded. We found that HMOs' provider networks with physicians, hospitals, skilled nursing homes, and home health agencies are complex and multi-tiered Seventy-six percent of HMOs in our study use contracts for their HMO products that involve global, professional services, or hospital risk capitation to intermediate entities. These arrangements account for between 24.5 million and 27.4 million of the 55.9 million commercial and Medicare HMO enrollees in the 60 largest markets. While capitation arrangements are particularly common in California, they are more common elsewhere than many assume. The complex layering of risk sharing and delegation of care management responsibility raise questions about accountability and administrative costs in managed care. Do complex structures provide a way to involve providers more directly in managed care, or do they diffuse authority and add to administrative costs?

  5. Optimal Cross-Layer Design for Energy Efficient D2D Sharing Systems

    KAUST Repository

    Alabbasi, Abdulrahman

    2016-11-23

    In this paper, we propose a cross-layer design, which optimizes the energy efficiency of a potential future 5G spectrum-sharing environment, in two sharing scenarios. In the first scenario, underlying sharing is considered. We propose and minimize a modified energy per good bit (MEPG) metric, with respect to the spectrum sharing user’s transmission power and media access frame length. The cellular users, legacy users, are protected by an outage probability constraint. To optimize the non-convex targeted problem, we utilize the generalized convexity theory and verify the problem’s strictly pseudoconvex structure. We also derive analytical expressions of the optimal resources. In the second scenario, we minimize a generalized MEPG function while considering a probabilistic activity of cellular users and its impact on the MEPG performance of the spectrum sharing users. Finally, we derive the associated optimal resource allocation of this problem. Selected numerical results show the improvement of the proposed system compared with other systems.

  6. Optimal task partition and state-dependent loading in heterogeneous two-element work sharing system

    International Nuclear Information System (INIS)

    Levitin, Gregory; Xing, Liudong; Ben-Haim, Hanoch; Dai, Yuanshun

    2016-01-01

    Many real-world systems such as multi-channel data communication, multi-path flow transmission and multi-processor computing systems have work sharing attributes where system elements perform different portions of the same task simultaneously. Motivated by these applications, this paper models a heterogeneous work-sharing system with two non-repairable elements. When one element fails, the other element takes over the uncompleted task of the failed element upon finishing its own part; the load level of the remaining operating element can change at the time of the failure, which further affects its performance, failure behavior and operation cost. Considering these dynamics, mission success probability (MSP), expected mission completion time (EMCT) and expected cost of successful mission (ECSM) are first derived. Further, optimization problems are formulated and solved, which find optimal task partition and element load levels maximizing MSP, minimizing EMCT or minimizing ECSM. Effects of element reliability, performance, operation cost on the optimal solutions are also investigated through examples. Results of this work can facilitate a tradeoff analysis of different mission performance indices for heterogeneous work-sharing systems. - Highlights: • A heterogeneous work-sharing system with two non-repairable elements is considered. • The optimal work distribution and element loading problem is formulated and solved. • Effects of element reliability, performance, operation cost on the optimal solutions are investigated.

  7. Correlation risk and optimal portfolio choice

    OpenAIRE

    Buraschi, Andrea; Porchia, Paolo; Trojani, Fabio

    2010-01-01

    We develop a new framework for multivariate intertemporal portfolio choice that allows us to derive optimal portfolio implications for economies in which the degree of correlation across industries, countries, or asset classes is stochastic. Optimal portfolios include distinct hedging components against both stochastic volatility and correlation risk. We find that the hedging demand is typically larger than in univariate models, and it includes an economically significant covariance hedging...

  8. Modifiable risk factors for schizophrenia and autism--shared risk factors impacting on brain development.

    Science.gov (United States)

    Hamlyn, Jess; Duhig, Michael; McGrath, John; Scott, James

    2013-05-01

    Schizophrenia and autism are two poorly understood clinical syndromes that differ in age of onset and clinical profile. However, recent genetic and epidemiological research suggests that these two neurodevelopmental disorders share certain risk factors. The aims of this review are to describe modifiable risk factors that have been identified in both disorders, and, where available, collate salient systematic reviews and meta-analyses that have examined shared risk factors. Based on searches of Medline, Embase and PsycINFO, inspection of review articles and expert opinion, we first compiled a set of candidate modifiable risk factors associated with autism. Where available, we next collated systematic-reviews (with or without meta-analyses) related to modifiable risk factors associated with both autism and schizophrenia. We identified three modifiable risk factors that have been examined in systematic reviews for both autism and schizophrenia. Advanced paternal age was reported as a risk factor for schizophrenia in a single meta-analysis and as a risk factor in two meta-analyses for autism. With respect to pregnancy and birth complications, for autism one meta-analysis identified maternal diabetes and bleeding during pregnancy as risks factors for autism whilst a meta-analysis of eight studies identified obstetric complications as a risk factor for schizophrenia. Migrant status was identified as a risk factor for both autism and schizophrenia. Two separate meta-analyses were identified for each disorder. Despite distinct clinical phenotypes, the evidence suggests that at least some non-genetic risk factors are shared between these two syndromes. In particular, exposure to drugs, nutritional excesses or deficiencies and infectious agents lend themselves to public health interventions. Studies are now needed to quantify any increase in risk of either autism or schizophrenia that is associated with these modifiable environmental factors. Copyright © 2012 Elsevier Inc

  9. Risk and utility in portfolio optimization

    Science.gov (United States)

    Cohen, Morrel H.; Natoli, Vincent D.

    2003-06-01

    Modern portfolio theory (MPT) addresses the problem of determining the optimum allocation of investment resources among a set of candidate assets. In the original mean-variance approach of Markowitz, volatility is taken as a proxy for risk, conflating uncertainty with risk. There have been many subsequent attempts to alleviate that weakness which, typically, combine utility and risk. We present here a modification of MPT based on the inclusion of separate risk and utility criteria. We define risk as the probability of failure to meet a pre-established investment goal. We define utility as the expectation of a utility function with positive and decreasing marginal value as a function of yield. The emphasis throughout is on long investment horizons for which risk-free assets do not exist. Analytic results are presented for a Gaussian probability distribution. Risk-utility relations are explored via empirical stock-price data, and an illustrative portfolio is optimized using the empirical data.

  10. RISK LOAN PORTFOLIO OPTIMIZATION MODEL BASED ON CVAR RISK MEASURE

    Directory of Open Access Journals (Sweden)

    Ming-Chang LEE

    2015-07-01

    Full Text Available In order to achieve commercial banks liquidity, safety and profitability objective requirements, loan portfolio risk analysis based optimization decisions are rational allocation of assets.  The risk analysis and asset allocation are the key technology of banking and risk management.  The aim of this paper, build a loan portfolio optimization model based on risk analysis.  Loan portfolio rate of return by using Value-at-Risk (VaR and Conditional Value-at-Risk (CVaR constraint optimization decision model reflects the bank's risk tolerance, and the potential loss of direct control of the bank.  In this paper, it analyze a general risk management model applied to portfolio problems with VaR and CVaR risk measures by using Using the Lagrangian Algorithm.  This paper solves the highly difficult problem by matrix operation method.  Therefore, the combination of this paper is easy understanding the portfolio problems with VaR and CVaR risk model is a hyperbola in mean-standard deviation space.  It is easy calculation in proposed method.

  11. The Application of Fitness Sharing Method in Evolutionary Algorithm to Optimizing the Travelling Salesman Problem (TSP

    Directory of Open Access Journals (Sweden)

    Nurmaulidar Nurmaulidar

    2015-04-01

    Full Text Available Travelling Salesman Problem (TSP is one of complex optimization problem that is difficult to be solved, and require quite a long time for a large number of cities. Evolutionary algorithm is a precise algorithm used in solving complex optimization problem as it is part of heuristic method. Evolutionary algorithm, like many other algorithms, also experiences a premature convergence phenomenon, whereby variation is eliminated from a population of fairly fit individuals before a complete solution is achieved. Therefore it requires a method to delay the convergence. A specific method of fitness sharing called phenotype fitness sharing has been used in this research. The aim of this research is to find out whether fitness sharing in evolutionary algorithm is able to optimize TSP. There are two concepts of evolutionary algorithm being used in this research. the first one used single elitism and the other one used federated solution. The two concepts had been tested to the method of fitness sharing by using the threshold of 0.25, 0.50 and 0.75. The result was then compared to a non fitness sharing method. The result in this study indicated that by using single elitism concept, fitness sharing was able to give a more optimum result for the data of 100-1000 cities. On the other hand, by using federation solution concept, fitness sharing can yield a more optimum result for the data above 1000 cities, as well as a better solution of data-spreading compared to the method without fitness sharing.

  12. Optimal Sequential Resource Sharing and Exchange in Multi-Agent Systems

    OpenAIRE

    Xiao, Yuanzhang

    2014-01-01

    Central to the design of many engineering systems and social networks is to solve the underlying resource sharing and exchange problems, in which multiple decentralized agents make sequential decisions over time to optimize some long-term performance metrics. It is challenging for the decentralized agents to make optimal sequential decisions because of the complicated coupling among the agents and across time. In this dissertation, we mainly focus on three important classes of multi-agent seq...

  13. Event classification and optimization methods using artificial intelligence and other relevant techniques: Sharing the experiences

    Science.gov (United States)

    Mohamed, Abdul Aziz; Hasan, Abu Bakar; Ghazali, Abu Bakar Mhd.

    2017-01-01

    Classification of large data into respected classes or groups could be carried out with the help of artificial intelligence (AI) tools readily available in the market. To get the optimum or best results, optimization tool could be applied on those data. Classification and optimization have been used by researchers throughout their works, and the outcomes were very encouraging indeed. Here, the authors are trying to share what they have experienced in three different areas of applied research.

  14. Spare parts sharing with joint optimization of maintenance and inventory policies

    DEFF Research Database (Denmark)

    Larsen, Christian; Wong, Hartanto Wijaya; Nielsen, Lars Relund

    We consider a collaborative arrangement where a number of companies are willing to share expensive spare parts, required for both failure replacement and preventive maintenance purposes. We develop a discrete-time Markov decision model for the joint optimization of maintenance and spare parts...

  15. Optimal security investments and extreme risk.

    Science.gov (United States)

    Mohtadi, Hamid; Agiwal, Swati

    2012-08-01

    In the aftermath of 9/11, concern over security increased dramatically in both the public and the private sector. Yet, no clear algorithm exists to inform firms on the amount and the timing of security investments to mitigate the impact of catastrophic risks. The goal of this article is to devise an optimum investment strategy for firms to mitigate exposure to catastrophic risks, focusing on how much to invest and when to invest. The latter question addresses the issue of whether postponing a risk mitigating decision is an optimal strategy or not. Accordingly, we develop and estimate both a one-period model and a multiperiod model within the framework of extreme value theory (EVT). We calibrate these models using probability measures for catastrophic terrorism risks associated with attacks on the food sector. We then compare our findings with the purchase of catastrophic risk insurance. © 2012 Society for Risk Analysis.

  16. Optimal dividends and ALM under unhedgeable risk

    NARCIS (Netherlands)

    Pelsser, A.A.J.; Laeven, R.J.A.

    2013-01-01

    In this paper we develop a framework for optimal investment decisions for insurance companies in the presence of (partially) unhedgeable risk. The perspective that we choose is from an insurance company that maximises the stream of dividends paid to its shareholders. The policy instruments that the

  17. Shared risk aversion in spontaneous and induced abortion.

    Science.gov (United States)

    Catalano, Ralph; Bruckner, Tim A; Karasek, Deborah; Adler, Nancy E; Mortensen, Laust H

    2016-05-01

    Does the incidence of spontaneous abortion correlate positively over conception cohorts with the incidence of non-clinically indicated induced abortion as predicted by shared risk aversion? We find that the number of spontaneous and non-clinically indicated induced abortions correlates in conception cohorts, suggesting that risk aversion affects both the conscious and non-conscious mechanisms that control parturition. Much literature speculates that natural selection conserved risk aversion because the trait enhanced Darwinian fitness. Risk aversion, moreover, supposedly influences all decisions including those that individuals can and cannot report making. We argue that these circumstances, if real, would manifest in conscious and non-conscious decisions to invest in prospective offspring, and therefore affect incidence of induced and spontaneous abortion over time. Using data from Denmark, we test the hypothesis that monthly conception cohorts yielding unexpectedly many non-clinically indicated induced abortions also yield unexpectedly many spontaneous abortions. The 180 month test period (January 1995 through December 2009), yielded 1 351 800 gestations including 156 780 spontaneous as well as 233 280 induced abortions 9100 of which were clinically indicated. We use Box-Jenkins transfer functions to adjust the incidence of spontaneous and non-clinically indicated induced abortions for autocorrelation (including seasonality), cohort size, and fetal as well as gestational anomalies over the 180-month test period. We use cross-correlation to test our hypothesized association. We find a positive association between spontaneous and non-clinically indicated induced abortions. This suggests, consistent with our theory, that mothers of conception cohorts that yielded more spontaneous abortions than expected opted more frequently than expected for non-clinically indicated induced abortion. Limitations of our work include that even the world's best registration system

  18. Optimal diving under the risk of predation.

    Science.gov (United States)

    Heithaus, Michael R; Frid, Alejandro

    2003-07-07

    Many air-breathing aquatic foragers may be killed by aerial or subsurface predators while recovering oxygen at the surface; yet the influence of predation risk on time allocation during dive cycles is little known in spite of numerous studies on optimal diving. We modeled diving behavior under the risk of predation at the surface. The relationship between time spent at the surface and the risk of death is predicted to influence the optimal surface interval, regardless of whether foragers accumulate energy at a constant rate while at the food patch, deplete food resources over the course of the dive, or must search for food during the dive. When instantaneous predation risk during a single surface interval decreases with time spent at the surface, a diver should increase its surface interval relative to that which maximizes energy intake, thereby increasing dive durations and reducing the number of surfacings per foraging bout. When instantaneous risk over a single surface interval does not change or increases with increasing time at the surface, divers should decrease their surface interval (and consequently their dive duration) relative to that which maximizes energy intake resulting in more dives per foraging bout. The fitness consequences of selecting a suboptimal surface interval vary with the risk function and the way divers harvest energy when at depth. Finally, predation risk during surface intervals should have important consequences for habitat selection and other aspects of the behavioral ecology of air-breathing aquatic organisms.

  19. Risk-based optimization of land reclamation

    International Nuclear Information System (INIS)

    Lendering, K.T.; Jonkman, S.N.; Gelder, P.H.A.J.M. van; Peters, D.J.

    2015-01-01

    Large-scale land reclamations are generally constructed by means of a landfill well above mean sea level. This can be costly in areas where good quality fill material is scarce. An alternative to save materials and costs is a ‘polder terminal’. The quay wall acts as a flood defense and the terminal level is well below the level of the quay wall. Compared with a conventional terminal, the costs are lower, but an additional flood risk is introduced. In this paper, a risk-based optimization is developed for a conventional and a polder terminal. It considers the investment and residual flood risk. The method takes into account both the quay wall and terminal level, which determine the probability and damage of flooding. The optimal quay wall level is found by solving a Lambert function numerically. The terminal level is bounded by engineering boundary conditions, i.e. piping and uplift of the cover layer of the terminal yard. It is found that, for a representative case study, the saving of reclamation costs for a polder terminal is larger than the increase of flood risk. The model is applicable to other cases of land reclamation and to similar optimization problems in flood risk management. - Highlights: • A polder terminal can be an attractive alternative for a conventional terminal. • A polder terminal is feasible at locations with high reclamation cost. • A risk-based approach is required to determine the optimal protection levels. • The depth of the polder terminal yard is bounded by uplifting of the cover layer. • This paper can support decisions regarding alternatives for port expansions.

  20. 12 CFR 955.3 - Required credit risk-sharing structure.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 7 2010-01-01 2010-01-01 false Required credit risk-sharing structure. 955.3...-BALANCE SHEET ITEMS ACQUIRED MEMBER ASSETS § 955.3 Required credit risk-sharing structure. (a... conducting a rating review of the asset or pool of assets in a securitization transaction. (b) Credit risk...

  1. Optimal Adaptive Droop Control for Effective Load Sharing in AC Microgrids

    DEFF Research Database (Denmark)

    Anvari-Moghaddam, Amjad; Shafiee, Qobad; Quintero, Juan Carlos Vasquez

    2016-01-01

    During the past few years, microgrids (MGs) have been becoming more attractive as effective means to integrate different distributed energy resources (DERs). To coordinate active and reactive power sharing among DERs, conventional droop control method is widely used as a decentralized control...... control strategy is developed in two levels. The upper control level is a mixed-objective optimization algorithm that provides optimal set-points for power generations considering system’s constraints and goals, while the lower control level is responsible for tracking the reference signals coming from...

  2. The simple economics of risk-sharing agreements between the NHS and the pharmaceutical industry.

    Science.gov (United States)

    Barros, Pedro Pita

    2011-04-01

    The introduction of new (and expensive) pharmaceutical products is one of the major challenges for health systems. The search for new institutional arrangements is natural. The use of the so-called risk-sharing agreements is one example. Recent discussions have somewhat neglected the economic fundamentals underlying risk-sharing agreements. We argue here that risk-sharing agreements, although attractive due to the principle of paying by results, also entail risks. Too many patients may be put under treatment. Prices are likely to be adjusted upward, in anticipation of future risk-sharing agreements between the pharmaceutical company and the third-party payer. An available instrument is a verification cost per patient treated, which allows obtaining the first-best allocation of patients to the new treatment, under the agreement. Overall, the welfare effects of risk-sharing agreements are ambiguous, and caution is urged regarding their use. Copyright © 2010 John Wiley & Sons, Ltd.

  3. Who Should I Share Risk with? Gifts can tell : Theory and Evidence from Rural China

    NARCIS (Netherlands)

    Wang, Ruixin

    2016-01-01

    This paper studies how gift exchange may help to overcome limited commitment problem in risk sharing. When efficient contract enforcement is lacking, people rely on friends (or relatives) to share risk since emotional or moral cost of defaulting between friends can help to prevent moral hazard. The

  4. Perception and Management of Risk in Internet-Based Peer-to-Peer Milk-Sharing

    Science.gov (United States)

    Gribble, Karleen D.

    2014-01-01

    The perception and management of the risks of peer-to-peer milk sharing was explored via a written questionnaire administered to 97 peer milk donors and 41 peer milk recipients who were recruited via Facebook. All recipients' respondents were aware that there were risks associated with using peer-shared milk and took action to mitigate these…

  5. Stochastic Discount Factor Approach to International Risk-Sharing: Evidence from Fixed Exchange Rate Episodes

    NARCIS (Netherlands)

    Hadzi-Vaskov, M.; Kool, C.J.M.

    2007-01-01

    This paper presents evidence of the stochastic discount factor approach to international risk-sharing applied to fixed exchange rate regimes. We calculate risk-sharing indices for two episodes of fixed or very rigid exchange rates: the Eurozone before and after the introduction of the Euro, and

  6. Stochastic Discount Factor Approach to International Risk-Sharing:A Robustness Check of the Bilateral Setting

    NARCIS (Netherlands)

    Hadzi-Vaskov, M.; Kool, C.J.M.

    2007-01-01

    This paper presents a robustness check of the stochastic discount factor approach to international (bilateral) risk-sharing given in Brandt, Cochrane, and Santa-Clara (2006). We demonstrate two main inherent limitations of the bilateral SDF approach to international risk-sharing. First, the discount

  7. Applications of polynomial optimization in financial risk investment

    Science.gov (United States)

    Zeng, Meilan; Fu, Hongwei

    2017-09-01

    Recently, polynomial optimization has many important applications in optimization, financial economics and eigenvalues of tensor, etc. This paper studies the applications of polynomial optimization in financial risk investment. We consider the standard mean-variance risk measurement model and the mean-variance risk measurement model with transaction costs. We use Lasserre's hierarchy of semidefinite programming (SDP) relaxations to solve the specific cases. The results show that polynomial optimization is effective for some financial optimization problems.

  8. Impact of a financial risk-sharing scheme on budget-impact estimations: a game-theoretic approach.

    Science.gov (United States)

    Gavious, Arieh; Greenberg, Dan; Hammerman, Ariel; Segev, Ella

    2014-06-01

    As part of the process of updating the National List of Health Services in Israel, health plans (the 'payers') and manufacturers each provide estimates on the expected number of patients that will utilize a new drug. Currently, payers face major financial consequences when actual utilization is higher than the allocated budget. We suggest a risk-sharing model between the two stakeholders; if the actual number of patients exceeds the manufacturer's prediction, the manufacturer will reimburse the payers by a rebate rate of α from the deficit. In case of under-utilization, payers will refund the government at a rate of γ from the surplus budget. Our study objective was to identify the optimal early estimations of both 'players' prior to and after implementation of the risk-sharing scheme. Using a game-theoretic approach, in which both players' statements are considered simultaneously, we examined the impact of risk-sharing within a given range of rebate proportions, on players' early budget estimations. When increasing manufacturer's rebate α to be over 50 %, then manufacturers will announce a larger number, and health plans will announce a lower number of patients than they would without risk sharing, thus substantially decreasing the gap between their estimates. Increasing γ changes players' estimates only slightly. In reaction to applying a substantial risk-sharing rebate α on the manufacturer, both players are expected to adjust their budget estimates toward an optimal equilibrium. Increasing α is a better vehicle for reaching the desired equilibrium rather than increasing γ, as the manufacturer's rebate α substantially influences both players, whereas γ has little effect on the players behavior.

  9. Active load sharing technique for on-line efficiency optimization in DC microgrids

    DEFF Research Database (Denmark)

    Sanseverino, E. Riva; Zizzo, G.; Boscaino, V.

    2017-01-01

    Recently, DC power distribution is gaining more and more importance over its AC counterpart achieving increased efficiency, greater flexibility, reduced volumes and capital cost. In this paper, a 24-120-325V two-level DC distribution system for home appliances, each including three parallel DC......-DC converters, is modeled. An active load sharing technique is proposed for the on-line optimization of the global efficiency of the DC distribution network. The algorithm aims at the instantaneous efficiency optimization of the whole DC network, based on the on-line load current sampling. A Look Up Table......, is created to store the real efficiencies of the converters taking into account components tolerances. A MATLAB/Simulink model of the DC distribution network has been set up and a Genetic Algorithm has been employed for the global efficiency optimization. Simulation results are shown to validate the proposed...

  10. Optimal loading and protection of multi-state systems considering performance sharing mechanism

    International Nuclear Information System (INIS)

    Xiao, Hui; Shi, Daimin; Ding, Yi; Peng, Rui

    2016-01-01

    Engineering systems are designed to carry the load. The performance of the system largely depends on how much load it carries. On the other hand, the failure rate of the system is strongly affected by its load. Besides internal failures, such as fatigue and aging process, systems may also fail due to external impacts such as nature disasters and terrorism. In this paper, we integrate the effect of loading and protection of external impacts on multi-state systems with performance sharing mechanism. The objective of this research is to determine how to balance the load and protection on system elements. An availability evaluation algorithm of the proposed system is suggested and the corresponding optimization problem is solved utilizing genetic algorithms. - Highlights: • Performance sharing of multi-state systems is considered. • The effect of load on system elements is analyzed. • Joint optimization model of element loading and protection is formulated. • Genetic Algorithms are adapted to solve the reliability optimization problem.

  11. Optimized design and performance of a shared pump single clad 2 μm TDFA

    Science.gov (United States)

    Tench, Robert E.; Romano, Clément; Delavaux, Jean-Marc

    2018-05-01

    We report the design, experimental performance, and simulation of a single stage, co- and counter-pumped Tm-doped fiber amplifier (TDFA) in the 2 μm signal wavelength band with an optimized 1567 nm shared pump source. We investigate the dependence of output power, gain, and efficiency on pump coupling ratio and signal wavelength. Small signal gains of >50 dB, an output power of 2 W, and small signal noise figures of performance agree well with the experimental data. We also discuss performance tradeoffs with respect to amplifier topology for this simple and efficient TDFA.

  12. Tacit Knowledge Sharing Modes of University Teachers from the Perspectives of Psychological Risk and Value

    Science.gov (United States)

    Yu, Dengke; Zhou, Rong

    2015-01-01

    Tacit knowledge sharing (TKS) is important to improve the teaching skill and researching knowledge of university teachers. In this paper, the tacit knowledge sharing of university teachers is catalogued as four modes from perspectives of the psychological risk and psychological value which are measured by two grades--high and low. The four modes…

  13. Optimization of communication network topology for navigation sharing among distributed satellites

    Science.gov (United States)

    Dang, Zhaohui; Zhang, Yulin

    2013-01-01

    Navigation sharing among distributed satellites is quite important for coordinated motion and collision avoidance. This paper proposes optimization methods of the communication network topology to achieve navigation sharing. The whole communication network constructing by inter-satellite links are considered as a topology graph. The aim of this paper is to find the communication network topology with minimum communication connections' number (MCCN) in different conditions. It has found that the communication capacity and the number of channels are two key parameters affecting the results. The model of MCCN topology for navigation sharing is established and corresponding method is designed. Two main scenarios, viz., homogeneous case and heterogeneous case, are considered. For the homogeneous case where each member has the same communication capacity, it designs a construction method (Algorithm 1) to find the MCCN topology. For the heterogeneous case, it introduces a modified genetic algorithm (Algorithm 2) to find the MCCN topology. When considering the fact that the number of channels is limited, the Algorithm 2 is further modified by adding a penalized term in the fitness function. The effectiveness of these algorithms is all proved in theoretical. Three examples are further tested to illustrate the methods developed in this paper.

  14. A Comprehensive Optimization Strategy for Real-time Spatial Feature Sharing and Visual Analytics in Cyberinfrastructure

    Science.gov (United States)

    Li, W.; Shao, H.

    2017-12-01

    For geospatial cyberinfrastructure enabled web services, the ability of rapidly transmitting and sharing spatial data over the Internet plays a critical role to meet the demands of real-time change detection, response and decision-making. Especially for the vector datasets which serve as irreplaceable and concrete material in data-driven geospatial applications, their rich geometry and property information facilitates the development of interactive, efficient and intelligent data analysis and visualization applications. However, the big-data issues of vector datasets have hindered their wide adoption in web services. In this research, we propose a comprehensive optimization strategy to enhance the performance of vector data transmitting and processing. This strategy combines: 1) pre- and on-the-fly generalization, which automatically determines proper simplification level through the introduction of appropriate distance tolerance (ADT) to meet various visualization requirements, and at the same time speed up simplification efficiency; 2) a progressive attribute transmission method to reduce data size and therefore the service response time; 3) compressed data transmission and dynamic adoption of a compression method to maximize the service efficiency under different computing and network environments. A cyberinfrastructure web portal was developed for implementing the proposed technologies. After applying our optimization strategies, substantial performance enhancement is achieved. We expect this work to widen the use of web service providing vector data to support real-time spatial feature sharing, visual analytics and decision-making.

  15. Optimization and Control for Sharing of the ITER Vacuum Vessel Support Force

    International Nuclear Information System (INIS)

    Rozov, V.

    2006-01-01

    The ITER Vacuum Vessel (VV) is a complex body supported in 9 points below lower ports by restraints in the radial, toroidal and vertical directions. The applied load produces a combination of reaction forces, which must be consistent with the design of the supported object. A reasonable sharing of the load among the supports is important for overall performance of the structure and helps to avoid excessive stress at the joints between the VV and lower ports. Optimization has been performed of the sharing of the total horizontal load applied to the ITER VV between radial and toroidal restraints. An effective method of finding simple parametric relationships between the design parameters of supports and the balance of the reaction forces has been developed. This allows purely analytical prediction of the sharing of the reaction forces for any desired stiffness of the applied restraints with no need for finite element structural analysis, and also allows control of the sharing by a proper selection of parameters of the supports. The method is based on the use of elementary mono-directional schemes - equivalent oscillators built for the main global modes, in static problems. The types of schemes and parameters of their members, related to the a-priori unknown stiffness of the VV structure under the supports, are found from consideration of the free vibration problem for the object using a 3D model of the VV with mass simulators - a series of simple eigenvalue analyses with variation of stiffness of the external restraints, that demands quite moderate computational resources. The equivalent schemes for the main modes not only enable simple one-line analytical calculation of the natural frequencies at any desired stiffness of the supports, but also indicate the contributions and balance of stiffness, to be considered in the static problem. The results of assessments of the reaction forces by direct static structural analyses for several cases are in agreement with values

  16. Risk sharing between competing health plans and sponsors

    NARCIS (Netherlands)

    E.M. van Barneveld (Erik); W.P.M.M. van de Ven (Wynand); R.C.J.A. van Vliet (René)

    2001-01-01

    textabstractIn many countries, competing health plans receive capitation payments from a sponsor, whether government or a private employer. All capitation payment methods are far from perfect and have raised concerns about risk selection. Paying health plans partly on the basis

  17. 78 FR 52962 - 60-Day Notice of Proposed Information Collection: Housing Finance Agency Risk-Sharing Program

    Science.gov (United States)

    2013-08-27

    ... Information Collection: Housing Finance Agency Risk-Sharing Program AGENCY: Office of the Assistant Secretary... Finance Agency Risk- Sharing Program. OMB Approval Number: 2502-0500. Type of Request (i.e. new, revision... Secretary to implement risk sharing with State and local housing finance agencies (HFAs). Under this program...

  18. Radical uncertainty, non-predictability, antifragility and risk-sharing Islamic finance

    Directory of Open Access Journals (Sweden)

    Umar Rafi

    2016-12-01

    Full Text Available Under conditions of radical uncertainty, risk sharing renders financial systems anti-fragile. Our goal in this paper is to show that risk-sharing Islamic finance (RSIF shares the characteristics defined by Taleb for an anti-fragile system, by mapping some characteristics of anti-fragility onto those of risk-sharing Islamic finance. A key insight around which such a connection can be established is by relating the principle of “no risk-no gain”from Islamic finance to the concept of skin-in-the-game from anti-fragility theory. The relationship is then extended to other characteristics of the two frameworks, to show that RSIF overlaps with anti-fragility over many dimensions. The broader case for an antifragile system includes another important characteristic, namely “soul in the game” and concern for social justice. It is the authors’ hope that emerging research on anti-fragility, combined with the emerging research on RSIF, can have a lasting impact on the field of finance by laying the foundations for a compelling case that it is time for humanity to replace the dominant debt-based risk transfer/risk shifting financial system with a system in which everyone shares the risks faced by society. JEL: D81, D89, E44, F34, G32

  19. Balancing the risks and benefits of genomic data sharing: genome research participants' perspectives.

    Science.gov (United States)

    Oliver, J M; Slashinski, M J; Wang, T; Kelly, P A; Hilsenbeck, S G; McGuire, A L

    2012-01-01

    Technological advancements are rapidly propelling the field of genome research forward, while lawmakers attempt to keep apace with the risks these advances bear. Balancing normative concerns of maximizing data utility and protecting human subjects, whose privacy is at risk due to the identifiability of DNA data, are central to policy decisions. Research on genome research participants making real-time data sharing decisions is limited; yet, these perspectives could provide critical information to ongoing deliberations. We conducted a randomized trial of 3 consent types affording varying levels of control over data release decisions. After debriefing participants about the randomization process, we invited them to a follow-up interview to assess their attitudes toward genetic research, privacy and data sharing. Participants were more restrictive in their reported data sharing preferences than in their actual data sharing decisions. They saw both benefits and risks associated with sharing their genomic data, but risks were seen as less concrete or happening in the future, and were largely outweighed by purported benefits. Policymakers must respect that participants' assessment of the risks and benefits of data sharing and their privacy-utility determinations, which are associated with their final data release decisions, vary. In order to advance the ethical conduct of genome research, proposed policy changes should carefully consider these stakeholder perspectives. Copyright © 2011 S. Karger AG, Basel.

  20. Research on Liquidity Risk Evaluation of Chinese A-Shares Market Based on Extension Theory

    Science.gov (United States)

    Bai-Qing, Sun; Peng-Xiang, Liu; Lin, Zhang; Yan-Ge, Li

    This research defines the liquidity risk of stock market in matter-element theory and affair-element theory, establishes the indicator system of the forewarning for liquidity risks,designs the model and the process of early warning using the extension set method, extension dependent function and the comprehensive evaluation model. And the paper studies empirically A-shares market through the data of 1A0001, which prove that the model can better describe liquidity risk of China’s A-share market. At last, it gives the corresponding policy recommendations.

  1. Exploring Shared-Memory Optimizations for an Unstructured Mesh CFD Application on Modern Parallel Systems

    KAUST Repository

    Mudigere, Dheevatsa

    2015-05-01

    In this work, we revisit the 1999 Gordon Bell Prize winning PETSc-FUN3D aerodynamics code, extending it with highly-tuned shared-memory parallelization and detailed performance analysis on modern highly parallel architectures. An unstructured-grid implicit flow solver, which forms the backbone of computational aerodynamics, poses particular challenges due to its large irregular working sets, unstructured memory accesses, and variable/limited amount of parallelism. This code, based on a domain decomposition approach, exposes tradeoffs between the number of threads assigned to each MPI-rank sub domain, and the total number of domains. By applying several algorithm- and architecture-aware optimization techniques for unstructured grids, we show a 6.9X speed-up in performance on a single-node Intel® XeonTM1 E5 2690 v2 processor relative to the out-of-the-box compilation. Our scaling studies on TACC Stampede supercomputer show that our optimizations continue to provide performance benefits over baseline implementation as we scale up to 256 nodes.

  2. Patients who share transparent visit notes with others: characteristics, risks, and benefits.

    Science.gov (United States)

    Jackson, Sara L; Mejilla, Roanne; Darer, Jonathan D; Oster, Natalia V; Ralston, James D; Leveille, Suzanne G; Walker, Jan; Delbanco, Tom; Elmore, Joann G

    2014-11-12

    Inviting patients to read their primary care visit notes may improve communication and help them engage more actively in their health care. Little is known about how patients will use the opportunity to share their visit notes with family members or caregivers, or what the benefits might be. Our goal was to evaluate the characteristics of patients who reported sharing their visit notes during the course of the study, including their views on associated benefits and risks. The OpenNotes study invited patients to access their primary care providers' visit notes in Massachusetts, Pennsylvania, and Washington. Pre- and post-intervention surveys assessed patient demographics, standardized measures of patient-doctor communication, sharing of visit notes with others during the study, and specific health behaviors reflecting the potential benefits and risks of offering patients easy access to their visit notes. More than half (55.43%, 2503/4516) of the participants who reported viewing at least one visit note would like the option of letting family members or friends have their own Web access to their visit notes, and 21.70% (980/4516) reported sharing their visit notes with someone during the study year. Men, and those retired or unable to work, were significantly more likely to share visit notes, and those sharing were neither more nor less concerned about their privacy than were non-sharers. Compared to participants who did not share clinic notes, those who shared were more likely to report taking better care of themselves and taking their medications as prescribed, after adjustment for age, gender, employment status, and study site. One in five OpenNotes patients shared a visit note with someone, and those sharing Web access to their visit notes reported better adherence to self-care and medications. As health information technology systems increase patients' ability to access their medical records, facilitating access to caregivers may improve perceived health

  3. Competition Leverage : How the Demand Side Affects Optimal Risk Adjustment

    NARCIS (Netherlands)

    Bijlsma, M.; Boone, J.; Zwart, Gijsbert

    2011-01-01

    We study optimal risk adjustment in imperfectly competitive health insurance markets when high-risk consumers are less likely to switch insurer than low-risk consumers. First, we find that insurers still have an incentive to select even if risk adjustment perfectly corrects for cost differences

  4. Patients Who Share Transparent Visit Notes With Others: Characteristics, Risks, and Benefits

    OpenAIRE

    Jackson, Sara L; Mejilla, Roanne; Darer, Jonathan D; Oster, Natalia V; Ralston, James D; Leveille, Suzanne G; Walker, Jan; Delbanco, Tom; Elmore, Joann G

    2014-01-01

    Background Inviting patients to read their primary care visit notes may improve communication and help them engage more actively in their health care. Little is known about how patients will use the opportunity to share their visit notes with family members or caregivers, or what the benefits might be. Objective Our goal was to evaluate the characteristics of patients who reported sharing their visit notes during the course of the study, including their views on associated benefits and risks....

  5. 78 FR 64145 - 30-Day Notice of Proposed Information Collection: Housing Finance Agency Risk-Sharing Program

    Science.gov (United States)

    2013-10-25

    ... Information Collection: Housing Finance Agency Risk-Sharing Program AGENCY: Office of the Chief Information... Title of Information Collection: Housing Finance Agency Risk- Sharing Program. OMB Approval Number: 2502... sharing with State and local housing finance agencies (HFAs). Under this program, HUD provides full...

  6. Is parent-child bed-sharing a risk for wheezing and asthma in early childhood?

    Science.gov (United States)

    Luijk, Maartje P C M; Sonnenschein-van der Voort, Agnes M M; Mileva-Seitz, Viara R; Jansen, Pauline W; Verhulst, Frank C; Hofman, Albert; Jaddoe, Vincent W V; de Jongste, Johan C; van IJzendoorn, Marinus H; Duijts, Liesbeth; Tiemeier, Henning

    2015-03-01

    Household crowding can place young children at risk for respiratory infections which subsequently provoke asthma symptoms. However, crowding might also protect against asthma, in accordance with the hygiene hypothesis. We tested if parent-infant bed-sharing, an important dimension of household crowding, increases or decreases the risk for asthma. In a population-based prospective cohort (N = 6160) we assessed bed-sharing at 2 and 24 months; wheezing between 1 and 6 years of age; and asthma at 6 years of age. Generalised estimating equation models were used to assess repeated measures of wheezing and asthma. We found no association between bed-sharing in early infancy and wheezing or diagnosis of asthma. By contrast, we found a positive association between bed-sharing in toddlerhood and both wheezing (OR 1.42, 95% CI 1.15-1.74) and asthma (OR 1.57, 95% CI 1.03-2.38). Wheezing was not associated with bed-sharing when using cross-lagged modelling. This study suggests that bed-sharing in toddlerhood is associated with an increased risk of asthma at later ages, and not vice versa. Further studies are needed to explore the underlying causal mechanisms. Copyright ©ERS 2015.

  7. The Formation of Optimal Portfolio of Mutual Shares Funds using Multi-Objective Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Yandra Arkeman

    2013-09-01

    Full Text Available Investments in financial assets have become a trend in the globalization era, especially the investment in mutual fund shares. Investors who want to invest in stock mutual funds can set up an investment portfolio in order to generate a minimal risk and maximum return. In this study the authors used the Multi-Objective Genetic Algorithm Non-dominated Sorting II (MOGA NSGA-II technique with the Markowitz portfolio principle to find the best portfolio from several mutual funds. The data used are 10 company stock mutual funds with a period of 12 months, 24 months and 36 months. The genetic algorithm parameters used are crossover probability of 0.65, mutation probability of 0.05, Generation 400 and a population numbering 20 individuals. The study produced a combination of the best portfolios for the period of 24 months with a computing time of 63,289 seconds.

  8. Optimal International Asset Allocation with Time-varying Risk

    OpenAIRE

    Flavin, Thomas; Wickens, M.R.

    2006-01-01

    This paper examines the optimal allocation each period of an internationally diversified portfolio from the different points of view of a UK and a US investor. We find that investor location affects optimal asset allocation. The presence of exchange rate risk causes the markets to appear not fully integrated and creates a preference for home assets. Domestic equity is the dominant asset in the optimal portfolio for both investors, but the US investor bears less risk than the UK...

  9. Risk-optimized proton therapy to minimize radiogenic second cancers

    DEFF Research Database (Denmark)

    Rechner, Laura A; Eley, John G; Howell, Rebecca M

    2015-01-01

    Proton therapy confers substantially lower predicted risk of second cancer compared with photon therapy. However, no previous studies have used an algorithmic approach to optimize beam angle or fluence-modulation for proton therapy to minimize those risks. The objectives of this study were...... to demonstrate the feasibility of risk-optimized proton therapy and to determine the combination of beam angles and fluence weights that minimizes the risk of second cancer in the bladder and rectum for a prostate cancer patient. We used 6 risk models to predict excess relative risk of second cancer. Treatment...

  10. INJECTING EQUPMENT SHARING AND PERCEPTION OF HIV AND HEPATITIS RISK AMONG INJECTING DRUG USERS IN BUDAPEST

    Science.gov (United States)

    Gyarmathy, V. Anna; Neaigus, Alan; Ujhelyi, Eszter

    2008-01-01

    In Central European states, rates of HIV among IDUs have been low although HCV infection is widespread. The goal of our study was to assess HIV infection, risk perceptions and injecting equipment sharing among injection drug users in Budapest, Hungary. Altogether 150 IDUs were interviewed (121 structured between 1999-2000 and 29 ethnographic between 2003-2004). The majority of them injected heroin (52% and 79%) and many injected amphetamines (51% and 35%). One person tested positive for HIV. Two thirds (68% of 121) shared injecting equipment (syringes, cookers and filters). Some participants said they shared syringes because they were not carrying them for fear of police harassment, and that they reused filters as a backup drug supply. In multivariate analysis, sharing of injecting equipment was associated with higher perceived susceptibility to HIV/AIDS, lower self-efficacy for sterile equipment use, higher motivation to comply with peer pressure to use dirty injecting equipment, and with having a criminal record. The high levels of injecting risk behaviors found in this study are a cause for serious concern. HIV prevention interventions need to address not only sharing syringes but also sharing and reusing other injecting equipment and drug filters. PMID:17129858

  11. Improved Adaptive Droop Control Design for Optimal Power Sharing in VSC-MTDC Integrating Wind Farms

    Directory of Open Access Journals (Sweden)

    Xiaohong Ran

    2015-07-01

    Full Text Available With the advance of insulated gate bipolar transistor (IGBT converters, Multi-Terminal DC (MTDC based on the voltage-source converter (VSC has developed rapidly in renewable and electric power systems. To reduce the copper loss of large capacity and long distance DC transmission line, an improved droop control design based on optimal power sharing in VSC-MTDC integrating offshore wind farm is proposed. The proposed approach provided a calculation method for power-voltage droop coefficients under two different scenarios either considering local load or not. The available headroom of each converter station was considered as a converter outage, to participate in the power adjustment according to their ability. A four-terminal MTDC model system including two large scale wind farms was set up in PSCAD/EMTDC. Then, the proposed control strategy was verified through simulation under the various conditions, including wind speed variation, rectifier outage and inverter outage, and a three-phase short-circuit of the converter.

  12. The Effect of Teachers' Shared Leadership Perception on Academic Optimism and Organizational Citizenship Behaviour: A Turkish Case

    Science.gov (United States)

    Akin Kösterelioglu, Meltem

    2017-01-01

    Purpose: The present study investigates the capability of high school teachers' shared leadership perception to predict the academic optimism and organizational citizenship levels. Research methods: The population of the current descriptive study, which was conducted via screening model, consists of 321 high school teachers working for Amasya…

  13. Intergenerational risk sharing and endogenous labour supply within funded pension schemes

    NARCIS (Netherlands)

    Bonenkamp, J.; Westerhout, E.

    2014-01-01

    Funded defined-benefit pensions add to welfare on account of providing intergenerational risk sharing, but lower it on account of inducing labour supply distortions. We show that a properly designed funded defined-benefit pension scheme involves a welfare improvement even if contributions are

  14. TEACHING WRITING USING THINK-PAIR-SHARE VIEWED FROM STUDENTS’ LEVEL OF RISK-TAKING

    Directory of Open Access Journals (Sweden)

    Ningtyas Orilina Argawati

    2017-12-01

    Full Text Available Writing is considered as the most difficult skill to master compared with the other skills because it involves many language elements such as content, organization, vocabulary, grammar and mechanics. The research examines the effect of two independent variables (Think-Pair-Share and Direct instruction method on dependent variable (Writing Descriptive skill. The samples were class A1 2016 as the experimental class and A3 2016 as the control class. Each class consisted of 32 students. The instruments used covered the risk-taking’s questionnaire and writing test. Before applying the questionnaire of risk-taking, it was tried out to class A2 2016 to find out the validity and the reliability of the instrument. Meanwhile, before conducting the writing test, it needs to test the readability of the writing instruction. The treatment was conducted in eight meetings, and the 9th meeting was allocated for the post-test. The data were then analyzed using ANOVA and Tukey test. From the analysis, it reveals that: (1 Think-Pair-Share is significantly different from direct instruction method to teach writing; (2 the students with high level of risk-taking have better writing than those with low level of risk-taking; and (3 there is an interaction between teaching methods and the students’ level of risk-taking. Even though Think-Pair-Share is effective to teach writing, teachers must consider about the students’ condition, in this case their level of risk-taking.

  15. Genome-wide association study identifies shared risk loci common to two malignancies in golden retrievers.

    Directory of Open Access Journals (Sweden)

    Noriko Tonomura

    2015-02-01

    Full Text Available Dogs, with their breed-determined limited genetic background, are great models of human disease including cancer. Canine B-cell lymphoma and hemangiosarcoma are both malignancies of the hematologic system that are clinically and histologically similar to human B-cell non-Hodgkin lymphoma and angiosarcoma, respectively. Golden retrievers in the US show significantly elevated lifetime risk for both B-cell lymphoma (6% and hemangiosarcoma (20%. We conducted genome-wide association studies for hemangiosarcoma and B-cell lymphoma, identifying two shared predisposing loci. The two associated loci are located on chromosome 5, and together contribute ~20% of the risk of developing these cancers. Genome-wide p-values for the top SNP of each locus are 4.6×10-7 and 2.7×10-6, respectively. Whole genome resequencing of nine cases and controls followed by genotyping and detailed analysis identified three shared and one B-cell lymphoma specific risk haplotypes within the two loci, but no coding changes were associated with the risk haplotypes. Gene expression analysis of B-cell lymphoma tumors revealed that carrying the risk haplotypes at the first locus is associated with down-regulation of several nearby genes including the proximal gene TRPC6, a transient receptor Ca2+-channel involved in T-cell activation, among other functions. The shared risk haplotype in the second locus overlaps the vesicle transport and release gene STX8. Carrying the shared risk haplotype is associated with gene expression changes of 100 genes enriched for pathways involved in immune cell activation. Thus, the predisposing germ-line mutations in B-cell lymphoma and hemangiosarcoma appear to be regulatory, and affect pathways involved in T-cell mediated immune response in the tumor. This suggests that the interaction between the immune system and malignant cells plays a common role in the tumorigenesis of these relatively different cancers.

  16. Stochastic optimization under risk constraint and utility functions

    International Nuclear Information System (INIS)

    Seck, B.

    2008-09-01

    In a context of concurrence and emergence of energy markets, the production of electricity is affected by the new sources of risks which are the price variations on the energy markets. These new sources of risks generate a new risk: the market risk. In this research, the author explores the possibility of introducing constraints, expressed by measurements of risk, into the process of optimization of electricity production when financial contracts are signed on the energy market. The author makes the distinction between the engineering approach (taking the risk into account by risk measurements) and the economist approach (taking the risk into account by utility functions). After an overview of these both approaches in a static framework, he gives an economical formulation (a Maccheroni type one) for a static optimization problem under a risk constraint when the risk measurement is written under the form of an expected infimum like the variance, the 'conditional value at risk', and so on. The obtained results are then extended to a dynamic optimization framework under risk constraints. A numerical application of this approach is presented to solve a problem of electricity production management under a constraint of 'conditional value at risk' on a middle term

  17. Impact of catch shares on diversification of fishers' income and risk.

    Science.gov (United States)

    Holland, Daniel S; Speir, Cameron; Agar, Juan; Crosson, Scott; DePiper, Geret; Kasperski, Stephen; Kitts, Andrew W; Perruso, Larry

    2017-08-29

    Many fishers diversify their income by participating in multiple fisheries, which has been shown to significantly reduce year-to-year variation in income. The ability of fishers to diversify has become increasingly constrained in the last few decades, and catch share programs could further reduce diversification as a result of consolidation. This could increase income variation and thus financial risk. However, catch shares can also offer fishers opportunities to enter or increase participation in catch share fisheries by purchasing or leasing quota. Thus, the net effect on diversification is uncertain. We tested whether diversification and variation in fishing revenues changed after implementation of catch shares for 6,782 vessels in 13 US fisheries that account for 20% of US landings revenue. For each of these fisheries, we tested whether diversification levels, trends, and variation in fishing revenues changed after implementation of catch shares, both for fishers that remained in the catch share fishery and for those that exited but remained active in other fisheries. We found that diversification for both groups was nearly always reduced. However, in most cases, we found no significant change in interannual variation of revenues, and, where changes were significant, variation decreased nearly as often as it increased.

  18. Risk:reward sharing contracts in the oil industry: the effects of bonus:penalty schemes

    International Nuclear Information System (INIS)

    Kemp, A.G.; Stephen, L.

    1999-01-01

    Partnering and alliancing among oil companies and their contractors have become common in the oil industry in recent years. The risk:reward mechanisms established very often incorporate bonus/penalty schemes in relation to agreed base values. This paper examines the efficiency requirements of such schemes. The effects of project cost and completion risks on the risk: reward positions of field investors and contractors with and without bonus/penalty schemes are examined with the aid of Monte Carlo simulation analysis. The schemes increase the total risk for contractors and have consequence for their cost of capital and optimal risk-bearing arrangements within the industry. (author)

  19. Assessing the evidence for shared genetic risks across psychiatric disorders and traits.

    Science.gov (United States)

    Martin, Joanna; Taylor, Mark J; Lichtenstein, Paul

    2017-12-04

    Genetic influences play a significant role in risk for psychiatric disorders, prompting numerous endeavors to further understand their underlying genetic architecture. In this paper, we summarize and review evidence from traditional twin studies and more recent genome-wide molecular genetic analyses regarding two important issues that have proven particularly informative for psychiatric genetic research. First, emerging results are beginning to suggest that genetic risk factors for some (but not all) clinically diagnosed psychiatric disorders or extreme manifestations of psychiatric traits in the population share genetic risks with quantitative variation in milder traits of the same disorder throughout the general population. Second, there is now evidence for substantial sharing of genetic risks across different psychiatric disorders. This extends to the level of characteristic traits throughout the population, with which some clinical disorders also share genetic risks. In this review, we summarize and evaluate the evidence for these two issues, for a range of psychiatric disorders. We then critically appraise putative interpretations regarding the potential meaning of genetic correlation across psychiatric phenotypes. We highlight several new methods and studies which are already using these insights into the genetic architecture of psychiatric disorders to gain additional understanding regarding the underlying biology of these disorders. We conclude by outlining opportunities for future research in this area.

  20. Optimal annuity portfolio under inflation risk

    DEFF Research Database (Denmark)

    Konicz, Agnieszka Karolina; Pisinger, David; Weissensteiner, Alex

    2015-01-01

    The paper investigates the importance of in ation-linked annuities to individuals facing in ation risk. Given the investment opportunities in nominal, real, and variable annuities, as well as cash and stocks, we investigate the consumption and investment decisions under two different objective fu...... and risk aversion, real annuities are a crucial asset in every portfolio. In addition, without investing in real annuities, the retiree has to rebalance the portfolio more frequently, and still obtains the lower and more volatile real consumption....

  1. Indirect Reciprocity, Resource Sharing, and Environmental Risk: Evidence from Field Experiments in Siberia

    Science.gov (United States)

    Howe, E. Lance; Murphy, James J.; Gerkey, Drew; West, Colin Thor

    2016-01-01

    Integrating information from existing research, qualitative ethnographic interviews, and participant observation, we designed a field experiment that introduces idiosyncratic environmental risk and a voluntary sharing decision into a standard public goods game. Conducted with subsistence resource users in rural villages on the Kamchatka Peninsula in Northeast Siberia, we find evidence consistent with a model of indirect reciprocity and local social norms of helping the needy. When participants are allowed to develop reputations in the experiments, as is the case in most small-scale societies, we find that sharing is increasingly directed toward individuals experiencing hardship, good reputations increase aid, and the pooling of resources through voluntary sharing becomes more effective. We also find high levels of voluntary sharing without a strong commitment device; however, this form of cooperation does not increase contributions to the public good. Our results are consistent with previous experiments and theoretical models, suggesting strategic risks tied to rewards, punishments, and reputations are important. However, unlike studies that focus solely on strategic risks, we find the effects of rewards, punishments, and reputations are altered by the presence of environmental factors. Unexpected changes in resource abundance increase interdependence and may alter the costs and benefits of cooperation, relative to defection. We suggest environmental factors that increase interdependence are critically important to consider when developing and testing theories of cooperation PMID:27442434

  2. Risk mitigation of shared electronic records system in campus institutions: medical social work practice in singapore.

    Science.gov (United States)

    Ow Yong, Lai Meng; Tan, Amanda Wei Li; Loo, Cecilia Lay Keng; Lim, Esther Li Ping

    2014-10-01

    In 2013, the Singapore General Hospital (SGH) Campus initiated a shared electronic system where patient records and documentations were standardized and shared across institutions within the Campus. The project was initiated to enhance quality of health care, improve accessibility, and ensure integrated (as opposed to fragmented) care for best outcomes in our patients. In mitigating the risks of ICT, it was found that familiarity with guiding ethical principles, and ensuring adherence to regulatory and technical competencies in medical social work were important. The need to negotiate and maneuver in a large environment within the Campus to ensure proactive integrative process helped.

  3. Risk-adaptive optimization: Selective boosting of high-risk tumor subvolumes

    International Nuclear Information System (INIS)

    Kim, Yusung; Tome, Wolfgang A.

    2006-01-01

    Background and Purpose: A tumor subvolume-based, risk-adaptive optimization strategy is presented. Methods and Materials: Risk-adaptive optimization employs a biologic objective function instead of an objective function based on physical dose constraints. Using this biologic objective function, tumor control probability (TCP) is maximized for different tumor risk regions while at the same time minimizing normal tissue complication probability (NTCP) for organs at risk. The feasibility of risk-adaptive optimization was investigated for a variety of tumor subvolume geometries, risk-levels, and slopes of the TCP curve. Furthermore, the impact of a correlation parameter, δ, between TCP and NTCP on risk-adaptive optimization was investigated. Results: Employing risk-adaptive optimization, it is possible in a prostate cancer model to increase the equivalent uniform dose (EUD) by up to 35.4 Gy in tumor subvolumes having the highest risk classification without increasing predicted normal tissue complications in organs at risk. For all tumor subvolume geometries investigated, we found that the EUD to high-risk tumor subvolumes could be increased significantly without increasing normal tissue complications above those expected from a treatment plan aiming for uniform dose coverage of the planning target volume. We furthermore found that the tumor subvolume with the highest risk classification had the largest influence on the design of the risk-adaptive dose distribution. The parameter δ had little effect on risk-adaptive optimization. However, the clinical parameters D 5 and γ 5 that represent the risk classification of tumor subvolumes had the largest impact on risk-adaptive optimization. Conclusions: On the whole, risk-adaptive optimization yields heterogeneous dose distributions that match the risk level distribution of different subvolumes within the tumor volume

  4. Optimal natural resources management under uncertainty with catastrophic risk

    Energy Technology Data Exchange (ETDEWEB)

    Motoh, Tsujimura [Graduate School of Economics, Kyoto University, Yoshida-honmochi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2004-05-01

    We examine an optimal natural resources management problem under uncertainty with catastrophic risk and investigate the optimal rate of use of a natural resource. For this purpose, we use stochastic control theory. We assume that, until a catastrophic event occurs, the stock of the natural resource is governed by a stochastic differential equation. We describe the catastrophic phenomenon as a Poisson process. From this analysis, we show the optimal rate of use of the natural resource in explicit form. Furthermore, we present comparative static results for the optimal rate of use of the natural resource.

  5. Optimal natural resources management under uncertainty with catastrophic risk

    International Nuclear Information System (INIS)

    Motoh, Tsujimura

    2004-01-01

    We examine an optimal natural resources management problem under uncertainty with catastrophic risk and investigate the optimal rate of use of a natural resource. For this purpose, we use stochastic control theory. We assume that, until a catastrophic event occurs, the stock of the natural resource is governed by a stochastic differential equation. We describe the catastrophic phenomenon as a Poisson process. From this analysis, we show the optimal rate of use of the natural resource in explicit form. Furthermore, we present comparative static results for the optimal rate of use of the natural resource

  6. An Optimization of the Risk Management using Derivatives

    Directory of Open Access Journals (Sweden)

    Ovidiu ŞONTEA

    2011-07-01

    Full Text Available This article aims to provide a process that can be used in financial risk management by resolving problems of minimizing the risk measure (VaR using derivatives products, bonds and options. This optimization problem was formulated in the hedging situation of a portfolio formed by an active and a put option on this active, respectively a bond and an option on this bond. In the first optimization problem we will obtain the coverage ratio of the optimal price for the excertion of the option which is in fact the relative cost of the option’s value. In the second optimization problem we obtained optimal exercise price for a put option which is to support a bond.

  7. Risk-optimized proton therapy to minimize radiogenic second cancers

    Science.gov (United States)

    Rechner, Laura A.; Eley, John G.; Howell, Rebecca M.; Zhang, Rui; Mirkovic, Dragan; Newhauser, Wayne D.

    2015-01-01

    Proton therapy confers substantially lower predicted risk of second cancer compared with photon therapy. However, no previous studies have used an algorithmic approach to optimize beam angle or fluence-modulation for proton therapy to minimize those risks. The objectives of this study were to demonstrate the feasibility of risk-optimized proton therapy and to determine the combination of beam angles and fluence weights that minimize the risk of second cancer in the bladder and rectum for a prostate cancer patient. We used 6 risk models to predict excess relative risk of second cancer. Treatment planning utilized a combination of a commercial treatment planning system and an in-house risk-optimization algorithm. When normal-tissue dose constraints were incorporated in treatment planning, the risk model that incorporated the effects of fractionation, initiation, inactivation, and repopulation selected a combination of anterior and lateral beams, which lowered the relative risk by 21% for the bladder and 30% for the rectum compared to the lateral-opposed beam arrangement. Other results were found for other risk models. PMID:25919133

  8. 78 FR 65696 - 30-Day Notice of Proposed Information Collection: Housing Finance Agency Risk-Sharing Program

    Science.gov (United States)

    2013-11-01

    ... Information Collection: Housing Finance Agency Risk-Sharing Program AGENCY: Office of the Chief Information... Information Collection: Housing Finance Agency Risk- Sharing Program. OMB Approval Number: 2502-0500. Type of... housing finance agencies (HFAs). Under this program, HUD provides full mortgage insurance on multifamily...

  9. Multistage Logistic Network Optimization under Disruption Risk

    OpenAIRE

    Rusman, Muhammad

    2013-01-01

    Getting over disruptions risk has been a challenging issue for many companies under the globalization that will link to potential external source such as demand uncertainties, natural disasters, and terrorist attacks. The disruption is an unexpected event that disturbs normal flows of products and materials within a supply chain. The disruption at one members of supply chain will propagate the offers and finally affect significant impacts on the entire chain. If we look back...

  10. Risk Sharing in Corporate and Public Finance: The Contribution of Islamic Finance

    Directory of Open Access Journals (Sweden)

    Obiyathulla Ismath Bacha

    2015-09-01

    Full Text Available Financial crises have become a recurring problem for modern economies with increasingly detrimental fallouts. Risk-sharing finance (RSF contracts may be the best instrument for addressing the problem and its fallout, and in particular the risk-sharing principles of Islamic finance offer a potential alternative. This paper offers some preliminary thoughts on the design and implementation of RSF for both private and public sector funding, for revenue and non-revenue generating projects. It is argued that such form of financing avoids the leverage of conventional debt, minimizes the costs of dilution, reduces macroeconomic vulnerability, and enhances financial inclusion. It also has the potential to be a less risky alternative for developing countries to finance public spending and economic growth. JEL Classifications: G32, P43, O16

  11. Profit and Risk Measures in Oil Production Optimization

    DEFF Research Database (Denmark)

    Capolei, Andrea; Foss, Bjarne; Jørgensen, John Bagterp

    2015-01-01

    In oil production optimization, we usually aim to maximize a deterministic scalar performance index such as the profit over the expected reservoir lifespan. However, when uncertainty in the parameters is considered, the profit results in a random variable that can assume a range of values dependi...... pro and cons for each of them. Finally, among the presented risk measures, we identify two of them as appropriate risk measures when minimizing the risk....

  12. Entanglement sharing via qudit channels: Nonmaximally entangled states may be necessary for one-shot optimal singlet fraction and negativity

    Science.gov (United States)

    Pal, Rajarshi; Bandyopadhyay, Somshubhro

    2018-03-01

    We consider the problem of establishing entangled states of optimal singlet fraction and negativity between two remote parties for every use of a noisy quantum channel and trace-preserving local operations and classical communication (LOCC) under the assumption that the parties do not share prior correlations. We show that for a family of quantum channels in every finite dimension d ≥3 , one-shot optimal singlet fraction and entanglement negativity are attained only with appropriate nonmaximally entangled states. A consequence of our results is that the ordering of entangled states in all finite dimensions may not be preserved under trace-preserving LOCC.

  13. Setting the Stage for Harmonized Risk Assessment by Seismic Hazard Harmonization in Europe (SHARE)

    Science.gov (United States)

    Woessner, Jochen; Giardini, Domenico; SHARE Consortium

    2010-05-01

    Probabilistic seismic hazard assessment (PSHA) is arguably one of the most useful products that seismology can offer to society. PSHA characterizes the best available knowledge on the seismic hazard of a study area, ideally taking into account all sources of uncertainty. Results form the baseline for informed decision making, such as building codes or insurance rates and provide essential input to each risk assessment application. Several large scale national and international projects have recently been launched aimed at improving and harmonizing PSHA standards around the globe. SHARE (www.share-eu.org) is the European Commission funded project in the Framework Programme 7 (FP-7) that will create an updated, living seismic hazard model for the Euro-Mediterranean region. SHARE is a regional component of the Global Earthquake Model (GEM, www.globalquakemodel.org), a public/private partnership initiated and approved by the Global Science Forum of the OECD-GSF. GEM aims to be the uniform, independent and open access standard to calculate and communicate earthquake hazard and risk worldwide. SHARE itself will deliver measurable progress in all steps leading to a harmonized assessment of seismic hazard - in the definition of engineering requirements, in the collection of input data, in procedures for hazard assessment, and in engineering applications. SHARE scientists will create a unified framework and computational infrastructure for seismic hazard assessment and produce an integrated European probabilistic seismic hazard assessment (PSHA) model and specific scenario based modeling tools. The results will deliver long-lasting structural impact in areas of societal and economic relevance, they will serve as reference for the Eurocode 8 (EC8) application, and will provide homogeneous input for the correct seismic safety assessment for critical industry, such as the energy infrastructures and the re-insurance sector. SHARE will cover the whole European territory, the

  14. Optimization and parallelization of B-spline based orbital evaluations in QMC on multi/many-core shared memory processors

    OpenAIRE

    Mathuriya, Amrita; Luo, Ye; Benali, Anouar; Shulenburger, Luke; Kim, Jeongnim

    2016-01-01

    B-spline based orbital representations are widely used in Quantum Monte Carlo (QMC) simulations of solids, historically taking as much as 50% of the total run time. Random accesses to a large four-dimensional array make it challenging to efficiently utilize caches and wide vector units of modern CPUs. We present node-level optimizations of B-spline evaluations on multi/many-core shared memory processors. To increase SIMD efficiency and bandwidth utilization, we first apply data layout transfo...

  15. A Heuristic Design Information Sharing Framework for Hard Discrete Optimization Problems

    National Research Council Canada - National Science Library

    Jacobson, Sheldon H

    2007-01-01

    .... This framework has been used to gain new insights into neighborhood structure designs that allow different neighborhood functions to share information when using the same heuristic applied to the same problem...

  16. Educational differences in cardiovascular mortality: The role of shared family factors and cardiovascular risk factors.

    Science.gov (United States)

    Kjøllesdal, M K R; Ariansen, I; Mortensen, L H; Davey Smith, G; Næss, Ø

    2016-12-01

    To explore the confounding effects of early family factors shared by siblings and cardiovascular risk factors in midlife on the educational differences in mortality from cardiovascular disease (CVD). Data from national and regional health surveys in Norway (1974-2003) were linked with data from the Norwegian Family Based Life Course Study, the National Educational Registry and the Cause of Death Registry. The study population consisted of participants with at least one full sibling among the health survey participants ( n=271,310). Data were available on CVD risk factors, including weight, height, blood pressure, total cholesterol and smoking. The hazards ratio (HR) of CVD mortality was 3.44 (95% confidence interval (CI) 2.98-3.96) in the lowest educational group relative to the highest. The HRs were little altered in the within-sibship analyses. Adjusted for risk factors, the HR for CVD mortality in the cohort analyses was 2.05 (CI 1.77-2.37) in the lowest educational group relative to the highest. The respective HR in the within-sibship analyses was 2.46 (CI 1.48-2.24). Using a sibling design, we did not find that the association between education and CVD mortality was confounded by early life factors shared by siblings, but it was explained to a large extent by CVD risk factors. These results suggest that reducing levels of CVD risk factors could have the greatest effect on mortality in less well-educated people.

  17. Risk spreading, connectivity, and optimal reserve spacing.

    Science.gov (United States)

    Blowes, Shane A; Connolly, Sean R

    2012-01-01

    Two important processes determining the dynamics of spatially structured populations are dispersal and the spatial covariance of demographic fluctuations. Spatially explicit approaches to conservation, such as reserve networks, must consider the tension between these two processes and reach a balance between distances near enough to maintain connectivity, but far enough to benefit from risk spreading. Here, we model this trade-off. We show how two measures of metapopulation persistence depend on the shape of the dispersal kernel and the shape of the distance decay in demographic covariance, and we consider the implications of this trade-off for reserve spacing. The relative rates of distance decay in dispersal and demographic covariance determine whether the long-run metapopulation growth rate, and quasi-extinction risk, peak for adjacent patches or intermediately spaced patches; two local maxima in metapopulation persistence are also possible. When dispersal itself fluctuates over time, the trade-off changes. Temporal variation in mean distance that propagules are dispersed (i.e., propagule advection) decreases metapopulation persistence and decreases the likelihood that persistence will peak for adjacent patches. Conversely, variation in diffusion (the extent of random spread around mean dispersal) increases metapopulation persistence overall and causes it to peak at shorter inter-patch distances. Thus, failure to consider temporal variation in dispersal processes increases the risk that reserve spacings will fail to meet the objective of ensuring metapopulation persistence. This study identifies two phenomena that receive relatively little attention in empirical work on reserve spacing, but that can qualitatively change the effectiveness of reserve spacing strategies: (1) the functional form of the distance decay in covariance among patch-specific demographic rates and (2) temporal variation in the shape of the dispersal kernel. The sensitivity of metapopulation

  18. Scenarios for the risk of hunger in the twenty-first century using Shared Socioeconomic Pathways

    International Nuclear Information System (INIS)

    Hasegawa, Tomoko; Fujimori, Shinichiro; Takahashi, Kiyoshi; Masui, Toshihiko

    2015-01-01

    Shared socioeconomic pathways (SSPs) are being developed internationally for cross-sectoral assessments of climate change impacts, adaptation, and mitigation. These are five scenarios that include both qualitative and quantitative information for mitigation and adaptation challenges to climate change. In this study, we quantified scenarios for the risk of hunger in the 21st century using SSPs, and clarified elements that influence future hunger risk. There were two primary findings: (1) risk of hunger in the 21st-century greatly differed among five SSPs; and (2) population growth, improvement in the equality of food distribution within a country, and increases in food consumption mainly driven by income growth greatly influenced future hunger risk and were important elements in its long-term assessment. (letter)

  19. Sharing of Needles and Syringes among Men Who Inject Drugs: HIV Risk in Northwest Bangladesh.

    Directory of Open Access Journals (Sweden)

    M Kamal Pasa

    Full Text Available Injection drug use is prevalent in northwestern Bangladesh. We sought to explore the context of needle/syringe sharing among persons who inject drugs (PWID, examining risk exposures to blood-borne infections like the human immunodeficiency virus (HIV and hepatitis in a region where these dual epidemics are likely to expand.We used a qualitative research approach to learn about injection practices, conducting 60 in-depth interviews among PWID. We then conducted 12 focus group discussions (FGDs that generated a checklist of salient issues, and followed up with personal observations of typical days at the drug-use venues. Content and interpretative frameworks were used to analyze qualitative information and socio-demographic information, using SPSS software.We found that needle/syringe-sharing behaviours were integrated into the overall social and cultural lives of drug users. Sharing behaviours were an central component of PWID social organization. Sharing was perceived as an inherent element within reciprocal relationships, and sharing was tied to beliefs about drug effects, economic adversity, and harassment due to their drug user status. Carrying used needles/syringes to drug-use venues was deemed essential since user-unfriendly needle-syringe distribution schedules of harm reduction programmes made it difficult to access clean needles/syringes in off-hours. PWID had low self-esteem. Unequal power relationships were reported between the field workers of harm reduction programmes and PWID. Field workers expressed anti-PWID bias and judgmental attitudes, and also had had misconceptions about HIV and hepatitis transmission. PWID were especially disturbed that no assistance was forthcoming from risk reduction programme staff when drug users manifested withdrawal symptoms.Interventions must take social context into account when scaling up programmes in diverse settings. The social organization of PWID include values that foster needle

  20. [Targeting high-risk drugs to optimize clinical pharmacists' intervention].

    Science.gov (United States)

    Mouterde, Anne-Laure; Bourdelin, Magali; Maison, Ophélie; Coursier, Sandra; Bontemps, Hervé

    2016-12-01

    By the Order of 6 April 2011, the pharmacist must validate all the prescriptions containing "high-risk drugs" or those of "patients at risk". To optimize this clinical pharmacy activity, we identified high-risk drugs. A list of high-risk drugs has been established using literature, pharmacists' interventions (PI) performed in our hospital and a survey sent to hospital pharmacists. In a prospective study (analysis of 100 prescriptions for each high-risk drug selected), we have identified the most relevant to target. We obtained a statistically significant PI rate (P<0.05) for digoxin, oral anticoagulants direct, oral methotrexate and colchicine. This method of targeted pharmaceutical validation based on high-risk drugs is relevant to detect patients with high risk of medicine-related illness. Copyright © 2016 Société française de pharmacologie et de thérapeutique. Published by Elsevier Masson SAS. All rights reserved.

  1. Risk Stratification and Shared Decision Making for Colorectal Cancer Screening: A Randomized Controlled Trial.

    Science.gov (United States)

    Schroy, Paul C; Duhovic, Emir; Chen, Clara A; Heeren, Timothy C; Lopez, William; Apodaca, Danielle L; Wong, John B

    2016-05-01

    Eliciting patient preferences within the context of shared decision making has been advocated for colorectal cancer (CRC) screening, yet providers often fail to comply with patient preferences that differ from their own. To determine whether risk stratification for advanced colorectal neoplasia (ACN) influences provider willingness to comply with patient preferences when selecting a desired CRC screening option. Randomized controlled trial. Asymptomatic, average-risk patients due for CRC screening in an urban safety net health care setting. Patients were randomized 1:1 to a decision aid alone (n= 168) or decision aid plus risk assessment (n= 173) arm between September 2012 and September 2014. The primary outcome was concordance between patient preference and test ordered; secondary outcomes included patient satisfaction with the decision-making process, screening intentions, test completion rates, and provider satisfaction. Although providers perceived risk stratification to be useful in selecting an appropriate screening test for their average-risk patients, no significant differences in concordance were observed between the decision aid alone and decision aid plus risk assessment groups (88.1% v. 85.0%,P= 0.40) or high- and low-risk groups (84.5% v. 87.1%,P= 0.51). Concordance was highest for colonoscopy and relatively low for tests other than colonoscopy, regardless of study arm or risk group. Failure to comply with patient preferences was negatively associated with satisfaction with the decision-making process, screening intentions, and test completion rates. Single-institution setting; lack of provider education about the utility of risk stratification into their decision making. Providers perceived risk stratification to be useful in their decision making but often failed to comply with patient preferences for tests other than colonoscopy, even among those deemed to be at low risk of ACN. © The Author(s) 2016.

  2. The PREVIEW Global Risk Data Platform: a geoportal to serve and share global data on risk to natural hazards

    Directory of Open Access Journals (Sweden)

    G. Giuliani

    2011-01-01

    Full Text Available With growing world population and concentration in urban and coastal areas, the exposure to natural hazards is increasing and results in higher risk of human and economic losses. Improving the identification of areas, population and assets potentially exposed to natural hazards is essential to reduce the consequences of such events. Disaster risk is a function of hazard, exposure and vulnerability. Modelling risk at the global level requires accessing and processing a large number of data, from numerous collaborating centres.

    These data need to be easily updated, and there is a need for centralizing access to this information as well as simplifying its use for non GIS specialists. The Hyogo Framework for Action provides the mandate for data sharing, so that governments and international development agencies can take appropriate decision for disaster risk reduction.

    Timely access and easy integration of geospatial data are essential to support efforts in Disaster Risk Reduction. However various issues in data availability, accessibility and integration limit the use of such data. In consequence, a framework that facilitate sharing and exchange of geospatial data on natural hazards should improve decision-making process. The PREVIEW Global Risk Data Platform is a highly interactive web-based GIS portal supported by a Spatial Data Infrastructure that offers free and interoperable access to more than 60 global data sets on nine types of natural hazards (tropical cyclones and related storm surges, drought, earthquakes, biomass fires, floods, landslides, tsunamis and volcanic eruptions and related exposure and risk. This application portrays an easy-to-use online interactive mapping interface so that users can easily work with it and seamlessly integrate data in their own data flow using fully compliant OGC Web Services (OWS.

  3. The PREVIEW Global Risk Data Platform: a geoportal to serve and share global data on risk to natural hazards

    Science.gov (United States)

    Giuliani, G.; Peduzzi, P.

    2011-01-01

    With growing world population and concentration in urban and coastal areas, the exposure to natural hazards is increasing and results in higher risk of human and economic losses. Improving the identification of areas, population and assets potentially exposed to natural hazards is essential to reduce the consequences of such events. Disaster risk is a function of hazard, exposure and vulnerability. Modelling risk at the global level requires accessing and processing a large number of data, from numerous collaborating centres. These data need to be easily updated, and there is a need for centralizing access to this information as well as simplifying its use for non GIS specialists. The Hyogo Framework for Action provides the mandate for data sharing, so that governments and international development agencies can take appropriate decision for disaster risk reduction. Timely access and easy integration of geospatial data are essential to support efforts in Disaster Risk Reduction. However various issues in data availability, accessibility and integration limit the use of such data. In consequence, a framework that facilitate sharing and exchange of geospatial data on natural hazards should improve decision-making process. The PREVIEW Global Risk Data Platform is a highly interactive web-based GIS portal supported by a Spatial Data Infrastructure that offers free and interoperable access to more than 60 global data sets on nine types of natural hazards (tropical cyclones and related storm surges, drought, earthquakes, biomass fires, floods, landslides, tsunamis and volcanic eruptions) and related exposure and risk. This application portrays an easy-to-use online interactive mapping interface so that users can easily work with it and seamlessly integrate data in their own data flow using fully compliant OGC Web Services (OWS).

  4. Assessing predation risk: optimal behaviour and rules of thumb.

    Science.gov (United States)

    Welton, Nicky J; McNamara, John M; Houston, Alasdair I

    2003-12-01

    We look at a simple model in which an animal makes behavioural decisions over time in an environment in which all parameters are known to the animal except predation risk. In the model there is a trade-off between gaining information about predation risk and anti-predator behaviour. All predator attacks lead to death for the prey, so that the prey learns about predation risk by virtue of the fact that it is still alive. We show that it is not usually optimal to behave as if the current unbiased estimate of the predation risk is its true value. We consider two different ways to model reproduction; in the first scenario the animal reproduces throughout its life until it dies, and in the second scenario expected reproductive success depends on the level of energy reserves the animal has gained by some point in time. For both of these scenarios we find results on the form of the optimal strategy and give numerical examples which compare optimal behaviour with behaviour under simple rules of thumb. The numerical examples suggest that the value of the optimal strategy over the rules of thumb is greatest when there is little current information about predation risk, learning is not too costly in terms of predation, and it is energetically advantageous to learn about predation. We find that for the model and parameters investigated, a very simple rule of thumb such as 'use the best constant control' performs well.

  5. Improvement of the Torque-Speed Performance and Drive Efficiency in an SRM Using an Optimal Torque Sharing Function

    Directory of Open Access Journals (Sweden)

    Wei Ye

    2018-05-01

    Full Text Available In this paper, by evaluating the extreme value of the qth-power current, a torque sharing function (TSF family for reducing the torque ripples in the switched reluctance motor (SRM is proposed. The optimization criteria of the TSF has two secondary objectives, including the maximization of the torque-speed range and the minimization of copper loss. The evaluation indices in terms of the peak phase current, the rms (root mean square phase current, and the torque ripple factor are compared between the proposed TSF family and four conventional TSFs including linear, sinusoidal, exponential, and cubic TSFs. An optimization objective function that combines the maximum absolute value of the rate-of-change of the flux linkage (MAV-RCFL and the qth-power of current is proposed and a weighting factor is used to balance the influence of the two optimization objectives. An optimal TSF can be easily obtained by solving the optimization problem from the TSF family. The proposed TSF is validated by using simulations and experiments with a three-phase 6/4 SRM with 7.5 kW, 3000 rpm, and 270 V DC-link voltage. The dynamic simulation model is implemented in Matlab/Simulink. The results demonstrate the validity and superiority of the proposed control method; the optimal TSF provides better torque-speed performance, and a better reduction in copper loss and torque ripples at high speed, as compared to conventional TSFs.

  6. Do adolescent delinquency and problem drinking share psychosocial risk factors? A literature review.

    Science.gov (United States)

    Curcio, Angela L; Mak, Anita S; George, Amanda M

    2013-04-01

    Despite the prevalence and damaging effects of adolescent problem drinking, relative to delinquency, far less research has focused on drinking using an integrated theoretical approach. The aim of the current research was to review existing literature on psychosocial risk factors for delinquency and problem drinking, and explore whether integrating elements of social learning theory with an established psychosocial control theory of delinquency could explain adolescent problem drinking. We reviewed 71 studies published post-1990 with particular focus on articles that empirically researched risk factors for adolescent problem drinking and delinquency in separate and concurrent studies and meta-analytic reviews. We found shared risk factors for adolescent delinquency and problem drinking that are encompassed by an extension of psychosocial control theory. The potential of an extended psychosocial control theory providing a parsimonious theoretical approach to explaining delinquency, problem drinking and other adolescent problem behaviours, along with suggestions for future investigations, is discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Integrating market share models with network optimizing models for strategic planning in an oil pipeline company

    International Nuclear Information System (INIS)

    Smith, L.D.; Moses, S.W.

    1991-01-01

    Mathematical models of market share are constructed to describe the distribution of petroleum products from pipeline terminals, water terminals and refineries in the midcontinental United States. Network distribution models are developed to analyse the constraints and economics of alternative distribution systems. This paper describes how the two types of models were integrated for strategic planning in an oil pipeline company

  8. Optimal control of a head-of-line processor sharing model with regular and opportunity customers

    NARCIS (Netherlands)

    Wijk, van A.C.C.

    2011-01-01

    Motivated by a workload control setting, we study a model where two types of customers are served by a single server according to the head-of-line processor sharing discipline. Regular customers and opportunity customers are arriving to the system according to two independent Poisson processes, each

  9. Optimize Knowledge Sharing, Team Effectiveness, and Individual Learning within the Flipped Team-Based Classroom

    Science.gov (United States)

    Huang, Chung-Kai; Lin, Chun-Yu; Lin, Zih-Cin; Wang, Cui; Lin, Chia-Jung

    2017-01-01

    Due to the competitive and fast-changing nature of external business environments, university students should acquire knowledge of how to cooperate, share knowledge, and enhance team effectiveness and individual learning in the future workplace. Consequently, the redesign of business courses in higher education merits more discussion. Based on the…

  10. A model for the optimal risk management of (farm) firms

    DEFF Research Database (Denmark)

    Rasmussen, Svend

    Current methods of risk management focus on efficiency and do not provide operational answers to the basic question of how to optimise and balance the two objectives, maximisation of expected income and minimisation of risk. This paper uses the Capital Asset Pricing Model (CAPM) to derive...... an operational criterion for the optimal risk management of firms. The criterion assumes that the objective of the firm manager is to maximise the market value of the firm and is based on the condition that the application of risk management tools has a symmetric effect on the variability of income around...... the mean. The criterion is based on the expected consequences of risk management on relative changes in the variance of return on equity and expected income. The paper demonstrates how the criterion may be used to evaluate and compare the effect of different risk management tools, and it illustrates how...

  11. The Stability of Interbank Market Network: A Perspective on Contagion and Risk Sharing

    Directory of Open Access Journals (Sweden)

    Chi Xie

    2016-01-01

    Full Text Available As an important part of the financial system, interbank market provides banks with liquidity and credit lending and also is the main channel for risk contagion. In this paper, we test the existence of systematic risk contagion within the Chinese interbank market. By building the networks of the Chinese interbank market for each year and using the measure of mutual information, we quantitatively detect the changes of interbank market networks and observe that the correlations between banks become increasingly tighter in recent years. With the bilateral risk exposure among Chinese listed commercial banks, we find that the possibility of systemic risk contagion in Chinese interbank market is fairly small. But of great concern on each individual bank, the matter is different. Our simulation shows that the failures of three special banks (i.e., Agricultural Bank of China and Bank of China and Industrial and Commercial Bank of China most likely lead to systemic risk contagion. Furthermore, we test the antirisk ability of the Chinese interbank market from the perspective of risk sharing and discover that the interbank market is stable when the loss scale is lower than forty percent of banks’ total core capital.

  12. Risk management frameworks: supporting the next generation of Murray-Darling Basin water sharing plans

    Directory of Open Access Journals (Sweden)

    G. M. Podger

    2014-09-01

    Full Text Available Water jurisdictions in Australia are required to prepare and implement water resource plans. In developing these plans the common goal is realising the best possible use of the water resources – maximising outcomes while minimising negative impacts. This requires managing the risks associated with assessing and balancing cultural, industrial, agricultural, social and environmental demands for water within a competitive and resource-limited environment. Recognising this, conformance to international risk management principles (ISO 31000:2009 have been embedded within the Murray-Darling Basin Plan. Yet, to date, there has been little strategic investment by water jurisdictions in bridging the gap between principle and practice. The ISO 31000 principles and the risk management framework that embodies them align well with an adaptive management paradigm within which to conduct water resource planning. They also provide an integrative framework for the development of workflows that link risk analysis with risk evaluation and mitigation (adaptation scenarios, providing a transparent, repeatable and robust platform. This study, through a demonstration use case and a series of workflows, demonstrates to policy makers how these principles can be used to support the development of the next generation of water sharing plans in 2019. The workflows consider the uncertainty associated with climate and flow inputs, and model parameters on irrigation and hydropower production, meeting environmental flow objectives and recreational use of the water resource. The results provide insights to the risks associated with meeting a range of different objectives.

  13. Financial "risk-sharing" or refund programs in assisted reproduction: an Ethics Committee opinion.

    Science.gov (United States)

    2016-10-01

    Financial "risk-sharing" fee structures in assisted reproduction programs charge patients a higher initial fee but provide reduced fees for subsequent cycles and often a partial or complete refund if treatment fails. This opinion of the ASRM Ethics Committee analyzes the ethical issues raised by these fee structures, including patient selection criteria, conflicts of interest, success rate transparency, and patient informed consent. This document replaces the document of the same name, last published in 2013 (Fertil Steril 2013;100:334-6). Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  14. Identifying Unique Versus Shared Pre- and Perinatal Risk Factors for ASD and ADHD Using a Simplex-Multiplex Stratification

    NARCIS (Netherlands)

    Oerlemans, Anoek M.; Burmanje, Marlot J.; Franke, Barbara; Buitelaar, Jan K.; Hartman, Catharina A.; Rommelse, Nanda N. J.

    Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur. Besides shared genetic factors, pre- and perinatal risk factors (PPFs) may determine if ASD, ADHD, or the combination of both disorders becomes manifest. This study aimed to test shared and unique

  15. Application of probabilistic risk based optimization approaches in environmental restoration

    International Nuclear Information System (INIS)

    Goldammer, W.

    1995-01-01

    The paper presents a general approach to site-specific risk assessments and optimization procedures. In order to account for uncertainties in the assessment of the current situation and future developments, optimization parameters are treated as probabilistic distributions. The assessments are performed within the framework of a cost-benefit analysis. Radiation hazards and conventional risks are treated within an integrated approach. Special consideration is given to consequences of low probability events such as, earthquakes or major floods. Risks and financial costs are combined to an overall figure of detriment allowing one to distinguish between benefits of available reclamation options. The probabilistic analysis uses a Monte Carlo simulation technique. The paper demonstrates the applicability of this approach in aiding the reclamation planning using an example from the German reclamation program for uranium mining and milling sites

  16. Risk perception about medication sharing among patients: a focus group qualitative study on borrowing and lending of prescription analgesics

    Directory of Open Access Journals (Sweden)

    Markotic F

    2017-02-01

    Full Text Available Filipa Markotic,1 Davorka Vrdoljak,2 Marijana Puljiz,3 Livia Puljak,4 1Centre for Clinical Pharmacology, University Clinical Hospital Mostar, Mostar, Bosnia and Herzegovina; 2Department of Family Medicine, University of Split School of Medicine, Split, 3Family Medicine Clinic, Health Centre Imotski, Kamenmost, 4Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia Background: One form of self-medication is sharing of medications, defined as borrowing or lending medications in situations where the receiver of these drugs is not the individual to whom the medications were allocated. Objective: To explore experiences and opinions of patients about sharing prescription analgesics, reasons for sharing prescription analgesics, the way in which patients choose to share those medications, their awareness of risk regarding sharing prescription analgesics, and how they estimated the potential risk.Methods: This qualitative study was conducted by focus group discussions with 40 participants led by a moderator trained in focus group methodology using a semi-structured moderator guide. Adults aged ≥18 years who had received a prescription for an analgesic at least once in a lifetime were included. Six separate focus groups were conducted to discuss participants’ perception of risks associated with sharing of prescription analgesics among patients. Additionally, participants filled out two questionnaires on demographic data, their own behavior regarding sharing analgesics, and their attitudes about risks associated with sharing prescription analgesics.Results: In a questionnaire, 55% of the participants indicated that they personally shared prescription analgesics, while subsequently in the focus group discussions, 76% confessed to such behavior. Participants recognized certain risks related to sharing of prescription analgesics, mentioned a number of reasons for engaging in such behavior, and indicated certain positive

  17. Infectious Cognition: Risk Perception Affects Socially Shared Retrieval-Induced Forgetting of Medical Information.

    Science.gov (United States)

    Coman, Alin; Berry, Jessica N

    2015-12-01

    When speakers selectively retrieve previously learned information, listeners often concurrently, and covertly, retrieve their memories of that information. This concurrent retrieval typically enhances memory for mentioned information (the rehearsal effect) and impairs memory for unmentioned but related information (socially shared retrieval-induced forgetting, SSRIF), relative to memory for unmentioned and unrelated information. Building on research showing that anxiety leads to increased attention to threat-relevant information, we explored whether concurrent retrieval is facilitated in high-anxiety real-world contexts. Participants first learned category-exemplar facts about meningococcal disease. Following a manipulation of perceived risk of infection (low vs. high risk), they listened to a mock radio show in which some of the facts were selectively practiced. Final recall tests showed that the rehearsal effect was equivalent between the two risk conditions, but SSRIF was significantly larger in the high-risk than in the low-risk condition. Thus, the tendency to exaggerate consequences of news events was found to have deleterious consequences. © The Author(s) 2015.

  18. Anorexia nervosa and major depression: shared genetic and environmental risk factors.

    Science.gov (United States)

    Wade, T D; Bulik, C M; Neale, M; Kendler, K S

    2000-03-01

    The authors sought to derive heritability estimates for anorexia nervosa and to explore the etiology of the comorbid relationship between anorexia nervosa and major depression. They applied bivariate structural equation modeling to a broad definition of anorexia nervosa and lifetime major depression as assessed in a population-based sample of 2,163 female twins. Anorexia nervosa was estimated to have a heritability of 58% (95% confidence interval=33%-84%). The authors were unable to completely rule out a contribution of shared environment. The comorbidity between anorexia nervosa and major depression is likely due to genetic factors that influence the risk for both disorders. Although the study was limited by the small number of affected twins, the results suggest that genetic factors significantly influence the risk for anorexia nervosa and substantially contribute to the observed comorbidity between anorexia nervosa and major depression.

  19. Shared risk: who engages in substance use with American homeless youth?

    Science.gov (United States)

    Green, Harold D; de la Haye, Kayla; Tucker, Joan S; Golinelli, Daniela

    2013-09-01

    To identify characteristics of social network members with whom homeless youth engage in drinking and drug use. A multi-stage probability sample of homeless youth completed a social network survey. Forty-one shelters, drop-in centers and known street hangouts in Los Angeles County. A total of 419 homeless youth, aged 13-24 years (mean age = 20.09, standard deviation = 2.80). Respondents described 20 individuals in their networks, including their substance use and demographics, and the characteristics of the relationships they shared, including with whom they drank and used drugs. Dyadic, multi-level regressions identified predictors of shared substance use. Shared drinking was more likely to occur with recent sex partners [odds ratio (OR) = 2.64, confidence interval (CI): 1.67, 4.18], drug users (OR = 4.57, CI: 3.21, 6.49), sexual risk takers (OR = 1.71, CI: 1.25, 2.33), opinion leaders (OR = 1.69, CI: 1.42, 2.00), support providers (OR = 1.41, CI: 1.03, 1.93) and popular people (those with high degree scores in the network) (OR = 1.07, CI: 1.01, 1.14). Shared drug use was more likely to occur with recent sex partners (OR = 2.44, CI: 1.57, 3.80), drinkers (OR = 4.53, CI: 3.05, 6.74), sexual risk takers (OR = 1.51, CI: 1.06, 2.17), opinion leaders (OR = 1.24, CI: 1.03, 1.50), support providers (OR = 1.83, CI: 1.29, 2.60) and popular people (OR = 1.16, CI: 1.08, 1.24). Homeless youth in the United States are more likely to drink or use drugs with those who engage in multiple risk behaviors and who occupy influential social roles (popular, opinion leaders, support providers, sex partners). Understanding these social networks may be helpful in designing interventions to combat substance misuse. © 2013 Society for the Study of Addiction.

  20. From Risks to Shared Value? Corporate Strategies in Building a Global Water Accounting and Disclosure Regime

    Directory of Open Access Journals (Sweden)

    Marco A. Daniel

    2012-10-01

    Full Text Available The current debate on water accounting and accountability among transnational actors such as corporations and NGOs is likely to contribute to the emergence of a global water governance regime. Corporations within the food and beverage sector (F-B are especially vulnerable to water risks; therefore, in this article we analyse motivations and strategies of the major F-B corporations participating in the debate and developing different water accounting, disclosure and risk-assessment tools. Neo-institutionalism and neo-Gramscian regime theory provide the basis for our framework to analyse the discursive, material and organisational corporate water strategies. Findings based on an analysis of the chosen F-B corporations’ sustainability reports and interviews with key informants suggest that the corporations share similar goals and values with regard to the emerging regime. They seek a standardisation that is practical and supportive in improving their water efficiency and communication with stakeholders. This indicates that some harmonisation has taken place over time and new actors have been pursuing the path of the pioneering companies, but the lead corporations are also differentiating their strategies, thus engaging in hegemonic positioning. However, so far the plethora of NGO-driven accountability initiatives and tools has fragmented the field more than 'war of position' amongst the corporations. Furthermore, several companies claim to have proceeded from internal water-risk management to reducing risks throughout their value chains and watersheds. As a result they are 'creating shared value' with stakeholders, and potentially manifesting an emergent paradigm that goes beyond a private regime framework. Nevertheless, in the absence of verification schemes, questions of sustainability and legitimacy of such actions on the ground prevail and remain a topic for further research.

  1. Exploring shared risks through public-private partnerships in public health programs: a mixed method.

    Science.gov (United States)

    Alonazi, Wadi B

    2017-06-12

    The natural assimilation of the process through which health partners sustain long-term relationships is a key issue in maintaining social well-being, reducing health risk factors, and sustaining public health programs. One global initiative in building effective healthcare systems is public-private partnerships (PPPs). This study elucidates the proposed key performance indicators initiated by the Ministry of Health of Saudi Arabia based on the projections of the government, known as Vision 2030, from the perspective of health risk factors. Through an inductive content analysis, this study assessed primary and secondary data in relation to the Saudi National Transformation Program (NTP). To identify the institutions that played a role in formulating the new Saudi Healthcare System, health policies, regulations, and reports published between 1996 and 2016 were categorized. After ranking the risk factors, the investigator selected 13 healthcare professionals in four focus group interviews to insightfully explore the challenges that the NTP faces from a health risk perspective. Thus, the study employed qualitative data gathered through focus group interviews with key figures as well as data extracted from written sources to identify distinct but interrelated partnerships practiced within risk management. A methodological overview of NTP priority and implementation offered practical guidance in the healthcare context. The five critical factors in maintaining successful and sustainable PPPs were (1) trustworthiness, (2) technological capability, (3) patient-centeredness, (4) competence, and (5) flexibility. Concession on primary and secondary healthcare services might be a good option based on the literature review and considering its popularity in other countries. A high outcome-based risk of PPPs was found as the most commonly shared perspective in risk management. Although the impact of the NTP rise has yet to be explored, its potential for challenging health

  2. Worst-Case Portfolio Optimization under Stochastic Interest Rate Risk

    Directory of Open Access Journals (Sweden)

    Tina Engler

    2014-12-01

    Full Text Available We investigate a portfolio optimization problem under the threat of a market crash, where the interest rate of the bond is modeled as a Vasicek process, which is correlated with the stock price process. We adopt a non-probabilistic worst-case approach for the height and time of the market crash. On a given time horizon [0; T], we then maximize the investor’s expected utility of terminal wealth in the worst-case crash scenario. Our main result is an explicit characterization of the worst-case optimal portfolio strategy for the class of HARA (hyperbolic absolute risk aversion utility functions.

  3. Optimized Architectural Approaches in Hardware and Software Enabling Very High Performance Shared Storage Systems

    CERN Multimedia

    CERN. Geneva

    2004-01-01

    There are issues encountered in high performance storage systems that normally lead to compromises in architecture. Compute clusters tend to have compute phases followed by an I/O phase that must move data from the entire cluster in one operation. That data may then be shared by a large number of clients creating unpredictable read and write patterns. In some cases the aggregate performance of a server cluster must exceed 100 GB/s to minimize the time required for the I/O cycle thus maximizing compute availability. Accessing the same content from multiple points in a shared file system leads to the classical problems of data "hot spots" on the disk drive side and access collisions on the data connectivity side. The traditional method for increasing apparent bandwidth usually includes data replication which is costly in both storage and management. Scaling a model that includes replicated data presents additional management challenges as capacity and bandwidth expand asymmetrically while the system is scaled. ...

  4. Optimal decisions of sharing rate and ticket price of different transportation modes in inter-city transportation corridor

    Directory of Open Access Journals (Sweden)

    Zhaoping Tang

    2015-11-01

    Full Text Available Purpose: The paper concerns competition of different transportation modes coexist in inter-city transportation corridor. The purpose of this paper is to express the competitive relationship by building mathematical model and obtain the best sharing rate and the optimal ticket price of different transportation modes. Design/methodology/approach: Firstly, analyzing influencing factors of passenger choice about transportation modes, we designed an utility function of transportation modes. Secondly, referring to the game theory and logit modle, a non-cooperative game model between railway and highway was built. Finally, the model was applied to Nanchang-Jiujiang transportation corridor in China for an empirical analysis. Findings: The results indicate that the proposed non-cooperative game model is rational and reliable, and it supplies a scientific method to determine the optimal ticket price and passenger sharing rate of different transportation modes, and can be applied to the competition study on different transportation modes in inter-city transportation corridor. Originality/value: The main contribution of this paper is to built the non-cooperative game model, which can consider the needs of different travelers, and achieve reasonable passenger divergence of different transportation modes and coordinated development of whole transport market.

  5. Building shared understandings in introductory physics tutorials through risk, repair, conflict & comedy

    Science.gov (United States)

    Conlin, Luke D.

    Collaborative inquiry learning environments, such as The Tutorials in Physics Sensemaking, are designed to provide students with opportunities to partake in the authentic disciplinary practices of argumentation and sensemaking. Through these practices, groups of students in tutorial can build shared conceptual understandings of the mechanisms behind physical phenomena. In order to do so, they must also build a shared epistemological understanding of what they are doing together, such that their activity includes collaboratively making sense of mechanisms. Previous work (Conlin, Gupta, Scherr, & Hammer, 2007; Scherr & Hammer, 2009) has demonstrated that tutorial students do not settle upon only one way of understanding their activity together, but instead build multiple shared ways of understanding, or framing (Scherr & Hammer, 2009; Tannen, 1993a), their activity. I build upon this work by substantiating a preliminary finding that one of these shared ways of framing corresponds with increased evidence of the students' collaboratively making sense of physical mechanisms. What previous research has not yet addressed is how the students come to understand their activity as including collaborative sensemaking discussions in the first place, and how that understanding develops over the course of the semester. In this dissertation, I address both of these questions through an in-depth video analysis of three groups' discussions throughout the semester. To build shared understandings through scientific argumentation and collaborative sensemaking, the students need to continually make repairs of each other's understanding, but this comes with the risk of affective damage that can shut down further sensemaking discussions. By analyzing the discourse of the three groups' discussions throughout the semester, I show how each group is able to manage this essential tension as they each build and maintain a safe space to sensemake together. I find that the three groups differ in

  6. Optimal antiviral switching to minimize resistance risk in HIV therapy.

    Directory of Open Access Journals (Sweden)

    Rutao Luo

    Full Text Available The development of resistant strains of HIV is the most significant barrier to effective long-term treatment of HIV infection. The most common causes of resistance development are patient noncompliance and pre-existence of resistant strains. In this paper, methods of antiviral regimen switching are developed that minimize the risk of pre-existing resistant virus emerging during therapy switches necessitated by virological failure. Two distinct cases are considered; a single previous virological failure and multiple virological failures. These methods use optimal control approaches on experimentally verified mathematical models of HIV strain competition and statistical models of resistance risk. It is shown that, theoretically, order-of-magnitude reduction in risk can be achieved, and multiple previous virological failures enable greater success of these methods in reducing the risk of subsequent treatment failures.

  7. Optimizing primary care research participation: a comparison of three recruitment methods in data-sharing studies.

    Science.gov (United States)

    Lord, Paul A; Willis, Thomas A; Carder, Paul; West, Robert M; Foy, Robbie

    2016-04-01

    Recruitment of representative samples in primary care research is essential to ensure high-quality, generalizable results. This is particularly important for research using routinely recorded patient data to examine the delivery of care. Yet little is known about how different recruitment strategies influence the characteristics of the practices included in research. We describe three approaches for recruiting practices to data-sharing studies, examining differences in recruitment levels and practice representativeness. We examined three studies that included varying populations of practices from West Yorkshire, UK. All used anonymized patient data to explore aspects of clinical practice. Recruitment strategies were 'opt-in', 'mixed opt-in and opt-out' and 'opt-out'. We compared aggregated practice data between recruited and not-recruited practices for practice list size, deprivation, chronic disease management, patient experience and rates of unplanned hospital admission. The opt-out strategy had the highest recruitment (80%), followed by mixed (70%) and opt-in (58%). Practices opting-in were larger (median 7153 versus 4722 patients, P = 0.03) than practices that declined to opt-in. Practices recruited by mixed approach were larger (median 7091 versus 5857 patients, P = 0.04) and had differences in the clinical quality measure (58.4% versus 53.9% of diabetic patients with HbA1c ≤ 59 mmol/mol, P Researchers should, with appropriate ethical safeguards, consider opt-out recruitment of practices for studies involving anonymized patient data sharing. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Optimal Premium Pricing for a Heterogeneous Portfolio of Insurance Risks

    Directory of Open Access Journals (Sweden)

    Athanasios A. Pantelous

    2009-01-01

    Full Text Available The paper revisits the classical problem of premium rating within a heterogeneous portfolio of insurance risks using a continuous stochastic control framework. The portfolio is divided into several classes where each class interacts with the others. The risks are modelled dynamically by the means of a Brownian motion. This dynamic approach is also transferred to the design of the premium process. The premium is not constant but equals the drift of the Brownian motion plus a controlled percentage of the respective volatility. The optimal controller for the premium is obtained using advanced optimization techniques, and it is finally shown that the respective pricing strategy follows a more balanced development compared with the traditional premium approaches.

  9. Risk-Informed Decisions Optimization in Inspection and Maintenance

    International Nuclear Information System (INIS)

    Robertas Alzbutas

    2002-01-01

    The Risk-Informed Approach (RIA) used to support decisions related to inspection and maintenance program is considered. The use of risk-informed methods can help focus the adequate in-service inspections and control on the more important locations of complex dynamic systems. The focus is set on the highest risk measured as conditional core damage frequency, which is produced by the frequencies of degradation and final failure at different locations combined with the conditional failure consequence probability. The probabilities of different degradation states per year and consequences are estimated quantitatively. The investigation of inspection and maintenance process is presented as the combination of deterministic and probabilistic analysis based on general risk-informed model, which includes the inspection and maintenance program features. Such RIA allows an optimization of inspection program while maintaining probabilistic and fundamental deterministic safety requirements. The failure statistics analysis is used as well as the evaluation of reliability of inspections. The assumptions regarding the effectiveness of the inspection methods are based on a classification of the accessibility of the welds during the inspection and on the different techniques used for inspection. The probability of defect detection is assumed to depend on the parameters either through logarithmic or logit transformation. As example the modeling of the pipe systems inspection process is analyzed. The means to reduce a number of inspection sites and the cumulative radiation exposure to the NPP inspection personnel with a reduction of overall risk is presented together with used and developed software. The developed software can perform and administrate all the risk evaluations and ensure the possibilities to compare different options and perform sensitivity analysis. The approaches to define an acceptable level of risk are discussed. These approaches with appropriate software in

  10. Optimal CO2 mitigation under damage risk valuation

    Science.gov (United States)

    Crost, Benjamin; Traeger, Christian P.

    2014-07-01

    The current generation has to set mitigation policy under uncertainty about the economic consequences of climate change. This uncertainty governs both the level of damages for a given level of warming, and the steepness of the increase in damage per warming degree. Our model of climate and the economy is a stochastic version of a model employed in assessing the US Social Cost of Carbon (DICE). We compute the optimal carbon taxes and CO2 abatement levels that maximize welfare from economic consumption over time under different risk states. In accordance with recent developments in finance, we separate preferences about time and risk to improve the model's calibration of welfare to observed market interest. We show that introducing the modern asset pricing framework doubles optimal abatement and carbon taxation. Uncertainty over the level of damages at a given temperature increase can result in a slight increase of optimal emissions as compared to using expected damages. In contrast, uncertainty governing the steepness of the damage increase in temperature results in a substantially higher level of optimal mitigation.

  11. Probabilistic framework for product design optimization and risk management

    Science.gov (United States)

    Keski-Rahkonen, J. K.

    2018-05-01

    Probabilistic methods have gradually gained ground within engineering practices but currently it is still the industry standard to use deterministic safety margin approaches to dimensioning components and qualitative methods to manage product risks. These methods are suitable for baseline design work but quantitative risk management and product reliability optimization require more advanced predictive approaches. Ample research has been published on how to predict failure probabilities for mechanical components and furthermore to optimize reliability through life cycle cost analysis. This paper reviews the literature for existing methods and tries to harness their best features and simplify the process to be applicable in practical engineering work. Recommended process applies Monte Carlo method on top of load-resistance models to estimate failure probabilities. Furthermore, it adds on existing literature by introducing a practical framework to use probabilistic models in quantitative risk management and product life cycle costs optimization. The main focus is on mechanical failure modes due to the well-developed methods used to predict these types of failures. However, the same framework can be applied on any type of failure mode as long as predictive models can be developed.

  12. Multi-objective optimization for the maximization of the operating share of cogeneration system in District Heating Network

    International Nuclear Information System (INIS)

    Franco, Alessandro; Versace, Michele

    2017-01-01

    Highlights: • Combined Heat and Power plants and civil/residential energy uses. • CHP plant supported by auxiliary boilers and thermal energy storage. • Definition of optimal operational strategies for cogeneration plants for District Heating. • Optimal-sized Thermal Energy Storage and a hybrid operational strategy. • Maximization of cogeneration share and reduction of time of operation of auxiliary boilers. - Abstract: The aim of the paper is to define optimal operational strategies for Combined Heat and Power plants connected to civil/residential District Heating Networks. The role of a reduced number of design variables, including a Thermal Energy Storage system and a hybrid operational strategy dependent on the storage level, is considered. The basic principle is to reach maximum efficiency of the system operation through the utilization of an optimal-sized Thermal Energy Storage. Objective functions of both energetic and combined energetic and economic can be considered. In particular, First and Second Law Efficiency, thermal losses of the storage, number of starts and stops of the combined heat and power unit are considered. Constraints are imposed to nullify the waste of heat and to operate the unit at its maximum efficiency for the highest possible number of consecutive operating hours, until the thermal tank cannot store more energy. The methodology is applied to a detailed case study: a medium size district heating system, in an urban context in the northern Italy, powered by a combined heat and power plant supported by conventional auxiliary boilers. The issues involving this type of thermal loads are also widely investigated in the paper. An increase of Second Law Efficiency of the system of 26% (from 0.35 to 0.44) can be evidenced, while the First Law Efficiency shifts from about 0.74 to 0.84. The optimization strategy permits of combining the economic benefit of cogeneration with the idea of reducing the energy waste and exergy losses.

  13. [Evidence-based Risk and Benefit Communication for Shared Decision Making].

    Science.gov (United States)

    Nakayama, Takeo

    2018-01-01

     Evidence-based medicine (EBM) can be defined as "the integration of the best research evidence with clinical expertise and a patient's unique values and circumstances". However, even with the best research evidence, many uncertainties can make clinical decisions difficult. As the social requirement of respecting patient values and preferences has been increasingly recognized, shared decision making (SDM) and consensus development between patients and clinicians have attracted attention. SDM is a process by which patients and clinicians make decisions and arrive at a consensus through interactive conversations and communications. During the process of SDM, patients and clinicians share information with each other on the goals they hope to achieve and responsibilities in meeting those goals. From the clinician's standpoint, information regarding the benefits and risks of potential treatment options based on current evidence and professional experience is provided to patients. From the patient's standpoint, information on personal values, preferences, and social roles is provided to clinicians. SDM is a sort of "wisdom" in the context of making autonomous decisions in uncertain, difficult situations through interactions and cooperation between patients and clinicians. Joint development of EBM and SDM will help facilitate patient-clinician relationships and improve the quality of healthcare.

  14. Cost sharing and hereditary cancer risk: predictors of willingness-to-pay for genetic testing.

    Science.gov (United States)

    Matro, Jennifer M; Ruth, Karen J; Wong, Yu-Ning; McCully, Katen C; Rybak, Christina M; Meropol, Neal J; Hall, Michael J

    2014-12-01

    Increasing use of predictive genetic testing to gauge hereditary cancer risk has been paralleled by rising cost-sharing practices. Little is known about how demographic and psychosocial factors may influence individuals' willingness-to-pay for genetic testing. The Gastrointestinal Tumor Risk Assessment Program Registry includes individuals presenting for genetic risk assessment based on personal/family cancer history. Participants complete a baseline survey assessing cancer history and psychosocial items. Willingness-to-pay items include intention for: genetic testing only if paid by insurance; testing with self-pay; and amount willing-to-pay ($25-$2,000). Multivariable models examined predictors of willingness-to-pay out-of-pocket (versus only if paid by insurance) and willingness-to-pay a smaller versus larger sum (≤$200 vs. ≥$500). All statistical tests are two-sided (α = 0.05). Of 385 evaluable participants, a minority (42%) had a personal cancer history, while 56% had ≥1 first-degree relative with colorectal cancer. Overall, 21.3% were willing to have testing only if paid by insurance, and 78.7% were willing-to-pay. Predictors of willingness-to-pay were: 1) concern for positive result; 2) confidence to control cancer risk; 3) fewer perceived barriers to colorectal cancer screening; 4) benefit of testing to guide screening (all p testing (all p testing, and anticipate benefits to reducing cancer risk. Identifying factors associated with willingness-to-pay for genetic services is increasingly important as testing is integrated into routine cancer care.

  15. Shared Genetic Aetiology between Cognitive Ability and Cardiovascular Disease Risk Factors: Generation Scotland's Scottish Family Health Study

    Science.gov (United States)

    Luciano, Michelle; Batty, G. David; McGilchrist, Mark; Linksted, Pamela; Fitzpatrick, Bridie; Jackson, Cathy; Pattie, Alison; Dominiczak, Anna F.; Morris, Andrew D.; Smith, Blair H.; Porteous, David; Deary, Ian J.

    2010-01-01

    People with higher general cognitive ability in early life have more favourable levels of cardiovascular disease (CVD) risk factors in adulthood and CVD itself. The mechanism of these associations is not known. Here we examine whether general cognitive ability and CVD risk factors share genetic and/or environmental aetiology. In this large,…

  16. Cost shared wildfire risk mitigation in Log Hill Mesa, Colorado: Survey evidence on participation and willingness to pay

    Science.gov (United States)

    James R. Meldrum; Patricia A. Champ; Travis Warziniack; Hannah Brenkert-Smith; Christopher M. Barth; Lilia C. Falk

    2014-01-01

    Wildland-urban interface (WUI) homeowners who do not mitigate the wildfire risk on their properties impose a negative externality on society. To reduce the social costs of wildfire and incentivise homeowners to take action, cost sharing programs seek to reduce the barriers that impede wildfire risk mitigation. Using survey data from a WUI community in western Colorado...

  17. A supply chain contract with flexibility as a risk-sharing mechanism for demand forecasting

    Science.gov (United States)

    Kim, Whan-Seon

    2013-06-01

    Demand forecasting is one of the main causes of the bullwhip effect in a supply chain. As a countermeasure for demand uncertainty as well as a risk-sharing mechanism for demand forecasting in a supply chain, this article studies a bilateral contract with order quantity flexibility. Under the contract, the buyer places orders in advance for the predetermined horizons and makes minimum purchase commitments. The supplier, in return, provides the buyer with the flexibility to adjust the order quantities later, according to the most updated demand information. To conduct comparative simulations, four-echelon supply chain models, that employ the contracts and different forecasting techniques under dynamic market demands, are developed. The simulation outcomes show that demand fluctuation can be effectively absorbed by the contract scheme, which enables better inventory management and customer service. Furthermore, it has been verified that the contract scheme under study plays a role as an effective coordination mechanism in a decentralised supply chain.

  18. Load sharing with a local thermal network fed by a microcogenerator: Thermo-economic optimization by means of dynamic simulations

    International Nuclear Information System (INIS)

    Angrisani, Giovanni; Canelli, Michele; Rosato, Antonio; Roselli, Carlo; Sasso, Maurizio; Sibilio, Sergio

    2014-01-01

    The cogeneration is the combined production of electric and/or mechanical and thermal energy starting by a single energy source; in particular in this paper the analysis will be focused on a cogeneration system with electric power lower than 15 kW (micro-cogeneration). The paper analyzes a system consisting of a natural gas-fired micro-cogeneration unit (MCHP), a heat storage and a peak boiler. The system provides thermal and electric energy to two end-users, the former is a tertiary building (office), where the generation system is located, and the latter is a residential building connected to the former through a district heating micro-grid. In order to analyze the influence of climatic conditions, two different geographical locations in Italy (Benevento and Milano) are considered, that are also characterized by different natural gas and electricity tariffs. Particular attention is paid to the choice of the users, in order to obtain more stable and continuous electric and thermal loads (load sharing approach) and to increase the operating hours per year of the MCHP unit. The operation of the MCHP is governed by a control system, aimed to optimize a thermo-economic objective function. The models representing the components, the thermo-economic objective function and the buildings have been implemented in a widely used commercial software for building simulations. The models are calibrated and validated through data obtained from experimental tests carried out in the laboratory of the University of Sannio (Benevento). The results of the simulations highlight the potential benefits of the thermal load sharing approach. In particular, this study shows that an MCHP unit connected by means of a thermal micro-grid to different users in “load sharing mode” can obtain a high number of operating hours as well as significant energy (Primary Energy Saving) and environmental (avoided CO 2 equivalent emissions) benefits with respect to an appropriate reference system

  19. An Optimal Scheduling Dispatch of a Microgrid under Risk Assessment

    Directory of Open Access Journals (Sweden)

    Whei-Min Lin

    2018-06-01

    Full Text Available This paper presents the scheduling dispatch of a microgrid (MG, while considering renewable energy, battery storage systems, and time-of-use price. For the risk evaluation of an MG, the Value-at-Risk (VAR is calculated by using the Historical Simulation Method (HSM. By considering the various confidence levels of the VAR, a scheduling dispatch model of the MG is formulated to achieve a reasonable trade-off between the risk and cost. An Improved Bee Swarm Optimization (IBSO is proposed to solve the scheduling dispatch model of the MG. In the IBSO procedure, the Sin-wave Weight Factor (SWF and Forward-Backward Control Factor (FBCF are embedded in the bee swarm of the BSO to improve the movement behaviors of each bee, specifically, its search efficiency and accuracy. The effectiveness of the IBSO is demonstrated via a real MG case and the results are compared with other methods. In either a grid-connected scenario or a stand-alone scenario, an optimal scheduling dispatch of MGs is carried out, herein, at various confidence levels of risk. The simulation results provide more information for handling uncertain environments when analyzing the VAR of MGs.

  20. 2-Phase NSGA II: An Optimized Reward and Risk Measurements Algorithm in Portfolio Optimization

    Directory of Open Access Journals (Sweden)

    Seyedeh Elham Eftekharian

    2017-11-01

    Full Text Available Portfolio optimization is a serious challenge for financial engineering and has pulled down special attention among investors. It has two objectives: to maximize the reward that is calculated by expected return and to minimize the risk. Variance has been considered as a risk measure. There are many constraints in the world that ultimately lead to a non–convex search space such as cardinality constraint. In conclusion, parametric quadratic programming could not be applied and it seems essential to apply multi-objective evolutionary algorithm (MOEA. In this paper, a new efficient multi-objective portfolio optimization algorithm called 2-phase NSGA II algorithm is developed and the results of this algorithm are compared with the NSGA II algorithm. It was found that 2-phase NSGA II significantly outperformed NSGA II algorithm.

  1. Distributionally Robust Return-Risk Optimization Models and Their Applications

    Directory of Open Access Journals (Sweden)

    Li Yang

    2014-01-01

    Full Text Available Based on the risk control of conditional value-at-risk, distributionally robust return-risk optimization models with box constraints of random vector are proposed. They describe uncertainty in both the distribution form and moments (mean and covariance matrix of random vector. It is difficult to solve them directly. Using the conic duality theory and the minimax theorem, the models are reformulated as semidefinite programming problems, which can be solved by interior point algorithms in polynomial time. An important theoretical basis is therefore provided for applications of the models. Moreover, an application of the models to a practical example of portfolio selection is considered, and the example is evaluated using a historical data set of four stocks. Numerical results show that proposed methods are robust and the investment strategy is safe.

  2. Optimization of constellation jettisoning regards to short term collision risks

    Science.gov (United States)

    Handschuh, D.-DA.-A.; Bourgeois, E.

    2018-04-01

    The space debris problematic is directly linked to the in-orbit collision risk between artificial satellites. With the increase of the space constellation projects, a multiplication of multi-payload launches should occur. In the specific cases where many satellites are injected into orbit with the same launcher upper stage, all these objects will be placed on similar orbits, very close one from each other, at a specific moment where their control capabilities will be very limited. Under this hypothesis, it is up to the launcher operator to ensure that the simultaneous in-orbit injection is safe enough to guarantee the non-collision risk between all the objects under a ballistic hypothesis eventually considering appropriate uncertainties. The purpose of the present study is to find optimized safe separation conditions to limit the in-orbit collision risk following the injection of many objects on very close orbits in a short-delay mission.

  3. Exploring shared risks through public-private partnerships in public health programs: a mixed method

    Directory of Open Access Journals (Sweden)

    Wadi B. Alonazi

    2017-06-01

    Full Text Available Abstract Background The natural assimilation of the process through which health partners sustain long-term relationships is a key issue in maintaining social well-being, reducing health risk factors, and sustaining public health programs. One global initiative in building effective healthcare systems is public-private partnerships (PPPs. This study elucidates the proposed key performance indicators initiated by the Ministry of Health of Saudi Arabia based on the projections of the government, known as Vision 2030, from the perspective of health risk factors. Methods Through an inductive content analysis, this study assessed primary and secondary data in relation to the Saudi National Transformation Program (NTP. To identify the institutions that played a role in formulating the new Saudi Healthcare System, health policies, regulations, and reports published between 1996 and 2016 were categorized. After ranking the risk factors, the investigator selected 13 healthcare professionals in four focus group interviews to insightfully explore the challenges that the NTP faces from a health risk perspective. Thus, the study employed qualitative data gathered through focus group interviews with key figures as well as data extracted from written sources to identify distinct but interrelated partnerships practiced within risk management. Results A methodological overview of NTP priority and implementation offered practical guidance in the healthcare context. The five critical factors in maintaining successful and sustainable PPPs were (1 trustworthiness, (2 technological capability, (3 patient-centeredness, (4 competence, and (5 flexibility. Concession on primary and secondary healthcare services might be a good option based on the literature review and considering its popularity in other countries. A high outcome-based risk of PPPs was found as the most commonly shared perspective in risk management. Conclusions Although the impact of the NTP rise has yet

  4. Portfolio Implementation Risk Management Using Evolutionary Multiobjective Optimization

    Directory of Open Access Journals (Sweden)

    David Quintana

    2017-10-01

    Full Text Available Portfolio management based on mean-variance portfolio optimization is subject to different sources of uncertainty. In addition to those related to the quality of parameter estimates used in the optimization process, investors face a portfolio implementation risk. The potential temporary discrepancy between target and present portfolios, caused by trading strategies, may expose investors to undesired risks. This study proposes an evolutionary multiobjective optimization algorithm aiming at regions with solutions more tolerant to these deviations and, therefore, more reliable. The proposed approach incorporates a user’s preference and seeks a fine-grained approximation of the most relevant efficient region. The computational experiments performed in this study are based on a cardinality-constrained problem with investment limits for eight broad-category indexes and 15 years of data. The obtained results show the ability of the proposed approach to address the robustness issue and to support decision making by providing a preferred part of the efficient set. The results reveal that the obtained solutions also exhibit a higher tolerance to prediction errors in asset returns and variance–covariance matrix.

  5. Financial risk-sharing in updating the National List of Health Services in Israel: stakeholders' perceived interests.

    Science.gov (United States)

    Hammerman, Ariel; Feder-Bubis, Paula; Greenberg, Dan

    2012-01-01

    Risk-sharing is being considered by many health care systems to address the financial risk associated with the adoption of new technologies. We explored major stakeholders' views toward the potential implementation of a financial risk-sharing mechanism regarding budget-impact estimates for adding new technologies to the Israeli National List of Health Services. According to our proposed scheme, health plans will be partially compensated by technology sponsors if the actual use of a technology is substantially higher than what was projected and health plans will refund the government for budgets that were not fully utilized. By using a semi-structured protocol, we interviewed major stakeholders involved in the process of updating the National List of Health Services (N = 31). We inquired into participants' views toward our proposed risk-sharing mechanism, whether the proposed scheme would achieve its purpose, its feasibility of implementation, and their opinion on the other stakeholders' incentives. Participants' considerations were classified into four main areas: financial, administrative/managerial, impact on patients' health, and influence on public image. Most participants agreed that the conceptual risk-sharing scheme will improve the accuracy of early budget estimates and were in favor of the proposed scheme, although Ministry of Finance officials tended to object to it. The successful implementation of risk-sharing schemes depends mainly on their perception as a win-win situation by all stakeholders. The perception exposed by our participants that risk-sharing can be a tool for improving the accuracy of early budget-impact estimates and the challenges pointed by them are relevant to other health care systems also and should be considered when implementing similar schemes. Copyright © 2012 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  6. Stroke Health and Risk Education (SHARE): design, methods, and theoretical basis.

    Science.gov (United States)

    Brown, Devin L; Conley, Kathleen M; Resnicow, Kenneth; Murphy, Jillian; Sánchez, Brisa N; Cowdery, Joan E; Sais, Emma; Lisabeth, Lynda D; Skolarus, Lesli E; Zahuranec, Darin B; Williams, Geoffrey C; Morgenstern, Lewis B

    2012-07-01

    Stroke is a disease with tremendous individual, family, and societal impact across all race/ethnic groups. Mexican Americans, the largest subgroup of Hispanic Americans, are at even higher risk of stroke than European Americans. To test the effectiveness of a culturally sensitive, church-based, multi-component, motivational enhancement intervention for Mexican Americans and European Americans in reducing stroke risk factors. Participants enroll in family or friendship pairs, from the same Catholic church in the Corpus Christi Texas area, and are encouraged to change diet and physical activity behaviors and provide support for behavior change to their partners. Churches are randomized to either the intervention or control group. Goal enrollment for each of the 10 participating churches is 40 participant pairs. The intervention consists of self-help materials (including a motivational short film, cookbook/healthy eating guide, physical activity guide with pedometer, and photonovella), five motivational interviewing calls, two tailored newsletters, parish health promotion activities and environmental changes, and a peer support workshop where participants learn to provide autonomy supportive counseling to their partner. SHARE's three primary outcomes are self-reported sodium intake, fruit and vegetable intake, and level of physical activity. Participants complete questionnaires and have measurements at baseline, six months, and twelve months. Persistence testing is performed at 18 months in the intervention group. The trial is registered with clinicaltrials.gov (NCT01378780). Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Optimal dividends in the Brownian motion risk model with interest

    Science.gov (United States)

    Fang, Ying; Wu, Rong

    2009-07-01

    In this paper, we consider a Brownian motion risk model, and in addition, the surplus earns investment income at a constant force of interest. The objective is to find a dividend policy so as to maximize the expected discounted value of dividend payments. It is well known that optimality is achieved by using a barrier strategy for unrestricted dividend rate. However, ultimate ruin of the company is certain if a barrier strategy is applied. In many circumstances this is not desirable. This consideration leads us to impose a restriction on the dividend stream. We assume that dividends are paid to the shareholders according to admissible strategies whose dividend rate is bounded by a constant. Under this additional constraint, we show that the optimal dividend strategy is formed by a threshold strategy.

  8. Shared Risk Factors for the Perpetration of Physical Dating Violence, Bullying, and Sexual Harassment Among Adolescents Exposed to Domestic Violence

    Science.gov (United States)

    McNaughton Reyes, H. Luz; Chen, May S.; Ennett, Susan T.; Basile, Kathleen C.; DeGue, Sarah; Vivolo-Kantor, Alana M.; Moracco, Kathryn E.; Bowling, J. Michael

    2016-01-01

    The high risk of perpetrating physical dating violence, bullying, and sexual harassment by adolescents exposed to domestic violence points to the need for programs to prevent these types of aggression among this group. This study of adolescents exposed to domestic violence examined whether these forms of aggression share risk factors that could be targeted for change in single programs designed to prevent all three types of aggression. Analyses were conducted on 399 mother victims of domestic violence and their adolescents, recruited through community advertising. The adolescents ranged in age from 12 to 16 years; 64 % were female. Generalized estimating equations was used to control for the covariation among the aggression types when testing for shared risk factors. Approximately 70 % of the adolescents reported perpetrating at least one of the three forms of aggression. In models examining one risk factor at a time, but controlling for demographics, adolescent acceptance of sexual violence, mother–adolescent discord, family conflict, low maternal monitoring, low mother–adolescent closeness, low family cohesion, depressed affect, feelings of anger, and anger reactivity were shared across all three aggression types. In multivariable models, which included all of the risk factors examined and the demographic variables, low maternal monitoring, depressed affect and anger reactivity remained significant shared risk factors. Our findings suggest that programs targeting these risk factors for change have the potential to prevent all three forms of aggression. In multivariable models, poor conflict management skills was a risk for bullying and sexual harassment, but not dating violence; acceptance of dating violence was a risk for dating violence and bullying, but not sexual harassment; and none of the examined risk factors were unique to aggression type. The study’s implications for the development of interventions and future research are discussed. PMID:26746242

  9. Shared Risk Factors for the Perpetration of Physical Dating Violence, Bullying, and Sexual Harassment Among Adolescents Exposed to Domestic Violence.

    Science.gov (United States)

    Foshee, Vangie A; McNaughton Reyes, H Luz; Chen, May S; Ennett, Susan T; Basile, Kathleen C; DeGue, Sarah; Vivolo-Kantor, Alana M; Moracco, Kathryn E; Bowling, J Michael

    2016-04-01

    The high risk of perpetrating physical dating violence, bullying, and sexual harassment by adolescents exposed to domestic violence points to the need for programs to prevent these types of aggression among this group. This study of adolescents exposed to domestic violence examined whether these forms of aggression share risk factors that could be targeted for change in single programs designed to prevent all three types of aggression. Analyses were conducted on 399 mother victims of domestic violence and their adolescents, recruited through community advertising. The adolescents ranged in age from 12 to 16 years; 64 % were female. Generalized estimating equations was used to control for the covariation among the aggression types when testing for shared risk factors. Approximately 70 % of the adolescents reported perpetrating at least one of the three forms of aggression. In models examining one risk factor at a time, but controlling for demographics, adolescent acceptance of sexual violence, mother-adolescent discord, family conflict, low maternal monitoring, low mother-adolescent closeness, low family cohesion, depressed affect, feelings of anger, and anger reactivity were shared across all three aggression types. In multivariable models, which included all of the risk factors examined and the demographic variables, low maternal monitoring, depressed affect and anger reactivity remained significant shared risk factors. Our findings suggest that programs targeting these risk factors for change have the potential to prevent all three forms of aggression. In multivariable models, poor conflict management skills was a risk for bullying and sexual harassment, but not dating violence; acceptance of dating violence was a risk for dating violence and bullying, but not sexual harassment; and none of the examined risk factors were unique to aggression type. The study's implications for the development of interventions and future research are discussed.

  10. Knowledge sharing behaviour among non-academic staff in higher learning institutes: The role of trust and perceived risk

    Directory of Open Access Journals (Sweden)

    Muhammad Sabbir Rahman

    2018-03-01

    Full Text Available The purpose of the paper is to analyse knowledge sharing behaviour among non-academic staff of higher learning institutions. This research focuses on the mediation impact of perceived risk on trust and knowledge sharing behaviour. The research also proposes actions that can be taken by higher learning institutions to enhance trust among the staff in order to create a knowledge sharing environment at the workplace. This research applied confirmatory factor analysis and Structural Equation Modeling (SEM to evaluate the proposed measurement model and proved the research hypotheses. The findings from the research show that perceived risk plays a strong mediating role between trust and knowledge sharing behaviour among the non-academic staff of higher learning institutions. The SEM analysis also confirmed that the research model shows a good fit. This research highlights issues concerning knowledge sharing practices among non-academic staff and provides some recommendations to the managers to address these issues. The researchers agreed that more research needs to be done in this area as there are aspects that are yet to be explored. The findings of this research serve to add to the literature on knowledge sharing focussing on non-academic staff of higher learning institutions.

  11. Does market integration buffer risk, erode traditional sharing practices and increase inequality? A test among Bolivian forager-farmers.

    Science.gov (United States)

    Gurven, Michael; Jaeggi, Adrian V; von Rueden, Chris; Hooper, Paul L; Kaplan, Hillard

    2015-08-01

    Sharing and exchange are common practices for minimizing food insecurity in rural populations. The advent of markets and monetization in egalitarian indigenous populations presents an alternative means of managing risk, with the potential impact of eroding traditional networks. We test whether market involvement buffers several types of risk and reduces traditional sharing behavior among Tsimane Amerindians of the Bolivian Amazon. Results vary based on type of market integration and scale of analysis (household vs. village), consistent with the notion that local culture and ecology shape risk management strategies. Greater wealth and income were unassociated with the reliance on others for food, or on reciprocity, but wealth was associated with a greater proportion of food given to others (i.e., giving intensity) and a greater number of sharing partners (i.e., sharing breadth). Across villages, greater mean income was negatively associated with reciprocity, but economic inequality was positively associated with giving intensity and sharing breadth. Incipient market integration does not necessarily replace traditional buffering strategies but instead can often enhance social capital.

  12. Evidence for shared genetic risk between ADHD symptoms and reduced mathematics ability: a twin study.

    Science.gov (United States)

    Greven, Corina U; Kovas, Yulia; Willcutt, Erik G; Petrill, Stephen A; Plomin, Robert

    2014-01-01

    Attention-deficit/hyperactivity disorder (ADHD) symptoms and mathematics ability are associated, but little is known about the genetic and environmental influences underlying this association. Data came from more than 6,000 twelve-year-old twin pairs from the UK population-representative Twins Early Development Study. Parents rated each twin's behaviour using a DSM-IV-based 18-item questionnaire of inattentive and hyperactive-impulsive ADHD symptoms. Mathematics tests based on the UK National Curriculum were completed by each twin. The twins also completed standardised tests of reading and general cognitive ability. Multivariate twin model fitting was applied. Inattentive and hyperactive-impulsive ADHD symptoms were highly heritable (67% and 73% respectively). Mathematics ability was moderately heritable (46%). Mathematics ability and inattentiveness showed a significantly greater phenotypic correlation (r(p) = -.26) and genetic correlation (r(A) = -.41) than mathematics ability and hyperactivity-impulsivity (r(p) = -.18; r(A) = -.22). The genetic correlation between inattentiveness and mathematics ability was largely independent from hyperactivity-impulsivity, and was only partially accounted for by genetic influences related to reading and general cognitive ability. Results revealed the novel finding that mathematics ability shows significantly stronger phenotypic and genetic associations with inattentiveness than with hyperactivity-impulsivity. Genetic associations between inattentiveness and mathematics ability could only partially be accounted for by hyperactivity-impulsivity, reading and general cognitive ability. Results suggest that mathematics ability is associated with ADHD symptoms largely because it shares genetic risk factors with inattentiveness, and provide further evidence for considering inattentiveness and hyperactivity-impulsivity separately. DNA markers for ADHD symptoms (especially inattentiveness) may also be candidate risk factors for

  13. The European Banking Union: Will It Be a True Union without Risk Sharing?

    Directory of Open Access Journals (Sweden)

    Mario Sarcinelli

    2013-06-01

    Full Text Available The recent developments of the Euro crisis reveal the lack of clear or coherent thinking on the part of both the Eurozone finance ministers and the European Commission. The crisis in Cyprus is partly the consequence of decisions made on private sector involvement in the previous Greek bailout, and other such examples may be made. It is time, therefore, to look reality in the face and strengthen the structures of the EMU. The article is devoted to what has been done and what must still be done to make the European banking system more robust and less permeable to crises, and to preserve the single financial market. It looks at the initiatives of both the European Commission and the European Council to complete the EMU by creating a banking union, the doubts on the wisdom of entrusting banking oversight to the ECB, the organization of the ECB’s new tasks, the continuing absence of facilities for the recovery or liquidation of banks, as well as for a Euro-wide deposit insurance, the need for some form of risk-sharing in order to stabilise the economy, and thus the recourse to a common budget and the possibility of joint debt for the Eurozone.

  14. Knowledge Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia: A Participative Workshop to Reduce Volcanic Risk

    Science.gov (United States)

    Sheridan, M. F.; Cordoba, G. A.

    2009-12-01

    Galeras has been in nearly constant activity during modern historic times (roughly the past 500 years). Approximately 10,000 people live within an area designated as the highest-hazard and nearly 400,000 people are within areas of potential harmful effects. A wide variety of stakeholders are affected by the hazards, including: farmers, indigenous villagers, and people in urban environments. Hazards assessment and volcano monitoring are the responsibility of the Colombian Geological Survey (INGEOMINAS), whereas decisions regarding mitigation and response procedures are the responsibility of various governmental offices and the national emergency system (SNPAD). According to the current plan, when the risk level rises to a high level the people in the highest risk zone are required to evacuate. The volcano currently is in a very active, but fluctuating, condition and a future large eruption in a medium time frame (years to decades) is possible. There is a growing level of discomfort among many of the affected groups, including indigenous communities, farmers, and urban dwellers, related to the risk assessment. The general opinion prior to July 2009 was quite polarized as the decision makers saw the people of the region as poorly prepared to understand this hazard, whereas the population felt that their views were not being heard. The result was that the people in the hazardous areas decided not to evacuate, even during the current period of explosive activity. To resolve this situation the University of Nariño (Colombia) and the State University of New York at Buffalo organized a workshop named "Knowledge, Sharing and Collaboration in Volcanic Risk Mitigation at Galeras Volcano, Colombia" that was held in Pasto (Colombia), between 6 and 11 July, 2009. The general objective of this workshop was to analyze the existing hazard maps and safety plans for Galeras and form a bridge connecting scientists, decision makers, and other stake holders to promote a better

  15. Modeling of Mean-VaR portfolio optimization by risk tolerance when the utility function is quadratic

    Science.gov (United States)

    Sukono, Sidi, Pramono; Bon, Abdul Talib bin; Supian, Sudradjat

    2017-03-01

    The problems of investing in financial assets are to choose a combination of weighting a portfolio can be maximized return expectations and minimizing the risk. This paper discusses the modeling of Mean-VaR portfolio optimization by risk tolerance, when square-shaped utility functions. It is assumed that the asset return has a certain distribution, and the risk of the portfolio is measured using the Value-at-Risk (VaR). So, the process of optimization of the portfolio is done based on the model of Mean-VaR portfolio optimization model for the Mean-VaR done using matrix algebra approach, and the Lagrange multiplier method, as well as Khun-Tucker. The results of the modeling portfolio optimization is in the form of a weighting vector equations depends on the vector mean return vector assets, identities, and matrix covariance between return of assets, as well as a factor in risk tolerance. As an illustration of numeric, analyzed five shares traded on the stock market in Indonesia. Based on analysis of five stocks return data gained the vector of weight composition and graphics of efficient surface of portfolio. Vector composition weighting weights and efficient surface charts can be used as a guide for investors in decisions to invest.

  16. Multiple energy supply risks, optimal reserves, and optimal domestic production capacities

    International Nuclear Information System (INIS)

    Zweifel, P.; Ferrari, M.

    1992-01-01

    This study starts from the observation that today's Western trading nations are exposed to multiple risks of energy supplies, e.g. simultaneous shortage of oil and electricity supplies. To cope with these risks, oil can be stockpiled as well as domestic capacity for power production built up. Adopting the viewpoint of a policy maker who aims at minimizing the expected cost of security of supply, optimal simultaneous adjustments of oil stocks and electric production capacities to exogenous changes such as economic growth are derived. Against this benchmark, one-dimensional rules such as 'oil reserves for 90 days' turn out to be not only suboptimal but also to foster adjustments that exacerbate suboptimality. 9 refs., 1 tabs

  17. Performance-Based Risk-Sharing Arrangements: U.S. Payer Experience.

    Science.gov (United States)

    Goble, Joseph A; Ung, Brian; van Boemmel-Wegmann, Sascha; Navarro, Robert P; Parece, Andrew

    2017-10-01

    As a result of global concern about rising drug costs, many U.S. payers and European agencies such as the National Health Service have partnered with pharmaceutical companies in performance-based risk-sharing arrangements (PBRSAs) by which manufacturers share financial risk with health care purchasing entities and authorities. However, PBRSAs present many administrative and legal challenges that have minimized successful contract experiences in the United States. To (a) identify drug and disease characteristics and contract components that contribute to successful PBRSA experiences and the primary barriers to PBRSA execution and (b) explore solutions to facilitate contract negotiation and execution. A 37-item, web-based survey instrument (Qualtrics), approximately 20 minutes in duration, was open during July and August 2016. The survey was emailed to 90 pharmacy and medical directors of various health care organizations. Statistical analysis included the Kruskal-Wallis test and chi-square tests to examine differences among payer responses. Survey responses were anonymized and data were aggregated. Twenty-seven individuals completed the survey (30% completion rate). The majority of respondents worked for regional health plans (52%, n = 14), covering at least 1 million lives (63%, n = 17), with at least 7 years of managed care experience (81%, n = 22). A total of 51 PBRSAs were active among respondents at the time of the survey. Easily obtainable and evaluable drug data and medical data were the most important drug and disease attributes for successful PBRSAs, respectively. Pharmacy claims and patient demographic data were assessed as "very easy and inexpensive" to collect. Type and amount of manufacturer payment for drug outcome performance failure, endpoint measurement, and necessary clinical data for drug performance measurement were all critical factors for successful PBRSAs. Standardized contract templates and transparent contract financial risk evaluation and

  18. Accident frequency and unrealistic optimism: Children's assessment of risk.

    Science.gov (United States)

    Joshi, Mary Sissons; Maclean, Morag; Stevens, Claire

    2018-02-01

    Accidental injury is a major cause of mortality and morbidity among children, warranting research on their risk perceptions. Three hundred and seven children aged 10-11 years assessed the frequency, danger and personal risk likelihood of 8 accidents. Two social-cognitive biases were manifested. The frequency of rare accidents (e.g. drowning) was overestimated, and the frequency of common accidents (e.g. bike accidents) underestimated; and the majority of children showed unrealistic optimism tending to see themselves as less likely to suffer these accidents in comparison to their peers, offering superior skills or parental control of the environment as an explanation. In the case of pedestrian accidents, children recognised their seriousness, underestimated the frequency of this risk and regarded their own road crossing skill as protection. These findings highlight the challenging task facing safety educators who, when teaching conventional safety knowledge and routines, also need to alert children to the danger of over-confidence without disabling them though fear. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Economic risk analysis and critical comparison of optimal biorefinery concepts

    DEFF Research Database (Denmark)

    Cheali, Peam; Posada, John A.; Gernaey, Krist

    2016-01-01

    In this paper, eight optimal biorefinery concepts for biofuels and biochemicals production are critically analyzed and compared in terms of their techno-economic performance and associated economic risks against historical market fluctuations. The investigated biorefinery concepts consider...... different combinations of biomass feedstock (lignocellulosic versus algal) and conversion technologies (biochemical versus thermochemical). In addition, the economic performance of each biorefinery concept is tested assuming a sudden drop in oil prices in order to compare the fitness/survival of each...... concept under extreme market disturbances. The analyses reveal amongst others that: (i) lignocellulosic bioethanol production is not economically feasible considering a drop in oil prices (a negative internal rate of return); (ii) a multi-product biorefinery concept, where bioethanol is upgraded to higher...

  20. Optimal Risk-Based Inspection Planning for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Rangel-Ramirez, Jose G.; Sørensen, John Dalsgaard

    2008-01-01

    , inspection and maintenance activities are developed. This paper considers aspects of inspection and maintenance planning of fatigue prone details in jacket and tripod types of wind turbine support structures. Based oil risk-based inspection planning methods used for oil & gas installations, a framework......Wind turbines for electricity production have increased significantly the last years both in production capability and size. This development is expected to continue also in the coining years. The Support structure for offshore wind turbines is typically a steel structure consisting of a tower...... for optimal inspection and maintenance planning of offshore wind turbines is presented. Special aspects for offshore wind turbines are considered: usually the wind loading are dominating the wave loading, wake effects in wind farms are important and the reliability level is typically significantly lower than...

  1. Preoperative Optimization of Total Joint Arthroplasty Surgical Risk: Obesity.

    Science.gov (United States)

    Fournier, Matthew N; Hallock, Justin; Mihalko, William M

    2016-08-01

    Obesity is a problem that is increasing in prevalence in the United States and in other countries, and it is a common comorbidity in patients seeking total joint arthroplasty for degenerative musculoskeletal diseases. Obesity, as well as commonly associated comorbidities such as diabetes mellitus, cardiovascular disease, and those contributing to the diagnosis of metabolic syndrome, have been shown to have detrimental effects on total joint arthroplasty outcomes. Although there are effective surgical and nonsurgical interventions which can result in weight loss in these patients, concomitant benefit on arthroplasty outcomes is not clear. Preoperative optimization of surgical risk in obese total joint arthroplasty patients is an important point of intervention to improve arthroplasty outcomes. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Resource effects of training general practitioners in risk communication skills and shared decision making competences.

    Science.gov (United States)

    Cohen, David; Longo, M F; Hood, Kerenza; Edwards, Adrian; Elwyn, Glyn

    2004-08-01

    Involving patients more in decisions about their own care requires doctors to be trained in effective ways of communicating information and in developing competences to negotiate levels of patient involvement which are most appropriate for each case. The aim of this study was to determine the cost of such training and identify which service resource variables are subsequently affected. An explanatory cluster randomized crossover trial was carried out which involved training general practitioners (GPs) in the use of risk communication (RC) tools, shared decision making (SDM) competences or both. Continuing care by GPs of patients with one of four chronic conditions (menopausal symptoms, menorrhagia, atrial fibrillation, prostatism) was reviewed before and after training. Cost of training was assessed by prospective monitoring of resources used. Data on prescribing, referrals and investigations were collected via questionnaires to participating practitioners. Data on follow-up GP consultations were extracted from medical records. Three two-level logistic models were performed to investigate the probability of training having an effect on prescribing, referrals and investigations ordered at the review consultation. Training cost pound 1218 per practitioner which increased the cost of a consultation by pound 2.89. Training in SDM or combined with RC significantly affected the probability of a prescription being issued to women with menopausal symptoms and menorrhagia (although RC on its own had no effect) but did not significantly affect prescribing for patients with prostatism or atrial fibrillation. It did not significantly affect the probability of investigations, referrals or follow-up GP visits for any of the conditions. Unless training has a major influence on consultation length, it is unlikely to have any major impacts on cost.

  3. Private sector risk-sharing agreements in the United States: trends, barriers, and prospects.

    Science.gov (United States)

    Garrison, Louis P; Carlson, Josh J; Bajaj, Preeti S; Towse, Adrian; Neumann, Peter J; Sullivan, Sean D; Westrich, Kimberly; Dubois, Robert W

    2015-09-01

    Risk-sharing agreements (RSAs) between drug manufacturers and payers link coverage and reimbursement to real-world performance or utilization of medical products. These arrangements have garnered considerable attention in recent years. However, greater use outside the United States raises questions as to why their use has been limited in the US private sector, and whether their use might increase in the evolving US healthcare system. To understand current trends, success factors, and challenges in the use of RSAs, we conducted a review of RSAs, interviews, and a survey to understand key stakeholders' experiences and expectations for RSAs in the US private sector. Trends in the numbers of RSAs were assessed using a database of RSAs. We also conducted in-depth interviews with stakeholders from pharmaceutical companies, payer organizations, and industry experts in the United States and European Union. In addition, we administered an online survey with a broader audience to identify perceptions of the future of RSAs in the United States. Most manufacturers and payers expressed interest in RSAs and see potential value in their use. Due to numerous barriers associated with outcomes-based agreements, stakeholders were more optimistic about financial-based RSAs. In the US private sector, however, there remains considerable interest--improved data systems and shifting incentives (via health reform and accountable care organizations) may generate more action. In the US commercial payer markets, there is continued interest among some manufacturers and payers in outcomes-based RSAs. Despite continued discussion and activity, the number of new agreements is still small.

  4. Multiple sclerosis risk sharing scheme: two year results of clinical cohort study with historical comparator.

    Science.gov (United States)

    Boggild, Mike; Palace, Jackie; Barton, Pelham; Ben-Shlomo, Yoav; Bregenzer, Thomas; Dobson, Charles; Gray, Richard

    2009-12-02

    To generate evidence on the longer term cost effectiveness of disease modifying treatments in patients with relapsing-remitting multiple sclerosis. Prospective cohort study with historical comparator. Specialist multiple sclerosis clinics in 70 centres in the United Kingdom. Patients with relapsing-remitting multiple sclerosis who started treatment from May 2002 to April 2005 under the UK risk sharing scheme. Treatment with interferon beta or glatiramer acetate in accordance with guidelines of the UK Association of British Neurologists. Observed utility weighted progression in disability at two years' follow-up assessed on the expanded disability status scale (EDSS) compared with that expected by applying the progression rates in a comparator dataset, modified for patients receiving treatment by multiplying by the hazard ratio derived separately for each disease modifying treatment from the randomised trials. In the primary per protocol analysis, progression in disability was worse than that predicted and worse than that in the untreated comparator dataset ("deviation score" of 113%; excess in mean disability status scale 0.28). In sensitivity analyses, however, the deviation score varied from -72% (using raw baseline disability status scale scores, rather than applying a "no improvement" algorithm) to 156% (imputing missing data for year two from progression rates for year one). It is too early to reach any conclusion about the cost effectiveness of disease modifying treatments from this first interim analysis. Important methodological issues, including the need for additional comparator datasets, the potential bias from missing data, and the impact of the "no improvement" rule, will need to be addressed and long term follow-up of all patients is essential to secure meaningful results. Future analyses of the cohort are likely to be more informative, not least because they will be less sensitive to short term fluctuations in disability.

  5. Shared Responsibility for Type 1 Diabetes Care Is Associated With Glycemic Variability and Risk of Glycemic Excursions in Youth.

    Science.gov (United States)

    Marker, Arwen M; Noser, Amy E; Clements, Mark A; Patton, Susana R

    2018-01-01

    We examined how parent and youth responsibility for type 1 diabetes (T1D) care is related to adherence and glycemic outcomes, namely, glycemic variability and risk of glycemic excursions. One hundred thirty-five parent-youth dyads (10-16 years old; diagnosed with T1D for at least 6 months) participated in this study. Percent responsibility of T1D care attributed to the youth, parent, or shared was measured using the Diabetes Family Responsibility Questionnaire. We collected youth's hemoglobin A1c (HbA1c) and glucometer downloads to examine relationships between responsibility and HbA1c, frequency of blood glucose monitoring (self-monitoring blood glucose, SMBG), risk of glycemic excursions, and actual glycemic variability using bivariate correlations and path analysis. Participants reported shared responsibility for almost half of T1D self-care tasks. Bivariate correlations showed shared responsibility was associated with less variability, whereas parent responsibility was associated with greater glycemic variability and risk for glycemic excursions. Youth responsibility was associated with lower frequency of SMBG. The path analyses confirmed our correlational findings (pshypothesis that shared T1D responsibility is associated with better diabetes outcomes in youth. © The Author 2017. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

  6. Applications of nuclear safety probabilistic risk assessment to nuclear security for optimized risk mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Donnelly, S.K.; Harvey, S.B. [Amec Foster Wheeler, Toronto, Ontario (Canada)

    2016-06-15

    Critical infrastructure assets such as nuclear power generating stations are potential targets for malevolent acts. Probabilistic methodologies can be applied to evaluate the real-time security risk based upon intelligence and threat levels. By employing this approach, the application of security forces and other protective measures can be optimized. Existing probabilistic safety analysis (PSA) methodologies and tools employed. in the nuclear industry can be adapted to security applications for this purpose. Existing PSA models can also be adapted and enhanced to consider total plant risk, due to nuclear safety risks as well as security risks. By creating a Probabilistic Security Model (PSM), safety and security practitioners can maximize the safety and security of the plant while minimizing the significant costs associated with security upgrades and security forces. (author)

  7. Analysis of Risk Optimization on the Industrial Area Around

    International Nuclear Information System (INIS)

    Sony, DT; Demon-Handoyo

    2000-01-01

    Indonesia as an industrial country, there are large industrial area whichis directly or indirectly have an effect to human health by routine dischargeof waste from industrial installations. So, the criteria limit must bedetermined to regulate industrial area. The PRA method (Probabilistic RiskAssessment) is used in the nuclear technology especially reactor safetytechnology could be applied to accommodate those problems. The principles ofPRA method is to determine probability and consequences for accident ofindustrial plant or transportation of product. The analysis procedureincludes classification of industry activity type and inventories, estimationof external consequences, estimation of probability for installation andtransportation accident, determination of social risk and prioritization ofrisks. Calculation of consequence is based on the lost of life which isaffected by fire, toxic and explosive. The calculation for one industrialarea simple model as case study was done. From the calculation result, theconsequences value of 0 - 25 persons/event; 26 - 50 persons/event; 51 - 75persons/event, 625 - 650 persons/event and the event probability value of1.10 -2 to 3.10 -8 are obtained. The optimization value of industrial areaaround can be determined by using combination of probability value andconsequences value. (author)

  8. Performance-based risk-sharing arrangements-good practices for design, implementation, and evaluation: report of the ISPOR good practices for performance-based risk-sharing arrangements task force.

    Science.gov (United States)

    Garrison, Louis P; Towse, Adrian; Briggs, Andrew; de Pouvourville, Gerard; Grueger, Jens; Mohr, Penny E; Severens, J L Hans; Siviero, Paolo; Sleeper, Miguel

    2013-01-01

    There is a significant and growing interest among both payers and producers of medical products for agreements that involve a "pay-for-performance" or "risk-sharing" element. These payment schemes-called "performance-based risk-sharing arrangements" (PBRSAs)-involve a plan by which the performance of the product is tracked in a defined patient population over a specified period of time and the amount or level of reimbursement is based on the health and cost outcomes achieved. There has always been considerable uncertainty at product launch about the ultimate real-world clinical and economic performance of new products, but this appears to have increased in recent years. PBRSAs represent one mechanism for reducing this uncertainty through greater investment in evidence collection while a technology is used within a health care system. The objective of this Task Force report was to set out the standards that should be applied to "good practices"-both research and operational-in the use of a PBRSA, encompassing questions around the desirability, design, implementation, and evaluation of such an arrangement. This report provides practical recommendations for the development and application of state-of-the-art methods to be used when considering, using, or reviewing PBRSAs. Key findings and recommendations include the following. Additional evidence collection is costly, and there are numerous barriers to establishing viable and cost-effective PBRSAs: negotiation, monitoring, and evaluation costs can be substantial. For good research practice in PBRSAs, it is critical to match the appropriate study and research design to the uncertainties being addressed. Good governance processes are also essential. The information generated as part of PBRSAs has public good aspects, bringing ethical and professional obligations, which need to be considered from a policy perspective. The societal desirability of a particular PBRSA is fundamentally an issue as to whether the cost of

  9. The use of copula functions for modeling the risk of investment in shares traded on the Warsaw Stock Exchange

    Science.gov (United States)

    Domino, Krzysztof; Błachowicz, Tomasz

    2014-11-01

    In our work copula functions and the Hurst exponent calculated using the local Detrended Fluctuation Analysis (DFA) were used to investigate the risk of investment made in shares traded on the Warsaw Stock Exchange. The combination of copula functions and the Hurst exponent calculated using local DFA is a new approach. For copula function analysis bivariate variables composed of shares prices of the PEKAO bank (a big bank with high capitalization) and other banks (PKOBP, BZ WBK, MBANK and HANDLOWY in decreasing capitalization order) and companies from other branches (KGHM-mining industry, PKNORLEN-petrol industry as well as ASSECO-software industry) were used. Hurst exponents were calculated for daily shares prices and used to predict high drops of those prices. It appeared to be a valuable indicator in the copula selection procedure, since Hurst exponent’s low values were pointing on heavily tailed copulas e.g. the Clayton one.

  10. Child Sexual Abuse and Negative Affect as Shared Risk Factors for Sexual Aggression and Sexual HIV Risk Behavior in Heterosexual Men.

    Science.gov (United States)

    Peterson, Zoё D; Janssen, Erick; Goodrich, David; Fortenberry, J Dennis; Hensel, Devon J; Heiman, Julia R

    2018-02-01

    Previous research has suggested that sexually aggressive behavior and sexual HIV risk behavior are associated. Childhood sexual abuse (CSA) is a well-established risk factor for both types of problematic sexual behavior. Negative affect (i.e., anxiety, depression, and anger) is a less well-studied risk factor, but it has been theorized to relate to both sexual aggression and HIV risk behavior. Thus, this study sought to (1) confirm the relationship between sexual aggression and HIV risk behavior, (2) establish CSA and negative affect as shared risk factors for sexual aggression and HIV risk behavior, and (3) evaluate whether negative affect mediates the relationship between CSA and sexual aggression and between CSA and HIV sexual risk in a sample of heterosexual men. We recruited 18- to 30-year-old heterosexual men (N = 377) from urban sexually transmitted infection clinics. Men completed measures of sexual HIV risk history (number of partners and condom use), sexual aggression history, CSA history, and trait negative affect (anger, anxiety, and depression). Structural equation modeling was used to examine hypothesized direct and indirect relationships. In the final SEM model, sexual aggression history and sexual HIV risk behavior were correlated. CSA was associated with both types of problematic sexual behavior. Anxiety significantly mediated the relationship between CSA and sexual aggression and between CSA and sexual HIV risk behavior (χ 2 [1300] = 2121.79, p Sexual aggression appears to be part of a constellation of sexual risk behaviors; thus, it may be possible to develop prevention programs that target both sexual HIV risk and sexual aggression. CSA is a shared risk factor for sexual aggression and HIV risk behavior through the pathway of anxiety. Thus, anxiety might be one promising target for intervention.

  11. The costs of electricity systems with a high share of fluctutating renewables. A stochastic investment and dispatch optimization model for Europe

    International Nuclear Information System (INIS)

    Nagl, Stephan; Fuersch, Michaela; Lindenberger, Dietmar

    2012-01-01

    Renewable energies are meant to produce a large share of the future electricity demand. However, the availability of wind and solar power depends on local weather conditions and therefore weather characteristics must be considered when optimizing the future electricity mix. In this article we analyze the impact of the stochastic availability of wind and solar energy on the cost-minimal power plant mix and the related total system costs. To determine optimal conventional, renewable and storage capacities for different shares of renewables, we apply a stochastic investment and dispatch optimization model to the European electricity market. The model considers stochastic feed-in structures and full load hours of wind and solar technologies and different correlations between regions and technologies. Key findings include the overestimation of fluctuating renewables and underestimation of total system costs compared to deterministic investment and dispatch models. Furthermore, solar technologies are - relative to wind turbines - underestimated when neglecting negative correlations between wind speeds and solar radiation.

  12. Identification of risk loci with shared effects on five major psychiatric disorders

    DEFF Research Database (Denmark)

    Steinhausen, Hans-Christoph E.; Strauss, John; Strohmaier, Jana

    2013-01-01

    Findings from family and twin studies suggest that genetic contributions to psychiatric disorders do not in all cases map to present diagnostic categories. We aimed to identify specific variants underlying genetic effects shared between the five disorders in the Psychiatric Genomics Consortium: a......: autism spectrum disorder, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder, and schizophrenia.......Findings from family and twin studies suggest that genetic contributions to psychiatric disorders do not in all cases map to present diagnostic categories. We aimed to identify specific variants underlying genetic effects shared between the five disorders in the Psychiatric Genomics Consortium...

  13. Risk Informed Optimization of Nuclear Instrumentation for Emergency Conditions

    International Nuclear Information System (INIS)

    Knoll, Alexander

    2013-06-01

    Emergency conditions after a nuclear accident are different in each case and cannot be predicted accurately. The accident at TMI did not contaminate the environment. The accident at Chernobyl had a large, early release of nuclear contamination, widely dispersed over many countries. Although there was no large, early release of contamination at Fukushima Daiichi, the timeline of the accident included days of later contamination of various degrees of severity. A large amount of the contamination has been released to the ocean and an exclusion zone still exists around the station. In all of these accidents there were no adequate radiation monitoring systems distant from the origin point that could provide accurate status to the authorities and the local population. In the recent years a number of new nuclear monitoring systems have been implemented or are under development to be installed in areas that might be exposed to nuclear contamination in emergencies. Based on the risk informed optimization methodology, this paper provides recommendations for selecting the quantity and type of instrumentation, the location and sampling of data, and the real-time processing of information. (authors)

  14. Power sector investment risk and renewable energy: A Japanese case study using portfolio risk optimization method

    International Nuclear Information System (INIS)

    Bhattacharya, Anindya; Kojima, Satoshi

    2012-01-01

    The conventional pricing mechanism used for electricity systematically hides huge investment risks which are embedded in the overall cost of production. Although consumers are often unaware of these risks, they present a large financial burden on the economy. This study applies the portfolio optimization concepts from the field of finance to demonstrate the scope of greater utilization of renewable energies (RE) while reducing the embedded investment risk in the conventional electricity sector and its related financial burden. This study demonstrates that RE investment can compensate for the risks associated with the total input costs; such costs being external volatilities of fossil fuel prices, capital costs, operating and maintenance costs and the carbon costs. By means of example, this case study shows that Japan could in theory obtain up to 9% of its electricity supply from green sources, as compared to the present 1.37%, based on the utilization of a portfolio risk-analysis evaluation. Explicit comparison of the monetary values of the investment risks of conventional and renewable energy sources shows that renewable energies have high market competitiveness. The study concludes with a recommendation that, as a business objective, investors would benefit by focusing on electricity supply portfolio risk minimization instead of cost. This could also inherently increase the supply of renewable energy in the market. - Research highlights: ►Energy sector investors should not be bothered only about the absolute cost figures of the input factors like fossil fuels but should also be careful about the fluctuation of their costs while making the investment decisions. ►Inclusion of renewable energy in the investment portfolio can increase the cost apparently but can reduce the risk hedging costs, too. ►International carbon price may not be a good factor to encourage renewable energy investment in the market.

  15. ORRION: A specific information sharing tool to (rebuild a “flood risk culture” in the Rhine Graben (France - Germany

    Directory of Open Access Journals (Sweden)

    Martin Brice

    2016-01-01

    Full Text Available When is led a prevention initiative concerning flood risk, the recall of old events allows just as much to act as pedagogy to legitimize the initiative. So as it is written in the information leaflet on the “Plan de Prévention des Risques d’Inondation” (PPRI:«Alsace did not know any more exceptional floods since 1910. In almost a century, the flood risk thus naturally faded of our memory”. A paradoxical assertion because the floods of 1910 are not taken into account for risk mapping. Only the recent floods (1983, 1990 are used as benchmarks. We were able to show [1] that, although legitimate as reference events, the floods of 1910 and many others had become manifestly underestimated for multiple reasons connected to the history of Alsace, or due to disorganization of the archives. Worse, these riks unawareness is shared by all the actors, causing problems of acceptance of the risk and their management, and an additional vulnerability in terms of population behavior before, during and after the crises. This is the reason why an online participative database (ORRION has been created. the objective of this database is to inform and to share the information about floods history, in the particular context of a cross-border territory (France, Germany, Switzerland. This tool has been immediately involved into risks prevention actions (PAPI, PPRI.

  16. No evidence that common genetic risk variation is shared between schizophrenia and autism

    NARCIS (Netherlands)

    Vorstman, Jacob A. S.; Anney, Richard J. L.; Derks, Eske M.; Gallagher, Louise; Gill, Michael; de Jonge, Maretha V.; van Engeland, Herman; Kahn, René S.; Ophoff, Roel A.

    2013-01-01

    The similarity between aspects of the clinical presentation of schizophrenia and autism spectrum disorders (ASD) suggests that elements of the biological etiology may also be shared between these two disorders. Recently, an increasing number of rare, mostly structural genetic variants are reported

  17. Additive genetic variation in schizophrenia risk is shared by populations of African and European descent

    NARCIS (Netherlands)

    De Candia, T.r.; Lee, S.H.; Yang, J.; Browning, B.L.; Gejman, P. V.; Levinson, D. F.; Mowry, B. J.; Hewitt, J.K.; Goddard, M.E.; O'Donovan, M.C.; Purcell, S.M.; Posthuma, D.; Visscher, P. M.; Wray, N.R.; Keller, M. C.

    2013-01-01

    To investigate the extent to which the proportion of schizophrenia's additive genetic variation tagged by SNPs is shared by populations of European and African descent, we analyzed the largest combined African descent (AD [n = 2,142]) and European descent (ED [n = 4,990]) schizophrenia case-control

  18. The educational gradient in cardiovascular risk factors: impact of shared family factors in 228,346 Norwegian siblings

    Directory of Open Access Journals (Sweden)

    Inger Ariansen

    2017-03-01

    Full Text Available Abstract Background Various indicators of childhood socioeconomic position have been related to cardiovascular disease (CVD risk in adulthood. We investigated the impact of shared family factors on the educational gradient in midlife CVD risk factors by assessing within sibling similarities in the gradient using a discordant sibling design. Methods Norwegian health survey data (1980–2003 was linked to educational and generational data. Participants with a full sibling in the health surveys (228,346 individuals in 98,046 sibships were included. Associations between attained educational level (7–9 years, 10–11 years, 12 years, 13–16 years, or >16 years and CVD risk factor levels in the study population was compared with the corresponding associations within siblings. Results Educational gradients in risk factors were attenuated when factors shared by siblings was taken into account: A one category lower educational level was associated with 0.7 (95% confidence interval 0.6 to 0.8 mm Hg higher systolic blood pressure (27% attenuation, 0.4 (0.4 to 0.5 mmHg higher diastolic blood pressure (30%, 1.0 (1.0 to 1.1 more beats per minute higher heart rate (21%, 0.07 (0.06 to 0.07 mmol/l higher serum total cholesterol (32%, 0.2 (0.2 to 0.2 higher smoking level (5 categories (30%, 0.15 (0.13 to 0.17 kg/m2 higher BMI (43%, and 0.2 (0.2 to 0.2 cm lower height (52%. Attenuation increased with shorter age-difference between siblings. Conclusion About one third of the educational gradients in modifiable CVD risk factors may be explained by factors that siblings share. This implies that childhood environment is important for the prevention of CVD.

  19. The educational gradient in cardiovascular risk factors: impact of shared family factors in 228,346 Norwegian siblings.

    Science.gov (United States)

    Ariansen, Inger; Mortensen, Laust Hvas; Graff-Iversen, Sidsel; Stigum, Hein; Kjøllesdal, Marte Karoline Råberg; Næss, Øyvind

    2017-03-30

    Various indicators of childhood socioeconomic position have been related to cardiovascular disease (CVD) risk in adulthood. We investigated the impact of shared family factors on the educational gradient in midlife CVD risk factors by assessing within sibling similarities in the gradient using a discordant sibling design. Norwegian health survey data (1980-2003) was linked to educational and generational data. Participants with a full sibling in the health surveys (228,346 individuals in 98,046 sibships) were included. Associations between attained educational level (7-9 years, 10-11 years, 12 years, 13-16 years, or >16 years) and CVD risk factor levels in the study population was compared with the corresponding associations within siblings. Educational gradients in risk factors were attenuated when factors shared by siblings was taken into account: A one category lower educational level was associated with 0.7 (95% confidence interval 0.6 to 0.8) mm Hg higher systolic blood pressure (27% attenuation), 0.4 (0.4 to 0.5) mmHg higher diastolic blood pressure (30%), 1.0 (1.0 to 1.1) more beats per minute higher heart rate (21%), 0.07 (0.06 to 0.07) mmol/l higher serum total cholesterol (32%), 0.2 (0.2 to 0.2) higher smoking level (5 categories) (30%), 0.15 (0.13 to 0.17) kg/m 2 higher BMI (43%), and 0.2 (0.2 to 0.2) cm lower height (52%). Attenuation increased with shorter age-difference between siblings. About one third of the educational gradients in modifiable CVD risk factors may be explained by factors that siblings share. This implies that childhood environment is important for the prevention of CVD.

  20. Optimal fuel-mix in CHP plants under a stochastic permit price. Risk-neutrality versus risk-aversion

    International Nuclear Information System (INIS)

    Lappi, Pauli; Ollikka, Kimmo; Ollikainen, Markku

    2010-01-01

    This paper studies the optimal fuel-mix of a CHP producer under emission permit price risk. The producer's multi-fuel plant uses two CO 2 -intensive fuels and one clean fuel. Using a mean-variance framework we develop three models. The models are divided into spot-models (risk neutral and risk averse cases) and a forward-model (risk averse case). We derive the effects of price risk on optimal fuel use. An increase in price risk can in fact increase the use of CO 2 -intensive fuel in the spot-model. In the forward-model, the production and financial decisions are separate. We also evaluate the risk-bearing behavior of seven Finnish CHP producers. We found that risk-neutrality describes behavior better than risk-aversion. (author)

  1. Optimal fuel-mix in CHP plants under a stochastic permit price. Risk-neutrality versus risk-aversion

    Energy Technology Data Exchange (ETDEWEB)

    Lappi, Pauli; Ollikka, Kimmo; Ollikainen, Markku [Department of Economics and Management, P.O. Box 27, University of Helsinki, FIN-00014 Helsinki (Finland)

    2010-02-15

    This paper studies the optimal fuel-mix of a CHP producer under emission permit price risk. The producer's multi-fuel plant uses two CO{sub 2}-intensive fuels and one clean fuel. Using a mean-variance framework we develop three models. The models are divided into spot-models (risk neutral and risk averse cases) and a forward-model (risk averse case). We derive the effects of price risk on optimal fuel use. An increase in price risk can in fact increase the use of CO{sub 2}-intensive fuel in the spot-model. In the forward-model, the production and financial decisions are separate. We also evaluate the risk-bearing behavior of seven Finnish CHP producers. We found that risk-neutrality describes behavior better than risk-aversion. (author)

  2. Optimal fuel-mix in CHP plants under a stochastic permit price: Risk-neutrality versus risk-aversion

    Energy Technology Data Exchange (ETDEWEB)

    Lappi, Pauli, E-mail: pauli.lappi@helsinki.f [Department of Economics and Management, P.O. Box 27, University of Helsinki, FIN-00014 Helsinki (Finland); Ollikka, Kimmo, E-mail: kimmo.ollikka@helsinki.f [Department of Economics and Management, P.O. Box 27, University of Helsinki, FIN-00014 Helsinki (Finland); Ollikainen, Markku, E-mail: markku.ollikainen@helsinki.f [Department of Economics and Management, P.O. Box 27, University of Helsinki, FIN-00014 Helsinki (Finland)

    2010-02-15

    This paper studies the optimal fuel-mix of a CHP producer under emission permit price risk. The producer's multi-fuel plant uses two CO{sub 2}-intensive fuels and one clean fuel. Using a mean-variance framework we develop three models. The models are divided into spot-models (risk neutral and risk averse cases) and a forward-model (risk averse case). We derive the effects of price risk on optimal fuel use. An increase in price risk can in fact increase the use of CO{sub 2}-intensive fuel in the spot-model. In the forward-model, the production and financial decisions are separate. We also evaluate the risk-bearing behavior of seven Finnish CHP producers. We found that risk-neutrality describes behavior better than risk-aversion.

  3. A Risk-Sensitive Portfolio Optimization Problem with Fixed Incomes Securities

    OpenAIRE

    Goel, Mayank; Kumar, K. Suresh

    2007-01-01

    We discuss a class of risk-sensitive portfolio optimization problems. We consider the portfolio optimization model investigated by Nagai in 2003. The model by its nature can include fixed income securities as well in the portfolio. Under fairly general conditions, we prove the existence of optimal portfolio in both finite and infinite horizon problems.

  4. Effective mine risk education in war-zone areas--a shared responsibility.

    Science.gov (United States)

    Durham, Joanne; Gillieatt, Sue; Sisavath, Bounpheng

    2005-09-01

    The focus of this paper is effective health education and promotion in the field of mine awareness, or what has more recently been re-titled 'mine risk education'. According to the United Nations, mine risk education comprises educational activities that aim to reduce the risk of injury from landmine/unexploded ordnance (UXO) through raising awareness and promoting behavioural change and includes public information dissemination, education and training, and community mine action liaison. Specifically, this paper is an empirical study of mine risk education practices using data collected during the implementation of a mine risk education programme that commenced in Lao PDR in 1996 and is ongoing. In particular, it considers lessons learned from the programme's monitoring and evaluation process. The authors argue that in a country such as Lao PDR, where communities have lived with UXO infestation for over 25 years, more mine risk education is not necessarily needed. This paper concludes that common programmes of mine risk education using top-down educational methods, based on the assumption that ignorance of landmine/UXO risk is the key factor in mine accidents, are inadequate. Evidence from the literature on health promotion and the experience of the programme indicate that there is a need to supplement or replace existing common mine risk education practices with techniques that incorporate an understanding of the economic, social and political circumstances faced by communities at risk.

  5. Risk Acceptance Criteria and/or Decision optimization

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager

    1996-01-01

    Acceptance criteria applied in practical risk analysis are recapitulated including the concept of rist profile. Modelling of risk profiles is illustrated on the basis of compound Poisson process models. The current practice of authoritative acceptance criteria formulation is discussed from...... a decision theoretical point of view. It is argued that the phenomenon of risk aversion rather than being of concern to the authority should be of concern to the owner. Finally it is discussed whether there is an ethical problem when formally capitalising human lives with a positive interest rate. Keywords......: Risk acceptance, Risk profile, Compound Poisson model for risk profile, Capitalization of human life, Risk aversion....

  6. Financing, risk covering and sharing; Financement, couverture et partage des risques

    Energy Technology Data Exchange (ETDEWEB)

    Gouze, J.R. [Sinerg, Societe d`Investissement en Energie, 92 - Boulogne Billancourt (France)

    1996-07-01

    The risks and constraints of a cogeneration project are studied, and it is shown that investments in cogeneration are restrained by the technical complexity, the high financial costs and the industrial and economical risks. These risks are identified in the various phases of the project (design, realization and operation). An innovative investment solution, known as third-party-investment which offers the client all the technical and financial charges and the operating assistance, is presented. Technical and industrial risks are covered by assistance, insurance, supply contracts and covering contracts

  7. Optimal Risk Reduction in the Railway Industry by Using Dynamic Programming

    OpenAIRE

    Michael Todinov; Eberechi Weli

    2013-01-01

    The paper suggests for the first time the use of dynamic programming techniques for optimal risk reduction in the railway industry. It is shown that by using the concept ‘amount of removed risk by a risk reduction option’, the problem related to optimal allocation of a fixed budget to achieve a maximum risk reduction in the railway industry can be reduced to an optimisation problem from dynamic programming. For n risk reduction options and size of the available risk reduction budget B (expres...

  8. Is periodontitis a comorbidity of COPD or can associations be explained by shared risk factors/behaviors?

    Science.gov (United States)

    Hobbins, Stephanie; Chapple, Iain Lc; Sapey, Elizabeth; Stockley, Robert A

    2017-01-01

    COPD is recognized as having a series of comorbidities potentially related to common inflammatory processes. Periodontitis is one of the most common human inflammatory diseases and has previously been associated with COPD in numerous observational studies. As periodontitis and COPD are both chronic, progressive conditions characterized by neutrophilic inflammation with subsequent proteolytic destruction of connective tissue, it has been proposed that they share common pathophysiological processes. The mechanisms proposed to link COPD and periodontitis include mechanical aspiration of oral contents into the respiratory tree, overspill of locally produced inflammatory mediators into the systemic circulation or oral or lung-derived bacteremia activating an acute-phase response and also reactive oxygen species (ROS) and cytokine release by systemic neutrophils at distant sites. Studies of systemic neutrophils in COPD and chronic periodontitis describe altered cellular functions that would predispose to inflammation and tissue destruction both in the lung and in the mouth, again potentially connecting these conditions. However, COPD and periodontitis also share risk factors such as age, chronic tobacco smoke exposure, and social deprivation that are not always considered in observational and interventional studies. Furthermore, studies reporting associations have often utilized differing definitions of both COPD and periodontitis. This article reviews the current available evidence supporting the hypothesis that COPD and inflammatory periodontal disease (periodontitis) could be pathologically associated, including a review of shared inflammatory mechanisms. It highlights the potential limitations of previous studies, in particular, the lack of uniformly applied case definitions for both COPD and periodontitis and poor recognition of shared risk factors. Understanding associations between these conditions may inform why patients with COPD suffer such a burden of comorbid

  9. Offset Risk Minimization for Open-loop Optimal Control of Oil Reservoirs

    DEFF Research Database (Denmark)

    Capolei, Andrea; Christiansen, Lasse Hjuler; Jørgensen, J. B.

    2017-01-01

    Simulation studies of oil field water flooding have demonstrated a significant potential of optimal control technology to improve industrial practices. However, real-life applications are challenged by unknown geological factors that make reservoir models highly uncertain. To minimize...... the associated financial risks, the oil literature has used ensemble-based methods to manipulate the net present value (NPV) distribution by optimizing sample estimated risk measures. In general, such methods successfully reduce overall risk. However, as this paper demonstrates, ensemble-based control strategies...... practices. The results suggest that it may be more relevant to consider the NPV offset distribution than the NPV distribution when minimizing risk in production optimization....

  10. Risk-Averse Suppliers’ Optimal Pricing Strategies in a Two-Stage Supply Chain

    Directory of Open Access Journals (Sweden)

    Rui Shen

    2013-01-01

    Full Text Available Risk-averse suppliers’ optimal pricing strategies in two-stage supply chains under competitive environment are discussed. The suppliers in this paper focus more on losses as compared to profits, and they care their long-term relationship with their customers. We introduce for the suppliers a loss function, which covers both current loss and future loss. The optimal wholesale price is solved under situations of risk neutral, risk averse, and a combination of minimizing loss and controlling risk, respectively. Besides, some properties of and relations among these optimal wholesale prices are given as well. A numerical example is given to illustrate the performance of the proposed method.

  11. The effect of a new lifetime-cardiovascular-risk display on patients' motivation to participate in shared decision-making.

    Science.gov (United States)

    Jegan, Nikita Roman A; Kürwitz, Sarah Anna; Kramer, Lena Kathrin; Heinzel-Gutenbrunner, Monika; Adarkwah, Charles Christian; Popert, Uwe; Donner-Banzhoff, Norbert

    2018-06-09

    This study investigated the effects of three different risk displays used in a cardiovascular risk calculator on patients' motivation for shared decision-making (SDM). We compared a newly developed time-to-event (TTE) display with two established absolute risk displays (i.e. emoticons and bar charts). The accessibility, that is, how understandable, helpful, and trustworthy patients found each display, was also investigated. We analysed a sample of 353 patients recruited in general practices. After giving consent, patients were introduced to one of three fictional vignettes with low, medium or high cardiovascular risk. All three risk displays were shown in a randomized order. Patients were asked to rate each display with regard to motivation for SDM and accessibility. Two-factorial repeated measures analyses of variance were conducted to compare the displays and investigate possible interactions with age. Regarding motivation for SDM, the TTE elicited the highest motivation, followed by the emoticons and bar chart (p motivation for SDM and accessibility when compared to established displays using emoticons and a bar chart. If future research can replicate these results in real-life consultations, the TTE display will be a valuable addition to current risk calculators and decision aids by improving patients' participation.

  12. Analisis Pembentukan Portofolio Optimal Saham Dengan Pendekatan Optimisasi Multiobjektif Untuk Pengukuran Value at Risk

    OpenAIRE

    Farkhati, Fiki; Hoyyi, Abdul; Wilandari, Yuciana

    2014-01-01

    Mean Variance Efficient Portfolio (MVEP) is theory of portfolio which purposed to standard investor because approach has only one objective that minimize portfolio risk. Portfolio with multi-objective optimization that simultaneously maximize portfolio return and minimize portfolio risk with various weighting coefficient k represents risk aversion index. The purpose of this research is analyze proportion each stock in order that is formed optimal portfolio approach multi-objective optimizati...

  13. A model for the optimal risk management of farm firms

    DEFF Research Database (Denmark)

    Rasmussen, Svend

    2012-01-01

    Risk management is an integrated part of business or firm management and deals with the problem of how to avoid the risk of economic losses when the objective is to maximize expected profit. This paper will focus on the identification, assessment, and prioritization of risks in agriculture followed...... by a description of procedures for coordinated and economical application of resources to control the probability and/or impact of unfortunate events. Besides identifying the major risk factors and tools for risk management in agricultural production, the paper will look critically into the current methods...... for risk management Risk management is typically based on numerical analysis and the concept of efficiency. None of the methods developed so far actually solve the basic question of how the individual manager should behave so as to optimise the balance between expected profit/income and risk. In the paper...

  14. Risk-sensitive optimal feedback control accounts for sensorimotor behavior under uncertainty.

    Directory of Open Access Journals (Sweden)

    Arne J Nagengast

    2010-07-01

    Full Text Available Many aspects of human motor behavior can be understood using optimality principles such as optimal feedback control. However, these proposed optimal control models are risk-neutral; that is, they are indifferent to the variability of the movement cost. Here, we propose the use of a risk-sensitive optimal controller that incorporates movement cost variance either as an added cost (risk-averse controller or as an added value (risk-seeking controller to model human motor behavior in the face of uncertainty. We use a sensorimotor task to test the hypothesis that subjects are risk-sensitive. Subjects controlled a virtual ball undergoing Brownian motion towards a target. Subjects were required to minimize an explicit cost, in points, that was a combination of the final positional error of the ball and the integrated control cost. By testing subjects on different levels of Brownian motion noise and relative weighting of the position and control cost, we could distinguish between risk-sensitive and risk-neutral control. We show that subjects change their movement strategy pessimistically in the face of increased uncertainty in accord with the predictions of a risk-averse optimal controller. Our results suggest that risk-sensitivity is a fundamental attribute that needs to be incorporated into optimal feedback control models.

  15. Dispositional optimism and perceived risk interact to predict intentions to learn genome sequencing results.

    Science.gov (United States)

    Taber, Jennifer M; Klein, William M P; Ferrer, Rebecca A; Lewis, Katie L; Biesecker, Leslie G; Biesecker, Barbara B

    2015-07-01

    Dispositional optimism and risk perceptions are each associated with health-related behaviors and decisions and other outcomes, but little research has examined how these constructs interact, particularly in consequential health contexts. The predictive validity of risk perceptions for health-related information seeking and intentions may be improved by examining dispositional optimism as a moderator, and by testing alternate types of risk perceptions, such as comparative and experiential risk. Participants (n = 496) had their genomes sequenced as part of a National Institutes of Health pilot cohort study (ClinSeq®). Participants completed a cross-sectional baseline survey of various types of risk perceptions and intentions to learn genome sequencing results for differing disease risks (e.g., medically actionable, nonmedically actionable, carrier status) and to use this information to change their lifestyle/health behaviors. Risk perceptions (absolute, comparative, and experiential) were largely unassociated with intentions to learn sequencing results. Dispositional optimism and comparative risk perceptions interacted, however, such that individuals higher in optimism reported greater intentions to learn all 3 types of sequencing results when comparative risk was perceived to be higher than when it was perceived to be lower. This interaction was inconsistent for experiential risk and absent for absolute risk. Independent of perceived risk, participants high in dispositional optimism reported greater interest in learning risks for nonmedically actionable disease and carrier status, and greater intentions to use genome information to change their lifestyle/health behaviors. The relationship between risk perceptions and intentions may depend on how risk perceptions are assessed and on degree of optimism. (c) 2015 APA, all rights reserved.

  16. Comorbidity of depression with levels of smoking: an exploration of the shared familial risk hypothesis.

    Science.gov (United States)

    Johnson, Eric O; Rhee, Soo Hyun; Chase, Gary A; Breslau, Naomi

    2004-12-01

    Comorbidity of depression and smoking is well recognized, but results from studies that have assessed alternative explanations have varied by the level of smoking and the study method. We examined all 13 etiology models of comorbidity described by Neale and Kendler (American Journal of Genetics, 57, 935-953, 1995) for depression and each of four levels of smoking to shed light on the role that differing definitions might have played in generating the conflicting findings. Data came from 979 young adults aged 26-35 years who participated in an epidemiological cohort study in southeastern Michigan. Respondent and family history data on parental smoking and depression were analyzed using the biometric modeling method for family data, which Rhee and colleagues (Journal of Child Psychology and Psychiatry and Allied Disciplines, 44, 612-636, 2003; Behavior Genetics, 34, 251-265, 2004) have shown to be valid more frequently than traditional prevalence analyses. Results of the biometric model fitting suggested that for ever smoking, the comorbidity with depression may be related to chance or a high liability threshold for smoking only. In contrast, a correlated liabilities model fit the data best for the comorbidity of depression with daily, heavy, and nicotine-dependent smoking. The familial correlations accounted for 73%-95% of the total variance shared between depression and these levels of smoking. These results differ from analyses of these data using a traditional prevalence approach, which found no evidence of shared familial liability. The conflicting findings of the studies that have examined the relationship between smoking and depression may be attributable to differences in definition of the disorders and the methods used to analyze them.

  17. The RISAP-study: a complex intervention in risk communication and shared decision-making in general practice

    DEFF Research Database (Denmark)

    Kirkegaard, Pia; Edwards, Adrian G K; Hansen, Bo

    2010-01-01

    decision satisfaction (Provider Decision Process Assessment Instrument). The patients will receive a questionnaire at baseline and after 3 and 6 months. It includes questions about adherence to chosen treatment (Morisky Compliance Scale), self-rated health (SF-12), enablement (Patient Enablement Instrument...... training are needed. Aim:1) to systematically develop, describe and evaluate a complex intervention comprising a training programme for GPs in risk communication and shared decision-making, 2) to evaluate the effect of the training programme on real-life consultations between GPs and patients with high......), and risk communication and decision-making effectiveness (COMRADE Scale). Prescriptions, contacts to the health services, and cholesterol level will be drawn from the registers.In each group, 12 consultations will be observed and tape-recorded. The patients from these 24 consultations will be interviewed...

  18. A PUBLIC PLATFORM FOR GEOSPATIAL DATA SHARING FOR DISASTER RISK MANAGEMENT

    Directory of Open Access Journals (Sweden)

    S. Balbo

    2014-01-01

    This paper presents a case study scenario of setting up a Web platform based on GeoNode. It is a public platform called MASDAP and promoted by the Government of Malawi in order to support development of the country and build resilience against natural disasters. A substantial amount of geospatial data has already been collected about hydrogeological risk, as well as several other-disasters related information. Moreover this platform will help to ensure that the data created by a number of past or ongoing projects is maintained and that this information remains accessible and useful. An Integrated Flood Risk Management Plan for a river basin has already been included in the platform and other data from future disaster risk management projects will be added as well.

  19. Real-Time Optimal Flood Control Decision Making and Risk Propagation Under Multiple Uncertainties

    Science.gov (United States)

    Zhu, Feilin; Zhong, Ping-An; Sun, Yimeng; Yeh, William W.-G.

    2017-12-01

    Multiple uncertainties exist in the optimal flood control decision-making process, presenting risks involving flood control decisions. This paper defines the main steps in optimal flood control decision making that constitute the Forecast-Optimization-Decision Making (FODM) chain. We propose a framework for supporting optimal flood control decision making under multiple uncertainties and evaluate risk propagation along the FODM chain from a holistic perspective. To deal with uncertainties, we employ stochastic models at each link of the FODM chain. We generate synthetic ensemble flood forecasts via the martingale model of forecast evolution. We then establish a multiobjective stochastic programming with recourse model for optimal flood control operation. The Pareto front under uncertainty is derived via the constraint method coupled with a two-step process. We propose a novel SMAA-TOPSIS model for stochastic multicriteria decision making. Then we propose the risk assessment model, the risk of decision-making errors and rank uncertainty degree to quantify the risk propagation process along the FODM chain. We conduct numerical experiments to investigate the effects of flood forecast uncertainty on optimal flood control decision making and risk propagation. We apply the proposed methodology to a flood control system in the Daduhe River basin in China. The results indicate that the proposed method can provide valuable risk information in each link of the FODM chain and enable risk-informed decisions with higher reliability.

  20. Risk Taking and Optimal Contracts for Money Managers

    OpenAIRE

    Palomino, Frédéric; Prat, Andrea

    1999-01-01

    Recent empirical work suggests a strong connection between the incentives money managers are offered and their risk-taking behavior. We develop a general model of delegated portfolio management, with the feature that the agent can control the riskiness of the portfolio. This represents a departure from the existing literature on agency theory in that moral hazard is not only effort exertion but also risk taking behavior. The moral hazard problem with risk taking involves an incentive-compatib...

  1. Connecting the Dots: State Health Department Approaches to Addressing Shared Risk and Protective Factors Across Multiple Forms of Violence

    Science.gov (United States)

    Wilkins, Natalie; Myers, Lindsey; Kuehl, Tomei; Bauman, Alice; Hertz, Marci

    2018-01-01

    Violence takes many forms, including intimate partner violence, sexual violence, child abuse and neglect, bullying, suicidal behavior, and elder abuse and neglect. These forms of violence are interconnected and often share the same root causes. They can also co-occur together in families and communities and can happen at the same time or at different stages of life. Often, due to a variety of factors, separate, “siloed” approaches are used to address each form of violence. However, understanding and implementing approaches that prevent and address the overlapping root causes of violence (risk factors) and promote factors that increase the resilience of people and communities (protective factors) can help practitioners more effectively and efficiently use limited resources to prevent multiple forms of violence and save lives. This article presents approaches used by 2 state health departments, the Maryland Department of Health and Mental Hygiene and the Colorado Department of Public Health and Environment, to integrate a shared risk and protective factor approach into their violence prevention work and identifies key lessons learned that may serve to inform crosscutting violence prevention efforts in other states. PMID:29189502

  2. Connecting the Dots: State Health Department Approaches to Addressing Shared Risk and Protective Factors Across Multiple Forms of Violence.

    Science.gov (United States)

    Wilkins, Natalie; Myers, Lindsey; Kuehl, Tomei; Bauman, Alice; Hertz, Marci

    Violence takes many forms, including intimate partner violence, sexual violence, child abuse and neglect, bullying, suicidal behavior, and elder abuse and neglect. These forms of violence are interconnected and often share the same root causes. They can also co-occur together in families and communities and can happen at the same time or at different stages of life. Often, due to a variety of factors, separate, "siloed" approaches are used to address each form of violence. However, understanding and implementing approaches that prevent and address the overlapping root causes of violence (risk factors) and promote factors that increase the resilience of people and communities (protective factors) can help practitioners more effectively and efficiently use limited resources to prevent multiple forms of violence and save lives. This article presents approaches used by 2 state health departments, the Maryland Department of Health and Mental Hygiene and the Colorado Department of Public Health and Environment, to integrate a shared risk and protective factor approach into their violence prevention work and identifies key lessons learned that may serve to inform crosscutting violence prevention efforts in other states.

  3. Production sharing agreements

    International Nuclear Information System (INIS)

    1994-01-01

    This paper, which was presented at the Production Sharing Agreement seminar, discusses economic rent, negotiations, trends in fiscal system development, and concessionary systems. Production sharing contracts, risk service contracts, joint ventures and the global market are examined. (UK)

  4. A multi-scale energy demand model suggests sharing market risks with intelligent energy cooperatives

    NARCIS (Netherlands)

    G. Methenitis (Georgios); M. Kaisers (Michael); J.A. La Poutré (Han)

    2015-01-01

    textabstractIn this paper, we propose a multi-scale model of energy demand that is consistent with observations at a macro scale, in our use-case standard load profiles for (residential) electric loads. We employ the model to study incentives to assume the risk of volatile market prices for

  5. Risk assessment by client and case manager for shared decision making in outpatient forensic psychiatry

    NARCIS (Netherlands)

    van den Brink, Rob H. S.; Troquete, Nadine A. C.; Beintema, Harry; Mulder, Tamara; van Os, Titus W. D. P.; Schoevers, Robert A.; Wiersma, Durk

    2015-01-01

    Background: In outpatient forensic psychiatry, assessment of re-offending risk and treatment needs by case managers may be hampered by an incomplete view of client functioning. The client's appreciation of his own problem behaviour is not systematically used for these purposes. The current study

  6. Genetic sharing with cardiovascular disease risk factors and diabetes reveals novel bone mineral density loci

    NARCIS (Netherlands)

    S. Reppe (Sjur); Y. Wang (Yunpeng); W.K. Thompson (Wesley K.); L.K. McEvoy (Linda K.); N.J. Schork (Nicholas); V. Zuber (Verena); M. Leblanc (Marissa); F. Bettella (Francesco); I.G. Mills (Ian G.); R.S. Desikan (Rahul S.); S. Djurovic (Srdjan); K.M. Gautvik (Kaare); A.M. Dale (Anders); O.A. Andreassen (Ole); K. Estrada Gil (Karol); U. Styrkarsdottir (Unnur); E. Evangelou (Evangelos); Y.-H. Hsu (Yi-Hsiang); E.L. Duncan (Emma); E.E. Ntzani (Evangelia); L. Oei (Ling); O.M.E. Albagha (Omar M.); N. Amin (Najaf); J.P. Kemp (John); D.L. Koller (Daniel); G. Li (Guo); C.-T. Liu (Ching-Ti); R.L. Minster (Ryan); A. Moayyeri (Alireza); L. Vandenput (Liesbeth); D. Willner (Dana); S.-M. Xiao (Su-Mei); L.M. Yerges-Armstrong (Laura); H.-F. Zheng (Hou-Feng); N. Alonso (Nerea); J. Eriksson (Joel); C.M. Kammerer (Candace); S. Kaptoge (Stephen); P.J. Leo (Paul); G. Thorleifsson (Gudmar); S.G. Wilson (Scott); J.F. Wilson (James F); V. Aalto (Ville); M. Alen (Markku); A.K. Aragaki (Aaron); T. Aspelund (Thor); J.R. Center (Jacqueline); Z. Dailiana (Zoe); C. Duggan; M. Garcia (Melissa); N. Garcia-Giralt (Natàlia); S. Giroux (Sylvie); G. Hallmans (Göran); L.J. Hocking (Lynne); L.B. Husted (Lise Bjerre); K. Jameson (Karen); R. Khusainova (Rita); G.S. Kim (Ghi Su); C. Kooperberg (Charles); T. Koromila (Theodora); M. Kruk (Marcin); M. Laaksonen (Marika); A.Z. Lacroix (Andrea Z.); S.H. Lee (Seung Hun); P.C. Leung (Ping C.); J.R. Lewis (Joshua); L. Masi (Laura); S. Mencej-Bedrac (Simona); T.V. Nguyen (Tuan); X. Nogues (Xavier); M.S. Patel (Millan); J. Prezelj (Janez); L.M. Rose (Lynda); S. Scollen (Serena); K. Siggeirsdottir (Kristin); G.D. Smith; O. Svensson (Olle); S. Trompet (Stella); O. Trummer (Olivia); N.M. van Schoor (Natasja); J. Woo (Jean); K. Zhu (Kun); S. Balcells (Susana); M.L. Brandi; B.M. Buckley (Brendan M.); S. Cheng (Sulin); C. Christiansen; C. Cooper (Charles); G.V. Dedoussis (George); I. Ford (Ian); M. Frost (Morten); D. Goltzman (David); J. González-Macías (Jesús); M. Kähönen (Mika); M. Karlsson (Magnus); E.K. Khusnutdinova (Elza); J.-M. Koh (Jung-Min); P. Kollia (Panagoula); B.L. Langdahl (Bente); W.D. Leslie (William D.); P. Lips (Paul); O. Ljunggren (Östen); R. Lorenc (Roman); J. Marc (Janja); D. Mellström (Dan); B. Obermayer-Pietsch (Barbara); D. Olmos (David); U. Pettersson-Kymmer (Ulrika); D.M. Reid (David); J.A. Riancho (José); P.M. Ridker (Paul); M.F. Rousseau (Francois); P.E. Slagboom (Eline); N.L.S. Tang (Nelson L.S.); R. Urreizti (Roser); W. Van Hul (Wim); J. Viikari (Jorma); M.T. Zarrabeitia (María); Y.S. Aulchenko (Yurii); M.C. Castaño Betancourt (Martha); E. Grundberg (Elin); L. Herrera (Lizbeth); T. Ingvarsson (Torvaldur); H. Johannsdottir (Hrefna); T. Kwan (Tony); R. Li (Rui); R.N. Luben (Robert); M.C. Medina-Gomez (Carolina); S.T. Palsson (Stefan Th); J.I. Rotter (Jerome I.); G. Sigurdsson (Gunnar); J.B.J. van Meurs (Joyce); D.J. Verlaan (Dominique); F.M. Williams (Frances); A.R. Wood (Andrew); Y. Zhou (Yanhua); T. Pastinen (Tomi); S. Raychaudhuri (Soumya); J.A. Cauley (Jane); D.I. Chasman (Daniel); G.R. Clark (Graeme); S.R. Cummings (Steven R.); P. Danoy (Patrick); E.M. Dennison (Elaine); R. Eastell (Richard); J.A. Eisman (John); V. Gudnason (Vilmundur); A. Hofman (Albert); R.D. Jackson (Rebecca); G. Jones (Graeme); J.W. Jukema (Jan Wouter); K.T. Khaw; T. Lehtimäki (Terho); Y. Liu (YongMei); M. Lorentzon (Mattias); E. McCloskey (Eugene); B.D. Mitchell (Braxton); K. Nandakumar (Kannabiran); G.C. Nicholson (Geoffrey); B.A. Oostra (Ben); M. Peacock (Munro); H.A.P. Pols (Huib); R.L. Prince (Richard); O. Raitakari (Olli); I.R. Reid (Ian); J. Robbins (John); P.N. Sambrook (Philip); P.C. Sham (Pak Chung); A.R. Shuldiner (Alan); F.A. Tylavsky (Frances); C.M. van Duijn (Cornelia); N.J. Wareham (Nicholas J.); L.A. Cupples (Adrienne); M.J. Econs (Michael); D.M. Evans (David); T.B. Harris (Tamara B.); A.W.C. Kung (Annie Wai Chee); B.M. Psaty (Bruce); J. Reeve (Jonathan); T.D. Spector (Timothy); E.A. Streeten (Elizabeth); M.C. Zillikens (Carola); U. Thorsteinsdottir (Unnur); C. Ohlsson (Claes); D. Karasik (David); J.B. Richards (Brent); M.A. Brown (Matthew); J-A. Zwart (John-Anker); A.G. Uitterlinden (André); S.H. Ralston (Stuart); J.P.A. Ioannidis (John P.A.); D.P. Kiel (Douglas P.); F. Rivadeneira Ramirez (Fernando)

    2015-01-01

    textabstractBone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown.

  7. Consolidating the shared area of investigation between planning theory, risk theory and ethical inquiry

    NARCIS (Netherlands)

    Basta, C.

    2012-01-01

    Although it is perhaps the most prominent interdisciplinary theme to have emerged in the past decades, in the domain of planning studies the prevention of technological risks has only recently started the pathway towards a rigorous theoretical definition (Boholm and Lofsted 2004; Hayden Lesbirel and

  8. Individual and shared effects of social environment and polygenic risk scores on adolescent body mass index.

    Science.gov (United States)

    Coleman, Jonathan R I; Krapohl, Eva; Eley, Thalia C; Breen, Gerome

    2018-04-20

    Juvenile obesity is associated with adverse health outcomes. Understanding genetic and environmental influences on body mass index (BMI) during adolescence could inform interventions. We investigated independent and interactive effects of parenting, socioeconomic status (SES) and polygenic risk on BMI pre-adolescence, and on the rate of change in BMI across adolescence. Genome-wide genotype data, BMI and child perceptions of parental warmth and punitive discipline were available at 11 years old, and parental SES was available from birth on 3,414 unrelated participants. Linear models were used to test the effects of social environment and polygenic risk on pre-adolescent BMI. Change in BMI across adolescence was assessed in a subset (N = 1943). Sex-specific effects were assessed. Higher genetic risk was associated with increased BMI pre-adolescence and across adolescence (p parenting was not significantly associated with either phenotype, but lower SES was associated with increased BMI pre-adolescence. No interactions passed correction for multiple testing. Polygenic risk scores from adult GWAS meta-analyses are associated with BMI in juveniles, suggesting a stable genetic component. Pre-adolescent BMI was associated with social environment, but parental style has, at most, a small effect.

  9. Cost-optimal power system extension under flow-based market coupling and high shares of photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Hagspiel, Simeon; Jaegemann, Cosima; Lindenberger, Dietmar [Koeln Univ. (Germany). Inst. of Energy Economics; Cherevatskiy, Stanislav; Troester, Eckehard; Brown, Tom [Energynautics GmbH, Langen (Germany)

    2012-07-01

    Electricity market models, implemented as dynamic programming problems, have been applied widely to identify possible pathways towards a cost-optimal and low carbon electricity system. However, the joint optimization of generation and transmission remains challenging, mainly due to the fact that different characteristics and rules apply to commercial and physical exchanges of electricity in meshed networks. This paper presents a methodology that allows to optimize power generation and transmission infrastructures jointly through an iterative approach based on power transfer distribution factors (PTDFs). As PTDFs are linear representations of the physical load flow equations, they can be implemented in a linear programming environment suitable for large scale problems such as the European power system. The algorithm iteratively updates PTDFs when grid infrastructures are modified due to cost-optimal extension and thus yields an optimal solution with a consistent representation of physical load flows. The method is demonstrated on a simplified three-node model where it is found to be stable and convergent. It is then scaled to the European level in order to find the optimal power system infrastructure development under the prescription of strongly decreasing CO{sub 2} emissions in Europe until 2050 with a specific focus on photovoltaic (PV) power. (orig.)

  10. Time-explicit methods for joint economical and geological risk mitigation in production optimization

    DEFF Research Database (Denmark)

    Christiansen, Lasse Hjuler; Capolei, Andrea; Jørgensen, John Bagterp

    2016-01-01

    Real-life applications of production optimization face challenges of risks related to unpredictable fluctuations in oil prices and sparse geological data. Consequently, operating companies are reluctant to adopt model-based production optimization into their operations. Conventional production...... of mitigating economical and geological risks. As opposed to conventional strategies that focus on a single long-term objective, TE methods seek to reduce risks and promote returns over the entire reservoir life by optimization of a given ensemble-based geological risk measure over time. By explicit involvement...... of time, economical risks are implicitly addressed by balancing short-term and long-term objectives throughout the reservoir life. Open-loop simulations of a two-phase synthetic reservoir demonstrate that TE methods may significantly improve short-term risk measures such as expected return, standard...

  11. DC Voltage Control and Power-Sharing of Multi-Terminal DC Grids Based on Optimal DC Power Flow and Flexible Voltage Droop Strategy

    Directory of Open Access Journals (Sweden)

    F. Azma

    2015-06-01

    Full Text Available This paper develops an effective control framework for DC voltage control and power-sharing of multi-terminal DC (MTDC grids based on an optimal power flow (OPF procedure and the voltage-droop control. In the proposed approach, an OPF algorithm is executed at the secondary level to find optimal reference of DC voltages and active powers of all voltage-regulating converters. Then, the voltage droop characteristics of voltage-regulating converters, at the primary level, are tuned based on the OPF results such that the operating point of the MTDC grid lies on the voltage droop characteristics. Consequently, the optimally-tuned voltage droop controller leads to the optimal operation of the MTDC grid. In case of variation in load or generation of the grid, a new stable operating point is achieved based on the voltage droop characteristics. By execution of a new OPF, the voltage droop characteristics are re-tuned for optimal operation of the MTDC grid after the occurrence of the load or generation variations. The results of simulation on a grid inspired by CIGRE B4 DC grid test system demonstrate efficient grid performance under the proposed control strategy.

  12. On the optimal design of risk retention in securitisation

    Directory of Open Access Journals (Sweden)

    Metin Kaptan

    2011-09-01

    Full Text Available This paper examines the optimal design of retention in securitisation, in order to maximize welfare of screening per unit of retention, assuming that screening is costly and that the bank intends to securitise its loans. In contrast to the focus of previous literature on tranche retention, we deviate from the constitutional mechanisms of tranche retention to present a pareto-optimal method of tranche retention. Unlike the current ad-hoc-regulations, we derive the optimal design of retention from a utility maximization problem. We show that the level of retention per tranche should be dependent on the rate of credit default, i.e. the higher the rate of default, the higher the optimal rate of retention required to provide an incentive to screen carefully. From this approach, it follows that the rate of retention per tranche should be higher, the higher the position within the ranking order of subordination. Accordingly, the efficiency of tranche retention can be enhanced, reducing the level of retention required to maintain a given level of screening-effort. This retention design entails a recovery of the bank’s equity capital, thereby increasing liquidity and lending capacities.

  13. Risk-based optimization of pipe inspections in large underground networks with imprecise information

    International Nuclear Information System (INIS)

    Mancuso, A.; Compare, M.; Salo, A.; Zio, E.; Laakso, T.

    2016-01-01

    In this paper, we present a novel risk-based methodology for optimizing the inspections of large underground infrastructure networks in the presence of incomplete information about the network features and parameters. The methodology employs Multi Attribute Value Theory to assess the risk of each pipe in the network, whereafter the optimal inspection campaign is built with Portfolio Decision Analysis (PDA). Specifically, Robust Portfolio Modeling (RPM) is employed to identify Pareto-optimal portfolios of pipe inspections. The proposed methodology is illustrated by reporting a real case study on the large-scale maintenance optimization of the sewerage network in Espoo, Finland. - Highlights: • Risk-based approach to optimize pipe inspections on large underground networks. • Reasonable computational effort to select efficient inspection portfolios. • Possibility to accommodate imprecise expert information. • Feasibility of the approach shown by Espoo water system case study.

  14. Abundance in Capital: Global Risk Sharing and Insurance in a Changing Financial Environment

    Science.gov (United States)

    Michel, Gero; Schaper, Christopher

    2014-05-01

    Insurance has played a viable role in the hedging of homeowners and commercial risks around the world. Countries that have significant penetration in insurance have in addition performed better after large regional or over-regional catastrophic losses. Insurance has hence increased the resilience of western societies. This is opposed to emerging or developing markets with low insurance penetration which have suffered significant drawbacks in their development after large catastrophic events. Examples include the recent Typhoon(s) in the Philippines and the 2010 Haiti earthquake. This presentation will provide insights into the opportunities, views and risk management features a global reinsurance company must assume in order to hedge and mitigate risk across the world. During the past year, an unprecedented amount of new capital has been entering the insurance market, looking for profitable investments outside the much wider capital market. Catastrophe insurance is seen as a valuable alternative to investing in assets that that have shown low returns and high correlation in the recent financial meltdown. The new capital is mostly deployed - or competing with already deployed capital - in the US where insurance penetration is already high. This is opposed to more than half of the world including all developing and most emerging countries which have low insurance penetration and often lack infrastructure hindering new capital to be deployed effectively. What is needed to overcome this obvious deficiency in capital supply and demand? One reason why it is difficult to deploy capital in developing countries is the lack of available exposure information and catastrophe models. This presentation sheds light on the potential science needs of our market and gives an overview of what is being done at Montpelier, a global reinsurance company, to understand catastrophe risk around the globe.

  15. Spatial Optimization of Future Urban Development with Regards to Climate Risk and Sustainability Objectives.

    Science.gov (United States)

    Caparros-Midwood, Daniel; Barr, Stuart; Dawson, Richard

    2017-11-01

    Future development in cities needs to manage increasing populations, climate-related risks, and sustainable development objectives such as reducing greenhouse gas emissions. Planners therefore face a challenge of multidimensional, spatial optimization in order to balance potential tradeoffs and maximize synergies between risks and other objectives. To address this, a spatial optimization framework has been developed. This uses a spatially implemented genetic algorithm to generate a set of Pareto-optimal results that provide planners with the best set of trade-off spatial plans for six risk and sustainability objectives: (i) minimize heat risks, (ii) minimize flooding risks, (iii) minimize transport travel costs to minimize associated emissions, (iv) maximize brownfield development, (v) minimize urban sprawl, and (vi) prevent development of greenspace. The framework is applied to Greater London (U.K.) and shown to generate spatial development strategies that are optimal for specific objectives and differ significantly from the existing development strategies. In addition, the analysis reveals tradeoffs between different risks as well as between risk and sustainability objectives. While increases in heat or flood risk can be avoided, there are no strategies that do not increase at least one of these. Tradeoffs between risk and other sustainability objectives can be more severe, for example, minimizing heat risk is only possible if future development is allowed to sprawl significantly. The results highlight the importance of spatial structure in modulating risks and other sustainability objectives. However, not all planning objectives are suited to quantified optimization and so the results should form part of an evidence base to improve the delivery of risk and sustainability management in future urban development. © 2017 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

  16. Application of a general risk management model to portfolio optimization problems with elliptical distributed returns for risk neutral and risk averse decision makers.

    NARCIS (Netherlands)

    B. Kaynar; S.I. Birbil (Ilker); J.B.G. Frenk (Hans)

    2007-01-01

    textabstractWe discuss a class of risk measures for portfolio optimization with linear loss functions, where the random returns of financial instruments have a multivariate elliptical distribution. Under this setting we pay special attention to two risk measures, Value-at-Risk and

  17. Importance measures and genetic algorithms for designing a risk-informed optimally balanced system

    International Nuclear Information System (INIS)

    Zio, Enrico; Podofillini, Luca

    2007-01-01

    This paper deals with the use of importance measures for the risk-informed optimization of system design and management. An optimization approach is presented in which the information provided by the importance measures is incorporated in the formulation of a multi-objective optimization problem to drive the design towards a solution which, besides being optimal from the points of view of economics and safety, is also 'balanced' in the sense that all components have similar importance values. The approach allows identifying design systems without bottlenecks or unnecessarily high-performing components and with test/maintenance activities calibrated according to the components' importance ranking. The approach is tested at first against a multi-state system design optimization problem in which off-the-shelf components have to be properly allocated. Then, the more realistic problem of risk-informed optimization of the technical specifications of a safety system of a nuclear power plant is addressed

  18. Minimal investment risk of a portfolio optimization problem with budget and investment concentration constraints

    Science.gov (United States)

    Shinzato, Takashi

    2017-02-01

    In the present paper, the minimal investment risk for a portfolio optimization problem with imposed budget and investment concentration constraints is considered using replica analysis. Since the minimal investment risk is influenced by the investment concentration constraint (as well as the budget constraint), it is intuitive that the minimal investment risk for the problem with an investment concentration constraint can be larger than that without the constraint (that is, with only the budget constraint). Moreover, a numerical experiment shows the effectiveness of our proposed analysis. In contrast, the standard operations research approach failed to identify accurately the minimal investment risk of the portfolio optimization problem.

  19. Affect, risk perception and future optimism after the tsunami disaster

    Directory of Open Access Journals (Sweden)

    Daniel Vastfjall

    2008-01-01

    Full Text Available Environmental events such as natural disasters may influence the public's affective reactions and decisions. Shortly after the 2004 Tsunami disaster we assessed how affect elicited by thinking about this disaster influenced risk perceptions and future time perspective in Swedish undergraduates not directly affected by the disaster. An experimental manipulation was used to increase the salience of affect associated with the disaster. In Study 1 we found that participants reminded about the tsunami had a sense that their life was more finite and included fewer opportunities than participants in the control condition (not reminded about the tsunami. In Study 2 we found similar effects for risk perceptions. In addition, we showed that manipulations of ease-of-thought influenced the extent to which affect influenced these risk perceptions, with greater ease of thoughts being associated with greater perceived risks.

  20. A method for minimum risk portfolio optimization under hybrid uncertainty

    Science.gov (United States)

    Egorova, Yu E.; Yazenin, A. V.

    2018-03-01

    In this paper, we investigate a minimum risk portfolio model under hybrid uncertainty when the profitability of financial assets is described by fuzzy random variables. According to Feng, the variance of a portfolio is defined as a crisp value. To aggregate fuzzy information the weakest (drastic) t-norm is used. We construct an equivalent stochastic problem of the minimum risk portfolio model and specify the stochastic penalty method for solving it.

  1. Optimal Premium Pricing for a Heterogeneous Portfolio of Insurance Risks

    OpenAIRE

    Pantelous, Athanasios A.; Frangos, Nicholas E.; Zimbidis, Alexandros A.

    2009-01-01

    The paper revisits the classical problem of premium rating within a heterogeneous portfolio of insurance risks using a continuous stochastic control framework. The portfolio is divided into several classes where each class interacts with the others. The risks are modelled dynamically by the means of a Brownian motion. This dynamic approach is also transferred to the design of the premium process. The premium is not constant but equals the drift of the Brownian motion plus a controlled percent...

  2. [Radiotherapy quality and risk manager role optimization in 2017].

    Science.gov (United States)

    Ponsard, N; Brusadin, G; Schick, U

    2017-10-01

    The quality and risk manager works in a regulated framework, which delimits its missions. Nevertheless, the variety among the centers generates heterogeneous situations regarding the positioning and the range of action. A well-defined framework is needed in order to ratify the legitimacy and the recognition of quality and risk manager's main function. Copyright © 2017 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

  3. Portfolio management using value at risk: A comparison between genetic algorithms and particle swarm optimization

    NARCIS (Netherlands)

    V.A.F. Dallagnol (V. A F); J.H. van den Berg (Jan); L. Mous (Lonneke)

    2009-01-01

    textabstractIn this paper, it is shown a comparison of the application of particle swarm optimization and genetic algorithms to portfolio management, in a constrained portfolio optimization problem where no short sales are allowed. The objective function to be minimized is the value at risk

  4. Optimal taxation and debt with uninsurable risks to human capital accumulation

    OpenAIRE

    Gottardi, Piero; Kajii, Atsushi; Nakajima, Tomoyuki

    2015-01-01

    We consider an economy where individuals face uninsurable risks to their human capital accumulation, and analyze the optimal level of linear taxes on capital and labor income together with the optimal path of government debt. We show that in the presence of such risks it is beneficial to tax both labor and capital and to issue public debt. We also assess the quantitative importance of these findings, and show that the benefits of government debt and capital taxes both increase with the magnit...

  5. Integrated testing strategies can be optimal for chemical risk classification.

    Science.gov (United States)

    Raseta, Marko; Pitchford, Jon; Cussens, James; Doe, John

    2017-08-01

    There is an urgent need to refine strategies for testing the safety of chemical compounds. This need arises both from the financial and ethical costs of animal tests, but also from the opportunities presented by new in-vitro and in-silico alternatives. Here we explore the mathematical theory underpinning the formulation of optimal testing strategies in toxicology. We show how the costs and imprecisions of the various tests, and the variability in exposures and responses of individuals, can be assembled rationally to form a Markov Decision Problem. We compute the corresponding optimal policies using well developed theory based on Dynamic Programming, thereby identifying and overcoming some methodological and logical inconsistencies which may exist in the current toxicological testing. By illustrating our methods for two simple but readily generalisable examples we show how so-called integrated testing strategies, where information of different precisions from different sources is combined and where different initial test outcomes lead to different sets of future tests, can arise naturally as optimal policies. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Innovations in optimizing mitigation and pipeline risk management for natural gas and hazardous liquid systems

    Energy Technology Data Exchange (ETDEWEB)

    Gloven, Michael P; Hendren, Elaine S; Zeller, Sherri A; Ramirez, Pete V [Bass-Trigon (United States)

    2003-07-01

    Pipeline risk management has been stimulated by pipeline ruptures throughout the world. This paper explores risk management and mitigation strategies for minimizing consequences from pipeline releases, and optimizing financial resources in response or in prevention of these events. More specifically, it examines private sector innovations which optimize mitigation activities in combination with public sector programs such as regulations and standards (i.e., ASME B31.S, API 1160). The mitigation of risk involves the implementation of measures to reduce the frequency of failure, the severity of consequences, or both these attributes of risk. A wide variety of risk mitigation measures are available to pipeline operators. Given the diversity of mitigation measures available, this paper proposes a framework that can assist operating companies in selecting risk mitigation strategies based on risk results, mitigation costs and benefits. (author)

  7. A methodological model to assist in the optimization and risk management of mining investment decisions

    International Nuclear Information System (INIS)

    Botin, Jose A; Guzman, Ronald R; Smith, Martin L

    2011-01-01

    Identifying, quantifying, and minimizing technical risks associated with investment decisions is a key challenge for mineral industry decision makers and investors. However, risk analysis in most bankable mine feasibility studies are based on the stochastic modeling of project N et Present Value (NPV)which, in most cases, fails to provide decision makers with a truly comprehensive analysis of risks associated with technical and management uncertainty and, as a result, are of little use for risk management and project optimization. This paper presents a value-chain risk management approach where project risk is evaluated for each step of the project life cycle, from exploration to mine closure, and risk management is performed as a part of a stepwise value-added optimization process.

  8. Risk management and portfolio optimization in volatile energy markets

    International Nuclear Information System (INIS)

    El-Ramly, Z.

    2002-01-01

    Characteristics of competitive markets, especially as they relate to the deregulated electricity market, are explained in terms of pricing, contracting, operation, the types of physical and financial products and services, and procurement decisions. The importance of market monitoring, organization monitoring and analysis, the understanding of market dynamics and the impacts of market data, price volatility and risk, and how they affect and are used in decision making are reviewed in some detail. A variety of proprietary task-specific power tools such as the ZE Data Manager, ZE XML Importer, ZE Market Analyzer, ZE Forward Price Models, ZE Trade Manager, and ZE Credit Risk Manager are described, and their application demonstrated. The inter-relatedness of price volatility and risk is discussed, along with the need to understand, monitor, quantify and deal with it on a continuous basis

  9. Achieving involvement: process outcomes from a cluster randomized trial of shared decision making skill development and use of risk communication aids in general practice.

    NARCIS (Netherlands)

    Elwyn, G.; Edwards, A.; Hood, K.; Robling, M.; Atwell, C.; Russell, I.; Wensing, M.J.P.; Grol, R.P.T.M.

    2004-01-01

    BACKGROUND: A consulting method known as 'shared decision making' (SDM) has been described and operationalized in terms of several 'competences'. One of these competences concerns the discussion of the risks and benefits of treatment or care options-'risk communication'. Few data exist on

  10. Can't get no satisfaction? Will pay for performance help?: toward an economic framework for understanding performance-based risk-sharing agreements for innovative medical products.

    Science.gov (United States)

    Towse, Adrian; Garrison, Louis P

    2010-01-01

    This article examines performance-based risk-sharing agreements for pharmaceuticals from a theoretical economic perspective. We position these agreements as a form of coverage with evidence development. New performance-based risk sharing could produce a more efficient market equilibrium, achieved by adjustment of the price post-launch to reflect outcomes combined with a new approach to the post-launch costs of evidence collection. For this to happen, the party best able to manage or to bear specific risks must do so. Willingness to bear risk will depend not only on ability to manage it, but on the degree of risk aversion. We identify three related frameworks that provide relevant insights: value of information, real option theory and money-back guarantees. We identify four categories of risk sharing: budget impact, price discounting, outcomes uncertainty and subgroup uncertainty. We conclude that a value of information/real option framework is likely to be the most helpful approach for understanding the costs and benefits of risk sharing. There are a number of factors that are likely to be crucial in determining if performance-based or risk-sharing agreements are efficient and likely to become more important in the future: (i) the cost and practicality of post-launch evidence collection relative to pre-launch; (ii) the feasibility of coverage with evidence development without a pre-agreed contract as to how the evidence will be used to adjust price, revenues or use, in which uncertainty around the pay-off to additional research will reduce the incentive for the manufacturer to collect the information; (iii) the difficulty of writing and policing risk-sharing agreements; (iv) the degree of risk aversion (and therefore opportunity to trade) on the part of payers and manufacturers; and (v) the extent of transferability of data from one country setting to another to support coverage with evidence development in a risk-sharing framework. There is no doubt that

  11. Functional variants in the LRRK2 gene confer shared effects on risk for Crohn's disease and Parkinson's disease.

    Science.gov (United States)

    Hui, Ken Y; Fernandez-Hernandez, Heriberto; Hu, Jianzhong; Schaffner, Adam; Pankratz, Nathan; Hsu, Nai-Yun; Chuang, Ling-Shiang; Carmi, Shai; Villaverde, Nicole; Li, Xianting; Rivas, Manual; Levine, Adam P; Bao, Xiuliang; Labrias, Philippe R; Haritunians, Talin; Ruane, Darren; Gettler, Kyle; Chen, Ernie; Li, Dalin; Schiff, Elena R; Pontikos, Nikolas; Barzilai, Nir; Brant, Steven R; Bressman, Susan; Cheifetz, Adam S; Clark, Lorraine N; Daly, Mark J; Desnick, Robert J; Duerr, Richard H; Katz, Seymour; Lencz, Todd; Myers, Richard H; Ostrer, Harry; Ozelius, Laurie; Payami, Haydeh; Peter, Yakov; Rioux, John D; Segal, Anthony W; Scott, William K; Silverberg, Mark S; Vance, Jeffery M; Ubarretxena-Belandia, Iban; Foroud, Tatiana; Atzmon, Gil; Pe'er, Itsik; Ioannou, Yiannis; McGovern, Dermot P B; Yue, Zhenyu; Schadt, Eric E; Cho, Judy H; Peter, Inga

    2018-01-10

    Crohn's disease (CD), a form of inflammatory bowel disease, has a higher prevalence in Ashkenazi Jewish than in non-Jewish European populations. To define the role of nonsynonymous mutations, we performed exome sequencing of Ashkenazi Jewish patients with CD, followed by array-based genotyping and association analysis in 2066 CD cases and 3633 healthy controls. We detected association signals in the LRRK2 gene that conferred risk for CD (N2081D variant, P = 9.5 × 10 -10 ) or protection from CD (N551K variant, tagging R1398H-associated haplotype, P = 3.3 × 10 -8 ). These variants affected CD age of onset, disease location, LRRK2 activity, and autophagy. Bayesian network analysis of CD patient intestinal tissue further implicated LRRK2 in CD pathogenesis. Analysis of the extended LRRK2 locus in 24,570 CD cases, patients with Parkinson's disease (PD), and healthy controls revealed extensive pleiotropy, with shared genetic effects between CD and PD in both Ashkenazi Jewish and non-Jewish cohorts. The LRRK2 N2081D CD risk allele is located in the same kinase domain as G2019S, a mutation that is the major genetic cause of familial and sporadic PD. Like the G2019S mutation, the N2081D variant was associated with increased kinase activity, whereas neither N551K nor R1398H variants on the protective haplotype altered kinase activity. We also confirmed that R1398H, but not N551K, increased guanosine triphosphate binding and hydrolyzing enzyme (GTPase) activity, thereby deactivating LRRK2. The presence of shared LRRK2 alleles in CD and PD provides refined insight into disease mechanisms and may have major implications for the treatment of these two seemingly unrelated diseases. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  12. Optimal portfolio selection for cashflows with bounded capital at risk

    NARCIS (Netherlands)

    Vyncke, D.; Goovaerts, M.J.; Dhaene, J.L.M.; Vanduffel, S.

    2005-01-01

    We consider a continuous-time Markowitz type portfolio problem that consists of minimizing the discounted cost of a given cash-fl ow under the constraint of a restricted Capital at Risk. In a Black-Scholes setting, upper and lower bounds are obtained by means of simple analytical expressions that

  13. Optimization of agricultural field workability predictions for improved risk management

    Science.gov (United States)

    Risks introduced by weather variability are key considerations in agricultural production. The sensitivity of agriculture to weather variability is of special concern in the face of climate change. In particular, the availability of workable days is an important consideration in agricultural practic...

  14. Genetic Sharing with Cardiovascular Disease Risk Factors and Diabetes Reveals Novel Bone Mineral Density Loci.

    Directory of Open Access Journals (Sweden)

    Sjur Reppe

    Full Text Available Bone Mineral Density (BMD is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR method to identify single nucleotide polymorphisms (SNPs associated with BMD by leveraging cardiovascular disease (CVD associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD at conditional FDR < 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity.

  15. A Risk-Based Multi-Objective Optimization Concept for Early-Warning Monitoring Networks

    Science.gov (United States)

    Bode, F.; Loschko, M.; Nowak, W.

    2014-12-01

    Groundwater is a resource for drinking water and hence needs to be protected from contaminations. However, many well catchments include an inventory of known and unknown risk sources which cannot be eliminated, especially in urban regions. As matter of risk control, all these risk sources should be monitored. A one-to-one monitoring situation for each risk source would lead to a cost explosion and is even impossible for unknown risk sources. However, smart optimization concepts could help to find promising low-cost monitoring network designs.In this work we develop a concept to plan monitoring networks using multi-objective optimization. Our considered objectives are to maximize the probability of detecting all contaminations and the early warning time and to minimize the installation and operating costs of the monitoring network. A qualitative risk ranking is used to prioritize the known risk sources for monitoring. The unknown risk sources can neither be located nor ranked. Instead, we represent them by a virtual line of risk sources surrounding the production well.We classify risk sources into four different categories: severe, medium and tolerable for known risk sources and an extra category for the unknown ones. With that, early warning time and detection probability become individual objectives for each risk class. Thus, decision makers can identify monitoring networks which are valid for controlling the top risk sources, and evaluate the capabilities (or search for least-cost upgrade) to also cover moderate, tolerable and unknown risk sources. Monitoring networks which are valid for the remaining risk also cover all other risk sources but the early-warning time suffers.The data provided for the optimization algorithm are calculated in a preprocessing step by a flow and transport model. Uncertainties due to hydro(geo)logical phenomena are taken into account by Monte-Carlo simulations. To avoid numerical dispersion during the transport simulations we use the

  16. Measuring Treasury Bond Portfolio Risk and Portfolio Optimization with a Non-Gaussian Multivariate Model

    Science.gov (United States)

    Dong, Yijun

    The research about measuring the risk of a bond portfolio and the portfolio optimization was relatively rare previously, because the risk factors of bond portfolios are not very volatile. However, this condition has changed recently. The 2008 financial crisis brought high volatility to the risk factors and the related bond securities, even if the highly rated U.S. treasury bonds. Moreover, the risk factors of bond portfolios show properties of fat-tailness and asymmetry like risk factors of equity portfolios. Therefore, we need to use advanced techniques to measure and manage risk of bond portfolios. In our paper, we first apply autoregressive moving average generalized autoregressive conditional heteroscedasticity (ARMA-GARCH) model with multivariate normal tempered stable (MNTS) distribution innovations to predict risk factors of U.S. treasury bonds and statistically demonstrate that MNTS distribution has the ability to capture the properties of risk factors based on the goodness-of-fit tests. Then based on empirical evidence, we find that the VaR and AVaR estimated by assuming normal tempered stable distribution are more realistic and reliable than those estimated by assuming normal distribution, especially for the financial crisis period. Finally, we use the mean-risk portfolio optimization to minimize portfolios' potential risks. The empirical study indicates that the optimized bond portfolios have better risk-adjusted performances than the benchmark portfolios for some periods. Moreover, the optimized bond portfolios obtained by assuming normal tempered stable distribution have improved performances in comparison to the optimized bond portfolios obtained by assuming normal distribution.

  17. Identification of novel genetic risk loci in Maltese dogs with necrotizing meningoencephalitis and evidence of a shared genetic risk across toy dog breeds.

    Science.gov (United States)

    Schrauwen, Isabelle; Barber, Renee M; Schatzberg, Scott J; Siniard, Ashley L; Corneveaux, Jason J; Porter, Brian F; Vernau, Karen M; Keesler, Rebekah I; Matiasek, Kaspar; Flegel, Thomas; Miller, Andrew D; Southard, Teresa; Mariani, Christopher L; Johnson, Gayle C; Huentelman, Matthew J

    2014-01-01

    Necrotizing meningoencephalitis (NME) affects toy and small breed dogs causing progressive, often fatal, inflammation and necrosis in the brain. Genetic risk loci for NME previously were identified in pug dogs, particularly associated with the dog leukocyte antigen (DLA) class II complex on chromosome 12, but have not been investigated in other susceptible breeds. We sought to evaluate Maltese and Chihuahua dogs, in addition to pug dogs, to identify novel or shared genetic risk factors for NME development. Genome-wide association testing of single nucleotide polymorphisms (SNPs) in Maltese dogs with NME identified 2 regions of genome-wide significance on chromosomes 4 (chr4:74522353T>A, p = 8.1×10-7) and 15 (chr15:53338796A>G, p = 1.5×10-7). Haplotype analysis and fine-mapping suggests that ILR7 and FBXW7, respectively, both important for regulation of immune system function, could be the underlying associated genes. Further evaluation of these regions and the previously identified DLA II locus across all three breeds, revealed an enrichment of nominal significant SNPs associated with chromosome 15 in pug dogs and DLA II in Maltese and Chihuahua dogs. Meta-analysis confirmed effect sizes the same direction in all three breeds for both the chromosome 15 and DLA II loci (p = 8.6×10-11 and p = 2.5×10-7, respectively). This suggests a shared genetic background exists between all breeds and confers susceptibility to NME, but effect sizes might be different among breeds. In conclusion, we identified the first genetic risk factors for NME development in the Maltese, chromosome 4 and chromosome 15, and provide evidence for a shared genetic risk between breeds associated with chromosome 15 and DLA II. Last, DLA II and IL7R both have been implicated in human inflammatory diseases of the central nervous system such as multiple sclerosis, suggesting that similar pharmacotherapeutic targets across species should be investigated.

  18. Identification of novel genetic risk loci in Maltese dogs with necrotizing meningoencephalitis and evidence of a shared genetic risk across toy dog breeds.

    Directory of Open Access Journals (Sweden)

    Isabelle Schrauwen

    Full Text Available Necrotizing meningoencephalitis (NME affects toy and small breed dogs causing progressive, often fatal, inflammation and necrosis in the brain. Genetic risk loci for NME previously were identified in pug dogs, particularly associated with the dog leukocyte antigen (DLA class II complex on chromosome 12, but have not been investigated in other susceptible breeds. We sought to evaluate Maltese and Chihuahua dogs, in addition to pug dogs, to identify novel or shared genetic risk factors for NME development. Genome-wide association testing of single nucleotide polymorphisms (SNPs in Maltese dogs with NME identified 2 regions of genome-wide significance on chromosomes 4 (chr4:74522353T>A, p = 8.1×10-7 and 15 (chr15:53338796A>G, p = 1.5×10-7. Haplotype analysis and fine-mapping suggests that ILR7 and FBXW7, respectively, both important for regulation of immune system function, could be the underlying associated genes. Further evaluation of these regions and the previously identified DLA II locus across all three breeds, revealed an enrichment of nominal significant SNPs associated with chromosome 15 in pug dogs and DLA II in Maltese and Chihuahua dogs. Meta-analysis confirmed effect sizes the same direction in all three breeds for both the chromosome 15 and DLA II loci (p = 8.6×10-11 and p = 2.5×10-7, respectively. This suggests a shared genetic background exists between all breeds and confers susceptibility to NME, but effect sizes might be different among breeds. In conclusion, we identified the first genetic risk factors for NME development in the Maltese, chromosome 4 and chromosome 15, and provide evidence for a shared genetic risk between breeds associated with chromosome 15 and DLA II. Last, DLA II and IL7R both have been implicated in human inflammatory diseases of the central nervous system such as multiple sclerosis, suggesting that similar pharmacotherapeutic targets across species should be investigated.

  19. Risk, Benefit, and Moderators of the Affect Heuristic in a Widespread Unlawful Activity: Evidence from a Survey of Unlawful File-Sharing Behavior.

    Science.gov (United States)

    Watson, Steven J; Zizzo, Daniel J; Fleming, Piers

    2017-06-01

    Increasing the perception of legal risk via publicized litigation and lobbying for copyright law enforcement has had limited success in reducing unlawful content sharing by the public. We consider the extent to which engaging in file sharing online is motivated by the perceived benefits of this activity as opposed to perceived legal risks. Moreover, we explore moderators of the relationship between perceived risk and perceived benefits; namely, trust in industry and legal regulators, and perceived online anonymity. We examine these questions via a large two-part survey of consumers of music (n = 658) and eBooks (n = 737). We find that perceptions of benefit, but not of legal risk, predict stated file-sharing behavior. An affect heuristic is employed: as perceived benefit increases, perceived risk falls. This relationship is increased under high regulator and industry trust (which actually increases perceived risk in this study) and low anonymity (which also increases perceived risk). We propose that, given the limited impact of perceived legal risk upon unlawful downloading, it would be better for the media industries to target enhancing the perceived benefit and availability of lawful alternatives. © 2016 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

  20. Optimizing the Management of High-Risk, Localized Prostate Cancer

    OpenAIRE

    Sundi, Debasish; Jeong, Byong Chang; Lee, Seung Bae; Han, Misop

    2012-01-01

    Prostate cancer has a high prevalence and a rising incidence in many parts of the world. Although many screen-detected prostate cancers may be indolent, prostate cancer remains a major contributor to mortality in men. Therefore, the appropriate diagnosis and treatment of localized prostate cancer with lethal potential are of great importance. High-risk, localized prostate cancer has multiple definitions. Treatment options that should be individualized to each patient include observation, radi...

  1. Constrained Inefficiency and Optimal Taxation with Uninsurable Risks

    OpenAIRE

    Gottardi, Piero; Kajii, Atsushi; Nakajima, Tomoyuki

    2010-01-01

    Should capital and labor be taxed, and if so how when individuals' labor and capital income are subject to uninsurable idiosyncratic risks? In a two period general equilibrium model with production, we first show that reducing investment is welfare improving if households are ho- mogeneous enough ex ante. On the other hand, when the degree of heterogeneity is sufficiently high a welfare improvement is achieved by increasing investment, even if the investment level is already higher than at th...

  2. Self-Harm and Suicide Attempts among High-Risk, Urban Youth in the U.S.: Shared and Unique Risk and Protective Factors

    Directory of Open Access Journals (Sweden)

    Angela C. Jones

    2012-01-01

    Full Text Available The extent to which self-harm and suicidal behavior overlap in community samples of vulnerable youth is not well known. Secondary analyses were conducted of the “linkages study” (N = 4,131, a cross-sectional survey of students enrolled in grades 7, 9, 11/12 in a high-risk community in the U.S. in 2004. Analyses were conducted to determine the risk and protective factors (i.e., academic grades, binge drinking, illicit drug use, weapon carrying, child maltreatment, social support, depression, impulsivity, self-efficacy, parental support, and parental monitoring associated with both self-harm and suicide attempt. Findings show that 7.5% of participants reported both self-harm and suicide attempt, 2.2% of participants reported suicide attempt only, and 12.4% of participants reported self-harm only. Shared risk factors for co-occurring self-harm and suicide attempt include depression, binge drinking, weapon carrying, child maltreatment, and impulsivity. There were also important differences by sex, grade level, and race/ethnicity that should be considered for future research. The findings show that there is significant overlap in the modifiable risk factors associated with self-harm and suicide attempt that can be targeted for future research and prevention strategies.

  3. Nuclear risk and optimal civil liability of the operator

    International Nuclear Information System (INIS)

    Schmitt, Andre; Spaeter, Sandrine

    2007-01-01

    The civil liability of nuclear operators are regulated by two sets of international Conventions. In particular, strict liability, limited financial responsibility and the obligation of providing financial guaranties are imposed to the nuclear operator by the Paris Convention and the Vienna Convention. Then national legislations are free to increase the financial cap of responsibility fixed by the international regimes. First we present the main elements of these Conventions. Then we focus on the impact of a modification in the amount of responsibility of the nuclear operator on his risk mitigation policy and on his financial condition. In particular we show that an increase of the cap beyond a given level determined by the model gives the operator some incentives to lessen the investment in prevention, contrary to what is expected. Besides, the impact of the preventive activities done by the firm on its financial constraint depends on the sensitivity of the risk distribution to the variation of the prevention level: The risk mitigation activities must be discussed with respect to the severity of the incidents and/or to the size of the nuclear park

  4. Using spatial information about recurrence risk for robust optimization of dose-painting prescription functions

    International Nuclear Information System (INIS)

    Bender, Edward T.

    2012-01-01

    Purpose: To develop a robust method for deriving dose-painting prescription functions using spatial information about the risk for disease recurrence. Methods: Spatial distributions of radiobiological model parameters are derived from distributions of recurrence risk after uniform irradiation. These model parameters are then used to derive optimal dose-painting prescription functions given a constant mean biologically effective dose. Results: An estimate for the optimal dose distribution can be derived based on spatial information about recurrence risk. Dose painting based on imaging markers that are moderately or poorly correlated with recurrence risk are predicted to potentially result in inferior disease control when compared the same mean biologically effective dose delivered uniformly. A robust optimization approach may partially mitigate this issue. Conclusions: The methods described here can be used to derive an estimate for a robust, patient-specific prescription function for use in dose painting. Two approximate scaling relationships were observed: First, the optimal choice for the maximum dose differential when using either a linear or two-compartment prescription function is proportional to R, where R is the Pearson correlation coefficient between a given imaging marker and recurrence risk after uniform irradiation. Second, the predicted maximum possible gain in tumor control probability for any robust optimization technique is nearly proportional to the square of R.

  5. HLA similarities indicate shared genetic risk in 21-hydroxylase autoantibody positive South African and United States Addison's disease.

    Science.gov (United States)

    Ross, I L; Babu, S; Armstrong, T; Zhang, L; Schatz, D; Pugliese, A; Eisenbarth, G; Baker Ii, P

    2014-10-01

    Genetic similarities between patients from the United States and South African (SA) Addison's Disease (AD) strengthen evidence for genetic association. SA-AD (n = 73), SA healthy controls (N = 78), and US-AD patients (N = 83) were genotyped for DQA1, DQB1, DRB1, and HLA-B alleles. Serum was tested for the quantity of 21OH-AA and IFNα-AA at the Barbara Davis Center. Although not as profound as in US-AD, in SA-AD 21OH-AA + subjects the predominantly associated risk haplotypes were DRB1*0301-DQB1*0201 (DR3), DRB1*04xx-DQB1*0302 (DR4), and the combined DR3/4 genotype. DQB1*0302 associated DRB1*04xx haplotypes conferred higher risk than those DRB1*04xx haplotypes associated with other DQB1 alleles. We found negative association in 21OH-AA + SA-AD for DQA1*0201-DQB1*0202 and DQA1*0101-DQB1*0501 vs SA controls, and positive association for DQA1*0401-DQB1*0402 vs US-AD. Apart from the class II DR3 haplotype, HLA-B8 did not have an independent effect; however together DR3 and HLA-B8 conferred the highest risk vs 21OH-AA negative SA-AD and SA-controls. HLA-B7 (often with DR4) conferred novel risk in 21OH-AA + SA-AD vs controls. This study represents the first comparison between South African and United States AD populations utilizing genotyping and serology performed at the same center. SA-AD and US-AD 21OH-AA + patients share common HLA risk haplotypes including DR4 (with HLA-B7) and DR3 (with HLA-B8), strengthening previously described HLA associations and implicating similar genetic etiology. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Rational risk-based decision support for drinking water well managers by optimized monitoring designs

    Science.gov (United States)

    Enzenhöfer, R.; Geiges, A.; Nowak, W.

    2011-12-01

    Advection-based well-head protection zones are commonly used to manage the contamination risk of drinking water wells. Considering the insufficient knowledge about hazards and transport properties within the catchment, current Water Safety Plans recommend that catchment managers and stakeholders know, control and monitor all possible hazards within the catchments and perform rational risk-based decisions. Our goal is to supply catchment managers with the required probabilistic risk information, and to generate tools that allow for optimal and rational allocation of resources between improved monitoring versus extended safety margins and risk mitigation measures. To support risk managers with the indispensable information, we address the epistemic uncertainty of advective-dispersive solute transport and well vulnerability (Enzenhoefer et al., 2011) within a stochastic simulation framework. Our framework can separate between uncertainty of contaminant location and actual dilution of peak concentrations by resolving heterogeneity with high-resolution Monte-Carlo simulation. To keep computational costs low, we solve the reverse temporal moment transport equation. Only in post-processing, we recover the time-dependent solute breakthrough curves and the deduced well vulnerability criteria from temporal moments by non-linear optimization. Our first step towards optimal risk management is optimal positioning of sampling locations and optimal choice of data types to reduce best the epistemic prediction uncertainty for well-head delineation, using the cross-bred Likelihood Uncertainty Estimator (CLUE, Leube et al., 2011) for optimal sampling design. Better monitoring leads to more reliable and realistic protection zones and thus helps catchment managers to better justify smaller, yet conservative safety margins. In order to allow an optimal choice in sampling strategies, we compare the trade-off in monitoring versus the delineation costs by accounting for ill

  7. Large portfolio risk management and optimal portfolio allocation with dynamic elliptical copulas

    Directory of Open Access Journals (Sweden)

    Jin Xisong

    2018-02-01

    Full Text Available Previous research has focused on the importance of modeling the multivariate distribution for optimal portfolio allocation and active risk management. However, existing dynamic models are not easily applied to high-dimensional problems due to the curse of dimensionality. In this paper, we extend the framework of the Dynamic Conditional Correlation/Equicorrelation and an extreme value approach into a series of Dynamic Conditional Elliptical Copulas. We investigate risk measures such as Value at Risk (VaR and Expected Shortfall (ES for passive portfolios and dynamic optimal portfolios using Mean-Variance and ES criteria for a sample of US stocks over a period of 10 years. Our results suggest that (1 Modeling the marginal distribution is important for dynamic high-dimensional multivariate models. (2 Neglecting the dynamic dependence in the copula causes over-aggressive risk management. (3 The DCC/DECO Gaussian copula and t-copula work very well for both VaR and ES. (4 Grouped t-copulas and t-copulas with dynamic degrees of freedom further match the fat tail. (5 Correctly modeling the dependence structure makes an improvement in portfolio optimization with respect to tail risk. (6 Models driven by multivariate t innovations with exogenously given degrees of freedom provide a flexible and applicable alternative for optimal portfolio risk management.

  8. Optimal Management of Supply Disruptions when Contracting with Unreliable, Risk-averse, Suppliers

    OpenAIRE

    Parlane, Sarah; Tsai, Ying-Yi

    2017-01-01

    This paper investigates the optimal management of supply disruptions by a manufacturer who uses order inflation and/or investments in process reliability when contracting two risk-averse suppliers. We consider that these investments can be subject to moral hazard. Technically we solve a newsvendor optimization problem using a random capacity model of disruption. In such a model, the order size does not affect the average production but impacts the probability of disruption. When investments a...

  9. Does training family physicians in shared decision making promote optimal use of antibiotics for acute respiratory infections? Study protocol of a pilot clustered randomised controlled trial

    Directory of Open Access Journals (Sweden)

    Côté Luc

    2007-11-01

    Full Text Available Abstract Background In North America, although it varies according to the specific type of acute respiratory infections (ARI, use of antibiotics is estimated to be well above the expected prevalence of bacterial infections. The objective of this pilot clustered randomized controlled trial (RCT is to assess the feasibility of a larger clustered RCT aiming at evaluating the impact of DECISION+, a continuing professional development (CPD program in shared decision making, on the optimal use of antibiotics in the context of ARI. Methods/design This pilot study is a cluster RCT conducted with family physicians from Family Medicine Groups (FMG in the Quebec City area, Canada. Participating FMG are randomised to an immediate DECISION+ group, a CPD program in shared decision making, (experimental group, or a delayed DECISION+ group (control group. Data collection involves recruiting five patients consulting for ARI per physician from both study groups before (Phase 1 and after (Phase 2 exposure of the experimental group to the DECISION+ program, and after exposure of the control group to the DECISION+ program (Phase 3. The primary outcome measures to assess the feasibility of a larger RCT include: 1 proportion of contacted FMG that agree to participate; 2 proportion of recruited physicians who participate in the DECISION+ program; 3 level of satisfaction of physicians regarding DECISION+; and 4 proportion of missing data in each data collection phase. Levels of agreement of the patient-physician dyad on the Decisional Conflict Scale and physicians' prescription profile for ARI are performed as secondary outcome measures. Discussion This study protocol is informative for researchers and clinicians interested in designing and/or conducting clustered RCT with FMG regarding training of physicians in shared decision making. Trial Registration ClinicalTrials.gov Identifier: NCT00354315

  10. Risk and Resilience in Pediatric Chronic Pain: Exploring the Protective Role of Optimism.

    Science.gov (United States)

    Cousins, Laura A; Cohen, Lindsey L; Venable, Claudia

    2015-10-01

    Fear of pain and pain catastrophizing are prominent risk factors for pediatric chronic pain-related maladjustment. Although resilience has largely been ignored in the pediatric pain literature, prior research suggests that optimism might benefit youth and can be learned. We applied an adult chronic pain risk-resilience model to examine the interplay of risk factors and optimism on functioning outcomes in youth with chronic pain. Participants included 58 children and adolescents (8-17 years) attending a chronic pain clinic and their parents. Participants completed measures of fear of pain, pain catastrophizing, optimism, disability, and quality of life. Consistent with the literature, pain intensity, fear of pain, and catastrophizing predicted functioning. Optimism was a unique predictor of quality of life, and optimism contributed to better functioning by minimizing pain-related fear and catastrophizing. Optimism might be protective and offset the negative influence of fear of pain and catastrophizing on pain-related functioning. © The Author 2014. Published by Oxford University Press on behalf of the Society of Pediatric Psychology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Optimal combined purchasing strategies for a risk-averse manufacturer under price uncertainty

    Directory of Open Access Journals (Sweden)

    Qiao Wu

    2015-09-01

    Full Text Available Purpose: The purpose of our paper is to analyze optimal purchasing strategies when a manufacturer can buy raw materials from a long-term contract supplier and a spot market under spot price uncertainty. Design/methodology/approach: This procurement model can be solved by using dynamic programming. First, we maximize the DM’s utility of the second period, obtaining the optimal contract quantity and spot quantity for the second period. Then, maximize the DM’s utility of both periods, obtaining the optimal purchasing strategy for the first period. We use a numerical method to compare the performance level of a pure spot sourcing strategy with that of a mixed strategy. Findings: Our results show that optimal purchasing strategies vary with the trend of contract prices. If the contract price falls, the total quantity purchased in period 1 will decrease in the degree of risk aversion. If the contract price increases, the total quantity purchased in period 1 will increase in the degree of risk aversion. The relationship between the optimal contract quantity and the degree of risk aversion depends on whether the expected spot price or the contract price is larger in period 2. Finally, we compare the performance levels between a combined strategy and a spot sourcing strategy. It shows that a combined strategy is optimal for a risk-averse buyer. Originality/value: It’s challenging to deal with a two-period procurement problem with risk consideration. We have obtained results of a two-period procurement problem with two sourcing options, namely contract procurement and spot purchases. Our model incorporates the buyer’s risk aversion factor and the change of contract prices, which are not addressed in early studies.

  12. Optimal Consumption and Investment under Time-Varying Relative Risk Aversion

    DEFF Research Database (Denmark)

    Steffensen, Mogens

    2011-01-01

    We consider the continuous time consumption-investment problem originally formalized and solved by Merton in case of constant relative risk aversion. We present a complete solution for the case where relative risk aversion with respect to consumption varies with time, having in mind an investor...... with age-dependent risk aversion. This provides a new motivation for life-cycle investment rules. We study the optimal consumption and investment rules, in particular in the case where the relative risk aversion with respect to consumption is increasing with age....

  13. Risk-Constrained Dynamic Programming for Optimal Mars Entry, Descent, and Landing

    Science.gov (United States)

    Ono, Masahiro; Kuwata, Yoshiaki

    2013-01-01

    A chance-constrained dynamic programming algorithm was developed that is capable of making optimal sequential decisions within a user-specified risk bound. This work handles stochastic uncertainties over multiple stages in the CEMAT (Combined EDL-Mobility Analyses Tool) framework. It was demonstrated by a simulation of Mars entry, descent, and landing (EDL) using real landscape data obtained from the Mars Reconnaissance Orbiter. Although standard dynamic programming (DP) provides a general framework for optimal sequential decisionmaking under uncertainty, it typically achieves risk aversion by imposing an arbitrary penalty on failure states. Such a penalty-based approach cannot explicitly bound the probability of mission failure. A key idea behind the new approach is called risk allocation, which decomposes a joint chance constraint into a set of individual chance constraints and distributes risk over them. The joint chance constraint was reformulated into a constraint on an expectation over a sum of an indicator function, which can be incorporated into the cost function by dualizing the optimization problem. As a result, the chance-constraint optimization problem can be turned into an unconstrained optimization over a Lagrangian, which can be solved efficiently using a standard DP approach.

  14. Optimization of the production plan and risk control in Third Qinshan Nuclear Power Co.,Ltd

    International Nuclear Information System (INIS)

    Zhou Jun

    2009-01-01

    Some optimized and improved measures have been taken in Third Qinshan Nuclear Power Co., Ltd. (TQNPC) to optimize the routine production plan management, strengthen the maintenance work risk analysis, and improve the plan execution capability. Which involve unified management of generation, refueling, periodic test and maintenance plans; simplifying the defect scale and reducing the intermediate link of defect treatment; intensifying the appraisal on plan execution and adopting star performance evaluation and merit rating measures. In this paper, the above-mentioned improvement and optimization are introduced comprehensively and systematically. (authors)

  15. Reduction of cancer risk by optimization of Computed Tomography head protocols: far eastern Cuban experience

    International Nuclear Information System (INIS)

    Miller Clemente, R.; Adame Brooks, D.; Lores Guevara, M.; Perez Diaz, M.; Arias Garlobo, M. L.; Ortega Rodriguez, O.; Nepite Haber, R.; Grinnan Hernandez, O.; Guillama Llosas, A.

    2015-01-01

    The cancer risk estimation constitutes one way for the evaluation of the public health, regarding computed tomography (CT) exposures. Starting from the hypothesis that the optimization of CT protocols would reduce significantly the added cancer risk, the purpose of this research was the application of optimization strategies regarding head CT protocols, in order to reduce the factors affecting the risk of induced cancer. The applied systemic approach included technological and human components, represented by quantitative physical factors. the volumetric kerma indexes, compared with respect to standard, optimized and reference values, were evaluated with multiple means comparison method. The added cancer risk resulted from the application of the methodology for biological effects evaluation, at low doses with low Linear Energy Transfer. Human observers in all scenarios evaluated the image quality. the reduced dose was significantly lower than for standard head protocols and reference levels, where: (1) for pediatric patients, by using an Automatic Exposure Control system, a reduction of 31% compared with standard protocol and ages range of 10-14, and (2) adults, using a Bilateral Filter for images obtained at low doses of 62% from those of standard head protocol. The risk reduction was higher than 25%. The systemic approach used allows the effective identification of factors involved on cancer risk related with exposures to CT. The combination of dose modulation and image restoration with Bilateral Filter, provide a significantly reduction of cancer risk, with acceptable diagnostic image quality. (Author)

  16. The influence of dispositional optimism on post-visit anxiety and risk perception accuracy among breast cancer genetic counselees

    NARCIS (Netherlands)

    Wiering, B. M.; Albada, A.; Bensing, J. M.; Ausems, M. G. E. M.; van Dulmen, A. M.

    2013-01-01

    Objective uch is unknown about the influence of dispositional optimism and affective communication on genetic counselling outcomes. This study investigated the influence of counselees' optimism on the counselees' risk perception accuracy and anxiety, while taking into account the affective

  17. Current status and trends in performance-based risk-sharing arrangements between healthcare payers and medical product manufacturers.

    Science.gov (United States)

    Carlson, Josh J; Gries, Katharine S; Yeung, Kai; Sullivan, Sean D; Garrison, Louis P

    2014-06-01

    Our objective was to identify and characterize publicly available cases and related trends for performance-based risk-sharing arrangements (PBRSAs). We performed a review of PBRSAs over the past 20 years (1993-2013) using available databases and reports from colleagues and healthcare experts. These were categorized according to a previously published taxonomy of scheme types and assessed in terms of the underlying product and market attributes for each scheme. Macro-level trends were identified related to the timing of scheme adoption, countries involved, types of arrangements, and product and market factors. Our search yielded 148 arrangements. From this set, 65 arrangements included a coverage with an evidence development component, 20 included a conditional treatment continuation component, 54 included a performance-linked reimbursement component, and 42 included a financial utilization component. Each type of scheme addresses fundamental uncertainties that exist when products enter the market. The pace of adoption appears to be slowing, but new countries continue to implement PBRSAs. Over this 20-year period, there has been a consistent movement toward arrangements that minimize administrative burden. In conclusion, the pace of PBRSA adoption appears to be slowing but still has traction in many health systems. These remain a viable coverage and reimbursement mechanism for a wide range of medical products. The long-term viability and growth of these arrangements will rest in the ability of the parties to develop mutually beneficial arrangements that entail minimal administrative burden in their development and implementation.

  18. Portfolio optimization using Mean Absolute Deviation (MAD and Conditional Value-at-Risk (CVaR

    Directory of Open Access Journals (Sweden)

    Lucas Pelegrin da Silva

    Full Text Available Abstract This paper investigates the efficiency of traditional portfolio optimization models when the returns of financial assets are highly volatile, e.g., in financial crises periods. We also develop alternative optimization models that combine the mean absolute deviation (MAD and the conditional value at risk (CVaR, attempting to mitigate inefficient, low return and/or high-risk, portfolios. Three methodologies for estimating the probability of the asset’s historical returns are also compared. By using historical data on the Brazilian stock market between 2004 and 2013, we analyze the efficiency of the proposed approaches. Our results show that the traditional models provide portfolios with higher returns, but our propose model are able to generate lower risk portfolios, which might be more attractive in volatile markets. In addition, we find that models that do not use equiprobable scenarios produce better results in terms of return and risk.

  19. Effects of Perceived Risks, Reputation and Electronic Word of Mouth (E-WOM) on Collaborative Consumption of Uber Car Sharing Service

    Science.gov (United States)

    Wati Hawapi, Mega; Sulaiman, Zuraidah; Kohar, Umar Haiyat Abdul; Abu Talib, Noraini

    2017-06-01

    Current transition from traditional economic model of selling and buying to sharing economic business creates a huge impact on consumers’ preferences to participate in collaborative consumption. The market entrance of sharing economic business is relatively new, thus it builds scepticism among consumers. Consumers’ trust becomes the most crucial aspect in determining their willingness to participate in collaborative consumption. This study will reveal the effects of perceived risks (performance and social), reputation and Electronic Word-of Mouth (E-WOM) on Malaysian consumers’ intention of collaborative consumption, especially for Uber car sharing service. This study inspires to enrich the literature for collaborative consumption and perceived risk theory. From the practical perspective, this study may provide insights in assisting the collaborative consumption service providers especially Uber car users on factors influencing the intention to engage in such service.

  20. Large Portfolio Risk Management and Optimal Portfolio Allocation with Dynamic Copulas

    OpenAIRE

    Thorsten Lehnert; Xisong Jin

    2011-01-01

    Previous research focuses on the importance of modeling the multivariate distribution for optimal portfolio allocation and active risk management. However, available dynamic models are not easily applied for high-dimensional problems due to the curse of dimensionality. In this paper, we extend the framework of the Dynamic Conditional Correlation/Equicorrelation and an extreme value approach into a series of Dynamic Conditional Elliptical Copulas. We investigate risk measures like Value at Ris...

  1. Optimization of urban spatial development against flooding and other climate risks, and wider sustainability objectives

    OpenAIRE

    Caparros-Midwood Daniel; Dawson Richard; Barr Stuart

    2016-01-01

    A spatial optimization framework has been developed to help urban areas mitigate climate risks such as flooding and to curb resource use and greenhouse gas emissions. Measures required to address these issues often conflict with each other, for example more compact cities typically use less energy for transportation but increase runoff from high intensity rainfall events. Balancing potential trade-offs and maximizing synergies between these risks and vulnerabilities is therefore a multi-dimen...

  2. Health Cost Risk and Optimal Retirement Provision : A Simple Rule for Annuity Demand

    NARCIS (Netherlands)

    Peijnenburg, J.M.J.; Nijman, T.E.; Werker, B.J.M.

    2010-01-01

    We analyze the effect of health cost risk on optimal annuity demand and consumption/savings decisions. Many retirees are exposed to sizeable out-of-pocket medical expenses, while annuities potentially impair the ability to get liquidity to cover these costs and smooth consumption. We find that if

  3. Optimal Portfolio Allocation under a Probabilistic Risk Constraint and the Incentives for Financial Innovation

    NARCIS (Netherlands)

    J. Daníelsson (Jón); B.N. Jorgensen (Bjørn); C.G. de Vries (Casper); X. Yang (Xiaoguang)

    2001-01-01

    textabstractWe derive, in a complete markets environment, an investor's optimal portfolio allocation subject to both a budget constraint and a probabilistic risk constraint. We demonstrate that the set of feasible portfolios need not be connected or convex, while the number of local optima increases

  4. Optimal, Risk-based Operation and Maintenance Planning for Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard

    2008-01-01

    For offshore wind turbines costs to operation and maintenance are substantial. This paper describes a risk-based life-cycle approach for optimal planning of operation and maintenance. The approach is based on pre-posterior Bayesian decision theory. Deterioration mechanisms such as fatigue...

  5. A Multiswarm Optimizer for Distributed Decision Making in Virtual Enterprise Risk Management

    Directory of Open Access Journals (Sweden)

    Yichuan Shao

    2012-01-01

    Full Text Available We develop an optimization model for risk management in a virtual enterprise environment based on a novel multiswarm particle swarm optimizer called PS2O. The main idea of PS2O is to extend the single population PSO to the interacting multiswarms model by constructing hierarchical interaction topology and enhanced dynamical update equations. With the hierarchical interaction topology, a suitable diversity in the whole population can be maintained. At the same time, the enhanced dynamical update rule significantly speeds up the multiswarm to converge to the global optimum. With five mathematical benchmark functions, PS2O is proved to have considerable potential for solving complex optimization problems. PS2O is then applied to risk management in a virtual enterprise environment. Simulation results demonstrate that the PS2O algorithm is more feasible and efficient than the PSO algorithm in solving this real-world problem.

  6. Cyber security: a critical examination of information sharing versus data sensitivity issues for organisations at risk of cyber attack.

    Science.gov (United States)

    Mallinder, Jason; Drabwell, Peter

    Cyber threats are growing and evolving at an unprecedented rate.Consequently, it is becoming vitally important that organisations share information internally and externally before, during and after incidents they encounter so that lessons can be learned, good practice identified and new cyber resilience capabilities developed. Many organisations are reluctant to share such information for fear of divulging sensitive information or because it may be vague or incomplete. This provides organisations with a complex dilemma: how to share information as openly as possibly about cyber incidents, while protecting their confidentiality and focusing on service recovery from such incidents. This paper explores the dilemma of information sharing versus sensitivity and provides a practical overview of considerations every business continuity plan should address to plan effectively for information sharing in the event of a cyber incident.

  7. A Novel Approach for Risk Minimization in Life-Cycle Oil Production Optimization

    DEFF Research Database (Denmark)

    Capolei, Andrea; Christiansen, Lasse Hjuler; Jørgensen, John Bagterp

    2017-01-01

    The oil research community has invested much effort into computer aided optimization to enhance oil recovery. While simulation studies have demonstrated the potential of model-based technology to improve industrial standards, the largely unknown geology of subsurface reservoirs limits applications...... to commercial oil fields. In particular, uncertain model descriptions lead to risks of profit loss. To address the challenges of geological uncertainty, this paper proposes offset risk minimization. As opposed to existing methodologies of the oil literature, the offset approach minimizes risk of profit loss...

  8. Stochastic optimized life cycle models for risk mitigation in power system applications

    International Nuclear Information System (INIS)

    Sageder, A.

    1998-01-01

    This ork shows the relevance of stochastic optimization in complex power system applications. It was proven that usual deterministic mean value models not only predict inaccurate results but are also most often on the risky side. The change in the market effects all kind of evaluation processes (e.g. fuel type and technology but especially financial engineering evaluations) in the endeavor of a strict risk mitigation comparison. But not only IPPs also traditional Utilities dash for risk/return optimized investment opportunities. In this study I developed a 2-phase model which can support a decision-maker in finding optimal solutions on investment and profitability. It has to be stated, that in this study no objective function will be optimized in an algorithmically way. On the one hand focus is laid on finding optimal solutions out of different choices (highest return at lowest possible risk); on the other hand the endeavor was to provide a decision makers with a better assessment of the likelihood of outcomes on investment considerations. The first (deterministic) phase computes in a Total Cost of Ownership (TCO) approach (Life cycle Calculation; DCF method). Most of the causal relations (day of operation, escalation of personal expanses, inflation, depreciation period, etc.) are defined within this phase. The second (stochastic) phase is a total new way in optimizing risk/return relations. With the some decision theory mathematics an expected value of stochastic solutions can be calculated. Furthermore probability function have to be defined out of historical data. The model not only supports profitability analysis (including regress and sensitivity analysis) but also supports a decision-maker in a decision process. Emphasis was laid on risk-return analysis, which can give the decision-maker first hand informations of the type of risk return problem (risk concave, averse or linear). Five important parameters were chosen which have the characteristics of typical

  9. Estimating vegetation dryness to optimize fire risk assessment with spot vegetation satellite data in savanna ecosystems

    Science.gov (United States)

    Verbesselt, J.; Somers, B.; Lhermitte, S.; van Aardt, J.; Jonckheere, I.; Coppin, P.

    2005-10-01

    The lack of information on vegetation dryness prior to the use of fire as a management tool often leads to a significant deterioration of the savanna ecosystem. This paper therefore evaluated the capacity of SPOT VEGETATION time-series to monitor the vegetation dryness (i.e., vegetation moisture content per vegetation amount) in order to optimize fire risk assessment in the savanna ecosystem of Kruger National Park in South Africa. The integrated Relative Vegetation Index approach (iRVI) to quantify the amount of herbaceous biomass at the end of the rain season and the Accumulated Relative Normalized Difference vegetation index decrement (ARND) related to vegetation moisture content were selected. The iRVI and ARND related to vegetation amount and moisture content, respectively, were combined in order to monitor vegetation dryness and optimize fire risk assessment in the savanna ecosystems. In situ fire activity data was used to evaluate the significance of the iRVI and ARND to monitor vegetation dryness for fire risk assessment. Results from the binary logistic regression analysis confirmed that the assessment of fire risk was optimized by integration of both the vegetation quantity (iRVI) and vegetation moisture content (ARND) as statistically significant explanatory variables. Consequently, the integrated use of both iRVI and ARND to monitor vegetation dryness provides a more suitable tool for fire management and suppression compared to other traditional satellite-based fire risk assessment methods, only related to vegetation moisture content.

  10. Optimization of urban spatial development against flooding and other climate risks, and wider sustainability objectives

    Directory of Open Access Journals (Sweden)

    Caparros-Midwood Daniel

    2016-01-01

    Full Text Available A spatial optimization framework has been developed to help urban areas mitigate climate risks such as flooding and to curb resource use and greenhouse gas emissions. Measures required to address these issues often conflict with each other, for example more compact cities typically use less energy for transportation but increase runoff from high intensity rainfall events. Balancing potential trade-offs and maximizing synergies between these risks and vulnerabilities is therefore a multi-dimensional, spatial, challenge for urban planners. A spatial optimization framework is used to optimize the following objectives to minimize: (1 risk from heat waves; (2 risk from flooding; (3 the distance of new development to the current central business district; (4 urban sprawl to prevent increased travel costs; and (5 the development of green-space. The framework is applied to a real case study in the North East of England. From an initial configuration, alternative spatial configurations are tested against these objectives and the spatial pattern is evolved over successive generations to search for spatially optimum configurations. The resulting solutions provide planners with a range of robust spatial development patterns known to be best trade-offs which mitigate conflicts between risk and sustainability objectives.

  11. A Multi-Breed Genome-Wide Association Analysis for Canine Hypothyroidism Identifies a Shared Major Risk Locus on CFA12.

    Directory of Open Access Journals (Sweden)

    Matteo Bianchi

    Full Text Available Hypothyroidism is a complex clinical condition found in both humans and dogs, thought to be caused by a combination of genetic and environmental factors. In this study we present a multi-breed analysis of predisposing genetic risk factors for hypothyroidism in dogs using three high-risk breeds--the Gordon Setter, Hovawart and the Rhodesian Ridgeback. Using a genome-wide association approach and meta-analysis, we identified a major hypothyroidism risk locus shared by these breeds on chromosome 12 (p = 2.1x10(-11. Further characterisation of the candidate region revealed a shared ~167 kb risk haplotype (4,915,018-5,081,823 bp, tagged by two SNPs in almost complete linkage disequilibrium. This breed-shared risk haplotype includes three genes (LHFPL5, SRPK1 and SLC26A8 and does not extend to the dog leukocyte antigen (DLA class II gene cluster located in the vicinity. These three genes have not been identified as candidate genes for hypothyroid disease previously, but have functions that could potentially contribute to the development of the disease. Our results implicate the potential involvement of novel genes and pathways for the development of canine hypothyroidism, raising new possibilities for screening, breeding programmes and treatments in dogs. This study may also contribute to our understanding of the genetic etiology of human hypothyroid disease, which is one of the most common endocrine disorders in humans.

  12. Use of Neural Networks in Risk Assessment and Optimization of Insurance Cover in Innovative Enterprises

    Directory of Open Access Journals (Sweden)

    Pukała Ryszard

    2016-09-01

    Full Text Available The scientific objective of the paper is to present the findings of a study into the use of artificial neural networks in quantifying activity related risks of an innovative enterprise and to optimize its insurance cover in order to minimize the probable financial losses whenever they materialize. The Kohonen network involving the activation of 51 input variables was applied in the study. The outcomes of the stimulation for the given set of variables made it possible to determine the probability of a threat occurring in the classes. The results of the analysis were used to prepare an optimal insurance cover for the activities of the innovative company. The research findings are suitable for use in risk theory as well as in issues relating to entrepreneurship and insurance. The analytical device employed can also be put to practical use as a support tool in corporate risk management.

  13. Risks associated with borrowing and sharing of prescription analgesics among patients observed by pain management physicians in Croatia: a qualitative study

    Directory of Open Access Journals (Sweden)

    Markotic F

    2016-11-01

    Full Text Available Filipa Markotic,1 Livia Puljak2 1Centre for Clinical Pharmacology, University Clinical Hospital Mostar, Mostar, Bosnia and Herzegovina; 2Laboratory for Pain Research, University of Split School of Medicine, Split, Croatia Background: Understanding and improving patient safety is a key issue in medicine. One of the potential threats to patient safety is the sharing of medication among patients, which is a form of self-medication. This study analyzed experiences and attitudes of pain management physicians (PMPs about sharing prescription analgesics among patients.Methods: This qualitative study was conducted by semi-structured interviews among PMPs employed in Croatian pain clinics. The study involved two researchers and 15 PMPs.Results: Among PMPs, 80% have seen patients who share their prescription analgesics with other patients for whom prescription is not intended. Most PMPs consider prescription analgesics sharing a risky and negative behavior. Some of them, however, found certain positive aspects associated to it, such as being a benevolent behavior, helping patients to get medications when they need them, and helping them cope with pain.Conclusion: The majority of physicians specialized in pain management encountered patients sharing prescription analgesics. Most of them considered this as risky behavior with a number of potential consequences. It has been noted that this problem is neglected and that physicians should inquire about medication sharing. Direct-to-consumers advertising was perceived as a factor contributing to such behavior. Patient education and more involvement of physicians in identifying this behavior were cited as potential remedies for preventing sharing of prescription analgesics. Keywords: analgesics, sharing, lending, borrowing, risks

  14. Optimal dietary calcium intake in HIV treated patients: no femoral osteoporosis but higher cardiovascular risk.

    Science.gov (United States)

    Galli, Laura; Rubinacci, Alessandro; Cocorullo, Deborah; Salpietro, Stefania; Spagnuolo, Vincenzo; Gianotti, Nicola; Bigoloni, Alba; Vinci, Concetta; Mignogna, Giovanna; Sirtori, Marcella; Lazzarin, Adriano; Castagna, Antonella

    2014-04-01

    We performed a cross-sectional study on adult HIV-infected patients, on HAART, without calcium or vitamin D supplementation to evaluate if the cardiovascular risk or the presence of osteoporosis may be predictive factors of an optimal daily calcium intake (DCI>1000 mg/day). Patients underwent a dual-energy X-ray absorptiometry, measured biochemical parameters and compiled a validated questionnaire for the assessment of DCI. Osteoporosis (OP) was defined according to the WHO classification at either the vertebral spine or femoral neck. Cardiovascular risk was assessed by the 10-year Framingham cardiovascular risk score. 200 HIV-infected patients evaluated: 171 (86%) males with a median age of 48.1 (42.3-53.8) years and 10.6 (4.3-13.6) years of HAART exposure. DCI was 889 (589-1308) mg/day and 79 (40%) patients had an optimal DCI. Framingham risk>20% was found in 13 (6.7%) patients and femoral OP was diagnosed in 12 (6%) pts. By multivariate analysis, optimal DCI was more likely in patients with a Framingham risk>20% [OR = 5.547, 95% CI:1.337, p = 0.025] and less likely in patients with femoral osteoporosis [OR = 0.159, 95% CI: 0.018-0.790, p = 0.047]. We found that an optimal dietary calcium intake was more likely in patients with high cardiovascular risk and no femoral osteoporosis. Copyright © 2013 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  15. Dynamic Value Engineering Method Optimizing the Risk on Real Time Operating System

    Directory of Open Access Journals (Sweden)

    Prashant Kumar Patra

    2014-04-01

    Full Text Available The value engineering is the umbrella of the many more sub-system like quality assurance, quality control, quality function design and development for manufacturability. The system engineering & value engineering is two part of the coin. The value engineering is the high level of technology management for every aspect of engineering fields. The value engineering is the high utilization of System Product (i.e. Processor, Memory & Encryption key, Services, Business and Resources at minimal cost. The high end operating system providing highest services at optimal cost & time. The value engineering provides the maximum performance, accountability, reliability, integrity and availability of processor, memory, encryption key and other inter dependency sub-components. The value engineering is the ratio of the maximum functionality of individual components to the optimal cost. VE=k [(P, M, E, C, A]/optimal cost. Where k is the proportionality constant. The VE is directly proportional to performance of individual components and inversely proportional to the minimal cost. The VE is directly proportional to the risk assessment. The VE maximize the business throughput & decision process mean while minimize the risk and down time. We have to develop the dynamic value engineering model & mechanism for risk optimization over a complex real time operating system This proposed composition model definite will be resolve our objective at top high level. Product

  16. Report: Implementation Plan With Cost Sharing Methodology Needed for Region 8 Senior Environmental Employee Work on Lead Risk Reduction

    Science.gov (United States)

    Report #13-P-0430, September 24, 2013. The two Region 8 program offices that jointly implement the Lead Renovation, Repair and Painting Program do not have methodology or agreement for sharing SEE funding, which has led to confusion.

  17. Risk averse optimal operation of a virtual power plant using two stage stochastic programming

    International Nuclear Information System (INIS)

    Tajeddini, Mohammad Amin; Rahimi-Kian, Ashkan; Soroudi, Alireza

    2014-01-01

    VPP (Virtual Power Plant) is defined as a cluster of energy conversion/storage units which are centrally operated in order to improve the technical and economic performance. This paper addresses the optimal operation of a VPP considering the risk factors affecting its daily operation profits. The optimal operation is modelled in both day ahead and balancing markets as a two-stage stochastic mixed integer linear programming in order to maximize a GenCo (generation companies) expected profit. Furthermore, the CVaR (Conditional Value at Risk) is used as a risk measure technique in order to control the risk of low profit scenarios. The uncertain parameters, including the PV power output, wind power output and day-ahead market prices are modelled through scenarios. The proposed model is successfully applied to a real case study to show its applicability and the results are presented and thoroughly discussed. - Highlights: • Virtual power plant modelling considering a set of energy generating and conversion units. • Uncertainty modelling using two stage stochastic programming technique. • Risk modelling using conditional value at risk. • Flexible operation of renewable energy resources. • Electricity price uncertainty in day ahead energy markets

  18. Assessment of Medical Risks and Optimization of their Management using Integrated Medical Model

    Science.gov (United States)

    Fitts, Mary A.; Madurai, Siram; Butler, Doug; Kerstman, Eric; Risin, Diana

    2008-01-01

    The Integrated Medical Model (IMM) Project is a software-based technique that will identify and quantify the medical needs and health risks of exploration crew members during space flight and evaluate the effectiveness of potential mitigation strategies. The IMM Project employs an evidence-based approach that will quantify probability and consequences of defined in-flight medical risks, mitigation strategies, and tactics to optimize crew member health. Using stochastic techniques, the IMM will ultimately inform decision makers at both programmatic and institutional levels and will enable objective assessment of crew health and optimization of mission success using data from relevant cohort populations and from the astronaut population. The objectives of the project include: 1) identification and documentation of conditions that may occur during exploration missions (Baseline Medical Conditions List [BMCL), 2) assessment of the likelihood of conditions in the BMCL occurring during exploration missions (incidence rate), 3) determination of the risk associated with these conditions and quantify in terms of end states (Loss of Crew, Loss of Mission, Evacuation), 4) optimization of in-flight hardware mass, volume, power, bandwidth and cost for a given level of risk or uncertainty, and .. validation of the methodologies used.

  19. Optimal hydro scheduling and offering strategies considering price uncertainty and risk management

    International Nuclear Information System (INIS)

    Catalão, J.P.S.; Pousinho, H.M.I.; Contreras, J.

    2012-01-01

    Hydro energy represents a priority in the energy policy of Portugal, with the aim of decreasing the dependence on fossil fuels. In this context, optimal hydro scheduling acquires added significance in moving towards a sustainable environment. A mixed-integer nonlinear programming approach is considered to enable optimal hydro scheduling for the short-term time horizon, including the effect of head on power production, start-up costs related to the units, multiple regions of operation, and constraints on discharge variation. As new contributions to the field, market uncertainty is introduced in the model via price scenarios and risk management is included using Conditional Value-at-Risk to limit profit volatility. Moreover, plant scheduling and pool offering by the hydro power producer are simultaneously considered to solve a realistic cascaded hydro system. -- Highlights: ► A mixed-integer nonlinear programming approach is considered for optimal hydro scheduling. ► Market uncertainty is introduced in the model via price scenarios. ► Risk management is included using conditional value-at-risk. ► Plant scheduling and pool offering by the hydro power producer are simultaneously considered. ► A realistic cascaded hydro system is solved.

  20. Risk-informed optimal routing of ships considering different damage scenarios and operational conditions

    International Nuclear Information System (INIS)

    Decò, Alberto; Frangopol, Dan M.

    2013-01-01

    The aim of this paper is the development of a risk-informed decision tool for the optimal mission-oriented routing of ships. The strength of the hull is investigated by modeling the midship section with finite elements and by analyzing different damage levels depending on the propagation of plastification throughout the section. Vertical and horizontal flexural interaction is investigated. Uncertainties associated with geometry and material properties are accounted for by means of the implementation of the response surface method. Load effects are evaluated using strip theory. Reliability analysis is performed for several ship operational conditions and considering four different limit states. Then, risk is assessed by including the direct losses associated with five investigated damage states. The effects of corrosion on aged ships are included in the proposed approach. Polar representation of load effects, reliability, and direct risk are presented for a large spectrum of operational conditions. Finally, the optimal routing of ships is obtained by minimizing both the estimated time of arrival and the expected direct risk, which are clearly conflicting objectives. The optimization process provides feasible solutions belonging to the Pareto front. The proposed approach is applied to a Joint High Speed Sealift

  1. Dizziness in older people: at risk of shared therapeutic nihilism between patient and physician. A qualitative study.

    Science.gov (United States)

    Stam, Hanneke; Wisse, Marjanne; Mulder, Bram; van der Wouden, Johannes C; Maarsingh, Otto R; van der Horst, Henriëtte E

    2016-07-16

    Dizziness-related impairment is a strong predictor for an unfavourable course of dizziness in older people. In this study we explored the experiences of older patients with significant dizziness-related impairment and their wishes and expectations regarding general practitioner (GP) care. Knowing the expectations and priorities of people with dizziness may enable the GP to provide tailor-made care, which in turn may substantially increase the quality of life and decrease the use and costs of health care. We conducted a qualitative study with semi-structured interviews. We selected patients from ten Dutch general practices. Patients were invited to participate in the study if they were ≥ 65 years, visited their GP because of dizziness and were significantly impaired due to dizziness (Dizziness Handicap Inventory ≥ 30). We applied content analysis to the semi-structured interviews. Thirteen participants participated, seven were female. Analysis of the interviews resulted in the overall theme "Dizziness in older people: at risk of shared therapeutic nihilism by the patient and the GP". Firstly, this can explained by the fact that participants frequently presented dizziness as a secondary complaint when they visited the GP for another complaint. Secondly, participants reported that the GP often could not help them with any treatment. Despite a poor therapeutic outcome, the vast majority of participants was satisfied how the GP handled their dizziness. Yet, understanding the cause of dizziness seems important for dizzy older patients. Despite significant dizziness-related impairment, older dizzy patients may not present dizziness as main reason for encounter. Presenting dizziness as a secondary complaint may give GPs the - wrong - impression that the dizziness-related impairment is only mild. GPs need to be aware of this potential underreporting. Knowing the cause of dizziness seems important for older patients. Yet, GPs regularly did not succeed in

  2. Shared pledge shared vision

    International Nuclear Information System (INIS)

    Boussaha, Ali; Diatta, Christian Sina

    2005-01-01

    The New Partnership for Africa's Development (NEPAD) is a pledge by African leaders to eradicate poverty and to promote sustainable growth and development. NEPAD is a 'new framework of interaction with the rest of the world, including the industrialised countries and multilateral organizations.' The agenda is based on regional priorities and development plans and its implementation relies on African ownership and management. As a UN system organisation, the IAEA strongly supports the priorities identified in the Millennium Declaration and the New Partnership for Africa's Development. As a technical agency, the IAEA shares its recognized core competencies and technical expertise in support of NEPAD goals. Efforts aim at strengthening institutional capacity building in nuclear sciences and technology and promoting the sustainable application of nuclear techniques for social and economic development. The IAEA has a membership of 34 African countries. The Agency supports them under its technical cooperation programme through provision of expertise, training opportunities and equipment in priority areas identified by the countries themselves. For many African Member States, meeting basic human needs through the implementation of poverty alleviation strategies remains the top priority on the agenda for national development plans and international cooperation programmes. In the context of sustainable development, special attention is being paid to enlarging the contribution of isotopes and nuclear techniques in major areas of economic and social significance and to promoting regional cooperation in nuclear science and technology related fields. As a partner in development, the Agency has promoted and undertaken programmes to support African countries' efforts to address priority development issues particularly in the areas of health care, food and agriculture and water resources development. The IAEA technical cooperation mechanism includes support to the African Regional

  3. Using risk-informed asset management for feedwater system preventative maintenance optimization

    International Nuclear Information System (INIS)

    Kee, Ernest; Sun, Alice; Richards, Andrew; Grantom, Rick; Liming, James; Salter, James

    2004-01-01

    The initial development of a South Texas Project Nuclear Operating Company process for supporting preventative maintenance optimization by applying the Balance-Of-Plant model and Risk-Informed Asset Management alpha-level software applications is presented. Preventative maintenance activities are evaluated in the South Texas Project Risk-Informed Asset Management software while the plant maintains or improves upon high levels of nuclear safety. In the Balance-Of-Plant availability application, the level of detail in the feedwater system is enhanced to support plant decision-making at the component failure mode and human error mode level of indenture by elaborating on the current model at the super-component level of indenture. The enhanced model and modeling techniques are presented. Results of case studies in feedwater system preventative maintenance optimization sing plant-specific data are also presented. (author)

  4. Perhitungan Value at Risk Pada Portfolio Optimal: Studi Perbandingan Saham Syariah dan Saham Konvensional

    Directory of Open Access Journals (Sweden)

    Sri Astuti Heryanti

    2017-05-01

    Full Text Available The aim of this study was to obtain empirical evidence about the difference between the level of risk when investing stocks in the Islamic and conventional by using Value at Risk (VaR. The object of research including consistent stock in the Jakarta Islamic Index and LQ45. The analytical method used in this research is quantitative analysis consisting of the establishment of the optimal portfolio by Markowitz method, calculation of VaR and testing the differences with Independent sample t-test. This study indicated that the value every stock can be reduced by diversifying through the establishment of an optimal portfolio. Based on the calculation Independent sample t-test, it is known that there is no difference between VaR of Islamic stocks and conventional stocks.

  5. Optimal Control for Insurers with a Jump-diffusion Risk Pro cess

    Institute of Scientific and Technical Information of China (English)

    WU Kun; XIAO Jian-wu; LUO Rong-hua

    2015-01-01

    In this paper, the optimal XL-reinsurance of an insurer with jump-diffusion risk process is studied. With the assumptions that the risk process is a compound Possion pro-cess perturbed by a standard Brownian motion and the reinsurance premium is calculated according to the variance principle, the implicit expression of the priority and corresponding value function when the utility function is exponential are obtained. At last, the value func-tion is argued, the properties of the priority about parameters are discussed and numerical results of the priority for various claim-size distributions are shown.

  6. Risk-Sensitive and Mean Variance Optimality in Markov Decision Processes

    Czech Academy of Sciences Publication Activity Database

    Sladký, Karel

    2013-01-01

    Roč. 7, č. 3 (2013), s. 146-161 ISSN 0572-3043 R&D Projects: GA ČR GAP402/10/0956; GA ČR GAP402/11/0150 Grant - others:AVČR a CONACyT(CZ) 171396 Institutional support: RVO:67985556 Keywords : Discrete-time Markov decision chains * exponential utility functions * certainty equivalent * mean-variance optimality * connections between risk -sensitive and risk -neutral models Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2013/E/sladky-0399099.pdf

  7. Combinatorial Algorithms for Portfolio Optimization Problems - Case of Risk Moderate Investor

    Science.gov (United States)

    Juarna, A.

    2017-03-01

    Portfolio optimization problem is a problem of finding optimal combination of n stocks from N ≥ n available stocks that gives maximal aggregate return and minimal aggregate risk. In this paper given N = 43 from the IDX (Indonesia Stock Exchange) group of the 45 most-traded stocks, known as the LQ45, with p = 24 data of monthly returns for each stock, spanned over interval 2013-2014. This problem actually is a combinatorial one where its algorithm is constructed based on two considerations: risk moderate type of investor and maximum allowed correlation coefficient between every two eligible stocks. The main outputs resulted from implementation of the algorithms is a multiple curve of three portfolio’s attributes, e.g. the size, the ratio of return to risk, and the percentage of negative correlation coefficient for every two chosen stocks, as function of maximum allowed correlation coefficient between each two stocks. The output curve shows that the portfolio contains three stocks with ratio of return to risk at 14.57 if the maximum allowed correlation coefficient between every two eligible stocks is negative and contains 19 stocks with maximum allowed correlation coefficient 0.17 to get maximum ratio of return to risk at 25.48.

  8. Probabilistic runoff volume forecasting in risk-based optimization for RTC of urban drainage systems

    DEFF Research Database (Denmark)

    Löwe, Roland; Vezzaro, Luca; Mikkelsen, Peter Steen

    2016-01-01

    overflow risk. The stochastic control framework and the performance of the runoff forecasting models are tested in a case study in Copenhagen (76 km2 with 6 sub-catchments and 7 control points) using 2-h radar rainfall forecasts and inlet flows to control points computed from a variety of noisy...... smoothing. Simulations demonstrate notable improvements of the control efficiency when considering forecast information and additionally when considering forecast uncertainty, compared with optimization based on current basin fillings only....

  9. The 'bankability' of the new waste technologies: an econometric method for risk sharing in private finance waste contracts.

    Science.gov (United States)

    Black, I; Seaton, R; Chackiath, S; Wagland, S T; Pollard, S J T; Longhurst, P J

    2011-12-01

    The identification of risk and its appropriate allocation to partners in project consortia is essential for minimizing overall project risks, ensuring timely delivery and maximizing benefit for money invested. Risk management guidance available from government bodies, especially in the UK, does not specify methodologies for quantitative risk assessment, nor does it offer a procedure for allocating risk among project partners. Here, a methodology to quantify project risk and potential approaches to allocating risk and their implications are discussed. Construction and operation of a waste management facility through a public-private finance contract are discussed. Public-private partnership contracts are special purpose vehicle (SPV) financing methods promoted by the UK government to boost private sector investment in facilities for public service enhancement. Our findings question the appropriateness of using standard deviation as a measure for project risk and confirm the concept of portfolio theory, suggesting the pooling of risk can reduce total risk and its impact.

  10. Lifetime risk of atrial fibrillation according to optimal, borderline, or elevated levels of risk factors: cohort study based on longitudinal data from the Framingham Heart Study

    Science.gov (United States)

    Staerk, Laila; Wang, Biqi; Preis, Sarah R; Larson, Martin G; Lubitz, Steven A; Ellinor, Patrick T; McManus, David D; Ko, Darae; Weng, Lu-Chen; Lunetta, Kathryn L; Frost, Lars; Benjamin, Emelia J

    2018-01-01

    Abstract Objective To examine the association between risk factor burdens—categorized as optimal, borderline, or elevated—and the lifetime risk of atrial fibrillation. Design Community based cohort study. Setting Longitudinal data from the Framingham Heart Study. Participants Individuals free of atrial fibrillation at index ages 55, 65, and 75 years were assessed. Smoking, alcohol consumption, body mass index, blood pressure, diabetes, and history of heart failure or myocardial infarction were assessed as being optimal (that is, all risk factors were optimal), borderline (presence of borderline risk factors and absence of any elevated risk factor), or elevated (presence of at least one elevated risk factor) at index age. Main outcome measure Lifetime risk of atrial fibrillation at index age up to 95 years, accounting for the competing risk of death. Results At index age 55 years, the study sample comprised 5338 participants (2531 (47.4%) men). In this group, 247 (4.6%) had an optimal risk profile, 1415 (26.5%) had a borderline risk profile, and 3676 (68.9%) an elevated risk profile. The prevalence of elevated risk factors increased gradually when the index ages rose. For index age of 55 years, the lifetime risk of atrial fibrillation was 37.0% (95% confidence interval 34.3% to 39.6%). The lifetime risk of atrial fibrillation was 23.4% (12.8% to 34.5%) with an optimal risk profile, 33.4% (27.9% to 38.9%) with a borderline risk profile, and 38.4% (35.5% to 41.4%) with an elevated risk profile. Overall, participants with at least one elevated risk factor were associated with at least 37.8% lifetime risk of atrial fibrillation. The gradient in lifetime risk across risk factor burden was similar at index ages 65 and 75 years. Conclusions Regardless of index ages at 55, 65, or 75 years, an optimal risk factor profile was associated with a lifetime risk of atrial fibrillation of about one in five; this risk rose to more than one in three in individuals with at least

  11. Optimizing an Investment Solution in Conditions of Uncertainty and Risk as a Multicriterial Task

    Directory of Open Access Journals (Sweden)

    Kotsyuba Oleksiy S.

    2017-10-01

    Full Text Available The article is concerned with the methodology for optimizing investment decisions in conditions of uncertainty and risk. The subject area of the study relates, first of all, to real investment. The problem of modeling an optimal investment solution is considered to be a multicriterial task. Also, the constructive part of the publication is based on the position that the multicriteriality of objectives of investment projecting is the result, first, of the complex nature of the category of economic attractiveness (efficiency of real investment, and secondly, of the need to take into account the risk factor, which is a vector measure, in the preparation of an investment solution. An attempt has been made to develop an instrumentarium to optimize investment decisions in a situation of uncertainty and the risk it engenders, based on the use of roll-up of the local criteria. As a result of its implementation, a model has been proposed, which has the advantage that it takes into account, to a greater extent than is the case for standardized roll-up options, the contensive and formal features of the local (detailed criteria.

  12. To share and be shared

    DEFF Research Database (Denmark)

    Winther, Ida Wentzel

    2018-01-01

    to another. To a certain degree, they share their everyday lives, things, places, memories, and past/future, but as the ones who move back and forth, they belong a little less in each place. This article is about children who are shared between their parent, households and siblings. They are shared...

  13. What is the optimal management of high risk, clinically localized prostate cancer?

    Science.gov (United States)

    Eastham, James A; Evans, Christopher P; Zietman, Anthony

    2010-01-01

    To summarize the presentations and debate regarding the optimal treatment of localized high-risk prostate cancer as presented at the 2009 Spring Meeting of the Society of Urologic Oncology. The debate was centered on presentations arguing for radical prostatectomy (RP) or radiotherapy as the optimal treatment for this condition. The meeting presentations are summarized by their respective presenters herein. Dr. James Eastham presents the varied definitions for "high-risk" prostate cancer as strongly influencing which patients end up in this cohort. Based upon this, between 3% and 38% of patients with high-risk features could be defined as "high-risk". Despite that, these men do not have a uniformly poor prognosis after RP, and attention to surgical principles as outlined improve outcomes. Disease-specific survival at 12 years is excellent and up to one-half of these men may not need adjuvant or salvage therapies, depending on their specific disease characteristics. Adjuvant or salvage radiotherapies improve outcomes and are part of a sequential approach to treating these patients. Dr. Anthony Zietman presented radiotherapy as the gold-standard based upon large, randomized clinical trials of intermediate- and high-risk prostate cancer patients. Compared with androgen deprivation alone, the addition of radiotherapy provided a 12% cancer-specific survival advantage and 10% overall survival advantage. Dose escalation seems to confer further improvements in cancer control without significant escalation of toxicities, with more data forthcoming. There are no randomized trials comparing RP to radiotherapy for any risk category. In high-risk prostate cancer patients, both approaches have potential benefits and cumulative toxicities that must be matched to disease characteristics and patient expectations in selecting a treatment course. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  14. Human MHC-II with Shared Epitope Motifs Are Optimal Epstein-Barr Virus Glycoprotein 42 Ligands—Relation to Rheumatoid Arthritis

    Science.gov (United States)

    Trier, Nicole; Izarzugaza, Jose; Chailyan, Anna; Marcatili, Paolo; Houen, Gunnar

    2018-01-01

    Rheumatoid arthritis (RA) is a chronic systemic autoimmune disorder of unknown etiology, which is characterized by inflammation in the synovium and joint damage. Although the pathogenesis of RA remains to be determined, a combination of environmental (e.g., viral infections) and genetic factors influence disease onset. Especially genetic factors play a vital role in the onset of disease, as the heritability of RA is 50–60%, with the human leukocyte antigen (HLA) alleles accounting for at least 30% of the overall genetic risk. Some HLA-DR alleles encode a conserved sequence of amino acids, referred to as the shared epitope (SE) structure. By analyzing the structure of a HLA-DR molecule in complex with Epstein-Barr virus (EBV), the SE motif is suggested to play a vital role in the interaction of MHC II with the viral glycoprotein (gp) 42, an essential entry factor for EBV. EBV has been repeatedly linked to RA by several lines of evidence and, based on several findings, we suggest that EBV is able to induce the onset of RA in predisposed SE-positive individuals, by promoting entry of B-cells through direct contact between SE and gp42 in the entry complex. PMID:29361739

  15. Identification of risk loci with shared effects on five major psychiatric disorders: a genome-wide analysis

    NARCIS (Netherlands)

    Smoller, J.W.; Craddock, N.; Kendler, K.; Lee, P.H.; Neale, B.M.; Nurnberger, J.I.; Ripke, S.; Santangelo, S.; Sullivan, P.F.; Buitelaar, J.K.; Franke, B.; et al.,

    2013-01-01

    BACKGROUND: Findings from family and twin studies suggest that genetic contributions to psychiatric disorders do not in all cases map to present diagnostic categories. We aimed to identify specific variants underlying genetic effects shared between the five disorders in the Psychiatric Genomics

  16. Communicating and Sharing in the Semantic Web: An Examination of Social Media Risks, Consequences, and Attitudinal Awareness

    Science.gov (United States)

    Buzzetto-More, Nicole; Johnson, Robert; Elobaid, Muna

    2015-01-01

    Empowered by and tethered to ubiquitous technologies, the current generation of youth yearns for opportunities to engage in self-expression and information sharing online with personal disclosure no longer governed by concepts of propriety and privacy. This raises issues about the unsafe online activities of teens and young adults. The following…

  17. QbD for pediatric oral lyophilisates development: risk assessment followed by screening and optimization.

    Science.gov (United States)

    Casian, Tibor; Iurian, Sonia; Bogdan, Catalina; Rus, Lucia; Moldovan, Mirela; Tomuta, Ioan

    2017-12-01

    This study proposed the development of oral lyophilisates with respect to pediatric medicine development guidelines, by applying risk management strategies and DoE as an integrated QbD approach. Product critical quality attributes were overviewed by generating Ishikawa diagrams for risk assessment purposes, considering process, formulation and methodology related parameters. Failure Mode Effect Analysis was applied to highlight critical formulation and process parameters with an increased probability of occurrence and with a high impact on the product performance. To investigate the effect of qualitative and quantitative formulation variables D-optimal designs were used for screening and optimization purposes. Process parameters related to suspension preparation and lyophilization were classified as significant factors, and were controlled by implementing risk mitigation strategies. Both quantitative and qualitative formulation variables introduced in the experimental design influenced the product's disintegration time, mechanical resistance and dissolution properties selected as CQAs. The optimum formulation selected through Design Space presented ultra-fast disintegration time (5 seconds), a good dissolution rate (above 90%) combined with a high mechanical resistance (above 600 g load). Combining FMEA and DoE allowed the science based development of a product with respect to the defined quality target profile by providing better insights on the relevant parameters throughout development process. The utility of risk management tools in pharmaceutical development was demonstrated.

  18. Cultural Effects on Cancer Prevention Behaviors: Fatalistic Cancer Beliefs and Risk Optimism Among Asians in Singapore.

    Science.gov (United States)

    Kim, Hye Kyung; Lwin, May O

    2017-10-01

    Although culture is acknowledged as an important factor that influences health, little is known about cultural differences pertaining to cancer-related beliefs and prevention behaviors. This study examines two culturally influenced beliefs-fatalistic beliefs about cancer prevention, and optimistic beliefs about cancer risk-to identify reasons for cultural disparity in the engagement of cancer prevention behaviors. We utilized data from national surveys of European Americans in the United States (Health Information National Trends Survey 4, Cycle3; N = 1,139) and Asians in Singapore (N = 1,200) to make cultural comparisons. The odds of an Asian adhering to prevention recommendations were less than half the odds of a European American, with the exception of smoking avoidance. Compared to European Americans, Asians were more optimistic about their cancer risk both in an absolute and a comparative sense, and held stronger fatalistic beliefs about cancer prevention. Mediation analyses revealed that fatalistic beliefs and absolute risk optimism among Asians partially explain their lower engagement in prevention behaviors, whereas comparative risk optimism increases their likelihood of adhering to prevention behaviors. Our findings underscore the need for developing culturally targeted interventions in communicating cancer causes and prevention.

  19. Optimal Treatment for Intermediate- and High-Risk, Nonmuscle-Invasive Bladder Cancer

    Directory of Open Access Journals (Sweden)

    A.P.M. van der Meijden

    2006-01-01

    Full Text Available According to clinical and pathological factors the prognosis of a patient with non-muscle invasive bladder tumors can be assessed. The prognosis is determined by the likelihood of recurrence(30-70% and/or progression to muscle invasive bladder cancer(1-15%.Trans urethral resection of bladder tumors remains the initial therapy but adjuvant intravesical instillations are necessary.All patients benefit from a single immediate post operative instillation with a chemotherapeutic agent and for low risk tumors this is the optimal therapy.Patients with intermediate and high risk tumors need more intravesical chemo-or immunotherapy. Chemotherapy reduces recurrences but not progression. Intravesical immunotherapy(BCG prevents or delays progression. Patients at high risk for progression may need upfront cystectomy.

  20. Mean-variance model for portfolio optimization with background risk based on uncertainty theory

    Science.gov (United States)

    Zhai, Jia; Bai, Manying

    2018-04-01

    The aim of this paper is to develop a mean-variance model for portfolio optimization considering the background risk, liquidity and transaction cost based on uncertainty theory. In portfolio selection problem, returns of securities and assets liquidity are assumed as uncertain variables because of incidents or lacking of historical data, which are common in economic and social environment. We provide crisp forms of the model and a hybrid intelligent algorithm to solve it. Under a mean-variance framework, we analyze the portfolio frontier characteristic considering independently additive background risk. In addition, we discuss some effects of background risk and liquidity constraint on the portfolio selection. Finally, we demonstrate the proposed models by numerical simulations.

  1. Optimal Ordering Policy of a Risk-Averse Retailer Subject to Inventory Inaccuracy

    Directory of Open Access Journals (Sweden)

    Lijing Zhu

    2013-01-01

    Full Text Available Inventory inaccuracy refers to the discrepancy between the actual inventory and the recorded inventory information. Inventory inaccuracy is prevalent in retail stores. It may result in a higher inventory level or poor customer service. Earlier studies of inventory inaccuracy have traditionally assumed risk-neutral retailers whose objective is to maximize expected profits. We investigate a risk-averse retailer within a newsvendor framework. The risk aversion attitude is measured by conditional-value-at-risk (CVaR. We consider inventory inaccuracy stemming both from permanent shrinkage and temporary shrinkage. Two scenarios of reducing inventory shrinkage are presented. In the first scenario, the retailer conducts physical inventory audits to identify the discrepancy. In the second scenario, the retailer deploys an automatic tracking technology, radiofrequency identification (RFID, to reduce inventory shrinkage. With the CVaR criterion, we propose optimal policies for the two scenarios. We show monotonicity between the retailer’s ordering policy and his risk aversion degree. A numerical analysis provides managerial insights for risk-averse retailers considering investing in RFID technology.

  2. Revisiting support optimization at the Driskos tunnel using a quantitative risk approach

    Directory of Open Access Journals (Sweden)

    J. Connor Langford

    2016-04-01

    Full Text Available With the scale and cost of geotechnical engineering projects increasing rapidly over the past few decades, there is a clear need for the careful consideration of calculated risks in design. While risk is typically dealt with subjectively through the use of conservative design parameters, with the advent of reliability-based methods, this no longer needs to be the case. Instead, a quantitative risk approach can be considered that incorporates uncertainty in ground conditions directly into the design process to determine the variable ground response and support loads. This allows for the optimization of support on the basis of both worker safety and economic risk. This paper presents the application of such an approach to review the design of the initial lining system along a section of the Driskos twin tunnels as part of the Egnatia Odos highway in northern Greece. Along this section of tunnel, weak rock masses were encountered as well as high in situ stress conditions, which led to excessive deformations and failure of the as built temporary support. Monitoring data were used to validate the rock mass parameters selected in this area and a risk approach was used to determine, in hindsight, the most appropriate support category with respect to the cost of installation and expected cost of failure. Different construction sequences were also considered in the context of both convenience and risk cost.

  3. Stochastic optimal generation bid to electricity markets with emissions risk constraints.

    Science.gov (United States)

    Heredia, F-Javier; Cifuentes-Rubiano, Julián; Corchero, Cristina

    2018-02-01

    There are many factors that influence the day-ahead market bidding strategies of a generation company (GenCo) within the framework of the current energy market. Environmental policy issues are giving rise to emission limitation that are becoming more and more important for fossil-fueled power plants, and these must be considered in their management. This work investigates the influence of the emissions reduction plan and the incorporation of the medium-term derivative commitments in the optimal generation bidding strategy for the day-ahead electricity market. Two different technologies have been considered: the high-emission technology of thermal coal units and the low-emission technology of combined cycle gas turbine units. The Iberian Electricity Market (MIBEL) and the Spanish National Emissions Reduction Plan (NERP) defines the environmental framework for dealing with the day-ahead market bidding strategies. To address emission limitations, we have extended some of the standard risk management methodologies developed for financial markets, such as Value-at-Risk (VaR) and Conditional Value-at-Risk (CVaR), thus leading to the new concept of Conditional Emission at Risk (CEaR). This study offers electricity generation utilities a mathematical model for determining the unit's optimal generation bid to the wholesale electricity market such that it maximizes the long-term profits of the utility while allowing it to abide by the Iberian Electricity Market rules as well as the environmental restrictions set by the Spanish National Emissions Reduction Plan. We analyze the economic implications for a GenCo that includes the environmental restrictions of this National Plan as well as the NERP's effects on the expected profits and the optimal generation bid. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Sharing City

    DEFF Research Database (Denmark)

    This magazine offers an insight into the growing commercial innovation, civic movements, and political narratives surrounding sharing economy services, solutions and organisational types. It presents a cross-section of the manifold sharing economy services and solutions that can be found in Denmark....... Moreover, 15 thought leading experts - professionals and academic - have been invited to give their perspective on sharing economy for cities. This magazine touches upon aspects of the sharing economy as mobility, communities, sustainability, business development, mobility, and urban-rural relation....

  5. Risk-Optimized Design of Production Systems by Use of GRAMOSA

    Directory of Open Access Journals (Sweden)

    Michael Lütjen

    2014-01-01

    Full Text Available Today production and logistic systems are getting more complex. This is a problem which the planning and design of such systems have to deal with. One main issue of production system development in series production is the planning of production processes and systems under uncertainty. New and existing production technologies are often not fully adoptable to new products. This is why some of the main characteristics, like, for example, cost, time, or quality, are not definable at the beginning. Only value ranges and probabilities can be estimated. However, the adaptation process is controllable, which means that the adaptation results are depending on the existing development budget and its resources. This paper presents an approach for the optimized allocation of development resources regarding the adaptation risks of production technologies and processes. The modeling concept GRAMOSA is used for integrated modeling and discrete event-based simulation of the aspired production system. To this end a domain-specific modeling language (DSML is applied. The further risk-based analysis of the simulation results and the optimized allocation of the development budget are done by use of mathematical optimization.

  6. Comparative Pessimism or Optimism: Depressed Mood, Risk-Taking, Social Utility and Desirability.

    Science.gov (United States)

    Milhabet, Isabelle; Le Barbenchon, Emmanuelle; Cambon, Laurent; Molina, Guylaine

    2015-03-05

    Comparative optimism can be defined as a self-serving, asymmetric judgment of the future. It is often thought to be beneficial and socially accepted, whereas comparative pessimism is correlated with depression and socially rejected. Our goal was to examine the social acceptance of comparative optimism and the social rejection of comparative pessimism in two dimensions of social judgment, social desirability and social utility, considering the attributions of dysphoria and risk-taking potential (studies 2 and 3) on outlooks on the future. In three experiments, the participants assessed either one (study 1) or several (studies 2 and 3) fictional targets in two dimensions, social utility and social desirability. Targets exhibiting comparatively optimistic or pessimistic outlooks on the future were presented as non-depressed, depressed, or neither (control condition) (study 1); non-depressed or depressed (study 2); and non-depressed or in control condition (study 3). Two significant results were obtained: (1) social rejection of comparative pessimism in the social desirability dimension, which can be explained by its depressive feature; and (2) comparative optimism was socially accepted on the social utility dimension, which can be explained by the perception that comparatively optimistic individuals are potential risk-takers.

  7. Multi-objective portfolio optimization of mutual funds under downside risk measure using fuzzy theory

    Directory of Open Access Journals (Sweden)

    M. Amiri

    2012-10-01

    Full Text Available Mutual fund is one of the most popular techniques for many people to invest their funds where a professional fund manager invests people's funds based on some special predefined objectives; therefore, performance evaluation of mutual funds is an important problem. This paper proposes a multi-objective portfolio optimization to offer asset allocation. The proposed model clusters mutual funds with two methods based on six characteristics including rate of return, variance, semivariance, turnover rate, Treynor index and Sharpe index. Semivariance is used as a downside risk measure. The proposed model of this paper uses fuzzy variables for return rate and semivariance. A multi-objective fuzzy mean-semivariance portfolio optimization model is implemented and fuzzy programming technique is adopted to solve the resulted problem. The proposed model of this paper has gathered the information of mutual fund traded on Nasdaq from 2007 to 2009 and Pareto optimal solutions are obtained considering different weights for objective functions. The results of asset allocation, rate of return and risk of each cluster are also determined and they are compared with the results of two clustering methods.

  8. Optimization (Alara) and probabilistic exposures: the application of optimization criteria to the control of risks due to exposures of a probabilistic nature

    International Nuclear Information System (INIS)

    Gonzalez, A.J.

    1989-01-01

    The paper described the application of the principles of optimization recommended by the International Commission on Radiological Protection (ICRP) to the restrain of radiation risks due to exposures that may or may not be incurred and to which a probability of occurrence can be assigned. After describing the concept of probabilistic exposures, it proposes a basis for a converging policy of control for both certain and probabilistic exposures, namely the dose-risk relationship adopted for radiation protection purposes. On that basis some coherent approaches for dealing with probabilistic exposures, such as the limitation of individual risks, are discussed. The optimization of safety for reducing all risks from probabilistic exposures to as-low-as-reasonably-achievable (ALARA) levels is reviewed in full. The principles of optimization of protection are used as a basic framework and the relevant factors to be taken into account when moving to probabilistic exposures are presented. The paper also reviews the decision-aiding techniques suitable for performing optimization with particular emphasis to the multi-attribute utility-analysis technique. Finally, there is a discussion on some practical application of decision-aiding multi-attribute utility analysis to probabilistic exposures including the use of probabilistic utilities. In its final outlook, the paper emphasizes the need for standardization and solutions to generic problems, if optimization of safety is to be successful

  9. Effective pseudonymisation and explicit statements of public interest to ensure the benefits of sharing health data for research, quality improvement and health service management outweigh the risks

    Directory of Open Access Journals (Sweden)

    Simon de Lusignan

    2014-05-01

    Full Text Available This journal strongly supports the sharing of data to support research and quality improvement. However, this needs to be done in a way that ensures the benefits vastly outweigh the risks, and vitally using methods which are inspire both public and professional confidences – robust pseudonymisation is needed to achieve this. The case for using routine data for research has already been well made and probably also for quality improvement; however, clearer mechanisms are needed of how we test that the public interest is served. Ensuring that the public interest is served is essential if we are to maintain patients’ and public’s trust, especially in the English National Health Service where the realpolitik is that patients can opt out of data sharing.  

  10. .: Risk sharing in the paper ticket distribution system on the example of municipal transport union of the upper Silesian industrial district in Katowice

    Directory of Open Access Journals (Sweden)

    Anna URBANEK

    2015-03-01

    Full Text Available Properly organized ticket distribution is a crucial tool to realize tariff policy of public passenger transport provider in the given area, as well as the factor influencing the ticket sale profits. Providing the proper accessibility of public communication ticket sale network requires signing contracts with third parties, which is consequently connected with the necessity to divide the tasks and responsibilities among them, which generates certain risk for each of the parties. In the article the types of risks have been discussed, as well as the methods of its sharing in case of agreements concerning public communication paper ticket distribution. Based on the example of the Municipal Transport Union of the Upper Silesian Industrial District in Katowice, the types of such agreements have been presented as well as their influence on organizing urban communication ticket distribution system in Silesian agglomeration. The paper presents a new approach to risk management as an important part of integration strategy of urban transport organizer.

  11. Optimal timing of vitamin K antagonist resumption after upper gastrointestinal bleeding. A risk modelling analysis.

    Science.gov (United States)

    Majeed, Ammar; Wallvik, Niklas; Eriksson, Joakim; Höijer, Jonas; Bottai, Matteo; Holmström, Margareta; Schulman, Sam

    2017-02-28

    The optimal timing of vitamin K antagonists (VKAs) resumption after an upper gastrointestinal (GI) bleeding, in patients with continued indication for oral anticoagulation, is uncertain. We included consecutive cases of VKA-associated upper GI bleeding from three hospitals retrospectively. Data on the bleeding location, timing of VKA resumption, recurrent GI bleeding and thromboembolic events were collected. A model was constructed to evaluate the 'total risk', based on the sum of the cumulative rates of recurrent GI bleeding and thromboembolic events, depending on the timing of VKA resumption. A total of 121 (58 %) of 207 patients with VKA-associated upper GI bleeding were restarted on anticoagulation after a median (interquartile range) of one (0.2-3.4) week after the index bleeding. Restarting VKAs was associated with a reduced risk of thromboembolism (HR 0.19; 95 % CI, 0.07-0.55) and death (HR 0.61; 95 % CI, 0.39-0.94), but with an increased risk of recurrent GI bleeding (HR 2.5; 95 % CI, 1.4-4.5). The composite risk obtained from the combined statistical model of recurrent GI bleeding, and thromboembolism decreased if VKAs were resumed after three weeks and reached a nadir at six weeks after the index GI bleeding. On this background we will discuss how the disutility of the outcomes may influence the decision regarding timing of resumption. In conclusion, the optimal timing of VKA resumption after VKA-associated upper GI bleeding appears to be between 3-6 weeks after the index bleeding event but has to take into account the degree of thromboembolic risk, patient values and preferences.

  12. File sharing

    NARCIS (Netherlands)

    van Eijk, N.

    2011-01-01

    ‘File sharing’ has become generally accepted on the Internet. Users share files for downloading music, films, games, software etc. In this note, we have a closer look at the definition of file sharing, the legal and policy-based context as well as enforcement issues. The economic and cultural

  13. Shared leadership

    DEFF Research Database (Denmark)

    Ulhøi, John Parm; Müller, Sabine

    2012-01-01

    The aim of this paper is twofold. First, this paper comprehensively will review the conceptual and empirical literature to identify such critical underlying mechanisms which enable shared or collective leadership. Second, this article identifies the antecedents and outcomes of shared leadership...... according to the literature review to develop a re-conceptualised and synthesized framework for managing the organizational issues associated with shared leadership on various organizational levels. The paper rectifies this by identifying the critical factors and mechanisms which enable shared leadership...... and its antecedents and outcomes, and to develop a re-conceptualized and synthesized framework of shared leadership. The paper closes with a brief discussion of avenues for future research and implications for managers....

  14. Risk management and statistical multivariate analysis approach for design and optimization of satranidazole nanoparticles.

    Science.gov (United States)

    Dhat, Shalaka; Pund, Swati; Kokare, Chandrakant; Sharma, Pankaj; Shrivastava, Birendra

    2017-01-01

    Rapidly evolving technical and regulatory landscapes of the pharmaceutical product development necessitates risk management with application of multivariate analysis using Process Analytical Technology (PAT) and Quality by Design (QbD). Poorly soluble, high dose drug, Satranidazole was optimally nanoprecipitated (SAT-NP) employing principles of Formulation by Design (FbD). The potential risk factors influencing the critical quality attributes (CQA) of SAT-NP were identified using Ishikawa diagram. Plackett-Burman screening design was adopted to screen the eight critical formulation and process parameters influencing the mean particle size, zeta potential and dissolution efficiency at 30min in pH7.4 dissolution medium. Pareto charts (individual and cumulative) revealed three most critical factors influencing CQA of SAT-NP viz. aqueous stabilizer (Polyvinyl alcohol), release modifier (Eudragit® S 100) and volume of aqueous phase. The levels of these three critical formulation attributes were optimized by FbD within established design space to minimize mean particle size, poly dispersity index, and maximize encapsulation efficiency of SAT-NP. Lenth's and Bayesian analysis along with mathematical modeling of results allowed identification and quantification of critical formulation attributes significantly active on the selected CQAs. The optimized SAT-NP exhibited mean particle size; 216nm, polydispersity index; 0.250, zeta potential; -3.75mV and encapsulation efficiency; 78.3%. The product was lyophilized using mannitol to form readily redispersible powder. X-ray diffraction analysis confirmed the conversion of crystalline SAT to amorphous form. In vitro release of SAT-NP in gradually pH changing media showed 95%) in pH7.4 in next 3h, indicative of burst release after a lag time. This investigation demonstrated effective application of risk management and QbD tools in developing site-specific release SAT-NP by nanoprecipitation. Copyright © 2016 Elsevier B.V. All

  15. Temporal variation of optimal UV exposure time over Korea: risks and benefits of surface UV radiation

    Science.gov (United States)

    Lee, Y. G.; Koo, J. H.

    2015-12-01

    Solar UV radiation in a wavelength range between 280 to 400 nm has both positive and negative influences on human body. Surface UV radiation is the main natural source of vitamin D, providing the promotion of bone and musculoskeletal health and reducing the risk of a number of cancers and other medical conditions. However, overexposure to surface UV radiation is significantly related with the majority of skin cancer, in addition other negative health effects such as sunburn, skin aging, and some forms of eye cataracts. Therefore, it is important to estimate the optimal UV exposure time, representing a balance between reducing negative health effects and maximizing sufficient vitamin D production. Previous studies calculated erythemal UV and vitamin-D UV from the measured and modelled spectral irradiances, respectively, by weighting CIE Erythema and Vitamin D3 generation functions (Kazantzidis et al., 2009; Fioletov et al., 2010). In particular, McKenzie et al. (2009) suggested the algorithm to estimate vitamin-D production UV from erythemal UV (or UV index) and determined the optimum conditions of UV exposure based on skin type Ⅱ according to the Fitzpatrick (1988). Recently, there are various demands for risks and benefits of surface UV radiation on public health over Korea, thus it is necessary to estimate optimal UV exposure time suitable to skin type of East Asians. This study examined the relationship between erythemally weighted UV (UVEry) and vitamin D weighted UV (UVVitD) over Korea during 2004-2012. The temporal variations of the ratio (UVVitD/UVEry) were also analyzed and the ratio as a function of UV index was applied in estimating the optimal UV exposure time. In summer with high surface UV radiation, short exposure time leaded to sufficient vitamin D and erythema and vice versa in winter. Thus, the balancing time in winter was enough to maximize UV benefits and minimize UV risks.

  16. Multiple shooting applied to robust reservoir control optimization including output constraints on coherent risk measures

    DEFF Research Database (Denmark)

    Codas, Andrés; Hanssen, Kristian G.; Foss, Bjarne

    2017-01-01

    The production life of oil reservoirs starts under significant uncertainty regarding the actual economical return of the recovery process due to the lack of oil field data. Consequently, investors and operators make management decisions based on a limited and uncertain description of the reservoir....... In this work, we propose a new formulation for robust optimization of reservoir well controls. It is inspired by the multiple shooting (MS) method which permits a broad range of parallelization opportunities and output constraint handling. This formulation exploits coherent risk measures, a concept...

  17. Portfolio optimization for heavy-tailed assets: Extreme Risk Index vs. Markowitz

    OpenAIRE

    Mainik, Georg; Mitov, Georgi; Rüschendorf, Ludger

    2015-01-01

    Using daily returns of the S&P 500 stocks from 2001 to 2011, we perform a backtesting study of the portfolio optimization strategy based on the extreme risk index (ERI). This method uses multivariate extreme value theory to minimize the probability of large portfolio losses. With more than 400 stocks to choose from, our study seems to be the first application of extreme value techniques in portfolio management on a large scale. The primary aim of our investigation is the potential of ERI in p...

  18. SOCIAL-COMPARISON OF HEALTH RISKS - LOCUS OF CONTROL, THE PERSON-POSITIVITY BIAS, AND UNREALISTIC OPTIMISM

    NARCIS (Netherlands)

    HOORENS, [No Value; BUUNK, BP

    1993-01-01

    People typically attribute lower health risks to themselves than to others, a phenomenon referred to as unrealistic optimism. The present study tested the person positivity bias as a previously unexamined explanation of the phenomenon and analyzed the relationship between unrealistic optimism and

  19. Supporting evidence-based analysis for modified risk tobacco products through a toxicology data-sharing infrastructure [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Stéphanie Boué

    2017-09-01

    Full Text Available The US FDA defines modified risk tobacco products (MRTPs as products that aim to reduce harm or the risk of tobacco-related disease associated with commercially marketed tobacco products.  Establishing a product’s potential as an MRTP requires scientific substantiation including toxicity studies and measures of disease risk relative to those of cigarette smoking.  Best practices encourage verification of the data from such studies through sharing and open standards. Building on the experience gained from the OpenTox project, a proof-of-concept database and website (INTERVALS has been developed to share results from both in vivo inhalation studies and in vitro studies conducted by Philip Morris International R&D to assess candidate MRTPs. As datasets are often generated by diverse methods and standards, they need to be traceable, curated, and the methods used well described so that knowledge can be gained using data science principles and tools. The data-management framework described here accounts for the latest standards of data sharing and research reproducibility. Curated data and methods descriptions have been prepared in ISA-Tab format and stored in a database accessible via a search portal on the INTERVALS website. The portal allows users to browse the data by study or mechanism (e.g., inflammation, oxidative stress and obtain information relevant to study design, methods, and the most important results. Given the successful development of the initial infrastructure, the goal is to grow this initiative and establish a public repository for 21st-century preclinical systems toxicology MRTP assessment data and results that supports open data principles.

  20. Using ensemble weather forecast in a risk based real time optimization of urban drainage systems

    DEFF Research Database (Denmark)

    Courdent, Vianney Augustin Thomas; Vezzaro, Luca; Mikkelsen, Peter Steen

    2015-01-01

    Global Real Time Control (RTC) of urban drainage system is increasingly seen as cost-effective solution in order to respond to increasing performance demand (e.g. reduction of Combined Sewer Overflow, protection of sensitive areas as bathing water etc.). The Dynamic Overflow Risk Assessment (DORA......) strategy was developed to operate Urban Drainage Systems (UDS) in order to minimize the expected overflow risk by considering the water volume presently stored in the drainage network, the expected runoff volume based on a 2-hours radar forecast model and an estimated uncertainty of the runoff forecast....... However, such temporal horizon (1-2 hours) is relatively short when used for the operation of large storage facilities, which may require a few days to be emptied. This limits the performance of the optimization and control in reducing combined sewer overflow and in preparing for possible flooding. Based...

  1. Research on the robust optimization of the enterprise's decision on the investment to the collaborative innovation: Under the risk constraints

    International Nuclear Information System (INIS)

    Zhou, Qing; Fang, Gang; Wang, Dong-peng; Yang, Wei

    2016-01-01

    Abstracts: The robust optimization model is applied to analyze the enterprise's decision of the investment portfolio for the collaborative innovation under the risk constraints. Through the mathematical model deduction and the simulation analysis, the research result shows that the enterprise's investment to the collaborative innovation has relatively obvious robust effect. As for the collaborative innovation, the return from the investment coexists with the risk of it. Under the risk constraints, the robust optimization method could solve the minimum risk as well as the proportion of each investment scheme in the portfolio on the condition of different target returns from the investment. On the basis of the result, the enterprise could balance between the investment return and risk and make optimal decision on the investment scheme.

  2. Stochastic multi-objective model for optimal energy exchange optimization of networked microgrids with presence of renewable generation under risk-based strategies.

    Science.gov (United States)

    Gazijahani, Farhad Samadi; Ravadanegh, Sajad Najafi; Salehi, Javad

    2018-02-01

    The inherent volatility and unpredictable nature of renewable generations and load demand pose considerable challenges for energy exchange optimization of microgrids (MG). To address these challenges, this paper proposes a new risk-based multi-objective energy exchange optimization for networked MGs from economic and reliability standpoints under load consumption and renewable power generation uncertainties. In so doing, three various risk-based strategies are distinguished by using conditional value at risk (CVaR) approach. The proposed model is specified as a two-distinct objective function. The first function minimizes the operation and maintenance costs, cost of power transaction between upstream network and MGs as well as power loss cost, whereas the second function minimizes the energy not supplied (ENS) value. Furthermore, the stochastic scenario-based approach is incorporated into the approach in order to handle the uncertainty. Also, Kantorovich distance scenario reduction method has been implemented to reduce the computational burden. Finally, non-dominated sorting genetic algorithm (NSGAII) is applied to minimize the objective functions simultaneously and the best solution is extracted by fuzzy satisfying method with respect to risk-based strategies. To indicate the performance of the proposed model, it is performed on the modified IEEE 33-bus distribution system and the obtained results show that the presented approach can be considered as an efficient tool for optimal energy exchange optimization of MGs. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

  3. Risk-Assessment Score and Patient Optimization as Cost Predictors for Ventral Hernia Repair.

    Science.gov (United States)

    Saleh, Sherif; Plymale, Margaret A; Davenport, Daniel L; Roth, John Scott

    2018-04-01

    Ventral hernia repair (VHR) is associated with complications that significantly increase healthcare costs. This study explores the associations between hospital costs for VHR and surgical complication risk-assessment scores, need for cardiac or pulmonary evaluation, and smoking or obesity counseling. An IRB-approved retrospective study of patients having undergone open VHR over 3 years was performed. Ventral Hernia Risk Score (VHRS) for surgical site occurrence and surgical site infection, and the Ventral Hernia Working Group grade were calculated for each case. Also recorded were preoperative cardiology or pulmonary evaluations, smoking cessation and weight reduction counseling, and patient goal achievement. Hospital costs were obtained from the cost accounting system for the VHR hospitalization stratified by major clinical cost drivers. Univariate regression analyses were used to compare the predictive power of the risk scores. Multivariable analysis was performed to develop a cost prediction model. The mean cost of index VHR hospitalization was $20,700. Total and operating room costs correlated with increasing CDC wound class, VHRS surgical site infection score, VHRS surgical site occurrence score, American Society of Anesthesiologists class, and Ventral Hernia Working Group (all p variance in costs (p optimization significantly reduced direct and operating room costs (p < 0.05). Cardiac evaluation was associated with increased costs. Ventral hernia repair hospital costs are more accurately predicted by CDC wound class than VHR risk scores. A straightforward 6-factor model predicted most cost variation for VHR. Copyright © 2018 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Application of recourse optimization for risk management of electricity production with weekly and monthly horizon

    International Nuclear Information System (INIS)

    Apparigliato, R.

    2008-06-01

    In this Phd, we focus on the problem of weekly risk management in electric production. In the first part of this work, we investigate how to take into account stochastic inflows in the optimal management of a hydraulic valley. Our model is based on robust optimization and linear decision rules. A validation procedure based on simulation over random scenarios shows that we are able to postpone constraints violations of volume at very low cost. The second part deals with the problem of active management of electrical power margin, defined as the difference between the total offer and the total demand, considering the different random parameters which affect the electrical system. The objective is to determine optimal solutions to be taken in order to satisfy the demand in 99% of the cases. In that purpose, we propose a new open-looped formulation, based on the stochastic process of power margin and on the use of probabilistic constraints. To be able to solve this problem, we generate power margin's scenarios using more realistic methods than those used in exploitation. At last, a closed-loop approach, based on the heuristic 'Stochastic Programming with Step Decision Rules', introduced by Thenie and Vial, is studied. First results are quite promising in comparison with the opened-loop ones. (author)

  5. Optimization method to determine mass transfer variables in a PWR crud deposition risk assessment tool

    International Nuclear Information System (INIS)

    Do, Chuong; Hussey, Dennis; Wells, Daniel M.; Epperson, Kenny

    2016-01-01

    Optimization numerical method was implemented to determine several mass transfer coefficients in a crud-induced power shift risk assessment code. The approach was to utilize a multilevel strategy that targets different model parameters that first changes the major order variables, mass transfer inputs, then calibrates the minor order variables, crud source terms, according to available plant data. In this manner, the mass transfer inputs are effectively simplified as 'dependent' on the crud source terms. Two optimization studies were performed using DAKOTA, a design and analysis toolkit, with the difference between the runs, being the number of model runs using BOA, allowed for adjusting the crud source terms, therefore, reducing the uncertainty with calibration. The result of the first case showed that the current best estimated values for the mass transfer coefficients, which were derived from first principle analysis, can be considered an optimized set. When the run limit of BOA was increased for the second case, an improvement in the prediction was obtained with the results deviating slightly from the best estimated values. (author)

  6. Optimization of a dynamic supply portfolio considering risks and discount’s constraints

    Directory of Open Access Journals (Sweden)

    Masoud Rabbani

    2014-01-01

    Full Text Available Purpose: Nowadays finding reliable suppliers in the global supply chains has become so important for success, because reliable suppliers would lead to a reliable supply and besides that orders of customer are met effectively . Yet, there is little empirical evidence to support this view, hence the purpose of this paper is to fill this need by considering risk in order to find the optimum supply portfolio. Design/methodology/approach: This paper proposes a multi objective model for the supplier selection portfolio problem that uses conditional value at risk (CVaR criteria to control the risks of delayed, disrupted and defected supplies via scenario analysis. Also we consider discount’s constraints which are common assumptions in supplier selection problems. The proposed approach is capable of determining the optimal supply portfolio by calculating value-at-risk and minimizing conditional value-at-risk. In this study the Reservation Level driven Tchebycheff Procedure (RLTP which is one of the reference point methods, is used to solve small size of our model through coding in GAMS. As our model is NP-hard; a meta-heuristic approach, Non-dominated Sorting Genetic Algorithm (NSGA which is one of the most efficient methods for optimizing multi objective models, is applied to solve large scales of our model. Findings and Originality/value: In order to find a dynamic supply portfolio, we developed a Mixed Integer Linear Programming (MILP model which contains two objectives. One objective minimizes the cost and the other minimizes the risks of delayed, disrupted and defected supplies. CVaR is used as the risk controlling method which emphases on low-probability, high-consequence events. Discount option as a common offer from suppliers is also implanted in the proposed model. Our findings show that the proposed model can help in optimization of a dynamic supplier selection portfolio with controlling the corresponding risks for large scales of real word

  7. Knowledge Sharing

    DEFF Research Database (Denmark)

    Holdt Christensen, Peter

    The concept of knowledge management has, indeed, become a buzzword that every single organization is expected to practice and live by. Knowledge management is about managing the organization's knowledge for the common good of the organization -but practicing knowledge management is not as simple...... as that. This article focuses on knowledge sharing as the process seeking to reduce the resources spent on reinventing the wheel.The article introduces the concept of time sensitiveness; i.e. that knowledge is either urgently needed, or not that urgently needed. Furthermore, knowledge sharing...... is considered as either a push or pull system. Four strategies for sharing knowledge - help, post-it, manuals and meeting, and advice are introduced. Each strategy requires different channels for sharing knowledge. An empirical analysis in a production facility highlights how the strategies can be practiced....

  8. On the optimization of a CAPM portfolio using lower partial moments as measure of risk and using the possibility of safeguarding its loss

    Science.gov (United States)

    Spreitzer, U. W.; Reznik, V.

    2007-05-01

    Using a portfolio built from bonds (investment without volatility) and shares (investment with volatility) corresponding to the CAPM we calculate the possible loss of this portfolio. The loss is measured by a so-called lower partial moment of the rate of return of the portfolio. Using this loss, we optimize the composition of the portfolio with respect to this loss. Also we investigate the optimization of the portfolio when the loss can be underwritten by an insurance. Concerning the premium of this insurance contract, we show that when the premium is defined inadequate, e.g. proportional to the investment or proportional to the amount of investment in shares, the optimal portfolio consists only of investment in shares. When the premium is defined more suitable, e.g. proportional to the loss, the optimal portfolio is built by an investment in bonds and shares.

  9. Dispositional optimism and stock investments

    NARCIS (Netherlands)

    Angelini, Viola; Cavapozzi, D.

    This paper analyzes the relationship between dispositional optimism and stock investments, controlling for cognitive skills and personality traits such as trust, social interactions and risk aversion. We use data from the Survey of Health, Ageing and Retirement in Europe (SHARE) on investors aged

  10. Optimization of an In silico Cardiac Cell Model for Proarrhythmia Risk Assessment

    Directory of Open Access Journals (Sweden)

    Sara Dutta

    2017-08-01

    Full Text Available Drug-induced Torsade-de-Pointes (TdP has been responsible for the withdrawal of many drugs from the market and is therefore of major concern to global regulatory agencies and the pharmaceutical industry. The Comprehensive in vitro Proarrhythmia Assay (CiPA was proposed to improve prediction of TdP risk, using in silico models and in vitro multi-channel pharmacology data as integral parts of this initiative. Previously, we reported that combining dynamic interactions between drugs and the rapid delayed rectifier potassium current (IKr with multi-channel pharmacology is important for TdP risk classification, and we modified the original O'Hara Rudy ventricular cell mathematical model to include a Markov model of IKr to represent dynamic drug-IKr interactions (IKr-dynamic ORd model. We also developed a novel metric that could separate drugs with different TdP liabilities at high concentrations based on total electronic charge carried by the major inward ionic currents during the action potential. In this study, we further optimized the IKr-dynamic ORd model by refining model parameters using published human cardiomyocyte experimental data under control and drug block conditions. Using this optimized model and manual patch clamp data, we developed an updated version of the metric that quantifies the net electronic charge carried by major inward and outward ionic currents during the steady state action potential, which could classify the level of drug-induced TdP risk across a wide range of concentrations and pacing rates. We also established a framework to quantitatively evaluate a system's robustness against the induction of early afterdepolarizations (EADs, and demonstrated that the new metric is correlated with the cell's robustness to the pro-EAD perturbation of IKr conductance reduction. In summary, in this work we present an optimized model that is more consistent with experimental data, an improved metric that can classify drugs at

  11. Decision Support and Shared Decision Making About Active Surveillance Versus Active Treatment Among Men Diagnosed with Low-Risk Prostate Cancer: a Pilot Study.

    Science.gov (United States)

    Myers, Ronald E; Leader, Amy E; Censits, Jean Hoffman; Trabulsi, Edouard J; Keith, Scott W; Petrich, Anett M; Quinn, Anna M; Den, Robert B; Hurwitz, Mark D; Lallas, Costas D; Hegarty, Sarah E; Dicker, Adam P; Zeigler-Johnson, Charnita M; Giri, Veda N; Ayaz, Hasan; Gomella, Leonard G

    2018-02-01

    This study aimed to explore the effects of a decision support intervention (DSI) and shared decision making (SDM) on knowledge, perceptions about treatment, and treatment choice among men diagnosed with localized low-risk prostate cancer (PCa). At a multidisciplinary clinic visit, 30 consenting men with localized low-risk PCa completed a baseline survey, had a nurse-mediated online DS session to clarify preference for active surveillance (AS) or active treatment (AT), and met with clinicians for SDM. Participants also completed a follow-up survey at 30 days. We assessed change in treatment knowledge, decisional conflict, and perceptions and identified predictors of AS. At follow-up, participants exhibited increased knowledge (p decision. Perceived support of the decision facilitated patient choice of AS.

  12. Optimism and depression: a new look at social support as a mediator among women at risk for breast cancer.

    Science.gov (United States)

    Garner, Melissa J; McGregor, Bonnie A; Murphy, Karly M; Koenig, Alex L; Dolan, Emily D; Albano, Denise

    2015-12-01

    Breast cancer risk is a chronic stressor associated with depression. Optimism is associated with lower levels of depression among breast cancer survivors. However, to our knowledge, no studies have explored the relationship between optimism and depression among women at risk for breast cancer. We hypothesized that women at risk for breast cancer who have higher levels of optimism would report lower levels of depression and that social support would mediate this relationship. Participants (N = 199) with elevated distress were recruited from the community and completed self-report measures of depression, optimism, and social support. Participants were grouped based on their family history of breast cancer. Path analysis was used to examine the cross-sectional relationship between optimism, social support, and depressive symptoms in each group. Results indicated that the variance in depressive symptoms was partially explained through direct paths from optimism and social support among women with a family history of breast cancer. The indirect path from optimism to depressive symptoms via social support was significant (β = -.053; 90% CI = -.099 to -.011, p = .037) in this group. However, among individuals without a family history of breast cancer, the indirect path from optimism to depressive symptoms via social support was not significant. These results suggest that social support partially mediates the relationship between optimism and depression among women at risk for breast cancer. Social support may be an important intervention target to reduce depression among women at risk for breast cancer. Copyright © 2015 John Wiley & Sons, Ltd.

  13. Optimal predator risk assessment by the sonar-jamming arctiine moth Bertholdia trigona.

    Directory of Open Access Journals (Sweden)

    Aaron J Corcoran

    Full Text Available Nearly all animals face a tradeoff between seeking food and mates and avoiding predation. Optimal escape theory holds that an animal confronted with a predator should only flee when benefits of flight (increased survival outweigh the costs (energetic costs, lost foraging time, etc.. We propose a model for prey risk assessment based on the predator's stage of attack. Risk level should increase rapidly from when the predator detects the prey to when it commits to the attack. We tested this hypothesis using a predator--the echolocating bat--whose active biosonar reveals its stage of attack. We used a prey defense--clicking used for sonar jamming by the tiger moth Bertholdia trigona--that can be readily studied in the field and laboratory and is enacted simultaneously with evasive flight. We predicted that prey employ defenses soon after being detected and targeted, and that prey defensive thresholds discriminate between legitimate predatory threats and false threats where a nearby prey is attacked. Laboratory and field experiments using playbacks of ultrasound signals and naturally behaving bats, respectively, confirmed our predictions. Moths clicked soon after bats detected and targeted them. Also, B. trigona clicking thresholds closely matched predicted optimal thresholds for discriminating legitimate and false predator threats for bats using search and approach phase echolocation--the period when bats are searching for and assessing prey. To our knowledge, this is the first quantitative study to correlate the sensory stimuli that trigger defensive behaviors with measurements of signals provided by predators during natural attacks in the field. We propose theoretical models for explaining prey risk assessment depending on the availability of cues that reveal a predator's stage of attack.

  14. Optimal Predator Risk Assessment by the Sonar-Jamming Arctiine Moth Bertholdia trigona

    Science.gov (United States)

    Corcoran, Aaron J.; Wagner, Ryan D.; Conner, William E.

    2013-01-01

    Nearly all animals face a tradeoff between seeking food and mates and avoiding predation. Optimal escape theory holds that an animal confronted with a predator should only flee when benefits of flight (increased survival) outweigh the costs (energetic costs, lost foraging time, etc.). We propose a model for prey risk assessment based on the predator's stage of attack. Risk level should increase rapidly from when the predator detects the prey to when it commits to the attack. We tested this hypothesis using a predator – the echolocating bat – whose active biosonar reveals its stage of attack. We used a prey defense – clicking used for sonar jamming by the tiger moth Bertholdia trigona– that can be readily studied in the field and laboratory and is enacted simultaneously with evasive flight. We predicted that prey employ defenses soon after being detected and targeted, and that prey defensive thresholds discriminate between legitimate predatory threats and false threats where a nearby prey is attacked. Laboratory and field experiments using playbacks of ultrasound signals and naturally behaving bats, respectively, confirmed our predictions. Moths clicked soon after bats detected and targeted them. Also, B. trigona clicking thresholds closely matched predicted optimal thresholds for discriminating legitimate and false predator threats for bats using search and approach phase echolocation – the period when bats are searching for and assessing prey. To our knowledge, this is the first quantitative study to correlate the sensory stimuli that trigger defensive behaviors with measurements of signals provided by predators during natural attacks in the field. We propose theoretical models for explaining prey risk assessment depending on the availability of cues that reveal a predator's stage of attack. PMID:23671686

  15. Communicating and Sharing in the Semantic Web: An Examination of Social Media Risks, Consequences, and Attitudinal Awareness

    Directory of Open Access Journals (Sweden)

    Nicole A. Buzzetto-More

    2015-05-01

    Full Text Available Empowered by and tethered to ubiquitous technologies, the current generation of youth yearns for opportunities to engage in self-expression and information sharing online with personal disclosure no longer governed by concepts of propriety and privacy. This raises issues about the unsafe online activities of teens and young adults. The following paper presents the findings of a study examining the social networking activities of undergraduate students and also highlights a program to increase awareness of the dangers and safe practices when using and communicating, via social media. According to the survey results, young adults practice risky social networking site (SNS behaviors with most having experienced at least one negative consequence. Further, females were more likely than males to engage in oversharing as well as to have experienced negative consequences. Finally, results of a post-treatment survey found that a targeted program that includes flyers, posters, YouTube videos, handouts, and in-class information sessions conducted at a Mid-Atlantic Historically Black College or University (HBCU increased student awareness of the dangers of social media as well as positively influenced students to practice more prudent online behaviors.

  16. An optimization-based approach for facility energy management with uncertainties, and, Power portfolio optimization in deregulated electricity markets with risk management

    Science.gov (United States)

    Xu, Jun

    Topic 1. An Optimization-Based Approach for Facility Energy Management with Uncertainties. Effective energy management for facilities is becoming increasingly important in view of the rising energy costs, the government mandate on the reduction of energy consumption, and the human comfort requirements. This part of dissertation presents a daily energy management formulation and the corresponding solution methodology for HVAC systems. The problem is to minimize the energy and demand costs through the control of HVAC units while satisfying human comfort, system dynamics, load limit constraints, and other requirements. The problem is difficult in view of the fact that the system is nonlinear, time-varying, building-dependent, and uncertain; and that the direct control of a large number of HVAC components is difficult. In this work, HVAC setpoints are the control variables developed on top of a Direct Digital Control (DDC) system. A method that combines Lagrangian relaxation, neural networks, stochastic dynamic programming, and heuristics is developed to predict the system dynamics and uncontrollable load, and to optimize the setpoints. Numerical testing and prototype implementation results show that our method can effectively reduce total costs, manage uncertainties, and shed the load, is computationally efficient. Furthermore, it is significantly better than existing methods. Topic 2. Power Portfolio Optimization in Deregulated Electricity Markets with Risk Management. In a deregulated electric power system, multiple markets of different time scales exist with various power supply instruments. A load serving entity (LSE) has multiple choices from these instruments to meet its load obligations. In view of the large amount of power involved, the complex market structure, risks in such volatile markets, stringent constraints to be satisfied, and the long time horizon, a power portfolio optimization problem is of critical importance but difficulty for an LSE to serve the

  17. A risk explicit interval linear programming model for uncertainty-based environmental economic optimization in the Lake Fuxian watershed, China.

    Science.gov (United States)

    Zhang, Xiaoling; Huang, Kai; Zou, Rui; Liu, Yong; Yu, Yajuan

    2013-01-01

    The conflict of water environment protection and economic development has brought severe water pollution and restricted the sustainable development in the watershed. A risk explicit interval linear programming (REILP) method was used to solve integrated watershed environmental-economic optimization problem. Interval linear programming (ILP) and REILP models for uncertainty-based environmental economic optimization at the watershed scale were developed for the management of Lake Fuxian watershed, China. Scenario analysis was introduced into model solution process to ensure the practicality and operability of optimization schemes. Decision makers' preferences for risk levels can be expressed through inputting different discrete aspiration level values into the REILP model in three periods under two scenarios. Through balancing the optimal system returns and corresponding system risks, decision makers can develop an efficient industrial restructuring scheme based directly on the window of "low risk and high return efficiency" in the trade-off curve. The representative schemes at the turning points of two scenarios were interpreted and compared to identify a preferable planning alternative, which has the relatively low risks and nearly maximum benefits. This study provides new insights and proposes a tool, which was REILP, for decision makers to develop an effectively environmental economic optimization scheme in integrated watershed management.

  18. A Risk Explicit Interval Linear Programming Model for Uncertainty-Based Environmental Economic Optimization in the Lake Fuxian Watershed, China

    Directory of Open Access Journals (Sweden)

    Xiaoling Zhang

    2013-01-01

    Full Text Available The conflict of water environment protection and economic development has brought severe water pollution and restricted the sustainable development in the watershed. A risk explicit interval linear programming (REILP method was used to solve integrated watershed environmental-economic optimization problem. Interval linear programming (ILP and REILP models for uncertainty-based environmental economic optimization at the watershed scale were developed for the management of Lake Fuxian watershed, China. Scenario analysis was introduced into model solution process to ensure the practicality and operability of optimization schemes. Decision makers’ preferences for risk levels can be expressed through inputting different discrete aspiration level values into the REILP model in three periods under two scenarios. Through balancing the optimal system returns and corresponding system risks, decision makers can develop an efficient industrial restructuring scheme based directly on the window of “low risk and high return efficiency” in the trade-off curve. The representative schemes at the turning points of two scenarios were interpreted and compared to identify a preferable planning alternative, which has the relatively low risks and nearly maximum benefits. This study provides new insights and proposes a tool, which was REILP, for decision makers to develop an effectively environmental economic optimization scheme in integrated watershed management.

  19. Moving toward comprehensive acute heart failure risk assessment in the emergency department: the importance of self-care and shared decision making.

    Science.gov (United States)

    Collins, Sean P; Storrow, Alan B

    2013-08-01

    Nearly 700,000 emergency department (ED) visits were due to acute heart failure (AHF) in 2009. Most visits result in a hospital admission and account for the largest proportion of a projected $70 billion to be spent on heart failure care by 2030. ED-based risk prediction tools in AHF rarely impact disposition decision making. This is a major factor contributing to the 80% admission rate for ED patients with AHF, which has remained unchanged over the last several years. Self-care behaviors such as symptom monitoring, medication taking, dietary adherence, and exercise have been associated with decreased hospital readmissions, yet self-care remains largely unaddressed in ED patients with AHF and thus represents a significant lost opportunity to improve patient care and decrease ED visits and hospitalizations. Furthermore, shared decision making encourages collaborative interaction between patients, caregivers, and providers to drive a care path based on mutual agreement. The observation that “difficult decisions now will simplify difficult decisions later” has particular relevance to the ED, given this is the venue for many such issues. We hypothesize patients as complex and heterogeneous as ED patients with AHF may need both an objective evaluation of physiologic risk as well as an evaluation of barriers to ideal self-care, along with strategies to overcome these barriers. Combining physician gestalt, physiologic risk prediction instruments, an evaluation of self-care, and an information exchange between patient and provider using shared decision making may provide the critical inertia necessary to discharge patients home after a brief ED evaluation.

  20. Model-based clinical dose optimization for phenobarbital in neonates: An illustration of the importance of data sharing and external validation

    NARCIS (Netherlands)

    Völler, S. (Swantje); R. Flint (Robert); L. Stolk (Lisette); Degraeuwe, P.L.J. (Pieter L.J.); S.H. Simons (Sinno); P. Pokorna (Pavla); D.M. Burger (David); de Groot, R. (Ronald); D. Tibboel (Dick); C.A.J. Knibbe (Catherijne)

    2017-01-01

    textabstractBackground: Particularly in the pediatric clinical pharmacology field, data-sharing offers the possibility of making the most of all available data. In this study, we utilize previously collected therapeutic drug monitoring (TDM) data of term and preterm newborns to develop a population

  1. Risk-weighted optimization for cyclic steam stimulation of water-underlain reservoirs

    International Nuclear Information System (INIS)

    Mehra, R.K.; Ding, L.Y.; Donnelly, J.K.

    1991-01-01

    The paper describes the procedure that was adopted to develop operating guidelines for the cyclic steam stimulation process in a water underlain oil sands reservoir. The study consisted of three parts: i) The risks associated with fracturing into water sands were quantified by conducting a stochastic simulation; ii) Numerical simulations were conducted to obtain correlations among the cumulative production volumes and six selected operating variables; iii) These correlations were subsequently embodied in the economic model to maximize the profits under different constraints. The study concluded that rather than a unique value, a wide range of operating conditions maximized the project profitability. It recommended that a cautious approach in exploitation of these resources was warranted since the penalty for selecting non-optimal conditions was not high

  2. Optimizing risk stratification in heart failure and the selection of candidates for heart transplantation.

    Science.gov (United States)

    Pereira-da-Silva, Tiago; M Soares, Rui; Papoila, Ana Luísa; Pinto, Iola; Feliciano, Joana; Almeida-Morais, Luís; Abreu, Ana; Cruz Ferreira, Rui

    2018-02-01

    Selecting patients for heart transplantation is challenging. We aimed to identify the most important risk predictors in heart failure and an approach to optimize the selection of candidates for heart transplantation. Ambulatory patients followed in our center with symptomatic heart failure and left ventricular ejection fraction ≤40% prospectively underwent a comprehensive baseline assessment including clinical, laboratory, electrocardiographic, echocardiographic, and cardiopulmonary exercise testing parameters. All patients were followed for 60 months. The combined endpoint was cardiac death, urgent heart transplantation or need for mechanical circulatory support, up to 36 months. In the 263 enrolled patients (75% male, age 54±12 years), 54 events occurred. The independent predictors of adverse outcome were ventilatory efficiency (VE/VCO 2 ) slope (HR 1.14, 95% CI 1.11-1.18), creatinine level (HR 2.23, 95% CI 1.14-4.36), and left ventricular ejection fraction (HR 0.96, 95% CI 0.93-0.99). VE/VCO 2 slope was the most accurate risk predictor at any follow-up time analyzed (up to 60 months). The threshold of 39.0 yielded high specificity (97%), discriminated a worse or better prognosis than that reported for post-heart transplantation, and outperformed peak oxygen consumption thresholds of 10.0 or 12.0 ml/kg/min. For low-risk patients (VE/VCO 2 slope <39.0), sodium and creatinine levels and variations in end-tidal carbon dioxide partial pressure on exercise identified those with excellent prognosis. VE/VCO 2 slope was the most accurate parameter for risk stratification in patients with heart failure and reduced ejection fraction. Those with VE/VCO 2 slope ≥39.0 may benefit from heart transplantation. Copyright © 2018 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  3. Breast Cancer-Related Arm Lymphedema: Incidence Rates, Diagnostic Techniques, Optimal Management and Risk Reduction Strategies

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Chirag [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States); Vicini, Frank A., E-mail: fvicini@beaumont.edu [Department of Radiation Oncology, William Beaumont Hospital, Royal Oak, MI (United States)

    2011-11-15

    As more women survive breast cancer, long-term toxicities affecting their quality of life, such as lymphedema (LE) of the arm, gain importance. Although numerous studies have attempted to determine incidence rates, identify optimal diagnostic tests, enumerate efficacious treatment strategies and outline risk reduction guidelines for breast cancer-related lymphedema (BCRL), few groups have consistently agreed on any of these issues. As a result, standardized recommendations are still lacking. This review will summarize the latest data addressing all of these concerns in order to provide patients and health care providers with optimal, contemporary recommendations. Published incidence rates for BCRL vary substantially with a range of 2-65% based on surgical technique, axillary sampling method, radiation therapy fields treated, and the use of chemotherapy. Newer clinical assessment tools can potentially identify BCRL in patients with subclinical disease with prospective data suggesting that early diagnosis and management with noninvasive therapy can lead to excellent outcomes. Multiple therapies exist with treatments defined by the severity of BCRL present. Currently, the standard of care for BCRL in patients with significant LE is complex decongestive physiotherapy (CDP). Contemporary data also suggest that a multidisciplinary approach to the management of BCRL should begin prior to definitive treatment for breast cancer employing patient-specific surgical, radiation therapy, and chemotherapy paradigms that limit risks. Further, prospective clinical assessments before and after treatment should be employed to diagnose subclinical disease. In those patients who require aggressive locoregional management, prophylactic therapies and the use of CDP can help reduce the long-term sequelae of BCRL.

  4. Breast Cancer-Related Arm Lymphedema: Incidence Rates, Diagnostic Techniques, Optimal Management and Risk Reduction Strategies

    International Nuclear Information System (INIS)

    Shah, Chirag; Vicini, Frank A.

    2011-01-01

    As more women survive breast cancer, long-term toxicities affecting their quality of life, such as lymphedema (LE) of the arm, gain importance. Although numerous studies have attempted to determine incidence rates, identify optimal diagnostic tests, enumerate efficacious treatment strategies and outline risk reduction guidelines for breast cancer–related lymphedema (BCRL), few groups have consistently agreed on any of these issues. As a result, standardized recommendations are still lacking. This review will summarize the latest data addressing all of these concerns in order to provide patients and health care providers with optimal, contemporary recommendations. Published incidence rates for BCRL vary substantially with a range of 2–65% based on surgical technique, axillary sampling method, radiation therapy fields treated, and the use of chemotherapy. Newer clinical assessment tools can potentially identify BCRL in patients with subclinical disease with prospective data suggesting that early diagnosis and management with noninvasive therapy can lead to excellent outcomes. Multiple therapies exist with treatments defined by the severity of BCRL present. Currently, the standard of care for BCRL in patients with significant LE is complex decongestive physiotherapy (CDP). Contemporary data also suggest that a multidisciplinary approach to the management of BCRL should begin prior to definitive treatment for breast cancer employing patient-specific surgical, radiation therapy, and chemotherapy paradigms that limit risks. Further, prospective clinical assessments before and after treatment should be employed to diagnose subclinical disease. In those patients who require aggressive locoregional management, prophylactic therapies and the use of CDP can help reduce the long-term sequelae of BCRL.

  5. Incidence, outcomes, and risk factors for retreatment after wavefront-optimized ablations with PRK and LASIK.

    Science.gov (United States)

    Randleman, J Bradley; White, Alfred J; Lynn, Michael J; Hu, Michelle H; Stulting, R Doyle

    2009-03-01

    To analyze and compare retreatment rates after wavefront-optimized photorefractive keratectomy (PRK) and LASIK and determine risk factors for retreatment. A retrospective chart review was performed to identify patients undergoing PRK or LASIK with the wavefront-optimized WaveLight platform from January 2005 through December 2006 targeted for a piano outcome and to determine the rate and risk factors for retreatment surgery in this population. Eight hundred fifty-five eyes were analyzed, including 70 (8.2%) eyes with hyperopic refractions and 785 (91.8%) eyes with myopic refractions. After initial treatment, 72% of eyes were 20/20 or better and 99.5% were 20/40 or better. To improve uncorrected visual acuity, 54 (6.3%) eyes had retreatments performed. No significant differences in retreatment rates were noted based on age (P = .15), sex (P = .8), eye (P = .3), PRK versus LASIK (P = 1.0), room temperature (P = .1) or humidity (P = .9), and no correlation between retreatment rate and month or season of primary surgery (P = .4). There was no correlation between degree of myopia and retreatment rate. Eyes were significantly more likely to undergo retreatment if they were hyperopic (12.8% vs 6.0%, P = .006) or had astigmatism > or = 1.00 diopter (D) (9.1% vs 5.3%, P = .04). Retreatment rate was 6.3% with the WaveLight ALLEGRETTO WAVE excimer laser. This rate was not influenced by age, sex, corneal characteristics, or environmental factors. Eyes with hyperopic refractions or astigmatism > or = 1.00 D were more likely to undergo retreatment.

  6. Determining the optimal screening interval for type 2 diabetes mellitus using a risk prediction model.

    Directory of Open Access Journals (Sweden)

    Andrei Brateanu

    Full Text Available Progression to diabetes mellitus (DM is variable and the screening time interval not well defined. The American Diabetes Association and US Preventive Services Task Force suggest screening every 3 years, but evidence is limited. The objective of the study was to develop a model to predict the probability of developing DM and suggest a risk-based screening interval.We included non-diabetic adult patients screened for DM in the Cleveland Clinic Health System if they had at least two measurements of glycated hemoglobin (HbA1c, an initial one less than 6.5% (48 mmol/mol in 2008, and another between January, 2009 and December, 2013. Cox proportional hazards models were created. The primary outcome was DM defined as HbA1C greater than 6.4% (46 mmol/mol. The optimal rescreening interval was chosen based on the predicted probability of developing DM.Of 5084 participants, 100 (4.4% of the 2281 patients with normal HbA1c and 772 (27.5% of the 2803 patients with prediabetes developed DM within 5 years. Factors associated with developing DM included HbA1c (HR per 0.1 units increase 1.20; 95%CI, 1.13-1.27, family history (HR 1.31; 95%CI, 1.13-1.51, smoking (HR 1.18; 95%CI, 1.03-1.35, triglycerides (HR 1.01; 95%CI, 1.00-1.03, alanine aminotransferase (HR 1.07; 95%CI, 1.03-1.11, body mass index (HR 1.06; 95%CI, 1.01-1.11, age (HR 0.95; 95%CI, 0.91-0.99 and high-density lipoproteins (HR 0.93; 95% CI, 0.90-0.95. Five percent of patients in the highest risk tertile developed DM within 8 months, while it took 35 months for 5% of the middle tertile to develop DM. Only 2.4% percent of the patients in the lowest tertile developed DM within 5 years.A risk prediction model employing commonly available data can be used to guide screening intervals. Based on equal intervals for equal risk, patients in the highest risk category could be rescreened after 8 months, while those in the intermediate and lowest risk categories could be rescreened after 3 and 5 years

  7. Knowledge Sharing for Disaster Risk Reduction: Insights from a Glacier Lake Workshop in the Ladakh Region, Indian Himalayas

    Directory of Open Access Journals (Sweden)

    Naho Ikeda

    2016-02-01

    Full Text Available Small glacier lakes are distributed in the Ladakh Range in northwestern India. This area has experienced several glacier lake outburst floods (GLOFs since the 1970s, damaging settlements along streams. To reduce GLOF risk through a knowledge-based approach focused on nonstructural measures, we held a workshop in May 2012 for residents of Domkhar Village in the northwestern part of the Ladakh Range. More than 100 villagers participated in the workshop, which conveyed useful disaster information to participants while enabling the researchers to understand local knowledge and beliefs about floods. A survey conducted 3 months later confirmed an improvement in residents’ knowledge of natural disasters. The researchers also learned useful lessons, such as the need to adjust the program design for diverse participants and the importance of clearly communicating disaster risks and supporting local residents’ attempts to incorporate new scientific knowledge into existing local knowledge. Challenges to implementing flood countermeasures in this area included problems relating to land use and emergency communications and the need for coordination of efforts by the government and local residents.

  8. Achieving involvement: process outcomes from a cluster randomized trial of shared decision making skill development and use of risk communication aids in general practice.

    Science.gov (United States)

    Elwyn, G; Edwards, A; Hood, K; Robling, M; Atwell, C; Russell, I; Wensing, M; Grol, R

    2004-08-01

    A consulting method known as 'shared decision making' (SDM) has been described and operationalized in terms of several 'competences'. One of these competences concerns the discussion of the risks and benefits of treatment or care options-'risk communication'. Few data exist on clinicians' ability to acquire skills and implement the competences of SDM or risk communication in consultations with patients. The aims of this study were to evaluate the effects of skill development workshops for SDM and the use of risk communication aids on the process of consultations. A cluster randomized trial with crossover was carried out with the participation of 20 recently qualified GPs in urban and rural general practices in Gwent, South Wales. A total of 747 patients with known atrial fibrillation, prostatism, menorrhagia or menopausal symptoms were invited to a consultation to review their condition or treatments. Half the consultations were randomly selected for audio-taping, of which 352 patients attended and were audio-taped successfully. After baseline, participating doctors were randomized to receive training in (i) SDM skills or (ii) the use of simple risk communication aids, using simulated patients. The alternative training was then provided for the final study phase. Patients were allocated randomly to a consultation during baseline or intervention 1 (SDM or risk communication aids) or intervention 2 phases. A randomly selected half of the consultations were audio-taped from each phase. Raters (independent, trained and blinded to study phase) assessed the audio-tapes using a validated scale to assess levels of patient involvement (OPTION: observing patient involvement), and to analyse the nature of risk information discussed. Clinicians completed questionnaires after each consultation, assessing perceived clinician-patient agreement and level of patient involvement in decisions. Multilevel modelling was carried out with the OPTION score as the dependent variable, and

  9. Actions on climate change, Intended Reducing carbon emissions in China via optimal industry shifts: Toward hi-tech industries, cleaner resources and higher carbon shares in less-develop regions

    International Nuclear Information System (INIS)

    Fu, Xue; Lahr, Michael; Yaxiong, Zhang; Meng, Bo

    2017-01-01

    This paper uses an optimal interregional input-output model to focus on how interregional industrial shifts alone might enable China to reduce carbon intensity instead of national shifts. The optimal industry shifts assure integration of all regions by regional products and goods in which carbon emissions are embodied via energy consumption. Generally speaking, high-tech industries concentrate in affluent regions to replace construction. Selected services increase output shares across most of regions. Meanwhile, energy-intensive manufacturing, rather than agriculture, decrease their shares to achieve the national annual growth constrained by nation’s carbon targets. Due to the need to decelerate energy use, carbon intensity goal puts particularly extreme pressure on less-developed regions to shutter heavy industries. Explicit shifts toward cleaner resources and renewable energy appear to be quite important for coal mines in Central China. - Highlights: • The model optimizes GDP constrained by industry-based emissions targets. • Scenario on carbon intensity, growth rate, energy mix, and technology advance. • Interregional I-O table informs technology, industry mix, and interregional trade. • China could raise the output of high-tech in South Coast and of selected services. • Shifts toward cleaner resources and renewable energy are important in the Central.

  10. Optimal Bi-Objective Redundancy Allocation for Systems Reliability and Risk Management.

    Science.gov (United States)

    Govindan, Kannan; Jafarian, Ahmad; Azbari, Mostafa E; Choi, Tsan-Ming

    2016-08-01

    In the big data era, systems reliability is critical to effective systems risk management. In this paper, a novel multiobjective approach, with hybridization of a known algorithm called NSGA-II and an adaptive population-based simulated annealing (APBSA) method is developed to solve the systems reliability optimization problems. In the first step, to create a good algorithm, we use a coevolutionary strategy. Since the proposed algorithm is very sensitive to parameter values, the response surface method is employed to estimate the appropriate parameters of the algorithm. Moreover, to examine the performance of our proposed approach, several test problems are generated, and the proposed hybrid algorithm and other commonly known approaches (i.e., MOGA, NRGA, and NSGA-II) are compared with respect to four performance measures: 1) mean ideal distance; 2) diversification metric; 3) percentage of domination; and 4) data envelopment analysis. The computational studies have shown that the proposed algorithm is an effective approach for systems reliability and risk management.

  11. Optimal use of β-blockers in high-risk hypertension: A guide to dosing equivalence

    Directory of Open Access Journals (Sweden)

    Janet B McGill

    2010-05-01

    Full Text Available Janet B McGillDepartment of Medicine, Washington University School of Medicine, St. Louis, Missouri, USAAbstract: Hypertension is the number one diagnosis made by primary care physicians, placing them in a unique position to prescribe the antihypertensive agent best suited to the individual patient. In individuals with diabetes mellitus, blood pressure (BP levels > 130/80 mmHg confer an even higher risk for cardiovascular and renal disease, and these patients will benefit from aggressive antihypertensive treatment using a combination of agents. β‑blockers are playing an increasingly important role in the management of hypertension in high-risk patients. β‑blockers are a heterogeneous class of agents, and this review presents the differences between β‑blockers and provides evidence-based protocols to assist in understanding dose equivalence in the selection of an optimal regimen in patients with complex needs. The clinical benefits provided by β‑blockers are only effective if patients adhere to medication treatment long term. β‑blockers with proven efficacy, once-daily dosing, and lower side effect profiles may become instrumental in the treatment of hypertensive diabetic and nondiabetic patients.Keywords: antihypertensive, blood pressure, atenolol, carvedilol, labetalol, metoprolol, nebivolol

  12. Patients with first-episode, drug-naive schizophrenia and subjects at ultra-high risk of psychosis shared increased cerebellar-default mode network connectivity at rest.

    Science.gov (United States)

    Wang, Houliang; Guo, Wenbin; Liu, Feng; Wang, Guodong; Lyu, Hailong; Wu, Renrong; Chen, Jindong; Wang, Shuai; Li, Lehua; Zhao, Jingping

    2016-05-18

    Increased cerebellar-default mode network (DMN) connectivity has been observed in first-episode, drug-naive patients with schizophrenia. However, it remains unclear whether increased cerebellar-DMN connectivity starts earlier than disease onset. Thirty-four ultra-high risk (UHR) subjects, 31 first-episode, drug-naive patients with schizophrenia and 37 healthy controls were enrolled for a resting-state scan. The imaging data were analyzed using the seed-based functional connectivity (FC) method. Compared with the controls, UHR subjects and patients with schizophrenia shared increased connectivity between the right Crus I and bilateral posterior cingulate cortex/precuneus and between Lobule IX and the left superior medial prefrontal cortex. There are positive correlations between the right Crus I-bilateral precuneus connectivity and clinical variables (Structured Interview for Prodromal Syndromes/Positive and Negative Symptom Scale negative symptoms/total scores) in the UHR subjects. Increased cerebellar-DMN connectivity shared by the UHR subjects and the patients not only highlights the importance of the DMN in the pathophysiology of psychosis but also may be a trait alteration for psychosis.

  13. Disruption of Fetal Hormonal Programming (Prenatal Stress) Implicates Shared Risk for Sex Differences in Depression and Cardiovascular Disease

    Science.gov (United States)

    Goldstein, JM; Handa, RJ; Tobet, SA

    2014-01-01

    Comorbidity of major depressive disorder (MDD) and cardiovascular disease (CVD) represents the fourth leading cause of morbidity and mortality worldwide, and women have a two times greater risk than men. Thus understanding the pathophysiology has widespread implications for attenuation and prevention of disease burden. We suggest that sex-dependent MDD-CVD comorbidity may result from alterations in fetal programming consequent to the prenatal maternal environments that produce excess glucocorticoids, which then drive sex-dependent developmental alterations of the fetal hypothalamic-pituitary-adrenal (HPA) axis circuitry impacting mood, stress regulation, autonomic nervous system (ANS), and the vasculature in adulthood. Evidence is consistent with the hypothesis that disruptions of pathways associated with gamma aminobutyric acid (GABA) in neuronal and vascular development and growth factors have critical roles in key developmental periods and adult responses to injury in heart and brain. Understanding the potential fetal origins of these sex differences will contribute to development of novel sex-dependent therapeutics. PMID:24355523

  14. Analysis of risk reduction measures applied to shared essential service water systems at multi-unit sites

    International Nuclear Information System (INIS)

    Kohut, P.; Musicki, Z.; Fitzpatrick, R.

    1991-06-01

    This report summarizes a study performed by Brookhaven National Laboratory for the US Nuclear Regulatory Commission in support of the resolution of NRC Generic Issue 130. GI-130 is concerned with the potential core damage vulnerability resulting from failure of the emergency service water (ESW) system in selected multiplant units. These multiplant units are all twin pressurized water reactor designs that have only two ESW pumps per unit (one per train) backed up by a unit crosstie capability. This generic issue applies to seven US sites (14 plants). The study established and analyzed the core damage vulnerability and identified potential improvements for the ESW system. It obtained generic estimates of the risk reduction potential and cost effectiveness of each potential improvement. The analysis also investigated the cost/benefit aspects of selected combinations of potential improvements. 4 figs., 62 tabs

  15. Relationship of optimism and suicidal ideation in three groups of patients at varying levels of suicide risk.

    Science.gov (United States)

    Huffman, Jeff C; Boehm, Julia K; Beach, Scott R; Beale, Eleanor E; DuBois, Christina M; Healy, Brian C

    2016-06-01

    Optimism has been associated with reduced suicidal ideation, but there have been few studies in patients at high suicide risk. We analyzed data from three study populations (total N = 319) with elevated risk of suicide: (1) patients with a recent acute cardiovascular event, (2) patients hospitalized for heart disease who had depression or an anxiety disorder, and (3) patients psychiatrically hospitalized for suicidal ideation or following a suicide attempt. For each study we analyzed the association between optimism (measured by the Life-Orientation Test-Revised) and suicidal ideation, and then completed an exploratory random effects meta-analysis of the findings to synthesize this data. The meta-analysis of the three studies showed that higher levels of self-reported optimism were associated with a lower likelihood of suicidal ideation (odds ratio [OR] = .89, 95% confidence interval [CI] = .85-.95, z = 3.94, p optimism (OR = .84, 95% CI = .76-.92, z = 3.57, p optimism may be associated with a lower risk of suicidal ideation, above and beyond the effects of depressive symptoms, for a wide range of patients with clinical conditions that place them at elevated risk for suicide. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Does high optimism protect against the inter-generational transmission of high BMI? The Cardiovascular Risk in Young Finns Study.

    Science.gov (United States)

    Serlachius, Anna; Pulkki-Råback, Laura; Juonala, Markus; Sabin, Matthew; Lehtimäki, Terho; Raitakari, Olli; Elovainio, Marko

    2017-09-01

    The transmission of overweight from one generation to the next is well established, however little is known about what psychosocial factors may protect against this familial risk. The aim of this study was to examine whether optimism plays a role in the intergenerational transmission of obesity. Our sample included 1043 participants from the prospective Cardiovascular Risk in Young FINNS Study. Optimism was measured in early adulthood (2001) when the cohort was aged 24-39years. BMI was measured in 2001 (baseline) and 2012 when they were aged 35-50years. Parental BMI was measured in 1980. Hierarchical linear regression and logistic regression were used to examine the association between optimism and future BMI/obesity, and whether an interaction existed between optimism and parental BMI when predicting BMI/obesity 11years later. High optimism in young adulthood demonstrated a negative relationship with high BMI in mid-adulthood, but only in women (β=-0.127, p=0.001). The optimism×maternal BMI interaction term was a significant predictor of future BMI in women (β=-0.588, p=0.036). The logistic regression results confirmed that high optimism predicted reduced obesity in women (OR=0.68, 95% CI, 0.55-0.86), however the optimism × maternal obesity interaction term was not a significant predictor (OR=0.50, 95% CI, 0.10-2.48). Our findings supported our hypothesis that high optimism mitigated the intergenerational transmission of high BMI, but only in women. These findings also provided evidence that positive psychosocial factors such as optimism are associated with long-term protective effects on BMI in women. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Shared effects of the clusterin gene on the default mode network among individuals at risk for Alzheimer's disease.

    Science.gov (United States)

    Ye, Qing; Su, Fan; Shu, Hao; Gong, Liang; Xie, Chun-Ming; Zhou, Hong; Zhang, Zhi-Jun; Bai, Feng

    2017-05-01

    To explore the common effects of the clusterin (CLU) rs11136000 variant on the default mode network (DMN) in amnestic mild cognitive impairment (aMCI) subjects and remitted geriatric depression (RGD) subjects. Fifty-one aMCI subjects, 38 RGD subjects, and 64 cognitively normal elderly subjects underwent resting-state fMRI scans and neuropsychological tests at both baseline and a 35-month follow-up. Posterior cingulate cortex seed-based functional connectivity (FC) analysis was used to obtain the DMN patterns. A CLU gene×disease×time interaction for aMCI subjects was mainly detected in the core cortical midline structures of the DMN, and the interaction for RGD subjects was mainly detected in the limbic system. However, they overlapped in two frontal regions, where consistent effects of the CLU gene on FC alterations were found between aMCI and RGD groups. Furthermore, the alterations of FC with frontal, parietal, and limbic regions compensated for episodic memory impairments in CLU-CT/TT carriers, while no such compensation was found in CLU-CC carriers. The CLU gene could consistently affect the DMN FC with frontal regions among individuals at risk for Alzheimer's disease, and the CLU-T allele was associated with more compensatory neural processes in DMN changes. © 2017 John Wiley & Sons Ltd.

  18. Proposing a Universal Framework for Resilience: Optimizing Risk and Combating Human Vulnerabilities

    Science.gov (United States)

    Sarkar, Arunima

    2017-04-01

    strengthen and optimize the decision making skill and platform for a better sustainable society. The resilience framework provides a cross-sector and multi-level analysis to tackle the vulnerabilities which can be caused to essential utilities like power, water, transport and various machineries that are essential for human sustainability. The direction of resilience framework focuses on prevention of damage and disruption of disaster, mitigate the loss caused to human society and provide the best response for disaster resilience. Thus, the basic pillars which are important for the implementation of resilience is proper governance framework and transparency which takes into account various cost and risk analysis. Thus a common and universal framework for resilience is the main requirement for mass accessibility. The aim of resilience framework focuses on universal adaptability, coherence and validation. A mixed method analysis has been undertaken in this research paper which focuses on the following issues: • Legal, Institutional and community framework for integrating resilience framework of global north and global south. • Spatial as well as statistical analysis to structuralize disaster risk and resilient framework for disaster management. • Early warning system and emergency response in a comparative scale to analyse the various models of risk and resilience framework implemented in USA, China, Nepal and India for proposing an integrated resilience strategy.

  19. Doses to organs at cerebral risks: optimization by robotized stereotaxic radiotherapy and automatic segmentation atlas versus three dimensional conformal radiotherapy

    International Nuclear Information System (INIS)

    Bondiau, P.Y.; Thariat, J.; Benezery, K.; Herault, J.; Dalmasso, C.; Marcie, S.; Malandain, G.

    2007-01-01

    The stereotaxic radiotherapy robotized by 'Cyberknife fourth generation' allows a dosimetric optimization with a high conformity index on the tumor and radiation doses limited on organs at risk. A cerebral automatic anatomic segmentation atlas of organs at risk are used in routine in three dimensions. This study evaluated the superiority of the stereotaxic radiotherapy in comparison with the three dimensional conformal radiotherapy on the preservation of organs at risk in regard of the delivered dose to tumors justifying an accelerated hypo fractionation and a dose escalation. This automatic segmentation atlas should allow to establish correlations between anatomy and cerebral dosimetry; This atlas allows to underline the dosimetry optimization by stereotaxic radiotherapy robotized for organs at risk. (N.C.)

  20. Multivariate analysis of structure and contribution per shares made by potential risk factors at malignant neoplasms in trachea, bronchial tubes and lung

    Directory of Open Access Journals (Sweden)

    G.T. Aydinov

    2017-03-01

    Full Text Available The article gives the results of multivariate analysis of structure and contribution per shares made by potential risk factors at malignant neoplasms in trachea, bronchial tubes and lung. The authors used specialized databases comprising personified records on oncologic diseases in Taganrog, Rostov region, over 1986-2015 (30,684 registered cases of malignant neoplasms, including 3,480 cases of trachea cancer, bronchial tubes cancer, and lung cancer. When carrying out analytical research we applied both multivariate statistical techniques (factor analysis and hierarchical cluster correlation analysis and conventional techniques of epidemiologic analysis including etiologic fraction calculation (EF, as well as an original technique of assessing actual (epidemiologic risk. Average long-term morbidity with trachea, bronchial tubes and lung cancer over 2011-2015 amounts to 46.64 o / oooo . Over the last 15 years a stable decreasing trend has formed, annual average growth being – 1.22 %. This localization holds the 3rd rank place in oncologic morbidity structure, its specific weight being 10.02 %. We determined etiological fraction (EF for smoking as a priority risk factor causing trachea, bronchial tubes and lung cancer; this fraction amounts to 76.19 % for people aged 40 and older, and to 81.99 % for those aged 60 and older. Application of multivariate statistical techniques (factor analysis and cluster correlation analysis in this research enabled us to make factor structure more simple; namely, to highlight, interpret, give a quantitative estimate of self-descriptiveness and rank four group (latent potential risk factors causing lung cancer.

  1. Instant Social Ride-Sharing

    OpenAIRE

    Gidofalvi, Gyözö; Herenyi, Gergely; Bach Pedersen, Torben

    2008-01-01

    This paper explores the use of ride–sharing as a resource-efficient mode of personal transportation. While the perceived benefits of ride–sharing include reduced travel times, transportation costs, congestion, and carbon emissions, its wide–spread adoption is hindered by a number of barriers. These include the scheduling and coordination of routes, safety risks, social discomfort in sharing private spaces, and an imbalance of costs and benefits among parties. To address these barriers, the au...

  2. Shared epitope alleles remain a risk factor for anti-citrullinated proteins antibody (ACPA--positive rheumatoid arthritis in three Asian ethnic groups.

    Directory of Open Access Journals (Sweden)

    Too Chun-Lai

    Full Text Available BACKGROUND: To investigate the associations between HLA-DRB1 shared epitope (SE alleles and rheumatoid arthritis in subsets of rheumatoid arthritis defined by autoantibodies in three Asian populations from Malaysia. METHODS: 1,079 rheumatoid arthritis patients and 1,470 healthy controls were included in the study. Levels of antibodies to citrullinated proteins (ACPA and rheumatoid factors were assessed and the PCR-SSO method was used for HLA-DRB1 genotyping. RESULTS: The proportion of ACPA positivity among Malay, Chinese and Indian rheumatoid arthritis patients were 62.9%, 65.2% and 68.6%, respectively. An increased frequency of SE alleles was observed in ACPA-positive rheumatoid arthritis among the three Asian ethnic groups. HLA-DRB1*10 was highly associated with rheumatoid arthritis susceptibility in these Asian populations. HLA-DRB1*0405 was significantly associated with susceptibility to rheumatoid arthritis in Malays and Chinese, but not in Indians. HLA-DRB1*01 did not show any independent effect as a risk factor for rheumatoid arthritis in this study and HLA-DRB1*1202 was protective in Malays and Chinese. There was no association between SE alleles and ACPA- negative rheumatoid arthritis in any of the three Asian ethnic groups. CONCLUSION: The HLA-DRB1 SE alleles increase the risk of ACPA-positive rheumatoid arthritis in all three Asian populations from Malaysia.

  3. Exergy based methods for economic and risk design optimization of energy systems: Application to a gas turbine

    International Nuclear Information System (INIS)

    Cassetti, G.; Rocco, M.V.; Colombo, E.

    2014-01-01

    Exergy based analyses are considered by the scientific community appropriate tools for the design and the performance evaluation and improvements of energy systems. Moreover, they are today recognized as proper instruments to assess economic, environmental and social externalities of energy systems. This paper presents the results of a study in which different exergy analysis methods are adopted to determine the optimal design configuration of a gas turbine operating in simple Joule Brayton cycle. Standard exergy and Thermoeconomic analyses are performed to identify the highest thermodynamic efficiency and minimum economic cost configurations of the system, while for the environmental analysis Authors propose an innovative method in which the exergy analysis is combined with a Risk Analysis. With this method the total risk associated to the system is used as objective function in the same way as monetary cost is for standard Thermoeconomic analysis. These three methods aims therefore to determine the optimal design configurations of the system with respect to their specific objective functions, respectively: exergy cost (J/J), monetary (exergoeconomic) cost (€/J) and risk (injured/J) of the product. Results lead to three different optimal design parameters for the system, according to the objective of each analysis procedure. - Highlights: • An original implementation of Thermoeconomic framework is proposed. • Standard Exergy and Thermoeconomic analysis are performed on a case study. • A new model using exergy as allocation criteria for Risk Analysis is performed. • Different optimal configurations are obtained and compared

  4. Optimal lag in dynamical investments

    OpenAIRE

    Serva, M.

    1998-01-01

    A portfolio of different stocks and a risk-less security whose composition is dynamically maintained stable by trading shares at any time step leads to a growth of the capital with a nonrandom rate. This is the key for the theory of optimal-growth investment formulated by Kelly. In presence of transaction costs, the optimal composition changes and, more important, it turns out that the frequency of transactions must be reduced. This simple observation leads to the definition of an optimal lag...

  5. Bilastine: a new antihistamine with an optimal benefit-to-risk ratio for safety during driving.

    Science.gov (United States)

    Jáuregui, Ignacio; Ramaekers, Johannes G; Yanai, Kazuhiko; Farré, Magí; Redondo, Esther; Valiente, Román; Labeaga, Luis

    2016-01-01

    Rational selection of a second-generation H1-antihistamine requires efficacy and safety considerations, particularly regarding central nervous system (CNS) effects (cognitive and psychomotor function), potential for driving impairment, minimal sedative effects and a lack of interactions. This review evaluates the key safety features of the non-sedating antihistamine, bilastine, during driving and in preventing road traffic accidents. Among the second-generation H1-antihistamines, sedative effects which can affect cognitive and psychomotor performance, and possibly driving ability, may not be similar. Bilastine is absorbed rapidly, undergoes no hepatic metabolism or cytochrome P450 interaction (minimal drug-drug interaction potential), and is a substrate for P-glycoprotein (limiting CNS entry). Positron emission tomography showed that, compared with other second-generation H1-antihistamines, bilastine has the lowest cerebral histamine H1-receptor occupancy. Bilastine 20 mg once daily (therapeutic dose) is non-sedating, does not enhance the effects of alcohol or CNS sedatives, does not impair driving performance and has at least similar efficacy as other second-generation H1-antihistamines in the treatment of allergic rhinoconjunctivitis and urticaria. Current evidence shows that bilastine has an optimal benefit-to-risk ratio, meeting all conditions for contributing to safety in drivers who need antihistamines, and hence for being considered as an antihistamine of choice for drivers.

  6. D1+ Simulator: A cost and risk optimized approach to nuclear power plant simulator modernization

    International Nuclear Information System (INIS)

    Wischert, W.

    2006-01-01

    D1-Simulator is operated by Kraftwerks-Simulator-Gesellschaft (KSG) and Gesellschaft f?r Simulatorschulung (GfS) at the Simulator Centre in Essen since 1977. The full-scope control room training simulator, used for Kernkraftwerk Biblis (KWB) is based on a PDP-11 hardware platform and is mainly programmed in ASSEMBLER language. The Simulator has reached a continuous high availability of operation throughout the years due to specialized hardware and software support from KSG maintenance team. Nevertheless, D1-Simulator largely reveals limitations with respect to computer capacity and spares and suffers progressively from the non-availability of hardware replacement materials. In order to ensure long term maintainability within the framework of the consensus on nuclear energy, a 2-years refurbishing program has been launched by KWB focusing on quality and budgetary aspects. The so-called D1+ Simulator project is based on the re-use of validated data from existing simulators. Allowing for flexible project management methods, the project outlines a cost and risk optimized approach to Nuclear Power Plant (NPP) Simulator modernization. D1+ Simulator is being built by KSG/GfS in close collaboration with KWB and the simulator vendor THALES by re-using a modern hardware and software development environment from D56-Simulator, used by Kernkraftwerk Obrigheim (KWO) before its decommissioning in 2005. The Simulator project, launched in 2004, is expected to be completed by end of 2006. (author)

  7. OPTIMIZING LIFESTYLE IMPROVES GLYCEMIC PROFILE IN PATIENTS AT RISK FOR DIABETES MELLITUS

    Directory of Open Access Journals (Sweden)

    Rucsandra Dănciulescu Miulescu

    2009-10-01

    Full Text Available There is a pandemic of type 2 diabetes mellitus due to urban and sedentary lifestyle, ageing and obesity.The most important means to prevent this disease is to optimize the lifestyle.Our study aimed to follow-up the effect of moderate caloric restriction and increase of physical activityon clinical and metabolic parameters in persons at risk to develop type 2 diabetes.Twenty-three overweight or obese patients with either altered fasting glucose or altered glucosetolerance were included in this study. They were followed up for 2 years for clinical progress and metabolicprofile, while on lifestyle counseling.The dietary and physical recommendations to improve lifestyle were followed by a small reduction inthe BMI, total cholesterol, systolic and diastolic blood pressure, together with an increase of HDL at 1 and 2years of dietary counseling. However there was a significant reduction in abdominal circumference, fastingglycemia and glycemia at 2 hours during oral glucose tolerance test.The small reduction in BMI indicates the need of a more intensive lifestyle conseling.

  8. Risk factors associated with atherogenic dyslipidemia in the presence of optimal statin therapy.

    Science.gov (United States)

    Zhao, Wang; Zheng, Xi-Long; Jiang, Ze-Nan; Liao, Xiao-Bo; Zhao, Shui-Ping

    2017-12-01

    This study investigated the prevalence of atherogenic dyslipidemia (AD) in Chinese outpatients whose low-density lipoprotein cholesterol (LDL-C) levels reached the goals with statin monotherapy and evaluated the characteristics of these patients. An analysis of the Dyslipidemia International Survey-China study that was carried out at 122 hospitals in China. Among patients reaching their LDL-C goals, the presence of AD was defined as triglyceride levels ≥1.7mmol/L and/or low levels of high-density lipoprotein cholesterol (men: dyslipidemia, 13,551 patients reached LDL-C goals, and 7719 patients of them had AD. Age, male gender, BMI, sedentary lifestyle, coronary heart disease, serum uric acid levels, and fasting plasma glucose (all P<0.05) were independently associated with AD. The intensity of statin therapy did not affect the prevalence of AD. There was a high prevalence of AD in Chinese patients with optimal statin treatment. Some risk factors associated with AD were identified, but these factors were slightly different according to two criteria/guidelines. The intensity of statin therapy did not reduce the prevalence of AD. A combination lipid therapy may be more suitable for Chinese patients. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  9. Urban sharing culture

    DEFF Research Database (Denmark)

    Fjalland, Emmy Laura Perez

    of the structures of the networked urban mobilities and holds the potentials to change the future mobilities. References Bauman, Zygmunt. 2000. Liquid Modernity. Cambridge: Polity. Beck, Ulrich. 1992. Risk Society: Towards a New Modernity (Published in Association with Theory, Culture & Society). London: SAGE......In urban areas sharing cultures, services and economies are rising. People share, rent and recycle their homes, cars, bikes, rides, tools, cloths, working space, knowhow and so on. The sharing culture can be understood as mobilities (Kesselring and Vogl 2013) of goods, values and ideas reshaping...... problems and side effects from concentration of consumption and contamination; and due to the shift from ownership to access it change our basic social cultural norms (Sayer 2005; Sayer 2011) about the ‘good’ life and social status (Freudendal-Pedersen 2007), commons and individuality, responsibility...

  10. Set optimization and applications the state of the art : from set relations to set-valued risk measures

    CERN Document Server

    Heyde, Frank; Löhne, Andreas; Rudloff, Birgit; Schrage, Carola

    2015-01-01

    This volume presents five surveys with extensive bibliographies and six original contributions on set optimization and its applications in mathematical finance and game theory. The topics range from more conventional approaches that look for minimal/maximal elements with respect to vector orders or set relations, to the new complete-lattice approach that comprises a coherent solution concept for set optimization problems, along with existence results, duality theorems, optimality conditions, variational inequalities and theoretical foundations for algorithms. Modern approaches to scalarization methods can be found as well as a fundamental contribution to conditional analysis. The theory is tailor-made for financial applications, in particular risk evaluation and [super-]hedging for market models with transaction costs, but it also provides a refreshing new perspective on vector optimization. There is no comparable volume on the market, making the book an invaluable resource for researchers working in vector o...

  11. Shared familial risk factors between attention-deficit/hyperactivity disorder and overweight/obesity - a population-based familial coaggregation study in Sweden.

    Science.gov (United States)

    Chen, Qi; Kuja-Halkola, Ralf; Sjölander, Arvid; Serlachius, Eva; Cortese, Samuele; Faraone, Stephen V; Almqvist, Catarina; Larsson, Henrik

    2017-06-01

    Despite meta-analytic evidence for the association between attention-deficit/hyperactivity disorder (ADHD) and overweight/obesity, the mechanisms underlying the association are yet to be fully understood. By linking multiple Swedish national and regional registers, we identified 472,735 index males born during 1973-1992, with information on body weight and height directly measured before they were conscripted for military service. We further identified 523,237 full siblings born during 1973-2002 for the index males. All individuals were followed up from their third birthday to December 31, 2009 for ADHD diagnosis. Logistic regression models were used to estimate the association between overweight/obesity in index males and ADHD in their full siblings. Siblings of index males with overweight/obesity had increased risk for ADHD (overweight: OR = 1.14, 95% CI = 1.05-1.24; obesity: OR = 1.42, 95% CI = 1.24-1.63), compared with siblings of index males with normal weight. The results were adjusted for birth year of the index male and sex of the sibling. After further adjustment for ADHD status of the index male, the familial coaggregation remained significant (overweight: OR = 1.13, 95% CI = 1.04-1.22; obesity: OR = 1.38, 95% CI = 1.21-1.57). The results were similar across sex of the siblings. Attention-deficit/hyperactivity disorder and overweight/obesity share familial risk factors, which are not limited to those causing overweight/obesity through the mediation of ADHD. Future research aiming at identifying family-wide environmental risk factors as well as common pleiotropic genetic variants contributing to both traits is warranted. © 2017 Association for Child and Adolescent Mental Health.

  12. PERSPECTIVE: Technical fixes and climate change: optimizing for risks and consequences

    Science.gov (United States)

    Rasch, Philip J.

    2010-09-01

    Scientists and society in general are becoming increasingly concerned about the risks of climate change from the emission of greenhouse gases (IPCC 2007). Yet emissions continue to increase (Raupach et al 2007), and achieving reductions soon enough to avoid large and undesirable impacts requires a near-revolutionary global transformation of energy and transportation systems (Hoffert et al 1998). The size of the transformation and lack of an effective societal response have motivated some to explore other quite controversial strategies to mitigate some of the planetary consequences of these emissions. These strategies have come to be known as geoengineering: 'the deliberate manipulation of the planetary environment to counteract anthropogenic climate change' (Keith 2000). Concern about society's inability to reduce emissions has driven a resurgence in interest in geoengineering, particularly following the call for more research in Crutzen (2006). Two classes of geoengineering solutions have developed: (1) methods to draw CO2 out of the atmosphere and sequester it in a relatively benign form; and (2) methods that change the energy flux entering or leaving the planet without modifying CO2 concentrations by, for example, changing the planetary albedo. Only the latter methods are considered here. Summaries of many of the methods, scientific questions, and issues of testing and implementation are discussed in Launder and Thompson (2009) and Royal Society (2009). The increased attention indicates that geoengineering is not a panacea and all strategies considered will have risks and consequences (e.g. Robock 2008, Trenberth and Dai 2007). Recent studies involving comprehensive Earth system models can provide insight into subtle interactions between components of the climate system. For example Rasch et al (2009) found that geoengineering by changing boundary clouds will not simultaneously 'correct' global averaged surface temperature, precipitation, and sea ice to present

  13. [The optimal cutoff value of waist-to-height ratio in Chinese: based on cardiovascular risk and metabolic disease].

    Science.gov (United States)

    Jia, A H; Xu, S Y; Ming, J; Zhou, J; Zhang, W C; Hao, P R; Ji, Q H

    2017-11-01

    Objective: Waist-to-height ratio (WHtR), a measurement of the distribution of body fat, correlated with abdominal obesity indicating that it might be a better predictor of cardiovascular risk and metabolic disease. We, therefore, evaluated optimal WHtR cutoff points according to the risk of framingham risk score (FRS) and metabolic syndrome (MS) in Chinese. Methods: The subjects were from China National Diabetes and Metabolic Disorders Survey during 2007-2008. Receiver operating characteristic analysis was used to examine the optimal cutoff values of WHtR according to the risk of FRS and MS. Results: A total of 27 820 women and 18 419 men were included in the evaluation. The average age was (45.0±13.7) years. The proportions of FRS ≥10% and MS increased with WHtR both in men and women. The cutoff points of WHtR for the risk of FRS ≥10% and MS were 0.51, 0.52 in men, and 0.52, 0.53 in women, respectively. When FRS ≥10% and MS were taken into consideration with a certain weights, the pooled cutoffs of WHtR were 0.51 in men, and 0.53 in women, respectively. By using the similar method, the optimized cutoff points were 0.52, 0.51, 0.50 for men and 0.51, 0.53, 0.54 for women in age group 20-39, 40-59 and ≥60 years, respectively. Conclusions: The optimal cutoffs of WHtR are 0.51 in men, and 0.53 in women for FRS≥10% in combination with MS indicating that this WHtR cutoff points might be used as indexes to evaluate obesity and risk of obesity-related diseases.

  14. Application of a General Risk Management Model to Portfolio Optimization Problems with Elliptical Distributed Returns for Risk Neutral and Risk Averse Decision Makers

    NARCIS (Netherlands)

    B. Kaynar; S.I. Birbil (Ilker); J.B.G. Frenk (Hans)

    2007-01-01

    textabstractIn this paper portfolio problems with linear loss functions and multivariate elliptical distributed returns are studied. We consider two risk measures, Value-at-Risk and Conditional-Value-at-Risk, and two types of decision makers, risk neutral and risk averse. For Value-at-Risk, we show

  15. Sharing knowledge

    Energy Technology Data Exchange (ETDEWEB)

    2009-07-01

    The workshop on Climate Change Impacts and Adaptation Strategies for Arctic Indigenous Communities is one stage in developing positions and providing input from the perspectives of Arctic Peoples in preparation for the Indigenous Peoples' Global Summit on Climate Change that will take place in April, 2009, in Anchorage, Alaska. The Summit, organized by the Inuit Circumpolar Council with oversight of an International Steering Committee, will bring together hundreds of indigenous Peoples around the world. This Workshop intended to bring together Arctic Indigenous Peoples to deliver and to share information, academic research, case studies based on traditional knowledge and researchers knowledgeable in traditional knowledge and/or policy issues drawn from traditional knowledge. The following themes were discussed: 1) Traditional knowledge research and education; 2) Laws and lawmaking; 3) Food and health; 4) Organisation; 5) Communications and advocacy. (ln)

  16. Voluntary Disclosure and Risk Sharing

    NARCIS (Netherlands)

    Suijs, J.P.M.

    2001-01-01

    This paper analyzes the disclosure strategy of firms that face uncertainty regarding the investor's response to a voluntary disclosure of the firm's private information.This paper distinguishes itself from the existing disclosure literature in that firms do not use voluntary disclosures to separate

  17. Connect. Risk. Ask. Share. Lead!

    Science.gov (United States)

    Lieberman, Daina S.

    2014-01-01

    Teachers are encouraged to "Step into Leadership" because they have a lot to offer, but also a lot to learn. However, many teachers need a push to get started on the path to teacher leadership beyond their classroom walls; therefore, this article provides teachers 10 tips on how to get started and where to look to expand their effect on…

  18. Model-based clinical dose optimization for phenobarbital in neonates: An illustration of the importance of data sharing and external validation.

    Science.gov (United States)

    Völler, Swantje; Flint, Robert B; Stolk, Leo M; Degraeuwe, Pieter L J; Simons, Sinno H P; Pokorna, Paula; Burger, David M; de Groot, Ronald; Tibboel, Dick; Knibbe, Catherijne A J

    2017-11-15

    Particularly in the pediatric clinical pharmacology field, data-sharing offers the possibility of making the most of all available data. In this study, we utilize previously collected therapeutic drug monitoring (TDM) data of term and preterm newborns to develop a population pharmacokinetic model for phenobarbital. We externally validate the model using prospective phenobarbital data from an ongoing pharmacokinetic study in preterm neonates. TDM data from 53 neonates (gestational age (GA): 37 (24-42) weeks, bodyweight: 2.7 (0.45-4.5) kg; postnatal age (PNA): 4.5 (0-22) days) contained information on dosage histories, concentration and covariate data (including birth weight, actual weight, post-natal age (PNA), postmenstrual age, GA, sex, liver and kidney function, APGAR-score). Model development was carried out using NONMEM ® 7.3. After assessment of model fit, the model was validated using data of 17 neonates included in the DINO (Drug dosage Improvement in NeOnates)-study. Modelling of 229 plasma concentrations, ranging from 3.2 to 75.2mg/L, resulted in a one compartment model for phenobarbital. Clearance (CL) and volume (V d ) for a child with a birthweight of 2.6kg at PNA day 4.5 was 0.0091L/h (9%) and 2.38L (5%), respectively. Birthweight and PNA were the best predictors for CL maturation, increasing CL by 36.7% per kg birthweight and 5.3% per postnatal day of living, respectively. The best predictor for the increase in V d was actual bodyweight (0.31L/kg). External validation showed that the model can adequately predict the pharmacokinetics in a prospective study. Data-sharing can help to successfully develop and validate population pharmacokinetic models in neonates. From the results it seems that both PNA and bodyweight are required to guide dosing of phenobarbital in term and preterm neonates. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  19. A risk-based multi-objective model for optimal placement of sensors in water distribution system

    Science.gov (United States)

    Naserizade, Sareh S.; Nikoo, Mohammad Reza; Montaseri, Hossein

    2018-02-01

    In this study, a new stochastic model based on Conditional Value at Risk (CVaR) and multi-objective optimization methods is developed for optimal placement of sensors in water distribution system (WDS). This model determines minimization of risk which is caused by simultaneous multi-point contamination injection in WDS using CVaR approach. The CVaR considers uncertainties of contamination injection in the form of probability distribution function and calculates low-probability extreme events. In this approach, extreme losses occur at tail of the losses distribution function. Four-objective optimization model based on NSGA-II algorithm is developed to minimize losses of contamination injection (through CVaR of affected population and detection time) and also minimize the two other main criteria of optimal placement of sensors including probability of undetected events and cost. Finally, to determine the best solution, Preference Ranking Organization METHod for Enrichment Evaluation (PROMETHEE), as a subgroup of Multi Criteria Decision Making (MCDM) approach, is utilized to rank the alternatives on the trade-off curve among objective functions. Also, sensitivity analysis is done to investigate the importance of each criterion on PROMETHEE results considering three relative weighting scenarios. The effectiveness of the proposed methodology is examined through applying it to Lamerd WDS in the southwestern part of Iran. The PROMETHEE suggests 6 sensors with suitable distribution that approximately cover all regions of WDS. Optimal values related to CVaR of affected population and detection time as well as probability of undetected events for the best optimal solution are equal to 17,055 persons, 31 mins and 0.045%, respectively. The obtained results of the proposed methodology in Lamerd WDS show applicability of CVaR-based multi-objective simulation-optimization model for incorporating the main uncertainties of contamination injection in order to evaluate extreme value

  20. Optimism and Pessimism in Social Context: An Interpersonal Perspective on Resilience and Risk

    Science.gov (United States)

    Smith, Timothy W.; Ruiz, John M.; Cundiff, Jenny M.; Baron, Kelly G.; Nealey-Moore, Jill B.

    2016-01-01

    Using the interpersonal perspective, we examined social correlates of dispositional optimism. In Study 1, optimism and pessimism were associated with warm-dominant and hostile-submissive interpersonal styles, respectively, across four samples, and had expected associations with social support and interpersonal stressors. In 300 married couples, Study 2 replicated these findings regarding interpersonal styles, using self-reports and spouse ratings. Optimism-pessimism also had significant actor and partner associations with marital quality. In Study 3 (120 couples), husbands’ and wives’ optimism predicted increases in their own marital adjustment over time, and husbands’ optimism predicted increases in wives’ marital adjustment. Thus, the interpersonal perspective is a useful integrative framework for examining social processes that could contribute to associations of optimism-pessimism with physical health and emotional adjustment. PMID:27840458

  1. Assessment of health risk due to PM 10 using fuzzy linear membership kriging with particle swarm optimization

    International Nuclear Information System (INIS)

    Singh, Jeetendra B.; Reddy, Vijay S.; Jana, Soumya; De, Swades

    2013-01-01

    Air quality is an important determinant of individual as well as broader well-being. Major pollutants include gasses as well as assorted suspended particulate matter (PM). In this paper, we focus on PM10, which are a collection of particles with median aerodynamic diameter less than 10 μm that remains suspended in the air for long periods. PM10, usually consist of smoke, dirt and dust particles, as well as spores and pollen, could easily be inhaled deep into lung. As a result, high outdoor PM10 concentration poses significant health hazard, and accurate modeling and prediction of health risk due to PM10 assume importance in pollution and public health management. In this backdrop, we propose an improved health risk assessment technique, and demonstrate its efficacy using widely used California PM10 database. At the heart of the proposed method lies indicator kriging, a well-known risk estimation technique. However, improved assessment of subjective health risk is achieved by posing the problem in a fuzzy setting, and optimizing the associated membership functions. In particular, we employ particle swarm optimization (PSO) algorithm, which has been motivated by natural behavior of organisms such as fish-schooling and bird flocking, and proven effective in various optimization contexts. We apply the fuzzy PSO membership grade kriging technique to predict the PM10 spatial distribution over the entire California state. (orig.)

  2. Assessment of health risk due to PM 10 using fuzzy linear membership kriging with particle swarm optimization

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jeetendra B.; Reddy, Vijay S.; Jana, Soumya [Indian Institute of Technology, Hyderabad (India). Dept. of Electrical Engineering; De, Swades [Indian Institute of Technology, Delhi (India). Dept. of Electrical Engineering

    2013-07-01

    Air quality is an important determinant of individual as well as broader well-being. Major pollutants include gasses as well as assorted suspended particulate matter (PM). In this paper, we focus on PM10, which are a collection of particles with median aerodynamic diameter less than 10 {mu}m that remains suspended in the air for long periods. PM10, usually consist of smoke, dirt and dust particles, as well as spores and pollen, could easily be inhaled deep into lung. As a result, high outdoor PM10 concentration poses significant health hazard, and accurate modeling and prediction of health risk due to PM10 assume importance in pollution and public health management. In this backdrop, we propose an improved health risk assessment technique, and demonstrate its efficacy using widely used California PM10 database. At the heart of the proposed method lies indicator kriging, a well-known risk estimation technique. However, improved assessment of subjective health risk is achieved by posing the problem in a fuzzy setting, and optimizing the associated membership functions. In particular, we employ particle swarm optimization (PSO) algorithm, which has been motivated by natural behavior of organisms such as fish-schooling and bird flocking, and proven effective in various optimization contexts. We apply the fuzzy PSO membership grade kriging technique to predict the PM10 spatial distribution over the entire California state. (orig.)

  3. Adipocyte hypertrophy, fatty liver and metabolic risk factors in South Asians: the Molecular Study of Health and Risk in Ethnic Groups (mol-SHARE.

    Directory of Open Access Journals (Sweden)

    Sonia S Anand

    Full Text Available OBJECTIVE: We sought to determine if differences in the distribution and characteristics of adipose tissue between South Asians and white Caucasians account for differences in risk factors for cardiovascular disease. RESEARCH DESIGN AND METHODS: We recruited 108 healthy South Asians (36.8 years and white Caucasians (34.2 years within three BMI strata. Body composition, adipocyte size, abdominal fat area, and hepatic adiposity were assessed and related to fasting glucose, insulin, lipids and adiponectin. RESULTS: After adjustment for age, sex, and BMI, South Asians compared to white Caucasians had higher ln fasting insulin (mean difference (MD: 0.44; 95% CI: 0.20-0.69, lower HDL cholesterol (md: -0.13; 95% CI:-0.26 to -0.01, and lower adiponectin (md: -2.38; 95% CI: -3.59 to -1.17. South Asians also had more body fat (md: 2.69; 95% CI: 0.70 to 4.69, lower lean muscle mass (md: -3.25; 95%CI: -5.35 to -1.14, increased waist to hip ratio (md: 0.03; 95% CI: 0.01-0.05, less superficial subcutaneous abdominal adipose tissue (md: -2.94; 95% CI: -5.56 to-0.32, more deep/visceral to superficial adipose tissue ratio (md 0.34; 95% CI: 0.02 to 0.65, and more liver fat (md: 7.43%; 95% CI: 2.30 to 12.55%. Adipocyte area was increased in South Asians compared to white Caucasians (md: 64.26; 95% CI: 24.3 to 104.1 units(2. Adjustment for adipocyte area attenuated the ethnic differences in insulin (md: 0.22; 95% CI: -0.07 to 0.51, HDL (md: -0.01; 95% CI: -0.16 to 0.13 and adiponectin (md: -1.11; 95% CI: -2.61 to 0.39. Adjustment for differences in adipocyte area and fat distribution attenuated the ethnic difference in liver fat (md: 5.19; 95% CI: 0.31 to 10.06. CONCLUSION: South Asians have an increased adipocyte area compared to white Caucasians. This difference accounts for the ethnic differences in insulin, HDL cholesterol, adiponectin, and ectopic fat deposition in the liver.

  4. Hybrid Electricity Markets with Long-Term Risk-Sharing Arrangements: Adapting Market Design to Security of Supply and decarbonization Objectives

    International Nuclear Information System (INIS)

    ROQUES, Fabien; FINON, Dominique

    2017-01-01

    The re-emergence of policy interventionism in electricity markets raises questions as to how market design can best be adapted to meeting the investment challenge associated with security of supply (SoS) and decarbonization objectives. This paper takes an institutionalist approach in terms of modularity of the market design, and reviews the standard historical approach towards competitive markets, in order to analyse the roles and interactions of the initial and additional market 'modules'. We argue that a number of additional modules is required to achieve long-term policy objectives, such as decarbonization and security of supply (SoS). But, in turn, they destabilise the initial modules of the market design, in particular by the entries of renewables. We review the international experience with hybrid market design and draw a number of policy recommendations at to best practices, as well as suggesting ways in which the initial market modules can be improved to prevent inconsistencies with the new modules. The move towards a hybrid market regime, which relies on a combination of planning, long-term risk sharing arrangements and improved markets entrenched in a function of short-term coordination, appears to be unavoidable where decarbonization policies are adopted. (authors)

  5. Hitting the Optimal Vaccination Percentage and the Risks of Error: Why to Miss Right.

    Science.gov (United States)

    Harvey, Michael J; Prosser, Lisa A; Messonnier, Mark L; Hutton, David W

    2016-01-01

    To determine the optimal level of vaccination coverage defined as the level that minimizes total costs and explore how economic results change with marginal changes to this level of coverage. A susceptible-infected-recovered-vaccinated model designed to represent theoretical infectious diseases was created to simulate disease spread. Parameter inputs were defined to include ranges that could represent a variety of possible vaccine-preventable conditions. Costs included vaccine costs and disease costs. Health benefits were quantified as monetized quality adjusted life years lost from disease. Primary outcomes were the number of infected people and the total costs of vaccination. Optimization methods were used to determine population vaccination coverage that achieved a minimum cost given disease and vaccine characteristics. Sensitivity analyses explored the effects of changes in reproductive rates, costs and vaccine efficacies on primary outcomes. Further analysis examined the additional cost incurred if the optimal coverage levels were not achieved. Results indicate that the relationship between vaccine and disease cost is the main driver of the optimal vaccination level. Under a wide range of assumptions, vaccination beyond the optimal level is less expensive compared to vaccination below the optimal level. This observation did not hold when the cost of the vaccine cost becomes approximately equal to the cost of disease. These results suggest that vaccination below the optimal level of coverage is more costly than vaccinating beyond the optimal level. This work helps provide information for assessing the impact of changes in vaccination coverage at a societal level.

  6. Flood risk and economically optimal safety targets for coastal flood defense systems

    NARCIS (Netherlands)

    Dupuits, E.J.C.; Schweckendiek, T.

    2015-01-01

    A front defense can improve the reliability of a rear defense in a coastal flood defense system. The influence of this interdependency on the accompanying economically optimal safety targets of both front and rear defense is investigated. The results preliminary suggest that the optimal safety level

  7. Human MHC-II with Shared Epitope Motifs Are Optimal Epstein-Barr Virus Glycoprotein 42 Ligands—Relation to Rheumatoid Arthritis

    DEFF Research Database (Denmark)

    Trier, Nicole; Gonzalez-Izarzugaza, Jose Maria; Chailyan, Anna

    2018-01-01

    influence disease onset. Especially genetic factors play a vital role in the onset of disease, as the heritability of RA is 50–60%, with the human leukocyte antigen (HLA) alleles accounting for at least 30% of the overall genetic risk. Some HLA-DR alleles encode a conserved sequence of amino acids, referred...... by several lines of evidence and, based on several findings, we suggest that EBV is able to induce the onset of RA in predisposed SE-positive individuals, by promoting entry of B-cells through direct contact between SE and gp42 in the entry complex...

  8. Finding Risk Groups by Optimizing Artificial Neural Networks on the Area under the Survival Curve Using Genetic Algorithms.

    Science.gov (United States)

    Kalderstam, Jonas; Edén, Patrik; Ohlsson, Mattias

    2015-01-01

    We investigate a new method to place patients into risk groups in censored survival data. Properties such as median survival time, and end survival rate, are implicitly improved by optimizing the area under the survival curve. Artificial neural networks (ANN) are trained to either maximize or minimize this area using a genetic algorithm, and combined into an ensemble to predict one of low, intermediate, or high risk groups. Estimated patient risk can influence treatment choices, and is important for study stratification. A common approach is to sort the patients according to a prognostic index and then group them along the quartile limits. The Cox proportional hazards model (Cox) is one example of this approach. Another method of doing risk grouping is recursive partitioning (Rpart), which constructs a decision tree where each branch point maximizes the statistical separation between the groups. ANN, Cox, and Rpart are compared on five publicly available data sets with varying properties. Cross-validation, as well as separate test sets, are used to validate the models. Results on the test sets show comparable performance, except for the smallest data set where Rpart's predicted risk groups turn out to be inverted, an example of crossing survival curves. Cross-validation shows that all three models exhibit crossing of some survival curves on this small data set but that the ANN model manages the best separation of groups in terms of median survival time before such crossings. The conclusion is that optimizing the area under the survival curve is a viable approach to identify risk groups. Training ANNs to optimize this area combines two key strengths from both prognostic indices and Rpart. First, a desired minimum group size can be specified, as for a prognostic index. Second, the ability to utilize non-linear effects among the covariates, which Rpart is also able to do.

  9. An Integrated Simulation, Inference and Optimization Approach for Groundwater Remediation with Two-stage Health-Risk Assessment

    Directory of Open Access Journals (Sweden)

    Aili Yang

    2018-05-01

    Full Text Available In this study, an integrated simulation, inference and optimization approach with two-stage health risk assessment (i.e., ISIO-THRA is developed for supporting groundwater remediation for a petroleum-contaminated site in western Canada. Both environmental standards and health risk are considered as the constraints in the ISIO-THRA model. The health risk includes two parts: (1 the health risk during the remediation process and (2 the health risk in the natural attenuation period after remediation. In the ISIO-THRA framework, the relationship between contaminant concentrations and time is expressed through first-order decay models. The results demonstrate that: (1 stricter environmental standards and health risk would require larger pumping rates for the same remediation duration; (2 higher health risk may happen in the period of the remediation process; (3 for the same environmental standard and acceptable health-risk level, the remediation techniques that take the shortest time would be chosen. ISIO-THRA can help to systematically analyze interaction among contaminant transport, remediation duration, and environmental and health concerns, and further provide useful supportive information for decision makers.

  10. Risk based economic optimization of investment decisions of regulated power distribution system operators; Risikobasierte wirtschaftliche Optimierung von Investitionsentscheidungen regulierter Stromnetzbetreiber

    Energy Technology Data Exchange (ETDEWEB)

    John, Oliver

    2012-07-01

    The author of the contribution under consideration reports on risk-based economic optimization of investment decisions of regulated power distribution system operators. The focus is the economically rational decision behavior of operators under certain regulatory requirements. Investments in power distribution systems form the items subject to decisions. Starting from a description of theoretical and practical regulatory approaches, their financial implications are quantified at first. On this basis, optimization strategies are derived with respect to the investment behavior. For this purpose, an optimization algorithm is developed and applied to exemplary companies. Finally, effects of uncertainties in regulatory systems are investigated. In this context, Monte Carlo simulations are used in conjunction with real options analysis.

  11. Who reaps the benefits, who bears the risks? Comparative optimism, comparative utility, and regulatory preferences for mobile phone technology.

    Science.gov (United States)

    White, Mathew P; Eiser, J Richard; Harris, Peter R; Pahl, Sabine

    2007-06-01

    Although the issue of risk target (e.g., self, others, children) is widely acknowledged in risk perception research, its importance appears underappreciated. To date, most research has been satisfied with demonstrating comparative optimism, i.e., lower perceived risk for the self than others, and exploring its moderators, such as perceived controllability and personal exposure. Much less research has investigated how the issue of target may affect benefit perceptions or key outcomes such as stated preferences for hazard regulation. The current research investigated these issues using data from a public survey of attitudes toward mobile phone technology (N= 1,320). First, results demonstrated comparative optimism for this hazard, and also found moderating effects of both controllability and personal exposure. Second, there was evidence of comparative utility, i.e., users believed that the benefits from mobile phone technology are greater for the self than others. Third, and most important for policy, preferences for handset regulation were best predicted by perceptions of the risks to others but perceived benefits for the self. Results suggest a closer awareness of target can improve prediction of stated preferences for hazard regulation and that it would be profitable for future research to pay more attention to the issue of target for both risk and benefit perceptions.

  12. Optimal breastfeeding durations for HIV-exposed infants: the impact of maternal ART use, infant mortality and replacement feeding risk.

    Science.gov (United States)

    Mallampati, Divya; MacLean, Rachel L; Shapiro, Roger; Dabis, Francois; Engelsmann, Barbara; Freedberg, Kenneth A; Leroy, Valeriane; Lockman, Shahin; Walensky, Rochelle; Rollins, Nigel; Ciaranello, Andrea

    2018-04-01

    In 2010, the WHO recommended women living with HIV breastfeed for 12 months while taking antiretroviral therapy (ART) to balance breastfeeding benefits against HIV transmission risks. To inform the 2016 WHO guidelines, we updated prior research on the impact of breastfeeding duration on HIV-free infant survival (HFS) by incorporating maternal ART duration, infant/child mortality and mother-to-child transmission data. Using the Cost-Effectiveness of Preventing AIDS Complications (CEPAC)-Infant model, we simulated the impact of breastfeeding duration on 24-month HFS among HIV-exposed, uninfected infants. We defined "optimal" breastfeeding durations as those maximizing 24-month HFS. We varied maternal ART duration, mortality rates among breastfed infants/children, and relative risk of mortality associated with replacement feeding ("RRRF"), modelled as a multiplier on all-cause mortality for replacement-fed infants/children (range: 1 [no additional risk] to 6). The base-case simulated RRRF = 3, median infant mortality, and 24-month maternal ART duration. In the base-case, HFS ranged from 83.1% (no breastfeeding) to 90.2% (12-months breastfeeding). Optimal breastfeeding durations increased with higher RRRF values and longer maternal ART durations, but did not change substantially with variation in infant mortality rates. Optimal breastfeeding durations often exceeded the previous WHO recommendation of 12 months. In settings with high RRRF and long maternal ART durations, HFS is maximized when mothers breastfeed longer than the previously-recommended 12 months. In settings with low RRRF or short maternal ART durations, shorter breastfeeding durations optimize HFS. If mothers are supported to use ART for longer periods of time, it is possible to reduce transmission risks and gain the benefits of longer breastfeeding durations. © 2018 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

  13. Adapting risk management and computational intelligence network optimization techniques to improve traffic throughput and tail risk analysis.

    Science.gov (United States)

    2014-04-01

    Risk management techniques are used to analyze fluctuations in uncontrollable variables and keep those fluctuations from impeding : the core function of a system or business. Examples of this are making sure that volatility in copper and aluminum pri...

  14. A meta-analysis of genome-wide association scans identifies IL18RAP, PTPN2, TAGAP, and PUS10 as shared risk loci for Crohn's disease and celiac disease.

    Directory of Open Access Journals (Sweden)

    Eleonora A M Festen

    2011-01-01

    Full Text Available Crohn's disease (CD and celiac disease (CelD are chronic intestinal inflammatory diseases, involving genetic and environmental factors in their pathogenesis. The two diseases can co-occur within families, and studies suggest that CelD patients have a higher risk to develop CD than the general population. These observations suggest that CD and CelD may share common genetic risk loci. Two such shared loci, IL18RAP and PTPN2, have already been identified independently in these two diseases. The aim of our study was to explicitly identify shared risk loci for these diseases by combining results from genome-wide association study (GWAS datasets of CD and CelD. Specifically, GWAS results from CelD (768 cases, 1,422 controls and CD (3,230 cases, 4,829 controls were combined in a meta-analysis. Nine independent regions had nominal association p-value <1.0 x 10⁻⁵ in this meta-analysis and showed evidence of association to the individual diseases in the original scans (p-value < 1 x 10⁻² in CelD and < 1 x 10⁻³ in CD. These include the two previously reported shared loci, IL18RAP and PTPN2, with p-values of 3.37 x 10⁻⁸ and 6.39 x 10⁻⁹, respectively, in the meta-analysis. The other seven had not been reported as shared loci and thus were tested in additional CelD (3,149 cases and 4,714 controls and CD (1,835 cases and 1,669 controls cohorts. Two of these loci, TAGAP and PUS10, showed significant evidence of replication (Bonferroni corrected p-values <0.0071 in the combined CelD and CD replication cohorts and were firmly established as shared risk loci of genome-wide significance, with overall combined p-values of 1.55 x 10⁻¹⁰ and 1.38 x 10⁻¹¹ respectively. Through a meta-analysis of GWAS data from CD and CelD, we have identified four shared risk loci: PTPN2, IL18RAP, TAGAP, and PUS10. The combined analysis of the two datasets provided the power, lacking in the individual GWAS for single diseases, to detect shared loci with a

  15. Co-occurrence of viruses and mosquitoes at the vectors' optimal climate range: An underestimated risk to temperate regions?

    Science.gov (United States)

    Blagrove, Marcus S C; Caminade, Cyril; Waldmann, Elisabeth; Sutton, Elizabeth R; Wardeh, Maya; Baylis, Matthew

    2017-06-01

    Mosquito-borne viruses have been estimated to cause over 100 million cases of human disease annually. Many methodologies have been developed to help identify areas most at risk from transmission of these viruses. However, generally, these methodologies focus predominantly on the effects of climate on either the vectors or the pathogens they spread, and do not consider the dynamic interaction between the optimal conditions for both vector and virus. Here, we use a new approach that considers the complex interplay between the optimal temperature for virus transmission, and the optimal climate for the mosquito vectors. Using published geolocated data we identified temperature and rainfall ranges in which a number of mosquito vectors have been observed to co-occur with West Nile virus, dengue virus or chikungunya virus. We then investigated whether the optimal climate for co-occurrence of vector and virus varies between "warmer" and "cooler" adapted vectors for the same virus. We found that different mosquito vectors co-occur with the same virus at different temperatures, despite significant overlap in vector temperature ranges. Specifically, we found that co-occurrence correlates with the optimal climatic conditions for the respective vector; cooler-adapted mosquitoes tend to co-occur with the same virus in cooler conditions than their warmer-adapted counterparts. We conclude that mosquitoes appear to be most able to transmit virus in the mosquitoes' optimal climate range, and hypothesise that this may be due to proportionally over-extended vector longevity, and other increased fitness attributes, within this optimal range. These results suggest that the threat posed by vector-competent mosquito species indigenous to temperate regions may have been underestimated, whilst the threat arising from invasive tropical vectors moving to cooler temperate regions may be overestimated.

  16. Solution Monitoring Evaluated by Proliferation Risk Assessment and Fuzzy Optimization Analysis for Safeguards in a Reprocessing Process

    Directory of Open Access Journals (Sweden)

    Mitsutoshi Suzuki

    2013-01-01

    Full Text Available Solution monitoring (SM has been used in a nuclear reprocessing plant as an additional measure to provide assurance that the plant is operated as declared. The inline volume and density monitoring equipment with dip tubes is important for safety and safeguards purposes and is a typical example of safeguards by design (SBD. Recently safety, safeguards, and security by design (3SBD are proposed to promote an efficient and effective generation of nuclear energy. In 3SBD, proliferation risk assessment has the potential to consider likelihood of the incidence and proliferation risk in safeguards. In this study, risk assessment methodologies for safeguards and security are discussed and several mathematical methods are presented to investigate risk notion applied to intentional acts of facility misuse in an uncertainty environment. Proliferation risk analysis with the Markov model, deterrence effect with the game model, and SBD with fuzzy optimization are shown in feasibility studies to investigate the potential application of the risk and uncertainty analyses in safeguards. It is demonstrated that the SM is an effective measurement system using risk-informed and cost-effective SBD, even though there are inherent difficulties related to the possibility of operator’s falsification.

  17. Shared decision making

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000877.htm Shared decision making To use the sharing features on this page, ... treatment you both support. When to use Shared Decision Making Shared decision making is often used when you ...

  18. Updating Optimal Decisions Using Game Theory and Exploring Risk Behavior Through Response Surface Methodology

    National Research Council Canada - National Science Library

    Jordan, Jeremy D

    2007-01-01

    .... Methodology is developed that allows a decision maker to change his perceived optimal policy based on available knowledge of the opponents strategy, where the opponent is a rational decision maker...

  19. The Optimal Configuration Scheme of the Virtual Power Plant Considering Benefits and Risks of Investors

    Directory of Open Access Journals (Sweden)

    Jingmin Wang

    2017-07-01

    Full Text Available A virtual power plant (VPP is a special virtual unit that integrates various distributed energy resources (DERs distributed in the generation and consumption sides. The optimal configuration scheme of the VPP needs to break the geographical restrictions to make full use of DERs, considering the uncertainties. First, the components of the DERs and the structure of the VPP are briefly introduced. Next, the cubic exponential smoothing method is adopted to predict the VPP load requirement. Finally, the optimal configuration of the DER capacities inside the VPP is calculated by using portfolio theory and genetic algorithms (GA. The results show that the configuration scheme can optimize the DER capacities considering uncertainties, guaranteeing economic benefits of investors, and fully utilizing the DERs. Therefore, this paper provides a feasible reference for the optimal configuration scheme of the VPP from the perspective of investors.

  20. Optimal fossil-fuel taxation with backstop technologies and tenure risk

    Energy Technology Data Exchange (ETDEWEB)

    Strand, Jon [World Bank, Development Economics Group, Washington DC 20433 (United States); Department of Economics, University of Oslo (Norway)

    2010-03-15

    The paper derives the global welfare-optimizing time path for a tax on fossil fuels causing a negative stock externality (climate change), under increasing marginal extraction cost, and in the presence of an unlimited backstop resource causing no externality. In a basic competitive case, the optimal tax equals the Pigou rate, equivalent to the present discounted value of marginal damage costs. We consider two separate types of tenure insecurity for resource owners, and their impact on the tax implementing the optimal policy. When insecure control is with respect to future ownership to the resource, competitive extraction is higher than otherwise, and the efficiency-implementing tax exceeds the Pigou rate. When tenure insecurity instead implies possible expropriation ('holdup') of investment in extraction capacity, it deters extraction, and the optimal tax is lower than the Pigou rate. (author)

  1. An Empirical Study on Hedge Fund Portfolio Optimization, Mean-Risk Based Approaches

    OpenAIRE

    Li, Yang

    2011-01-01

    Abstract This research attempts to investigate the divergences between the Mean-Variance and the Mean-CVaR portfolio optimization methods in examining various assets classes, such as equities, bonds, and especially hedge funds. In order to get a thorough understanding of hedge funds facts and available optimization techniques, relevant literatures are carefully reviewed and incorporated into later stage computer modelling. By constructing three hypothetical portfolios, including traditiona...

  2. Optimal high b-value for diffusion weighted MRI in diagnosing high risk prostate cancers in the peripheral zone.

    Science.gov (United States)

    Agarwal, Harsh K; Mertan, Francesca V; Sankineni, Sandeep; Bernardo, Marcelino; Senegas, Julien; Keupp, Jochen; Daar, Dagane; Merino, Maria; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L; Turkbey, Baris

    2017-01-01

    To retrospectively determine the optimal b-value(s) of diffusion-weighted imaging (DWI) associated with intermediate-high risk cancer in the peripheral zone (PZ) of the prostate. Forty-two consecutive patients underwent multi b-value (16 evenly spaced b-values between 0 and 2000 s/mm 2 ) DWI along with multi-parametric MRI (MP-MRI) of the prostate at 3 Tesla followed by trans-rectal ultrasound/MRI fusion guided targeted biopsy of suspicious lesions detected at MP-MRI. Computed DWI images up to a simulated b-value of 4000 s/mm 2 were also obtained using a pair of b-values (b = 133 and 400 or 667 or 933 s/mm 2 ) from the multi b-value DWI. The contrast ratio of average intensity of the targeted lesions and the background PZ was determined. Receiver operator characteristic curves and the area under the curve (AUCs) were obtained for separating patients eligible for active surveillance with low risk prostate cancers from intermediate-high risk prostate cancers as per the cancer of the prostate risk assessment (CAPRA) scoring system. The AUC first increased then decreased with the increase in b-values reaching maximum at b = 1600 s/mm 2 (0.74) with no statistically significant different AUC of DWI with b-values 1067-2000 s/mm 2 . The AUC of computed DWI increased then decreased with the increase in b-values reaching a maximum of 0.75 around b = 2000 s/mm 2 . There was no statistically significant difference between the AUC of optimal acquired DWI and either of optimal computed DWI. The optimal b-value for acquired DWI in differentiating intermediate-high from low risk prostate cancers in the PZ is b = 1600 s/mm 2 . The computed DWI has similar performance as that of acquired DWI with the optimal performance around b = 2000 s/mm 2 . 4 J. Magn. Reson. Imaging 2017;45:125-131. © 2016 International Society for Magnetic Resonance in Medicine.

  3. Systematic review with meta-analysis: risk factors for non-alcoholic fatty liver disease suggest a shared altered metabolic and cardiovascular profile between lean and obese patients.

    Science.gov (United States)

    Sookoian, S; Pirola, C J

    2017-07-01

    The pathogenesis of non-alcoholic fatty liver disease (NAFLD) is closely associated with the co-occurrence of multiple pathological conditions characterising the metabolic syndrome (MetS), obesity in particular. However, NAFLD also develops in lean subjects, whose risk factors remain poorly defined. We performed a meta-analysis of 15 studies, along with the data pertaining to our own population (n=336 patients). Data from lean (n=1966) and obese (n=5938) patients with NAFLD were analysed; lean (n=9946) and obese (n=6027) subjects without NAFLD served as controls. Relative to the lean non-NAFLD controls, lean patients with NAFLD were older (3.79±0.72 years, P=1.36×10 -6 ) and exhibited the entire spectrum of the MetS risk factors. Specifically, they had a significant (P=10 -10 ) increase in plasma glucose levels (6.44±1.12 mg/dL) and HOMA-IR (0.52±0.094-unit increment), blood lipids (triglycerides: 48.37±3.6, P=10 -10 and total cholesterol: 7.04±3.8, mg/dL, P=4.2×10 -7 ), systolic (5.64±0.7) and diastolic (3.37±0.9) blood pressure (mm Hg), P=10 -10 , and waist circumference (5.88±0.4 cm, P=10 -10 ); values denote difference in means±SE. Nevertheless, the overall alterations in the obese group were much more severe when compared to lean subjects, regardless of the presence of NAFLD. Meta-regression suggested that NAFLD is a modifier of the level of blood lipids. Lean and obese patients with NAFLD share a common altered metabolic and cardiovascular profile. The former, while having normal body weight, showed excess of abdominal adipose tissue as well as other MetS features. © 2017 John Wiley & Sons Ltd.

  4. Processing Risk In Asset Management : Exploring The Boundaries Of Risk Based Optimization Under Uncertainty For An Energy Infrastructure Asset Manager

    NARCIS (Netherlands)

    Wijnia, Y.C.

    2016-01-01

    In the liberalized energy market Distribution Network Operators (DNOs) are confronted with income reductions by the regulator. The common response to this challenge is the implementation of asset management, which can be regarded as systematically applying Cost Benefit Analysis (CBA) to the risks in

  5. Presentation of a Software Method for Use of Risk Assessment in Building Fire Safety Measure Optimization

    Directory of Open Access Journals (Sweden)

    A. R. Koohpaei

    2012-05-01

    Full Text Available Background and aims: The property loss and physical injuries due to fire events in buildings demonstrate the necessity of implementation of efficient and performance based fire safety measures. Effective and high efficiency protection is possible when design and selection of protection measures are based on risk assessment. This study aims at presenting a software method to make possible selection and design of building fire safety measures based upon quantitative risk assessment and building characteristics. Methods: based on “Fire Risk Assessment Method for Engineer (FRAME” a program in MATLB software was written. The first section of this program, according to the FRAME method and based on the specification of a building, calculates the potential risk and acceptable risk level. In the second section, according to potential risk, acceptable risk level and the fire risk level that user want, program calculate concession of protective factor for that building.Results: The prepared software make it possible to assign the fire safety measure based on quantitative risk level and all building specifications. All calculations were performed with 0.001 of precision and the accuracy of this software was assessed with handmade calculations. During the use of the software if an error occurs in calculations, it can be distinguished in the output. Conclusion: Application of quantitative risk assessment is a suitable tool for increasing of efficiency in designing and execution of fire protection measure in building. With using this software the selected fire safety measure would be more efficient and suitable since the selection of fire safety measures performed on risk assessment and particular specification of a building. Moreover fire risk in the building can be managed easily and carefully.

  6. A time consistent risk averse three-stage stochastic mixed integer optimization model for power generation capacity expansion

    International Nuclear Information System (INIS)

    Pisciella, P.; Vespucci, M.T.; Bertocchi, M.; Zigrino, S.

    2016-01-01

    We propose a multi-stage stochastic optimization model for the generation capacity expansion problem of a price-taker power producer. Uncertainties regarding the evolution of electricity prices and fuel costs play a major role in long term investment decisions, therefore the objective function represents a trade-off between expected profit and risk. The Conditional Value at Risk is the risk measure used and is defined by a nested formulation that guarantees time consistency in the multi-stage model. The proposed model allows one to determine a long term expansion plan which takes into account uncertainty, while the LCoE approach, currently used by decision makers, only allows one to determine which technology should be chosen for the next power plant to be built. A sensitivity analysis is performed with respect to the risk weighting factor and budget amount. - Highlights: • We propose a time consistent risk averse multi-stage model for capacity expansion. • We introduce a case study with uncertainty on electricity prices and fuel costs. • Increased budget moves the investment from gas towards renewables and then coal. • Increased risk aversion moves the investment from coal towards renewables. • Time inconsistency leads to a profit gap between planned and implemented policies.

  7. Environmental and Economic Optimization Model for Electric System Planning in Ningxia, China: Inexact Stochastic Risk-Aversion Programming Approach

    Directory of Open Access Journals (Sweden)

    L. Ji

    2015-01-01

    Full Text Available The main goal of this paper is to provide a novel risk aversion model for long-term electric power system planning from the manager’s perspective with the consideration of various uncertainties. In the proposed method, interval parameter programming and two-stage stochastic programming are integrated to deal with the technical, economics, and policy uncertainties. Moreover, downside risk theory is introduced to balance the trade-off between the profit and risk according to the decision-maker’s risk aversion attitude. To verify the effectiveness and practical application of this approach, an inexact stochastic risk aversion model is developed for regional electric system planning and management in Ningxia Hui Autonomous Region, China. The series of solutions provide the decision-maker with the optimal investment strategy and operation management under different future emission reduction scenarios and risk-aversion levels. The results indicated that pollution control devices are still the main measures to achieve the current mitigation goal and the adjustment of generation structure would play an important role in the future cleaner electricity system with the stricter environmental policy. In addition, the model can be used for generating decision alternatives and helping decision-makers identify desired energy structure adjustment and pollutants/carbon mitigation abatement policies under various economic and system-reliability constraints.

  8. Inexact stochastic risk-aversion optimal day-ahead dispatch model for electricity system management with wind power under uncertainty

    International Nuclear Information System (INIS)

    Ji, Ling; Huang, Guo-He; Huang, Lu-Cheng; Xie, Yu-Lei; Niu, Dong-Xiao

    2016-01-01

    High penetration of wind power generation and deregulated electricity market brings a great challenge to the electricity system operators. It is crucial to make optimal strategy among various generation units and spinning reserve for supporting the system safety operation. By integrating interval two-stage programming and stochastic robust programming, this paper proposes a novel robust model for day-ahead dispatch and risk-aversion management under uncertainties. In the proposed model, the uncertainties are expressed as interval values with different scenario probability. The proposed method requires low computation, and still retains the complete information. A case study is to validate the effectiveness of this approach. Facing the uncertainties of future demand and electricity price, the system operators need to make optimal dispatch strategy for thermal power units and wind turbine, and arrange proper spinning reserve and flexible demand response program to mitigate wind power forecasting error. The optimal strategies provide the system operators with better trade-off between the maximum benefits and the minimum system risk. In additional, two different market rules are compared. The results show that extra financial penalty for the wind power dispatch deviation is another efficient way to enhance the risk consciousness of decision makers and lead to more conservative strategy. - Highlights: • An inexact two-stage stochastic robust programming model for electricity system with wind power penetration. • Uncertainties expressed as discrete intervals and probability distributions. • Demand response program was introduced to adjust the deviation in real-time market. • Financial penalty for imbalance risk from wind power generation was evaluated.

  9. Treatment of chronic myeloid leukemia: assessing risk, monitoring response, and optimizing outcome.

    Science.gov (United States)

    Shanmuganathan, Naranie; Hiwase, Devendra Keshaorao; Ross, David Morrall

    2017-12-01

    Over the past two decades, tyrosine kinase inhibitors have become the foundation of chronic myeloid leukemia (CML) treatment. The choice between imatinib and newer tyrosine kinase inhibitors (TKIs) needs to be balanced against the known toxicity and efficacy data for each drug, the therapeutic goal being to maximize molecular response assessed by BCR-ABL RQ-PCR assay. There is accumulating evidence that the early achievement of molecular targets is a strong predictor of superior long-term outcomes. Early response assessment provides the opportunity to intervene early with the aim of ensuring an optimal response. Failure to achieve milestones or loss of response can have diverse causes. We describe how clinical and laboratory monitoring can be used to ensure that each patient is achieving an optimal response and, in patients who do not reach optimal response milestones, how the monitoring results can be used to detect resistance and understand its origins.

  10. Input price risk and optimal timing of energy investment: choice between fossil- and biofuels

    Energy Technology Data Exchange (ETDEWEB)

    Murto, Pauli; Nese, Gjermund

    2002-05-01

    We consider energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a numerical example based on cost, estimates of two different power plant types. (author)

  11. Input price risk and optimal timing of energy investment: choice between fossil- and biofuels

    International Nuclear Information System (INIS)

    Murto, Pauli; Nese, Gjermund

    2002-01-01

    We consider energy investment, when a choice has to be made between fossil fuel and biomass fired production technologies. A dynamic model is presented to illustrate the effect of the different degrees of input price uncertainty on the choice of technology and the timing of the investment. It is shown that when the choice of technology is irreversible, it may be optimal to postpone the investment even if it would otherwise be optimal to invest in one or both of the plant types. We provide a numerical example based on cost, estimates of two different power plant types. (author)

  12. Gait dynamics to optimize fall risk assessment in geriatric patients admitted to an outpatient diagnostic clinic

    NARCIS (Netherlands)

    Kikkert, Lisette H. J.; de Groot, Maartje H; van Campen, Jos P.; Beijnen, Jos H.; Hortobagyi, Tibor; Vuillerme, Nicolas; Lamoth, Claudine C. J.

    2017-01-01

    Fall prediction in geriatric patients remains challenging because the increased fall risk involves multiple, interrelated factors caused by natural aging and/or pathology. Therefore, we used a multi-factorial statistical approach to model categories of modifiable fall risk factors among geriatric

  13. Optimal investment and indifference pricing when risk aversion is not monotone: SAHARA utility functions

    NARCIS (Netherlands)

    Chen, A.; Pelsser, A.; Vellekoop, M.

    2008-01-01

    Abstract. We develop a new class of utility functions, SAHARA utility, with the dis- tinguishing feature that they implement the assumption that agents may become less risk-averse for very low values of wealth. This means that SAHARA utility can be used to characterize risk gambling behavior of an

  14. A Novel Approach for Risk Minimization in Life-Cycle Oil Production Optimization

    DEFF Research Database (Denmark)

    Capolei, Andrea; Christiansen, Lasse Hjuler; Jørgensen, John Bagterp

    2017-01-01

    The oil research community has invested much effort into computer aided optimization to enhance oil recovery. While simulation studies have demonstrated the potential of model-based technology to improve industrial standards, the largely unknown geology of subsurface reservoirs limits application...

  15. Mean-variance portfolio optimization with state-dependent risk aversion

    DEFF Research Database (Denmark)

    Bjoerk, Tomas; Murgoci, Agatha; Zhou, Xun Yu

    2014-01-01

    The objective of this paper is to study the mean-variance portfolio optimization in continuous time. Since this problem is time inconsistent we attack it by placing the problem within a game theoretic framework and look for subgame perfect Nash equilibrium strategies. This particular problem has...

  16. Optimizing prescribed fire allocation for managing fire risk in central Catalonia.

    Science.gov (United States)

    Alcasena, Fermín J; Ager, Alan A; Salis, Michele; Day, Michelle A; Vega-Garcia, Cristina

    2018-04-15

    We used spatial optimization to allocate and prioritize prescribed fire treatments in the fire-prone Bages County, central Catalonia (northeastern Spain). The goal of this study was to identify suitable strategic locations on forest lands for fuel treatments in order to: 1) disrupt major fire movements, 2) reduce ember emissions, and 3) reduce the likelihood of large fires burning into residential communities. We first modeled fire spread, hazard and exposure metrics under historical extreme fire weather conditions, including node influence grid for surface fire pathways, crown fraction burned and fire transmission to residential structures. Then, we performed an optimization analysis on individual planning areas to identify production possibility frontiers for addressing fire exposure and explore alternative prescribed fire treatment configurations. The results revealed strong trade-offs among different fire exposure metrics, showed treatment mosaics that optimize the allocation of prescribed fire, and identified specific opportunities to achieve multiple objectives. Our methods can contribute to improving the efficiency of prescribed fire treatment investments and wildfire management programs aimed at creating fire resilient ecosystems, facilitating safe and efficient fire suppression, and safeguarding rural communities from catastrophic wildfires. The analysis framework can be used to optimally allocate prescribed fire in other fire-prone areas within the Mediterranean region and elsewhere. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Development of Optimization method about Capital Structure and Senior-Sub Structure by considering Project-Risk

    Science.gov (United States)

    Kawamoto, Shigeru; Ikeda, Yuichi; Fukui, Chihiro; Tateshita, Fumihiko

    Private finance initiative is a business scheme that materializes social infrastructure and public services by utilizing private-sector resources. In this paper we propose a new method to optimize capital structure, which is the ratio of capital to debt, and senior-sub structure, which is the ratio of senior loan to subordinated loan, for private finance initiative. We make the quantitative analysis of a private finance initiative's project using the proposed method. We analyze trade-off structure between risk and return in the project, and optimize capital structure and senior-sub structure. The method we propose helps to improve financial stability of the project, and to make a fund raising plan that is expected to be reasonable for project sponsor and moneylender.

  18. A Probabilistic Alternative Approach to Optimal Project Profitability Based on the Value-at-Risk

    Directory of Open Access Journals (Sweden)

    Yonggu Kim

    2018-03-01

    Full Text Available This paper focuses on an investment decision-making process for sustainable development based on the profitability impact factors for overseas projects. Investors prefer to use the discounted cash-flow method. Although this method is simple and straightforward, its critical weakness is its inability to reflect the factor volatility associated with the project evaluation. To overcome this weakness, the Value-at-Risk method is used to apply the volatility of the profitability impact factors, thereby reflecting the risks and establishing decision-making criteria for risk-averse investors. Risk-averse investors can lose relatively acceptable investment opportunities to risk-neutral or risk-amenable investors due to strict investment decision-making criteria. To overcome this problem, critical factors are selected through a Monte Carlo simulation and a sensitivity analysis, and solutions to the critical-factor problems are then found by using the Theory of Inventive Problem Solving and a business version of the Project Definition Rating Index. This study examines the process of recovering investment opportunities with projects that are investment feasible and that have been rejected when applying the criterion of the Value-at-Risk method. To do this, a probabilistic alternative approach is taken. To validate this methodology, the proposed framework for an improved decision-making process is demonstrated using two actual overseas projects of a Korean steel-making company.

  19. Coastal and river flood risk analyses for guiding economically optimal flood adaptation policies: a country-scale study for Mexico

    Science.gov (United States)

    Haer, Toon; Botzen, W. J. Wouter; van Roomen, Vincent; Connor, Harry; Zavala-Hidalgo, Jorge; Eilander, Dirk M.; Ward, Philip J.

    2018-06-01

    Many countries around the world face increasing impacts from flooding due to socio-economic development in flood-prone areas, which may be enhanced in intensity and frequency as a result of climate change. With increasing flood risk, it is becoming more important to be able to assess the costs and benefits of adaptation strategies. To guide the design of such strategies, policy makers need tools to prioritize where adaptation is needed and how much adaptation funds are required. In this country-scale study, we show how flood risk analyses can be used in cost-benefit analyses to prioritize investments in flood adaptation strategies in Mexico under future climate scenarios. Moreover, given the often limited availability of detailed local data for such analyses, we show how state-of-the-art global data and flood risk assessment models can be applied for a detailed assessment of optimal flood-protection strategies. Our results show that especially states along the Gulf of Mexico have considerable economic benefits from investments in adaptation that limit risks from both river and coastal floods, and that increased flood-protection standards are economically beneficial for many Mexican states. We discuss the sensitivity of our results to modelling uncertainties, the transferability of our modelling approach and policy implications. This article is part of the theme issue `Advances in risk assessment for climate change adaptation policy'.

  20. Gait dynamics to optimize fall risk assessment in geriatric patients admitted to an outpatient diagnostic clinic

    OpenAIRE

    Kikkert, Lisette H. J.; de Groot, Maartje H; van Campen, Jos P.; Beijnen, Jos H.; Hortobagyi, Tibor; Vuillerme, Nicolas; Lamoth, Claudine C. J.

    2017-01-01

    Fall prediction in geriatric patients remains challenging because the increased fall risk involves multiple, interrelated factors caused by natural aging and/or pathology. Therefore, we used a multi-factorial statistical approach to model categories of modifiable fall risk factors among geriatric patients to identify fallers with highest sensitivity and specificity with a focus on gait performance. Patients (n = 61, age = 79; 41% fallers) underwent extensive screening in three categories: (1)...

  1. Optimal Bi-Objective Redundancy Allocation for Systems Reliability and Risk Management

    DEFF Research Database (Denmark)

    Govindan, Kannan; Jafarian, Ahmad; Azbari, Mostafa E.

    2016-01-01

    In the big data era, systems reliability is critical to effective systems risk management. In this paper, a novel multiobjective approach, with hybridization of a known algorithm called NSGA-II and an adaptive population-based simulated annealing (APBSA) method is developed to solve the systems...... of domination; and 4) data envelopment analysis. The computational studies have shown that the proposed algorithm is an effective approach for systems reliability and risk management....

  2. Optimal hypofractionated conformal radiotherapy for large brain metastases in patients with high risk factors: a single-institutional prospective study

    International Nuclear Information System (INIS)

    Inoue, Hiroshi K; Sato, Hiro; Suzuki, Yoshiyuki; Saitoh, Jun-ichi; Noda, Shin-ei; Seto, Ken-ichi; Torikai, Kota; Sakurai, Hideyuki; Nakano, Takashi

    2014-01-01

    A single-institutional prospective study of optimal hypofractionated conformal radiotherapy for large brain metastases with high risk factors was performed based on the risk prediction of radiation-related complications. Eighty-eight patients with large brain metastases ≥10 cm 3 in critical areas treated from January 2010 to February 2014 using the CyberKnife were evaluated. The optimal dose and number of fractions were determined based on the surrounding brain volume circumscribed with a single dose equivalent (SDE) of 14 Gy (V14) to be less than 7 cm 3 for individual lesions. Univariate and multivariate analyses were conducted. As a result of optimal treatment, 92 tumors ranging from 10 to 74.6 cm 3 (median, 16.2 cm 3 ) in volume were treated with a median prescribed isodose of 57% and a median fraction number of five. In order to compare the results according to the tumor volume, the tumors were divided into the following three groups: 1) 10–19.9 cm 3 , 2) 20–29.9 cm 3 and 3) ≥30 cm 3 . The lesions were treated with a median prescribed isodose of 57%, 56% and 55%, respectively, and the median fraction number was five in all three groups. However, all tumors ≥20 cm 3 were treated with ≥ five fractions. The median SDE of the maximum dose in the three groups was 47.2 Gy, 48.5 Gy and 46.5 Gy, respectively. Local tumor control was obtained in 90.2% of the patients, and the median survival was nine months, with a median follow-up period of seven months (range, 3-41 months). There were no significant differences in the survival rates among the three groups. Six tumors exhibited marginal recurrence 7-36 months after treatment. Ten patients developed symptomatic brain edema or recurrence of pre-existing edema, seven of whom required osmo-steroid therapy. No patients developed radiation necrosis requiring surgical resection. Our findings demonstrate that the administration of optimal hypofractionated conformal radiotherapy based on the dose-volume prediction

  3. Dipyridamole-thallium scanning in patients undergoing vascular surgery. Optimizing preoperative evaluation of cardiac risk

    International Nuclear Information System (INIS)

    Eagle, K.A.; Singer, D.E.; Brewster, D.C.; Darling, R.C.; Mulley, A.G.; Boucher, C.A.

    1987-01-01

    Dipyridamole-thallium imaging has been suggested as a method of preoperatively assessing cardiac risk in patients undergoing major surgery. To define more clearly its proper role in preoperative assessment, we prospectively evaluated 111 patients undergoing vascular surgery. In the first set of 61 patients, our data confirmed the value of preoperative dipyridamole-thallium scanning in identifying the patients who suffered postoperative ischemic events. Events occurred in eight of 18 patients with reversible defects on preoperative imaging, compared with no events in 43 patients with no thallium redistribution (confidence interval for the risk difference: 0.624, 0.256). The results also suggested that clinical factors might allow identification of a low-risk subset of patients. To test the hypothesis that patients with no evidence of congestive heart failure, angina, prior myocardial infarction, or diabetes do not require further preoperative testing, we evaluated an additional 50 patients having vascular procedures. None of the 23 without the clinical markers had untoward outcomes, while ten of 27 patients with one or more of these clinical markers suffered postoperative ischemic events (confidence interval for the risk difference: 0.592, 0.148). In the clinical high-risk subset, further risk stratification is achieved with dipyridamole-thallium scanning

  4. Development of stand-alone risk assessment software for optimized maintenance planning of power plant facilities

    International Nuclear Information System (INIS)

    Choi, Woo Sung; Song, Gee Wook; Kim, Bum Shin; Chang, Sung Ho; Lee, Sang Min

    2015-01-01

    Risk-Risk-based inspection (RBI) has been developed in order to identify risky equipment that can cause major accidents or damages in large-scale plants. This assessment evaluates the equipment's risk, categorizes their priorities based on risk level, and then determines the urgency of their maintenance or allocates maintenance resources. An earlier version of the risk-based assessment software is already installed within the equipment management system; however, the assessment is based on examination by an inspector, and the results can be influenced by his subjective judgment, rather than assessment being based on failure probability. Moreover, the system is housed within a server, which limits the inspector's work space and time, and such a system can be used only on site. In this paper, the development of independent risk-based assessment software is introduced; this software calculates the failure probability by an analytical method, and analyzes the field inspection results, as well as inspection effectiveness. It can also operate on site, since it can be installed on an independent platform, and has the ability to generate an I/O function for the field inspection results regarding the period for an optimum maintenance cycle. This program will provide useful information not only to the field users who are participating in maintenance, but also to the engineers who need to decide whether to extend the life cycle of the power machinery or replace only specific components

  5. Acute cognitive dysfunction after hip fracture: frequency and risk factors in an optimized, multimodal, rehabilitation program

    DEFF Research Database (Denmark)

    Bitsch, Martin; Foss, Nicolai Bang; Kristensen, Billy Bjarne

    2006-01-01

    hip fracture surgery in an optimized, multimodal, peri-operative rehabilitation regimen. METHODS: One hundred unselected hip fracture patients treated in a well-defined, optimized, multimodal, peri-operative rehabilitation regimen were included. Patients were tested upon admission and on the second......BACKGROUND: Patients undergoing hip fracture surgery often experience acute post-operative cognitive dysfunction (APOCD). The pathogenesis of APOCD is probably multifactorial, and no single intervention has been successful in its prevention. No studies have investigated the incidence of APOCD after......, fourth and seventh post-operative days with the Mini Mental State Examination (MMSE) score. RESULTS: Thirty-two per cent of patients developed a significant post-operative cognitive decline, which was associated with several pre-fracture patient characteristics, including age and cognitive function...

  6. Multi-objective portfolio optimization of mutual funds under downside risk measure using fuzzy theory

    OpenAIRE

    M. Amiri; M. Zandieh; A. Alimi

    2012-01-01

    Mutual fund is one of the most popular techniques for many people to invest their funds where a professional fund manager invests people's funds based on some special predefined objectives; therefore, performance evaluation of mutual funds is an important problem. This paper proposes a multi-objective portfolio optimization to offer asset allocation. The proposed model clusters mutual funds with two methods based on six characteristics including rate of return, variance, semivariance, turnove...

  7. Stochastic optimization of subprime residential mortgage loan funding and its risks / by B. de Waal

    OpenAIRE

    De Waal, Bernadine

    2010-01-01

    The subprime mortgage crisis (SMC) is an ongoing housing and nancial crisis that was triggered by a marked increase in mortgage delinquencies and foreclosures in the U.S. It has had major adverse consequences for banks and nancial markets around the globe since it became apparent in 2007. In our research, we examine an originator's (OR's) nonlinear stochastic optimal control problem related to choices regarding deposit inflow rates and marketable securities allocation. Here, ...

  8. Optimizing Support Vector Machine Parameters with Genetic Algorithm for Credit Risk Assessment

    Science.gov (United States)

    Manurung, Jonson; Mawengkang, Herman; Zamzami, Elviawaty

    2017-12-01

    Support vector machine (SVM) is a popular classification method known to have strong generalization capabilities. SVM can solve the problem of classification and linear regression or nonlinear kernel which can be a learning algorithm for the ability of classification and regression. However, SVM also has a weakness that is difficult to determine the optimal parameter value. SVM calculates the best linear separator on the input feature space according to the training data. To classify data which are non-linearly separable, SVM uses kernel tricks to transform the data into a linearly separable data on a higher dimension feature space. The kernel trick using various kinds of kernel functions, such as : linear kernel, polynomial, radial base function (RBF) and sigmoid. Each function has parameters which affect the accuracy of SVM classification. To solve the problem genetic algorithms are proposed to be applied as the optimal parameter value search algorithm thus increasing the best classification accuracy on SVM. Data taken from UCI repository of machine learning database: Australian Credit Approval. The results show that the combination of SVM and genetic algorithms is effective in improving classification accuracy. Genetic algorithms has been shown to be effective in systematically finding optimal kernel parameters for SVM, instead of randomly selected kernel parameters. The best accuracy for data has been upgraded from kernel Linear: 85.12%, polynomial: 81.76%, RBF: 77.22% Sigmoid: 78.70%. However, for bigger data sizes, this method is not practical because it takes a lot of time.

  9. Optimism and barriers to colonoscopy in low-income Latinos at average risk for colorectal cancer.

    Science.gov (United States)

    Efuni, Elizaveta; DuHamel, Katherine N; Winkel, Gary; Starr, Tatiana; Jandorf, Lina

    2015-09-01

    Colorectal cancer (CRC) screening continues to be underused, particularly by Latinos. CRC and colonoscopy fear, worry, and fatalism have been identified as screening barriers in Latinos. The study purpose was to examine the relationship of optimism, fatalism, worry, and fear in the context of Latinos referred for CRC screening. Our sample included 251 Latinos between the ages of 50 and 83 years who had no personal or immediate family history of CRC, no personal history of gastrointestinal disorder, no colonoscopy in the past 5 years, and received a referral for a colonoscopy. Face-to-face interviews were performed, and data were analyzed using regression models. Greater optimism (β = -1.72, p optimism (β = -0.09, p < 0.05), higher fatalism (β = 0.28, p < 0.01), and female gender (β = 0.9, p < 0.05) were associated with greater worry. Interventions that address fatalism and promote optimistic beliefs may reduce worry among Latinos referred for colonoscopy. Interventions that alleviate colonoscopy fear because of family history of cancer particularly among Latino women may help improve distress about CRC screening. Copyright © 2014 John Wiley & Sons, Ltd.

  10. PEMODELAN OPTIMASI MITIGASI RISIKO RANTAI PASOK PRODUK/KOMODITAS JAGUNG Optimization Model Of Corn Supply Chain Risk Mitigation

    Directory of Open Access Journals (Sweden)

    Suharjito Suharjito

    2012-03-01

    Full Text Available Besides more complexes, the agricultural product supply chain also was probabilistic, dynamic and higher dependencies. This happened because of the agricultural product was easy broken, the process of planting, the growth and the harvesting depended the season, the yield had variety form and measurement, and the agricultural product was bulky so that the agricultural product was difficult to be handled. The height of the dependency level and the complexity from the supply chain network of the agricultural product made this chain to be more susceptible to the disturbance. The risk of failure for the supply chain could be happen internally (the relations between the organization and the network of the supplier and externally (between the network of the supplier and its environment. Therefore, the needs for supply chain risk management to avoid a result that can continuously occur at any point in the supply network. The purpose of this study was to describe a model of evaluation and risk management supply chain of agricultural products. Model could identify risks of every level of supply chain and provide solutions that can be done to minimize them. The index value of risk on farm level was 26 % higher than the risk at the level of collector (8.78 % and distributors (8.31 %. The model can optimize farmers’ planting schedules to reduce supply risk and price, while also optimizing the selection of suppliers at the level of collectors and distributors with the consideration of minimizing risk and optimizing profits.   Keywords: Risk evaluation, supply chain management, corn supply risk commodity   ABSTRAK   Selain lebih kompleks, rantai pasok produk pertanian juga bersifat probabilistik, dinamis dan kebergantungan yang tinggi. Hal ini terjadi karena produk pertanian bersifat mudah rusak, proses penanaman, pertumbuhan dan pemanenan tergantung musim, hasil panen memiliki bentuk dan ukuran yang bervariasi, dan produk pertanian bersifat kamba

  11. The Integrated Medical Model - Optimizing In-flight Space Medical Systems to Reduce Crew Health Risk and Mission Impacts

    Science.gov (United States)

    Kerstman, Eric; Walton, Marlei; Minard, Charles; Saile, Lynn; Myers, Jerry; Butler, Doug; Lyengar, Sriram; Fitts, Mary; Johnson-Throop, Kathy

    2009-01-01

    The Integrated Medical Model (IMM) is a decision support tool used by medical system planners and designers as they prepare for exploration planning activities of the Constellation program (CxP). IMM provides an evidence-based approach to help optimize the allocation of in-flight medical resources for a specified level of risk within spacecraft operational constraints. Eighty medical conditions and associated resources are represented in IMM. Nine conditions are due to Space Adaptation Syndrome. The IMM helps answer fundamental medical mission planning questions such as What medical conditions can be expected? What type and quantity of medical resources are most likely to be used?", and "What is the probability of crew death or evacuation due to medical events?" For a specified mission and crew profile, the IMM effectively characterizes the sequence of events that could potentially occur should a medical condition happen. The mathematical relationships among mission and crew attributes, medical conditions and incidence data, in-flight medical resources, potential clinical and crew health end states are established to generate end state probabilities. A Monte Carlo computational method is used to determine the probable outcomes and requires up to 25,000 mission trials to reach convergence. For each mission trial, the pharmaceuticals and supplies required to diagnose and treat prevalent medical conditions are tracked and decremented. The uncertainty of patient response to treatment is bounded via a best-case, worst-case, untreated case algorithm. A Crew Health Index (CHI) metric, developed to account for functional impairment due to a medical condition, provides a quantified measure of risk and enables risk comparisons across mission scenarios. The use of historical in-flight medical data, terrestrial surrogate data as appropriate, and space medicine subject matter expertise has enabled the development of a probabilistic, stochastic decision support tool capable of

  12. Innovative practice model to optimize resource utilization and improve access to care for high-risk and BRCA+ patients.

    Science.gov (United States)

    Head, Linden; Nessim, Carolyn; Usher Boyd, Kirsty

    2017-02-01

    Bilateral prophylactic mastectomy (BPM) has demonstrated breast cancer risk reduction in high-risk/ BRCA + patients. However, priority of active cancers coupled with inefficient use of operating room (OR) resources presents challenges in offering BPM in a timely manner. To address these challenges, a rapid access prophylactic mastectomy and immediate reconstruction (RAPMIR) program was innovated. The purpose of this study was to evaluate RAPMIR with regards to access to care and efficiency. We retrospectively reviewed the cases of all high-risk/ BRCA + patients having had BPM between September 2012 and August 2014. Patients were divided into 2 groups: those managed through the traditional model and those managed through the RAPMIR model. RAPMIR leverages 2 concurrently running ORs with surgical oncology and plastic surgery moving between rooms to complete 3 combined BPMs with immediate reconstruction in addition to 1-2 independent cases each operative day. RAPMIR eligibility criteria included high-risk/ BRCA + status; BPM with immediate, implant-based reconstruction; and day surgery candidacy. Wait times, case volumes and patient throughput were measured and compared. There were 16 traditional patients and 13 RAPMIR patients. Mean wait time (days from referral to surgery) for RAPMIR was significantly shorter than for the traditional model (165.4 v. 309.2 d, p = 0.027). Daily patient throughput (4.3 v. 2.8), plastic surgery case volume (3.7 v. 1.6) and surgical oncology case volume (3.0 v. 2.2) were significantly greater in the RAPMIR model than the traditional model ( p = 0.003, p < 0.001 and p = 0.015, respectively). A multidisciplinary model with optimized scheduling has the potential to improve access to care and optimize resource utilization.

  13. Net returns, fiscal risks, and the optimal patient mix for a profit-maximizing hospital.

    Science.gov (United States)

    Ozatalay, S; Broyles, R

    1987-10-01

    As is well recognized, the provisions of PL98-21 not only transfer financial risks from the Medicare program to the hospital but also induce institutions to adjust the diagnostic mix of Medicare beneficiaries so as to maximize net income or minimize the net loss. This paper employs variation in the set of net returns as the sole measure of financial risk and develops a model that identifies the mix of beneficiaries that maximizes net income, subject to a given level of risk. The results indicate that the provisions of PL98-21 induce the institution to deny admission to elderly patients presenting conditions for which the net return is relatively low and the variance in the cost per case is large. Further, the paper suggests that the treatment of beneficiaries at a level commensurate with previous periods or the preferences of physicians may jeopardize the viability and solvency of Medicare-dependent hospitals.

  14. INFORMATION SECURITY RISKS OPTIMIZATION IN CLOUDY SERVICES ON THE BASIS OF LINEAR PROGRAMMING

    Directory of Open Access Journals (Sweden)

    I. A. Zikratov

    2013-01-01

    Full Text Available The paper discusses theoretical aspects of secure cloud services creation for information processing of various confidentiality degrees. A new approach to the reasoning of information security composition in distributed computing structures is suggested, presenting the problem of risk assessment as an extreme problem of decisionmaking. Linear programming method application is proved to minimize the risk of information security for given performance security in compliance with the economic balance for the maintenance of security facilities and cost of services. An example is given to illustrate the obtained theoretical results.

  15. Mean-risk optimal decision of a steel company under emission control

    Czech Academy of Sciences Publication Activity Database

    Zapletal, F.; Šmíd, Martin

    2016-01-01

    Roč. 24, č. 2 (2016), s. 435-454 ISSN 1435-246X R&D Projects: GA ČR(CZ) GBP402/12/G097; GA ČR GA13-25911S Grant - others:EC(XE) SP2014/146; EC(XE) SP2013/148 Institutional support: RVO:67985556 Keywords : Stochastic programming * Risk management * Mean-risk modeling * Emissions trading * Emissions management Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.659, year: 2016 http://library.utia.cas.cz/separaty/2015/E/smid-0451991.pdf

  16. Optimal investment and location decisions of a firm in a flood risk area using Impulse Control Theory

    Science.gov (United States)

    Grames, Johanna; Grass, Dieter; Kort, Peter; Prskawetz, Alexia

    2017-04-01

    Flooding events can affect businesses close to rivers, lakes or coasts. This paper provides a partial equilibrium model which helps to understand the optimal location choice for a firm in flood risk areas and its investment strategies. How often, when and how much are firms willing to invest in flood risk protection measures? We apply Impulse Control Theory to solve the model analytically and develop a continuation algorithm to solve the model numerically. Firms always invest in flood defense. The investment increases the higher the flood risk and the more firms also value the future, i.e. the more sustainable they plan. Investments in production capital follow a similar path. Hence, planning in a sustainable way leads to economic growth. Sociohydrological feedbacks are crucial for the location choice of the firm, whereas different economic situations have an impact on investment strategies. If flood defense is already present, e.g. built up by the government, firms move closer to the water and invest less in flood defense, which allows firms to accrue higher expected profits. Firms with a large initial production capital surprisingly try not to keep their market advantage, but rather reduce flood risk by reducing exposed production capital.

  17. Identification of risk conditions for the development of adrenal disorders: how optimized PubMed search strategies makes the difference.

    Science.gov (United States)

    Guaraldi, Federica; Parasiliti-Caprino, Mirko; Goggi, Riccardo; Beccuti, Guglielmo; Grottoli, Silvia; Arvat, Emanuela; Ghizzoni, Lucia; Ghigo, Ezio; Giordano, Roberta; Gori, Davide

    2014-12-01

    The exponential growth of scientific literature available through electronic databases (namely PubMed) has increased the chance of finding interesting articles. At the same time, search has become more complicated, time consuming, and at risk of missing important information. Therefore, optimized strategies have to be adopted to maximize searching impact. The aim of this study was to formulate efficient strings to search PubMed for etiologic associations between adrenal disorders (ADs) and other conditions. A comprehensive list of terms identifying endogenous conditions primarily affecting adrenals was compiled. An ad hoc analysis was performed to find the best way to express each term in order to find the highest number of potentially pertinent articles in PubMed. A predefined number of retrieved abstracts were read to assess their association with ADs' etiology. A more sensitive (providing the largest literature coverage) and a more specific (including only those terms retrieving >40 % of potentially pertinent articles) string were formulated. Various researches were performed to assess strings' ability to identify articles of interest in comparison with non-optimized literature searches. We formulated optimized, ready applicable tools for the identification of the literature assessing etiologic associations in the field of ADs using PubMed, and demonstrated the advantages deriving from their application. Detailed description of the methodological process is also provided, so that this work can easily be translated to other fields of practice.

  18. California Earthquake Clearinghouse Crisis Information-Sharing Strategy in Support of Situational Awareness, Understanding Interdependencies of Critical Infrastructure, Regional Resilience, Preparedness, Risk Assessment/mitigation, Decision-Making and Everyday Operational Needs

    Science.gov (United States)

    Rosinski, A.; Morentz, J.; Beilin, P.

    2017-12-01

    The principal function of the California Earthquake Clearinghouse is to provide State and Federal disaster response managers, and the scientific and engineering communities, with prompt information on ground failure, structural damage, and other consequences from significant seismic events such as earthquakes and tsunamis. The overarching problem highlighted in discussions with Clearinghouse partners is the confusion and frustration of many of the Operational Area representatives, and some regional utilities throughout the state on what software applications they should be using and maintaining to meet State, Federal, and Local, requirements, and for what purposes, and how to deal with the limitations of these applications. This problem is getting in the way of making meaningful progress on developing multi-application interoperability and the necessary supporting cross-sector information-sharing procedures and dialogue on essential common operational information that entities need to share for different all hazards missions and related operational activities associated with continuity, security, and resilience. The XchangeCore based system the Clearinghouse is evolving helps deal with this problem, and does not compound it by introducing yet another end-user application; there is no end-user interface with which one views XchangeCore, all viewing of data provided through XchangeCore occurs in and on existing, third-party operational applications. The Clearinghouse efforts with XchangeCore are compatible with FEMA, which is currently using XchangeCore-provided data for regional and National Business Emergency Operations Center (source of business information sharing during emergencies) response. Also important, and should be emphasized, is that information-sharing is not just for response, but for preparedness, risk assessment/mitigation decision-making, and everyday operational needs for situational awareness. In other words, the benefits of the Clearinghouse

  19. Carrying the (paper) burden: A portfolio view of systemic risk and optimal bank size

    NARCIS (Netherlands)

    Bos, J.W.B.; Lamers, M.; Purice, V.

    2014-01-01

    We examine the relationship between bank size and financial stability by viewing the supervisor of a banking system as an ‘investor’ holding a portfolio of banks. Based on this view, we investigate the role of large banks in determining the systemic risk in this portfolio. Our results, based on book

  20. Risk-Based Inspection and Maintenance Planning Optimization of Offshore Wind Turbines

    DEFF Research Database (Denmark)

    Ramírez, José G. Rangel; Sørensen, John Dalsgaard

    2009-01-01

    A risk-based inspection planning (RBI) approach applied to offshore wind turbines (OWT) is presented, based on RBI methodology developed in the last decades in the oil and gas industry. In wind farm (IWF) and single-alone locations are considered using a code-established turbulence models including...

  1. Risk-based optimization of photon and proton radiotherapy for pediatric medulloblastoma

    DEFF Research Database (Denmark)

    Brodin, Nils Patrik

    Medulloblastoma (MB) is one of the most common brain tumors in children and most patients will survive their disease if treated with surgery, radio- and chemotherapy. This has resulted in a growing number of MB survivors who are at risk of developing severe late complications related to the aggre...

  2. Gait dynamics to optimize fall risk assessment in geriatric patients admitted to an outpatient diagnostic clinic.

    Science.gov (United States)

    Kikkert, Lisette H J; de Groot, Maartje H; van Campen, Jos P; Beijnen, Jos H; Hortobágyi, Tibor; Vuillerme, Nicolas; Lamoth, Claudine C J

    2017-01-01

    Fall prediction in geriatric patients remains challenging because the increased fall risk involves multiple, interrelated factors caused by natural aging and/or pathology. Therefore, we used a multi-factorial statistical approach to model categories of modifiable fall risk factors among geriatric patients to identify fallers with highest sensitivity and specificity with a focus on gait performance. Patients (n = 61, age = 79; 41% fallers) underwent extensive screening in three categories: (1) patient characteristics (e.g., handgrip strength, medication use, osteoporosis-related factors) (2) cognitive function (global cognition, memory, executive function), and (3) gait performance (speed-related and dynamic outcomes assessed by tri-axial trunk accelerometry). Falls were registered prospectively (mean follow-up 8.6 months) and one year retrospectively. Principal Component Analysis (PCA) on 11 gait variables was performed to determine underlying gait properties. Three fall-classification models were then built using Partial Least Squares-Discriminant Analysis (PLS-DA), with separate and combined analyses of the fall risk factors. PCA identified 'pace', 'variability', and 'coordination' as key properties of gait. The best PLS-DA model produced a fall classification accuracy of AUC = 0.93. The specificity of the model using patient characteristics was 60% but reached 80% when cognitive and gait outcomes were added. The inclusion of cognition and gait dynamics in fall classification models reduced misclassification. We therefore recommend assessing geriatric patients' fall risk using a multi-factorial approach that incorporates patient characteristics, cognition, and gait dynamics.

  3. Gait dynamics to optimize fall risk assessment in geriatric patients admitted to an outpatient diagnostic clinic.

    Directory of Open Access Journals (Sweden)

    Lisette H J Kikkert

    Full Text Available Fall prediction in geriatric patients remains challenging because the increased fall risk involves multiple, interrelated factors caused by natural aging and/or pathology. Therefore, we used a multi-factorial statistical approach to model categories of modifiable fall risk factors among geriatric patients to identify fallers with highest sensitivity and specificity with a focus on gait performance. Patients (n = 61, age = 79; 41% fallers underwent extensive screening in three categories: (1 patient characteristics (e.g., handgrip strength, medication use, osteoporosis-related factors (2 cognitive function (global cognition, memory, executive function, and (3 gait performance (speed-related and dynamic outcomes assessed by tri-axial trunk accelerometry. Falls were registered prospectively (mean follow-up 8.6 months and one year retrospectively. Principal Component Analysis (PCA on 11 gait variables was performed to determine underlying gait properties. Three fall-classification models were then built using Partial Least Squares-Discriminant Analysis (PLS-DA, with separate and combined analyses of the fall risk factors. PCA identified 'pace', 'variability', and 'coordination' as key properties of gait. The best PLS-DA model produced a fall classification accuracy of AUC = 0.93. The specificity of the model using patient characteristics was 60% but reached 80% when cognitive and gait outcomes were added. The inclusion of cognition and gait dynamics in fall classification models reduced misclassification. We therefore recommend assessing geriatric patients' fall risk using a multi-factorial approach that incorporates patient characteristics, cognition, and gait dynamics.

  4. Optimization of the cumulative risk assessment of pesticides and biocides using computational techniques: Pilot project

    DEFF Research Database (Denmark)

    Jonsdottir, Svava Osk; Reffstrup, Trine Klein; Petersen, Annette

    This pilot project is intended as the first step in developing a computational strategy to assist in refining methods for higher tier cumulative and aggregate risk assessment of exposure to mixture of pesticides and biocides. For this purpose, physiologically based toxicokinetic (PBTK) models were...

  5. An innovative approach to determine economically optimal coastal setback lines for risk informed coastal zone management

    NARCIS (Netherlands)

    Ranasinghe, R.; Jongejan, R.B.; Callaghan, D.; Vrijling, J.K.

    2012-01-01

    Current methods used to determine Coastal setback lines have several limitations. Furthermore, the historical practice of defining setback lines based on a single deterministic estimate is also proving inadequate with the emergence of risk management style coastal planning frameworks which require

  6. Blackout risk prevention in a smart grid based flexible optimal strategy using Grey Wolf-pattern search algorithms

    International Nuclear Information System (INIS)

    Mahdad, Belkacem; Srairi, K.

    2015-01-01

    Highlights: • A generalized optimal security power system planning strategy for blackout risk prevention is proposed. • A Grey Wolf Optimizer dynamically coordinated with Pattern Search algorithm is proposed. • A useful optimized database dynamically generated considering margin loading stability under severe faults. • The robustness and feasibility of the proposed strategy is validated in the standard IEEE 30 Bus system. • The proposed planning strategy will be useful for power system protection coordination and control. - Abstract: Developing a flexible and reliable power system planning strategy under critical situations is of great importance to experts and industrials to minimize the probability of blackouts occurrence. This paper introduces the first stage of this practical strategy by the application of Grey Wolf Optimizer coordinated with pattern search algorithm for solving the security smart grid power system management under critical situations. The main objective of this proposed planning strategy is to prevent the practical power system against blackout due to the apparition of faults in generating units or important transmission lines. At the first stage the system is pushed to its margin stability limit, the critical loads shedding are selected using voltage stability index. In the second stage the generator control variables, the reactive power of shunt and dynamic compensators are adjusted in coordination with minimization the active and reactive power at critical loads to maintain the system at security state to ensure service continuity. The feasibility and efficiency of the proposed strategy is applied to IEEE 30-Bus test system. Results are promising and prove the practical efficiency of the proposed strategy to ensure system security under critical situations

  7. The safety monitor and RCM workstation as complementary tools in risk based maintenance optimization

    International Nuclear Information System (INIS)

    Rawson, P.D.

    2000-01-01

    Reliability Centred Maintenance (RCM) represents a proven technique for rendering maintenance activities safer, more effective, and less expensive, in terms of systems unavailability and resource management. However, it is believed that RCM can be enhanced by the additional consideration of operational plant risk. This paper discusses how two computer-based tools, i.e., the RCM Workstation and the Safety Monitor, can complement each other in helping to create a living preventive maintenance strategy. (author)

  8. Representing the Fuzzy improved risk graph for determination of optimized safety integrity level in industrial setting

    Directory of Open Access Journals (Sweden)

    Z. Qorbali

    2013-12-01

    .Conclusion: as a result of establishing the presented method, identical levels in conventional risk graph table are replaced with different sublevels that not only increases the accuracy in determining the SIL, but also elucidates the effective factor in improving the safety level and consequently saves time and cost significantly. The proposed technique has been employed to develop the SIL of Tehran Refinery ISOMAX Center. IRG and FIRG results have been compared to clarify the efficacy and importance of the proposed method

  9. Optimizing Screening and Risk Assessment for Suicice in the U. S. Military

    Science.gov (United States)

    2013-09-01

    health care visits, and absenteeism among Iraq War veterans. American Journal of Psychiatry, 164, 150−153. Hoge, C. W., Toboni, H. E., Messer, S. C...among regular-duty military personnel: A retrospective case–control study of occupation-specific risk factors for workplace suicide. American...care visits, and absenteeism among Iraq War veterans. American Journal of Psychiatry, 164, 150- 153. Hoge, C. W., Toboni, H. E., Messer, S. C., Bell

  10. A risk-averse optimization model for trading wind energy in a market environment under uncertainty

    International Nuclear Information System (INIS)

    Pousinho, H.M.I.; Mendes, V.M.F.; Catalao, J.P.S.

    2011-01-01

    In this paper, a stochastic programming approach is proposed for trading wind energy in a market environment under uncertainty. Uncertainty in the energy market prices is the main cause of high volatility of profits achieved by power producers. The volatile and intermittent nature of wind energy represents another source of uncertainty. Hence, each uncertain parameter is modeled by scenarios, where each scenario represents a plausible realization of the uncertain parameters with an associated occurrence probability. Also, an appropriate risk measurement is considered. The proposed approach is applied on a realistic case study, based on a wind farm in Portugal. Finally, conclusions are duly drawn. -- Highlights: → We model uncertainties on energy market prices and wind power production. → A hybrid intelligent approach generates price-wind power scenarios. → Risk aversion is also incorporated in the proposed stochastic programming approach. → A realistic case study, based on a wind farm in Portugal, is provided. → Our approach allows selecting the best solution according to the desired risk exposure level.

  11. Are oil and gas stocks from the Australian market riskier than coal and uranium stocks? Dependence risk analysis and portfolio optimization

    International Nuclear Information System (INIS)

    Arreola Hernandez, Jose

    2014-01-01

    This article models the dependence risk and resource allocation characteristics of two 20-stock coal–uranium and oil–gas sector portfolios from the Australian market in the context of the global financial crisis of 2008–2009. The modeling framework implemented consists of pair vine copulas and, linear and nonlinear portfolio optimization methods with respect to five risk measures. The paper's objectives are to find out if the oil and gas stocks are riskier than the coal and uranium stocks, to identify the optimization method and risk measure that produce the best risk-return trade-off, to recognize the stocks in which the optimal weight allocations converge on average, and to acknowledge the vine copula model that best accounts for the overall dependence of the energy portfolios. The research findings indicate that the oil stocks have higher dependence risk than the coal, uranium and gas stocks in financial crisis periods. The higher risk of the oil stocks is confirmed by the larger concentration of symmetric and asymmetric dependence they have in the negative tail. The canonical vine (c-vine) copula model is observed to better capture the overall dependence of the energy portfolios. The combination of a pair c-vine copula and nonlinear portfolio optimization produces the highest return relative to risk. The optimal weight allocations converge on average in some stocks. - Highlights: • Vine copula dependence modeling of coal, uranium, oil and gas stocks • Oil stocks are riskier than coal, uranium and gas stocks in financial crisis periods. • The c-vine model better captures the overall dependence of the energy portfolios. • Vine copulas and nonlinear optimization combined produce the best results. • The optimal weight allocations converge on average in some stocks

  12. Shared breastfeeding in central Africa

    NARCIS (Netherlands)

    Ramharter, Michael; Chai, Sanders K.; Adegnika, Ayola A.; Klöpfer, Anna; Längin, Matthias; Agnandji, Selidji T.; Oyakhirome, Sunny; Schwarz, Norbert G.; Grobusch, Martin P.; Issifou, Saadon; Kremsner, Peter G.

    2004-01-01

    In this study, shared breastfeeding is described asa novel risk factor for vertical HIV transmission. This cross-sectional survey conducted in the central African country Gabon found that 40% of lactating mothers also breastfed other children than their own, and as many children were additionally

  13. Overview of a benefit/risk ratio optimized for a radiation emitting device used in non-destructive testing

    Energy Technology Data Exchange (ETDEWEB)

    Maharaj, H.P., E-mail: H_P_Maharaj@hc-sc.gc.ca [Health Canada, Dept. of Health, Consumer and Clinical Radiaton Protection Bureau, Ottawa, Ontario (Canada)

    2016-03-15

    This paper aims to provide an overview of an optimized benefit/risk ratio for a radiation emitting device. The device, which is portable, hand-held, and open-beam x-ray tube based, is utilized by a wide variety of industries for purposes of determining elemental or chemical analyses of materials in-situ based on fluorescent x-rays. These analyses do not cause damage or permanent alteration of the test materials and are considered a non-destructive test (NDT). Briefly, the key characteristics, principles of use and radiation hazards associated with the Hay device are presented and discussed. In view of the potential radiation risks, a long term strategy that incorporates risk factors and guiding principles intended to mitigate the radiation risks to the end user was considered and applied. Consequently, an operator certification program was developed on the basis of an International Standards Organization (ISO) standard (ISO 20807:2004) and in collaboration with various stake holders and was implemented by a federal national NDT certification body several years ago. It comprises a written radiation safety examination and hands-on training with the x-ray device. The operator certification program was recently revised and the changes appear beneficial. There is a fivefold increase in operator certification (Levels 1 a nd 2) to date compared with earlier years. Results are favorable and promising. An operational guidance document is available to help mitigate radiation risks. Operator certification in conjunction with the use of the operational guidance document is prudent, and is recommended for end users of the x-ray device. Manufacturers and owners of the x-ray devices will also benefit from the operational guidance document. (author)

  14. Overview of a benefit/risk ratio optimized for a radiation emitting device used in non-destructive testing

    International Nuclear Information System (INIS)

    Maharaj, H.P.

    2016-01-01

    This paper aims to provide an overview of an optimized benefit/risk ratio for a radiation emitting device. The device, which is portable, hand-held, and open-beam x-ray tube based, is utilized by a wide variety of industries for purposes of determining elemental or chemical analyses of materials in-situ based on fluorescent x-rays. These analyses do not cause damage or permanent alteration of the test materials and are considered a non-destructive test (NDT). Briefly, the key characteristics, principles of use and radiation hazards associated with the Hay device are presented and discussed. In view of the potential radiation risks, a long term strategy that incorporates risk factors and guiding principles intended to mitigate the radiation risks to the end user was considered and applied. Consequently, an operator certification program was developed on the basis of an International Standards Organization (ISO) standard (ISO 20807:2004) and in collaboration with various stake holders and was implemented by a federal national NDT certification body several years ago. It comprises a written radiation safety examination and hands-on training with the x-ray device. The operator certification program was recently revised and the changes appear beneficial. There is a fivefold increase in operator certification (Levels 1 a nd 2) to date compared with earlier years. Results are favorable and promising. An operational guidance document is available to help mitigate radiation risks. Operator certification in conjunction with the use of the operational guidance document is prudent, and is recommended for end users of the x-ray device. Manufacturers and owners of the x-ray devices will also benefit from the operational guidance document. (author)

  15. Bed-sharing in the absence of hazardous circumstances: is there a risk of sudden infant death syndrome? An analysis from two case-control studies conducted in the UK.

    Directory of Open Access Journals (Sweden)

    Peter S Blair

    Full Text Available The risk of sudden infant death syndrome (SIDS among infants who co-sleep in the absence of hazardous circumstances is unclear and needs to be quantified.Combined individual-analysis of two population-based case-control studies of SIDS infants and controls comparable for age and time of last sleep.Parents of 400 SIDS infants and 1386 controls provided information from five English health regions between 1993-6 (population: 17.7 million and one of these regions between 2003-6 (population:4.9 million.Over a third of SIDS infants (36% were found co-sleeping with an adult at the time of death compared to 15% of control infants after the reference sleep (multivariate OR = 3.9 [95% CI: 2.7-5.6]. The multivariable risk associated with co-sleeping on a sofa (OR = 18.3 [95% CI: 7.1-47.4] or next to a parent who drank more than two units of alcohol (OR = 18.3 [95% CI: 7.7-43.5] was very high and significant for infants of all ages. The risk associated with co-sleeping next to someone who smoked was significant for infants under 3 months old (OR = 8.9 [95% CI: 5.3-15.1] but not for older infants (OR = 1.4 [95% CI: 0.7-2.8]. The multivariable risk associated with bed-sharing in the absence of these hazards was not significant overall (OR = 1.1 [95% CI: 0.6-2.0], for infants less than 3 months old (OR = 1.6 [95% CI: 0.96-2.7], and was in the direction of protection for older infants (OR = 0.1 [95% CI: 0.01-0.5]. Dummy use was associated with a lower risk of SIDS only among co-sleepers and prone sleeping was a higher risk only among infants sleeping alone.These findings support a public health strategy that underlines specific hazardous co-sleeping environments parents should avoid. Sofa-sharing is not a safe alternative to bed-sharing and bed-sharing should be avoided if parents consume alcohol, smoke or take drugs or if the infant is pre-term.

  16. Assessing the optimism-pessimism debate: Nuclear proliferation, nuclear risks, and theories of state action

    International Nuclear Information System (INIS)

    Busch, Nathan Edward

    2001-01-01

    This dissertation focuses on the current debate in international relations literature over the risks associated with the proliferation of nuclear weapons. On this subject, IR scholars are divided into roughly two schools: proliferation 'optimists,' who argue that proliferation can be beneficial and that its associated hazards are at least surmountable, and proliferation 'pessimists,' who believe the opposite. This debate centers upon a theoretical disagreement about how best to explain and predict the behavior of states. Optimists generally ground their arguments on rational deterrence theory and maintain that nuclear weapons can actually increase stability among states, while pessimists often ground their arguments on 'organization theory,' which contends that organizational, bureaucratic, and other factors prevent states from acting rationally. A major difficulty with the proliferation debate, however, is that both sides tend to advance their respective theoretical positions without adequately supporting them with solid empirical evidence. This dissertation detailed analyses of the nuclear programs in the United States, Russia, China, India, and Pakistan to determine whether countries with nuclear weapons have adequate controls over their nuclear arsenals and tissue material stockpiles (such as highly enriched uranium and plutonium). These case studies identify the strengths and weaknesses of different systems of nuclear controls and help predict what types of controls proliferating states are likely to employ. On the basis of the evidence gathered from these cases, this dissertation concludes that a further spread of nuclear weapons would tend to have seriously negative effects on international stability by increasing risks of accidental, unauthorized, or inadvertent use of nuclear weapons and risks of thefts of fissile materials for use in nuclear or radiological devices by aspiring nuclear states or terrorist groups. (author)

  17. Risk based optimization of technical specifications for operation of nuclear power plants

    International Nuclear Information System (INIS)

    1993-12-01

    The objective of the report is to present an overview of the risk and reliability based approaches (using a probabilistic safety assessment (PSA)) for improving nuclear power plant technical specifications (TS). In that case, it will provide an information base to the Member States in seeking PSA based applications to enhance the effectiveness of their technical specifications. To achieve this objective, the report discusses the basic objectives and reasons for seeking TS changes, the methods, data requirements and uses of different types of applications, and an overview of different applications that have been completed, including detailed descriptions of selected applications. Refs, figs and tabs

  18. «Neutral» Profit Taxation, Risk Taking and Optimal Profit Taxation

    OpenAIRE

    Jack M. MINTZ

    1982-01-01

    The object of this study is to answer two questions related to the design of profit taxes when taking into account riskiness of firms. The first question is the following: leaving aside general equilibrium effects of taxation on the interest rate and risk premia faced by firms, would a cash flow tax be neutral with respect to the investment decisions made by firms. The second question to be considered is whether profit tax rates should vary across industries because of different degrees of ri...

  19. Setting Optimal Bounds on Risk in Asset Allocation - a Convex Program

    Directory of Open Access Journals (Sweden)

    James E. Falk

    2002-10-01

    Full Text Available The 'Portfolio Selection Problem' is traditionally viewed as selecting a mix of investment opportunities that maximizes the expected return subject to a bound on risk. However, in reality, portfolios are made up of a few 'asset classes' that consist of similar opportunities. The asset classes are managed by individual `sub-managers', under guidelines set by an overall portfolio manager. Once a benchmark (the `strategic' allocation has been set, an overall manager may choose to allow the sub-managers some latitude in which opportunities make up the classes. He may choose some overall bound on risk (as measured by the variance and wish to set bounds that constrain the submanagers. Mathematically we show that the problem is equivalent to finding a hyper-rectangle of maximal volume within an ellipsoid. It is a convex program, albeit with potentially a large number of constraints. We suggest a cutting plane algorithm to solve the problem and include computational results on a set of randomly generated problems as well as a real-world problem taken from the literature.

  20. Optimization of carrageenan-based jelly products added with nutrients for reducing osteoporosis risks

    Science.gov (United States)

    Athaillah, Zatil Afrah; Eviana, Irma; Pudjiraharti, Sri; Haryono, Agus

    2017-11-01

    Osteoporosis is a main concern, particularly in aging populations and more specifically in elderly women. Introducing functional foods that contains nutrients that have been scientifically proven to bring beneficial effects for bone metabolism is one of potential mechanism to reduce its prevalence. In this study, optimization of jelly products containing the necessary nutrients was conducted. We investigated the effect of adding skim milk, at particular concentrations, to gelling temperature of the sol, syneresis of the gels, and texture profile of the gels. Furthermore, green tea and ginger extract were added to the formulation and consumer preference on color and taste was analyzed. Our findings demonstrated that no significant difference in gelling temperature and syneresis was found as skim milk concentration was increased from 0.64 to 2.51%. Texture profile analysis data suggested that adding skim milk contributed to increased firmness, toughness, stringiness, and initial stiffness of the gels. In general, panellist could accept both color and taste of green tea and ginger jellies, as the median values were between 6 and 7 in the 9-point rating hedonic scale. These findings suggested that addition of nutrients beneficial for bone health can be conducted to jelly products with good sensory acceptance.